JPWO2011021649A1 - Method for producing copper sinter article for craft or decoration and copper-containing plastic composition - Google Patents

Abstract

Provided are a method for producing a copper sintered article for craft or decoration related to copper or a copper alloy that can be air-fired in a general-purpose heating furnace or the like, and a copper-containing plastic composition. The method for producing a craft or decorative copper sintered article according to the present invention comprises a copper-containing plastic composition containing at least one powder selected from copper and a copper alloy containing 50% by weight or more of copper and an organic binder. After the copper shaped body is formed, the copper shaped body is fired to obtain a copper shaped fired body, which is a method for manufacturing a craft or decorative copper sintered article, wherein the powder contains the copper-containing plastic composition. The copper shaped plastic composition having an average particle size of 10 μm or less is obtained, and the copper shaped body is fired in the air to obtain a copper shaped fired body.

Description

  The present invention relates to a method for producing a copper sintered article for craft or decoration related to copper or a copper alloy that can be air-fired in a general-purpose heating furnace or the like, and a copper-containing plastic composition.

  Conventionally, as a copper material for arts and crafts, a copper-containing plastic composition obtained by mixing copper powder or copper alloy powder and an organic binder is known. This copper-containing plastic composition is shaped, and the copper shaped body is fired to obtain a copper shaped fired body. For example, Patent Documents 1 to 4 can be cited as examples.

In Patent Documents 1 and 2, the first metal particles having an average particle size of 3 to 8 μm of 25% by weight or more and less than 100% by weight and the first metal particles having an average particle size of more than 0% by weight and 75% by weight or less of 15 to 25 μm A plastic composition obtained by mixing a mixed powder of two metal particles and an organic binder is used.
In <Example 19> described in paragraph [0026] of Patent Document 1 and paragraph [0028] of Patent Document 2, 75% by weight of first copper particles having an average particle diameter of 5 μm and an average particle diameter of 20 μm are used. An example is shown in which second copper particles are used in combination with 25% by weight.
Then, as described in paragraph [0031] of Patent Document 1 and paragraph [0033] of Patent Document 2, the firing conditions of <Example 19> in which the two types of copper particles were mixed were as follows: It is clearly stated that firing was performed in an inert atmosphere by introducing nitrogen or argon gas therein.

On the other hand, in Patent Document 3, a plastic composition containing a precious metal mixed powder containing silver and copper is primarily sintered at 400 ° C. or higher in an oxidizing atmosphere, and then secondary at 800 ° C. or higher in a reducing atmosphere. A method of sintering is disclosed.
In the examples, examples are shown in which mixed powders containing 2.0 to 12.5% by weight of pure Cu having an average particle diameter of 18 μm and Cu-50 wt% Ni alloy powder having an average particle diameter of 20 μm are shown. According to the results, when primary sintering is performed in an oxidizing atmosphere at a temperature of 400 ° C. or higher, and then secondary sintering is performed in a reducing atmosphere, a sintered body having a uniform color tone without visible holes can be obtained. In the case of using the mixed powder A containing only 12.5% by weight of pure Cu having an average particle diameter of 18 μm, when baked only in an oxidizing atmosphere (in the air), there are visible holes or color tone. It has been reported that it becomes a non-uniform sintered body and does not become a precious metal ornament or precious metal arts and crafts.

Patent Document 4 discloses that a plastic composition containing a powder containing copper or a copper alloy is primarily sintered in an oxidizing atmosphere at 230 to 300 ° C. for 4 to 6 hours, and then 700 in a reducing atmosphere. A method of secondary sintering at ˜1000 ° C. for 2-3 hours is disclosed. In the examples, an example using spherical copper powder having an average particle size of 37 μm is shown, and after demolding a molded body of a plastic composition containing this copper powder and an organic binder at about 250 ° C. for 5 hours in the air. It has been reported that sintering was performed at 1000 ° C. for 2 hours in a hydrogen stream.
In these patent documents 3 and 4, the primary firing in the oxidizing atmosphere is premised on the secondary firing in the reducing atmosphere, and if the firing is performed only in the oxidizing atmosphere, the precious metal ornaments and the precious metal arts and crafts As described above, this is not the case.

Furthermore, a copper-containing plastic composition obtained by mixing copper powder or copper alloy powder and an organic binder and a noble metal-containing plastic composition of a different noble metal are combined and shaped, and an example of obtaining a fired body by firing the shaped body, It is disclosed in Patent Documents 5 to 7. In Patent Documents 5 to 7, copper is included in noble metals, but copper is significantly more resistant to corrosion (oxidation resistance) than general noble metals which are gold, silver and white metal elements. As described above, it has the property that the property is inferior.
In Patent Document 5 and Patent Document 6, the plastic composition containing pure gold powder is sintered in the air, that is, in an oxidizing atmosphere, and 75.0 wt% gold, 12.5 wt% silver, and 12. In the case of a plastic composition containing a so-called alloy metal of K18 mixed at a ratio of 5% by weight, it is described that sintering is performed in an argon gas atmosphere. That is, it is disclosed that even a plastic composition containing an alloy metal such as K18 containing only 12.5% by weight of copper must be sintered in an inert atmosphere.
However, none of these Patent Documents 5 and 6 proposes an invention of firing in a state where a plastic composition of metal powders having different colors is physically combined, for example, an oxidation containing pure gold. In a state where the plastic composition A that is fired in an atmosphere and the plastic composition B that is fired in an inert atmosphere containing copper such as K18 are combined, there is no disclosure as to under what conditions. In particular, Patent Document 7 does not allow any description of the firing atmosphere.

