Appearance unevenness suppression member

Abstract

To provide a large and mass-producible appearance unevenness suppression member capable of suppressing appearance unevenness.SOLUTION: An appearance unevenness suppression member 1 comprises an aluminum base 40 and an anodic oxide film 50. The anodic oxide film 50 includes a porous layer 52. A coloring layer 53 is provided in the porous layer 52. The appearance unevenness suppression member 1 further comprises a triangular-wave structure 10. A salient 20 and a recess 30 are alternately and continuously arranged in the triangular-wave structure 10. The average depth of a plurality of recesses 30 is 1 mm or greater and 30 mm or less. In a cross-sectional view, the average value of an internal embrace angle, which is the angle inside the recess 30 formed by a first wall part 22a and a second wall part 22b, is greater than 0° and less than or equal to 90°.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a member for suppressing unevenness in appearance. [Background technology]

[0002] BACKGROUND ART Aluminum members made of pure aluminum or aluminum alloys are used for building exterior components arranged on the exterior walls of buildings, vehicle components, civil engineering components, optical components, and the like.

[0003] The brightness of an aluminum component changes depending on the relationship between the position of the light source relative to the component and the position of the observer relative to the component, as well as the optical properties of the aluminum component. Even aluminum components from the same lot manufactured using the same materials and under the same manufacturing conditions may have different optical properties. For example, when aluminum components are used as building exterior components and multiple aluminum components from the same lot are combined and arranged in a plane, the observer may perceive the multiple aluminum components as having different brightnesses. Such differences in brightness among multiple aluminum components are perceived as unevenness in the appearance of the building.

[0004] Patent Document 1 discloses a technology for low-reflection aluminum materials that increases the uniformity of reflected light from aluminum components by performing a laser irradiation treatment on the surface of the aluminum material to form a low-reflection layer with a surface layer having micron-order irregularities. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-106095 Summary of the Invention [Problem to be solved by the invention]

[0006] Patent Document 1 can improve the uniformity of reflected light from a single aluminum member. However, Patent Document 1 does not address the issue of reducing uneven appearance caused by differences in brightness between multiple aluminum members.

[0007] Furthermore, in Patent Document 1, a low-reflection layer having an uneven surface layer is formed by performing a laser irradiation process, so that it is only applicable to small aluminum components, and there is a demand for improvements in productivity, such as for larger components and mass production.

[0008] The present disclosure has been made in view of the problems inherent in the conventional techniques, and an object of the present disclosure is to provide a member for suppressing appearance unevenness that can be mass-produced in large quantities and that can suppress appearance unevenness. [Means for solving the problem]

[0009] The appearance unevenness suppressing member according to an embodiment of the present disclosure is a member for suppressing unevenness in appearance, comprising an aluminum substrate containing pure aluminum or an aluminum alloy and an anodized coating formed on the surface of the aluminum substrate. The anodized coating comprises a barrier layer formed on the surface of the aluminum substrate and a porous layer formed on the surface of the barrier layer and having a plurality of pores. The porous layer is provided with a coloring layer containing at least one of a metal, a metal salt, a dye, a pigment, and an organic acid. The appearance unevenness suppressing member has a triangular wave structure. The triangular wave structure has a plurality of convex portions each having a peak and a plurality of concave portions each having a bottom and sandwiched between adjacent convex portions among the plurality of convex portions, the convex portions and the concave portions being alternately arranged in succession. Each of the plurality of concave portions is formed by a first wall portion and a second wall portion in a cross-sectional view, and is recessed so that its width narrows toward its bottom. Each of the plurality of convex portions is formed by a first wall portion of one concave portion adjacent to the convex portion and a second wall portion of the other concave portion adjacent to the convex portion in a cross-sectional view, and protrudes so that its width narrows toward its top. The average depth of the multiple recesses is 1 mm or more and 30 mm or less. In a cross-sectional view, the average value of the included angle, which is the internal angle of the recess formed by the first wall portion and the second wall portion, is more than 0° and 90° or less. The depth of each of the multiple recesses is substantially the same. In a first direction in which the convex portions and concave portions of the triangular wave structure are alternately and continuously arranged, the bottom of the recess is located between the tops of the convex portions on both sides that are continuous with the recess. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a member for suppressing appearance unevenness that can be mass-produced in large scale and that can suppress appearance unevenness. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a cross-sectional view illustrating an example of an appearance unevenness suppression member according to an embodiment. [Figure 2] FIG. 10 is a cross-sectional view showing an example of an appearance unevenness suppression member according to another embodiment. [Figure 3] FIG. 10 is a cross-sectional view showing an example of an appearance unevenness suppression member according to another embodiment. [Figure 4] It is a schematic enlarged cross-sectional view of the circular frame portion in FIG. 1. [Figure 5] It is an explanatory diagram showing an example in which incident light is reflected as the first reflected light when 0 ≦ θ < π / 2. [Figure 6] It is an explanatory diagram showing how the incident light changes within the range of 0 ≦ α ≦ θ / 2 when 0 ≦ θ < π / 2. [Figure 7] It is an explanatory diagram showing the relationship between incident light and reflected light when π / 2 ≦ θ ≦ π and 0 ≦ X ≦ θ - π / 2. [Figure 8] It is an explanatory diagram showing how the incident light is incident on the line segment AC when π / 2 ≦ θ ≦ π and 0 ≦ X ≦ θ - π / 2. [Figure 9] It is an explanatory diagram showing the relationship between incident light and reflected light when π / 2 ≦ θ ≦ π and θ - π / 2 < X ≦ π. [Figure 10] It is a schematic cross-sectional view showing the structure when the included angle θ is less than π. [Figure 11] It is a schematic cross-sectional view showing the structure when the included angle θ is π. [Figure 12] It is a graph showing the relationship between the included angle θ and the probability function. [Figure 13] It is an explanatory diagram for explaining the Fresnel formula. [Figure 14] It is a graph showing the relationship between the incident angle α and the reflectance R. [Figure 15] It is an explanatory diagram showing the model used in the simulation. [Figure 16] It is a diagram showing an example of an image obtained by simulation. [Figure 17] It is an image of a bronze material with an included angle of 20° obtained by simulation. [Figure 18] It is an image of a bronze material with an included angle of 50° obtained by simulation. [Figure 19] It is an image of a bronze material with an included angle of 60° obtained by simulation. [Figure 20] It is an image of a bronze material with an included angle of 80° obtained by simulation. [Figure 21] This is an image of a bronze material with an included angle of 90° obtained through simulation. [Figure 22] This is an image of a bronze material with an included angle of 100° obtained through simulation. [Figure 23] This is an image of black material with an included angle of 20° obtained through simulation. [Figure 24] This is an image of black material with an included angle of 50° obtained through simulation. [Figure 25] This is an image of black material with an included angle of 60° obtained through simulation. [Figure 26] This is an image of black material with an included angle of 80° obtained through simulation. [Figure 27] This is an image of black material with an included angle of 90° obtained through simulation. [Figure 28] This is an image of black material with an included angle of 100° obtained through simulation. [Figure 29] 10 is a graph showing the relationship between the included angle of a bronze material and the luminance difference at an observation angle of 0°. [Figure 30] 10 is a graph showing the relationship between the included angle of a bronze material and the luminance difference at an observation angle of −45°. [Figure 31] 10 is a graph showing the relationship between the included angle and the luminance difference of a bronze material at an observation angle of −60°. [Figure 32] 10 is a graph showing the relationship between the included angle of the black material and the luminance difference at an observation angle of 0°. [Figure 33] 10 is a graph showing the relationship between the included angle of the black material and the luminance difference at an observation angle of −45°. [Figure 34] 10 is a graph showing the relationship between the included angle of the black material and the luminance difference at an observation angle of −60°. [Figure 35] 10 is a cross-sectional view showing an aluminum plate having a triangular wave structure used in Experimental Example 2. FIG. [Figure 36] 1 is a photograph showing the appearance of a test member used in Experimental Example 2. [Figure 37]FIG. 2 is a plan view schematically showing the relationship between a test member and an observation position. [Figure 38] 10 is a graph showing the relationship between observation position and brightness difference. DETAILED DESCRIPTION OF THE INVENTION

[0012] The appearance unevenness suppression member according to this embodiment will be described in detail below with reference to the drawings. The present disclosure is not limited to the following embodiment. Furthermore, some or all of the components in the embodiment can be combined as appropriate. Note that the dimensional proportions in the drawings are exaggerated for the sake of explanation and may differ from the actual proportions.

[0013] In this embodiment, the direction in which the convex portions 20 and the concave portions 30 are alternately arranged is referred to as a first direction X. Furthermore, the direction perpendicular to the first direction X and in which the convex portions 20 and the concave portions 30 extend is referred to as a second direction Y. Furthermore, the direction perpendicular to the first direction X and the second direction Y and in which the convex portions 20 protrude or the concave portions 30 sink is referred to as a third direction Z.

[0014] [1. Appearance unevenness suppression material] As shown in FIG. 1 , the appearance unevenness suppression member 1 according to this embodiment has a triangular wave structure 10. The triangular wave structure 10 has a plurality of convex portions 20 and a plurality of concave portions 30, and the convex portions 20 and the concave portions 30 are arranged alternately and continuously. Each concave portion 30 is sandwiched between adjacent convex portions 20 among the plurality of convex portions 20. Similarly, each convex portion 20 is sandwiched between adjacent concave portions 30 among the plurality of concave portions 30.

[0015] Each of the multiple protrusions 20 has an apex 21 and a pair of wall portions 22. The pair of wall portions 22 includes a first wall portion 22a and a second wall portion 22b. That is, the protrusion 20 includes the first wall portion 22a and the second wall portion 22b. The first wall portion 22a and the second wall portion 22b are connected via the apex 21. Each of the multiple protrusions 20 is formed by the first wall portion 22a and the second wall portion 22b in a cross-sectional view. Each of the multiple protrusions 20 is formed by the first wall portion 22a of one recess 30 adjacent to the protrusion 20 and the second wall portion 22b of the other recess 30 adjacent to the protrusion 20 in a cross-sectional view, and protrudes so that its width narrows toward the apex 21. Each of the multiple protrusions 20 may protrude so that its width gradually narrows continuously toward the apex 21 in a cross-sectional view.

