JP6545626B2 - Silver plating body - Google Patents

Description

  The present invention relates to a silver-plated coated body, and more particularly to a silver-plated coated body in which the deterioration of the coating which occurs when used for a long time is improved.

  A silver-plated coated body having a silver plating layer on a substrate is processed to a metal or plastic surface because silver has the highest reflective gloss among metals, and is used as a design material, a reflective material, etc. . In addition, it is a material that can be effectively used as, for example, an electromagnetic wave shielding material by utilizing the high conductivity of silver.

  The silver plating layer is a useful material that exhibits high reflective gloss and high conductivity even if it is a thin film, but its mechanical strength is weak because it is thin and soft. In order to compensate for such a defect, it is known to provide a top coat layer on the surface using various hard coat materials. For example, JP-A-2000-129448 describes that liquid epoxy resin, unsaturated polyester resin, fluorocarbon resin, acrylic resin, melamine resin, silicone resin and the like can be used for the top coat layer, and JP-A-2003-155580 JP-A-2004-203014 (Patent Document 1) and the like disclose that a silicone acrylic paint having a specific glass transition temperature is used. Further, JP-A-2008-110101, JP-A-2008-176050, and the like describe that an ultraviolet-curable resin or an electron beam-curable resin may be used.

  However, when a silver-plated coated body having such a top coat layer is used for a long time, there are problems such as discoloration of the silver plating layer and peeling of the top coat layer from the silver plating layer. Deterioration of a silver-plated product is promoted by various external factors, but in particular, color change due to heat, corrosion due to salt, color change due to moisture or corrosion is a factor that causes deterioration of the paint.

  In the past, attempts have been made to prevent deterioration of a silver-plated product, for example, in JP-A 2004-169157 (Patent Document 2), a silver-plated layer reacts with silver or has affinity with silver. No. 2011-128501 (Patent Document 3) describes that a discoloration inhibitor layer containing the same compound is provided. In addition, it is also attempted to prevent deterioration of the silver-plated product by providing a top coat layer containing a specific compound. For example, Japanese Patent Application Laid-Open No. 2003-238901 discloses a top coat layer containing a benzothiazole based metal deactivator, and Japanese Patent Application Laid-Open No. 2007-169685 discloses a top coat layer containing a benzotriazole compound. There is. However, even with these methods, it has been difficult to cope with various external factors that change during long-term storage, and in particular, it has been difficult to achieve both heat discoloration of the silver plating layer and corrosion due to salt. .

  As a method of solving the above problems in a compatible manner, Japanese Patent Application Laid-Open No. 2013-202818 (Patent Document 4) discloses a top coat layer containing thioureas and a thiol organic acid derivative. The same publication shows that it is possible to prevent both heat discoloration and corrosion due to salt. However, it has been found that the water resistance is lowered by this method if the examination is made in detail. That is, it has been found that the deterioration of the coating proceeds to ordinary water containing little salt, and a solution is required.

  On the other hand, it is thought that the above-mentioned patent document 1 contains a specific ultraviolet absorber in the top coat layer, for example, because the problem of discoloration of the silver plating layer and peeling of the top coat layer as described above is accelerated by ultraviolet light. A method is described. However, even with these methods, a satisfactory improvement effect on the deterioration of the paint has not been obtained.

Unexamined-Japanese-Patent No. 2004-203014 JP 2004-169157 A JP, 2011-128501, A JP, 2013-202818, A

  An object of the present invention is to provide a silver-plated coated body in which the deterioration of the coating which occurs when used for a long time is improved, and in particular, it has sufficient water resistance while preventing heat discoloration and corrosion by salt. It is providing a silver plating paint body.

The above object of the present invention is achieved by the invention described below.
The topcoat layer is represented by the following general formula (1) in a silver-plated coated body having on the substrate at least a silver plating layer and a topcoat layer adjacent thereto containing a thermosetting resin or an ultraviolet curing resin. The thiourea derivative to be added is added in an amount of 0.1 to 1% by mass based on the solid content of the top coat, and the triazine derivative represented by the following general formula (2) is based on the solid content of the top coat The top coat layer has a thickness of 10 μm or more when it contains a thermosetting resin, and the thickness of the top coat layer when it contains a UV-curable resin. Silver-plated coated body characterized by having a diameter of 3 μm or more .

