JPH0470264B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a silver glaze for ceramic tiles. In particular, the present invention relates to improvements in silver glazes for pottery tiles that contain MnO expressed in Segel representation.

[Prior Art] Oxides of metals such as iron, manganese, copper, chromium, cobalt, and nickel are often used as colorants in glazes for ceramic tiles. In particular, recently there have been many requests for silver-glazed tiles, and this type of glazed tiles have been produced in large quantities. As illustrated in JP-A No. 58-79838, this silver glaze contains
May contain a large amount of MnO. This MnO component generally uses tetravalent manganese oxide (manganese dioxide) as a raw material, and carbonate is also sometimes used. That is, conventionally, manganese dioxide, such as crushed natural manganese ore, has been customarily used.

The glaze composition of the silver glaze, which is disclosed in the above -mentioned special opening of 58-79838, is displayed in the Zegel display, 0-0.025 LI ₂ O + NA ₂ O + ₂ O 0.03-0.11 CAO + MGO + BAO + ZNO + SRO 0.21-0.22 PBO 0.60 ~ 0.76 MNO 0.1 ~0.31 _Al2O3 and/or _Fe2O3 1.2-1.6 _{SiO2 0.11-0.15} ZrO2 _{0.25-0.30 TiO2 0.03-0.16 B2O3} , characterized by 0.60-0.76 _mol MnO,
If MnO is supplied from manganese dioxide in the glaze formulation, the manganese dioxide in the glaze formulation will account for approximately 20% or more.

[Problems to be Solved by the Invention] However, this glaze containing a large amount of MnO has the following drawbacks when firing tiles.

(1) It is known that when this glaze is fired, heat absorption occurs as the glaze reaction progresses, and the temperature of the furnace must be further raised to compensate for this.

(2) Therefore, if tiles are fired in the same furnace as tiles with other glazes that do not contain much MnO, such as high silver, orange, black, blue-green, maroon glazes, etc. (such different types of products cannot be fired in the same furnace). (This is common in the industry when firing at the same time as other glazes), but if the temperature is controlled according to the temperature of the other glazes, the glaze containing a lot of MnO will not be melted sufficiently.

(3) In such cases, if you try to melt the glaze sufficiently, the quality of the other glazes mentioned above will change significantly.
This tends to interfere with on-site production planning.

As mentioned above, unlike tiles, in the production of ceramic tiles, different types of products are generally fired at the same time. For example, the products are placed on a trolley, naked, side by side, and fired through a tunnel kiln. When firing in this manner, it is difficult to control the firing temperature to achieve a good yield.

When it comes to insufficient melting of the glaze, it is common practice to lower the softening temperature of the glaze, but with glazes that contain a large amount of MnO, point (1) above cannot be solved by simply lowering the softening temperature. When firing the glaze, the temperature of the furnace should be increased to 10 to 15℃ when the temperature decreases due to heat absorption.
As a result, the burden of fuel costs is high.

[Means for Solving the Problems] An object of the present invention is to provide a silver glaze for ceramic tiles that does not have the above-mentioned drawbacks. That is, according to the present invention, there is provided a silver glaze for a ceramic tile which contains MnO expressed in Segel representation, characterized in that the Mn-containing raw material is Mn ₂ O ₃ and/or Mn ₃ O ₄ . A silver glaze is provided.

As a result of intensive research, the present inventors found that when manganese dioxide was conventionally used as a manganese-containing raw material, it was replaced with Mn ₂ O ₃ and/or Mn ₃ O ₄ .
It was discovered that no endothermic reaction occurred.

In the glaze of the present invention, components other than manganese are conventional, including those disclosed in the above-mentioned publication.
Same as MnO-containing silver glaze. For example, typical examples of conventional silver glaze compositions are shown in Segel representation: 0-0.1 K ₂ O, Na ₂ O and/or Li ₂ O 0-0.2 CaO, BaO, MgO, SrO and/or
ZnO 0 - 0.3 PbO 0.6 - 1.0 MnO 0.02 - 0.8 Al ₂ O ₃ 0.5 - 1.5 SiO ₂ 0 - 0.3 B ₂ O ₃ 0.2 - 1.5 TiO ₂ , ZrO ₂ and/or V ₂ O ₅ . To obtain such compositions, the starting materials are generally leaded frits, unleaded frits,
Silica powder, kaolin, frog's eye clay, zirconium silicate, rutile, lime, barium carbonate, magnesium carbonate, strontium carbonate, zinc white, vanadium pentoxide, manganese dioxide, iron oxide, etc. are used.

