Metal member, MEMS device, container, and straw

Abstract

To provide a metal member which develops a color tone with different hues depending on the angle of the observer's line of sight relative to the surface of the metal member, a MEMS device including the metal member, a container, and a straw.SOLUTION: A metal member 1 has a substrate 2 composed of a metal, a transparent layer 3 composed of a substance that transmits visible light and provided on the substrate 2, and a reflective layer 4 provided on the transparent layer 3. The reflective layer 4 is configured to reflect a portion of light incident on the reflective layer 4. The developed area ratio Sdr of the interface 21 between the substrate 2 and the transparent layer 3 is 0.7% or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a metal member, a MEMS device including the metal member, a container, and a straw.

Background Art

[0002] Metal members may be used in applications that require high design quality, such as building materials and the casings of electronic devices. The surface of this type of metal member may be colored for the purpose of enhancing its design quality. When imparting a colored tone to the surface of a metal member, paint is often used. However, paint contains organic substances that are easily deteriorated by various causes such as ultraviolet irradiation. Therefore, a colored member having a colored tone imparted by paint has a problem that peeling, fading, and deterioration of the coating film are likely to occur during use.

[0003] On the other hand, a technique has been proposed in which a colored tone is imparted to the surface of a member without using paint by utilizing the interference of light. For example, Patent Document 1 describes an interference color-developing metal body including a metal substrate capable of forming a transparent anodic oxide film, a barrier layer formed on the surface thereof, and a light-reflective layer having a film thickness of 0.5 to 100 nm formed on the barrier layer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, in order to further enhance the design quality of metal members, metal members whose hue changes according to the angle of the observer's line of sight with respect to the surface have been desired. However, the metal body of Patent Document 1 may have a small change in hue when the angle of the observer's line of sight with respect to its surface is changed.

[0006] The present invention has been made in view of such a background, and aims to provide a metal member that exhibits a color tone having different hues according to the angle of the observer's line of sight with respect to the surface of the metal member.

Means for Solving the Problems

[0007] One aspect of the present invention includes a base material made of metal, a transparent layer made of a substance that transmits visible light and provided on the base material, and a reflective layer provided on the transparent layer, wherein the reflective layer is configured to reflect a part of the visible light incident on the reflective layer, and the metal member has a developed area ratio Sdr of the interface between the base material and the transparent layer of 0.7% or less.

Effects of the Invention

[0008] In the metal member, the developed area ratio Sdr of the interface between the base material and the transparent layer is within the specific range. Thus, by adjusting the uneven shape of the interface between the base material and the transparent layer so that the developed area ratio Sdr is within the specific range, the metal member can be made to exhibit a color tone having different hues according to the angle of the observer's line of sight with respect to its surface.

[0009] Therefore, according to the above aspect, a metal member that exhibits a color tone having different hues according to the angle of the observer's line of sight with respect to the surface of the metal member can be provided.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0011] (Metal Member) The base material of the metal member is composed of metal. As the metal constituting the base material, for example, metals showing achromatic colors such as white, gray, off-white, and silver-white can be preferably used. Examples of metals presenting such color tones include iron, iron alloys, aluminum, aluminum alloys, titanium, and titanium alloys. By using an achromatic metal as the base material of the metal member, the influence of the color tone of the base material on the color tone of the metal member can be reduced, and a metal member having a desired color tone can be obtained more easily.

[0012] As the metal constituting the base material, it is preferable to use aluminum, an aluminum alloy, titanium, or a titanium alloy. Since these metals have low chroma, the influence of the color tone of the base material on the color tone of the metal member can be further reduced. Furthermore, by performing anodic oxidation treatment on the base material made of these metals, a transparent layer made of an oxide can be easily formed on the surface of the base material. Among these metals, from the viewpoint of reducing material costs, the metal constituting the base material is more preferably aluminum or an aluminum alloy.

[0013] The materials of the aluminum and aluminum alloys constituting the base material are not particularly limited and can be appropriately selected according to the use of the metal member and the required mechanical properties, etc. For example, when high strength is required for the metal member, it is preferable to use a base material made of a 5000 series alloy or a 6000 series alloy. Also, when excellent design properties are required for the metal member, it is preferable to use a base material made of 1000 series aluminum or a 6000 series alloy in which coloring due to anodic oxidation treatment hardly occurs.

