JP2788972B2 - Insert for ceramic firing - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insert sheet for ceramic firing for applying to a firing table to obtain a fired body having excellent surface smoothness with good yield.

Conventional technology and problems In the firing process of a ceramic molded body, in order to obtain a fired body having excellent surface smoothness, measures are taken so that scratches and undulations do not occur between the ceramic molded body and a firing table such as a fence plate. There is a need to.

Conventionally, as a measure, a method of spraying powder such as alumina or zirconia, a method of interposing a sheet formed by dispersing inorganic powder in a polymer-based film forming material, A discard plate method that sacrificed things was known.

However, in the above-described spraying method and sheet inserting method, the problem that the used powder binds to the fired body, the problem that the obtained fired body has poor surface smoothness, and the problem that dust is generated by removing the used powder. And so on. On the other hand, the discarded plate method has a problem in that the yield is inferior, the irregularities of the baking table are easily reflected, and scratches and undulations are generated on the second layer and the like, and the surface smoothness is poor.

Therefore, an object of the present invention is to develop an interleaved sheet that can obtain a fired body having excellent surface smoothness without causing a binding problem while utilizing a sheet interposing method with a good yield.

Means for Solving the Problems The present invention has achieved the above-mentioned objects by a method of capturing an inorganic powder by also firing an interposed sheet when firing a ceramic molded body to be processed.

That is, the present invention provides an average particle size of 5 to 300 μm that does not melt at the firing temperature in or / and on the surface of a green sheet that is itself fired when firing a ceramic molded body.
Has a non-melting, non-melting, 50 μm or more barrier layer that thermally decomposes at a higher temperature than the organic binder used to form the green sheet on one side, and the surface roughness on the other side is Another object of the present invention is to provide an interposed sheet for ceramic firing characterized in that the thickness is 10 to 200 µm.

Action The large-sized inorganic powder dispersed and held in the green sheet acts as a spacer, and at the time of firing the ceramic molded body, the green sheet is fired to capture the large-sized inorganic powder, and the ceramic molded body is formed into a fired body. Prevent binding.

Also, on one side of the interposed sheet, a non-melting, 50 μm or more-thick barrier layer that thermally splits at a higher temperature than the organic binder used to form the green sheet is provided, and the liquefied organic material in the green sheet during firing is provided. The binder is prevented from being deposited on the ceramic formed body, and the flow is prevented from causing the ceramic formed body, and furthermore, the fired body from becoming uneven and being fused to the interposed sheet.

Further, the surface roughness of the other side of the interposed sheet is 10 to 20
By controlling the thickness to 0 μm, a cushioning property is provided within a range in which the unevenness is not reflected on the fired body, and the unevenness of the firing table is absorbed to enable firing with excellent surface smoothness.

Example The ceramic firing interposed sheet of the present invention is illustrated in FIGS. 1 is a barrier layer, 2 is a green sheet, 3 is an inorganic powder, and 21 is a surface having a surface roughness of 10 to 200 μm. Reference numeral 4 denotes an organic powder for forming the surface roughness on the surface 21.

The barrier layer is thermally decomposed at a higher temperature than the organic binder used to form the green sheet, and is made non-melting so as not to flow during firing. If the ceramic molded body to be treated contains an organic binder that liquefies and flows during firing, and the organic binder is thermally decomposed at a higher temperature than that in the green sheet, the temperature may be higher than that of the organic binder if necessary. The barrier layer may be formed so as to be thermally decomposed. The thickness of the barrier layer is at least 50 μm, especially at least 80 μm. If the thickness is less than 50 μm, the effect of preventing the liquefied organic binder from flowing is poor. The upper limit of the thickness of the barrier layer is not particularly limited, but is generally 500 μm or less from the viewpoint of handleability. The formation of the barrier layer may be appropriately performed. As an example, a method in which a polymer powder that does not melt during baking such as a thermosetting resin is pyrolyzed without being melted is sprayed on one surface of a green sheet and retained, and paper containing cellulose that does not generate inorganic residues during baking is used. It can be performed by a method of laminating on one side of the green sheet.

The green sheet itself is fired when the ceramic molded body to be processed is fired. Therefore, an appropriate ceramic powder that can be fired is used for the formation. Generally, powders such as alumina, zirconia, aluminum nitride, silicon nitride, barium trioxide titanate and the like are used. The average particle size of the powder is 0.01-10 μm, especially 0.1.
1 to 5 μm is appropriate. When forming a green sheet, a firing aid such as magnesia, calcia, or silica may be blended as appropriate according to the ceramic molded body to be treated, if necessary, in order to enhance firing properties.

