JP6087357B2 - Alumina through-hole membrane and manufacturing method thereof - Google Patents

Description

The present invention, alumina through hole membrane formed from anodized porous alumina is produced by anodic oxidation of aluminum, a manufacturing method thereof.

  Anodized porous alumina obtained by anodizing aluminum in an acidic bath has a hole array structure in which pores of uniform size are arranged, so it is expected to be used in various applications such as filters, catalyst carriers, and template materials. It is a functional material that can be used. Anodized porous alumina is a porous oxide film formed on the surface of an aluminum material by anodizing it in an electrolytic solution using an aluminum material as an electrode, so the formed porous alumina is used as a membrane for filter applications, etc. When you do, it is necessary to peel from the bullion. It is possible to obtain a porous alumina film by chemically dissolving and removing the remaining bullion of the anodized aluminum material. However, since the bullion is dissolved, the remaining bullion is made of anodized porous alumina. Therefore, it is not suitable for a method for producing a high-throughput membrane.

  In addition, as a method of peeling the porous alumina film from the bare metal aluminum, there are several methods including a reverse electrolytic peeling method (Non-patent Document 1) and a method of performing anode electrolysis in an electrolytic polishing liquid (Non-Patent Document 2). This method has been proposed. For example, according to the reverse electrolytic stripping method, it is known that the coating can be stripped by performing anodization under a predetermined condition to form a porous alumina film and then performing reverse electrolysis using an aluminum material as a cathode. . It has also been reported that an oxide film can be peeled off by performing anodization again on an aluminum material on which a desired anodized film is formed in a perchloric acid-based electropolishing liquid. Based on such a technique, since the bare metal after peeling the porous alumina film can be used as a base material for forming the film again, it is possible to efficiently form the porous alumina film. .

  One of the characteristics of anodized porous alumina is that the pores form a regular array in a self-organized manner when anodized under appropriate conditions (Non-patent Document 3). According to the two-step anodizing process in which the oxide film layer formed by anodizing for a long time under appropriate conditions is selectively dissolved and removed, and then anodized again under the same conditions, Porous alumina in which pores are regularly arranged to the bottom of the film can also be obtained (Non-Patent Document 4). This is because a depression array corresponding to the regular pore arrangement at the bottom of the film formed by the first stage of anodic oxidation is formed on the surface of the aluminum metal, and this is the start of pore generation during the second anodic oxidation. This is because it functions as a point. By making use of such characteristics, a porous alumina membrane having a hole array structure in which pores are regularly arranged can be produced.

  However, with the existing porous alumina film peeling method, even if anodization is performed for a long time under appropriate conditions and a regular depression array is formed on the surface of the remaining metal, the regular depression arrangement is performed during the peeling process. There was a problem that the structure collapsed. For this reason, even when anodization is again performed on the aluminum material after the peeling treatment under the same conditions, porous alumina in which pores are regularly arranged from the surface cannot be formed. If it is possible to peel the porous alumina film while maintaining the regular uneven structure formed on the metal surface, it is possible to produce a regular porous alumina membrane repeatedly from one aluminum material continuously. However, such a porous alumina film peeling method has not yet been established.

  Since an anodized porous alumina has an alumina layer called a barrier layer formed at the bottom of the coating, it is essential to remove the barrier layer when used as a through-hole membrane. For removing the barrier layer, a method of physically scraping the alumina layer such as Ar ion milling and a method of chemically dissolving the layer are known. If a technique such as Ar ion milling is used, penetration processing can be performed without enlarging the pore diameter, but there is a problem that it is difficult to apply to a large-area sample due to restrictions on the apparatus size. . On the other hand, the chemical dissolution method can be applied to a large-area sample, but the problem is that the pore diameter increases because the dissolution inside the pore also proceeds during the barrier layer dissolution treatment. There is. This is because the barrier layer is dissolved, the etchant penetrates into the pores, and the dissolution of the pore wall portion proceeds. Usually, the pore diameter of the porous alumina formed by anodization is about 1/3 of the pore period. However, when chemical through-pore treatment is used, the pore diameter is 1/3 or less of the pore period. It is difficult to form a through-hole membrane having pores. If it becomes possible to produce an anodized porous alumina whose barrier layer portion has significantly higher solubility properties than other alumina layers, it is possible to produce a through-hole membrane with a small pore diameter even by a chemical dissolution method. Although it can be expected, a method for producing such an anodized porous alumina film has not been reported so far.

Kazunari Mizuki, Journal of Aluminum Research, 6, 6 (1985) H. H. Yuan, F. Y. He, D. C. Sun, X. H. Xia, Chem. Mater., 16, 1841 (2004) H. Masuda and K. Fukuda, Science, 268, 1466 (1995) H. Masuda and M. Satoh, Jpn. J. Appl. Phys. 35 (1996) 126

  As described above, in the existing method for peeling the anodized porous alumina film formed on the surface of the aluminum material, the concavo-convex structure corresponding to the barrier layer on the back surface of the porous alumina film to be peeled is held on the aluminum metal surface. It was difficult. Further, in the through-hole treatment by chemical dissolution of the barrier layer applicable to a large area sample, it was difficult to obtain a through-hole without enlarging the hole diameter.

Accordingly, an object of the present invention is to provide an anode having a plurality of alumina layers with different solubility, particularly having a highly soluble alumina layer in a portion necessary for through-hole treatment, which can solve these problems described above. It is to make it the alumina through hole membrane made from oxidized porous alumina can be produced without a complicated process.

  The present invention provides a method for peeling a porous alumina membrane while maintaining a regular uneven structure on the surface of the remaining aluminum metal, which has been difficult to realize by a conventional method for producing a porous alumina through-hole membrane. This was completed as a result of intensive studies on a method for obtaining a porous alumina through-hole membrane with a fine pore diameter.

That is, the method for producing an alumina through-hole membrane according to the present invention forms an anodized porous alumina film having a structure in which two or more alumina layers having different solubility are laminated only by anodization of aluminum . Two or more alumina layers having different concentrations are prepared by anodizing in different concentrations or types of acids contained in the electrolyte, and a highly soluble alumina layer is formed with an acid having a concentration of 3M or more. produced by anodic oxidation using an electrolyte solution containing, immersed in etchant anodised porous alumina, by selectively dissolving and removing the high alumina layer of said soluble, pore lower alumina layer having solubility It forms in the through-hole membrane made into the through-hole, and consists of a method characterized by the above-mentioned.

