JP2014065268A - Silver plating-coated body - Google Patents

Abstract

The present invention provides a silver-plated coated body with improved change in reflectance that occurs when stored for a long period of time.
In a silver-plated coated body having at least an undercoat layer, a silver thin film layer, and a topcoat layer on a substrate in this order, at least one layer selected from the undercoat layer and the topcoat layer comprises a thiol group and A silver-plated coated body comprising a heterocyclic compound having a hydrophobic group and having an octanol-water partition coefficient (Log P) of 3.5 or more.
[Selection figure] None

Description

  The present invention relates to a silver-plated coated body, and more particularly to a silver-plated coated body with improved change in reflectance that occurs when stored for a long period of time.

  A silver-plated coated body having a silver thin film layer on a base material has the highest reflection gloss among metals, and is therefore processed into a metal or plastic surface and used as a design material or a reflective material. Further, it is a material that can be effectively used as an electromagnetic shielding material, for example, by utilizing the high conductivity of the silver thin film layer.

  In such a silver-plated coated body, an undercoat layer is provided on the base material in order to improve the adhesion between the silver thin film layer and the base material, or to smooth the base material surface in the formation region of the silver thin film layer. It is known. For example, Japanese Patent Laid-Open No. 10-309774 describes an undercoat agent made of a paint containing at least one of an alkoxytitanium ester, a silane coupling agent having an epoxy group, and an epoxy resin. The publication describes an undercoat layer made of polyester resin, alkyd resin, acrylic resin, two-component curable polyurethane resin, or the like. Further, in order to make the adhesion between the silver thin film layer and the substrate stronger, for example, JP 2009-249671 A (Patent Document 1) discloses a silver thin film by silver mirror reaction using a solution containing a nitrogen-containing compound. The formation of a layer is described.

  Further, since silver is very soft and its surface is easily damaged, it is known that a top coat layer is provided on the surface of the silver thin film layer using various hard coat materials, for example, Japanese Patent Application Laid-Open No. 2000-129448. Describes that a liquid epoxy resin, an unsaturated polyester resin, a fluororesin, an acrylic resin, a melamine resin, a silicon resin, and the like can be used for the topcoat layer. JP-A-2003-155580, JP-A-2004-203014 Describe the use of a silicone acrylic paint having a specific glass transition temperature. Japanese Patent Application Laid-Open Nos. 2008-110101 and 2008-176050 describe that ultraviolet curable resins and electron beam curable resins may be used.

  However, when the silver-plated coated body is stored for a long period of time, there is a problem that the reflectance changes due to discoloration of the silver thin film layer, and improvement has been demanded.

  On the other hand, Japanese Patent Application Laid-Open No. 2004-169157 (Patent Document 2) discloses that a silver thin film layer is treated with an organic compound that reacts with silver or has an affinity for silver, whereby the corrosion resistance and coating of the silver thin film layer are obtained. A technique for increasing the strength is disclosed. Japanese Patent Application Laid-Open No. 2003-238901 (Patent Document 3) describes that a benzothiazole-based metal deactivator is used in at least one of the undercoat layer and the topcoat layer. Patent Document 4) describes that a benzotriazole compound is used in at least one of the undercoat layer and the topcoat layer, and Japanese Patent Application Laid-Open No. 2011-128501 (Patent Document 5) discloses a thioether type, a thiol type, and a Ni type. It describes that an anti-discoloring agent layer containing an organic compound-based, benzotriazole-based, imidazole-based, oxazole-based, tetrazaindene-based, pyrimidine-based or thiadiazole-based compound is provided.

  However, these proposals are not fully satisfactory, and further improvements are required.

JP 2009-249671 A JP 2004-169157 A JP 2003-238901 A JP 2007-169685 A JP 2011-128501 A

  An object of this invention is to provide the silver plating coating body by which the change of the reflectance which arises when preserve | saving for a long period of time was improved.

The above object of the present invention is achieved by the invention described below.
1. In a silver-plated coated body having at least an undercoat layer, a silver thin film layer, and a topcoat layer in this order on a substrate, at least one layer selected from the undercoat layer and the topcoat layer has a thiol group and a hydrophobic group. A silver-plated coated body comprising a heterocyclic compound having an octanol-water partition coefficient (Log P) of 3.5 or more.

