WO2020059728A1

WO2020059728A1 - Aluminum member and manufacturing method for same

Info

Publication number: WO2020059728A1
Application number: PCT/JP2019/036453
Authority: WO
Inventors: 裕太清水; 修平榎
Original assignee: 日本軽金属株式会社
Priority date: 2018-09-19
Filing date: 2019-09-18
Publication date: 2020-03-26
Also published as: CN112739855B; JP2023085311A; JP7306405B2; CN117258542A; CN112739855A; JPWO2020059728A1

Abstract

An aluminum member 100 is provided with a porous layer 40 that includes a base material 11 made of metallic aluminum and a coating 12 that contains aluminum oxide and covers a surface of the base material 11. The coating 12 has a thickness of 5-1000 nm, and a plurality of recesses 13 and/or protrusions 14 are formed on the surface of the coating 12, the recesses 13 having a depth of 10-100 nm and the protrusions 14 having a height of 10-100 nm. The porous layer 40 has a plurality of holes 15 having an average pore diameter of 0.1 to 10 μm.

Description

Aluminum member and method of manufacturing the same

The present invention relates to an aluminum member and a method for manufacturing the same.

Conventionally, a test kit using immunochromatography has been known as an in vitro diagnostic drug for quickly and easily testing for infections such as influenza virus. This test kit is, for example, a sample collected from a living body is dropped at a predetermined position and is positive when both the test line and the control line can be visually confirmed, and only the control line can be visually confirmed. If it is, it indicates a negative.

The test kit includes a nitrocellulose membrane filter as a developing member for developing a sample, as shown in Patent Document 1, for example. The collected sample flows through the membrane filter by capillary action and is developed to a test line and a control line.

JP-A-2003-344406

Nitrocellulose membrane filters generally have high whiteness, so it is relatively easy to visually check the test line and control line, and they are used in many test kits.

However, nitrocellulose membrane filters tend to have non-uniform pore sizes and non-uniform thicknesses depending on the date of production, production location, production lot, and the like, and tend to have large variations in quality. If such a variation in quality is large, the flow velocity of the liquid flowing due to the capillary phenomenon is likely to be non-uniform, which may adversely affect the inspection result.

ニトロ In addition, nitrocellulose membrane filters generally have poor storage stability. Therefore, there is a demand for a deployment member that replaces the nitrocellulose membrane filter and has high whiteness and preservability.

The present invention has been made in view of such problems of the conventional technology. An object of the present invention is to provide an aluminum member having high whiteness and high water absorption performance, and a method for manufacturing the same.

アルミニウム The aluminum member according to the aspect of the present invention includes a porous layer including a base material made of metallic aluminum, and a coating containing aluminum oxide covering the surface of the base material. The film has a thickness of 5 nm to 1000 nm, and the film has at least one of a plurality of concave portions and a plurality of convex portions formed on the surface. The depth of each concave portion included in the plurality of concave portions is 10 nm to 100 nm, and the height of each convex portion included in the plurality of convex portions is 10 nm to 100 nm. The porous layer has a plurality of pores, and the plurality of pores have an average pore diameter of 0.1 μm to 10 μm.

The method for manufacturing an aluminum member according to an aspect of the present invention includes a film forming step of anodizing an aluminum plate having a porous structure and forming a film containing aluminum oxide on the aluminum plate. The method for manufacturing an aluminum member includes a depolarizing step of depolarizing the aluminum plate on which the film is formed and removing a part of the surface of the film. The film forming step and the depolarizing step are alternately repeated. The aluminum plate is made of metal aluminum.

FIG. 1 is a schematic cross-sectional view illustrating a tertiary rough surface structure of a porous layer in which a part of the porous layer according to the present embodiment is enlarged. FIG. 2 is a schematic cross-sectional view showing a primary rough surface structure and a secondary rough surface structure of a porous layer in which a portion surrounded by a frame in FIG. 1 is enlarged. FIG. 3 is a schematic cross-sectional view showing another example of the primary roughened surface structure and the secondary roughened surface structure of the porous layer. FIG. 4 is a schematic cross-sectional view showing another example of the primary roughened surface structure and the secondary roughened surface structure of the porous layer. FIG. 5 is a cross-sectional view illustrating an example of the aluminum member according to the present embodiment. FIG. 6 is a perspective view showing an example of an inspection kit using the aluminum member according to the present embodiment. FIG. 7 is a photograph obtained by observing the surface of the aluminum plate after etching with a scanning electron microscope (SEM). FIG. 8 is a photograph of the surface of the aluminum member according to Example 3 observed with a scanning electron microscope. FIG. 9 is a photograph of the surface of the aluminum member according to Example 10 observed with a scanning electron microscope. FIG. 10 is a photograph obtained by observing the surface of the aluminum member according to Comparative Example 3 with a scanning electron microscope.

Hereinafter, the aluminum member according to the present embodiment and a method for manufacturing the same will be described in detail with reference to the drawings. The present invention is not limited only to the following embodiments. In addition, some or all of the components in the embodiments can be appropriately combined. Note that the dimensional ratios in the drawings are exaggerated for the sake of explanation, and may differ from the actual ratios.

[Aluminum member]
In the present embodiment, it was examined whether an aluminum member having a porous structure could be used as a substitute for a nitrocellulose membrane filter. However, it is generally considered that it is difficult for an aluminum member to exhibit a capillary phenomenon that can be applied to immunochromatography. In addition, the aluminum member is usually gray, and it is difficult to confirm the coloring of the test line and the control line.

However, it was found that the aluminum member according to the present embodiment described in detail below has high whiteness and high water wicking performance. Such an aluminum member is expected to be useful not only as a substitute for a nitrocellulose membrane filter but also for various uses.

FIG. 1 is a schematic cross-sectional view in which a part of the porous layer 40 according to the present embodiment is enlarged. 2 to 4 are schematic cross-sectional views showing the primary roughened surface structure 10 and the secondary roughened surface structure 20 of the porous layer 40 in which a portion surrounded by the frame in FIG. 1 is enlarged. As shown in FIG. 1, the aluminum member 100 according to the present embodiment includes a porous layer 40. Further, as shown in FIGS. 2 to 4, the porous layer 40 includes a base material 11 and a film 12. In the porous layer 40, the coating 12 is in contact with the base material 11, and the coating 12 is disposed on the outer surface of the aluminum member 100. The coating 12 has at least one of a concave portion 13 (first concave portion) and a convex portion 14 (first convex portion) on the surface. The porous layer 40 has a plurality of holes 15.

<Rough surface structure>
Aluminum member 100 has a rough surface structure on its surface. The rough surface structure refers to a surface structure having a plurality of irregularities on the surface so that the surface is rougher than a smooth surface. Preferably, the rough surface structure refers to a structure in which at least one of the concave portion 13 and the convex portion 14 is dispersed on the surface of the aluminum member 100. It is preferable that no needle-like or plate-like uneven structure is arranged on the rough surface structure on the surface of the aluminum member 100. The rough surface structure of the aluminum member 100 can be represented by the primary rough surface structure 10, the secondary rough surface structure 20, and the tertiary rough surface structure 30 in the order of increasing the surface roughness scale. That is, the scale of the surface roughness of the secondary rough structure 20 is larger than the scale of the surface roughness of the primary rough structure 10, and the scale of the surface roughness of the tertiary rough structure 30 is larger than the surface roughness of the secondary rough structure 20. Greater than the degree scale. As described later, it is presumed that the aluminum member 100 has a primary roughened surface structure 10, a secondary roughened surface structure 20, and a tertiary roughened surface structure 30 to increase whiteness.

As shown in FIGS. 2 to 4, the primary roughened surface structure 10 has a fine structure formed by the film 12 and at least one of the plurality of concave portions 13 and the plurality of convex portions 14 existing on the surface of the film 12. It has a rough surface structure. The primary rough surface structure 10 is formed on the surface of the coating 12. The primary rough surface structure 10 has a surface roughness scale on the order of several nm to several hundred nm.

