Metal member, MEMS device, container, and straw

Abstract

This metal member (1) has a substrate (2) formed from metal, a transparent layer (3) which is formed from a substance that transmits visible light and which is 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 interface (21) between the substrate (2) and the transparent layer (3) has a developed area ratio Sdr of 1% or more.

Description

Metallic member, MEMS device, container and straw

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

[0002] Metallic components are often used in applications requiring high design quality, such as building materials and housings for electronic devices. The surfaces of these metallic components are often colored to enhance their design quality. Paints are often used to impart chromatic colors to the surfaces of metallic components. However, paints contain organic substances that are susceptible to deterioration due to various factors, such as exposure to ultraviolet light. Therefore, colored components imparted with chromatic colors by paints are prone to peeling, fading, and deterioration of the coating film during use.

[0003] In response to this, a technology has been proposed that uses light interference to impart chromatic color tones to the surface of a component without using paint. For example, Patent Document 1 describes an interference color-producing metal body that consists of a metal base on which a transparent anodic oxide film can be formed, a barrier layer formed on the surface of the metal base, and a light-reflecting layer with a thickness of 0.5 to 100 nm formed on the barrier layer.

[0004] Japanese Patent Application Laid-Open No. 2002-363772

[0005] However, the metal body of Patent Document 1 sometimes changes its hue when the angle of the viewer's line of sight relative to the surface is changed.

[0006] The present invention has been made in view of the above background, and aims to provide a metal member whose surface can be colored by the interference of light, and whose hue changes little even when the angle of the observer's line of sight changes.

[0007] One aspect of the present invention is a metal member having: a substrate made of metal; a transparent layer made of a substance that transmits visible light and provided on the substrate; and a reflective layer provided on the transparent layer, wherein the reflective layer is configured to reflect a portion of the visible light that is incident on the reflective layer; and a developed area ratio Sdr of the interface between the substrate and the transparent layer is 1% or more.

[0008] The metal member has a substrate, a transparent layer provided on the substrate, and a reflective layer provided on the transparent layer. The reflective layer is configured to reflect a portion of visible light incident on the reflective layer, thereby causing interference between light reflected at the interface between the substrate and the transparent layer and light reflected by the reflective layer.

[0009] Furthermore, the developed area ratio Sdr of the interface between the substrate and the transparent layer in the metal member is within the specific range. By adjusting the uneven shape of the interface between the substrate and the transparent layer so that the developed area ratio Sdr is within the specific range, it is possible to reduce changes in the hue of the surface of the metal member even when the angle of the viewer's line of sight with respect to the surface of the metal member changes.

[0010] Therefore, according to the above-described embodiment, the surface of a metal component can be colored by the interference of light, and a metal component can be provided in which the change in hue is small even when the angle of the observer's line of sight changes.

[0011] Fig. 1 is a cross-sectional view schematically showing a metal member in an example, and Fig. 2 is an explanatory diagram of an evaluation device for evaluating changes in color tone of the metal member in an example.

[0012] (Metallic Member) The substrate of the metallic member is made of a metal. As the metal constituting the substrate, for example, a metal exhibiting an achromatic color such as white, gray, grayish white, or silvery white can be preferably used. Examples of metals exhibiting such a color tone include iron, iron alloys, aluminum, aluminum alloys, titanium, and titanium alloys. By using an achromatic metal as the substrate of the metallic member, the influence of the color tone of the substrate on the color tone of the metallic member can be reduced, and a metallic member having a desired color tone can be more easily obtained.

[0013] The metal constituting the substrate is preferably aluminum, an aluminum alloy, titanium, or a titanium alloy. These metals have low chroma, so the influence of the color tone of the substrate on the color tone of the metal component can be further reduced. Furthermore, by subjecting a substrate made of these metals to anodizing treatment, a transparent layer made of an oxide can be easily formed on the surface of the substrate. Among these metals, the metal constituting the substrate is more preferably aluminum or an aluminum alloy from the viewpoint of reducing material costs.

