Electromagnetic wave-transmitting metallic luster member, and method for manufacturing the same

Abstract

The present invention pertains to an electromagnetic wave-transmitting metallic lustrous member that comprises: a base body; and a metal layer formed on the base body. The metal layer includes a plurality of portions that are at least partially discontinuous with each other. The metal layer contains aluminum elements and indium elements, and the contained amount of the indium elements in the metal layer is more than 90 mass% but not more than 98 mass%.

Description

[Technical Field]

[0001] The present invention relates to an electromagnetic wave-transmitting metallic luster member and a method for manufacturing the same. [Background technology]

[0002] Conventionally, materials possessing electromagnetic wave transparency and metallic luster have been suitably used in devices that transmit and receive electromagnetic waves because they combine the high-quality appearance derived from their metallic luster with electromagnetic wave transparency.

[0003] When metal is used in components with a metallic sheen, the transmission and reception of electromagnetic waves becomes virtually impossible or is interfered with. Therefore, in order to avoid interfering with the transmission and reception of electromagnetic waves without compromising the aesthetic appeal, there is a need for electromagnetic wave-transmitting metallic components that possess both a metallic sheen and electromagnetic wave transparency.

[0004] Such electromagnetic wave-transmitting metallic luster materials are expected to have applications as devices that transmit and receive electromagnetic waves in various devices that require communication, such as car door handles equipped with smart keys, in-vehicle communication equipment, mobile phones, personal computers, and other electronic devices. Furthermore, with the recent development of IoT technology, applications are also expected in a wide range of fields, such as home appliances like refrigerators and other household equipment, where communication was not previously performed.

[0005] Regarding electromagnetic wave-transmitting metallic luster members, Patent Document 1 describes an electromagnetic wave-transmitting metallic luster member comprising an indium oxide-containing layer provided on the surface of a substrate and a metal layer laminated on the indium oxide-containing layer, wherein the metal layer includes a plurality of portions that are discontinuous from each other in at least a part of them. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-69462 [Overview of the project] [Problems that the invention aims to solve]

[0007] In such electromagnetic wave-transmitting metallic luster components, when manufacturing 3D molded products by bending and stretching, cracks occur in areas with high elongation, leading to clouding and discoloration. This is because when the metal layer is formed through an underlying layer such as an indium oxide-containing layer, cracks originating from this underlying layer occur. When cracks occur, clouding and discoloration are impaired, making it impossible to achieve both good electromagnetic wave transmittance and luster simultaneously.

[0008] Furthermore, when electromagnetic wave-transmitting metallic luster components are used in electronic devices such as smartphones, there is a need to improve their durability against humidification and heating so that their quality does not deteriorate due to the effects of humidity and heat.

[0009] The present invention was made to solve the above problems, and aims to provide an electromagnetic wave-transmitting metallic luster member that has excellent electromagnetic wave transmittance and luster, suppresses clouding and discoloration caused by stretching, and has excellent durability against humidification and heating. [Means for solving the problem]

[0010] The inventors of the present invention have conducted extensive research to solve the above problems and have found that the above problems can be solved by discontinuously providing a metal layer containing aluminum and indium elements, and a specific amount of indium, on a substrate, and have completed the present invention.

[0011] In other words, the present invention is as follows. [1] It comprises a substrate and a metal layer formed on the substrate, The metal layer includes a plurality of portions that are discontinuous from each other in at least part of the way. The aforementioned metal layer contains aluminum and indium. The content of the indium element in the metal layer is more than 90% by mass and at most 98% by mass. Electromagnetic wave transmissive metallic luster member. [2] The aluminum element is unevenly distributed in the metal layer, the electromagnetic wave transmissive metallic luster member according to [1]. [3] The metal layer contains at least one element selected from Sn, Si, Ga, Ge, and Pb, the electromagnetic wave transmissive metallic luster member according to [1] or [2]. [4] The thickness of the metal layer is from 10 nm to 100 nm, the electromagnetic wave transmissive metallic luster member according to any one of [1] to [3]. [5] After a humidification heating test at 65 °C and 90% RH, the Y value (SCI) measured using a spectrophotometer in accordance with the geometric condition c of JIS Z 8722 is 40% or more, the electromagnetic wave transmissive metallic luster member according to any one of [1] to [4]. [6] The plurality of portions are formed in an island shape, the electromagnetic wave transmissive metallic luster member according to any one of [1] to [5]. [7] The substrate is any one of a base film, a resin molded article substrate, or an article to be provided with metallic luster, the electromagnetic wave transmissive metallic luster member according to any one of [1] to [6]. [8] A first step of forming a layer including a plurality of portions that contain at least indium element and are in a discontinuous state with each other at least in part, on a substrate; A second step of depositing a metal containing aluminum element on above the layer formed in the first step, including: A method for manufacturing an electromagnetic wave transmissive metallic luster member according to any one of [1] to [7]. [9] In the first step, the layer is formed by sputtering in an atmosphere substantially free of oxygen, the method according to [8].

