JPH0848561A - Clay parts for molten glass - Google Patents

Abstract

PURPOSE:To facilitate casting work at the time of forming clay parts and to obtain clay parts preventing bubbles from entering into molten glass from the surfaces of the inner walls by casting and firing a slurry contg. a specified amt. of Na2O orginated from beta-Al2O3. CONSTITUTION:A slurry contg. sintered alumina and beta-Al2O3 as starting materials and contg. 1-10wt.% Na2O orginated from the beta-Al2O3 is cast and fired to produce the objective clay parts for molten glass, especially an orifice, a plunger rod, a stirrer and a sleeve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractory for a glass industrial furnace, and more particularly to a molten glass creper manufactured by a casting method followed by firing.

[0002]

2. Description of the Related Art The clay parts used for discharging a glass kiln or molten glass are formed of a stable refractory so that no reaction occurs with the molten glass in contact with the inner peripheral wall surface thereof. For example, in order to prevent bubbles generated in the refractory lining the glass kiln feeder part from being mixed in the molten glass and deteriorating the quality of the glass, 0.1 to 0.5% by weight of C is added.
A zircon refractory containing one or more of aO, MgO and Na ₂ O is introduced. (Tokuhei 3
-39986 publication)

In this refractory, sodium carbonate, sodium silicate, sodium phosphate and sodium borate can be used as a source of Na ₂ O. In addition, after applying a solution containing a Na component to the inner peripheral wall surface of the orifice for discharging molten glass, it may be dried or heat-treated, or a reducing agent layer of a metal such as aluminum or chromium may be formed on the outer peripheral wall surface of the orifice. By providing, blocking the approach of oxygen ions in the molten glass,
It has been reported that oxygen bubbles are prevented from being generated on the inner peripheral wall surface of the orifice. (Japanese Utility Model Publication No. 5-62534)

[0004]

By the way, when a solution containing a Na component is added to a raw material (slurry) slurry for casting and molding, the viscosity of the slurry changes, and when molding molten glass clay parts. There is a technical problem that the casting work of the above is difficult, and the clay parts coated with the solution containing the Na component on the inner peripheral wall absorbs moisture in the air due to the nature of the Na component. It is easy to lose the low-foaming effect when stored for a long time after applying the Na component,
There is a technical problem that bubbles such as oxygen are generated in the molten glass, and these bubbles remain in the glass product to significantly reduce the quality of the product.

The present invention has been made in view of such technical problems, and does not change the viscosity of the slurry of the raw material of the clay part, and therefore, in the molding of the clay part. Casting work is easy, and after molding
It is an object of the present invention to provide a creper for molten glass in which bubbles are not mixed into the molten glass from the inner wall surface of the part.

[0006]

The molten glass clay parts according to the present invention, which have been made to achieve the above-mentioned objects, include:
For example, using sintered alumina and β-Al ₂ O ₃ as raw materials,
1 wt% or more of Na ₂ O derived from β-Al ₂ O ₃
0% by weight or less, and after molding by the casting method,
It is characterized by being manufactured by firing. In the molten glass clay parts which have been subjected to such raw material mixing and molding treatment, the viscosity of the slurry which is a raw material for clay glass does not change, and therefore, in the molding of the clay parts. The casting work is easy, and the molten glass clay parts completed by firing can obtain excellent low foaming characteristics. Further, as the clay parts according to the present invention, particularly an orifice, a plunger rod, a stirrer,
A sleeve etc. can be mentioned.

