JPH11277522A - Manufacture of ceramic extrusion-molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent voids from developing in a ceramic sintered compact by a method wherein a highly viscous composition for extrusion molding, which is prepared by removing some part of a solvent from a slurry, is extrusion- molded. SOLUTION: In a highly viscous composition preparing process, any highly viscous composition will do as long as the solvent centent of the obtained highly viscous composition is smaller than that of the slurry obtained in a slurry preparing process or the slurry containing a solvent, a binder and a ceramic powder. In a solvent removing step, at least some part of the solvent is removed from the slurry. As the removing means, there is no specific limitation. For example, a spray drier method, a freeze dry method, a centrifugal separation method, a fiber press method or the like will do. By a method such as the centrifugal separation method. a filter press method or the like, by which only some part of the solvent can be removed, the highly viscous composition can be directly obtained without providing a solvent re-mixing step.

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 molded body of ceramic powder by an extrusion molding method.

[0002]

2. Description of the Related Art A ceramic sintered body is manufactured by firing a formed body of ceramic powder. Various methods such as one-way pressing, rubber pressing, and extrusion molding are used for molding ceramic powders. However, piezoelectric ceramics and dielectric ceramics used for electronic components are easily and inexpensively sheet-shaped. Extrusion molding is often used because a molded article is obtained.

Conventionally, in order to manufacture an extruded body made of a ceramic material, a method of kneading ceramic powder, a solvent such as water, a binder, a plasticizer, or the like with a kneader or a roll mill, and extruding the mixture is generally used. is there. However, the kneaded material used for extrusion molding needs to have a low water content, unlike the slurry used for wet compression molding. In order to obtain a kneaded product having a low water content, it is necessary to reduce the amount of the solvent. For this reason, it becomes difficult to uniformly mix the ceramic powder and the binder,
Many undissolved or undispersed binder materials are present in the molded article. When such a molded body is fired, undissolved matter and undispersed matter are burned off, so that pores are generated in the sintered body. If pores are present in the sintered body, the properties of the sintered body generally deteriorate. For example, a piezoelectric body having holes tends to cause problems such as an increase in impedance at a resonance point, and a dielectric having a hole applied to a capacitor tends to have a low withstand voltage.

In order to solve such a problem, for example, Japanese Patent Publication No. 58-51806 discloses a slurry obtained by adding 30 to 100% by weight of water to a ceramic powder, and forming a slurry having a water content of 15 to 25% by weight. After dewatering by a filter press or the like, an appropriate amount of a water-soluble binder and a plasticizer are added and kneaded to form a kneaded material, and a method of extruding the kneaded material has been proposed. In the examples of the publication, both the density of the compact and the density of the sintered compact are improved.

Japanese Patent Laid-Open Publication No. Hei 5-228912 proposes a method of preparing a slurry by mixing a ceramic powder, a binder and a solvent, and dehydrating the slurry with an ultracentrifuge to obtain a ceramic molded body. I have. In the example of the publication, it is stated that a piezoelectric ceramic having no pores of 5 μm or more was obtained.

The methods described in the above-mentioned JP-B-58-51806 and JP-A-5-228912 each disperse ceramic powder in order to uniformly mix the ceramic powder and the binder, and dehydrate the slurry. There is a characteristic in what you do.

[0007] Japanese Patent Application Laid-Open No. 1-111770 discloses that a cellulose derivative contained as a binder for a molded product contains 8 μl of a cellulose derivative present in 2 cc of a 0.1% by weight aqueous solution thereof.
Extrusion ceramic materials are described in which the amount of undissolved fibers of m to 200 μm is 1000 or less. According to the publication, this binder is obtained by adopting conditions under which a uniform and sufficient reaction is performed, such as using a sufficient amount of a reactant in a usual method for producing a cellulose derivative and selecting and using a necessary solvent. Is described. Since the binder undissolved component present in the molded body is burned out during binder removal or firing, voids are generated in the binder undissolved component existing portion, but the binder undissolved component described in the same publication is used. If a small amount of the ceramic material for extrusion molding is used, it is possible to reduce pores in the sintered body.

[0008]

As described in the above publications, in order to obtain a sintered body having a small number of pores by using an extrusion molding method, a ceramic powder and a binder are uniformly mixed. It is important to reduce the undissolved content of the binder. However, the means described in the above publications have the following problems.