～ As shown in FIGS. 2 to 4, the secondary rough surface structure 20 is a rough surface structure formed by the base material 11 and the plurality of holes 15 in the porous layer 40. That is, the secondary rough surface structure 20 is formed by the convex portions 21 (second convex portions, projecting portions) and the concave portions 22 (second concave portions, indentations). The protrusion 21 is formed by the base material 11 and the coating 12 and protrudes toward the outside of the porous layer 40. The recess 22 is formed by the base material 11 and the coating 12, and is recessed toward the inside of the porous layer 40. The holes 15 are formed by the internal space of the porous layer 40 surrounded by the base material 11 and the coating 12 that form the concave portions 22. In other words, the secondary rough surface structure 20 is formed on the surface of the aluminum member 100 by the base material 11 and the coating 12 itself. The secondary rough surface structure 20 has a surface roughness scale on the order of several hundred nm to several tens of μm.

Thus, the porous layer 40 is a porous body having the pores 15 communicating with the outside inside. At this time, the holes 15 are surrounded by the coating 12. That is, the concave portions 13 and the convex portions 14 of the primary rough surface structure 10 are formed in the coating 12 on the surface of the porous layer 40, whereas the holes 15 of the secondary rough surface structure 20 It is formed by being surrounded by a base material 11 and a film 12 covering the surface thereof. The holes 15 forming one cell structure surrounded by the coating 12 may communicate with the holes 15 forming another cell structure. Specifically, the porous layer 40 may have an open cell type structure. The holes 15 may penetrate from one surface of the porous layer 40 to the other surface, or may not penetrate.

よう As shown in FIG. 1, the tertiary rough surface structure 30 is constituted by the outer surface of the porous layer 40. The tertiary rough surface structure 30 is a coarse rough surface structure formed by collecting a plurality of irregularities due to the primary rough surface structure 10 and the secondary rough surface structure 20. The tertiary rough surface structure 30 is an aggregate including a set of the primary rough surface structure 10 and the secondary rough surface structure 20 on the surface of the aluminum member 100. As will be described later, the tertiary rough surface structure 30 has an uneven structure composed of an aggregate of the primary rough surface structure 10 and the secondary rough surface structure 20 by repeating the film forming step and the depolarizing step after the etching step. It is formed by developing. The tertiary rough surface structure 30 is a structure having a surface roughness scale on the order of several tens of μm to several hundred μm.

凹凸 As shown in FIG. 1, an uneven structure is formed on the surface of the aluminum member 100 by the tertiary rough surface structure 30 including an aggregate of the primary rough surface structure 10 and the secondary rough surface structure 20. Specifically, the tertiary roughened surface structure 30 is formed by an aggregate of the primary roughened surface structure 10 and the secondary roughened surface structure 20, and includes a convex portion 31 (third convex portion and a mountain portion) and a concave portion 32 (third concave portion). , Valleys) are formed. The protrusion 31 rises like a mountain with respect to the thickness direction of the surface of the aluminum member 100, and the recess 32 falls like a valley with respect to the thickness direction of the surface of the aluminum member 100. When the convex portions 31 and the concave portions 32 appear repeatedly at intervals, the tertiary rough surface structure 30 has a periodic valley structure with a larger scale than the primary rough surface structure 10 and the secondary rough surface structure 20. have.

周期 The period of the tertiary rough surface structure 30 is preferably 10 μm to 500 μm, more preferably 30 μm to 200 μm. The period of the tertiary rough surface structure 30 refers to, in the planar direction of the aluminum member 100, the convex portions 31 that periodically appear adjacent to each other across the concave portion 32 or the concave portions that periodically appear adjacent to each other across the convex portion 31. 32. When the period of the tertiary rough surface structure 30 is in such a range, the aluminum member 100 having better whiteness can be provided. The period of the tertiary rough surface structure 30 can be measured by observing the cross section of the aluminum member 100 with an optical microscope or the like.

(4) Since the aluminum member 100 has the tertiary rough surface structure 30 as described above, the glossiness of the surface is reduced and the matte feeling is improved. Thereby, the gloss generated on the surface of the aluminum member 100 is suppressed, and the visibility of information such as colors, patterns, figures, symbols, and characters presented on the aluminum member 100 is improved. Such improvement in visibility is effective, for example, when the aluminum member 100 is used as a test sheet or a developing member for chromatography, and the test results generated on the aluminum member 100 are visually or optically confirmed.

<Base material>
The base material 11 is made of metal aluminum. The metallic aluminum constituting the base material 11 is preferably pure aluminum having a purity of 99% or more, more preferably pure aluminum having a purity of 99.9% or more, and pure metal having a purity of 99.98% or more. More preferably, it is aluminum.

The base material 11 may contain unavoidable impurities. In the present embodiment, the unavoidable impurities mean those which are present in the raw material or unavoidably mixed in the manufacturing process. The unavoidable impurities are originally unnecessary, but are trace amounts and do not affect the properties in aluminum, and are thus allowed impurities. Inevitable impurities that may be contained in aluminum are elements other than aluminum (Al). As inevitable impurities that may be contained in aluminum, for example, magnesium (Mg), iron (Fe), silicon (Si), copper (Cu), lead (Pb), manganese (Mn), chromium (Cr) ), Zinc (Zn), titanium (Ti), gallium (Ga), boron (B), vanadium (V), zirconium (Zr), calcium (Ca), cobalt (Co), and the like. The amount of the inevitable impurities is preferably 1% by mass or less in total in aluminum, more preferably 0.1% by mass or less, and even more preferably 0.02% by mass or less.

形状 The shape of the base material 11 is not particularly limited, and may be porous, tree-like, fibrous, massive, spongy, or the like.

<Coating>
The coating 12 covers the surface of the base material 11. More specifically, the coating 12 is in contact with the surface of the base material 11 and the pores 15 to suppress the base material 11 from being corroded.

The film 12 contains aluminum oxide. In the present embodiment, the film 12 is an anodic oxide film, and the anodic oxide film is preferably a barrier type anodic oxide film. Further, the film 12 may include aluminum hydroxide. The film 12 may have a hydrated film containing aluminum hydroxide.

For example, the coating 12 may be formed by laminating an anodized film and a hydrated film in this order from the base material 11 side, but the surface side of the anodized film covering the surface of the base material 11 may be used. It is preferable that a hydration film is provided on a part of the film. Alternatively, the coating 12 may be one in which the anodized film and the hydrated film are distributed in a sea-island shape on the surface of the base material 11, but the anodized film is distributed in the sea shape on the surface of the base material 11. Preferably, the hydrated film is distributed in an island shape. Specifically, the ratio of the hydrated film to the entire outer surface of the film 12 is preferably 5% or more and 50% or less, more preferably 10% or more and 40% or less, and 15% or more and 30% or less. Is more preferable. When the coating 12 contains aluminum hydroxide and aluminum hydroxide is present on a part of the outermost surfaces of the base material 11 and the porous layer 40, it is preferable that the aluminum hydroxide forms the projections 14.

It is preferable that the porous layer 40 according to the present embodiment does not include a hydrated film covering the base material 11 and the porous layer 40 over the entire outermost surface. Since the porous layer 40 does not include a hydrated film on the entire outermost surface, diffuse reflection becomes superior, and the whiteness of the aluminum member 100 can be further improved. Aluminum hydroxide is represented by the general formula Al (OH) ₃ .

(4) When the outermost surface of the coating 12 is covered with a needle-like or plate-like hydrated coating, the aluminum member 100 may be observed in black or gray. This is because such a hydrated film has a sharp tip shape in the vicinity of the surface, and although this tip portion contributes to diffuse reflection of incident light, the portion that can diffusely reflect is formed at the tip portion. It is considered that the effect is limited by the area. In addition, such a coating has an internal shape in which the space between adjacent needle-like or plate-like hydration coatings gradually narrows from the tip to the base. Therefore, the incident light that has entered the interior is absorbed by the hydrated film while repeating reflection, and the fact that the light is not easily emitted to the outside also affects that the aluminum member 100 is observed in black or gray. it is conceivable that.