Advantages of the Invention

[0012] According to the present invention, it is possible to provide an electromagnetic wave-transmitting metallic luster member that has excellent electromagnetic wave transmittance and luster, suppresses clouding and discoloration caused by stretching, and has excellent durability against humidification and heating. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a schematic cross-sectional view of an electromagnetic wave-transmitting metallic glossy member 1 according to one embodiment of the present invention. [Figure 2] Figure 2 is an electron microscope image (SEM image) of the surface of the electromagnetic wave-transmitting metallic luster member 1 according to Example 2. [Figure 3] Figure 3 is a diagram illustrating a method for measuring the thickness of the metal layer of an electromagnetic wave-transmitting metallic gloss member according to one embodiment of the present invention. [Figure 4] Figure 4 is a photographic diagram showing the distribution of Al and In elements when elemental analysis was performed on the electromagnetic wave-transmitting metallic glossy member of Example 2. (a) is a TEM image of the metal layer, (b) is a TEM image showing the distribution of Al elements in the metal layer, (c) is a TEM image showing the distribution of In elements in the metal layer, and (d) is a photographic diagram superimposed on the TEM image showing the distribution of Al elements and the TEM image showing the distribution of In elements in the metal layer. [Modes for carrying out the invention]

[0014] The present invention will be described in detail below with reference to the attached drawings, but the present invention is not limited to the following embodiments and can be modified and implemented as such without departing from the spirit of the invention. Furthermore, the "~" symbol, which indicates a numerical range, is used to mean that the numbers written before and after it are included as the lower and upper limits, respectively. Furthermore, in this specification, "weight" and "mass," as well as "weight%" and "wt%" and "mass%," shall be treated as synonyms.

[0015] An electromagnetic wave-transmitting metallic luster member according to an embodiment of the present invention comprises a substrate and a metal layer formed on the substrate, The metal layer includes a plurality of portions that are discontinuous from each other in at least part of the way. The aforementioned metal layer contains aluminum and indium. The content of the indium element in the metal layer is greater than 90% by mass and less than or equal to 98% by mass.

[0016] <1.Basic configuration> An electromagnetic wave-transmitting metallic glossy member according to an embodiment of the present invention comprises a substrate and a metal layer formed on the substrate, wherein the metal layer includes a plurality of portions that are discontinuous from each other in at least part of the way.

[0017] Figure 1 shows a schematic cross-sectional view of an electromagnetic wave-transmitting metallic luster member 1 according to one embodiment of the present invention, and Figure 2 shows an example of an electron microscope image (SEM image) of the surface of the electromagnetic wave-transmitting metallic luster member 1 according to one embodiment of the present invention (Example 2). The image size in the electron microscope image is 6 μm × 5 μm.

[0018] As shown in Figure 1, the electromagnetic wave-transmitting metallic glossy member 1 includes a substrate 10 and a metal layer 12 formed on the substrate 10. In the electromagnetic wave-transmitting metallic gloss member 1, a discontinuous metal layer 12 is formed on a substrate 10, and it is preferable that no underlayer is formed between the substrate 10 and the metal layer 12. By not forming an underlayer between the substrate 10 and the metal layer 12, whitening and discoloration caused by stretching can be suppressed. However, a layer that is less likely to cause whitening or discoloration due to stretching (such as a protective layer) may be provided between the substrate 10 and the metal layer 12. Details will be explained below in <4. Other Layers>.

[0019] The metal layer 12 includes multiple portions 12a. These portions 12a are discontinuous in at least some respects, in other words, separated in at least some respects by gaps 12b. Because they are separated by gaps 12b, the sheet resistance of these portions 12a increases, reducing their interaction with radio waves, and thus allowing radio waves to pass through. Each of these portions 12a is an aggregate of sputtered particles formed by depositing metal. When sputtered particles form a thin film on a substrate such as the substrate 10, the surface diffusivity of the particles on the substrate affects the shape of the thin film.

[0020] In this specification, "discontinuous state" refers to a state in which the sheets are separated from each other by gaps 12b, and as a result, are electrically insulated from each other. By being electrically insulated, the sheet resistance increases, and the desired electromagnetic wave transmission is achieved. The form of the discontinuity is not particularly limited and includes, for example, island-like structures, crack structures, etc.

[0021] Figure 2 is an example of an electron microscope image (SEM image) of the surface of the metal layer of the electromagnetic wave-transparent metallic luster member 1. "Island-like" refers to a structure in which the sputtered particle aggregates are independent of each other, and these particles are arranged in a state where they are slightly separated from each other or partially in contact with each other, as shown in Figure 2.

[0022] Furthermore, a crack structure is a structure in which a thin metal film is divided by cracks. It should be noted that such a crack structure is distinct from the cracks that occur during stretching, as described above.

[0023] A metal layer 12 with a crack structure can be formed, for example, by providing a thin metal film layer on a substrate and bending and stretching it to induce cracks in the thin metal film layer. In this case, a brittle layer made of a material with poor elasticity, i.e., a material that easily generates cracks when stretched, can be provided between the substrate and the thin metal film layer to easily form a metal layer 12 with a crack structure.