In the method described in JP-B-58-51806, the ceramic powder and water are mixed uniformly by mixing the ceramic powder with a large amount of water to form a slurry. Is performed on a cake obtained by dewatering the slurry, so that it is difficult to uniformly mix the ceramic powder and the binder. Also,
Since the kneaded product of the cake and the binder has a high viscosity, it is difficult to remove undissolved components of the binder by filtration.

In the above-mentioned Japanese Patent Application Laid-Open No. 5-228912,
The mixture of ceramic powder and binder is in a slurry state,
That is, since the mixing is performed in a state containing a large amount of solvent, the uniformity of mixing is considered to be considerably high. However, since the dehydration molding method by ultracentrifugation is poor in mass productivity, industrial application is difficult. When the centrifugal separation method is used, it is easy to obtain a bulk-shaped molded body, but it is difficult to obtain a sheet-shaped molded body suitable for manufacturing electronic components.

In the above-mentioned Japanese Patent Application Laid-Open No. 1-111770,
The use of a water-soluble binder having a small amount of undissolved components is intended to suppress the generation of vacancies. The gazette states that
The smaller the amount of undissolved matter, the better, but it is extremely difficult and expensive, so there is a limit naturally.
Is described. Therefore, if the quality required for the ceramic molded body becomes higher, the presence of undissolved components again becomes a problem.

The present invention has been made in view of such circumstances, and it is an object of the present invention to prevent the occurrence of voids in a ceramic sintered body manufactured by using an extrusion molding method.

[0013]

This and other objects are achieved by any one of the following constitutions (1) to (11). (1) a slurry preparation step of obtaining a slurry containing a solvent, a binder and a ceramic powder; a high-viscosity composition preparation step of obtaining a high-viscosity composition for extrusion in which a part of the solvent has been removed from the slurry; A method for producing a ceramic extruded body, comprising: a molding step of extruding a high-viscosity composition for molding. (2) the slurry preparing step includes a binder solution preparing step of obtaining a binder solution by dissolving the binder in a solvent, and a binder solution slurrying step of mixing the binder solution and the ceramic powder to obtain a slurried binder solution. (1) The method for producing a ceramic extruded product according to the above (1). (3) The method for producing a ceramic extruded product according to the above (2), wherein the slurry preparation step includes a binder adding step of adding a binder to the slurry binder solution. (4) The above (2), wherein the slurry preparation step has a binder solution filtration step of filtering the binder solution.
Or (3) the method for producing a ceramic extruded product. (5) The method for producing a ceramic extruded product according to any one of the above (2) to (4), wherein the slurry preparation step includes a slurry filtration step of filtering the slurry binder solution. (6) The method according to (1), wherein the slurry preparing step includes a solvent slurrying step of mixing a solvent and a ceramic powder to obtain a slurrying solvent, and a binder mixing step of mixing the slurrying solvent and a binder. A method of manufacturing a ceramic extruded product. (7) The method for producing a ceramic extruded product according to the above (6), wherein the slurry preparation step includes a slurry filtration step of filtering the slurry-forming solvent after mixing the binder. (8) The method for producing a ceramic extruded product according to any one of (1) to (7), wherein the step of preparing the high-viscosity composition includes a solvent removing step of removing at least a part of the solvent from the slurry. (9) The method for producing a ceramic extruded product according to the above (8), wherein the step of preparing the high-viscosity composition has a solvent remixing step of adding a solvent after the solvent removing step. (10) The method for producing an extruded ceramic article according to the above (9), wherein a spray drier method is used in the solvent removing step. (11) The plasticizer is added in the slurry preparation step and / or the high viscosity composition preparation step.
0) The method for producing a ceramic extruded product according to any one of the above items.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a flow of steps in a manufacturing method according to the present invention. The production method of the present invention includes a slurry preparation step, a high-viscosity composition preparation step, and a molding step.

In the conventional extrusion molding method, a binder, a relatively small amount of a solvent, and ceramic powder are simultaneously kneaded to directly produce a high-viscosity kneaded material suitable for extrusion molding. Ceramic powder could not be uniformly mixed.