Furthermore, if the hydrated film is present, the primary roughened structure 10 and the secondary roughened structure 20 are often clogged, so that the appearance of the aluminum member 100 tends to be black or gray. Therefore, it is preferable that the film 12 made of the anodic oxide film is provided on the surface of the porous layer 40, and the concave portions 13 and the holes 15 exist on the outermost surface of the film 12. On the other hand, the aluminum hydroxide covers the entire outermost surface of the porous layer 40 and does not form a hydrated film. In this case, the whiteness can be improved by the convex portions 14. Further, the whiteness can be improved by the convex portions 14 and the concave portions 13 exposed on the outermost surface of the porous layer 40 without being covered with the hydrated film. Further, when aluminum hydroxide covers the entire outermost surface of the porous layer 40 to form a hydrated film, and when the aluminum oxide exists in the outermost surface of the porous layer 40 in the form of granules or lump to form the projections 14, The whiteness can be improved by the convex portions 14.

The film 12 usually has a thickness of 5 nm to 1000 nm. The thickness of the film 12 is preferably from 20 nm to 800 nm, more preferably from 30 nm to 500 nm, and still more preferably from 50 nm to 300 nm. By setting the thickness of the coating 12 to such a range, it is easy to secure a sufficient thickness to diffusely reflect light incident on the porous layer 40, and to provide the aluminum member 100 having better whiteness. can do. Further, the aluminum member 100 having sufficiently high corrosion resistance can be provided. The thickness of the film 12 can be measured, for example, by observing the cross section of the film 12 with a scanning electron microscope or the like. In the present specification, the thickness of the coating 12 means a thickness not including the concave portions 13 and the convex portions 14.

The coating 12 has at least one of the plurality of concave portions 13 and the plurality of convex portions 14 formed on the surface. Specifically, as shown in FIG. 2, the film 12 may have a plurality of recesses 13 on the surface of the film 12. Alternatively, as shown in FIG. 3, the film 12 may have a plurality of convex portions 14 on the surface of the film 12. Alternatively, as shown in FIG. 4, the film 12 may have a concave portion 13 and a convex portion 14 on the surface of the film 12. That is, the film 12 may have either the concave portion 13 or the convex portion 14, or may have both the concave portion 13 and the convex portion 14. The presence or absence of the concave portion 13 or the convex portion 14 can be determined by observing the surface of the coating 12 with a scanning electron microscope or the like.

The concave portion 13 and the convex portion 14 contribute to the whiteness of the aluminum member 100. The reason why the whiteness of the aluminum member 100 is improved by forming at least one of the concave portion 13 and the convex portion 14 on the surface of the film 12 is not necessarily clear, but is presumed as follows. First, when light enters the aluminum member, the incident light is reflected on the surface of the aluminum member. At this time, if the surface of the aluminum member is smooth, the aluminum member has a mirror-like gloss. Here, when there are minute irregularities on the surface of the aluminum member, diffuse reflection of the incident light occurs due to the irregularities, but there are usually no irregularities that are visible in white.

On the other hand, in the aluminum member 100 according to the present embodiment, the diffuse reflection on the surface of the coating 12 can be increased by the concave portions 13 and the convex portions 14. That is, when the film 12 has the concave portion 13, the area in which the incident light can be diffusely reflected is increased by the concave portion 13, so that the aluminum member 100 is observed to be white. Similarly, when the coating 12 has the convex portions 14, the area where the incident light can be diffusely reflected is increased by the convex portions 14, so that the aluminum member 100 is observed to show white.

(4) The recess 13 is preferably formed so as to be depressed from the exposed surface of the coating 12 toward the base material 11. It is preferable that the bottom of the recess 13 does not penetrate to the base material 11, and the coating 12 is formed between the recess 13 and the base material 11. The shape of the concave portion 13 is not particularly limited, but is preferably substantially U-shaped or substantially V-shaped in cross section in the laminating direction of the base material 11 and the film 12 (the thickness direction of the film 12). As will be described later, the anodized and depolarized aluminum plate is etched to form a film 12 made of an anodized film on the surface of the base material 11. The recess 13 is formed in this anodic oxide film. It is preferable that the convex portion 14 is formed to protrude outward from the exposed surface of the film 12. The shape of the convex portion 14 is not particularly limited, but is preferably granular or massive.

径 The diameter of each recess 13 included in the plurality of recesses is preferably 10 nm to 200 nm, more preferably 20 nm to 150 nm, and even more preferably 50 nm to 100 nm. Further, the diameter of each protrusion 14 included in the plurality of protrusions is preferably from 10 nm to 200 nm, more preferably from 20 nm to 150 nm, and further preferably from 50 nm to 100 nm. By setting the diameter of the concave portion 13 and the convex portion 14 in such a range, the light incident on the porous layer 40 can be easily diffused and reflected by the concave portion 13 and the convex portion 14, and the aluminum member 100 having a better whiteness can be obtained. Can be provided. The diameter of the recess 13 can be obtained by observing the surface of the coating 12 with a scanning electron microscope or the like and measuring the diameter of the entrance of the recess 13. The diameter of the protrusion 14 can be obtained by observing the surface of the coating 12 with a scanning electron microscope or the like and measuring the diameter of the portion where the diameter of the protrusion 14 is largest.

Here, the recognition of the recess 13 and its diameter when the plurality of recesses 13 are close to each other will be described. First, the position of the concave portion 13 is determined by the deepest position of the concave portion 13 (the peak position on the bottom side). The interval between adjacent recesses 13 can be determined by the distance between the peak positions on the bottom side of each recess 13. If a certain recess 13 is present at a distance of 50 nm or more from the surrounding recess 13, the recess 13 is regarded as an independent recess 13. On the other hand, a case where a plurality of recesses 13 are gathered at intervals of less than 50 nm, and a group is formed at intervals of 50 nm or more from surrounding recesses 13 not included in the group. In this case, this group is regarded as one recess 13. Then, the diameter of the entire group is measured as the diameter of the recess 13. In addition, when the plurality of recesses 13 share the peripheral edge of the recess and the peak positions on the bottom side of the plurality of recesses 13 are vacant by 50 nm or more, the plurality of recesses 13 are separately and independently provided. It is regarded as the recess 13. At this time, a region belonging to each of the concave portions 13 can be defined by performing Voronoi division with respect to the concave portion sharing the peripheral edge portion with the peak position on the bottom side of the plurality of concave portions 13 as a base point. .

Similarly, a description will be given of the recognition of the protrusions 14 and the diameter thereof when the plurality of protrusions 14 are close to each other. First, the position of the protrusion 14 is determined by the highest position of the protrusion 14 (the peak position on the top side). The interval between the adjacent protrusions 14 can be determined by the distance between the top peak positions of the respective protrusions 14. If a certain protrusion 14 is present at a distance of 50 nm or more from the surrounding protrusions 14, the protrusion 14 is regarded as an independent protrusion 14. On the other hand, a group in which the plurality of convex portions 14 are gathered with an interval of less than 50 nm, and a group in which there is an interval of 50 nm or more with surrounding convex portions 14 not included in the group is formed. If so, this group is regarded as one protrusion 14. Then, the diameter of the entire group is measured as the diameter of the projection 14. In the case where the plurality of protrusions 14 share the overhanging peripheral portion and the peak positions on the top side of the plurality of protrusions 14 are vacant by 50 nm or more, the plurality of protrusions 14 are separately provided. Are regarded as independent projections 14. At this time, a region belonging to each convex portion 14 is defined by performing Voronoi division on the overhang that shares the peripheral portion with the peak position on the top side of the plurality of convex portions 14 as a generating point. Can be.

The depth of each of the recesses 13 included in the plurality of recesses is generally 10 nm to 100 nm, preferably 20 nm to 80 nm, and more preferably 30 nm to 50 nm in cross-sectional view in the laminating direction of the base material 11 and the film 12. Is more preferable. The depth of the recess 13 can be obtained by observing the cross section of the coating 12 with a scanning electron microscope or the like and calculating the average value of the distance from the entrance to the bottom of the recess 13.

