JP6945464B2 - Manufacturing method of silver-plated painted body - Google Patents

Description

The present invention relates to a method for producing a silver-plated coated body having at least an undercoat layer, a silver-plated layer, and a topcoat layer on a base material. More specifically, the present invention relates to a method for producing a silver-plated coated body having excellent durability by improving the adhesiveness between the undercoat layer and the silver-plated layer.

A silver-plated coated body having a silver-plated layer on a base material is processed into a metal or plastic surface because silver has the highest reflective luster among metals, and is used as a design material, a reflective material, or the like. .. Further, 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-plated layer is a useful material that exhibits high reflective luster 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 make up for such a defect, it is known that a top coat layer is provided on the surface by using various hard coat materials. For example, Japanese Patent Application Laid-Open No. 2000-129448 (Patent Document 1) describes that various resins such as liquid epoxy resin and unsaturated polyester resin can be used for the top coat layer, and Japanese Patent Application Laid-Open No. 2003-155580 (Patent Document 2). ), Japanese Patent Application Laid-Open No. 2004-203014 and the like describe that a silicon acrylic paint is used, and Japanese Patent Application Laid-Open No. 2006-111857 and the like disclose a top coat layer using a urethane resin. Further, Japanese Patent Application Laid-Open No. 2008-110101 and the like describe that an ultraviolet curable resin may be used.

However, even if these top coat layers are provided, the adhesive strength between the base material or the undercoat layer and the silver plating layer is weakened by exposing the silver-plated body to a high-temperature and high-humidity environment or an atmosphere containing salt water. There was a problem.

On the other hand, in producing a silver-plated coated body, in order to effectively utilize the good reflectance of the silver thin film layer, an undercoat layer is provided under the silver thin film layer to improve the roughness of the substrate surface. Is being done. The undercoat layer of such a silver-plated coated body is required to have excellent adhesion to the base material and further to be excellent in adhesion to the silver-plated layer provided on the undercoat layer.

As such an undercoat layer, for example, Japanese Patent Application Laid-Open No. 2001-164380 describes an undercoat layer coated with a mixed coating material containing an alkyd resin and an unsaturated polyester resin as main components and dried. Japanese Patent Application Laid-Open No. 04486 describes an undercoat agent containing an acrylic resin, an amino resin, an epoxy resin, and an alkoxytitanium ester in specific ratios. Patent Document 1 describes an undercoat layer containing a urethane resin having a phthalate ester, and Japanese Patent Application Laid-Open No. 2012-206326 (Patent Document 3) may use a urethane resin or an epoxy resin for the undercoat layer. There is a statement that it can be done.

Further, for the purpose of improving the adhesion between the undercoat layer and the silver plating layer, a method of forming the undercoat layer with a paint containing a silane coupling agent is known. As a paint for forming an undercoat layer, JP-A-2000-129448, JP-A-2007-23087 and the like disclose a paint containing a silane coupling agent having an epoxy group or an amino group. Kai 2005-213345 (Patent Document 4) discloses a coating material containing a silane coupling agent having a mercapto group. Further, Patent Document 3 describes that various silane coupling agents can be contained in the undercoat layer.

However, the above-mentioned conventional technique cannot solve the problem that the adhesiveness between the undercoat layer and the silver plating layer is lowered due to the influence of a long-term high temperature and high humidity environment, salt water, etc., and further improvement is required. rice field.

Japanese Unexamined Patent Publication No. 2000-129448 Japanese Unexamined Patent Publication No. 2003-155580 Japanese Unexamined Patent Publication No. 2012-206326 Japanese Unexamined Patent Publication No. 2005-213345

An object of the present invention is to provide a method for producing a silver-plated coated body having excellent durability by improving the adhesiveness between the undercoat layer and the silver-plated layer.