[0014] A transparent layer made of a substance that transmits visible light is provided on the base material. The developed area ratio Sdr of the interface between the base material and the transparent layer is 0.7% or less. By setting the developed area ratio Sdr of the interface between the base material and the transparent layer within the specific range, the surface of the metal member can be made to exhibit a color tone having different hues according to the angle of the observer's line of sight with respect to the surface. For example, the following reasons can be considered for this.

[0015] Since the interface with the spreading area ratio Sdr within the specific range is relatively smooth, it is considered that the incident light from the light source incident on the metal member is reflected at the interface between the base material and the transparent layer generally in the direction corresponding to the incident angle. At this time, since the optical path length of the light reflected from the interface in the direction of the observer's line of sight is generally uniform, it is considered that the phase of the light reflected from the interface in the direction of the observer's line of sight is also generally uniform. Further, since the length of the optical path length of the reflected light reflected at the interface changes according to the reflection angle, when the direction of the observer's line of sight with respect to the surface of the metal member changes, it is considered that the phase of the light reflected in the direction of the line of sight also changes. And it is considered that the reflected light having different phases according to the reflection angle in this way interferes with the reflected light reflected on the surface of the reflection layer and the like, so that the metal member can be made to exhibit colors having different hues according to the angle of the observer's line of sight with respect to its surface.

[0016] The spreading area ratio Sdr of the interface between the base material and the transparent layer is preferably 0.5% or less, more preferably 0.3% or less, still more preferably 0.2% or less, particularly preferably 0.1% or less, and most preferably 0.05% or less. In this case, the change in the hue of the metal member when the angle of the line of sight is changed can be made larger.

[0017] The spreading area ratio Sdr of the interface between the base material and the transparent layer described above is measured by a method conforming to ISO 25178:2021. For measuring the spreading area ratio Sdr, for example, a non-contact surface roughness measuring device such as a laser microscope or a white interference microscope can be used.

[0018] Also, as a method for controlling the developed area ratio Sdr at the interface between the base material and the transparent layer within the specific range, for example, in the manufacturing process of the metal member, a method of forming a transparent layer on the base material after adjusting the surface properties of the base material can be adopted. As a method for adjusting the surface properties of the base material, for example, a method of rolling the base material using a rolling roll having an appropriate surface roughness or a method of polishing the surface of the base material can be adopted. The method of polishing the base material is not particularly limited, and known polishing methods such as mechanical polishing for polishing the surface of the base material using an abrasive, electrolytic polishing for electrochemically dissolving the surface of the base material, and chemical polishing for chemically dissolving the surface of the base material can be adopted. When adjusting the surface properties of the base material, the above-described methods may be performed alone, or a plurality of methods may be appropriately combined.

[0019] The substance constituting the transparent layer may be an organic substance or an inorganic substance. The transparent layer is preferably composed of an inorganic substance. A transparent layer made of an inorganic substance is less likely to deteriorate against temperature changes, humidity changes, sunlight irradiation, etc. during the use of the metal member, and can maintain optical properties for a longer period. Therefore, by providing a transparent layer made of an inorganic substance on the base material, the color tone of the metal member can be maintained for a longer period.

[0020] Also, the transparent layer is preferably composed of an oxide of the metal constituting the base material. Since the metal oxide is less likely to deteriorate against temperature changes, humidity changes, sunlight exposure, etc., by providing a transparent layer made of an oxide on the base material, the color tone of the metal member can be maintained for a longer period. Furthermore, in this case, by performing anodic oxidation treatment on the base material, a transparent layer can be grown from the surface of the base material, so that the formation of gaps and the intrusion of foreign substances at the interface between the base material and the transparent layer can be prevented. As a result, the occurrence of unevenness and defects in the color tone of the metal member can be more effectively suppressed.

[0021] The thickness of the transparent layer is preferably 15 nm or more and 600 nm or less. In this case, due to the interference between the light reflected by the reflective layer and the light reflected by the base material, light waves having wavelengths in the visible light region can be enhanced. As a result, the metal member can be colored in various color tones. Note that, as a method for controlling the thickness of the transparent layer, for example, a method of adjusting the applied voltage in an anodizing process can be adopted. For example, when performing anodizing by direct current electrolysis, the thickness of the transparent layer can be increased by increasing the applied voltage.

