JP3262748B2 - Laminated product having silver plating layer and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminate having a silver plating layer and a method for producing the same. In the production method of the present invention, an undercoat layer having a specific composition is formed on the surface of an insulating base material such as plastics or a conductive base material such as metal, and then a silver solution is formed from an aqueous solution containing silver on the surface. Is chemically precipitated. As a result, it is possible to easily obtain a laminate having excellent adhesion, durability and the like and having a silver plating layer having a desired luster. In addition, by providing the top coat layer, a laminate having more excellent durability and the like and a beautiful appearance can be obtained. The laminate provided with the silver plating layer of the present invention is a plate-shaped body such as a film or a sheet, or a molded article having a specific shape such as a container for cosmetics.
Furthermore, since the silver plating layer is composed of a film made of pure silver, it has a very high conductivity and can be used as a conductive material and a material for electromagnetic wave shielding.

[0002]

2. Description of the Related Art A chemical plating method utilizing a silver mirror reaction is a well-known method such as the manufacture of a mirror which is a product having a plating layer formed on a glass surface. Various improvements have been made, such as the medicine to be used, the operation procedure, and the method. However, except for mirrors, no method has been developed that satisfies all requirements such as adhesion to the substrate, gloss and durability of the plating layer, and productivity, and especially to adhesion to the substrate. There is a problem that it is inferior. For this reason, at present, methods such as an electroplating method, a vacuum evaporation method, and a hot stamping method have not been established to the extent specified in JIS standards.

[0003] Conventionally, silver chemical plating methods include, for example, when the substrate is plastics, degreasing the surface of the substrate, immersing the substrate in a chromic acid aqueous solution, washing with water, and applying a solution to a stannous chloride solution. There are known methods which require immersion, rinsing, plating, rinsing of a material and application of a top coat agent, and numerous steps. There is also a method of dipping in an organic solvent solution containing organic titanate, but the base material used is only paper, and the solution is extremely dilute,
It is inferior in workability as described below.

Depending on the type of organic titanate, for example, when a solution having a concentration of about 2% by weight or more is used, countless cracks are generated in the silver plating layer in a drying step or the like. Or it becomes powder on the surface of the substrate,
The intended purpose cannot be achieved. Therefore, if the solution is diluted and the catalyst layer made of organic titanate is made extremely thin, such cracking, powdering, and the like can be prevented to some extent. However, as a result, slight contamination present on the surface of the base material, stains, stains, and foreign substances such as dust may cause uneven deposition of silver, discoloration, pinholes, peeling from the undercoat layer, and the like, The process needs to be highly controlled. Further, even if advanced management is performed, the adhesion cannot be sufficiently improved.

In any case, conventionally, in order to obtain a beautiful silver plating layer by a chemical plating method, it has been essential to keep the surface of the undercoat layer highly clean. Therefore, many processing steps were required, and those steps had to be highly controlled. Further, in the conventional technique, the adhesion between the undercoat layer and the silver plating layer is not sufficient, and the required performance cannot be obtained in a grid test which is a general evaluation method. In order to make it a general-purpose technology, it must be a method that can obtain a silver-plated product with excellent durability etc. and a beautiful appearance with simple operations and processes. Not at all.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a laminate having a silver-plated layer which is excellent in adhesion and durability and has a beautiful appearance. Aim. Another object of the present invention is to provide a method in which the steps can be significantly shortened, and a laminated product having the silver plating layer can be easily manufactured by a simple operation and method such as a spray method. . Furthermore,
In the present invention, excellent workability and simplicity can be achieved by using a specific undercoat layer that can cope with various base materials such as insulation and conductivity, and has excellent adhesion to a silver plating layer. According to the method, a laminate having a silver plating layer having excellent performance can be obtained.

[0007]

According to a first aspect of the present invention, there is provided a laminate having a silver plating layer, comprising a base material layer, an undercoat layer, a silver plating layer and a top coat layer, wherein the undercoat layer is formed of an alkoxy layer. An undercoating agent comprising a paint containing at least one of a titanium ester, a silane coupling agent having an epoxy group, and an epoxy resin is formed by drying.

