JP4539101B2 - Formation method of silver mirror film - Google Patents

Description

  The present invention relates to a method for forming a silver mirror film that prevents whitening of the silver mirror film formed on a substrate.

  In order to give a specular gloss to a base material such as glass or resin, for example, when the base material is glass, a chemical plating layer utilizing a silver mirror reaction is conventionally formed on the glass surface. When the base material is a resin molded product, a primer layer, a specular reflection layer, and a clear layer are sequentially formed on the surface of the base material to give a specular gloss.

  For example, a primer layer (first layer), a specular reflection layer (second layer), and a clear layer (third layer) are sequentially provided on the surface of a base material made of plastic or metal, and at least the first layer to the third layer are provided. The coating body in which any one layer was formed with the coating composition containing a benzothiazole type metal deactivator is proposed (for example, patent document 1).

  Also, in the resin component plating method, anchor grooves are formed on the surface of the component, the surface of the component is activated by an activation treatment agent containing hydrogen chloride and stannous chloride solution, and the surface of the activated resin component is electrolessly plated. There has been proposed a plating method in which electroplating is performed on the surface of a component after applying conductivity to impart conductivity (for example, Patent Document 2). Here, the solution used for silver mirror plating in electroless plating is composed of solution A and solution B in order to eliminate fluctuations in pH, and solution A contains ammonia water, ammoniacal silver nitrate solution and ammonium hydroxide. On the other hand, the B liquid contains glucose and sodium hydroxide.

  Further, a method has been proposed in which a coating including an electroless plating layer is formed on at least a part of the inner surface of the container, and the coating includes at least a primer layer and a silver plating layer (for example, Patent Document 3). . The primer layer contains titanium alkoxide, and when a silver plating layer is formed on the primer layer, the primer layer is activated in advance, and a) an inorganic acid such as hydrochloric acid and / or formic acid, After contacting an organic acid such as acetic acid with the primer layer, b) contacting a hydrochloric acid acidic stannous chloride aqueous solution with the primer layer, c) contacting an aqueous solution containing palladium ions and tin (II) ions with the primer layer , Contacting an activation treatment solution containing sulfuric acid (accelerator-accelerator method), d) contacting a hydrochloric acid acidic stannous chloride aqueous solution and a hydrochloric acid acidic palladium chloride aqueous solution simultaneously with the primer layer (sensitizer-activator method), e) An aqueous solution of palladium chloride or palladium sulfate and a reducing solution containing sodium hypophosphite etc. are simultaneously brought into contact with the primer layer (acrylic). Over data - to adopt either of the accelerator method) has been proposed.

  Moreover, in the manufacturing method of the plating product provided with the base coat, the metal plating layer, and the top coat layer on the surface of the base material, by applying a reducing solution containing sulfite ions on the surface of the metal plating layer, the surface of the metal plating layer is applied. There has been proposed a method of imparting a highly polar hydroxyl group, increasing the bonding point between the metal plating layer and the topcoat layer by intermolecular force, and improving the adhesion strength between the two layers (for example, Patent Document 4).

JP 2003-238901 A JP 2003-105588 A JP 2000-104175 A JP 2003-293146 A

  However, any of the methods described above cannot sufficiently prevent defects due to whitening in the metal plating layer, particularly the silver mirror film, and it is difficult to obtain the desired brightness of the silver mirror film.

  This invention is made | formed in view of the said subject, and it aims at providing the formation method of the silver mirror film which prevents the whitening of a silver mirror film and improves the brightness of a film.

  In order to achieve the above object, the method for forming a silver mirror film of the present invention has the following characteristics.

(1) In a silver mirror coating film provided with a primer layer and a silver mirror film layer on the substrate surface, a first step of forming the primer layer on the substrate surface, and an activator applied to the surface of the primer layer 2 steps, a third step of applying a silver medicinal solution after application of the activator, then washing and draining, and a fourth step of draining and drying, and the silver medicinal solution in the third step The coating amount is 4.1 × 10 ⁻² g / cm ² or more and 8.2 × 10 ⁻² g / cm ² or less in terms of silver atoms, and the concentration of the activator in the second step is 5. This is a method for forming a silver mirror film of 0 × 10 ⁻³ g / liter or less.

  In the above-mentioned process, by using the above-mentioned silver chemical solution coating amount, there is no excess silver on the primer layer, and by setting the concentration of the above-mentioned activator, excess activator remains. Without this, whitening of the obtained silver mirror film can be prevented.