[0024] As described above, the manner in which the metal layer 12 is discontinuous is not particularly limited, but from the viewpoint of productivity, it is preferable to have an "island-like" structure.

[0025] The electromagnetic wave permeability of the electromagnetic wave permeable metallic luster member 1 can be evaluated, for example, by the radio wave transmission attenuation. The radio wave transmission attenuation can be measured, for example, by the method described later in the examples.

[0026] Specifically, the radio wave transmission attenuation at 28 GHz can be evaluated using a KEC method measurement and evaluation jig and an Agilent CXA signal analyzer NA9000A spectrum analyzer. There is a correlation between the electromagnetic wave transmission in the frequency band of millimeter-wave radar (76-80 GHz) and the electromagnetic wave transmission in the microwave band (28 GHz), and they show relatively close values. Therefore, the electromagnetic wave transmission in the microwave band (28 GHz), i.e., the microwave field transmission attenuation, is used as the indicator.

[0027] The radio wave transmission attenuation in the microwave band (28 GHz) is preferably 1 dB or less, more preferably 0.3 dB or less, and even more preferably 0.1 dB or less. By setting the radio wave transmission attenuation in the microwave band (28 GHz) to 1 dB or less, the problem of more than 20% of the radio waves being blocked can be avoided.

[0028] The luster (appearance) of the electromagnetic wave-transmitting metallic luster component 1 can be evaluated by measuring, for example, the Y value (SCI, SCE) and the ΔE value. The Y value (SCI, SCE) and ΔE value can be measured using a spectrophotometer in accordance with geometric condition c of JIS Z 8722.

[0029] The durability of the electromagnetic wave-transmitting metallic luster component 1 against humidified heating can be evaluated by the above-mentioned luster (appearance) indicators before and after a humidified heating test at 65°C and 90%RH.

[0030] The larger the Y value (SCI) after the humidification and heating test, the more it indicates that the decrease in brightness due to humidification and heating can be suppressed. The Y value (SCI) after the humidification and heating test is preferably 40% or more, more preferably 50% or more, and even more preferably 60% or more. When the Y value (SCI) is 40% or more, the brightness is good and the appearance is excellent. Also, the upper limit of the Y value (SCI) after the humidification and heating test is not particularly limited, but for example, it is 70% or less.

[0031] The ΔE value is an index indicating a change in color tone, and is based on the L * value, a * value, b * value (L1 * , a1 * , b1 * ) before the humidification and heating test and the L * value, a * value, b * value (L2 * , a2 * , b2 * ) after the humidification and heating test, and is defined by the following formula. ΔE = √[(L1 * - L2 * ) 2 + (a1 * - a2 * ) 2 + (b1 * - b2 * ) 2

[0032] The smaller the ΔE value, the more it indicates that the change in color tone due to humidification and heating can be suppressed. The ΔE value is preferably 3 or less, more preferably 2 or less, and even more preferably 1 or less.

[0033] Also, the stretch resistance of the electromagnetic wave-transmissive metallic gloss member 1 can be evaluated by each index of the above-mentioned brightness (appearance) before and after the tensile test performed under the conditions of 150 °C, a stretching speed of 5 mm / min, and an elongation rate of 20% using a tensile testing machine.

[0034] A higher Y-value (SCI) after the tensile test indicates that the reduction in luster due to stretching has been suppressed. A Y-value (SCI) of 40% or higher is preferable, 50% or higher is more preferable, and 55% or higher is even preferable. A Y-value (SCI) of 40% or higher indicates good luster and excellent appearance.

[0035] Furthermore, a smaller Y-value (SCE) after the tensile test indicates that the clouding due to stretching has been suppressed. The Y-value (SCE) after the tensile test is preferably 1 or less, more preferably 0.3 or less, and even more preferably 0.1 or less. If the Y-value (SCE) is greater than 1, the appearance becomes cloudy, resulting in a poor appearance.

[0036] The tensile properties of the electromagnetic wave-transmitting metallic luster member 1 can also be evaluated by measuring the crack width of the metal layer after a tensile test. The tensile test is performed, for example, in the same manner as the luster (appearance) test described above. The smaller the crack width of the metal layer after the tensile test, the better the crack formation due to stretching is suppressed, indicating excellent stretch resistance. The crack width of the metal layer after the tensile test is preferably 170 nm or less, more preferably 160 nm or less, and even more preferably 150 nm or less.

[0037] <2.Base> Examples of substrates 10 from the viewpoint of electromagnetic wave permeability include base film, resin molded substrate, or articles to which metallic luster should be imparted.

[0038] More specifically, as the base film, transparent films made of homopolymers or copolymers of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate, polyamide, polyvinyl chloride, polycarbonate (PC), cycloolefin polymer (COP), polystyrene, polypropylene (PP), polyethylene, polycycloolefin, polyurethane, acrylic (PMMA), ABS, etc. can be used.

