Laminate

Abstract

A laminate including a base material and a silver particle layer provided on the base material, the silver particles in the silver particle layer having a radio wave-transmitting layer on the surface.

Description

Technical Field

[0001] The present disclosure relates to a laminated body. Background Art

[0002] In recent years, safety devices have been significantly improved in automobiles, and automatic collision avoidance systems, for example, have become increasingly common.

[0003] The automatic collision avoidance system is a system that automatically applies brakes using image data from an on-vehicle camera and information about the relative distance to an object obtained by a millimeter-wave radar.

[0004] The transceiver of the millimeter wave radar constituting the automatic collision avoidance system is preferably arranged in the front center of the car. The car logo is usually arranged in the front center of the car. Therefore, it is desirable to arrange the transceiver of the millimeter wave radar behind the car logo.

[0005] Automobile emblems are generally obtained by forming a metal film for expressing metallic luster on a substrate such as resin. For example, Japanese Patent Application Laid-Open No. 2003-019765 describes a method of forming a metal film on a substrate by a silver mirror reaction. Summary of the invention

[0006] Problems to be solved by the invention

[0007] In the invention described in Japanese Patent Application Laid-Open No. 2003-019765, the radio wave transmittance of the metal film for millimeter wave radar or the like has not been studied.

[0008] The present disclosure is an invention made in view of the above circumstances, and an object of the present invention is to provide a laminate having a metallic luster and excellent radio wave transmittance.

[0009] Methods for solving problems

[0010] The specific method for achieving the above-mentioned subject is as follows.

[0011] <1> A laminate comprising a substrate and a silver particle layer comprising silver particles provided on the substrate,

[0012] The silver particles have a radio wave transmission layer on the surface.

[0013] <2> The laminate according to <1>, wherein the radio wave transmitting layer is an organic layer.

[0014] <3> The laminate according to <1> or <2>, wherein the silver particles include secondary particles, and the radio wave transmission layer is provided on the surface of the silver particles which are primary particles.

[0015] <4> The laminate according to any one of <1> to <3>, wherein the radio wave transmission layer is a millimeter wave transmission layer.

[0016] <5> The laminate according to any one of <1> to <4>, wherein the radio wave transmitting layer is a layer that transmits at least a portion of wavelengths in a wavelength range from infrared light to visible light.

[0017] <6> The laminate according to any one of <1> to <5>, which is an automobile part.

[0018] Effects of the Invention

[0019] According to the present disclosure, a laminate having a metallic luster and excellent radio wave transmittance can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a scanning transmission electron microscope (STEM) photograph of the silver particle layer obtained in Example.

[0021] Figure 2 This is a transmission electron microscope-energy dispersive X-ray spectroscopy (TEM-EDX) image of the silver particle layer obtained in the example.

[0022] Figure 3 This is a diagram for explaining a component of the front part of a car to which the laminated body of the present disclosure can be applied.

[0023] Figure 4 The diagrams illustrate components from the side to the rear of an automobile to which the laminated body of the present disclosure can be applied.

[0024] Figure 5 The diagrams are for explaining parts of an interior part of an automobile to which the laminated body of the present disclosure can be applied.

[0025] Figure 6 These are the spectral transmittance spectra of the laminate A and the polycarbonate substrate monomer B produced in the examples in the infrared to ultraviolet regions.

[0026] Figure 7 These are spectral reflectance spectra of the laminate A and the polycarbonate substrate monomer B produced in Examples in the infrared to ultraviolet regions. DETAILED DESCRIPTION

[0027] Hereinafter, the method for implementing the present disclosure is described in detail. However, the present disclosure is not limited to the following embodiments. In the following embodiments, its constituent elements (including element steps, etc.) are not necessary except for the cases specifically indicated. The same is true for numerical values ​​and their ranges, which do not limit the present disclosure.

[0028] In the present disclosure, a numerical range expressed using "to" includes the numerical values ​​described before and after "to" as a minimum value and a maximum value, respectively.

[0029] In the numerical range recorded in stages in the present disclosure, the upper limit or lower limit recorded in one numerical range can be replaced by the upper limit or lower limit of the numerical range recorded in other stages. In addition, in the numerical range recorded in the present disclosure, the upper limit or lower limit of its numerical range can also be replaced by the value shown in the embodiment.

