JPS5983972A - Manufacture of ceramic porous body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a porous ceramic body, and more particularly to an improvement in the method for producing a porous ceramic body used in filters and the like by solvent extraction.

Generally, the manufacturing method of ceramic porous bodies used for automobile exhaust gas filters, etc. is to mix a large amount of carbonate, etc., which has a large loss on ignition, and to prevent the generation of air bubbles due to thermal decomposition during firing. In addition, by mixing a large amount of resin powder and removing it as a gas from the ceramic by thermal decomposition, the resin can be treated as a gas and left behind. It was formed in a porous manner.

However, according to these methods, gas generation is associated with thermal decomposition, so they emit a foul odor, cause air to flow, and are unsafe and unsanitary to work with, requiring special consideration to prevent pollution. Furthermore, all of these decomposed products are disposable (), which is not desirable from the standpoint of resource conservation, resulting in losses of 1 to 10%. In addition, it is difficult to crush this resin for pyrolysis due to its flexibility and stickiness.It is even more difficult to obtain resin powder with uniform particle size in a high yield. Differences in the material or size of the mix cause uneven heating and differences in heating speed, making it difficult to generate uniform air bubbles.These problems cause quality control problems and reduce yield. Ta.

Therefore, instead of using thermal decomposition, the resin in the ceramics before firing is extracted with an organic solvent to elute the resin and form pores in the ceramics where the resin has been removed. However, in this method, the resin used for various purposes is completely extracted compared to the decomposition and foaming method by heating, and the remaining resin must be thermally decomposed, and the process is similar to the above. t [Problems arose. Furthermore, the organic solvent extraction processing port was handled in a blasphemous manner, further deteriorating operational safety and hygiene.

As a result of intensive research on ω1, the present inventors found that f is insoluble in organic solvents.
The inventors have discovered that the above problems can be solved by using a water-soluble substance and performing extraction with water, and have completed the present invention.

That is, the gist of the present invention is that 11
Dissolved in organic solvent! : The binder and the water-soluble granular material insoluble in the organic solvent are kneaded with the Reramitsu raw material powder, molded, and then the organic solvent and the water-soluble granular material are extracted in water IM! A method for producing a porous ceramic body includes firing for 1 hour.

The water-compatible organic solvent used here is, for example, dimebylformamide,]]nitylal=1-lumef)
Examples thereof include lenoyl, propylfalloon, methylethylketene, dimethylsulfoxide, and the like. The binder is various polymers that are soluble in organic solvents.
Examples include polyurethane, borisdyrene, polyvinyl butyral, vinyl chloride, nitrocell['-s], polyacrylic, nibblecel[1-s], and the like. This binder is used after being dissolved in the above organic solvent, and its concentration is 20
It is preferably 35% by weight, and if it is less than 20% by weight, it is too thin, and a large amount of the solution must be blended in order to exhibit its performance as a binder. However, when this happens, the viscosity of the raw ceramic decreases, and it begins to have C fluidity and loses shape retention, making it impossible to mold.Also, if it exceeds 35% by weight, the viscosity of the solution itself decreases. If the temperature becomes too high, the raw ceramic becomes hard and difficult to mold using machines such as extrusion.In addition, when blending the binder by dissolving it in solution, the binder is not dissolved in all the solvent from the beginning, but may be dissolved in some of the solvent. After blending the dissolved solution with another ceramic raw material 1, the remaining solvent is added to adjust the hardness of the raw ceramic by adding C to the final binder concentration of 20.
It suffices if ~351fi% of the material is added. Next, the blending amount of the binder solution with this high degree of strength is preferably 25 to 50 parts by weight per 100 parts of ceramic raw material powder, and if it is less than 25,000 ID parts, the amount of binder becomes too small and raw material The shape-retaining properties of the raw raw ceramic lamix deteriorate, and the green raw lamic molded body collapses during the first molding process or during the subsequent extraction treatment in water. Again, 50! 'T8t
If it exceeds 1 part, there will be too much binder, which will affect the pore size and porosity during ceramic firing, and a large amount of combustion gas will be generated, making it unsafe! ti'I-
This would cause pollution problems and defeat the purpose of the method of the present invention.

