JPH05263102A - Method for forming noble-metal article - Google Patents

Abstract

PURPOSE:To form a noble-metal article by using a die. CONSTITUTION:82 to 96wt.% of a powder selected from a noble-metal powder and/or a noble-metal powder or a mixture of a noble-metal powder or a noble- metal alloy powder and a metal powder or a metallic alloy powder, 2-10wt.% of a thermoplastic resin and 2-10wt.% of a plasticizer are mixed to prepare a noble-metal plastic composition. The composition is filled in the recesses 1b and 2b formed in a couple of split molds 1 and 2, the molds 1 and 2 are butted on each other to integrate the composition filled in the respective recesses 1b and 2b, and then the molds 1 and 2 are opened to release the formed composition which is calcined.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a noble metal article, and more particularly to a method for forming a noble metal article suitable for forming a noble metal article using a molding die.

[0002]

2. Description of the Related Art Conventionally, a noble metal such as Au, Ag, Pt, Pb or an alloy material containing these metals as a main component has been used as a molding material for arts and crafts, etc. to form an article having a complicated shape. However, casting and rolling are the main ones of the modeling methods.

However, such a molding method not only requires large-scale equipment, but also has a problem that it is difficult to perform molding by casting depending on the metal, for example, Pt has a high melting point. It is left.

Therefore, the applicant of the present application has previously proposed a clay-like noble metal plastic composition excellent in moldability. (JP-A-4
-26707) This is produced by mixing the above-mentioned noble metal powder or noble metal alloy powder with a water-soluble binder, and is made into a noble metal article by firing after shaping.

[0005]

By the way, the above-mentioned noble metal plastic composition is a very useful molding material in that it is excellent in moldability and can easily form various complicated shapes. The following characteristics have been demanded.

[0006] That is, if the technique of injection molding using a pair of molding dies is adopted in the production of articles, there is an advantage that articles of the same shape can be easily obtained, but noble metal produced by using the water-soluble binder. Since the plastic composition has a high viscosity, it is difficult to fill it in a mold and is not suitable for injection molding.

In order to perform molding using the molding dies, the molding dies are made into a pair of split dies, and the noble metal plastic composition is packed in the recesses (cavities) of the split dies, and the split dies are formed. It is conceivable that the noble metal plastic compositions packed in these split molds are brought into close contact with each other and integrated by abutting.

However, also in this method, the self-adhesiveness of the above-mentioned noble metal plastic composition, that is, the integration at the time of the subsequent application is not complete, and some pretreatment is required, and the binder evaporates over time. Since the viscosity of the noble metal plastic composition changes with time, it is necessary to control the viscosity of the noble metal plastic composition in order to surely fit it into the split cavity shape.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to effectively solve the above-mentioned conventional demands.
The method for forming a noble metal article described is a noble metal powder and / or a noble metal alloy powder, or a powder selected from a noble metal powder or a mixed powder of a noble metal alloy powder and a metal powder or a metal alloy powder, in an amount of 82% by weight to 96% by weight. And 2% by weight of thermoplastic resin
10 wt% and 2 wt% to 10 wt% of a plasticizer are mixed to produce a noble metal plastic composition, and the noble metal plastic composition is filled in the recesses formed in the pair of molds. Then, the pair of molding dies are butted against each other, and the precious metal plastic compositions filled in the respective recesses are brought into close contact with each other to be integrated, and then the molding die is opened to release the molded precious metal plastic composition. After that, the molded noble metal plastic composition is fired. In the invention according to claim 2, the noble metal powder according to claim 1 is A
It is characterized in that it is a mixed powder of one kind or two kinds or more selected from u, Ag, Pt, and Pd. The invention according to claim 3 is characterized in that the noble metal alloy powder according to claim 1 is a mixed powder of one kind or two or more kinds selected from an Au alloy, an Ag alloy, a Pt alloy, and a Pd alloy. In the invention according to claim 4, the metal powder according to claim 1 is Al, Ni, Co, Fe, Cu, Ti, Zn, S.
It is characterized by being a mixed powder of one or more kinds selected from n, Zr, V, Pb, and Cr. In the invention according to claim 5, the metal powder according to claim 1 is an Al alloy, a Ni alloy, a Co alloy, a Fe alloy, a Cu alloy, a Ti alloy, a Zn alloy, a Sn alloy, a Zr alloy, a V alloy, a Pb alloy, and , And a mixed powder of one or more selected from Cr alloys. In the invention according to claim 6, the thermoplastic resin according to claim 1 is an acrylic resin, and the plasticizer is one or two selected from a phthalic acid compound or polyethylene glycol.
It is characterized by being more than one species.