[0016] Each of the plurality of recesses 30 has a bottom 31 and a pair of wall portions 22. Each of the plurality of recesses 30 is formed, in a cross-sectional view, by the walls 22 of adjacent protrusions 20 among the plurality of protrusions 20. That is, the recess 30 includes a first wall portion 22a and a second wall portion 22b. The first wall portion 22a and the second wall portion 22b are connected via the bottom portion 31. Each of the plurality of recesses 30 is formed, in a cross-sectional view, by the first wall portion 22a and the second wall portion 22b. Each of the plurality of recesses 30 is recessed so that its width narrows toward the bottom 31 in a cross-sectional view. Each of the plurality of recesses 30 may be recessed so that its width gradually and continuously narrows toward the bottom 31 in a cross-sectional view.

[0017] In this embodiment, when a line connecting the bottoms 31 of adjacent recesses 30 is assumed to be a line segment at Z=0 in the XZ coordinate system in a cross-sectional view, the apex 21 is a portion where the slope of a tangent line contacting the protrusion 20 changes from positive to negative or from negative to positive and becomes parallel to Z=0. The apex 21 does not have to have a flat portion parallel to the first direction X. The apex 21 may be a vertex. The apex 21 may be, for example, a point where the slope of a tangent line contacting the protrusion 20 becomes parallel to the line connecting the bottoms 31 of adjacent recesses 30.

[0018] In this embodiment, when a line connecting the apexes 21 of adjacent protrusions 20 is assumed to be a line segment at Z=0 in the XZ coordinate system, the bottom 31 is a portion where the slope of a tangent line contacting the recess 30 changes from positive to negative or from negative to positive and becomes parallel to Z=0 in a cross-sectional view. The bottom 31 does not have to have a flat portion parallel to the first direction X. The bottom 31 may be a point. For example, the bottom 31 may be a point where the slope of a tangent line contacting the recess 30 becomes parallel to the line connecting the apexes 21 of adjacent protrusions 20.

[0019] In the first direction X in which the convex portions 20 and concave portions 30 of the triangular wave structure 10 are alternately and continuously arranged, the bottom 31 of the concave portion 30 is located between the apexes 21 of the convex portions 20 on both sides that are continuous with the concave portion 30. Note that the phrase "the bottom 31 of the concave portion 30 is located between the apexes 21 of the convex portions 20 on both sides that are continuous with the concave portion 30" also includes the case in which the concave portion 30 is located at the same position as the apex 21 of one of the convex portions 20 in the first direction X. Here, with reference to FIG. 1 , the relationship between the first wall portion 22a connected in the positive direction of the first direction X (left side in the drawing) via the bottom 31 of the concave portion 30 and the second wall portion 22b connected in the negative direction of the first direction X (right side in the drawing) via the bottom 31 of the concave portion 30 in the triangular wave structure 10 will be described. With the above-described configuration, when the normal to the third direction Z is taken as a reference and the bottom 31 of the recess 30 is the center, the first wall portion 22a is inclined counterclockwise by an angle of 0° or more. Furthermore, when the normal to the third direction Z is taken as a reference and the bottom 31 of the recess 30 is the center, the second wall portion 22b is inclined clockwise by an angle of 0° or more. Furthermore, with the above-described configuration, the bottom 31 of the recess 30 is located at the same position in the first direction X as the convex portions 20 that are continuous in the positive direction of the first direction X of the recess 30, or in the negative direction. Furthermore, the bottom 31 of the recess 30 is located at the same position in the first direction X as the convex portions 20 that are continuous in the negative direction of the first direction X of the recess 30, or in the positive direction. This causes the first wall portion 22a to tilt clockwise at an angle greater than 0° with respect to the normal to the third direction Z, centered on the bottom 31 of the recess 30, so that the first wall portion 22a is positioned in the positive direction of the third direction Z (upper side in the figure) of the bottom 31 of the recess 30, and the top 21 of the protrusion 20, which is continuous in the positive direction of the first direction X of the recess 30, is positioned in the negative direction of the first direction X relative to the bottom 31 of the recess 30, preventing the protrusion 20 from overhanging the recess 30.Furthermore, it is possible to prevent a state in which the second wall portion 22b is inclined counterclockwise at an angle greater than 0° with respect to the normal to the third direction Z, with the bottom portion 31 of the recess 30 as the center, so that the second wall portion 22b is located in the positive direction of the third direction Z of the bottom portion 31 of the recess 30 (upper side in the figure), and the top portion 21 of the convex portion 20 that is continuous with the recess 30 in the negative direction of the first direction X is located in the positive direction of the first direction X relative to the bottom 31 of the recess 30, thereby preventing the convex portion 20 from overhanging the recess 30. Preventing such an overhanging state prevents an increase in reflected light by the first wall portion 22a or the second wall portion 22b of the convex portion 20 on the non-overhanging side of the convex portions 20, 20 on both sides that are continuous with the overhanging recess 30, thereby reducing color unevenness.

[0020] The first wall portion 22a and the second wall portion 22b may be flat as shown in Fig. 1. The first wall portion 22a and the second wall portion 22b may not have, for example, multiple protrusions and multiple recesses.

[0021] As described above, in this embodiment, the peaks 21 and bottoms 31 may have substantially no flat portions parallel to the first direction X, and the triangular wave structure 10 may have a repeated uneven structure consisting of slopes (walls 22) connecting the peaks 21 of the convex portions 20, the concave portions 30, and the bottoms 31. This configuration makes it easier to suppress the effect of specular reflection on the flat portions on color unevenness. The peaks 21 and bottoms 31 having substantially no flat portions may mean that the length of the flat portions occupies 10% or less, 5% or less, 1% or less, or 0% of the length of the triangular wave structure 10 in the first direction X.

[0022] The average height of the plurality of protrusions 20 may be 1 mm or more and 30 mm or less. By making the average height 1 mm or more, it is possible to manufacture a member for suppressing unevenness in appearance 1 that has excellent formability, even for large members. Furthermore, by making the average height 30 mm or less, it is possible to prevent the protrusions 20 from becoming sharp, and to manufacture a member for suppressing unevenness in appearance 1 that is highly safe. The average height may be 1.5 mm or more, or 2 mm or more. The average height may be 20 mm or less, 10 mm or less, 5 mm or less, or 3 mm or less.

[0023] The average height of the plurality of protrusions 20 can be obtained by calculating the average value of the heights H of at least 10 consecutively arranged protrusions 20. The height H of the protrusions 20 can be obtained by dropping a perpendicular line from a line connecting the bottoms 31 of the recesses 30 on both sides adjacent to the protrusion 20 to be measured to the top 21 of the protrusion 20 and measuring the length of the perpendicular line. The height H of the protrusions 20 can be measured using an observation image of the cross section of the triangular wave structure 10.

[0024] In this specification, an observation image of the cross section of the triangular wave structure 10 can be obtained by embedding the triangular wave structure 10 in an embedding material such as epoxy resin, and then polishing the embedded triangular wave structure 10 to obtain a cross section sample using a microscope. As the microscope, for example, a Keyence microscope VHX-8000 can be used.

[0025] The height H of each of the multiple protrusions 20 may be substantially the same. With such a configuration, it is possible to uniformly suppress light reflection from the appearance unevenness suppression member 1. Note that, "the height H of each of the multiple protrusions 20 is substantially the same" may mean that the height H of each of the multiple protrusions 20 is between -20% and +20% of the average height of the multiple protrusions 20. The height H of each of the multiple protrusions 20 may be between -10% and +10%, between -5% and +5%, or between -1% and +1% of the average height of the multiple protrusions 20.

[0026] The average width of the multiple protrusions 20 may be greater than 0 mm and less than 60 mm. By making the average width of the multiple protrusions 20 greater than 0 mm, the protrusions 20 are prevented from becoming sharp, allowing for the manufacture of a highly safe member for suppressing unevenness in appearance 1. Furthermore, by making the average width less than 60 mm, it becomes easier to achieve a structure in which the included angle θ (described below) is smaller than the desired angle, thereby suppressing light reflection from the member for suppressing unevenness in appearance 1 and effectively suppressing unevenness in the member for suppressing unevenness in appearance 1. The average width may be greater than 0.5 mm or may be greater than 1 mm. The average width of the multiple protrusions 20 may be less than 50 mm, less than 40 mm, less than 30 mm, less than 20 mm, less than 10 mm, less than 5 mm, less than 3 mm, or less than 2 mm.

[0027] The average width of the plurality of protrusions 20 can be obtained by calculating the average value of the widths W1 of at least 10 consecutively arranged protrusions 20. In this specification, the width W1 of each protrusion 20 is the distance between two lines that are perpendicular to a line connecting the apexes 21 of the protrusions 20 on both sides adjacent to the protrusion 20 being measured and that pass through the bottoms 31 on both sides adjacent to the apex 21 of the protrusion 20 being measured. The width W1 of the protrusion 20 can be measured using an observation image of the cross section of the triangular wave structure 10.

[0028] The average depth of the multiple recesses 30 is 1 mm or more and 30 mm or less. By setting the average depth to 1 mm or more, it is possible to manufacture a member for suppressing unevenness in appearance 1 with excellent formability, even for large components. Furthermore, by setting the average depth to 30 mm or less, it is possible to prevent the protrusions 20 from becoming sharp, and to manufacture a member for suppressing unevenness in appearance 1 with high safety. The average depth may be 1.5 mm or more, or may be 2 mm or more. The average depth may be 20 mm or less, 10 mm or less, 5 mm or less, or 3 mm or less.

[0029] The average depth of the plurality of recesses 30 can be obtained by calculating the average value of the depths D of at least 10 consecutively arranged recesses 30. The depth D of the recess 30 can be obtained by drawing a perpendicular line from a line connecting the tops 21 of the protrusions 20 on both sides adjacent to the recess 30 to be measured to the bottom 31 of the recess 30, and measuring the length of the perpendicular line. The depth D of the recess 30 can be measured using a cross-sectional observation image of the triangular wave structure 10.

[0030] The depth D of each of the multiple recesses 30 is substantially the same. With this configuration, it is possible to uniformly suppress light reflection from the appearance unevenness suppression member 1. Note that, "the depth D of each of the multiple recesses 30 is substantially the same" may mean that the depth D of each of the multiple recesses 30 is between -20% and +20% of the average depth of the multiple recesses 30. The depth D of each of the multiple recesses 30 may be between -10% and +10%, between -5% and +5%, or between -1% and +1% of the average depth of the multiple recesses 30.

