JPS6210959B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ceramic porous body. As described in Japanese Patent Publication No. 52-5328, an inorganic fine powder, which is a raw material for a porous ceramic body, is suspended in an aqueous dispersion of a fibrous combustible material such as pulp, and then the inorganic fine powder is suspended in an aqueous dispersion of a fibrous combustible material such as pulp. is adsorbed and aggregated on the surface of the combustible material using an amphoteric surfactant, and a sheet-like or plate-like molded product is obtained by a wet papermaking method,
There is a method for producing ceramics by firing the molded product, but the present invention improves this method and is a method for manufacturing porous ceramic bodies suitable for uses such as sound absorbing plates and heat insulating materials.

Conventionally, in order to obtain this type of ceramic porous body or foam, known as the kneading method, an inorganic fine powder raw material and an organic blowing agent or a natural inorganic blowing agent such as expandable shale, vermiculite, and olivine are used as a blowing agent. Knead and shape,
There is a method to obtain a foam after firing, and another method is to knead and mold inorganic fine powder raw materials with flammable impurities such as plastic beads and wood chips and a resin binder, and then burn out the combustible materials to obtain a foam. be.

However, with these methods, it is difficult to knead more than 30% by weight of blowing agents and combustibles, and even with lower amounts, as the proportion of blowing agents and combustibles increases, inorganic Deformation during firing due to non-uniform distribution of fine powder cannot be avoided, and there are also problems such as non-uniform distribution of air bubbles after firing. Furthermore, the method disclosed in Japanese Patent Publication No. 52-5328 mentioned above has the advantage of being able to obtain molded products with a large area, but since fibrous pulp is used as the combustible material, the shape of the void becomes layered. However, the disadvantage was that the ceramic was likely to peel off in layers, making it difficult to obtain a ceramic with a high porosity.

The present invention is a method for producing a ceramic porous body that does not cause the above-mentioned drawbacks, and specifically, it is a method for producing a ceramic porous body that does not have the above-mentioned drawbacks. Adding a flocculant to an aqueous suspension containing 70 to 10% by weight of a combustible substance to adsorb the inorganic fine powder on the surface of the combustible substance,
This is a method for producing a ceramic porous body in which the material is formed into a sheet or plate shape by an agglomeration wet papermaking method, dried, and then flammable substances are burned and scattered in an oxidizing atmosphere, followed by sintering the inorganic fine powder.

To further explain the details of the present invention, the present invention provides 70 to 10% by weight of granular, flaky, or powdery combustible material dispersed in a suspension on the surface itself.
~90% by weight of sinterable inorganic fine powder is adsorbed and agglomerated using a flocculant, and a normal papermaking method is used to obtain a molded product from the suspension, so the inorganic fine powder required for unfired molded products is obtained. A uniformly dispersed distribution state of combustible materials and combustible materials has already been achieved at the papermaking stage. When drying from the suspension, it is possible to obtain an unfired product containing a wide range of combustible substances in the range of 70 to 10% by weight. A uniform unfired product can be obtained according to the uniform distribution state of the combustible material that is forcibly dispersed, and this can be fired to produce a wide range of bulk specific gravity in which porous cells are uniformly distributed. A porous ceramic body having the following properties can be manufactured.

The inorganic fine powder used in the present invention is small enough to be sufficiently dispersed in stirred water, and it is usually appropriate to select a fine powder with a particle size that can pass through a 200-mesh sieve. Metal compounds that are insoluble in water and can coexist with metals, metal oxides, silicates, borates, phosphates, or other sintering materials to form sintered bodies. It goes without saying that any material can be used, and even naturally occurring inorganic materials for ceramics can be used. In the present invention, since the combustible material is burnt out in the initial stage of sintering, the temperature conditions and atmosphere for subsequent sintering can be arbitrarily determined, and therefore almost all ceramic raw materials can be used. Furthermore, if necessary, in addition to the above-mentioned inorganic fine powder, ceramic fibers such as silica-alumina-based ceramic fibers and alumina-based ceramic fibers for the purpose of reinforcing the ceramic porous body may be used in combination with a flammable substance.

This does not affect the porous cells formed by burning off the combustible material and their distribution, and the ceramic fibers exist in the fired product in a state in which the fibers are entangled with each other.

The effect of this intertwining of fibers can reinforce the ceramic porous body.

The ceramic fiber that can be used here is one that does not melt at the sintering temperature of the inorganic fine powder of the porous ceramic base and retains its fiber shape, with a fiber length of 30 to
250mm is selected. The amount of ceramic fiber mixed is preferably 0 to 20% by weight based on the inorganic fine powder.

On the other hand, combustible materials include flaky pulp, sawdust, rice husk,
The temperature is not particularly limited to thread waste, activated carbon, etc., and is below the temperature at which inorganic fine powder sinters, e.g. 600 to 800°C.
Any material that can be combusted and scattered at a temperature of 100 to 100 m is acceptable, but it is preferable to use a combustible material in the form of granules, flakes, or powder.

In the present invention, the remains of the burnt-out combustible material become voids and become a ceramic porous body.
It is desirable that the combustible substance be in the form of powder, particles, or flakes and be bulky to some extent. The particle size should be larger than that of the inorganic fine powder, but a particle having too large a diameter is not desirable because it will hinder the sintering of the inorganic fine powder during firing. For example, a particle size in the range of 10 to 60 mesh, preferably 20 to 40 mesh, is preferable as a carrier for inorganic fine powder or in terms of suitability for paper making.