The above object of the present invention is achieved by the invention described below.
In a method for producing a silver-plated coating body having at least an undercoat layer, a silver plating layer and a topcoat layer on a substrate in this order, a polyol resin, a polyisocyanate compound, a silane coupling agent having a mercapto group, and an isocyanate group or It contains at least a silane coupling agent having an amino group , and the content of the silane coupling agent having a mercapto group is 10 to 50% by mass based on the total solid content of the coating material for the undercoat layer, and the isocyanate. The undercoat layer is formed by applying an undercoat layer coating having a content of a silane coupling agent having a group or an amino group of 5 to 30% by mass based on the total solid content of the undercoat layer coating. A method for manufacturing a silver-plated coating body, which is characterized by this.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a method for producing a silver-plated coated body having excellent durability by improving the adhesiveness between the undercoat layer and the silver-plated layer.

Hereinafter, the present invention will be described in detail.

The silver-plated coating body obtained by the present invention is a silver-plated coating body having at least an undercoat layer, a silver plating layer and a topcoat layer on the substrate in this order, and the undercoat layer is a polyol resin and a polyisocyanate compound. , A silane coupling agent having a mercapto group, and a coating material containing at least a silane coupling agent having an isocyanate group or an amino group.

The polyol resin contained in the paint used for forming the undercoat layer of the present invention (hereinafter referred to as the paint for the undercoat layer) is an oligomer or polymer having two or more hydroxyl groups, and is an alkyd polyol, polyester polyol, or acrylic. Examples thereof include polyols, polyether polyols, polycarbonate polyols, polycaprolactone polyols, etc. Among them, acrylic polyol resins are preferable.

The polyisocyanate compound contained in the coating material for the undercoat layer of the present invention is a compound having two or more isocyanate groups, and exemplifies a polyisocyanate compound composed of either an aromatic diisocyanate or an aliphatic or aliphatic diisocyanate. be able to. These may be any of a biuret type, an isocyanate type, an adduct type, and a bifunctional type. These polyisocyanate compounds are, for example, the Duranate (registered trademark) series marketed by Asahi Kasei Corporation, the Barnock (registered trademark) series marketed by DIC Corporation, and the Coronate (registered trademark) marketed by Tosoh Corporation. The (trademark) series or the Mytec (registered trademark) series commercially available from Mitsubishi Chemical Corporation can be obtained and used. These polyisocyanate compounds may be used alone or in combination of a plurality of compounds.

The suitable content of the polyisocyanate compound contained in the coating material for the undercoat layer of the present invention depends on the amount of hydroxyl groups of the polyol resin contained in the coating material for the undercoat layer, but depends on the total solid content of the coating material for the undercoat layer. On the other hand, it is preferably about 1 to 50% by mass, more preferably 5 to 30% by mass. If the amount of the isocyanate compound is too large, defects may occur in the undercoat layer due to unnecessary chemical reactions such as unreacted isocyanate groups reacting with water to generate carbon dioxide gas. On the other hand, if the amount is too small, the strength of the undercoat layer cannot be sufficiently maintained. The total solid content of the coating material referred to here represents the total amount of the total coating composition excluding the solvent component that evaporates to form a layer after coating.

The combination of the polyol resin and the polyisocyanate compound as described above can be easily obtained as a main agent and a curing agent for a commercially available two-component curable urethane-based paint. For example, Mirror Shine commercially available from Ohashi Chemical Industries, Ltd. Undercoat Clear D-1 and Underblack No. 128 can be mentioned.

The undercoat layer coating material of the present invention contains a silane coupling agent having a mercapto group. Examples of the silane coupling agent having a mercapto group include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane and the like. can.

If the amount of these silane coupling agents added is too small, the effect of improving the adhesion cannot be obtained, and if it is too large, the effect of improving the adhesion is rather lowered. The preferable addition amount is 10 to 50% by mass with respect to the total solid content of the undercoat layer coating material.

The coating material for an undercoat layer of the present invention further contains a silane coupling agent having an isocyanate group or an amino group. Examples of the silane coupling agent having an isocyanate group include 3-isocyanatepropyltriethoxysilane and 3-isocyanatepropyltrimethoxysilane. Examples of silane coupling agents having an amino group include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, and N- (2). −Aminoethyl) -3-aminopropyltriethoxysilane and the like can be mentioned.

If the amount of these silane coupling agents added is too small, the effect of improving the adhesion cannot be obtained, and if it is too large, the effect of improving the adhesion is rather lowered. The preferable addition amount is 5 to 30% by mass with respect to the total solid content of the undercoat layer coating material.

