Stock material or miscellaneous articles – All metal or with adjacent metals – Composite; i.e. – plural – adjacent – spatially distinct metal...
Reexamination Certificate
2001-02-02
2002-07-02
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
All metal or with adjacent metals
Composite; i.e., plural, adjacent, spatially distinct metal...
C428S655000, C428S658000, C428S674000, C428S675000, C428S680000
Reexamination Certificate
active
06413653
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a personal ornament wherein a basis material composed of a copper alloy or zinc is covered with, as an outermost layer, a colored coating of, for example, titanium nitride formed by dry-plating such as the ion plating process, and further relates to a process for producing the personal ornament.
BACKGROUND OF THE INVENTION
Personal ornaments wherein a basis material composed of a copper alloy or zinc is covered with, as an outermost layer, a colored coating of, for example, titanium nitride formed by the ion plating process are known. For example, Japanese Patent Publication No. 6(1994)-2935 whose applicant is identical with that of the present application discloses a personal ornament with a colored surface, comprising a personal ornament basis material composed of a copper alloy, a 1 to 10 &mgr;m thick nickel layer formed as an undercoat layer on a surface thereof by electroplating, a 0.5 to 5 &mgr;m thick palladium or palladium alloy (for example, palladium
ickel) layer formed on the nickel layer by electroplating and a colored coating layer of, for example, titanium nitride formed on the palladium or palladium alloy layer by the ion plating process. This personal ornament, because it is not needed to thicken the nickel layer, is free from pattern unsharpness and sagging attributed to thick plating, exhibits an appearance of superior quality and is excellent in corrosion resistance.
However, this personal ornament, although involving no practical problem, poses a cost problem due to the inclusion of the palladium or palladium
ickel layer. The price of palladium (Pd) as a constituent of the layer is recently very high, thereby extremely increasing the production cost of the personal ornament. For example, the price of palladium was about 500 yen/g in 1997, but currently (1998) it is as high as 1400 yen/g. Moreover, ammonia gas emitted at the electroplating conducted for the formation of the palladium
ickel layer is likely to be detrimental to other cyanide using platings (14 or 18 karat Au/Ag plating). Further, the palladium
ickel layer tends to occlude hydrogen, so that cracking of the palladium
ickel layer is likely to occur resulting unfavorable lowering of the adhesion to the colored coating layer and lowering of the durability (corrosion resistance) of the palladium
ickel layer.
Further, Japanese Patent Laid-open Publication No. 4(1992)-304386 whose applicant is identical with that of the present application discloses a basis material composed of a material of low melting point such as brass, german silver (nickel silver or argentan) or zinc die cast, a nickel layer formed as an undercoat layer on a surface of the basis material by wet-plating, a nickel/phosphorus alloy layer formed directly on the nickel layer by electroplating and a dry plating layer (colored coating layer) formed on the nickel/phosphorus alloy layer by dry-plating. With respect to this metal member, the amount of ammonia gas emitted at the electroplating conducted for the formation of the nickel/phosphorus alloy layer is so small that the ammonia gas is substantially free from adversely affecting other platings (ion plating process (dry-plating)). Also, the nickel/phosphorus alloy layer substantially does not occlude hydrogen and is free from cracking, so that there is no danger of lowering of the adhesion to the dry plating layer (colored coating layer) and lowering of the durability of the nickel/phosphorus alloy layer. In particular, the metal member described in Example 1 of Japanese Patent Laid-open Publication No. 4(1992)-304386, because of the formation of a nickel/phosphorus alloy layer having a phosphorus content of about 10%, is excellent in durability and poses no practical problem at all. Although not described in the above Japanese Patent Laid-open Publication No. 4(1992)-304386, the nickel/phosphorus alloy layer of Example 1 thereof is formed by electroplating at a current density (Dk) of 5 A/dm
2
at 55° C. in a pH 4.0 acid plating solution which contains nickel sulfate in an amount, in terms of nickel atom, of 50 g/lit., nickel chloride in an amount, in terms of nickel atom, of 15 g/lit. and sodium hypophosphite in an amount, in terms of phosphorus atom, of 35 g/lit. Electroplating in this plating solution under the above plating conditions for a prolonged current passage time, however, does not lead to formation of an amorphous nickel/phosphorus alloy layer having a phosphorus content of 11% by weight or more.
