Electromagnetic wave-transmitting metallic glossy member and its manufacturing method

Abstract

The present invention relates to an electromagnetic wave-transmitting metallic lustrous member which comprises a base material and a metal layer that is formed on the base material, wherein: the metal layer comprises a plurality of portions that are at least partially discontinuous with each other; the metal layer comprises portions that contain elemental aluminum and portions that contain elemental indium; the portions that contain elemental indium are unevenly distributed in the metal layer; and the volume fraction (% by volume) of the portions that contain elemental indium in the metal layer is from 5 to 40% by volume.

Description

[Technical field]

[0001] The present invention relates to an electromagnetic wave transparent lustrous metallic member and a method for producing the same. [Background technology]

[0002] 2. Description of the Related Art Conventionally, members having electromagnetic wave transparency and metallic luster have been suitably used in devices that transmit and receive electromagnetic waves because they combine the luxurious appearance resulting from their metallic luster with electromagnetic wave transparency.

[0003] When metal is used in a metallic luster-like component, transmission and reception of electromagnetic waves is substantially impossible or is hindered. Therefore, in order to avoid impeding the transmission and reception of electromagnetic waves and impairing the design, an electromagnetic wave-transmitting metallic luster component that combines both metallic luster and electromagnetic wave transmittance is required.

[0004] Such electromagnetic wave-transmitting lustrous metallic members are expected to be applied as devices for transmitting and receiving electromagnetic waves to various devices requiring communication, such as door handles of automobiles equipped with smart keys, in-vehicle communication devices, mobile phones, personal computers, and other electronic devices, etc. Furthermore, in recent years, with the development of IoT technology, applications are expected in a wide range of fields, such as home appliances such as refrigerators and lifestyle devices, which did not previously involve communication.

[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, the metal layer including a plurality of portions that are at least partially discontinuous from each other. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-69462 Summary of the Invention [Problem to be solved by the invention]

[0007] In such electromagnetic wave-transmitting metallic glossy members, when bending and stretching to produce a 3D molded product, cracks occur in areas where the elongation rate is high, causing clouding and discoloration. This is because when a metal layer is formed via an underlayer such as an indium oxide-containing layer, cracks occur due to the underlayer. When cracks occur and clouding and discoloration occur, the metallic gloss is impaired, making it impossible to achieve both good electromagnetic wave transmission and brilliance.

[0008] The present invention has been made to solve the above problems, and aims to provide an electromagnetic wave-transmitting metallic glossy member that has excellent electromagnetic wave transmittance and brilliance, and is suppressed from cracks caused by stretching and from clouding or discoloration resulting therefrom. [Means for solving the problem]

[0009] As a result of extensive research into solving the above-mentioned problems, the inventors have found that the above-mentioned problems can be solved by providing a metal layer on a substrate discontinuously, the metal layer including a portion containing elemental aluminum and a portion containing elemental indium, wherein the portion containing elemental indium is unevenly distributed within the metal layer and the volume fraction of the portion containing elemental indium is within a specific range, and have thus completed the present invention.

[0010] That is, the present invention is as follows. [1] A substrate and a metal layer formed on the substrate, the metal layer includes a plurality of portions that are at least partially discontinuous with each other; the metal layer includes a portion containing an aluminum element and a portion containing an indium element, the portion containing the indium element is unevenly distributed in the metal layer, the volume fraction (volume %) of the portion containing the indium element in the metal layer is 5 to 40 volume %; Electromagnetic wave-transmitting metallic glossy material. [2] The electromagnetic wave transmissive lustrous metallic member according to [1] above, wherein the portion containing the indium element is unevenly distributed on the opposite side of the substrate within the metal layer. [3] The electromagnetic wave transmissive lustrous metallic member according to the above [1] or [2], wherein the metal layer has a thickness of 10 nm to 200 nm. [4] The electromagnetic wave transparent lustrous metallic member according to any one of the above [1] to [3], wherein the plurality of portions are formed in an island shape. [5] The electromagnetic wave transparent metallic luster member according to any one of the above [1] to [4], wherein the substrate is any one of a base film, a resin molding base material, and an article to be imparted with metallic luster. [6] The electromagnetic wave transparent lustrous metallic member according to any one of the above [1] to [5], wherein the metal layer has a crack width of 150 nm or less when subjected to a tensile test at an elongation rate of 20%. [7] The electromagnetic wave transparent metallic luster member according to any one of the above [1] to [6], wherein the Y value (SCE) measured using a spectrophotometer in accordance with geometric condition c of JIS Z 8722 when a tensile test is performed at an elongation rate of 20% is 0.3 or less. [8] A first step of forming a layer on a substrate, the layer including at least an indium element and including a plurality of portions that are at least partially discontinuous with each other; A second step of depositing a metal containing an aluminum element on the layer formed in the first step. A method for producing an electromagnetic wave transparent lustrous metallic member according to any one of the above [1] to [7]. [9] The method according to [8] above, wherein in the first step, the layer is formed by sputtering in an atmosphere substantially free of oxygen. Effect of the Invention

[0011] According to the present invention, it is possible to provide an electromagnetic wave-transmitting lustrous metallic member that has excellent electromagnetic wave transmittance and brilliance, and is suppressed from cracking due to stretching and from causing cloudiness or discoloration due to the cracking. [Brief description of the drawings]

