Laminate body and decorative device

Abstract

This laminate body comprises, in the order indicated, a base material, a silver mirror layer, and a light-shielding image layer that shields a part of a region in which the silver mirror layer is provided.

Description

Laminate and decorating device

[0001] The present disclosure relates to a laminate and a decorating device.

[0002] The surface of a molded product may be decorated with a metallic finish for design purposes. Examples of metallic decoration methods include electrolytic plating, vacuum deposition, and hot stamping. Electrolytic plating is widely used to decorate vehicle parts such as bumpers and emblems. For example, a method has been disclosed in which a nickel layer is formed on the surface of a part by electrolytic plating, and then a chromium layer is formed thereon (see, for example, Patent Document 1). There is a demand for adding various designs to these metallic parts. Examples of designs include a surface that is normally entirely metallic, but can display a design image using a backlight.

[0003] Meanwhile, millimeter-wave transparency has been required for automobile emblems in recent years. Recent advances in automobile safety devices have been remarkable, and automatic collision avoidance systems, for example, have become commonplace. Automatic collision avoidance systems automatically apply the brakes using image data from an onboard camera and relative distance information from a millimeter-wave radar to an object. The millimeter-wave radar transceiver that constitutes the automatic collision avoidance system is preferably located at the front center of the automobile. The automobile emblem is generally located at the front center of the automobile. Therefore, it is desirable to locate the millimeter-wave radar transceiver behind the automobile emblem. Therefore, automobile emblems that have the millimeter-wave radar transceiver located behind them are required to be millimeter-wave transparent.

[0004] Furthermore, with growing interest in energy conservation, resource conservation, safety, and health, the use of millimeter wave sensors inside homes and other buildings is also attracting attention. In addition to the conventional functions of infrared motion sensors, which detect people, hands, etc. and automatically switch on, millimeter wave sensors can also detect the movement of people and other objects, making it possible to detect falls and monitor health conditions such as pulse and respiratory rate. Until now, sensor covers for motion sensors have mainly been flat or curved plastic products, which lacked design and aesthetic appeal.

[0005] JP 2016-216783 A

[0006] Metal plating layers commonly used for metallic decorations have poor transmittance for millimeter waves. Therefore, although metal-plated emblems and sensor covers have excellent metallic finishes, they cannot be used for applications where a millimeter-wave radar transceiver or millimeter-wave sensor is placed behind them. Furthermore, because metal plating layers also have poor transmittance for visible light, designs such as displaying images using a backlight cannot be added. The present disclosure has been made in consideration of the above circumstances, and aims to provide a laminate and a decoration device that have excellent metallic finishes and millimeter-wave transmittance and are capable of displaying images using a backlight.

[0007] Specific means for achieving the above object are as follows: <1> A laminate comprising, in this order, a substrate, a silver mirror layer, and a light-shielding image layer that shields a part of the area where the silver mirror layer is provided. <2> An L measured from the side opposite to the side where the light-shielding image layer is provided. ＊ a ＊ b ＊ L in color system ＊ <3> The laminate according to <1>, wherein the surface resistivity of the silver mirror layer is 10 ４The laminate according to <1> or <2>, having a spectral transmittance of Ω / □ or more. <4> The laminate according to any one of <1> to <3>, having a spectral transmittance of 1% or more at a wavelength of 400 nm in a region not shielded by the light-shielding image layer. <5> The laminate according to any one of <1> to <4>, having a spectral transmittance of 0.05% or more at wavelengths from 500 nm to 600 nm in a region not shielded by the light-shielding image layer. <6> The laminate according to any one of <1> to <5>, having a spectral transmittance of 1% or more at a wavelength of 700 nm in a region not shielded by the light-shielding image layer. <7> The laminate according to any one of <1> to <6>, having a spectral transmittance of 5% or more at a wavelength of 800 nm in a region not shielded by the light-shielding image layer. <8> The laminate according to any one of <1> to <7>, which is a cover for a millimeter-wave sensor or an automobile emblem. <9> A decorating device comprising the laminate according to any one of <1> to <8> and a light source disposed on the light-shielding image layer side. <10> The decorating device according to <9>, further comprising a millimeter-wave radar transceiver or a millimeter-wave sensor disposed on the light-shielding image layer side. <11> The decorating device according to <9> or <10>, further comprising an infrared sensor disposed on the light-shielding image layer side.

[0008] According to the present disclosure, a laminate and a decorating device are provided that have an excellent metallic appearance and millimeter wave transmittance, and are capable of displaying images using a backlight.

[0009] 1 is a schematic cross-sectional view showing an example of a laminate according to the present disclosure;

[0010] Hereinafter, embodiments for carrying out the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments. In the following embodiments, components (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values ​​and their ranges, and do not limit the present disclosure.

