JP2788970B2 - Insert for ceramic firing - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interposed sheet for ceramic firing, which can fire a ceramic molded body with good surface smoothness and can easily collect formed fired bodies individually.

2. Description of the Related Art In the firing process of ceramics, it is necessary to take measures to prevent the ceramic molded bodies from binding to each other or between the ceramic molded body and its firing base so that individual recovery of the fired bodies becomes impossible. As a measure, the method of spraying inorganic powders such as alumina and zirconia, in addition to the following binding problems,
Since there is a problem of dust and irregularities such as warpage and undulation of the fired body due to uneven distribution, a method of interposing sheets has been proposed.

Conventionally, as the interleaving sheet, a sheet in which an inorganic powder is dispersed and contained in a polymer film forming material has been known (Japanese Patent Publication No.
60-88991). However, there was a problem that the inorganic powder was bound to the formed fired body by firing. Therefore, it is necessary to remove the bound inorganic powder by treating the obtained fired body with sand blasting or the like, and there is a problem that the surface smoothness of the fired body is significantly reduced.

Therefore, an object of the present invention is to develop an interposed sheet in which the inorganic powder does not bind to the fired body by firing.

Means for Solving the Problems The present invention has achieved the above-mentioned object by making an interposed sheet of a type which is fired at the time of firing a ceramic molded body to be processed, and causing the fired sheet to capture inorganic powder. It is.

That is, the present invention is a sheet interposed in order to prevent binding when firing the ceramic molded body, the small ceramic powder fired when firing the ceramic molded body is preserved by an organic binder. Inside the sheet or /
Further, the present invention provides an interleaving sheet for ceramic firing, characterized in that large inorganic powders that do not melt at the firing temperature of the ceramic molded body are dispersed and held on the surface.

The large-sized inorganic powder placed in or on the surface of the sheet made of small-sized ceramic powder, while exerting the function as a spacer, the sheet made of small-sized ceramic powder is also fired at the time of firing the ceramic molded body, and the large-sized inorganic powder is fired. The inorganic powder is captured to prevent the ceramic molded body from binding to the fired body.

Illustrative Components of the Invention The ceramic firing interleaving sheet of the present invention uses small-sized ceramic powder and large-sized inorganic powder.

The small ceramic powder to be used may be one that is fired when firing the ceramic molded body to be treated.
Generally, alumina, zirconia, aluminum nitride,
A powder composed of silicon nitride, barium trioxide titanate, or the like is used. The particle size of the powder is 0.01% based on the average particle size.
1010 μm, especially 0.1-5 μm, is suitable. When forming the small-sized ceramic powder into a sheet, a firing aid such as magnesia, calcia, or silica may be added as appropriate according to the ceramic molded body to be treated, if necessary, in order to enhance the firing property.

As the large inorganic powder, one that does not melt at the firing temperature of the ceramic molded body to be treated is used. In general, the materials exemplified as the small-sized ceramic powder are used, and are appropriately selected and used so as not to react with the ceramic molded body to be treated during firing. The particle size of large inorganic powders is 20 to 300 μm,
100100 μm is appropriate. Spherical powder is more preferably used than crushed powder. The amount of the large inorganic powder used is 2 to 200 parts by weight, preferably 5 to 100 parts by weight of the small ceramic powder.
~ 50 parts by weight is suitable. If the amount used is less than 2 parts by weight, the effect of preventing binding to the ceramic molded article is poor, and
If the amount exceeds the weight part, the interposed sheet formed becomes poor in flexibility and easily broken.

The preferred composition of the small ceramic powder and the large inorganic powder in the interposed sheet has a surface roughness of 0.4 μm based on Ra according to JIS B 0601, after firing.
The composition is as described above. Its surface roughness (Ra) is 0.4μm
If the amount is less than the above, the ceramic molded body may be poor in binding prevention. From this point, a large inorganic powder used particularly preferably has an average particle diameter of 5 to 200 times that of a small ceramic powder.

