JPH072568A - Alumina plastic material - Google Patents

Abstract

PURPOSE:To provide an alumina material excellent in plasticity. CONSTITUTION:This alumina plastic material is prepared by blending and kneading a plate-shaped powdery alumina having <=1.0mum particle size and <=0.1mum thickness and an organic water retention agent with water. As the organic water retention agent, methyl cellulose, polyvinyl alcohol, carboxymethyl cellulose, polyethylene glycol, etc., are preferably used. This material is excellent in plasticity and, therefore, can be molded without requiring a large amount of a binder. Accordingly, a dense molding having stable properties can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alumina powder having plasticity, and more specifically, it is a fine plate-like particle having a uniform particle size, and in particular, an alumina plastic material which exhibits plasticity when kneaded with water. Regarding

[0002]

2. Description of the Related Art Alumina powder, which is a typical raw material for fine ceramics, is widely used as a material excellent in heat resistance, electrical insulation, mechanical strength and the like in structural parts, electronic parts and other fields. . However, in the molding of alumina powder, when molding is carried out by utilizing plasticity, the plasticity like clay cannot be exhibited by simply kneading the powder with water. Therefore, in order to obtain the plasticity required for molding, plastic molding is performed by adding various molding aids such as plastic viscosity and a large amount of organic binder. However, when a large amount of these molding aids is used, there arises a problem of necessity of degreasing treatment in a later step, reduction of molding density, and nonuniformity of the sintered body.

On the other hand, the kaolinite clay, which has been conventionally used as a raw material for pottery, has a great plasticity by itself. The reason for this plasticity development is explained by Mr. Motoki and Mr. Okuda (ceramic raw materials Vol. 4, 99
-106, 1952, Clay Science, 8, 14-23, 19
68), a. The particles are fine and close to the colloidal region, b. Its shape is flat, c. It is mentioned that the water film on the surface of particles (by hydrogen bond) is thicker than water. However, it is also pointed out that there are still many unsolved problems regarding the essence of the cause of this plasticity development.

[0004]

In view of the above-mentioned conventional techniques, the alumina particles used in the production of fine ceramics have a large plasticity comparable to that of kaolinite clay, and an attempt is made to improve the molding density as well as the excellent moldability. It is a thing.

[0005]

According to the present invention, the particle shape is plate-like, the particle size is 1.0 μm or less, and the thickness is 0.1 μm.
It is an alumina-based plastic material characterized by kneading an alumina powder having a particle size of m or less with an organic water-retaining material and water.

In all cases, the basic shape of the alumina particles is preferably plate-like, and it is necessary that the size is 1.0 μm or less and the thickness is 0.1 μm or less. Particles that are not plate-shaped or have a size larger than these values lead to a decrease in plasticity. In particular, it is preferable that the particle shape is a hexagonal plate shape for the closest packing of the particles.

The organic water retention agent is not particularly limited as long as it gives the kneaded material water retention and fluidity. For example, it ranges from natural products such as tragacanth gum to synthetic polymers. The main ones are polyvinyl alcohol, polyvinyl butyrate, polyethylene glycol, methyl cellulose, carboxymethyl cellulose,
It is at least one of ethylene cellulose and hydroxypropyl cellulose. In particular, methyl cellulose, polyvinyl alcohol, carboxymethyl cellulose, and polyethylene glycol are preferable from the viewpoint of water retention or fluidity.

By containing a small amount of these organic water retention agents, the alumina particles having the above-mentioned shape can be plastically molded like clay by the presence of water. As a method for obtaining the plate-like particles of alumina forming the basis of the present invention, for example, a method of producing by adding a mineralizing agent such as aluminum fluoride in the calcination step, adding aluminum hydroxide to a sodium aluminate solution There are methods such as hydrolyzing to obtain fine plate-like aluminum hydroxide and calcining it to produce hydrothermal synthesis method. In the present invention, the method for obtaining plate-like particles is particularly limited. do not do. In the present invention, the particles obtained may be in the form of fine plates. The alumina particles thus obtained are fine plate-like particles, and when this powder is kneaded with water, it exhibits plasticity not found in conventional alumina particles, but by holding an organic water retention agent on its surface, It develops plasticity comparable to clay.