[0011] In the present disclosure, numerical ranges indicated using "to" include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in the present disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another staged numerical range. Furthermore, in numerical ranges described in the present disclosure, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples. In the present disclosure, each component may contain multiple corresponding substances. When multiple substances corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple substances present in the composition, unless otherwise specified. In the present disclosure, particles corresponding to each component may include multiple types of particles. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified. In this disclosure, the term "layer" or "film" includes cases where the layer or film is formed over the entire area when the area where the layer or film is present is observed, as well as cases where the layer or film is formed over only a part of the area.

[0012] When embodiments are described with reference to the drawings in this disclosure, the configuration of the embodiment is not limited to the configuration shown in the drawings. Furthermore, the sizes of components in each drawing are conceptual, and the relative size relationships between components are not limited to these. In this disclosure, the surface of the laminate on which the light-shielding image layer is provided is also referred to as the back surface, and the surface opposite to the light-shielding image layer is also referred to as the design surface.

[0013] <Laminate> The laminate of the present disclosure comprises, in this order, a substrate, a silver mirror layer, and a light-shielding image layer that shields a portion of the area where the silver mirror layer is provided. The laminate of the present disclosure has excellent metallic tones and millimeter-wave transmittance, and is capable of displaying images using a visible light backlight. The reason for this is presumed to be as follows: The silver mirror layer formed by the silver mirror reaction has a sea-island structure in which silver particles are scattered like islands. This structure allows millimeter waves to pass through the gaps between the silver particles. This structure also allows transmission of at least a portion of wavelengths in the visible light wavelength range. Therefore, by disposing the light-shielding image layer on the backside facing the backlight, the non-shielding area not shielded by the light-shielding image layer transmits visible light from the backlight, while the shielding area shielded by the light-shielding image layer does not transmit visible light from the backlight. As a result, when observed from the design surface side, an image corresponding to the light-shielding image layer is displayed by the backlight. The light-shielding image in the light-shielding image layer can be changed in design, resulting in excellent design. When the backlight is not irradiated, the area on the design surface where the silver mirror layer is provided appears metallic.

[0014] In the present disclosure, millimeter wave transparency refers to the property of transmitting radio waves of frequencies between 20 GHz and 300 GHz that are generally used in millimeter wave radar transmitters and receivers or millimeter wave sensors. ＊ a ＊ b ＊ L in color system ＊ In the present disclosure, the phrase "capable of displaying an image using a backlight of visible light" means that an image can be displayed using a backlight of at least a part of the wavelength in the wavelength range of visible light.

[0015] Each member used in this disclosure will be described below.

[0016] - Substrate - The material of the substrate is not particularly limited, and inorganic materials such as glass, organic materials such as resins, etc. Examples of resins include thermosetting resins and thermoplastic resins.

[0017] Examples of thermoplastic resins include polyethylene, polypropylene, polycarbonate, polystyrene, polyvinyl chloride, vinyl polymers, polyester, polyamide, ABS resin (acrylonitrile-butadiene-styrene copolymer resin), thermoplastic elastomers, and acrylic resins. These resins may be used alone or in combination of two or more. An example of a combination of two or more resins is polycarbonate / ABS resin.

[0018] Examples of the thermosetting resin include silicone resin, polyurethane resin, polyester resin, melamine resin, epoxy resin, phenol resin, urea resin, etc. These resins may be used alone or in combination of two or more.

[0019] When used for sensor covers for motion sensors, etc., preferred substrate materials include polypropylene, polycarbonate, ABS resin, polycarbonate / ABS, and acrylic resin. Polypropylene has a low specific gravity among resins, is easy to process, has high tensile strength, impact strength, and compressive strength, and is also excellent in weather resistance and heat resistance. ABS resin is relatively easy to apply surface treatments to, among plastic materials, and therefore is a resin that is easy to paint after molding the substrate. It also has excellent chemical resistance and rigidity, as well as excellent impact resistance, heat resistance, and cold resistance. Polycarbonate has high impact resistance among plastic materials, excellent weather resistance and heat resistance, and excellent transparency. Polycarbonate is also easy to process, and is a relatively light and durable material among plastic materials.

[0020] The thickness and shape of the substrate can be appropriately designed depending on the application.

[0021] In order to improve adhesion between the substrate and the silver mirror layer and to smooth the substrate surface, an undercoat layer may be provided on the side of the substrate on which the silver mirror layer is to be formed. The material for the undercoat layer is not particularly limited and can be selected depending on the purpose of the undercoat layer. For example, fluororesin, polyester resin, epoxy resin, melamine resin, silicone resin, acrylic silicone resin, acrylic urethane resin, etc. may be used. These resins may be in the form of a paint to which a solvent or the like has been added.

