JPH09255434A - Production of ceramic molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a ceramic molded product by molding a powdery material and subsequently sintering the molded product, enabling to mold the powdery material even with a low pressure. SOLUTION: This method for producing a ceramic molded product comprises coating ceramic powder 12, 12a with a methyl cellulose aqueous solution 13, 13a comprising a water-soluble methyl cellulose dissolved in water, drying the coated ceramic powder, molding the dried water-containing methyl cellulose powder at a temperature for gelling the water-containing methyl cellulose, and subsequently sintering the molded product.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ceramic molded product.

[0002]

2. Description of the Related Art Conventionally, ceramic molded products have been used as substrates for mounting electronic elements. As a method for producing this ceramic molded product, a ceramic powder such as alumina is mixed with a solvent and a binder such as methylcellulose to knead to form a clay or slurry, and in the case of a clay, an extrusion molding machine or the like is used. After that, it is dried to form a green sheet, and in the case of a slurry, the green sheet is formed by using a doctor blade or the like, then dried to form a green sheet, and then baked.

In recent years, ceramic molded products have been used not only in a flat shape but also in various shapes. When trying to manufacture this non-planar ceramic molded product, in the case of using the soil, it is difficult for the soil to penetrate deep inside the molding die, and there is a gap between the molding die and the soil. However, there is a problem that it is difficult to obtain the shape to be formed, and the method using a slurry has a problem that the dimension shrinkage due to drying of the solvent is large and it is not suitable for manufacturing a non-planar ceramic molded product.

Therefore, by filling the molding die with the ceramic powder without forming a clay or a slurry,
A method of manufacturing by making ceramic powder penetrate into the inner part of a molding die is being studied. As the powder in that case, a ceramic powder whose surface is coated with polyvinyl alcohol or the like is used so that the powder adheres when molded. However, when the powder whose ceramic powder is coated with this polyvinyl alcohol is used, the molding pressure is 1
Unless the pressure is raised to about 0 MPa, it is difficult for the powder particles to adhere to each other, so a facility capable of generating a large pressure was required. Therefore, there is a demand for a method for producing a ceramic molded product that can be molded even at a low pressure.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its object is to manufacture a ceramic molded product manufactured by powder molding and then firing. Another object of the present invention is to provide a method for producing a ceramic molded product, which is a method and can be molded even at a low pressure.

[0006]

According to a first aspect of the present invention, there is provided a method for producing a ceramic molded article, which comprises coating a ceramic powder with an aqueous methylcellulose solution prepared by dissolving water-soluble methylcellulose in water, and then drying the water. The method is characterized in that a hydrated methylcellulose-coated powder is formed, and then the hydrated methylcellulose-coated powder is powder-molded at a temperature at which the hydrated methylcellulose gels and then fired.

The method for producing a ceramic molded article according to claim 2 of the present invention is the method for producing a ceramic molded article according to claim 1, which comprises coating the ceramic powder with a methylcellulose aqueous solution and then drying the water. The method is characterized in that a method of spraying an air-dispersed ceramic powder with an aqueous solution of methylcellulose to bring it into contact with the powder to coat it, and then vaporizing water during the fall to dry it.

The method for producing a ceramic molded article according to claim 3 of the present invention is the method for producing a ceramic molded article according to claim 1 or 2, wherein the aqueous solution of methylcellulose 1 is used.
Water-soluble methyl cellulose is added in an amount of 0.1 to 2 in 100 parts by weight.
It is characterized by containing parts by weight.

According to the present invention, the hydrated methylcellulose of the hydrated methylcellulose-coated powder is gelled and adhered by heating during molding, so that the powder particles are bonded to each other and molding can be carried out even at a low pressure.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing a ceramic molded article according to the present invention comprises the steps of coating a ceramic powder with an aqueous solution of methylcellulose in which water-soluble methylcellulose is dissolved, and then drying the water to give a hydrous methylcellulose-coated powder. After being formed, the hydrated methyl cellulose-coated powder is formed by powder molding at a temperature at which the hydrated methyl cellulose gels and then firing.

The methyl cellulose used in the present invention is limited to water-soluble methyl cellulose. A liquid obtained by dissolving this water-soluble methylcellulose in water, when it has an appropriate amount of water, gels when heated and produces the effect of an adhesive. Further, when it is fired, it is burned or evaporated to be vaporized and removed, so that it does not remain in the ceramic molded product and a high-purity ceramic molded product is obtained.

