JP2004190061A - Method of manufacturing silver mirror film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the corrosion resistance and discoloration resistance of a silver mirror film deposited on a surface of various kinds of base materials by a method in which a silver mirror reaction is performed after activation by stannous ions. <P>SOLUTION: A surface of a base material is activated by stannous ions, treated with silver ions, and subjected to the silver mirror reaction to deposit a silver mirror film. After the silver mirror deposition, treatment is performed with a thiosulfate. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of forming a base layer (base coat / undercoat) directly or on a surface of a base material such as plastic, metal, glass, rubber, ceramics, wood, bamboo, leather, and styrofoam. And a method for forming a silver mirror film.
[0002]
[Prior art]
As a method of forming a silver mirror film on the surface of various substrates, for example, the following methods are known. That is, first, by immersing in a hydrochloric acid aqueous solution containing stannous ions or palladium ions, or by activating the substrate surface by spraying the solution with a spray gun, stannous ions or palladium Adsorb ions. After washing off the excess activating solution by washing with water, a known silver mirror plating solution, for example, a silver mirror plating solution comprising a silver ammonia solution and a reducing agent is sprayed with a double spray gun to form a silver mirror coating. Thereafter, the substrate is washed with deionized water and dried (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-11-335858 [0004]
[Problems to be solved by the invention]
The silver mirror film obtained by the conventional silver mirror forming method described above has poor corrosion resistance due to residual chlorine ions, and it is hard to say that the adhesion of the silver mirror film to the substrate surface is sufficient due to displacement plating.
[0005]
Further, due to the nature of silver as a metal, the coloration resistance and the like are poor. For this reason, when the silver mirror film comes into direct contact with the environmental atmosphere, it is common to protect the silver mirror film by applying a top coat such as clear coating.
[0006]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve the above-mentioned problems relating to the formation of the silver mirror film. First, the surface of the base material was activated with stannous ions, and then the surface of the activated base material was treated with silver. The silver mirror coating formed on the surface of the substrate is subjected to a corrosion resistance (neutral salt spray test) by performing a silver mirror coating forming reaction using a silver mirror plating solution composed of a silver ammonia solution and a reducing agent. Is significantly improved.
[0007]
In addition, the present inventors performed a silver mirror film forming reaction according to the above method and washing with deionized water, followed by treatment with an aqueous solution containing a thiosulfate to cause discoloration such as uneven color, cloudiness, or yellowing. It was found that a uniform silver-white appearance free from defects was obtained.
[0008]
Accordingly, an object of the present invention is to activate a substrate such as plastic, metal, ceramics, wood, or the like directly or after forming an underlayer, with stannous ions or palladium ions, and then subject it to a silver mirror reaction. In the method of forming a silver mirror film, the method comprises the steps of: activating with a stannous ion or palladium ion, subjecting to a treatment with silver ions, and then performing a silver mirror reaction. To provide.
[0009]
Another object of the present invention is to provide a method for forming a silver mirror film, which comprises treating the silver mirror film with an aqueous solution containing thiosulfate after forming the silver mirror film.
[0010]
According to the method for forming a silver mirror film of the present invention, after the activation treatment, extra adhesion and remaining on the surface of the base material, tin causing a decrease in the adhesion of the silver mirror film, and causing deterioration in corrosion resistance. The treatment with silver ions eliminates residual chlorine ions as much as possible, and has an effect of adapting silver ions to the surface of the substrate on which a silver mirror film is to be formed.
[0011]
When a silver ammine complex and a reducing agent act on the surface familiar with the silver ions, a substitution reaction occurs between silver and tin, and a silver mirror film is formed smoothly.
[0012]
After the formation of the silver mirror film, washing is performed using deionized water in order to remove excess silver mirror plating solution adhering to the surface. However, since the silver mirror plating solution is ammonia alkaline, the plating solution cannot be sufficiently washed away by washing with water.
