JP2007197743A - Liquid activation agent for silver mirror - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid activation agent which is excellent in preservation stability, and capable of consistently obtaining hydrophilicity to a surface of a silver mirror film deposited thereon for a long period immediately after preparing the liquid activation agent. <P>SOLUTION: When forming a silver mirror film on a surface of a base material such as plastic, metal and glass, a liquid activation agent for the silver mirror containing a stannous compound to activate the surface of the base material for forming the silver mirror film thereon contains hydrogen peroxide. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for forming a silver mirror film on the surface of a substrate such as plastic, metal, glass, rubber, ceramics, wood, bamboo, leather, and polystyrene foam.

  For base materials used for automobile parts, interior decorations, fishing gear products, home appliances, communication equipment products, Buddhist accessories, building materials, plastics, metals, glass, rubber, ceramics, wood, bamboo, leather, foamed polystyrene, etc. A silver mirror film may be formed on the surface mainly for the purpose of decoration. Further, the silver mirror film is sometimes used in electromagnetic shielding products for the purpose of blocking electromagnetic waves.

  It is known that the following method is usually used to form a silver mirror film of a product comprising such a substrate. First, pretreatment is performed to make the surfaces of the products of the various substrates into a surface suitable for forming a silver mirror film (hereinafter referred to as “silver mirror film-formed surface”). In order to deposit silver by a silver mirror reaction, the activation treatment liquid containing stannous chloride or the like is brought into contact with the clean surface on which the silver mirror film is formed, thereby supporting stannous ions as a catalyst. Then, a silver mirror film is formed by performing silver mirror plating on the surface of the base material that has been activated. The silver mirror plating solution generally uses an electroless plating solution composed of a mixture of a silver solution containing silver nitrate and ammonia and a solution containing a reducing agent such as formalin, glucose, glyoxal, and hydrazine. And after repeating washing | cleaning, it dries and forms a protective layer on the surface of the said silver plating layer.

  The above method is a method capable of obtaining a product having a silver mirror film with excellent performance by a simple method having excellent adhesion and durability between the silver mirror film and the surface on which the silver mirror film is formed and having good workability. Are known.

The activation treatment solution used in the above method is an aqueous solution containing a stannous compound that acts as a catalyst for precipitating silver ions as metallic silver in the electroless plating solution. However, when, for example, stannous chloride is used as the stannous compound, stannous chloride reacts with a hydroxyl group (OH ⁻ ) in an aqueous solution by storing the activation treatment solution for several days, so that a basic salt (Sn ( A white precipitate of Cl) OH) is deposited. When the basic salt is precipitated, the amount of stannous ions in the activation treatment solution decreases and the hydrophilicity of the surface of the silver mirror coating is reduced. After that, when the silver mirror plating treatment is performed, the resulting silver mirror coating is stained and stained. Visible unevenness occurs.

  As means for improving the storage stability problem of the activation treatment liquid described above, for example, Japanese Patent Application Laid-Open No. 2003-13240 (Patent Document 1) discloses oxygen in a liquid containing a stannous compound and hydrogen chloride (hydrochloric acid). An activation treatment liquid in which a certain amount of a second tin compound is added to a liquid containing a stannous compound is disclosed in JP 2003-129249 A (Patent Document 2). Yes. However, the storage stability of the activation treatment solutions described in these publications is not fully satisfactory.

  The activation treatment solution is not immediately active immediately after the preparation of the solution, that is, in the so-called new solution state. Therefore, in order to obtain a satisfactory silver mirror coating, it is necessary to repeatedly perform the activation treatment on the surface on which the silver mirror coating is formed. It was. Alternatively, after preparing the activation treatment liquid, it was necessary to perform the activation treatment after waiting for the hydrophilicity to the surface on which the silver mirror film was formed to improve by storing for a certain period of time. However, if the storage period is too long, the hydrophilicity of the surface of the silver mirror coating will decrease with the formation of the basic salt of the stannous compound. It was necessary to repeatedly carry out the activation treatment until it was obtained, and finally, most of the stannous compound was precipitated, and the effect as an activation treatment solution was completely lost.

  In addition, although the inventions of Patent Documents 1 and 2 both require hydrochloric acid, the hydrochloric acid generally added to the activation treatment liquid causes corrosion called so-called “shike” such as discoloration and corrosion of the silver mirror film. In particular, in a product that requires a beautiful appearance, “shike” may cause a significant decrease in design and may impair the value of the product.