Average particle size 5 to 300μ dispersed and held on green sheet
As the inorganic powder of m, one that does not melt at the firing temperature of the ceramic molded body to be treated is used. Generally,
The materials exemplified in the above-described green sheet are used, and are appropriately selected and used so as not to react with the ceramic molded body to be processed at the time of firing. The preferred average particle size of the inorganic powder is from 20 to 100 μm. The appropriate amount is 2 to 200 parts by weight per 100 parts by weight of the ceramic powder for forming the green sheet. If the amount used is less than 2 parts by weight, the effect of preventing binding to the ceramic molded body is poor, and if it exceeds 200 parts by weight, the interposed sheet formed has poor sintering power and is easily broken.

Manufacture of an interposed sheet for firing ceramics is performed, for example, by casting a mixture of one or more kinds of ceramic powder for forming a green sheet 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 by an appropriate method. In this case, for example, the inorganic powder for dispersion may be dispersed and held in a sheet formed by being previously mixed with a mixture (FIG. 1), or may be dispersed on an unformed formed sheet and held on the surface. Good (Figure 2). Further, both of the above methods may be used in combination to be dispersed and held in the sheet and on the surface.

As the above-mentioned organic binder, a material such as polyvinyl butyral, an acrylic polymer, and a styrene polymer, which can keep ceramic powder in a sheet form, is used. The amount of the organic binder used is appropriately determined according to the properties of the sheet to be formed and the like, but is generally 5 to 100 parts by weight per 100 parts by weight of the ceramic powder for forming the green sheet. When preparing the mixture, if necessary, solvent, peptizer or dispersant, plasticizer, wetting agent, release agent,
An appropriate additive such as an antifoaming agent may be blended.

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 2000 μm. If the thickness is too thin, it becomes difficult to handle due to insufficient strength, and if it is too thick, the resulting fired body is liable to cause deformation problems such as unnel.

The surface roughness of the surface on which the barrier layer is not provided of the ceramic firing interposed sheet may be adjusted to 10 to 200 μm by an appropriate method. For example, a method in which a foaming agent-containing interposed sheet is formed and foamed, a method in which a sheet is formed by casting on a substrate having predetermined irregularities, and an interleaving method formed by an arbitrary method such as an extrusion method or a roll rolling method. Examples of the method include a method of imparting irregularities to the sheet via a pressing die or the like, and a method of mixing an organic powder having an average particle size of 50 to 500 μm in the interposed sheet or on the surface. As the organic powder used in this case, for example, a resin powder such as a polyethylene powder, in particular, a thermosetting resin powder which does not melt at the time of firing but thermally decomposes is preferably used.

The insert sheet for ceramic firing of the present invention is, for example, as shown in FIG.
In firing the ceramic molded body 5 formed into a sheet or the like as described above, the molded body 5 and the sintering table 7
The side 21 in which the surface roughness of the interposed sheet 6 is controlled is used as the baking table side between the baking table having a large unevenness such as a fence plate and the surface of the interposed sheet 6. The firing conditions may be appropriately determined according to the ceramic molded body to be processed. As illustrated in FIG. 4, the organic components such as the barrier layer and the organic binder disappear by the firing, and the interposed sheet is fired together with the ceramic molded body to be processed. At this time, the barrier layer 1 prevents the liquefied organic binder in the green sheet, and in some cases, the liquefied organic binder from flowing to the other side, and the inorganic powder 3 is captured by the fired body 9 of the green sheet to form the ceramic sheet. The spacer functions as a spacer while preventing transfer or binding to the body, and the uneven surface absorbs the unevenness of the firing table 7 and
Of the fired body and keep the surface of the fired body smooth.

Example 1 20 parts of spherical alumina having an average particle diameter of 50 μm (parts by weight, the same applies hereinafter), 40 parts of activated alumina having an average particle diameter of 1.5 μm, and an average particle diameter of 300
μm polyethylene 20 parts, polyvinyl butyral 16 parts,
One part of silica, one part of magnesia, one part of calcia, and one part of benzylbutyl phthalate are uniformly mixed with toluene, and the uniform dispersion is developed by a casting method to have a thickness of 320 μm and a surface roughness on one side ( Ra: same hereafter) 17
Form a sheet of 0μm, 30μm thick on the other side
Of acrylic pressure-sensitive adhesive layer, on top of which an average particle size of 200
A barrier layer was formed by spraying and holding crosslinked polystyrene of 1 μm (1 g / m ² ) to obtain an insert sheet for ceramic firing.