[0012] [Figure 1] Fig. 1(a) is a schematic cross-sectional view of an electromagnetic wave-transmitting lustrous metallic member 1 according to one embodiment of the present invention, and Fig. 1(b) is an electron microscope photograph (SEM image) of the surface of the electromagnetic wave-transmitting lustrous metallic member 1 according to one embodiment of the present invention. [Diagram 2] Fig. 2(a) shows an example of an electron microscope photograph (TEM image) of a cross section of an electromagnetic wave transparent lustrous metallic member 1 according to one embodiment of the present invention. Fig. 2(b) is a photographic drawing in which the metal layer in Fig. 2(a) is enlarged. [Diagram 3] FIG. 3 is a diagram for explaining a method for measuring the thickness of the metal layer of an electromagnetic wave permeable metallic luster member according to one embodiment of the present invention. [Figure 4] Fig. 4(a) is a photograph showing the distribution of In, Al, and O elements when elemental analysis was performed on the electromagnetic wave-transmitting metallic luster member of Example 1. Fig. 4(b) is a photograph showing the distribution of In, Al, and O elements when elemental analysis was performed on the electromagnetic wave-transmitting metallic luster member of Comparative Example 4. [Diagram 5] FIG. 5(a) shows an electron microscope photograph (SEM image) of the surface of the electromagnetic wave-transmitting metallic luster part of Example 1 before stretching, and FIG. 5(b) shows an electron microscope photograph (SEM image) of the surface of the electromagnetic wave-transmitting metallic luster part of Example 1 after stretching. [Figure 6] FIG. 6(a) shows an electron microscope photograph (SEM image) of the surface of the electromagnetic wave-transmitting metallic luster part of Comparative Example 4 before stretching, and FIG. 6(b) shows an electron microscope photograph (SEM image) of the surface of the electromagnetic wave-transmitting metallic luster part of Comparative Example 4 after stretching. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] An electromagnetic wave-transmitting metallic glossy member according to an embodiment of the present invention comprises a base and a metal layer formed on the base, the metal layer including a plurality of portions that are at least partially discontinuous from one another, the metal layer including a portion containing elemental aluminum and a portion containing elemental indium, the portion containing elemental indium being unevenly distributed within the metal layer, and the volume fraction (volume %) of the portion containing elemental indium in the metal layer being 5 to 40 volume %.

[0014] The present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited to the following embodiments and can be modified as desired without departing from the gist of the present invention. In addition, the symbol "to" indicating a numerical range is used to mean that the numerical values ​​before and after it are included as the lower and upper limits.

[0015] <1.Basic configuration> An electromagnetic wave transparent lustrous metallic member according to an embodiment of the present invention comprises a substrate and a metal layer formed on the substrate, the metal layer including a plurality of portions that are at least partially discontinuous from one another.

[0016] Fig. 1(a) shows a schematic cross-sectional view of an electromagnetic wave-transmitting lustrous metallic member 1 according to one embodiment of the present invention, and Fig. 1(b) shows an example of an electron microscope photograph (SEM image) of the surface of the electromagnetic wave-transmitting lustrous metallic member 1 according to one embodiment of the present invention. The image size in the electron microscope photograph is 6.25 μm × 4.65 μm.

[0017] As shown in FIG. 1( a ), the electromagnetic wave transparent lustrous metallic member 1 includes a substrate 10 and a metal layer 12 formed on the substrate 10 . In the electromagnetic wave transparent metallic luster 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, it is possible to suppress the occurrence of cracks due to breakage of the underlayer caused by stretching. Note that a layer (such as a protective layer) that is unlikely to cause cracks may be provided between the substrate 10 and the metal layer 12. Details will be described in <4. Other layers> below.

[0018] The metal layer 12 includes a plurality of portions 12a. These portions 12a are at least partially discontinuous from one another, in other words, at least partially separated by gaps 12b. Being separated by the gaps 12b, the sheet resistance of these portions 12a is increased and the interaction with radio waves is reduced, allowing radio waves to pass through. Each of these portions 12a is an aggregate of sputtered particles formed by vapor deposition of metal. When the 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.

[0019] In this specification, the term "discontinuous state" means that the gaps 12b separate the layers from each other, and as a result, the layers are electrically insulated from each other. The electrical insulation increases the sheet resistance, and the desired electromagnetic wave transmittance is obtained. The form of the discontinuity is not particularly limited, and examples thereof include an island shape, a crack structure, and the like.

[0020] Fig. 1(b) is an electron microscope photograph (SEM image) of the surface of the metal layer of the electromagnetic wave permeable lustrous metallic member 1. "Island-like" means a structure in which particles, which are an aggregate of sputtered particles, are independent of each other and are spread out slightly spaced apart or partially in contact with each other, as shown in Fig. 1(b).

[0021] The crack structure is a structure in which the metal thin film is divided by cracks, and is to be distinguished from the above-mentioned cracks that occur during stretching.

[0022] The cracked metal layer 12 can be formed, for example, by providing a metal thin film layer on a substrate and bending and stretching the metal thin film layer to generate cracks. In this case, by providing a brittle layer made of a material that has poor elasticity, i.e., that is likely to generate cracks by stretching, between the substrate and the metal thin film layer, the cracked metal layer 12 can be easily formed.

[0023] As described above, the form in which the metal layer 12 is discontinuous is not particularly limited, but from the viewpoint of productivity, it is preferable that the metal layer 12 be discontinuous in an "island-like" form.