Hydrochloric acid used for the activation treatment liquid is used, for example, for the purpose of preventing the precipitation of a white precipitate of basic salt (Sn (Cl) OH) by reacting stannous chloride with a hydroxyl group (OH ⁻ ) in an aqueous solution. This is well known. This is also described, for example, in the Metal Surface Technology Handbook (edited by the Metal Surface Technology Association, published by Nikkan Kogyo Shimbun, 1977). Therefore, the absence of hydrochloric acid from the activation treatment solution for the purpose of preventing “shikake” is that, as described above, the precipitation of the white salt of the basic salt becomes significant in the conventional technology, and the activation treatment solution It was difficult to significantly reduce the storage stability. On the other hand, hydrochloric acid may corrode devices such as spray guns, and therefore it is desired that hydrochloric acid is not used as much as possible or used in a small amount.
JP 2003-013240 A JP 2003-129249 A

  The object of the present invention is that the activation stability of the surface of the substrate is good to form a silver mirror film, and the storage stability of the activation treatment liquid is good and stable for a long time immediately after the activation treatment liquid is produced. Then, it is providing the activation process liquid which can acquire the hydrophilicity with respect to the silver mirror film formation surface. Another object of the present invention is to provide an activation treatment liquid that has good storage stability without using hydrochloric acid, and that can stably obtain hydrophilicity for the surface of the silver mirror film formation immediately after production. It is to provide.

  The object of the present invention is to form a silver mirror film on the surface of the base material, in the activation treatment liquid containing a stannous compound for activating the silver mirror film-formed surface of the base material. This was achieved by an activation treatment solution for silver mirrors characterized by containing hydrogen.

  According to the present invention, the storage stability of the activation treatment liquid is good, and the hydrophilicity with respect to the surface on which the silver mirror film is to be formed can be obtained over a long period of time immediately after the activation treatment liquid is produced. In addition, according to the present invention, it is not necessary to use hydrochloric acid substantially, so that the storage stability is good without causing the problem of “shike”, and the silver mirror film-formed surface is stable over a long period of time immediately after production. Can be obtained.

  Hereinafter, the present invention will be described in detail. The activation treatment liquid of the present invention contains a stannous compound. The amount of stannous compound is about 0.005 to about 0.3 mole, preferably about 0.01 to about 0.25 mole per liter of water.

  As the stannous compound used in the present invention, stannous chloride, stannous oxide, stannous sulfate, and a mixture thereof can be used.

  The activation treatment liquid of the present invention contains hydrogen peroxide in addition to the stannous compound. The amount of hydrogen peroxide is about 0.005 to about 1.0 mole, preferably about 0.01 to about 0.50 mole per liter of water.

  Since the activation treatment liquid of the present invention uses hydrogen peroxide, the stannous compound can be easily dissolved without substantially using hydrochloric acid, and the production of a basic salt of the stannous compound can be achieved. However, if necessary, hydrochloric acid can be used. The amount of hydrochloric acid used can be in the range of about 0.001 mol to about 0.5 mol per liter of the activation treatment solution used. It should be noted that it is preferable not to contain hydrochloric acid substantially. However, it is preferable that the hydrochloric acid is not contained at all. It means that an amount of hydrochloric acid of 1 mol or less may be included.

  Furthermore, in the activation treatment liquid of the present invention, a stannic compound may be added in a range of about 5 to about 75 mol% with respect to the stannous compound, and as described in Patent Document 1 described above. Further, oxygen may be blown into a solution containing the stannous compound. As the stannic compound, stannic chloride, stannic oxide, and a mixture thereof can be used.

  The activation treatment liquid of the present invention can also be prepared as a so-called concentrated liquid having a tin compound corresponding to, for example, 2-fold dilution for the purpose of long-term storage.

  Next, a specific example of the silver mirror coating method using the activation treatment liquid of the present invention will be described.

  In the present invention, various materials such as metal, plastic resin such as ABS (acrylonitrile-butadiene-styrene) resin, rubber, wood, leather, glass plate, ceramics can be used as the base material on which the silver mirror film is formed.

  Prior to each processing step described below, it is preferable to clean the surface of these base materials as a pretreatment to form a silver mirror coating surface. That is, when the base material is plastic resin such as ABS (acrylonitrile-butadiene-styrene) resin, rubber, wood, leather, pretreatment that does not damage the surface oil, other dirt such as isopropyl alcohol, detergent, etc. Degrease using an agent and dry thoroughly. When the substrate is glass, it is degreased with ethyl alcohol. When the base material is ceramic, pretreatment similar to that of glass may be performed, but when porous, it is preferable to perform pretreatment similar to the above plastic. When the base material is a metal, the surface is often contaminated with oil, rust, etc., so it is preferable to perform pretreatment similar to plastics as necessary after sufficient degreasing and derusting. .