[0039] These components do not affect luster or electromagnetic wave transmittance. However, from the viewpoint of later forming the metal layer 12, it is preferable that they can withstand high temperatures such as those for vapor deposition. For this reason, among the above materials, polyethylene terephthalate, polyethylene naphthalate, acrylic, polycarbonate, cycloolefin polymer, ABS, polypropylene, and polyurethane are preferred. Among these, polyethylene terephthalate, cycloolefin polymer, polycarbonate, and acrylic are preferred because they offer a good balance between heat resistance and cost.

[0040] The base film may be a single-layer film or a laminated film. For ease of processing, the thickness is preferably, for example, about 6 μm to 250 μm. Plasma treatment or an easy-adhesion treatment may be applied to strengthen the adhesion with the metal layer 12. Furthermore, it is preferable that the film does not contain particles.

[0041] It should be noted here that the base film is merely one example of an object (substrate 10) on which a metal layer 12 can be formed on its surface. The substrate 10 includes, as described above, not only the base film but also resin molded substrates and the articles themselves to which metallic luster should be applied. Examples of resin molded substrates and articles to which metallic luster should be applied include vehicle structural parts, vehicle-mounted accessories, electronic equipment casings, home appliance casings, structural parts, machine parts, various automotive parts, electronic equipment parts, furniture, kitchenware and other household goods, medical equipment, building material parts, and other structural and exterior parts.

[0042] <3.Metal layer> The metal layer 12 is formed on the substrate 10. As described above, the metal layer 12 may be directly provided on the surface of the substrate 10, or it may be provided indirectly via a protective layer or other layer provided on the surface of the substrate 10 that is less likely to cause cracks due to stretching. The metal layer 12 is a layer having a metallic appearance and preferably a layer having a metallic luster.

[0043] The metal layer 12 contains aluminum and indium. In particular, it is preferable that the aluminum is unevenly distributed within the metal layer 12. That is, as shown in Figure 4, it is preferable that the aluminum is not uniformly scattered throughout the metal layer 12, but rather concentrated in certain regions of the metal layer 12. As long as the aluminum is unevenly distributed within the metal layer 12, there are no restrictions on the manner in which it is distributed, but as shown in Figure 4, it is preferable that the aluminum is unevenly distributed around the region where the indium is present. In other words, it is preferable that the aluminum is unevenly distributed within the metal layer 12 so as to surround the indium. Furthermore, it is preferable that the aluminum element and the indium element are substantially incompatible with each other in the metal layer 12. Here, substantially incompatible means that in the range where the depth from the surface of the metal layer 12 is greater than 14 nm, the aluminum element and the indium element are not compatible with each other (they are not alloyed). It is presumed that the reason why the aluminum element and the indium element exist in the metal layer substantially incompatible with each other is because the sputtering temperature is low.

[0044] The indium content in the metal layer 12 is more than 90% by mass and less than or equal to 98% by mass. The indium content being more than 90% by mass results in a disc-shaped island, providing excellent resistance to humidification and heating. Furthermore, the indium content being 98% by mass or less results in the presence of aluminum in the surrounding layer, further enhancing durability. The indium content in the metal layer 12 is preferably 92% by mass or more. Furthermore, the indium content in the metal layer 12 is preferably 96% by mass or less.

[0045] The indium element mentioned above may be included as elemental indium or as an indium alloy, and is not particularly limited. Examples include In-Sn, In-Cr, and In-Zn. However, as stated above, alloys of indium and aluminum are not included.

[0046] The aluminum content in the metal layer 12 is preferably 2% by mass or more, and more preferably 4% by mass or more. A content of 2% by mass or more allows for the formation of an aluminum oxide film around the indium. Furthermore, the aluminum content in the metal layer 12 is preferably 10% by mass or less, and more preferably 8% by mass or less.

[0047] The above-mentioned aluminum element may be included as elemental aluminum or as an aluminum alloy, and is not particularly limited. Examples include Cu, Mn, Si, Mg, Zn, Ni, etc. However, as mentioned above, alloys of indium and aluminum are not included.

[0048] The metal layer 12 may contain other metallic elements. Preferably, it contains at least one of the following elements: Sn, Si, Ga, Ge, and Pb. These may exist in the metal layer as individual elements or in an alloy state. For example, Sn may be included in the metal layer in the form of an ITM (indium tin-metal alloy), which is an alloy with the element indium. The inclusion of the above-mentioned other metallic elements in the metal layer 12 improves its resistance to humidification and heating.

[0049] From the viewpoint of exhibiting sufficient metallic luster, the thickness of the metal layer 12 is preferably 10 nm or more, more preferably 40 nm or more, even more preferably 60 nm or more, and particularly preferably 80 nm or more. On the other hand, from the viewpoint of sheet resistance and electromagnetic wave transmittance, it is preferably 100 nm or less, more preferably 80 nm or less, and even more preferably 60 nm or less. This thickness is also suitable for forming a uniform film with good productivity, and the final resin molded product has a good appearance. The thickness of the metal layer 12 can be measured, for example, by the method described later in the examples.