[0022] The thickness of the undercoat layer is not particularly limited, but from the viewpoint of ensuring a smooth surface, it is preferably about 5 μm to 25 μm.

[0023] In order to improve the adhesion between the undercoat layer and the substrate, a primer layer may be provided between the undercoat layer and the substrate.

[0024] - Silver Mirror Layer - The silver mirror layer contains silver particles (precipitated silver particles) precipitated by a silver mirror reaction. The silver mirror layer has millimeter wave transparency. As described below, millimeter wave transparency can be taken into consideration in terms of the surface resistivity of the silver mirror layer. The silver mirror layer also has visible light transparency, which transmits at least a portion of the wavelengths in the visible light wavelength range. Furthermore, the silver mirror layer may have infrared transparency, which transmits at least a portion of the wavelengths in the infrared wavelength range. As described below, the visible light transparency and infrared transparency may be confirmed as the overall physical properties of the laminate by measuring the spectral transmittance of wavelengths in the visible light range and the infrared range in areas of the laminate that are not shielded by the light-shielding image layer.

[0025] The formation of the silver mirror layer by the silver mirror reaction may be carried out by contacting an aqueous ammoniacal silver nitrate solution with an aqueous reducing agent solution, which causes an oxidation-reduction reaction to produce silver particles and form the silver mirror layer.

[0026] In one embodiment of the present disclosure, the ammoniacal silver nitrate aqueous solution is obtained by dissolving silver nitrate, ammonia, and at least one amine compound selected from the group consisting of amino alcohol compounds, amino acids, and amino acid salts in water. Specific examples of the amine compound include amino alcohol compounds such as monoethanolamine, diethanolamine, diisopropanolamine, triethanolamine, and triisopropanolamine, and amino acids or salts thereof such as glycine, alanine, and sodium glycinate.

[0027] The contents of silver nitrate, ammonia, and amine compound contained in the aqueous ammoniacal silver nitrate solution are not particularly limited.

[0028] The concentration of silver nitrate contained in the ammoniacal silver nitrate aqueous solution is not particularly limited, but from the viewpoint of controlling the reaction rate, it is preferably adjusted to a range of 0.1% by mass to 10% by mass. The pH of the ammoniacal silver nitrate aqueous solution is preferably adjusted to a range of 10 to 13, more preferably 11 to 12.

[0029] In one embodiment of the present disclosure, the aqueous reducing agent solution is obtained by dissolving a reducing agent containing a phenolic compound and a strong alkaline component in water. Examples of phenolic compounds contained in the reducing agent include benzenediol compounds such as hydroquinone, catechol, and resorcinol, with hydroquinone being preferred. The reducing agent may contain only phenolic compounds or a combination of phenolic compounds and compounds other than phenolic compounds. Examples of compounds other than phenolic compounds include hydrazine compounds such as hydrazine sulfate, hydrazine carbonate, and hydrazine hydrate, sulfite compounds such as sodium sulfite, and thiosulfate compounds such as sodium thiosulfate. When the reducing agent contains a phenolic compound and a compound other than phenolic compounds, the proportion of the phenolic compound in the total reducing agent is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more.

[0030] Specific examples of the strong alkaline component contained in the aqueous reducing agent solution include sodium hydroxide and potassium hydroxide.

[0031] The aqueous reducing agent solution may contain the above-mentioned amine compound as needed. The aqueous reducing agent solution may contain a compound containing a formyl group as needed. Specific examples of the compound containing a formyl group include glucose and glyoxal. The contents of the reducing agent, strong alkaline component, amine compound (if needed), and compound containing a formyl group (if needed) contained in the aqueous reducing agent solution are not particularly limited.

[0032] The concentration of the reducing agent contained in the aqueous reducing agent solution is not particularly limited, but is preferably adjusted to a range of 0.1% by mass to 10% by mass from the viewpoint of controlling the reaction rate. The pH of the aqueous reducing agent solution is preferably adjusted to a range of 10 to 13, more preferably 10.5 to 11.5.

[0033] The average primary particle size of the silver particles in the silver mirror layer is preferably 1 nm to 30 nm, more preferably 5 nm to 25 nm, and even more preferably 10 nm to 20 nm. In particular, when the average primary particle size of the silver particles in the silver mirror layer is 15 nm or more, the uniformity of the silver mirror layer is excellent, and the appearance is improved.

[0034] The silver particles in the silver mirror layer may be aggregated to form secondary particles, and the average secondary particle size is preferably 350 nm or less, more preferably 300 nm or less, and even more preferably 250 nm or less.

[0035] The average primary particle size and average secondary particle size of silver particles are determined by measuring the diameters of 50 silver particles using a scanning electron microscope (SEM) image or a transmission electron microscope (TEM) image, and calculating the arithmetic mean.