[0013]
According to the present invention, after the formation of the silver mirror film, by treating with a thiosulfate, the unreacted ammonia and the ammine complex of silver which still remain on the surface of the silver mirror film can be eliminated and, at the same time, remain. Possible traces of silver chloride can be dissolved and eliminated. Therefore, it is possible to prevent a slight unreacted substance from remaining, and to prevent the appearance of poor appearance such as partial fogging and yellowing of the surface of the silver mirror film which occurs within a short time.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
The method for forming a silver mirror according to the present invention will be described in detail with reference to FIG.
[0015]
First, degreasing is performed to clean the surface of the substrate (step 1). In the degreasing step, various types of degreasing agents already generally used in the art can be used according to the type of the base material.
[0016]
Next, the substrate is washed with water to remove the degreasing agent attached to the substrate (Step 2), and dried at room temperature to 80 ° C. to remove moisture (Step 3).
[0017]
Subsequently, in order to enhance the adhesion between the substrate and the silver mirror film, when the substrate is metal or ceramic, a special base coat paint (primer) is applied (Step 4), and then at room temperature to 80 ° C. Dry (step 5).
[0018]
Thereafter, an undercoat paint is applied (Step 6) and dried at room temperature to 80 ° C (Step 7).
[0019]
When the base material is plastic, there is no need to apply a base coat except for some plastics (thus, steps 4 and 5 are omitted).
[0020]
When no paint is used, that is, when a silver mirror film is formed directly on the surface of the substrate (for example, in the case of glass), the above steps 4 to 7 can be omitted.
[0021]
The substrate surface adjusted as described above is subjected to conventionally known activation treatment (activation treatment) with stannous ions and palladium ions (step 8). The activation liquid used for the activation treatment is an aqueous solution obtained by dissolving 5 g of stannous chloride and 10 ml of 35% hydrochloric acid in 1 L of tap water. In the activation treatment, the substrate surface adjusted as described above is immersed in the aqueous solution, or the aqueous solution is sprayed on the substrate surface by a spray gun substrate.
[0022]
Thereafter, the substrate is immersed in deionized water and washed, or deionized water is sprayed on the surface of the base material by a spray gun to wash off excess activating liquid from the surface of the base material (step 9).
[0023]
Subsequently, a treatment with silver ions is performed according to the present invention (step 10). In this treatment, an aqueous solution containing 0.01 to 0.3 mol, preferably 0.05 to 0.1 mol of silver nitrate in 1 L of deionized water is used, and this aqueous solution is sprayed on the surface of the substrate by a spray gun. It is implemented by.
[0024]
After the treatment, a conventionally known silver mirror plating solution is sprayed on the surface of the base material by a double spray gun without washing with water to form a silver mirror film (step 11).
[0025]
The silver mirror plating solution to be used is, for example, a silver ammonia aqueous solution obtained by dissolving 0.1 mol of silver nitrate and 0.4 mol of ammonia (as aqueous ammonia) in 1 liter of deionized water, and separately in 1 liter of deionized water. And a reducing agent solution prepared by dissolving 0.2 mol of formalin. Each solution is stored in a separate pumping tank, and at the time of use, both solutions are simultaneously sprayed onto a surface treated with silver ions by a double spray gun to form a silver mirror film.
[0026]
After the silver mirror film is formed, deionized water is quickly sprayed with a spray gun to wash away the extra silver mirror plating solution (step 12).
[0027]
Next, a stabilization treatment with the thiosulfate of the present invention is performed (Step 13). This stabilization treatment is performed by spraying an aqueous solution containing 0.01 to 0.2 mol, preferably 0.03 to 0.1 mol of thiosulfate in 1 L of deionized water with a spray gun to form a silver mirror film on the surface. It is done by spraying.
[0028]
After the stabilization treatment (Step 13), the substrate is washed by spraying deionized water with a spray gun (Step 14), dried at room temperature to 80 ° C. (Step 15), and, if necessary, further formed as a silver mirror film. A top coat such as a clear coat is applied thereon (step 16) and dried at room temperature to 80 ° C (step 17).
[0029]
Next, a method for forming a silver mirror film according to the present invention will be described based on examples. However, the present invention is not limited to these examples.