[0010]

The noble metal plastic composition according to any one of claims 1 to 3 softens at a temperature near body temperature and is not sticky, has good plasticity, that is, moldability, and is pressed or kneaded with a separate composition. In that case, they can be easily integrated and easily sprinkled (the self-adhesiveness is good).

Therefore, when filling the split molds, it is possible to easily fit the shape of the cavity, and the split molds are butted to integrate the noble metal plastic compositions filled in the split molds. Further, when the split mold is opened, the noble metal plastic composition is easily released, and the molding using the split mold is effectively performed.

Further, the noble metal plastic composition according to claims 4 and 5 is provided with various color tones by the mixed metal powder.

Further, according to claim 6, the characteristics of the noble metal plastic composition according to claim 1 are preferably embodied.

Here, specific examples of each component and the reasons for limiting the above-mentioned formulation examples will be described. (A) Noble metal powder or noble metal alloy powder As the noble metal powder, spherical, irregularly shaped or flattened powder having an average particle diameter of 200 μm or less can be used. As the noble metal forming the noble metal powder, one kind or two kinds or more selected from Au, Ag, Pt, and Pd or alloys thereof is used. This noble metal powder is a main component constituting the noble metal plastic composition and is an important factor for determining the color tone of the product, but when the content is less than 82% by weight,
The color becomes unclear, or the precious metal plastic composition does not sinter well, and if it exceeds 96% by weight, the elongation (tackiness) and the plasticity of the obtained precious metal plastic composition deteriorate, and cracking occurs. Etc. are likely to occur.

(B) Composition of Binder (a) Thermoplastic Resin The thermoplastic resin is an acrylic resin such as polymethylmethacrylate, which retains the shape of the noble metal plastic composition in a good condition and which is combined with a plasticizer. Depending on the combination, the noble metal plastic composition has a plasticity in the vicinity of the body temperature of the operator,
It imparts characteristics such as self-adhesiveness, elongation, and crack prevention. The acrylic resin is usually stored in a state of being dissolved in a solvent such as toluene or ethanol, but these solvent components are removed by evaporation in the manufacturing process of the noble metal plastic composition. Compounding amount of this thermoplastic resin (ie,
If the compounding amount (after the solvent component is removed) is less than 2% by weight, the properties such as self-adhesiveness, elongation, and crack prevention cannot be sufficiently obtained, while if it exceeds 10% by weight, molding is performed. When degreasing / sintering the body, deformation of the molded body, sagging, foaming, etc. occur, and a sintered body having a desired shape cannot be obtained. Therefore, the blending amount of the thermoplastic resin is 2% by weight to 10% by weight. I decided. (B) Plasticizers Plasticizers include phthalic acid compounds such as DBP (diN-butyl phthalate), DEP (diethylhexyl phthalate), DOP (diN-octyl phthalate), polyethylene glycol, ethylene glycol, glycerin and the like. One or more selected from alcohols are used. This plasticizer, when combined with the thermoplastic resin, imparts the noble metal plastic composition with properties such as plasticity, self-adhesiveness, elongation, and prevention of cracking in the vicinity of the body temperature of the operator, as described above. However, the compounding amount is 2
If it is less than 10% by weight, properties such as plasticity, elongation, and crack prevention cannot be sufficiently obtained, while if it exceeds 10% by weight, the self-adhesiveness is lowered, and the internal properties of the molded product during molding are deteriorated. Since many air bubbles are involved, the strength of the molded body is reduced and molding becomes difficult, and there is a problem that it becomes greasy and the feel is bad, etc.
The compounding amount of the plasticizer was set to 2% by weight to 10% by weight. (C) Dispersant The dispersant is preferably added, for example, a surfactant such as Span 80 (sorbitan monooleate) is used, which enhances the mixing property of the powder and the binder, and is unavoidable. 0.05% to 6% by weight including impurities
Is added within the range. (D) Blending Ratio of Thermoplastic Resin and Plasticizer The reason why the blending amounts of the thermoplastic resin and the plasticizer are almost the same is that if either is large, the self-adhesiveness of the resulting noble metal plastic composition decreases. It also causes stickiness during handling.