The height of each protrusion 14 included in the plurality of protrusions is generally 10 nm to 100 nm, preferably 20 nm to 80 nm, and more preferably 30 nm to 50 nm in cross-sectional view in the laminating direction of the base material 11 and the film 12. Is more preferable. The height of the protrusion 14 is obtained by observing a cross section of the film 12 with a scanning electron microscope or the like and calculating an average value obtained by measuring the distance from the surface of the flat portion of the film 12 to the top of the protrusion 14. be able to.

When the depth of the concave portion 13 and the height of the convex portion 14 exceed the lower limit of the above range, the area where the concave portion 13 and the convex portion 14 can diffuse and reflect the incident light increases, and the diffuse reflection tends to increase. When the depth of the concave portion 13 and the height of the convex portion 14 are less than the upper limit of the above range, a decrease in diffuse reflection caused by the concave portion 13 and the convex portion 14 becoming a needle-like or plate-like concave-convex structure, for example. Can be suppressed. It is considered that the decrease in the diffuse reflection is due to the fact that the area in which the incident light can be diffusely reflected is reduced and the incident light is absorbed by the needle-shaped or plate-shaped uneven structure. As described above, when the depth of the concave portion 13 and the height of the convex portion 14 are within the above ranges, the aluminum member 100 tends to be observed as exhibiting white color.

The density of the concave portions 13 and the convex portions 14 in the coating 12 is preferably 3 / μm ² to 500 / μm ² , more preferably 5 / μm ² to 200 / μm ² , and 10 / Μm ² to 100 particles / μm ² is more preferable. By setting the densities of the concave portions 13 and the convex portions 14 in such a range, the light incident on the porous layer 40 can be easily diffused and reflected by the concave portions 13 and the convex portions 14, and the aluminum member 100 having better whiteness can be obtained. Can be provided. The densities of the concave portions 13 and the convex portions 14 can be obtained by counting the total number of the concave portions 13 and the convex portions 14 per unit area on the surface of the film 12 using a scanning electron microscope or the like.

(5) The area ratio of the concave portions 13 and the convex portions 14 in the film 12 is preferably 5% to 80%, more preferably 20% to 70%, and further preferably 30% to 60%. By setting the area ratio of the concave portions 13 and the convex portions 14 in such a range, the light incident on the porous layer 40 can be easily diffused and reflected by the concave portions 13 and the convex portions 14, and the aluminum member 100 having more favorable whiteness can be obtained. Can be provided. The area ratio of the concave portions 13 and the convex portions 14 represents the ratio of the area occupied by the concave portions 13 and the convex portions 14 to the surface area of the film 12 on the surface of the porous layer 40 as a percentage. The area ratio of the concave portions 13 and the convex portions 14 can be obtained by calculating the total area occupied by the concave portions 13 and the convex portions 14 per unit area on the surface of the film 12 using a scanning electron microscope or the like.

The porous layer 40 has a plurality of pores, and the plurality of pores have an average pore diameter of 0.1 μm to 10 μm. The average pore diameter of the pores 15 in the porous layer 40 is preferably 0.5 μm to 8 μm, and more preferably 1 μm to 5 μm. The average pore diameter d (μm) of the porous layer 40 is preferably in a range represented by the following equation, where the time required for the aluminum member 100 to suck up 4 cm of water is t seconds.
Average pore diameter d = k / t
Here, k is a constant, and specifically, k is preferably from 200 to 2000, and more preferably from 500 to 1500. Such holes 15 make it easy to secure an appropriate diameter for sucking up water by capillary action, and improve the water sucking performance of the aluminum member 100. The average pore diameter of the pores 15 can be measured, for example, by a mercury intrusion method. In addition, it is preferable that the diameter of the concave portion 13 or the convex portion 14 is within the above-described predetermined range and smaller than the average pore diameter of the porous layer 40. Specifically, the diameter of the concave portion 13 is preferably 10 nm to 200 nm, and is preferably smaller than the average pore diameter in the porous layer 40. It is preferable that the diameter of the projections 14 is 10 nm to 200 nm and smaller than the average pore diameter in the porous layer 40.

The thickness of the porous layer 40 is preferably 30 μm to 10 cm. By setting the thickness of the porous layer 40 in such a range, it is easy to secure a sufficient thickness for absorbing water by capillary action, and the aluminum member 100 having better whiteness and water absorption performance is provided. can do. The thickness of the porous layer 40 is preferably 40 μm or more, and more preferably 50 μm or more. The thickness of the porous layer 40 is more preferably 1000 μm or less, further preferably 200 μm or less, and particularly preferably 150 μm or less.

<Substrate>
As shown in FIG. 5, the aluminum member 100 may further include a substrate 50. The substrate 50 can support the porous layer 40, and can improve the rigidity of the aluminum member 100. The substrate 50 may have a layered shape.

The porous layer 40 may be provided on at least one surface of the substrate 50. Specifically, the porous layer 40 may be provided only on one surface side of the substrate 50, or may be provided on both surface sides of the substrate 50. The porous layer 40 is preferably disposed on the outermost surface of the aluminum member 100.

Since the aluminum member 100 does not necessarily need to have the substrate 50, the thickness of the substrate 50 is more than 0 μm. The thickness of the substrate 50 depends on the application, but may be, for example, 1 mm or less, 100 μm or less, 10 μm or less, or 1 μm or less.

The material forming the substrate 50 may be substantially the same as the material of the base material 11. When the substrate 50 and the base material 11 are the same material, the substrate 50 and the base material 11 may be integrally formed. In this case, the substrate 50 and the base material 11 of the porous layer 40 may be formed continuously. The substrate 50 may be made of metal aluminum. The metallic aluminum constituting the substrate 50 is preferably pure aluminum having a purity of 99% or more, more preferably pure aluminum having a purity of 99.9% or more, and pure aluminum having a purity of 99.98% or more. Is more preferable.

The thickness of the aluminum member 100 depends on the application, but may be, for example, 50 μm or more, 100 μm or more, or 150 μm or more. Further, the thickness of aluminum member 100 may be 300 μm or less, 250 μm or less, or 200 μm or less. By setting the thickness of the aluminum member 100 in such a range, the aluminum member 100 having good bending strength can be provided.

The arithmetic average roughness Sa of the aluminum member 100 is preferably 0.1 μm to 30 μm, more preferably 0.6 μm to 20 μm, and further preferably 1 μm to 10 μm. By setting the arithmetic mean roughness Sa in such a range, the L ^* value tends to increase, and it becomes easy to provide the aluminum member 100 having better whiteness. The arithmetic average roughness Sa can be obtained by measuring the surface of the aluminum member 100 on the side of the porous layer 40 according to ISO25178. In this specification, the arithmetic mean roughness Sa of the aluminum member 100 mainly reflects the roughness of the secondary rough surface structure 20.

The aluminum member 100 preferably has an L ^* value in the L ^* a ^* b ^* color system of 80 or more, more preferably 85 or more, even more preferably 90 or more, and even more preferably 95 or more. Is particularly preferred. The L ^* value in the L ^* a ^* b ^* color system can be determined according to JIS Z8722: 2009 (color measurement method-reflection and transmission object colors). Specifically, the L ^* value can be measured using a colorimeter or the like, and can be measured under conditions such as a diffuse illumination vertical light receiving system (D / 0), a viewing angle of 2 °, and a C light source. .

The aluminum member 100 preferably has a water suction height of 3 cm or more, more preferably 4 cm or more, and even more preferably 5 cm or more, due to capillary action. By doing so, for example, an aluminum member 100 suitable for chromatography or the like can be provided. The suction height is, for example, such that the aluminum member 100 is immersed in pure water and allowed to stand for 10 minutes so that the plane direction of the aluminum member 100 is perpendicular to the liquid level, and then the water is sucked up by capillary action. It can be obtained by measuring the height. Note that the pure water is pure water having a specific resistance of 10 kΩm measured at 30 ° C.