JP 2007-113107 A JP 2007-113106 A Japanese Patent No. 3191434 Japanese Patent Publication No. 6-37642 Japanese Patent No. 2924139 Japanese Patent No. 2932648 Japanese Patent No. 3389613

As described above, a copper-containing plastic composition obtained by mixing copper powder or copper alloy powder and an organic binder is fired in an inert atmosphere or a reducing atmosphere. This is because, when fired in an oxidizing atmosphere, that is, when fired in the atmosphere, the fired copper shaped fired body becomes extremely weak. In order to increase the strength, it must be sufficiently sintered, so it must naturally be fired for a long time. This is because the degree of oxidation from the surface to the inside increases further, and as a result, the fired copper shaped fired body becomes fragile and unusable.
In addition, a composite shaped body combined with a copper-containing plastic composition containing copper or a copper alloy and a noble metal-containing plastic composition containing a noble metal such as silver having oxidation-resistant properties that are not oxidized in the atmosphere during firing In order to obtain a decorative metal article by firing without deteriorating, it is not specifically known under what conditions and procedures it should be fired.

  Therefore, in view of the above, the present inventors have used copper or copper alloys that are known in many shades such as copper of bronze, bronze, bronze, brass, and the like. As a result of studying to provide a copper-containing plastic composition that can be fired in the atmosphere in a general-purpose heating furnace for the copper-containing plastic composition, copper or copper alloy powder in the copper-containing plastic composition Is limited to a powder with a specific average particle size of 10 μm or less, the necessary strength can be obtained for sintered articles for crafts and decorations even when fired in the atmosphere, and it can be fired in a short time, and the crafts are also well-crafted. As a result, the inventors have found a point that can be used as a sintered article for decoration, and have arrived at the present invention.

For example, by limiting the powder in a copper-containing plastic composition containing at least one powder selected from copper and copper alloy of 50 wt% or more to an average particle size of 10 μm or less, the copper content Even if the copper shaped body formed using the plastic composition is fired in the air, the copper shaped fired body can obtain a certain strength required for a sintered article for crafts and decoration, and fired in a short time. Since the process can be completed, even if the surface of the copper or copper alloy copper molding fired body is oxidized very thinly by atmospheric firing, it is not affected by the oxidation to the inside. Therefore, the oxide film on the surface of the copper molded fired body can be easily peeled off, and a product that can be sufficiently used as a sintered article for crafts or decoration is obtained.
Therefore, since firing in a reducing atmosphere is not performed as in the prior art, a troublesome work that requires an inert gas such as argon gas or nitrogen gas to continue to flow during firing and a reducing agent such as carbon are added together with the copper shaped body. Troublesome work such as heating in the sealed container can be avoided, and it can be easily applied at culture schools.
In particular, when forming a decorative object by combining a copper shaped fired body of the copper-containing plastic composition according to the present invention and a noble metal shaped fired body of a noble metal-containing plastic composition containing a noble metal powder such as silver, the same atmosphere is used. It can be fired, the same firing equipment can be used, and it is extremely efficient.

  The method for producing a craft or decorative copper sintered article according to claim 1 of the present invention contains one or more powders selected from copper and a copper alloy containing 50% by weight or more of copper and an organic binder. After forming a copper shaped body with a copper-containing plastic composition, the copper shaped body is fired to obtain a copper shaped fired body. The copper-containing plasticity of a mixed powder consisting of 25 to 75% by weight of the first powder having an average particle diameter of 0.1 to 4 μm and the balance of the second powder having an average particle diameter exceeding 4 μm and not more than 10 μm A copper shaped fired body is obtained by firing the copper shaped body into the composition and air firing.

According to the method for manufacturing a craft or decorative copper sintered article according to claim 1 as described above, as described above, a copper shaped body obtained by shaping a copper-containing plastic composition into an arbitrary shape can be air-fired. Further, it is possible to obtain a copper molded fired body with higher strength, and the linear shrinkage rate can be suppressed, and about 10% of a wire equivalent to a silver-containing plastic composition containing a commercially available silver powder or silver alloy powder. The shrinkage rate can be set.
Furthermore, since it can be fired in the atmosphere as described above, the copper-containing plastic composition in the present invention is also integrated into a shaped body in combination with a silver-containing plastic composition containing silver powder or silver alloy powder. At the same time, the shaped body can be fired by atmospheric firing.

The “copper alloy” of the present invention means a copper alloy containing 50% by weight or more of copper. More preferably, a copper alloy containing no copper oxide is preferable. By not containing copper oxide, it is possible to avoid becoming porous.
The “average particle size” of the copper and copper alloy according to the present invention is also called a median diameter, a medium diameter, a median diameter, a median diameter, or a 50% particle diameter, and is usually represented by D50. Means a particle size corresponding to 50%. Specifically, using a laser diffraction particle size distribution measuring device (manufactured by Microtrac) having three laser scattered light detection mechanisms, the measurement conditions are [particle permeability: reflection] and [true sphere / non-spherical: non-spherical]. ] (When the particle permeability setting is set to reflection and the true / non-spherical selection is set to non-spherical), the D50 value of the particle size distribution is measured.
In the present invention, air firing means firing in the air and is synonymous with firing in an oxidizing atmosphere. The reducing atmosphere is treated synonymously with an inert atmosphere such as an argon gas atmosphere and includes these.