  According to the present invention, it is possible to provide a silver-plated coated body in which a change in reflectance that occurs when stored for a long period of time is improved.

  The silver-plated coated body of the present invention is a silver-plated coated body having at least an undercoat layer, a silver thin film layer, and a topcoat layer in this order on a substrate, and at least selected from the undercoat layer and the topcoat layer One layer contains a heterocyclic compound having a thiol group and a hydrophobic group and an octanol-water partition coefficient (Log P) of 3.5 or more (hereinafter referred to as a compound of the present invention).

  In the present invention, examples of the hydrophobic group include an alkyl group, an alkylene group, and an aryl group. These may have a substituent, and the alkyl group or the alkylene group may be branched. Specific examples of the alkyl group include methyl group, ethyl group, butyl group, isopropyl group, n-hexyl group, n-heptyl group, n-octyl group, n-decyl group, n-tetradecyl group, n-hexadecyl group and the like. Examples of the alkylene group include these divalent groups. Preferred alkyl groups and alkylene groups are those having 4 or more carbon atoms. Specific examples of the aryl group include a phenyl group and a naphthyl group. These hydrophobic groups are preferably bonded to a heterocyclic ring, and are preferably bonded to the heterocyclic ring via a sulfur, nitrogen, oxygen atom or the like. The aryl group may be condensed with a heterocyclic ring serving as a mother nucleus. Further, these alkyl group, alkylene group, and aryl group may further have the above-described alkyl group or aryl group as a substituent via a sulfur, nitrogen, oxygen atom or the like.

  Since the heterocyclic compound used in the present invention has these hydrophobic groups, the octanol-water partition coefficient (Log P) as the compound needs to be 3.5 or more, and more preferably 4.0 or more. .

  Specific examples of the heterocyclic ring include imidazole, imidazolidine, imidazoline, oxadiazole, oxazine, thiadiazole, thiazole, thiazolidine, tetrazole, triazine, triazole, piperazine, piperidine, pyrazine, pyrazole, pyrazolidine, pyridine, pyridazine, pyrimidine, pyrrole, Pyrrolidine is mentioned. Particularly preferred heterocycles are oxadiazole, thiadiazole, and triazole. The compound of the present invention may have a plurality of these heterocycles in one molecule. In that case, the alkylene group may connect a plurality of heterocycles, and the alkylene group may be sulfur, nitrogen, oxygen. A plurality of heterocycles may be linked via an atom or the like.

  Specific examples of the compound of the present invention are shown below, but the present invention is not limited thereto. The LogP values shown in the figure were calculated by the Crippen method.

  The compound of the present invention is contained in the topcoat layer and the undercoat layer in combination of one or more kinds, and the amount thereof is 0.01 to each of the resin solid content contained in the topcoat layer or the undercoat layer. It is preferable that it is 40 mass%, More preferably, it is the range of 0.1-10 mass%. If the amount is too large, the reflectance may decrease due to silver discoloration.

  The undercoat layer is required to have good adhesion to the substrate and excellent adhesion to the silver thin film layer provided on the undercoat layer. It is also required to form a smooth surface. Examples of the undercoat layer include polymers having terminal hydroxyl groups, such as alkyd polyols, polyester polyols, and acrylic polyols, in addition to the undercoat layers described in JP-A-10-309774 and JP-A-2002-256455 described above. Or, an undercoat layer obtained by applying a polyol-based paint composition in which an isocyanate compound is mixed as an oligomer and a curing agent, or an epoxy-based paint composition in which an amine compound is mixed as a curing agent on an epoxy resin is exemplified. . These can be appropriately selected and used based on the properties required for the substrate and the coated body. The thickness of the undercoat layer is preferably 5 to 30 μm, but is not particularly limited.