[0031] The average width of the multiple recesses 30 may be greater than 0 mm and less than or equal to 60 mm. By making the average width of the multiple recesses 30 greater than 0 mm, the protrusions 20 are prevented from becoming sharp, making it possible to produce a highly safe member for suppressing unevenness in appearance 1. Furthermore, by making the average width of the multiple recesses 30 less than or equal to 60 mm, it is possible to suppress light reflection from the member for suppressing unevenness in appearance 1, making it possible to effectively suppress unevenness in the appearance of the member for suppressing unevenness in appearance 1. The average width of the multiple recesses 30 may be greater than or equal to 0.5 mm, or may be greater than or equal to 1 mm. The average width of the multiple recesses 30 may be less than or equal to 50 mm, less than or equal to 40 mm, less than or equal to 30 mm, less than or equal to 20 mm, less than or equal to 10 mm, less than or equal to 5 mm, less than or equal to 3 mm, or less than or equal to 2 mm.

[0032] The average width of the plurality of recesses 30 can be obtained by calculating the average value of the widths W2 of at least 10 recesses 30 arranged in succession. In this specification, the width W2 of each recess 30 is the distance between two lines that are perpendicular to a line connecting the bottoms 31 of the recesses 30 on both sides adjacent to the recess 30 being measured and that pass through the apexes 21 on both sides adjacent to the bottom 31 of the recess 30 being measured. The width W2 of the recess 30 can be measured using an observation image of the cross section of the triangular wave structure 10.

[0033] In a cross-sectional view, the average value of the included angle θ, which is the angle of the inside of the recess 30 formed by the first wall portion 22a and the second wall portion 22b, is greater than 0° and less than 90°. By setting the average value of the included angle θ to 90° or less, it is possible to reduce the proportion of reflected light that exits the appearance unevenness suppression member 1 compared to a case in which the triangular wave structure 10 is not present. The average value of the included angle θ is preferably greater than 0° and less than 90°, more preferably greater than 0° and less than 70°, even more preferably greater than 0° and less than 60°, particularly preferably greater than 0° and less than 50°, and most preferably greater than 0° and less than 20°.

[0034] The average included angle θ can be obtained by calculating the average included angle θ of the bottoms 31 of at least 10 consecutively arranged recesses 30. Each included angle θ can be obtained by measuring the included angle θ at the corner where a tangent to the first wall portion 22a and a tangent to the second wall portion 22b, which are located on either side of the recess 30, intersect. The position where the tangent to the first wall portion 22a intersects is the midpoint between the apex 21 and the bottom 31 connected to the first wall portion 22a. The position where the tangent to the second wall portion 22b intersects is the midpoint between the apex 21 and the bottom 31 connected to the second wall portion 22b. The included angle θ can be measured using an observation image of the cross section of the triangular wave structure 10.

[0035] In a cross-sectional view, the average angle Φ of the apexes 21 may be greater than 0° and less than or equal to 90°. By making the average angle Φ of the apexes 21 less than or equal to 90°, the number of protrusions 20 per unit length can be increased. Furthermore, the average included angle θ is more likely to be less than or equal to 90°. This makes it possible to further suppress light reflection in the appearance unevenness suppression member 1. The average angle Φ of the apexes 21 is preferably less than 90°, more preferably greater than 0° and less than or equal to 70°, even more preferably less than or equal to 60°, particularly preferably less than or equal to 50°, and most preferably less than or equal to 20°.

[0036] The average value of the angle Φ of the apexes 21 can be obtained by calculating the average value of the angles Φ of the apexes 21 of at least 10 consecutively arranged protrusions 20. The angle Φ can be obtained by measuring the angle Φ at the corner where a tangent to the first wall 22a and a tangent to the second wall 22b, which are located on either side of the protrusion 20, intersect. The position at which the tangent to the first wall 22a is drawn is the midpoint between the apex 21 connected to the first wall 22a and the bottom 31. The position at which the tangent to the second wall 22b is drawn is the midpoint between the apex 21 connected to the second wall 22b and the bottom 31. The angle Φ can be measured using an observation image of the cross section of the triangular wave structure 10.

[0037] The angles Φ of the multiple protrusions 20 may all be substantially the same, or the angles Φ of at least two of the multiple protrusions 20 may be different, or the angles Φ of the multiple protrusions 20 may all be different. The angles Φ of the multiple protrusions 20 may all be greater than 0° and less than or equal to 90°. The included angles θ of the multiple recesses 30 may all be substantially the same, or the included angles θ of at least two of the multiple recesses 30 may be different, or the included angles θ of the multiple recesses 30 may all be different. The included angles θ of the multiple recesses 30 may all be greater than 0° and less than or equal to 90°. Even in these configurations, the appearance unevenness suppressing member 1 can suppress appearance unevenness.

[0038] Note that "the angles Φ of the plurality of protrusions 20 are all substantially the same" may mean that all angles Φ are -20% to +20% or -10% to +10% or -5% to +5% or -1% to +1% of the average value of the angles Φ of the plurality of protrusions 20. Similarly, "the included angles θ of the plurality of recesses 30 are all substantially the same" may mean that all included angles θ are -20% to +20% or -10% to +10% or -5% to +5% or -1% to +1% of the average value of the included angles θ.

[0039] The angle formed by a line perpendicular to a line segment connecting the bottoms 31 of adjacent recesses 30 and a line tangent to the midpoint of first wall portion 22a may be greater than 0° and less than 45°. By setting the angle within this range, the proportion of reflected light that exits the appearance unevenness suppression member 1 can be further reduced compared to a case in which the triangular wave structure 10 is not present. The angle may be greater than 0° and less than 45°, greater than 0° and less than 30°, greater than 0° and less than 25°, or greater than 0° and less than 10°.

[0040] The angle formed by a line perpendicular to a line segment connecting the bottoms 31 of adjacent recesses 30 and a line tangent to the midpoint of second wall portion 22b may be greater than 0° and less than 45°. By setting the angle within this range, the proportion of reflected light that exits the appearance unevenness suppression member 1 can be further reduced compared to a case in which the triangular wave structure 10 is not present. The angle may be greater than 0° and less than 45°, greater than 0° and less than 30°, greater than 0° and less than 25°, or greater than 0° and less than 10°.

[0041] In a cross-sectional view, the length of the first wall portion 22a and the length of the second wall portion 22b may be substantially the same. Such a configuration makes it easier to prevent the occurrence of the above-mentioned overhang, and can effectively suppress light reflection from the appearance unevenness suppression member 1. Note that the length of the first wall portion 22a and the length of the second wall portion 22b being substantially the same may mean that the length of the first wall portion 22a is between -20% and +20% of the length of the second wall portion 22b. The length of the first wall portion 22a may be between -10% and +10%, between -5% and +5%, or between -1% and +1% of the length of the second wall portion 22b.

[0042] It is preferable that all of the interior angles of the triangle formed by connecting the apex 21 and the bottoms 31 of the recesses 30 on both sides of the apex 21 are acute angles. With this configuration, it is possible to effectively suppress light reflection from the appearance unevenness suppression member 1. The magnitude of the largest interior angle of the three interior angles of the triangle may be greater than 45° and less than 90°, greater than 50° and less than 90°, greater than 55° and less than 90°, greater than 60° and less than 90°, greater than 65° and less than 90°, or greater than 70° and less than 90°.

[0043] The triangular wave structure 10 is formed of pure aluminum or an aluminum alloy. The purity of the pure aluminum may be 99.00% by mass or more, 99.50% by mass or more, 99.80% by mass or more, 99.99% by mass or more, or 99.995% by mass or more. The pure aluminum may contain elements other than aluminum (Al). The elements other than aluminum contained in the pure aluminum may include one or more of silicon (Si), iron (Fe), copper (Cu), manganese (Mn), magnesium (Mg), chromium (Cr), zinc (Zn), titanium (Ti), vanadium (V), gallium (Ga), nickel (Ni), boron (B), zirconium (Zr), and the like. The content of each element other than aluminum contained in the pure aluminum may be less than 1% by mass, less than 0.1% by mass, or less than 0.01% by mass.

[0044] An aluminum alloy contains aluminum and elements other than aluminum. The elements other than aluminum contained in the aluminum alloy may include one or more of silicon (Si), iron (Fe), copper (Cu), manganese (Mn), magnesium (Mg), chromium (Cr), zinc (Zn), titanium (Ti), vanadium (V), gallium (Ga), nickel (Ni), boron (B), zirconium (Zr), etc. The total content of the elements other than aluminum contained in the aluminum alloy may be more than 1 mass%. The total content of the elements other than aluminum contained in the aluminum alloy may be 10 mass% or less, or may be 5 mass% or less. The content of each of the elements other than aluminum contained in the aluminum alloy may be 10 mass% or less, or may be 1 mass% or less. Hereinafter, at least one of pure aluminum and an aluminum alloy will be simply referred to as aluminum.

[0045] In the embodiment shown in FIG. 1, the apex 21 has an acute angle, i.e., an angular shape. However, as shown in FIG. 2, the apex 21 may have an arc shape. Furthermore, the apex 21 may have a curved shape with an R. When the apex 21 has an arc shape, the average radius of curvature of the apex 21 may be 0.2 mm or more and 12 mm or less. When the average radius of curvature of the apex 21 is 0.2 mm or more, an appearance unevenness suppressing member 1 with excellent moldability can be manufactured. When the average radius of curvature of the apex 21 is 12 mm or less, the average width of the protrusions 20 can be reduced to prevent the protrusions 20 from becoming sharp, and a highly safe appearance unevenness suppressing member 1 can be manufactured.

[0046] In the embodiment shown in FIG. 1 , the bottom 31 has an acute angle, i.e., an angular shape. However, as shown in FIG. 2 , the bottom 31 may have an arc shape. Furthermore, the bottom 31 may have a curved shape with an R. When the bottom 31 has an arc shape, the average radius of curvature of the bottom 31 may be 0.2 mm or more and 12 mm or less. When the average radius of curvature of the bottom 31 is 0.2 mm or more, the appearance unevenness suppressing member 1 can be easily manufactured by extrusion molding. Furthermore, when the average radius of curvature of the bottom 31 is 12 mm or less, the average width of the multiple recesses 30 can be reduced to suppress light reflection from the appearance unevenness suppressing member 1, thereby effectively suppressing unevenness in the appearance of the appearance unevenness suppressing member 1.