  In such a method, for example, in an anodized porous alumina in which a low-solubility alumina layer is formed on the top of the film and a high-solubility alumina layer is formed on the bottom of the film, the high-solubility alumina layer is preferentially used in the etchant. As a result, an anodized porous alumina membrane having a through hole can be obtained. At this time, if two or more alumina layers having high solubility and alumina layers having low solubility are substantially alternately laminated, a plurality of porous layers having low solubility can be obtained by chemical dissolution treatment in an etchant. It is also possible to obtain an alumina film at once.

  As a method for forming an alumina layer having different solubility by anodic oxidation, a method of changing the type of electrolytic bath used for anodic oxidation is effective. The alumina layer formed by anodization is known to incorporate an anionic component in the electrolyte into the coating, and the solubility of the resulting alumina layer depends on the type and concentration of the anion incorporated in the coating. And change. Therefore, it is possible to form alumina layers with different solubilities by performing anodization in two or more types of electrolytes containing different anion species, or by anodizing in electrolytes with different acid concentrations. Become.

In the present invention, the highly soluble alumina layer is formed by anodic oxidation using an electrolytic solution containing 3 M or more acid or alkali reagent. Furthermore , it is effective to use an electrolytic solution containing an acid or alkali reagent of 8 M or more.

  It is effective to use an electrolytic solution containing one or more of sulfuric acid, oxalic acid, phosphoric acid, and sulfamic acid to form an alumina layer exhibiting high solubility.

  Moreover, when an aluminum material formed on the surface of anodized porous alumina having two or more layers of alumina layers with different solubility prepared as described above is immersed in an etchant, the etchant is introduced into the pores from the sample surface. Intrusions can preferentially dissolve and remove the highly soluble alumina layer, so that a porous alumina through-hole membrane can be obtained without dissolving and removing the metal. At this time, if a plurality of low-solubility porous alumina layers and high-solubility alumina layers are laminated, a plurality of porous alumina through-hole membranes can be obtained from one aluminum material at a time.

  Further, when selectively dissolving and removing the highly soluble alumina layer, an etchant containing an oxidizing agent is used. In particular, an acidic solution containing at least one of chromic acid and nitric acid is used as the etchant containing the oxidizing agent. The use of is one of the preferred forms. When an anodized porous alumina film having a layered structure of alumina layers with different solubility is formed on the surface of aluminum and the highly soluble alumina layer formed at the bottom of the film is dissolved, phosphoric acid or the like is usually used. When the acid solution of is used, when the aluminum ingot is exposed, the acid and aluminum react on the aluminum surface to generate hydrogen. The hydrogen gas generated in this way is trapped at the interface between the porous alumina film and the aluminum base metal, which may cause mechanical stress on the porous alumina film and generate cracks. Such a problem is caused by dissolving a highly soluble alumina layer using an etchant containing an oxidizing agent, particularly an acidic solution having a high oxidizing power (for example, an acidic solution containing at least one of chromic acid and nitric acid described above). It is possible to solve. Etchant containing oxidant, especially acidic solutions with strong oxidizing power such as chromic acid and nitric acid, even when aluminum ingot is exposed, a passive film is formed on the surface, and the reaction between aluminum and acid Does not progress. As a result, generation of hydrogen gas can also be suppressed, so that cracks in the porous alumina film can be suppressed. In a laminated structure in which a low-solubility porous alumina layer is formed on the bottom of a high-solubility alumina layer, even if the high-solubility alumina layer is dissolved and removed, the low-solubility alumina layer remains on the aluminum surface. Therefore, it is possible to prevent the bare metal from being directly exposed to the solution. Also in such a method, it can suppress that a crack enters into the peeled porous alumina film.

  Further, if the end portion of the sample on which the porous alumina is formed is cut in advance, the dissolution proceeds from the side portion, so that a porous alumina through-hole membrane can be obtained efficiently. If a highly soluble alumina layer is formed at the bottom of the film, the aluminum ingot is exposed after the porous alumina film is peeled off by chemical dissolution treatment. It is also possible to repeatedly form anodized porous alumina. In particular, if a highly soluble alumina layer is dissolved using a low-solubility etchant of ingot aluminum, it is possible to retain the depression array corresponding to the pore arrangement of anodized porous alumina on the surface of the remaining ingot. It is. For this reason, a low-solubility alumina layer is prepared by a self-organizing method (for example, non-patent document H. Masuda and K. Fukuda, Science, 268, 1466 (1995)) or a texturing method (for example, non-patent document H. Masuda). , H. Yamada, M. Satoh, H. Asoh, M. Nakao and T. Tamamura: Appl. Phys. Lett. 1997, 71, 2770). If it is possible to maintain a regular arrangement of pores when forming a highly functional alumina layer, a regular dent arrangement structure can be maintained on the surface of the remaining metal after peeling the porous alumina. . If such an aluminum material is anodized again under appropriate conditions, a porous alumina membrane in which pores are regularly arranged from the surface can be repeatedly produced.

  Further, an alumina layer having a low solubility is formed by anodic oxidation in a predetermined specific region of aluminum (for example, in a specific region predetermined by masking), and then the specific region including the specific region Alternatively, a highly soluble alumina layer can be formed by anodizing again over a wide area (for example, a wider area where masking has been removed) to form the anodized porous alumina film. According to the present invention, anodization is performed on aluminum to form a low-solubility alumina layer, and then anodization is performed by changing the electrolytic solution to form a porous alumina layer having a laminated structure. It is possible to produce an alumina through-hole membrane by performing wet etching on the sample, but when performing re-anodization, up to the part where the low-solubility alumina layer is not formed (the above-mentioned wider If a highly soluble alumina layer is formed by immersing in an electrolyte solution (up to the region), a structure in which the alumina through-hole membrane is completely separated from the aluminum material can be obtained only by performing wet etching. Furthermore, an alumina layer with a low solubility is formed only on a portion of the aluminum material by performing anodization in advance by applying a treatment that prevents a portion of the aluminum material from being immersed in the electrolyte using masking or a jig. Then, to the part that has not been anodized by masking and jigs, forming a highly soluble alumina layer, and finally performing wet etching to dissolve and remove the highly soluble alumina layer, It is also possible to more easily peel the alumina through-hole membrane from the aluminum material. By using such a method, it is possible to obtain an alumina through-hole membrane having a desired shape such as a disk shape regardless of the shape of the aluminum material.

  In addition, when the through-hole treatment of the anodized porous alumina is performed by wet etching, the pore diameter increases, but according to the anodized porous alumina having the laminated structure proposed in the present invention, the pore diameter increases. It is also possible to perform through-hole treatment of the film without any problem. Even when etching is performed with a bare metal, it is possible to minimize the enlargement of the pore diameter. However, a highly soluble alumina layer is formed on the bottom of the film by dissolving and removing the aluminum in advance. According to the direct etching method, it is possible to make a through-hole in a shorter time than the case with a bare metal, and as a result, it is possible to minimize the expansion of the pore diameter. .