On the other hand, in the present invention, a slurry preparation step is provided. In this step, a slurry which is a low-viscosity mixture in which a binder and a ceramic powder are mixed with a relatively large amount of a solvent is prepared. In this slurry, almost no undissolved matter of the binder is generated except for insoluble components,
The state is such that the binder and the ceramic powder are uniformly mixed. Next, in a high-viscosity composition preparation step, a high-viscosity composition for extrusion is prepared by removing a part of the solvent from the slurry. By obtaining the high-viscosity composition for extrusion by such a procedure, the binder and the ceramic powder are uniformly mixed even in the high-viscosity composition for extrusion, so this is molded and fired. If this is the case, pores in the sintered body can be significantly reduced. In addition, if a binder solution filtration step or a slurry filtration step is provided, the binder undissolved components including insoluble components can be removed, so that pores can be further reduced.

FIG. 1 shows a preferred configuration of each step in the first embodiment.
And a second embodiment. Hereinafter, details of each embodiment will be described.

Slurry Preparation Step (First Aspect) The slurry preparation step in the first aspect is provided with a binder solution preparation step, a binder solution filtration step provided as needed, a binder solution slurrying step, and as needed. A binder adding step and an optional slurry filtering step are provided in this order.

Binder Solution Preparation Step In the binder solution preparation step, the binder is dissolved in a solvent to obtain a binder solution.

The solvent used in the present invention is not particularly limited, and may be appropriately selected according to the type of binder and ceramic powder used. However, water, alcohol, or a mixed solvent thereof is preferable, and water is particularly preferable, since the treatment after use is easy and the influence on the environment is small.

The type of the binder is not particularly limited, and may be appropriately selected from those soluble in the solvent used. When water or alcohol is used as the solvent, for example, at least one of a cellulose derivative, an acrylic binder, and the like can be preferably used. The properties of the binder are not particularly limited, and may be powdery or liquid.

The amount of the solvent with respect to the binder may be determined so that the binder solution has a relatively low viscosity. The use of a binder solution having a low viscosity facilitates uniform dispersion of the ceramic powder in the binder solution slurrying step. Also, since the mixing ratio between the ceramic powder and the binder is determined, the mixing ratio of the binder solution to the ceramic powder can be increased by making the binder solution low in viscosity (low concentration). Can be easily dispersed uniformly. However,
If the amount of the solvent is too large, the operation of removing the solvent from the slurry becomes troublesome, and the cost increases. For this reason, the concentration of the binder solution is preferably 0.1 to 3% by weight, more preferably 0.5 to 2% by weight.

As will be described later, by providing a binder adding step after the binder solution slurrying step, the amount of the binder with respect to the solvent in the binder solution preparing step can be reduced. For this reason, since the viscosity of the binder solution can be further reduced, uniform mixing of the ceramic powder and the binder is further facilitated. When the binder addition step is provided, the mixing ratio of the binder and the solvent in the binder solution preparation step may be determined based on the amount of the binder added in the binder addition step.

Binder Solution Filtration Step In the binder solution filtration step, undissolved components contained in the binder solution, for example, fibers which do not dissolve in the solvent are removed, and contaminants and the like are also removed. It is preferable to use a sieve as the filtering means. The opening of the sieve may be appropriately set so that undissolved components and foreign substances cannot pass through. Specifically, the opening of the sieve is preferably 10 to 5
The thickness may be 0 μm, more preferably 20 to 30 μm.

Binder Solution Slurry Step In the binder solution slurry step, a slurry binder solution is obtained. The slurry binder solution is a slurry obtained by mixing the binder solution and the ceramic powder.

When the binder addition step is not provided, the amount ratio of the ceramic powder and the binder solution mixed in the binder solution slurrying step is determined depending on the concentration of the binder solution, but the ceramic powder is uniformly dispersed. For this purpose, the amount of the binder solution with respect to 100 parts by weight of the ceramic powder is preferably 100 to 3000 parts by weight, more preferably 150 to 600 parts by weight.

Even when a binder adding step is provided,
That is, even when the whole amount of the binder is not added in the binder solution slurrying step, the amount of the binder solution with respect to 100 parts by weight of the ceramic powder in the binder solution slurrying step is preferably within the above range.