R ₁ and R ₂ in the general formula (1) represent a hydrogen atom or a hydrocarbon group having 10 or less carbon atoms. However, R ₁ and R ₂ may not be hydrogen atoms at the same time, and may be the same or different. Further, R ₁ and R ₂ may be linked to form a ring.

In the general formula (2), R ₃ and R ₄ represent an aryl group, and R ₅ represents an alkyl group having 4 or more carbon atoms or a substituent having 4 or more carbon atoms represented by the following general formula (3).

In formula (3), R ₆ represents an alkylene group, the linking group L represents -O-, -COO- or -OCO-, and R ₇ represents an alkyl group.

  According to the present invention, it is possible to provide a silver-plated coated body having sufficient water resistance while preventing heat discoloration and corrosion by salt.

  The present invention will be described in detail below.

  The silver-plated coated body of the present invention is a silver-plated coated body having at least a silver-plated layer and a top coat layer in this order on a substrate, and the top coat layer is represented by the above-mentioned general formula (1) It contains a thiourea derivative and a triazine derivative represented by the above-mentioned general formula (2).

  As a method of preventing both the color change by heat of a silver plating coating and corrosion by salt content, the silver plating coating which contains thioureas and a thiol organic acid derivative in a top coat layer was known conventionally (patent documents) 4). However, it has been found that with this method the water resistance, ie the resistance to water which is largely salt free, is rather reduced. As a result of intensive investigations conducted by the present inventors, color change due to heat without lowering water resistance by using the thiourea derivative represented by the general formula (1) and the triazine derivative represented by the general formula (2) in combination It has been found that it is possible to obtain a silver-plated product which can prevent both corrosion and corrosion due to salt. The triazine derivative used in the present invention is generally commercially available as a UV absorber, but it has been known that such an effect can be obtained by using it in combination with the thiourea derivative represented by the general formula (1). It was not.

  The top coat layer of the present invention contains a thiourea derivative represented by the following general formula (1).

R ₁ and R ₂ in the general formula (1) represent a hydrogen atom or a hydrocarbon group having 10 or less carbon atoms. However, R ₁ and R ₂ may not be hydrogen atoms at the same time, and may be the same or different. Further, R ₁ and R ₂ may be linked to form a ring.

Examples of the hydrocarbon group having 10 or less carbon atoms include an alkyl group, a cycloalkyl group, an alkenyl group and an aryl group. Examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, heptyl group and decyl group. Examples of the cycloalkyl group include cyclopentyl group, cyclohexyl group, cyclooctyl group and the like. Examples of the alkenyl group include ethenyl group, propenyl group, pentenyl group, heptenyl group, nonenyl group and the like, and aryl groups include phenyl group, methylphenyl group, ethylphenyl group, dimethylphenyl group and the like. It can be mentioned. Furthermore, these groups may have a substituent such as an alkoxy group, a phenyl group or a hydroxy group. Moreover, as an example which R < ₁ > and R < ₂ > connect and form a ring, the example which connects with ethylene group and forms an imidazoline ring can be mentioned, for example.

  The thiourea derivatives used in the present invention may be used alone or in combination of two or more. It is preferable that the addition amount to the topcoat layer of the thiourea derivative used for this invention is 0.1-1 mass% with respect to the solid content of a topcoat. When the addition amount is too small, a sufficient effect can not be obtained, and when the addition amount is too large, the coating strength decreases. When adding two or more types in combination, it is preferable to make it the said addition amount by a total amount. Specific examples of the thiourea derivative used in the present invention are shown below, but the present invention is not limited thereto.

  In the present invention, the topcoat layer contains a triazine derivative represented by the following general formula (2).

In the general formula (2), R ₃ and R ₄ represent an aryl group, and R ₅ represents an alkyl group having 4 or more carbon atoms or a substituent having 4 or more carbon atoms represented by the following general formula (3).

In formula (3), R ₆ represents an alkylene group, the linking group L represents -O-, -COO- or -OCO-, and R ₇ represents an alkyl group.

