JPS6327310B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a ceramic porous body, and more particularly to a method for producing a ceramic porous body having continuous fine pores. Conventionally, porous ceramic materials have been used as filling materials for bone defects,
The ceramic porous body is used as a catalyst carrier, a filtration material, etc., and the method for producing the ceramic porous body is to immerse an organic porous body having continuous pores such as polyurethane foam in a ceramic raw material slurry, and then coat the inner surface of the pores with ceramic. A known method is to deposit a raw material slurry, then heat to decompose the organic porous material, and sinter the deposited ceramic to form a porous ceramic material. However, in this known method, the ceramic raw material slurry fills the pores of the organic porous body, resulting in clogging. As a result, it has been difficult to produce a ceramic porous body having continuous pores and pores uniformly distributed throughout. This tendency to easily become clogged is particularly noticeable when a ceramic porous body having continuous fine pores is manufactured using an organic porous body having fine pores; It was not even possible to attach the raw material slurry to the pores inside the organic porous body, and it was completely impossible to produce it using the above method. In order to prevent this clogging, a method has been proposed in which an organic porous material is immersed in ceramic raw material slurry and then passed through a centrifuge or rolls to remove the clogged parts of the raw material slurry, but only the clogged parts of the ceramic raw material slurry are removed. It is difficult to do so, and has the disadvantage that even the ceramic raw material slurry adhering to the inner surface of the pores of the organic porous body is removed, which weakens the skeleton of the ceramic porous body that is formed and reduces its strength. It was extremely small and could not be put to practical use. On the other hand, if we focus on strength and try to increase the strength by increasing the density of the slurry by reducing the particle size of the ceramic powder that makes up the ceramic raw material slurry, the viscosity will inevitably increase, which will further promote clogging. I become confused. On the other hand, if the density of the ceramic raw material slurry is reduced in order to prevent clogging, the strength of the ceramic porous body formed will be reduced, making it impossible to satisfy the contradictory requirements of increasing strength and preventing clogging. Furthermore, in order to increase the adhesion of ceramic raw material slurry to the inner surface of the pores of an organic porous body, a method has been proposed in which the inner surface of the pores is roughened.
It has not been possible to provide an effective manufacturing method because an extra step of surface roughening is required, and in the case of an organic porous body having fine pores, the ceramic raw material slurry inevitably becomes clogged. As mentioned above, in all known methods for producing ceramic porous bodies, it is not possible to attach the ceramic raw material slurry to the inner surface of the pores of the organic porous body having fine pores without clogging it, and it is impossible to attach the ceramic raw material slurry to the inner surface of the pores of the organic porous body with continuous fine pores. It has not been possible to produce strong ceramic porous bodies with pores and pores uniformly distributed throughout. Therefore, one object of the present invention is to produce a ceramic porous body having continuous fine pores by attaching a ceramic raw material slurry to the inner surface of the pores of an organic porous body having fine pores without clogging the pores. The purpose is to provide a method. Another object of the present invention is to provide a method for producing a porous ceramic body having pores uniformly distributed throughout. Still another object of the present invention is to provide a method for producing a ceramic porous body having a strength suitable for practical use. The above and other objects of the present invention will become clearer from the following description. According to the present invention, a foaming agent is added to a ceramic raw material slurry, and an organic porous body having continuous fine pores is immersed in the ceramic raw material slurry after foaming with the foaming agent, or is immersed and then foamed. The ceramic raw material slurry was attached to the inner surface of the pores, and then the organic porous body to which the ceramic raw material slurry was attached was heated to decompose and disappear, and the remaining ceramic skeleton was sintered to form a continuous ceramic material. A method for manufacturing a porous ceramic body is provided, which comprises forming a porous ceramic body having fine pores and pores uniformly distributed throughout. The present invention will be explained in more detail below. Ceramic raw materials constituting the ceramic raw material slurry used in the present invention include clay, talc,
Natural raw materials used in ceramic production such as silica, feldspar, pottery stone, silicon, aluminum, calcium,
Examples include oxides, hydroxides, salts, carbides, and nitrides of magnesium, titanium, zirconium, and the like. The smaller the particle size of the ceramic raw material used, the larger the surface area and the greater the cohesive force when made into a slurry. The strength of a ceramic porous body that has not been sintered immediately after immersing an organic porous body in a ceramic raw material slurry and attaching it to the pores and thermally decomposing the organic porous body is determined by the particle size of the ceramic raw material used. The smaller the particle size, the larger the particle size, so it is preferable that the particle size is small. Therefore, when using natural raw materials, they must be crushed to an average particle size of several μm.
