JPS6259070B2 - - Google Patents

Description

[Detailed description of the invention]

Fired ceramic sheets can be broadly classified into porous sheets and dense sheets, depending on the amount of pores they have inside the sheet. The former is used for insulation, soundproofing, etc., while the latter is used for IC packages, thin film magnetic materials, and electroceramics such as ceramic capacitors. The first manufacturing process for fine ceramic sheets
As shown in the figure. Dense fired ceramic sheets have conventionally been produced by a doctor blade method, an extrusion method, a roll method, and a dry press method. These manufacturing methods can be roughly divided into: (1) using organic solvents for ceramic raw material powder;
A method of manufacturing sheets by combining an organic polymeric binder, a plasticizer, and a lubricant (doctor blade method). (2) A method of manufacturing a sheet by mixing ceramic raw material powder with a water-soluble organic polymer or synthetic resin emulsion, a plasticizer, and a lubricant (extrusion method, roll method, dry press method). There are the above two methods. However, with conventional sheet manufacturing methods, the thickness and dimensions of the sheet that can be obtained are limited depending on the manufacturing method. Selected. The main points of the conventional method for manufacturing dense fired sheets are described below. 1 Doctor blade method A wet method in which a solvent is combined with an organic polymer, a plasticizer, a lubricant, and ceramic raw material powder. The slurry is poured onto a flat polyethylene sheet and adjusted with a doctor blade to form a raw sheet of a certain thickness. This is the way to get it. Since this method uses a large amount of organic solvent, there are many problems such as manufacturing cost and solvent recovery. Furthermore, when obtaining a thick sheet, it is practically impossible to obtain a thickness of 1 mm or more due to non-uniform density of the green sheet due to sedimentation of ceramic particles and warping of the sheet during drying. 2 Extrusion method This is a semi-wet molding method using a water-soluble polymer, plasticizer, and lubricant to extrude a flat plate of a predetermined shape. Due to the structure of the extrusion molding machine, this method has a limit on the width of the shape, the thickness is about 0.15 to 1.0 mm, and it requires a large amount of organic polymer to be added. 3 Roll method A rolled sheet method using a roll method. Generally, a water-soluble polymer or synthetic resin emulsion, a plasticizer, and a lubricant are combined to form a sheet in a semi-wet process, with a thickness of about 0.15 to 0.4 mm. Since the molding process is repeated several times using a heating roll method, manufacturing costs are high and a large amount of organic polymer material is required. 4 Dry press method Generally, a mechanical press or hydraulic press is used.
A water-soluble polymer, a plasticizer, a lubricant, and ceramic raw material powder are mixed, and the powder is granulated using a spray dryer, and the powder is poured into a designated mold.
Pressure molding is performed at a molding pressure of 1 ton/cm ² . This method is used to manufacture small ceramic sheets, but it is limited by the maximum molding pressure of the press molding machine,
Manufacturing problems such as handling of the green sheet make it unsuitable for forming large area sheets.
Furthermore, thin sheets with a thickness of 0.18 mm or less cannot be formed. The main points of each manufacturing method have been described above, and the characteristics can be summarized as shown in Table 1 and FIG. 2.

[Example 1]