[0047] The average radius of curvature of the convex portions 20 can be obtained by calculating the average value of the radii of curvature of at least 10 consecutively arranged apexes 21. The average radius of curvature of the bottom portions 31 can be obtained by calculating the average value of the radii of curvature of at least 10 consecutively arranged bottom portions 31. The radii of curvature of the apexes 21 and the bottom portions 31 can be measured using image processing software such as Click Measure on an observed image of the cross section of the triangular wave structure 10.

[0048] 1, the wall portion 22 is linear. However, as shown in FIG. 3, the first wall portion 22a and the second wall portion 22b may be curved so as to bulge toward the adjacent recessed portion 30. That is, the first wall portion 22a and the second wall portion 22b may protrude so as to constrict the protruding portion 20. Even in such a configuration, the appearance unevenness suppressing member 1 can suppress appearance unevenness.

[0049] In a plan view, the plurality of protrusions 20 and the plurality of recesses 30 may be formed parallel to one another and extend linearly in a second direction Y perpendicular to the first direction X in which the protrusions 20 and the recesses 30 are alternately arranged. Such an appearance unevenness suppressing member 1 has excellent formability and is particularly suitable for extrusion molding. Therefore, an appearance unevenness suppressing member 1 can be produced inexpensively with high productivity.

[0050] The triangular wave structure 10 according to this embodiment may have the convex portions 20 and the concave portions 30 arranged alternately and continuously in a cross-sectional view. Therefore, the triangular wave structure 10 may include a single spiral convex portion 20 when viewed from a third direction Z perpendicular to the first direction X and the second direction Y, with a single concave portion 30 provided between adjacent convex portions 20. Even in this form, the convex portions 20 and the concave portions 30 are arranged alternately and continuously in a cross-sectional view. Therefore, by setting the average value of the included angle θ to be greater than 0° and equal to or less than 90°, it is possible to suppress unevenness in appearance.

[0051] In the above-described embodiment, the protrusions 20 and recesses 30, each including the first wall portion 22a and the second wall portion 22b, are alternately and continuously arranged in a cross-sectional view. The appearance unevenness suppression member 1 may be any member as long as it has a triangular wave structure 10 having a predetermined included angle formed by the first wall portion 22a and the second wall portion 22b. For example, the protrusions 20 may have a hollow shape that includes the first wall portion 22a and the second wall portion 22b in its outer shape. In other words, the protrusions 20 may have a triangular wave plate shape that includes the first wall portion 22a and the second wall portion 22b.

[0052] In the second direction Y in which the convex portions 20 and concave portions 30 extend, the total length of the triangular wave structure 10 may be 1 m or more. An appearance unevenness suppression member 1 of this size is suitable for suppressing appearance unevenness in large components such as building components. In the second direction Y, the total length of the triangular wave structure 10 may be 1 cm or more, 10 cm or more, 30 cm or more, or 50 cm or more. Furthermore, in the second direction Y, the total length of the triangular wave structure 10 may be 50 m or less, 10 m or less, 5 m or less, or 1 m or less.

[0053] In the first direction X, in which the convex portions 20 and concave portions 30 are alternately arranged, the total length of the triangular wave structure 10 may be 1 cm or more. An appearance unevenness suppression member 1 of this size is suitable for suppressing appearance unevenness in large components such as building components. In the first direction X, the total length of the triangular wave structure 10 may be 1 cm or more, 5 cm or more, 10 cm or more, or 20 cm or more. Furthermore, in the first direction X, the total length of the triangular wave structure 10 may be 1 m or less, 50 cm or less, 40 cm or less, or 30 cm or less.

[0054] The appearance unevenness suppressing member 1 may be an extruded material. Extruded materials can be continuously molded and have high productivity, so the appearance unevenness suppressing member 1 can be mass-produced inexpensively. Furthermore, when the appearance unevenness suppressing member 1 is an extruded material, it is possible to form large components such as building components. Furthermore, since an extruded material can be formed simply by extrusion, it is suitable for producing an appearance unevenness suppressing member 1 in which the total length of the triangular wave structure 10 in the second direction Y is 1 m or more, as described above.

[0055] The member for suppressing unevenness in appearance 1 includes an aluminum base material 40. By including the aluminum base material 40 in the member for suppressing unevenness in appearance 1, it is possible to provide a member for suppressing unevenness in appearance 1 that is easy to mold by extrusion and easy to handle.

[0056] The aluminum base 40 contains pure aluminum or an aluminum alloy. The pure aluminum or aluminum alloy (hereinafter also referred to as aluminum) contained in the aluminum base 40 can be the same as those exemplified for the triangular wave structure 10.

[0057] The thickness and shape of the aluminum base 40 are not particularly limited and can be changed appropriately depending on the application. For example, the aluminum base 40 may be plate-shaped. The thickness of the aluminum base 40 may be, for example, 0.1 mm to 30 mm, 1 mm to 20 mm, or 5 mm to 10 mm.

[0058] As shown in FIG. 4, the member for suppressing unevenness in appearance 1 includes an anodized film 50 formed on the surface of an aluminum base material 40. The anodized film 50 contains aluminum oxide. The anodized film 50 is formed as the outermost layer of the member for suppressing unevenness in appearance 1 and may be exposed to the outside. By providing the member for suppressing unevenness in appearance 1 with the anodized film 50, it is possible to improve corrosion resistance, wear resistance, and the like.

[0059] The refractive index of the anodized coating 50 may be 1.4 or more and 1.8 or less. When the refractive index of the anodized coating 50 is within the above range, it becomes close to the refractive index of a coating film such as the electrodeposition coating film 60. This reduces the refractive index difference between the refractive index of the anodized coating 50 and the refractive index of the electrodeposition coating film 60, thereby reducing light reflection between the anodized coating 50 and the electrodeposition coating film 60. The refractive index of the anodized coating 50 may be 1.4 or more and 1.6 or less. In this specification, the refractive index is a value measured using an Abbe refractometer in accordance with JIS K0062-1992, "Methods for measuring solid samples."

[0060] The thickness of the anodic oxide coating 50 is not particularly limited, but is preferably more than 5 μm and not more than 50 μm. By making the thickness of the anodic oxide coating 50 more than 5 μm, corrosion of the aluminum base material 40 can be effectively suppressed. Furthermore, by making the thickness of the anodic oxide coating 50 not more than 50 μm, the productivity of the appearance unevenness suppressing member 1 can be improved. The anodic oxide coating 50 has a barrier layer 51 and a porous layer 52.

[0061] The barrier layer 51 is provided on the surface of the aluminum substrate 40. The barrier layer 51 is a dense, non-porous layer and contains aluminum oxide. The anodized film 50 may contain components derived from the anodizing electrolyte in addition to aluminum and oxygen. The thickness of the barrier layer 51 is not particularly limited, but may be, for example, more than 0 nm, 1 nm or more, or 10 nm or more. The thickness of the barrier layer 51 may also be 60 nm or less, 30 nm or less, or 20 nm or less.

[0062] The porous layer 52 is provided on the surface of the barrier layer 51. Specifically, the porous layer 52 may be disposed on the opposite side of the barrier layer 51 from the aluminum substrate 40. The porous layer 52 contains aluminum oxide. In addition to aluminum and oxygen, the porous layer 52 may contain components derived from the anodizing electrolyte. The thickness of the porous layer 52 is not particularly limited, but may be more than 5 μm and not more than 50 μm. By setting the thickness of the porous layer 52 within the above range, good coloring can be achieved when electrolytic coloring is performed.

[0063] The porous layer 52 has a plurality of pores. The pores of the porous layer 52 may extend in the thickness direction. The pores of the porous layer 52 may include at least one of a plurality of straight-chain pores and a plurality of branched pores. The straight-chain pores may extend in a straight chain shape in the thickness direction of the porous layer 52. The branched pores may be branched pores.

[0064] The average pore size of the pores in the porous layer 52 may be in the range of 5 nm to 350 nm. The average pore size of the pores in the porous layer 52 may be 20 nm or more, or 50 nm or more. The average pore size of the porous layer 52 may be 300 nm or less, 200 nm or less, or 150 nm or less. In this specification, the average pore size is the average value obtained by observing the cross section of the appearance unevenness suppression member 1 with an electron microscope and measuring 10 or more pores.

[0065] The porous layer 52 is provided with a colored layer 53 containing at least one of a metal, a metal salt, a dye, a pigment, and an organic acid. By providing the colored layer 53 on the porous layer 52, the design of the appearance unevenness suppression member 1 can be improved. Examples of the colored layer 53 include an electrolytic colored layer, an organic dyed layer, an inorganic dyed layer, an alloy colored layer, and an electrolytic colored layer. The electrolytic colored layer is a layer colored by depositing a metal or a metal salt in the pores of the anodized coating 50. The organic dyed layer is a layer colored by adsorbing an organic dye or an organic pigment on the surface or pores of the anodized coating 50. The inorganic dyed layer is a layer colored by adsorbing an inorganic dye or an inorganic pigment on the surface or pores of the anodized coating 50. The alloy colored layer is a layer colored by depositing a metal (alloy element) contained in an aluminum alloy in the anodized coating 50. The electrolytic coloring layer is a layer colored by depositing an organic acid as an electrolyte contained in the electrolytic solution used for anodization in the anodized coating 50. The coloring layer 53 can be formed by a known coloring method. The electrolytic coloring layer can be formed by a known electrolytic coloring method, the organic coloring layer can be formed by a known organic coloring method, the inorganic coloring layer can be formed by a known inorganic coloring method, the alloy coloring layer can be formed by a known alloy coloring method, and the electrolytic coloring layer can be formed by a known electrolytic coloring method. Hereinafter, this embodiment will be described by exemplifying a case in which the electrolytic coloring layer 53 is provided as the coloring layer 53. Furthermore, in the manufacturing method of a member for suppressing appearance unevenness described below, the coloring step of forming the coloring layer 53 will be described by exemplifying a case in which an electrolytic coloring step of forming the electrolytic coloring layer 53 is performed.