[0014] The aluminum and aluminum alloy materials constituting the substrate are not particularly limited and can be appropriately selected depending on the application of the metal member, the required mechanical properties, etc. For example, when high strength is required for the metal member, it is preferable to use a substrate made of a 5000 series alloy or a 6000 series alloy. Furthermore, when excellent design properties are required for the metal member, it is preferable to use a substrate made of a 1000 series aluminum or a 6000 series alloy, which are less likely to be discolored by anodizing treatment.

[0015] A transparent layer made of a material that transmits visible light is provided on the substrate. The developed area ratio Sdr of the interface between the substrate and the transparent layer is 1% or more. By setting the developed area ratio Sdr of the interface between the substrate and the transparent layer within the above-mentioned specific range, it is possible to reduce changes in the hue of the surface of the metal component even when the angle of the viewer's line of sight relative to the surface of the metal component changes. The following reasons, for example, are thought to be the reasons for this.

[0016] Since the interface having the developed area ratio Sdr within the specific range is relatively rough, it is considered that the incident light from the light source incident on the metal member is reflected in various directions. Therefore, it is considered that the light reflected from the interface in the direction of the viewer's line of sight includes light reflected from different positions on the interface. Furthermore, if the reflection position of the light at the interface is different, the optical path length from the interface to the reflective layer will also be different, so it is considered that the light reflected from the interface in the direction of the viewer's line of sight includes light having various phases.

[0017] Furthermore, the reflected light reflected at the interface interferes with the reflected light reflected at the surface of the reflective layer, etc. At this time, the reflected light reflected at the interface contains light having various phases, and therefore it is thought that an interference color appears on the surface of the metal component, regardless of the direction of the observer's line of sight, due to interference between the light having an average phase among the reflected light reflected at the interface and the reflected light reflected at the surface of the reflective layer, etc. As a result of the above, it is thought that it is possible to reduce changes in the hue of the surface of the metal component even when the angle of the observer's line of sight with respect to the surface of the metal component changes.

[0018] The developed area ratio Sdr of the interface between the substrate and the transparent layer is preferably 3% or more, more preferably 5% or more, and even more preferably 10% or more. In this case, the change in hue of the metal member when the angle of the line of sight is changed can be reduced. On the other hand, the developed area ratio Sdr of the interface between the substrate and the transparent layer is preferably 100% or less, more preferably 70% or less, even more preferably 60% or less, and particularly preferably 50% or less. In this case, scattering at the interface between the substrate and the transparent layer and the surface of the reflective layer can be suppressed, and the reflected light reflected at the interface and the reflected light reflected on the surface of the reflective layer can be more reliably interfered with. As a result, the surface of the metal member can be more reliably colored with an interference color.

[0019] In determining a preferred range of the developed area ratio Sdr of the interface, the upper and lower limits of the developed area ratio Sdr can be combined arbitrarily. For example, the developed area ratio Sdr of the interface between the substrate and the transparent layer may be 1% or more and 100% or less, 1% or more and 70% or less, 3% or more and 70% or less, 5% or more and 60% or less, or 10% or more and 50% or less.

[0020] The developed area ratio Sdr of the interface between the substrate and the transparent layer is measured by a method conforming to ISO 25178: 2021. The developed area ratio Sdr can be measured using, for example, a non-contact surface roughness measuring device such as a laser microscope or a white light interference microscope.

[0021] In addition, as a method for controlling the developed area ratio Sdr of the interface between the substrate and the transparent layer within the specific range, for example, a method of forming a transparent layer on the substrate after adjusting the surface property of the substrate during the manufacturing process of the metal component can be adopted. As a method for adjusting the surface property of the substrate, for example, a method of rolling the substrate using a rolling roll having an appropriate surface roughness, a method of polishing the surface of the substrate, etc. can be adopted. The method for polishing the substrate is not particularly limited, and known polishing methods such as mechanical polishing, which polishes the surface of the substrate using an abrasive, electrolytic polishing, which electrochemically dissolves the surface of the substrate, and chemical polishing, which chemically dissolves the surface of the substrate, can be adopted. When adjusting the surface property of the substrate, the above-mentioned method may be performed alone, or multiple methods may be appropriately combined.

