JPH09328366A - Production of ceramic sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an excellent ceramic sheet having homogeneous texture and uniform thickness by using a clay produced by adding methyl cellulose as a binder and a fatty acid ester as a plasticizer to powder of ceramic raw material. SOLUTION: Clay for the ceramic sheet is produced by adding methyl cellulose as a binder and a partially esterified glycerol fatty acid ester as a plasticizer to a powdery ceramic raw material and kneading the mixture. The ceramic sheet is produced by the extrusion molding of the clay. As an alternative method, a propylene glycol fatty acid ester is used as the plasticizer. The amount of the plasticizer is preferably about 0.2-5 pts.wt. based on the ceramic raw material. An excellent ceramic sheet can be produced since the slippery between the particles of the ceramic raw material powder in the clay is improved by the addition of the plasticizer to decrease the extrusion resistance difference in the lateral direction of the sheet in extrusion molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ceramic sheet.

[0002]

2. Description of the Related Art A conventional method for producing a ceramic sheet having a thickness of 0.1 to 1.0 mm is as follows.
Add an aqueous solution of methyl cellulose as a binder and glycerin or propylene glycol as a plasticizer,
A production method in which the kneaded kneaded material is extruded into a sheet at a pressure of 10 to 100 kg / cm ² , and then dried, punched and fired is generally used.

[0003]

However, in the conventional production method using a binder and a plasticizer, slippage between the ceramic raw material powder particles in the kneaded material is poor in a high viscosity state suitable for extrusion molding, and as a result, The sheet quality after extrusion was not stable, and the production efficiency was not good.

That is, in the above-mentioned conventional example, in the case of extrusion molding, since the resistance applied to the kneaded clay at the time of extrusion is different between the center portion and both end portions in the width direction of the sheet, the speed and amount of the kneaded material to be extruded are different, As a result, in the next drying step, the thickness of both end portions of the sheet becomes thinner than that of the central portion, or both ends are wavy, so that a partial crack occurs. Therefore, in the actual production process, both ends were largely cut to remove the defective portion.

An object of the present invention is to provide a high quality ceramic sheet having stable quality by using a kneaded material in which sliding between ceramic raw material powder particles is improved.

[0006]

To achieve this object, the method for producing a ceramic sheet of the present invention is to add a partially esterified glycerin-based fatty acid ester as a plasticizer in addition to the binder. . The plasticizer of the present invention improves the slippage between the ceramic raw material powder particles in the kneaded material, and can reduce the difference in extrusion resistance in the width direction of the sheet during extrusion molding, thus reducing the thickness difference between both ends and the center. An excellent ceramic sheet is obtained.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION According to the first aspect of the present invention, in addition to a binder, a partially esterified glycerin-based fatty acid ester is added and kneaded as a plasticizer to a ceramic raw material powder to form a kneaded material. This esterified glycerin-based fatty acid ester controls the hydrophilicity of the ceramic raw material, improves the sliding between the ceramic raw material powder particles in the kneaded clay, and obtains a high-viscosity kneaded clay suitable for extrusion molding. You can

According to the second aspect of the present invention, glycerin fatty acid ester or propylene glycol fatty acid ester is used as the partially esterified glycerin fatty acid ester added as a plasticizer. Is for improving the slippage between the ceramic raw material powder particles in the high-viscosity kneaded clay suitable for extrusion molding.

According to a third aspect of the present invention, the amount of the plasticizer to be added is set to 0.2 to 5 parts by weight based on the ceramic raw material. This is a small amount in the kneaded clay. It improves the slipperiness between the ceramic raw material powder particles.

Embodiments of the present invention will be described below. (Embodiment 1) First, a piezoelectric ceramic raw material, methyl cellulose as a binder, and (Table 1),
Various plasticizers shown in (Table 2) were each weighed, an appropriate amount of pure water was added and mixed, and an extrusion-molded kneaded material was prepared using a vacuum heating kneader.

