Coating agent liquid composition, method for manufacturing laminate, and molded article

Abstract

A coating agent liquid composition used for forming a silver particle layer in combination with an aqueous ammonia silver nitrate solution, the composition containing an additive that satisfies the conditions of a highest occupied molecular orbital (HOMO) energy level of -0.3192 (Hartree) or higher and an adsorption stabilization energy of -13 (kcal / mol) or lower in the calculation of the HOMO energy level and the adsorption stabilization energy.

Description

Coating agent liquid composition, manufacturing method of laminate, and molded article

[0001] The present disclosure relates to a coating agent liquid composition, a method for producing a laminate, and a molded article.

[0002] In recent years, interest in millimeter-wave sensors has been growing. For example, in recent automobiles, the advancement of safety devices has been remarkable, and automatic collision avoidance systems, for example, have become common. Automatic collision avoidance systems automatically apply the brakes using image data from an onboard camera and relative distance information from millimeter-wave radar to an object.

[0003] Furthermore, with growing interest in energy conservation, resource conservation, safety, and health, the use of millimeter wave sensors is also attracting attention inside homes and other buildings. In addition to the conventional function 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.

[0004] When a millimeter wave radar is installed inside a component such as an automobile part, millimeter wave transparency is required. For example, Japanese Patent Application Laid-Open No. 2019-177311 discloses a method for detecting millimeter wave transparency and L ＊ a ＊ b ＊ L in color system ＊ The document describes a millimeter wave transmitting decorative article having a silver mirror film having a reflectivity of 65 or more.

[0005] In order to improve the transmittance of light of at least a portion of the wavelengths in the wavelength range from radio waves such as millimeter waves or infrared rays to visible light, it is desirable to increase the surface resistivity and reduce attenuation of a silver-containing layer such as a silver mirror film. The present disclosure has been made in view of the above circumstances, and aims to provide a coating agent liquid composition capable of forming a silver particle layer having high surface resistivity and low attenuation, as well as a method for producing a laminate and a molded article using this composition.

[0006] Specific means for achieving the above object are as follows. <1> A coating agent liquid composition used in combination with an ammoniacal silver nitrate aqueous solution to form a silver particle layer, the coating agent liquid composition comprising an additive that satisfies the conditions of a HOMO energy level of −0.3192 (Hartree) or more and an adsorption stabilization energy of −13 (kcal / mol) or less in calculations of the highest occupied molecular orbital (HOMO) energy level and the adsorption stabilization energy. <2> The coating agent liquid composition according to <1>, wherein the additive comprises a compound having a ring structure and at least one functional group selected from the group consisting of a hydroxy group, a formyl group, and a carbonyl group. <3> The coating agent liquid composition according to <1>, wherein the L of the silver particle layer is formed by adding an additive to the L of the silver particle layer. ＊ a ＊ b ＊ L in color system ＊ <4> The coating agent liquid composition according to any one of <1> to <3>, wherein the silver particle layer has a millimeter wave transmission attenuation of 4.0 dB or less. <5> The coating agent liquid composition according to <1> or <2>, wherein the silver particle layer has a surface resistivity of 10 ４ <6> A method for producing a laminate according to any one of <1> to <4>, having a resistance to light of 100% or more, the resistance being Ω / □ or more. <6> A method for producing a laminate, comprising a step of forming a silver particle layer on a substrate, the step comprising contacting an ammoniacal silver nitrate aqueous solution with the coating liquid composition according to any one of <1> to <5>. <7> A method for producing a laminate according to <6>, comprising a step of subjecting the surface of the substrate to at least one of surface activation treatment and pretreatment before the step of forming the silver particle layer. <8> A method for producing a laminate according to <6> or <7>, comprising a step of subjecting the surface of the substrate on which the silver particle layer has been formed to a passivation treatment after the step of forming the silver particle layer. <9> A molded article comprising a silver particle layer formed by contacting an ammoniacal silver nitrate aqueous solution with the coating liquid composition according to any one of <1> to <5>. <10> The molded article according to <9>, which is used for an automobile part, an interior / exterior part, or a sensor cover.

[0007] The present disclosure provides a coating liquid composition capable of forming a silver particle layer having high surface resistivity and low attenuation, as well as a method for producing a laminate using this composition and a molded article.