[0022] The material constituting the transparent layer may be an organic material or an inorganic material. The transparent layer is preferably composed of an inorganic material. A transparent layer made of an inorganic material is resistant to deterioration due to temperature changes, humidity changes, exposure to sunlight, etc. during use of the metal member, and can maintain its optical properties for a longer period of time. Therefore, by providing a transparent layer made of an inorganic material on the substrate, the color tone of the metal member can be maintained for a longer period of time.

[0023] Furthermore, the transparent layer is preferably composed of an oxide of the metal that constitutes the substrate. Metal oxides are resistant to deterioration due to temperature changes, humidity changes, exposure to sunlight, and the like, so by providing a transparent layer composed of an oxide on the substrate, the color tone of the metal component can be maintained for a longer period of time. Furthermore, in this case, anodizing the substrate allows the transparent layer to grow from the surface of the substrate, thereby preventing the formation of gaps at the interface between the substrate and the transparent layer and the inclusion of foreign matter. As a result, the occurrence of uneven color tone and defects in the metal component can be more effectively suppressed.

[0024] The thickness of the transparent layer is preferably 15 nm or more and 600 nm or less. In this case, light having wavelengths in the visible light region can be intensified by interference between light reflected by the reflective layer and light reflected by the substrate. As a result, the metal member can be colored in various colors. As a method for controlling the thickness of the transparent layer, for example, a method of adjusting the applied voltage during anodizing treatment can be adopted. For example, when anodizing treatment is performed by direct current electrolysis, the thickness of the transparent layer can be increased by increasing the applied voltage.

[0025] A reflective layer configured to reflect a portion of visible light incident on the metal member is provided on the transparent layer. By providing such a reflective layer on the transparent layer, light reflected by the reflective layer and light reflected at the interface between the substrate and the transparent layer interfere with each other, allowing the metal member to develop various color tones. From the viewpoint of further increasing the saturation of the metal member and developing more vivid colors, the average spectral transmittance of the reflective layer in the wavelength range of 400 nm to 700 nm is preferably 2% to 80%, more preferably 20% to 70%, and even more preferably 30% to 60%.

[0026] The average 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 in the wavelength range of 400 nm or more and 700 nm or less. In this case, from the viewpoint of more accurately calculating the average spectral transmittance of the reflective layer, 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. Furthermore, it is preferable that the wavelength intervals at which the spectral transmittance is measured are, for example, 20 nm or less. The arithmetic average of the spectral transmittances at the plurality of wavelengths obtained as described above is taken as the average spectral transmittance of the reflective layer.

[0027] The reflective layer may be made of, for example, a metal or a metal compound. The reflective layer may also contain both a metal and a metal compound. When the reflective layer is made 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 spectral transmittance of the reflective layer can be more easily adjusted to fall within the specified range.

[0028] Examples of metals that can be used to form the reflective layer include aluminum, copper, silver, and platinum. Examples of metal compounds that can be used to form the reflective layer include copper oxide and silver sulfide. Among these, it is preferable that the reflective layer contains copper atoms or silver atoms, from the viewpoint of more reliably obtaining the above-described effects.

[0029] Furthermore, it is more preferable that the reflective layer contains a metal compound. Metal compounds are less likely to deteriorate in the atmosphere, so the optical properties of the reflective layer can be maintained for a longer period of time. Therefore, by providing a reflective layer made of a metal containing a metal compound on a transparent layer, the vivid color tone of the metal member can be maintained for a longer period of time. From the viewpoint of more reliably obtaining such effects, it is preferable that the reflective layer contains copper oxide or silver sulfide, and it is more preferable that it contains copper oxide.

[0030] Furthermore, from the viewpoint of more reliably imparting the above-mentioned optical properties to the reflective layer, it is preferable that the reflective layer contains a plurality of crystal grains, and 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.

[0031] The average grain size of the crystal grains is calculated as follows. First, a 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 circle-equivalent diameters of the crystal grains present in the electron microscope image, i.e., the diameters of circles equal to the cross-sectional areas of the crystal grains, are calculated. The arithmetic mean value of the circle-equivalent diameters of the crystal grains obtained in this way is taken as the average grain size of the crystal grains.