[0030] In the present disclosure, each component may contain a plurality of substances corresponding to each component. When a plurality of substances corresponding to each component are present in the composition, the content or content of each component refers to the total content or content of the plurality of substances present in the composition unless otherwise specified.

[0031] In the present disclosure, particles corresponding to each component may include multiple types of particles. When multiple types of particles corresponding to each component exist in the composition, the particle size of each component refers to the value for the mixture of the multiple types of particles present in the composition unless otherwise specified.

[0032] In the present disclosure, the term "layer" or "film" includes a case where, when a region where the layer or film exists is observed, the layer or film is formed on the entire region and a case where the layer or film is formed on only a part of the region.

[0033] <Laminated body>

[0034] The laminated body disclosed in the present invention includes a substrate and a silver particle layer including silver particles provided on the substrate, wherein the silver particles have a radio wave transmission layer on the surface.

[0035] The laminated body of the present disclosure has a metallic luster and is excellent in radio wave transmittance. The reason for this is not clear, but it can be inferred as follows.

[0036] The silver particles in the silver particle layer are easy to condense, and at this time, the radio waves do not penetrate or are difficult to penetrate the gaps between the silver particles. Therefore, in the present disclosure, a radio wave transmission layer is provided on the surface of the silver particles. It is believed that due to the presence of the radio wave transmission layer, gaps are provided between the silver particles, and the radio waves penetrate the gaps. If silver particles having a radio wave transmission layer on the surface are used, the radio waves can be penetrated even if the filling property of the silver particles is improved, so the filling property of the silver particles can be improved, and the metallic luster is excellent.

[0037] Hereinafter, each member used in the present disclosure will be described.

[0038] -Base Material-

[0039] The material of the substrate is not particularly limited, and inorganic materials such as glass, organic materials such as resins, etc. can be used. Examples of the resin include thermosetting resins and thermoplastic resins.

[0040] Examples of thermoplastic resins include polyethylene, polypropylene, polycarbonate, polystyrene, polyvinyl chloride, vinyl polymers, polyesters, polyamides, ABS resins (acrylonitrile-butadiene-styrene copolymer resins), polyesters, thermoplastic elastomers, acrylic resins, etc. These resins may be used alone or in combination of two or more. Examples of combinations of two or more include polycarbonate / ABS resins, etc.

[0041] Examples of the thermosetting resin include silicone resins, polyurethane resins, polyester resins, melamine resins, epoxy resins, phenolic resins, and urea resins.

[0042] When the laminate is used for automobile parts such as logos, polypropylene, polycarbonate, ABS resin, polycarbonate / ABS, acrylic resin, etc. are preferably used as the material of the substrate. Polypropylene has a light specific gravity among resins, is easy to process, has high tensile strength, impact strength and compression strength, and is also excellent in weather resistance and heat resistance. ABS resin is easier to implement surface treatment among plastic materials, so it is a resin that is easy to implement coating after the substrate is formed, has excellent chemical resistance and rigidity, and is also very excellent in impact resistance, heat resistance and cold resistance. Polycarbonate has high impact resistance among plastic materials, is also excellent in weather resistance and heat resistance, and is also very excellent in transparency. In addition, polycarbonate is also easy to process and is a lighter and more durable material among plastic materials.

[0043] The substrate may be provided with a primer layer for the purpose of improving the adhesion between the substrate and the silver particle layer, smoothing the surface of the substrate, and the like.

[0044] The material of the primer layer is not particularly limited and can be selected according to the purpose of the primer layer. For example, fluororesins, polyester resins, epoxy resins, melamine resins, silicone resins, acrylic silicone resins, acrylic urethane resins, etc. can be used. These resins can also be in the form of coatings with solvents added.

[0045] The thickness of the primer layer is not particularly limited, but is preferably about 5 μm to 25 μm from the viewpoint of ensuring a smooth surface.

[0046] In order to improve the adhesion between the primer layer and the substrate, a primer layer may be provided between the primer layer and the substrate.

[0047] The thickness of the substrate can be appropriately designed according to the application of the laminate. The shape of the substrate is not particularly limited.