[0008] 1 is a graph showing the HOMO energy level and adsorption stabilization energy of each compound. 2 is a diagram illustrating a part of the front portion of an automobile to which the molded article of the present disclosure can be applied. 3 is a diagram illustrating a part of the side to rear portion of an automobile to which the molded article of the present disclosure can be applied. 4 is a diagram illustrating a part of the interior portion of an automobile to which the molded article of the present disclosure can be applied.

[0009] 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.

[0010] In the present disclosure, the term "process" includes not only processes that are independent of other processes, but also processes that cannot be clearly distinguished from other processes as long as the purpose of the process is achieved. 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 numerical range described in stages. 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 contain multiple types of particles. When a composition contains multiple types of particles corresponding to each component, the particle size of each component refers to the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified. In the present disclosure, the terms "layer" and "film" include 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.

[0011] <Coating Agent Liquid Composition> The coating agent liquid composition of the present disclosure is a coating agent liquid composition used in combination with an ammoniacal silver nitrate aqueous solution to form a silver particle layer, and contains an additive that satisfies the conditions of a HOMO energy level of −0.3192 (Hartree) or higher and an adsorption stabilization energy of −13 (kcal / mol) or lower, in calculations of the highest occupied molecular orbital (HOMO) energy level and the adsorption stabilization energy.

[0012] By using the coating agent liquid composition of the present disclosure in combination with an ammoniacal silver nitrate aqueous solution, it is possible to form a silver particle layer having high surface resistivity and small attenuation.

[0013] Regarding the additive contained in the coating agent liquid composition of the present disclosure, the additive (hereinafter also referred to as "specific additive") satisfies the conditions that, in calculation of the highest occupied molecular orbital (HOMO) energy level and the adsorption stabilization energy, the HOMO energy level is -0.3192 (Hartree) or higher and the adsorption stabilization energy is -13 (kcal / mol) or lower. The higher the HOMO energy level, the more reducing the additive is, and the smaller the adsorption stabilization energy, the more easily the additive is adsorbed.

[0014] The coating agent liquid composition of the present disclosure may or may not contain components other than the specific additive. The coating agent liquid composition of the present disclosure preferably contains components other than the specific additive, and is preferably an aqueous solution containing components other than the specific additive.

[0015] The coating agent liquid composition of the present disclosure may contain a specific additive as a reducing agent, or may be an aqueous reducing agent solution containing the reducing agent.

[0016] The specific additive may have a HOMO energy level of −0.31 (Hartree) or higher, −0.305 (Hartree) or higher, or −0.300 (Hartree) or higher. The specific additive may have a HOMO energy level of −0.20 (Hartree) or lower, −0.26 (Hartree) or lower, −0.28 (Hartree) or lower, −0.29 (Hartree) or lower, or −0.295 (Hartree) or lower.

[0017] The specific additive may have an adsorption stabilization energy of −13.5 (kcal / mol) or less, −14.0 (kcal / mol) or less, or −14.5 (kcal / mol) or less. The specific additive may have an adsorption stabilization energy of −30 (kcal / mol) or more, −25 (kcal / mol) or more, −20 (kcal / mol) or more, or −18 (kcal / mol) or more.

[0018] The specific additive preferably includes a compound having a ring structure and at least one functional group selected from the group consisting of a hydroxy group, a formyl group, and a carbonyl group, and more preferably includes a compound having a ring structure and two functional groups selected from the group consisting of a hydroxy group, a formyl group, and a carbonyl group. When the specific additive includes two or more functional groups, the functional groups may be the same or different. From the viewpoint of water solubility, the specific additive is preferably a compound having one ring structure and at least one functional group selected from the group consisting of a hydroxy group, a formyl group, and a carbonyl group, and more preferably includes a compound having one ring structure and two functional groups selected from the group consisting of a hydroxy group, a formyl group, and a carbonyl group. In the specific additive, the ring structure may be an aromatic ring, and the specific compound may be a compound in which at least one functional group selected from the group consisting of a hydroxy group, a formyl group, and a carbonyl group is bonded to the aromatic ring, or may be a compound in which a hydroxy group is bonded to the aromatic ring. The specific additive may be a compound in which the carbon atoms of the carbonyl group form a ring structure, i.e., a compound in which a carbonyl group is contained in a ring structure, or a compound in which two carbonyl groups are contained in one ring structure. When the specific additive contains a ring structure, at least a portion of the hydrogen atoms bonded to the ring structure may be substituted with a substituent other than a hydroxy group, a formyl group, or a carbonyl group, for example, an alkyl group. The number of other substituents is preferably four or less, and from the viewpoint of water solubility, more preferably two or less, and even more preferably zero.