  As a method for providing the undercoat layer, it is common to apply the coating composition by dissolving or diluting it in an organic solvent. Examples of the organic solvent include hydrocarbons such as cyclohexane and Solvesso 100 (trade name, manufactured by Exxon Chemical), ethers such as cellosolve, methyl cellosolve, butyl cellosolve, carbitol and diethylcarbitol, methanol, ethanol, isopropyl Alcohols such as alcohol, butyl alcohol and cyclohexanol, ethyl acetate, n-butyl acetate, isobutyl acetate, amyl formate, isoamyl acetate, isobutyl acetate, butyl propionate, isopropyl butyrate, ethyl butyrate, butyl butyrate, alkyl esters, Estes such as methyl lactate, ethyl lactate, methyl oxyacetate, ethyl oxyacetate, butyl oxyacetate, methyl methoxyacetate, ethyl methoxyacetate, butyl methoxyacetate, methyl ethoxyacetate, ethyl ethoxyacetate Diethylene glycol dimethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, Examples include ethers such as propylene glycol monoethyl ether acetate and propylene glycol monopropyl ether acetate, and ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 2-heptanone, and 3-heptanone, but the present invention is limited. No.

  These organic solvents are used for coating the undercoat layer or the solubility of the coating composition used for coating the topcoat layer described later, and improving the surface quality of the coated surface. From the viewpoint of the above, it is appropriately selected and used alone, but is often used in a mixture of two or more. Moreover, as a coating method of the coating composition used for coating the undercoat layer and the topcoat layer, a conventionally known coating method may be used. For example, a gravure roll method, a reverse roll method, a dip roll method, a bar coater method Any method such as a knife coater method, an air spray method, an airless spray method, or a dip method can be used.

  The coating composition used for coating the topcoat layer of the silver-plated coating body of the present invention is generally a coating composition containing a thermosetting resin, but a coating containing an ultraviolet curable resin. Compositions can also be used. The use of an ultraviolet curable resin is particularly suitable because the manufacturing process time is short. In the ultraviolet curable resin, a photopolymerization initiator is used as necessary. These topcoat layers may be used in combination with coloring materials and additives as necessary.

  Examples of the thermosetting resin include liquid epoxy resins, unsaturated polyester resins, fluororesins, acrylic resins, melamine resins, and silicon resins described in JP-A No. 2000-129448, and JP-A No. 2003-155580. Examples thereof include silicone acrylic resins, two-component curable polyurethane resins described in JP-A No. 2002-256445, and acrylic modified silicone resins. Moreover, as a commercially available thermosetting resin, for example, “PTC-02UH (10B)” (silicon acrylic paint) manufactured by Fujikura Kasei Co., Ltd. or “Origigtsuk # 100” (acrylic silicone paint) manufactured by Origin Electric Co., Ltd. ), “Hi-Polynal No. 800S” (acrylic paint) manufactured by Ohashi Chemical Industries, Ltd. is preferably used.

  As the ultraviolet curable resin, monomers and oligomer compounds mainly containing an ethylenically unsaturated group are preferably used, which include an electron curable resin and is cured with ultraviolet rays. Specific examples include amide monomers, (meth) acrylate monomers, urethane acrylates, polyester (meth) acrylates, and epoxy (meth) acrylates. Examples of amide monomers include amide compounds such as N-vinylpyrrolidone, N-vinylcaprolactam, and acryloylmorpholine. Examples of (meth) acrylate monomers include: hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 2-hydroxy-3-phenylpropyl acrylate; phenoxyethyl (meta ) Acrylates of alkylene oxide adducts of phenols such as acrylates and their halogen nucleus substitution products; mono- or di (meth) acrylates of ethylene glycol, mono (meth) acrylates of methoxyethylene glycol, mono- or di (meta) of tetraethylene glycol ) Acrylates, mono- or di (meth) acrylates of glycols, such as mono- or di (meth) acrylates of tripropylene glycol; trimethylolpropane tri (meth) acrylates, Poly (pentaerythritol) tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexaacrylate, etc., and (meth) acrylic acid ester of alkylene oxide, isocyanuric acid EO modified di- or tri (meth) acrylate, etc. Is mentioned.

  Examples of the urethane (meth) acrylate oligomer include a reaction product obtained by further reacting a hydroxyl group-containing (meth) acrylate with a polyol and an organic polyisocyanate reaction product. Here, examples of the polyol include a low molecular weight polyol, polyethylene glycol, and polyester polyol, and examples of the low molecular weight polyol include ethylene glycol, propylene glycol, cyclohexanedimethanol, and 3-methyl-1,5-pentanediol. Examples of the polyether polyol include polyethylene glycol and polypropylene glycol. Examples of the polyester polyol include these low molecular weight polyols and / or polyether polyols, adipic acid, succinic acid, phthalic acid, hexahydrophthalic acid, and terephthalic acid. And a reaction product with an acid component such as a dibasic acid or an anhydride thereof. Examples of the organic polyisocyanate include tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate. Examples of the hydroxyl group-containing (meth) acrylate include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate.

