JP2976707B2 - Metal plastic composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal plastic composition suitable for use as a molding material for producing arts and crafts, metal tableware, jewelry and the like.

[0002]

2. Description of the Related Art Conventionally, when arts and crafts are manufactured, Au, Ag, Pt, Pd, Ir, O
Metals such as s, Ni, Cr, W, and Mo, and alloy materials containing these metals as main components are used, and the main processing method is casting, rolling, or the like, or hammering. Was something.

[0003] However, such a processing method not only requires large-scale facilities, but also has a problem that, depending on the metal, for example, Pt has a high melting point, so that molding by casting is difficult. is there.

[0004] Further, in the case of working methods such as hammering and rolling, there is a disadvantage that the shape of the shaping is restricted, or the time required for the shaping becomes long.

Accordingly, the present applicant has proposed a metal plastic composition in which a metal powder or an alloy powder is mixed with a water-soluble binder to form a clay state (see Japanese Patent Application Laid-Open No. Hei 4-26707).

[0006] The metal plastic composition according to the prior proposal has almost the same plasticity as ordinary clay, and has the advantage that various complicated shapes can be easily formed with a simple tool such as a fingertip or a spatula. Have.

[0007]

By the way, the above-mentioned noble metal plastic composition is extremely useful as a molding material, but the following items have been further demanded.

That is, the above-mentioned metal plastic composition has a problem that the volume after firing is reduced to about 40% to 60% as compared with the volume at the time of molding.

[0009]

SUMMARY OF THE INVENTION The present invention is to provide a metal plastic composition which can effectively solve the above-mentioned conventional problems, and more particularly, to a metal powder or its alloy powder and a water-soluble resin binder. To produce an intermediate mixture,
After drying and solidifying this intermediate mixture, it is immersed in water.
It is characterized in that a slurry is obtained by dissolving, then the slurry is dried to form a cake, and then a condensed powder obtained by grinding is kneaded with a binder. The binder includes a water-soluble resin binder, a thermoplastic resin binder, or a mixed binder thereof.

[0010]

The metal plastic composition according to the present invention forms an intermediate mixture by kneading metal powder or its alloy powder (hereinafter simply referred to as metal powder) with a water-soluble resin binder. In this state, the metal powder is uniformly dispersed in the binder. Thus, by drying the intermediate mixture, moisture in the binder is removed, and the metal powder is bound by the remainder of the binder. Then, the mixture of the dried metal powder and the binder is immersed in water and dissolved to form a slurry, and then dried to form a cake. This cake is an aggregate of granular materials in which a large number of metal powders having a binder attached to the surface are bonded. Then, by pulverizing the cake, the granules are finely pulverized to form condensed powder in which metal powders are combined in an irregular arrangement state.
Then, the metal plastic composition obtained by kneading the condensed powder and the binder becomes a molding material having excellent image forming properties, as in the previous proposal.

When the metal plastic composition using the thus obtained condensed powder is fired after molding, a metal article having almost no shrinkage can be obtained. This is because the condensed powder has an irregular arrangement in the newly mixed binder, and is sintered mutually while maintaining the irregular state at the time of sintering. This is considered to be due to the formation of a space in the space.

Here, the composition of the intermediate mixture will be described. The preferred composition is as follows: Metal powder: 50% by weight to 98.5% by weight Water-soluble resin binder: 1.5% by weight to 50% by weight Further, the preferred composition of the binder is as follows. However, the compounding ratio of this binder is shown assuming that the whole obtained mixture is 100% by weight. Cellulose-based water-soluble binder; 0.4% to 16.5% by weight Surfactant; 0.001% to 8.5% by weight Oils and fats or alcohols; 1.2% to 25% by weight Water and inevitable impurities The rest

Next, specific examples of the respective components and the reasons for limiting the mixing ratio will be described. (A) Metal Powder Spherical powder having an average particle diameter of 20 μm is used as the metal powder. Au, Ag, Pt, Ru, Rh, Pd, I
One or more selected from the group consisting of r, Os, Cu, Ni, Cr, W, Mo, and alloys thereof are used.

(B) Cellulose-based water-soluble binder The cellulose-based water-soluble binder is obtained by dissolving methylcellulose, ethylcellulose and the like in water.
The effect as a binder cannot be obtained, and if it exceeds the above range, the viscosity of the intermediate mixture becomes too large, which is not preferable.

(C) Surfactant The surfactant enhances the affinity between the metal powder and the cellulose-based water-soluble binder, and facilitates mixing of both. As the surfactant, an anionic surfactant such as an alkylbenzene sulfonate and a fatty acid soap is suitably used. If the compounding ratio is less than the above range, the effect is insufficient, and If it exceeds, the viscosity of the obtained intermediate mixture decreases and the fluidity increases, which is not preferable.

