JP6944425B2 - Electromagnetic wave transmissive metallic luster member, articles using this, and metal thin film - Google Patents

Description

The present invention relates to an electromagnetic wave transmitting metallic luster member, an article using the member, and a metal thin film.

For example, in order to decorate a cover member of a millimeter-wave radar mounted on a front part of an automobile such as a front grille and an emblem, a metallic luster member having both brilliance and electromagnetic wave transmission is required.

Millimeter-wave radar transmits electromagnetic waves in the millimeter-wave band (frequency of about 77 GHz, wavelength of about 4 mm) to the front of the vehicle, receives reflected waves from the target, measures and analyzes the reflected waves, and so on. It can measure the distance, the direction of the target, and the size. The measurement results can be used for inter-vehicle distance measurement, automatic speed adjustment, automatic brake adjustment, and the like. Since the front part of the automobile in which such a millimeter-wave radar is arranged is, so to speak, the face of the automobile and has a great impact on the user, it is preferable to produce a high-class feeling with a metallic luster-like front decoration. However, when metal is used for the front part of the automobile, the transmission and reception of electromagnetic waves by the millimeter wave radar is practically impossible or obstructed. Therefore, a metallic luster member having both brilliance and electromagnetic wave transmission is required in order not to interfere with the operation of the millimeter-wave radar and not to impair the design of the automobile.

This type of metallic glossy member is used not only for millimeter-wave radar but also for various devices that require communication, such as door handles of automobiles equipped with smart keys, in-vehicle communication devices, mobile phones, electronic devices such as personal computers, and the like. Is expected to be applied. Furthermore, in recent years, with the development of IoT technology, it is expected to be applied in a wide range of fields such as home appliances such as refrigerators and household appliances, which have not been used for communication in the past.

Regarding the metallic luster member, Japanese Patent Application Laid-Open No. 2007-144988 (Patent Document 1) discloses a resin product containing a metal film made of chromium (Cr) or indium (In). This resin product has a resin base material, an inorganic base film containing an inorganic compound formed on the resin base material, and a brilliant and discontinuous film formed on the inorganic base film by a physical vapor deposition method. It contains a metal film made of chromium (Cr) or indium (In) having a structure. As the inorganic base film, in Patent Document 1, (a) a thin film of a metal compound, for example, _{a titanium compound such as titanium oxide (TIO, TiO 2} , Ti ₃ O _5, etc.); silicon oxide (SiO, SiO _2, etc.), nitrided Silicon compounds such as silicon (Si ₃ N ₄ etc.); Aluminum compounds such as aluminum _{oxide (Al 2} O _{3 ); Iron compounds such as iron oxide (Fe 2} O ₃ ); Selenium compounds such as selenium oxide (CeO); Oxidation Zyrcon compounds such as zircon (ZrO); zinc compounds such as zinc sulfide (ZnS), etc., (b) coating film of inorganic paint, for example, silicon, amorphous TiO _{2 and the} like (other metal compounds exemplified above) as main components. A coating film made of inorganic paint is used. However, in this resin product, only chromium (Cr) or indium (In) is used as the metal film, and aluminum (Al), for example, which is superior in price and brilliance as compared with these, is used as the metal film. It is not possible.

On the other hand, in Japanese Patent Application Laid-Open No. 2009-298006 (Patent Document 2), not only chromium (Cr) or indium (In) but also aluminum (Al), silver (Ag) and nickel (Ni) are formed as a metal film. An electromagnetic wave transmissive bright resin product capable of being disclosed is disclosed. These metal films are formed by providing a base film having a discontinuous structure. In order to make the base film a discontinuous layer, the inclination angle of the base material for sputtering is set to 0 ° or 70 °. There is a problem that the manufacturing is complicated because there are restrictions such as having to do so. Further, according to Patent Document 2, for example, zinc (Zn), lead (Pb), copper (Cu), or an alloy thereof cannot be formed as a metal film.

JP-A-2007-144988 JP-A-2009-298006 Japanese Unexamined Patent Publication No. 2010-5999

The present invention has been made to solve these problems in the prior art, and not only chromium (Cr) or indium (In) but also other metals such as aluminum (Al) are used as the metal layer. In this case as well, it is an object of the present invention to provide an electromagnetically transmissive metallic luster member that can be easily manufactured. Further, an electromagnetic wave-transmitting metallic luster member capable of forming a metal layer of zinc (Zn), lead (Pb), copper (Cu), or an alloy thereof in addition to aluminum (Al) and silver (Ag) is provided. The purpose is to do.