[0024] The electromagnetic wave transmission of the electromagnetic wave-transmitting metallic luster member 1 can be evaluated, for example, by the amount of radio wave transmission attenuation. The amount of radio wave transmission attenuation can be measured, for example, by the method described later in the Examples.

[0025] Specifically, the radio wave transmission attenuation at 28 GHz can be evaluated using a KEC method measurement and evaluation tool and an Agilent CXA signal analyzer NA9000A spectrum analyzer. Since there is a correlation between the electromagnetic wave transmission in the millimeter wave radar frequency band (76-80 GHz) and the electromagnetic wave transmission in the microwave band (28 GHz) and they show relatively close values, the electromagnetic wave transmission in the microwave band (28 GHz), i.e., the microwave electric field transmission attenuation, is used as the index.

[0026] 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 making the radio wave transmission attenuation in the microwave band (28 GHz) 1 [-dB] or less, the problem of 20% or more of the radio waves being blocked can be avoided.

[0027] The brilliance (appearance) of the electromagnetic wave transmitting metallic luster member 1 is, for example, Y value (SCI), Y value (SCE), and b *It can be evaluated by measuring the Y value (SCI), Y value (SCE), and b * The value can be measured using a spectrophotometer in accordance with the geometric condition c of JIS Z 8722.

[0028] When evaluating the luster (appearance) after stretching, for example, a tensile test is carried out using a tensile tester at 150° C., a stretching speed of 5 mm / min, and an elongation rate of 20%, and then the evaluation is performed.

[0029] The larger the Y value (SCI) after the tensile test, the more the reduction in brilliance due to stretching can be suppressed. The Y value (SCI) after the tensile test is preferably 40 or more, more preferably 50 or more, and even more preferably 55 or more. When the Y value (SCI) is 40 or more, the brilliance is good and the appearance is excellent.

[0030] Furthermore, the smaller the Y value (SCE) after the tensile test, the more the clouding caused by stretching can be 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. When the Y value (SCE) is 1 or less, clouding in appearance is suppressed, resulting in an excellent appearance.

[0031] b * The value indicates the intensity of the color from blue to yellow. * If the value is less than -4, the color will be bluish, which is not desirable. * A value of 4 or more is undesirable because the color becomes yellowish.

[0032] In addition, after the tensile test, * The value is preferably less than 4, more preferably less than 3, and even more preferably less than 2. b after tensile test * When the value is less than 4, the occurrence of yellowing due to stretching can be suppressed, and the film has a natural color (silver) and is excellent in appearance. * The value is preferably -1 or more. *When the value is −1 or more, the generation of a bluish color due to stretching can be suppressed, and the film exhibits a natural color (silver) and has an excellent appearance.

[0033] The stretchability of the electromagnetic wave transparent metallic luster member 1 can 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 for the above-mentioned luster (appearance). The smaller the crack width of the metal layer after the tensile test, the more the occurrence of cracks due to stretching can be suppressed, and the better the 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.

[0034] <2.Base> From the viewpoint of electromagnetic wave transparency, examples of the substrate 10 include a base film, a resin molded base material, and an article to be imparted with metallic luster.

[0035] More specifically, examples of the substrate film that can be used include transparent films made of homopolymers or copolymers such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate, polyamide, polyvinyl chloride, polycarbonate (PC), cycloolefin polymer (COP), polystyrene, polypropylene (PP), polyethylene, polycycloolefin, polyurethane, acrylic (PMMA), and ABS.

[0036] These materials do not affect the brilliance or electromagnetic wave transmittance. However, from the viewpoint of forming the metal layer 12 later, it is preferable that the material is able to withstand high temperatures such as those used in deposition. Therefore, among the above materials, for example, polyethylene terephthalate, polyethylene naphthalate, acrylic, polycarbonate, cycloolefin polymer, ABS, polypropylene, and polyurethane are preferable. Among these, polyethylene terephthalate, cycloolefin polymer, polycarbonate, and acrylic are preferable because they have a good balance between heat resistance and cost.

[0037] The base film may be a single layer film or a laminated film. From the viewpoint of ease of processing, the thickness is preferably, for example, about 6 μm to 250 μm. In order to strengthen the adhesive force with the metal layer 12, the base film may be subjected to a plasma treatment or an easy-adhesion treatment. In addition, it is preferable that the base film does not contain particles.

[0038] It should be noted that the base film is merely one example of an object (substrate 10) on whose surface the metal layer 12 can be formed. The substrate 10 includes not only the base film as described above, but also resin molded substrates and articles themselves to which a metallic luster should be imparted. Examples of resin molded substrates and articles to which a metallic luster should be imparted include structural parts for vehicles, vehicle-mounted items, housings for electronic devices, housings for home appliances, structural parts, machine parts, various automobile parts, electronic device parts, household goods such as furniture and kitchenware, medical equipment, building material parts, other structural parts and exterior parts, etc.

[0039] <3.Metal layer> The metal layer 12 is formed on the substrate 10. As described above, the metal layer 12 may be provided directly on the surface of the substrate 10, or may be provided indirectly via a layer that is unlikely to cause cracks due to stretching, such as a protective layer, provided on the surface of the substrate 10. The metal layer 12 is a layer that has a metallic appearance and is preferably a layer that has a metallic luster.