The ceramic firing interposed sheet of the present invention is obtained by dispersing and holding large inorganic powder in or on the surface of a sheet obtained by shaping small ceramic powder with an organic binder. 1 and 2 show examples. 1 is a large inorganic powder, 2 is a small ceramic powder, and 3 is an organic binder. FIG. 3 shows still another embodiment.
In this case, a reinforcing layer 4 made of paper or the like is provided in order to enhance the handleability.

The organic binder used may be any as long as it can keep the ceramic powder in a sheet form. Generally, organic polymers commonly used for green sheets, such as polyvinyl butyral, acrylic polymers, and styrene polymers, are used. The amount of the organic binder to be used may be appropriately determined depending on the properties of the sheet to be formed and the like, but is generally 20 to 2,000 parts by weight per 100 parts by weight of the small ceramic powder.

The formation of the interposed sheet may be performed, for example, by casting a mixture of one or more small ceramic powders, large inorganic powders, and an organic binder by a doctor blade method or the like, an extrusion molding method, a roll rolling method, or the like. It can be performed by forming a sheet in a simple manner. that time,
The purity between the inorganic compositions except for the large-sized inorganic powder in the obtained interposed sheet is adjusted so as to be close to that of the ceramic molded body to be treated, and the firing conditions of the interposed sheet and the ceramic molded body to be treated are determined. It is more preferable to increase the identity. Incidentally, when the purity between the inorganic compositions in the ceramic molded body to be treated is 96%, the purity between the inorganic compositions in the interposed sheet is 94 to 98%, especially 95.8 to 96.2.
% Is preferable.

When preparing the above mixture, if necessary, suitable additives such as a solvent, a peptizer or a dispersant, a plasticizer, a wetting agent, a release agent, and an antifoaming agent may be blended. The large inorganic powder may be previously blended with the mixture as described above, formed into a sheet, and dispersed and held in the sheet (FIG. 1).
The unmixed mixture may be formed into a sheet and then sprayed and held on the surface of the formed sheet (FIG. 2), or both may be dispersed and held on the surface of the sheet by using both of the above methods. In the case where the molded body of the ceramic fired body to be processed is liable to be deformed or cracked due to the shrinkage of the interposed sheet during firing, for example, a polymer powder that is thermally decomposed without melting during firing, such as a thermosetting resin Mixing powder or the like into the interleaving sheet is effective in solving the above problem.

The thickness of the interposed sheet to be formed is determined according to the ceramic molded body to be processed. Generally, it is 50 to 500 μm. If the thickness of the interposed sheet is too small, it becomes difficult to handle due to insufficient strength or the like. If the thickness is too large, deformation problems such as undulation of the fired body are liable to occur when fired while being interposed between ceramic molded bodies.

The ceramic firing interposed sheet of the present invention is, for example, for firing a ceramic molded body formed into a sheet form or the like, between the molded body and its firing table, between the molded bodies arranged on the firing table, It is applied between the stacked moldings. At this time, if the interposed sheet does not have an adhesive fixing force, the adhesive fixing force may be applied as necessary by attaching an adhesive layer or the like. The firing conditions may be appropriately determined according to the ceramic molded body to be processed. Organic components such as an organic binder disappear by thermal decomposition or the like by firing, and the interposed sheet is fired together with the ceramic molded body to be processed. At this time, the large inorganic powder is captured by the fired body of the interposed sheet and acts as a spacer while preventing transfer or binding to the ceramic molded body, and serves as a spacer between the fired bodies of the ceramic molded body to be treated. To prevent individual binding of the fired body.

Effect of the Invention The ceramic firing interposed sheet of the present invention is such that when firing the ceramic molded body to be treated, the ceramic molded body itself is also fired to capture large inorganic powders. It is possible to prevent the large inorganic powder as a spacer from binding to the fired body. As a result, it is not necessary to remove inorganic powder having a larger particle size than the fired body after firing by a method such as polishing, and a fired body having excellent surface smoothness can be obtained.