As a result of diligent studies to solve the above problems, the present inventors have used an indium oxide-containing layer as a base layer, and as a result, not only chromium (Cr) or indium (In) but also a normally discontinuous structure. It has been found that a metal layer made of other metals such as indium (Al) can also have a discontinuous structure, and the present invention has been completed.

In order to solve the above problems, the electromagnetic wave transmitting gloss member according to one aspect of the present invention includes an indium oxide-containing layer provided along the surface of the substrate and a metal layer laminated on the indium oxide-containing layer. , The metal layer includes a plurality of portions that are discontinuous with each other at least in part.
According to the electromagnetic wave transmitting metal gloss member of this embodiment, by using the indium oxide-containing layer as the base layer, it is usually difficult to form a discontinuous structure, for example, even a metal layer made of another metal such as aluminum (Al). Since the discontinuous structure can be formed, and as a result, the sheet resistance can be increased to improve the electromagnetic wave transmission property, not only chromium (Cr) or indium (In) but also aluminum (Al) and the like can be used. Provided is an easily manufacturable electromagnetic wave transmitting metal gloss member using the same metal as a metal layer. Further, an electromagnetic wave-transmitting metallic luster member using silver (Ag), zinc (Zn), lead (Pb), copper (Cu), or an alloy thereof as a metal layer in addition to aluminum (Al) is provided. NS.
In the electromagnetic wave transmitting metallic luster member of the above aspect, the indium oxide-containing layer may be in a continuous state. By setting the continuous state, smoothness and corrosion resistance can be improved, and it becomes easy to form an indium oxide-containing layer without in-plane variation.
The substrate may be a substrate film, a resin molded substrate, a glass substrate, or an article to which metallic luster should be imparted.

In the electromagnetic wave transmitting metal gloss member of the above aspect, the indium oxide-containing layer may be either indium oxide (In2O3), indium tin oxide (ITO), or indium zinc oxide (IZO).

Further, in the electromagnetic wave transmitting metallic luster member of the above aspect, the thickness of the indium oxide-containing layer is preferably 1 nm to 1000 nm. Further, in the electromagnetic wave transmitting metallic luster member of the above aspect, the thickness of the metal layer is preferably 20 nm to 100 nm. Further, in the electromagnetic wave transmitting metallic luster member of the above aspect, the ratio of the thickness of the metal layer to the thickness of the indium oxide-containing layer (thickness of the metal layer / thickness of the indium oxide-containing layer) is 0. It is preferably 02 to 100.

Further, in the electromagnetic wave transmitting metallic luster member of the above aspect, the sheet resistance of the metal layer and the indium oxide-containing layer as a laminate may be 100 to 100,000 Ω / □.

Further, in the electromagnetic wave transmitting metallic luster member of the above aspect, the portion may be formed in an island shape.

In the electromagnetic wave transmitting metallic luster member of the above aspect, the metal layer is any of aluminum (Al), zinc (Zn), lead (Pb), copper (Cu), silver (Ag), or an alloy thereof. You may.

Further, in the electromagnetic wave-transmitting metallic luster member of the above-described embodiment, the article may be an article using a base film, a resin molded base material, or a glass base material, or an article to be imparted metallic luster to an electromagnetic wave-transmitting metal. It may be an article provided with a glossy member.

Further, according to another aspect of the present invention, it is a metal thin film provided along the surface of the substrate, and the metal thin film has a thickness of 20 nm to 100 nm and is in a state of being discontinuous with each other at least in a part. It is characterized by a metal thin film containing a plurality of island-shaped portions in.
By making the metal thin film transferable, the metal thin film can be easily provided on various articles.

According to the present invention, an electromagnetic wave transmitting metal that can be easily produced not only when chromium (Cr) or indium (In) but also other metals such as aluminum (Al) are used as the metal layer. A glossy member can be provided. Further, an electromagnetic wave-transmitting metallic luster member capable of forming a metal layer of silver (Ag), zinc (Zn), lead (Pb), copper (Cu), or an alloy thereof in addition to aluminum (Al) is provided. be able to.