[0048] -Silver particle layer-

[0049] The silver particle layer includes silver particles having an electric wave transmission layer on the surface. The silver particle layer may be a layer formed by a silver mirror reaction. In addition, the silver particles contained in the silver particle layer may also include silver particles precipitated by the silver mirror reaction (precipitated silver particles). Furthermore, the silver particle layer may also present a sea island structure in which silver particles are dispersed in an island shape.

[0050] The silver particle layer can be formed by the silver mirror reaction by bringing an aqueous ammoniacal silver nitrate solution into contact with an aqueous reducing agent solution, thereby causing an oxidation-reduction reaction to generate silver particles and form the silver particle layer.

[0051] 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.

[0052] Specific examples of the amine compound include amino alcohol compounds such as monoethanolamine, diethanolamine, diisopropanolamine, triethanolamine, and triisopropanolamine; amino acids such as glycine, alanine, and sodium glycinate; and salts thereof.

[0053] The contents of silver nitrate, ammonia, and the amine compound contained in the aqueous ammoniacal silver nitrate solution are not particularly limited.

[0054] The concentration of silver nitrate contained in the aqueous ammoniacal silver nitrate solution is not particularly limited, but is preferably adjusted within a range of 0.1% by mass to 10% by mass from the viewpoint of controlling the reaction rate.

[0055] The pH of the ammoniacal silver nitrate aqueous solution is preferably adjusted to between 10 and 13, and more preferably between 11 and 12.

[0056] In one embodiment of the present disclosure, the reducing agent aqueous solution is obtained by dissolving a reducing agent including a phenol compound and a strong base component in water.

[0057] Examples of the phenol compound contained in the reducing agent include benzene glycol compounds such as hydroquinone, catechol, and resorcinol, and among them, hydroquinone is preferred.

[0058] The reducing agent may be a phenol compound alone or a combination of a phenol compound and a compound other than the phenol compound. Examples of the compound other than the phenol compound 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.

[0059] When the reducing agent contains a phenol compound and a compound other than the phenol compound, the proportion of the phenol compound is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 90% by mass or more of the entire reducing agent.

[0060] Specific examples of the strong base component contained in the reducing agent aqueous solution include sodium hydroxide and potassium hydroxide.

[0061] The reducing agent aqueous solution may contain the above-mentioned amine compound as necessary.

[0062] The reducing agent aqueous solution may contain a compound containing a formyl group as required. Specific examples of the compound containing a formyl group include glucose, glyoxal, and the like.

[0063] The content of the reducing agent, the strong base component, the amine compound contained as needed, and the compound containing a formyl group contained as needed in the reducing agent aqueous solution is not particularly limited.

[0064] The concentration of the reducing agent contained in the aqueous reducing agent solution is not particularly limited, but is preferably adjusted within a range of 0.1% by mass to 10% by mass from the viewpoint of controlling the reaction rate.

[0065] The pH of the reducing agent aqueous solution is preferably adjusted to between 10 and 13, and more preferably between 10.5 and 11.5.

[0066] The average primary particle size of the silver particles in the silver particle layer is preferably 1 nm to 30 nm, more preferably 5 nm to 25 nm, and further preferably 10 nm to 20 nm. If the average primary particle size of the silver particles in the silver particle layer is 15 nm or more, the homogeneity of the silver particle layer is better and the appearance is improved.

[0067] The silver particles in the silver particle layer may also aggregate to form secondary particles, and the average secondary particle size is preferably 350 nm or less, more preferably 300 nm or less, and further preferably 250 nm or less.

[0068] The average primary particle size and the average secondary particle size of the silver particles are obtained by measuring the diameters of 50 silver particles from a scanning microscope (SEM) image or a transmission electron microscope (TEM) image and calculating the arithmetic average thereof.

[0069] The radio wave transmission layer arranged on the surface of the silver particles is not limited as long as it is a layer that transmits radio waves. As radio waves, millimeter waves, microwaves, etc. can be listed, and the radio wave transmission layer is preferably a millimeter wave transmission layer that transmits millimeter waves. In addition, the radio wave transmission layer is preferably a layer that transmits at least a portion of the wavelength in the wavelength region from infrared to visible light.

[0070] As the radio wave transmitting layer, an organic layer may be mentioned.

