JP2013202818A - Silver plating coating body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silver plating coating body having excellent adhesion and resistance to discoloration.SOLUTION: A silver plating coating body includes at least a silver thin film layer and a top coat layer on a substrate thereof, and the top coat layer contains a thiourea and a thiol organic acid derivative.

Description

  The present invention relates to a silver-plated painted body, and more particularly to a silver-plated painted body excellent in adhesion and discoloration prevention.

  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. However, silver has a high reactivity with sulfides, so discoloration such as whitening and blackening is likely to occur, and because it is very soft, its surface is easily damaged, so it has not been used in a wide range of industrial products. .

  In order to cope with such problems inherent to silver, it has been devised to provide a topcoat layer on the surface of the silver thin film layer using various hard coat materials. For example, JP 2000-129448 A describes that liquid epoxy resins, unsaturated polyester resins, fluororesins, acrylic resins, melamine resins, silicon resins, and the like can be used for the topcoat layer. JP, 2004-203014, A (patent documents 1) etc. describe using a silicon acrylic paint which has 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, even if these topcoat layers are provided, the silver thin film layer has high hydrophilicity, so that it can be exposed to high temperature and high humidity environments, and particularly to an atmosphere containing salt water, so that the adhesion between the silver thin film and the topcoat layer can be improved. There was a problem that became very weak, and there was a need for improvement.

  In order to improve the adhesion between the silver thin film layer and the top coat layer, it is known to use various silane coupling agents. For example, JP 2004-203014 A and JP 2005-307179 A mentioned above. No. (Patent Document 2) and the like. However, the adhesiveness with the silver thin film layer in an environment containing salt water is not always sufficient, and improvement has been desired.

  On the other hand, Japanese Patent Laid-Open No. 06-41762 (Patent Document 3) discloses that a surface of a copper base is pretreated with an acidic solution containing thiourea or a derivative thereof, and then electroless tin plating or solder plating is performed. JP-A-2001-247826 (Patent Document 4) describes that the adhesion between a copper base material and these plating layers is improved. JP-A-2001-247826 (Patent Document 4) describes thiourea. A metal surface coating composition containing an organic sulfur compound such as an analog is described. However, when thioureas are allowed to act on the silver thin film layer, silver discoloration such as whitening or blackening may occur, and improvement has been desired.

JP 2004-203014 A JP 2005-307179 A Japanese Patent Laid-Open No. 06-41762 JP 2001-247826 A

  An object of this invention is to provide the silver plating coating body excellent in adhesiveness and discoloration prevention property.

The above object of the present invention is achieved by the following invention.
(1) A silver-plated coated body having at least a silver thin film layer and a topcoat layer on a substrate, wherein the topcoat layer contains a thiourea and a thiol organic acid derivative.
(2) The silver-plated coated body according to (1) above, wherein the topcoat layer further contains a silane coupling agent.

  By this invention, the silver plating coating body excellent in adhesiveness and discoloration prevention property can be provided.

  In the silver-plated coated body of the present invention, the topcoat layer contains thioureas and a thiol organic acid derivative. As will be described later in Examples, thioureas act on silver and cause discoloration such as blackening. The present inventor can significantly improve the adhesion between the silver thin film layer and the topcoat layer without discoloring silver by using thioureas that cause discoloration in combination with a thiol organic acid derivative when used alone. I found. Although the mechanism is not clear, it is considered that thioureas are somehow involved in strengthening the bond between silver and a thiol organic acid derivative, without silver and thiourea being bound alone.

  The thioureas used in the present invention are thiourea and thiourea derivatives. Examples of thiourea derivatives include 1-methylthiourea, 1,3-dimethylthiourea, diethylthiourea (for example, 1,3-diethylthiourea), trimethylthiourea, 1,3-diisopropylthiourea, allylthiourea, acetylthiourea, ethylenethio Urea, 1,3-diphenylthiourea, thiourea dioxide, thiosemicarbazide, s-methylisothiourea sulfate, tributylthiourea, benzylisothiourea hydrochloride, 1,3-dibutylthiourea, 1-naphthylthiourea, tetramethylthiourea, Examples include 1-phenylthiourea.