FIG. 1A is a schematic cross-sectional view of an electromagnetic wave-transmitting metallic luster member according to an embodiment of the present invention and an electromagnetic wave-transmitting metal film using the metallic luster member, and FIG. 1B is a schematic cross-sectional view. It is an electron micrograph of the surface of the electromagnetic wave transmissive metallic luster member according to one embodiment of the present invention. It is an image of the cross section in a part region of FIG. 1 (b).

Hereinafter, one preferred embodiment of the present invention will be described with reference to the accompanying drawings. In the following, for convenience of explanation, only preferred embodiments of the present invention will be shown, but of course, this is not intended to limit the present invention.

<1. Basic configuration>
FIG. 1A shows an electromagnetic wave-transmitting metallic luster member (hereinafter, referred to as “metallic luster member”) 1 according to an embodiment of the present invention, and an electromagnetic wave-transmitting metal film (hereinafter, referred to as “metal luster member”) using the metallic luster member 1. , "Metal film") 3 is shown, and FIG. 1 (b) shows an electron micrograph (SEM image) of the surface of the metallic luster member 1 according to the embodiment of the present invention. The image size in the electron micrograph is 1.16 μm × 0.85 μm.

The metallic luster member 1 includes an indium oxide-containing layer 11 as a base layer containing at least indium oxide, and a metal layer 12 laminated on the indium oxide-containing layer 11. The metal film 3 includes the metallic luster member 1 and the base film 10. The indium oxide-containing layer 11 is provided on the surface of the base film 10 to which metallic luster should be imparted. The indium oxide-containing layer 11 may be provided directly on the surface of the base film 10, or may be indirectly provided via a protective film or the like provided on the surface of the base film 10. The indium oxide-containing layer 11 is preferably provided continuously on the surface of the base film 10 to be imparted metallic luster, in other words, without gaps. By providing the indium oxide-containing layer 11 in a continuous state, the smoothness and corrosion resistance of the metallic luster member 1 and the metal film 3 can be improved, and the indium oxide-containing layer 11 is formed without in-plane variation. It also becomes easier.

The metal layer 12 is laminated on the indium oxide-containing layer 11. The metal layer 12 includes a plurality of portions 12a. By being laminated on the indium oxide-containing layer 11, these portions 12a are separated from each other by a gap 12b at least in a discontinuous state, in other words, at least in a part. Since they are separated by the gap 12b, the sheet resistance of these portions 12a increases and the interaction with the radio waves decreases, so that the radio waves can be transmitted. Each of these portions 12a is an aggregate of sputtered particles formed by vapor deposition, sputtering, or the like of a metal. When the sputtered particles form a thin film on a substrate such as the substrate film 10, the surface diffusivity of the particles on the substrate affects the shape of the thin film. As a result of diligent research, the present inventors have succeeded in growing the metal layer in a discontinuous state by providing an indium oxide-containing layer on the substrate and promoting the surface diffusivity of the metal film. The "discontinuous state" referred to in the present specification means a state in which they are separated from each other by a gap 12b, and as a result, they are electrically insulated from each other. By being electrically insulated, the sheet resistance is increased and the desired electromagnetic wave transmission can be obtained. The discontinuous form is not particularly limited, and includes, for example, islands, cracks, and the like. Here, as shown in FIG. 1B, the term "island-like" means that the particles, which are aggregates of sputtered particles, are independent of each other, and the particles are slightly separated from each other or separated from each other. It means a structure that is laid out in a state of partial contact.

<2. Base film (base)>
The base film 10 includes polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate, polyamide, polyvinyl chloride, polycarbonate (PC), cycloolefin polymer (COP), polystyrene, polypropylene (PP), and polyethylene. , Polycycloolefin, polyurethane, acrylic (PMMA), ABS and other homopolymers and copolymers can be used. According to these members, the brilliance and the electromagnetic wave transmission are not affected. However, from the viewpoint of forming the indium oxide-containing layer 11 and the metal layer 12 later, it is preferable that the layer can withstand high temperatures such as vapor deposition and sputtering. Therefore, among the above materials, for example, polyethylene terephthalate, polyethylene naphthalate, and the like. Acrylic, polycarbonate, cycloolefin polymer, ABS, polypropylene and polyurethane are preferred. Of these, polyethylene terephthalate, cycloolefin polymer, polycarbonate, and acrylic are preferable because they have a good balance between heat resistance and cost. The base film 10 may be a single-layer film or a laminated film. From the viewpoint of ease of processing and the like, the thickness is preferably about 6 μm to 250 μm, for example. In order to strengthen the adhesive force with the indium oxide-containing layer 11, plasma treatment, easy-adhesion treatment, or the like may be performed.