  The above-mentioned “silver alloy” and “noble metal” are silver alloys and noble metals having a copper content of less than 20% by weight, and preferably silver alloys and noble metals not containing copper. That is, it means an oxidation-resistant silver alloy or noble metal that does not affect the shape of the fired body even when fired in the air. As such a “silver alloy”, for example, a silver-Pd alloy having improved antisulfuration performance can be mentioned.

  The method for producing a craft or decorative copper sintered article according to claim 2 of the present invention is the above-described claim 1, wherein the copper shaped fired body obtained by air firing is pickled or pickled. It is characterized by polishing.

  According to the method for manufacturing a craft or decorative copper sintered article as set forth in claim 2, even if the surface of the copper or copper alloy copper shaped fired body is extremely thinly oxidized by air firing, Because it is not affected by oxidation, it is very easy to peel off the oxide film on the surface of the copper shaped fired body by pickling and polishing, and it can be used as a sintered article for craft and decoration. It is done.

  The copper-containing plastic composition according to claim 3 of the present invention is one or more powders selected from copper and a copper alloy containing 50% by weight or more of copper, and has an average particle size of 0.1 to 4 μm. The first powder is contained in an amount of 25 to 75% by weight, and the balance contains a mixed powder that is a second powder having an average particle size exceeding 4 μm and not more than 10 μm, and an organic binder.

Such a copper-containing plastic composition according to claim 3 can produce a copper shaped fired body having high strength while being capable of firing in the air a copper shaped body obtained by shaping the copper-containing plastic composition into an arbitrary shape. The linear shrinkage rate can also be suppressed, and the linear shrinkage rate can be about 10%, which is equivalent to that of a plastic composition containing commercially available silver or silver alloy. And since baking can be completed in a short time, even if the surface of the copper shaping | molding sintered body of copper or a copper alloy is extremely thinly oxidized by air baking, it does not receive the influence of oxidation to the inside. Therefore, the oxide film on the surface of the copper molded fired body can be easily peeled off, and a product that can be sufficiently used as a sintered article for crafts or decoration is obtained.
Therefore, it is not essential to perform firing in a reducing atmosphere as in the prior art, and firing can be performed in either a reducing atmosphere or an oxidizing atmosphere. In particular, if firing in a reducing atmosphere is not performed, an inert gas such as argon gas or nitrogen gas is used during firing. It is possible to avoid the troublesome work that has to be continued and troublesome work such as heating carbon from the outside by putting a reducing agent such as carbon in a sealed container together with the copper shaped body, so that it can be easily applied at culture schools etc. become.
Furthermore, since it can be fired in the atmosphere as described above, the copper-containing plastic composition in the present invention is also integrated into a shaped body in combination with a silver-containing plastic composition containing silver powder or silver alloy powder. At the same time, it is possible to fire the shaped body by atmospheric firing.

According to the method for manufacturing a craft or decorative copper sintered article of the present invention, the powder in a copper-containing plastic composition containing one or more powders selected from copper and copper alloy of 50% by weight or more of copper. Is limited to a specific particle size having an average particle size of 10 μm or less, and the copper-containing plastic composition using this is used, and the copper shaped body is air-fired in, for example, a general-purpose heating furnace. The fired body has a certain strength required for sinter articles for crafts and decoration, and since the firing is completed in a short time, the surface of the copper or copper alloy copper shaped fired body is oxidized very thinly by air firing. However, the inside is not affected by oxidation. Therefore, the oxide film on the surface of the copper molded fired body can be easily peeled off, and a product that can be sufficiently used as a sintered article for crafts or decoration is obtained.
That is, as described above, it has been conventionally known that a copper shaped fired body fired in the air is extremely weak, but in the present invention, one or more kinds of powders selected from copper and copper alloy are averaged. By limiting the particle size to a specific particle size of 10 μm or less, firing can be completed in a short time, and a certain strength required as a sintered article for craft or decoration can be obtained. Therefore, it can be easily applied at culture schools. Furthermore, when the copper-containing plastic composition according to the present invention is combined with a silver-containing plastic composition containing silver or a silver alloy powder to form a shaped body, the decoration is fired by atmospheric firing using the same firing apparatus. It is possible to reduce the burden on equipment.

  In addition, the copper-containing plastic composition of the present invention using a specific copper mixed powder having an average particle size of 10 μm or less and a different average particle size, and a method for producing a sintered copper article using the copper-containing plastic composition can be conventionally fired in the atmosphere. It can be handled in exactly the same manner as a silver-containing plastic composition known as a noble metal-containing plastic composition, and the copper-containing plastic composition of the present invention and a silver-containing plastic composition are combined to form a composite shaped body. At the same time, it can be fired in the atmosphere. In this case, as described above, copper or copper alloys are already known in many shades such as bronze, bronze, white, brass, etc., so combine them with silver. Therefore, it is possible to obtain a baked article for craft or decoration that is highly interesting and has a high contrast.