In the bending test according to the MIT bending test method, it is preferable that the aluminum member 100 does not break even if it is bent 100 times or more. When the aluminum member 100 satisfies such requirements, the aluminum member 100 is easily stored and transported in a roll shape. The MIT type bending test method is specified by EIAJ RC-2364A, and the MIT type bending test device uses the device specified by JIS P8115 (paper and board-folding strength test method-MIT test machine method). can do.

As described above, the aluminum member 100 according to the present embodiment includes the porous layer 40 including the base material 11 made of metallic aluminum, and the coating 12 containing aluminum oxide covering the surface of the base material 11. The film 12 has a thickness of 5 nm to 1000 nm, and the film 12 has at least one of a plurality of concave portions 13 and a plurality of convex portions 14 formed on the surface. The depth of each recess 13 included in the plurality of recesses 13 is 10 nm to 100 nm, and the height of each projection 14 included in the plurality of protrusions 14 is 10 nm to 100 nm. The porous layer 40 has a plurality of pores 15, and the average pore diameter of the plurality of pores 15 is 0.1 μm to 10 μm.

The aluminum member 100 may further include a substrate 50 made of metallic aluminum, and the porous layer 40 may be provided on at least one surface of the substrate 50.

The aluminum member 100 according to the present embodiment has high whiteness and water wicking performance, but is not limited to an application in which any of these characteristics is required, and is used in an application in which any one of the characteristics is required. Can also be used.

Examples of useful applications of the aluminum member 100 according to the present embodiment include, for example, a gas or liquid separation membrane; a moisture absorbing material; a water absorbing material; and adsorb foreign substances such as pollen, particulate matter, bacteria, odor components, and heavy metals. Adsorbent material; Wiping sheet; Test sheet for chemicals such as concentrated sulfuric acid, urine test and pH test; Developing member for chromatography such as thin-layer chromatography; Material for disinfection and sterilization; Reflector: Standard white plate Separators such as batteries and electric double layer capacitors; catalyst carriers; reaction sites for synthetic reactions and the like; heat insulating materials; Examples of the separation membrane include a reverse osmosis membrane, an ion exchange membrane, and a gas separation membrane. Examples of the adsorption material include a mask, a filtration membrane, a filter, and the like.

Since the aluminum member 100 has high whiteness, it is preferable to use it as a test sheet, a developing member for chromatography, a reflector, and a standard white plate. Further, since the aluminum member 100 is porous, it is preferable to use the aluminum member 100 as a separation membrane, a moisture absorbing material, a water absorbing material, an adsorbing material, a developing member for chromatography, a separator, a catalyst carrier, a reaction field, and a heat insulating material.

な Among these, the aluminum member 100 is more preferably used for chromatography because of its high whiteness and high water absorption performance. Among chromatography, it is more preferable to use for lateral flow type chromatography. Further, the chromatography is preferably immunochromatography. Among immunochromatography, it is more preferable to be used for a lateral flow immunoassay. Therefore, the aluminum member 100 may be a developing member for chromatography. The developing member for chromatography may be a test strip for chromatography. The aluminum member 100 is also preferably used for an in vitro diagnostic drug such as a test kit using immunochromatography. Note that the test kit may be referred to as a diagnostic kit.

[Test kit]
Next, an example of an inspection kit 200 using the aluminum member 100 will be described. As shown in FIG. 6, the test kit 200 includes an aluminum member 100. Specifically, the test kit 200 includes an aluminum member 100, a sample supply unit 110, a determination unit 120, and an absorption unit 130.

The sample supply unit 110 may include, for example, a labeled antibody that specifically binds to a detection target such as an influenza virus. A sample collected from a living body or the like is supplied to the sample supply unit 110 and mixed with the labeled antibody to form a mixed solution. The mixed solution is developed to the determination unit 120 by the capillary action of the aluminum member 100, and the excess sample is absorbed by the absorption unit 130.

The determination unit 120 has, for example, a test line and a control line. In the test line, for example, an antibody that specifically binds to the detection target is fixed. When the detection target is contained in the sample, the labeled antibody is fixed to the antibody on the test line via the detection target. For example, an antibody that specifically binds to the labeled antibody is immobilized on the control line. When the mixture containing the sample and the labeled antibody is developed to the control line, the labeled antibody binds to the antibody immobilized on the control line.

Labeled antibodies generally include a label such as colored particles or colloidal gold particles, and an antibody that binds to the label to form a complex and specifically binds to a detection target. Therefore, when there is a place where the concentration or the density of the labeled antibody is high, the place can be visually confirmed by densely packed labels. Therefore, with the test kit 200, it is possible to test that both the test line and the control line are positive when they can be visually confirmed, and that the test kit 200 is negative when only the control line can be visually confirmed. .

The test kit 200 can be used, for example, for infectious disease tests; genetic analysis; pregnancy tests; livestock tests; allergen tests for foods, animals, plants, metals, house dust, and the like.

検査 The test target by the test kit 200 includes, for example, amino acids, peptides, proteins, genes, sugars, lipids, cells, or complexes thereof. More specifically, peptides such as PCT (procalcitonin); proteins such as urinary albumin; hormones such as HCG (human chorionic gonadotropin) and LH (luteinizing hormone); HBs antigen, rotavirus antigen, adenovirus antigen , RSV (Respiratory @ Syncytial virus) antigen, influenza virus antigen, norovirus antigen, mump virus antigen, cytomegalovirus antigen, herpes simplex virus antigen, varicella-zoster virus antigen, SARS (severe acute respiratory syndrome) antigen, HBs antibody, HCV (Hepatitis C virus) Antigens or antibodies for viral infections such as antibodies, HIV antibodies, EBV antibodies, RSV antibodies, rubella virus antibodies, measles virus antibodies, enterovirus antibodies, dengue virus antibodies, SARS antibodies; pneumococcal antigens, mycoplasma Antigens or antibodies for bacterial infectious diseases such as Ma antigen, group A hemolytic streptococcal antigen, Legionella antigen, Mycobacterium tuberculosis antigen, Neisseria gonorrhoeae antigen, Tetanus antigen, Mycoplasma antibody, Helicobacter pylori antibody, Mycobacterium tuberculosis antibody; Chlamydia such as Chlamydia antigen Antigens or antibodies for infectious diseases; antigens or antibodies for spirochete infections such as T. pallidum antibodies; antigens or antibodies for protozoal diseases such as malaria antibodies and toxoplasma antibodies.

[Production method of aluminum member]
Next, a method for manufacturing the aluminum member 100 according to the present embodiment will be described. The method for manufacturing the aluminum member 100 of the present embodiment is not particularly limited, but includes, for example, an etching step, a film forming step, and a depolarizing step. In addition, the method for manufacturing the aluminum member 100 may include a hydration step as needed. Hereinafter, each step will be described in detail.

(Etching process)
In the etching step, before the film forming step, the aluminum plate is etched to form a porous structure on the aluminum plate. By the etching step, an aluminum plate having a porous structure having a plurality of pits can be formed. In the etching step, the base material 11 is formed by etching the aluminum plate. The same material as that of the substrate 50 described above can be used for the aluminum plate. That is, the aluminum plate may be made of metallic aluminum.

In the etching step, pits are formed in the aluminum plate to make the aluminum plate porous. Thus, by making the aluminum plate a porous body having a porous structure, the surface area can be increased. The etching step can be performed by, for example, electrolytic etching, chemical etching, or the like. Examples of the electrolytic etching include DC electrolytic etching and AC electrolytic etching. Examples of chemical etching include chemical etching using an acidic solution and chemical etching using an alkaline solution. These etching techniques may be performed alone or a plurality of techniques may be combined.

Here, the explanation will be made by taking electrolytic etching as an example. In the etching step, by performing DC electrolytic etching, pits are formed on the surface of the aluminum plate, and the pits grow in a tunnel shape in a depth direction perpendicular to the surface of the aluminum plate, and the pit diameter is reduced. Expanding. Further, by performing the AC electrolytic etching, the pits are formed in a three-dimensional direction and grow in a spongy manner, and the diameter of the pits is increased. When the pits have grown to the center of the aluminum plate, the aluminum member 100 including the porous layer 40 is formed. If pits do not grow to the center of the aluminum plate and there is a center where the porous layer 40 is not formed, an aluminum member 100 including the porous layer 40 and the substrate 50 is formed.