Here, it should be noted that the base film 10 is only an example of an object (hereinafter, referred to as “base”) to which the metallic luster member 1 of the present invention can be applied. The substrate includes, in addition to the substrate film 10, a resin molded substrate, a glass substrate, and the article itself to which metallic luster should be imparted. Examples of the resin molded base material include resins for automobile emblems and the like. Examples of articles to which metallic luster should be imparted include automobile doorknobs provided with smart keys, mobile phone housings, personal computer housings, refrigerators, and the like. The metallic luster member 1 of the present invention can be applied to all of these substrates. In this case, the substrate to which the metallic luster member 1 is to be provided preferably satisfies the same materials and conditions as the above-mentioned substrate film 10.

<3. Indium oxide-containing layer>
Indium oxide (In2O3) itself can be used as the indium oxide-containing layer 11, or a metal-containing substance such as indium tin oxide (ITO) or indium zinc oxide (IZO) can be used. can. However, ITO and IZO containing a second metal are more preferable because they have high discharge stability in the sputtering process. By using these indium oxide-containing layers 11, a continuous film can be formed along the surface of the substrate, and in this case, a metal layer laminated on the indium oxide-containing layer can be formed. For example, it may have an island-like discontinuous structure. Further, as will be described later, in this case, not only chromium (Cr) or indium (In) but also aluminum or the like, which is usually difficult to form a discontinuous structure in the metal layer and is difficult to apply to this application, is used. Various metals can be included. The content of tin (Sn) with respect to the weight of In2O3 in ITO is not particularly limited, but is, for example, 2.5 wt% to 30 wt%, more preferably 3 wt% to 10 wt%. The content of zinc oxide (ZnO) with respect to the weight of In2O3 in IZO is, for example, 2 wt% to 20 wt%. The thickness of the indium oxide-containing layer 11 is usually preferably 1000 nm or less, more preferably 50 nm or less, still more preferably 20 nm or less, from the viewpoint of sheet resistance, radio wave transmission, and productivity. On the other hand, it is preferably 1 nm or more so that the laminated metal layer 12 is in a discontinuous state, more preferably 2 nm or more, and further preferably 5 nm or more in order to ensure a discontinuous state. preferable.

<4. Metal layer>
It is desirable that the metal layer 12 has a relatively low melting point as well as being able to exhibit sufficient brilliance. This is because the metal layer 12 is provided by thin film growth using sputtering. For this reason, a metal having a melting point of about 1000 ° C. or lower is suitable as the metal layer 12, and for example, aluminum (Al), zinc (Zn), lead (Pb), copper (Cu), and silver (Ag). ), And any of an alloy containing the metal as a main component is preferably contained. In particular, Al and its alloys are preferable because of the brilliance, stability, price, and the like of the substance.

The thickness of the metal layer 12 is usually preferably 20 nm or more so as to exhibit sufficient brilliance, while it is usually preferably 100 nm or less from the viewpoint of sheet resistance and radio wave transmission. For example, 20 nm to 100 nm is preferable, and 30 nm to 70 nm is more preferable. This thickness is also suitable for forming a uniform film with good productivity, and the appearance of the final resin molded product is also good.

For the same reason, the ratio of the thickness of the metal layer to the thickness of the indium oxide-containing layer (thickness of the metal layer / thickness of the indium oxide-containing layer) is preferably in the range of 0.1 to 100, and is 0. The range of 3 to 35 is more preferable.

Further, the sheet resistance of the metal layer and the indium oxide-containing layer as a laminate is preferably 100 to 100,000 Ω / □. In this case, the radio wave transmission property is about 10 to 0.01 [−dB] at a wavelength of 1 GHz. More preferably, it is 1000 to 50,000 Ω / □. The value of this sheet resistance is greatly affected not only by the material and thickness of the metal layer but also by the material and thickness of the indium oxide-containing layer which is the base layer. Therefore, it is necessary to consider the relationship with the indium oxide-containing layer before setting.