[0032] The reflective layer of the metal member may further be provided with a protective layer made of a substance that transmits visible light, which can prevent deterioration of the reflective layer due to reactions with oxygen, moisture, sulfur, etc. in the atmosphere for a longer period of time, thereby maintaining the vivid chromatic colors of the metal member for a longer period of time.

[0033] The material constituting the protective layer may be either organic or inorganic. Suitable materials for the protective layer include transparent resins such as acrylic resin, methacrylic resin, polycarbonate resin, and nitrocellulose resin, and organic glass.

[0034] As described above, the metal member exhibits a color tone having a substantially constant hue even when the angle of the viewer's line of sight relative to the surface of the metal member is changed, and therefore the metal member can be suitably used in applications where design is required, such as building materials and housings for electronic devices.

[0035] Furthermore, for example, containers equipped with the metal members have high designability and are therefore suitable for applications requiring particularly excellent appearance characteristics, such as cosmetic containers and straws.

[0036] Furthermore, the metal member has the property that the change in hue is small even when the angle of the viewer's line of sight relative to the surface changes, and can be suitably used in MEMS devices such as micromirrors.

[0037] (Method for manufacturing metal member) The metal member can be obtained, for example, by preparing a substrate having a surface developed area ratio Sdr of 1% or more, anodizing the substrate in a weakly acidic or weakly basic electrolyte to form a transparent layer, and then forming a reflective layer on the transparent layer by a sputtering method.

[0038] The method for preparing the substrate used in manufacturing the metal component can take various forms. For example, the substrate may be a wrought material obtained by wrought processing such as rolling or extrusion. The substrate may also be formed into a desired shape by machining or plastic processing. Furthermore, the surface of the substrate may be polished as necessary to adjust the developed surface area ratio Sdr of the substrate to fall within the specified range.

[0039] Next, the substrate is anodized to form a transparent layer on the surface of the substrate. When the substrate is anodized, dissolution of the substrate surface and formation of the transparent layer proceed simultaneously. Furthermore, dissolution of the substrate surface and formation of the transparent layer proceed uniformly on the surface of the substrate. Therefore, the developed area ratio Sdr of the interface between the substrate surface and the transparent layer after anodization is approximately equal to the developed area ratio Sdr of the substrate surface before anodization.

[0040] The electrolytic solution used in 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, phosphate, borate, adipic acid, or the like is used as an electrolyte, and an electrolytic solution having a pH of 3.5 or more and 7 or less can be used. Furthermore, as the weakly basic electrolytic solution, for example, borate, phosphate, or the like is used as an electrolyte, and an electrolytic solution having a pH of 7 or more and 8 or less can be used.

[0041] In addition, the treatment method for anodizing is preferably either DC electrolysis performed by applying a voltage of 10 V to 400 V, AC electrolysis performed by applying a voltage so that the peak voltage is 10 V to 400 V, or pulse electrolysis. The transparent layer formed in this manner is made of an oxide of the metal that constitutes the substrate and does not have pores, so light scattering in the transparent layer can be further reduced. Therefore, by performing anodizing treatment using the above-mentioned treatment method, metal parts with vivid chromatic colors can be more easily obtained.

[0042] Furthermore, the sputtering method is preferably DC magnetron sputtering. In this case, the thickness variation 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, DC magnetron sputtering makes it easier to control the grain size of the crystal grains in the reflective layer. Therefore, by performing sputtering using the above-mentioned method, it is possible to more easily form a reflective layer having desired optical properties on the transparent layer, and more easily obtain a metal member having a vivid chromatic color.

[0043] For example, argon can be used as the atmospheric gas in the chamber in DC magnetron sputtering. 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 set to 0.1 mA / cm. ２ 7mA / cm or more ２ It is preferable that the following conditions are satisfied: By performing DC magnetron sputtering under such conditions, a reflective layer having desired optical properties can be more easily formed on the transparent layer.