(2) In a silver mirror coating film provided with a primer layer and a silver mirror film layer on the surface of the substrate, a first step of forming the primer layer on the surface of the substrate, and an activator applied to the surface of the primer layer Two steps, a third step of applying a silver medicinal solution after application of the activator, washing with water and then draining, and a fourth step of draining and drying, at the time of draining and drying in the fourth step The concentration of hydrochloric acid in the drying furnace atmosphere is 1.2 × 10 ⁻⁵ g / liter or less, and the silver nitrate concentration on the surface of the silver mirror coating is 5.0 × 10 ⁻³ g / liter or less. It is.

In the above-described process, by setting the hydrochloric acid concentration in the atmosphere in the drying furnace at the time of draining and drying to the above range, there is no excess hydrochloric acid in the drying furnace atmosphere, and there is no possibility of causing an unexpected reaction. As a result, there is no possibility that the crystal aggregates and the silver mirror film is whitened. Further, by controlling the silver nitrate concentration on the surface of the silver mirror film, unreacted silver ions (Ag ⁺ ) do not remain on the surface of the silver mirror film, and there is no possibility of causing whitening defects.

  (3) In the method for forming a silver mirror film as described in (1) or (2) above, the silver chemical solution comprises an ammoniacal silver nitrate solution and a reducing agent solution.

  (4) In the method for forming a silver mirror film according to (1) or (2) above, the activator contains tin chloride [II] and hydrochloric acid.

  (5) A coated body in which a silver mirror film is formed by the method for forming a silver mirror film according to any one of (1) to (4) above.

  A coated body having sufficient brightness without whitening of the silver mirror film can be obtained.

  According to the present invention, it is possible to obtain a silver mirror film having sufficient brightness without causing a whitening defect.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  A method for forming the silver mirror film of the present embodiment will be described with reference to FIGS.

  As shown in FIGS. 1 and 2, in the method of forming a silver mirror film of the present embodiment, in the first step, a primer is applied to the surface of the substrate 30 (S10), and then the primer is baked to obtain a primer layer. 32 is formed (S12). Next, in the second step, an activator is applied to the surface of the primer layer 32 (S14), and in the third step, after applying the activator, a silver medicinal solution is applied (S16), Thereafter, it is washed with water (S18) and drained by air blow (S20). Next, draining and drying are performed in the fourth step (S22). The primer may be dried after application.

  Furthermore, the formation method of the silver mirror film of this Embodiment is demonstrated in detail.

  Examples of the resin composition suitable for the primer in the first step include acrylic urethane resin, polyester urethane resin, epoxy resin, styrenated alkyd (urethane) resin, acrylated alkyd (urethane) resin, α-methylstyrene or alkyd. (Urethane) resin, epoxy ester / acrylic urethane resin, tertiary amino group-containing acrylic resin / hydrolyzable silyl group-containing compound, acrylic silicon resin (NCO cross-linking type, siloxane bond type), and the like.

  The activator in the second step is not particularly limited as long as it contains tin [II] chloride. For example, an aqueous solution containing hydrochloric acid acidic stannous chloride (that is, an aqueous solution containing tin [II] chloride and hydrochloric acid). ), A combination of an aqueous solution containing palladium ion and tin (II) ion and an activation treatment solution containing sulfuric acid (accelerator-accelerator method), a combination of hydrochloric acid acidic stannous chloride aqueous solution and hydrochloric acid acidic palladium chloride aqueous solution ( Sensitizer-activator method).

Moreover, the silver chemical | medical solution in a 3rd process consists of the aqueous solution containing silver complex ion, and the solution containing a reducing agent. Here, as the aqueous solution containing silver complex ions, it is preferable to use an ammoniacal silver nitrate ([Ag (NH ₃ ) ₂ ] ⁺ OH ⁻ ) solution (Trens reagent). The ammoniacal silver nitrate solution can be obtained by dissolving silver nitrate in pure water or distilled water, and adding ammonia water dropwise while stirring the aqueous solution until the black precipitate disappears and the aqueous solution becomes transparent. Moreover, you may add sodium hydroxide to this ammoniacal silver nitrate solution. As a result, the reduction reaction can be promoted, so that the reaction time can be adjusted by the combination of the type and concentration of the reducing agent. Further, a surfactant can be added to the ammoniacal silver nitrate solution. By adding the surfactant, wettability with the primer layer is improved, and adhesion and adhesion between the silver mirror film layer and the primer layer are improved. The surfactant is preferably added in an appropriate amount in order to reduce the rate of reduction of the silver complex ions.