In addition to the above-mentioned polyol resin, the coating material for the undercoat layer of the present invention includes, for example, epoxy resin, polyvinyl chloride, hydrocarbon resin, ketone resin, phenoxy resin, polyamide, ethyl cellulose, nitrocellulose, vinyl acetate, ABS resin, and melamine. Other resins such as resins, urea resins, benzoguanamine resins, unsaturated polyester resins, alkyd resins and silicone resins can be included. In that case, the content of the resin other than the polyol resin is preferably 30% by mass or less of the content of the polyol resin, and further, a curing agent suitable for the above-mentioned various resins can be contained.

The coating material for the undercoat layer of the present invention may contain a curing accelerator. As the curing accelerator, it is cured by Nagashima Co., Ltd.'s urethane curing accelerator, Sansei Paint Industry Co., Ltd.'s drying accelerator A, Nitto Bussan Co., Ltd., Sun Appro Co., Ltd., Nippon Kagaku Sangyo Co., Ltd., Mitsubishi Chemical Co., Ltd., etc. Phenolic salts, oleates, and octylates of 1,8-diazabicyclo [5,4,0] undecene-7 and 1,5-diazabicyclo [4,3,0] nonen-5, which are commercially available as accelerators. Etc. can be used. The amount of the curing accelerator used is preferably 1% by mass or less with respect to the total solid content of the paint for the undercoat layer.

The undercoat layer coating material of the present invention may contain a leveling agent in order to improve the surface quality of the surface. As the leveling agent, a silicon-based leveling agent, a fluorine-based leveling agent, or the like can be obtained from Toshin Kagaku Co., Ltd., DIC Corporation, BYK Co., Ltd., etc. and used. The amount of the leveling agent used is preferably 0.1% by mass or less with respect to the total solid content of the paint for the undercoat layer.

The coating material for an undercoat layer of the present invention can be obtained by dissolving the above-mentioned resin composition or the like in an organic solvent. Examples of such organic solvents include hydrocarbons such as toluene, xylene, cyclohexane and Solbesso (registered trademark) 100 (trade name, manufactured by Exxon Chemical Co., Ltd.), alcohols such as methanol, ethanol, isopropyl alcohol and butyl alcohol, and butyl cellosolve. , Ethers such as tetrahydrofuran and methyl cellosolve acetate, esters such as ethyl acetate, -n-butyl acetate, isobutyl acetate and isobutyl isobutyrate, and ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, but are limited thereto. It's not something. These organic solvents are appropriately selected depending on the solubility of the resin composition or the like used for providing the undercoat layer and from the viewpoint of surface quality, and may be used alone or in combination of two or more.

The undercoat layer is formed by applying the above-mentioned paint for the undercoat layer on the base material. In the present invention, coating includes a step of coating, followed by drying and curing. The coating method may be a conventionally known coating method, 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, or an airless spray method. , Dip method and other coating methods can be mentioned. Of these, the air spray method, which can be applied to complicated surface shapes, is particularly preferable. The film thickness of the undercoat layer is preferably 5 to 30 μm, but is not particularly limited.

In order to dry and cure the undercoat layer paint after applying it to the base material, it can be naturally dried at room temperature, but it is preferable to heat it to accelerate the drying and curing. It is preferable that the heating temperature is high, but if the base material is plastic, it may be deformed if the temperature is too high, so it is necessary to heat within a temperature range in which the base material is not deformed. When the base material is plastic, heating is usually performed at 60 to 80 ° C. for about 20 to 120 minutes. When the base material is a metal that can withstand high temperatures, the drying and curing time can be shortened by heating at a higher temperature.

The silver-plated coated body obtained by the present invention has a silver-plated layer on an undercoat layer provided on the base material. A preferred method for forming a silver-plated layer is to treat the surface of the undercoat layer on which the silver-plated layer is formed with a silver mirror active treatment solution containing stannous chloride to support stannous ions on the surface of the undercoat layer. Then, a silver plating layer is formed on the activated undercoat layer by a silver mirror reaction.