  In addition, if a highly soluble alumina layer is formed thick on the bottom of the film, for example, if it is formed thicker than an alumina layer with low solubility, when the aluminum metal is melted, the film up to the through-hole treatment is formed. Since it can function as a support layer, it is effective for producing a large-area through-hole membrane or an ultra-thin membrane having a thickness of 100 nm or less.

  Further, in the method according to the present invention, when the pores of the low-solubility alumina layer are subjected to through-hole treatment, it is possible to make only predetermined desired region portions through-holes. That is, when forming a film of anodized porous alumina having a structure in which two or more alumina layers having different solubilities are laminated, a highly soluble alumina layer is formed in advance with respect to a formation region of an alumina layer having low solubility. It is partially formed only in the specified specific region, and after the aluminum ingot is dissolved and removed, it is immersed in an etchant to selectively dissolve and remove the highly soluble alumina layer. This is a technique for forming a through-hole membrane in which only the pores of the low-solubility alumina layer are made through-holes. For example, as a method of forming an alumina layer having high solubility only in a portion to be through-holed, after forming a low-solubility alumina layer, a mask is formed in addition to the portion to be through-holed. A technique of performing anodization can be used. As the mask, a polymer solution or a masking tape that becomes a coating film by drying can be used. It is also effective to apply pore filling to a portion where no through-hole is formed by a barrier type film formed by anodizing in a neutral electrolyte.

  Furthermore, in the present invention, the following method can be adopted as a more specific method. For example, a first alumina layer in which pores are regularly arranged in a self-organized manner is formed by anodic oxidation of aluminum, and the first soluble layer is formed by anodization on the bottom side of the pores of the first alumina layer. Forming a high alumina layer, utilizing the regularly arranged pores of the first highly soluble alumina layer as a starting point of pore generation of the next layer, forming an alumina layer having low solubility by anodic oxidation, On the bottom side of the pores of the low-solubility alumina layer, a second high-solubility alumina layer is formed by anodic oxidation, and the formed anodic porous alumina is immersed in an etchant. It is also possible to employ a technique in which the low-solubility alumina layer is selectively dissolved and removed to form the low-solubility alumina layer on the through-hole membrane having through holes. When regular porous alumina is produced from the sample surface to the bottom by the self-assembly process, a two-step anodizing process is usually essential. This removes the porous alumina layer formed by anodic oxidation for a long time, and uses the regular dent array on the surface of the aluminum ingot formed as a starting point for pore generation during the second anodic oxidation. To do. However, when a more specific method in the present invention as described above is used, after anodizing for a long time under appropriate conditions to form a self-organized regular array of pores, once the solubility is high By forming a thin alumina layer and then forming a porous alumina layer with a desired thickness under conditions that allow formation of a low-solubility alumina layer and immersing it in an etchant, the pores are regular from the surface to the bottom. It is possible to easily produce a sample in which porous alumina arranged in the above is formed on the surface of an aluminum ingot. Finally, after forming a highly soluble alumina layer again and immersing it in an etchant, the low solubility alumina layer can be easily converted into a highly regular through-hole membrane with the desired film thickness by a simple process. Can also be obtained.

  Furthermore, in the method according to the present invention, anodized porous alumina in which pores are regularly arranged in a self-organized manner is formed by anodization, and the anodized porous alumina is selectively dissolved and removed, and the surface after removal is removed. An anodized porous alumina film having a structure in which two or more alumina layers are laminated for manufacturing an alumina through-hole membrane can be formed with higher accuracy by using the arrangement of regular depressions remaining in the substrate. . That is, a first alumina layer in which pores are regularly arranged in a self-organized manner is formed by anodic oxidation of aluminum, and the film of the first alumina layer is selectively dissolved and removed, whereby the pores are formed on the surface. An anodized porous material having a structure in which two or more alumina layers having different solubility by anodization are laminated on an aluminum material in which an array of regular depressions corresponding to the bottom of the material is formed. By forming an alumina film and immersing the anodized porous alumina in an etchant to selectively dissolve and remove the highly soluble alumina layer, the low-solubility alumina layer has a through-hole. This is a technique for forming a hole membrane.

  In this method, when anodizing to form the first alumina layer, after performing the first stage of anodization, at least one of the anodization voltage and the electrolyte concentration is changed to form the second stage. It is also possible to carry out anodic oxidation after the first. In this way, the pores of the first alumina layer can be arranged with higher regularity, and the recesses after the removal of the first alumina layer can be arranged with higher regularity. Therefore, the through holes of the finally obtained alumina through hole membrane can also be arranged with higher regularity.

In the present invention, furthermore, a anodized porous alumina formed by anodic oxidation of aluminum, for the anodic porous alumina solubility of different alumina layer is characterized by having a laminated structure of two or more layers It is also possible to provide .

In the present invention , anodized porous having a structure in which two or more alumina layers having different solubilities are laminated by performing anodization of aluminum in solutions having different concentrations or types of acids contained in the electrolytic solution. It is also possible to provide a method for producing anodized porous alumina, which is characterized by forming alumina .

  The present invention also relates to an alumina through-hole membrane obtained by selectively dissolving and removing a highly soluble alumina layer of anodized porous alumina having a structure in which two or more alumina layers having different solubility are laminated. The present invention also provides an alumina through-hole membrane characterized in that the surface has a structure in which the peripheral portion of the pore is recessed. When anodization is performed in a high-concentration acid or alkaline electrolyte, a large amount of anions in the electrolyte is taken into the alumina film, so that a highly soluble alumina layer is formed. At this time, if anodization is performed in a high concentration electrolyte solution after anodization in a low concentration electrolyte solution, an oval anion uptake distribution as shown in the figure below will be formed, resulting in pores. A highly soluble alumina layer with the same shape is formed on the periphery of the surface, and by selectively dissolving and removing this highly soluble alumina layer by wet etching, the peripheral portion of the pores is recessed on the surface. A structure, for example, a structure in which the periphery of the pore is recessed with respect to the cell boundary portion is formed.

In the present invention, the solubility of different alumina layer is obtained by selectively dissolving and removing the high alumina layer soluble in anodized porous alumina with a laminated structure of two or more layers, the pore period It is also possible to provide an alumina through-hole membrane characterized by having pores having a pore diameter of 1/3 or less of the above. As described above, it is difficult to form a through-hole membrane having pores having a size of 1/3 or less of the pore period by the conventional chemical through-hole forming treatment. The alumina through-hole membrane can be produced by the method according to the invention.

