JPH07242477A - Glaze for somber silver earthenware roof tile - Google Patents

Abstract

PURPOSE:To obtain glaze which is less fluctuated in color development, is mass producible and overcomes defects associated with green body by compounding MnO, PbO, SiO2, ZrO2, TiO2, and V2O5 in limited compsn. ranges and specifying the existence amts. of the ZrO2, TiO2, V2O5 and SnO2. CONSTITUTION:This glaze has the compsn. consisting, in Seger designation, 0.3 to 0.7mol MnO, 0.3 to 0.7mol PbO, 0.9 to 5.0mol SiO2, 1.1 to 16.5 Al2O3, 0.5 to 3.5mol total of ZrO2+TiO2+V2O5 and <=0.5mol SnO2. The glazed roof tile is obtd. by subjecting glazed roof tiles which are formed by reduction burning and fumigation stages and are approximate to somber silver roof tiles to oxidation burning with this glaze. The glaze has effects of (2) lessening the fluctuation in the color development of the silver color, (3) improving the yield of product roof tiles and permitting mass production, (4) improving fusibility of the glaze, making it possible to increase adhesion and overcoming the defects associated with the green body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glaze for smoldering silver-colored ceramic tiles.

[0002]

2. Description of the Related Art Conventionally, a method of forming a thin smoldering silver-colored carbon film on the surface of a clay roof requires reduction baking and a smoke-imparting step. Especially, the smoke-imparting condition at a high temperature and the reducing atmosphere in the cooling process are required. However, there is a drawback in that the product yield is poor and it is not suitable for mass production. In addition, discoloration called rust and shoyu and peeling of the carbon film may occur depending on the smoked conditions and the composition of the base soil, which is also a major quality defect. On the other hand, the present inventors
JP-A-58-79838, JP-B-63-3141
No. 8, JP-A-2-243537, there has been provided a method for obtaining a smoldering silver-colored glaze roof tile by oxidative firing without requiring a smoking step, but these methods have the following drawbacks. It was

The method exemplified in Japanese Patent Laid-Open No. 58-79838 contains PbO in an amount of 0.22 mol at most and Mn
O, TiO ₂ , ZrO ₂ , Fe ₂ O ₃ , NiO, Co
Although squid silver color is obtained with the components of O, MoO, and WO ₄ , it is insufficient in terms of smolder silver color as compared with the smoky silver roof tile produced by the reduction firing and smoke process.

The method exemplified in Japanese Examined Patent Publication No. 63-31418 includes MnO containing 0.3 mol or less of PbO.
Of 0.9 to 1.0 mol, and the total amount of oxides of Zr, Ti, V, and Sn, and optionally Sb, is 0.
Using a glaze characterized by containing 2 to 1.5 moles, a dull silver color is obtained. The Ibushi silver-colored glaze tile in this method was very similar in terms of color development to the Ibushi silver-colored tile produced by the reduction firing and smoldering process, but (a) the fired product tile was mechanical. The glaze surface is easily damaged by impact, (b) the original aesthetics of the glaze are impaired under the influence of surface defects on the tile base such as uneven cracks, (c)
In the roof tile production process, it is easily affected by the atmosphere (temperature conditions, gas composition, kiln-packing type, etc.) in the firing furnace, and there are major drawbacks such as a large variation in color development between furnaces and a poor yield of product roof tiles.

The glaze and method disclosed in JP-A-2-243537 is an improved version of the glaze and method disclosed in JP-B-63-31418, and the number of moles of SiO _{2 in} the glaze component is And Zr, Ti, V and Sn
The present invention is characterized by simultaneously increasing the total number of moles of the oxide of No. 1 and the oxide of Sb at the same time, but there were the following drawbacks in mass-producing the smoky silver glaze roof tile by this method. (B) In the production process of the glaze roof tile, it is common to fire different colors of glaze roof tile at the same time. The melting state and color development of the roof tile are affected. (B) The roof tiles are not only a fine appearance after they have been roofed, but also the appearance when they are wet with water when it rains, but the Ibushi silver glaze tile is When it got wet with water, it looked dark brown, and the smoldering silver color after the thatching was insufficient.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks and is similar to the smoldering silver roof tiles produced by a reduction firing and a smoke-making process, and can be mass-produced with little color variation and has the disadvantages of the base soil. It is intended to provide a method for obtaining a coverable smoked silver glaze roof by oxidation firing.

[0007]

Means for Solving the Problems As a result of intensive research to solve the above-mentioned drawbacks, the present inventor has shown that the glaze is represented by Zegel,
MnO 0.3-0.7 mol, PbO 0.3 mol
0.7 moles, SiO ₂ 0.9 to 5.0 mol, Al ₂ O ₃
0.08 to 1.0 _{moles, SiO 2 / Al 2 O 3} 1.1~
16.5, ZrO ₂ + TiO ₂ + V ₂ O ₅ total 0.5
A glaze having a composition of up to 3.5 mol and SnO ₂ 0.5 mol or less is suitable for mass production because it has good meltability and smoldering silver coloration and shows little color variation due to simultaneous firing with different color glazes. I found it.