Examples of the aryl group of R ₃ and R ₄ include phenyl group, methylphenyl group, dimethylphenyl group and biphenyl group. Examples of the alkyl group having 4 or more carbon atoms for R ₅ include hexyl and nonyl. The alkylene group of R ₆ preferably has 3 or less carbon atoms, and examples thereof include a methylene group, an ethylene group and a trimethylene group. Furthermore, the alkylene group of R ₆ may have a substituent such as a methyl group or a hydroxy group. The alkyl group of R ₇ is preferably one having 1 to 15 carbon atoms, and examples of linear alkyl groups include methyl, octyl, dodecyl and tridecyl groups, and branched alkyl groups include ethyl pentyl, Ethylhexyl group etc. can be mentioned.

  The triazine derivatives used in the present invention may be used alone or in combination of two or more. The amount of the triazine derivative used in the present invention to be added to the topcoat layer is preferably 1 to 20% by mass, more preferably 2 to 10% by mass, relative to the solid content of the topcoat. When the addition amount is too small, a sufficient effect can not be obtained, and when the addition amount is too large, the coating strength decreases. When adding two or more types in combination, it is preferable to make it the said addition amount by a total amount. Specific examples of the triazine derivative used in the present invention are shown below, but the present invention is not limited thereto.

  A coating composition containing a thermosetting resin is generally used as a coating composition used to coat the top coat layer of the silver-plated coated body of the present invention. As the thermosetting resin, for example, epoxy resins, unsaturated polyester resins, melamine resins, silicone resins described in JP-A-2000-129448, JP-A-2002-256454 and JP-A-2003-155580. Urethane resin and acrylic silicone resin etc. can be mentioned. Among these, a coating composition containing a melamine resin, a urethane resin and an acrylic silicone resin is preferably used because application is easy.

  As a coating composition containing a urethane resin, a two-component curable urethane-based coating composition obtained by mixing a polymer or oligomer such as an alkyd polyol, a polyester polyol, an acrylic polyol and an isocyanate compound as a curing agent is preferable. As a coating composition containing an acrylic silicone resin, an acrylic silicone based coating in which an acrylic resin and an alkoxysilane compound (silicon based curing agent) as a curing agent are mixed is preferable.

  As a thermosetting coating generally marketed, for example, "ORIZITOK # 100" (acrylic silicone-based paint) manufactured by Origin Electric Co., Ltd., "Hypolard No. 800S" manufactured by Ohashi Chemical Industry Co., Ltd. (acrylic silicone-based paint) ), "Omax No. 100 (E) clear FV" (acrylic silicone based paint), or "neohard clear H" (melamine based paint), etc. are preferably used.

  As a method for providing a top coat layer made of a thermosetting resin, it is general to dissolve or dilute the above-described coating composition in an organic solvent. Such organic solvents include, for example, cyclohexane, hydrocarbons such as Solvesso 100 (trade name, manufactured by Exxon Chemical Company), cellosolve, methyl cellosolve, ethers such as butyl cellosolve, carbitol, diethyl carbitol, methanol, ethanol, isopropyl Alcohol, butyl alcohol, alcohols such as cyclohexanol, ethyl acetate, n-butyl acetate, isobutyl acetate, amyl formate, isoamyl acetate, isobutyl acetate, butyl propionate, isopropyl butyrate, ethyl butyrate, butyl butyrate, alkyl esters, Methyl lactate, ethyl lactate, methyl oxyacetate, ethyl oxyacetate, butyl oxyacetate, methyl methoxyacetate, ethyl methoxyacetate, butyl methoxyacetate, methyl ethoxyacetate, ethyl ethoxyacetate etc , 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, Ethers such as propylene glycol monoethyl ether acetate and propylene glycol monopropyl ether acetate; ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 2-heptanone and 3-heptanone;

  These organic solvents are appropriately selected depending on the solubility of the coating composition and from the viewpoint of improving the surface quality of the coated surface and the like, and may be used alone but are often used in combination of two or more. Moreover, as a coating method of the coating composition used for coating an undercoat layer and a topcoat layer, it may be based on the conventionally well-known coating method, for example, a gravure roll system, a reverse roll system, a dip roll system, a bar coater system Any of a knife coater method, an air spray method, an airless spray method, a dip method and the like can be used.