[0019] The specific additive is not particularly limited, and examples thereof include alcohol compounds such as pyrocatechol, bisphenol A, resorcinol, pyrogallol, 2,3-dimethylhydroquinone, 2,5-dimethylhydroquinone, 2,6-dimethylhydroquinone, trimethylhydroquinone, and tetramethylhydroquinone, and ketone compounds such as benzoquinone, 2,3-dimethylbenzoquinone, 2,5-dimethylbenzoquinone, 2,6-dimethylbenzoquinone, trimethylbenzoquinone, and tetramethylbenzoquinone. Of these, pyrocatechol and pyrogallol are preferred. The specific additive may be used alone or in combination of two or more. For example, a mixture of an alcohol compound and a ketone compound may be used.

[0020] Figure 1 is a graph showing the HOMO energy level and adsorption stabilization energy of each compound. The lower right part of the dotted line in Figure 1 is the region that satisfies the conditions of a HOMO energy level of -0.3192 (Hartree) or higher and an adsorption stabilization energy of -13 (kcal / mol) or lower.

[0021] The specific additive may be a compound other than hydroquinone, and is preferably, for example, one of the compounds mentioned above.

[0022] The coating agent liquid composition of the present disclosure may contain a reducing agent other than the specific additive (another reducing agent). For example, the aforementioned alcohol compound may be used in combination with another reducing agent, or the aforementioned ketone compound may be used in combination with another reducing agent. Examples of the other reducing agent include phenol, o-cresol, m-cresol, p-cresol, tetroquinone, phloroglucinol, hydrazine, quinhydrone, glucose, and ascorbic acid. The other reducing agents may be used alone or in combination of two or more.

[0023] In the coating agent liquid composition of the present disclosure, the content of the specific additive may be 50% by mass to 100% by mass, 70% by mass to 100% by mass, or 90% by mass to 100% by mass, relative to the total amount of the reducing agent.

[0024] In the coating agent liquid composition of the present disclosure, the content of the other reducing agent may be 0% by mass to 50% by mass, 0% by mass to 30% by mass, 0% by mass to 10% by mass, or 0% by mass, relative to the total amount of the reducing agents.

[0025] In one embodiment of the present disclosure, the coating agent liquid composition is obtained by dissolving a reducing agent containing specific additives and a strong alkaline component in water.

[0026] Specific examples of strong alkaline components that can be contained in the coating agent liquid composition include sodium hydroxide and potassium hydroxide.

[0027] The coating agent liquid composition may contain, as necessary, at least one amine compound selected from the group consisting of amino alcohol compounds, amino acids and amino acid salts.

[0028] The contents of the reducing agent, the strong alkaline component which is contained as needed, and the amine compound which is contained as needed, which are contained in the coating agent liquid composition, are not particularly limited.

[0029] The concentration of the reducing agent (preferably the specific additive) contained in the coating agent liquid composition is not particularly limited, and from the viewpoint of controlling the reaction rate, it is preferable to adjust it to a range of 0.1 mass % to 10 mass %.

[0030] <Method for Producing Laminate> The method for producing a laminate according to the present disclosure includes a step of forming a silver particle layer on a substrate (hereinafter, referred to as a silver particle layer forming step), and the step comprises contacting an aqueous ammoniacal silver nitrate solution with the coating agent liquid composition according to the present disclosure.

[0031] Each component used in the method of the present disclosure will be described below.

[0032] -Substrate- 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 resins include thermosetting resins and thermoplastic resins. The resins may be used alone or in combination of two or more types.

[0033] Examples of thermoplastic resins include polyethylene, polypropylene, polycarbonate, polystyrene, polyvinyl chloride, vinyl polymers, polyester, polyamide, ABS resin (acrylonitrile-butadiene-styrene copolymer resin), polyester, and thermoplastic elastomer.

