JPH0368707A - Perfume noble metal product - Google Patents

Abstract

PURPOSE:To manufacture a perfume noble metal product maintaining perfume over the long time and having dimensional accuracy by compacting noble metal super fine powder specifying particle size distribution without any heating from outer part and impregnating the perfume into a green compact. CONSTITUTION:The noble metal super fine powder (silver or silver series alloy, etc.) consisting of >=70% super fine particle of <=1mu particle diameter to the whole is compacted without any heating from the outer part to make the green compact having 10 - 35% void ratio shown with the void ratio = [1 - (apparent sp. gr./true sp. gr.)] and the perfume is impregnated. Then, this noble metal super fine powder is composed of substantially spherical particles generated at the time of discharging under atmosphere after dissolving activated hydrogen and nitrogen into the molten noble metal with heating plasma or arc discharge at the same time of melting the noble metal with the heating plasma or arc discharge. By this method, the perfume noble metal product is obtd. at extremely low manufacturing cost.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a precious metal article that emits a fragrance for a long period of time and is particularly suitable as an accessory.

[Conventional technology]

Aromatic metals in which porous metals are impregnated with aromatic substances such as fragrances have been known for some time. For example, Japanese Patent No. 17704
．． No. 0 1 Utility Model Registration No. 1773439, Utility Model Registration No. 1773439
-144543 Publication, Utility Model Publication No. 59-36709 (Utility Model Publication No. 63-28896), Utility Model Publication No. 59-16
Publication No. 5421, etc. discloses accessories in which a porous sintered body obtained by sintering metal powder is impregnated with perfume, and Japanese Patent Application Laid-open No. 59-38304 discloses a porous sintered body obtained by sintering metal powder. An invention is disclosed in which the density of the surface layer of the sintered body is increased by light rolling and then impregnated with a fragrance.

In any case, conventional aromatic metals are made by impregnating a porous metal body with fragrance, and the porous metal body is a sintered body of metal powder.

[Problem that the invention seeks to solve]

A porous sintered body of metal is produced by sintering a molded body of metal powder at a sintering temperature below the melting point (temperature sufficient to cause diffusion at the contact surface between particles).
Porous sintered crystals can be produced by appropriately selecting the shape and particle size of the powder particles used, as well as the material properties, and by optimizing the compaction and sintering conditions. However, there is a problem that shrinkage generally occurs during sintering. For this reason, it is often difficult to produce finished products with precise shapes from baked crystals in articles that require precision shapes, such as jewelry.

In addition, when impregnated with liquid fragrance, it is necessary to prevent the fragrance from leaching out and to retain the fragrance for a long time.
The shape of the pores in the porous sintered body must be made very appropriate, but it is also stated in the above-mentioned Japanese Patent Application Laid-Open No. 59-38304 that such a product has not been completed with conventional sintered bodies. It is as written. For this reason, the publication proposes that light rolling be performed to increase the density of only the surface layer of the sintered body. However, even though plate-shaped articles can be manufactured by rolling, it is difficult to manufacture accessories with complex shapes.

Therefore, with the known technology of obtaining a porous metal body by sintering, it is extremely difficult to retain volatile fragrances in the pores for a long time and to obtain a character accessory product with a predetermined size and shape. Was that.

The present invention is aimed at solving these problems, and is intended to develop aromatic precious metal products that maintain their aroma over a long period of time and at the same time have good dimensional accuracy.

[Means to solve problems]

The above-mentioned problems can be solved if a porous metal body having sufficient strength and having extremely fine pores and good dimensional accuracy can be obtained by a technique other than sintering.

The present inventors have learned that ultrafine precious metal powders with an average particle size of 1 μm or less can be compression-molded at room temperature to produce high-strength products with fine pores. Moreover,
In the case of ultrafine powder of precious metals, which are spherical ultrafine powders that are almost perfectly spherical when observed under a microscope, when a pressing action called w1 molding is applied, substantially all of the particles inside the molded product maintain their spherical shape. It became a high-strength molded product, and I learned that very fine voids were formed between the spherical particles. It has also been found that compacted powder products with such voids have good fragrance impregnation properties, and at the same time maintain their aromatic effect for an extremely long period of time.