[0036] The thickness of the silver mirror layer is not particularly limited. From the viewpoint of obtaining a sufficient metallic luster, the thickness of the silver mirror layer is preferably 50 nm or more, and from the viewpoint of obtaining a sufficient millimeter wave transmittance, the thickness of the silver mirror layer is preferably 300 nm or less.

[0037] The surface resistivity of the silver mirror layer is 10 ４ It is preferably 10 Ω / □ or more, ５It is more preferable that the surface resistivity of the silver mirror layer is Ω / □ or more. When the surface resistivity of the silver mirror layer is within the above range, it can be determined that sufficient millimeter wave transmittance has been achieved. There is no particular upper limit for the surface resistivity of the silver mirror layer. The surface resistivity of the silver mirror layer refers to a value measured in accordance with JIS K6911:2006.

[0038] A protective layer may be provided on the surface of the silver mirror layer facing the light-shielding image layer in order to improve the adhesion between the silver mirror layer and the light-shielding image layer and to protect the silver mirror layer. The material of the protective layer is not particularly limited, and can be selected, for example, from the resins mentioned above as the material for the undercoat layer of the substrate. The thickness of the protective layer is not particularly limited, and is preferably, for example, about 2 μm to 20 μm.

[0039] - Light-shielding image layer - The light-shielding image layer is a layer that shields part of the area where the silver mirror layer is provided. The light-shielding image layer may have a light-shielding portion and a non-light-shielding portion. The non-light-shielding portion may be a through space. There are no particular restrictions on the method for forming the light-shielding image layer, and the light-shielding image layer may be formed by attaching a light-shielding sheet with a hollow portion, by using masking tape, or by printing a coating liquid for forming the light-shielding image layer.

[0040] The shape of the image is not particularly limited and may be any of letters, numbers, pictures, etc.

[0041] In the light-shielding portion of the light-shielding image layer, the spectral transmittance at a wavelength of 400 nm in the visible light region is preferably 0.01% or less, the spectral transmittance at wavelengths from 500 nm to 600 nm is preferably 0.01% or less, and the spectral transmittance at a wavelength of 700 nm is preferably 0.01% or less.

[0042] The material of the light-shielding image layer is not particularly limited, and inorganic materials, organic materials such as resins, etc. Examples of resins include thermosetting resins and thermoplastic resins.

[0043] Examples of thermoplastic resins include polycarbonate (PC) resin and polymethyl methacrylate (PMMA). These resins may be used alone or in combination of two or more. Examples of thermosetting resins include epoxy resin and polyurethane resin. These resins may be used alone or in combination of two or more.

[0044] In order to reduce the visible light transmittance of the light-shielding portion, the light-shielding image layer may contain a colorant, such as a pigment.

[0045] The thickness of the light-shielding image layer can be appropriately designed depending on the application.

[0046] -Clear Coat Layer- The laminate may have a clear coat layer on the surface of the design side of the substrate, as necessary. The clear coat layer preferably has transparency to the extent that it does not conceal the metallic luster of the silver mirror layer and transparency to the extent that it does not block millimeter waves, and may be colorless clear (colorless and transparent) or colored color clear (colored and transparent).

[0047] The material for the clear coat layer is not particularly limited, and can be selected from the resins mentioned above as the material for the undercoat layer of the substrate, for example.

[0048] The thickness of the clear coat layer can be appropriately designed depending on the application.

[0049] Fig. 1 shows a schematic cross-sectional view illustrating an example of a laminate of the present disclosure. The laminate 100 in Fig. 1 has, in order from the design surface side, a clear coat layer 10, a substrate 20, a silver mirror layer 30, a protective layer 40, and a light-shielding image layer 50. As described above, a primer layer (not shown) and an undercoat layer (not shown) may be provided between the substrate 20 and the silver mirror layer 30.

[0050] <Physical properties of laminate> In the laminate, the transmission attenuation at 77.0 GHz, which is the millimeter wave region, is preferably 4.0 dB or less, more preferably 3.0 dB or less, and even more preferably 2.0 dB or less. The transmission attenuation of the laminate is measured based on JIS R1679:2007 (Method for measuring radio wave absorption characteristics of radio wave absorbers in the millimeter wave band). A sample is placed between a transmitting antenna and a receiving antenna, and the transmission attenuation is calculated from the transmitted wave (transmission coefficient) obtained by the free space method in which electromagnetic waves are irradiated perpendicularly to the sample. The transmission attenuation can be calculated using the transmission coefficient (absolute value) according to the following formula: Transmission attenuation = 20 log １０ | (Permeability coefficient) |

[0051] In areas of the laminate that are not shielded by the light-shielding image layer, the spectral transmittance at a wavelength of 400 nm in the visible light region is preferably 1% or more, the spectral transmittance at wavelengths from 500 nm to 600 nm is preferably 0.05% or more, and the spectral transmittance at a wavelength of 700 nm is preferably 1% or more. Note that it has been confirmed that even when the spectral transmittance at a wavelength of 580 nm measured by the following method is about 0.1%, sufficient color discrimination is possible by visual inspection.

