WO2014157527A1

WO2014157527A1 - Clay-like composition for noble metal sintered compact

Info

Publication number: WO2014157527A1
Application number: PCT/JP2014/058880
Authority: WO
Inventors: 佳史山本; 井戸　康夫; 司池田; 真二大谷
Original assignee: 三菱マテリアル株式会社
Priority date: 2013-03-28
Filing date: 2014-03-27
Publication date: 2014-10-02
Also published as: EP2979782A4; JP6090664B2; EP2979782A1; EP2979782B1; US20160001363A1; JP2014189896A

Abstract

This clay-like composition is for forming a noble metal sintered compact comprising at least a noble metal powder and/or noble metal alloy powder, an organic binder, an organic additive, and water. The organic additive is 0.1 to 3.0 mass % propylene glycol. The clay-like composition has excellent bending workability, even after having been dried during molding, and as a result, there are few time restraints when the composition is being worked by bending, and the like.

Description

Clay-like composition for sintered noble metal

The present invention relates to a clay-like composition for forming a precious metal sintered body.
This application claims priority on March 28, 2013 based on Japanese Patent Application No. 2013-0669638 filed in Japan, the contents of which are incorporated herein by reference.

Conventionally, for example, precious metal jewelry and arts and crafts such as rings are generally manufactured by casting or forging a precious metal-containing material such as silver or gold.

However, in recent years, precious metal clay containing a precious metal powder such as silver or gold (clay-like composition for forming a sintered body) is commercially available, and by firing the precious metal clay into an arbitrary shape, Methods have been proposed for producing precious metal jewelry and arts and crafts having an arbitrary shape (see, for example, Patent Documents 1 to 3).

According to such a method, modeling can be performed freely using precious metal clay in the same manner as normal clay work. In addition, after drying the molded body obtained by shaping the precious metal clay, it is possible to manufacture precious metal jewelry and arts and crafts very easily by firing using a heating furnace. .

Japanese Patent No. 4265127 JP-A-4-26707 JP 2005-187858 A

When manufacturing the said conventional noble metal sintered compact, modeling is performed using the silver clay using the silver powder of pure Ag, for example. Such modeling is mainly performed manually, but when time elapses, the clay dries and it may be difficult to perform a process such as bending. In particular, the shape of the precious metal sintered body is complicated due to diversification in design and preference, and the time required for the shaping tends to be long. Specifically, when a dried product of silver clay is bent, the conventional product is cracked on the surface, and further bent when bent. Therefore, when making a ring or the like, it is necessary to perform modeling in a limited time, and the design is limited.
In view of such circumstances, the present invention has been completed as a result of intensive research for the following purposes.

The present invention is a precious metal ware that has excellent flexibility and bending workability even during the precious metal clay shaping process, even after the precious metal clay has dried, and as a result, the shaping time such as bending can be increased. An object is to provide a clay-like composition for forming a knot.

In order to solve the above-mentioned problems, the inventors tried to add various organic substances to noble metal clay (clay-like composition for forming a noble metal sintered body). Researched earnestly. As a result, it has been found that by adding a predetermined amount of propylene glycol to the noble metal clay, it is possible to have sufficient flexibility and bending workability even after the noble metal clay is dried during the shaping of the noble metal clay. It was.
Furthermore, as a result of repeated detailed experiments, it has been found that a better effect can be obtained by adding one or both of glycerin and polyethylene glycol than by adding propylene glycol alone. The present invention has been made on the basis of the above-mentioned knowledge, and the configuration and the background to arrive at the present invention will be described below.

The clay-like composition for forming a noble metal sintered body of the present invention (hereinafter referred to as “noble metal clay”) is, for example, a powder containing gold or silver or a silver alloy as a noble metal, at least an organic binder such as methylcellulose, It is obtained by adding water and adding at least a predetermined amount of propylene glycol as an additive component.

The propylene glycol described above is widely used as a solvent, and is added to a solution to adjust the viscosity, or added to foods and cosmetics to provide water retention. However, it has not been known at all what characteristics are exhibited by drying during molding in addition to precious metal sintering clay.