Solves the meltability of glaze and the fluctuation of smoldering silver color
In the present invention to be determined, the number of moles of MnO and PbO and
SiO₂/ Al₂O₃The value of is especially important. MnO
It is an essential component for smoldering silver coloring, and its amount is 0.3-
It is 0.7 mol. If it is less than 0.3 mol, it is difficult to develop color. P
mol of bO and SiO₂/ Al₂O₃The ratio value is for glaze
It is a condition that determines the meltability, and its range is 1.1 to 1.
It is 6.5, preferably 2.5 to 8.5. Si
O₂/ Al₂O₃Ratio value is less than 1.1 or more than 16.5
In the case of, even if PbO is 0.7 mol, it does not melt sufficiently.
Yes. The amount of PbO is greater than 0.3 mol to 0.7 mol.
It ZrO₂, TiO₂, V₂O_FiveGoes with MnO
It is an essential ingredient for silver color development, and the total number of moles is
If it is less than 0.5 mol, it does not become a silvery smolder, and if it is 3.5 mol.
Above this level, the glaze does not melt sufficiently. SnO ₂Silver smoke
Although it is an effective ingredient for color development, it is the same as a different color glaze.
To reduce color variation due to occasional firing, 0.5 mol or more
It is necessary to be below.

SiO ₂ and Al ₂ O ₃ are used for adjusting the fire resistance of glaze,
That is, it can be appropriately selected by setting the firing temperature of 980 ° C. to 1200 ° C., but SiO ₂ is 0.9
0-5.0 mol, preferably 2.0-4.5 mol, Al
₂ O ₃ is 0.08 to 1.0 mol, preferably 0.3 to
A range of 0.8 mol is suitable.

Further, in the present invention, B ₂ O ₃ , R
₂ O and RO ₂ can be added as long as they do not affect the properties of the glaze. B ₂ O ₃ 0.0-0.3 mol, R ₂ O 0.0-0.1 mol, RO ₂ 0.0-0.2
Molar is preferred.

Further, metal oxides such as Sb, Co, Ni, Mo and W can be appropriately selected as long as they do not interfere with the color development of smoky silver. Next, the present invention will be specifically described with reference to examples.

Compositions of Examples 1 to 22 shown in Table 1 (Zegel indication) using leaded frit, silica stone powder, kaolin, alumina powder, titanium oxide, zirconium silicate, vanadium oxide, manganese dioxide, iron oxide and the like as raw materials. ) Of the glaze was wet-milled with a pot mill, and the obtained slip was applied to a dry tile base,
Japanese-style sash tile JIS53A plate is glazed to have an adhesion amount of 60 to 90 g per sheet, and oxidized and baked at the temperature shown in Table 1,
A good neat silvery glaze roof tile was obtained. These squid silver-colored glaze roof tiles did not show color variation due to the type of other glaze-tile roof tiles co-fired in the furnace, and the silver color development in a wet state was also good. Further, since the adhesion amount is as large as 60 to 90 g, the defects of the base soil are covered and the appearance can be maintained. The yield as product roof tile was 97% or more.

For comparison, the glazes having the compositions of Comparative Examples 1 to 7 (indicated by Zegel) were used and subjected to oxidation firing in the same manner as in the examples. The composition of each comparative example is also summarized in Table 1. In Comparative Examples 1 to 3, the glaze did not melt sufficiently and peeling and the like occurred. Comparative Examples 4 and 7
As for No. 1, the smoldering silver color after firing was insufficient, and exhibited a blackish coloration. In Comparative Examples 5 and 6, the smoldering silver color after firing was good, but when fired simultaneously with another glaze roof tile (for example, high silver), the color changed to reddish purple, and when wet with water, it turned brown and became a silver color. Was not shown. The yield of product roof tiles was about 85%. In addition, in Table 1,
The results of observation of three items, (1) color development and melting state, (2) color change due to mixed firing, and (3) color change due to temperature change, are shown. In the table, the ∘ mark indicates “good”, “no change” and “no change” for the items (1), (2) and (3) respectively, and the X mark similarly indicates “poor” and “change” respectively. "Yes" and "variable".

[0014]

[Table 1]

[Table 2]

[Table 3]

[0015]

Effect of the Invention It is possible to obtain a glaze roof tile that is similar to the smoky silver roof tile that is produced through the reduction firing process and the smoking process by oxidation firing process. 2. Little variation in silver color. 3. The yield of product tiles is improved and mass production is possible. 4. The glaze has good meltability, and the amount of adhesion can be increased, which can cover the defects of the base soil.

Claims (5)

[Claims] 1. MnO 0.3-0.7 in Zegel display
Mol, PbO greater than 0.3 mol to 0.7 mol, SiO₂
0.9-5.0 mol, Al₂O₃0.08 to 1.0
Le, SiO₂/ Al₂O₃1.1 to 16.5, ZrO₂
+ TiO₂+ V ₂O_Five0.5 to 3.5 mol, Sn
O₂Characterized by having a composition of 0.5 mol or less,
A glaze for smoldering silver-colored ceramic tiles. 2. SiO ₂ is 0.90 to 5.0 mol, Al
_The glaze for smoked silver porcelain tile according to claim 1, wherein ₂ O ₃ is 0.08 to 1.0 mol. 3. SiO ₂ of 2.0 to 4.5 mol, Al ₂
The glaze for smoked silver-colored ceramic tile according to claim 1, wherein O ₃ is 0.3 to 0.8 mol. 4. Further, B ₂ O ₃ is 0.3 mol or less, R ₂ O
Is 0.1 mol or less and RO ₂ is 0.2 mol or less (where,
R is an alkali metal or an alkaline earth metal),
The glaze for smoked silver-colored ceramic tile according to claim 1. 5. The glaze for smoky silver-colored ceramic tile according to claim 1, which contains a metal oxide of Sb, Co, Ni, Mo and / or W.