[0040] The metal layer 12 includes a portion containing an aluminum element and a portion containing an indium element. The portion containing an aluminum element usually occupies a major region of the metal layer 12, as shown by the white arrows in Figs. 2(a) and (b). In addition, the portion containing an aluminum element and the portion containing an indium element are each included at least once in the same metal layer. That is, referring to Fig. 1(a), at least one portion 12a includes both a portion containing an aluminum element and a portion containing an indium element. Note that the embodiment of the present invention does not include a mode in which the portion containing an aluminum element and the portion containing an indium element are present in different metal layers, such as when the portion 12a is formed by laminating a metal layer containing an aluminum element and a metal layer containing an indium element, and both the portion containing an aluminum element and the portion containing an indium element are not included in the same metal layer.

[0041] The volume fraction (volume %) of the portion containing aluminum element in the metal layer 12 is preferably 60 volume % or more, more preferably 75 volume % or more, and even more preferably 90 volume % or more. When the volume fraction of the portion containing aluminum element in the metal layer 12 is 60 volume % or more, sufficient brilliance can be achieved and a natural color can be presented.

[0042] The aluminum element-containing portion preferably contains, in addition to aluminum, a material that can exhibit sufficient brilliance and has a relatively low melting point. This is because the aluminum element-containing portion is preferably formed by thin film growth through vapor deposition. For this reason, the aluminum element-containing portion is preferably a metal with a melting point of about 1000°C or less, and may contain, for example, at least one metal selected from zinc (Zn), lead (Pb), copper (Cu), and silver (Ag), or an alloy containing the metal as a main component.

[0043] There is no particular limitation on how the aluminum element-containing portion is contained in the metal layer, but it is preferable that at least a part of the aluminum element-containing portion is in contact with the substrate (or with the other layer, if another layer is provided on the substrate). In other words, it is preferable that the aluminum element-containing portion is present on the substrate side. This allows the high brilliance to be maintained even in the appearance observed through the substrate.

[0044] In the metal layer 12, the portion containing the indium element is unevenly distributed. As shown by the black arrows in Figs. 2(a) and (b), the portion containing the indium element is not uniformly distributed in the metal layer 12, but is unevenly distributed at some point in the metal layer 12. If the portion containing the indium element is unevenly distributed in the metal layer 12, it may be unevenly distributed in the metal layer 12 so as to be surrounded by the portion containing the aluminum element, or may be unevenly distributed near the upper part of the portion containing the aluminum element, that is, on the opposite side to the substrate (the surface side of the metal layer 12) as shown in Figs. 2(a) and (b), and is not particularly limited. In particular, it is preferable that the portion containing the indium element is unevenly distributed on the opposite side to the substrate. This allows the high brilliance to be maintained even in the appearance observed through the substrate.

[0045] To obtain the metal layer 12 having such unevenly distributed portions containing elemental indium, a layer containing elemental indium and including a plurality of portions that are at least partially discontinuous with each other is first formed on the substrate 10, as described in <5. Manufacturing method for electromagnetic wave-transmitting lustrous metallic member> below. Next, a metal target material containing elemental aluminum is vapor-deposited on the formed discontinuous layer. This results in the metal layer 12 having unevenly distributed portions containing elemental indium. The reason why such a metal layer 12 is obtained is not clear, but is presumed to be as follows.

[0046] That is, after forming a discontinuous layer on the substrate 10, when a metal target material containing aluminum element is vapor-deposited (sputtering film formation, etc.) on the discontinuous layer, metal such as aluminum element grows continuously on the discontinuous layer while maintaining the discontinuous shape, and an aluminum-containing layer is formed on the discontinuous layer. When the thickness and energy of the aluminum-containing layer gradually increase due to such vapor deposition (sputtering film formation, etc.), low melting point indium, etc. contained in the discontinuous layer melts. Since the wettability between the metals contained in the discontinuous layer and the aluminum-containing layer is poor, and the surface energy of the indium, etc. contained in the discontinuous layer is low, the indium, etc. contained in the discontinuous layer transfers to the aluminum-containing layer or its surface. As a result, indium, etc. is taken into the aluminum-containing layer, and a part containing aluminum element and a part containing indium element are present in the same metal layer, and it is presumed that a metal layer 12 in which the part containing indium element is unevenly distributed is formed directly on the substrate.

[0047] The volume fraction (volume %) of the portion containing elemental indium in the metal layer 12 is 5 to 40 volume %. When it is 5 volume % or more, clouding after stretching can be suppressed. Also, when it is 40 volume % or less, high brilliance and natural color can be presented.

[0048] The volume fraction (volume %) of the portion containing elemental indium in the metal layer 12 is 5 volume % or more, preferably 10 volume % or more, and 40 volume % or less, preferably 25 volume % or less.

[0049] The volume fraction of the portion containing elemental indium in the metal layer 12 can be measured, for example, by the method described later in the Examples.

[0050] The indium element may be contained as simple indium or as an indium alloy, and is not particularly limited, and examples thereof include In-Sn, In-Cr, and In-Zn.

[0051] In addition to the portion containing elemental aluminum and the portion containing elemental indium, metal layer 12 may also contain a portion containing, for example, silver (Ag), chromium (Cr), or the like.

[0052] The thickness of the metal layer 12 is usually 7 nm or more, preferably 10 nm or more, from the viewpoint of exerting sufficient metallic luster, while usually 200 nm or less is preferable from the viewpoint of sheet resistance and electromagnetic wave transmittance. For example, 7 nm to 100 nm is more preferable, and 10 nm to 70 nm is even more preferable. This thickness is suitable for forming a uniform film with good productivity, and also provides a good appearance to the final product, that is, a resin molded article. The thickness of the metal layer 12 can be measured, for example, by the method described later in the Examples.