[0009]

[Examples] Aluminum hydroxide prepared by the Bayer method was subjected to particle size adjustment with a ball mill to a central diameter of 0.7 μm to prepare a slurry with 10 g of a predetermined amount of pure water, and the slurry was filled in a small autoclave 100 cc at a temperature of 600 Hydrothermal treatment was carried out for 2 hours at a temperature of 200 ° C. and a pressure of 200 kg / cm ² . The treated product is washed with water, filtered and dried to obtain a sample. The obtained alumina powder was hexagonal plate-like particles having a uniform particle size and a central diameter of 1.0 μm. An electron micrograph of the sample is shown in FIG. To 100 g of the alumina powder, 3 g of polyethylene glycol and water were added and kneaded to obtain a plastic material of the present invention.

The plasticity of this inventive plastic material and the commercially available kaolinite clay were evaluated. As a plasticity evaluation method, Pfe indicating the water content and the plastic deformation amount in the kneaded material is displayed.
According to the fferKorn method, the water content at the time of drying at 100 ° C. of the sample at a deformation ratio of 3.3 was calculated as the plastic water content PI,
Moisture that escapes from drying at 100 ° C to 100 ° C (water considered to be bound water) is evaluated by the water retention rate WR, and the ratio of the water retention rate and the plastic water content shown in the following formula is evaluated by the plastic characteristic value CV. (Ceramics Association Magazine, 92, 77-82, 1984) CV = (WR / PI) × 100

The results were as follows: PI WR CV Commercial kaolinite 38.64 0.589 1.523 Plastic material of the present invention 33.08 0.623 1.884 As is apparent from the above evaluation results, the plastic material of the present invention is comparable to commercial kaolinite clay. It was confirmed that the resin has a plastic property value that

[0012]

INDUSTRIAL APPLICABILITY According to the present invention, an alumina-based plastic material having a plasticity comparable to that of a commercially available kaolinite clay can be obtained, and a large amount of binder (molding auxiliary agent) can be added as in the conventional plastic molding method. Since it is not necessary, it is possible to obtain a compact and dense molded body. Therefore, it can be widely applied to structural parts, electronic parts and other fields as a material excellent in heat resistance, electrical insulation, mechanical strength and the like.

[Brief description of drawings]

FIG. 1 is an electron micrograph showing the particle structure of basic alumina particles of the present invention.

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[Procedure amendment]

[Submission date] October 19, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document name] Statement

Title of invention Alumina-based plastic material

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alumina powder having plasticity, and more specifically, it is a fine plate-like particle having a uniform particle size, and in particular, an alumina plastic material which exhibits plasticity when kneaded with water. Regarding

[0002]

2. Description of the Related Art Alumina powder, which is a typical raw material for fine ceramics, is widely used as a material excellent in heat resistance, electrical insulation, mechanical strength and the like in structural parts, electronic parts and other fields. . However, in the molding of alumina powder, when molding is carried out by utilizing plasticity, the plasticity like clay cannot be exhibited by simply kneading the powder with water. Therefore, in order to obtain the plasticity required for molding, plastic molding is performed by adding various molding aids such as plastic viscosity and a large amount of organic binder. However, when a large amount of these molding aids is used, there arises a problem of necessity of degreasing treatment in a later step, reduction of molding density, and nonuniformity of the sintered body.

On the other hand, the kaolinite clay, which has been conventionally used as a raw material for pottery, has a great plasticity by itself. The reason for this plasticity development is explained by Mr. Motoki and Mr. Okuda (ceramic raw materials Vol. 4, 99
-106, 1952, Clay Science, 8, 14-23, 19
68), a. The particles are fine and close to the colloidal region, b. Its shape is flat, c. It is mentioned that the water film on the surface of particles (by hydrogen bond) is thicker than water. However, it is also pointed out that there are still many unsolved problems regarding the essence of the cause of this plasticity development.

[0004]

In view of the above-mentioned conventional techniques, the alumina particles used in the production of fine ceramics have a large plasticity comparable to that of kaolinite clay, and an attempt is made to improve the molding density as well as the excellent moldability. It is a thing.

[0005]

According to the present invention, the particle shape is plate-like, the particle size is 1.0 μm or less, and the thickness is 0.1 μm.
It is an alumina-based plastic material characterized by kneading an alumina powder having a particle size of m or less with an organic water-retaining material and water.

In all cases, the basic shape of the alumina particles is preferably plate-like, and it is necessary that the size is 1.0 μm or less and the thickness is 0.1 μm or less. Particles that are not plate-shaped or have a size larger than these values lead to a decrease in plasticity. In particular, it is preferable that the particle shape is a hexagonal plate shape for the closest packing of the particles.