[0011]

[Table 1]

[0012]

[Table 2]

A molding pressure of 30 is used by using an extruder equipped with a die capable of extruding the kneaded material into a sheet width of about 90 cm.
A green sheet having a thickness of 0.50 mm and a weight of 50 kg / cm ² was formed, and then dried by a belt dryer at a temperature of 40 to 80 ° C. to obtain a ceramic sheet. The amount of addition used at this time was 4 parts by weight of methyl cellulose and 3 parts by weight of plasticizer with respect to the raw material powder. This is intended to work effectively for a high-viscosity kneaded clay for extrusion molding with a small amount of addition, and to prevent the ceramics from being adversely affected during firing. In addition, some of them were made out of the claims of the present invention in order to know the limit value, and the evaluation results are shown in (Table 1) and (Table 2). The quality of the molded product in the table is the surface roughness of the ceramic sheet, and the flatness thereof is visually evaluated for quality, and the brittleness or hardness of the ceramic sheet is determined by punching in the next step. Since it affects the process, the quality was evaluated by feeling the tentacle. In addition, the effective width in the table is a percentage of the effective width of the sheet in which the thickness variation of the ceramic sheet is within a range of ± 0.01 mm. That is, 0.
± 0.
The distance from both ends of the ceramic sheet at which a difference of 01 mm or more began to be measured was calculated by dividing by the molding width of 90 cm. In this evaluation, a ceramic sheet having a length of about 5 m was prepared for each composition material, and the lengthwise direction was divided into 10 parts, and the minimum values were shown in (Table 1) and (Table 2). For comparison, a ceramic sheet using a conventional plasticizer was also processed and evaluated in exactly the same manner as in the present invention.

As is clear from (Table 1), the partially esterified glycerin fatty acid ester and propylene glycol fatty acid ester of the present invention were added from the kneaded clay to which glycerin or propylene glycol not esterified was added to the plasticizer. The effective width is large.
That is, it can be seen that a highly accurate ceramic sheet with a small thickness variation can be obtained. Further, the completely esterified product was not practical because the ceramic sheet after drying was brittle and cracked in the punching process in the next step, and the surface smoothness of the ceramic sheet was lowered. When the amount of plasticizer added exceeded 5 parts by weight, the effective width decreased. This is thought to be due to the increase in tackiness of the kneaded material and the decrease in viscoelasticity. If the amount of plasticizer added is less than 0.2 parts by weight, the ceramic sheet will become hard and difficult to handle and punch. Is not preferable. Therefore, in order to obtain a preferable ceramic sheet, the addition amount of the plasticizer is 0.
It is necessary to limit the amount to 2 to 5 parts by weight. Further, although the present invention uses the piezoelectric ceramic material, it can be applied to various ceramic raw materials such as PTC thermistor material, NTC thermistor material, and zinc oxide material.

The term "partially esterified" means that one or two hydroxyl groups in the glycerin group are substituted with fatty acids.

[0016]

As described above, according to the present invention, when a kneaded material for extrusion molding is prepared, in addition to methylcellulose as a binder, ceramic raw material powder is further used as a plasticizer, or partially esterified glycerin or By adding the fatty acid ester of propylene glycol, it is possible to provide an excellent ceramic sheet that is homogeneous and has a small thickness variation.

Claims (3)

[Claims] 1. A method for producing a ceramic sheet, comprising adding methyl cellulose as a binder and partially esterified glycerin-based fatty acid ester as a plasticizer to a ceramic raw material, and extruding a kneaded kneaded material. 2. The method for producing a ceramic sheet according to claim 1, wherein the partially esterified glycerin fatty acid ester added as a plasticizer is glycerin fatty acid ester or propylene glycol fatty acid ester. . 3. The method for producing a ceramic sheet according to claim 1, wherein the added amount of the plasticizer is 0.2 to 5 parts by weight based on the ceramic raw material.