[0066] The electrolytic coloring layer 53 is a layer in which a metal or metal salt is deposited in a plurality of pores of the porous layer 52. The metal or metal salt may fill at least a portion of the pores of the porous layer 52, or may fill all of the pores of the porous layer 52. The concentration of the metal or metal salt in the region of the pores on the aluminum substrate 40 side may be the same as or higher than the region of the pores of the porous layer 52 on the opposite side of the aluminum substrate 40.

[0067] The thickness of the electrolytic colored layer 53 may be 2 μm or more. When the thickness of the electrolytic colored layer 53 is 2 μm or more, an appearance unevenness suppressing member 1 having good coloring properties can be provided. The thickness of the electrolytic colored layer 53 may be 3 μm or more. Furthermore, the upper limit of the thickness of the electrolytic colored layer 53 is not particularly limited, but may be the same as the upper limit of the thickness of the porous layer 52. Specifically, the thickness of the porous layer 52 may be 50 μm or less.

[0068] The metal and metal salt may contain at least one selected from the group consisting of Ni, Co, Cu, Sn, Mn, Fe, Pb, Ca, Zn, and Mg. This allows the appearance unevenness suppression member 1 to have an off-gray appearance color. The metal salt may contain at least one of an organic acid salt and an inorganic acid salt. The organic acid salt may contain at least one selected from the group consisting of oxalate, acetate, and tartrate. The inorganic acid salt may contain at least one selected from the group consisting of nitrate, sulfate, phosphate, hydrochloride, and chromate.

[0069] As shown in Fig. 4, the member for suppressing unevenness in appearance 1 may have an electrodeposition coating film 60 on an anodized coating film 50. By providing the member for suppressing unevenness in appearance 1 with the electrodeposition coating film 60, it is possible to improve corrosion resistance, abrasion resistance, and the like. Specifically, the electrodeposition coating film 60 is provided on the side of the anodized coating film 50 opposite the aluminum base material 40. The electrodeposition coating film 60 is provided as the outermost layer of the member for suppressing unevenness in appearance 1, and may be exposed to the outside. There are no particular limitations on the film thickness of the electrodeposition coating film 60, but it may be, for example, 5 µm to 20 µm.

[0070] The electrodeposition coating film 60 may contain at least one resin selected from the group consisting of acrylic resin, melamine resin, epoxy resin, and fluororesin. The electrodeposition coating film 60 may be, for example, a resin containing acrylic resin and melamine resin, or a resin in which acrylic resin is crosslinked with melamine resin.

[0071] The refractive index of the electrodeposition coating film 60 may be 1.4 or more and 1.8 or less. When the refractive index of the electrodeposition coating film 60 is within the above range, it is close to the refractive index of the electrodeposition coating film 60. Therefore, the refractive index difference between the refractive index of the anodized coating film 50 and the refractive index of the electrodeposition coating film 60 is reduced, thereby reducing light reflection between the anodized coating film 50 and the electrodeposition coating film 60. Furthermore, by setting the refractive index of the anodized coating film 50 to 1.8 or less, total reflection on the surface of the electrodeposition coating film 60 can be suppressed. The refractive index of the anodized coating film 50 may be 1.4 or more and 1.6 or less. The refractive index difference between the refractive index of the anodized coating film 50 and the refractive index of the electrodeposition coating film 60 may be 0.2 or less, 0.1 or less, or 0.05 or less. In this specification, the refractive index is a value measured using an Abbe refractometer in accordance with JIS K0062-1992, "Methods for measuring solid samples."

[0072] An anodized coating composite film may be applied to the appearance unevenness suppression member 1. As specified in JIS H8602:2010, the anodized coating composite film is a film formed by anodizing aluminum or an aluminum alloy to form an anodized coating film 50 with an average thickness of 5 μm or more, and then applying a coating such as an electrodeposition coating film 60.

[0073] L of the appearance unevenness suppression member 1 measured from the triangular wave structure 10 side * a * b * L in color space * The value is between 0 and 40, and a * The value is between -15 and +15, and b * The value can be between -15 and +15. * value, a * value and b * When the value is within the above range, the appearance unevenness of the appearance unevenness suppressing member 1 can be further suppressed. * a * b * L in color space * value, a * value and b *The value can be calculated in accordance with JIS Z8781-4:2013 (Colorimetry - Part 4: CIE 1976 L*a*b* color space). * a * b * L in color space * value, a * value and b * The value is L under the geometric condition c (di: 8°) specified in JIS Z8781-4:2013. * a * b * can be measured using a color difference meter such as the Konica Minolta CR-400. * a * b * L in color space * value, a * value and b * The value conforms to the geometric condition c of JIS Z8722:2009 (the irradiated light includes a component that is specularly reflected from the sample), and can be measured under the conditions of a diffuse illumination, perpendicular light receiving method, and D65 light source.

[0074] The appearance unevenness suppressing member 1 may be a building material, an optical member, a vehicle member, or a civil engineering member. By using the appearance unevenness suppressing member 1 for these applications, it is possible to suppress the appearance unevenness of these members. Examples of building materials include interior and exterior materials and roofing materials for buildings such as buildings, houses, facilities, and warehouses. Examples of optical members include the barrels of cameras and telescopes. Examples of vehicle members include passenger cars, freight trucks, and trains. Examples of civil engineering members include bridges, balustrades, guardrails, and permanent scaffolding.

[0075] [2. Composite materials] The composite member according to this embodiment includes multiple appearance unevenness suppression members 1. The multiple appearance unevenness suppression members 1 have surfaces, on which triangular wave structures 10 are arranged, lined up in a row on the same plane. In the composite member, the appearance unevenness suppression members 1 may each have a different BRDF (bidirectional reflectance distribution function). The BRDF varies depending on the color tone and surface structure of the appearance unevenness suppression member 1. Because the appearance unevenness suppression members 1 can suppress appearance unevenness, a composite member with suppressed appearance unevenness can be provided even if appearance unevenness suppression members 1 with different BRDFs are used. The composite member may be a building material, optical member, vehicle member, or civil engineering member as described above. The composite member may include multiple appearance unevenness suppression members 1, and may include 2 or more, 3 or more, 5 or more, 10 or more, 20 or more, or 50 or more. The composite member may include 100 or less appearance unevenness suppression members 1.

[0076] [3. Manufacturing method of components for suppressing uneven appearance] Next, a description will be given of a method for manufacturing the member for suppressing unevenness in appearance 1. The method for manufacturing the member for suppressing unevenness in appearance 1 may include an extrusion step, an anodizing step, an electrolytic coloring step, and an electrodeposition coating step.

[0077] <Extrusion process> The extrusion process is a process of forming an aluminum base material 40 having a triangular wave structure 10 by extrusion. As described above, the appearance unevenness suppression member 1 according to this embodiment has excellent extrusion processability, and therefore the aluminum base material 40 can be easily manufactured by the extrusion process. In the extrusion process, first, a billet is prepared by casting molten aluminum. If necessary, the billet may be subjected to a homogenization process or the like to homogenize the concentrations of metal components contained in the aluminum.

[0078] In the extrusion process, the billet is extruded so that it passes through a die. After being extruded from the die, the extruded material is cooled and may be subjected to aging treatment, etc., as needed. The extrusion conditions, such as the billet temperature, die temperature, container temperature, extrusion pressure, and extrusion speed, are not particularly limited and may be adjusted appropriately depending on the aluminum composition, the shape of the appearance unevenness suppression member 1, and the like.

[0079] <Anodizing process> In the anodizing process, the extruded member is anodized to form an anodized film 50 on the surface of the aluminum base material 40. In the anodizing process, for example, an anode on which the extruded member is placed and a cathode on which stainless steel (SUS) is placed are immersed in an electrolytic solution to perform electrolysis. The electrolytic solution used in the anodizing process is not particularly limited, and any known electrolytic solution can be used.

[0080] The electrolyte may be an electrolyte containing an organic acid or an electrolyte containing an inorganic acid. The electrolyte containing an organic acid may be an electrolyte containing at least one selected from the group consisting of acids having a carboxyl group and salts thereof. The electrolyte containing an inorganic acid may be an electrolyte containing at least one selected from the group consisting of sulfuric acid, phosphoric acid, boric acid, chromic acid, and salts thereof. Examples of these salts include ammonium salts, sodium salts, potassium salts, and silicates. The acid having a carboxyl group may include at least one selected from the group consisting of citric acid, adipic acid, oxalic acid, maleic acid, tartaric acid, malonic acid, and salicylic acid.

[0081] The conditions for anodization are not particularly limited. For example, the electrolysis temperature may be 0°C or higher, 10°C or higher, 20°C or higher, 30°C or higher, 40°C or higher, or 50°C or higher. The electrolysis temperature may be 70°C or lower, 60°C or lower, or 50°C or lower. Anodization may be performed using a DC power supply or an AC power supply. The electrolysis voltage varies depending on the type of electrolyte, but may be 0.1V or higher or 1V or higher. The electrolysis voltage varies depending on the type of electrolyte, but may be 500V or lower or 400V or lower. The electrolysis time may be 0.1 minutes or longer or 1 minute or longer. The electrolysis time may be 60 minutes or shorter or 20 minutes or shorter. Anodization may be performed in a single step or may be performed in multiple separate steps.

[0082] <Electrolytic coloring process> The electrolytic coloring step is a step of performing electrolytic coloring in an aqueous solution containing metal ions to form the electrolytic colored layer 53. Specifically, the electrolytic coloring step is a step of electrolyzing the appearance unevenness suppressing member 1 having the anodized coating 50 formed thereon with direct current or alternating current in an electrolyte solution to deposit metal or metal salt in the pores of the porous layer 52, thereby forming the electrolytic colored layer 53.

[0083] The electrolyte used in the electrolytic coloring process may be an aqueous solution containing metal ions. The metal ions contained in the electrolyte may include at least one selected from the group consisting of Ni, Co, Cu, Sn, Mn, Fe, Pb, Ca, Zn, and Mg. This allows the appearance unevenness suppression member 1 to have an off-gray appearance color. The electrolyte may include at least one of an organic acid salt and an inorganic acid salt. The organic acid salt may include at least one selected from the group consisting of oxalate, acetate, and tartrate. The inorganic acid salt may include at least one selected from the group consisting of nitrate, sulfate, phosphate, hydrochloride, and chromate. The electrolyte used in the electrolytic coloring process may be, for example, a nickel sulfate solution.