  In order to apply a top coat layer, a coating composition containing a UV curable resin can also be used. The UV curable resin to be preferably used is a resin which contains an electron curable resin and is cured by UV, and monomers and oligomer compounds mainly having an ethylenically unsaturated group are preferably used. Specifically, amide-based monomers, (meth) acrylate monomers, urethane (meth) acrylates, polyester (meth) acrylates, epoxy (meth) acrylates and the like can be mentioned. Amide-based monomers include amide compounds such as N-vinyl pyrrolidone, N-vinyl caprolactam, acryloyl morpholine and the like. As (meth) acrylate monomers, hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-phenylpropyl acrylate, etc., phenoxyethyl (meth) Acrylates of alkylene oxide adducts of phenols such as acrylates and their halogen nucleus substitutes, mono or di (meth) acrylate of ethylene glycol, mono (meth) acrylate of methoxy ethylene glycol, mono or di (meth) of tetra ethylene glycol Mono- or di (meth) acrylates of glycols, such as acrylates, mono or di (meth) acrylates of tripropylene glycol; trimethylolpropane tri (meth) acrylate, PE Taerythritol tri (meth) acrylate and polyols such as pentaerythritol tetra (meth) acrylate, dipentaerythritol hexaacrylate and the like, and (meth) acrylic acid esters of alkylene oxides thereof, isocyanuric acid EO modified di- or tri (meth) acrylates, etc. Can be mentioned.

  As a urethane (meth) acrylate oligomer, the reaction product etc. which made the hydroxyl group containing (meth) acrylate further react with respect to a polyol and organic polyisocyanate reaction material are mentioned. Here, examples of the polyol include low molecular weight polyols, polyethylene glycol and polyester polyols, and examples of the low molecular weight polyols include ethylene glycol, propylene glycol, cyclohexanedimethanol and 3-methyl-1,5-pentanediol. Polyether polyols include polyethylene glycol and polypropylene glycol, etc. Polyester polyols include these low molecular weight polyols and / or polyether polyols and 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 hydroxyl group-containing (meth) acrylates include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate.

  As polyester (meth) acrylate oligomer, the dehydration condensation product of polyester polyol and (meth) acrylic acid is mentioned. Examples of polyester polyols include ethylene glycol, polyethylene glycol, cyclohexanedimethanol, 3-methyl-1,5-pentanediol, propylene glycol, polypropylene glycol, low molecular weight polyols such as 1,6-hexanediol and trimethylolpropane, and these The reaction products from polyols such as alkylene oxide adducts of the above, and acid components such as adipic acid, succinic acid, phthalic acid, dibasic acids such as hexahydrophthalic acid and terephthalic acid, or anhydrides thereof. Epoxy acrylate is obtained by addition reaction of unsaturated carboxylic acid such as (meth) acrylic acid with epoxy resin, and epoxy (meth) acrylate of bisphenol A type epoxy resin, epoxy (meth) of phenol or cresol novolac type epoxy resin Acrylate, (meth) acrylic acid addition reaction product of diglycidyl ether of polyether, etc. may be mentioned.

  Photoinitiators include benzoin, benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether and their alkyl ethers; 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-ethyl anthraquinone, 2-tert-butyl anthraquinone, 1-chloroanthraquinone and 2-amyl anthraquinone; 2,4-dimethylthioxa Thioxanthones such as ton, 2,4-diethylthioxanthone, 2-chlorothioxanthone and 2,4-diisopyrthioxanthone; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; such as 2,4,6-trimethyl benzoyl diphenyl phosphine oxide Monoacyl phosphine oxides or bisacyl phosphine oxides; 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.

  0.01-20 mass% is preferable with respect to ultraviolet curable resin, and, as for content of the said photoinitiator, 0.5-7 mass% is especially preferable.

  In order to cure the coating composition used to coat the top coat layer, heating may be performed in the case of a thermosetting resin, and electron beams, ultraviolet rays, etc. may be irradiated in the case of an ultraviolet curable resin. . As a means for irradiating an electron beam and ultraviolet light, lamp light sources such as xenon lamp, halogen lamp, tungsten lamp, high pressure mercury lamp, super high pressure mercury lamp, metal halide lamp, medium pressure mercury lamp, low pressure mercury lamp, argon ion laser, YAG laser, excimer Laser light sources, such as a laser and a nitrogen laser, etc. are mentioned.