Further, in the present invention , anodized porous alumina having a structure in which two or more alumina layers having different solubilities are laminated is partially only in a specific region predetermined with respect to the region where the low-solubility alumina layer is formed. Only the pores of the low-solubility alumina layer in the specific region obtained by selectively dissolving and removing the formed high-solubility alumina layer are formed as through-holes. An alumina through-hole membrane can also be provided . A method according to the present invention as described above, for example, as a method of forming an alumina layer having high solubility only in a portion to be through-hole formed, after forming a low-solubility alumina layer, a portion to be through-hole formed In addition, an alumina through-hole membrane in which only such a specific region is formed as a through hole can be obtained by a method using a method of forming a mask and performing anodization.

  Thus, according to the present invention, a desired alumina through-hole membrane can be easily obtained without going through complicated steps.

It is a schematic block diagram which shows the manufacturing method of the anodic oxidation porous alumina which concerns on one embodiment of this invention. It is a schematic block diagram which shows the manufacturing method of the alumina through hole membrane which concerns on one embodiment of this invention. It is a schematic block diagram which shows the manufacturing method of the alumina through hole membrane which concerns on another embodiment of this invention. It is a schematic block diagram which shows the manufacturing method of the anodic oxidation porous alumina which concerns on another embodiment of this invention. It is a schematic block diagram which shows the manufacturing method of the alumina through-hole membrane which concerns on another embodiment of this invention. It is a schematic block diagram which shows the manufacturing method of the alumina through-hole membrane which concerns on another embodiment of this invention. It is a schematic block diagram which shows the manufacturing method of the alumina through-hole membrane which concerns on another embodiment of this invention. It is a schematic block diagram which shows the manufacturing method of the alumina through-hole membrane which concerns on another embodiment of this invention. It is a schematic block diagram which shows the manufacturing method of the alumina through-hole membrane which concerns on another embodiment of this invention. It is a figure which shows an example which observed the structure obtained by the method shown in FIG. 9 with the electron microscope.

Hereinafter, with reference to drawings, the manufacturing method of the alumina through-hole membrane of this invention is demonstrated in detail.
FIG. 1 shows a method for producing anodized porous alumina obtained by laminating alumina layers having different solubility obtained in the present invention. Porous alumina in which alumina layers having different solubilities are laminated in the depth direction can be obtained by changing the anodizing conditions and performing the second floor anodizing. For example, two or more alumina layers having different solubility due to anodization of aluminum 1 are prepared by anodizing in solutions having different concentrations or types of acids contained in the electrolytic solution. In the illustrated example, an alumina layer 4 with high solubility is formed on the bottom side of the pores 3 of the alumina layer 2 with low solubility.

  FIG. 2 shows a case where porous etching is performed by immersing anodized porous alumina 5 having a laminated structure of alumina layers 2 and 4 having different solubilities as described above in an etchant with bare metal aluminum 6 and performing wet etching. It shows how the alumina layer is peeled off. At this time, the high-solubility alumina layer 4 is selectively dissolved and removed, and the pores 3 of the low-solubility alumina layer 2 are made through-holes to form alumina through-hole membranes 7 that are peeled off from the bare aluminum 6 Is done.

  FIG. 3 shows a method of forming a plurality of alumina through-hole membranes at a time by producing anodized porous alumina having a laminated structure of three or more layers and performing wet etching. For example, a highly soluble alumina layer is formed by performing anodic oxidation in a solution having a different concentration or type of acid contained in the electrolytic solution with respect to the low-solubility alumina layer 2 formed by anodic oxidation of aluminum 1. Is done. In the illustrated example, an alumina layer 4a having a high solubility, an alumina layer 2a having a low solubility, an alumina layer 4b having a high solubility, an alumina layer 2b having a low solubility, and an alumina layer having a high solubility, in this order from the metal aluminum 6 side. 4c, low-solubility alumina layers 2c are alternately formed. By immersing the whole of the anodized porous alumina in an etchant with the base metal aluminum 6 and performing wet etching, the highly soluble alumina layers 4a, 4b and 4c are dissolved and removed substantially simultaneously. A plurality of alumina through-hole membranes 7a, 7b, 7c are formed at a time.

  FIG. 4 shows a method of forming an anodized porous alumina having a pore arrangement corresponding to a dent pattern on the surface of a bare metal by performing anodization again after performing a peeling treatment. For example, as shown in FIG. 2, wet etching is performed by immersing anodized porous alumina having a laminated structure of alumina layers 2 and 4 having different solubilities in an etchant with a bare aluminum 6. Then, the alumina layer 4 having high solubility is selectively dissolved and removed, and the alumina layer 2 having low solubility is formed as the alumina through-hole membrane 7 and peeled off from the metal aluminum 6. After the peeling, anodic oxidation is performed again with the depression pattern 8 remaining on the surface, thereby forming an anodized porous alumina 9 having a pore arrangement corresponding to the depression pattern 8.

  FIG. 5 shows a method for producing a porous alumina through-hole membrane by performing wet etching after dissolving and removing the metal part. In the illustrated example, as shown in FIG. 1, two or more alumina layers having different solubility due to the anodic oxidation of aluminum 1 are formed in, for example, an anode in a solution having a different concentration or type of acid contained in the electrolytic solution. It is produced by performing oxidation. That is, the highly soluble alumina layer 4 is formed on the bottom side of the pores 3 of the lowly soluble alumina layer 2. After the metal aluminum 6 is dissolved and removed, the alumina layer 4 having high solubility is selectively dissolved and removed, and the pores 3 of the alumina layer 2 having low solubility are made through-holes to produce an alumina through-hole membrane 7.

  FIG. 6 shows a process in which a highly soluble alumina layer is formed thick and used as a support layer. For example, the solubility of the anodized porous alumina 5 formed as shown in FIG. 5 and having a laminated structure of the low-solubility alumina layer 2d and the high-solubility alumina layer 4d after the dissolution and removal of the bare aluminum 6 is performed. A high-alumina layer 4d is formed in a relatively thick layer and functions as a support layer. The alumina layer 4d having high solubility functioning as the support layer is selectively dissolved and removed, and the pores of the alumina layer 2d having low solubility are made through-holes to produce the alumina through-hole membrane 7. Until the high-solubility alumina layer 4d is dissolved and removed, the low-solubility alumina layer 2d is supported by the alumina layer 4d, so that the low-solubility alumina layer 2d itself can retain its form even with a relatively thin layer. Finally, it becomes possible to produce a thin alumina through-hole membrane 7.