[0030]
Embodiment 1
The plate-like ABS resin product is degreased with a neutral detergent, washed with water and dried, and a commercially available undercoat paint (manufactured by Ohashi Chemical Industry Co., Ltd .; under black No. 0128) is applied to the surface of the base material thus treated. The mixture was applied to the thinner together with a curing agent at a ratio of 10: 2: 4 to 5 and then the thinner was evaporated, followed by drying at 80 ° C. for 30 minutes.
[0031]
The activation treatment liquid consisting of an aqueous solution obtained by dissolving 5 g of stannous chloride and 10 ml of 35% hydrochloric acid in 1 L of tap water is sprayed on the surface of the base material thus adjusted with a spray gun, and the activation treatment is performed. went. Subsequently, cleaning was performed by spraying deionized water with a spray gun.
[0032]
Next, a treatment liquid prepared by dissolving 0.1 mol of silver nitrate in 1 L of deionized water was sprayed on the surface of the substrate that had been activated and washed with deionized water, using a spray gun.
[0033]
An aqueous silver ammonia solution obtained by dissolving 0.1 mol of silver nitrate and 0.4 mol of ammonia (as aqueous ammonia) in 1 liter of deionized water and 1 liter of formalin in 1 liter of deionized water A silver mirror plating solution composed of a reducing agent solution prepared by dissolving 0.2 mol was sprayed with a double spray gun to form a silver mirror film.
[0034]
Immediately after the silver mirror film was formed in this way, the surface of the silver mirror film was washed by spraying deionized water with a spray gun.
[0035]
Subsequently, a stabilization treatment is performed by spraying a stabilization treatment solution prepared by dissolving 0.1 mol of sodium thiosulfate in 1 L of deionized water on a surface of the silver mirror film washed with deionized water by a spray gun, Thereafter, the substrate was washed by spraying deionized water with a spray gun. In order to remove moisture adhering to the surface of the silver mirror film, the film was drained by air blow and dried at 80 ° C. for 10 minutes.
[0036]
Finally, a commercially available top coat (manufactured by Ohashi Chemical Industry Co., Ltd .; TDM Clear) is mixed with a curing agent in a thinner at a weight ratio of 10: 2: 4 to 6 on the silver mirror film, and spray-coated. At 70 ° C. for 40 minutes.
[0037]
The silver mirror film-formed product prepared as described above was subjected to a neutral salt spray test or a salt solution immersion test by performing a cross-cut as described below, and the corrosion resistance of the silver mirror film was evaluated in comparison with a comparative product.
[0038]
Embodiment 2
A silver mirror film-formed product was manufactured in the same manner as in Example 1 except that the stabilization treatment with thiosulfate was omitted.
[0039]
[Comparative Example 1]
A silver mirror film-formed product was manufactured in the same manner as in Example 1 except that the treatment with silver ions was omitted.
[0040]
[Comparative Example 2]
A silver mirror film-formed product was manufactured according to a conventionally known processing method, that is, omitting the treatment with silver ions and the stabilization treatment with thiosulfate in the operation of Example 1 described above.
[0041]
Corrosion resistance test Prior to the evaluation test, the surface of the plate-like silver mirror film was cross-cut. Cuts were made in the depth direction by a sharp cutter knife in the depth direction at intervals of 5 mm until reaching the ABS resin of the base material, thereby forming a total of 10 grids. This was subjected to an evaluation test described below.
[0042]
The neutral salt spray test was carried out according to JIS H8502: 1999, section 7.1.
[0043]
On the other hand, in the saline immersion test, the silver mirror film-formed product was immersed in a saline solution prepared by dissolving 5 g of sodium chloride in 1 L of deionized water while maintaining the temperature of the solution at 25 ± 1 ° C. It was carried out by.
[0044]
In each case of the neutral salt spray test and the salt solution immersion test, the silver mirror film-formed product was immediately washed with deionized water after the test was completed, and the corrosion, discoloration, and peeling state of the silver mirror film surface were visually observed and evaluated. .
[0045]
Test results- The silver mirror film-formed product of Example 1 showed no evidence of corrosion from the cross-cut portion and no peeling of the silver mirror film in the neutral salt spray test for 240 hours. No abnormal change such as discoloration was observed in the portions other than the cross cut. In the salt water immersion test, no evidence of corrosion from the cross-cut portion and no peeling of the silver mirror film were observed even after immersion for 500 hours, and no abnormal changes such as discoloration were observed on the surface other than the cross-cut. Did not.