[0007]

In the molten glass cleats of the present invention, it is preferable to contain 1% by weight or more of Na ₂ O derived from β-Al ₂ O ₃ . Content of Na ₂ O is 1% by weight
As a result of experiments, it has been proved that the finished clay parts cannot prevent bubbles from being mixed in the molten glass if the amount is less than the above. Also, the content of Na ₂ O is 10% by weight.
The following is preferred. Β-Al ₂ O ₃ generally contains 10% by weight of Na ₂ O as a reason for not exceeding 10% by weight.
The content of Na ₂ O is not more than 10% by weight, and in order for the content of Na ₂ O to be 10% by weight or more, it is inevitably necessary to further add a substance other than β-Al ₂ O ₃ which serves as a Na ₂ O source. In this case, if the viscosity of the raw material (slurry) slurry becomes too high and it cannot be poured into the casting mold, or if the concentration of the raw material slurry is reduced to reduce the viscosity, the molded body will stick to the mold during demolding, resulting in This makes it impossible to obtain a molded body. Further, as the clay of the present invention, the effect of the present invention can be further obtained when it is used in an orifice used under particularly severe conditions among various clays.

[0008]

EXAMPLES Hereinafter, the molten glass scraper according to the present invention
Will be described with reference to the drawings. FIG. 1 shows an example of a glass gob feeder having a molten glass discharge orifice. This glass gob feeder is a spout 2 provided at the tip of a feeder for guiding the melted molten glass 1 and a molten glass spouting orifice provided in a bottom opening 2a of the spout 2 and having a spouting hole 3a in the center. It is composed of 3. Although not shown, a stirrer is provided on the right side to which the molten glass is supplied. Inside the spout 2, a rotary sleeve 4 for stirring the molten glass 1 and a plunger rod 5 that moves up and down on the axis of the rotary sleeve 4 are arranged.

In the glass gob feeder thus constructed, the vertical movement of the plunger rod 5 causes
Molten glass 1 is discharged from a discharge hole 3a provided at the center of orifice 3, and glass gob 1a is supplied onto, for example, a glass shaping mold (not shown). The molten glass orifice 3, sleeve 4, plunger rod 5, and stirrer are, for example, as described above, for example, sintered alumina and β-.
Al ₂ O ₃ is used as a raw material, Na ₂ O derived from β-Al ₂ O ₃ is contained in an amount of 1% by weight or more and 10% by weight or less, and it is manufactured by firing after molding by a casting method.

In this case, β-Al ₂ O is used as the Na ₂ O source.
_The reason why ₃ is used is that when β-Al ₂ O ₃ is added as a Na component to a raw material slurry for casting molding, the viscosity of the slurry does not change and casting molding becomes possible. Next, Examples of the molten glass orifice of the present invention are shown in Table 1 below. That is, Table 1 shown below
Example No. 1 to Example No. No. ₃ was obtained by weighing a predetermined amount of sintered alumina and β-Al ₂ O ₃ and then adding water and a dispersant and stirring and mixing to obtain a slurry for casting, and the slurry was a gypsum mold of 65 × 65 × 230 mm. A refractory sample was prepared by casting in a mold, demolding and baking. Each refractory sample obtained in this manner was treated with 15 × 15
It was cut out to x10 mm to obtain a test piece for foaming test. In the foaming test, print glass was placed on a test piece, heated at 1250 ° C. for 30 minutes in an electric furnace, then cooled to room temperature, immersed in dimethyl phthalate, and the condition of bubbles was observed with a microscope. The apparent porosity (%), bulk specific gravity and compressive strength (MPa) were also measured, and the results are shown in Table 1.

[0011]

[Table 1]

In Table 2, Comparative Example No. 1 to No. 5
Indicates. In this comparative example, sintered alumina and β-Al ₂ O _{3 are used.}
(Comparative Example No. 2), sintered alumina (Comparative Example No. 1, Comparative Example No. 3, Comparative Example N)
o. 4), or sintered alumina and β-Al ₂ O ₃ with N
Water and a dispersant were added to a mixture of a ₂ CO ₃ (Comparative Example No. 5) and the mixture was stirred and mixed to obtain a slurry for casting. Then, in Comparative Examples 1 and 2, the slurry was cast into a plaster mold of 65 × 65 × 230 mm, demolded, and dried and fired. 1 of each refractory sample obtained in this way
A test piece having a size of 5 × 15 × 15 mm was cut out to obtain a test piece. In Comparative Example 5, a molded body was not obtained.