[0050] The metal layer 12 is formed on the substrate 10 and includes multiple portions that are discontinuous from each other in at least some respects. If the metal layer 12 is continuous on the substrate 10, sufficient metallic luster can be obtained, but the radio wave transmission attenuation becomes very large, and therefore, electromagnetic wave transparency cannot be ensured.

[0051] To form a discontinuous metal layer 12 on the substrate 10, it is preferable to lower the oxygen concentration in the metal layer 12. When sputtered particles from metal deposition form a thin film on the substrate, the surface diffusivity of the particles on the substrate affects the shape of the thin film. It is thought that a discontinuous structure is more easily formed when the substrate temperature is high, the wettability of the metal layer to the substrate is low, and the melting point of the metal layer material is low. It is thought that by using a sputtering material that is substantially oxygen-free on the substrate, or by performing deposition in a substantially oxygen-free atmosphere, the surface diffusivity of the metal particles on the substrate surface is promoted, and the metal layer can be formed in a discontinuous state.

[0052] The equivalent circular diameter of portion 12a of the metal layer 12 is not particularly limited, but is usually 10 to 1000 nm. The average grain size of multiple portions 12a refers to the average value of the equivalent circular diameters of multiple portions 12a. Furthermore, the equivalent circular diameter of portion 12a refers to the diameter of a perfect circle corresponding to the area of ​​portion 12a. Furthermore, the distance between each portion 12a is not particularly limited, but it is usually around 10 to 1000 nm.

[0053] <4. Other layers> Furthermore, the electromagnetic wave-transmitting metallic gloss member 1 according to the embodiment of the present invention may include other layers in addition to the metal layer 12 described above, depending on the application. However, if two or more continuous layers are formed on the substrate 10, cracks in the continuous layers due to stretching are likely to occur. Therefore, if other layers are provided between the substrate 10 and the metal layer 12, it is preferable that these layers are less likely to cause cracks.

[0054] Other layers include, for example, optical adjustment layers (color adjustment layers) made of high refractive index materials to adjust appearance such as color, protective layers (scratch-resistant layers) to improve durability such as scratch resistance, barrier layers (corrosion-resistant layers), easy-adhesion layers, hard coat layers, anti-reflective layers, light extraction layers, and anti-glare layers.

[0055] <5. Method for manufacturing electromagnetic wave-transmitting metallic luster member> The method for manufacturing an electromagnetic wave-transmitting metallic luster member according to this embodiment is characterized by comprising: a first step of forming a layer (hereinafter simply referred to as a discontinuous layer or first layer) on a substrate which contains at least indium and includes a plurality of parts that are discontinuous with each other in at least a part; and a second step of depositing a metal containing aluminum onto the discontinuous layer. Each step will be described in detail below.

[0056] (1) First step In this process, a layer is formed on the substrate 10 that contains at least indium and includes multiple portions that are discontinuous with each other in at least part.

[0057] The discontinuous layer described above can be formed, for example, by depositing a metal containing indium onto the surface of the substrate 10. Examples of deposition methods include physical deposition methods such as vacuum deposition, sputtering, and ion plating, and chemical deposition methods (CVD) such as plasma CVD, photo-CVD, and laser CVD. Physical deposition is preferred, and sputtering is more preferred. This method allows for the formation of a uniform, thin, discontinuous layer.

[0058] In particular, it is preferable to form a discontinuous layer by sputtering using a metal target material that contains indium and is substantially oxygen-free (1 volume % or less). It is even more preferable that the metal target material is oxygen-free. By being oxygen-free, such a metal target material can reduce its wettability with the substrate, thereby promoting the formation of a discontinuous layer on the substrate 10. For the same reason, when forming the discontinuous layer, it is preferable to perform the deposition in an atmosphere that is substantially oxygen-free (100 volume ppm or less), and it is even more preferable to perform the deposition in an atmosphere that is oxygen-free.

[0059] The indium element contained in the metal target material may be indium element or indium alloy, and is not particularly limited. Examples include In-Sn, In-Cr, and In-Zn. Furthermore, the above-mentioned metal target material may contain metals containing indium, as well as silver (Ag), chromium (Cr), and the like.

[0060] Sputtering is performed under vacuum. Specifically, the atmospheric pressure during sputtering is, for example, 1 Pa or less, preferably 0.7 Pa or less, from the viewpoint of suppressing a decrease in the sputtering rate and ensuring discharge stability.

[0061] The power supply used in the sputtering method may be, for example, a DC power supply, an AC power supply, an MF power supply, or an RF power supply, or a combination thereof.

[0062] Furthermore, in order to form a discontinuous layer of the desired thickness, sputtering may be performed multiple times by appropriately setting the metal target material and sputtering conditions.

[0063] (2)Second process Next, a metal containing aluminum is deposited onto the formed discontinuous layer. The deposition method can be the same as that used in the first step described above.

[0064] As the metal target material, a metal containing aluminum is used. The aluminum element may be contained in the metal target material as elemental aluminum, an aluminum compound, or an aluminum alloy.

[0065] Furthermore, the above-mentioned metal target material may contain metals containing aluminum, as well as zinc (Zn), lead (Pb), copper (Cu), silver (Ag), and the like.