The following is desirable. In addition, when producing ceramic raw materials, if a method is adopted in which the ceramic raw materials are obtained as gel-like substances from metal alcoholates or solutions by precipitation, ceramic raw materials with fine particle sizes, for example, 1 μm or less, can be obtained. It is preferable because it can be obtained. It is preferable that the ceramic raw material has fine particles and therefore the ceramic raw material slurry has thixotropic properties, since the adhesion to the inner surface of the pores of the organic porous body is good. The ceramic raw material slurry used in the present invention can be obtained by dispersing ceramic raw material powder in a dispersion medium such as water, ethanol, or nitrobenzene. If necessary, viscosity modifiers and dispersants can be added to change the properties of the slurry, but additives other than ceramic raw materials should be kept as low as possible to increase the bulk density of the ceramic porous body and develop strength. is desirable. It is desirable that the ceramic raw material slurry has a viscosity coefficient in the range of 0.5 to 1000 poise, preferably 5 to 200 poise. If it is less than 0.5 poise, the amount of ceramic raw material may be insufficient and the strength of the ceramic porous body may not be sufficient. On the other hand, if it exceeds 1000 poise, fluidity will deteriorate and there is a risk of clogging, and foaming may be difficult. Sometimes I get old. In the present invention, a foaming agent is added to the above-mentioned ceramic raw material slurry and foaming is performed after foaming or after an organic porous body having continuous fine pores is immersed in the slurry. The foaming operation can be carried out simply by stirring the ceramic raw material slurry or by compressing and expanding an organic porous body immersed in the ceramic raw material slurry. Foaming caused by the addition of a foaming agent has an important meaning in the present invention. In other words, the ceramic raw material slurry contains fine air bubbles due to the foaming of the foaming agent, and these fine air bubbles enter the fine pores of the organic porous material, so that the pores are filled with the ceramic raw material slurry and become clogged. There is no such thing as a problem. The fine closed cells that have entered the pores of the organic porous body are composed of a film of ceramic raw material slurry, and the closed cells are bonded to each other, and the ceramic raw material slurry is attached to the inner surface of the pores. When a foaming surfactant is used as the foaming agent, as will be described later, adhesion to the inner surface of the pores of the organic porous material is increased. If the bubbles are small, the bubbles are enlarged by placing them under reduced pressure, and a ceramic raw material slurry film is attached to the inner surface of the pores, thereby increasing the tendency of the bubbles to bond with each other. In order to adjust the amount of ceramic raw material slurry adhering to the organic porous body, it is possible to use a centrifuge or rollers, but even in such a case, the air bubbles made up of the ceramic raw material slurry membrane remain in the pores. There is no possibility that too much of the ceramic raw material slurry will be removed. As mentioned above, independent air bubbles are combined, but not all the air bubbles are combined to form a continuous film of ceramic raw material slurry inside the pores. The bubbles are completely broken, the slurry dispersion medium evaporates, and the ceramic raw material is continuously deposited along the pores. Organic porous materials usually decompose and disappear when heated to around 500°C, leaving only the ceramic skeleton. Bubbles can also be broken by applying ether vapor or ultrasonic waves before heating to break the bubbles. Examples of the organic porous material having continuous fine pores used in the present invention include polyurethane foam and polyvinyl foam. The organic porous material preferably has a pore diameter in the range of 0.05 to 1.5 mm, particularly 0.1 to 0.7 mm. If it is less than 0.05 mm, there may be a risk of clogging of the ceramic raw material slurry;