[0053] Metal layer 12 is formed on substrate 10 and includes a plurality of portions that are at least partially discontinuous from one another. If metal layer 12 is continuous on substrate 10, sufficient metallic luster is obtained, but radio wave transmission attenuation becomes very large, and therefore electromagnetic wave transparency cannot be ensured.

[0054] In order to form the metal layer 12 discontinuously on the substrate 10, it is preferable to lower the oxygen concentration in the metal layer 12. When sputtered particles formed by vapor deposition of metal form a thin film on the substrate, the surface diffusivity of the particles on the substrate affects the shape of the thin film, and it is believed that a discontinuous structure is more likely to be formed when the substrate temperature is high, the wettability of the metal layer to the substrate is low, and the melting point of the material of the metal layer is low. It is believed that the surface diffusivity of the metal particles on the substrate surface is promoted by using a sputtering material that is substantially oxygen-free on the substrate, or by performing vapor deposition in an atmosphere that is substantially oxygen-free, so that the metal layer can be formed in a discontinuous state.

[0055] The equivalent circle diameter of the portions 12a of the metal layer 12 is not particularly limited, but is usually about 10 to 1000 nm. The average particle diameter of the portions 12a means the average value of the equivalent circle diameters of the portions 12a.

[0056] The circle equivalent diameter of the portion 12a refers to the diameter of a perfect circle equivalent to the area of ​​the portion 12a.

[0057] The distance between the portions 12a is not particularly limited, but is usually about 10 to 1000 nm.

[0058] <4. Other layers> Furthermore, the electromagnetic wave transparent metallic luster member 1 according to the embodiment of the present invention may include other layers depending on the application, in addition to the above-mentioned metal layer 12. However, when two or more continuous layers are formed on the substrate 10, the continuous layers are likely to break (crack) due to stretching. Therefore, when another layer is provided between the substrate 10 and the metal layer 12, it is preferable that the other layer is one that is unlikely to cause cracks.

[0059] Examples of other layers include an optical adjustment layer (color adjustment layer) made of a highly refractive material or the like for adjusting the appearance such as color, a protective layer (scratch-resistant layer) for improving durability such as scratch resistance, a barrier layer (corrosion-resistant layer), an easy-adhesion layer, a hard coat layer, an anti-reflection layer, a light extraction layer, and an anti-glare layer.

[0060] <5. Manufacturing method of electromagnetic wave-transmitting metallic gloss member> The manufacturing method of the electromagnetic wave transmitting lustrous metallic member according to the present embodiment is characterized by including a first step of forming a layer (hereinafter simply referred to as a discontinuous layer or a first layer) on a substrate, the layer including at least an indium element and including a plurality of portions that are at least partially discontinuous with each other, and a second step of depositing a metal including an aluminum element on the discontinuous layer. Each step will be described in detail below.

[0061] (1) First step In this step, a layer is formed on the substrate 10, which contains at least elemental indium and includes a plurality of portions that are at least partially discontinuous from one another.

[0062] The discontinuous layer can be formed, for example, by depositing a metal containing indium on 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 can form a uniform, thin, discontinuous layer.

[0063] In particular, it is preferable to form the discontinuous layer by sputtering using a metal target material that contains indium element and is substantially free of oxygen (1 volume % or less). It is more preferable that the metal target material does not contain any oxygen. By not containing oxygen, the wettability of such a metal target material with the substrate can be reduced, and the formation of the discontinuous layer on the substrate 10 is promoted. For the same reason, when forming the discontinuous layer, it is preferable to perform deposition in an atmosphere that is substantially free of oxygen (100 volume ppm or less), and it is more preferable to perform deposition in an atmosphere that is completely free of oxygen.

[0064] The indium element contained in the metal target material may be indium alone or in the form of an indium alloy, and is not particularly limited, and examples thereof include In-Sn, In-Cr, and In-Zn. The metal target material may contain silver (Ag), chromium (Cr) and the like in addition to the metal containing the indium element.

[0065] Sputtering is carried out under vacuum. Specifically, the atmospheric pressure during sputtering is, for example, 1 Pa or less, preferably 0.7 Pa or less, from the viewpoints of suppressing a decrease in the sputtering rate and stabilizing discharge.

[0066] The power source used in the sputtering method may be, for example, any of a DC power source, an AC power source, an MF power source, and an RF power source, or a combination of these.

[0067] In order to form a discontinuous layer of a desired thickness, sputtering may be carried out multiple times by appropriately setting the metal target material, sputtering conditions, and the like.

[0068] (2)Second process Next, a metal containing aluminum element is vapor-deposited on the formed discontinuous layer. As the vapor deposition method, the same method as in the first step can be adopted.

[0069] The metal target material to be used is a metal containing aluminum element. The aluminum element may be contained in the metal target material as simple aluminum, an aluminum compound, or an aluminum alloy.

[0070] The metal target material may contain zinc (Zn), lead (Pb), copper (Cu), silver (Ag) and the like in addition to the metal containing the aluminum element.