Example 2 10 parts of spherical alumina having an average particle diameter of 70 μm, average particle diameter of 1.5 μm
m, 40 parts of active alumina, 30 parts of crosslinked polystyrene having an average particle size of 100 μm, 16 parts of polyvinyl butyral, 1 part of silica, 1 part of magnesia, 1 part of calcia, and 1 part of benzylbutyphthalate, according to Example 1, A sheet having a thickness of 200 μm and a surface roughness of 60 μm on one side is formed, and a cross-linked polystyrene having an average particle diameter of 100 μm is scattered and held on the smooth other side of the sheet via an acrylic pressure-sensitive adhesive layer having a thickness of 30 μm (1 g /
m ² ) A barrier layer was formed to obtain an interposed sheet for firing ceramic.

Example 3 30 parts of spherical alumina having an average particle diameter of 50 μm, and an average particle diameter of 1.5 μm
m 49 parts of active alumina, 16 parts of polyvinyl butyral, 1 part of silica, 1 part of magnesia, 1 part of calcia and 1 part of benzyl butyl phthalate, and 1 part of paratoluenesulfonyl hydrazide (blowing agent) are uniformly mixed with toluene. After developing the uniform dispersion by casting method,
Foamed at 130 ° C, thickness 220μm, surface roughness on one side
Form 70μm sheet, 30μm thick on the other side
A barrier layer was formed by spraying and holding (1 g / m ² ) a crosslinked polystyrene having an average particle size of 100 μm through the acrylic pressure-sensitive adhesive layer of Example 1 to obtain an interposed sheet for ceramic firing.

Comparative Example 1 40 parts of spherical alumina having an average particle diameter of 50 μm, and an average particle diameter of 1.5 μm
m, a thickness of 200 parts according to Example 1 using 40 parts of active alumina, 16 parts of polyvinyl butyral, 1 part of silica, 1 part of magnesia, 1 part of calcia and 1 part of benzyl butyl phthalate.
A ceramic firing interposed sheet (without a barrier layer) having a thickness of 5 μm and a surface roughness of 5 μm on one side was obtained.

Comparative Example 2 0.1 part of spherical alumina having an average particle diameter of 50 μm, and an average particle diameter of 1.5 μm
In the same manner as in Example 1 except that the mixing ratio was 59.9 parts of active alumina of m and a barrier layer was not provided, an interposed sheet for firing ceramic having a thickness of 320 μm and a surface roughness of 170 μm on one side was obtained.

Comparative Example 3 An interposed sheet for ceramic firing was obtained in the same manner as in Example 1 except that a barrier layer was formed using crosslinked polystyrene having an average particle size of 30 μm.

Evaluation test Inserted sheets for ceramic firing obtained in Examples and Comparative Examples
The sheet was cut into a 16 cm square, and this was inserted between the lowermost part of the stacked body of 12 alumina green sheets having a thickness of 15 mm and a thickness of 0.8 mm and the fence plate and fired.

In the above, the presence or absence of fusion between the lowermost fired body and the fence plate, the presence or absence of binding of the inorganic powder to the target fired body, and the surface smoothness of the target fired body were examined.

 The results are shown in the table.

Effect of the Invention In the interposed sheet of the present invention, the green sheet is also fired when the ceramic molded body to be processed is fired, the inorganic powder is captured, and the binding to the target fired body is prevented. As a result, the environment is not polluted by dust or the like due to the removal of the bound inorganic powder.

In addition, the barrier layer provided on one side of the interposed sheet prevents the liquefied organic binder from flowing, preventing the fired body from becoming uneven and fusing with the interposed sheet. Are offset, and a fired body having excellent surface smoothness can be obtained with good yield.

[Brief description of the drawings]

1 and 2 are cross-sectional views of other examples, respectively, and FIG. 3 (before firing) and FIG. 4 (after firing) are explanatory cross-sectional views of an applied example. 6: Inserting sheet for ceramic firing 1: Barrier layer 2: Green sheet 3: Inorganic powder 21: Surface with a surface roughness of 10 to 200 μm 5: Ceramic molded body 7: firing table

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tatsushi Yasuda 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nippon Denko Corporation (58) Field surveyed (Int. Cl. ⁶ , DB name) C04B 35 / 64-35/65

Claims (1)

(57) [Claims] An inorganic powder having an average particle size of 5 to 300 μm that does not melt at the firing temperature is dispersed and held in a green sheet which is itself fired when firing a ceramic molded body, and / or on one surface. A non-melting barrier layer that decomposes at a higher temperature than the organic binder used to form the green sheet, has a thickness of 50 μm or more, and has a surface roughness of 10 to 20 μm on the other surface. Insertion sheet for ceramic firing.