6 is a drawing-substituting photograph of a decorative metal product (ring) manufactured in Example 2. FIG. 4 is a drawing-substituting photograph of a decorative metal product (ring) manufactured in Example 3. FIG.

The copper-containing plastic composition used in the present invention contains at least one powder selected from copper and a copper alloy containing 50% by weight or more of copper and an organic binder, and has an average particle size of 10 μm or less. Is used.
As described above, copper has a bronze color, and copper alloys include bronze, which is a copper alloy with tin, white copper, which is a copper alloy with nickel, and zinc. Many shades are known, such as brass, which is a copper alloy. These copper powders and copper alloy powders are not particularly specified for production methods such as atomized powder, reduced powder, etc., but it is preferable that the particles have a nearly spherical shape, and a powder having an average particle size of 10 μm or less is used. Since it is used, it can be fired in the air in a short time, and the oxide film on the surface can be easily peeled off by rapid cooling, pickling or polishing.

The copper-containing plastic composition used in claim 1 of the present invention is a copper-containing plastic composition according to claim 3 of the present invention, and copper and a copper alloy of 50% by weight or more of copper and One or more powders selected from the group consisting of 25 to 75% by weight of a first powder having an average particle size of 0.1 to 4 μm, and the balance exceeding the average particle size of 4 μm and having an average particle size of 10 μm or less. It contains a mixed powder consisting of two powders and an organic binder.
By using the mixed powder composed of the first powder and the second powder, a copper shaped body obtained by shaping the copper-containing plastic composition into an arbitrary shape can be fired in the atmosphere, and a higher strength copper shaped fired body can be obtained. The linear shrinkage rate can also be suppressed, and the linear shrinkage rate can be about 10%, which is equivalent to a commercially available silver-containing plastic composition. Furthermore, also when combining with a commercially available silver containing plastic composition etc. to make a modeling body, a modeling body can be baked by air | atmosphere baking simultaneously with integral.

Further, the copper-containing plastic composition used in the first claim of the present invention is selected from copper and a copper alloy containing 50% by weight or more of copper. One or more kinds of powders containing 25 to 75% by weight of a first powder having an average particle size of 0.5 to 4 μm, and the balance comprising a second powder having an average particle size exceeding 4 μm and not more than 10 μm; And an organic binder.
Further, a more preferable copper-containing plastic composition is one or more kinds of powders selected from copper and a copper alloy containing 50% by weight or more of copper, and a first powder having an average particle size of 2.0 to 3.0 μm. It contains 30 to 70% by weight, and the balance contains a mixed powder composed of a second powder having an average particle size of 5 to 10 μm and an organic binder.
Thus, by using the mixed powder further specifying the respective particle size ranges of the first powder and the second powder, the strength after firing can be increased, and the linear shrinkage rate can be about 10%. Furthermore, the firing temperature can be lowered and the firing time can be shortened.

  Although it does not specifically limit as said organic binder, Cellulose type | system | groups, such as methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, carmellose (carboxymethylcellulose), carboxymethylcellulose sodium, carboxymethylcellulose potassium, carboxymethylcellulose calcium Alginate binder such as binder, sodium alginate, starch, starch starch, wheat flour, British gum, xanthan gum, dextrin, dextran, pullulan and other polysaccharide binders, gelatin and other animal binders, polyvinyl alcohol, polyvinylpyrrolidone and other vinyl binders , Polyacrylic acid, polyacrylic acid ester Preferred acrylic binder, polyethylene oxide, polypropylene oxide, and the like other resin-based binder such as polyethylene glycol for use in selecting one or more binders. In the cellulose binder, it is most preferable to use a water-soluble cellulose binder.

  Moreover, as conditions for the above-mentioned atmospheric firing of the copper-containing plastic composition, the firing temperature of the copper-containing plastic composition whose powder is pure copper is 990 ° C. × 3 minutes to 6 minutes, 980 ° C. × 4 minutes to 15 minutes, 970 ° C x 5 minutes to 30 minutes, 950 ° C x 5 minutes to 40 minutes, 850 ° C x 10 minutes to 50 minutes, 800 ° C x 30 minutes to 60 minutes, preferably 850 ° C to 980 ° C, Preferably it is 950 degreeC-970 degreeC. Of course, it is of course possible to fire at a similar temperature even in a reducing atmosphere, but the firing time should be longer.

Next, the copper-containing plastic composition used in claim 1 of the present invention and according to claim 3 of the present invention is combined with a silver-containing plastic composition containing silver or a silver alloy. The case where a decorative object is used will be described.
As described above, the copper-containing plastic composition used in claim 1 of the present invention and selected from claim 3 of the present invention is selected from copper and a copper alloy containing 50% by weight or more of copper. It is a powder of at least seeds and contains 25 to 75% by weight of a first copper powder having an average particle size of 0.1 to 4.0 μm, and the remainder exceeds the average particle size of 4.0 μm and has an average particle size of 10 μm or less. It contains a copper mixed powder consisting of two copper powders and an organic binder, and can be handled in exactly the same manner as a silver-containing plastic composition that has been conventionally known as a noble metal-containing plastic composition that can be fired in the atmosphere. The copper-containing plastic composition and the silver-containing plastic composition of the present invention are combined to form a composite shaped body, and a copper-silver shaped fired body can be obtained by air firing at the same time as an integral body.