<5. Mechanism of discontinuity of metal layer>
When the metal layer 12 is formed directly on the substrate without providing the indium oxide-containing layer 11, the metal layer 11 is in a continuous state on the substrate 10. In this case, although sufficient brilliance can be obtained, the sheet resistance becomes very small, and therefore radio wave transmission cannot be ensured. On the other hand, when the metal layer 12 is laminated on the indium oxide-containing layer 11 formed on the substrate, for example, the metal layer 11 is discontinuous on the indium oxide-containing layer 11 formed in a continuous state. It is formed in a state, and as a result, not only sufficient brilliance can be obtained, but also radio wave transmission can be ensured. The details of the mechanism by which the metal layer 11 becomes discontinuous on the indium oxide-containing layer 11 are not always clear, but it is presumed to be roughly as follows. That is, in the thin film forming process of the metal layer 11, the ease of forming the discontinuous structure is related to the surface diffusion on the applied member (indium oxide-containing layer 11 in this case) to which the metal layer 11 is applied. The higher the temperature of the applied member, the smaller the wettability of the metal layer with respect to the applied member, and the lower the melting point of the material of the metal layer, the easier it is to form a discontinuous structure. Therefore, with respect to metals other than aluminum (Al) particularly used in the following examples, metals having a relatively low melting point such as zinc (Zn), lead (Pb), copper (Cu), and silver (Ag) are used. , It is considered that a discontinuous structure can be formed by the same method.

<6. Manufacture of metallic luster members>
An example of a method for manufacturing the metallic luster member 1 will be described by taking as an example a case where the base film 10 is used as a substrate, that is, a case where the metal film 3 is manufactured. Although not particularly described, it can be produced by the same method when a substrate other than the substrate film 10 is used.

(1) Step of forming an indium oxide-containing layer A film of an indium oxide-containing layer 11 is formed on a base film 10. The indium oxide-containing layer 11 can be formed by vacuum deposition, sputtering, ion plating, or the like. However, sputtering is preferable because the thickness can be strictly controlled even in a large area.

(2) Step of Laminating the Metal Layer Next, the metal layer 12 is laminated on the indium oxide-containing layer 11. In this case as well, for example, sputtering can be used. It is preferable that the indium oxide-containing layer 11 and the metal layer 12 are in direct contact with each other without interposing another layer. However, if the mechanism of surface diffusion of the metal layer 12 on the indium oxide-containing layer 11 described above is ensured, another layer can be interposed.

<7. Example>
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. Various samples were prepared for the metal film 3, and the sheet resistance, the amount of radio wave transmission attenuation, and the visible light reflectance were evaluated. Sheet resistance and radio wave transmission attenuation are evaluations related to radio wave transmission, and visible light reflectance is an evaluation related to brilliance. The values of visible light reflectance and sheet resistance are preferably large, and the values of radio wave transmission attenuation are preferably small.
The details of the evaluation method are as follows.

(1) Sheet resistance Using a non-contact resistance measuring device NC-80MAP manufactured by Napson Corporation, the sheet resistance as a laminate of a metal layer and an indium oxide-containing layer was measured by an eddy current measurement method in accordance with JIS-Z2316.
The sheet resistance needs to be 100 Ω / □ or more, preferably 200 Ω / □ or more, and more preferably 600 Ω / □ or more. If it is smaller than 100Ω / □, there is a problem that sufficient radio wave transmission cannot be obtained.

(2) Radio wave transmission attenuation
The amount of radio wave transmission attenuation at 1 GHz was evaluated using the KEC method measurement evaluation jig and the Agilent spectrum analyzer CXA signal Analyzer NA9000A. Since there is a correlation between the electromagnetic wave transmission in the frequency band (76 to 80 GHz) of the millimeter wave radar and the electromagnetic wave transmission in the microwave band (1 GHz), and the values are relatively close, in this evaluation, microwaves are used. The electromagnetic wave permeability in the band (1 GHz), that is, the amount of microwave electric field transmission attenuation was used as an index.
The amount of microwave electric field transmission attenuation needs to be 10 [−dB] or less, preferably 5 [−dB] or less, and more preferably 2 [−dB] or less. If it is 10 [−dB] or more, there is a problem that 90% or more of the radio waves are blocked.

(3) Visible light reflectance The reflectance at a measurement wavelength of 550 nm was measured using a spectrophotometer U4100 manufactured by Hitachi High-Technologies Corporation. As a reference, the reflectance of the Al vapor deposition mirror was set to 100%.
The visible light reflectance needs to be 20% or more, preferably 40% or more, and more preferably 50% or more in order to have sufficient brilliance. If the visible light reflectance is less than 20%, there is a problem that the brilliance is lowered and the appearance is not excellent.