As a ratio of dissolving this methylcellulose in water, it is preferable that 0.1 to 2 parts by weight of methylcellulose be contained in 100 parts by weight of the aqueous solution. If the amount is less than 0.1 parts by weight, a large amount of methylcellulose aqueous solution is required to cover the ceramic powder, and the amount of water to be dried increases, resulting in a large drying facility. When the viscosity of the aqueous solution becomes high, the amount of methylcellulose coating the ceramic powder partially increases, and when this is fired to produce a ceramic molded product, traces of hydrated methylcellulose remain There is a problem.

After the water-soluble methyl cellulose is dissolved in water, the solution is filtered with a filter of about 10 μm or less to remove the undissolved portion of the water-soluble methyl cellulose before use, and then fired to obtain a ceramic molded article. When it is produced, traces of hydrated methyl cellulose are less likely to remain, which is preferable.

As the ceramic powder used in the present invention,
The powder is not particularly limited, and examples thereof include powders of alumina, aluminum nitride, silicon nitride, ferrite, barium titanate, and the like. The size of the powder is not particularly limited, but if the average particle size is 0.3 to 2.5 μm, even if a complicated shape is molded, the ceramic powder reaches the inner part of the molding die. It is preferable because it can penetrate the body.

As a method of drying the water content after coating the ceramic powder with the methylcellulose aqueous solution, the air-dispersed ceramic powder is sprayed with the methylcellulose aqueous solution so as to be in contact therewith, and then the water content is vaporized during the fall. And the like, and a method of mixing the aqueous solution of methylcellulose and the ceramic powder and then spraying to vaporize the water during the fall to dry. To the air-dispersed ceramic powder, a method of spraying an aqueous solution of methylcellulose to contact and coating, and then evaporating water during the fall to dry the ceramic powder when air-dispersing,
Since the ceramic powder does not easily agglomerate and a small hydrous methylcellulose-coated powder can be obtained, even when molding a complicated shape, ensure that the ceramic powder penetrates deep inside the molding die. Is preferred and is preferable.

After spraying and contacting the air-dispersed ceramic powder with an aqueous solution of methylcellulose,
As a method of vaporizing and drying water while falling, for example, as shown in FIG. 1, a powder injection port 14 for injecting ceramic powder 12, 12a and a methylcellulose aqueous solution 1 are used.
An apparatus having a solution injection port 15 for spraying 3, 13a is used. Then, the ceramic powder 12 is pressurized by the air 11 and jetted upward from the powder jet port 14 to be dispersed in the air. Further, the methyl cellulose aqueous solution 13 is sprayed upward from the solution injection port 15 and dispersed in the air. Then, the ceramic powder 12a dispersed in the apparatus and the methylcellulose aqueous solution 13a are brought into contact with each other when dropped, and the ceramic powder 12a is coated with the methylcellulose aqueous solution 13a. Since the aqueous solution of methyl cellulose 13a has a large amount of water and a low viscosity, it diffuses on the surface of the ceramic powder 12a and covers almost the entire surface of the ceramic powder 12a. It should be noted that the term "covering" in the present invention is not limited to covering the entire surface of the ceramic powder 12a, and the effect of the present invention is obtained even when a part of the surface is covered. Can be played. And an aqueous solution of methylcellulose 13a covering the surface of the ceramic powder 12a
The water evaporates and dries while falling. Since the surface area of the methyl cellulose aqueous solution 13a covering the surface of the ceramic powder 12a is large, the water content is easily evaporated, and the methyl cellulose aqueous solution 13a can be easily dried.

The drying in the present invention does not completely remove water, but it is important that the methyl cellulose contains a little water as long as it is dried to a powder. The moisture contained in the methylcellulose gels and adheres when the methylcellulose-coated powder is heated and molded, so that molding can be performed even at a low pressure.

The liquid temperature of the sprayed methyl cellulose aqueous solution 13 is preferably about 40 to 50 ° C.
At this temperature, the viscosity of the aqueous solution of methylcellulose 13 is low, and it is easy to diffuse on the surface of the ceramic powder 12a, so that the ratio of the surface covered with the ceramic powder 12a can be increased.

Then, the methylcellulose-coated powder is
Powder molding is performed at a temperature at which methyl cellulose gels. The hydrated methyl cellulose gradually decreases in viscosity when heated, and rapidly increases in viscosity at a specific temperature due to the molecular structure of methyl cellulose at about 50 to 90 ° C. and gels. Due to the adhesive force of this gelled methyl cellulose, molding is possible even at low pressure.

Next, firing is performed to produce a ceramic molded product. As a firing condition, firing is performed at a temperature suitable for the ceramic powder used.