[0034] Examples of the thermosetting resin include silicone resin, polyurethane resin, polyester resin, melamine resin, epoxy resin, phenol resin, and urea resin.

[0035] When the laminate is used for automotive parts such as emblems, polypropylene, polycarbonate, ABS resin, etc. are preferably used as the substrate material. 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 apply painting, etc. to 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 strong material among plastic materials.

[0036] The substrate may have an undercoat layer to improve adhesion between the substrate and the silver particle layer, smooth the substrate surface, etc. 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.

[0037] 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.

[0038] In order to improve the adhesion between the undercoat layer and the substrate body, a primer layer may be provided between the undercoat layer and the substrate body.

[0039] The thickness of the substrate can be appropriately designed depending on the application of the laminate, and the shape of the substrate is not particularly limited.

[0040] -Silver Particle Layer- In the method of the present disclosure, the silver particle layer is formed by contacting an aqueous ammoniacal silver nitrate solution with the coating agent liquid composition.

[0041] 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.

[0042] The contents of silver nitrate, ammonia, and amine compound contained in the aqueous ammoniacal silver nitrate solution are not particularly limited.

[0043] 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.

[0044] Silver particle layer L ＊ a ＊ b ＊ L in color system ＊ is preferably 75 or more. ＊ 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.

[0045] L ＊ a ＊b ＊ In the color system, L ＊ is an index of lightness, and is a numerical value ranging from 0 (black) to 100 (white). ＊ The larger the value of L of the silver particle layer, the higher the lightness of the silver particle layer and the more excellent the brilliance of the silver particle layer. ＊ a ＊ b ＊ L in color system ＊ The value is preferably 77 or greater, more preferably 79 or greater, and even more preferably 82 or greater.

[0046] In the present disclosure, L of the silver particle layer ＊ a ＊ b ＊ L in color system ＊ is a value measured using an SCI type spectrocolorimeter (for example, CM-2600d manufactured by Konica Minolta).

[0047] The attenuation of the silver particle layer is preferably 4.0 dB or less, more preferably 2.0 dB or less. The attenuation of the silver particle layer refers to a value measured in accordance with JIS R1679:2007 (Method for measuring radio wave absorption characteristics of radio wave absorbers in the millimeter wave band), and is the value obtained by subtracting the attenuation of the substrate from the attenuation of the laminate of the base material (e.g., polycarbonate substrate) and the silver particle layer.

[0048] The surface resistivity of the silver particle layer is 10 ４ It is preferably 10 Ω / □ or more, ５ More preferably, it is 10Ω / □ or more. ６ When 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, and may be, for example, 10 １３ Ω / □ or less, １０ Ω / □ or less, ７ From the viewpoint of the balance between the appearance of a laminate, a molded product, etc., including a silver particle layer and millimeter wave transmittance, ４ Ω / □ to 10 ７The surface resistivity of the silver particle layer is a value measured in accordance with JIS K6911:2006.

[0049] The surface resistivity of the silver particle layer is an index of the radio wave transmittance of the silver particle layer, and the higher the surface resistivity, the easier it is for radio waves to transmit through.

[0050] In the present disclosure, the type of radio waves through which the silver particle layer is transparent is not particularly limited and can be selected depending on the application of the laminate. Specific examples of radio waves through which the silver particle layer is transparent include millimeter waves and microwaves, and among these, millimeter waves are preferred. In the present disclosure, millimeter waves refer to radio waves with a frequency of 20 GHz to 300 GHz. The silver particle layer may be transparent to at least a portion of wavelengths in the wavelength range from infrared to visible light.

[0051] (Silver Particle Layer Formation Step) In the silver particle layer formation step, the method for bringing the ammoniacal silver nitrate aqueous solution and the coating agent liquid composition into contact with each other is not particularly limited. For example, a method in which these aqueous solutions are applied to the surface of the substrate in a mixed state or an unmixed state can be mentioned.

[0052] The method for applying the ammoniacal silver nitrate aqueous solution and the coating liquid composition to the silver mirror reaction-treated surface is not particularly limited. Among these, spray application is preferred, as it can form a uniform silver particle layer regardless of the shape of the substrate. Spray application can be carried out using known means such as an airbrush or a spray gun.