[0066] According to the manufacturing method of this embodiment, a discontinuous metal layer containing aluminum and indium elements can be formed on a substrate. The metal layer is formed to contain more than 90% by mass and no more than 98% by mass of indium. As described above, the aluminum and indium elements exist in the metal layer immiscibly from each other. That is, the aluminum and indium elements exist in the metal layer without forming an alloy.

[0067] <6. Applications of electromagnetic wave-transmitting metallic luster components> The electromagnetic wave-transmitting metallic luster member of this embodiment is preferable for use in devices, articles, and parts that transmit and receive electromagnetic waves, due to its electromagnetic wave-transmitting properties. Examples include vehicle structural parts, vehicle-mounted accessories, electronic equipment housings, home appliance housings, structural parts, machine parts, various automobile parts, electronic equipment parts, furniture, kitchenware and other household goods, medical equipment, building material parts, and other structural and exterior parts.

[0068] More specifically, vehicle-related components include the instrument panel, console box, door handles, door trim, shift lever, pedals, glove box, bumper, hood, fenders, trunk, doors, roof, pillars, seats, steering wheel, ECU box, electrical components, engine components, drivetrain and gear components, intake and exhaust system components, and cooling system components.

[0069] More specifically, electronic devices and home appliances include home appliances such as refrigerators, washing machines, vacuum cleaners, microwave ovens, air conditioners, lighting fixtures, electric water heaters, televisions, clocks, ventilation fans, projectors, and speakers, as well as electronic information devices such as personal computers, mobile phones, smartphones, digital cameras, tablet PCs, portable music players, portable game consoles, chargers, and batteries. [Examples]

[0070] The present invention will be described in more detail below with reference to examples and comparative examples. Various samples related to the electromagnetic wave-transmitting metallic luster member 1 were prepared. Electromagnetic wave permeability was evaluated by measuring the amount of radio wave attenuation before and after the humidification and heating test. Furthermore, durability against humidified heating was evaluated by measuring various indicators of luster (appearance) (Y value (SCI), ΔE value) before and after the humidified heating test. Furthermore, stretch resistance was evaluated by measuring the Y-value (SCI, SCE) of glossiness (appearance) before and after the tensile test.

[0071] <Humidification and heating test> In each example and comparative example, a LuciaX CS9861UAS (adhesive layer) manufactured by Nitto Denko was formed on the metal layer of the electromagnetic wave-transmitting metallic luster member, and a slide glass (glass) manufactured by Matsunami Glass Industry Co., Ltd. was attached thereon to obtain a glass-attached sample. A humidification and heating test was performed on the glass-attached sample by leaving it in an environment of 65°C and 90%RH for 120 hours. The following evaluations of radio wave transmittance and luster were performed on the glass-attached sample before the humidification and heating test and on the glass-attached sample after the humidification and heating test, respectively.

[0072] [Electromagnetic wave transparency] The radio wave transmission attenuation at 28 GHz was measured from the substrate side using a free-space evaluation jig (KEYCOM) LAF-26.5A, antenna WR-28, and Agilent's spectrum analyzer (CXA signal analyzer NA9000A). Since there is a correlation between electromagnetic wave transmission in the millimeter-wave radar frequency band (76-80 GHz) and electromagnetic wave transmission in the microwave band (28 GHz), showing relatively close values, this evaluation used electromagnetic wave transmission in the microwave band (28 GHz), i.e., microwave field transmission attenuation, as the indicator, and judged according to the following criteria. The measured results are shown in Table 2.

[0073] (Radio wave transmission attenuation) 0.1[-dB] or less:◎ More than 0.1[-dB] and less than 0.3[-dB]:〇 More than 0.3[-dB] and less than 1[-dB]:△ Over 1[-dB]: ×

[0074] [Luminousness (Appearance)] The Y-value (SCI) and ΔE-value were measured using a Konica Minolta Japan CM-2600d spectrophotometer according to geometric condition c of JIS Z 8722. For each glass-attached sample, the results of measuring each index from the glass surface side with the above spectrophotometer are shown in Table 1, and the results of measuring each index from the substrate side with the above spectrophotometer are shown in Table 2. Here, as quantitative representations of appearance, the Y value (SCI) was used to quantitatively represent metallic luster, and the ΔE value was used to represent color tone changes. The Y value (SCI) and ΔE value were evaluated according to the following criteria.

[0075] (Y value (SCI) after humidification and heating test) 50% or more: ○ 40% or more, less than 50%: △ Less than 40%: ×

[0076] (ΔE values ​​before and after humidification and heating test) 3 or less: ○ Over 3: ×

[0077] <Tensile Test> The electromagnetic wave-transmitting metallic luster members of each example and comparative example were stretched using a MinebeaMitsumi TG-10kN tensile testing machine at 150°C under conditions of a stretching speed of 5 mm / min and an elongation of 20% by uniaxial tensile testing. The elongation is expressed by the following formula. Growth rate (%) = 100 × (L - Lo) / Lo Note that Lo is the sample length before stretching, and L is the sample length after stretching.

