JPH05262553A - Production of ceramic molded product - Google Patents

Abstract

PURPOSE:To improve the shape-retaining property of a ceramic molded product in its molding process and further improve the strength of the molded product after its drying and calcining processes by subjecting the ceramic fine powder raw material to a dry crushing process when the ceramic molded product is produced from the ceramic powder raw material by a series of processes. CONSTITUTION:A dry crushing treatment is applied to a ceramic fine powder raw material 1 by either one or more of a ball mill method, a vibration mill method and a rubber press method in a period ranging from the time of the raw material to the time for kneading the raw material. Thereby, spaces 3 in blocks formed by the combination of the primary particles 2 at the time of the raw material are eliminated due to the dispersing of the coagulated primary particles 2, and such the increase in the production cost as by conventional techniques using the above-mentioned spray drying method is not caused.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a ceramic compact using fine ceramic powder as a raw material.

[0002]

2. Description of the Related Art Conventionally, in the production of ceramics compacts, micron or submicron ceramic fine powder having a specific surface area of 20 m ² / g or more, such as alumina or zeolite, has often been used as a raw material. For the conventional technique used as a raw material, see JP-A-61-171539). Since such a ceramic fine powder has a property that primary particles are easily aggregated and voids are easily generated between the primary particles, the following problems occur when it is used for producing a ceramic molded body. That is, it is necessary to add a large amount of water in order to disperse the agglomerated primary particles when adding water to the ceramic fine powder raw material and kneading. Since the formability is deteriorated, it becomes difficult to obtain a desired shape, and a large number of voids are formed inside the molded body, resulting in insufficient strength after drying and firing.

In order to solve these problems, there has been proposed a conventional technique of uniformly dispersing the finely divided ceramic raw material powder by using an attritor or the like and then drying it by an atmosphere mist drying method.

[0004]

However, in the above-mentioned prior art, it is difficult to sufficiently eliminate the agglomeration of the primary particles because granulation easily occurs when the ceramic fine powder raw material is dried. Since the body raw material is once slurried and then dried, the number of steps is increased and the cost is increased.

The present invention provides a technique for removing the air from the ceramic fine powder raw material while ensuring the specific surface area of the fine or submicron ceramic fine powder raw material such as alumina or zeolite. The object is to improve the shape retention during molding and the strength after drying and firing.

[0006]

To this end, a method for producing a ceramic molded body of the present invention comprises a ceramic fine powder raw material to which a molding aid and a firing aid are added and mixed, followed by kneading for a predetermined time after water addition. When the kneaded material is molded, dried, and fired to produce a ceramic molded body, the ceramic fine powder raw material is dry-crushed before the kneading. is there.

[0007]

According to the method of the present invention, when the ceramic compact is manufactured from the ceramic fine powder raw material by a series of steps, the ceramic fine powder raw material after adding and mixing the molding aid and the firing aid is dry-processed. Since the step of scouring is added, it is possible to improve the shape retention during the molding of the ceramics molded body and to improve the strength after drying and firing without causing the cost increase as in the conventional technique using the above-mentioned mist drying method. You can The dry crushing may be performed before or after adding the molding aid and the firing aid to the ceramic fine powder raw material, and in that case, the same effect as above can be obtained.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a flow chart showing a method for manufacturing a ceramic molded body of the present invention. First, explaining the overall flow, in step 51, a ceramic fine powder raw material is manufactured by a conventional method, in step 52, the ceramic fine powder raw material is subjected to dry disintegration, which is the gist of the present invention, and in step 53. Mixing is performed by adding a molding aid and a firing aid to the ceramic fine powder raw material after dry defibration, and the ceramic fine powder raw material after mixing is mixed in step 54, and after kneading for a predetermined time, kneaded into a kneaded clay, and step In 55, the kneaded material is extrusion-molded into a predetermined shape, in step 56 the extrusion-molded body is dried, in step 57 a finishing treatment is applied, and in step 58 the extrusion-molded body is fired to produce a ceramics molded body. is there.

In the above, the dry crushing is carried out at the time of the raw material of the ceramic fine powder, but since this dry crushing is intended to reduce the viscosity of the kneaded clay,
In step 53, it may be dry defibrated after the mixing by adding the molding aid and the firing aid, or in step 54, it may be dry defibrated after mixing the ceramic fine powder raw materials after the mixing, in short, It may be before kneading.

Next, the dry type crushing will be described. As a method for performing dry defibration, for example, any one of ball mill method, vibration mill method, and rubber press method or 2
More than one seed shall be used. By this dry defibration, the ceramic fine powder raw material 1 becomes the primary particles 2 constituting it.
Before dry defibration, they were in a state of agglomeration to form voids 3 inside as shown in Fig. 2 (a), but after dry defibration, as shown in Fig. 2 (b), The aggregated primary particles 2 are dispersed, and the size of the block generated by the binding of the primary particles 2 is significantly smaller than that before dry crushing, so that voids are not generated and the specific surface area is reduced. There is no loss. In addition, this dry disintegration method has the effect of dispersing primary particles as compared with the conventional technique in which the ceramic fine powder raw material that has been agglomerated by a wet method using an attritor or the like is uniformly dispersed and then dried by an atmosphere mist drying method. It is remarkably excellent, and the ceramic fine powder raw material does not need to be once slurried and then dried, so that the cost is reduced.

Next, Example 1 in which the method of the present invention is applied to an alumina fine powder raw material will be described together with a comparative example. In Example 1, the raw material of α-alumina fine powder having a specific surface area of 20 m ² / g was placed in a pot mill, and dry defibration was performed for 12 hours using 15φ urethane balls in an amount three times the weight ratio, to aid in forming a defibration powder. After adding and mixing the agent and the firing aid, 21-25 Wt% of water is added, and the mixture is kneaded for a predetermined time to obtain a kneaded clay, which is extruded into a tubular molded body having an outer diameter of 8.5-10φ. When various measurements were performed on this Example 1, the results shown in Table 1 were obtained. The bending strength of the fired body was measured by a rheometer, and the specific surface area was measured by the BET method.

