JPS5864396A - White colored external parts for timepieces - Google Patents

Abstract

PURPOSE:To provide white colored external parts for timepieces at reduced costs and with good corrosion resistance by applying underlying plating of Cu-Sn, finish plating of Pd-Ni and if necessary flash plating of Rh on said parts. CONSTITUTION:Underlying plating of >=2mu is applied on blank materials for watch cases, etc. by using a Cu-Sn alloy contg. 40-45% Sn. Thereafter, finish plating of a Pb-Ni alloy is applied thereon to 0.2-2mu thickness and further if necessary flash plating of Rh is applied, whereby white colored external parts for timepieces are obtained. The external parts for timepieces obtained by said method do not corrode and discolor against seat. Since the Cu-Sn plating is applied under the finish plating, the finish plating of noble metals is made thin in thickness and the cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exterior part for a timepiece, and particularly to an exterior part for a white timepiece that is inexpensive and has excellent corrosion resistance.

Time measurement exterior parts (case 1, band, dial ring,
When applying K white plating (such as tensile rings, etc.), the main materials used are brass, nickel silver, etc., and the types of plating include tarom plating, palladium-nickel alloy plating, badge laminate, etc. Rhodium flash plating is used for nickel alloy plating.

Conventionally, such white plating has been applied to IK watch case material made of brass, as shown in Figure 1, using the example of a case.
As a base plating, nickel plating 2 is applied to a thickness of about 2 to 8 microns, and on top of that, paddillam-nickel alloy plating 3 is applied to about 2 to 5 microns, and then rhodium flash plating 4 is applied to form the watch case. I was standing there. In the case of such a watch case, since the alloy tube containing palladium, which is a precious metal, is thickly plated, expensive plating and high cost have become a problem. In addition, if the case is finished with only a mirror surface, there will be no particular problem with corrosion resistance, but if a part or most of the case is finished with a streaky finish, it will not work as a conventional base plating. If the nickel plating is applied thickly, the appearance of streaks will be lost, so it must be thick! It had the disadvantage of being inferior in corrosion resistance compared to mirror-finished cases. Furthermore, even if a type of nickel plating is used that does not impair the aesthetic appearance of the streaks even if the plating is thick, the coverage of the plating to the valleys of the streaks will be poor, resulting in poor corrosion resistance as well. There was a drawback.

The present invention was developed as a result of various studies to eliminate the above-mentioned drawbacks, to reduce plating costs, and to provide a watch exterior part with good corrosion resistance for all surface finished watch exterior parts. 40 ~ tin as the base plating.
Copper-tin alloy plating containing 45% is applied to a thickness of 2 microns or more, and palladium-nickel alloy plating is applied as a final plating*
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It is characterized by 2 to 2 micron plating, and if necessary, rhodium flash plating.

The copper-tin alloy plating containing 40 to 45% tin't here refers to various steel-tin platings such as copper cyanide-alkali stannate, copper cyanide-tin birophosphate, or copper birophosphate-tin birophosphate. The present inventors investigated various types of this plating, and found that even relatively thin plating is not easily corroded, with only a slight yellowing caused by sweat etc., which led to the present invention. It is something.

The copper-tin alloy plating used as the base plating is most preferably copper cyanide-alkali stannate plating, and is from a plating bath using a thiocyanate, a polyethyleneimine compound, or a nickel salt as a brightener. Thick plating can be done without damaging the aesthetic appearance of the surface finish such as streaks.

The present invention will be explained below using a watch case as an example.

As shown in Fig. 2, a steel-tin alloy plate 15 containing 40 to 45% tin was coated on a watch case 1 made of brass material with a partially streaked finish using the following plating bath and plating conditions. 2 micron plating was carried out, and palladium-nickel (palladium nickel plating 3 containing 60% palladium) was further applied to 1 micron as a final plating.

(Plating bath) Sodium stannate 100jl/sodium cyanide 3011/sodium cyanide
i 29/ sodium hydroxide
1011/l Sodium thiocyanate 401
1/l polyethyleneimine o, it
I/L (Plating conditions) Bath temperature 65℃ vlm Density 2 A/dtn” Anode Carbon plate plating time 9 minutes or more Conventional nickel plating on watch cases and similar watch case materials When a watch case plated with 4 micron microns and palladium-nickel plating was subjected to a corrosion resistance test using an artificial sweat immersion test, the case of the present invention showed no corrosion or discoloration after 5 days of immersion, but the case of the conventional one did not. Some dot-like corrosion occurred in the lined areas.

As described above, according to the present invention, by performing copper-tin alloy plating containing 40 to 45% tin as the base plating, it is possible to reduce the cost by making the final noble metal plating thinner. Exterior parts for watches with good corrosion resistance can be produced with any surface finish.

In the embodiments, a watch case has been described, but it goes without saying that the present invention can be applied to other parts as well, and it goes without saying that not only brass but also other materials can be used.

It goes without saying that the thicknesses of the final plating and the base plating can be used in any combination other than those described in the examples.

[Brief explanation of the drawing]

1 is a partial cross-sectional view of a conventional watch case, and FIG. 2 is a partial cross-sectional view of a watch case according to the present invention. Nickel plating 41. Rhodium plating 50. Copper-tin alloy plating containing 40-45% tin Applicant Daini Seikosha Co., Ltd. Agent Mogami Patent Attorney Figure 1 Figure 2

Claims (1)

[Claims] Tin as a base plating! A white watch made by applying a 40 to 45-containing octopus-tin alloy plating of 1112 microns or more, a palladium-nickel alloy plating of 1 it 0.2 to 2 micron as a final plating, and if necessary, rhodium flash plating. Exterior parts.