A fifth aspect of the present invention provides a method for producing a laminate having a silver plating layer, wherein the coating material contains at least one of an alkoxy titanium ester, a silane coupling having an epoxy group, and an epoxy resin on the surface of the substrate. An undercoat agent consisting of is applied and dried to form an undercoat layer. Thereafter, an aqueous solution containing silver is applied to the surface of the undercoat layer and dried to form a silver plating layer, and then A top coat layer is formed on the surface of the silver plating layer.

The above “substrate” may be insulative or conductive. Examples of the insulating substrate include molded articles of various shapes made of various ceramics including plastics, rubber, glass, ceramics, and the like, wood, paper, and the like. As plastics, polyester,
Thermoplastic resins such as acrylonitrile-butadiene-styrene copolymer resin (ABS resin), polyolefin, polyvinyl chloride, acrylic resin, and polyamide; and thermosetting resins such as phenolic resin, unsaturated polyester resin, epoxy resin, and urethane resin Can be used similarly. Examples of the conductive substrate include molded products made of various metals such as stainless steel and aluminum. The molded article may be a plate-shaped body such as a film or a sheet, or may be a molded article having a specific shape such as a cosmetic container made of plastics, glass, or the like.

The above-mentioned "undercoat layer" can be formed by applying the above-mentioned "undercoat agent" to a substrate and drying it. This undercoat agent contains the above “paint” as a main component. As the paint, various kinds of synthetic resin paints and cellulose paints can be used. As the synthetic resin paint, paints containing various synthetic resins as main components can be used. Examples of such a paint include an alkyd resin paint, a phenol resin paint, an amino alkyd resin paint, an epoxy resin paint, an acrylic resin paint, a polyurethane resin paint, and a silicone resin paint.

As the paint, alkyd resin paint,
Paints that can be dried at room temperature, such as epoxy alkyd resin paints, epoxy ester resin paints, epoxy isocyanate resin paints, silicone resin paints, and acrylic resin paints are preferred. These paints have a tough film after drying, have excellent adhesion to the silver plating layer, and can form a silver plating layer having an excellent appearance. In particular, the alkyd resin paint is excellent in adhesiveness and is more preferable, regardless of whether it is an insulating or conductive substrate or an organic or inorganic substrate. Cellulose-based paints are also preferred because they have excellent performance, but interference fringes may occur in the resulting silver plating layer. Therefore, it is preferable to use the interference fringes after confirming that the interference fringes do not cause a problem in practical use.

Further, when the base material is plastics, an alkyd resin paint is particularly preferred. When the base material is a metal, a resin coating containing 70 to 90% by weight of an alkyd resin and 30 to 10% by weight of a silicone resin is particularly preferable. As the paint, a mixture of an alkyd resin paint and a silicone resin paint at a predetermined ratio can be used. In addition, even when using these excellent performance paints, when using a substrate made of a resin having poor adhesiveness such as polyethylene, polypropylene, polyethylene terephthalate and fluororesin, the surface thereof is corona discharge, plasma discharge, flame irradiation. It is preferable to improve the wettability by preliminarily treating with such a method.

The above-mentioned "alkoxy titanium ester" is added to the paint. As the alkoxy titanium ester, butyl titanate dimer (DB
T), tetra-n-butoxytitanium (TBT) and its polymer, tetraisopropoxytitanium (TPT), tetrakis (2-ethylhexyloxy) titanium, tetrastearyloxytitanium and the like can be used. As the alkoxy titanium ester, the second
As in the present invention, polymers of DBT and TBT are preferable, and in addition to these, TPT and the like are also suitable. DBT and TBT
The polymer having a low hydrolysis rate is stable and is particularly preferable. Furthermore, DBT does not lose its catalytic function even after 24 hours from the drying of the coating film, which is very convenient in operation. This DBT is also excellent in the function of improving the adhesion between the undercoat layer and the silver plating layer.

[0014] The compounding amount of the alkoxy titanium ester is, as in the third invention, the amount of the resin 100 contained in the paint.
"10 to 25 parts by weight" with respect to parts by weight, especially 15 to 20 parts by weight
It is preferable to use parts by weight. If the amount is less than 10 parts by weight, silver precipitation will be insufficient. In addition, when the added amount is increased, silver is easily precipitated due to its catalytic activity.
However, if the amount is excessive, undecomposed esters increase, and the alkoxy titanium ester is hydrolyzed by moisture penetrating through the silver plating layer to generate alcohol. The alcohol may swell the undercoat layer, thereby hindering the adhesion between the undercoat layer and the silver plating layer.