As a treatment method for treating with an active treatment liquid for a silver mirror containing stannous chloride, a method of immersing the surface of the undercoat layer for forming a silver plating layer in the active treatment liquid for a silver mirror, and an undercoat for forming a silver plating layer. There is a method of applying an active treatment liquid for a silver mirror containing stannous chloride or the like on the surface of the coat layer. As a coating method, spray coating regardless of the shape of the base material is particularly preferable. Further, it is preferable to wash the activation treatment liquid excessively attached to the surface with deionized water or purified distilled water.

Examples of the activation treatment liquid for silver mirrors containing stannous chloride include the activation treatment liquids described in JP-A-2007-197743 and JP-A-2006-111912.

After the step of treating with the silver mirror activation treatment liquid, a step of performing the activation treatment with silver ions may be provided. The activation treatment with silver ions can be exemplified by treatment with a treatment liquid containing silver nitrate, for example. The concentration of the silver nitrate aqueous 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 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 treatments, spray coating in which a new liquid is always supplied is preferable.

The silver plating layer is formed by the silver mirror reaction by using two solutions, an ammoniacal silver nitrate solution containing silver nitrate and ammonia and a reducing agent solution containing a reducing agent and a strong alkaline component, on the surface of the undercoat layer subjected to the above activation treatment. Apply to mix. As a result, a redox reaction occurs to precipitate metallic silver, and a silver film is formed to form a silver-plated layer.

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

Some additives can also 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 thereof include amino alcohol compounds such as amines, triethanolamines and triisopropanolamines, amino acids such as glycine, alanine and sodium glycine 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 as to be mixed on the surface on which the silver plating layer is formed, the two aqueous solutions are mixed in advance and the mixed solution is sprayed with a spray gun or the like. A method of spraying on the surface of the undercoat layer using a concentric spray gun having a structure in which two types of aqueous solutions are mixed in the head of the spray gun and immediately discharged, and a method of spraying the two types of aqueous solutions with two spray nozzles. There is a method of ejecting and spraying each of them from a double-headed spray gun, and a method of simultaneously spraying two kinds of aqueous solutions using two separate spray guns. These can be arbitrarily selected according to the situation.

Subsequently, it is preferable to wash the surface of the silver-plated layer with deionized water or purified distilled water to remove the solution after the silver mirror reaction remaining on the surface. Further, before providing the above-mentioned top coat layer on the silver plating layer, for the purpose of stabilizing the precipitated metallic silver, the solution is immersed in a solution containing an organic compound having a reaction or affinity with silver, or the solution is applied. Surface treatment can be performed.

Examples of the organic compound include nitrogen-containing heterocyclic compounds having a thiol group or a thione group. As the heterocycle contained in the nitrogen-containing heterocyclic compound, an imidazole ring, a triazole ring, and a tetrazole ring are preferable. Specific examples include 2-mercapto-4-phenylimidazole, 2-mercapto-benzimidazole, 1-ethyl-2-mercapto-benzimidazole, 1,3-diethyl-benzimidazolin-2-thione, 2,2'-dimercapto. -1,1'-decamethylene-diamidazoline, 2-mercapto-4-phenylthiazole, 2-mercapto-benzothiazole, 3-ethyl-benzothiazolin-2-thione, 3-dodecyl-benzthiazolin-2-thione, 2 -Mercaptobenzoxazole, 1-phenyl-3-methylpyrazoline-5-thion, 3-mercapto-5-nonyl-1,2,4-triazole, 2-mercapto-5-phenyl-1,3,4-thiazole, 2 -Mercapto-5-n-heptyl-oxathiazole, 2-mercapto-5-n-heptyl-oxadiazole, 2-mercapto-5-phenyl-1,3,4-oxadiazole, 5-mercapto-1- Examples thereof include phenyl-tetrazole and 2-mercapto-4,6-diphenyl-1,3,5-triazine.

Since the metallic silver formed as described above is easily damaged, in the present invention, a top coat layer is further provided on the surface of the silver plating layer. The top coat layer is preferably formed by applying a paint made of a heat or photocurable resin.