If it exceeds mm, the strength of the final ceramic porous body may be insufficient. The foaming agent added to the above-mentioned ceramic raw material slurry includes surfactants with foaming properties, such as ionic surfactants such as anionic surfactants and cationic surfactants, and nonionic surfactants. There are surfactants and non-aqueous dispersion medium surfactants. Examples of anionic surfactants include fatty acid stones such as sodium laurate, sodium myrstate, and sodium oleate, alkyl sulfate salts such as sodium decyl sulfate, and sodium hexadecyl sulfate, and linear alkylbenzene sulfonate salts. . Examples of cationic surfactants include quaternary ammonium salts such as benzyl dimethyl alkylammonium chloride, dodecyl dimethyl benzyl ammonium bromide, and amine salts such as diethylaminoethyl oleylamide. Examples of nonionic surfactants include polyoxyethylene alkyl ethers such as ethylene oxide adducts such as lauryl alcohol, stearyl alcohol, and cetyl alcohol, and polyoxyethylene such as sorbitan monooleate polyglycol ether and sorbitan monolaurate polyglycol ether. These include sorbitan monoalkyl esters and sugar esters. Other non-aqueous dispersion medium surfactants include fatty acid dodecyl ammonium and sodium dioctyl sulfosuccinate. The ceramic skeleton obtained by thermally decomposing the organic porous material as described above has a temperature of, for example, 1000° to 1850°C.
The ceramic porous body of the present invention can be obtained by sintering at a temperature of . By the method of the present invention, the porous body has fine continuous pores of 0.03 to 1.2 mm, the pores are uniformly distributed throughout the porous body, the porosity is 40 to 97%, and it has practical strength. It is possible to obtain a porous ceramic body. The ceramic porous material of the present invention can be used as a filtration material and a catalyst carrier, and since it has fine continuous pores, it can also be applied as a biomaterial, and can be used as a culture carrier for microorganisms and cells, a bone filler, and a bone filler. It can be used as a replacement agent, etc. Next, the present invention will be explained with reference to examples. Example 1 Kibushi clay 10 parts by weight, kaolin 64 parts by weight, talc 12 parts by weight
parts by weight, 14 parts by weight of magnesite, 25 parts by weight of water, and 0.5 parts by weight of water glass were mixed and pulverized in a pot mill for 40 hours to produce ceramic slurry A having a particle size of 5 μm or less. Ceramic slurry B was produced by adding 1 part by weight of polyoxyethylene sorbitan monolaurate as a foaming agent. A polyurethane foam having an average pore diameter of 0.5 mm was immersed in each of these, and the foam was repeatedly expanded and compressed in the slurry, and the foam was sufficiently impregnated with the slurry. In the case of ceramic slurry A, there was no foaming at all, and the slurry filled the pores of the polyurethane foam. On the other hand, in the case of ceramic slurry B, air bubbles having the same size as the pore diameter of the polyurethane foam were generated in the slurry, and the slurry containing the air bubbles filled the pores of the urethane foam. A polyurethane foam containing the above ceramic slurry A was passed through a roller to completely remove excess slurry in the pores to prepare A ₁ , and A ₂ was prepared by changing the roller pressure to leave some slurry.
On the other hand, a sample _B2 was prepared by applying _a slight roller pressure to remove the excess slurry. These were dried at 100°C for a day and a night. Upon drying, the slurry bubbles in polyurethane foam B ₂ were completely destroyed, and the ceramic slurry was attached to the inner surface of the pores of the polyurethane foam.
In _B1 , there was a little extra slurry, and there were some parts that filled in some pores. On the other hand, in polyurethane foam A ₂ , a considerable portion of the pores are filled with residual slurry.