[0052] In the area of ​​the laminate that is not shielded by the light-shielding image layer, the spectral transmittance at a wavelength of 800 nm in the infrared region is preferably 5% or more, and the spectral transmittance at wavelengths of 900 nm to 1600 nm is preferably 10% or more. If the spectral transmittance at a wavelength of 800 nm is in the above range, the laminate can also be used as a cover for an infrared motion sensor.

[0053] In areas of the laminate that are not shielded by the light-shielding image layer, the spectral reflectance at a wavelength of 400 nm in the visible light region is preferably 40% or more, the spectral reflectance at a wavelength of 500 nm is preferably 60% or more, the spectral reflectance at a wavelength of 600 nm is preferably 50% or more, and the spectral reflectance at wavelengths from 700 nm to 800 nm is preferably 35% or more.

[0054] In the present disclosure, the spectral transmittance and spectral reflectance of the laminate in the infrared to visible wavelength region are measured using an ultraviolet-visible-near infrared (UV-VIS-NIR) spectrophotometer in the atmosphere at 25° C. The spectral reflectance in the wavelength region from 700 nm to 800 nm is the average value of the spectral reflectance in this wavelength region.

[0055] The design surface of the laminate is L ＊ a ＊ b ＊ L in color system ＊ The value is preferably 80 or more, more preferably 82 or more, and even more preferably 83 or more. ＊ a ＊ b ＊ In the color system, L ＊ is an index of brightness, and is a value ranging from 0 (black) to 100 (white). ＊ The larger the value, the higher the brightness of the silver mirror layer and the more excellent the brilliance.

[0056] L ＊ a ＊ b ＊ The color system was standardized by the International Commission on Illumination (CIE) in 1976 and is adopted in JIS Z 8781-4:2013. ＊ a ＊ b ＊ L in color system ＊ is a value measured using an SCI type spectrocolorimeter (for example, CM-2600d manufactured by Konica Minolta).

[0057] <Method for producing laminate> The method for producing the laminate is not particularly limited. In forming a silver mirror layer by silver mirror reaction, the method for bringing an aqueous ammoniacal silver nitrate solution and an aqueous reducing agent solution into contact with each other is not particularly limited, and examples thereof include a method in which these aqueous solutions are applied to the surface of a substrate in a mixed state or in an unmixed state.

[0058] The method for applying the ammoniacal silver nitrate aqueous solution and the reducing agent aqueous solution to the silver mirror reaction-treated surface is not particularly limited. Among these, spray coating is preferred, as it can form a uniform silver mirror layer regardless of the shape of the substrate. Spray coating can be carried out using known means such as an airbrush or a spray gun.

[0059] If necessary, the surface of the substrate may be subjected to a surface activation treatment before the silver mirror layer is formed. In one embodiment of the present disclosure, the surface activation treatment involves applying a surface activation treatment liquid containing an inorganic tin compound to the surface of the substrate. This causes tin to be present on the surface of the substrate. The presence of tin between the silver mirror layer and the substrate tends to improve adhesion between the substrate and the silver particles.

[0060] Examples of inorganic tin compounds contained in the surface activation treatment liquid include tin(II) chloride, tin(II) oxide, and tin(II) sulfate. In addition to the inorganic tin compound, the surface activation treatment liquid may contain hydrogen chloride, hydrogen peroxide, polyhydric alcohol, and the like, as needed. The content of these components contained in the surface activation treatment liquid is not particularly limited.

[0061] The pH of the surface activation treatment solution is preferably adjusted to between 0.5 and 3.0, and more preferably between 0.5 and 1.5.

[0062] Methods for applying the surface activation treatment liquid to the surface of a substrate include a method of immersing the substrate in the surface activation treatment liquid, a method of coating the surface of the substrate with the surface activation treatment liquid, etc. Among these, spray coating is preferred because it can be applied uniformly to any substrate regardless of its shape.

[0063] After the surface activation treatment, it is preferable to remove excess surface activation treatment solution from the surface of the substrate, for example, by rinsing the surface of the substrate with deionized water or purified distilled water.

[0064] If necessary, the surface of the substrate may be pretreated before the silver mirror layer is formed. In one embodiment of the present disclosure, as the pretreatment, a pretreatment liquid such as an aqueous silver nitrate solution is applied to the surface of the substrate after the above-described surface activation treatment. This causes silver to be present on the surface of the substrate. The presence of silver between the silver mirror layer and the substrate tends to facilitate the precipitation of silver particles of uniform size.