In the present embodiment, it is preferable that the etching of the substrate 50 is an AC type electrochemical etching. Although the etching conditions are not particularly limited, for example, the etching time is 1 minute to 60 minutes, and the etching temperature is 20 ° C. to 80 ° C. In the case of electrochemical etching, the current density is, for example, 50 mA / cm ² to 500 mA / cm ² .

エッチング The etching solution used for etching is preferably an aqueous solution containing hydrochloric acid. The concentration of the aqueous hydrochloric acid solution is preferably from 6% by mass to 25% by mass. The aqueous hydrochloric acid solution may contain aluminum ions derived from aluminum chloride or the like in order to suppress excessive dissolution of aluminum. The concentration of aluminum chloride is preferably 0.1% by mass to 10% by mass.

(4) The etching step may be performed in a single-step process, or may be performed in different multi-step processes. For example, the etching step may include a plurality of etching steps in which the chemical species contained in the etching solution, the concentration of the etching solution, the etching time, the etching temperature, the current density, and the like are different.

(Film formation step)
In the film forming step, an aluminum plate having a porous structure is anodized to form a film 12 containing aluminum oxide on the surface of the aluminum plate. In the film forming step, a film 12 is formed by anodic oxidation on the surface of the base material 11 which has been made porous by the etching step. At this time, the coating 12 is formed on the surface of the base material 11 exposed to the outside and the surface of the base material 11 forming internal pits on the aluminum plate. In the film forming step, for example, an anode on which the substrate 50 is installed and a cathode on which stainless steel (SUS) is installed are immersed in an electrolytic solution to be subjected to electrolytic treatment.

電解 The electrolytic solution used for forming the film is not particularly limited. For example, an aqueous solution of boric acid, ammonium borate, phosphoric acid, pyrophosphoric acid, ammonium phosphate, ammonium adipate, sulfuric acid, oxalic acid, or the like can be used. The conditions for forming the film are not particularly limited. For example, the voltage is 5 V to 500 V. The film formation may be performed in a single-step process, or may be performed in different steps.

(Depolarization process)
In the depolarization (depolarization) process, the aluminum plate on which the film 12 is formed is subjected to a depolarization process to remove a part of the surface of the film 12. In the depolarizing step, a part of the film 12 formed in the film forming step is removed, and voids and cracks remaining in the film 12 are exposed. In the depolarization treatment step, the surface of the film 12 is roughened by removing (eroding) the film 12, and the concave portion 13 can be formed on the surface of the film 12. The depolarization treatment is performed, for example, by immersing the aluminum plate, on which the film 12 is formed in the film formation step, in a depolarization treatment liquid.

The depolarization treatment liquid is not particularly limited as long as it can remove (erode) the surface of the aluminum oxide film, but is selected from the group consisting of phosphoric acids, metal salts of phosphoric acids, tartaric acid, hydrochloric acid, and metal salts of hydrochloric acid. It is preferably a solution in which at least one is dissolved, or at least one of a sodium hydroxide solution and an aqueous ammonia solution. Phosphoric acids include, for example, orthophosphoric acid, phosphorous acid, hypophosphorous acid, and mixtures thereof. The metal forming the metal salt includes, for example, aluminum, sodium, magnesium, calcium, zinc and the like.

(4) When phosphoric acid or a metal salt of a phosphoric acid is used as the depolarization treatment liquid, the content of the phosphoric acid or the metal salt of the phosphoric acid is preferably, for example, 0.1 g / L to 50 g / L. The treatment temperature of the phosphoric acid treatment is preferably, for example, 50 ° C. to 80 ° C. Further, the treatment time of the phosphoric acid treatment is preferably 1 minute to 60 minutes.

In the method for manufacturing the aluminum member 100 according to the present embodiment, at least one of the plurality of concave portions 13 and the plurality of convex portions 14 is formed on the surface of the film by the film forming step and the depolarizing step. That is, in the method for manufacturing the aluminum member 100 according to the present embodiment, the etching step, the film forming step, and the depolarization step can be performed at least once in this order. Although the number of times each step is performed is not particularly limited, it is preferable that the film forming step and the depolarizing step are alternately repeated after the etching step. Thereby, the erosion of the coating 12 and the repair of the eroded coating 12 are repeated, so that a good porous layer 40 is formed. At least one of the plurality of concave portions 13 and the plurality of convex portions 14 is preferably formed by alternately repeating the film forming step and the depolarizing step two or more times. The number of repetitions of the film forming step and the depolarizing step is not particularly limited, but may be, for example, 20 times or less, or 15 times or less. The number of repetitions of the film forming step and the depolarizing step is preferably 2 to 10 times, more preferably 3 to 8 times. More preferably, the number of repetitions of the film forming step and the depolarizing step is 5 or more. By repeating the film forming step and the depolarizing step, a plurality of recesses 13 can be formed in the film 12, so that the whiteness of the aluminum member 100 can be improved.

(Hydration process)
Although the method for manufacturing the aluminum member 100 according to the present embodiment may include a hydration step, when the hydration step is performed, the film formation step and the depolarization step are thereafter performed. It is preferable to repeat. The method of manufacturing the aluminum member 100 may further include a hydration step of hydrating the aluminum plate to form a hydrated film on the aluminum plate having a porous structure before the film formation step. The hydration treatment step is generally a step of forming a hydration film of aluminum hydroxide on the surface of metal aluminum after the etching step.The aluminum whose surface has been made porous is treated with hot water such as boiling water. This is the step of heat treatment. When fine irregularities on the surface are covered with aluminum hydroxide, diffuse reflection of light is hindered, and the whiteness of the aluminum member may be reduced. Further, since the porous portion of the aluminum member is easily clogged with aluminum hydroxide, the diffuse reflection of light is hindered, and the whiteness of the aluminum member is reduced.

白色 By omitting the hydration step, the whiteness of the aluminum member 100 can be further improved. When a hydrated film is formed by the hydration process, the hydrated film can be dissolved by further performing anodization and depolarization. As a result, the hydrated film can be reduced or eliminated, and the protrusions 14 can be formed on the surface of the film 12. Then, the whiteness can be improved by the convex portions 14. At this time, it is considered that the protrusion 14 can be formed by the remaining hydrated film or anodic oxide film.

Specifically, by performing anodic oxidation and depolarization treatment, the hydrated film on the inner layer side is taken into the anodic oxide film in order, and the surface of the base material 11 is composed of the anodic oxide film and the remainder of the hydrated film. A coating 12 results. In other words, a layer structure is formed in which the base material 11, the anodic oxide film, and the rest of the hydrated film are laminated in this order. The layer structure is further subjected to an anodizing treatment and a depolarizing treatment, so that the protrusions 14 are formed on the film 12.

凹部 Depending on the conditions of the anodic oxidation treatment and the depolarization treatment, the concave portion 13 can be formed on the film 12 together with the convex portion 14. By performing the anodizing treatment and the depolarizing treatment to the extent that the hydrated film does not remain, the concave portion 13 can be formed on the surface of the film 12. The convex portion 14 is formed by (the remainder of) a hydrated film or an anodized film.

As described above, the pores 15 are formed in the porous layer 40 through the formation of the pits in the base material 11 by the etching process and the formation and removal of the anodic oxide film by the film forming process and the depolarizing process. Thereby, the secondary rough surface structure 20 is formed. Further, by the film forming step and the depolarizing step, a concave portion 13 is formed on the surface of the film 12, and the primary rough surface structure 10 is formed. Further, by the film forming step and the depolarizing step after the hydration processing step, the convex portion 14 is formed on the surface of the film 12, and the primary rough surface structure 10 is formed. Furthermore, after the etching step, by repeating the film forming step and the depolarizing step, an uneven structure composed of an aggregate of the primary rough surface structure 10 and the secondary rough surface structure 20 develops, and the tertiary rough surface structure 30 is formed. You.