As the paint used for forming the top coat layer used in the present invention (hereinafter referred to as the paint for the top coat layer), a paint containing a thermosetting resin is generally used. Examples of the thermosetting resin include epoxy resins, unsaturated polyester resins, melamine resins, silicon resins, and acrylics described in JP-A-2000-129448, JP-A-2003-155580, and JP-A-2006-111857. Examples thereof include silicon resin and urethane resin. Among these, a paint containing a melamine resin, a urethane resin, and an acrylic silicon resin is preferably used because of its high transparency and easy application.

As the coating material containing a urethane resin, a two-component curable urethane-based coating material in which a polyol resin such as an alkyd polyol, a polyester polyol, or an acrylic polyol and a polyisocyanate compound as a curing agent is mixed is preferable. As the paint containing the acrylic silicone resin, an acrylic silicone-based paint in which an acrylic resin and an alkoxysilane compound (silicon-based curing agent) are mixed as a curing agent is preferable.

Examples of commercially available thermosetting paints include Origin Tuk (registered trademark) # 100 (acrylic silicon-based paint) manufactured by Origin Electric Co., Ltd. and Hypolynal (registered trademark) No. 1 manufactured by Ohashi Chemical Industries, Ltd. 800S (acrylic silicone paint), Omac (registered trademark) No. 100 (E) Clear FV (Acrylic Silicone Paint), Polynal (Registered Trademark) 800 (Acrylic Urethane Paint), Neohard (Registered Trademark) Clear H (Melamine Paint) and the like are preferably used.

The coating material for the top coat layer used in the present invention can be obtained by dissolving or diluting the above-mentioned coating composition in an organic solvent. As the organic solvent, the same type of organic solvent as that used in the paint for the undercoat layer can be used. These organic solvents are appropriately selected from the viewpoint of the solubility of the coating composition and the improvement of the surface quality of the coated surface, and are used alone, but are often used as a mixture of two or more.

The coating method for the top coat layer may be a conventionally known coating method, for example, a gravure roll method, a reverse roll method, a dip roll method, a bar coater method, a knife coater method, an air spray method, an airless spray method, or a dip. The method and the like can be mentioned. Of these, the air spray method, which can be applied to complicated surface shapes, is particularly preferable.

As the paint for the top coat layer, a UV curable paint containing a UV curable resin can also be used. The ultraviolet curable resin preferably used is a monomer and an oligomer compound having an ethylenically unsaturated group. Specific examples thereof include amide-based monomers, (meth) acrylate monomers, urethane acrylates, polyester (meth) acrylates and epoxy (meth) acrylates. Examples of the amide-based monomer include amide compounds such as N-vinylpyrrolidone, N-vinylcaprolactam, and acryloylmorpholine. Examples of the (meth) acrylate monomer include hydroxyalkyl (meth) acrylates, acrylates with an alkylene oxide adduct of phenol, (meth) acrylates of glycol, (meth) acrylic acid esterified product of polyol and its alkylene oxide, and isocyanur. Acid EO modified di or tri (meth) acrylate and the like can be mentioned.

Examples of the urethane (meth) acrylate oligomer include a reaction product obtained by further reacting a polyol and an organic polyisocyanate reaction product with a hydroxyl group-containing (meth) acrylate. Examples of the polyester (meth) acrylate oligomer include a dehydration condensate of a polyester polyol and (meth) acrylic acid. Epoxy acrylate is obtained by adding an unsaturated carboxylic acid such as (meth) acrylic acid to an epoxy resin, and is an epoxy (meth) acrylate of a bisphenol A type epoxy resin, or an epoxy (meth) of a phenol or cresol novolac type epoxy resin. Examples thereof include (meth) acrylic acid addition reactants of acrylate and diglycidyl ether of polyether.

Examples of the photopolymerization initiator include benzoins, acetophenones, anthraquinones, thioxanthones, ketals, benzophenones, xanthones and the like. These photopolymerization initiators can be used alone or in combination with benzoic acid-based or amine-based photopolymerization initiators.

The content of the photopolymerization initiator is preferably 0.01 to 20% by mass, particularly preferably 0.5 to 7% by mass, based on the ultraviolet curable resin.