[0065] The pH of the pretreatment liquid is preferably adjusted to a range of 4.0 to 8.0, and more preferably to a range of 6.0 to 7.0.

[0066] Methods for applying the pretreatment liquid to the surface of a substrate include a method of immersing the substrate in the pretreatment liquid, a method of coating the surface of the substrate with the pretreatment liquid, etc. Among these, spray coating is preferred because it can apply the pretreatment liquid uniformly regardless of the shape of the substrate.

[0067] If necessary, a passivation treatment may be performed after forming a silver mirror layer on the surface of the substrate. In one embodiment of the present disclosure, the passivation treatment involves contacting the silver mirror layer with a passivation treatment solution, which is an aqueous solution containing a strong alkaline component such as potassium hydroxide and a sulfite such as sodium sulfite. This reduces the reactivity of the silver in the silver mirror layer with residual ions such as chloride ions and sulfide ions. The content of the components contained in the passivation treatment solution is not particularly limited.

[0068] The pH of the inactivation treatment solution is preferably adjusted to between 4.0 and 8.0, more preferably between 7.0 and 8.0.

[0069] Methods for bringing the inactivation treatment liquid into contact with the silver mirror layer include immersing the substrate on which the silver mirror layer has been formed in the inactivation treatment liquid, applying the inactivation treatment liquid to the silver mirror layer, etc. Among these, spray application is preferred because it can apply the inactivation treatment liquid uniformly regardless of the shape of the substrate.

[0070] Before and after the passivation treatment, it is preferable to wash the silver mirror layer with deionized water or purified distilled water.

[0071] <Uses of Laminate> The laminate of the present disclosure has an excellent metallic appearance and excellent millimeter wave transmittance. It is also possible to display images using a backlight. Therefore, it is particularly suitable for use as a cover for various millimeter wave sensors that displays various information. As an automobile part, it is suitable for use as an automobile emblem placed on the front of a millimeter wave radar transmitter / receiver. If the laminate of the present disclosure can transmit at least a portion of the wavelengths in the infrared wavelength range, it can also be used as a cover for an infrared sensor.

[0072] Examples of sensors include sensors that detect human movement and monitor health status, and can be used as covers for indoor and outdoor sensors such as vital signs sensors, security motion sensors, automatic faucet sensors, toilet seat / standby sensors, automatic toilet seat opening / closing sensors, automatic flushing sensors, automatic lighting sensors, elderly care sensors, automatic door sensors, sensor-activated escalator sensors, remote controller sensors, non-contact body temperature sensors, sensor-activated traffic lights sensors, and traffic volume measurement sensors. The detection targets may be other than people, and may include bicycles, automobiles, airplanes, and other transportation vehicles, animals, plants, and merchandise (such as precious metals). Because the exterior is reflective, it may be placed in place of an existing mirror, or it may be placed as an interior or exterior fixture.

[0073] <Decoration Device> The decoration device of the present disclosure includes the laminate of the present disclosure and a light source arranged on the light-shielding image layer side (rear side). When a backlight serving as a light source is arranged on the rear side, opposite the viewing side, of a laminate having a light-shielding image layer, light emitted from the backlight reaches the viewing side, which is the design surface, through the light-shielding image layer. Therefore, when the laminate is observed from the viewing side, an image formed in the non-light-shielding portion of the light-shielding image layer is displayed on the surface of the laminate.

[0074] The type of light source is not particularly limited, and conventionally known light sources can be appropriately selected and used. Examples of light sources include lamp light sources and light-emitting elements. Examples include lamp light sources, incandescent lamps, halogen lamps, discharge lamps, and neon lamps. Examples of light-emitting elements include light-emitting diodes (LEDs), laser diodes (LDs), and organic electroluminescence elements. Among the above, LEDs are preferred from the viewpoints of visibility, ease of dimming, power consumption, lifespan, and the like.

[0075] The wavelength of the light emitted from the light source is not particularly limited and can be selected appropriately. For example, two or more light sources emitting light of different wavelengths may be used to create an illumination device in which light of different colors is observed depending on the location.

[0076] The light source may include a point light source, a surface light source, or two or more point light sources. When the light source includes two or more point light sources, the range of designs for the lighting device can be expanded, and the design tends to be further improved.

[0077] When the light source includes two or more point light sources, the point light sources are preferably arranged in the decoration device appropriately according to the shape of the mounting location of the vehicle, etc., and may be arranged regularly or irregularly. For example, the decoration device may have a plurality of point light sources arranged in a straight line, a curved line, or a combination thereof.