The amount of the binder with respect to the ceramic powder varies depending on the type of the ceramic powder, the type of the binder, and the use of the compact or the sintered body. Preferably 1 to 5 parts by weight, more preferably 2 parts by weight
４4 parts by weight.

The present invention can be applied to extrusion molding of various ceramic powders, and the effect of reducing pores in the sintered body is realized by using any of the ceramic powders. Extrusion molding may be applied, and as a ceramic material effective to reduce pores for improving properties, for example, has piezoelectricity, pyroelectricity, dielectric properties, soft magnetism, hard magnetism, etc. , Specifically, PbTiO ₃ (P
T), PbTiO ₃ -PbZrO ₃ (PZT), PZ
T is Pb (Mg, Nb) O ₃ , Pb (Y, Nb) O ₃ , P
b (Mn, Sb) O ₃ , Pb (Co, Nb) O _3, etc. as a solid solution, a three-component system, a Bi layered compound, a BaTiO ₃ system, S
Various materials such as rTiO ₃ type, CaTiO ₃ type, magnetoplumbite type ferrite such as Sr ferrite and Ba ferrite are exemplified. The average particle size of the ceramic powder is not particularly limited, but is usually about 1 to 10 μm.

The mixing means used in this step is not particularly limited, but generally a ball mill or a stirring blade mixer is used.

Binder addition step This step is provided when it is desired to further lower the concentration of the binder solution mixed with the ceramic powder in the binder solution slurrying step. If the required amount of binder is secured by adding a binder to the slurry in this step, the concentration of the binder solution used in the binder solution slurrying step can be lowered, so that the ceramic powder and the binder solution Uniform mixing becomes easier.

In this step, the amount of binder added to the slurry is not particularly limited, and is 0% by weight of the total binder.
It may be selected as needed from ultra-less than 100% by weight, but in order to sufficiently obtain the effect of providing this step, usually, 20% by weight or more, preferably 50% by weight or more of the total binder is added. Add in step. On the other hand, dissolving the binder in the slurry is more difficult than dissolving it in the solvent. Therefore, if the amount added in this step is too large, the uniformity of mixing of the binder and the ceramic powder will be slightly lower. For these reasons,
The amount added in this step is preferably 90% by weight or less of the total binder amount.

Slurry Filtration Step In the slurry filtration step, undissolved components of the binder, for example, fibrous materials that do not dissolve in the solvent, are removed from the slurried binder solution, and foreign substances mixed in the previous steps are removed. . It is preferable to use a sieve as the filtering means. Since the undissolved portion in the binder is generally larger than the ceramic powder, the opening of the sieve may be set so that the ceramic powder passes and the undissolved portion cannot pass. Specifically, the opening of the sieve is preferably 10 to 50 μm, and more preferably 20 to 30 μm.

When both the slurry filtering step and the binder adding step are provided, it is preferable that the slurry filtering step is provided after the binder adding step, as shown in FIG.

Since the slurry binder solution is more difficult to filter than the binder solution, if only one of the slurry filtration step and the binder solution filtration step is provided, the binder solution filtration step may be provided. preferable.

In the step of preparing the plasticizer-added slurry, a plasticizer may be added. Plasticizers are additives to facilitate extrusion.
The plasticizer may be added in this step, may be added in a high-viscosity composition preparation step described below, or may be added separately in both of these steps. However, if the plasticizer is added in this step, it is possible to generally mix more uniformly than in the case where it is added in the high viscosity composition preparation step. However, when added in this step, a part of the plasticizer may be lost due to decomposition or the like in the solvent removal step, so the addition step may be appropriately determined according to the type of the plasticizer. As the plasticizer, usually, at least one kind of glycerin and various other plasticizers is used. The preferred amount of the plasticizer varies depending on the type of the plasticizer, but is usually preferably 1 to 5 parts by weight, more preferably 2 to 4 parts by weight, per 100 parts by weight of the ceramic powder. If the amount of the plasticizer is too small, the effect becomes insufficient, and if the amount of the plasticizer is too large, the shape retention of the molded article tends to deteriorate.

The step of adding the plasticizer in the slurry preparation step is not particularly limited, but is usually added in the binder solution preparation step.