Therefore, according to the present invention, ultrafine precious metal powder of which 70% or more of the total particle size is 1 μm or less is compression molded into a desired shape without external heating, and a compacted powder product is impregnated with a fragrance. Aromatic precious metal articles of various shapes with a long fragrance time are provided. The porosity of this compacted product is 10-3
It is 5%.

The precious metal ultrafine powder used to obtain the aromatic precious metal product of the present invention is produced by melting the precious metal by bithermal plasma or arc discharge, and at the same time hydrogen or nitrogen activated by the thermal plasma or arc discharge is dissolved in the molten precious metal, and then the atmosphere is The vaporous (smoky) ultrafine powder that is simultaneously generated from the surface of the molten precious metal at the same time as the gas is released should have an average particle size of is 1 μm or less, and each particle is substantially spherical.

〔Example〕

Japanese Patent Publication No. 57-44725, Japanese Patent Publication No. 58-54166, Japanese Patent Publication No. 61-39, which share the same inventor as the present application.
Based on the principle disclosed in Publication No. 372 and Japanese Patent Application Laid-Open No. 61-42318! ! is melted by arc discharge in a hydrogen or nitrogen atmosphere, and at the same time activated hydrogen or nitrogen (diatomic molecular gas) that comes into contact with this arc is dissolved in the molten silver, and this dissolved gas is simultaneously transferred from the molten silver into the atmosphere. The emitted silver vapor (smoke) was collected. When observed under a microscope (514M), this ultra-fine silver powder contains 70 particles of 1 μm or less.
% or more, and has a particle size distribution in which most of the particles are on the submicron order. Additionally, each particle is substantially spherical.

This ultra-fine silver powder has a diameter of 121 mm. It was molded into a disk shape with a thickness of 2II11 at room temperature while changing the pressing force (press pressure) as shown in Table 1. The apparent specific gravity and porosity of the obtained compacted products were measured, and the tensile strength of each compacted product was also measured. The results are shown in Table 1.

Porosity = [1-(apparent ratio 3!r/true specific gravity)]×10
The same amount of the same fragrance was impregnated into each product kl~8, and after being left for 7 days and 144 days, five people evaluated the fragrance strength. All had strong aromas, and no significant difference could be perceived between the products. In the evaluation on the 144th day, the products of patients 4 to 7 maintained strong aromas with no significant difference between them.
It was found that the products of Hiro 1, 2, and 3.8 had weaker aromas than those of Nα4 to 7.

From this result, 3. The compacted powder molded product according to the present invention has a weak aroma persistence if the porosity is too small or too large, but compression molding is performed so that the porosity is in the range of 10 to 35%. It can be seen that the fragrance persistence is extremely good in the case of the above.

FIGS. 1 and 2 are microscopic (S[4M) photographs of the surface and fractured surface of the finished product of Sho 6. In both cases, the magnification is 4000 times, and the length of the white line in the photograph is 1 μm. As seen in these figures, more than 70% of each fine silver particle has a particle size of 1 μm or less, and there are almost no coarse particles, and the surface of the product (Figure 1) has a particle size of 1 μm or less. It can be seen that densification occurs due to deformation, forming pores smaller than the diameter of one particle. Furthermore, as seen in the fracture surface (Figure 2), each particle maintains a spherical shape inside the product, which is why pores exist.In other words, as shown in the tensile test mentioned above, Despite being compression molded into a molded article with sufficient strength, each particle maintains its original spherical shape.There are sufficient gaps between each spherical particle. This result was achieved because noble metals have very small oxide layers on their surfaces and have very large specific surface areas due to their small particle sizes.
It is assumed that there are a large number of physical (physical) contact points, and their combined force is what maintains the strength of the molded product as a whole.

