JPS6365631B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a porous ceramic molded body.

In recent years, this type of porous ceramic molded body has been used as a filter medium, a catalyst carrier, a radiation converter, and the like. As a method for producing this porous ceramic molded body, the method disclosed in Japanese Unexamined Patent Publication No. 58-84162 exists as an existing technique.

As shown in FIG. 2, this existing method extrudes a material into a line shape that can be plastically deformed from a nozzle 101 provided in an extrusion die 100, fills the extrudate 102 into a forming die 103 of a predetermined shape, and then presses the extrusion die 100 into a molding die 103. After forming an aggregate 104 according to the shape of the inside 103, this is dried and sintered.

However, this method has the following problems.

(1) Since the linear extrudate is unsintered, the aggregate shrinks during the drying and sintering stages, making it difficult to obtain a ceramic porous molded body with regular dimensions.

(2) Since the linear extrudate is directly filled into the molding die, it is not only difficult to mold products with complex shapes, but also requires skill when filling the die, resulting in partially uneven packing density.

The present invention has been made in view of the above-mentioned conventional circumstances, and its object is a method for producing a ceramic porous molded body that can easily and reliably mold a porous molded body of a predetermined shape without producing dimensional errors due to shrinkage. We aim to provide the following.

The basic method for achieving this purpose is to form short linear sintered bodies into straight or curved shapes of the desired length and fire them, bond them together through slurry, fill them into a production mold, and after drying. , demolding and firing.

Hereinafter, an example of implementation of the present invention will be described based on the drawings.

The first step is to obtain a short linear sintered body A having a desired length.

The short linear sintered body A is one type or several types of straight or curved pieces with a wire diameter of 3 mmφ or less and a length of 10 to 150 times, preferably 30 to 80 times, the wire diameter. Then, water or a suitable binder is added to powder of a non-porous inorganic material such as alumina, cordierite, mullite, silicon nitride, etc., and extruded with a clay kneader to produce a short wire-shaped extrudate, which is then fired and dried, or After firing, the extrudate is cut into a long linear shape and shaped.

Note that the cross-sectional shape of the short linear sintered body A may be any shape such as a circle or a corner.

In the second step, short linear sintered bodies A are joined together using slurry C to form an aggregate B.

The slurry C has the same composition as the short linear sintered body A, or has a composition with a slightly lower ignition temperature, and can be prepared by spraying or by dipping the short linear sintered body A into the slurry layer c as shown in the figure. After a predetermined period of time, the slurry layer c is taken out to form an aggregate B.

In addition, it goes without saying that excess slurry C not related to bonding must be removed from the aggregate B, and even if this aggregate B is not manufactured using the same type of short linear sintered body A, the length, diameter, and shape of the aggregate B can be improved. It may be produced by mixing several types of short linear sintered bodies A with different shapes.

The third step is to dry the aggregate B, remove it from the mold, and fire it. Fill the predetermined manufacturing mold D with the aggregate B so that it blends in, dry it, remove it from the mold, and fire it to make it continuous inside. A ceramic porous molded body F having pores E is obtained.

In addition, to explain the experimental examples conducted in order to further ensure the understanding of the present invention, in the experimental example (), 35 parts of chlorite, 30 parts of kaolin, and feldspar were used.
16 parts of petalite, 13 parts of alumina, and 6 parts of alumina are mixed with 2 parts of water glass and 50 parts of water. This mixture is ground with a cylinder mill to form a slurry, dried, and then ground with a power mill to form granules. get something Next, 52 parts of water, 7 parts of polyethylene glycol,
A binder prepared by mixing 9 parts of methylcellulose and 32 parts of vinyl acetate and kneading with a kneader is mixed in a ratio of 1 part to 2 parts of the granules. This is extruded using a clay kneading machine to make linear products of 1Φ and 0.7Φ, which are dried and then cut into pieces of 20 to 80 mm and fired at 1250°C to obtain two types of short linear sintered bodies A. Add this short linear sintered body A to 100 parts of the slurry at a CMC rate of 1%.
After being immersed in a slurry bath containing 20 parts by weight of the solution, it was taken out and the excess slurry was cut off to form the aggregate B. This was put into a prescribed mold and formed into a prescribed shape, and after temporary drying, the mold was removed and main drying was carried out. Calcined at ℃. As a result, there was no shrinkage,
A porous molded body F having continuous pores with a porosity of 75 to 89% was obtained.

Experimental example () uses a slurry prepared by mixing 98 parts of alumina, 1 part of clay, and 1 part of MgCo ₃ with 67 parts of water as the composition of the short linear sintered body A, and this is mixed with 4 parts of methylcellulose, 15 parts of water, and 3 parts of glycerin. Example of an experiment: kneading with a binder mixed with a mixer and using a clay kneading machine.
Extrude in the same way as in (1) to make linear objects of 1Φ and 0.7Φ,
After drying, the pieces are cut into pieces of 20 to 80 mm and fired at 1600°C to obtain two types of short linear sintered bodies A.

This was immersed in a slurry bath in the same way as in the experimental example (),
Apply slurry C, fill it in a specified mold and dry it.
Fired. The results showed that the manufactured porous molded body F had no shrinkage deformation and maintained a continuous porosity of 70 to 85%. In addition, this porosity is an experimental example ()
It goes without saying that both () can be freely changed depending on the relationship between the shape, length, and diameter of the short linear sintered body A.

Since the present invention employs the method described above, it is possible to easily and simply form a porous molded body with accurate dimensional accuracy without shrinkage deformation, and in order to obtain a predetermined shape, complicated splitting during the firing process and cutting after firing can be performed. There is no need to waste effort.

In addition, it is possible to form porous compacts with various continuous porosity depending on the length, shape, and wire diameter of the short linear sintered compact, and it is possible to form porous compacts with a maximum continuous porosity of 95%. Manufacturing is also possible.

Thus, the intended purpose can be achieved.

[Brief explanation of drawings]

The drawings show an example of the method for producing a ceramic porous molded body according to the present invention, with FIG. 1 being a process diagram and FIG. 2 being a vertical sectional view schematically showing the conventional production method. In the figure, A: short linear sintered body, B: aggregate, C:
Slime, D: Manufacturing type, E: Continuous pores, F: Ceramic porous molded body.

Claims (1)

[Claims] 1 Cutting an unfired cotton-like material and then firing it, or cutting the fired cotton-like material to make a large number of short linear sintered bodies, and attaching slurry to the short linear sintered bodies to form a predetermined shape. A method for producing a porous ceramic molded article, which comprises filling a production mold, drying, removing the mold, and firing.