  The silver-containing plastic composition combined with such a copper-containing plastic composition is one or more powders selected from silver and a silver alloy, and the first silver powder having an average particle diameter of 0.1 to 4.0 μm is 25 to 25. A silver-containing plastic composition containing 75% by weight of the silver mixed powder composed of a second silver powder having an average particle size of more than 4.0 μm and an average particle size of 40 μm or less and an organic binder is preferable. This silver-containing plastic composition is commercially available.

More preferably, the silver-containing plastic composition contains 25 to 75% by weight of the first silver powder having an average particle size of 0.5 to 4.0 μm, and the remainder exceeds the average particle size of 4 μm and the average particle size of 25 μm or less. A silver-containing plastic composition containing a silver mixed powder composed of the second silver powder.
Further, a more preferable silver-containing plastic composition contains 30 to 70% by weight of the first silver powder having an average particle diameter of 2.0 to 3.0 μm, and the balance is composed of the second silver powder having an average particle diameter of 5 to 20 μm. It is a silver containing plastic composition containing silver mixed powder.
Since these copper-containing plastic composition and silver-containing plastic composition can approximate the density and have the same linear shrinkage rate, one shrinkage is too large in the copper-silver molded fired body, and it peels off or forms after firing. There is no loss.

  In addition, the silver-containing plastic composition is not particularly specified as a method for producing silver powder, such as atomized powder or reduced powder, as in the case of the copper powder in the copper-containing plastic composition, but the particles have a shape close to a sphere. The organic binder can be the same as that described above in the copper-containing plastic composition.

In the case of forming an ornament as a composite shaped body by appropriately combining these copper-containing plastic composition and silver-containing plastic composition, unlike the above-mentioned firing conditions of the copper-containing plastic composition alone, 660-770 Bake in the atmosphere for 3 to 40 minutes at ° C. It is particularly preferred that the copper-containing plastic composition alone is fired in the air at a significantly lower temperature and in a shorter time than when the shaped body is fired in the air.
Of course, it is of course possible to fire at a similar temperature even in a reducing atmosphere, but preferably the firing temperature is higher and the firing time is longer. Further, for example, in order to burn the organic binder, the first half may be fired in the air, and the second half may be fired in a reducing atmosphere. As an example of this case, when the atmospheric firing in the first half reaches 350 ° C. to 450 ° C. from room temperature, the decoration is immediately taken out from a heating source such as an electric furnace, and is put together with a reducing agent such as carbon and sealed. The obtained stainless steel container is put into an electric furnace, heated from room temperature to 700 ° C. to 800 ° C., and then maintained at that temperature for 30 minutes to 9 hours, whereby firing in a reducing atmosphere can be performed.
In addition, the firing in an argon gas atmosphere is performed by circulating argon gas through an electric furnace so that the atmosphere does not enter.

  As one technique for forming a decorative article as a composite shaped body by appropriately combining the copper-containing plastic composition and the silver-containing plastic composition, a method for producing a decorative article having a marble pattern is illustrated.

  The manufacturing method of the ornament provided with this marble pattern is a rod-shaped body forming step in which the copper-containing plastic composition and the silver-containing plastic composition are each formed into a columnar shape to form a copper rod-shaped body and a silver rod-shaped body, Flatten at least part of the mixed rod-shaped body formed through the mixed rod-shaped body forming step and the mixed rod-shaped body formed by mixing the copper rod-shaped body and the silver rod-shaped body that have been subjected to the rod-shaped body formed step together to form a mixed rod-shaped body. A decorative object forming process for producing a decorative object, and a fired body manufacturing process for baking the obtained decorative object to obtain a decorative fired body.

In the mixing rod-shaped body forming step, the mixing rod-shaped body may be manufactured by accommodating the copper rod-shaped body and the silver rod-shaped body in a syringe and injecting the same, and further accommodating the ejected mixing rod-shaped body in a syringe. The operation of obtaining the mixed rod-like body that has been injected and re-injected may be repeated at least once to produce the mixed rod-like body.
In the mixed rod-shaped body forming step, the copper rod-shaped body and the silver rod-shaped body are wound together to form a columnar shape, then the columnar bodies are divided or folded, and the columnar bodies are wound together to form a column again. The mixing rod-like body may be manufactured by repeating the forming operation at least once.
In the decorative object forming step, the mixed rod-shaped body may be wound in a plane spiral shape, and at least the upper surface thereof may be flattened to form a plate shape.
In the decoration forming step, the mixing rod-shaped body may be wound in a plane spiral shape, and the upper and lower surfaces thereof may be flattened to form a plate, and the plate may be formed in a ring shape to manufacture the decoration.

  Moreover, when forming an ornament as a composite molded body by suitably combining 15 to 85% by weight of the copper-containing plastic composition and 85 to 15% by weight of the silver-containing plastic composition, it is 10 to 700 ° C at 700 to 750 ° C. It can be fired in the air for 15 minutes, and in this case as well, it is particularly preferable that the copper-containing plastic composition is fired in the air at a significantly lower temperature and for a shorter time than when fired in the air. The shaped and fired body fired in this way can be used as a decoration with a particularly well-balanced copper color and silver color.