In addition, if the amount of combustible material exceeds 70% by weight, the amount of inorganic fine powder is too small and it is difficult to obtain a sintered product even if fired, and if the amount is less than 10% by weight, the physical properties as a practical porous material are does not reach.

Next, when talking about flocculants, flocculants can be broadly divided into inorganic flocculants and polymer flocculants. Inorganic flocculants include aluminum sulfate (aluminium sulfate), sodium aluminate, aluminum chloride, ferrous sulfate, ferric sulfate, ferric chloride, etc., and polymer flocculants include polyacrylamide-based polymers. A typical example is a molecular flocculant, but other polymer flocculants such as polyamine, cationized starch, polyethyleneimine, and sodium polyacrylate can also be used.

For example, the polymer flocculant is 0.01 for inorganic fine powder.
It is characterized by the fact that the adsorption and flocculation effect increases with the addition of a small amount of about 0.2% by weight, and the use of a polymer flocculant alone is often sufficient. However, if an inorganic flocculant such as alba sulfate is used simultaneously in addition to a polyacrylamide-based polymer flocculant, the yield of adsorption and flocculation may be further improved. Inorganic flocculants tend to be added in large amounts compared to polymer flocculants, and can amount to as much as 0.5 to 3% by weight based on the inorganic fine powder. However, since the inorganic flocculant changes into a metal oxide during firing and becomes a component constituting the porous ceramic, there is no particular problem.

Although the explanation has been mixed, for an aqueous suspension whose solid content is sinterable inorganic fine powder and a combustible substance, it is necessary to sufficiently disperse the solid content and make it uniform. On the other hand, it is appropriate to suspend it with water in an amount of about 7 to 20 times by weight.

The present invention is as described above, and according to the present invention, a porous body formed by burning off a combustible material is more effective during the sintering process than a porous body formed by a method of kneading an inorganic or organic blowing agent. It is characterized by little deformation and high dimensional stability, and by arbitrarily selecting the amount of combustible material used, it is possible to obtain ceramic porous bodies with a wide range of bulk specific gravity, e.g. 0.3 to 1.5, depending on the purpose. . Since the papermaking method is used for the forming method, it is easy to uniformly distribute flammable substances that become porous cells, and it is also easy to form large-area plate-like objects, making it possible to obtain high-quality, large-sized porous ceramic bodies. It is something. Moreover, according to the manufacturing method of the present invention, the shape of the porous cells is a grain shape or a shape close to it, reflecting the shape of the powdery or flaky combustible material, and the shape of the porous cells is a grain shape or a shape close to it, reflecting the shape of the powdery or flaky combustible material. The structure is also robust,
Ceramic with high porosity can be obtained.

The porous ceramic body obtained by the manufacturing method of the present invention can be used as a heat insulating material, a sound absorbing material, an inner wall material of a building, and the like.

Example 1 70% by weight of inorganic fine powder with a composition of 45 parts viscosity, 40 parts feldspar, 5 parts wollastonite, and 10 parts chinastone,
A suspension aqueous solution was prepared by dispersing 30% by weight of sawdust classified into ~40 meshes, and a polyacrylamide-based polymer flocculant (trade name: Sanpoly N-500 (manufactured by Sankyo Kasei Co., Ltd.) was added at 0.02% of the inorganic fine powder. The inorganic fine powder was adsorbed and agglomerated on the surface of the sawdust powder, formed into a 10 mm thick plate by a normal wet papermaking method, and dried.

Next, the temperature was gradually raised to 1250°C over 8 hours in an oxidizing atmosphere to burn out the sawdust, and then a firing operation was performed at 1250°C for 1 hour to produce a uniform porous ceramic plate with a bulk specific gravity of 0.73. Obtained.

Example 2 An aqueous suspension solution was prepared in which 35% by weight of inorganic fine powder having the same composition as in Example 1 and 65% by weight of flaky pulp that passed through a 10-mesh sieve was dispersed, and a sulfate band was added to the fine powder. Add 2% by weight of polyacrylamide polymer flocculant to the fine powder at 0.02%.
% by weight, the fine powder is adsorbed and agglomerated on the surface of flaky pulp, and the thickness is 30% by normal wet paper making method.
Cut into a plate shape of 20 mm without drying it thoroughly.
It was pressed at a pressure of Kg/cm ² to obtain a 15 mm plate-shaped molded product.

Next, this was dried and subjected to normal firing in which the temperature was raised to 1280°C over 10 hours in an oxidizing atmosphere, kept at 1280°C cm ² for 1 hour, and then naturally cooled to obtain a uniform highly porous ceramic plate with a bulk specific gravity of 0.41. .

Claims (1)

[Claims] 1 30 to 90% by weight of sinterable inorganic fine powder and particle size of 10
A flocculant is added to an aqueous suspension containing 70 to 10% by weight of a powdered, granular or flaky combustible material of ~60 mesh to adsorb the inorganic fine powder onto the surface of the combustible material. It is characterized by forming a sheet-like or plate-like product by a normal wet papermaking method, drying it, burning and scattering flammable substances in an oxidizing atmosphere, and then sintering the inorganic fine powder. A method for producing a ceramic porous body.