[0078] [Luminousness (Appearance)] In the electromagnetic wave-transmitting metallic luster members of each example and comparative example after tensile testing, the Y values ​​(SCI, SCE) were measured using a Konica Minolta Japan CM-2600d spectrophotometer in accordance with geometric condition c of JIS Z 8722. Table 1 shows the results of measuring each index from the metal layer side using the spectrophotometer described above, and Table 2 shows the results of measuring each index from the substrate side using the spectrophotometer described above. For control, the electromagnetic wave-transmitting metallic luster members of each example and comparative example, which were not subjected to tensile testing, were also measured in the same manner. The Y-values ​​(SCI, SCE) were evaluated according to the following criteria.

[0079] (Y value (SCI) after tensile test) 50% or more: ○ 40% or more, less than 50%: △ Less than 40%: ×

[0080] <Y value (SCE) after tensile test> 0.1 or less: ◎ More than 0.1, less than 0.3:〇 More than 0.3, less than 1: △ Over 1: ×

[0081] [Thickness of the metal layer] The thickness of the metal layer was measured by FE-TEM observation using a JEOL FE-TEM, JEM-2800. Considering the variations in the metal layer, and more specifically the variations in the thickness of section 12a shown in Figure 1, the average thickness of section 12a was used as the thickness of the metal layer. The thickness of each section 12a was defined as the thickness at the thickest point perpendicular to the substrate 10. Hereafter, this average value will be referred to as the "maximum thickness" for convenience. In determining the maximum thickness, first, a square region 3 with sides of 5 cm, as shown in Figure 3, was appropriately extracted from the metal layer exposed on the surface of the electromagnetic wave-transparent laminated member. Then, five points "a" to "e" were selected as measurement points by dividing the centerlines A and B of the vertical and horizontal sides of the square region 3 into four equal parts. Next, for each selected measurement location, a field of view region containing approximately five portions 12a was extracted from the cross-sectional image. The individual thicknesses of the five portions 12a at each of these five measurement locations, i.e., 25 portions 12a (5 portions × 5 locations), were determined, and their average value was defined as the "maximum thickness".

[0082] [Content of aluminum and indium elements] The aluminum and indium content in the metal layer was measured by X-ray fluorescence analysis. A Rigaku ZSX Primus III+ analyzer was used. The measured fluorescence intensity was converted to the sample thickness using a calibration curve obtained from measurements of indium and aluminum films of known thickness as reference samples. From the resulting sample thickness, the aluminum density was calculated to be 2.70 g / cm³. 3 Indium density 7.31 g / cm³ 3 Using this method, we performed mass conversion and calculated the content of aluminum and indium elements in the metal layer.

[0083] (Example 1) A readily moldable PET film manufactured by Mitsubishi Chemical Corporation (product number: G931E75, thickness: 50 μm) was used as the base film. First, an In-Sn alloy layer was formed on the base film as the first layer by DC pulse sputtering (150 kHz) using an In-Sn alloy target (Sn ratio 5 mass%):ITM. The sputtering was carried out in an atmosphere without oxygen supply. The resulting first layer had a discontinuous structure. Next, an aluminum (Al)-containing layer was formed as a second layer on top of the first layer by AC sputtering (AC: 40 kHz) using an Al target. Thus, an electromagnetic wave-transmitting metallic gloss member of Example 1 was obtained, in which the above-mentioned metal layer was formed on the substrate film. Tables 1 and 2 show the results of various evaluations performed on the electromagnetic wave-transmitting metallic luster member obtained in Example 1. Elemental analysis was also performed using a JEOL FE-TEM JEM-2800 to measure the distribution of Al and In elements.

[0084] The metal layer obtained in Example 1 was confirmed to have a discontinuous structure. It was also confirmed that the aluminum element was unevenly distributed within the metal layer, surrounding the indium element. Furthermore, the distribution regions of the aluminum and indium elements overlapped in the range of 14 nm or less from the surface of the metal layer. In other words, it was found that the aluminum and indium elements were not miscible (not alloyed) with each other in the range of 14 nm or more from the surface of the metal layer.

[0085] (Examples 2-10) Except for changing the content of aluminum and indium elements in the metal layer to match those shown in Tables 1 and 2, electromagnetic wave-transmitting metallic gloss members of Examples 2 to 10 were fabricated and evaluated in the same manner as in Example 1. For Examples 7 to 10, evaluation was performed only from the substrate side. Furthermore, it was confirmed that the metal layers in Examples 2 to 10 had a discontinuous structure. Figure 2 shows an electron microscope image (SEM image) of the surface of the electromagnetic wave-transmitting metallic luster member in Example 2. Furthermore, it was confirmed that in Examples 2 to 10, the aluminum element was unevenly distributed within the metal layer, surrounding the indium element. The results of the elemental analysis for Example 2 are shown in Figure 4. In Examples 2 to 10, the distribution regions of aluminum and indium elements overlapped in the range of 14 nm or less from the surface of the metal layer (shown in Figure 4(d) for Example 2 only).