As described above, the method for manufacturing the aluminum member 100 includes a film forming step of anodizing an aluminum plate having a porous structure and forming a film 12 containing aluminum oxide on the aluminum plate. The method for manufacturing the aluminum member 100 includes a depolarization process of depolarizing the aluminum plate on which the film 12 is formed and removing a part of the surface of the film 12. The film forming step and the depolarizing step are alternately repeated. The aluminum plate is made of metal aluminum. Further, in the method of manufacturing the aluminum member 100, at least one of the plurality of concave portions 13 and the plurality of convex portions 14 is formed on the surface of the film 12 by the film forming step and the depolarizing step. Further, the film 12 has a thickness of 5 nm to 1000 nm. The depth of each recess 13 included in the plurality of recesses 13 is 10 nm to 100 nm, and the height of each projection 14 included in the plurality of protrusions 14 is 10 nm to 100 nm. The aluminum member 100 has a plurality of pores 15, and the average pore diameter of the plurality of pores 15 is 0.1 μm to 10 μm.

In the present embodiment, a method for manufacturing the aluminum member 100 including the porous layer 40 by electrochemical etching or the like has been described. However, the method for manufacturing the aluminum member 100 is not limited to the above embodiment, and for example, the porous layer 40 may be formed by sintering aluminum powder.

Hereinafter, the present embodiment will be described in more detail with reference to examples and comparative examples, but the present embodiment is not limited thereto.

[Example 1]
An aluminum foil having a thickness of 150 μm is subjected to alternating current electrolytic etching in an aqueous solution containing 3 mol / L hydrochloric acid and 0.2 mol / L sulfuric acid to make the surface of the aluminum foil porous, and then sufficiently washed with water. Washed. As the aluminum foil, high-purity aluminum having a purity of 99.98% was used.

FIG. 7 is a photograph showing a state of the surface of the aluminum plate after the etching observed with a scanning electron microscope. As shown in FIG. 7, the etched aluminum plate has a diameter of about 0.1 μm to 1 μm, and has a porous structure having a plurality of pits traveling inside. A plurality of pits having a diameter of about 0.1 μm to 1 μm are formed on the surface of the aluminum plate and are exposed to the outside, and the aluminum plate is roughened.

Next, the electrolytically etched aluminum foil was anodized to form a film on the surface of the base material made of pure aluminum. Specifically, an aluminum foil provided on the anode and stainless steel (SUS) provided on the cathode were immersed in a boric acid electrolyte having a concentration of 80 g / L and an electrolyte temperature of 70 ° C. . Then, anodizing treatment was performed at a voltage of 200 V for 10 minutes.

Next, after the aluminum foil on which the film was formed was sufficiently washed with water, the aluminum foil was immersed in a phosphoric acid aqueous solution having a concentration of 50 g / L and a temperature of 60 ° C. for 20 minutes to perform a depolarization treatment.

{Circle around (5)} Then, the anodizing and the depolarizing treatment were repeated 5 times in this order under the same conditions as above, thereby producing an aluminum member.

[Example 2]
An aluminum member was produced in the same manner as in Example 1, except that the boric acid electrolytic solution used for the anodizing treatment was changed to an aqueous solution of ammonium dihydrogen phosphate 1 g / L and the anodizing treatment voltage was changed to 50 V.

[Example 3]
An aluminum member was produced in the same manner as in Example 1, except that the boric acid electrolytic solution used for the anodizing treatment was changed to an aqueous solution of ammonium adipate 100 g / L, and the anodizing treatment voltage was changed to 150 V.

[Example 4]
An aluminum member was prepared in the same manner as in Example 1 except that the boric acid electrolyte used for the anodizing treatment was changed to an aqueous solution of oxalic acid of 50 g / L, the anodizing treatment temperature was changed to 30 ° C., and the anodizing treatment voltage was changed to 20 V. Produced.

[Example 5]
Before performing the anodizing treatment, as a pretreatment, the electrode was immersed in a phosphoric acid aqueous solution having a concentration of 50 g / L and a temperature of 60 ° C. for 10 minutes to perform depolarization treatment, and the voltage of the anodizing treatment was changed to 150 V. An aluminum member was produced in the same manner as in Example 1.

[Example 6]
An aluminum member was produced in the same manner as in Example 1 except that a hydrophilic coating agent was applied as a post-treatment to the sample after repeating the depolarization treatment.

[Example 7]
An aluminum member was produced in the same manner as in Example 1, except that one surface of the sample after repeating the depolarization treatment was coated with a 20-μm-thick nylon resin as a post-treatment.

Example 8
An aluminum member was produced in the same manner as in Example 1, except that one of the depolarization treatments with the phosphoric acid aqueous solution was changed to heat treatment. The heat treatment was performed in air at 500 ° C. for 5 minutes.

[Example 9]
An aluminum member was produced in the same manner as in Example 1 except that the aqueous solution of phosphoric acid used for the depolarization treatment was changed to a 5 g / L aqueous solution of sodium hydroxide, and the temperature of the depolarization treatment was changed to 40 ° C.

[Example 10]
Before the anodizing treatment, the electrolytically etched aluminum foil is immersed in boiling pure water for 10 minutes to perform a hydration treatment. Thereafter, the anodizing treatment and the depolarization treatment are performed. The number of repetitions was changed to seven. Except for the above, an aluminum member was produced in the same manner as in Example 1.

[Comparative Example 1]
An aluminum member was produced in the same manner as in Example 1 except that the anodized aluminum foil was subjected to the anodic oxidation treatment only once and the depolarization treatment was not performed.

[Comparative Example 2]
An aluminum member was produced in the same manner as in Example 1, except that the anodic oxidation treatment and the depolarization treatment were performed without performing the electrolytic etching.

[Comparative Example 3]
An aluminum member was produced in the same manner as in Example 10, except that the number of repetitions of the anodic oxidation treatment and the depolarization treatment was changed to one.

[Evaluation]
The surfaces of the aluminum members according to Example 3, Example 10, and Comparative Example 3 were observed with a scanning electron microscope. Electron micrographs are shown in FIGS. 8, 9 and 10, respectively.

In the aluminum member obtained in each example, the film thickness, the diameter of the concave portion or convex portion of the primary structure, the depth of the concave portion or the height of the convex portion, the average pore diameter of the pores, the bending test, the arithmetic average roughness Sa , The period of the tertiary rough surface structure, the L ^* value, and the water suction height were evaluated as follows.

(Film thickness)
After cutting the aluminum member, the cut surface was mirror-finished with a cross section polisher (registered trademark) manufactured by JEOL Ltd. to obtain a sample for measuring the film thickness. The thickness of the film was measured by observing the cross section of the sample for measuring the film thickness with a scanning electron microscope ULTRA plus manufactured by Carl Zeiss Co., Ltd.

(Diameter of concave part of primary structure)
The surface of the film was observed with a scanning electron microscope ULTRA plus manufactured by Carl Zeiss Co., Ltd., and the diameter of the concave portion was determined by averaging the diameter of the entrance portion of the concave portion.

(Diameter of primary structure protrusion)
The surface of the film was observed with a scanning electron microscope ULTRA plus manufactured by Carl Zeiss Co., Ltd., and the diameter of the convex part was averaged to find the diameter of the part where the convex part was the largest.

(Depth of recess)
The cross section of the film was observed with a scanning electron microscope, and the depth of the recess was determined by calculating the average value of the distance from the entrance to the bottom of the recess.

(Protrusion height)
The height of the projections was determined by observing the cross section of the coating with a scanning electron microscope and calculating the average value of the distance from the surface of the flat portion of the coating to the top of the projections.

(Average pore diameter of pores)
The average pore diameter of the pores was measured by the mercury intrusion method.