[0078] The laminate of the present disclosure has excellent millimeter-wave transmittance, and therefore, a millimeter-wave radar transceiver or millimeter-wave sensor can be disposed on the light-shielding image layer side (back side) of the laminate. The millimeter-wave radar transceiver can be a typical one used in automatic collision avoidance systems. Examples of millimeter-wave sensors include those described above.

[0079] When the laminate of the present disclosure is capable of transmitting at least part of the wavelength in the infrared wavelength range, an infrared sensor can be further disposed on the light-shielding image layer side (rear side) of the laminate.

[0080] 2 is a schematic cross-sectional view showing an example of a decoration device according to the present disclosure. The decoration device 200 has a light source 110 disposed on the rear surface side opposite the viewing side. The light source 110 may be housed in a housing 120. The housing 120 is preferably light-blocking. A millimeter-wave radar transceiver or a millimeter-wave sensor may be housed in the housing 120 together with the light source 110. Furthermore, an infrared sensor may be housed in the housing 120.

[0081] Hereinafter, the present disclosure will be described based on examples, but the present disclosure is not limited to the following examples.

[0082] Example 1 (1) Preparation of Substrate The surface of a 2 mm thick polycarbonate substrate was wiped with a cloth soaked in isopropyl alcohol to remove oil film, dirt, and dust, and then the substrate was dried.

[0083] (2) Surface Activation Step After the substrate was spray-washed with pure water, a surface activation treatment solution (MSPS-Sa1A, manufactured by Mitsubishi Paper Mills, Ltd.) was spray-coated onto the substrate. The substrate was then spray-washed with pure water. The surface activation treatment solution used was an aqueous solution containing tin(II) chloride, hydrogen chloride, hydrogen peroxide, and a polyhydric alcohol, with a pH of 1.0.

[0084] (3) Pretreatment Step A pretreatment liquid (MSPS-Sa2A manufactured by Mitsubishi Paper Mills Co., Ltd.) was sprayed onto the surface of the substrate after the surface activation treatment. The surface was then spray-washed with pure water. The pretreatment liquid used was a silver nitrate aqueous solution with a pH of 6.8.

[0085] (4) Silver Mirror Layer Formation Step An ammoniacal silver nitrate aqueous solution and a reducing agent aqueous solution were prepared. The ammoniacal silver nitrate aqueous solution was an aqueous solution containing silver nitrate, ammonia, and triethanolamine with a pH of 11.5 (silver nitrate concentration: 0.5% by mass). The reducing agent aqueous solution was an aqueous solution containing hydroquinone, triethanolamine, sodium hydroxide, and an amino alcohol with a pH of 10.8 (hydroquinone concentration: 4.5% by mass).

[0086] The ammoniacal silver nitrate aqueous solution and the reducing agent aqueous solution were simultaneously sprayed from separate airbrushes. The discharge rates of the airbrushes were 1.0 g / 10 seconds to 1.5 g / 10 seconds, respectively. During this process, silver particles precipitated on the surface of the substrate due to the silver mirror reaction, forming a silver mirror layer (thickness: 0.2 μm) with a silver luster. The substrate was then spray-washed with pure water.

[0087] (5) Passivation Treatment Step After the silver mirror layer formation step, the surface of the substrate was sprayed with a passivation treatment solution (MSPS-R1A, manufactured by Mitsubishi Paper Mills, Ltd.). The substrate was then spray-washed with pure water. The passivation treatment solution used was an aqueous solution containing potassium hydroxide and sulfite, with a pH of 7.5.

[0088] (6) Protective Layer Forming Step After the inactivation treatment, an acrylic resin paint was sprayed onto the treated surface.

[0089] (7) Light-shielding Image Layer Forming Step A portion was cut out from a black adhesive sheet for office use, and this was attached onto the silver mirror layer.

[0090] Comparative Example 1 A laminate was produced in the same manner as in Example 1, except that instead of the silver mirror layer, a nickel layer was formed on the surface of the carbonate substrate by electrolytic plating, and a chromium layer was further formed thereon.

[0091] Comparative Example 2 A laminate was produced in the same manner as in Example 1, except that indium was vapor-deposited on the surface of a polycarbonate substrate instead of the silver mirror layer.

[0092] <Evaluation> (1) L ＊ Measurement of L on the design surface of the obtained laminate ＊ a ＊ b ＊ L in color system ＊ The results are shown in Table 1. ＊ The L of the laminate of Comparative Example 1 was 84.83. ＊ The L of the laminate of Comparative Example 2 was 84.98. ＊ was 67.58.