  Furthermore, it is preferable to provide an undercoat layer in advance on the surface of the substrate after cleaning. As the undercoat layer, for example, as described in JP-A-2002-256454 and JP-A-10-309774, an undercoat layer made of a polyester resin, an alkyd resin, an acrylic resin, a two-component curable polyurethane resin, or the like. Or an undercoat layer made of a coating material containing at least one of an alkoxytitanium ester, an epoxy group-containing silane coupling agent, and an epoxy resin. In this way, a clean silver mirror film-formed surface can be formed on each substrate surface.

  Subsequently, an activation process is performed on the clean silver mirror film-formed surface using the activation process liquid of the present invention. As a method of performing the treatment using the activation treatment liquid, a substrate on which a silver mirror film-formed surface is formed is immersed in the activation treatment liquid, or the activation treatment liquid of the present invention is applied to the silver mirror film-formed surface. Is carried out by spray coating. Spray coating is particularly preferred.

  Next, it is preferable to wash the activation treatment liquid that has excessively adhered to the substrate surface in the activation treatment step with the activation treatment liquid of the present invention with deionized water or purified distilled water. This cleaning liquid may contain a surfactant as described in, for example, JP-A-6-38860.

  After the washing, it is preferable to perform a treatment with a metal salt compound. A preferable metal salt compound is silver, and silver nitrate is particularly preferable.

  This treatment step is carried out by immersing the substrate in the aqueous solution of the metal salt compound or spray-coating the aqueous solution of the metal salt compound on the surface of the substrate. In particular, spray coating is preferred.

  Then, it progresses to the process of the silver mirror reaction process which uses the plating solution for silver mirrors. In this step, for example, by using the following silver mirror plating solution, it has a uniform gloss and, in particular, has a strong surface with respect to a silver mirror coating surface having an undercoat layer coated with lacquer or a two-component reactive paint. Can exhibit excellent adhesion.

  The plating solution for silver mirror is prepared as follows, for example. That is, first, 1 to 20 g, preferably 3 to 15 g of silver nitrate, 2 to 150 g of 28% aqueous ammonia solution, preferably 5 to 75 g, for example, monoethanolamine, with respect to 1 liter of water, suitably deionized water. , Tris (hydroxymethyl) aminomethane, 2-amino-2-hydroxymethyl-1,3-propanediol, 1-amino-2-propanol, 2-amino-1-propanol, diethanolamine, diisopropanolamine, triethanolamine Silver containing at least one compound selected from the group consisting of amino alcohol compounds such as triisopropanolamine, and amino acids such as glycine, alanine, sodium glycine or salts thereof, and preferably 0 to 10 g. A solution (A) is prepared.

  Separately, for 1 liter of deionized water, for example, 1 to 50 g, preferably 2 to 15 g of a hydrazine compound such as hydrazine sulfate or hydrazine hydrate, and 0 to 20 g of sodium hydroxide or potassium hydroxide, preferably 0 to A reducing solution (B) containing 10 g and 0 to 50 g, preferably 0 to 10 g, of at least one compound selected from the group consisting of the same amino alcohol compound and amino acid or salt thereof as the silver solution (A) is prepared. To do.

  Moreover, the compounding quantity of the at least 1 compound chosen from the group which consists of an amino alcohol compound and an amino acid, or its salt to a silver solution (A) and / or a reduction | restoration solution (B) is plating obtained by mixing these liquids In the solution, the total amount is preferably adjusted to 1 to 50 g, preferably 3 to 10 g per liter of the plating solution.

  The silver solution (A) and the reducing solution (B) obtained as described above are stored in separate pumping tanks, and both solutions are simultaneously sprayed onto the surface of the silver mirror film by a spray gun for each solution. Processing is performed to form a silver mirror film. After treatment, wash with deionized water or purified distilled water.

  The formed silver mirror film can be treated with the treatment described in JP-A No. 2004-169157, that is, with a solution containing an organic compound having a reaction or affinity with silver. This treatment is carried out by immersing the substrate in the organic compound solution or spray-coating the organic compound solution onto the substrate surface. After the treatment, it is washed with deionized water or purified distilled water.

  In the present invention, adhesion resistance, corrosion resistance, abrasion resistance, discoloration resistance and the like can be further improved by applying a known clear coating as a top coat layer on the silver mirror film.

  In the present invention, the undercoat layer and / or the topcoat layer may contain an organic compound that reacts or has affinity with silver as described in JP-A-2004-169157.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, the content of this invention is not restricted to an Example. In addition, a part and% show a mass part and the mass%.

  A degreased, washed, and dried surface of an ABS resin product is coated with an undercoat paint for silver mirror (Ohashi Chemical Industry Co., Ltd .; Under Black No. 0128) in a weight ratio of 10: 2: 4 to 5 with a curing agent and thinner. Then, after the solvent was volatilized, it was dried at 80 ° C. for 30 minutes to obtain a silver mirror film-formed surface.