[0053] (Surface Activation Treatment Step) If necessary, a surface activation treatment may be performed on the surface of the substrate before the silver particle 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 particle layer and the substrate tends to improve adhesion between the substrate and the silver particles.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] (Pretreatment Step) If necessary, the surface of the substrate may be pretreated before the silver particle layer is formed. In one embodiment of the present disclosure, as a pretreatment, 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 particle layer and the substrate tends to facilitate the precipitation of silver particles of uniform size.

[0059] 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.

[0060] 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.

[0061] (Deactivation Treatment Step) If necessary, after forming a silver particle layer on the surface of a substrate, the surface of the substrate on which the silver particle layer has been formed may be subjected to a deactivation treatment. In one embodiment of the present disclosure, the deactivation treatment involves bringing the silver particle layer into contact with a deactivation 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 silver in the silver particle layer with residual ions such as chloride ions and sulfide ions. The content of the components contained in the deactivation treatment solution is not particularly limited.

[0062] 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.

[0063] Examples of methods for bringing the deactivation treatment liquid into contact with the silver particle layer include a method of immersing a substrate on which a silver particle layer has been formed in the deactivation treatment liquid, a method of applying the deactivation treatment liquid to the silver particle layer, etc. Among these, spray application is preferred because it can apply the deactivation treatment liquid uniformly regardless of the shape of the substrate.

[0064] After forming the silver particle layer on the surface of the substrate and before the passivation treatment, and after the passivation treatment, it is preferable to wash the silver particle layer with deionized water or purified distilled water. After the passivation treatment, the silver particle layer may be dried.

[0065] The thickness of the silver particle layer formed on the substrate is not particularly limited. From the viewpoint of obtaining a sufficient metallic luster, the thickness is preferably 50 nm or more, and from the viewpoint of obtaining sufficient millimeter wave radar transmittance, the thickness is preferably 300 nm or less.

[0066] -Top Coat Layer- The laminate may have a layer other than the substrate and the silver particle layer, as necessary. For example, a top coat layer may be provided on the silver particle layer for the purpose of protecting the silver particle layer. The top coat layer preferably has transparency to the extent that it does not conceal the metallic luster of the silver particle layer and does not block millimeter-wave radar, and may be colorless clear (colorless and transparent) or colored color clear (colored and transparent).

[0067] The material for the top 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.

[0068] The thickness of the top coat layer is not particularly limited, but is preferably about 20 μm to 40 μm. When the thickness of the top coat layer is 20 μm or more, the silver particle layer tends to be sufficiently protected, and when it is 40 μm or less, cracking, peeling, poor adhesion, and the like due to changes over time tend to be less likely to occur.

[0069] (Molded Article) The molded article of the present disclosure includes a silver particle layer formed by contacting an aqueous ammoniacal silver nitrate solution with a coating agent liquid composition. The molded article of the present disclosure may include the laminate described above.

[0070] The molded article of the present disclosure has a silver particle layer with high surface resistivity and low attenuation, and is therefore particularly suitable for use as an automobile part, interior or exterior part, or sensor cover.

[0071] Examples of automotive parts include millimeter-wave-transmitting automotive emblems and other parts. For example, when the laminate is placed in the front of a vehicle body as an automotive emblem, it can function as an emblem without interfering with millimeter-wave radar transmission and reception by a millimeter-wave radar transceiver placed behind the emblem. Examples of other parts include parts in the front portion of the vehicle as shown in FIG. 2 , parts in the side and rear portions of the vehicle as shown in FIG. 3 , and parts inside the vehicle as shown in FIG. 4 . Specific examples of automotive parts include an emblem 102, lamp 104, garnish 106, bumper 108, and grille 110 shown in FIG. 2 ; a lamp 202, tailgate 204, garnish 206, outer mirror 208, door outer handle 210, and bumper 212 shown in FIG. 3 ; and a room lamp 302, roof garnish 304, room mirror 306, instrument panel garnish 308, and door trim 310 shown in FIG. 4 . The automobile part may have a sensing function such as an obstacle sensor, a human sensor, or a vital sign sensor.

[0072] Examples of sensor covers include covers that are transparent to light of at least a portion of the wavelength range from millimeter waves or other radio waves, or infrared to visible light, and have a design. Examples of sensors include millimeter wave sensors and infrared sensors, which may be used to detect human movement, monitor health status, and the like. The sensor cover may be a cover for indoor or outdoor sensors, such as vital signs sensors, security motion sensors, automatic faucet sensors, toilet seat presence / absence 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 light sensors, and traffic volume measurement sensors. The detection target may be something other than a person, such as a bicycle, automobile, or aircraft, an animal, a plant, or a commodity (such as precious metals).