[0071] According to the manufacturing method of this embodiment, a discontinuous metal layer containing an aluminum element and an indium element can be formed on a substrate. As described above, this is presumably because, when the aluminum-containing layer is continuously grown on the discontinuous layer, the indium element and the like contained in the discontinuous layer are transferred into the aluminum-containing layer or its surface, resulting in the presence of an aluminum element and an indium element in the same metal layer.

[0072] <6. Uses of electromagnetic wave-transmitting metallic glossy parts> Since the electromagnetic wave-transmitting metallic luster member of the present embodiment has electromagnetic wave transmittance, it is preferable to use it in devices and articles that transmit and receive electromagnetic waves, and parts thereof, etc. Examples of such products include structural parts for vehicles, vehicle-mounted items, housings for electronic devices, housings for home appliances, structural parts, machine parts, various automobile parts, parts for electronic devices, household goods such as furniture and kitchenware, medical equipment, parts for building materials, other structural parts and exterior parts, etc.

[0073] More specifically, vehicle-related parts include instrument panels, console boxes, door handles, door trim, shift levers, pedals, glove boxes, bumpers, bonnets, fenders, trunks, doors, roofs, pillars, seats, steering wheels, ECU boxes, electrical components, engine peripheral parts, drive system and gear peripheral parts, intake and exhaust system parts, cooling system parts, etc.

[0074] More specific examples of electronic devices and home appliances include home appliances such as refrigerators, washing machines, vacuum cleaners, microwave ovens, air conditioners, lighting equipment, 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

[0075] The present invention will be described more specifically below with reference to examples and comparative examples. Various samples of electromagnetic wave-transmitting metallic glossy material 1 were prepared, and the electromagnetic wave attenuation was measured as an evaluation of electromagnetic wave transmittance, and the Y value (SCI), Y value (SCE), and b * As an evaluation of stretchability, the crack width was measured before and after stretching.

[0076] The stretching of each sample was performed by uniaxial tensile testing at 150° C., a stretching speed of 5 mm / min, and an elongation rate of 20% using a tensile tester TG-10kN manufactured by MinebeaMitsumi Inc. The elongation rate is expressed by the following formula. Elongation percentage (%)=100×(L−Lo) / Lo (Lo: sample length before stretching, L: sample length after stretching).

[0077] [Electromagnetic wave transparency] (1) Radio wave transmission attenuation The radio wave transmission attenuation at 28GHz was evaluated using a KEC method measurement evaluation jig and an Agilent spectrum analyzer (CXA signal analyzer NA9000A). Since there is a correlation between the electromagnetic wave transmission in the millimeter wave radar frequency band (76-80GHz) and the electromagnetic wave transmission in the microwave band (28GHz) and they show relatively close values, this evaluation was made using the electromagnetic wave transmission in the microwave band (28GHz), i.e., the microwave electric field transmission attenuation, as an index and was judged according to the following criteria.

[0078] <Radio wave transmission attenuation after extension> 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]: ×

[0079] [Brilliance (appearance)] (2) Y value (SCI), Y value (SCE), b * Y value (SCI), Y value (SCE), b * The measurements were made using a spectrophotometer CM-2600d manufactured by Konica Minolta Japan Co., Ltd., in accordance with the geometric condition c of JIS Z 8722. Here, the quantitative expressions of appearance are Y value (SCI) for the quantitative expression of metallic luster, Y value (SCE) for the quantitative expression of opacity, and b value for the quantitative expression of hue. * Y value (SCI), Y value (SCE), b * was evaluated according to the following criteria.

[0080] <Y value after stretching (SCI)> 55 and above: ◎ 50 or older, under 55: Yes Over 40 and under 50: △ Under 40: ×

[0081] <Y value after stretching (SCE)> 0.1 or less: ◎ More than 0.1, less than 0.3:〇 More than 0.3, less than 1: △ Over 1: ×

[0082] <b before and after stretching * > Before stretching b * is greater than -4 and less than 4, and after stretching b * is -1 or more and less than 2: ◎ Before stretching b * is greater than -4 and less than 4, and after stretching b * is 2 or more but less than 3: Yes Before stretching b * is greater than -4 and less than 4, and after stretching b * is 3 or more and less than 4: △ Before stretching b * is -4 or less or 4 or more, or after stretching b * is less than -1 or 4 or more: ×

[0083] [Stretchability] (3) Crack width The crack width was measured using a Hitachi High-Technologies Corporation FE-SEM (SU-8000) and evaluated according to the following criteria. <Crack width after stretching> 150nm or less:◎ More than 150nm, less than 160nm:〇 More than 160nm, less than 170nm:△ Over 170nm:×

[0084] [comprehensive evaluation] If all evaluation results are ◎: ◎ If the lowest rating among all the evaluation results is 〇: 〇 If the lowest rating among all the evaluation results is △: △ If the lowest rating among all the evaluation results is ×: × An overall evaluation of △ or above is considered a pass.

[0085] (4)Metal layer measurement method Using the FE-TEM, JEM-2800 manufactured by JEOL Ltd., FE-TEM observation was carried out to measure the thickness of the metal layer. Also, EDX analysis (including mapping) was performed to measure and calculate the thickness of the entire metal layer and the volumes of aluminum and indium contained therein, and the volume fractions of the portions containing Al and the portions containing In were measured.