  As a polyester (meth) acrylate oligomer, the dehydration condensate of a polyester polyol and (meth) acrylic acid is mentioned. Examples of the polyester polyol include low molecular weight polyols such as ethylene glycol, polyethylene glycol, cyclohexanedimethanol, 3-methyl-1,5-pentanediol, propylene glycol, polypropylene glycol, 1,6-hexanediol and trimethylolpropane, and these And a reaction product from a polyol such as an alkylene oxide adduct and an acid component such as a dipic acid such as adipic acid, succinic acid, phthalic acid, hexahydrophthalic acid and terephthalic acid, or an anhydride thereof. Epoxy acrylate is obtained by addition reaction of unsaturated carboxylic acid such as (meth) acrylic acid to epoxy resin. Epoxy (meth) acrylate of bisphenol A type epoxy resin, epoxy (meth) of phenol or cresol novolac type epoxy resin Examples thereof include (meth) acrylic acid addition reactants of acrylate and polyether diglycidyl ether.

  Photopolymerization initiators include benzoin such as benzoin, benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether and alkyl ethers thereof; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenyl Acetophenones such as acetophenone, 1,1-dichloroacetophenone, 1-hydroxyacetophenone, 1-hydroxycyclohexyl phenyl ketone and 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one; 2 -Anthraquinones such as methyl anthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone and 2-amylanthraquinone; 2,4-dimethylthioxa Thioxanthone such as benzene, 2,4-diethylthioxanthone, 2-chlorothioxanthone and 2,4-diisopropylpyroxanthone; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; 2,4,6-trimethylbenzoyl diphenylphosphine oxide and the like Monoacylphosphine oxide or bisacylphosphine oxide; benzophenones such as benzophenone; and xanthones. These photopolymerization initiators can be used alone or in combination with a benzoic acid-based or amine-based photopolymerization initiation accelerator.

  The content of the photopolymerization initiator is preferably 0.01 to 20% by mass and particularly preferably 0.5 to 7% by mass with respect to the ultraviolet curable resin.

  In order to cure the coating composition used for coating the topcoat layer, it is sufficient to heat or irradiate with an electron beam or ultraviolet ray. Examples of means for irradiating the electron beam and ultraviolet ray include xenon lamps and halogens. Examples thereof include lamp light sources such as lamps, tungsten lamps, high-pressure mercury lamps, ultrahigh-pressure mercury lamps, metal halide lamps, medium-pressure mercury lamps, and low-pressure mercury lamps, and laser light sources such as argon ion lasers, YAG lasers, excimer lasers, and nitrogen lasers.

  The thickness of the thermosetting resin top coat layer is preferably in the range of 10 μm to 25 μm, and the ultraviolet curable resin top coat is preferably in the range of 3 μm to 10 μm. If the layer is too thin, the function of protecting the silver thin film layer cannot be obtained, and a uniform coating film cannot be formed. On the other hand, if it is too thick, the peripheral portion is locally thickened further. Furthermore, since the light transmission distance becomes longer and the light loss increases, the reflectance of the silver mirror plating layer is lowered, which is not preferable.

  The colorant added to the topcoat layer can be color-tuned by further including a colorant such as a pigment or dye. It is more preferable that the absorption wavelength of the coloring material does not include the absorption wavelength of the photoinitiator because it does not hinder the activity of the photoinitiator. Examples of pigments include organic pigments such as carbon black, quinacridone, naphthol red, cyanine blue, cyanine green, and hansa yellow; inorganics such as titanium oxide, aluminum oxide, calcium carbonate, barium sulfate, mica, petal, and composite metal oxides. Examples thereof include, but are not limited to, pigments. One or a combination of two or more selected from these pigments can be used. The dispersion of the pigment is not particularly limited, and a method of directly dispersing the pigment powder by a usual method, for example, dynomeal, paint shaker, sand mill, ball mill, kneader, roll, dissolver, homogenizer, ultrasonic vibration, stirrer, etc. Is used. At that time, it is possible to use a dispersant, a dispersion aid, a thickener, a coupling agent and the like. The amount of pigment added is not particularly limited because the concealability varies depending on the type of pigment, but for example, preferably 0.01 to 10% by mass, based on the solid content of the cured resin component in the total amount of each composition, More preferably, it is 0.1-5 mass%. When the added amount of the pigment is less than 0.01% by mass, the colorability tends to deteriorate. When the added amount exceeds 10% by mass, the reflectance of the silver thin film layer is lowered and the value of silver plating may be impaired.