  FIG. 7 shows a manufacturing example of an alumina through-hole membrane in which only a predetermined specific region is made a through hole. In the same manner as shown in FIG. 1, a low-solubility alumina layer 2 having pores 3 is formed by anodic oxidation of aluminum 1, and regions other than the predetermined specific region (that is, through holes are formed). For example, a mask 11 is applied to a region which is not desired to be performed, and the solubility of the mask layer 11 on the bottom side of the pores 3 of the alumina layer 2 is low with respect to the region where the mask 11 is not applied by anodic oxidation under conditions different from the above. An alumina through-hole membrane in which only a specific region is partially through-holed by dissolving and removing the mask 11 and the highly soluble alumina layer 12 after the high alumina layer 12 is formed and the bare aluminum 6 is dissolved and removed. 13 can be produced.

  FIG. 8 is a schematic plan view showing an example of a method of forming an alumina through-hole membrane simply by forming a high-solubility alumina layer in a wider area than a low-solubility alumina layer and dissolving and removing the high-solubility alumina layer. It is shown as a diagram. In the example shown in FIG. 8A, an alumina layer 22 having low solubility is formed by anodic oxidation in a predetermined specific region 21 of aluminum 1 (for example, in a specific region 21 predetermined by masking), Thereafter, an area wider than the area 21 is set on the area 23 including the specific area 21 and wider than the specific area 21 (for example, by removing the masking or by applying another masking). 23) to form an alumina layer 24 having high solubility by performing anodic oxidation again, and by removing the alumina layer 24 having high solubility by dissolving and removing the alumina layer 24 having low solubility. The membrane 25 can be easily peeled from the bare aluminum 6. Similarly, in the example shown in FIG. 8B, an alumina layer 27 having a low solubility is formed by anodic oxidation in a predetermined specific region 26 of aluminum 1, and then the specific region including the specific region 26 is formed. An area 28 wider than 26 is anodized again to form an alumina layer 29 with high solubility, and an alumina layer 29 with high solubility is formed by dissolving and removing the alumina layer 29 with high solubility. Further, the alumina through-hole membrane 30 can be easily peeled off from the bare aluminum 6.

  FIG. 9 shows an example of manufacturing an alumina through-hole membrane having a surface structure in which the peripheral portion of the pore is recessed. After forming the low-solubility alumina layer 31 on the surface of the aluminum 1, after forming the high-solubility alumina layer 32, the anodization is performed in the low-concentration electrolytic solution, and then in the high-concentration electrolytic solution. When anodization is performed, the distribution of uptake of the anion as shown in FIG. 9 is obtained, and when the highly soluble alumina layer 32 is dissolved and removed by performing wet etching on the highly soluble alumina layer 32, An alumina through-hole membrane 34 having a structure 33 in which the periphery of the pore 3 is recessed with respect to the cell boundary portion is formed. An example of observing the structure of an alumina through-hole membrane produced by such a method with an electron microscope is shown in FIG. 10 (structure 41 obtained by the method shown in FIG. 9).

Example 1 (Formation of alumina through hole membrane with 100 nm pore period from sample with aluminum ingot)
An aluminum plate having a purity of 99.99% was subjected to an electropolishing treatment in a perchloric acid ethanol mixed solution, and then anodized for 90 minutes under the conditions of a 0.3 M oxalic acid bath, a bath temperature of 17 degrees, and a formation voltage of 40 V. Subsequently, anodization was performed for 8 minutes under the conditions of a 12 M sulfuric acid bath, a bath temperature of 0 ° C., and a formation voltage of 40 V, thereby forming a highly soluble alumina layer at the bottom of the film. The obtained sample was immersed in a 1 wt% phosphoric acid aqueous solution and a bath temperature of 30 ° C. for 30 minutes to remove the highly soluble alumina layer. The etched sample was washed with distilled water and dried, and then the film portion was removed from the bare metal to obtain an alumina through-hole membrane.

Example 2 (Formation of alumina through-hole membrane with 63 nm pore period from sample with aluminum ingot)
An aluminum plate having a purity of 99.99% was subjected to an electropolishing treatment in a perchloric acid ethanol mixed solution, and then anodized for 180 minutes under the conditions of a 0.3 M sulfuric acid bath, a bath temperature of 17 degrees, and a conversion voltage of 25 V. Subsequently, anodic oxidation was carried out for 8 minutes under the conditions of a 12M sulfuric acid bath, a bath temperature of 0 ° C., and a formation voltage of 25 V to form a highly soluble alumina layer at the bottom of the film. The obtained sample was immersed in a 1 wt% phosphoric acid aqueous solution and a bath temperature of 30 ° C. for 30 minutes to remove the highly soluble alumina layer. The etched sample was washed with distilled water and dried, and then the film portion was removed from the bare metal to obtain an alumina through-hole membrane.

Example 3 (Formation of highly regular alumina through-hole membrane with a pore period of 100 nm)
An aluminum plate with a purity of 99.99% was subjected to an electropolishing treatment in a perchloric acid ethanol mixed solution, and then anodized for 5 hours under the conditions of a 0.3M oxalic acid bath, a bath temperature of 17 degrees, and a formation voltage of 40 V. By selectively dissolving and removing the oxide film portion in the chromic acid phosphoric acid mixed solution, an aluminum plate having a regular dent array formed on the surface was obtained. The aluminum plate thus obtained was anodized for 90 minutes under the conditions of a 0.3M oxalic acid bath, a bath temperature of 17 ° C., and a formation voltage of 40V. Subsequently, anodization was performed for 8 minutes under the conditions of a 12 M sulfuric acid bath, a bath temperature of 0 ° C., and a formation voltage of 40 V, thereby forming a highly soluble alumina layer at the bottom of the film. The obtained sample was immersed in a 1 wt% phosphoric acid aqueous solution and a bath temperature of 30 ° C. for 30 minutes to remove the highly soluble alumina layer. After etching, the sample was washed with distilled water and dried, and then the film portion was removed from the bare metal to obtain a porous alumina through-hole membrane.