In order to dry or cure the paint for the top coat layer, heating may be applied in the case of a thermosetting paint, and ultraviolet rays may be applied in the case of an ultraviolet curable paint. Examples of the means for irradiating ultraviolet rays include lamp light sources such as xenon lamps, halogen lamps, tungsten lamps, high-pressure mercury lamps, ultra-high pressure mercury lamps, metal halide lamps, medium-pressure mercury lamps, and low-pressure mercury lamps.

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

Coloring materials such as pigments and dyes may be added to the paint for the top coat layer in order to improve the design. Pigments include organic pigments such as carbon black, quinacridone, naphthol red, cyanine blue, cyanine green, and Hansa yellow, and inorganic pigments such as titanium oxide, aluminum oxide, calcium carbonate, barium sulfate, mica, petals, and composite metal oxides. Pigments can be mentioned, and one kind or a combination of two or more kinds 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, a dyno meal, a paint shaker, a sand mill, a ball mill, a kneader, a roll, a dissolver, a homogenizer, ultrasonic vibration, a stirrer, etc. Is used. At that time, a dispersant, a dispersion aid, a thickener, a coupling agent and the like can be used. The amount of the pigment added is not particularly limited because the hiding power differs depending on the type of pigment, but is usually 0.1 to 5% by mass with respect to the total solid content of the coating material.

Examples of dyes include azo-based, anthraquinone-based, indicoid-based, sulfide-based, triphenylmethane-based, xanthene-based, alizarin-based, acridine-based, quinoneimine-based, thiazole-based, methine-based, nitro-based, and nitroso-based dyes. It can be mentioned, and one kind or a combination of two or more kinds selected from these dyes can be used. The amount of the dye added is not particularly limited because the hiding power differs depending on the type of dye, but is usually 0.1 to 5% by mass with respect to the total solid content of the paint for the top coat layer.

The top coat layer may further contain a leveling agent, a metal powder, a glass powder, an antibacterial agent, an antioxidant, an ultraviolet absorber, a light stabilizer and the like as additives. Further, in order to improve the adhesion between the top coat layer and the silver plating layer, thiols such as pentaerythritol tetrakisthiopropionate described in JP2012-206326A may be contained. The amount of these thiols used is preferably 1 to 30% by mass with respect to the total solid content of the paint for the top coat layer.

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

The silver-plated coated body obtained by the present invention has an undercoat layer on the base material, but the adhesion between the undercoat layer and the base material may not be sufficient depending on the type of the base material. In such a case, the base material may be pretreated for the purpose of improving the adhesion between the base material and the undercoat layer. Examples of the pretreatment method include wet methods such as detergent, solvent cleaning and ultrasonic cleaning, and dry treatments such as corona treatment, ultraviolet irradiation, and electron beam irradiation. Further, depending on the type of the base material, for example, a primer layer may be provided between the base material and the undercoat layer for improving adhesiveness for polypropylene and for rust prevention for iron and aluminum.

Hereinafter, the present invention will be described with reference to examples, but of course, this description does not limit the present invention.

(Comparative Example 1)
Acrylic polyol resin (Mirror Shine Undercoat Clear D-1 manufactured by Ohashi Chemical Industries, Ltd.), polyisocyanate compound (hardener N for mirror shine undercoat manufactured by Ohashi Chemical Industries, Ltd.) and thinner (methyl ethyl ketone and butyl cell solve) in mass ratio (Mixed at a ratio of 1: 1) was mixed at a mass ratio of 10: 2:10. Further, a leveling agent (BYK-323 manufactured by BYK Co., Ltd.) was added to this mixed solution so as to be 0.02% by mass with respect to the total solid content of the coating material to obtain a coating material for an undercoat layer. The surface was washed with isopropyl alcohol and dried, and the above paint was applied to an ABS resin plate with 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.

A silver mirror activation treatment solution containing 0.1 mol of hydrochloric acid and 0.1 mol of stannous chloride was added to 1000 g of water and sprayed onto the undercoat layer with a spray gun for activation treatment, followed by deionization. Washed with water. Subsequently, 0.05 mol of silver nitrate was dissolved in water to make 1000 g, and this liquid 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. A silver nitrate solution prepared by dissolving 20 g of silver nitrate in deionized water to make 1000 g and an ammonia solution prepared by dissolving 100 g of a 28% aqueous ammonia solution and 5 g of monoethanolamine in deionized water to make 1000 g were separately prepared. Prior to use, these silver nitrate solutions and ammonia solutions were mixed 1: 1 to obtain an ammoniacal silver nitrate solution. Next, a reducing agent solution 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 was prepared.