The alkoxynitinium ester may act as a curing agent depending on the type of resin constituting the undercoat layer. In particular, alkyd resins, silicone resins, and acrylic resins have such a large effect. Also, the silane coupling agent or epoxy resin having an epoxy group functions as a curing catalyst for opening the epoxy ring and accelerating the reaction. Therefore, the alkoxy titanium ester promotes the drying of the undercoat agent and improves the adhesion of the silver plating layer.

In addition to the alkoxy titanium ester, at least one of the above-mentioned "silane coupling agent having an epoxy group" (hereinafter referred to as "epoxy silane") and the above-mentioned "epoxy resin" is added to the paint. Examples of the epoxysilane include β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidyloxypropylmethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and γ-glycidoxypropyltrimethoxysilane. Can be used. Various epoxy resins such as bisphenol A type, phenol novolak type, cresol novolak type, brominated bisphenol A type, and finger ring type can be used. With these epoxy silanes and epoxy resins, the adhesion between the silver plating layer and the undercoat layer is greatly improved.

The amount of the epoxysilane to be added is preferably 0.5 to 5 parts by weight, particularly 2 to 4 parts by weight, based on 100 parts by weight of the resin contained in the paint, as in the fourth invention. preferable. If the amount is less than 0.5 parts by weight, the adhesion between the undercoat layer and the silver plating layer tends to decrease. On the other hand, an excessive amount of epoxy silane is not preferred because the hardness of the undercoat layer is reduced or wrinkles are generated.

The amount of the epoxy resin to be added may be "5 to 15 parts by weight", especially 7 to 12 parts by weight, based on 100 parts by weight of the resin contained in the paint, as in the fourth invention. preferable. If the amount is less than 5 parts by weight, the adhesion between the undercoat layer and the silver plating layer will be reduced. On the other hand, when the epoxy resin is excessive, the leveling property of the undercoat layer tends to decrease. Incidentally, these epoxy silanes and epoxy resins may be used in combination, but the synergistic effect of the combination is not so remarkable.

The substrate coated with the undercoat material is immersed in an aqueous solution containing an organic acid such as formic acid or acetic acid for a short time. Alternatively, the aqueous solution is sprayed on the surface of the applied undercoat agent. The epoxy group of the epoxy silane or epoxy resin is opened by the treatment with such an aqueous solution. The undercoat layer treated with the aqueous solution is dried to remove the solvent contained in the paint. The surface of the dried undercoat layer is alkalinized by the ring opening of the epoxy group by the treatment with the aqueous solution containing the organic acid. Therefore, it is preferable to form a silver plating layer after washing with pure water and neutralizing the surface. When a silver plating layer is formed on an alkaline surface, there is a high possibility that a reaction of ring opening of the epoxy group occurs in parallel with the silver mirror reaction, and the silver plating layer is liable to be clouded or cracked.

Before the undercoat layer is brought into contact with an aqueous solution containing silver, it is preferable to treat the surface of the undercoat layer by corona discharge, plasma discharge, flame irradiation, ultraviolet irradiation, or the like. By these treatments, the surface of the undercoat layer is roughened, the wettability is significantly improved, and the surface is activated. Therefore, a silver plating layer having a required thickness can be formed by an aqueous solution containing a small amount of silver. Further, a surfactant for making the surface easily wettable is not required, and a beautiful and clear silver plating layer is formed.
There are many advantages. Further, when the surface of the undercoat layer is decomposed by corona discharge or plasma discharge to generate gas, washing with pure water can form a higher quality silver plating layer.

When the molded article constituting the substrate is large,
Or, when there are many irregularities, it is difficult to perform efficient treatment by such corona discharge, plasma discharge and the like. In such a case, a surfactant is usually used to improve the wettability of the aqueous solution containing silver on the undercoat layer. The surfactant is generally used by adding it to an aqueous solution containing silver. Since this aqueous solution is an ionic solution, it is preferable to use a nonionic surfactant that does not cause a reaction. Particularly preferred surfactants are those having an ethylene oxide group and a hydroxyl group as hydrophilic groups. Further, those containing an alkali metal salt are not preferred because they may react with nitrate ions in an aqueous solution containing silver to produce a compound which may explode.