(D) Fats and oils or alcohols The fats and oils or alcohols impart lubricity to the intermediate mixture when added in a small amount. Examples of the fats and oils include higher organic acid esters such as ethylhexyl phthalate, di-N-octyl phthalate, and di-N-butyl phthalate.Also, as the alcohols,
For example, higher alcohols such as polyvinyl alcohol and higher polyhydric alcohols such as polyethylene glycol are preferably used. Further, if these compounding ratios are less than the above range, the effect is not obtained, and if more than the above range,
The resulting intermediate mixture is undesirably oily and slippery.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment.
First, methyl cellulose; 9% by weight, alkylbenzene sulfonate; 3% by weight, di-N-octyl phthalate;
Binder consisting of weight%, water and unavoidable impurities; balance is prepared, and 22% by weight of this binder and 78% by weight of spherical Ag powder having an average particle diameter of 20 μm are kneaded to form an intermediate mixture.

Next, this metal-plastic plastic is heated at room temperature for 1 hour.
Allow to dry for a day. Also, instead of this natural drying,
Forced drying by heating at about 80 ° C. for 2 hours may be used.

Next, the mixture of the metal powder dried as described above and the binder from which moisture has been removed is immersed in water for 6 hours, and if necessary, an external force such as stirring is applied to form a slurry. , Temperature; kept at 80 ° C for 24 hours and dried to obtain a cake. This cake is an aggregate of agglomerated particles having an average particle size of about 1 mm in which metal powder to which a binder from which moisture has been removed is attached to the surface is irregularly bound via the binder.

From this, the cake is pulverized using a ball mill or the like, so that the average particle size is 50 μm to 100 μm.
A μm condensed powder is obtained. This condensed powder has a shape in which metal powder is irregularly bound by a binder from which water has been removed, similarly to the agglomerated powder.

Using the condensed powder thus obtained,
By adjusting the mixing ratio, a metal plastic composition (Example 1) having the following mixing ratio was produced. Ag condensed powder; 82% by weight methyl cellulose; 1.8% by weight alkylbenzene sulfonate; 0.5% by weight di-N-octyl phthalate; 0.5% by weight water and inevitable impurities;

Then, after a rectangular parallelepiped of 3.4 cm × 3.0 cm × 0.9 cm is formed with a predetermined amount of the metal plastic composition, the resultant is fired at a temperature of 900 ° C. for 2 hours, and its shrinkage ratio (after firing) The volume / volume before firing) was 95%. As is clear from these results,
The metal plastic composition produced using the condensed powder of the present invention shows almost no shrinkage even after firing. This is because, when a metal plastic composition is produced using the condensed powder obtained as described above, a gap is formed between the metal powders constituting the condensed powder, and the metal powder is bonded in a bridge shape during firing. It is considered that a gap is formed between them.

In place of the water-soluble binder used in the first embodiment, a thermoplastic resin binder may be used, or a mixed binder composed of both binders may be used. . The composition and mixing ratio in that case are shown below.

[Case of Thermoplastic Resin Binder] (a) Thermoplastic Resin As the thermoplastic resin, an acrylic resin such as polymethyl methacrylate is used, and the shape of the obtained metal-plastic composition is well maintained. And, by a combination with a plasticizer described below, at a relatively low temperature to the metal plastic composition,
It imparts properties such as plasticity, self-adhesiveness, elongation, and crack prevention, and the compounding ratio is 2% by weight to 10% by weight. If the compounding ratio is lower than the lower limit, the above-mentioned properties cannot be sufficiently obtained.If the compounding ratio is higher than the upper limit, when the metal plastic composition is degreased and sintered, deformation, dripping, or foaming occurs. Etc. occur and it is not preferable,
It is set within the above range.

(B) Plasticizer The plasticizer, as described above, gives the metal plastic composition properties such as plasticity, self-adhesion, elongation, and crack prevention. One or two or more selected from phthalic acid-based compounds such as diethylhexyl acrylate and di-N-octyl phthalate, and alcohols such as polyethylene glycol, ethylene glycol, and glycerin are used. 10% by weight
It is. If the compounding ratio is below the lower limit, plasticity, elongation, and properties such as crack prevention cannot be sufficiently obtained, and if the compounding ratio exceeds the upper limit, self-adhesiveness decreases, and Since the air bubbles are drawn into the inside of the mold at the time of the molding, the strength of the mold is reduced.

(C) Dispersant The dispersant is preferably added, for example,
A surfactant such as sorbitan monooleate is used to enhance the mixing property between the metal powder or alloy powder and the binder. The total amount of the surfactant is 0.05 to 6% by weight together with inevitable impurities. Is added.

[In the case of a mixed binder of a thermoplastic resin binder and a water-soluble cellulose resin binder] (a) Thermoplastic resin The thermoplastic resin is an acrylic resin such as poly (methyl methacrylate), and has an oil component. By doing so, the resilience of the metal plastic composition is improved, the shape is maintained well, and properties such as plasticity, elongation, and crack prevention are imparted. If the compounding ratio (that is, the compounding ratio after the solvent component is removed) is less than 0.1% by weight, good resuscitation cannot be obtained, and properties such as elongation and crack prevention are insufficient. On the other hand, if it exceeds 5% by weight, the metal plastic composition becomes fluid when heated during sintering, and it becomes impossible to sinter the molded article into a desired shape. The mixing ratio is set to 0.1% by weight to 5% by weight.