The inventors have conducted extensive and intensive studies with a view toward obtaining a personal ornament of high grade having a corrosion resistance greater than those of personal ornaments and metal members disclosed in the above publications without the use of expensive palladium. As a result, it has been found that the following personal ornament produced as described below (1) or (2) includes an amorphous nickel/phosphorus alloy plating layer whose phosphorus content is in the range of 11 to 16% by weight and has a corrosion resistance greater than those of personal ornaments and metal members disclosed in the above publications. The present invention has been completed on the basis of this finding.
Personal ornament (1): This is produced by the following process. First, a nickel plating layer of 1 to 5 &mgr;m thickness is formed by electroplating on a surface of a basis material for personal ornament composed of a copper alloy or zinc. Alternatively, a copper plating layer of 10 to 15 &mgr;m thickness is formed on the basis material by electroplating, and a surface of the copper plating layer is covered by electroplating with a nickel plating layer of 1 to 10 &mgr;m thickness. Subsequently, an amorphous nickel/phosphorus alloy coating layer of 3 to 10 &mgr;m thickness (phosphorus content: 11 to 16% by weight) is formed on a surface of the nickel plating layer by electroplating at a current density (Dk) of 1 to 3 A/dm
2
, at 50 to 60° C., in an acid plating solution of pH 3.0 to 3.5 which contains nickel sulfate in an amount, in terms of nickel atom, of 15 to 70 g/lit., sodium hypophosphite in an amount, in terms of phosphorus atom, of 10 to 50 g/lit., an electric conductive salt (ammonium chloride) in an amount of 50 to 90 g/lit., a pH buffer in an amount of 20 to 50 g/lit. and a completing agent in an amount of 5 to 30 g/lit. Finally, a 0.1 to 2 &mgr;m thick colored coating layer is formed by dry-plating on a surface of the amorphous nickel/phosphorus alloy plating layer.
Personal ornament (2): This is produced by the following process. First, a nickel plating layer of 1 to 10 &mgr;m thickness is formed by electroplating on a surface of a basis material for personal ornament composed of a copper alloy or zinc. Alternatively, a copper plating layer of 10 to 15 &mgr;m thickness is formed on the basis material by electroplating, and thereafter a surface of the copper plating layer is covered by electroplating with a nickel plating layer of 1 to 10 &mgr;m thickness. Subsequently, an amorphous nickel/phosphorus alloy coating layer layer of 3 to 10 &mgr;m thickness (phosphorus content: 11 to 16% by weight) is formed on a surface of the nickel plating (coating) by electroless plating in a plating solution which contains a nickel salt such as nickel sulfate in an amount, in terms of nickel atom, of 1 to 15 g/lit., sodium hypophosphite (reducing agent) in an amount, in terms of phosphorus atom, of 5 to 30 g/lit., a complexing agent, a buffer and a pH regulator, at 85 to 95° C. and pH of 3.0 to 4.5. Alternatively, the amorphous nickel/phosphorus alloy coating layer of 3 to 10 &mgr;m thickness (phosphorus content: 11 to 16% by weight) is formed by first electroplating by passing current at a density (Dk) of 0.5 to 1.0 A/dm
2
for a period of 5 to 30 sec through the above plating solution whose pH is in the range of 3.0 to 4.5 and whose temperature is in the range of 50 to 95° C. and thereafter electroless plating in the plating solution whose pH is in the range of 3.0 to 4.5 and whose temperature is in the range of 85 to 9
Araki Takeshi
Inoue Takeshi
Citizen Watch Co. Ltd.
Piziali Andrew T
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
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