[Comparative Example 1] For comparison, test results for sintered products are listed below. The powder molded products of Nos. 4 to 7 in Table 1 were sintered at 600'C for 30 seconds. The apparent specific gravity and porosity of each were measured and were as shown in Table 2.

From the results shown in Table 2, it can be seen that when sintering is performed, the apparent specific gravity increases and the porosity decreases. In other words, the shape of the molded product shrinks and the porosity becomes extremely small. Therefore, even if a molded product has a predetermined size and shape, the size and shape will be distorted by sintering, and the porosity will be reduced, making it impossible to maintain aromatic properties. In fact, when the same fragrance test as in Example 7 was carried out on the sintered product of No. 7, there was almost no fragrance even on the 7th day. Note that the porosity of the sintered N117 molded product is slightly higher than that of other sintered products. The reason for this is thought to be that gas is more likely to be trapped during sintering in high-pressure molded products than in low-pressure molded products, and this trapped gas expands.

[Comparative Example 2] For comparison, an example using a powder having an average particle size of 40 μm (commercially available silver powder of 400 μm) is given.

A compacted product was made with a pressing force of 3000 kg/cm", and its surface and fractured surface were observed using a microscope (SEM). The photographs are shown in Figures 3 and 4. In both cases, the magnification was 500x. The length of the white line in the photo is -10μ.The porosity in this case is approximately 9%, and the voids have an irregular shape, which is different from the inventive product shown in Figures 1 and 2. It can be easily seen that a porous article with such a void morphology would not have good perfume impregnation or aromatic properties.

〔effect〕

As explained above, according to the present invention, a new aromatic precious metal product that retains its aromatic properties for a long time is provided. The product of the present invention remains as a compression molded product and does not lose its shape unlike baked crystals. Therefore, an article with the same size and shape as the compression molding mold can be obtained, and even if the mold is complex, the transferability of the mold is extremely good because it is an ultra-fine powder. If you prepare a mold like this, you can easily make even small pieces. In addition, it has been found that coating and plating adhere well to the surface, and even with such ultra-thin surface treatment, surface pores are not filled, and fragrance impregnation and aromatic properties are maintained. Ta. Furthermore, since the present invention does not require a sintering operation, the manufacturing cost is extremely low. Although silver was used as an example in the above embodiment, any noble metal whose oxide film is hard to form may be used, and alloys containing noble metal as a main component can also be used.

[Brief explanation of drawings]

Figure 1 is a metallurgical microscope photograph (magnification x 4000) showing the surface of the aromatic precious metal product of the present invention, and Figure 2 is a metallurgical microscope photo (magnification x 400) showing the fracture surface of the same precious metal product as in Figure 1.
0), FIG. 3 is a metallurgical microscope photograph (magnification: X 500) showing the surface of a comparative example product, and FIG. 4 is a metallurgical microscope photograph (magnification: X 500) showing the fractured surface of the same comparative product as in FIG. 3.

Claims (4)

[Claims] (1) An aromatic precious metal product obtained by impregnating a compacted powder product obtained by compression molding ultrafine precious metal powder, in which ultrafine particles with a particle size of 1 μm or less account for 70% or more of the total, without external heating, and impregnating it with a fragrance. (2) The compacted powder molded product has a porosity of 10 to 3 as shown by the following formula.
The aromatic precious metal article according to claim 1, wherein the porosity is 5%.
1-(apparent specific gravity/true specific gravity)]×100. (3) Noble metal ultrafine powder is a precious metal generated when a precious metal is melted by thermal plasma or arc discharge, and at the same time hydrogen or nitrogen activated by the thermal plasma or arc discharge is dissolved in the molten precious metal and released into the atmosphere. The aromatic precious metal product according to claim 1 or 2, comprising substantially spherical particles obtained by collecting ultrafine powder. (4) The aromatic noble metal product according to claim 1, 2 or 3, wherein the noble metal is silver or a silver-based alloy.