(Bending test)
The bending test was performed according to the MIT-type bending test method (EIAJ RC-2364A) specified by the Japan Electronic Machinery Manufacturers Association. As the MIT type bending test apparatus, an apparatus specified in JIS P8115 (paper and paperboard-folding strength test method-MIT test machine method) was used. In the bending test, the process of bending the aluminum member 90 ° and returning it to its original shape was defined as one bending, and the aluminum member was bent 100 times. If the aluminum member did not break, the test was “good”. Was evaluated as “No”.

(Arithmetic average roughness Sa)
The arithmetic average roughness Sa of the surface of the aluminum member on the porous layer side was measured according to ISO25178. The conditions for measuring the arithmetic average roughness Sa are as follows.

Arithmetic mean roughness Sa measurement conditions Apparatus: Bruker AXS Co., Ltd. 3-D white interference microscope Contour GT-I
Measurement range: 60 μm × 79 μm
Objective lens: 115x Internal lens: 1x

(Period of tertiary rough surface structure)
The cross section of the obtained aluminum member was observed with an optical microscope, and the period of the tertiary rough surface structure was measured.

(L ^* value)
According to JIS Z8722, the surface of the aluminum member was measured with a colorimeter to determine the L ^* value. The colorimetric conditions are as follows.

Measurement conditions for L ^* value Color difference meter: Konica Minolta Japan CR400
Illumination / light receiving optical system: diffuse illumination vertical light receiving system (D / 0)
Observation conditions: CIE 2 ° visual field color matching function approximation Light source: C light source Color system: L ^* a ^* b ^*

(Water suction height)
The aluminum member was immersed in pure water so that the plane direction of the aluminum member was perpendicular to the liquid surface, and allowed to stand for 10 minutes. Then, the height at which water was sucked up by capillary action was taken as the water sucking height.

FIGS. 8, 9 and 10 are photographs of the surface of the aluminum member according to Example 3, Example 10 and Comparative Example 3, respectively, observed with a scanning electron microscope. The aluminum member according to Example 3 did not include a hydrated film because it was not subjected to a hydration treatment, and had a primary rough surface structure with concave portions having a diameter of 10 nm to 200 nm on the surface of the aluminum member as indicated by arrows. Had been formed. In the aluminum member according to Example 10, the anodic oxidation treatment and the depolarization treatment were repeatedly performed after forming a hydrated film by boiling with boiling pure water. For this reason, as shown by the arrows, a primary roughened surface structure having protrusions having a diameter of 10 nm to 200 nm was formed on the surface of the aluminum member. It is assumed that these concave portions and convex portions contribute to the whiteness of the aluminum member. On the other hand, in the aluminum member of Comparative Example 3, since the anodic oxidation treatment and the depolarization treatment after the hydration treatment were insufficient, no concave portion or convex portion was formed, and the porous aluminum plate was not used. The surface was covered with aluminum hydroxide having a needle-like or plate-like structure. Thus, in Comparative Example 3, it is assumed that the whiteness of the aluminum member is reduced.

Next, Table 1 shows the evaluation results of the aluminum members obtained in each example.

As shown in Table 1, the aluminum members of Examples 1 to 10 had better whiteness (L ^* value) and water wicking performance than the aluminum members of Comparative Examples 1 to 3. On the other hand, in Comparative Example 1, since the depolarization treatment was not performed after the anodic oxidation treatment, no concave portion or convex portion was formed, and the whiteness was low. In Comparative Example 2, since no electrolytic etching was performed, no holes were formed, and the water wicking performance was insufficient. In Comparative Example 3, since the number of repetitions of the anodic oxidation treatment and the depolarization treatment after the hydration treatment was small, the entire surface was covered with the hydrated film, and the whiteness was low.

The arithmetic mean roughness Sa of the aluminum plate (not shown) before etching is 0.37 μm, and the L ^* value is 49.5. The arithmetic average roughness Sa of the etched aluminum plate shown in FIG. 7 is 0.336 μm, and the L ^* value is 71.4. Therefore, simply etching the aluminum plate does not increase the whiteness of the aluminum plate.

The entire contents of Japanese Patent Application No. 2018-174947 (filing date: September 19, 2018) are incorporated herein.

Although the present embodiment has been described above with reference to examples and comparative examples, the present embodiment is not limited to these, and various modifications can be made within the scope of the present embodiment.

According to the present invention, it is possible to provide an aluminum member having high whiteness and high water absorption performance, and a method for producing the same.

DESCRIPTION OF SYMBOLS 10 Primary rough surface structure 11 Base material 12 Coating 13 Concavity 14 Convex part 15 Void 20 Secondary rough surface structure 30 Tertiary rough surface structure 40 Porous layer 50 Substrate 100 Aluminum member

Claims

A base material made of metallic aluminum, and a coating containing aluminum oxide covering the surface of the base material, comprising a porous layer,
The coating has a thickness of 5 nm to 1000 nm;
The film has at least one of a plurality of concave portions and a plurality of convex portions formed on the surface,
The depth of each recess included in the plurality of recesses is 10 nm to 100 nm,
Each of the plurality of protrusions has a height of 10 nm to 100 nm,
An aluminum member, wherein the porous layer has a plurality of pores, and the plurality of pores have an average pore diameter of 0.1 μm to 10 μm.
The aluminum member according to claim 1, wherein the diameter of each of the concave portions is 10 nm to 200 nm, and is smaller than the average pore diameter of the porous layer.
The aluminum member according to claim 1, wherein the diameter of each of the protrusions is 10 nm to 200 nm.
The coating, a primary rough surface structure formed by at least one of the plurality of concave portions and the plurality of convex portions,
A secondary rough surface structure formed by the base material and the plurality of holes,
A tertiary rough surface structure comprising a set of the primary rough surface structure and the secondary rough surface structure,
The aluminum member according to any one of claims 1 to 3, having:
The aluminum member according to any one of claims 1 to 4, wherein the arithmetic average roughness Sa is 0.1 μm to 30 μm.
The aluminum member according to any one of claims 1 to 5, wherein the L * value in the L * a * b * color system is 80 or more.
(7) The aluminum member according to any one of (1) to (6), wherein the water suction height by capillary action is 3 cm or more.
The aluminum member according to any one of claims 1 to 7, wherein the aluminum member does not break even after being bent 100 times or more in a bending test according to a MIT type bending test method.
Further comprising a substrate made of metal aluminum,
The aluminum member according to any one of claims 1 to 8, wherein the porous layer is provided on at least one surface side of the substrate.
(10) The aluminum member according to any one of (1) to (9), which is used for chromatography.
Anodizing an aluminum plate having a porous structure, a film forming step of forming a film containing aluminum oxide on the aluminum plate,
Depolarizing the aluminum plate on which the film is formed, and a depolarizing process of removing a part of the surface of the film,
The film forming step and the depolarizing step are alternately repeated,
The method for manufacturing an aluminum member, wherein the aluminum plate is made of metal aluminum.
By the film forming step and the depolarizing step, at least one of a plurality of concave portions and a plurality of convex portions is formed on the surface of the film,
The coating has a thickness of 5 nm to 1000 nm;
The depth of each recess included in the plurality of recesses is 10 nm to 100 nm,
Each of the plurality of protrusions has a height of 10 nm to 100 nm,
The method for manufacturing an aluminum member according to claim 11, wherein the aluminum member has a plurality of holes, and the average pore diameter of the plurality of holes is 0.1 μm to 10 μm.
The method of manufacturing an aluminum member according to claim 11, further comprising an etching step of etching the aluminum plate and forming the porous structure on the aluminum plate before the film forming step.
14. The method according to claim 11, further comprising, before the film forming step, hydrating the aluminum plate to form a hydrated film on the aluminum plate having the porous structure. 3. The method for producing an aluminum member according to item 1.
By the film forming step and the depolarizing step, at least one of a plurality of concave portions and a plurality of convex portions is formed on the surface of the film,
15. The method according to claim 11, wherein at least one of the plurality of concave portions and the plurality of convex portions is formed by alternately repeating the film forming step and the depolarizing step two or more times. Item 13. The method for producing an aluminum member according to Item 1.