Example 4 (Repeated formation of highly regular alumina through-hole membrane with a pore period of 100 nm)
An aluminum plate with a purity of 99.99% was subjected to an electropolishing treatment in a perchloric acid ethanol mixed solution, and then anodized for 5 hours under the conditions of a 0.3M oxalic acid bath, a bath temperature of 17 degrees, and a formation voltage of 40 V. By selectively dissolving and removing the oxide film portion in the chromic acid phosphoric acid mixed solution, an aluminum plate having a regular dent array formed on the surface was obtained. The aluminum plate thus obtained was anodized for 90 minutes under the conditions of a 0.3M oxalic acid bath, a bath temperature of 17 ° C., and a formation voltage of 40V. Subsequently, anodization was performed for 8 minutes under the conditions of a 12 M sulfuric acid bath, a bath temperature of 0 ° C., and a formation voltage of 40 V, thereby forming a highly soluble alumina layer at the bottom of the film. The obtained sample was immersed in a 1 wt% phosphoric acid aqueous solution and a bath temperature of 30 ° C. for 30 minutes to remove the highly soluble alumina layer. After etching, the sample was washed with distilled water and dried, and then the film portion was removed from the bare metal to obtain a porous alumina through-hole membrane. Since a regular array of depressions is formed on the surface of the bare metal from which the membrane has been removed, a plate is used for this aluminum, and a 0.3M oxalic acid bath, a bath temperature of 17 degrees, and a formation voltage of 40 V are used again. Anodization was performed for 90 minutes underneath. Subsequently, anodization was performed for 8 minutes under the conditions of a 12 M sulfuric acid bath, a bath temperature of 0 ° C., and a formation voltage of 40 V, thereby forming a highly soluble alumina layer at the bottom of the film. The obtained sample was immersed in a 1 wt% phosphoric acid aqueous solution and a bath temperature of 30 ° C. for 30 minutes to remove the highly soluble alumina layer. The etched sample was washed with distilled water and dried, and then the film portion was removed from the bare metal to obtain an alumina through-hole membrane. Even when such an operation was repeated 5 times, it was possible to produce an alumina through-hole membrane in which pores were regularly arranged from the surface to the bottom.

Example 5 (Batch molding of multiple porous alumina through-hole membranes)
An aluminum plate in which a regular array of depressions was formed by the method described in Example 3 was prepared, and this was anodized for 15 minutes under conditions of a 0.3 M oxalic acid bath, a bath temperature of 17 degrees, and a formation voltage of 40 V. Anodization was performed 5 times each for 8 minutes under the conditions of a sulfuric acid bath, a bath temperature of 0 ° C., and a formation voltage of 40V. The sample thus obtained was immersed in a 1 wt% phosphoric acid aqueous solution and a bath temperature of 30 ° C. for 30 minutes to selectively dissolve and remove the highly soluble alumina layer. Thereafter, the sample was washed with distilled water and dried. It was possible to obtain five through-hole membranes by removing the porous alumina layer from the sample surface.

Example 6 (Formation of ideal array alumina through-hole membrane)
A Ni mold having a structure in which protrusions were regularly arranged with a period of 100 nm was pressed against the surface of an aluminum plate with a purity of 99.99% to form a fine uneven pattern on the surface. The aluminum plate subjected to texturing was anodized for 90 minutes under the conditions of a 0.3M oxalic acid bath, a bath temperature of 17 ° C., and a formation voltage of 40V. Subsequently, anodization was performed for 8 minutes under the conditions of a 12 M sulfuric acid bath, a bath temperature of 0 ° C., and a formation voltage of 40 V, thereby forming a highly soluble alumina layer at the bottom of the film. The obtained sample was immersed in a 1 wt% phosphoric acid aqueous solution and a bath temperature of 30 ° C. for 30 minutes to remove the highly soluble alumina layer. The sample after etching was washed with distilled water and dried, and then the film portion was removed from the base metal to obtain an alumina through-hole membrane with ideally arranged pores.

Example 7 (Formation of 100 nm Periodic Alumina Through Hole Membrane with a Pore Diameter of 30 nm)
An aluminum plate with a purity of 99.99% was subjected to an electropolishing treatment in a perchloric acid ethanol mixed solution, and then anodized for 5 hours under the conditions of a 0.3M oxalic acid bath, a bath temperature of 17 degrees, and a formation voltage of 40 V. By selectively dissolving and removing the oxide film portion in the chromic acid phosphoric acid mixed solution, an aluminum plate having a regular dent array formed on the surface was obtained. The aluminum plate thus obtained was anodized for 15 minutes under the conditions of a 0.3M oxalic acid bath, a bath temperature of 17 ° C., and a formation voltage of 40V. Subsequently, anodization was performed for 8 minutes under the conditions of a 12 M sulfuric acid bath, a bath temperature of 0 ° C., and a formation voltage of 40 V, thereby forming a highly soluble alumina layer at the bottom of the film. The back part of the obtained sample was mechanically shaved to remove the oxide film to expose the bare metal, and immersed in iodine saturated methanol to selectively dissolve and remove the remaining bare metal. After removing the bullion, the sample was immersed in a 1 wt% phosphoric acid aqueous solution at a bath temperature of 30 ° C. for 10 minutes to obtain a 100 nm alumina through-hole membrane with a pore diameter of 30 nm on both the front and back surfaces.

Example 8 (Formation of an alumina through-hole membrane using a highly soluble alumina layer as a support layer)
An aluminum plate with a purity of 99.99% was subjected to an electropolishing treatment in a perchloric acid ethanol mixed solution, and then anodized for 5 hours under the conditions of a 0.3M oxalic acid bath, a bath temperature of 17 degrees, and a formation voltage of 40 V. By selectively dissolving and removing the oxide film portion in the chromic acid phosphoric acid mixed solution, an aluminum plate having a regular dent array formed on the surface was obtained. The aluminum plate thus obtained was anodized for 15 seconds under the conditions of a 0.3M oxalic acid bath, a bath temperature of 17 ° C., and a formation voltage of 40V. Subsequently, anodic oxidation was performed for 15 minutes under the conditions of a 12 M sulfuric acid bath, a bath temperature of 0 ° C., and a formation voltage of 40 V to form a highly soluble alumina layer at the bottom of the film. The back part of the obtained sample was mechanically shaved to remove the oxide film to expose the bare metal, and immersed in iodine saturated methanol to selectively dissolve and remove the remaining bare metal. The thickness of the low-solubility alumina layer was 100 nm, but since a high-solubility alumina layer was formed at 2 μm, it was possible to obtain a film having mechanical strength that can be handled. The sample after removal of the bullion could be made into a 100 nm through-hole membrane by immersing the sample in a 1 wt% phosphoric acid aqueous solution at a bath temperature of 30 ° C. for 10 minutes.

Example 9 (Formation of 200 nm periodic ideal array alumina through-hole membrane)
A Ni mold having a structure in which protrusions were regularly arranged with a period of 200 nm was pressed against the surface of an aluminum plate with a purity of 99.99% to form a fine uneven pattern on the surface. The textured aluminum plate was anodized for 15 minutes under the conditions of a 0.05M oxalic acid bath, a bath temperature of 17 degrees, and a formation voltage of 80V. Subsequently, anodization was carried out for 10 minutes under the conditions of a 14 M sulfuric acid bath, a bath temperature of 0 ° C., and a formation voltage of 80 V to form a highly soluble alumina layer at the bottom of the film. The obtained sample was immersed in a 1 wt% phosphoric acid aqueous solution and a bath temperature of 30 ° C. for 30 minutes to remove the highly soluble alumina layer. The sample after etching was washed with distilled water and dried, and then the film portion was removed from the base metal to obtain an alumina through-hole membrane with ideally arranged pores.

