JPH07300380A - Method for producing glazing agent for pottery roof tile - Google Patents

Abstract

PURPOSE:To provide a glazing agent for pottery roof tiles, minimized in the amount of lead contents eluted into the slurry in comparison with conventional glazing agents, also when lead-containing glass frit is used. CONSTITUTION:In a method for producing a glazing agent for pottery roof tiles by adding a proper amount of a metal oxide or pigment as a coloring agent to glass frit, silica, feldspar, clay, etc., and subsequently wet-grinding the mixture with a ball mill, there is used powdery glass frit preliminarily dry-ground into a particle size of <=100 mesh in an amount of >=99vol.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a glaze for earthenware tile used as a roofing material.

[0002]

2. Description of the Related Art In general, glazes for earthenware tiles are obtained by adding an appropriate amount of a metal oxide or pigment as a colorant to glass frit, silica stone, feldspar, clay, etc. and wet pulverizing with a ball mill. Glass frit is a melting agent for glaze, and the addition amount varies depending on the temperature at which the ceramic tile is fired. Generally, at a firing temperature of 950 ° C to 1150 ° C, basic glaze 1
It is used in an amount of 60% to 10% in 00%. At that time, the shape of the glass frit is granular from rice grain size to adzuki bean size or flake shape similar to fish phosphorus (depending on the frit production method), and the basic glaze raw material other than glass frit is used in powder form, and the whole is prescribed. It is generally manufactured by wet pulverizing for a long time (8 hours to 24 hours) using a ball mill so that the particle size becomes. However, depending on the purpose, 24 hours or more or 8 hours or less may be sufficient.

At this time, when a glass frit containing lead is used, there is a problem that a large amount of lead is eluted into the glaze slurry during wet grinding for a long time. The Water Pollution Control Law was revised (February 1, 1994), and the standard for drainage of lead content has been reduced from 1 PPm or less to 0.1 PPm or less, and glaze with a low lead content in the formulation, or lead content in the slurry. There is a need for a glaze with a low elution amount.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a glaze for pottery tiles in which, even when a leaded glass frit is used, the elution amount of lead in the slurry is extremely small compared to conventional glazes. Is.

[0005]

Means for Solving the Problems The gist of the present invention is, when a slurry of a glaze for pottery tiles is prepared by using a ball mill, a powder which is previously dry-milled as a glass frit to have a particle size of 100 mesh or less and 99% or more. It is a method for producing a glaze for a ceramic tile, which is characterized by using a glass frit.

The present invention is characterized in that the glass frit in the raw material of the glaze for earthenware roof tile is used in the form of powder in advance. The finer the particle size of the powder is, the more advantageous it is. However, as a glaze for roof tile, it is practically 100 mesh or less and 99% in amount.
Usually, 8 to 15 kinds of raw materials including glass frit are put into a ball mill, a predetermined amount of water is added, and the mixture is milled to a predetermined particle size to prepare a glaze slurry. The particle size of commonly used powdery raw materials such as silica stone and feldspar is 100 mesh or less and 99% or more, and glass frit may have the same particle size. If it is coarser than that, the milling time after the glaze preparation becomes long, and the lead elution increases. Finer than that is convenient, but the cost of grinding the glass frit increases. The particle size of a practical glaze slurry for roof tile is about 0.1 to 6 g of 200 mesh residue in 100 cc of glaze slurry. Therefore, if the particle size of all raw materials is set to 0.1 to 6 g of 200 mesh residue in advance, a glaze for practical use can be obtained by merely mixing. However, it is not always the case that all commercially available raw materials are within this range, and it is better for the glaze properties to take some milling time from the viewpoint of uniform mixing of the raw materials. Even in that case, the milling time can be significantly shortened as compared with the case where the glass frit is granular or flake.

[0007]

In the present invention, since the glass frit is powdered in advance, the milling time is much shorter than that of the conventional method, and depending on the purpose, the raw material containing the glass frit is simply mixed by milling. In some cases, it can be put to practical use without the need for pulling. Therefore, when using leaded glass frit,
Very little lead elution into the glaze slurry. When the wastewater treatment is performed as a post-process of these glazes, the lead concentration in the raw water is lower than that of the glaze obtained by the usual milling method, so that the management of the wastewater treatment is extremely easy. Moreover, since the milling time is short, the manufacturing cost of the glaze slurry can be reduced.

Next, the present invention will be described with reference to Examples and Comparative Examples.

Comparative Example 1 Leaded borosilicate glass frit (flakes with a thickness of 0.6 to 1.6 mm) 30% Zircon 20% Manganese oxide ore 25% Kaolin 10% Silica 5% Rutile 8% Lime 2% Basic glaze above Bentonite (1 part), CMC (0.5 part) and water (50 parts) were added to 100 parts as a mill additive, and the mixture was pulverized with a ball mill for 16 hours. The properties of the obtained slurry were as follows. Viscosity 3.3 Poise (normal temperature) Particle size 0.8 g / 200 mesh / 100 g Slurry Lead concentration in slurry 180 ppm

[0009]

Example 1 The borosilicate leaded glass frit of Comparative Example 1 was
A slurry was obtained by milling for 5 hours with the same composition as in Comparative Example 1 except that a powdery glass frit that had been dry-pulverized in advance so as to have 99% of less than 00 mesh was used. The properties of the obtained slurry were as follows. Viscosity 3.1 Poise (normal temperature) Particle size 1.8 g / 200 mesh / 100 g Slurry Lead concentration in the slurry 64 ppm

[0010]

Example 2 The same powdery glass frit as in Example 1 was used, and the properties of the glaze slurry mixed with the same composition with a stirrer were as follows. Viscosity 2.5 Poise (at room temperature) Particle size 3.1 g / 200 mesh / 100 g Slurry Lead concentration in the slurry 11 ppm The glaze slurries obtained in Examples and Comparative Examples are glazed on the tile base material on one side at 80 g / sheet, and tunneled. 11 in the kiln
As a result of firing at 00 ° C., a good silver-colored glazed roof tile having a commercial value but having a slight glaze difference was obtained.

[0011]

Industrial Applicability According to the method for producing a glaze for roof tile of the present invention, the amount of lead elution from the glass frit is small and the wastewater treatment is easy to manage, the mill time is short and the glaze for roof tile can be manufactured at a low cost. , Has a remarkable effect.

Claims (1)

[Claims] 1. A method for producing a glaze for earthenware tiles, which comprises adding an appropriate amount of a metal oxide or pigment as a colorant to glass frit, silica stone, feldspar, clay, etc. and wet pulverizing with a ball mill.
A method for producing a glaze for earthenware tiles, which comprises using powdery glass frit which is previously dry pulverized to 100 mesh or less and 99% or more.