[0086] <Thickness of the metal layer> Considering the variation in the metal layer, more specifically, the variation in the thickness of the portion 12a shown in Fig. 1(a), the average value of the thickness of the portion 12a was taken as the thickness of the metal layer. Note that the thickness of each individual portion 12a was taken as the thickness at the thickest point in the vertical direction from the substrate 10. Hereinafter, this average value will be referred to as the "maximum thickness" for convenience. Figs. 2(a) and (b) show examples of electron micrographs (TEM images) of the cross-section of the electromagnetic wave transmissive laminate member. When obtaining the maximum thickness, first, in the metal layer appearing on the surface of the electromagnetic wave transmissive laminate member as shown in Figs. 2(a) and (b), a square region 3 with a side length of 5 cm as shown in Fig. 3 was appropriately extracted, and a total of five points "a" to "e" obtained by equally dividing the center lines A and B of the vertical side and the horizontal side of the square region 3 into four equal parts were selected as the measurement locations. Next, in the cross-sectional images as shown in Figs. 2(a) and (b) at each of the selected measurement locations, a field-of-view angle region containing approximately five portions 12a was extracted. The individual thicknesses of the five portions 12a, that is, 25 (5 × 5) portions 12a at each of these five measurement locations were obtained, and their average value was taken as the "maximum thickness".

[0087] <Measurement of volume fractions of the portions containing Al and the portions containing In> To measure the volume fractions of the portions containing Al and the portions containing In, TEM-EDX analysis or TEM-EDX mapping was performed after the above-mentioned film thickness measurement to measure the mass concentrations (mass %) of aluminum and indium. That is, the aluminum mass concentration and the indium mass concentration at the locations corresponding to the above-mentioned 25 portions 12a selected during the measurement of the thickness of the metal layer were obtained, and their average values were obtained respectively. Thereafter, In density 7.31 g / cm3 , Al density 2.70g / cm 3 The volume fraction (volume %) of the part containing Al and the volume fraction (volume %) of the part containing In were calculated by converting mass % to volume % using the conversion formula: volume % = mass % ÷ density.

[0088] [Example 1] As the substrate film, a Mitsubishi Chemical Corporation easy-formable PET film (product number: G931E75, thickness: 50 μm) was used. First, an In-Sn alloy layer was formed as a first layer on the substrate film by DC pulse sputtering (150 kHz) using an In-Sn alloy target (Sn ratio 5 mass%): ITM. The sputtering was performed in an atmosphere without oxygen supply. The obtained first layer had a discontinuous structure. Next, an aluminum (Al)-containing layer was formed as a second layer on the first layer by AC sputtering (AC: 40 kHz) using an Al target. The first layer and the second layer were then integrated to form a metal layer. As a result, an electromagnetic wave-transmitting metallic gloss member of Example 1 in which the metal layer was formed on the substrate film was obtained. The electromagnetic wave transmissible metallic luster member of Example 1 thus obtained was subjected to various evaluations, and the results are shown in Table 1. In addition, elemental analysis was performed using a JEOL FE-TEM JEM-2800 to measure the distribution of In, Al, and O elements, and the results are shown in FIG. 4(a). The obtained metal layer had a discontinuous structure, and contained parts containing aluminum element and parts containing indium element within the same metal layer, and the parts containing indium element were unevenly distributed within the metal layer (on the side opposite to the base film). Electron microscope photographs (SEM images) of the surface of the electromagnetic wave transparent lustrous metallic member of Example 1 before and after stretching are shown in FIG. 5(a) and (b).

[0089] [Example 2] An electromagnetic wave-transmitting metallic glossy member of Example 2 was produced and evaluated in the same manner as Example 1, except that the content (volume %) of the portion containing Al element in the metal layer and the content (volume %) of the portion containing indium element (In, Sn) in the metal layer were changed to be as shown in Table 1. Furthermore, the obtained metal layer had a discontinuous structure, containing parts containing aluminum elements and parts containing indium elements within the same metal layer, and the parts containing indium elements were unevenly distributed within the metal layer (on the side opposite to the base film).

[0090] [Example 3] to [Example 6] The electromagnetic wave-transmitting metallic luster members of Examples 3 to 6 were produced and evaluated in the same manner as in Example 1, except that the content (volume %) of the portion containing Al element in the metal layer, the content (volume %) of the portion containing indium element (In, Sn) in the metal layer, and the film thickness of the metal layer were changed as shown in Table 1. Furthermore, the obtained metal layer had a discontinuous structure, containing parts containing aluminum elements and parts containing indium elements within the same metal layer, and the parts containing indium elements were unevenly distributed within the metal layer (on the side opposite to the base film).

[0091] [Comparative Example 1] An electromagnetic wave-transmitting metallic glossy member of Comparative Example 1 was produced and evaluated in the same manner as in Example 1, except that the first layer was an aluminum (Al)-containing layer and a metal layer was formed without providing a second layer.

[0092] [Comparative Example 2] An electromagnetic wave-transmitting metallic glossy member of Comparative Example 2 was produced and evaluated in the same manner as in Example 1, except that the content (volume %) of the portion containing Al element in the metal layer and the content (volume %) of the portion containing indium element (In, Sn) in the metal layer were changed to be as shown in Table 1.

[0093] [Comparative Example 3] An electromagnetic wave-transmitting metallic glossy member of Comparative Example 3 was produced and evaluated in the same manner as in Example 1, except that the first layer was a layer made of an In-Sn alloy and a metal layer was formed without providing a second layer.

