JPS5861268A - Case for watch - Google Patents

Abstract

PURPOSE:To provide case for a watch which are inexpensive and have high corrosion resistance and hardness and beautiful color tone by applying tin and tin alloy layer on metal having sufaces of copper and copper alloys and diffusing the surfaces of tin and tin alloys. CONSTITUTION:Tin or tin alloy layers of thin films are adhered or joined tightly to the surfaces of external parts for a watch such as watch cases, dials, crowns, bands and others, which are produced of copper or copper alloys or are formed with copper or copper alloy layers on the surfaces, by electroplating, electroless plating, vacuum deposition, sputtering, ion plating, melt spraying, etc. The tin or tin alloys are subjected to a treatment under heating wherein they are held for about >=25min at about 180-500 deg.C, whereby the surfaces are diffused and the desired external parts for the watch are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The invention is obtained by applying tin and tin alloy layers on metals with copper and copper alloy surfaces and carrying out surface diffusion of the tin and tin alloys.

This invention relates to an exterior part for a watch that is highly corrosion resistant, hard, and has an elegant color.

Conventionally, copper and copper alloys have poor corrosion resistance and discoloration resistance.To prevent this, expensive gold plating, rhodium plating, palladium plating, etc. are applied to obtain a certain degree of corrosion resistance and discoloration resistance. It is used as a part. Furthermore, tin and tin alloys are currently hardly used as exterior parts for watches because they are soft (about 100 on the Vickers hardness) and have an original color tone.

An object of the present invention is to eliminate the above-mentioned drawbacks and to obtain, at a low cost, an exterior part for a watch that is highly corrosion resistant, hard, has an elegant color, and has a luxurious appearance, using a copper and tin alloy.

Examples of the present invention will be described below.

Articles having sea bream or copper-containing surfaces are articles manufactured from copper or copper alloys, and articles with copper or copper alloy layers formed on the surface, and in the present invention, watch cases, dial plates, etc. , Liez, Nodondo, and other watch exterior parts.

A thin tin or tin alloy layer is adhered and bonded to the surface of the component by electroplating, electroless plating, vacuum evaporation, sputtering, ion plating, thermal spraying, etc., and then diffused by heat treatment.

Appropriate diffusion heat treatment conditions are selected depending on the type and thickness of the tin or tin alloy layer. Temperature 180υ~500℃
, a holding time of 25 minutes or more is appropriate.

Increasing the temperature or increasing the holding time increases the thickness of the tin or tin alloy diffusion layer, reduces the surface tin concentration, and increases the surface hardness. Therefore, by determining the temperature and holding time based on the nine hardness tones and the luxury appearance, it is possible to obtain a watch exterior part that is suitable for each.

Specific examples of the present invention will be described below.

Example t 5 A watch case made of brass (60% copper, 40 square meters of zinc) was electroplated with 3 microns of copper plating (99% copper), and 2 microns of tin plated (99 square meters of tin) using electroplating. Apply microparticles at a temperature of 200 in a vacuum of 10-' Torr.
Thermal diffusion was carried out at °C for a holding time of 60 minutes.

As a result, a watch case with a silvery white color was obtained due to the diffusion of tin plating.

This case showed no change in a 48-hour ammonia air test and a 10-day artificial sweat immersion test, and no corrosion was observed even after 2 years of actual use. It is about 2/3 cheaper than gold plating and about 1/3 cheaper than gold plating, and comparable to Niacel plating and gold plating.
A watch case with high corrosion resistance and a luxurious feel was obtained.

Example 2 A wristwatch case made of zinc tie-casting was plated with copper to a thickness of 2 microns by electroless plating, and tin plated to a thickness of 15 microns by electroplating, and heated in a vacuum of 1O-3 Torr with 250 liters of wet coal and a holding time of 45 Thermal diffusion was carried out for 10 minutes.

As a result, a wristwatch case with a silver-blue color and a distinctly luxurious appearance was obtained due to the diffusion of tin plating.

In this case, when the hardness was measured, the Vickers hardness of tin was usually about 100, and the Vickers hardness of copper was about 200, but in this case, the Vickers hardness was about 450. Therefore, it shows an improvement of about 4 times that of tin and about 2 times that of rust.

As described above, according to the present invention, by forming a tin diffusion layer on the surface of copper, it is possible to obtain an exterior part for a watch that has high corrosion resistance, high hardness, and a high-class appearance at a low cost.

that's all Applicant: Daini Seini Co., Ltd. Agent Patent Attorney Mogami:

Claims (1)

[Claims] A watch case obtained by applying a layer of tin and a tin alloy on a metal having a surface of copper and a copper alloy, and performing surface diffusion of tin and a tin alloy.