In order to solve the above-mentioned problems, the present inventors have determined the type and amount of additives to be added to the clay-like composition for forming a noble metal sintered body and the characteristics of the clay-like composition after drying by shaping. Evaluation was performed from the viewpoint of flexibility, bending workability, and formability.
As a result of continuing intensive studies based on the evaluation results, the present inventors have come up with the following present invention.

(1) A clay-like composition for forming a precious metal sintered body containing at least a precious metal powder and / or a precious metal alloy powder, an organic binder, an organic additive, and water,
A clay-like composition for forming a precious metal sintered body, wherein the organic additive is propylene glycol of 0.1 to 3.0% by mass.
(2) The clay-like composition for forming a noble metal sintered body according to (1), which further contains glycerin as the organic additive.
(3) The clay-like composition for forming a noble metal sintered body according to (1) or (2), further comprising polyethylene glycol as the organic additive.

According to the clay-like composition for forming a noble metal sintered body of the present invention, the clay-like composition for forming a noble metal sintered body containing at least a noble metal powder and / or a noble metal alloy powder, an organic binder, an organic additive and water. Since the organic additive is 0.1 to 3.0% by mass of propylene glycol, excellent flexibility and bending workability can be obtained even after the noble metal clay is dried during the molding. As a result, it is possible to provide a clay-like composition for forming a noble metal sintered body with less time constraints during processing such as bending.

Sectional photograph of the noble metal clay which concerns on this invention example 3 which was able to shape | mold into the plate shape of thickness 3mm entirely. A cross-sectional photograph of a precious metal clay according to Comparative Example 2 that partially recovered even after extension and could not be formed into a 3 mm thick plate overall.

Below, one Embodiment of the clay-like composition for noble metal sintered compact formation concerning this invention is described.
The clay-like composition according to this embodiment contains at least a noble metal powder and / or a noble metal alloy powder, an organic binder, an organic additive and water, and particularly 0.1 to 3.0% by mass of propylene as an organic additive. It contains glycol. Furthermore, it is desirable to contain glycerin or polyethylene glycol as the organic additive.
Here, in addition to the organic binder, the organic additive, and water, a surfactant, fats and oils, and olive oil may be added as necessary.

Next, the clay-like composition for forming a noble metal sintered body according to this embodiment will be described in detail.
(A) Noble metal powder, noble metal alloy powder As the noble metal powder and the noble metal alloy powder used in the present embodiment, gold powder, silver powder, copper powder, platinum powder, and alloy powders thereof can be used. A mixed powder of silver powder and copper powder can also be used. As the silver alloy powder, a silver-copper alloy is preferably used. These noble metal powders and / or noble metal alloy powders are the main components constituting a clay-like composition for forming a noble metal sintered body. The content is not a dominant condition in achieving the effect in the present embodiment, but the content is 50% by mass or more and 95% by mass in constituting a more practical clay-like composition. The following is preferable. That is, when the content is less than 50% by mass, the texture and gloss of the noble metal are not obtained. On the other hand, when the content exceeds 95% by mass, the elongation and strength of the clay-like composition are lowered, which is not preferable. The content of the noble metal powder and the noble metal alloy powder is more preferably 75 to 93% by mass.

(B) Organic Binder As the organic binder used in the present embodiment, at least one or two of a cellulose binder, a polyvinyl binder, an acrylic binder, a wax binder, a resin binder, starch, gelatin, and wheat flour are used. You may comprise by the above combination. Of the above, it is most preferable to use a cellulose-based binder, particularly water-soluble cellulose such as methylcellulose. The content of the organic binder in the clay-like composition is not particularly limited, but is considered to be 5 to 50% by mass, and more preferably 7 to 25% by mass.