1. Water-compatible 41Substances insoluble in solvents include, for example, ammonium chloride, chlorium chloride, potassium chloride, hydroxide, potassium hydroxide, salt, 9 M ammonium, phosphoric acid. Ammonium, mono-lium citrate, ammonium carbonate, sodium carbonate-11, potassium carbonate, mono-lium hydrogen phosphate, mono-lium phosphate,
Examples include phosphoric acid, sodium hydrogen phosphate, potassium hydrogen phosphate, glycogen, 3-aminolyrithylic acid, γ-aminobutyric acid, L-Δxyglutamic acid, etc., and these can be adjusted to the desired pore size and porosity ( The materials used for the specified purpose are crushed to a predetermined particle size and used.''The above substances are blended in such a way that the pore size and porosity of the ceramic after firing are in the desired state. If the particle size is too large, the pore size becomes large and the inner surface area of the pore becomes small, making it undesirable for filters, carriers for enzymes and ion exchange resins, light absorbing materials, etc. If the particles are too small, they will easily absorb moisture and moisture in the air or solvent, and will dissolve or solidify before the extraction process, so particles of 25 to 300 μ are generally used. If the amount is too large, the strong electric potential of the fired ceramic will decrease, and if it is too small, the porous material will no longer be effective.
Add 3 to 50 Φ parts per 0.

The pulverization method can be carried out using a commonly used pulverization method, for example, using a pulverization method such as a ball mill, vibration mill, rod mill, roll crusher, or micropulverizer, and if necessary, sieving to make the particle size uniform. used.

As raw materials for ceramics, all those normally used to form fired ceramic bodies can be used, such as talc, clay, alumina, silica, magnesia, feldspar, limestone, zirconia, petalite, dolomite, etc. These are used in dry bodies of appropriate fineness as required.

Using the above raw materials, the manufacturing method of the present invention is carried out as follows.

For kneading and molding the binder solution, water-soluble granular material, and ceramic raw material, equipment that generally kneads or molds ceramic raw materials can be used.

During this mixing and purification, water is not included, so the water-soluble particulate matter exists in the kneaded and molded raw ceramic in its original form.

In the above-mentioned method of extracting the molded product in water, the molded product may be simply immersed in a container filled with water, but in order to increase the extraction efficiency, it may also be immersed in running water. It is also effective to extract at a lower temperature.Due to this extraction process, the organic solvent migrates into water due to its compatibility with water, and then water enters and covers it.This intruded water causes water-soluble When the granular material is reached, the granular material is eluted and becomes pores.This results in a raw ceramic porous body.

The reason why the ceramic molded body does not decompose during extraction with water is that at the same time as the water-soluble particulate matter is extracted with water, the organic solvent that had dissolved the binder in the ceramic molded body is also extracted with water, and the binder is dissolved in the solvent. This is because it solidifies and retains the shape of the ceramic. In this case, the binder remains in the lamix and decomposes during firing, but the amount of binder does not affect the already formed pore size or cause odor or pollution.

As described above, the raw ceramic molded body extracted with water and turned into a porous body is dried and then fired under normal firing conditions to become a porous ceramic body having a desired pore size.