  The thiol organic acid derivative used in the present invention is a derivative of an organic acid having one or more thiol groups, preferably a carboxylic acid having one or more thiol groups. For example, thiomalic acid, 2-mercaptoethyloctanoic acid Thiol compounds such as esters, 2-mercaptopropionic acid, 3-mercaptopropionic acid, methoxybutyl mercaptopropionate, octyl mercaptopropionate, tridecyl mercaptopropionate, trimethylolpropane tristhiopropionate, pentaerythritol tetrakisthiopropioate Mercaptopropionic acid derivatives such as nates, thioglycolic acid, ammonium thioglycolate, monoethanolamine thioglycolate, methyl thioglycolate, octyl thioglycolate, thioglycolic acid Examples include thioglycolic acid derivatives such as toxibutyl, ethylene glycol bisthioglycolate, butanediol bisthioglycolate, trimethylolpropane tristhioglycolate, pentaerythritol tetrakisthioglycolate, and these can also be obtained as commercial products. it can. Of these, mercaptopropionic acid derivatives and thioglycolic acid derivatives are preferred.

  Thioureas are contained in the topcoat layer in combination of one or more, but the amount is preferably 0.1 to 5% by mass, more preferably based on the resin solid content contained in the topcoat layer. It is 0.5-3 mass%. Further, the thiol organic acid derivative is contained in the topcoat layer in combination of one or more, but the amount is preferably 1 to 20% by mass, more preferably based on the resin solid content contained in the topcoat layer. It is the range of 5-10 mass%. If the amount of thiourea is too small, the effect of improving adhesiveness with silver is poor, and if the amount of thiourea is too large, the discoloration of silver at high temperatures may increase. Moreover, when there are too many thiol organic acid derivatives, the bond strength of a topcoat layer may fall.

  In the present invention, it is more preferable to further combine a silane coupling agent with the thioureas and the thiol organic acid derivative. By combining the silane coupling agent, adhesion after the salt spray test and discoloration prevention after the heat resistance test are further improved.

  As the silane coupling agent used in the present invention, conventionally known silane coupling agents can be used. For example, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (2-methoxyethoxy) silane, vinylmethyldimethoxysilane, 3 -Methacryloxypropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-octanoylthio-1-propyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N- (2-aminoethyl) -3 Aminopropyltrimethoxysilane, 3- (N-phenyl) aminopropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-ureidopropyltriethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-isocyanatopropyltri And methoxysilane.

  The amount of the silane coupling agent used is preferably 1 to 30% by mass, more preferably 5%, based on the resin solids contained in the topcoat layer, combined with thioureas and thiol organic acid derivatives. ˜20 mass%. If the amount is too large, the bond strength of the undercoat resin or topcoat resin may be reduced.

  Although the silver-plated coating body of this invention has a silver thin film layer and a topcoat layer at least on a base material, it is preferable that a topcoat layer is provided on a silver thin film layer. The topcoat resin composition constituting the topcoat layer generally contains a resin such as a thermosetting resin or an ultraviolet curable resin.

  Examples of the thermosetting resin constituting the top coat layer include liquid epoxy resins, unsaturated polyester resins, fluororesins, acrylic resins, melamine resins, and silicon resins described in Japanese Patent Application Laid-Open No. 2000-129448. Examples thereof include silicon acrylic resins described in JP-A-155580, two-component curable polyurethane resins described in JP-A-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 silicone paint) “Omak No. 100 (E) Clear FV” (acrylic silicone series) “Neohard Clear H” (high hardness acrylic series) manufactured by Ohashi Chemical Industry Co., Ltd. Etc. are preferably used.

  On the other hand, when an ultraviolet curable resin is used, the time required for the production process can be shortened. Such an ultraviolet curable resin includes an electron curable resin and is a resin curable by ultraviolet rays, and mainly ethylenically unsaturated groups. Monomers and oligomer compounds having the following are preferably used. 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 and the like, and (meth) acrylic acid ester of an 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.

  In the ultraviolet curable resin, a photopolymerization initiator is used as necessary. 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, particularly preferably 0.5 to 7% by mass with respect to 100% by mass of the ultraviolet curable resin.