[0071] The organic layer may be composed of a reducing agent used in the silver mirror reaction, a compound derived from the reducing agent, or a combination thereof. For example, when hydroquinone is used as the reducing agent, the organic layer may be composed of hydroquinone, benzoquinone obtained by oxidation of hydroquinone, or a combination of hydroquinone and benzoquinone.

[0072] The average thickness of the radio wave transmission layer is preferably 20nm to 400nm, more preferably 50nm to 400nm, further preferably 70nm to 350nm, and particularly preferably 100nm to 250nm. If the average thickness of the radio wave transmission layer is less than or equal to 400nm, the radio wave transmittance is excellent, and if it is greater than or equal to 20nm, the homogeneity of the silver particle layer is excellent and the appearance is improved.

[0073] The average thickness of the radio wave transmitting layer is obtained by measuring the thickness of 50 locations of the radio wave transmitting layer based on a scanning transmission electron microscope (STEM) image or a transmission electron microscope-energy dispersive X-ray spectroscopy (TEM-EDX) image and calculating the arithmetic average thereof.

[0074] When silver particles aggregate to form secondary particles, it is preferred that a radio wave transmission layer is provided on the surface of the silver particles of the primary particles. If a radio wave transmission layer is provided on the surface of the silver particles of the primary particles, even if the silver particles form secondary particles, gaps can be provided between the primary particles due to the presence of the radio wave transmission layer, and radio waves can pass through the gaps, so that radio wave transmittance is excellent.

[0075] The radio wave transmission layer may be provided on the entire surface of the silver particles or may be provided partially. In addition, the radio wave transmission layer may be an aggregate of granular materials.

[0076] The thickness of the silver particle layer formed on the substrate is not particularly limited. From the perspective of obtaining sufficient metallic luster, the thickness of the silver particle layer is preferably greater than or equal to 50 nm, and from the perspective of obtaining sufficient millimeter wave transmittance, the thickness of the silver particle layer is preferably less than or equal to 300 nm.

[0077] When observing the cross section of the silver particle layer in the thickness direction, the proportion of silver particles in the silver particle layer is preferably less than or equal to 95%. If the proportion of silver particles in the silver particle layer is less than or equal to 95%, there is a tendency for the transmittance of millimeter waves to be further improved. From the viewpoint of obtaining sufficient metallic luster, the proportion of silver particles in the silver particle layer is preferably greater than or equal to 80%.

[0078] The ratio of the silver particles in the silver particle layer is a value measured as follows.

[0079] For the cross section of the silver particle layer in the laminate in the thickness direction, a transmission electron microscope photograph is taken at a magnification of 300,000 times. For the obtained electron microscope photograph, a central line passing through the center of the silver particle layer in the thickness direction is determined. Next, the length of the portion where the central line overlaps with the silver particles is calculated. The percentage of the value obtained by dividing the length of the portion where the central line overlaps with the silver particles by the length of the entire central line is defined as the proportion of the silver particles in the silver particle layer.

[0080] The surface resistivity of the silver particle layer is preferably greater than or equal to 10 5 Ω / □, more preferably greater than or equal to 10 7 Ω / □. If the surface resistivity of the silver particle layer is within the above range, it can be determined that sufficient millimeter wave transmittance is achieved. The upper limit of the surface resistivity of the silver particle layer is not particularly limited.

[0081] The surface resistivity of the silver particle layer refers to a value measured in accordance with JIS K6911:2006.

[0082] -Top Coating-

[0083] The laminate may have layers other than the substrate and the silver particle layer as required. For example, a top coat layer may be provided on the silver particle layer for the purpose of protecting the silver particle layer.

[0084] The top coat layer preferably has a degree of transparency not to obscure the metallic luster of the silver particle layer and a degree of transparency not to shield millimeter waves, and may be colorless and transparent (colorless transparent) or colored and transparent (colored transparent).

[0085] The material of the top coat layer is not particularly limited, and can be selected, for example, from the above-mentioned resins as the base material of the primer layer.

[0086] The thickness of the top coating layer is not particularly limited, but is preferably about 20 μm to 40 μm. If the thickness of the top coating layer is greater than or equal to 20 μm, there is a tendency to be able to fully protect the silver particle layer, and if it is less than or equal to 40 μm, there is a tendency that cracking, peeling, poor adhesion, etc. caused by changes over time are not easily generated.