Example 10 (Formation of 45 nm periodic alumina through-hole membrane)
An aluminum plate with a purity of 99.99% was subjected to electropolishing treatment in a perchloric acid ethanol mixed solution, and then anodized for 1 hour under conditions of an 8M sulfuric acid bath, a bath temperature of 17 ° C, and a formation voltage of 25V. By selectively dissolving and removing the film portion in the chromic acid phosphoric acid mixed solution, an aluminum plate having a regular dent array formed on the surface was obtained. The aluminum plate thus obtained was anodized for 2 minutes under the conditions of a 0.3 M sulfuric acid bath, a bath temperature of 17 degrees, and a formation voltage of 18 V. Subsequently, anodization was carried out for 20 minutes under the conditions of a 12M sulfuric acid bath, a bath temperature of 0 ° C., and a conversion voltage of 18 V to form a highly soluble alumina layer at the bottom of the film. The back part of the obtained sample was mechanically shaved to remove the oxide film to expose the bare metal, and immersed in iodine saturated methanol to selectively dissolve and remove the remaining bare metal. The sample after the removal of the bullion was immersed in a 1 wt% phosphoric acid aqueous solution at a bath temperature of 30 ° C. for 10 minutes to obtain a 45 nm alumina through-hole membrane with a pore diameter of 15 nm on both the front and back surfaces.

Example 11 (Formation of highly regular alumina through-hole membrane with a pore period of 100 nm)
An aluminum plate with a purity of 99.99% was electropolished in a perchloric acid ethanol mixed solution, then anodized for 5 hours under the conditions of a 0.3M oxalic acid bath, a bath temperature of 17 degrees, and a formation voltage of 40V. Anodization was performed for 10 minutes under the conditions of 12M sulfuric acid bath, 40V, 0 degree. Next, anodization was performed for 90 minutes under conditions of 0.3M oxalic acid bath, bath temperature of 17 ° C and conversion voltage of 40V, and 12M sulfuric acid bath, bath temperature of 0 ° C and conversion voltage of 40V for 8 minutes. A sample was obtained in which a highly soluble alumina layer under a top layer with poor regularity, a regular porous alumina layer having a desired film thickness, and a highly soluble alumina layer thereunder were further laminated. In this method, it has been confirmed that the regularity of pore arrangement can be maintained even when an alumina layer having high solubility is used as an intermediate layer. The obtained sample was immersed in a 1 wt% phosphoric acid aqueous solution and a bath temperature of 30 ° C. for 30 minutes to remove the highly soluble alumina layer. As a result, a porous alumina through-hole membrane was obtained in which pores were regularly arranged from the surface having the desired film thickness to the bottom.

Example 12 (200 nm periodic alumina through-hole membrane produced by self-assembly process)
An aluminum plate with a purity of 99.99% was subjected to electropolishing treatment in a perchloric acid ethanol mixed solution, and then anodized for 16 hours under the conditions of 0.8M oxalic acid bath, bath temperature of 17 degrees, and formation voltage of 40V. Anodization was performed for 1 hour under the conditions of 0.8 M oxalic acid, bath temperature of 17 ° C. and formation voltage of 80 V. By selectively dissolving and removing the oxide film portion of this sample in a mixed solution of chromic phosphoric acid, an aluminum plate having a regular dent array formed on the surface was obtained. The aluminum plate thus obtained was anodized for 90 minutes under the conditions of a 0.05M oxalic acid bath, a bath temperature of 0 ° C., and a formation voltage of 80V. Subsequently, anodization was performed for 20 minutes under the conditions of a 14 M sulfuric acid bath, a bath temperature of 0 ° C., and a formation voltage of 80 V, thereby forming a highly soluble alumina layer at the bottom of the film. The obtained sample was immersed in a 1 wt% phosphoric acid aqueous solution and a bath temperature of 30 ° C. for 30 minutes to remove the highly soluble alumina layer. The sample after etching was washed with distilled water and dried, and then the film portion was removed from the base metal to obtain an alumina through-hole membrane in which pores were regularly arranged in a cycle of 200 nm in a self-organized manner.

Example 13 (Dissolution removal of highly soluble alumina layer using chromic acid)
An aluminum plate with a purity of 99.99% was subjected to an electropolishing treatment in a perchloric acid ethanol mixed solution, and then anodized for 5 hours under the conditions of a 0.3M oxalic acid bath, a bath temperature of 17 degrees, and a formation voltage of 40 V. By selectively dissolving and removing the oxide film portion in the chromic acid phosphoric acid mixed solution, an aluminum plate having a regular dent array formed on the surface was obtained. The aluminum plate thus obtained was anodized for 90 minutes under the conditions of a 0.3M oxalic acid bath, a bath temperature of 17 ° C., and a formation voltage of 40V. Subsequently, anodic oxidation was performed for 15 minutes under the conditions of a 12 M sulfuric acid bath, a bath temperature of 0 ° C., and a formation voltage of 40 V to form a highly soluble alumina layer at the bottom of the film. The obtained sample was immersed in a mixed aqueous solution of 1.8 wt% chromic acid and 6 wt% phosphoric acid and a bath temperature of 30 ° C. for 15 minutes to remove the highly soluble alumina layer. The etched sample was washed with distilled water and dried, and then the alumina layer at the edge of the three sides was peeled off with scotch tape to remove the porous alumina through-hole membrane from the bare aluminum. Porous alumina with a regular pore arrangement is retained on the surface of the aluminum plate from which the porous alumina through-hole membrane has been peeled off. By re-anodizing the remaining metal, regularity with a high aspect ratio is achieved. It was possible to obtain a porous alumina membrane.

Example 14 (Suppression of hydrogen gas generation during dissolution and removal of a highly soluble alumina layer)
The aluminum plate was anodized for 90 minutes under conditions of a 0.3M oxalic acid bath, a bath temperature of 17 ° C., and a formation voltage of 40V. Subsequently, anodization was performed for 15 minutes under conditions of a 12M sulfuric acid bath, a bath temperature of 0 ° C, and a formation voltage of 40V, and a highly soluble alumina layer was formed on the bottom of the film, and then again a 0.3M oxalic acid bath and bath Anodization was performed for 5 minutes under conditions of a temperature of 17 degrees and a conversion voltage of 40V. The obtained sample was immersed in a mixed aqueous solution of 5 wt% phosphoric acid and a bath temperature of 30 ° C. for 15 minutes to remove the highly soluble alumina layer. The etched sample was washed with distilled water and dried, and then the alumina layer at the edge of the three sides was peeled off with a scotch tape to remove the porous alumina through-hole membrane from the substrate.