The evaluation results are shown in Table 1 below.

[Example 1]
As the base film, a PET film (thickness 125 μm) manufactured by Mitsubishi Plastics Co., Ltd. was used.
First, DC magnetron sputtering was used to form an ITO layer with a thickness of 50 nm directly on the surface of the base film. The temperature of the base film when forming the ITO layer was set to 130 ° C. ITO contains 10 wt% of Sn with respect to In2O3.

Next, an aluminum (Al) layer having a thickness of 50 nm was formed on the ITO layer by using alternating current sputtering (AC: 40 kHz) to obtain a metallic luster member (metal film). The temperature of the base film when forming the Al layer was set to 130 ° C.

FIG. 1B is an electron micrograph (SEM image) of the surface of a metallic luster member (metal film) obtained as a result of these treatments, and FIG. 2 is a partial region of FIG. 1B. It is an image of a cross section in. The image size in the electron micrograph of FIG. 2 is 1.16 μm × 0.85 μm.

As is clear from these figures, in this embodiment, since the ITO layer of the metallic luster member is provided in a continuous state along the surface of the base film, it exhibits high smoothness and corrosion resistance, while exhibiting high smoothness and corrosion resistance. Since the aluminum layer contains a plurality of portions 12a formed in a discontinuous state by being laminated on the ITO layer, its sheet resistance is 260 Ω / □, and its radio wave transmission attenuation is at a wavelength of 1 GHz. It was 4.5 [−dB], and good results were obtained for radio wave transmission. In Table 1, for convenience, as a result of "evaluation" of the radio wave transmission attenuation, the case where the radio wave transmission attenuation is smaller than 2 [−dB] is indicated by “⊚”, which is 2 [−dB] or more and 5 [−dB]. A case smaller than [dB] is represented by “◯”, a case of 5 [−dB] or more and smaller than 10 [−dB] is represented by “Δ”, and a case of 10 [−dB] or more is represented by “x”.
In addition, the visible light reflectance of this metallic luster member was 56%, and good results were obtained in terms of brilliance. For convenience, in Table 1, as a result of "evaluation" of the visible light reflectance, "⊚" is given when the visible light reflectance is greater than 50%, and "○" is given when the visible light reflectance is 50% or less and greater than 40%. The case of 40% or less and larger than 20% is represented by "Δ", and the case of 20% or less is represented by "x". Furthermore, as a "comprehensive evaluation" of radio wave transmission and brilliance, the same evaluation result is shown when both have the same evaluation result, and the worse evaluation result is shown when one is worse than the other. .. As a result, the overall evaluation of Example 1 was "◯", and a good metallic luster member or a metal film having both radio wave transmission and brilliance was obtained.

[Example 2] to [Example 4]
The thickness of the aluminum layer laminated on the ITO layer is changed so that it is thinner than that of Example 1 for Examples 2 and 3, while it is thicker than that of Example 1 for Example 4. Changed to be. Other conditions are the same as in Example 1.
In this case, the same values and results as in Example 1 were obtained for the sheet resistance and the amount of radio wave transmission attenuation in all of Examples 2 to 4. On the other hand, regarding the visible light reflectance, the result was slightly inferior to Examples 2 and 3 in which the thickness of the aluminum layer was thinner than that of Example 1, but it was better than that in Example 1 in Example 4. Results were obtained. However, Examples 2 and 3 are also sufficiently durable for practical use.

[Example 5] to [Example 8]
The thickness of the ITO layer was set to be thinner than that of Example 1. Other conditions are the same as in Example 1.
In this case, the sheet resistance and the amount of radio wave transmission attenuation were better than those of Example 1 in all of Examples 5 to 8. Further, regarding the visible light reflectance, the same values and results as those in Example 1 were obtained in all of Examples 5 to 8. From these examples, it was clarified that the thickness of the ITO layer may be thin, and it was clarified that the material cost can be suppressed by reducing the thickness of the ITO layer.