[0084] The conditions for electrolytic coloring are not particularly limited. For example, the electrolysis temperature may be 5°C or higher and 35°C or lower. The electrolysis voltage may be 5V or higher and 20V or lower. The electrolysis voltage is preferably lower than the electrolysis voltage in the anodization step. The electrolysis voltage may be, for example, 5V or higher and 20V or lower, or 10V or higher and 18V or lower. The electrolysis time and the like may be adjusted appropriately depending on the degree of coloring and the like.

[0085] <Electrodeposition coating process> The electrodeposition coating process is a process that follows the electrolytic coloring process, in which electrodeposition coating is performed on the aluminum substrate 40 to form an electrodeposition coating film 60 on the anodized film 50. The electrodeposition components in the electrodeposition paint are electrodeposited onto the anodized film 50 and then cured to form the electrodeposition coating film 60. The electrodeposition paint may be either a cationic electrodeposition paint or an anionic electrodeposition paint, with anionic electrodeposition paint being preferred. The electrodeposition paint may be, for example, an emulsion in which particles of melamine resin as a crosslinking agent encapsulated in acrylic resin as a base resin are dispersed in a solvent. The curing conditions for the electrodeposition components are not particularly limited and may be changed as appropriate depending on the type of electrodeposition paint, etc.

[0086] As described above, the triangular wave structure 10 of the appearance unevenness suppression member 1 according to this embodiment can be formed by extrusion molding. However, the triangular wave structure 10 of the appearance unevenness suppression member 1 can also be formed by cutting processes such as laser processing or end mill processing, press processing, etc., in addition to extrusion molding.

[0087] The anodized coating 50 may or may not be sealed. For example, the sealing may be performed after the anodizing step and before the electrodeposition coating step. The sealing may be performed using boiling water or a sealing agent such as a nickel compound.

[0088] [4. Light reflection suppression mechanism of appearance unevenness suppression material] Next, we will explain the mechanism by which reflected light can be reduced by the triangular wave structure 10 in which convex portions 20 and concave portions 30 are alternately and continuously arranged. In the above explanation, the angle conditions are expressed in degrees, but in the following explanation of the light reflection suppression mechanism of the appearance unevenness suppression member and the light reflection suppression mechanism using changes in refractive index, the angle conditions will be expressed in radians (arc degree system).

[0089] When light is incident on the appearance unevenness suppression member 1 having a triangular wave structure 10 in which convex portions 20 and concave portions 30 are alternately arranged, the incident light strikes the wall portions 22 of the concave portions 30 and undergoes a first specular reflection from the wall portions 22, generating a first reflected light. When the first reflected light strikes the wall portions 22 again, a second specular reflection occurs, generating a second reflected light. In this manner, the reflected light repeatedly strikes the wall portions 22, generating diffuse reflection components and being absorbed by the wall portions 22, thereby reducing the intensity of the reflected light. On the other hand, when the first reflected light does not strike the wall portions 22 and exits the appearance unevenness suppression member 1, it is observed by an observer positioned in front of the appearance unevenness suppression member 1 as reflected light from the appearance unevenness suppression member 1. As the amount of the first reflected light component, which has a weak degree of intensity reduction, increases, it becomes more easily noticeable as appearance unevenness between the appearance unevenness suppression members 1.

[0090] The probability function f(θ) can be expressed as the probability function that the first reflected light generated from the triangular wave structure 10 having an included angle θ will exit the appearance unevenness suppression member 1. Specifically, the relationship between the sum of line segments through which the first reflected light can exit the appearance unevenness suppression member 1 when the included angle θ is 180° and the sum of line segments through which the first reflected light can exit the appearance unevenness suppression member 1 when the included angle θ is 180° can be expressed as the probability function f(θ). In other words, the relationship between the sum of line segments through which the first reflected light can exit the appearance unevenness suppression member 1 when the included angle θ is 180° and the sum of line segments through which the first reflected light is maximized (θ=180°) can be expressed as the probability function f(θ).

[0091] The appearance unevenness suppression member 1 according to this embodiment is provided with a triangular wave structure 10 having an included angle θ in the range of 0°<θ<90°, so that the numerical value of the probability function f(θ) of the first reflected light escaping the appearance unevenness suppression member 1 is 0.6 or less. In other words, compared to when the appearance unevenness suppression member 1 is flat (θ=180°), the rate at which the first reflected light escaping the appearance unevenness suppression member 1 can be reduced to 60% or less. Therefore, the appearance unevenness of the appearance unevenness suppression member 1 can be suppressed.

[0092] Furthermore, the member for suppressing unevenness in appearance 1 according to this embodiment is formed with a triangular wave structure 10 on the order of millimeters, in which convex portions 20 and concave portions 30 are alternately arranged in succession. Therefore, a large member for suppressing unevenness in appearance 1 can be manufactured by extrusion, and can also be mass-produced.

[0093] Next, a more detailed description will be given of the mechanism by which reflected light can be reduced by the triangular wave structure 10 in which the convex portions 20 and the concave portions 30 are alternately and continuously arranged. Specifically, the probability function f(θ) of the first reflected light escaping the appearance unevenness suppression member 1 will be described.

[0094] [1] When 0≦θ<π / 2 As shown in Figure 5, the bottom of the recess is represented by point A, the apex of one protrusion is represented by point B, and the apex of the other protrusion is represented by point C, and the wall is represented by line segments AC and AB. The perpendicular line drawn from point B to line segment AC is represented by line segment BP. A point on line segment CP is represented by point Q. The included angle of the recess is represented by θ. For incident light L1 that passes through point B and enters between line segment CP, the angle formed by line segment BC and incident light L1 is represented by α. The angle of incidence of incident light L1 on line segment AC is represented by X.

[0095] Here, when incident light L1 is incident on line segment CQ at an incident angle X, if 0≦α≦θ / 2, the incident light L1 does not converge within the recess and is reflected outside the appearance unevenness suppression member as a first reflected light. The length of line segment CQ is expressed by equation (1).

[0096] Line segment CQ = Line segment AC - Line segment AP - Line segment PQ (1)

[0097] Here, it is assumed that the formula (2) holds true.

[0098] Line segment AC = Line segment AB = 1 (2)

[0099] Line segment AP = line segment AB × cosθ, and when equation (2) is substituted into this equation, the following equation (3) holds.

[0100] Line segment AP=cosθ (3)

[0101] Furthermore, from FIG. 5, the following formula (4) holds true. Line segment BQ×cosX = Line segment AB×sinθ (4)

[0102] Substituting equation (2) into equation (4) and converting it yields the following equation (5). Line segment BQ = (line segment AB × sinθ) / cosX = sinθ / cosX (5)

[0103] Furthermore, from FIG. 5, the following formula (6) holds true. Line segment PQ = Line segment BQ × sinX (6)

[0104] Substituting formula (5) into formula (6) and performing calculations, the following formula (7) is obtained. Line segment PQ = (sinθ / cosX) × sinX =(sinθ×sinX) / cosX =sinθ×tanX (7)

[0105] When formula (2), formula (3), and formula (7) are substituted into formula (1), the following formula (8) is obtained.

[0106] Line segment CQ=1-cosθ-sinθ×tanX (8)

[0107] Here, as shown in FIG. 6, the angle α varies within the range of 0 ≤ α ≤ θ / 2, and the incident angle X is expressed as X = θ / 2 - α. That is, the line segment CQ varies between 0 ≤ X ≤ θ / 2. Therefore, from Equation (8), the sum of the line segments that can be incident on the appearance unevenness suppressing member at the incident angle X is expressed by the following Equation (9).

[0108] [Number]

[0109] The above relationship also holds when the incident light and the reflected light are interchanged. Therefore, when Equation (9) is multiplied by 2, the following Equation (10) is obtained.

[0110] [Number]

[0111] [2] When π / 2 ≤ θ ≤ π When π / 2 ≤ θ ≤ π, when the incident light L1 incident at the incident angle X does not converge inside the appearance unevenness suppressing member and is reflected as the reflected light L2 to the outside of the appearance unevenness suppressing member, there are two cases: (1) 0 ≤ X ≤ θ - π / 2 and (2) θ - π / 2 < X ≤ π.

[0112] (1) When 0 ≤ X ≤ θ - π / 2 As shown in FIG. 7, when X = θ - π / 2, the incident light L1 is reflected at point A, and the reflected light L2 is reflected along the line segment AB. When X = θ - π / 2, the length that the incident light L1 can be reflected as the reflected light L2 to the outside of the appearance unevenness suppressing member without converging inside the appearance unevenness suppressing member is the same as the line segment AC shown in FIG. 8 and is 1. When 0 ≤ X ≤ θ - π / 2, the same can be said as above, so the sum of the line segments that can be incident at the incident angle X is expressed by the following Equation (11).

[0113] [Number]

[0114] Since the above relationship still holds even when the incident light and the reflected light are interchanged, multiplying Equation (11) by 2 gives the following Equation (12).

[0115] 2×(θ - π / 2) (12)

[0116] (2) When θ - π / 2 < X ≤ π As shown in FIG. 9, when the incident light L1 is incident on the line segment AQ, the reflected light L2 is blocked by the line segment AB. When the light is incident on the line segment CQ, the reflected light L2 is emitted outside the appearance unevenness suppressing member. Since the length of the line segment CQ is the same as Equation (8) when 0 ≤ θ < π / 2, the line segment CQ can be expressed as CQ = 1 - cosθ - sinθ × tanX. Since the line segment CQ changes between θ - π / 2 < X ≤ θ / 2, the total length of the line segments on which light can be incident at the incident angle X in the triangular wave structure with the included angle θ can be expressed by the following Equation (13).

[0117] [Number]

[0118] Since the above relationship still holds even when the incident light and the reflected light are interchanged, multiplying Equation (13) by 2 gives, as shown in the following Equation (14), the total length of the line segments on which light can be incident at the incident angle X in the structure with the included angle θ when θ - π / 2 < X ≤ π.