[0087] <Physical properties of laminated body>

[0088] The transmission attenuation of the laminate at 77.0 GHz, which is a millimeter wave region, is preferably 3.0 dB or less, more preferably 2.0 dB or less, and further preferably 1.0 dB or less.

[0089] The transmission attenuation of the laminate can be measured based on JIS R1679:2007 (Method for measuring the radio wave absorption characteristics of radio wave absorbers in the millimeter wave band). It is calculated from the transmission wave (transmission coefficient) obtained by the free space method in which a sample is placed between a transmitting antenna and a receiving antenna and electromagnetic waves are irradiated vertically to the sample. The transmission attenuation can be calculated using the transmission coefficient (absolute value) by the following formula.

[0090] Transmission attenuation = 20log 10 |(Transmittance coefficient)|

[0091] The spectral transmittance at a wavelength of 800 nm, which is an infrared region, is preferably 5% or more, and the spectral transmittance at a wavelength of 900 nm to 1600 nm is preferably 10% or more.

[0092] The spectral transmittance at a wavelength of 400 nm in the visible light region is preferably greater than or equal to 1%, the spectral transmittance at a wavelength of 500 nm to 600 nm is preferably greater than or equal to 0.05%, and the spectral transmittance at a wavelength of 700 nm is preferably greater than or equal to 1%.

[0093] It was confirmed that the color can be sufficiently recognized by visual observation even when the spectral transmittance at a wavelength of 580 nm in the measurement method described below is approximately 0.1%.

[0094] The spectral reflectivity at a wavelength of 400nm in the visible light region is preferably greater than or equal to 40%, the spectral reflectivity at a wavelength of 500nm is preferably greater than or equal to 60%, the spectral reflectivity at a wavelength of 600nm is preferably greater than or equal to 50%, and the spectral reflectivity at wavelengths from 700nm to 800nm ​​is preferably greater than or equal to 35%.

[0095] The spectral transmittance and spectral reflectance of the laminate in the wavelength range from infrared to visible light were measured at 25° C. in the air using an ultraviolet-visible-near-infrared (UV-VIS-NIR) spectrophotometer.

[0096] <Method for producing laminate>

[0097] The method for producing the laminate is not particularly limited. Hereinafter, a method for forming a silver particle layer by a silver mirror reaction will be described.

[0098] When the silver particle layer is formed by the silver mirror reaction, the method of contacting the aqueous ammoniacal silver nitrate solution with the aqueous reducing agent solution is not particularly limited, and examples thereof include a method of supplying the aqueous solutions thereof to the substrate surface in a mixed state or an unmixed state.

[0099] There is no particular limitation on the method of supplying the ammoniacal silver nitrate aqueous solution and the reducing agent aqueous solution to the reaction treated surface of the silver mirror. Among them, it is preferred to spray without picking the shape of the substrate and to form a uniform silver particle layer. Spraying can be carried out using a known method such as an airbrush or a spray gun.

[0100] When the radio wave transmission layer is composed of a reducing agent, a compound derived from a reducing agent, or a combination thereof, the spraying is preferably performed by the following method from the viewpoint of making the radio wave transmission layer more reliably present on the surface of the silver particles.

[0101] Different air brushes are used for the ammoniacal silver nitrate aqueous solution and the reducing agent aqueous solution. Then, the position and discharge direction of the air brush are fixed, and the substrate is moved in one direction to spray the entire surface of the substrate. It is preferred to adjust so that the spraying position of the ammoniacal silver nitrate aqueous solution discharged from different air brushes overlaps with the spraying position of the reducing agent aqueous solution.

[0102] Since the discharge conditions of each liquid are constant by fixing the position and discharge direction of the air brush, the radio wave transmission layer can be homogeneously and reliably present on the surface of the silver particles. The method of moving the substrate is not particularly limited, and the substrate can be rotated or slid. In addition, in this method, the spraying from the air brush and the movement of the substrate can be automated.

[0103] The discharge amount of each liquid from the air brush can be set to, for example, 1 g / 10 sec to 10 g / 10 sec, and preferably 4 g / 10 sec to 8 g / 10 sec.