  In order to cure the top coat composition, it is sufficient to heat or irradiate electron beam, ultraviolet ray, etc. As means for irradiating electron beam, ultraviolet ray, for example, xenon lamp, halogen lamp, tungsten lamp, high pressure mercury lamp, ultra high pressure Examples thereof include lamp light sources such as 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 to 25 μm, and the ultraviolet curable resin top coat is preferably in the range of 3 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.

  Moreover, you may use a coloring material and an additive together for the above-mentioned topcoat layer as needed. The colorant added to the topcoat layer can be color-tuned by further containing a colorant such as a pigment or dye. It is more preferable that the absorption wavelength of the color 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 there are ordinary methods such as a method of directly dispersing the pigment powder by a dyno mill, a paint shaker, a sand mill, a ball mill, a kneader, a roll, a dissolver, a homogenizer, ultrasonic vibration, a stirrer, and the like. 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 is preferably 0.01 to 10% by weight, more preferably, based on the resin solid content in the total amount of each composition, for example. 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 film is lowered to impair the value of silver plating.

  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 addition amount of the dye is not particularly limited because the concealability varies depending on the type of the dye, but is preferably 0.01 to 10% by mass, more preferably, based on the resin solid content in the total amount of each composition, for example. 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 film is lowered and the value of silver plating is impaired.

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

  As a method for providing the top coat layer, it is common to apply each coating composition by dissolving it in an organic solvent. As a coating method, 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, a die coater method, a curtain coater method, a knife coater method, an air spray method, an airless spray. Any method such as a method or a dip method can be used.

  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, Esters 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, propylene Examples include, but are not limited to, ethers such as 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. These organic solvents are selected depending on the solubility of the undercoat composition and the topcoat composition, but are selected from the viewpoint of improvement on the coated surface and the like. There are many cases.

  Various plastics, metals, glasses, ceramics, 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, polyethylene ( PE) resin, polypropylene (PP) resin, composite resin of these, and fiber reinforced plastic (FRP) reinforced with organic fibers such as nylon fiber and pulp fiber can be mentioned, but are not particularly limited. Examples of the metal include, but are not particularly limited to, iron, aluminum, stainless steel, copper, brass, and the like and those subjected to surface treatment such as rust prevention of these metals. The glass is not particularly limited, such as inorganic glass or plastic glass. In addition, an undercoat layer, a primer coating, a powder coating, an electrodeposition coating, or the like, a general easy-adhesion layer, a rust prevention layer, a colored layer, or the like may be provided on these various substrates.

  As the pre-coating treatment of these base materials, generally, wet processing such as detergent cleaning, solvent cleaning, ultrasonic cleaning and the like for removing substances that inhibit adhesion is preferably performed. In addition to the primer coating as the above-described easy adhesion treatment, dry treatment such as corona treatment, ultraviolet irradiation, electron beam irradiation treatment, and the like may be performed.

  In the present invention, an undercoat layer is not necessarily required, but in order to utilize the good reflectance of the silver thin film layer, it is an effective means to provide an undercoat layer to improve the surface roughness of the substrate. It is desirable to provide an undercoat layer. In that case, it is requested | required that adhesiveness with a base material is good and it is excellent in adhesiveness with the silver thin film layer provided on an undercoat layer. It is also required to form a smooth surface. As an undercoat material, for example, an alkyd polyol, a polyester polyol, an acrylic polyol or the like, a polyol-based paint in which an isocyanate compound is mixed as a curing agent with a polymer or oligomer having a terminal hydroxyl group, and an epoxy compound in which an amine compound is mixed as a curing agent with an epoxy resin The paint or the like is selected 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 it in an organic solvent. Examples of the organic solvent include the same organic solvents that are used when a topcoat layer described later is provided. As a coating method, 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, a die coater method, a curtain coater method, a knife coater method, an air spray method, an airless spray. Any method such as a method or a dip method can be used.

  In the silver-plated coated body of the present invention, a silver thin film layer may be provided directly on various substrates, or a silver thin film layer may be provided on the above-described undercoat layer. The silver thin film layer is preferably provided by a silver mirror plating method because it has a good reflection gloss. Here, a case where a silver thin film layer is formed on the surface of the undercoat layer generally performed by a silver mirror plating method will be described as an example.