(C) Metal powder or metal alloy powder These are Al, Ni, Co, Fe, Cu, Ti and Z.
n, Sn, Zr, V, and Cr, or a mixed powder of one or more selected from these alloys is used, and is added to adjust the strength and color tone of the resulting noble metal plastic composition. However, the addition amount thereof is appropriately set according to the intended strength and color tone.

[0017]

EXAMPLES The present invention will be described below with reference to examples. Acrylic resin: 50 wt%, toluene: 50 wt% Acrylic resin solution, PEG, DBP, and Span 80 in ethanol at room temperature so that the blending ratio after evaporation and drying is the blending ratio shown in Table 1. To produce a binder solution, and add an average particle size of 20 μm to each of these binder solutions.
m Au powder, Ag powder having an average particle size of 30 μm, and
Cu powder having an average particle diameter of 25 μm was mixed in the same mixing ratio as shown in Table 1 after evaporation and drying, and the mixed solution thus obtained was spread on a vat and kept at a temperature of 40 ° C. for 24 hours. By doing so, it was naturally dried to obtain Noble Metal Plastic Compositions 1-5. The composition of the noble metal plastic composition in Table 1 is a value calculated from the charged amount at the time of production, assuming that toluene and ethanol are completely removed in the drying step, and excludes a trace amount of unavoidable impurities. It is the value calculated by

[0018]

[Table 1]

Each of the thus obtained noble metal plastic compositions was tested for self-adhesion at room temperature, elongation, and adhesion with other substances (stickiness), and the results are shown in Table 2. It was shown to. Test conditions Self-adhesiveness: After pressure-bonding the noble metal plastic composition divided into two, a tensile force is applied with the pressure-bonded surface as a boundary,
At this time, check for the presence or absence of peeling on the pressure-bonded surfaces of both test pieces,
The case where there was no peeling was marked with “◯”, the case where peeling was slight was marked with “Δ”, and the case where peeling was large was marked with “x”. Elongation: Tensile force was applied to the noble metal plastic composition, and the elongation rate at the time when rupture occurred was measured. Adhesion with other substances; When the noble metal plastic composition is kneaded by hand, the state of adhesion to the hand is examined. When there is no adhesion, it is "○", when a small amount of adhesion is produced, "△"",Also,
The case where there was a large amount of adhesion was designated as "x".

[0020]

[Table 2]

In addition, as comparative examples, compositions 6 to 11 having the compounding amounts shown in Table 3 which deviated from the upper limit and the lower limit of the thermoplastic resin and the plasticizer, respectively, were prepared, and these were carried out in the present embodiment. A test similar to the example was conducted, and the results are shown in Table 4.

[0022]

[Table 3]

[0023]

[Table 4]

As is clear from these results, when the composition and the compounding ratio of this example are within the ranges, the self-adhesiveness and the elongation at room temperature are sufficient, and the adhesiveness with other substances is low. A noble metal plastic composition having excellent plasticity and easy to handle is obtained, and it is preferably used as a molding material.

Next, a method of shaping the thus-produced noble metal plastic composition will be described with reference to FIGS. 1 to 4.