[0104] If necessary, the surface of the substrate may be subjected to a surface activation treatment before forming the silver particle layer.

[0105] In one embodiment of the present disclosure, as a surface activation treatment, a surface activation treatment liquid containing an inorganic tin compound is supplied to the surface of the substrate. Thus, tin is present on the surface of the substrate. The presence of tin between the silver particle layer and the substrate tends to improve the adhesion between the substrate and the silver particles.

[0106] Examples of the inorganic tin compound contained in the surface activation treatment liquid include inorganic tin compounds such as tin (II) chloride, tin (II) oxide, and tin (II) sulfate.

[0107] The surface activation treatment liquid may contain hydrogen chloride, hydrogen peroxide, polyol, etc. in addition to the inorganic tin compound as needed.

[0108] The content of these components contained in the surface activation treatment liquid is not particularly limited.

[0109] The pH of the surface activation treatment solution is preferably adjusted to between 0.5 and 3.0, and more preferably adjusted to between 0.5 and 1.5.

[0110] Examples of methods for supplying the surface activation treatment liquid to the substrate surface include a method of immersing the substrate in the surface activation treatment liquid, a method of coating the surface activation treatment liquid on the substrate surface, etc. Among them, spraying is preferred because it can be supplied uniformly regardless of the substrate shape.

[0111] It is preferred that after the surface activation treatment, the excess surface activation treatment liquid adhering to the surface of the substrate is removed. For example, it is preferred that the substrate surface be cleaned using deionized water or purified distilled water.

[0112] If necessary, the surface of the substrate may be pretreated before forming the silver particle layer.

[0113] In one embodiment of the present disclosure, as a pretreatment, a pretreatment liquid such as a silver nitrate aqueous solution is supplied to the surface of the substrate after the surface activation treatment. As a result, silver is present on the surface of the substrate. Since silver exists between the silver particle layer and the substrate, silver particles of uniform size tend to be easily precipitated.

[0114] The pH of the pretreatment liquid is preferably adjusted to between 4.0 and 8.0, more preferably between 6.0 and 7.0.

[0115] Examples of methods for supplying the pretreatment liquid to the substrate surface include a method of immersing the substrate in the pretreatment liquid, a method of coating the substrate surface with the pretreatment liquid, etc. Among these, spray coating is preferred because it can be supplied uniformly regardless of the substrate shape.

[0116] If necessary, after forming the silver particle layer on the surface of the substrate, an inactivation treatment may be performed.

[0117] In one embodiment of the present disclosure, as a deactivation treatment, an aqueous solution containing a strong alkali component such as potassium hydroxide and a sulfite such as sodium sulfite, i.e., a deactivation treatment solution, is brought into contact with the silver particle layer. This can reduce the reactivity of silver in the silver particle layer with residual ions such as chloride ions and sulfide ions.

[0118] The content of the components contained in the inactivation treatment liquid is not particularly limited.

[0119] The pH of the inactivation treatment liquid is preferably adjusted to between 4.0 and 8.0, and more preferably adjusted to between 7.0 and 8.0.

[0120] As a method for bringing the inactivation treatment liquid into contact with the silver particle layer, there can be cited a method of immersing the substrate formed with the silver particle layer in the inactivation treatment liquid, a method of coating the inactivation treatment liquid on the silver particle layer, etc. Among them, spray coating is preferred because it can be coated uniformly regardless of the substrate shape.

[0121] It is preferred that the silver particle layer be washed with deionized water or purified distilled water before and after the inactivation treatment.

[0122] <Application of laminate>

[0123] The laminated body disclosed in the present invention has a metallic luster and excellent millimeter wave transmittance. Therefore, it can be particularly suitable for use as a vehicle component such as a logo. Specifically, when the laminated body is arranged in front of the vehicle body as a vehicle logo, it can realize the function as a logo without interfering with the transmission and reception of the millimeter wave radar by the transceiver of the millimeter wave radar arranged behind the logo.

[0124] In addition, it can also be extended to other interior and exterior accessories in the car. As other interior and exterior accessories in the car, for example, Figure 3 The components of the front part shown in the example, such as Figure 4 The illustrated parts from the side to the rear, and Figure 5 The illustrated interior parts include vehicle surrounding sensor modules such as bumpers, grilles, rear doors, and decorative parts; interior decorative accessories for indoor and outdoor human sensing and life sensing; sensor modules such as side mirrors, door handles, interior mirrors, and lights.