(B) Water-soluble cellulose resin Methyl cellulose, ethyl cellulose and the like are used as the water-soluble cellulose resin. The water-soluble cellulose resin has the effect of imparting plasticity and shape retention properties to the metal plastic composition. In combination with the acrylic resin, it exhibits the effect of adjusting the properties of the metal plastic composition provided by the acrylic resin, such as shape retention, plasticity, elongation, and crack prevention, and solidifies when moisture is dried. This controls the degree of progress of drying and solidification of the metal plastic composition. If the compounding ratio is less than 0.1% by weight, the solidification is insufficient even when the moisture is dried, so that the required hardness and strength of the molded article cannot be obtained. Since the viscosity of the metal plastic composition is lowered and the plasticity is significantly lowered, the mixing ratio of the water-soluble cellulose resin is 0.1% by weight to 5% by weight.
Is set to

(C) Fats and oils These fats and oils are vegetable oils, animal oils, synthetic oils or
Higher organic acids such as phthalic acid and oleic acid, or higher organic compounds such as di-N-butyl phthalate, ethylhexyl phthalate and sorbitan monooleate, and higher alcohols such as polyethylene glycol are used. This is for adjusting the plasticity of the resin and suppressing the adhesion to the hand and the molding jig during the molding. If the compounding ratio is less than 0.1% by weight, the effect cannot be obtained, and if the compounding ratio exceeds 5% by weight, the elongation property is remarkably deteriorated.
It is set to 0.1% by weight to 5% by weight.

(D) Lower alcohols The lower alcohols are ethylene glycol, glycerin and the like, which are used to suppress cracks and the like during molding of the obtained metal plastic composition. Depending on the required characteristics, it is not always necessary to mix them. If the compounding ratio exceeds 5% by weight, the viscosity of the metal plastic composition is reduced and the image quality is significantly reduced. Therefore, the compounding ratio is set to 5% by weight or less.

(E) Surfactant As this surfactant, sodium lauryl sulfate or the like is used, and the kneading and mixing of the compound during the production of the metal plastic composition are facilitated, and the time required for the mixing is shortened. It is not always necessary to mix depending on the manufacturing conditions. If the content exceeds 0.5% by weight, the above-mentioned effect is not changed. Therefore, the amount of the surfactant is set to 0.5% by weight or less.

Next, a metal plastic composition using a thermoplastic resin binder (Example 2) and a metal plastic composition using a binder obtained by mixing both of them (Example 3) have the following composition. The ratio produced a metal plastic composition.

Example 2 Ethanol was used in ethanol so that the mixing ratio after drying was 4% by weight, di-N-butyl phthalate: 4% by weight, and sorbitan monooleate: 2% by weight. After stirring and mixing at room temperature, Ag-condensed powder having an average particle diameter of 20 μm was stirred and mixed into the solution so that the blending ratio after evaporation and drying was 90% by weight. 24 at 40 ° C
It was air-dried by holding for a time to obtain a metal-plastic composition.

Example 3 The mixing ratio after evaporation and drying was as follows: polymethyl methacrylate: 2.7% by weight, di-N-butyl phthalate: 2.1% by weight, and sorbitan monooleate;
These are stirred and mixed at room temperature in ethanol so as to have a concentration of 0.5% by weight.
Ag powder was also stirred and mixed so that the compounding ratio after evaporation and drying was 84.9% by weight, and then the mixed solution was spread on a vat and kept at a temperature of 40 ° C. for 24 hours to be naturally dried. This is methylcellulose; 1.0
% By weight, sodium lauryl sulfate; 0.02, balance; water and unavoidable impurities were kneaded with a jelly-like composition obtained by stirring and mixing to obtain a metal-plastic composition.

Then, in each of these examples, after forming in the same manner as in Example 1, firing was performed at 900 ° C. for 2 hours, and the shrinkage ratio (volume after firing / volume before firing) was obtained.
As a result, it was 93% in Example 2 and 92% in Example 3.

As described above, the metal plastic composition of the present invention can provide a metal article which hardly shrinks after firing.

[0037]

As described above, the metal-plastic composition according to the present invention produces an intermediate mixture by kneading a metal powder or its alloy powder and a water-soluble resin binder, and then drying and solidifying the intermediate mixture. After that, a slurry is obtained by immersing and dissolving in water, and then the slurry is dried to form a cake, and then a condensed powder obtained by grinding is kneaded with a binder. By doing so, the shrinkage after firing can be greatly reduced, and the difference in appearance between the shape at the time of molding and the obtained metal article can be significantly reduced. Therefore, the quality of the metal article as a molding material can be significantly improved.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B22F 3/02

Claims (2)

(57) [Claims] 1. An intermediate mixture is produced by kneading a metal powder or its alloy powder and a water-soluble resin binder, and after drying and solidifying the intermediate mixture, it is immersed and dissolved in water to form a slurry, A metal plastic composition obtained by kneading a binder with a condensed powder obtained by drying the slurry to form a cake and then pulverizing the cake. 2. The metal-plastic composition according to claim 1, wherein the binder is a water-soluble resin binder and / or a thermoplastic resin binder.