This example illustrates the formation of a noble metal article having an array-like shape, that is, a shape in which a spherical weight portion is integrally provided at both ends of a cylindrical grip portion. Butt face 1a of split mold 1.2
2a has a recess (cavity) 1b having the same shape as the shape obtained by dividing the array-like shape in a plane including the axis line.
b (see FIG. 1), first, the noble metal plastic composition A of Example 2 is evenly distributed in the recesses 1b and 2b of the split molds 1 and 2 as shown in FIG. Noble metal plastic composition A is added to each split mold
From the abutting surfaces 1a and 2a, the height is slightly raised on average.

In the filling operation of the noble metal plastic composition A, the noble metal plastic composition A is appropriately softened by kneading the noble metal plastic composition A by hand or after applying a little heat. As a result, the work becomes easy, and the noble metal plastic composition A becomes
・ Can be smoothly blended into the inner surface of 2b.

Further, since the noble metal plastic composition A has a low adhesiveness to other substances, it does not stick to the hands during packing, and the packing operation is facilitated also from this point.

Next, the two split molds 1 and 2 are abutted against each other while being positioned relative to each other by a mold or the like, and the noble metal plastic compositions A inside are brought into close contact with each other. Thereby, both noble metal plastic compositions A are integrated by self-adhesion.

Further, after a lapse of a predetermined time, the split type 1.2
And the noble metal plastic composition A is released from the split molds 1 and 2. In this state, the noble metal plastic composition A is molded into an array, and as shown in FIG.
In some cases, parting lines L along the abutting surfaces 1a and 2a of the split molds 1 and 2 remain on the surface.

This parting line L is a split mold 1-2.
Although it depends on the filling density and the amount of swelling of the noble metal plastic composition A, the amount can be reduced to an almost inconspicuous level by adjusting these appropriately. And
When the parting line L is generated, it is removed at a stage where the viscosity remains after the mold release, or after the next firing step.

Next, the noble metal plastic composition A released as described above is heated and fired to obtain a noble metal article B having an array shape as shown in FIG.

The firing conditions are the noble metal plastic composition A
It depends on the type of the noble metal powder and the metal powder contained in, but for example, when the noble metal powder contained is pure Ag powder only, pure Au powder alone is obtained by firing in air at 900 ° C. for 1 hour or more. Is 1050 in the air
By firing at ℃ for 1 hour or more, again Au-Ag
-In case of Cu mixed powder, heating rate in H2 flow: 1 ℃
Each desired noble metal article can be obtained by heating to 700 ° C./min, holding for 5 hours or more to remove the binder, and then firing at 860 ° C. for 1 hour or more.

As described above, according to the method for forming a noble metal article according to the present invention, the noble metal plastic composition A is divided into the split molds 1.2.
When giving a shape using, it is possible to impart appropriate viscosity to the noble metal plastic composition A by body temperature or slight heating so that the noble metal plastic composition A can be smoothly blended with the inner surfaces of the recesses 1b and 2b of the split mold 1.2. As a result, the shapes of the recesses 1b and 2b are surely transferred to the noble metal plastic composition A.

Further, the split molds 1 and 2 are butted against each other and the noble metal plastic compositions A packed in them are pressure-bonded to each other, so that they are integrated by their self-adhesiveness. In the subsequent release from the split dies 1 and 2, the low adhesiveness to the other materials of the noble metal plastic composition A facilitates the release, and ensures that the shape transferred from the split dies 1 and 2 is reliable. Held in.

By the firing treatment after the mold release, a noble metal article B having a shape similar to the shape given by the split molds 1 and 2 is obtained although the volume is slightly reduced. Thus, according to the method of the present invention, the split mold 1
The molding of a precious metal article using 2 is easily and surely performed.

The shapes, dimensions, materials, etc. of the constituent members shown in the above embodiment are merely examples, and can be variously changed according to design requirements.

For example, although Ag is exemplified as the powder in the above-mentioned embodiments, the present invention is not limited to this, and other noble metal powders or alloys thereof, or those containing other metals or alloys thereof added thereto. Of course it's good.