The present invention is characterized in that manganese sesquioxide (Mn ₂ O ₃ ) and/or trimanganese tetroxide ₍ Mn ₃ O ₄ ) is used as the starting material for the manganese component in place of conventional manganese dioxide (MnO 2 ). shall be. Except for the manganese component, other starting materials are the same as conventional ones. Although it is preferable to use industrial products for manganese sesquioxide and trimanganese tetraoxide, this does not preclude the use of natural raw materials.

Furthermore, the firing temperature is also a conventional glaze firing temperature, preferably 1060°C to 1140°C.

Since the method for manufacturing the glaze of the present invention is no different from the conventional method, a detailed explanation is not required here.

The silver coloring effect of the obtained glaze is the same as that of conventional glazes.

[Effect] Conventional glazes using manganese dioxide show a significant endothermic peak near the furnace temperature of 1060 to 1100℃, and this temperature range is the highest firing temperature for glazes. It is thought that due to the endothermic action of MnO, the temperature of the furnace falls and the amount of heat received by the glaze is insufficient, making it difficult for the glaze to melt. The glaze of the present invention has almost no such endothermic peaks and is thermally stable. Therefore, even if a glaze containing a large amount of manganese oxide is fired, it is not necessary to specially change the firing temperature or apply a different type of glaze. Even if the tiles are fired at the same time, they will not change in quality.

Next, examples will be shown.

[Example] Example 1 A silver glaze was prepared using the following formulation.

Leaded frit 30% by weight Silica powder 8.2 Kaolin 11.8 Frog's eye clay 3.6 Mn ₃ O ₄ powder 22.5 Silver pigment 23.0 CMC 0.4% by weight Bentonite 0.5 Water was added to this mixture and ground in a ball mill to reduce the particle size to 74 μm or less. Aimed to be over 95%. In this way, a silver glaze was obtained. This glaze was applied to the dry base of the tile in an amount of 70 to 80 g per tile and fired in a tunnel kiln. This tunnel kiln also contained roof tiles with various glazes (high silver, orange, black, blue-green, and marron glazes). The firing temperature, i.e. the maximum temperature inside the furnace, is
It was 1100℃.

The firing temperature was constant, and no operation was performed to raise the temperature inside the kiln. That is, the firing operating conditions were not changed during firing.

In this way, the glaze was sufficiently melted, and a roof tile with a good silver color was obtained. No deterioration occurred in any of the other types of glazed tiles that were fired at the same time.

Example 2 A silver glaze was prepared using the following formulation.

Leaded frit 24.7% by weight Silica powder 12.2% by weight Kaolin 22.9 Frog's eye clay 1.8 Mn ₂ O ₃ powder 24.0 Silver pigment 13.2 CMC 0.5 Bentonite 0.7 Water was added to this mixture and ground in a ball mill to reduce the particle size to 74 μm or less. Aimed to be over 95%. In this way, a silver glaze was obtained. This glaze was applied to the dry base of the tile in an amount of 80 to 90 g per tile and fired in a tunnel kiln. Tiles glazed with other types of glazes (high silver, orange, black, blue-green, and marron glazes) were also placed in this tunnel kiln at the same time. The firing temperature, i.e. the maximum temperature inside the furnace, is
It was 1090℃.

The firing temperature was constant, and no operation was performed to raise the temperature inside the kiln. That is, the firing operating conditions were not changed during firing.

In this way, the glaze was sufficiently melted, and a roof tile with a good silver color was obtained. No deterioration occurred in any of the various types of glazed tiles that were fired at the same time.

Comparative Example A glaze was prepared under the same conditions as in Example 1 except that Mn ₃ O ₄ was replaced with MnO ₂ . 75-85g of this glaze is applied to each tile, and 1100g is applied in a tunnel kiln.
Calcined at ℃. When tiles glazed with the other types of glazes mentioned above were replaced with tiles glazed with the glaze of this example in a kiln operated under certain conditions, the glaze of this example showed that it was not sufficiently melted. . On the other hand, when the maximum temperature inside the kiln was raised by 15 degrees Celsius, a good silver tile was obtained, but the tile glazed with other glazes fired at the same time was significantly altered in quality.

[Effects of the Invention] According to the present invention, manganese sesquioxide and/or manganese are used as the starting materials for the manganese component among the starting materials for the glaze for silver roof tiles containing a relatively large amount of manganese components.
Alternatively, by using trimanganese tetroxide, production can be carried out under stable firing conditions, and even when fired at the same time as roof tiles with different types of glazes, there are no negative effects and the energy required for firing is low. It also has the advantage of being economical.

Claims (1)

[Claims] 1. A silver glaze for ceramic tiles containing 20% by weight or more of manganese oxide as a manganese-containing raw material, characterized in that the manganese oxide is Mn ₂ O ₃ and/or Mn ₃ O ₄ .