[0086] (Comparative Example 1) A comparative example of an electromagnetic wave-transmitting metallic luster member was fabricated and evaluated in the same manner as in Example 1, except that the content of aluminum and indium elements in the metal layer was changed to match those shown in Tables 1 and 2.

[0087] (Comparative Example 2) A radio-transparent metallic luster member of Comparative Example 2 was fabricated and evaluated in the same manner as in Example 1, except that the first layer was made of an In-Sn alloy and a metal layer was formed without a second layer.

[0088] (Comparative Example 3) A magnetically transparent metallic luster member of Comparative Example 3 was fabricated and evaluated in the same manner as in Example 1, except that the content of aluminum and indium elements in the metal layer was changed to match those shown in Tables 1 and 2.

[0089] (Comparative Example 4) An electromagnetic wave-transmitting metallic luster member of Comparative Example 4 was fabricated and evaluated in the same manner as in Example 1, except that the In-Sn alloy target (Sn ratio 5 mass%) was changed to In, and the content of aluminum and indium elements in the metal layer was changed to match Tables 1 and 2.

[0090] The results are shown in Tables 1 and 2. Note that "-" in Tables 1 and 2 indicates that measurement was not performed.

[0091] [Table 1]

[0092] [Table 2]

[0093] As shown in Tables 1 and 2, the electromagnetic wave-transmitting metallic luster members of Examples 1 to 10 showed good results in both electromagnetic wave transmittance and appearance even after humidification and heating tests and tensile tests. On the other hand, in Comparative Example 1, the indium element content in the metal layer was low at 25% by mass, resulting in a high ΔE value and inferior luster (appearance). Furthermore, because Comparative Example 2 did not contain the element Al, the Y value (SCI) in the humidified heating test was low, and the ΔE value was also high, resulting in inferior luster (appearance). Furthermore, in Comparative Example 3, the lack of order in the island-like shape and the presence of defects resulted in a high ΔE value and inferior luster (appearance). Furthermore, in Comparative Example 4, the high content of In element and the poor orderliness of the island-like shape resulted in defects, leading to a low Y value (SCI) and a high ΔE value in the humidified heating test, resulting in inferior luster (appearance).

[0094] The present invention is not limited to the embodiments described above, and can be modified and implemented as appropriate without departing from the spirit of the invention.

[0095] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to these examples. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention. Furthermore, the components of the above embodiments may be combined in any way without departing from the spirit of the invention.

[0096] This application is based on Japanese Patent Application No. 2021-055601 filed on March 29, 2021, and its contents are incorporated herein by reference. [Industrial applicability]

[0097] The electromagnetic wave-transmitting metallic glossy member according to the present invention can be used in devices, articles, and parts that transmit and receive electromagnetic waves. For example, it can be used in a variety of applications where both aesthetic appeal and electromagnetic wave transparency are required, such as vehicle structural parts, vehicle-mounted accessories, housings for electronic equipment, housings for home appliances, structural parts, machine parts, various automotive parts, electronic equipment parts, furniture, kitchenware and other household goods, medical equipment, building material parts, and other structural and exterior parts. [Explanation of Symbols]

[0098] 1. Electromagnetic wave transparent metallic luster member 10 Base 12 metal layer 12a part 12b Gap

Claims

1. It comprises a substrate and a metal layer formed on the substrate, The metal layer includes a plurality of portions that are discontinuous from each other in at least part of the way. The aforementioned metal layer contains aluminum and indium. The content of the indium element in the metal layer is more than 90% by mass and 98% by mass or less. The aluminum element is unevenly distributed in the metal layer, surrounding the indium element. Electromagnetic wave-transmitting metallic luster component.

2. The electromagnetic wave-transmitting metallic luster member according to claim 1, wherein the metal layer contains at least one element of Sn, Si, Ga, Ge, and Pb.

3. The electromagnetic wave-transmitting metallic luster member according to claim 1 or 2, wherein the thickness of the metal layer is 10 nm to 100 nm.

4. An electromagnetic wave-transmitting metallic luster member according to any one of claims 1 to 3, wherein the Y value (SCI) measured using a spectrophotometer in accordance with geometric condition c of JIS Z 8722 after a humidified heating test at 65°C and 90% RH is 40% or more.

5. The electromagnetic wave-transmitting metallic luster member according to any one of claims 1 to 4, wherein the plurality of parts are formed in an island-like manner.

6. The electromagnetic wave-transmitting metallic luster member according to any one of claims 1 to 5, wherein the substrate is a base film, a resin molded product base, or an article to be given a metallic luster.

7. A first step involves forming a layer on a substrate which contains at least an indium element and which comprises multiple portions that are discontinuous with each other in at least part of their respective states. The process includes a second step of depositing a metal containing aluminum onto the layer formed in the first step, A method for manufacturing an electromagnetic wave-transmitting metallic luster member according to any one of claims 1 to 6.

8. The method according to claim 7, wherein in the first step, the layer is formed by sputtering in a substantially oxygen-free atmosphere.

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