[0073] Hereinafter, the present disclosure will be described based on examples, but the present disclosure is not limited to the following examples.

[0074] <Example 1> (1) Preparation of substrate The surface of a polycarbonate substrate (PC substrate) having a thickness of 2 mm was wiped with a cloth soaked in isopropyl alcohol to remove oil film, dirt, and dust, and then the substrate was dried.

[0075] (2) Surface Activation Step After the substrate on which the undercoat layer was formed was spray-washed with pure water, a surface activation treatment liquid (MSPS-Sa1A, manufactured by Mitsubishi Paper Mills, Ltd.) was spray-coated. The substrate was then spray-washed with pure water. The surface activation treatment liquid used was an aqueous solution containing tin(II) chloride, hydrogen chloride, hydrogen peroxide, and a polyhydric alcohol, with a pH of 1.0.

[0076] (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.

[0077] (4) Silver Particle Layer Formation Process: An ammoniacal silver nitrate aqueous solution and a reducing agent aqueous solution were simultaneously spray-applied to the surface of the pretreated substrate using separate airbrushes. The airbrush discharge rates 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 particle layer (thickness: 0.2 μm) with a silver luster. The substrate was then spray-washed with pure water. The ammoniacal silver nitrate aqueous solution used 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 used was an aqueous solution containing pyrocatechol, triethanolamine, sodium hydroxide, and an amino alcohol (pyrocatechol concentration: 4.5% by mass). Pyrocatechol has a HOMO energy level of −0.298 (Hartree) and a stabilization energy due to adsorption of −14.9 (kcal / mol).

[0078] (5) Passivation Treatment Step A passivation treatment liquid (MSPS-R1A, manufactured by Mitsubishi Paper Mills, Ltd.) was sprayed onto the surface of the substrate after the silver particle layer formation step. The surface was then spray-washed with pure water to obtain the laminate of Example 1. The passivation treatment liquid used in the passivation treatment was an aqueous solution containing potassium hydroxide and sulfite, with a pH of 7.5.

[0079] Example 2 A silver particle layer (thickness: 0.2 μm) was formed on a substrate in the same manner as in Example 1, except that an aqueous solution containing pyrogallol (pyrogallol concentration: 4.5% by mass) was used instead of pyrocatechol as the aqueous reducing agent solution. Pyrogallol has a HOMO energy level of −0.299 (Hartree) and a stabilization energy due to adsorption of −17 (kcal / mol).

[0080] Comparative Example 1 A silver particle layer (thickness: 0.2 μm) was formed on a substrate in the same manner as in Example 1, except that an aqueous solution containing glucose (glucose concentration: 4.5% by mass) was used instead of pyrocatechol as the reducing agent aqueous solution. Glucose has a HOMO energy level of −0.354 (Hartree) and a stabilization energy due to adsorption of −19.6 (kcal / mol).

[0081] Comparative Example 2 A silver particle layer (thickness: 0.2 μm) was formed on a substrate in the same manner as in Example 1, except that an aqueous solution containing ascorbic acid (ascorbic acid concentration: 4.5% by mass) was used instead of pyrocatechol as the aqueous reducing agent solution. Ascorbic acid has a HOMO energy level of −0.319 (Hartree) and a stabilization energy due to adsorption of −18.9 (kcal / mol).

[0082] Comparative Example 3 A silver particle layer (thickness: 0.2 μm) was formed on a substrate in the same manner as in Example 1, except that an aqueous solution containing phenol (phenol concentration: 4.5% by mass) was used instead of pyrocatechol as the reducing agent aqueous solution. Phenol has a HOMO energy level of −0.309 (Hartree) and a stabilization energy due to adsorption of −9.6 (kcal / mol).

[0083] <Evaluation> (1) Measurement of color difference L of the silver particle layer of the laminate ＊ a ＊ b ＊ L in color system ＊ was measured using an SCI spectrocolorimeter (CM-2600d manufactured by Konica Minolta, Inc.). The results are shown in Table 1.