[0044] An example of the metal member will be described with reference to FIG. 1 . As shown in FIG. 1 , the metal member 1 of this example includes a substrate 2 made of metal, a transparent layer 3 made 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 developed area ratio Sdr of the interface 21 between the substrate 2 and the transparent layer 3 is 1% or more. The reflective layer 4 is configured to reflect a portion of the visible light incident on the reflective layer 4. The metal member 1 of this example is obtained by anodizing a substrate 2 having a surface developed area ratio Sdr of 1% or more to form the transparent layer 3, and then forming the reflective layer 4 on the transparent layer 3.

[0045] Next, a specific configuration of the metal member 1 of this example and an example of a manufacturing method thereof will be described. In manufacturing the metal member 1 of this example, first, base materials A to E shown in Table 1 are prepared. Each of base materials A to E is an aluminum plate having a chemical composition represented by alloy number A1050, and has a developed area ratio Sdr shown in Table 1.

[0046] Substrates A to D can be obtained, for example, by polishing the surface of an aluminum plate in multiple stages while changing the type of abrasive, and in the final stage, polishing using abrasive paper carrying abrasive grains with the particle sizes shown in Table 1. Substrate E can be obtained, for example, by polishing the surface of an aluminum plate in multiple stages while changing the type of abrasive, and in the final stage, polishing using an abrasive containing diamond abrasive grains with a particle size of 6 μm ("MetaDi (registered trademark) Supreme 6 μm" manufactured by BUEHLER) and a lubricant ("DP-Lubricant Red" manufactured by Struers). Substrate F shown in Table 1 is a substrate for comparison with substrates A to E. Substrate F is, specifically, an aluminum rolled plate having a chemical composition represented by alloy number A1050.

[0047] Next, after pretreatment such as cleaning is performed on the substrates A to E, the substrates are anodized to form a barrier-type anodic oxide film as a transparent layer on the surface of the substrate. DC electrolysis is used as the anodizing method, and the applied voltage is increased to the values ​​shown in Tables 2 to 4 over 2.5 minutes from the start of the treatment. Furthermore, a weakly basic electrolytic solution containing 0.5 mol / L boric acid and 0.05 mol / L sodium tetraborate is used as the electrolyte in the anodizing treatment. The temperature of the electrolytic solution in the anodizing treatment is 20°C. The thickness of the transparent layer formed under these conditions is as shown in Tables 2 to 4.

[0048] Then, a reflective layer made of copper is formed on the transparent layer by DC magnetron sputtering. In this example, the reflective layer has a thickness of 5 nm and an average spectral transmittance of 56.6% in the wavelength range of 400 nm to 700 nm. In forming the reflective layer in this example, argon is used as the atmospheric gas in the DC magnetron sputtering chamber, the degree of vacuum in the chamber is set to 0.05 Pa to 5 Pa, and the current density applied to the sputtering target is set to 0.1 mA / cm. ２ 7mA / cm or more ２ The method for measuring the spectral transmittance of the reflective layer will be described later.

[0049] As a result of the above, test materials A1 to E1 shown in Table 2, test materials A2 to E2 shown in Table 3, and test materials A3 to E3 shown in Table 4 can be obtained.

[0050] Note that test material F1 shown in Table 2, test material F2 shown in Table 3, and test material F3 shown in Table 4 are test materials for comparison with test materials A1 to E1, test materials A2 to E2, and test materials A3 to E3. Test materials F1 to F3 have the same configuration as test materials A1 to E1, test materials A2 to E2, and test materials A3 to E3, except that the developed area ratio Sdr of the interface between the substrate and the transparent layer is outside the specific range. The manufacturing method of test materials F1 to F3 is the same as the manufacturing method of test materials A1 to E1, test materials A2 to E2, and test materials A3 to E3, except that substrate F is used.

[0051] Next, the methods for evaluating the average spectral transmittance of the reflective layer and the color tone of the metal member shown in Tables 2 to 4 will be described.