  The alumina through-hole membrane according to the present invention can be applied as a highly regular porous material, as a material for various functional devices in various applications such as various filter materials.

1 Aluminum 2, 2a, 2b, 2c, 2d, 22, 27, 31 Alumina layer with low solubility 3 Pore 4, 4a, 4b, 4c, 4d, 24, 29, 32 Alumina layer with high solubility 5 Anodization Porous alumina 6 Metal ingot 7, 7a, 7b, 7c, 25, 30, 34 Alumina through-hole membrane 8 Depression array 9 Anodized porous alumina 11 Mask 12 Highly soluble alumina layer 13 Alumina through-hole membrane 21, 26 Predetermined Specific regions 23 and 28 Regions wider than specific regions 33 Structures in which pore peripheral portions are recessed 41 Structures obtained by the method shown in FIG.

Claims (15)

An anodized porous alumina film having a structure in which two or more alumina layers having different solubility are laminated only by anodization of aluminum is formed, and the two or more alumina layers having different solubility are included in the electrolyte. Anodization is performed by performing anodization in solutions having different acid concentrations or types, and a highly soluble alumina layer is prepared by anodization using an electrolyte containing an acid having a concentration of 3M or more. immersing the porous alumina etchant, by selectively dissolving and removing the high alumina layer of said soluble, pore lower alumina layer having solubility and characterized by forming a through hole membrane is penetrated Anaka A method for producing an alumina through-hole membrane. The method for producing an alumina through-hole membrane according to claim 1 , wherein the highly soluble alumina layer is formed using one or more of sulfuric acid, oxalic acid, phosphoric acid, and sulfamic acid. The high-solubility alumina layer is selectively dissolved and removed, and when forming a low-solubility alumina layer on the through-hole membrane, anodized porous alumina is immersed in an etchant without dissolving and removing the aluminum base metal. The method for producing an alumina through-hole membrane according to claim 1 or 2 . It has a laminated structure in which an alumina layer having low solubility, an alumina layer having high solubility on the bottom side of the alumina layer having low solubility, and an alumina layer having low solubility on the bottom side of the alumina layer having high solubility are formed. By forming a film of anodized porous alumina and immersing the anodized porous alumina in an etchant to selectively dissolve and remove the highly soluble alumina layer, a peeled through layer made of an alumina layer having low solubility is removed. The manufacturing method of the alumina through-hole membrane in any one of Claims 1-3 which obtains the hole metal and the aluminum ingot in which the low-solubility alumina layer was formed in the surface. The method for producing an alumina through-hole membrane according to any one of claims 1 to 3 , wherein an etchant containing an oxidizing agent is used when the alumina layer having high solubility is selectively dissolved and removed. The method for producing an alumina through-hole membrane according to claim 5 , wherein an acidic solution containing at least one of chromic acid and nitric acid is used as the etchant containing the oxidizing agent. The anodized porous alumina film is peeled off from an aluminum base metal, and an alumina layer having different solubility by repeated anodic oxidation is utilized by using a hollow array corresponding to the pore array at the bottom of the film remaining on the base metal surface after the peeling. There is formed a film of anodized porous alumina with a stacked or two-layer structure, a manufacturing method of alumina through hole membrane according to any one of claims 1-6. Highly soluble by forming an alumina layer having a low solubility in a predetermined specific region of aluminum by anodic oxidation, and then performing anodization again on a region wider than the specific region including the specific region The method for producing an alumina through-hole membrane according to any one of claims 1 to 7 , wherein an alumina layer is formed to form a film of the anodized porous alumina. An anodized porous alumina film having a structure in which two or more alumina layers having different solubilities are laminated is formed, an aluminum base metal is dissolved and removed, and then immersed in an etchant to select a highly soluble alumina layer. method for producing alumina through hole membrane according to dissolving removed, according to claim 1 or 2. The alumina through hole according to claim 9 , wherein the highly soluble alumina layer is formed to be thicker than the lowly soluble alumina layer, and is used as a support layer for an anodized porous alumina film after dissolution of an aluminum ingot. Membrane manufacturing method. In forming an anodized porous alumina film having a structure in which two or more alumina layers having different solubilities are laminated, a highly soluble alumina layer is determined in advance with respect to the formation region of the low-solubility alumina layer. It is partially formed only in a specific region, and after dissolving and removing the aluminum ingot, it is immersed in an etchant to selectively dissolve and remove the highly soluble alumina layer, thereby dissolving the specific region. The manufacturing method of the alumina through-hole membrane in any one of Claim 1 , 2 , 5-10 which forms the through-hole membrane by which only the pore of the low alumina layer was made into the through-hole. A first alumina layer in which pores are regularly arranged in a self-organized manner is formed by anodization of aluminum, and a first highly soluble alumina by anodization is formed on the bottom side of the pores of the first alumina layer. Forming a layer, using the regularly arranged pores of the first highly soluble alumina layer as a starting point for generating pores in the next layer, forming an alumina layer having low solubility by anodic oxidation, and A second high-solubility alumina layer is formed by anodic oxidation on the bottom side of the pores of the low-porosity alumina layer, and the formed anodic porous alumina is immersed in an etchant, and the first and second dissolutions are performed. The alumina according to any one of claims 1 to 11 , wherein the low-solubility alumina layer is formed on a through-hole membrane having pores formed by selectively dissolving and removing a high-solubility alumina layer. Through hole Membrane manufacturing method. A first alumina layer in which pores are regularly arranged in a self-organized manner is formed by anodic oxidation of aluminum, and a film of the first alumina layer is selectively dissolved and removed, whereby a bottom portion of the pores is formed on the surface. Of anodized porous alumina having a structure in which two or more alumina layers having different solubility properties are laminated by anodizing the aluminum material. A through-hole membrane in which pores are formed in the low-solubility alumina layer by forming a film, immersing the anodized porous alumina in an etchant, and selectively dissolving and removing the high-solubility alumina layer formed, the manufacturing method of alumina through hole membrane according to any one of claims 1 to 11. When anodizing to form the first alumina layer, after anodizing the first stage, change at least one of the anodizing voltage and the electrolyte concentration to change the anodizing after the second stage. The manufacturing method of the alumina through-hole membrane of Claim 13 which implements.   An alumina through-hole membrane obtained by selectively dissolving and removing a highly soluble alumina layer of an anodized porous alumina having a structure in which two or more layers of alumina layers having different solubility are laminated. , Alumina through-hole membrane characterized by having a structure in which the peripheral part of the pore is recessed.

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