[0084] (2) Measurement of Surface Resistivity The surface resistivity of the silver particle layer of the laminate was measured by pressing a surface resistance measurement terminal against the silver particle layer using a surface resistance measuring device (WA-400 manufactured by Taiyo Electric Sangyo Co., Ltd.). The results are shown in Table 1.

[0085] (3) Measurement of Millimeter Wave Transmission Attenuation The attenuation (transmission attenuation) when millimeter waves (76.5 GHz) were transmitted was measured by the following method. The results are shown in Table 1.

[0086] The transmission attenuation was calculated from the transmitted wave (transmission coefficient) determined by the free space method, as defined 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 onto the sample. In this experimental example, the attenuation of a laminate of a polycarbonate substrate as a base material and a silver particle layer is shown. The attenuation of the polycarbonate substrate as a base material alone is 0.86 dB. Here, the transmission attenuation can be calculated using the transmission coefficient (absolute value) from the following formula: Transmission attenuation (dB) = 20 log １０ | (Permeability coefficient) |

[0087] (4) Appearance Evaluation Appearance evaluation was performed on the laminates obtained in each Example and Comparative Example. Specifically, visual evaluation was performed by 20 subjects, and the evaluation was based on the number of subjects who judged that they could recognize the metal film. If 16 or more subjects judged that they could recognize the metal film, they were given an "A", if 11 to 15 subjects judged that they could recognize the metal film, they were given a "B", and if 10 or fewer subjects judged that they could not recognize the metal film, they were given a "C". The results are shown in Table 1.

[0088] (5) Presence or absence of organic film The laminates obtained in each example and comparative example were examined for the presence or absence of an organic film. Specifically, a transmission electron microscope (TEM) was used to determine the presence of an organic film when carbon components were found to be localized around silver particles.

[0089]

[0090] From the above results, in each of the Examples using a coating liquid composition containing an additive that satisfied the conditions of a HOMO energy level of −0.3192 (Hartree) or more and an adsorption stabilization energy of −13 (kcal / mol) or less, a silver mirror film with higher surface resistivity and lower attenuation was obtained compared to each of the Comparative Examples using a coating liquid composition that did not contain an additive that satisfied the above-mentioned conditions.

[0091] All publications, patent applications, and technical standards mentioned in this specification are incorporated by reference into this specification to the same extent as if each individual publication, patent application, or technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A coating agent liquid composition used to form a silver particle layer in combination with an ammoniacal silver nitrate aqueous solution, the coating agent liquid composition comprising an additive that satisfies the conditions of a HOMO energy level of -0.3192 (Hartree) or more and an adsorption stabilization energy of -13 (kcal / mol) or less in calculation of the highest occupied molecular orbital (HOMO) energy level and the adsorption stabilization energy.

2. The coating liquid composition according to claim 1, wherein the additive comprises a compound having a ring structure and at least one functional group selected from the group consisting of a hydroxy group, a formyl group, and a carbonyl group.

3. L of the silver particle layer ＊ a ＊ b ＊ L in color system ＊ The coating liquid composition according to claim 1 or 2, wherein the viscosity is 75 or more.

4. The coating liquid composition according to any one of claims 1 to 3, wherein the silver particle layer has a millimeter wave transmission attenuation of 4.0 dB or less.

5. The surface resistivity of the silver particle layer is 10 ４ The coating liquid composition according to any one of claims 1 to 4, having a viscosity of Ω / □ or more.

6. A method for producing a laminate, comprising a step of forming a silver particle layer on a substrate, the step comprising contacting an aqueous ammoniacal silver nitrate solution with the coating agent liquid composition according to any one of claims 1 to 5.

7. The method for producing a laminate according to claim 6, further comprising the step of subjecting the surface of the substrate to at least one of surface activation treatment and pretreatment prior to the step of forming the silver particle layer.

8. The method for producing a laminate according to claim 6 or 7, further comprising a step of performing a passivation treatment on the surface of the base material on which the silver particle layer has been formed, after the step of forming the silver particle layer.

9. A molded article having a silver particle layer formed by contacting an aqueous ammoniacal silver nitrate solution with the coating liquid composition according to any one of claims 1 to 5.

10. The molded article according to claim 9, which is used for automobile parts, interior and exterior parts, or sensor covers.

Images