JPH0124238B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention provides a method for applying a composite compound salt of chromium and phosphorus to the surface of a watch dial made of silver or a silver alloy, or a watch dial whose surface is plated with silver or a silver alloy. The present invention relates to a watch dial that is composed of a double anti-discoloration film consisting of an anti-discoloration film and a clear paint. It is an object of the present invention to prevent discoloration of a watch dial made of silver or all silver, or a watch dial plated with silver plating or silver alloy plating, for a long period of time, and to The objective of the present invention is to provide a decoratively valuable watch dial that is silvery white and has a beautiful luster. Conventionally, watch dials have been plated with silver or silver alloy and coated with clear paint to prevent discoloration. However, silver is susceptible to discoloration due to trace amounts of sulfide in the air, ultraviolet rays, etc., so there are some dials that discolor despite being coated with a protective coating. In addition, there are some problems with the adhesion of the clear paint to the silver-plated or silver alloy-plated surface, and furthermore, in hot and humid environments, the clear paint absorbs moisture and peels, which can cause discoloration of the silver. ing. On the other hand, in addition to the method of preventing discoloration using paint, there is a method of forming a chromic acid film on silver plating or silver alloy plating to prevent discoloration. This coating is very thin and has no long-term protective effect, and the adhesion of the coating is weak, so it often comes off just by touching it with your fingers. The present invention solves the above-mentioned problems and provides a watch dial that has a beautiful silvery-white and glossy color that lasts for a long time. [Example] Hereinafter, the present invention will be described according to an example shown in the drawings. FIG. 1 is a sectional view of a timepiece dial in which an anti-discoloration film is formed on the surface of the dial according to an embodiment of the present invention. B.S.
After punching the material into the shape of the specified dial 5, a small hole 6 is punched out.
The dial blank is completed by punching out, welding the edge 7, and forming the pattern 4. Next, the dial blank was degreased with trichlene and alkaline, and then pickled with dilute sulfuric acid, followed by nickel plating and bright silver plating 3. A transparent composite compound salt was applied on the silver plating 3 using the electrolytic solution and electrolytic conditions shown below. A discoloration prevention film 2 is applied. After forming the film, wash thoroughly with water and dry. <Electrolytic bath> Sodium tripolyphosphate ( _Na5P3O10 ) 80g/~85g/Sodium chromate ( _{Na2CrO4 ・ 4H2O} ) 20g/~ _25g /Surfactant 0.2%~ _0.3 % <Electrolytic conditions> Temperature 25°C to 30°C Current density 2A/dm ² to 2.5A/dm ² PH 11 to 12 Electrolysis time 120 to 150 seconds Anode plate Pt Next, coat the clear paint on the anti-discoloration film 2 of the composite compound salt. Then, a clear coating film 1 is formed. After setting a coating thickness of 8 μm to 10 μm and diluting the clear paint and thinner at a weight ratio of 6:5, add 0.01% by weight of silicone-based modified polysiloxane to the clear paint, and mix it with the paint by stirring with a propeller. Continue until the thinner and additives are thoroughly mixed. The modified polysiloxane additive is a surface active agent and is a leveling agent that prevents tin skin, clumps, etc. on the surface of the clear paint. The well-stirred clear paint is coated on the anti-discoloration film 2 using a coating machine, and after a 10-minute setting time, it is completely dried at 80°C for 30 minutes to form the anti-discoloration film of the clear coating film 1. . The compositions and coating conditions of the clear paint and thinner are described below, but it is desirable to select them within the following composition ratio range depending on the working environment. <Paint composition> Composition ratio (weight ratio) Acrylic resin 8-14% Vinyl resin 10-17% Cellulose resin 7-12% Ester solvent 18-25% Ketone solvent 28-35% Hydrocarbon solvent 8 ~15% Alcohol solvents 0.5-1.2% Ether solvents 0.8-1.5% <Thinner composition> Ester solvents 30-38% Ketone solvents 25-35% Ether solvents 10-18% Hydrocarbon solvents 5-13% Alcohol solvent 5-13% <Coating conditions> (air spray) Coating viscosity 13 seconds (±2 seconds) Film thickness 8 μm-10 μm Setting time 10 minutes-12 minutes Drying temperature 80°C, 30 minutes Next, the present invention The dial made in the example of
We investigated the functional quality of conventional dials, and the results are shown in Table 1. In addition, No. 1 is a dial blank with glossy silver plating, No. 2 is a conventional dial with clear paint applied on top of glossy silver plating, and No. 3 is a dial with clear paint applied on top of glossy silver plating. A discoloration prevention film of the composite compound salt of the invention is formed, and then a discoloration prevention film of a clear coating is formed thereon.

【table】

[Table] As shown in Table 1, the dial plate according to the present invention has improved functional quality compared to the conventional dial plate. In particular, the effect of the double discoloration prevention film has been shown to be effective against sulfides. A similar effect has also been observed for ultraviolet rays. As for the adhesion of the clear paint, it is coated on top of an anti-discoloration film made of a complex compound salt of chromic acid and phosphoric acid, which improves adhesion compared to conventional dials. On the other hand, regarding the appearance quality of the clear coating surface, due to the effect of the leveling agent polysiloxane, yuzu skin etc. were greatly reduced, and the quality was improved compared to the conventional dial. As described above, the watch dial made of silver or silver alloy of the present invention on which a double anti-tarnishing film is formed, or the watch dial made of silver plating or silver alloy plating, is free from sulfides and It has an excellent effect of preventing discoloration caused by ultraviolet rays, etc., and this effect lasts for a long time, and the adhesion of the clear coating film is also improved, resulting in improved functional quality compared to conventional dials. Furthermore, due to the improved smoothness of the clear coating film, it is possible to obtain a superior appearance quality than conventional dials without degrading the texture of silver, silver alloy, silver plating, or silver alloy plating, and it has remarkable practical effects. It is something that appears.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a dial plate in which the present invention is implemented. 1... Clear coating film, 2... Discoloration prevention film, 3... Glossy silver plating, 4... Pattern, 5... Dial plate, 6... Small hole, 7
...Etoashi.

Claims (1)

[Claims] 1. An anti-tarnish film made of a complex compound salt of chromium and phosphorus on the surface of a watch dial made of silver or silver alloy, or a watch dial whose surface is plated with silver or silver alloy, and A watch face plate characterized by being composed of a double anti-discoloration film with a clear coating film to which polysiloxane is added.