Example 1 Fifteen parts of fused alumina powder having an average particle diameter of 50 μm (parts by weight, the same applies hereinafter), 75 parts of active alumina powder having an average particle diameter of 1.5 μm, 9 parts of styrene / butylene / styrene copolymer, silica 1
Parts, magnesia and 1 part of calcia were uniformly mixed using toluene, and the uniform dispersion was developed by a casting method and dried to obtain a 150 μm-thick ceramic firing sheet. The surface roughness of this sheet after firing was 0.4 μm or more in Ra.

Example 2 25 parts of spherical alumina powder having an average particle diameter of 50 μm, and an average particle diameter of 1.
A 150-μm-thick interposed sheet for ceramic firing was obtained in the same manner as in Example 1, except that 65 parts of 5 μm active alumina powder was used. The surface roughness of this sheet after firing is 0.4μ in Ra
m or more.

Example 3 75 parts of activated alumina powder having an average particle size of 1.5 μm, styrene
7 parts of a butylene / styrene copolymer, 1 part of silica, 1 part of magnesia, and 1 part of calcia are uniformly mixed with toluene, and the uniform dispersion is developed by a casting method. Then, 15 parts of fused alumina powder having an average particle size of 50 μm were sprayed on the resultant to obtain a 150 μm-thick ceramic firing interposed sheet. The surface roughness of this sheet after firing was 0.4 μm or more in Ra.

Example 4 A 150-μm-thick interposed sheet for ceramic firing was obtained in the same manner as in Example 1 except that 7 parts of a styrene / isobutylene / styrene copolymer was used instead of the styrene / butylene / styrene copolymer. The surface roughness of this sheet after firing was 0.4 μm or more in Ra.

Example 5 According to Example 2, a 300-μm-thick ceramic firing interposed sheet was obtained. The surface roughness of this sheet after firing was 0.4 μm or more in Ra.

Comparative Example 1 An interleaved sheet was obtained in the same manner as in Example 1 except that active alumina powder having an average particle size of 1.5 μm was not used. The surface roughness of this sheet after firing was 0.4 μm or more in Ra.

Comparative Example 2 An interleaved sheet was obtained in the same manner as in Example 1 except that fused alumina powder having an average particle size of 50 μm was not used. The surface roughness of this sheet after firing was less than 0.4 μm in Ra.

Evaluation test Example, the interleaved sheet obtained in the comparative example was cut into 15 cm square,
Alumina green sheet 13 of 0.5 cm thickness and 15 cm square 13
It was baked by interposing between the layers and the lowermost part of the stacked body.

With respect to the obtained fired alumina sheet, the presence or absence of the result (individual recovery), the presence or absence of binding (transfer) of the inorganic powder, and the surface smoothness were examined.

 The results are shown in the table.

In addition, all of the interleaved sheets of the examples had good handleability, and were not damaged at the time of the interleaving work or the like.

[Brief description of the drawings]

1, 2 and 3 are sectional views of other embodiments. 1: Large inorganic powder 2: Small ceramic powder 3: Organic binder 4: Reinforcement layer

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Nakaji 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nippon Denko Corporation (72) Inventor Tatsushi Yasuda 1-1-1, Shimohozumi, Ibaraki-shi, Osaka No. 2 Nippon Denko Corporation (58) Field surveyed (Int. Cl. ⁶ , DB name) C04B 35/64-35/65

Claims (1)

(57) [Claims] 1. A sheet interposed in order to prevent binding when firing a ceramic molded body, wherein a small-sized ceramic powder fired when firing the ceramic molded body is shaped by an organic binder. An interposed sheet for ceramic firing, characterized in that a large inorganic powder that does not melt at the firing temperature of the ceramic molded body is dispersed and held in or on the sheet.