[0119] [Number]

[0120] When π / 2 ≤ θ ≤ π, the total length of the line segments on which light can be incident at the incident angle X in the structure with the included angle θ is the sum of two cases: (1) 0 ≤ X ≤ θ - π / 2 and (2) θ - π / 2 < X ≤ π. Therefore, adding Equation (12) and Equation (14) gives, as shown in the following Equation (15), the total length of the line segments on which light can be incident at the incident angle X in the structure with the included angle θ when π / 2 ≤ θ ≤ π.

[0121]

number

[0122] The length of the line segment that can be incident is maximum when θ = π, and is 1 for any incident angle X. The total length of the line segments that light can be incident on when θ = π is given by the following formula (16), which agrees with the result of substituting θ = π into formula (15).

[0123]

number

[0124] [3] Correction coefficient So far we have explained the included angle θ, which is defined as line segment AC = line segment AB = 1, as shown in equation (2). Therefore, as shown in Figure 10, the smaller the included angle θ, the more convex portions per unit length there are, and the total number of line segments onto which light can enter increases in accordance with the number of convex portions per unit length. As shown in Figure 11, when θ = π, the number of convex portions per unit length takes on the minimum value of 1. Because the unit length is 2, when θ = π is used as the base, the number of convex portions per unit length can be expressed as 2 sin(θ / 2) / 2 = sin(θ / 2).

[0125] When 0<θ<π / 2, by correcting equation (10) by dividing it by π and sin(θ / 2) in equation (16), the probability function f(θ) of the first reflected light shining outside the appearance unevenness suppression member in a triangular wave structure having an included angle θ is expressed as in equation (17).

[0126]

number

[0127] When π / 2≦θ≦π, by correcting equation (15) by dividing it by π and sin(θ / 2) in equation (16), the probability function f(θ) of the first reflected light shining outside the appearance unevenness suppression member in a triangular wave structure having an included angle θ is expressed as in equation (18).

[0128]

number

[0129] [4] Summary FIG. 12 shows a graph of Equation (17) and Equation (18). As shown in FIG. 12, the smaller the included angle θ, the smaller the value of the probability function f(θ). In particular, when the included angle θ is 90° or less, the reflected light can be reduced to less than 60% of that when θ = π. This result demonstrates that the triangular wave structure 10, in which the convex portions 20 and the concave portions 30 are alternately and continuously arranged, can reduce the reflected light. Furthermore, when the included angle θ is in the range of more than 60° and less than 90°, the probability function f(θ) is linear. However, when the included angle θ is 60° or less, the probability function f(θ) becomes a downwardly convex curve, making it easier to reduce the reflected light. Furthermore, when the included angle θ is 50° or less, the reflected light can be reduced to less than 20% of that when θ = π. Furthermore, when the included angle θ is 20° or less, the change in the slope of the probability function f(θ) with changes in the included angle θ becomes small, and it can be seen that the intensity of the reflected light is less likely to change even if the included angle θ changes.

[0130] [5. Light reflection suppression mechanism using changes in refractive index] Next, the mechanism by which the appearance unevenness suppression member 1 having the anodic oxide coating 50 can further reduce reflected light by utilizing a change in refractive index will be described with reference to FIG.

[0131] The appearance unevenness suppressing member 1 having an anodized coating composite film formed thereon has an anodized film 50 formed on the surface of an aluminum base material 40. A light-absorbing colored layer 53 (electrolytic colored layer 53) is also formed on a porous layer 52 of the anodized film 50. The anodized film 50 is known to have a refractive index of 1.4 to 1.8.

[0132] When light is incident from atmospheric air, which has a refractive index of 1.0, onto anodized film 50, which has a refractive index of 1.4 to 1.8, the incident light is separated into a component that is reflected at the interface between the air and anodized film 50, and a component that is not reflected at the interface and enters anodized film 50 as refracted light. The component that enters anodized film 50 as refracted light is absorbed by electrolytic coloring layer 53. Therefore, when considering the reflectance of the surface of appearance unevenness suppression member 1, only the component that is reflected at the interface between air and anodized film 50 needs to be considered.

[0133] The same consideration applies not only to cases where the anodized coating film 50 is the outermost layer, but also to cases where the appearance unevenness suppressing member 1 has an electrodeposition coating film 60 on the anodized coating film 50. The refractive indexes of the electrodeposition coating film 60 and the anodized coating film 50 are approximately equal. Therefore, when light enters the electrodeposition coating film 60 from the air, the light is separated into a component that is reflected at the interface between the air and the electrodeposition coating film 60 and a component that is not reflected at the interface and enters the electrodeposition coating film 60 as refracted light. Because the refractive indexes of the electrodeposition coating film 60 and the anodized coating film 50 are approximately equal, the light is transmitted through the interface between the electrodeposition coating film 60 and the anodized coating film 50 with almost no reflected component. The component that enters the electrodeposition coating film 60 and the anodized coating film 50 as refracted light is absorbed by the electrolytic coloring layer 53. Therefore, when considering the reflectance of the surface of the member for suppressing unevenness in appearance 1, only the component reflected at the interface between the air and the electrodeposition coating film 60 needs to be taken into consideration.

[0134] According to Fresnel's law, the reflectance at the interface between air and the anodized coating film 50 or the electrodeposition coating film 60 rises sharply when the angle of incidence is approximately 45°. When the triangular wave structure 10 has an included angle θ, the maximum possible reflection angle of the first reflected light that leaves the appearance unevenness suppression member 1 is θ / 2. The angle of incidence that causes the first reflected light to leave the appearance unevenness suppression member 1 can be 45° or more when the included angle θ is greater than 90°. When the included angle θ is greater than 90°, the maximum possible reflection angle of the first reflected light that leaves the member is greater than 45°. Therefore, as described below, the reflectance at the interface between air and the anodized coating film 50 or the electrodeposition coating film 60 rises sharply, the reflected light is intensified, and appearance unevenness is noticeable.

[0135] In this embodiment, the appearance unevenness suppression member 1 includes an anodized coating 50, an electrolytic coloring layer 53 is provided on a porous layer 52 of the anodized coating 50, and the included angle θ of the triangular wave structure 10 is within the range of 0°<θ≦90°. Therefore, the maximum possible reflection angle of the first reflected light exiting the appearance unevenness suppression member 1 is 45° or less, and the reflectance of the interface between the air and the anodized coating film 50 or the electrodeposition coating film 60 is reduced. Therefore, the reflected light from the appearance unevenness suppression member 1 is weakened, and appearance unevenness is suppressed.

[0136] Next, we will explain the reflection characteristics at the interface between media with different refractive indices. The reflection characteristics at the interface between media with different refractive indices are defined by the Fresnel equations in the following formulas (19) and (20) (see FIG. 13).

[0137]

number

[0138]

number

[0139] In the above formulas (19) and (20), rp represents the amplitude reflection coefficient of p-polarized light, rs represents the amplitude reflection coefficient of s-polarized light, α represents the angle of incidence, β represents the angle of refraction, n1 represents the refractive index of the medium on the incident light side, and n2 represents the refractive index of the medium on the transmitted light side. P-polarized light is a component whose electric field oscillates parallel to the plane of incidence, and s-polarized light is a component whose electric field oscillates perpendicular to the plane of incidence.

[0140] If the refractive index of air is 1, then the refraction angle β can be calculated from equation (21) according to Snell's law.

[0141]

number

[0142] The reflectance R can be calculated by the following formula (22).

[0143]

number

[0144] Fig. 14 shows a graph of formula (22) based on the value of β calculated from formula (21). As shown in Fig. 14, the reflectance R of the appearance unevenness suppression member 1 rises sharply at an incident angle of approximately 45°. Therefore, by setting θ≦90°, the reflectance of reflected light can be reduced.

[0145] [6. Action and Effects] The appearance unevenness suppressing member 1 according to this embodiment has a triangular wave structure 10 in which the protrusions 20 and the recesses 30 are alternately arranged in succession, each having a plurality of protrusions 20 each having a peak 21 and a plurality of recesses 30 each having a bottom 31 and sandwiched between adjacent protrusions 20. Each of the recesses 30 is formed by a first wall 22a and a second wall 22b in a cross-sectional view, and is recessed so that its width narrows toward the bottom 31. Each of the protrusions 20 is formed by a first wall 22a of one recess 30 adjacent to the protrusion 20 and a second wall 22b of the other recess 30 adjacent to the protrusion 20 in a cross-sectional view, and protrudes so that its width narrows toward the peak 21. The average depth of the recesses 30 is 1 mm or more and 30 mm or less. In a cross-sectional view, the average value of the included angle θ, which is the inner angle of the recess 30 formed by the first wall portion 22a and the second wall portion 22b, is greater than 0° and less than or equal to 90°. The depth D of each of the multiple recesses 30 is substantially the same. In the first direction in which the protrusions 20 and recesses 30 of the triangular wave structure 10 are alternately and continuously arranged, the bottom 31 of the recess 30 is located between the tops 21, 21 of the protrusions 20, 20 on both sides that are continuous with the recess 30. Therefore, it is possible to suppress unevenness in appearance and to provide a member 1 for suppressing unevenness in appearance that can be mass-produced in large quantities.

[0146] The member for suppressing unevenness in appearance 1 includes an aluminum base 40 containing pure aluminum or an aluminum alloy, and an anodized coating 50 provided on the surface of the aluminum base 40. The anodized coating 50 includes a barrier layer 51 provided on the surface of the aluminum base 40, and a porous layer 52 provided on the surface of the barrier layer 51 and having a plurality of pores. The porous layer 52 is provided with a colored layer 53 containing at least one of a metal, a metal salt, a dye, a pigment, and an organic acid. With this configuration, the colored layer 53 can absorb light, making it possible to provide a member for suppressing unevenness in appearance 1 that can further suppress unevenness in appearance. [Example]

[0147] Hereinafter, the present embodiment will be described in more detail with reference to examples and comparative examples, but the present embodiment is not limited to these.

[0148] [Experimental Example 1] Reflected light from sunlight was reproduced using physically based rendering that applied BRDF. Physically based rendering is a simulation approach based on the physical laws of light, such as reflection. BRDF is a function that indicates the spread of reflected light from a surface, and applying BRDF to physically based rendering makes it possible to predict the appearance of a product. Specifically, as shown in Figure 15, we used a simulation to evaluate the reflected light from sunlight irradiated onto a building on which two appearance unevenness suppression materials with triangular wave structures were installed, one above the other. Bronze or black materials were used for the appearance unevenness suppression materials.