[0022] On the transparent layer, a reflective layer configured to be able to reflect a part of the visible light incident on the metal member is provided. By providing such a reflective layer on the transparent layer, the light reflected by the reflective layer and the light reflected at the interface between the base material and the transparent layer can be made to interfere, and the metal member can be colored in various color tones. From the viewpoint of further enhancing the chroma of the metal member and developing a more vivid color tone, it is preferable that the average value of the spectral transmittance of the reflective layer in the range of 400 nm or more and 700 nm or less is 2% or more and 80% or less, more preferably 20% or more and 70% or less, and even more preferably 30% or more and 60% or less.

[0023] The average value of the spectral transmittance of the reflective layer described above can be calculated by the following method. First, the spectral transmittance of the reflective layer is measured at a plurality of wavelengths within the range of 400 nm or more and 700 nm or less. At this time, from the viewpoint of calculating the average value of the spectral transmittance of the reflective layer more accurately, it is preferable to measure the spectral transmittance of the reflective layer at a plurality of wavelengths determined so that the wavelength intervals are constant. Also, the wavelength interval for measuring the spectral transmittance is preferably 20 nm or less, for example. The value obtained by arithmetically averaging the spectral transmittances at the plurality of wavelengths obtained as described above is taken as the average value of the spectral transmittance of the reflective layer.

[0024] The reflective layer may be composed of, for example, a metal or a metal compound. Further, the reflective layer may contain both a metal and a metal compound. When the reflective layer is composed of a metal and / or a metal compound, the thickness of the reflective layer is preferably 2 nm or more and 30 nm or less. In this case, the average value of the spectral transmittance of the reflective layer can be more easily adjusted within the specific range.

[0025] As the metal constituting the reflective layer, for example, aluminum, copper, silver, platinum, etc. can be used. Further, as the metal compound constituting the reflective layer, for example, copper oxide, silver sulfide, etc. can be used. Among these, from the viewpoint of more surely obtaining the above-described effects, it is preferable that the reflective layer contains copper atoms or silver atoms.

[0026] Further, it is more preferable that the reflective layer contains a metal compound. Since the metal compound is less likely to deteriorate in the atmosphere, the optical properties of the reflective layer can be maintained for a longer period. Therefore, by providing a reflective layer made of a metal containing a metal compound on the transparent layer, the vivid color tone of the metal member can be maintained for a longer period. From the viewpoint of more surely obtaining such an effect, it is preferable that the reflective layer contains copper oxide or silver sulfide, and more preferably contains copper oxide.

[0027] Further, from the viewpoint of more surely imparting the above-described optical properties to the reflective layer, it is preferable that the reflective layer contains a plurality of crystal grains. From the same viewpoint, it is more preferable that the average grain size of the crystal grains contained in the reflective layer is 3 nm or more and 15 nm or less.

[0028] Note that the average grain size of the above-described crystal grains is a value calculated as follows. First, the cross-section of the reflective layer is observed using a high-resolution transmission electron microscope to obtain an electron microscope image of the reflective layer. Next, the equivalent circle diameter of the crystal grains present in the electron microscope image, that is, the diameter of a circle equal to the cross-sectional area of the crystal grains, is calculated. The arithmetic average value of the equivalent circle diameters of the crystal grains thus obtained is taken as the average grain size of the crystal grains.

[0029] On the reflective layer of the metal member, a protective layer made of a substance that transmits visible light and provided on the reflective layer may be further provided. In this case, deterioration of the reflective layer due to reaction with oxygen, moisture, sulfur content, etc. in the atmosphere can be suppressed over a longer period, and the vivid colored appearance of the metal member can be maintained over a longer period.

[0030] The substance constituting the protective layer may be an organic substance or an inorganic substance. As the protective layer, for example, transparent resins such as acrylic resin, methacrylic resin, polycarbonate resin, nitrocellulose resin, and organic glass can be preferably used.

[0031] As described above, since the metal member exhibits a color tone having different hues according to the angle of the observer's line of sight with respect to the surface of the metal member, it can be preferably used for applications that require designability. For example, the metal member is suitable for building materials, housings of electronic devices, etc.

[0032] Also, for example, since the container provided with the metal member has high designability, it is suitable for applications that require particularly excellent appearance characteristics such as cosmetic containers and straws.

[0033] Also, the metal member can be preferably used for MEMS devices such as micromirrors by taking advantage of the characteristic of developing a color tone having different hues according to the angle of the observer's line of sight with respect to its surface.