Slurry Preparation Step (Second Embodiment) In the first embodiment, first, a solvent and a binder are mixed to prepare a binder solution, and a ceramic powder is added to the binder solution to prepare a slurry. However, in the second embodiment, first, a slurry is prepared by mixing a solvent and ceramic powder, and a binder is added to the slurry. As described above, the mixing of the binder with the slurry is more difficult than the mixing of the binder with the solvent. Therefore, it is generally preferable to select the first embodiment. However, the mixing of the ceramic powder is easier in the solvent than in the binder solution, and good dispersibility can be obtained. Therefore, the second embodiment may be selected as necessary in consideration of the dispersibility of the ceramic powder and the solubility of the binder.

In the slurry preparation step in the second embodiment,
A solvent slurrying step, a binder mixing step, and a slurry filtration step provided as necessary are provided in this order.

Solvent Slurry Step In this step, a slurry slurry is obtained. The slurrying solvent is a slurry obtained by mixing the solvent and the ceramic powder. The ratio of the solvent and the ceramic powder to be mixed in this step is determined so that the ceramic powder can be uniformly dispersed and, when the binder corresponding to the amount of the ceramic powder is mixed, uniform mixing is possible. I just need. The amount of the solvent based on 100 parts by weight of the ceramic powder is preferably 100 to 3000 parts by weight,
More preferably, it is 150 to 600 parts by weight.

Binder Mixing Step In this step, the slurrying solvent and the binder are mixed. Since the mixing ratio between the ceramic powder and the binder is determined, the ratio between the amount of the slurrying solvent and the binder in this step may be determined according to the amount of the ceramic powder in the slurrying solvent. However, usually, in this step, mixing is performed so that the concentration calculated from the amount of the solvent and the amount of the binder is preferably 0.1 to 0.3% by weight, more preferably 0.5 to 2% by weight. desirable.

Slurry Filtration Step This step is the same as the slurry filtration step in the first embodiment except that the slurrying solvent after the addition of the binder is to be filtered.

Addition of Plasticizer The addition of the plasticizer in the second embodiment is the same as that in the first embodiment. However, in the second embodiment, usually, a plasticizer is added in the solvent slurrying step.

Step of Preparing High Viscosity Composition (First Embodiment and
Second Embodiment) In the high-viscosity composition preparing step, the high-viscosity composition for extrusion molding has a lower solvent content than the slurry obtained in the slurry preparing step, that is, the slurry containing the solvent, the binder and the ceramic powder. I just need to get it. As shown in FIG. 1, a preferred configuration of the high-viscosity composition preparing step has at least a solvent removing step and, if necessary, a solvent remixing step. This preferred configuration is common to the first embodiment and the second embodiment. Hereinafter, each step will be described.

Solvent Removal Step In this step, at least a portion of the solvent is removed from the slurry. Means for this is not particularly limited, for example, spray dryer method, freeze drying method, centrifugal separation method,
What is necessary is just to select from a filter press method etc. In a method capable of removing only a part of the solvent, such as a centrifugal separation method or a filter press method, it is possible to directly obtain a high-viscosity composition without providing a solvent remixing step. However, the centrifugal separation method and the filter press method are not suitable for mass production, and it is particularly difficult to remove the solvent from the slurry containing the binder by the filter press method. For this reason, a method of drying the slurry once is preferable, and a spray dryer method is particularly preferable. Various conditions in the spray dryer method, for example, the number of revolutions of the spray turbine, the hot air temperature, the slurry supply speed, and the like may be appropriately determined according to the components of the slurry, the scale of the spray dryer, and the like.

[0046] In solvent remixing step the solvent removal step, using a spray dryer method, when the dried product was almost completely remove the solvent from the slurry, in order to obtain for extrusion high viscosity compositions, solvents Need to be added again. A solvent remixing step is provided for this. Even when the slurry is not completely dried in the solvent removing step, a solvent remixing step is provided if the viscosity of the composition for extrusion molding is too high.

The ratio of the solid content to the solvent in the high-viscosity composition for extrusion may be the same as that of the conventional kneaded product for extrusion. For example, the amount of the solvent per 100 parts by weight of the solid content is preferably Is 10 to 20 parts by weight, more preferably 13 to 17 parts by weight.

The kneading means used in this step is not particularly limited, but usually a kneader or a high-speed mixer is used.