  The thickness of the top coat layer made of a thermosetting resin is preferably in the range of 10 to 25 μm, and the top coat made of an ultraviolet curable resin is preferably in the range of 3 to 10 μm. If the top coat layer is too thin, the function as a role of protecting the silver plating layer can not be obtained, and a uniform coating film can not be formed. On the other hand, if it is too thick, the peripheral portion becomes locally thicker. Further, the light transmission distance becomes long and the loss of light increases, which is not preferable because the reflectance of the silver plating layer is lowered.

  In order to improve the design, a coloring material such as a pigment or a dye may be added to the top coat layer. Examples of the pigment include organic pigments such as carbon black, quinacridone, naphthol red, cyanine blue, cyanine green, hanza yellow, etc .; inorganic substances such as titanium oxide, aluminum oxide, calcium carbonate, barium sulfate, mica, red iron oxide, complex metal oxide etc. Although a pigment is mentioned, it is not limited to these. One or two or more selected from these pigments can be used in combination. Dispersion of the pigment is not particularly limited, and it is possible to disperse the pigment powder directly by ordinary methods such as Dino meal, paint shaker, sand mill, ball mill, kneader, roll, dissolver, homogenizer, ultrasonic vibration, stirrer, etc. Is used. At that time, it is possible to use dispersing agents, dispersing aids, thickeners, coupling agents and the like. The addition amount of the pigment is not particularly limited because the hiding ability varies depending on the kind of the pigment, but usually, it is 0.1 to 5% by mass with respect to the solid content of the cured resin component in each composition.

  Examples of dyes include azo dyes, anthraquinone dyes, indichoid dyes, sulfide dyes, triphenylmethane dyes, xanthene dyes, alizarin dyes, acridine dyes, quinoneimine dyes, thiazole dyes, methine dyes, nitro dyes and nitroso dyes. These include, but are not limited to. One or more selected from these dyes can be used in combination. The addition amount of the dye is not particularly limited because the concealability varies depending on the type of the dye, but is usually 0.1 to 5% by mass based on the solid content of the cured resin component in the total amount of each composition.

  The topcoat layer may further contain, as additives, leveling agents, metal powders, glass powders, antibacterial agents, antioxidants, light stabilizers, and the like.

  Various plastics, metals, glasses, rubbers, etc. are used as a base material which the silver plating paint object of the present invention has. Examples of plastics include polyester resins such as polycarbonate resin, acrylic resin, ABS resin, vinyl chloride resin, epoxy resin, phenol resin, polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, fluorine resin, polypropylene ( PP) resin, resin composited with these, and fiber reinforced plastic (FRP) reinforced with organic fiber such as nylon fiber and pulp fiber, etc. may be mentioned, but it is not particularly limited. Examples of the metal include iron, aluminum, stainless steel, copper, brass and the like, but are not particularly limited. The glass is also not particularly limited, such as inorganic glass or plastic glass.

  The silver-plated product of the present invention has a silver-plated layer on a substrate, but depending on the type of the substrate, adhesion between the silver-plated layer and the substrate may not be sufficient. In such a case, an undercoat layer may be provided between the substrate and the silver plating layer to improve the adhesion between the silver plating layer and the substrate. Furthermore, the substrate may be pretreated for the purpose of improving the adhesion between the substrate and the undercoat layer. As the pretreatment method, there may be mentioned wet processing such as detergent, solvent washing and washing treatment by ultrasonic washing, and dry treatment such as corona treatment, ultraviolet irradiation and electron beam irradiation treatment. Further, depending on the type of the substrate, for example, a primer layer may be provided between the substrate and the undercoat layer in order to improve adhesion in polypropylene and in iron and aluminum in order to prevent corrosion.

  The undercoat layer is required to have excellent adhesion to the silver plating layer provided on the undercoat layer. It is also required to form a smooth surface. As the undercoat layer, in addition to the undercoat layers described in, for example, JP-A-10-309774 and JP-A-2002-256455, polymers or oligomers such as alkyd polyols, polyester polyols, and acrylic polyols and curing agents It is possible to use a urethane-based paint composition in which an isocyanate compound is mixed, and an undercoat layer obtained by applying an epoxy-based paint composition in which an amine compound is mixed with an epoxy resin as a curing agent. These can be appropriately selected and used based on the properties required as a substrate and a 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 above-mentioned coating composition by dissolving or diluting it in an organic solvent. The selection of the organic solvent and the coating method are the same as in the case of the top coat.

