JPS5867867A - Outer part for watch - Google Patents

Abstract

PURPOSE:To give colored metallic luster to an outer part made of a metal or alloy for a watch and to improve its corrosion resistance, by applying a Cu-Sn alloy plating layer and then a Pd-Ni alloy plating layer to the outer part, and heat-treating the plated outer part in vacuum. CONSTITUTION:An outer part made of a metal or alloy for a watch is coated with a Cu-Sn alloy plating layer. Thereafter, a Pd-Ni alloy plating layer is applied thereonto, the plated outer part is heat-treated in a vacuum atmosphere, and air is fed in immediately after the heat-treatment without lowering a temperature. In this case, the composition of the Pd-Ni alloy and the temperature for the heat-treatment are properly changed to obtain the outer part having metallic luster of various tones.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exterior part for a timepiece, and more particularly to an exterior part for a timepiece that has a colored metallic luster and is excellent in corrosion resistance.

Traditionally, the exterior parts of watches (cases, bands, dials, dial rings, tension rings, etc.) were often plated with metal, and the color tones were only white or gold, with no other color tones. In addition, methods for obtaining external parts for watches that have color tones other than metal plating include:
There is a method of painting the surface, but it is difficult to obtain a metallic luster.

Furthermore, as a method for obtaining exterior parts for watches that have a colored film with a metallic luster, there is a method of forming a metal compound film by a method such as vapor deposition, but this method has the advantage of being able to obtain metallic luster in various tones. However, there were drawbacks such as poor corrosion resistance due to the inability to form a thick film.

In order to improve the above-mentioned problems, the present invention aims to provide an exterior part for a watch that has a colored metallic luster and excellent corrosion resistance based on the results of numerous experiments and research. A watch exterior part made of metal or alloy is coated with copper-tin alloy plating, further plated with palladium-nickel alloy, and then heat treated in vacuum. It is.

The copper-tin alloy plating mentioned here is most preferably a copper-tin alloy with a tin content of 40 to 45% in order to maintain corrosion resistance as an exterior part for a watch.

In addition, palladium-nickel alloy plating is a film for imparting a colored film with metallic luster, and by varying the alloy composition, various color tones can be obtained by heat treatment as post-treatment.

Furthermore, various methods can be considered for the heat treatment, but the most preferable method is to perform the heat treatment in a vacuum with atmospheric air and immediately introduce air without lowering the temperature after the heat treatment in order to obtain a uniform color tone. . Further, the color tone can be varied depending on the heat treatment temperature.

The present invention will be explained in detail below with reference to Examples.

First, the watch case fabric made of brass material is plated with bronze bronze-alkaline stannic acid copper-tin alloy (tin content: 40-4
A watch case finished with palladium-nickel alloy plating was created by applying 5 microns of 5%) and then applying 1 micron of palladium-nickel alloy plating with a palladium content of 50% using a palladium-nickel alloy plating bath.

This case is heated to 300 to 500 using a vacuum heat treatment equipment.
Heat treatment was performed at υ, air was introduced immediately after the heat treatment, the temperature was lowered, and when taken out, a watch case with a metallic luster in the color tone shown in the table was obtained.

Table Heat Treatment Temperature and Color (Based on Heat Treatment Temperature) Color Tone 300 Slightly whitish gold 400 Pale pink 500 Dark blue Also, regarding the corrosion resistance of this watch case, we conducted an artificial sweat immersion test (soaked for 5 days) and found no corrosion. Moreover, no change in color tone was observed.

As described above, according to the present invention, palladium-nickel alloy plating, which also has good corrosion resistance, is applied on copper-tin alloy plating, which has good corrosion resistance, and the surface is colored by heat treatment, so that it has good corrosion resistance. This makes it possible to obtain a metallic luster with a beautiful tone.

In addition, regarding copper-tin alloy plating, the same effect can be obtained with a bath from other than the example, and the same effect can be obtained with a palladium-nickel alloy also with a composition other than the example.

Also, in the examples, a watch case was described, but
Needless to say, it can be applied to other parts as well.
It goes without saying that other materials than brass are also possible for the fabric.

that's all Applicant: Daini Seikosha Co., Ltd. Agent: Patent attorney, Mogami

Claims (1)

[Claims] An exterior part for a watch made of metal or an alloy, which is plated with a copper-tin alloy, further plated with a palladium-nickel alloy, and then heat-treated in a vacuum.