  The solution containing the reducing agent (that is, the reducing agent solution) is not particularly limited as long as it is a solution containing a water-soluble reducing agent capable of reducing the silver complex ions. For example, an aqueous solution containing formaldehyde, formalin, gluoxal, hydrazine sulfate, etc., having a relatively strong reducing power, and an aqueous solution containing glucose, Rochelle salt, sucrose nitrate conversion, etc., having a relatively weak reducing power Etc.

In the method for forming a silver mirror film of the first embodiment of the present invention, the coating amount of the silver chemical solution in the third step is 4.1 × 10 ⁻² g / cm ² or more and 8.2 × in terms of silver atoms. 10 ⁻² g / cm ² or less, and the concentration of the activator in the second step is preferably 1.0 × 10 ⁻⁴ g / liter or more and 5.0 × 10 ⁻³ g / liter or less. .

When the coating amount of the silver agent is less than 4.1 × 10 ⁻² g / cm ^{2 in} terms of silver atoms, the oxidation-reduction reaction in the electroless plating method becomes insufficient and the base is visible. On the other hand, when the coating amount of the silver agent exceeds 8.2 × 10 ⁻² g / cm ² in terms of silver atoms, whitening of the silver mirror film occurs.

On the other hand, when the concentration of the activator is less than 1.0 × 10 ⁻⁴ g / liter, activation of the primer layer becomes insufficient, silver is hardly precipitated, and formation of a silver mirror film becomes insufficient. On the other hand, when the concentration of the activator exceeds 5.0 × 10 ⁻³ g / liter, the degree of whitening of the silver mirror film increases.

In the method for forming a silver mirror film according to the second embodiment of the present invention, the hydrochloric acid concentration in the drying furnace atmosphere at the time of draining and drying in the fourth step is 1.2 × 10 ⁻⁵ g / liter or less. The silver nitrate concentration on the surface of the silver mirror film is preferably 5.0 × 10 ⁻³ g / liter or less.

  The concentration of hydrochloric acid in the drying furnace atmosphere at the time of draining and drying is controlled by hydrochloric acid evaporating from the container placed in a drying furnace. In addition, by controlling the concentration to be equal to or lower than the above concentration, there is no possibility of unexpected reaction due to hydrochloric acid existing excessively in the drying furnace, and as a result, crystals aggregate in the silver mirror film and cause whitening. There is no fear.

Moreover, when the silver nitrate concentration on the surface of the silver mirror film after the fourth step, that is, after the fourth step exceeds 5.0 × 10 ⁻³ g / liter, the washing with the silver chemical solution is insufficient. As a result, unreacted silver ions (Ag ⁺ ) remain on the surface of the silver mirror film, which may cause whitening defects.

  Hereinafter, the present invention will be described in more detail with reference to experimental examples, but the present invention is not limited to these experimental examples.

Experimental Example 1
[Experimental conditions]
In the process of forming the silver mirror film shown in FIG. 1, the primer baking process was performed at 85 ° C. for 90 minutes, and the draining and drying process was performed at 85 ° C. for 10 minutes. Furthermore, “0128” manufactured by Ohashi Chemical Co., Ltd. is used as a primer, “K103” of Metal Processing Technology Laboratory is used as an activator, and “LAX-LBX” of Metal Processing Technology Laboratory is used as a silver chemical solution. The experiment was conducted. FIG. 3 and FIG. 4 show the relationship between the silver drug solution application amount, the surplus Sn ²⁺ concentration after application of the activator, and the brightness of the silver mirror film. If the concentration of the activator in the second step is too high, the excess Sn ²⁺ concentration tends to increase.

[Evaluation by brightness]
The lightness L values in FIGS. 3 and 4 were measured using a variable angle spectrocolorimeter GSP-2 (manufactured by Murakami Color) at an incident light angle of 45 ° and a light receiving angle of −80 °. In addition, the evaluation “no whitening” was made with a lightness L value of 10 or less.

[Evaluation results]
From FIG. 3, it was found that the silver chemical solution coating amount is preferably 4.1 × 10 ⁻² g / cm ² or more and 8.2 × 10 ⁻² g / cm ² or less in terms of silver atoms. In addition, from FIG. 4, it is preferable that the surplus Sn ²⁺ concentration after application of the activator is 5.0 × 10 ⁻³ g / liter or less, and as a result, the concentration of the activator in the second step is 5.0 × 10 ⁻³ g / liter or less was found to be preferable.