Furthermore, if necessary, the following substances may be added to the organic binder as an additive to the copper-containing plastic composition or the silver-containing plastic composition. That is, the additives 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, citric acid. Acid), organic acid esters such as phthalic acid-n-dioctyl, phthalic acid-n-dipyl (methyl group, ethyl group, propyl group, butyl group, octyl group, hexyl group, dimethyl group, diethyl group, isopropyl group, isobutyl Organic acid ester having a group), higher alcohol (octanol, nonanol, decanol), polyhydric alcohol (glycerin, arabit, sorbitan, diglycerin, isoprene glycol, 1,3 butylene glycol), ether (dioctyl ether, didecyl ether) , Phenylpropane 1 type, or 2 or more types of mixtures (for example, olive oil containing many oleic acids) selected from the group consisting of lignin, liquid paraffin, and oils and fats, which is a network polymer formed by condensing the constituent units to be listed It is done. These additives are added for the purpose of improving plasticity, or added for the purpose of preventing the copper-containing plastic composition and the silver-containing plastic composition from adhering to the hand during molding. Furthermore, the above additives, lignin and glycerin, provide appropriate water retention.
Further, examples of the additive include anionic, cationic, and nonionic surfactants. The surfactant has an effect of improving the mixing property of silver powder or copper powder and an organic binder and an effect of improving water retention.

Among the organic binders, the water-soluble cellulose binder serves to impart plasticity. Of the organic binders, polyethylene oxide has a function of improving the adhesion in a liquid state by giving a high viscosity at a low concentration. Moreover, although sodium alginate gives moderate water retention like the said glycerol, it contributes also to the contact | adherence improvement effect | action. Furthermore, the polyacrylic acid ester and the polyacrylic acid serve to strengthen the adhesiveness.
The water-soluble cellulose binder serves to impart plasticity as described above, but the water-soluble cellulose binder includes methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose sodium, carboxymethyl cellulose. Potassium, carboxymethyl cellulose calcium and the like are used and dissolved in water.

As the amount of the organic binder in the copper-containing plastic composition and the silver-containing plastic composition using the water-soluble cellulose binder described above as the organic binder, as a more preferable aspect, the total amount of the organic binder is a solid content excluding water. It is desirable that it is within a range of 0.1 to 4 wt% in terms of display. In this case, if the amount of the organic binder is less than 0.1 wt%, it is difficult to obtain a homogeneous copper-containing plastic composition and silver-containing plastic composition. In addition, there is a disadvantage that the strength after coating and drying is weakened. When the amount of the organic binder exceeds 4 wt%, the shrinkage rate increases and cracks are likely to occur. Therefore, the amount of the organic binder is desirably 0.1 to 4 wt%.
When polyethylene oxide is used, it is desirable to use polyethylene oxide having a molecular weight of 100,000 to several million within the range of 0.1 to 3 wt%.
Moreover, when using surfactant, it is desirable to exist in the range of 0.03 to 3 wt%, and when using fats and oils, it is desirable to be within the range of 0.1 to 3 wt%.

Furthermore, water is added in a required amount. If it is too small, it becomes hard and difficult to form, and if it is too much, the shape cannot be maintained. The copper-containing plastic composition and silver-containing plastic composition used in the present invention can be prepared in the form of clay, paste, or slurry depending on the water content.
In the above preferred composition, the metal powder is 75 to 99 wt% in any plastic composition. However, if the amount is too small, the shrinkage becomes large and the sintering also becomes difficult. If the amount is too large, the organic binder is correspondingly increased. In addition, the ratio of water is reduced, which hinders modeling.

Moreover, you may add Bi, Se, Sb, In, Sn, Zn powder, or those alloy powders as a sintering promoter.
Furthermore, you may add the metal compound powder or glass powder chosen from lead carbonate, lithium carbonate, zinc oxide, phosphoric acid, sodium carbonate, vanadium oxide, sodium silicate, phosphate etc. as an adhesive improvement agent.
Further, for the purpose of improving plasticity, a network polymer formed by condensation of structural units having a skeleton of phenylpropane such as lignin, glycerin, diglycerin, isoprene glycol, 1,3 butylene glycol, liquid paraffin, alcohols, Fats and oils, phthalic acid, phthalic acid-n-dioctyl, phthalic acid-n-dibutyl, and polyvinyl alcohol may be added, and a surfactant and a surfactant may be added as necessary.
Furthermore, a metal oxide such as zirconium oxide may be added for the purpose of preventing deformation during firing. This has the effect of forming a passage for the gas generated when the organic binder burns to diffuse outside by delaying the sintering with the metal oxide.