  Examples of dyes include azo, anthraquinone, indoidoid, sulfide, triphenylmethane, xanthene, alizarin, acridine, quinoneimine, thiazole, methine, nitro, and nitroso dyes. Although it is mentioned, it is not limited to these. One or a combination of two or more selected from these dyes can be used. The amount of the dye added is not particularly limited because the concealability varies depending on the type of the dye, but is preferably 0.01 to 10% by mass, for example, based on the solid content of the cured resin component in the total amount of each composition, More preferably, it is 0.1-5 mass%. When the added amount of the dye is less than 0.01% by mass, the colorability tends to deteriorate. When the added amount exceeds 10% by mass, the reflectance of the silver thin film layer may be lowered to impair the value of the silver plating layer. .

  The topcoat layer may further contain a leveling agent, metal powder, glass powder, antibacterial agent, antioxidant, ultraviolet absorber, and the like as additives.

  Furthermore, the adhesiveness of the silver thin film layer can be further improved by using a silane coupling agent in the above-described undercoat layer and topcoat layer.

  The silane coupling agent used in the present invention may be any commonly used silane coupling agent such as vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (2-methoxyethoxy) silane, 3-methacrylic acid. Loxypropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3- Mercaptopropyltriethoxysilane, 3-octanoylthio-1-propyltriethoxysilane, 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, 3- (N-phenyl) a Roh trimethoxysilane, 3-glycidoxypropyl triethoxy silane, 3-ureidopropyltriethoxysilane, 3-isocyanate propyl triethoxysilane, and 3-isocyanate propyl trimethoxysilane.

  It is preferable that the usage-amount of a silane coupling agent is 1-30 mass% with respect to the resin solid content which the coating composition used in order to apply a topcoat layer and an undercoat layer. If the amount is too large, the bond strength of the undercoat resin or topcoat resin may be reduced.

  Various plastics, metals, glasses, rubbers and the like are used as the base material of the silver-plated coated body of the present invention. Examples of the plastics include polycarbonate resin, acrylic resin, ABS resin, vinyl chloride resin, epoxy resin, phenol resin, polyethylene terephthalate (PET) resin, polyester resin such as polybutylene terephthalate (PBT) resin, fluorine resin, polypropylene ( PP) resin, a resin obtained by compounding these, and fiber reinforced plastic (FRP) reinforced with organic fibers such as nylon fiber and pulp fiber may be mentioned, but not particularly limited. Examples of the metal include, but are not limited to, iron, aluminum, stainless steel, copper, and brass. The glass is not particularly limited, such as inorganic glass or plastic glass.

  The above-described base material may be pretreated for the purpose of improving the adhesion with the above-described undercoat layer. Examples of the pretreatment method include wet methods such as detergent, solvent washing and ultrasonic washing, and dry treatment such as corona treatment, ultraviolet irradiation, and electron beam irradiation treatment.

  Depending on the type of base material, for example, a primer layer may be provided between the base material and the undercoat layer in order to prevent rust and improve adhesion to polypropylene, iron, and aluminum. Further, if the undercoat layer cannot be dried at a high temperature of 100 ° C. or higher due to deformation and shrinkage of the base material, a curing accelerator may be added, or a leveling agent may be used to improve the surface quality. Curing accelerators include urethane curing accelerator from Nagashima Co., Ltd., drying accelerator A from Sansei Paint Industry Co., Ltd., Nitto Bussan Co., Ltd., San Apro Co., Ltd., Nippon Chemical Industry Co., Ltd., Mitsubishi Chemical Co. Curing of 1.8-diazabicyclo [5,4,0] undecene-7 and 1,5-diazabicyclo [4,3,0] nonene-5 phenols, oleates, octylates and epoxy resins as accelerators Various amines are available as accelerators. As leveling agents, silicon leveling agents and fluorine leveling agents are available from Tohshin Chemical Co., Ltd., DIC Corporation, and BYK Co., Ltd. If more leveling agents are used, adhesion between the undercoat layer and the silver thin film layer Care must be taken because it causes a drop. The amount of the curing accelerator used is 0.1 to 2% by weight, preferably 0.3 to 1% by weight, based on the whole undercoat paint, and the amount of the leveling agent used is 0.001 to 1% by weight based on the whole undercoat paint. Preferably, it is 0.005-0.05 mass%.