[0034] (Manufacturing method of metal member) For example, the metal member is prepared by preparing a base material having a surface development area ratio Sdr of 0.7% or less, forming a transparent layer by subjecting the base material to anodic oxidation treatment in a weakly acidic or weakly basic electrolytic solution, and then forming a reflective layer on the transparent layer by a sputtering method.

[0035] The method for preparing the base material used in the manufacture of the metal member can take various forms. For example, the base material may be an extended material subjected to an extension process such as rolling or extrusion. Further, the base material may be formed into a desired shape by machining or plastic working. Additionally, in order to adjust the developed area ratio Sdr of the surface of the base material within the specific range, the surface of the base material may be polished as necessary.

[0036] Next, an anodizing treatment is performed on the base material to form a transparent layer on the surface of the base material. When the anodizing treatment is performed on the base material, the dissolution of the surface of the base material and the formation of the transparent layer proceed simultaneously. Further, the dissolution of the surface of the base material and the formation of the transparent layer proceed uniformly on the surface of the base material. Therefore, the developed area ratio Sdr of the interface between the surface of the base material and the transparent layer after the anodizing treatment is generally equal to the developed area ratio Sdr of the surface of the base material before the anodizing treatment.

[0037] The electrolytic solution used for the anodizing treatment may be a weakly acidic electrolytic solution or a weakly basic electrolytic solution. More specifically, as the weakly acidic electrolytic solution, for example, phosphates, borates, and adipic acid are used as electrolytes, and an electrolytic solution having a pH of 3.5 or more and 7 or less can be used. Further, as the weakly basic electrolytic solution, for example, borates and phosphates are used as electrolytes, and an electrolytic solution having a pH of 7 or more and 8 or less can be used.

[0038] Further, the treatment method in the anodizing treatment is preferably any one of direct current electrolysis performed by applying a voltage of 10 V or more and 400 V or less, alternating current electrolysis performed by applying a voltage such that the peak voltage is 10 V or more and 400 V or less, or pulse electrolysis. The transparent layer formed in this way is composed of an oxide of the metal constituting the base material and has no pores, so that light scattering in the transparent layer can be further reduced. Therefore, by performing the anodizing treatment by the treatment method described above, a metal member having a vivid colored appearance can be obtained more easily.

[0039] Also, the processing method in the sputtering method is preferably DC magnetron sputtering. In this case, the variation in the thickness of the reflective layer formed on the transparent layer can be further reduced, and crystal grains can be more easily formed in the reflective layer. Furthermore, according to DC magnetron sputtering, the grain size of the crystal grains in the reflective layer can be more easily controlled. Therefore, by performing sputtering treatment with the above-described processing method, a reflective layer having desired optical properties can be more easily formed on the transparent layer, and a metallic member having vivid colored appearance can be more easily obtained.

[0040] As the atmospheric gas in the chamber in DC magnetron sputtering, for example, argon can be used. In this case, the degree of vacuum in the chamber is set to 0.05 Pa or more and 5 Pa or less, and the current density applied to the sputtering target is 0.1 mA / cm 2 or more and 7 mA / cm 2 or less. By performing DC magnetron sputtering under such conditions, a reflective layer having desired optical properties can be more easily formed on the transparent layer.

Example

[0041] (Example 1) An example of the metallic member will be described with reference to FIG. 1. As shown in FIG. 1, the metallic member 1 of this example has a base material 2 made of metal, a transparent layer 3 made of a substance that transmits visible light and provided on the base material 2, and a reflective layer 4 provided on the transparent layer 3. The developed area ratio Sdr of the interface 21 between the base material 2 and the transparent layer 3 is 0.7% or less. Also, the reflective layer 4 is configured to reflect a part of the visible light incident on the reflective layer 4. The metallic member 1 of this example can be obtained by forming the transparent layer 3 by subjecting the base material 2 having a developed area ratio Sdr of the surface of 0.7% or less to anodic oxidation treatment, and then forming the reflective layer 4 on the transparent layer 3.

[0042] Next, a specific configuration of the metal member 1 in this example and an example of its manufacturing method will be described. When manufacturing the metal member 1 in this example, first, base materials A to D shown in Table 1 are prepared. The base materials A to D are all aluminum plates having a chemical composition represented by alloy number A1050 and have the developed area ratio Sdr shown in Table 1.