[Example 1: Effect of particle size of copper powder in copper shaped fired body]
<Raw materials used>
The copper powder constituting the copper-containing plastic composition is pure copper, and is a copper mixture in which 50% by weight of a first copper powder having an average particle diameter of 2.5 μm and 50% by weight of a second copper powder having an average particle diameter of 10 μm are mixed. Powder was prepared. 90% by weight of this copper mixed powder, 1.20% by weight of methylcellulose as an organic binder, 0.30% by weight of sodium carboxymethylcellulose and 8.50% by weight of water were mixed thoroughly to form a clay, and the length was 50 mm. A test piece having a thickness of 10 mm and a thickness of 1.5 mm was prepared, dried at 80 ° C. × 30 min, the length was measured, and the shrinkage was determined. And it baked in air | atmosphere (oxidizing atmosphere) at 970 degreeC for 30 minutes using the electric furnace, and the surface of the obtained copper modeling baking body was polished and it was set as the test piece.
The bending strength is determined based on the three-point bending test method. Specifically, the center part of the test piece is bent with an indenter to a depth of 10 mm in speed (50 mm / min), and the load value at that time is measured. It calculated | required from the following formula | equation.
Bending strength = 3 Pl / 2bd ²
P: Load value,
l: Distance between supporting points b: Specimen width d: Specimen thickness In addition, as a reference example, instead of the copper mixed powder, a powder having the powder composition shown in Table 1 was formed in the same manner to make a specimen. Then, it was dried and fired under the same conditions, and the surface of the obtained copper molded fired body was polished and pickled to obtain a test piece. The two types of mixed powders in the table were equally divided (50% by weight each), and the three types of mixed powders were also equally divided (100/3% by weight each).

<result>

<Discussion>
In the copper-containing plastic compositions of Examples A to C containing a copper mixed powder having an average particle size of 10 μm or less, it was confirmed that a beautiful surface state would be obtained by subsequent polishing and pickling even after firing in the atmosphere. It was.
On the other hand, the copper-containing plastic compositions of Comparative Examples A and B to which copper powder having an average particle size of 40 μm is added have a low bending strength and are not suitable as a copper shaped fired body.
In addition, the copper-containing plastic composition of Example A containing 50% by weight of a first powder having an average particle size of 2.5 μm and 50% by weight of a second powder having an average particle size of 10.0 μm is the most. As a result, it was confirmed that the requirements defined in claims 1 and 3 are more desirable.
Incidentally, the copper-containing plastic compositions of Comparative Examples A and B had the above-mentioned results when fired in the atmosphere. However, when this copper-containing plastic composition was fired in an argon gas atmosphere, it could be used as a decorative article. A copper shaped fired body was obtained.

[Example 2: Evaluation of atmospheric firing conditions in a copper-silver shaped fired body]
<Raw materials used>
90 wt% of copper mixed powder [mixed weight composition: 50 wt% of first copper powder (pure copper) having an average particle diameter of 2.5 μm, 50 wt% of second copper powder (pure copper) having an average particle diameter of 10 μm], and an organic binder Methyl cellulose 1.20 wt%, carboxymethyl cellulose sodium 0.30 wt% and water 8.50 wt% were sufficiently mixed to obtain a clay-like copper-containing plastic composition.
On the other hand, the clay-like silver-containing plastic composition comprises 92 wt% of silver mixed powder [mixed weight composition: 50% by weight of first silver powder (pure silver) having an average particle diameter of 2.5 μm, and second silver powder having an average particle diameter of 20 μm ( 50% by weight of pure silver), 0.7 wt% starch as an organic binder, 0.8 wt% cellulose, and a water-soluble binder with the balance being water.

<Create test piece>
The silver-containing plastic composition and the copper-containing plastic composition are weighed so as to have a predetermined ratio, and are formed into a columnar shape having a width of about 3 mm with a finger to produce a silver bar and a copper bar, respectively. did.
The stretched silver bar and copper bar were put into an empty syringe without being twisted. When either one was long, the end was folded back and accommodated, and a columnar mixing rod-like body was ejected from the syringe.
As the syringe, a 2.0 ml syringe having a cylinder inner length of 8 cm, an inner diameter of 6 mm, and an extrusion port inner diameter of 1.4 mm (manufactured by Top Co., Ltd., medical device notification number 13B1 × 00085000023) was used.
The obtained mixing rod-shaped body was folded in half, and the two were twisted four times to form a columnar shape, which was then accommodated in the syringe, and the mixing rod-shaped body was ejected from the syringe.
This operation was repeated three times to obtain a mixed rod-like body in which the linear shape of the copper-containing plastic composition and the linear shape of the silver-containing plastic composition were intertwined in an intricate manner.
The obtained mixed rod-like body was injected onto a work table and wound into a plane spiral shape, and the upper surface thereof was flattened to form a plate shape, and the plate was pressed from the outside to form a flat plate shape.
Next, it was flattened with a roller (1.5 mm thickness), and a test piece (modeled body) of about 15 mm in length and 15 mm in width was created with a cutter.
After drying the obtained test piece, it was fired in the atmosphere under the conditions of 650 ° C. × 30 minutes to 850 ° C. × 5 minutes, and the firing time was shortened as the temperature became higher.
In addition, the atmospheric firing was performed by preheating the electric furnace to the above temperature, putting it in the electric furnace maintained at the set temperature, and maintaining a predetermined temperature and time.
After firing, it was quenched in water. The oxide film was removed well.
Next, it was immersed in a solid acid material for pickling (trade name: Pickling Compound, manufactured by GROBET FULE CO. OF AMERICA, INC., Main component: sodium hydrogen sulfate) to remove the oxide film on the surface of the sintered body.
Gloss came out by polishing the surface with a stainless steel brush if necessary.
As a result, a test piece having a marbled surface layer pattern of two types (two colors) of silver and copper was obtained.

