JPH0729862B2 - Manufacturing method of porous ceramic plate - Google Patents

Description

The present invention relates to a method for producing a porous ceramic plate. More specifically, the present invention relates to a method for producing a porous ceramic plate capable of obtaining a porous ceramic plate having a smooth and beautiful surface.

[Prior Art and Problems to be Solved by the Invention] A porous ceramic plate is lightweight, has heat insulating properties, fire resistance,
Since it is excellent in workability and so on, it is being widely used for building materials and the like, but on the other hand, there are problems in surface smoothness, decorativeness, surface strength and the like.

So, while taking advantage of the advantages of porous ceramic plates,
In order to improve the drawbacks, there has been proposed a method for producing a porous ceramic plate in which a foam layer and a dense ceramic layer are integrated by using porcelain paper (for example, JP-A-62-252385).

However, in the conventional manufacturing method, porcelain paper is arranged on the upper surface or the upper and lower surfaces of the inorganic raw material layer that is foamed by heating, and these are co-fired to be solution-integrated. For this reason, the gas generated from the inorganic raw material layer during firing was not completely exhausted (gas is difficult to escape when there is a dense layer in the upper layer), and bumps were formed on the surface of the porous ceramic plate. Also, since it is necessary to raise the surface temperature to be about 50 to 80 ° C lower than the backside temperature to keep the surface in a porous state without fusing and to emit gas, it is necessary to keep the temperature above 8 ° C per minute. Since the heating rate could cause the generation of humps, the firing speed could not be increased and it took a long time to manufacture.

In view of the above circumstances, the present invention provides a method for producing a porous ceramic plate that can obtain a smooth and beautiful finished surface without bumps and the like, and can increase the firing speed to enhance the production efficiency. The purpose is to

[Means for Solving the Problem] The method for producing a porous ceramic plate of the present invention is characterized in that an inorganic raw material layer that foams by heating is provided on porcelain paper, and these are heated and fired at the same time for solution integration. There is.

[Operation] Most of the gas generated when firing the inorganic raw material that is foamed by heating escapes from the upper side, but unless the airtight layer is provided in the upper layer as in the present invention, the gas easily escapes and escapes to the surface. The formation of bumps due to accumulated gas without cutting is prevented. In addition, since the gas is smoothly released, the firing speed can be increased.

[Example] The present invention relates to an alumina fiber and a mullite fiber (3Al ₂ O ₃ .2SiO).
Fiber having ₂ as the main crystal, and having excellent mechanical strength, heat resistance and corrosion resistance) and a mixed slurry made of inorganic powder, etc. It is characterized in that these are heated and solution-foamed to integrally form a foamed layer made of a foamable inorganic material and a dense surface layer made of porcelain paper.

As the foamable inorganic raw material, natural glass, artificial glass or the like powder, dolomite, may be used those added with a foaming agent such as silicon carbide, acid clay is a volcanic natural raw material instead of glass powder, Flux component and foaming agent are added to anti-fire stones, shirasu, etc. and finely pulverized (44μ-90%), and this powder is granulated to 0.2 to 1 m / m. It is preferable because it is excellent in gas divergence.

Flux components are substances that lower the melting point of other substances when mixed with other substances, such as Na ₂ CO ₃ and Na ₂ SiO _2.
3 , NaNO ₃ , Na ₂ HPO ₄ , Pb ₃ O ₄ , 2PbCO ₃ · Pb (OH) ₂ , BaCO
₃ , NaB ₄ O ₇ · 10H ₂ O, H ₃ BO ₃ , ZnO, glass powder, frit, etc.

Porcelain paper is a sheet-like substance obtained by making a slurry by mixing inorganic powder raw materials such as feldspar, glass powder, and frit with inorganic fibers, an organic binder, an inorganic binder, and an aggregating agent. Examples of the compounding include, for example, inorganic powder raw material mixed with alumina fiber and / or mullite fiber, inorganic powder raw material mixed with inorganic fiber and pulp fiber, inorganic raw material mixed with pulp fiber, and the like. There is. As described above, porcelain paper contains an inorganic powder raw material and a fibrous raw material as essential components, but when alumina fiber and / or mullite fiber is used as the fibrous raw material, shrinkage of the porcelain paper during firing can be reduced. It is preferable because it is possible. Further, the shrinkage is further reduced by using the calcination raw material. Although it is possible to use glass fiber, pulp fiber or the like as the fibrous raw material, these do not cause a problem in sheet formation, but they shrink by heating (in this case,
The base material layer is foamed and expanded, and there are disadvantages that there are many porcelain-free portions (and thus portions without a dense surface layer) in the peripheral portion of the resulting porous ceramic plate. Therefore, it is preferable that the raw material of porcelain paper contains 4 to 8% by weight of inorganic fibers such as alumina fibers and mullite fibers.

