Golden decorative part

Details Golden decorative part Golden decorative part

1997-06-06

2001-10-09

Nguyen, N. M. (Department: 1754)

Stock material or miscellaneous articles

All metal or with adjacent metals

Composite; i.e., plural, adjacent, spatially distinct metal...

C428S628000, C428S672000, C428S660000, C428S681000, C428S469000, C428S698000, C428S699000, C420S512000

Reexamination Certificate

active

06299987

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a golden decorative part having no danger of causing dermatitis attributed to allergy to metals, such as contact dermatitis, and to a process for producing the same.
BACKGROUND OF THE INVENTION
Conventionally, the decorative parts, such as a wristwatch band and other wristwatch parts, a finger ring, a necklace and an earring, have been provided with a high quality appearance and an excellent corrosion resistance by composing its outermost layer of a gold coating formed according to a wet or dry plating process. The respective outermost layers of such decorative parts are now increasingly composed of a coating of a gold alloy, such as gold-nickel and gold-palladium alloys, rather than of that of pure gold, because the pure gold coating is so soft as to have less wear resistance, and because the color of the pure gold is not favored due to its extremely deep golden tone and rather there is an inclination that light golden color is preferred.
However, in recent years, a marked increase is observed in the occurrence of allergic dermatitis in which contact dermatitis is caused by the contact of the skin with a decorative part, such as a necklace or an earring, made of a precious metal. Such allergic dermatitis cases are reported with respect to almost all types of metals. Especially, the occurrence of allergic dermatitis attributed to gold-nickel and gold-palladium alloys is described in many reports.
Titanium is a metal for which no allergic dermatitis case has been reported. However, the employment of titanium in an ion plating process to form an outermost coating of the above decorative part has been accompanied by drawbacks such that the tone of the resultant gold-titanium alloy coating is not uniform, and that the coating becomes blackish. Iron is another metal for which allergic dermatitis cases have been extremely rarely reported. However, the employment of iron in an ion plating process to form an outermost coating of the above decorative part has also been accompanied by drawbacks such that the tone of the resultant gold-iron alloy coating is not uniform, and that the coating becomes blackish. Extensive study has been made to find what causes such drawbacks. As a result, it has been found that titanium and iron are so active that large amounts of oxygen, carbon and nitrogen present in an ion plating apparatus are captured into the coating, and that the above drawbacks are caused by such capturing.
As indicated above, there has been a strong demand in the art for the development of a golden decorative part not only having no danger of causing allergic dermatitis, such as contact dermatitis, even if used in contact with the skin but also exhibiting a uniform golden tone.
The present invention has been made with a view toward obviating the above drawbacks of the prior art. Thus it an object of the present invention to provide a golden decorative part not only having no danger of causing allergic dermatitis, such as contact dermatitis, even if used in contact with the skin but also exhibiting a uniform golden tone. It is another object of the present invention to provide a process for producing the above golden decorative part.
SUMMARY OF THE INVENTION
A first golden decorative part according to the present invention comprises a substrate and, formed thereon according to a dry plating process, an outermost coating,
wherein the outermost coating comprises 60 to 99 atomic % of gold, 0.5 to 20 atomic % of titanium or iron and 0.5 to 20 atomic % of inevitable ingredients.
Further, a second golden decorative part according to the present invention comprises a substrate, a Ti coating containing inevitable ingredients formed on a surface of the substrate in an inert gas other than nitrogen and an outermost coating formed on the Ti coating according to a dry plating process.
wherein the outermost coating comprises 60 to 99 atomic % of gold, 0.5 to 20 atomic % of titanium or iron and 0.5 to 20 atomic % of inevitable ingredients.
Still further, a third golden decorative part according to the present invention comprises a substrate, a TiN coating formed on a surface of the substrate and an outermost coating formed on the TiN coating according to a dry plating process.
wherein the outermost coating comprises 60 to 99 atomic % of gold, 0.5 to 20 atomic % of titanium or iron and 0.5 to 20 atomic % of inevitable ingredients.
Still further, a fourth golden decorative part according to the present invention comprises a substrate, a Ti coating containing inevitable ingredients formed on a surface of the substrate in an inert gas other than nitrogen, a TiN coating formed on the Ti coating and an outermost coating formed on the TiN coating according to a dry plating process.
wherein the outermost coating comprises 60 to 99 atomic % of gold, 0.5 to 20 atomic % of titanium or iron and 0.5 to 20 atomic % of inevitable ingredients.
A first process for producing a golden decorative part according to the present invention comprises forming an outermost coating comprising 60 to 99 atomic % of gold, 0.5 to 20 atomic % of titanium or iron and 0.5 to 20 atomic % of inevitable ingredients on a substrate in an atmosphere of an inert gas other than nitrogen in a dry plating apparatus.
Further, a second process for producing a golden decorative part according to the present invention comprises evaporating titanium in an atmosphere of an inert gas other than nitrogen in a dry plating apparatus to thereby form a Ti coating containing inevitable ingredients present in the dry plating apparatus on a substrate,
and subsequently forming an outermost coating comprising 60 to 99 atomic % of gold, 0.5 to 20 atomic % of titanium or iron and 0.5 to 20 atomic % of inevitable ingredients on the Ti coating in an atmosphere of an inert gas other than nitrogen in the dry plating apparatus.
Still further, a third process for producing a golden decorative part according to the present invention comprises evaporating titanium in an atmosphere of nitrogen gas in a dry plating apparatus to thereby form a TiN coating on a substrate,
and subsequently forming an other most coating comprising 60 to 99 atomic % or gold, 0.5 to 20 atomic % of titanium or iron and 0.5 to 20 atomic % of inevitable ingredients on the TiN coating in an atmosphere of an inert gas other than nitrogen in the dry plating apparatus.
Still further, a fourth process for producing a golden decorative part according to the present invention comprises evaporating titanium in an atmosphere of an inert gas other than nitrogen in a dry plating apparatus to thereby form a Ti coating containing inevitable ingredients present in the dry plating apparatus on a substrate.
subsequently evaporating titanium in an atmosphere of nitrogen gas in the dry plating apparatus to thereby form a TiN coating on the Ti coating, and
thereafter forming an outermost coating comprising 60 to 99 atomic % of gold, 0.5 to 20 atomic % of titanium or iron and 0.5 to 20 atomic % of inevitable ingredients on the TiN coating in an atmosphere of an inert gas other than nitrogen in the dry plating apparatus.
In the present invention, it is preferred that the above TiN coating be disposed just under the outermost coating of the golden decorative part, and that the Ti coating be disposed on the substrate.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinbelow, the golden decorative part and the process for producing the same according to the present invention will be illustrated.
First, the golden decorative part of the present invention will be described in detail.
Essentially, the golden decorative part of the present invention comprises a substrate and an outermost coating formed on the substrate by a dry plating process, such as the vacuum evaporation, sputtering or ion plating process, which outermost coating comprises (i) gold and (ii) titanium or iron and (iii) inevitable ingredients in specific proportions.
In the golden decorative part of the present invention, there may be a TiN coating between the substrate and the outermost coating. Parti

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