  The undercoat layer provided on the surface of the base material is treated with an active treatment liquid for silver mirror containing stannous chloride so that the stannous ions are supported on the surface of the undercoat layer. A silver thin film layer is formed thereon by a silver mirror reaction.

  As a treatment method for treating the undercoat layer with an active treatment liquid for silver mirror containing stannous chloride, a method of immersing a substrate provided with an undercoat layer in an active treatment liquid 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, saccharides such as dextrin, aldehyde compounds such as glyoxal, organic compounds such as hydrazine compounds such as hydrazine sulfate, hydrazine carbonate or hydrazine hydrate, and aqueous solutions such as sodium sulfite or sodium thiosulfate are preferably used. Is done.

  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 the top coat layer is provided on the silver thin film layer, for the purpose of stabilizing the deposited metal silver, a treatment such as immersion in a solution containing an organic compound that reacts with or has affinity with silver or coating the solution is performed. It can be carried out.

  As the organic compound, a nitrogen-containing heterocyclic compound having a mercapto group or a thione group is 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-mercapto-naphthothiazole, 3-ethyl-benzothiazoline-2-thione, 3-dodecyl-benzothiazoline-2-thione, 2-mercapto-4,5-diphenyloxazole, 2-mercaptobenzoxazole 3-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- -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 -Diphenyl-s-triazolino [1,2-a] -s-triazoline and the like.

  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 polycarbonate plate was degreased, washed with water and dried. Polyol-based undercoat resin (Mirror Shine Undercoat Clear D1 manufactured by Ohashi Chemical Industries) and isocyanate-based curing agent (Raster Under Curing Agent N for gun plating manufactured by Ohashi Chemical Industries) and thinner (methyl ethyl ketone and butyl cellsolve in a ratio of 1: 1) The mixture was mixed at a mass ratio of 10: 2: 10 to obtain an undercoat paint. This undercoat paint was applied by spraying using a spray gun and then dried by heating at 80 ° C. for 2 hours to form an undercoat layer having a thickness of 20 μm.

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

  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, washed with deionized water, and then dried in a dryer at 70 ° C. for 30 minutes. I let you.

  Next, a top coat layer was provided on the silver mirror plating layer. Acrylic silicon-based topcoat paint (Ohmak No. 100 (E) Clear FV, manufactured by Ohashi Chemical Industries), silicone-based curing agent (curing agent W, manufactured by Ohashi Chemical Industry), thinner (methyl ethyl ketone and butyl cellsolve in a ratio of 1: 1. Mixed) at a mass ratio of 6: 1: 6, and 1-methylthiourea (dissolved in methyl isobutyl ketone at a concentration of 2% by mass) is 2.0% by mass with respect to the resin solid content of the topcoat layer. As a result, a top coat paint was obtained. This top coat paint was spray-coated on the silver thin film layer using a spray gun, and then heated and dried at 80 ° C. for 60 minutes to form a top coat layer having a thickness of 15 μm. In this way, a silver-plated coated body obtained by silver-plating a polycarbonate plate was obtained.

(Comparative Example 2)
A silver-plated coated body was obtained in the same manner as in Comparative Example 1 except that 1-methylthiourea in the topcoat layer of Comparative Example 1 was replaced with 1,3-diethylthiourea.

(Comparative Example 3)
A silver-plated coated body was obtained in the same manner as in Comparative Example 1 except that 1-methylthiourea in the topcoat layer of Comparative Example 1 was replaced with 1-naphthylthiourea.

Example 1
A silver-plated coated body was prepared in the same manner as in Comparative Example 1 except that pentaerythritol tetrakisthiopropionate was added to the top coat layer of Comparative Example 1 so as to be 7% by mass with respect to the resin solid content of the top coat layer. Obtained.

(Example 2)
A silver-plated coated body in the same manner as in Comparative Example 2 except that the topcoat layer of Comparative Example 2 contains trimethylolpropane tristhiopropionate so as to be 7% by mass with respect to the resin solid content of the topcoat layer. Got.