[0043] The base material A is obtained, for example, by polishing the surface of an aluminum plate in multiple stages while changing the type of abrasive, and performing polishing using a finishing abrasive ("SUPERFINISH FINAL LIQUID" manufactured by KULZER) in the final stage. The base material B is obtained, for example, by polishing the surface of an aluminum plate in multiple stages while changing the type of abrasive, performing polishing using an abrasive containing diamond abrasive grains with a particle size of 3 μm ("MetaDi (registered trademark) Supreme 3μm" manufactured by BUEHLER) and a lubricant ("DP-Lubricant Red" manufactured by Strothaus) in the final stage, and then performing electrolytic polishing for 2 minutes.

[0044] The base material C is obtained, for example, by polishing the surface of an aluminum plate in multiple stages while changing the type of abrasive, and performing polishing using an abrasive containing diamond abrasive grains with a particle size of 3 μm in the final stage. The base material D is obtained, for example, by rolling an aluminum plate using a roll with a small surface roughness. Note that the base material E shown in Table 1 is a base material for comparison with the base materials A to D. Specifically, the base material E is an aluminum rolled plate having a chemical composition represented by alloy number A1050.

[0045] Next, after subjecting substrates A to D to pretreatment such as cleaning, an anodizing treatment is performed on the substrates to form a barrier-type anodic oxide film as a transparent layer on the surface of the substrates. As the treatment method in the anodizing treatment, direct current electrolysis is employed, and the applied voltage is increased to 50 V over 2.5 minutes from the start of the treatment. Further, in the anodizing treatment, a weakly basic electrolytic solution containing 0.5 mol / L of boric acid and 0.05 mol / L of sodium tetraborate is used as the electrolyte. The temperature of the electrolytic solution in the anodizing treatment is set to 20°C. The thickness of the transparent layer formed under such conditions is 65 nm.

[0046] Thereafter, a reflective layer made of copper is formed on the transparent layer by DC magnetron sputtering. The thickness of the reflective layer in this example is 5 nm, and the average value of the spectral transmittance is 56.6%. Argon is used as the atmospheric gas in the chamber in DC magnetron sputtering, the degree of vacuum in the chamber is set to 0.05 Pa or more and 5 Pa or less, and the current density applied to the sputtering target is 2 7 mA / cm 2 or less. The method for measuring the spectral transmittance of the reflective layer will be described later.

[0047] Thus, test materials A1, B1, C1, and D1 shown in Table 2 can be obtained.

[0048] Note that test material E1 shown in Table 2 is a test material for comparison with test materials A1 to D1. Test material E1 has the same configuration as test materials A1 to D1 except that the spreading area ratio Sdr at the interface between the substrate and the transparent layer is outside the specific range. The manufacturing method of test material E1 is the same as that of test materials A1 to D1 except that substrate E is used.

[0049] Next, the method for evaluating the average value of the spectral transmittance of the reflective layer and the color tone of the metal members shown in Table 2 will be described.

[0050] 〔Average value of the spectral transmittance of the reflective layer〕 A reflective layer is formed on a glass substrate by a treatment method similar to the sputtering treatment for each test material, and the spectral transmittance of this reflective layer at various wavelengths is measured at 10-nm intervals within the range from a wavelength of 400 nm to 700 nm. Note that the light source used for the measurement of the spectral transmittance shall be Supplementary Illuminant C specified in JIS Z8720:2012. Also, the geometric conditions during the measurement shall be the geometric condition f represented by the symbol 0°:di in JIS Z8722:2009 (that is, the condition where light is irradiated from a direction in which the angle with respect to the normal of the surface of the transmission layer is 0°, and all transmitted light including the directly transmitted light is condensed), and the measurement area with a diameter of 30 mm is irradiated with light.

[0051] In the spectral transmittance at each wavelength obtained by the above method, in addition to the contributions such as light absorption in the reflective layer, the contributions such as light absorption in the glass substrate are included. The spectral transmittance T r of only the reflective layer is calculated based on the following formula (1) using the spectral transmittance T m obtained by measuring the reflective layer on the glass substrate at each wavelength and the spectral transmittance T glass of the glass substrate at each wavelength. T r = T m × (100 / T glass ) ···(1)

[0052] As described above, after correcting the measured spectral transmittance T m at each wavelength to exclude the influence of the glass substrate, the average value of the spectral transmittance of the reflective layer can be obtained by arithmetically averaging the corrected spectral transmittance T r .