[0093] (2) Measurement of millimeter wave transmission attenuation The attenuation (transmission attenuation) when millimeter waves (77.0 GHz and 79.0 GHz) were transmitted was measured by the following method. The transmission attenuation was calculated from the transmitted wave (transmission coefficient) obtained by the free space method specified in JIS R1679:2007 (Method for measuring radio wave absorption characteristics of radio wave absorbers in the millimeter wave band), in which a sample is placed between a transmitting antenna and a receiving antenna and electromagnetic waves are irradiated perpendicularly to the sample. Here, the transmission attenuation can be calculated using the transmission coefficient (absolute value) from the following formula: Transmission attenuation = 20 log １０ |(Permeability coefficient)| The results are shown in Table 1.

[0094]

[0095] The laminate of Comparative Example 1 did not transmit millimeter waves and measurement was not possible.

[0096] (3) Measurement of spectral transmittance and spectral reflectance in the infrared to ultraviolet region For the millimeter wave transmission attenuation measurement sample, the spectral transmittance and spectral reflectance in the infrared to ultraviolet region were measured using a UV-VIS-NIR spectrophotometer (PerkinElmer, Lambda 950). In addition, for reference, the spectral transmittance and spectral reflectance in the infrared to ultraviolet region were also measured for the polycarbonate (PC) substrate alone used as the substrate of the laminate.

[0097] The measurement conditions were as follows: - Use of an integrating sphere with a diameter of 150 mm - Standard sample (for 100% reflection): Spectralon manufactured by Labsphere - Wavelength range: 190-2500 nm - Wavelength interval: 5 nm steps - Measurement environment: Room temperature (25°C), in the atmosphere

[0098] The laminate of Example 1 had a spectral transmittance of 13.7% at a wavelength of 1000 nm in the infrared region and a spectral transmittance of 0.1% at a wavelength of 600 nm in the visible region. The laminate of Example 1 also had a spectral reflectance of 39.3% at a wavelength of 1000 nm in the infrared region and a spectral reflectance of 52.2% at a wavelength of 600 nm in the visible region.

[0099] (4) Image display Red, blue, and green light were irradiated onto the laminate from the backside. For the laminate of Example 1, an image corresponding to the light-shielding image layer was confirmed when visually observed from the design side, and red, blue, and green were clearly distinguishable from the design side. Since the laminate of Example 1 has an excellent metallic tone, when these colors were irradiated from the backside, metallic red, blue, and green colors were displayed. For the laminate of Comparative Example 1, no image corresponding to the light-shielding image layer was visible when visually observed from the design side. For the laminate of Comparative Example 2, an image corresponding to the light-shielding image layer was confirmed when visually observed from the design side.

[0100] (Discussion) The laminate of Example 1 had the same metallic luster as the laminate of Comparative Example 1 having a conventional plating layer, had millimeter wave transparency, and images were displayed by backlight. The laminate of Comparative Example 1 had an excellent metallic appearance, but did not transmit millimeter waves, and images were not displayed by backlight. The laminate of Comparative Example 2 transmitted millimeter waves and displayed images by backlight, but had an inferior metallic appearance.

[0101] The disclosure of Japanese Patent Application No. 2024-050257 is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

[0102] 10 Clear coat layer, 20 Base material, 30 Silver mirror layer, 40 Protective layer, 50 Light-shielding image layer, Laminate 100, Light source 110, Housing 120, Decorating device 200

Claims

1. A laminate comprising, in this order, a substrate, a silver mirror layer, and a light-shielding image layer that shields a portion of the area where the silver mirror layer is provided.

2. L measured from the side opposite to the side on which the light-shielding image layer is provided ＊ a ＊ b ＊ L in color system ＊ The laminate according to claim 1, wherein the tensile strength is 80 or more.

3. The surface resistivity of the silver mirror layer is 10 ４ The laminate according to claim 1 or 2, having a resistance of Ω / □ or more.

4. The laminate according to claim 1 or 2, wherein the spectral transmittance at a wavelength of 400 nm in the area not shielded by the light-shielding image layer is 1% or more.

5. The laminate according to claim 1 or 2, wherein the spectral transmittance in the wavelength range of 500 nm to 600 nm in the area not shielded by the light-shielding image layer is 0.05% or more.

6. The laminate according to claim 1 or 2, wherein the spectral transmittance at a wavelength of 700 nm in the area not shielded by the light-shielding image layer is 1% or more.

7. The laminate according to claim 1 or 2, wherein the spectral transmittance at a wavelength of 800 nm in the area not shielded by the light-shielding image layer is 5% or more.

8. The laminate according to claim 1 or 2, which is a cover for a millimeter wave sensor or an automobile emblem.

9. A decorating device comprising the laminate according to claim 1 or 2 and a light source disposed on the side of the light-shielding image layer.

10. The decorating device according to claim 9, further comprising a millimeter wave radar transceiver or a millimeter wave sensor disposed on the light-shielding image layer side.

11. The decorating device according to claim 9, further comprising an infrared sensor disposed on the light-shielding image layer side.