The porcelain paper is obtained by making a slurry having the above-mentioned composition into a sheet and making it into a sheet, and a continuous paper machine can be used for making the sheet. It is possible to give a desired pattern such as a multicolored pattern to the porcelain paper by printing the dried sheet with a printing machine or the like by pressing the porcelain paper into a sheet formed by a paper machine. Further, in the case of printing, a desired color can be added in addition to a clear pattern which cannot be realized by the conventional method.

Further, a colored sheet can be obtained by blending a metal oxide such as Cr, Mn, Co, Ni, or Cu with a colorant such as a pigment in the slurry. The metal oxide dissolves in the glass phase during firing to develop a color (the colored element dissolves as an ion). A pigment is one that is suspended in glass without dissolving in the glass phase like a metal oxide,
The metal oxide as described above is mixed with kaolin, feldspar, etc., calcined, washed with water and crushed. The pigment must be flux stable.

The porous ceramic plate is manufactured by firing a stack of the above-mentioned pelletized expandable inorganic raw material on porcelain paper to integrate them. As the firing furnace, it is preferable to adopt a transfer tunnel furnace equipped with a heat resistant mesh belt. When the mesh belt is used, the volatile components can be uniformly diffused from the upper and lower surfaces during foaming, and the heat can be uniformly transferred to the upper and lower surfaces.

The firing temperature is determined by the ratio of the compounded raw materials SiO ₂ , Al ₂ O ₃ , and flux components.When using metal parts for mesh belts, rolls, etc., fire them at the lowest possible temperature for the sake of maintenance. Is preferred, specifically 750 ° C
It is preferable to carry out the firing in the range of to 850 ° C.

The solubilization temperature of porcelain paper can be changed appropriately depending on the raw material formulation, but the firing temperature of the base material is more important for the performance of the product and it is necessary to select it with priority, so it is slightly lower than the base material. It is preferable to adjust so that the solution dissolves.

When the temperature of the base material layer and the porcelain paper is increased in the firing furnace, the base material layer and the porcelain paper begin to soften, and at the same time, the base material layer expands while generating gas to increase its volume and foam. move on. In this case,
The porcelain paper layered on the lower surface also softens and melts to become one with the foam layer.

After foaming, the porous ceramic plate in which the base material layer and the porcelain paper are integrated is cooled. In this case, the surface is rapidly cooled by the cooled roll, and then reheated so that the surface is resoftened ( For example, it is preferable to perform reheating depending on the ambient temperature in the firing furnace. Preferred types of rolls differ depending on the thickness of the porous ceramic plate and the type of raw material, and are not particularly limited in the present invention. After quenching
Re-softening can increase the brightness or gloss of the porous ceramic plate (measured according to JIS Z 8722). The reason for reheating after pressing and quenching with a roll is that even a glass surface having a luster by heating and heating becomes a matte surface (matte surface) that does not lose gloss when pressed by a roll while hot. Therefore, the surface is heated again to be melted to give a luster, and then transferred to the cooling zone and sequentially cooled so as to remove the "strain" stress, so that the dense layer and the foamed substrate are integrated. In this way, a smooth and glossy porous ceramic plate can be manufactured.

The temperature of the quenching pressure roll can be prevented from fusion of the roll by pressing with a roll having a temperature 60 to 70 ° C. lower than the product surface temperature, but it is preferable to lower the temperature to the solidification temperature in order to improve the productivity. For example, the surface of a porous ceramic plate fired at a surface temperature of 880 ℃ is rapidly cooled to 600 ℃,
After that, it is a general method to reheat at about 850 ° C.

Next, the method for producing the porous ceramic plate of the present invention will be described based on examples, but the present invention is not limited to such examples as a matter of course.

Example Feldspar 69% (wt%, same below), soda ash 17%, ZrSiO ₄
A blended raw material consisting of 10% and sodium nitrate 4% was wet pulverized using a pot mill so that the particle size was 250 mesh. Alumina fiber 5% (outer split.
Based on the blended raw materials), starch 5%, acrylic emulsion 2%, and anions or cations as coagulants are added so that the papermaking concentration (the concentration of raw materials made by a paper machine) is adjusted to 1% or less. did. The obtained liquid material was applied to a papermaking machine to make a sheet having a papermaking dimension of 50 cm × 50 cm × 0.1 cm.