[0053] 〔Change in color tone of metal member〕 Based on the gradation of the digital photograph and the result of visual observation when observing the surface of the metal member from various directions, the change in the color tone of the metal member is evaluated. As shown in FIG. 2, the evaluation apparatus 5 used for evaluating the change in color tone includes a photographing table 51 configured to be able to change the inclination angle with respect to the horizontal plane, and a camera 52 disposed vertically above the photographing table 51. As the camera 52, a single-lens reflex camera "EOS (registered trademark) 8000D" manufactured by Canon Inc. is used, and photography is performed with the ISO sensitivity automatically set (AUTO), the F value set to 8, and the exposure time set to 0.5 seconds.

[0054] In conducting the evaluation, first, the test specimen T is placed on the photographing table 51 with the surface of the photographing table 51 horizontal. Then, white light is irradiated from above the test specimen T to make the illuminance on the surface of the test specimen T 900 lux or more. As the light source, an LED bar (Toshiba Lighting & Technology, LEEM-40523N-01) attached to an LED bar type fixture (Toshiba Lighting & Technology, LEET-41201-LS9) is used, and the distance from the light source to the test specimen is set to 2 m or more. Also, in order to irradiate the test specimen T with white light from a direction as close as possible to the vertical above while avoiding the white light being blocked by the camera 52, the light source is installed at a position where the straight line connecting the center of the light source and the center of the test specimen T is inclined by about 10° to 40° with respect to the vertical direction. In this state, the test specimen T is photographed by the camera 52 under the above-described photographing conditions, and a digital photograph of the test specimen T is obtained. The above operations are performed by inclining the photographing table 51 to change the angle of the surface of the test specimen T with respect to the horizontal plane to 15°, 30°, 45°, 60°, and 75°, and digital photographs are taken at each angle.

[0055] Table 2 shows the results representing the color tone at the center of the digital photograph obtained in this way as RGB values in the sRGB color space and the results judged visually. Also, in the "ΔRGB ave " column of Table 2, the average value of the change amount of the RGB values calculated by the following formula (2) is described using the above-described RGB values.

[0056]

Equation

[0057] In addition, R in the formula (2) k is the gradation of the R channel at the center of the digital photograph taken by setting the angle of the surface of the test material with respect to the horizontal plane to k°, and G k is the gradation of the G channel at the center of the digital photograph taken by setting the angle of the test material to k°, and B k is the gradation of the B channel at the center of the digital photograph taken by setting the angle of the test material to k°. R, G, and B are integers of 0 or more and 255 or less, respectively, and the higher the luminance of each channel, the larger the values of R, G, and B become.

[0058] As can be understood from the formula (2), ΔRGB ave is the value obtained by averaging the change amounts of the gradations of each channel when the angle of the surface of the test material changes by 15°. Therefore, the larger the value of ΔRGB ave is, the greater the change in color tone when the angle of the sample stage is changed.

[0059] [Table 1]

[0060] [Table 2]

[0061] As shown in Table 2, since the test materials A1 to D1 are produced using a base material in which the developed area ratio Sdr is within the specific range, the developed area ratio Sdr at the interface between the base material and the transparent layer in these test materials is within the specific range. Therefore, in these test materials, the change in the hue of the surface of the test material is likely to be large when the angle of the observer's line of sight with respect to the surface changes. Therefore, the surfaces of the test materials A1 to D1 exhibit color tones having different hues according to the angle of the observer's line of sight with respect to the surface.

[0062] On the other hand, since the test specimen E1 is produced using a base material whose development area ratio Sdr is outside the specific range, the development area ratio Sdr at the interface between the base material and the transparent layer in the test specimen E1 is outside the specific range. Therefore, when the angle of the observer's line of sight with respect to the surface of the test specimen E1 changes, the change in the color tone of the surface of the test specimen E1 tends to be small.

[0063] (Example 2) In this example, an example of a metal member in which the thickness of the transparent layer formed on the base material is changed is shown. The metal members in this example (Test specimens A2 - A3, Test specimens B2 - B3, and Test specimens D2 - D3 in Table 3) have the same configuration as the test specimens A1, B1, or D1 of Example 1, except that the thickness of the transparent layer is different as shown in Table 3. The manufacturing method of the metal members in this example is the same as the manufacturing method of the metal members in Example 1, except that the applied voltage in the anodic oxidation treatment is changed to the value shown in Table 3. Table 3 shows the evaluation results of the change in color tone of the metal members (Test specimens A2 - A3, Test specimens B2 - B3, and Test specimens D2 - D3) in this example, which were carried out by the same method as in Example 1.