(C) Organic additive Propylene glycol is used as the organic additive used in the present embodiment. However, when the content is less than 0.1% by mass, when the clay-like composition is dried, the flexibility is lowered, and the effect expected by the present embodiment is not sufficiently achieved. On the other hand, when the content exceeds 3.0% by mass, the formability as a clay-like composition is deteriorated and it is difficult to mold. Therefore, the content of propylene glycol is set to 0.1 to 3.0% by mass.
Furthermore, by adding glycerin and / or polyethylene glycol in addition to propylene glycol, the flexibility of the clay-like composition after drying is further improved.
When glycerin and polyethylene glycol are added, it is desirable to adjust the total content of propylene glycol, glycerin and polyethylene glycol to be 0.1 to 3.0% by mass. Glycerin and polyethylene glycol are liquid substances having both hydrophilic and lipophilic properties, and are known to give viscosity when contained in a clay-like composition. However, in the present embodiment, particularly when propylene glycol is added alone to the clay-like composition, the effect that the flexibility is not easily lowered even when the clay-like composition is dried is obtained when propylene glycol is added alone. In comparison, glycerin and / or polyethylene glycol is added based on the novel finding that the present inventors have found that the increase is greater.
The content of the organic additive in the clay-like composition is more preferably 0.5 to 2.0% by mass.

Furthermore, the clay-like composition for forming a noble metal sintered body according to this embodiment may further contain at least one of fats and oils, olive oil, and a surfactant as necessary.
The content of fats and oils in the clay-like composition is not particularly limited, but is considered to be 0.01 to 0.08% by mass, and more preferably 0.03 to 0.06% by mass.
The content of olive oil in the clay-like composition is not particularly limited, but is considered to be 0.001 to 0.05% by mass, and more preferably 0.01 to 0.03% by mass.
The content of the surfactant in the clay-like composition is not particularly limited, but is considered to be 0.001 to 0.05% by mass, and more preferably 0.01 to 0.03% by mass.

Examples of the fats and oils include organic acids (oleic acid, stearic acid, phthalic acid, palmitic acid, sepacic acid, acetylcitric acid, hydroxybenzoic acid, lauric acid, myristic acid, caproic acid, enanthic acid, butyric acid, capric acid). , Organic acid esters (organic acid esters having methyl, ethyl, propyl, butyl, octyl, hexyl, dimethyl, diethyl, isopropyl, and isobutyl groups), higher alcohols (octanol, nonanol, decanol) And polyhydric alcohols (glycerin, arabit, sorbitan), ethers (dioctyl ether, didecyl ether) and the like.

The surfactant is added to and mixed with the clay-like composition, thereby pulverizing a solid material generated by the reaction between the binder and water and improving the mixing property between the noble metal powder and the binder. The kind of surfactant is not specifically limited, A normal surfactant can be used. Surfactant is a generic term for substances that have water-friendly parts (hydrophilic groups) and oil-friendly parts (lipophilic groups / hydrophobic groups) in the molecule. Polyethylene glycol in the embodiment is also included in the surfactant. However, the surfactant referred to here is one excluding polyethylene glycol added in anticipation of the action specific to the present embodiment, and dispersion / aggregation action, foaming / defoaming action, wettability improvement, Examples thereof include sodium lauryl sulfate and polyoxyethylene alkyl ether which are added in a predetermined amount for a softness / smoothing action, an antistatic action and the like.

The precious metal sintered body can be manufactured by kneading the above-mentioned clay-like composition for forming a precious metal sintered body, forming the precious metal sintered body into a predetermined shape, and then firing it.

Below, the manufacturing method of the clay-like composition demonstrated by this embodiment is demonstrated. First, methyl cellulose, surfactant, olive oil, propylene glycol, glycerin, polyethylene glycol and water as an organic binder are stirred and mixed in a stirring vessel. This binder mixed solution is introduced into the kneading apparatus together with the noble metal powder and / or the noble metal alloy powder.
In this embodiment, propylene glycol, glycerin and polyethylene glycol are added during the stirring and mixing of the binder mixed solution, but the organic binder, the noble metal powder and / or the noble metal alloy powder and water are added during the kneading in the kneading apparatus. You can also.
In the present embodiment, the stainless steel kneading container of the kneading apparatus is a container whose inner wall is coated with CrN. Since the CrN coating is excellent in wear resistance and lubricity, it is possible to suppress mixing of Fe.