Before firing, a firing aid or the like may be mixed in advance with the ceramic powder. Examples of the firing aid include talc and calcia. In addition, it is preferable to mix these firing aids and the like with the ceramic powder before coating the ceramic powder with the aqueous methylcellulose solution.

[0022]

【Example】

(Example 1) Water-soluble methyl cellulose [Matsumoto Yushi Co., Ltd.,
Brand name Marpo Rose] 0.5 part by weight was dissolved in 100 parts by weight of water to obtain an aqueous methylcellulose solution.

Next, to the air-dispersed ceramic powder,
After spraying and contacting the methyl cellulose aqueous solution to coat, using a device that evaporates water during the fall to dry it,
Alumina powder having an average particle size of 0.4 μm, manufactured by Sumitomo Chemical Co., Ltd., trade name AES-11
C] and then dried to obtain hydrous methylcellulose-coated powder.

Next, the hydrous methyl cellulose-coated powder was put into a mold for powder molding, and the pressure was 2.9 MPa.
Powder molding was performed at a temperature of 70 ° C. for 2 minutes. When taken out from the mold, the powder adhered and the desired shape was obtained.
It was fired at 600 ° C. to obtain a ceramic molded product.

(Example 2) 1 aqueous solution of methylcellulose
Unfiltered 10 μm through a 0 μm filter
A ceramic molded article was obtained in the same manner as in Example 1 except that the above-mentioned methyl cellulose was removed and then alumina powder was coated. Also in this case, when taken out from the mold, the powder adhered to obtain a desired shape.

Comparative Example 1 1 part by weight of polyvinyl alcohol was mixed with 100 parts by weight of water and dissolved to obtain an aqueous solution of polyvinyl alcohol, which was sprayed and coated with alumina powder. Powder molding was performed in the same manner as in Example 1.

When the powder was taken out from the mold, the adhesion of the powder was insufficient and a part of the powder was decomposed to give a desired shape.

(Comparative Example 2) Powder molding was carried out in the same manner as in Comparative Example 1 except that the powder molding was carried out at a pressure of 9.8 MPa.
Since the powder was adhered to the obtained molded product to obtain a desired shape, it was fired in the same manner as in Example 1 to obtain a ceramic molded product.

(Comparison of Results) Compared with Comparative Example 1, the adhesion of the powder was sufficient in each Example, and even if the molding was performed at a low molding pressure, polyvinyl alcohol was used at a high pressure for comparison. It was confirmed that molding could be performed in the same manner as in Example 2.

[0030]

EFFECTS OF THE INVENTION According to the method for producing a ceramic molded article according to the present invention, since the hydrated methylcellulose of the hydrated methylcellulose-coated powder is gelled and bonded by heating during molding, the powder particles are bonded to each other, resulting in low pressure. A ceramic molded product can also be obtained by molding with.

According to the method for producing a ceramic molded article according to claim 2 of the present invention, in addition to the above effects, the ceramic powder does not easily agglomerate when producing a hydrous methylcellulose-coated powder, and a small hydrous methylcellulose-coated powder is obtained. Therefore, even when a complicated shape is molded, the ceramic powder can be surely intruded into the inner deep part of the molding die.

[Brief description of drawings]

FIG. 1 relates to a method for manufacturing a ceramic molded article according to the present invention,
It is explanatory drawing which shows one Embodiment of the apparatus which evaporates and dries water | moisture content during a fall, after spraying and coating the air-dispersed ceramic powder with the methylcellulose aqueous solution.

[Explanation of symbols]

 11 Air 12,12a Ceramic powder 13,13a Methylcellulose aqueous solution 14 Powder injection port 15 Solution injection port

Claims (3)

[Claims] 1. A ceramic powder is coated with an aqueous solution of methylcellulose in which water-soluble methylcellulose is dissolved, and then water is dried to form a hydrated methylcellulose-coated powder. A method for producing a ceramic molded article, which comprises firing at a temperature at which the gelling occurs and then firing. 2. A method of coating ceramic powder with an aqueous solution of methylcellulose and then drying the water is a method of spraying an aqueous dispersion of methylcellulose onto and contacting the ceramic powder with air to coat the powder, and then vaporizing the water during falling. The method for producing a ceramic molded article according to claim 1, wherein the method is a method of drying by drying. 3. The method for producing a ceramic molded article according to claim 1, wherein 0.1 to 2 parts by weight of water-soluble methyl cellulose is contained in 100 parts by weight of the aqueous methyl cellulose solution.