  The silver-plated coated body of the present invention has a silver-plated layer on a substrate or on an undercoat layer provided on the substrate. A preferred method for forming a silver plating layer is to treat the surface on which the silver plating layer is to be formed with a silver mirror activation treatment solution containing stannous chloride to carry stannous ions on the surface of the undercoat layer, and to activate this. A silver mirror layer is to form a silver plating layer on the treated undercoat layer.

  As a treatment method for treating with a silver mirror activation treatment solution containing stannous chloride, a method of immersing the surface on which a silver plating layer is to be formed in a silver mirror activation treatment solution; There is a method of applying an active processing solution for silver mirror containing tin or the like. Although it can select arbitrarily by the shape etc. of a base material, as a coating method, the spray application which does not choose the shape of a base material especially is suitable. Furthermore, it is preferable to wash the activated processing solution that has been excessively attached to the surface with deionized water or purified distilled water.

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

  After the step of treatment with the silver mirror activation treatment solution, a step of activation treatment with silver ions may be provided. For example, treatment with a silver nitrate-containing treatment solution is preferable because it is simple and easy to perform treatment with silver ions. The concentration of the aqueous silver nitrate solution used in this step is preferably a dilute solution of 0.1 mol / L or less, and this solution is brought into contact with the stannous chloride-treated undercoat layer. When this silver ion treatment is performed, it is preferable to wash with deionized water after the silver ion treatment. For these activation processes, spray application in which a new solution is always supplied is preferable.

  The formation of the silver plating layer by the silver mirror reaction is carried out on the surface of the undercoat layer surface subjected to the above-mentioned activation treatment, 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 be mixed. As a result, oxidation-reduction reaction occurs to precipitate metallic silver, thereby forming a silver film and forming a silver plating layer.

  Examples of the reducing agent solution include an aqueous solution of an aldehyde compound such as glucose and glyoxal, an aqueous solution of a hydrazine compound such as hydrazine sulfate, hydrazine carbonate or hydrazine hydrate, and an aqueous solution such as sodium sulfite or sodium thiosulfate.

  Several additives can also be added to the ammoniacal silver nitrate aqueous solution in order to form a 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 thereof include amino alcohol compounds such as amines, triethanolamine and triisopropanolamine, and amino acids such as glycine, alanine and glycine sodium or 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 that they are mixed on the surface on which the silver plating layer is formed, two aqueous solutions are mixed in advance, and this mixed solution is used as a spray gun or the like. Method of spraying on the surface of the undercoat layer, spraying using a concentric spray gun having a structure in which two aqueous solutions are mixed and immediately discharged in the head of a spray gun, and two aqueous solutions are sprayed by two spray nozzles. There are a method of spraying and spraying each from a double-headed spray gun, and a method of spraying two aqueous solutions simultaneously using two separate spray guns. These can be chosen arbitrarily according to the situation.

  Subsequently, the surface of the silver-plated layer is preferably washed with deionized water or purified distilled water to remove the solution after the silver mirror reaction and the like remaining on the surface. Further, before providing the above-described top coat layer on the silver plating layer, for the purpose of stabilizing the deposited metal silver, the substrate is dipped or coated with a solution containing an organic compound having a reaction or affinity with silver. 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 compound of the present invention described above can also be effectively used. Examples of the heterocyclic ring possessed by the nitrogen-containing heterocyclic compound include an imidazole ring, an imidazoline ring, a thiazole ring, a thiazoline ring, an oxazole ring, an oxazoline ring, a pyrazoline ring, a triazole ring, a thiadiazole ring, an oxadiazole ring, a tetrazole ring and a pyridine ring And pyrimidine ring, pyridazine ring, pyrazine ring, triazine ring, quinoline ring and the like, among which imidazole ring, triazole ring and tetrazole ring are preferable. 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-benzoimidazoline-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-methylpyrazoline-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 and the like.

  Hereinafter, the present invention will be described using examples, but of course the present invention is not limited by this description. In the following description,% or part as a unit is on a mass basis unless otherwise specified.