The solvent used in this step is generally the same as the solvent used in the slurry preparation step, but may be any other solvent that can dissolve the binder used.

As described above, a plasticizer may be added in the step of preparing the high-viscosity composition.

Molding Step (First and Second Embodiments) In this step, the high-viscosity composition for extrusion molding is extruded to obtain molded articles of various shapes such as plate, rod and honeycomb. Extrusion molding conditions may be the same as those of general extrusion molding, and may be appropriately set according to the type and properties of the ceramic powder, the use of the molded body, and the like.

The molded body obtained in the molding step is usually fired to be a sintered body.

[0053]

EXAMPLES Examples of the first embodiment Manufacturing starting materials for ceramic powders include lead oxide (PbO), strontium carbonate (SrCO ₃ ), titanium oxide (TiO ₂ ), bismuth oxide (Bi ₂ O ₃ ), and manganese carbonate. Using (MnCO ₃ ) and niobium oxide (Nb ₂ O ₅ ), these powders have compositions (atomic ratios) after firing of (Pb _0.69 Sr _0.25 Bi _0.02 ) (T
i _0.95 Mn _0.02 Nb _0.03 ) O ₃ .
Next, the mixture was wet-mixed in pure water by a ball mill for 15 hours. Next, the mixture was sufficiently dried, pressed, and calcined at 900 ° C. for 2 hours. The obtained calcined product was wet-pulverized by a ball mill for 15 hours, and then dried again to obtain a granular ceramic powder. The average diameter of the primary particles of the granular ceramic powder was 1.5 μm.

Binder Solution Preparing Step Cellulose derivative powder (trade name: Metroose 60SH4000F, manufactured by Shin-Etsu Chemical Co., Ltd.) was used as a binder, and pure water was used as a solvent. After stirring, the stirring was continued for about 12 hours to obtain a binder solution. The concentration of the binder solution was 1.0% by weight.

Binder Solution Filtration Step The above binder solution is applied to a metal mesh (opening 22 μm).
To remove undissolved substances in the solution. The amount of undissolved matter (fibrous) was about 50 ppm of the binder.

Binder Solution Slurry Step The above ceramic powder was added while stirring the filtered binder solution to prepare a slurry binder solution. The amount of the binder solution relative to 100 parts by weight of the ceramic powder was 300 parts by weight.

Solvent Removal Step The slurry was dried with a spray drier to obtain granules in which the ceramic powder and the binder were uniformly mixed. The operating conditions of the spray dryer were a spray turbine rotation speed of 6000 rpm, a hot air temperature of 180 ° C., and a slurry supply rate of 0.7 liter / min.

Solvent Remixing Step The above granules, plasticizer (glycerin and trade name Ceramisol C-08) and a solvent (pure water) were kneaded by a mixer to prepare a high-viscosity composition for extrusion molding. Granules 10
The amount of each component relative to 0 parts by weight was as follows: 2.6 parts by weight of plasticizer (ceramisol: glycerin = 3.6: 50), solvent 1
It was 4.6 parts by weight.

Forming Step The above high-viscosity composition for extrusion was extruded to obtain a sheet-like molded product having a width of 50 mm and a thickness of 0.6 mm.

Firing Step The molded body was heated to 400 ° C. to remove the binder, and then placed in a magnesia sealed sagger and fired at 1200 ° C. for 4 hours to obtain a sintered body sample.

COMPARATIVE EXAMPLE The same ceramic powder, binder, solvent and plasticizer as in the above example were used.

In this comparative example, a ceramic powder and a binder were dry-mixed with a mixer, and a mixture of a solvent and a plasticizer was sprayed and kneaded into the obtained mixture.
A high viscosity composition for extrusion was prepared. The amounts of the binder and the plasticizer with respect to the ceramic powder were the same as in the above example. The amount of the solvent with respect to the ceramic powder was the same as in the solvent remixing step in the above example.

The obtained high-viscosity composition was molded and fired in the same manner as in the above example to obtain a sheet-shaped sintered body sample.

[0064] For the sintered body samples prepared respectively in characterization Examples and Comparative Examples, the following evaluations were carried out.

