JPH0448737B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is a method for producing foam glass using a continuous melting furnace, which can uniformly generate bubbles of uniform size by using the foreharth section of the continuous melting furnace. This relates to a manufacturing method.

(Prior art) Foam glass containing a large number of bubbles inside has been known for a long time, but in the conventional glass, a blowing agent such as calcium carbonate or magnesium carbonate is placed inside a crucible and stirred. It was manufactured using an artificial blowing method in which carbon dioxide gas produced when a blowing agent decomposes is distributed in the glass as bubbles.
However, when this method is applied to a continuous melting furnace and a blowing agent is introduced into the forehearth, bubbles of various sizes are generated, with a maximum particle size of several mm or more, and the glass may take a long time to reach the spout. Most of the bubbles floated to the surface, leaving a glass layer with almost no bubbles at the bottom, making it impossible to uniformly disperse the bubbles in the molded product. Another problem was that a layer of aggregated air bubbles was formed on the surface layer, and if this entered the molded product, it would cause defects such as chipping.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems and provides a foam glass in which bubbles of approximately uniform particle size are uniformly dispersed using a continuous melting furnace. It was completed with the aim of creating a method for producing foam glass using a continuous melting furnace.

(Means for Solving the Problems) The present invention introduces reducing frit onto the surface of oxidizing glass melted in a continuous melting furnace, and after a predetermined period of time, stirs it uniformly into the glass to dissolve the original glass. It is characterized by generating countless bubbles with a particle size of 0.5 to 1.5 mm upon reduction.

In the present invention, oxidizing glass is first melted in a continuous melting furnace according to a conventional method. The terms oxidizing glass and reducing glass are relative expressions and do not have precise definitions, but
In this industry, we focus on the concentration of S in glass as shown in Figure 1, and consider the glass with a high concentration of S ⁶⁺ to be an oxidizing glass, and the glass with a high concentration of S ^2- to be a reducing glass. Since it is called a synthetic glass, it will be used in this sense in this specification as well.

Common soda-lime glass that does not contain a colorant is an oxidizing glass, and its typical composition is as shown in the Examples below.

A reducing frit is introduced onto the surface of such oxidizing glass. Reducing frits are made by containing a strong reducing agent such as metal silicon in low-melting glass, but it is also possible to use pellet-shaped unmolten raw materials containing metal silicon. . The input amount is usually about 0.5 to 10% of the amount of oxidizing glass flowing out. If you start stirring immediately after adding the reducing frit to get it into the glass, a violent reaction will occur and the particle size of the bubbles will increase. After adjusting the reducing power by reacting with oxygen in the atmosphere, the mixture is stirred uniformly into the glass using a stirrer or the like. As a result, the oxidizing glass and the reducing frit react with each other, and countless bubbles having a particle size of 0.5 to 1.5 mm are uniformly generated. The reason why the particle size of the bubbles is set to 0.5 to 1.5 mm is because bubbles smaller than 0.5 mm are too small and have little commercial value, and vice versa.
This is because if it exceeds 1.5 mm, the floating ability in glass at about 1200° C. increases, and it becomes easier to float to the surface layer within 1 to 2 hours, which is the normal residence time in the glass. Therefore, the air bubbles having a particle size of 0.5 to 1.5 mm are maintained in a uniformly dispersed state up to the spout, and the air bubbles can be uniformly dispersed in the molded product.

Next, preferred embodiments of the present invention will be shown.

(Example) Example 1 SiO ₂ 72.0% (weight %, same below), Al ₂ O ₃
2.0%, CaO 11.5%, Na ₂ O 13.5%, K ₂ O 1.0
% of oxidizing glass was melted in a continuous melting furnace and introduced into a forhearth at a flow rate of 25 tons/day. Apart from this, SiO ₂ 58.2%, Al _2
O3 2.0%, _{B2O3 12.3} %, _Na2O 22.7%, _K2
A reducing frit with a composition of 1.3% O and 3.5% Si was prepared, and the amount was 21 kg/hour (2.0% of the flow rate).
It was put into the forharth at a rate of . The glass temperature at the frit injection part was maintained at 1250°C. The reducing frit was left to react with oxygen in the air by leaving it at the stirrer installation position approximately 0.5 m away from the input position, and the reducing frit was stirred uniformly by the stirrer to be engulfed in the oxidizing glass. As a result, a glass in which countless air bubbles with a particle size of 0.8 to 1.2 mm were uniformly dispersed was obtained. When glass tableware was molded using this glass, a product with excellent appearance was obtained, with countless air bubbles dispersed within the colorless and transparent glass.

Example 2 Oxidizing glass having the same composition as in Example 1 was melted in a continuous melting furnace and introduced into a forharse at a flow rate of 15 tons/day. Apart from this, SiO ₂
57.2%, _{Al2O3 2.0} %, _{B2O3 12.3} %, _Na2O
21.7%, _K2O 1.3%, Si 5.0%, _{Cr2O3 0.5} %
A reducing frit with a composition of 21.9 kg/hour (3.5% of the outflow amount) was prepared and charged into the forherse. This was left as it was at the stirrer installation position 0.5 m away, and then stirred with the stirrer. When glass tableware was molded using this glass using a conventional method, a beautiful product was obtained in which countless air bubbles with a particle size of 0.5 to 1.0 mm were uniformly dispersed in the green glass. In addition, when the moil at the mouth of this product was cut, no cracking occurred at all.

(Effects of the Invention) As is clear from the above description, the present invention is capable of obtaining glass in which bubbles with a particle size of 0.5 to 1.5 mm are uniformly dispersed using a continuous melting furnace. Unlike conventional methods, there is no risk of bubbles concentrating on the surface layer, and since the bubbles have a small diameter, chips will not occur when the product is manufactured. Therefore, according to the present invention, it is possible to easily mass-produce glass products with excellent aesthetic appearance. Therefore, the present invention greatly contributes to the development of industry as a method for manufacturing foam glass using a continuous melting furnace that eliminates the problems of the conventional method.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between the concentration of S in glass and the oxidizing and reducing properties of the glass.

Claims (1)

[Claims] 1 A reducing frit is added to the surface of oxidizing glass melted in a continuous melting furnace, and after a predetermined period of time, the original glass is reduced by stirring uniformly into the glass to form particles with a particle size of 0.5 to 1.5 mm. A method for producing foam glass using a continuous melting furnace, which is characterized by generating countless bubbles.