JP2002327224A - Silver based alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silver based alloy which does not discolor even after contacting with perspiration, sulfide, and the like, over a long time, can maintain original hue and luster of silver over a long term, and has superior workability and casting properties. SOLUTION: This alloy includes Sn of 2-20 wt.% and the balance Ag. The alloy is preferably used for an ornament or tableware, for example.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silver alloy used for decorative articles such as rings, brooches, necklaces and the like, and tableware such as spoons and dishes.

[0002]

2. Description of the Related Art Conventionally, silver alone or silver-based alloys have been widely used for ornaments and tableware, but conventional silver-based alloys turn black when they come into contact with sweat or the like during use. There was a problem of doing it. In addition, there is a problem that silver sulfide is formed by reacting with a small amount of sulfide in the air and discolored to black.

Various silver alloys are known as silver alloys for preventing the discoloration described above.
No. 243725 discloses that 90 to 95% by weight of silver and 0.2 to 9% by weight of platinum are used as main components, and palladium, gold, zinc, indium, tin, iridium, magnesium, gallium, ruthenium, copper, etc. A sulfur-resistant silver alloy comprising at least one or two or more impurities and unavoidable impurities is disclosed.

Japanese Patent Application Laid-Open No. 2000-119773 discloses that, by adding an Al component to an Ag component in a certain amount or more, even if used for a long time, the color does not change due to sweat or the like and the glittering property is impaired. No tin 2 as silver alloy for jewelry
-7% by weight, indium 1-5% by weight, copper 0.1-1% by weight, zinc 0.1-1% by weight, aluminum 0.1-
A silver alloy for accessories is disclosed in which the total is 100% by weight, with 0.2% by weight and the balance being silver.

On the other hand, from the viewpoint of improving the processability of silver,
Silver alloys for decorative articles having various other component compositions are known. For example, SV925 (Ag 92.5%, Cu balance) and SV950 (Ag 95.0%, Cu balance) are widely and commonly used. It is known and used. Since silver alone is soft and sticky and has poor workability, copper is added to these silver alloys to improve workability and castability.

[0006]

However, among the above-mentioned prior arts, the silver-based alloys disclosed in JP-A-62-243725 and JP-A-2000-119773 also have an insufficient effect of preventing discoloration of silver. In particular, when used for decorative items such as rings and necklaces that have been in contact with sweat or the like for a long time, or for dishes that have a long-term contact with food ingredients, discoloration due to long-term use cannot be avoided, It is not possible to completely prevent a decrease in merchantability. Further, any of the above-mentioned silver-based alloys requires an alloy composed of at least three kinds of metals, so that the composition is complicated, and there is also a problem that the manufacturing process is complicated and the cost is disadvantageous.

On the other hand, a conventional silver alloy to which only copper is added has good workability and castability, and has a simple composition and excellent productivity, but blackening due to reaction with sweat or sulfide is not observed. As described above, there is a problem that the commercial value of the decorative articles and tableware which cannot be effectively prevented and whose color tone and gloss are maximized is immediately reduced.

[0008] Therefore, an object of the present invention is to provide a long-term contact with sweat, sulfide, or the like without discoloring its color.
An object of the present invention is to provide a silver-based alloy which can maintain the color tone and luster inherent to silver for a long period of time, and is excellent in workability and castability.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and found that a two-component alloy obtained by adding a predetermined amount of Sn to Ag impairs workability and castability. Instead, the inventors have found that discoloration can be prevented over a long period of time, and have completed the present invention.

That is, the silver-based alloy of the present invention comprises Sn: 2
-20% by weight, with the balance being Ag.

According to this silver-based alloy, a predetermined amount of S is added to Ag.
Only by adding n, excellent discoloration resistance is imparted, so that discoloration of Ag can be effectively suppressed even in a use condition such as a ring or a necklace that comes into contact with sweat for a long time. Further, as the content of Sn is specified as 2 to 20% by weight as a range that does not impair the workability of Ag, the workability and castability are not impaired, and the productivity does not decrease.

In a preferred aspect of the present invention, the silver alloy is used for decorative articles or tableware.
Since the silver-based alloy of the present invention has an excellent effect of preventing discoloration due to sweat, it can be particularly suitably used for decorative articles worn directly on the skin such as rings and necklaces, and discoloration due to food components is also a problem. It can be particularly suitably used for silverware.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The silver-based alloy of the present invention has a composition of A
g: 80 to 98% by weight (hereinafter, "% by weight" is simply "%"
), An alloy containing only two components of Sn: 2 to 20%, and substantially no other components. When an alloy other than Ag and Sn is included, the long-term discoloration prevention effect is reduced. Here, “substantially not contained” means that even a very small amount of impurities inevitably mixed into Ag or Sn can be actually contained.