  An acrylic polyol resin (Mirror Shine undercoat clear D-1 manufactured by Ohashi Chemical Industry Co., Ltd.), an isocyanate curing agent (hardener N for mirror Shine undercoat manufactured by Ohashi Chemical Industry) and thinner (methyl ethyl ketone and butyl cell solb 1: 1) were mixed at a mass ratio of 10: 2: 10, respectively, to obtain a urethane-based paint composition for an undercoat layer. The coating composition was applied to a surface of the ABS resin plate washed with isopropanol and dried with a spray gun and then dried by heating at 80 ° C. for 1 hour to form a 20 μm thick undercoat layer.

  A silver mirror activation treatment solution containing 0.1 mol of hydrochloric acid and 0.1 mol of stannous chloride is adjusted to 1000 g with water, the above undercoat layer is sprayed with a spray gun to perform activation treatment, and then deionization Washed with water. Subsequently, 0.05 mol of silver nitrate was dissolved in water to make 1000 g, and this solution was sprayed with a spray gun to perform activation treatment with silver ions, and then washed with deionized water.

  The silver mirror plating solution was prepared as follows. Separately, a silver nitrate solution was prepared by dissolving 20 g of silver nitrate in deionized water to 1000 g, and separately, 100 g of a 28% aqueous ammonia solution and 5 g of monoethanolamine in deionized water to prepare an ammonia solution of 1000 g. Before use, the silver nitrate solution and the ammonia solution were mixed 1: 1 to obtain an ammoniacal silver nitrate solution. Next, a reducing agent solution was prepared by dissolving 10 g of hydrazine sulfate, 5 g of monoethanolamine, and 10 g of sodium hydroxide in deionized water to make 1000 g.

  The ammoniacal silver nitrate solution thus obtained and the reducing agent solution are simultaneously sprayed using a double-head spray gun to form a silver plating layer, washed with deionized water, and sufficiently removing surface water. And dried at 45 ° C. for 30 minutes.

(Comparative example 1)
A top coat layer was provided on the silver plating layer. Base resin of acrylic silicone paint (Omak No. 100 (E) clear FV made by Ohashi Chemical Industry Co., Ltd.), silicone hardener (hardener W for Omak No. 100 made by Ohashi Chemical Co., Ltd.), thinner (methyl ethyl ketone and butyl cellosolve 1 A mixture of 1) and 1) was mixed at a mass ratio of 6: 1: 6 to obtain an acrylic silicone-based paint composition for the top coat layer, and the above-mentioned silver plating layer was spray-coated with a spray gun. It was dried by heating at 80 ° C. for 30 minutes to form a top coat layer of 15 μm in thickness. Thus, a silver-plated coated body in which an ABS resin was plated with a silver mirror was obtained.

(Comparative example 2)
Except that the coating composition for the top coat layer of Comparative Example 1 contains thiourea derivative T-1 in an amount of 0.3% based on the resin solid content of the coating composition for the top coat layer. A silver-plated coated body was obtained in the same manner as in Comparative Example 1.

(Comparative example 3)
Comparative Example 1 except that the coating composition for the top coat layer of Comparative Example 1 contains triazine derivative P-7 in an amount of 5% based on the resin solid content of the coating composition for the top coat layer. In the same manner as in 1, a silver-plated product was obtained.

(Examples 1 to 7)
In the coating composition for the top coat layer of Comparative Example 1, the thiourea derivative and the triazine derivative in the combinations shown in Table 1 are each 0.3 for the resin solid content of the coating composition for the top coat layer. A silver-plated coated body was obtained in the same manner as in Comparative Example 1 except that the content was made to be% and 5%.

(Comparative example 4)
The coating composition for the top coat layer of Comparative Example 1 contains thiourea in an amount of 0.3% based on the resin solid content of the coating composition for the top coat layer, and triazine derivative P-7 A silver-plated coated body was obtained in the same manner as in Comparative Example 1 except that the coating composition for top coat layer contained 5% of the resin solid content.

(Comparative example 5)
In the paint composition for the top coat layer of Comparative Example 1, guanylthiourea is contained in an amount of 0.3% based on the resin solid content of the paint composition for the top coat layer, and triazine derivative P-7 A silver-plated coated body was obtained in the same manner as in Comparative Example 1 except that the coating composition for top coat layer contained 5% of the resin solid content.