The ammoniacal silver nitrate solution and the reducing agent solution thus obtained are simultaneously sprayed using a double-headed spray gun to form a silver-plated layer, washed with deionized water, and after the surface water is sufficiently removed. , 45 ° C. for 30 minutes.

A top coat layer was provided on the silver plating layer. Main resin of acrylic silicon paint (Ohashi Chemical Industries, Ltd. Omac (registered trademark) No. 100 (E) clear FV) and silicon curing agent (Ohashi Chemical Industries, Ltd. Omac No. 100 curing agent W) , Thinner (methyl ethyl ketone and butyl cellosolve mixed at a mass ratio of 1: 1) was mixed at a mass ratio of 6: 1: 6. Further, pentaerythritol tetrakisthiopropionate was added to this mixed solution so as to be 5% by mass based on the total solid content of the paint to obtain an acrylic silicon-based paint for the top coat layer, which was sprayed on the silver plating layer. It was applied with a gun and dried by heating at 80 ° C. for 30 minutes to form a top coat layer of 15 μm. In this way, a silver-plated coated body obtained by subjecting ABS resin to silver mirror plating was obtained.

(Comparative Examples 2 to 13 and Examples 1 to 10)
The same as in Comparative Example 1 except that the paint for the undercoat layer of Comparative Example 1 contained the addition amounts of the silane coupling agent 1 and the silane coupling agent 2 shown in Table 1 below, respectively. A silver-plated body was obtained. The addition amount shown in the table indicates the mass% of the silane coupling agent with respect to the total solid content of the paint for the undercoat layer.

<Evaluation method>
(Salt water resistance test)
The silver-plated coated bodies obtained in Examples and Comparative Examples were cross-scratched with a cutter so as to reach the ABS base material from the top coat layer surface. These samples were sprayed with 5% by mass saline solution in a salt spray tester (model STP-90) manufactured by Suga Test Instruments Co., Ltd. in an environment of 35 ° C. for 30 days. The salt-sprayed sample was washed with water, dried, and a cellophane tape was strongly attached on the cross-scratched portion, and then the tape was peeled off. The judgment was made based on the following criteria based on the peeling condition of the coating.
○; The width of the widest part of the paint peeling is less than 2 mm from the center of the cut line Δ; 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 widest part of the paint peeling The width of the part is 4 mm or more from the center of the cut line

(Moisture resistance test)
Similar to the salt spray test, the sample in which the cross was scratched with a cutter was stored for 30 days in an environment of a temperature of 65 ° C. and a humidity of 95% RH. Then, the sample was washed with water and dried, and after the cellophane tape was strongly attached on the portion where the cross was scratched, the tape was peeled off, and the judgment was made based on the following criteria based on the peeling condition of the coating.
◯; The width of the widest part of the paint peeling is less than 1 mm from the center of the cut line Δ; The width of the widest part of the paint peeling is 1 mm or more and less than 2 mm from the center of the cut line ×; The widest part of the paint peeling The width of the part is 2 mm or more from the center of the cut line

As is clear from Table 2, the production method of the present invention improves the adhesiveness between the undercoat layer and the silver-plated layer, and the silver-plated coated body has excellent durability against high-temperature and high-humidity environments and salt water. A manufacturing method can be provided.

Claims (1)

In a method for producing a silver-plated coating body having at least an undercoat layer, a silver plating layer and a topcoat layer on a substrate in this order, a polyol resin, a polyisocyanate compound, a silane coupling agent having a mercapto group, and an isocyanate group or It contains at least a silane coupling agent having an amino group , and the content of the silane coupling agent having a mercapto group is 10 to 50% by mass based on the total solid content of the coating material for the undercoat layer, and the isocyanate. The undercoat layer is formed by applying an undercoat layer coating having a content of a silane coupling agent having a group or an amino group of 5 to 30% by mass based on the total solid content of the undercoat layer coating. A method for manufacturing a silver-plated coating body, which is characterized by this.