Experimental Example 2.
[Experimental conditions]
In the process of forming the silver mirror film shown in FIG. 1, the primer baking process was performed at 85 ° C. for 90 minutes, and the draining and drying process was performed at 85 ° C. for 10 minutes. Furthermore, “0128” manufactured by Ohashi Chemical Co., Ltd. is used as a primer, “K103” of Metal Processing Technology Laboratory is used as an activator, and “LAX-LBX” of Metal Processing Technology Laboratory is used as a silver chemical solution. The experiment was conducted. FIG. 5 and FIG. 6 show the relationship between the hydrochloric acid concentration in the drying furnace atmosphere, the silver nitrate concentration remaining on the surface of the silver mirror coating, and the brightness of the silver mirror coating.
[Evaluation by brightness]

  The lightness L values in FIGS. 5 and 6 were measured using a variable angle spectrocolorimeter GSP-2 (manufactured by Murakami Color) at an incident light angle of 45 ° and a light receiving angle of −80 °. In addition, the evaluation “no whitening” was made with a lightness L value of 10 or less.

[Evaluation results]
From FIG. 5, it was found that the hydrochloric acid concentration in the drying furnace atmosphere during draining drying is preferably 1.2 × 10 ⁻⁵ g / liter or less. Further, FIG. 6 shows that the silver nitrate concentration on the surface of the silver mirror film is preferably 5.0 × 10 ⁻³ g / liter or less.

  The method for forming a silver mirror film of the present invention is effective for an object to be coated that requires a silver mirror film that prevents whitening.

It is a figure explaining the flow in an example of the formation method of the silver mirror film of the present invention. It is sectional drawing of the coating body in which the primer layer and the silver mirror film layer are formed in the base-material surface. It is a figure which shows the relationship between the coating amount of the silver chemical | medical solution of Experimental example 1 in the formation method of the silver mirror film of this invention, and the brightness of a silver mirror film. It is a figure which shows the relationship between the excess SN2 ⁺ density | concentration after the activation agent application | coating of Experimental example 1 in the formation method of the silver mirror film of this invention, and the brightness of a silver mirror film. It is a figure which shows the relationship between the hydrochloric acid density | concentration in the atmosphere in the drying furnace of Experimental example 2 in the formation method of the silver mirror film of this invention, and the brightness of a silver mirror film. It is a figure which shows the relationship between the silver nitrate density | concentration which remained on the silver mirror film surface of Experimental example 2 in the formation method of the silver mirror film of this invention, and the brightness of a silver mirror film.

Explanation of symbols

  30 base material, 32 primer layer, 34 silver mirror film layer.

Claims (5)

In silver mirror coating film with primer layer and silver mirror film layer on the substrate surface,
A first step of forming the primer layer on the substrate surface;
A second step of applying an activator to the surface of the primer layer;
A third step of applying a silver medicinal solution after application of the activator, washing with water and draining;
A fourth step of performing draining and drying,
The coating amount of the silver chemical solution in the third step is 4.1 × 10 ⁻² g / cm ² or more and 8.2 × 10 ⁻² g / cm ² or less in terms of silver atoms,
The method for forming a silver mirror film, wherein the concentration of the activator in the second step is 5.0 × 10 ⁻³ g / liter or less. In silver mirror coating film with primer layer and silver mirror film layer on the substrate surface,
A first step of forming the primer layer on the substrate surface;
A second step of applying an activator to the surface of the primer layer;
A third step of applying a silver medicinal solution after application of the activator, washing with water and draining;
A fourth step of performing draining and drying,
The hydrochloric acid concentration in the drying furnace atmosphere during the draining and drying in the fourth step is 1.2 × 10 ⁻⁵ g / liter or less,
A method for forming a silver mirror film, wherein the silver nitrate concentration on the surface of the silver mirror film is 5.0 × 10 ⁻³ g / liter or less. In the formation method of the silver mirror film of Claim 1 or Claim 2,
The silver mirror solution is composed of an ammoniacal silver nitrate solution and a reducing agent solution. In the formation method of the silver mirror film of Claim 1 or Claim 2,
The method for forming a silver mirror film, wherein the activator contains tin chloride [II] and hydrochloric acid. The coating body in which the silver mirror film was formed by the formation method of the silver mirror film of any one of Claims 1-4.

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