Further, when the formed silver plating layer contains a small amount of impurities, it may be slightly colored. Also,
The strength of the silver plating layer may not always be sufficient.
Therefore, the above “top coat layer” is provided on the surface of the silver plating layer. The top coat layer is usually formed by applying a coating and drying the coating, but a coating in which the coating film shrinks greatly upon drying is not preferable. When the shrinkage of the coating film is large, the undercoat layer and the silver plating layer, which are not necessarily firmly joined, may be separated from each other.

As the paint used for forming the top coat layer, a paint containing a silicone-modified resin is particularly preferable. Examples of the silicone-modified resin include an alkyd-modified silicone resin, an epoxy-modified silicone resin, an acryl-modified silicone resin and the like, and a flexible resin having a high modification rate and being particularly preferred. Note that soft materials having a high denaturation rate are easily damaged. For this reason, after providing the first layer made of this flexible resin, a second layer made of a relatively hard resin having a low modification rate can be formed on the surface thereof, and this can be used as a top coat layer. In this case, a coating containing a hard resin can be applied to the surface of the first layer after drying, and then dried. However, a coating containing a hard resin is applied before the coating containing a flexible resin dries. The paint can also be dried together. In addition, the silicone resin is easily dissolved in a general-purpose solvent such as xylene, and is advantageous in that a special solvent is not required.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a synthetic resin paint such as an alkyd resin paint is selected, and is prepared and stored in an appropriate composition in consideration of the effect on the appearance, such as the gloss and mat of the silver plating layer. On the other hand, an epoxy silane having a high affinity with the above-mentioned paint is added to an alkoxy titanium ester such as DBT so as to be 2 to 4 parts by weight based on 100 parts by weight of a synthetic resin such as an alkyd resin contained in the paint. . Similarly, an epoxy resin is added in an amount of 7 to 13 parts by weight based on 100 parts by weight of the synthetic resin.

After that, the stored coating material is added with an alkoxytitanium ester to which epoxy silane or epoxy resin is added so that the amount becomes 15 to 20 parts by weight with respect to 100 parts by weight of the synthetic resin contained in the coating material. Mix.
This is applied to a substrate as an undercoat agent. It should be noted that depending on the base material, the undercoat agent is hardly wet, and the base material and the undercoat layer may peel off. Therefore, it is necessary to consider a suitable combination in advance. The application of the undercoat agent to the substrate can be performed by an appropriate method such as brushing or spraying.

The alkoxy titanium ester is
It reacts with the hydroxyl group, carboxyl group, etc. of the resin contained in the paint and may gel or solidify. Therefore, it is necessary to confirm in advance that such a reaction does not occur. The viscosity of the undercoat agent is reduced by the addition of the epoxy silane, and the gelation is suppressed. In addition, a product obtained by adding an epoxy silane or an epoxy resin to an alkoxytitanium ester can be generally stored for about one month, and thus does not need to be mixed immediately before use. However, after mixing with the paint, the pot life is completely different depending on the type of the paint, so it is preferable to mix only the required amount. Further, the alkoxy titanium ester is sensitive to moisture, and is preferably used at a relative humidity of 65% or less. When the humidity is high, a required silver plating layer may not be formed due to fogging phenomenon, unevenness due to insufficient leveling, or the like.

The thickness of the coating film of the undercoat agent is 2 to 15
Microns, particularly about 3 to 8 microns, which is dried to form an undercoat layer. The undercoat layer has a clean surface, has high catalytic activity for depositing silver, and has excellent adhesion to the silver plating layer. Further, the gloss of the obtained silver plating layer can be easily changed as desired by the composition of the undercoat layer. Silver precipitated by the catalytic action of the alkoxy titanium ester is fixed to the surface of the undercoat layer by the ester residue and the epoxy silane or epoxy resin, and is not easily separated.