The number of vacancies After each sample was mirror-polished, the number of vacancies having a diameter of 20 μm or more contained in an area of 2 cm × 2 cm at the center of the main surface was examined by an optical microscope. The measurement is performed for each sample, ten samples at a time, and the total number of holes (the number of holes in a total area of 40 cm ² )
I asked. As a result, the total number of holes was 65 in the example sample and 171 in the comparative sample, and it was confirmed that the number of holes in the sintered body was significantly reduced by the present invention.

Defective rate Each sample was lapped and polished to a thickness of 246 μm, an Ag electrode for polarization treatment was printed and dried at 120 ° C.
Polarization was performed by applying an electric field of 5 kV / mm in silicone oil at 120 ° C. for 30 minutes. Next, after removing the Ag electrode with acetone, the sample was diced and cut so as to have a main surface size of 7.0 mm × 7.5 mm, and further, an Ag electrode having a diameter of 1 mm was formed on both main surfaces by vapor deposition. And a sample for characteristic evaluation.

After leaving these samples for characteristic evaluation at room temperature for 24 hours, a thickness longitudinal vibration 3 was measured using an impedance analyzer (HP-4194A, manufactured by Hewlett-Packard Company).
Check the impedance (R0) at the resonance point of the second harmonic,
The reject rate was determined. The number of measurements was 100 for each sample, and those with an R0 exceeding 20Ω were regarded as defectives, and the ratio was defined as the defective rate. As a result, the defective product rate was 0% in the example sample and 4.% in the comparative example sample.
It was 0%, and it was confirmed that the R0 defect rate also decreased as the number of vacancies decreased.

Incidentally, sintered body samples were prepared according to the second embodiment, and the above-mentioned characteristics were also evaluated. As a result, a decrease in the number of vacancies and a decrease in the defective rate were found in comparison with the comparative example. .

[0069]

According to the present invention, the ceramic powder and the binder can be uniformly mixed in the extrusion molding method.
Voids in the sintered body can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a flow of steps in the method of the present invention.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takuji Shiba 1-13-1 Nihonbashi, Chuo-ku, Tokyo Inside TDK Corporation (72) Inventor Matsumi Watanabe 1-13-1 Nihonbashi, Chuo-ku, Tokyo Tー Decay Corporation

Claims (11)

[Claims] A slurry preparation step of obtaining a slurry containing a solvent, a binder and ceramic powder; a high viscosity composition preparation step of obtaining a high viscosity composition for extrusion molding in which a part of the solvent is removed from the slurry; And a molding step of extruding the high-viscosity composition for extrusion molding. 2. The slurry preparing step includes a step of preparing a binder solution by dissolving the binder in a solvent, and a step of preparing a binder solution by mixing the binder solution and the ceramic powder to obtain a binder solution. 2. The method of manufacturing a ceramic extruded product according to claim 1, comprising the steps of: 3. The method for manufacturing a ceramic extruded product according to claim 2, wherein said slurry preparing step includes a binder adding step of adding a binder to said slurry binder solution. 4. The method for producing a ceramic extruded product according to claim 2, wherein the slurry preparing step includes a binder solution filtering step of filtering the binder solution. 5. The method for producing a ceramic extruded product according to claim 2, wherein the slurry preparing step includes a slurry filtration step of filtering the slurry binder solution. 6. The slurry preparing step includes a solvent slurrying step of mixing a solvent and a ceramic powder to obtain a slurrying solvent, and a binder mixing step of mixing the slurrying solvent and a binder. Of manufacturing extruded ceramics. 7. The method for producing a ceramic extruded product according to claim 6, wherein the slurry preparing step includes a slurry filtration step of filtering the slurry-forming solvent after mixing the binder. 8. The method for producing a ceramic extruded product according to claim 1, wherein the step of preparing the high-viscosity composition includes a solvent removing step of removing at least a part of the solvent from the slurry. 9. The method for producing a ceramic extruded product according to claim 8, wherein the step of preparing a high-viscosity composition has a solvent remixing step of adding a solvent after the solvent removing step. 10. The method according to claim 9, wherein a spray drier method is used in the solvent removing step. 11. A plasticizer is added in a slurry preparation step and / or a high viscosity composition preparation step.
10. The method for manufacturing a ceramic extruded product according to any one of the above items 10.