[0052] [Average value of spectral transmittance of reflective layer] A reflective layer is formed on a glass substrate by the same processing method as the sputtering process for each test material, and the spectral transmittance of this reflective layer at various wavelengths is measured at 10 nm intervals within a wavelength range of 400 nm to 700 nm. The light source used in measuring the spectral transmittance is auxiliary illuminant C specified in JIS Z8720:2012. The geometric conditions during measurement are geometric conditions f represented by the symbol 0 °:di in JIS Z8722:2009 (i.e., light is irradiated from a direction where the angle with respect to the normal line of the surface of the transmissive layer is 0 °, and all transmitted light, including regular transmitted light, is collected), and the light is irradiated onto a measurement area with a diameter of 30 mm.

[0053] The spectral transmittance at each wavelength obtained by the above method includes the contribution of light absorption in the glass substrate as well as the contribution of light absorption in the reflective layer. ｒ is the spectral transmittance T at each wavelength obtained by measuring the reflective layer on the glass substrate. ｍ and the spectral transmittance of the glass substrate at each wavelength is T ｇｌａｓｓ and can be calculated based on the following formula (1): ｒ =T ｍ × (100 / Tｇｌａｓｓ ) ... (1)

[0054] The spectral transmittance T measured at each wavelength in this manner ｍ After correcting to remove the influence of the glass substrate, the corrected spectral transmittance T ｒ By arithmetically averaging the values, the average value of the spectral transmittance of the reflective layer can be obtained.

[0055] [Change in Color Tone of Metal Member] The change in color tone of the metal member is evaluated based on the results of visual observation and the gradation of digital photographs when the surface of the metal member is observed from various directions. As shown in Figure 2, the evaluation device 5 used to evaluate the change in color tone has an imaging stand 51 configured so that the inclination angle with respect to the horizontal plane can be changed, and a camera 52 placed vertically above the imaging stand 51. Note that a single-lens reflex camera "EOS (registered trademark) 8000D" manufactured by Canon Inc. is used as the camera 52, and images are taken with the ISO sensitivity set to automatic (AUTO), the F-number set to 8, and the exposure time set to 0.5 seconds.

[0056] To perform the evaluation, first, the test material T is placed on the photographing table 51 with its surface horizontal. Then, white light is irradiated from above the test material T to set the illuminance on the surface of the test material T to 900 lux or more. An LED bar (Toshiba Lighting, LEEM-40523N-01) attached to an LED bar fixture (Toshiba Lighting, LEET-41201-LS9) is used as the light source, and the distance from the light source to the test material is 2 m or more. Furthermore, to irradiate the test material T with white light from a direction as close to vertically above as possible while avoiding the white light being blocked by the camera 52, the light source is installed in a position where the line connecting the center of the light source and the center of the test material T is inclined at approximately 10° to 40° with respect to the vertical. In this state, the test material T is photographed using the camera 52 under the above-mentioned photographing conditions, and a digital photograph of the test material T is obtained. The above procedure is repeated by tilting the photographing table 51 to change the angle of the surface of the test material T relative to the horizontal plane to 15°, 30°, 45°, 60°, and 75°, and digital photographs are taken at each angle.

[0057] The color tone at the center of the digital photograph thus obtained is expressed as RGB values ​​in the sRGB color space, and the results of visual evaluation are shown in Table 2. ave In the " column, the average value of the amount of change in the RGB values ​​calculated by the following formula (2) using the above-mentioned RGB values ​​is shown.

[0058]

[0059] In addition, R in the formula (2) k is the gradation of the R channel at the center of a digital photograph taken with the angle of the surface of the test material relative to the horizontal plane set to k°, and G k is the gradation of the G channel at the center of the digital photograph taken with the angle of the test material set to k°, and B k is the gradation of the B channel at the center of the digital photograph taken with the angle of the test material set to k°. R, G, and B are each integers between 0 and 255, and the higher the luminance of each channel, the larger the R, G, and B values.

[0060] As can be seen from the above formula (2), ΔRGB ave The value of ΔRGB is the average change in the gradation of each channel when the angle of the surface of the test material changes by 15°. ave The larger the value, the greater the change in color tone when the angle of the imaging table is changed.