(Comparative example 6)
The coating composition for the top coat layer of Comparative Example 2 contains pentaerythritol tetrakisthiopropionate (PEMP) in an amount of 5% based on the resin solid content of the coating composition for the top coat layer. A silver-plated coated body was obtained in the same manner as in Comparative Example 2 except for the above.

(Comparative example 7)
Comparative Example 6 Comparative Example 6 except that the coating composition for the top coat layer contained 3-aminopropyltriethoxysilane in an amount of 5% based on the resin solid content of the coating composition for the top coat layer. In the same manner as in Example 6, a silver-plated product was obtained.

<Evaluation method>
(Heat resistance test)
The silver-plated products obtained in the above-described Examples and Comparative Examples were stored for 10 days under an environment of 80 ° C. Thereafter, the heat was released for 2 hours at normal temperature, and the color change was evaluated by the color difference (ΔE), and the color change was judged based on the following criteria.
;; ΔE (color difference) ≦ 2.0
Δ: 2.0 <ΔE ≦ 5.0
×; 5.0 <ΔE

(Salt water resistance test)
A cross was scratched with a cutter so as to reach the ABS substrate from the top coat layer surface with respect to the silver-plated coated bodies obtained in Examples and Comparative Examples. These samples were sprayed with a 5% saline solution at 35 ° C. for 10 days in a salt spray tester (type STP-90) manufactured by Suga Test Co., Ltd. The salt-sprayed sample was washed with water, dried, and a cellophane tape was strongly attached from above the scratched portion of the cross, and then the tape was peeled off, and it was judged from the peeling state of the coating based on the following criteria.
○: The width of the widest part of the paint peeling is less than 2 mm from the center of the cut line ;; The width of the widest part of the paint peeling is 2 mm or more and less than 4 mm from the center of the cut line The width of the part is 4 mm or more from the center of the cut line

(Moisture resistance test)
The cross-wound sample with the cutter as in the salt spray test was stored for 10 days in an environment of temperature 65 ° C. and humidity 95%. Thereafter, the sample was washed with water, dried, and a cellophane tape was strongly attached from above the scratched portion of the cross, and then the tape was peeled off, and it was judged from the peeling state of the coating based on the following criteria.
○: The width of the widest part of the paint peeling is less than 2 mm from the center of the cut line ;; The width of the widest part of the paint peeling is 2 mm or more and less than 4 mm from the center of the cut line The width of the part is 4 mm or more from the center of the cut line

(Water resistance test)
After immersing the silver-plated coated bodies obtained in Examples and Comparative Examples in warm water at 40 ° C. for 10 days, after washing with water and drying, the color change was evaluated by color difference (ΔE) and judged based on the following criteria.
○: ΔE ≦ 2.0
Δ: 2.0 <ΔE ≦ 5.0
×; 5.0 <ΔE

  As apparent from Table 1, according to the present invention, it is possible to provide a silver-plated coated body having sufficient water resistance while preventing heat discoloration and corrosion by salt.

Claims (1)

The topcoat layer is represented by the following general formula (1) in a silver-plated coated body having on the substrate at least a silver plating layer and a topcoat layer adjacent thereto containing a thermosetting resin or an ultraviolet curing resin. The thiourea derivative to be added is added in an amount of 0.1 to 1% by mass based on the solid content of the top coat, and the triazine derivative represented by the following general formula (2) is based on the solid content of the top coat The top coat layer has a thickness of 10 μm or more when it contains a thermosetting resin, and the thickness of the top coat layer when it contains a UV-curable resin. Silver-plated coated body characterized by having a diameter of 3 μm or more .
(In the general formula (1), R ₁ and R _{2 each} represent a hydrogen atom or a hydrocarbon group having a carbon number of 10 or less. However, R ₁ and R ₂ are not simultaneously hydrogen atoms, and may be the same or different R ₁ and R ₂ may combine to form a ring.)
(In the general formula (2), R ₃ and R ₄ represent an aryl group, and R ₅ represents an alkyl group having 4 or more carbon atoms or a substituent having 4 or more carbon atoms represented by the following general formula (3).)
(In general formula (3), R ₆ represents an alkylene group having 2 or 3 carbon atoms, a linking group L represents -O-, -COO- or -OCO-, and R ₇ represents an alkyl group.)