The firing conditions were changed, and the ratio of the copper-containing plastic composition to the silver-containing plastic composition was changed within the range of copper 83 wt%: silver 17 wt% to copper 17 wt%: silver 83 wt%. 2 to Table 7 were obtained.
Test 1 is a baking condition of 650 ° C. × 30 minutes, and Table 2 shows the result.
Test 2 was baking conditions at 700 ° C. for 15 minutes, and Table 3 shows the results.
Test 3 is a baking condition at 750 ° C. × 10 minutes, and Table 4 shows the result.
Test 4 is a baking condition of 780 ° C. × 5 minutes, and Table 5 shows the result.
Test 5 is a baking condition of 800 ° C. × 5 minutes, and Table 6 shows the result.
Test 6 is a baking condition of 850 ° C. × 5 minutes, and Table 7 shows the result.
In Tables 2 to 7, “◯” and “Δ” in the evaluation column are usable evaluations, and “×” is an unusable evaluation. The “△” evaluation was an apparent problem that it was difficult to understand the marble pattern aesthetically, and it was not a problem for decorations with different designs, and had sufficient strength in use.

<result>

<Discussion>
In Test 1 (Table 2), Test 4 (Table 5), Test 5 (Table 6), and Test 6 (Table 7), regardless of the ratio of the copper-containing plastic composition and the silver-containing plastic composition, no good results were obtained. Only obtained.
In contrast, in Test 2 (Table 3) and Test 3 (Table 4), conversely, good results were obtained regardless of the ratio of the copper-containing plastic composition and the silver-containing plastic composition, and 700 ° C. × 15 It was confirmed that minutes to 750 ° C. × 10 minutes are conditions under which good atmospheric firing can be performed in firing this copper-silver mixed shaped body.
From this result, when a decorative object is formed as a composite shaped body by appropriately combining a copper-containing plastic composition and a silver-containing plastic composition, it can be air-fired at 700 to 750 ° C. for 10 to 15 minutes. In particular, it was possible to make an ornament with a design in which copper and silver were well-balanced.

  In addition, at the stage of making the above test piece (modeled body), it is flattened with a roller (1.5 mm thickness), and the circumference is made into a belt-like shape with a width of about 10 mm with a cutter. Fig. 1 shows a ring that was shaped into a model, dried, and then shaped with a file to form a model, which was fired in the air at 750 ° C for 10 minutes and pickled. It was a decorative metal product (ring) having a marble pattern.

[Example 3: Atmospheric firing of copper-silver shaped fired body]
Copper mixed powder 90% by weight [mixed weight composition: 47.5% copper powder (pure copper) with an average particle size of 2.5 μm, 47.5% copper powder (pure copper) with an average particle size of 10 μm, and 5.0% of zirconium oxide And 1.20% by weight methylcellulose as an organic binder, 0.15% by weight hydroxypropylmethylcellulose, 0.8% by weight starch, 0.10% by weight lignin and 7.75% by weight water are thoroughly mixed. A clay-like copper-containing plastic composition was made.
On the other hand, the clay-like silver-containing plastic composition was 92 wt% [mixed weight composition: first silver powder (pure silver) with an average particle size of 2.5 μm, 50 wt%, 50% by weight of second silver powder (pure silver) having an average particle size of 20 μm], 0.7% by weight starch as an organic binder, 0.8% by weight cellulose, and a water-soluble binder with the balance being water. .
In the same way as in Example 2 above, at the stage of making a shaped body, the surface is flattened with a roller, and the surroundings are cut with a cutter and shaped into a substantially plate shape. After drying, the shape is shaped with a file. The body. Separately from this, only with the silver-containing plastic composition, a ring with a base for fixing the shaped body is formed and dried, and this and the shaped body are integrated with a paste in which the silver-containing plastic composition is dissolved in water. Turned into.
This was fired in the atmosphere at 750 ° C. for 10 minutes and then pickled to obtain a decorative metal article (ring) having a marble pattern. This is shown in FIG. 2 as a drawing substitute photograph.

Claims (3)

After forming a copper shaped body with a copper-containing plastic composition containing at least one powder selected from copper and a copper alloy containing 50% by weight of copper and an organic binder, the copper shaped body is fired. A method for producing a copper sinter article for craft or decoration to obtain a copper shaped fired body,
The copper-containing plastic composition is mixed with 25 to 75% by weight of the first powder having an average particle size of 0.1 to 4 μm, and the balance of the second powder having an average particle size exceeding 4 μm and not more than 10 μm. A method for producing a copper-sintered article for crafts or decoration, characterized in that a copper-molded fired body is obtained by firing the copper shaped body in the atmosphere by using a powdered copper-containing plastic composition.   The method for producing a craft or decorative copper sintered article according to claim 1, wherein the copper shaped fired body obtained by air firing is pickled or polished.   One or more kinds of powders selected from copper and a copper alloy containing 50% by weight or more of copper, containing 25 to 75% by weight of the first powder having an average particle size of 0.1 to 4 μm, and the balance being the average particles A copper-containing plastic composition comprising a mixed powder composed of a second powder having a diameter exceeding 4 μm and not more than 10 μm, and an organic binder.

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