The organic water retention agent is not particularly limited as long as it gives the kneaded material water retention and fluidity. For example, it ranges from natural products such as tragacanth gum to synthetic polymers. The main ones are polyvinyl alcohol, polyvinyl butyrate, polyethylene glycol, methyl cellulose, carboxymethyl cellulose,
It is at least one of ethylene cellulose and hydroxypropyl cellulose. In particular, methyl cellulose, polyvinyl alcohol, carboxymethyl cellulose, and polyethylene glycol are preferable from the viewpoint of water retention or fluidity.

By containing a small amount of these organic water retention agents, the alumina particles having the above-mentioned shape can be plastically molded like clay by the presence of water. As a method for obtaining the plate-like particles of alumina forming the basis of the present invention, for example, a method of producing by adding a mineralizing agent such as aluminum fluoride in the calcination step, adding aluminum hydroxide to a sodium aluminate solution There are methods such as hydrolyzing to obtain fine plate-like aluminum hydroxide and calcining it to produce hydrothermal synthesis method. In the present invention, the method for obtaining plate-like particles is particularly limited. do not do. In the present invention, the particles obtained may be in the form of fine plates. The alumina particles thus obtained are fine plate-like particles, and when this powder is kneaded with water, it exhibits plasticity not found in conventional alumina particles, but by holding an organic water retention agent on its surface, It develops plasticity comparable to clay.

[0009]

[Examples] Aluminum hydroxide prepared by the Bayer method was subjected to particle size adjustment with a ball mill to a central diameter of 0.7 μm to prepare a slurry with 10 g of a predetermined amount of pure water, and the slurry was filled in a small autoclave 100 cc at a temperature of 600 Hydrothermal treatment was carried out for 2 hours at a temperature of 200 ° C. and a pressure of 200 kg / cm ² . The treated product is washed with water, filtered and dried to obtain a sample. The obtained alumina powder was hexagonal plate-like particles having a uniform particle size and a central diameter of 1.0 μm. An electron micrograph of the sample is shown in FIG. To 100 g of the alumina powder, 3 g of polyethylene glycol and water were added and kneaded to obtain a plastic material of the present invention.

The plasticity of this inventive plastic material and the commercially available kaolinite clay were evaluated. As a plasticity evaluation method, Pfe indicating the water content and the plastic deformation amount in the kneaded material is displayed.
According to the fferKorn method, the water content at the time of drying at 100 ° C. of the sample at a deformation ratio of 3.3 was calculated as the plastic water content PI,
Moisture that escapes from drying at 100 ° C to 100 ° C (water considered to be bound water) is evaluated by the water retention rate WR, and the ratio of the water retention rate and the plastic water content shown in the following formula is evaluated by the plastic characteristic value CV. (Ceramics Association Journal, 92, 77-82, 1984) CV = (WR / PI) × 100 The results were as follows.

PI WR CV Commercial kaolinite 38.64 0.589 1.523 Plastic material of the present invention 33.08 0.623 1.884 As is apparent from the above evaluation results, the plastic material of the present invention is a commercially available kaolinite. It was confirmed that it had a plastic property value comparable to that of clay.

[0012]

INDUSTRIAL APPLICABILITY According to the present invention, an alumina-based plastic material having a plasticity comparable to that of a commercially available kaolinite clay can be obtained, and a large amount of binder (molding auxiliary agent) can be added as in the conventional plastic molding method. Since it is not necessary, it is possible to obtain a compact and dense molded body. Therefore, it can be widely applied to structural parts, electronic parts and other fields as a material excellent in heat resistance, electrical insulation, mechanical strength and the like.

[Brief description of drawings]

FIG. 1 is an electron micrograph showing the particle structure of basic alumina particles of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiichi Oda 1-70 Heiwagaoka, Meito-ku, Nagoya, Aichi Prefecture (72) Inventor Yushi Fukuda 403-3 Chushin, Kurobe-shi, Toyama

Claims (4)

[Claims] 1. The particle shape is plate-like, and the particle size is 1.
An alumina-based plastic material, which is obtained by kneading an alumina powder having a thickness of 0 μm or less and a thickness of 0.1 μm or less with an organic water retention material and water. 2. The particle shape is hexagonal plate-shaped particles.
The alumina-based plastic material described. 3. The organic water retention material is polyvinyl alcohol,
The alumina plastic material according to claim 1, which is at least one kind of polyvinyl butyral, polyethylene glycol, methyl cellulose, carboxymethyl cellulose, ethylene cellulose, and hydroxypropyl cellulose. 4. The alumina plastic material according to claim 3, wherein the organic water retention material is at least one of methyl cellulose, polyvinyl alcohol, carboxymethyl cellulose, and polyethylene glycol.