  As an activation treatment solution for treating this silver mirror coating surface, a comparative activation treatment solution A containing 0.15 mol of hydrochloric acid and 0.06 mol of stannous chloride as hydrogen chloride per liter of water was prepared. did.

  As an activation treatment liquid, a comparative activation treatment liquid B containing 0.15 mol hydrochloric acid, 0.05 mol stannous chloride and 0.01 mol stannic chloride as hydrogen chloride per liter of water is used. Produced.

  After preparing the activation treatment liquid A, a comparative activation treatment liquid C was prepared by subjecting 1 liter of the activation treatment liquid A to an aeration treatment at an oxygen blowing rate of 30 liters for 1 hour for 1 hour.

  As the activation treatment liquid, the activation treatment liquid D of the present invention containing 0.15 mol hydrochloric acid, 0.06 mol stannous chloride, and 0.15 mol hydrogen peroxide as hydrogen chloride per liter of water. Produced.

  As the activation treatment liquid, the activation treatment liquid E of the present invention containing 0.06 mol of stannous chloride and 0.15 mol of hydrogen peroxide per liter of water was prepared.

  As the activation treatment liquid, the activation treatment liquid F of the present invention containing 0.05 mol of stannous chloride, 0.01 mol of stannic chloride, and 0.15 mol of hydrogen peroxide per liter of water is used. Produced.

  The storage stability of the activation treatment liquid was evaluated by the method described below. 500 ml of each of the activation treatment solutions was prepared and sealed in a commercially available polyethylene reagent bottle having an internal volume of about 1 liter. This was subjected to forced heating for 1 week and 3 weeks at a set temperature of 50 ° C., and the state of precipitation of the activation treatment liquid and the activity of the activation treatment liquid were examined.

  The precipitation state of the activation treatment liquid was evaluated in four stages by observing the activation treatment liquid after heating. ○ is a yellow activation treatment solution with no precipitation, ○ △ is an activation treatment solution with no precipitation but slightly cloudy, Δ is an activation treatment solution with no precipitation but white turbidity, and × is an activation treatment solution with precipitation. It is.

  Each of the activation treatment liquids was sprayed with a spray gun onto the surface of the base material on which the substrate obtained by the above method was formed, and washed with purified water.

  The activity of the activation treatment solution was evaluated by the method described below. Immediately after that, in order to examine the activity and storage activity, a hand spray was applied to the surface where the silver mirror film was formed (10 cm square each in the vertical and horizontal directions). To spray (a single discharge amount is about 1 ml). Subsequently, the silver mirror film is formed by spraying an aqueous solution (a) in which 10 g of silver nitrate is dissolved in 1 liter of deionized water with a spray gun and then applying the following plating solution for silver mirror. The activity was evaluated by the number of sprays of the activation treatment liquid necessary for obtaining a silver mirror film having a good mirror surface without the occurrence of unevenness that looks like Kusumi, and is shown in Table 1.

  The silver mirror plating solution was prepared as follows. First, 20 g of silver nitrate is dissolved in 1 liter of deionized water to obtain a liquid (1). Separately, 100 g of 28% ammonia aqueous solution and 5 g of monoethanolamine are dissolved in 1 liter of deionized water to obtain a liquid (2). Furthermore, these (1) liquid and (2) liquid were mixed 1: 1 to make an ammoniacal silver solution (A). Next, 10 g of hydrazine sulfate, 5 g of monoethanolamine and 10 g of sodium hydroxide were dissolved in 1 liter of deionized water to obtain a reducing solution (B).

  The silver solution (A) and the reducing solution (B) thus prepared were simultaneously sprayed onto the above-described silver mirror coating surface using a two-head spray gun to form a silver mirror and washed with purified water. . This spray gun allows a silver solution and a reducing solution to simultaneously reach the surface to be treated, and allows silver ions to be instantaneously reduced to form a silver mirror film.

  Finally, “PTC-02” manufactured by Fujikura Kasei Co., Ltd. was spray-coated on the surface of the silver mirror film and dried in an oven at about 70 ° C. for 70 minutes to form a topcoat layer.

  From the results shown in Table 1, the activation treatment liquids D to F of the present invention have good storage stability of the activation treatment liquid and are stable over a long period of time immediately after preparation of the activation treatment liquid. Hydrophilicity can be obtained. In addition, since the activation treatment liquids E and F of the present invention do not contain hydrochloric acid, there is an advantage that the apparatus such as a spray gun does not corrode.

Claims (2)

  In forming the silver mirror film on the surface of the base material, the activation treatment liquid containing the stannous compound for activating the surface of the base material on which the silver mirror film is formed contains hydrogen peroxide. An activation treatment solution for silver mirrors.   The activation treatment liquid for silver mirrors of Claim 1 which does not contain hydrogen chloride substantially.