[0064]

Table 3

[0065] As shown in Table 3, the development area ratio Sdr at the interface between the base material and the transparent layer in Test specimens A2 - A3, Test specimens B2 - B3, and Test specimens D2 - D3 is within the specific range. Therefore, like the test specimens A1 - D1 of Example 1, these test specimens exhibit color tones with different hues depending on the angle of the observer's line of sight with respect to the surface of the test specimen.

[0066] As described above, the specific embodiments of the metal member according to the present invention have been described based on Examples 1 - 2. However, the embodiments of the metal member, MEMS device, container, and straw according to the present invention are not limited to the embodiments of the examples, and the configuration can be appropriately changed without departing from the spirit of the present invention.

[0067] For example, the metal member can take the aspects according to the following [1] to [9].

[0068] [1] A base material made of metal, a transparent layer made of a substance that transmits visible light and provided on the base material, and a reflective layer provided on the transparent layer, and the reflective layer is configured to reflect a part of the light incident on the reflective layer, a metal member in which the developed area ratio Sdr of the interface between the base material and the transparent layer is 0.7% or less.

[0069] [2] The metal member according to [1], wherein the average value of the spectral transmittance of the reflective layer in the range of 400 nm or more and 700 nm or less in wavelength is 2% or more and 80% or less. [3] The metal member according to [1] or [2], wherein the transparent layer is made of an oxide of the metal constituting the base material. [4] The metal member according to any one of [1] to [3], wherein the transparent layer has a thickness of 15 nm or more and 600 nm or less.

[0070] [5] The metal member according to any one of [1] to [4], wherein the reflective layer is made of a metal and / or a metal compound and has a thickness of 2 nm or more and 30 nm or less. [6] The metal member according to any one of [1] to [4], wherein the reflective layer contains copper atoms or silver atoms. [7] The metal member according to any one of [1] to [6], wherein the reflective layer contains a plurality of crystal grains, and the average grain size of the crystal grains is 3 nm or more and 15 nm or less.

[0071] [8] The metal member according to any one of [1] to [7], wherein the base material is made of aluminum or an aluminum alloy. [9] The metal member according to any one of [1] to [8], further having a protective layer made of a substance that transmits visible light and provided on the reflective layer.

[0072] The MEMS device according to the present invention can take, for example, the aspect according to the following

[10] . The MEMS device having the metal member according to any one of [1] to [9] in

[10] .

[0073] The container according to the present invention can take, for example, the aspect according to the following

[11] . The container having the metal member according to any one of [1] to [9] in

[11] .

[0074] The straw according to the present invention can take, for example, the aspect according to the following

[12] . The straw having the metal member according to any one of [1] to [9] in

[12] .

Explanation of Reference Signs

[0075] 1 Metal member 2 Substrate 21 Interface 3 Transparent layer 4 Reflective layer

Claims

1. a base material made of metal, a transparent layer made of a substance that transmits visible light and provided on the base material, and a reflective layer provided on the transparent layer, wherein the reflective layer is configured to reflect a part of the light incident on the reflective layer, and the developed area ratio Sdr of the interface between the base material and the transparent layer is 0.7% or less. A metal member.

2. The metal member according to claim 1, wherein the average value of the spectral transmittance of the reflective layer in the range of a wavelength of 400 nm or more and 700 nm or less is 2% or more and 80% or less.

3. The metal member according to claim 1, wherein the transparent layer is made of an oxide of the metal constituting the base material.

4. The metal member according to claim 1, wherein the transparent layer has a thickness of 15 nm or more and 600 nm or less.

5. The metal member according to claim 1, wherein the reflective layer is made of a metal and / or a metal compound and has a thickness of 2 nm or more and 30 nm or less.

6. The metal member according to claim 4, wherein the reflective layer contains copper atoms or silver atoms.

7. The metal member according to claim 5, wherein the reflective layer contains a plurality of crystal grains, and the average particle size of the crystal grains is 3 nm or more and 15 nm or less.

8. The metal member according to claim 1, wherein the base material is made of aluminum or an aluminum alloy.

9. The metal member according to claim 1, further comprising a protective layer made of a substance that transmits visible light and provided on the reflective layer.

10. A MEMS device having the metal member according to any one of claims 1 to 9.

11. A container having the metal member according to any one of claims 1 to 9.

12. A straw having the metal member according to any one of claims 1 to 9.

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