  The silver plating coating body of this invention has a silver thin film layer on the undercoat layer mentioned above. In order to form a silver thin film layer on the undercoat layer, preferably the undercoat layer provided on the surface of the base material is treated with an active treatment solution for silver mirrors containing stannous chloride to understine stannous ions. A silver thin film layer is formed on the surface of the coat layer by a silver mirror reaction on the activated undercoat layer.

  As a treatment method for treating the undercoat layer with an active treatment solution for silver mirror containing stannous chloride, a method of immersing a substrate provided with an undercoat layer in an active treatment solution for silver mirror, on the surface of the undercoat layer There is a method of applying an active treatment liquid for silver mirror containing stannous chloride and the like. Although it can select arbitrarily by the shape of a base material etc., as an application | coating method, the spray application which does not choose the shape of a base material especially is suitable. Furthermore, you may wash | clean the activation process liquid adhering excessively to the undercoat layer surface with deionized water or purified distilled water.

  Examples of the active treatment liquid for silver mirror containing stannous chloride include activation treatment liquids described in JP 2007-197743 A, JP 2006-274400 A, and the like.

  You may provide the process of performing the activation process by silver ion after the process processed with the active process liquid for silver mirrors. For the activation treatment with silver ions, for example, treatment with a treatment solution containing silver nitrate is simple and preferable. The silver nitrate concentration of the silver nitrate aqueous solution used in this step is preferably 0.01 mol / L or less and further brought into contact with the undercoat layer treated with stannous chloride. When performing this silver ion treatment, it is preferable to wash with deionized water after the silver ion treatment. For these activation processes, spray coating in which a new solution is always supplied is suitable.

  The silver thin film layer is formed by silver mirror reaction on the surface of the undercoat layer that has been subjected to the above activation treatment with two solutions of an ammoniacal silver nitrate solution containing silver nitrate and ammonia and a reducing agent solution containing a reducing agent and a strong alkali component. Apply to mix. As a result, an oxidation-reduction reaction occurs, so that metallic silver is deposited, a silver coating is formed, and a silver thin film layer is formed.

  As the reducing agent solution, an aldehyde compound such as glucose or glyoxal, an organic compound such as a hydrazine compound such as hydrazine sulfate, hydrazine carbonate or hydrazine hydrate, or an aqueous solution such as sodium sulfite or sodium thiosulfate is preferably used.

  Several additives may be added to the aqueous ammoniacal silver nitrate solution to produce good silver. For example, monoethanolamine, tris (hydroxymethyl) aminomethane, 2-amino-2-hydroxymethyl-1,3-propanediol, 1-amino-2-propanol, 2-amino-1-propanol, diethanolamine, diisopropanol Examples include amino alcohol compounds such as amine, triethanolamine and triisopropanolamine, amino acids such as glycine, alanine and sodium glycine, and salts thereof, but are not particularly limited.

  As a method of applying the two solutions of the ammoniacal silver nitrate solution and the reducing agent solution so as to be mixed on the surface of the undercoat layer, two kinds of aqueous solutions are mixed in advance, and this mixed solution is used with a spray gun or the like. A method of spraying on the surface of the coating layer, a method of spraying using a concentric spray gun having a structure in which two types of aqueous solutions are mixed and immediately discharged in the head of the spray gun, and a two-head spray having two spray nozzles for the two types of aqueous solutions There are a method of spraying and spraying each from a gun, a method of spraying two kinds of aqueous solutions simultaneously using two separate spray guns, and the like. These can be arbitrarily selected according to the situation.