As described in detail above, according to the manufacturing method of the present invention, a binder dissolved in an organic solvent that is compatible with water and a water-soluble particulate material that is insoluble in the organic solvent are kneaded with ceramic raw material powder, and then molded. Then, by extracting the organic solvent and the water-soluble particulate material in water and baking it, the amount of pores in the water-soluble particulate material can be controlled, and the particle size of the material can be adjusted to J:. It is extremely easy to control the pore diameter from 1 to 1, contributing to improved quality. Furthermore, since a large amount of IM nfts is not thermally decomposed, problems of bad odor and air pollution are eliminated. Moreover, the water-soluble particulate matter eluted into water can be recovered by recrystallization separately, leading to resource saving and cost reduction. The ceramic porous body subjected to 'IJti' in this way can be used for automobile exhaust gas filters, various industrial filters, lightweight heat-resistant structural materials, sound absorbing materials, light absorbing materials, P1-pipe wicks, enzyme carriers, and ion exchange resins. It is useful for use as a carrier, etc.

Next, the present invention will be specifically explained based on examples thereof.

Example-1 ■Ceramics raw material talc 200 parts by weight Clay 222 Alumina 78II ■Binder solution Polyurethane resin 30% by weight Dimethylformamide 70 ■Hara 1',! l base material 500 (add a predetermined amount of ammonium chloride (grade 1 reagent) or υ゛tucharose as a water-soluble granular material to I, dry mix it, add 35% by weight of ■ to the entire base material, and mix it in a clay kneading machine. After kneading for 15 minutes, the mixture was extruded into a honeycomb shape using a molding machine.

This was kept in a running water tank for about 6 hours and then dried to obtain a porous honeycomb molded body. This was fired in an electric furnace at 1400° C. for 6 hours in an oxidizing atmosphere to obtain a cordierite porous honeycomb ceramic.

Example-2 ■ Ceramic raw material Example-1 and the binder solution Polyvinyl butyral 25% heavy duty bar 1% (manufactured by Katsuzu Kagaku Co., Ltd. - L Sletsk BMS) Soil 1-rual]-ru 75 II Ammonium carbonate as water-soluble granular material A porous honeycomb single rayonomics was obtained in the same manner as in Example 1, except that (1st class reagent), Gree J-gun, or γ-aminobutyric acid was used.

Example-33 ■e Lamix 16th +1 Same as Example-1 (2) Hinta solution methacrylic acid earth sprue resin 35% by weight A L? l-n
(35u water soluble (as 11 particulate matter)
A porous shell-shaped ceramic was prepared in the same manner as in Example 1, except that 1J of ammonium salt was used.

Compare J3 with Example-1 without adding any water-soluble particulate matter? Honeycomb-shaped ceramics were prepared using the same method as 19.

1 for each example and comparative example! Table 1 shows the measurement data of the water absorption rate and average pore diameter of the porous honeycomb-shaped ceramics. However, the average pore diameter was measured using the mercury 0-human method, and the water absorption rate was measured in 11 ways as follows.

How to measure water absorption: Weight when completely dry and saturated spoonful in water! ! I'!
If we plot the particle size (μ) of the water-soluble granular substances listed in Table 1 on a logarithmic scale on the horizontal axis and the average pore diameter (μ) of ceramics on a logarithmic scale on the vertical axis, we get a straight line as shown in Figure 1. The graph becomes or,
If we plot the proportion of water-soluble particulate matter (wt%) on a logarithmic scale on the 1# axis and the water absorption rate (%) corresponding to pores on a vertical scale, we get a straight line graph as shown in Figure 2. .

The results revealed the following: 1. No combustion gas was generated during firing of ceramics, and no safety problems were caused. In addition, water-soluble ↑111 from the water used for extraction
For one particulate matter crystal, the amount of J, S, 65) ~
70% was recovered. The foaming state was as desired and the uniformity was also good.

[Brief explanation of the drawing]

Figure 1 shows the particle size of water-soluble granular material after firing. - What is the average pore diameter of ceramic ceramics? ,: represents a graph.

Claims (1)

[Claims] 1 A binder dissolved in a water-compatible organic solvent and a water-soluble particulate material insoluble in the organic solvent are mixed into a ceramic raw material 1'.
31 powder, molding, then extracting the organic solvent and water-soluble particulate material in water, and firing.