High-purity alumina powder (AL-160SG manufactured by Showa Light Metal Co., Ltd., A ₂ O ₃ content of 99.5% or more) was used as a raw material for fine ceramics, and 100 parts by weight of the alumina and 40 parts by weight of water were put into a vacuum mixer and peptized. As an agent, Cerna D-305 (Chukyo Yushi Co., Ltd., ammonium salt of acrylic oligomer, active ingredient)
40%) and 0.3 parts by weight (solid content equivalent) of Homeless P-46 (Meisei Chemical Industry Co., Ltd.) as an antifoaming agent.
A fatty acid ester derivative) was added thereto and mixed with stirring to prepare an alumina slurry. On the other hand, the pulp used was natural pulp for general papermaking (NBKP/LBKP-2/8 mixed pulp), and 0.5 parts by weight of pulp (absolutely dry weight) and 5 parts by weight of water were tested for 100 parts by weight of alumina powder. In addition, a dispersant is added as a dispersant to promote pulp beating (Kumagai Riki, PFI Mill).
TLN (Meisei Chemical Industry Co., Ltd., β-naphthalene sulfonic acid formalin condensate ammonium salt)
0.02 parts by weight (in terms of solid content) was added and beaten under reduced pressure for 20 minutes to obtain pulp with a water content (csf) of 70 ml. This pulp was diluted by adding 155 parts by weight of water. The previously obtained alumina slurry and pulp slurry were stirred and mixed in a vacuum container to form a uniform alumina-pulp slurry, and then M-1430 (Meisei Chemical Industry Co., Ltd., anionic polyacrylamide partial hydrolyzate, 0.5 parts by weight (in terms of solid content) of 10% active ingredient was added and stirred for 5 minutes. Next, RC-104 (Meisei Chemical Industry Co., Ltd., cationic polyacrylamide resin, active ingredient 15
%) 0.3 parts by weight (in terms of solid content) was added and stirred as above. This slurry was suction-dehydrated and paper-formed using a TAPPI standard square sheet machine (manufactured by Toyo Seiki) to obtain a raw ceramic sheet with a length of 250 mm, a width of 200 mm, and a thickness of 2.6 mm. The green sheet was dehydrated and pressed under a pressure of 10 kg/cm ² for 30 minutes in a wet state, and then primarily dried in an oven at 60° C. for 60 minutes. Subsequently, semi-wet pressing was carried out using a roll press (processing speed 5 m/min) with a linear pressure of 100 kg, followed by final drying at 80° C. for 2 hours. After cutting the homogeneous sheet into a predetermined size, it was fired at a high temperature of 1600°C using a high-temperature gas furnace (fuel: LNG). The firing conditions are shown in FIG. The degree of Segel cone collapse was SK31. After boiling the fired sheet for 3 hours, the water absorption rate was measured. The water absorption rate was 0.20%. [Example 2] To 100 parts by weight of the alumina used in Example 1, the same viscous beaten pulp as in Example 1 (water content 50 ml) was added.
1.0 part by weight (absolutely dry weight) of cf) was added, and the same treatment as in Example 1 was carried out to obtain a fired sheet. The water absorption rate was 0.35%. (Comparative Example 1) A fired sheet was obtained in the same manner as in Example 2 using pulp having a water content different from that in Example 2. The pulp is similar to the pulp used in general papermaking.
Pulp with a water content (csf) of 360 ml was used. The water absorption rate of the fired sheet was 1.61%. (Comparative Example 2) A fired sheet was obtained in the same manner as in Example 2 using pulp having a water content different from that in Example 2. The pulp is slightly beaten and has a water content (CSF) of 100.
ml of pulp was used. The water absorption rate of the fired sheet is 1.30
It was %. Next, we investigated the effects of chemicals and found that when a synthetic resin emulsion or styrene-butadiene copolymer was added in addition to two types of organic polymers, the strength and flexibility of the green sheet improved, making it easier to handle the green sheet. It got easier. [Example 3] After adding both M-1430 and RC-104 in Example 1, 4.0 parts by weight (solid) of Meikaset N-100 (Meisei Chemical Co., Ltd., vinyl acetate resin, active ingredient 40%) was added. ) was added and treated in the same manner as in Example 1. The water absorption rate of the fired sheet is
It was 0.23%. [Example 4] As in Example 3, 4.8 parts by weight (solid content equivalent) of Naugatex 2001 (Sumitomo Naugatak Co., Ltd., styrene-butadiene copolymer, active ingredient 42%)
A sheet was prepared. The water absorption rate of the fired sheet was 0.30%.

[Brief explanation of the drawing]

Figure 1 is a process diagram showing the conventional manufacturing process of fine ceramic sheets, Figure 2 is a graph showing the relationship between thickness and width of fired sheets that can be manufactured by various conventional sheet manufacturing methods, and Figure 3 is Graphs showing the structure of ceramics produced by various conventional molding methods, Figure 4 is a process diagram showing the manufacturing process of fine ceramic sheets according to the present invention, and Figure 5 is a thermal decomposition curve of organic polymers added during molding. FIG. 6 is a graph showing the firing curve of an alumina sheet in one embodiment of the present invention.

Claims (1)

[Scope of Claims] 1. A fixing agent is added to an aqueous composition containing 100 parts by weight of fine ceramic raw material powder and 0.5 to 2.9 parts by weight of natural pulp and/or synthetic pulp having a water content (CSF) in the range of 95 to 10 ml. Adding cationic and anionic water-soluble organic polymers as
After defoaming and stirring and mixing in a reduced pressure or normal pressure container,
A ceramic sheet characterized by forming a ceramic sheet by a paper-making method, wet-pressing the sheet, and then firing it under the same conditions as general ceramics to obtain a dense fine ceramic fired sheet. Manufacturing method. 2. The method for producing a ceramic sheet according to claim 1, which comprises adding a binder and/or a plasticizer to the aqueous composition.