(Example 3)
A silver-plated coated body is obtained in the same manner as in Comparative Example 3, except that the topcoat layer of Comparative Example 3 contains butanediol bisthioglycolate in an amount of 7% by mass with respect to the resin solid content of the topcoat layer. It was.

(Comparative Example 4)
1-methylthiourea in the topcoat layer of Comparative Example 1 was replaced with 3-aminopropyltriethoxysilane and contained in an amount of 10% by mass with respect to the resin solid content of the topcoat layer. A silver-plated coating was obtained.

(Comparative Example 5)
1-methylthiourea in the topcoat layer of Comparative Example 1 was replaced with 3-mercaptopropyltrimethoxysilane, and contained in an amount of 10% by mass based on the resin solid content of the topcoat layer. A silver-plated coating was obtained.

(Comparative Example 6)
The same procedure as in Comparative Example 1 was conducted except that 1-methylthiourea in the topcoat layer of Comparative Example 1 was replaced with 3-isocyanatopropyltriethoxysilane and contained so as to be 10% by mass relative to the resin solid content of the topcoat layer. A silver-plated coating was obtained.

Example 4
A silver-plated coated body was prepared in the same manner as in Example 1 except that 3-aminopropyltriethoxysilane was added to the top coat layer of Example 1 so as to be 5% by mass with respect to the resin solid content of the top coat layer. Obtained.

(Example 5)
A silver-plated coated body was prepared in the same manner as in Example 2 except that 3-aminopropyltriethoxysilane was added to the top coat layer of Example 2 so as to be 5% by mass with respect to the resin solid content of the top coat layer. Obtained.

(Example 6)
A silver-plated coated body was prepared in the same manner as in Example 3 except that 3-aminopropyltriethoxysilane was added to the topcoat layer of Example 3 so as to be 5% by mass with respect to the resin solid content of the topcoat layer. Obtained.

<Evaluation test method>
The following evaluation test was done about the silver plating coating body obtained in Examples 1-6 and Comparative Examples 1-6. The results are shown in Table 1.

1) Evaluation A (Adhesiveness)
Use the TAIYU Equipment Co., Ltd. Super Cutter Guide so that it reaches the polycarbonate base material from the top coat layer surface of the silver-plated body, make a crosscut at 2mm intervals, press the cellophane tape strongly, and then peel off. Judgment based on criteria.
○: The top coat is good with no peeling between the silver film.
(Triangle | delta): The topcoat of the center part of the crosscut peeled off a little between silver films.
X: The top coat was peeled between the silver film and the entire crosscut part.
XX: The top coat was peeled from the entire silver film regardless of the presence or absence of cross cut.

2) Evaluation B (discoloration after heat test)
Using CONSTANT LOW TEMPERATURE / HUMIDITY CHAMBER THN054PB manufactured by Advantech, the product was stored for 10 days in an environment of 80 ° C. (no humidification), then allowed to stand at room temperature for 2 hours, and then the appearance was evaluated.
○: Discoloration is not seen even when compared with untreated products.
Δ: Discoloration can be seen when compared with untreated products, but discoloration is not noticeable when viewed alone.
X: Discoloration is clearly observed even when viewed alone.
XX: Silver is blackened as a whole, and gloss is lost.

3) Evaluation C (Adhesiveness after salt spray test 1)
A salt spray tester from Suga Test Co., Ltd., model STP-90, sprayed with 5% salt water in a 35 ° C. environment and conducted a salt spray test for 5 days. And evaluated according to the same criteria.

4) Evaluation D (Adhesiveness after salt spray test 2)
After cross-cutting in the same manner as in evaluation A, a 5-day salt spray test is performed in the same manner as in evaluation C. After washing and drying, the cellophane tape is strongly pressed from above the cross-cut portion, peeled off, and evaluated as described above. Evaluation was performed according to the same criteria as A.

  As is apparent from the above results, it can be seen that a silver-plated coated body having excellent adhesiveness and anti-discoloration property can be obtained by the present invention.

Claims (2)

  A silver-plated coated body having at least a silver thin film layer and a topcoat layer on a substrate, wherein the topcoat layer contains a thiourea and a thiol organic acid derivative.   The silver-plated coated body according to claim 1, wherein the top coat layer further contains a silane coupling agent.