[0125] Example

[0126] Hereinafter, the present disclosure will be described based on examples, but the present disclosure is not limited to the following examples.

[0127] <Example>

[0128] (1) Preparation of substrate

[0129] The surface of a polycarbonate substrate having a thickness of 2 mm was wiped with a rag containing isopropyl alcohol to remove oil film, dirt and dust, and then the substrate was dried.

[0130] (2) Surface activation process

[0131] After the substrate with the primer layer formed thereon was spray-washed with pure water, a surface activation treatment liquid (MSPS-Sa1A manufactured by Mitsubishi Paper Industries, Ltd.) was spray-washed. Then, the substrate was spray-washed with pure water. The surface activation treatment liquid used was an aqueous solution of pH 1.0 containing tin (II) chloride, hydrogen chloride, hydrogen peroxide, and a polyol.

[0132] (3) Pre-treatment process

[0133] A pretreatment liquid (MSPS-Sa2A manufactured by Mitsubishi Paper Industries, Ltd.) was sprayed on the surface of the substrate after the surface activation treatment. Then, the substrate was spray-washed with pure water. The pretreatment liquid used was a silver nitrate aqueous solution with a pH of 6.8.

[0134] (4) Silver particle layer formation step

[0135] An ammoniacal silver nitrate aqueous solution and a reducing agent aqueous solution were prepared. The ammoniacal silver nitrate aqueous solution was an aqueous solution of pH 11.5 containing silver nitrate, ammonia and triethanolamine (silver nitrate concentration: 0.5 mass%). The reducing agent aqueous solution was an aqueous solution of pH 10.8 containing hydroquinone, triethanolamine, sodium hydroxide and amino alcohol (hydroquinone concentration: 4.5 mass%).

[0136] Each air brush is arranged in such a way that an aqueous ammoniacal silver nitrate solution and an aqueous reducing agent solution are sprayed from different air brushes at the same time. The position and discharge direction of each air brush are fixed. The pre-treated substrate is mounted on a rotating support member, and each liquid is sprayed from the air brush toward the substrate while rotating the substrate in the horizontal direction. The rotation speed of the substrate is set to 120 rpm. The discharge amount of the air brush is set to 1.0 g / 10 sec to 1.5 g / 10 sec, respectively. At this time, silver particles are precipitated on the surface of the substrate through the silver mirror reaction, forming a silver particle layer with a silver luster (thickness: 0.2 μm). Then, spray cleaning is performed with pure water.

[0137] (5) Non-activation treatment process

[0138] After the silver particle layer formation step, a deactivation treatment liquid (MSPS-R1A manufactured by Mitsubishi Paper Industries, Ltd.) was sprayed on the substrate surface. Then, pure water was sprayed and washed. The deactivation treatment liquid used was an aqueous solution of pH 7.5 containing potassium hydroxide and sulfite.

[0139] <Comparative Example>

[0140] A silver particle layer (thickness: 0.13 μm) was formed on the substrate in the same manner except that an aqueous solution (pH 10.1) containing hydrazine sulfate was used instead of hydroquinone as the reducing agent aqueous solution.

[0141] <Evaluation>

[0142] (1) Determination of surface resistivity

[0143] The surface resistivity of the silver particle layer of the laminated body prepared in the example and the comparative example was measured by a four-probe method using a low resistivity meter (trade name: LORESTAEP, Dia Instruments). The surface resistivity of the silver particle layer in the example was 5.08E05Ω / □, and the surface resistivity of the silver particle layer in the comparative example was 4.28E00Ω / □.

[0144] In the comparative example, it is estimated from the value of the surface resistivity that no radio wave transmission layer is formed on the surface of the silver particles.

[0145] (2) Electron microscope observation

[0146] The silver particle layer of the example was observed with an electron microscope. Figure 1 This is a photograph taken using a scanning transmission electron microscope (STEM) (manufactured by JEOL Ltd., JEM-2100F). Figure 2 This is an image obtained using transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDX).