  Subsequently, it is preferable to wash the surface of the silver thin film layer with deionized water or purified distilled water, and remove the solution after the silver mirror reaction remaining on the surface. In addition, before providing the above-mentioned topcoat layer on the silver thin film layer, for the purpose of stabilizing the deposited silver metal, it is immersed in a solution containing an organic compound that reacts or has affinity with silver, or the solution is applied. Surface treatment can be performed.

  As the organic compound, a nitrogen-containing heterocyclic compound having a thiol group or a thione group is effectively used, and the aforementioned compound of the present invention can also be effectively used. Speaking of the heterocyclic ring of the nitrogen-containing heterocyclic compound, there are imidazole, imidazoline, thiazole, thiazoline, oxazole, oxazoline, pyrazoline, triazole, thiadiazole, oxadiazole, tetrazole, pyridine, pyrimidine, pyridazine, pyrazine, triazine, etc. Imidazole, triazole and tetrazole are preferred. Specific examples include 2-mercapto-4-phenylimidazole, 2-mercapto-1-benzylimidazole, 2-mercapto-benzimidazole, 1-ethyl-2-mercapto-benzimidazole, 2-mercapto-1-butyl-benzimidazole. 1,3-diethyl-benzimidazoline-2-thione, 1,3-dibenzyl-imidazolidine-2-thione, 2,2'-dimercapto-1,1'-decamethylene-diimidazoline, 2-mercapto-4- Phenylthiazole, 2-mercapto-benzothiazole, 2-mercaptonaphthothiazole, 3-ethyl-benzothiazoline-2-thione, 3-dodecyl-benzothiazoline-2-thione, 2-mercapto-4,5-diphenyloxazole, 2 -Mercaptobenzoxazole, -Pentyl-benzoxazoline-2-thione, 1-phenyl-3-methylpyrazolin-5-thione, 3-mercapto-4-allyl-5-pentadecyl-1,2,4-triazole, 3-mercapto-5-nonyl 1,2,4-triazole, 3-mercapto-4-acetamido-5-heptyl-1,2,4-triazole, 3-mercapto-4-amino-5-heptadecyl-1,2,4-triazole, 2- Mercapto-5-phenyl-1,3,4-thiadiazole, 2-mercapto-5-n-heptyl-oxathiazole, 2-mercapto-5-n-heptyl-oxadiazole, 2-mercapto-5-phenyl-1 , 3,4-oxadiazole, 2-heptadecyl-5-phenyl-1,3,4-oxadiazole, 5-mercapto-1 Phenyl-tetrazole, 2-mercapto-5-nitropyridine, 1-methyl-quinoline-2 (1H) -thione, 3-mercapto-4-methyl-6-phenyl-pyridazine, 2-mercapto-5,6-diphenyl- Pyrazine, 2-mercapto-4,6-diphenyl-1,3,5-triazine, 2-amino-4-mercapto-6-benzyl-1,3,5-triazine, 1,5-dimercapto-3,7- And diphenyl-s-triazolino [1,2-a] -s-triazoline.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, the content of this invention is not restricted to an Example. % Is based on mass.

(Comparative Example 1)
The surface of the aluminum plate was degreased, washed with water and dried. Polyol-based undercoat resin (Gunplating raster clear MS manufactured by Ohashi Chemical Industries) and isocyanate-based curing agent (Gunplating raster undercuring agent N manufactured by Ohashi Chemical Industries) and thinner (methyl ethyl ketone and butylcellsolve in a ratio of 1: 1) Were mixed at a mass ratio of 10: 2: 10 to obtain a coating composition for an undercoat layer. This coating composition was spray-coated using a spray gun and then heated and dried at 80 ° C. for 1 hour to form an undercoat layer having a thickness of 20 μm.

  The silver mirror activation treatment solution containing 0.15 mol of hydrochloric acid and 0.06 mol of stannous chloride is made up to 1000 g with water, sprayed onto the undercoat layer by a spray gun, and then deionized. Washed with water.

  The silver mirror plating solution was prepared as follows. Separately from a silver nitrate solution obtained by dissolving 20 g of silver nitrate in 1000 g of deionized water, 100 g of 28% aqueous ammonia solution and 5 g of monoethanolamine were dissolved in 1000 g of deionized water to prepare an ammonia solution. Prior to use, the silver nitrate solution and the ammonia solution were mixed one-to-one to obtain an ammoniacal silver nitrate solution. Next, 10 g of hydrazine sulfate, 5 g of monoethanolamine and 10 g of sodium hydroxide were dissolved in 1000 g of deionized water to prepare a reducing agent solution.