In the present invention, the Ag content is 80 to
It is necessary to be in the range of 98%, more preferably in the range of 90 to 98%.

When the content of Ag is less than 80%, the effect of preventing discoloration is good, but the content of Sn becomes relatively large and the alloy becomes hard, and the workability and castability deteriorate. On the other hand, if the Ag content exceeds 98%, the Sn content becomes relatively less than 2%, so that the effect of preventing discoloration is not obtained. Also decrease.

As described above, the silver-based alloy of the present invention has
By making n: 2 to 20% and the balance being Ag, it is excellent in workability and castability, and prevents discoloration for a long time, and is most suitable for decorative articles and tableware. A silver-based alloy having such a composition exhibits a white color tone and gloss peculiar to silver.

Here, the use of the silver-based alloy of the present invention is not particularly limited, but decorative articles or tableware are preferably applied. Here, examples of the ornament include, but are not particularly limited to, accessories such as rings, necklaces, earrings, earrings, bracelets, brooches, tie pins, cufflinks, and belt buckles. Examples of the tableware include tableware such as spoons and dishes.

For the casting of the silver-based alloy, for example, a crushed mold such as a gypsum-based or phosphoric acid-based mold made by a lost wax method is used to mold a molten metal of a metal melted in a crucible into a mold. General method, such as pouring and casting. The silver-based alloy thus cast and formed into a predetermined shape according to the purpose of use is polished and then commercialized as various decorative articles as described above.

[0019]

Examples 1 and 2 Ag and Sn were blended at the ratios shown in Table 1 and then cast and polished according to a conventional method to produce the rings of Examples 1 and 2.

Comparative Examples 1 and 2 The ratio of Ag and Sn was changed and the ratio of Ag and Sn was changed as shown in Table 1.
Rings of Comparative Examples 1 and 2 were produced under the same conditions as in the example except that Sn and Sn were blended.

Comparative Example 3 A ring of Comparative Example 3 was prepared under the same conditions as in the example except that Ag and Pt (platinum) were mixed at the ratios shown in Table 1.

Comparative Example 4 A ring of Comparative Example 4 was prepared under the same conditions as in the example except that Ag and Cu (copper) were blended at the ratios shown in Table 1.

Comparative Example 5 Ag, Au (gold), Cu
A ring of Comparative Example 5 was made under the same conditions as in the example except that (copper) and Pd (palladium) were blended.

Test Examples The rings of Examples 1 and 2 and Comparative Examples 1 to 5 were cast
Workability during polishing and a discoloration test with artificial sweat were performed.
The results are summarized in Table 1.

The discoloration test using artificial sweat is an aqueous solution containing synthesized salt, urea, lactic acid, ammonia, etc., which is used for testing in the clock and precious metal industries. This was performed by partially immersing the ring and visually checking the degree of discoloration.

[0026]

[Table 1]

From the results shown in Table 1, in Examples 1 and 2, there was no problem in the workability during casting and polishing, and no discoloration was observed even in a discoloration test at room temperature for 4 days. You can see that it is doing.

On the other hand, in Comparative Example 1, although the effect of preventing discoloration was good, the content of Sn was too large and the alloy became hard, and the workability during casting and polishing was reduced.

In Comparative Example 2, the effect of preventing discoloration was insufficient because the content of Sn was too small, and it can be seen that blackening was caused by artificial sweat. Furthermore, since the Sn content was small, it was sticky and soft, and the workability of the ring was poor.

Further, the alloys of Comparative Examples 3 to 5 all had good workability, but also had insufficient effect of preventing discoloration, and blackening could not be completely prevented by artificial sweat.

[0031]

As described above, according to the present invention,
Excellent workability and castability, easy handling and excellent productivity,
Moreover, even if it comes into contact with sweat or sulfide for a long period of time, the original color tone and luster of silver can be maintained for a long time without discoloring the color tone, especially for ornaments such as rings, brooches, necklaces and tableware. A suitable silver-based alloy can be provided.

Claims (2)

[Claims] 1. A silver alloy comprising: Sn: 2 to 20% by weight, with the balance being Ag. 2. The silver alloy according to claim 1, which is used for decorative articles or tableware.