[Example 9] to [Example 12]
The Sn content in the ITO layer was changed to be larger than that of Example 1 for Example 9, while it was changed to be smaller than that of Example 1 for Examples 10 to 12. Since Sn is set to zero in the ITO layer of Example 12, more accurately, it is not an ITO layer but an indium oxide (In2O3) layer. In addition, in Example 12, the aluminum layer was set to 40 nm. Other conditions are the same as in Example 1.
In this case, regarding the sheet resistance and the amount of radio wave transmission attenuation, the same results as in Example 1 were obtained in Examples 9 to 11, and the results in Example 12 were slightly inferior to those in Example 1. Regarding the visible light reflectance, the same values and results as in Example 1 were obtained in Examples 9 to 11, and the results were slightly inferior to those in Example 1 in Example 12. From this result, it became clear that the ITO layer preferably contains Sn.

[Example 13]
IZO containing ZnO in indium oxide was used instead of ITO. ZnO is contained in an amount of 11 wt% with respect to In2O3. Other conditions are the same as in Example 1.
In this case, the sheet resistance and the amount of radio wave transmission attenuation were slightly inferior to those of Example 1. On the other hand, regarding the visible light reflectance, the same values and results as in Example 1 were obtained. Although the overall evaluation was inferior to that of Example 1, it was clarified that even when ZnO was contained, it was sufficiently practical.

[Comparative Example 1]
The thickness of the aluminum layer laminated on the ITO layer was changed to be thicker than that of Example 1. Other conditions are the same as in Example 1.
In this case, the visible light reflectance was better than that of Example 1 due to the increased thickness. On the other hand, the sheet resistance and the amount of radio wave transmission attenuation were significantly inferior to those of Example 1, which made it impractical.

[Comparative Example 2]
An aluminum layer was directly formed on the base film without providing an ITO layer. Other conditions are the same as in Example 1.
In this case, the visible light reflectance was obtained in the same value and result as in Example 1, but the sheet resistance and the amount of radio wave transmission attenuation were significantly inferior to those in Example 1, which was impractical. It became something like that.

<8. Use of metal thin film>
The metal layer 12 formed on the metallic luster member 1 is thin with a thickness of about 20 nm to 100 nm, and only this can be used as a metal thin film. For example, a metal layer 12 is formed by sputtering on an indium oxide-containing layer 11 laminated on a substrate such as a substrate film 10 to obtain a film. Separately, an adhesive is applied onto the base material to prepare a base material with an adhesive layer. The metal layer (metal thin film) 12 existing on the outermost surface of the film is formed by adhering the film and the base material so that the metal layer 12 and the adhesive layer are in contact with each other, and after sufficiently adhering the film and the base material, the film and the base material are peeled off. Can be transferred to the outermost surface of the substrate.

The present invention is not limited to the above-described embodiment, and can be appropriately modified and embodied without departing from the spirit of the invention.

The metal film or metallic luster member according to the present invention can be suitably used for decorating a cover member of a millimeter-wave radar mounted on a front portion of an automobile such as a front grill or an emblem. Further, for example, it can be used for various applications requiring both design and electromagnetic wave transmission, such as mobile phones, smartphones, tablet PCs, notebook PCs, and refrigerators.

1 Metal luster member 3 Metal film 10 Base film 11 Indium oxide-containing layer 12 Metal layer

Claims (7)

A metal thin film provided along the surface of the substrate, wherein the metal thin film contains a plurality of portions that are discontinuous with each other at least in part, and the metal thin film is indium oxide provided on the surface of the substrate. is stacked-containing layer, in a plane the indium oxide-containing layer is continuous, characterized in that it comprises a plurality of portions in a discontinuous with each other at least in part, to the indium oxide-containing layer A laminated metal thin film for transfer that transmits radio waves. The metal thin film for transfer according to claim 1, wherein the indium oxide-containing layer is any one of indium oxide (In2O3), indium tin oxide (ITO), and indium zinc oxide (IZO). The metal thin film for transfer according to claim 2, wherein the thickness of the indium oxide-containing layer is 1 nm to 1000 nm. The transfer metal thin film according to any one of claims 1 to 3, wherein the metal thin film has a thickness of 20 nm to 100 nm. The transfer metal thin film according to any one of claims 1 to 4, wherein the portion is formed in an island shape. The method according to any one of claims 1 to 5, wherein the metal thin film is any one of aluminum (Al), zinc (Zn), lead (Pb), copper (Cu), silver (Ag), or an alloy thereof. Metal thin film for transfer. An article to which the metal thin film for transfer according to any one of claims 1 to 6 is transferred.

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