  The ammoniacal silver nitrate solution and the reducing agent solution thus obtained were simultaneously sprayed using a double-head spray gun to form a silver thin film layer, washed with deionized water, and then in a dryer at 70 ° C. for 30 minutes. Dried.

  Next, a top coat layer was provided on the silver thin film layer. Mass ratio of acrylic topcoat paint (Hipolynal No. 800S manufactured by Ohashi Chemical Industries), silicone curing agent (hardener B manufactured by Ohashi Chemical Industries) and thinner (Methyl ethyl ketone and butyl cellsolve are mixed at a ratio of 1: 1) The mixture was mixed at a ratio of 6: 1: 6 to obtain a coating composition for the topcoat layer, and was spray-coated on the silver thin film layer with a spray gun. A 15 μm topcoat layer was formed by heating and drying at 70 ° C. for 30 minutes. In this way, a silver-plated coated body obtained by silver mirror plating on the aluminum plate was obtained.

(Examples 1-8)
Resin solid content in which the coating composition for the topcoat layer contains M4, M6, M7, M9, M14, M17, M22, and M24 as the compounds of the present invention in the coating composition for the topcoat layer of Comparative Example 1 A silver-plated coated body was obtained in the same manner as in Comparative Example 1 except that the content was 0.5% with respect to each other.

Example 9
Comparative Example 1 except that M4 was added to the coating composition for the topcoat layer of Comparative Example 1 as a compound of the present invention so as to be 1% based on the resin solid content contained in the coating composition for the topcoat layer. In the same manner as in Example 1, a silver-plated coated body was obtained.

(Example 10)
Except for adding M14 as a compound of the present invention to the coating composition for the undercoat layer of Comparative Example 1 so that the solid content of the resin contained in the coating composition for the undercoat layer is 0.5%. Obtained a silver-plated coated body in the same manner as in Comparative Example 1.

(Example 11)
In Comparative Example 1, the silver thin film layer was surface treated by dipping in a 10% solution of M14 (solvent is methyl isobutyl ketone) for 20 seconds with respect to the silver thin film layer, and then washed with water and dried. Thereafter, the coating composition for the topcoat layer of Comparative Example 1 contains M14 as the compound of the present invention so that the content of the resin solids contained in the coating composition for the topcoat layer is 0.5%. A top coat layer was formed to obtain a silver-plated coating.

(Comparative Examples 2-3)
Silver plating was carried out in the same manner as in Comparative Example 1 except that the coating composition for the topcoat layer of Comparative Example 1 contained R1 and R2 as comparative compounds at 0.5% based on the solid content of the topcoat resin. A painted body was obtained.

(Comparative Example 4)
In Comparative Example 1, the silver thin film layer was immersed in a 10% solution of M14 (solvent is methyl isobutyl ketone) for 20 seconds to surface-treat the silver thin film layer, washed with water, dried, and then surface-treated silver thin film layer A top coat layer was provided in the same manner as in Comparative Example 1 to obtain a silver-plated coated body.

<Evaluation test method>
The silver-plated coatings obtained in Examples 1 to 11 and Comparative Examples 1 to 4 were stored at 120 ° C. for 4 months, and the change in color tone was measured using a spectral colorimeter CM-2500d manufactured by Konica Minolta Optics. The change in reflectivity (SCI measured value) at 400 nm (difference immediately after preparation of the silver-plated coated body and after lapse of 4 months) was examined. The results are shown in Table 1.
A: Less than 8%.
○: 8% or more and less than 10%.
○ △: 10% or more and less than 15%.
Δ: 15% or more and less than 40%.
X: 40% or more.

  As is apparent from the above results, it can be seen that the present invention can provide a silver-plated coated body with improved change in reflectance that occurs when stored for a long period of time.

Claims (1)

  In a silver-plated coated body having at least an undercoat layer, a silver thin film layer, and a topcoat layer in this order on a substrate, at least one layer selected from the undercoat layer and the topcoat layer has a thiol group and a hydrophobic group. A silver-plated coated body comprising a heterocyclic compound having an octanol-water partition coefficient (Log P) of 3.5 or more.