[0012]

[Table 1]

That is, in Example 1, the bending strength of the fired body shows a high value of 45 to 60 kg / mm ^{2 in} the case of crushing for 12 hours, and the manufactured tubular molded body is deformed during extrusion molding. It has excellent shape retention. On the other hand, in the comparative example simultaneously performed under the same conditions except that dry defibration was not performed, a large amount of water (for example, 36 Wt%) was required at the time of kneading in order to obtain a composition suitable for extrusion molding. The bending strength of the fired body was reduced to 30 kg / mm ² or less, and the produced tubular molded body was liable to be deformed during extrusion molding and had poor shape retention.

The above measurement is repeated to collect data and summarize them.
The characteristics shown in No. 5 were obtained. That is, regarding the bending strength of the fired body, as shown in FIG. 3, the bending strength of the fired body tends to improve as the unraveling time increases, and regarding the bulk specific gravity, as shown in FIG. At the beginning of crushing, the bulk specific gravity increases almost linearly with the crushing time, but after about 10 hours, it tends to converge to a constant value. It is shown that the kneading water content decreases as the bulk specific gravity increases.

Next, Example 2 in which the method of the present invention is applied to a zeolite fine powder raw material will be described together with a comparative example. In Example 2, the zeolite fine powder raw material having a specific surface area of 560 m ² / g was placed in a pot mill, and dry defibration was carried out for 20 hours using 15 to 5 times the weight ratio of 15φ alumina balls to form a defibration powder. After the auxiliary agent and the firing auxiliary agent are added and mixed, 50 to 55 Wt% of water is added and kneaded for a predetermined time to obtain a kneaded material, which is extrusion-molded by an extruder into a honeycomb molded body having an outer shape of 50 mm square. When various measurements were performed on this Example 2, the results shown in Table 2 were obtained. The bending strength of the fired body was measured by a rheometer, and the specific surface area was measured by the BET method.

[0016]

[Table 2]

That is, in Example 2, the compressive strength of the fired body shows a high value of 10 to 15 kg / cm ^{2 in} the case of crushing for 20 hours, for example, and the produced tubular molded body exhibits deformation during extrusion molding. It has excellent shape retention. On the other hand, in the comparative example simultaneously performed under the same conditions except that dry defibration was not performed, a large amount of water (for example, 80 Wt%) was required at the time of kneading in order to obtain a composition suitable for extrusion molding. The compressive strength of the fired body was reduced to 1 kg / cm ² or less, and the manufactured honeycomb molded body was liable to be deformed during extrusion molding and was inferior in shape retention and eventually could not be used. became.

By repeating the above-mentioned measurement and collecting and collecting data, the zeolite fine powder raw material is shown in FIG.
The characteristics shown in to 8 were obtained. That is, regarding the compressive strength of the fired body, as shown in FIG. 6, the bending strength of the fired body tends to improve as the unraveling time increases, and regarding the bulk specific gravity, as shown in FIG. At the beginning of the bowl, the bulk specific gravity increases with an increase in the unraveling time, but after about 10 hours, the bulk specific gravity tends to converge to a constant value. It is shown that the kneading water content decreases as the water content increases.

[0019]

As described above, according to the present invention,
When a ceramic compact is manufactured from a ceramic fine powder raw material by a series of steps, dry fine smashing is performed on the ceramic fine powder raw material from the time of the raw material to the time of kneading. It is possible to improve the shape retention during molding of a ceramics molded body and improve the strength after drying and firing without increasing the cost as in the conventional technique using the drying method.

[Brief description of drawings]

FIG. 1 is a flowchart showing a method for manufacturing a ceramic molded body of the present invention.

FIGS. 2 (a) and 2 (b) are views for explaining the action of dry crushing used in the method for manufacturing a ceramic molded body.

FIG. 3 is a view showing the transverse rupture strength characteristics of the first embodiment in which the method for producing a ceramics compact is applied to an alumina fine powder raw material.

FIG. 4 is a diagram showing the bulk specific gravity characteristics of the first embodiment in which the method for producing a ceramic compact described above is applied to an alumina fine powder raw material.

FIG. 5 is a diagram showing a kneading water characteristic of the first example in which the method for producing a ceramic compact is applied to an alumina fine powder raw material.

FIG. 6 is a diagram showing the compressive strength characteristics of the second embodiment in which the method for producing a ceramic compact described above is applied to a zeolite fine powder raw material.

FIG. 7 is a diagram showing the bulk specific gravity characteristics of a second embodiment in which the method for producing a ceramics compact is applied to a zeolite fine powder raw material.

FIG. 8 is a diagram showing a kneading water characteristic of a second example in which the method for producing a ceramic molded body is applied to a zeolite fine powder raw material.

[Explanation of symbols]

 1 Ceramic Fine Powder Raw Material 2 Primary Particle 3 Void

Claims (2)

[Claims] 1. A ceramics powder is formed by adding a molding aid and a firing aid to a ceramics fine powder raw material, mixing the mixture, kneading the mixture for a predetermined period of time to obtain a kneaded material, molding the kneaded material, drying it, and then firing it. A method for producing a ceramic molded body, which comprises dry-crushing the ceramic fine powder raw material before the kneading in producing the body. 2. The method for producing a ceramic molded body according to claim 1, wherein the dry crushing is performed before or after adding a molding aid and a firing aid to the ceramic fine powder raw material.