[0094] [Comparative Example 4] An electromagnetic wave-transmitting lustrous metal member of Comparative Example 4 was produced and evaluated in the same manner as in Example 1, except that the first layer was formed using ITO. In the electromagnetic wave-transmitting lustrous metal member of Comparative Example 4, the first layer was formed using ITO, so that the first layer and the second layer were not integrated, but were formed in a state where two independent layers (a base layer and a metal layer) were laminated. Therefore, the content of the portion containing Al element in the second layer was 100 volume %, and the content of the portion containing In element was 0 volume %. In addition, the electromagnetic wave transmissible metallic luster member obtained in Comparative Example 4 was subjected to elemental analysis using a JEOL FE-TEM JEM-2800. The distribution of In, Al, and O elements was measured, and the results are shown in FIG. 4(b). Electron microscope photographs (SEM images) of the surface of the electromagnetic wave transparent lustrous metallic member of Comparative Example 4 before and after stretching are shown in FIG. 6(a) and (b).

[0095] [Comparative Example 5] to [Comparative Example 6] Electromagnetic wave-transmitting metallic glossy members of Comparative Examples 5 and 6 were produced and evaluated in the same manner as in Example 1, except that the ITM target was changed to an In target, and the content (volume %) of the portion containing Al element in the metal layer, the content (volume %) of the portion containing indium element (In) in the metal layer, and the film thickness of the metal layer were changed to those shown in Table 1.

[0096] [Table 1]

[0097] As is clear from Table 1, the electromagnetic wave-transmitting metallic luster members of Examples 1 and 2 had good results in terms of electromagnetic wave transparency, appearance, and stretchability even after stretching. Furthermore, as shown in the SEM image of Example 1 after stretching (FIG. 5(b)), the crack width after stretching was small, and no surface turbidity was observed. The electromagnetic wave-transmitting metallic luster members of Examples 3 to 6 had good electromagnetic wave transparency and good stretchability even after stretching. Furthermore, the appearance was also at an acceptable level. On the other hand, in Comparative Examples 1 to 3, 5, and 6, the volume fraction of the portion containing indium element in the metal layer was outside the range of the present invention, and therefore at least one of the evaluations of electromagnetic wave transmission, appearance, and stretchability was poor after stretching. In Comparative Example 4, the first layer and the second layer were not integrated, and two independent metal layers were laminated, and the portion containing aluminum element and the portion containing indium element were not contained in the same metal layer, and at least one of the evaluations of electromagnetic wave transmission, appearance, and stretchability was poor after stretching. As shown in the SEM image (FIG. 6(b)) of Comparative Example 4 after stretching, the crack width was large and the surface was cloudy.

[0098] The present invention is not limited to the above-described embodiment, and can be embodied by making appropriate modifications without departing from the spirit of the invention. [Industrial Applicability]

[0099] The electromagnetic wave-transmitting lustrous metallic member according to the present invention can be used for devices and articles that transmit and receive electromagnetic waves, and parts thereof, etc. For example, it can be used for various applications that require both design and electromagnetic wave transmittance, such as vehicle structural parts, vehicle-mounted items, housings for electronic devices, housings for home appliances, structural parts, machine parts, various automobile parts, electronic device parts, household goods such as furniture and kitchen utensils, medical equipment, building material parts, and other structural parts and exterior parts.

[0100] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention. This application is based on a Japanese patent application (Patent Application No. 2020-040058) filed on March 9, 2020, the contents of which are incorporated herein by reference. [Explanation of symbols]

[0101] 1. Electromagnetic wave-transmitting metallic glossy material 10 Base 12 metal layer 12a part 12b Gap

Claims

1. A substrate and a metal layer formed on the substrate, the metal layer includes a plurality of portions that are at least partially discontinuous with each other; the metal layer includes a portion containing an aluminum element and a portion containing an indium element, the portion containing the indium element is unevenly distributed in the metal layer, a volume fraction (volume %) of the portion containing the indium element in the metal layer is 5 to 40 volume %; Electromagnetic wave-transmitting metallic glossy material.

2. 2. The electromagnetic wave transmissible lustrous metallic member according to claim 1, wherein the portion containing elemental indium is unevenly distributed on a side of the metal layer opposite to the substrate.

3. 3. The electromagnetic wave transmissive lustrous metallic member according to claim 1, wherein the metal layer has a thickness of 10 nm to 200 nm.

4. The electromagnetic wave transmitting lustrous metallic member according to any one of claims 1 to 3, wherein the plurality of portions are formed in an island shape.

5. The electromagnetic wave transmitting metallic luster member according to any one of claims 1 to 4, wherein the substrate is any one of a substrate film, a substrate of a resin molded product, and an article to which metallic luster is to be imparted.

6. The electromagnetic wave transparent lustrous metallic member according to any one of claims 1 to 5, wherein the metal layer has a crack width of 150 nm or less when subjected to a tensile test at an elongation rate of 20%.

7. The electromagnetic wave transparent metallic luster member according to any one of claims 1 to 6, wherein the Y value (SCE) measured using a spectrophotometer in accordance with the geometric condition c of JIS Z 8722 when a tensile test is performed at an elongation rate of 20% is 0.3 or less.

8. A first step of forming a layer on a substrate, the layer including at least an indium element and including a plurality of portions that are at least partially discontinuous with each other; A second step of depositing a metal containing an aluminum element on the layer formed in the first step. A method for producing the electromagnetic wave transparent lustrous metallic member according to any one of claims 1 to 7.

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

Images