[0061]

[0062]

[0063]

[0064]

[0065] As shown in Table 2, test materials A1 to E1 were prepared using substrates with a developed area ratio Sdr within the specified range, and therefore the developed area ratio Sdr of the interface between the substrate and the transparent layer in these test materials falls within the specified range. Therefore, these test materials tend to exhibit small changes in the hue of the surface of the test material when the angle of the observer's line of sight relative to the surface changes. Therefore, test materials A1 to E1 exhibit a color tone with roughly the same hue even when the angle of the observer's line of sight relative to the surface changes.

[0066] Furthermore, as can be seen from Tables 3 and 4, test materials A2 to E2 and A3 to E3, which have the same configuration as test materials A1 to E1 except for the thickness of the transparent layer, exhibit color tones with roughly the same hue, just like test materials A1 to E1, even when the angle of the observer's line of sight relative to their surface changes.

[0067] In contrast, test materials F1 to F3 were produced using substrates whose developed area ratios Sdr were outside the specific range, and therefore the developed area ratios Sdr of the interfaces between the substrates and the transparent layers in test materials F1 to F3 were outside the specific range, and therefore the changes in the hue of the surfaces of test materials F1 to F3 were likely to be large when the angle of the viewer's line of sight with respect to the surfaces of test materials F1 to F3 changed.

[0068] The above describes specific aspects of the metal member according to the present invention based on examples, but the aspects of the metal member, MEMS device, container, and straw according to the present invention are not limited to the aspects of the examples, and the configuration can be changed as appropriate within the scope that does not detract from the spirit of the present invention.

[0069] For example, the metal member may take the following forms [1] to [9].

[0070] [1] A metal member comprising: a substrate made of metal; a transparent layer made of a substance that transmits visible light and provided on the substrate; and a reflective layer provided on the transparent layer, wherein the reflective layer is configured to reflect a portion of the visible light incident on the reflective layer, and a developed area ratio Sdr of the interface between the substrate and the transparent layer is 1% or more.

[0071] [2] The metal member according to [1], wherein the average spectral transmittance of the reflective layer in the wavelength range of 400 nm to 700 nm is 2% to 80%. [3] The metal member according to [1] or [2], wherein the transparent layer is made of an oxide of the metal that constitutes 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 to 600 nm.

[0072] [5] The metallic 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 to 30 nm. [6] The metallic member according to any one of [1] to [5], wherein the reflective layer contains copper atoms or silver atoms. [7] The metallic 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 to 15 nm.

[0073] [8] The metal member according to any one of [1] to [7], wherein the substrate is made of aluminum or an aluminum alloy. [9] The metal member according to any one of [1] to [8], further comprising a protective layer made of a substance that transmits visible light and provided on the reflective layer.

[0074] The MEMS device according to the present invention may take the following form (10), for example:

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

[0075] The container according to the present invention may take the following form (11): (11) A container having the metal member according to any one of (1) to (9).

[0076] The straw according to the present invention can take the following form (12), for example:

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

Claims

1. A metal component comprising: a substrate made of a metal; a transparent layer made of a substance that transmits visible light and provided on the substrate; and a reflective layer provided on the transparent layer, wherein the reflective layer is configured to reflect a portion of light incident on the reflective layer, and a developed area ratio Sdr of the interface between the substrate and the transparent layer is 1% or more.

2. The metal member according to claim 1, wherein the average spectral transmittance of the reflective layer in the wavelength range 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 or 2, wherein the transparent layer is made of an oxide of the metal that constitutes the base material.

4. The metal member according to any one of claims 1 to 3, wherein the transparent layer has a thickness of 15 nm or more and 600 nm or less.

5. The metal member according to any one of claims 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 claims 1 to 5, wherein the reflective layer contains copper atoms or silver atoms.

7. The metal member according to any one of claims 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.

8. The metal component according to any one of claims 1 to 7, wherein the substrate is made of aluminum or an aluminum alloy.

9. The metal member according to any one of claims 1 to 8, further comprising a protective layer made of a substance that transmits visible light and provided on the reflective layer.

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

11. A container having a 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.

Images