[0149] The simulation was carried out using Lumicept, an optical simulation software manufactured by Integra Co., Ltd. The simulation conditions were: solar direction 180° (due south), solar altitude 40°, flat illuminance on the surface of the exterior unevenness suppression material 100,000 lux, and the position of the exterior unevenness suppression material on the south side of the building.

[0150] For the bronze and black materials, different L values ​​were used for the upper and lower parts as shown in Table 1 below. * value, a * value and b * These color tones were calculated by setting L values ​​under the geometric condition c (di: 8°) specified in JIS Z8722:2009 for two pieces (lower / upper) of bronze and black material from the same lot, which were manufactured as follows: * a * b * was measured using a Konica Minolta CR-400. * a * b * The graph shows the measurement of the color tone of the bronze material and black material in a flat shape without introducing a triangular wave shape.

[0151] <Bronze material> The bronze material was produced by anodizing an aluminum plate, electrolytically coloring it in bronze, and then electrodeposition coating it with an anionic electrodeposition paint made of melamine resin / acrylic resin.

[0152] <Black material> The black material was produced in the same manner as the bronze material, except that it was electrolytically colored black.

[0153] [Table 1]

[0154] In the simulation, the height of the convex parts of the triangular wave structure was set to 2 mm, and the depth of the concave parts was set to 2 mm. For observation angles of -60°, -45°, and 0°, the BRDF was evaluated when the included angle θ of the triangular wave structure was set to 20°, 30°, 50°, 60°, 70°, 80°, 90°, 100°, and 180°. The observation angle γ was set to 0°, with the perpendicular line drawn from the front of the building directly south defined as +, and the direction moving east defined as -.

[0155] Next, for each component, the luminance difference (absolute value) between the luminance of the upper component and the luminance of the lower component was evaluated. The luminance of the upper component was defined as the luminance within a 30 × 30 pixel square frame centered at X = 400 pixels and Y = 190 pixels, as shown in Figure 16. The luminance of the lower component was defined as the luminance within a 30 × 30 pixel square frame centered at X = 400 pixels and Y = 250 pixels, as shown in Figure 16. The resolution of all images obtained in the simulation was 800 × 600 pixels, with the coordinates (0,0) at the top left and (800,600) at the bottom right. The relationship between the luminance difference obtained as described above and the included angle was then evaluated. Figures 17 to 28 show images of the bronze and black components obtained by simulation when the observation angles were 0°, -45°, and -60°, and the included angles were 20°, 50°, 60°, 80°, 90°, and 100°. Figures 29 to 31 are graphs showing the relationship between the included angle and luminance difference for bronze materials when the observation angle is 0°, -45°, and -60°, respectively. Figures 32 to 34 are graphs showing the relationship between the included angle and luminance difference for black materials when the observation angle is 0°, -45°, and -60°, respectively.

[0156] 17 to 28 and 29 to 34, it can be seen that for the bronze and black materials, the luminance difference decreases sharply at an included angle of 90°. Furthermore, as the observation angle increases to 0°, -45°, and -60°, the change in luminance difference at included angles of 90° to 100° becomes greater than the change in luminance difference at included angles of 80° to 90°. These results show that when observing from a specific observation angle (especially -60°), setting the included angle θ to 90° or less reduces the luminance of reflected light and reduces color unevenness.

[0157] [Experimental Example 2] Next, two aluminum plates with a triangular wave structure having recesses and protrusions as shown in Figure 35 were produced as appearance unevenness suppression members by wire-cutting a 100 mm x 500 mm aluminum plate. The triangular wave structure of the aluminum plate of Experimental Example 2 had an included angle of 30°, an average depth of the multiple recesses of 2.4 mm, an average width of the multiple protrusions of 1.89 mm, and the tops of the protrusions were arc-shaped with a radius of 0.2 mm. The protrusions and recesses were arranged on the front side of the aluminum plate, and the back side of the aluminum plate was flat. The two aluminum plates with triangular wave structures were anodized and electrolytically colored black to produce an anodized coating composite film.

[0158] The color tone of the front and back surfaces of the two anodized coating composite films was measured using a Konica Minolta CR-400 color difference meter under the diffused illumination and perpendicular reception method with a D65 light source, in accordance with geometric condition c of JIS Z8722:2009 (the irradiated light includes a component that is specularly reflected from the sample). The specular gloss of the front and back surfaces of the two anodized coating composite films was also measured using a Suga Test Instruments Co., Ltd. GM-1 gloss meter at angles of 20°, 60°, and 85° in accordance with JIS Z8741-1997. The gloss was measured in the first direction (L), in which the triangular wave structure of convex and concave portions alternates continuously, and in the second direction (Lt), which is perpendicular to the first direction. The results are shown in Table 2.

[0159] [Table 2]

[0160] Next, as shown in FIG. 36, a test member 200 was prepared by arranging two anodized coating composite films 100 with triangular wave structures in the vertical direction, with the front and back surfaces facing each other, so that the observation surfaces were facing each other. Then, as shown in FIG. 37, the test member 200 was measured at observation positions 1 to 7 using a Konica Minolta LS100 luminance meter to measure the luminance of the central portion of the anodized coating composite film 100, as circled in FIG. 36. The luminance measurements were alternately conducted twice for both the example and the comparative example. The solar altitude was 27° to 29°, and the solar azimuth was 121° to 124° (southeast). The luminance was measured so that the height of the bottom of the test member 200 was 1.2 m from the observation position, and observation position 4 was 180° (due south). The average luminance difference between the luminance of the upper anodized coating composite film 100 and the luminance of the lower anodized coating composite film 100 was calculated. Table 3 shows the luminance and luminance difference of the example (front surface) at each observation position. Table 4 shows the luminance and luminance difference of the comparative example (rear surface) at each observation position. Figure 38 is a graph showing the relationship between observation position and luminance difference.

[0161] [Table 3]

[0162] [Table 4]

[0163] 38, in the example in which the observation area has a triangular wave structure, the luminance is lower than in the comparative example in which the observation area is flat, and the luminance difference is also lower. These results support the idea that appearance unevenness can be suppressed by providing the appearance unevenness suppression member with a triangular wave structure.

[0164] Although the present embodiment has been described above using examples and comparative examples, the present embodiment is not limited to these examples and comparative examples, and various modifications are possible within the scope of the gist of the present embodiment. [Explanation of symbols]

[0165] 1. Appearance unevenness suppression material 10 Triangular wave structure 20 Convex part 21 Top 22 Wall 22a 1st wall 22b 2nd wall part 30 recess 31 Bottom 40 Aluminum substrate 50 Anodized film 51 Barrier Layer 52 Porous layer 53 Electrolytically colored layer 60 Electrodeposition coating film H Height D Depth θ Included angle W1 Width of the convex part W2 Recess width

Claims

1. An appearance unevenness suppressing member comprising an aluminum base material containing pure aluminum or an aluminum alloy, and an anodized coating film provided on a surface of the aluminum base material, the anodized coating has a barrier layer provided on the surface of the aluminum base material, and a porous layer provided on the surface of the barrier layer and having a plurality of holes; the porous layer is provided with a colored layer containing at least one of a metal, a metal salt, a dye, a pigment, and an organic acid; The appearance unevenness suppression member has a triangular wave structure, the triangular wave structure has a plurality of convex portions each having a top portion, and a plurality of concave portions each having a bottom portion and sandwiched between adjacent convex portions among the plurality of convex portions, the convex portions and the concave portions being alternately and continuously arranged, Each of the plurality of recesses is formed by a first wall portion and a second wall portion in a cross-sectional view, and is recessed so that its width narrows toward the bottom portion, each of the plurality of protrusions is formed, in the cross-sectional view, by the first wall portion of one recess adjacent to the protrusion and the second wall portion of the other recess adjacent to the protrusion, and protrudes so as to narrow in width toward the apex; an average depth of the plurality of recesses is 1 mm or more and 30 mm or less; In the cross-sectional view, an average value of an included angle, which is an angle on the inside of the recess formed by the first wall portion and the second wall portion, is greater than 0° and less than or equal to 90°, the depth of each of the plurality of recesses is substantially the same; An appearance unevenness suppression member in which, in a first direction in which the convex portions and concave portions of the triangular wave structure are arranged alternately and continuously, the bottom of the concave portion is located between the tops of the convex portions on both sides that are continuous with the concave portion.

2. 2. The member for suppressing unevenness in appearance according to claim 1, wherein the refractive index of the anodized film is 1.4 or more and 1.8 or less.

3. 2. The member for suppressing uneven appearance according to claim 1, wherein the metal and the metal salt include at least one selected from the group consisting of Ni, Co, Cu, Sn, Mn, Fe, Pb, Ca, Zn, and Mg.

4. The member for suppressing unevenness in appearance according to claim 1 , further comprising an electrodeposition coating film on the anodized film.

5. The member for suppressing unevenness in appearance according to claim 4, wherein the refractive index of the electrodeposition coating film is 1.4 or more and 1.8 or less.

6. The member for suppressing unevenness in appearance according to claim 4 , wherein the electrodeposition coating film contains at least one resin selected from the group consisting of acrylic resin, melamine resin, epoxy resin, and fluororesin.

7. The member for suppressing unevenness in appearance according to claim 1 , wherein an average width of the plurality of recesses is greater than 0 mm and not greater than 60 mm.

8. 2. The member for suppressing unevenness in appearance according to claim 1, wherein the depth of each of the plurality of recesses is not less than −20% and not more than +20% of the average depth of the plurality of recesses.

9. 2. The appearance unevenness suppression member of claim 1, wherein, in a plan view, the plurality of convex portions and the plurality of concave portions extend linearly in a second direction perpendicular to the first direction in which the convex portions and the concave portions are alternately and continuously arranged, and are formed parallel to each other.

10. The member for suppressing unevenness in appearance according to claim 1 , wherein the total length of the triangular wave structure in a second direction perpendicular to the first direction is 1 m or more.

11. The member for suppressing unevenness in appearance according to claim 1 , which is an extruded material.

12. The member for suppressing unevenness in appearance according to any one of claims 1 to 11, which is a building material, an optical member, a vehicle member, or a civil engineering member.

Images