[0147] like Figure 1 and Figure 2As shown, it was confirmed that the silver particles of the examples had an organic layer on the surface. The average thickness of the organic layer was 25 nm.

[0148] (3) Appearance observation

[0149] The appearance of the samples obtained in the examples was observed and the metallic gloss was evaluated. The metallic gloss of the examples and comparative examples was excellent.

[0150] (4) Measurement of millimeter wave transmission attenuation

[0151] A top coating remover M for MSPS, a top coating thinner P-7 for MSPS, and a top coating curing agent W for MSPS manufactured by Ohashi Chemical Industry Co., Ltd. were mixed at a ratio of 20:20:5 (parts by mass) to prepare a top coating composition.

[0152] This composition was spray-coated on the silver particle layer of the samples of Examples and Comparative Examples to form a top coat layer having a thickness of 25 μm.

[0153] The attenuation (transmission attenuation) of the laminate having the top coating layer formed thereon when a millimeter wave (77.0125 GHz) is transmitted therethrough is measured by the following method.

[0154] The transmission attenuation is calculated based on the transmitted wave (transmission coefficient), which is 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 the transmitting antenna and the receiving antenna and electromagnetic waves are vertically irradiated on the sample.

[0155] Here, the transmission attenuation amount can be calculated by the following formula using the transmission coefficient (absolute value).

[0156] Transmission attenuation = 20log 10 |(Transmittance coefficient)|

[0157] The transmission attenuation of the laminated body of the example was 0.67 dB, and the transmission attenuation of the laminated body of the comparative example was 48.32 dB.

[0158] (5) Measurement of spectral transmittance and spectral reflectance in the infrared to ultraviolet range

[0159] The spectral transmittance and spectral reflectance of the sample for measuring the millimeter wave transmission attenuation in the infrared to ultraviolet range were measured using a UV-VIS-NIR spectrophotometer (Lambda 950, manufactured by PerkinElmer).

[0160] In addition, as a reference, the spectral transmittance and spectral reflectance in the infrared to ultraviolet range were also measured for a polycarbonate (PC) substrate alone used as a substrate of the laminate.

[0161] The measurement conditions are as follows.

[0162] Use 150mmφ integrating sphere

[0163] · Standard sample (for 100% reflection): Spectralon manufactured by Labsphere

[0164] Wavelength range: 190-2500nm

[0165] Wavelength interval: 5nm step

[0166] ·Measurement environment: room temperature (25°C), in the air

[0167] Figure 6 represents the spectral transmittance spectrum, Figure 7 Represents the spectral reflectance spectrum.

[0168] The spectral transmittance at a wavelength of 1000 nm in the infrared region is 13.7%, and the spectral transmittance at a wavelength of 600 nm in the visible region is 0.1%.

[0169] The spectral reflectance at a wavelength of 1000 nm in the infrared region is 39.3%, and the spectral reflectance at a wavelength of 600 nm in the visible region is 52.2%.

[0170] It should be noted that, for the laminated body of the embodiment, if red, blue, and green light is irradiated from the back side, red, blue, and green can be fully identified by visual inspection from the front side. Since the laminated body of the embodiment has excellent metallic gloss, when these colors are irradiated from the back side, it presents metallic tones and red, blue, and green colors.

[0171] The disclosure of International Application PCT / JP2022 / 023687 is incorporated into this specification by reference in its entirety.

[0172] All documents, patent applications, and technical standards described in this specification are incorporated into this specification to the same extent as if each individual document, patent application, and technical standard was specifically and individually described as being incorporated by reference.

Claims

1. A laminate comprising a substrate and a silver particle layer comprising silver particles disposed on the substrate, The silver particles have a radio wave transmission layer on the surface. 2 . The laminate according to claim 1 , wherein the radio wave transmitting layer is an organic layer. 3 . The laminate according to claim 1 , wherein the silver particles include secondary particles, and the radio wave transmission layer is provided on the surface of the silver particles which are primary particles. 4 . The laminate according to claim 1 , wherein the radio wave transmission layer is a millimeter wave transmission layer. 5 . The laminate according to claim 1 , wherein the radio wave transmitting layer is a layer that transmits at least a part of the wavelength range from infrared light to visible light. 6 . The laminate according to claim 1 , which is an automobile component.

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