Next, the clay-like composition of the present invention will be specifically described below with reference to examples.
First, methyl cellulose, surfactant, olive oil, propylene glycol, glycerin, polyethylene glycol and water as an organic binder were stirred and mixed in a stirring vessel to obtain a binder mixed solution. Next, this binder mixed solution was introduced together with silver powder into a stainless steel kneading apparatus having an inner wall coated with CrN.
In the kneading apparatus, a clay-like composition having the composition shown in Table 1 was prepared by kneading silver powder, a binder mixed solution and water.
In the following examples of the present invention and comparative examples, the case where silver powder is used as the noble metal powder is described, but the action of propylene glycol does not act specifically on the silver powder. Accordingly, the noble metal powder may be any other noble metal powder used in a clay-like composition for forming a noble metal sintered body, such as a gold powder and a silver alloy powder.

[Evaluation methods]
The clay-like composition shown in Table 1 was evaluated for Mayer hardness, bending workability, and formability.

(Meyer hardness)
In the Meyer hardness measurement, a steel ball is placed on a certain amount of dried clay, and a value obtained by dividing the applied load by the cross-sectional area of the recessed portion is obtained. The lower this value is, the softer, that is, the higher the flexibility even when the noble metal clay is dried.

In the present invention example and the comparative example, measurement was performed with a sample size: φ20 mm, a thickness: 3 mm, and a steel ball mass: 140 g, that is, a load [N]: 0.14 × 9.8 (gravity acceleration). Table 2 shows the results of evaluation with respect to three dry states of 0% by mass, 2.0% by mass, and 3.2% by mass.

(Bending workability)
After forming the clay-like composition shown in Table 1 into a plate having a length of 60 mm, a width of 5 mm, and a thickness of 2 mm, it was stored in a constant temperature and humidity chamber at room temperature and humidity of 40% for the time shown in Table 2, and then a cylinder having a diameter of 17 mm It was wound around a mold to evaluate cracks generated on the surface. The evaluation results are shown in Table 1. The case where a crack of 1 mm or more did not occur on the surface of the noble metal clay was evaluated as “A”, and the case where a crack of 1 mm or more occurred was evaluated as “B”. The evaluation results are shown in Table 2.

(Formability)
In order to form 10 g of the clay-like composition shown in Table 1 into a plate having a thickness of 3 mm, it was evaluated whether or not the precious metal clay could be plasticized into a plate when it was stretched with a flat plate. The case where it was able to be formed into a plate having a thickness of 3 mm as a whole was evaluated as “A”. B ”. FIG. 1 shows a photograph of the precious metal clay of Example 3 of the present invention which was formed into a plate shape having a thickness of 3 mm as a whole. FIG. The photograph of the noble metal clay of the comparative example 2 which could not be shape | molded in the shape is shown. The results of this evaluation are shown in Table 2.

From the results shown in Table 2, for the inventive examples 1 to 7 in which 0.1 to 3.0% by mass of propylene glycol was added to the clay-like composition, the Mayer hardness was lowered even after the amount of the clay-like composition material was reduced, and the molding work It was possible to maintain flexibility even after drying. Further, it was found that the bending workability was not inferior even after long-term storage in a constant temperature and humidity chamber, and the formability was sufficient. On the other hand, in Comparative Example 1 in which propylene glycol was not added, the Mayer hardness was increased after the mass was decreased, and the bendability was deteriorated. Moreover, in Comparative Example 2 in which 3.8% by mass of propylene glycol was added, the result was inferior in the formability because of too much elasticity.

The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit of the present invention. The present invention is not limited by the above description, but only by the scope of the appended claims.

According to the present invention, even when the precious metal clay is dried in the middle of modeling, it has excellent flexibility and bending workability. It is possible to provide an excellent clay-like composition for forming a precious metal sintered body.
Moreover, a noble metal sintered compact can be manufactured by knead | mixing the clay-like composition for noble metal sintered compact formation of this invention, shape | molding in a predetermined shape, and baking.

Claims

A clay-like composition for forming a noble metal sintered body containing at least a noble metal powder and / or a noble metal alloy powder, an organic binder, an organic additive and water,
A clay-like composition for forming a precious metal sintered body, wherein the organic additive is propylene glycol of 0.1 to 3.0% by mass.
The clay-like composition for forming a noble metal sintered body according to claim 1, further comprising glycerin as the organic additive.
The clay-like composition for forming a noble metal sintered body according to claim 1 or 2, further comprising polyethylene glycol as the organic additive.