The coating film made of the undercoat agent formed on the surface of the substrate is dried at a temperature of 60 to 70 ° C. for 15 to 30 minutes by a hot air drying furnace or the like. Insufficient drying causes clouding, cracks, etc. of the silver plating layer due to the effect of the residual solvent. On the other hand, if the drying is excessive, hydrolysis of the alkoxy titanium ester proceeds too much, resulting in insufficient silver precipitation and poor adhesion to the undercoat layer.
The lower the temperature of this drying is, the better the operation is because the allowable range of the drying time is widened. Also,
Depending on the type of the coating, the coating may be dried at room temperature of about 20 to 35 ° C. for about 2 to 4 hours. Further, it is necessary to take care that dust and dirt in the air do not adhere in the drying step, but by washing the surface of the undercoat layer with pure water or other chemicals for 1 to 2 seconds immediately before the silver mirror reaction. I can deal with it.

Next, an aqueous solution containing silver is applied to the surface of the undercoat layer. The application of the aqueous solution is preferably performed by a spray method which is excellent in workability and the like. By using a commonly used apparatus such as a spray coater having a two-head gun, an aqueous ammoniacal silver nitrate solution and a reducing aqueous solution are simultaneously sprayed to form a silver plating layer having a good appearance and the like in a short time of several seconds. it can. The higher the concentration of the above two solutions, the more silver is precipitated, and the lower the concentration, the slower the silver. Therefore, it is necessary to appropriately adjust the concentration according to the size of the base material, the temperature of the working environment, and the like.

At a room temperature of about 20 to 35 ° C., the aqueous ammoniacal silver nitrate aqueous solution contains 0.3 to 3% by weight, preferably 0.1 to 3% by weight.
About 6 to 2% by weight of silver nitrate is contained. As the reducing aqueous solution, a reducing agent such as glyoxal is used in an amount of 2 to 10%.
An aqueous solution containing about 3 to 7% by weight is used. Then, a good silver plating layer can be formed by simultaneously spraying equal amounts of these aqueous solutions onto the surface of the undercoat layer.

The effect of the temperature of the working environment is very large.
At a low temperature of about 0 ° C., silver precipitation is not observed at all in an aqueous solution having the above-mentioned ordinary concentration, and an aqueous solution having a concentration of 5 to 6 times is required, which is uneconomical. In such a case, measures such as raising the temperature of the aqueous solution are required. On the other hand, if the temperature is higher than necessary and the rate of silver precipitation is too high,
The silver plating layer becomes cloudy. Therefore, if the silver plating layer formation speed, workability, cost, etc. are considered overall,
It is preferable to set the temperature of the working environment to about 20 to 35 ° C. When the aqueous solution containing silver is difficult to wet the undercoat layer, it is preferable to improve the wettability by treatment such as corona discharge or plasma discharge, or by using an appropriate amount of a surfactant.

Thereafter, a top coat layer is formed on the surface of the silver plating layer. As the top coat layer, a paint used on the surface of a plating layer formed by a normal electrolytic plating method can be used. However, since the adhesiveness is slightly inferior to the surface of a general aluminum film, it is preferable to use a paint having excellent adhesiveness such as a silicone-modified resin paint. The thickness of the top coat layer is not particularly limited, and may be appropriately determined in consideration of the purpose, application, hiding power, and the like of the top coat layer.

[0033]

【Example】

Example 1 Toluene was used as a solvent, and 30 g of an alkyd resin was dissolved in 34 ml of the solvent to prepare a coating material. On the other hand, D
5 g of BT (manufactured by Mitsubishi Gas Chemical Co., Ltd.) and epoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd., trade name "KP-39")
2 ") 1 g was added. Thereafter, the DBT to which the epoxy silane was added was blended into a paint, stirred and mixed to prepare an undercoat agent. Next, the undercoat agent was applied to the surface of a substrate made of an ABS resin sheet of 150 × 150 × 2 mm by a spray method to form a coating film having a thickness of 5 μm. Then, with a hot air drying oven,
After drying at a temperature of 65 ° C. for 20 minutes, an undercoat layer having a thickness of 5 μm was formed.