-In the silver mirror coating formed product of Example 2, in the neutral salt spray test for 120 hours, almost no corrosion was observed in the cross-cut portion, but most of the silver mirror coating was discolored from yellow to white.
-In the silver mirror film-formed product of Comparative Example 1, in a 120-hour neutral salt spray test, blackening (corrosion) and peeling of the silver mirror film were observed on a part of the line of the cross-cut portion. No change such as discoloration was observed on the surface of the silver mirror film other than the cross cut.
-In the silver mirror film-formed product of Comparative Example 2, in the neutral salt spray test for 96 hours, blackening due to corrosion and peeling of the film occurred from the cross-cut portion, and the silver mirror film was entirely discolored from yellow to white Was. In the saline immersion test, the silver mirror film was corroded and peeled not only at the cross cut portion but also over the entire surface in 72 hours, and the peeled film was discolored from yellow to white.
[0046]
From the above test results, according to the present invention, the treatment with silver ions after the activation treatment and before the formation of the silver mirror film improves the corrosion resistance of the silver mirror film, and the stabilization treatment with thiosulfate after the formation of the silver mirror film. It is clear that the resulting silver mirror coating improves the discoloration resistance of the formed silver mirror coating.
[0047]
Embodiment 3
The pottery figurine was degreased using a neutral detergent, washed with water and dried. A commercially available base coat paint (primer) (manufactured by Ohashi Chemical Industry Co., Ltd .: Primer K) was mixed and applied with the thinner in a weight ratio of 10: 5 to 6 on the surface of the ornament, and the thinner was evaporated. Dry at 70 ° C. for 15 minutes. The same undercoat paint as in Example 1 was applied to the thus treated ornament by the same operation method as in Example 1.
[0048]
The surface of the base material of the pottery figurine painted in this manner is activated with stannous ions, washed with deionized water, treated with silver ions, silver mirror film formation, and deionized according to the same operation method as in Example 1. The steps of washing with water, stabilizing treatment with thiosulfate, washing with deionized water, and drying were sequentially performed.
[0049]
In the appearance of the obtained silver mirror film, no yellowing or white haze was observed by visual observation.
[0050]
A top coat was applied on the silver mirror film in the same manner as in Example 1, dried at 70 ° C. for 40 minutes, and then allowed to cool to room temperature. The results were the same as before the topcoat coating.
[0051]
[Comparative Example 3]
For comparison, a silver mirror film was formed in the same manner as in Example 3, except that the treatment with silver ions and the stabilization treatment with thiosulfate were omitted. As a result, the appearance of the silver mirror film before the top coat treatment was almost the same as that in Example 3, except that the top coat was applied, dried at 70 ° C. for 40 minutes, allowed to cool to room temperature, and visually observed. , The whole appearance was yellowing.
[0052]
【The invention's effect】
According to the present invention, in a method for forming a silver mirror film, a silver mirror film is formed by performing a conventionally known activation treatment with stannous ions, followed by a treatment with silver ions, and then forming a silver mirror film. The corrosion resistance of the silver mirror film can be significantly improved, and the discoloration resistance of the silver mirror film can be significantly improved by performing a stabilization treatment with a thiosulfate subsequent to the formation of the silver mirror film.
[Brief description of the drawings]
FIG. 1 is a process chart showing a preferred embodiment of a method for forming a silver mirror film according to the present invention.

Claims (2)

A substrate such as plastic, metal, porcelain, wood, or the like is directly or after forming an underlayer, activated with stannous ions or palladium ions, and then subjected to a silver mirror reaction to form a silver mirror film. A method for forming a silver mirror film, comprising: after the activation treatment with stannous ions or palladium ions, performing a treatment with silver ions, and then performing a silver mirror reaction to form a silver mirror film. 2. The method for forming a silver mirror coating according to claim 1, further comprising, after forming the silver mirror coating, a treatment with an aqueous solution containing thiosulfate.

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