In case of _A1 , most of the slurry had been removed, so only a small amount of slurry was attached to the wall surface. These were heated to 500°C to thermally decompose the polyurethane foam, and then heat treated at 1250°C for 2 hours to sinter the ceramics to obtain ceramic porous bodies A ₁ , A ₂ , B ₁ and B ₂ . Ceramic porous material
Since _A1 had a small amount of attached ceramic, it collapsed at the stage when the polyurethane foam was thermally decomposed. Since the ceramic porous body _A2 was filled with pores, almost no continuous pores were obtained. Most of the ceramic porous body _B1 had continuous pores, but there were only a few closed portions. A ceramic porous body _B2 had no closed portions and had continuous pores. Ceramic porous material
B ₁ and B ₂ did not collapse and had sufficient strength for practical use, and the pores were uniformly distributed throughout. Table 1 shows the measurement results of the porosity and the average pore diameter.

[Table] Examples 2 to 5 B ₁ in Example 2 by the same method as Example 1
Ceramic porous bodies corresponding to Examples 3 to 5 were
A ceramic porous body corresponding to B ₂ was manufactured in . The raw materials are shown in Table 2, and the results are shown in Table 3.

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Claims (1)

[Claims] 1. Adding a foaming agent to ceramic raw material slurry,
An organic porous body having continuous fine pores is immersed in the ceramic raw material slurry after foaming with the foaming agent, or is immersed and then foamed to adhere the ceramic raw material slurry to the inner surface of the pores, and then the ceramic raw material slurry is attached to the inner surface of the pores. heating the organic porous body to which the raw material slurry is attached to decompose and eliminate the organic porous body;
A method for manufacturing a porous ceramic body, which comprises sintering the remaining ceramic skeleton to form a porous ceramic body having continuous fine pores and pores uniformly distributed throughout. 2 The ceramic raw material slurry is 0.5 to 1000
2. The method of manufacturing a porous ceramic body according to claim 1, wherein the ceramic porous body has a viscosity coefficient of Poise. 3. The ceramic according to claim 1, wherein the foaming agent is selected from the group consisting of ionic surfactants, nonionic surfactants, and non-aqueous dispersion medium surfactants. Method for producing porous body. 4. The ionic surfactant is selected from the group consisting of fatty acid stone, an alkyl sulfate salt, a linear alkylbenzene sulfonate salt, a quaternary ammonium salt, and an amine salt. A method for producing a ceramic porous body. 5. The ceramic porous body according to claim 3, wherein the nonionic surfactant is selected from the group consisting of polyoxyethylene alkyl ether, polyoxyethylene sorbitan monoalkyl ester, and sugar ester. Production method. 6. The method for producing a porous ceramic body according to claim 3, wherein the non-aqueous dispersion medium-based surfactant is selected from the group consisting of fatty acid dodecyl ammonium and sodium dioctyl sulfosuccinate. 7 The organic porous body has a pore diameter of 0.05 to 1.5 mm.
A method for manufacturing a porous ceramic body according to claim 1, characterized in that: 8. Claim 1 or 7, characterized in that the organic porous material is selected from the group consisting of polyurethane foam and polyvinyl foam.
A method for producing a ceramic porous body as described in 2. 9. The method for producing a porous ceramic body according to claim 1, wherein after the ceramic raw material slurry is deposited on the inner surface of the pores of the organic porous body, the slurry is placed under reduced pressure. 10. The ceramic porous body according to claim 1 or 9, characterized in that after the ceramic raw material slurry is deposited on the inner surface of the pores of the organic porous body, it is exposed to ether vapor or ultrasonic waves. Production method. 11. Claim 1, 9 or 10, characterized in that after the ceramic raw material slurry is deposited on the inner surface of the pores of the organic porous body, it is applied to a centrifuge or a roller. A method for producing a ceramic porous body. 12. The method for producing a porous ceramic body according to claim 1, wherein the porous ceramic body has pores of 0.03 to 1.2 mm and a porosity of 40 to 97%.