Next, an aqueous solution containing silver was sprayed onto the surface of the undercoat layer by a spray coater having a two-head gun and applied. Examples of the aqueous solution containing silver include:
An aqueous solution containing 5% by weight of silver nitrate was used. Also,
As the reducing aqueous solution, an aqueous solution containing 5% by weight of glyoxal was used. The temperature of the working environment including the temperature of these aqueous solutions was set to 25 ° C., and equal amounts of both aqueous solutions were sprayed. After a few seconds, a silver-plated layer having a clear, glossy and beautiful appearance was formed. When the adhesion (adhesion) of this silver plating layer was evaluated by the grid method of JIS K 5400, it was found that there was almost no peeling, and that the silver plating layer had extremely excellent adhesion.

Thereafter, a silicone-modified resin paint (trade name “KR-
5206 ”) was similarly applied by a spray method to form a coating having a thickness of 5 μm. Next, this was dried in a hot-air drying furnace at a temperature of 75 ° C. for 40 minutes to form a top coat layer, thereby obtaining a laminated product. In this laminate,
The excellent appearance of the silver plating layer was maintained as it was, and the silver plating layer was sufficiently protected, and was a high-quality laminate.

Example 2 An undercoat layer and a silver plating layer were formed in the same manner except that a phenol resin sheet was used in place of the ABS resin sheet, and a top coat layer was formed in the same manner. The obtained laminate was of high quality as in Example 1.

Example 3 An undercoat layer and a silver plating layer were formed in the same manner except that a stainless steel plate was used in place of the ABS resin sheet, and that 30 g of the alkyd resin was replaced with 25 g of the alkyd resin and 5 g of the silicone resin. To form a top coat layer. The obtained laminate was of high quality as in Example 1.

[0038]

According to the first invention, the gloss and the like of the silver plating layer can be appropriately adjusted by using the undercoat layer containing the organic titanate and the additive having an epoxy group. In addition, since an organic titanate and an additive having an epoxy group are used in combination, the adhesiveness between the undercoat layer and the silver plating layer is excellent, and in addition to containers for cosmetics, products of various shapes and uses having a silver plating layer. It can be. Further, since the plating layer is made of pure silver, it can be used as a current-carrying material, a material for shielding electromagnetic waves, and the like.

Further, according to the fifth invention, the steps can be greatly simplified as compared with the case of the electroless plating method, and the laminate having the silver plating layer having excellent performance of the first invention can be easily manufactured. And can be manufactured at low cost.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional view of a laminate having a silver plating layer.

[Explanation of symbols]

1; undercoat layer; 2; substrate layer; 3; silver plating layer;
4: Top coat layer.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-253372 (JP, A) JP-A-55-11803 (JP, A) JP-A-54-33575 (JP, A) JP-A 63-253 1534 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B32B 15/08

Claims (5)

(57) [Claims] 1. A laminate comprising a base material layer, an undercoat layer, a silver plating layer and a top coat layer, wherein the undercoat layer comprises an alkoxy titanium ester, a silane coupling agent having an epoxy group, and an epoxy resin. A laminate having a silver plating layer, wherein the laminate is formed by drying and forming an undercoat agent comprising a paint containing at least one of the paints. 2. The alkoxy titanium ester according to claim 1,
The laminate according to claim 1, which is a polymer of butyl titanate dimer or tetra-n-butyl titanate. 3. The alkoxy titanium ester is used in an amount of 10 to 2 parts by weight per 100 parts by weight of the resin contained in the paint.
A laminate comprising the silver plated layer according to claim 1 or 2 in an amount of 5 parts by weight. 4. The silane coupling agent having an epoxy group is 0.5 to 5 parts by weight and the epoxy resin is 5 to 1 part by weight based on 100 parts by weight of a resin contained in the coating material.
A laminate comprising the silver plating layer according to any one of claims 1 to 3 in an amount of 5 parts by weight. 5. An undercoating agent comprising a paint containing at least one of an alkoxy titanium ester, a silane coupling agent having an epoxy group, and an epoxy resin is applied to the surface of a substrate, and dried to form an undercoating agent. A silver-containing aqueous solution is applied to the surface of the undercoat layer and dried to form a silver plating layer, and then a top coat layer is formed on the surface of the silver plating layer. A method for producing a laminate comprising a silver plating layer.