A surface pressure of 20 kg / cm ² was applied to the paper making roll to finish it, and far infrared rays were radiated for 2 hours for drying. After drying, the six color pigments adjusted to the melting temperature of 850 ° C were kneaded with 201 Cerazole (Mitamura Shoten Co., Ltd. pigment kneading oil), and the patterns were decomposed into six colors, and each was put on porcelain paper. It was directly printed with a squeegee (elastic rubber or resin) and dried to obtain patterned porcelain paper. It should be noted that the porcelain paper was adjusted so that the firing solution temperature was 850 ° C.

Next, acid clay 71%, soda ash 10%, sodium nitrate 4
%, Zircon flower (crushed zircon sand, particle size 74μ or less), dolomite 5%, dry-milled with a pot mill to a particle size of 44μ / 90%, and then into a bread-type granulator. Granulate with a particle size of 1-2 m / m
I got a pellet. The pellets are used as a foaming base material and are compounded so that the foaming temperature is 870 ° C.

On the continuous mesh belt, put a release paper with a thickness of 1.5 mm,
The obtained porcelain paper was placed thereon, and the pelletized expandable inorganic raw material was further laminated thereon so as to form a layer of 50 cm × 50 cm × 1 cm. A lath net was embedded in the middle of the foamable inorganic material layer. The obtained laminate was conveyed into the furnace at a speed of 28 cm / min. 12.5 up to 500-800 ℃
Despite the high temperature rising rate of ℃ / min, the fired plate does not show any defects such as buku (meaning bubbles in the glaze layer), and it is a decorative plate consisting of a smooth and dense glass layer and foam layer. I was able to get

Comparative Example Apply mold release powder on a mesh belt, stack pelletized expandable inorganic raw material so as to form a layer of 50 cm × 50 cm × 1 cm, and further screen print a pattern on the surface. The above-mentioned ceramic paper (thickness 0.1 cm) was placed. The obtained laminate is conveyed into the furnace at a speed of 28 cm / min, 500-800 ℃
Was heated at a rate of 12.5 ° C / min.

The fired plate obtained was smooth, but semicircular wrinkles of about 15 cm remained on the surface. This wrinkle is clearly a mark of the gas-induced hump being pressed by the roll, and in order to prevent this, it is necessary to reduce the firing speed or lengthen the furnace. Therefore, in the same furnace, the maximum temperature rise is 6.0 ℃ / min, and the production is down by about 40-50%. In addition, when porcelain paper was placed on the foamable inorganic raw material layer, the porcelain paper contracted more greatly than when laid below. If you lay it down
It was 494 mm against 500 mm, but when laid on top it was 48
It was 8 mm. This is considered to be because the contraction of the porcelain paper is suppressed by the contact with the net when it is laid below.

[Effects of the Invention] As described above, in the method for producing a porous ceramic plate of the present invention, since the expandable inorganic raw material is laminated on the porcelain paper and heated and fired, the gas generated during firing is It becomes easy to pull out, and it is possible to prevent humps from being formed on the surface of the obtained product. In addition, since a decorative layer of porcelain paper is formed on the lower dense layer, the finish becomes very beautiful. Further, the melting point of the porcelain paper is adjusted to be low because the porcelain paper is smoother than the substrate layer, and the foamed pellets are not fused even when the porcelain paper is melted. Therefore, the gas is free to scatter upward, and there is no need to make a temperature difference between the upper surface and the back surface when raising the temperature.
Even when the temperature is raised to ~ 800 ° C, there is no restriction due to the generation of bumps, so the firing speed can be increased and the production efficiency can be improved.

Front page continued (72) Inventor Shigeo Yoshida 1-1-12 Shinsenri Nishimachi, Toyonaka City, Osaka National Housing Industry Co., Ltd. (72) Inventor Takatoshi Miyazawa 1-1-12 Shinsenri Nishimachi, Toyonaka City, Osaka Prefecture National Housing Industry Co., Ltd. (56) Reference JP-A 64-108176 (JP, A) JP-A 62-252385 (JP, A)

Claims (1)

[Claims] 1. A method for producing a porous ceramic plate, characterized in that an inorganic raw material layer which is foamed by heating is provided on porcelain paper, and these are simultaneously heated and fired to be melted and integrated.