Further, the material of the split molds 1 and 2 can be appropriately selected, and for example, a molding rubber containing silicon rubber as a main component is used. The use of this molding rubber is advantageous when transferring a complicated shape, because the split molds 1 and 2 are elastically deformed at the time of mold release.

[0040]

As described above, according to the method for forming a noble metal article according to the present invention, the following excellent effects are exhibited.

When the noble metal plastic composition is given a shape using a split mold, the noble metal plastic composition is given an appropriate viscosity by body temperature or slight heating so that the noble metal plastic composition is smoothly blended with the inner surface of the recess of the split mold. Therefore, the shape of the recess can be surely transferred to the noble metal plastic composition.

Further, the two split molds are abutted against each other and the noble metal plastic compositions packed in them are pressure-bonded to each other, so that they can be integrated by their respective self-adhesiveness. At the time of releasing, it is possible to facilitate the releasing due to the low adhesiveness to the other material of the noble metal plastic composition, and to reliably hold the shape transferred from the split mold.

Although the volume is slightly reduced by the baking treatment after the mold release, a noble metal article having a shape similar to the shape given by the split mold can be obtained, and the shape set by the split mold can be surely made into a metal. Can be given to goods.

As described above, according to the method of the present invention, the molding of the noble metal article using the split mold can be carried out easily and reliably.

[Brief description of drawings]

FIG. 1 is a perspective view of a split mold used in the present invention.

FIG. 2 is a perspective view for explaining packing of a noble metal plastic composition into a split mold.

FIG. 3 is a perspective view showing the noble metal plastic composition in a state of being released from the split mold.

FIG. 4 is a perspective view of a noble metal article obtained after firing.

[Explanation of symbols]

 1 split mold 1a butt face 1b recess 2 split mold 2a butt face 2b recess A precious metal plastic composition B precious metal article L parting line

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Akira Mori Inventor Mita City, Hyogo Prefecture Techno Park 12 No. 6 Sanritsu Material Co., Ltd. Mita Factory

Claims (6)

[Claims] 1. Noble metal powder and / or noble metal alloy powder,
Alternatively, 82% by weight to 9% by weight of a powder selected from a mixed powder of a noble metal powder or a noble metal alloy powder and a metal powder or a metal alloy powder.
6% by weight, and 2% by weight to 10% by weight of thermoplastic resin,
2% to 10% by weight of a plasticizer is mixed to form a noble metal plastic composition, and the noble metal plastic composition is filled in the recesses formed in the pair of split molds, and then the The split molds are butted, the noble metal plastic compositions filled in the respective recesses are brought into close contact with each other to be integrated, and then the split mold is opened to release the noble metal plastic composition, and then the molding is performed. A method for shaping a noble metal article, which comprises firing the obtained noble metal plastic composition. 2. The method for forming a noble metal article according to claim 1, wherein the noble metal powder is one or a mixture of two or more selected from Au, Ag, Pt, and Pd. 3. The precious metal article according to claim 1, wherein the precious metal alloy powder is one kind or a mixed powder of two or more kinds selected from an Au alloy, an Ag alloy, a Pt alloy, and a Pd alloy. Modeling method. 4. The metal powder is Al, Ni, Co, F
The method for forming a noble metal article according to claim 1, which is a mixed powder of one or more selected from e, Cu, Ti, Zn, Sn, Zr, V, Pb, and Cr. 5. The metal powder is an Al alloy, a Ni alloy, or C
o alloy, Fe alloy, Cu alloy, Ti alloy, Zn alloy, S
The method for shaping a noble metal article according to claim 1, which is a mixed powder of one kind or two kinds or more selected from an n alloy, a Zr alloy, a V alloy, a Pb alloy, and a Cr alloy. 6. The thermoplastic resin is an acrylic resin, and the plasticizer is one or two selected from phthalic acid compounds and polyethylene glycol.
The method for forming a noble metal article according to claim 1, wherein the method is at least one kind.