In Comparative Example 3, the slurry was mixed with 65 × as described above.
Each refractory sample thus obtained was cast into a plaster mold of 65 × 230 mm, demolded, and then dried and baked.
A test piece having a size of mm was cut out, and the refractory sample was dipped in a saturated borax aqueous solution and then dried to obtain a test piece. In Comparative Example 4, the slurry was 65 × 65 × 2.
After casting in a 30 mm plaster mold, demolding and drying and firing, each refractory sample thus obtained was cut into a test piece shape of 15 × 15 × 15 mm, further immersed in a saturated borax aqueous solution, and then dried. A heat treatment was performed at 500 ° C. or higher to obtain a test piece.

The test piece thus treated was subjected to a foaming test in the same manner as in the examples. An attempt was made to add a saturated aqueous solution of borax to the slurry obtained for casting, but the viscosity of the slurry increased and it was difficult to supply it to the gypsum mold, making it impossible to perform molding. Also, the apparent porosity (%), bulk specific gravity, and compressive strength (MPa) were measured,
The results are also shown in Table 2.

[0015]

[Table 2]

As can be understood from several examples of the present invention and comparative examples shown in Tables 1 and 2, Na ₂ O
Is less than 1% by weight, the orifices after completion are in the molten glass except for the orifices shown in Comparative Examples 3 and 4 which are obtained by immersing in a saturated borax aqueous solution after firing and then drying. As a result of the experimental comparison, it was found that the inclusion of bubbles cannot be prevented.

Further, in Comparative Example No. As shown in 5, Na ₂
When the content of O exceeds 10% by weight, the content of substances other than β-Al ₂ O ₃ must be inevitably increased, and the viscosity of the raw material (slurry) slurry changes, and The casting work in forming the orifice became difficult, and a molded body could not be obtained.

Comparative Example No. 3 and No. As can be seen from FIG. 4, even when the product was soaked in a saturated borax aqueous solution after firing and then dried, no foam was observed as in this example as a result of the foaming test, but it is said that post-treatment is required. It is inferior to the present invention in that it is more likely to absorb moisture in the air due to the characteristics of the Na component, and when the Na component is stored for a long period of time, the low foaming effect cannot be obtained. There is a problem of. Incidentally, the molten glass for clay of the present invention - Pa - said used to Tsu beta-Al ₂
It is also possible to use electroformed alumina brick scraps as O ₃ .

[0019]

As is apparent from the above description, Kure for molten glass according to the present invention - Pa - tree, for example by adding β-Al ₂ O ₃ in the sintered alumina, derived from β-Al ₂ O ₃ Since the content of Na ₂ O to be contained is 1 wt% or more and 10 wt% or less, the viscosity of the slurry does not change,
It is possible to easily mold the clay parts by the cast molding method. In addition, it is possible to provide a crepe part for molten glass having excellent low foaming characteristics without performing a post-treatment such as applying a solution containing a Na component.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a glass gob feeder using the molten glass clay parts of the present invention.

[Explanation of symbols]

 1 Molten Glass 1a Glass Gob 2 Spout 2a Bottom Opening 3 Orifice 3a Discharge Hole 4 Sleeve 5 Plunger Rod

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location C03B 7/088 C04B 35/101 35/66 C04B 35/68 (72) Inventor Kazuhiro Iwakawa Kariya Aichi Prefecture No. 1 Minamifuji, Ogakie-cho, Shiga, Toshiba Corporation Ceramics Co., Ltd. Kariya Plant (72) Inventor Takaaki Hirano No. 1, Minamifuji, Ogakie-cho, Kariya City, Aichi Toshiba Ceramics Co., Ltd. Kariya Plant (72) Inventor Mitsuo Yoshida Kawasaki, Kanagawa Prefecture Toyo Glass Co., Ltd.

Claims (5)

[Claims] 1. Na ₂ O derived from β-Al ₂ O ₃
A melt glass creper containing at least 10% by weight and manufactured by firing after molding by a casting method. 2. The molten glass kraper according to claim 1, wherein the kraper is an orifice. 3. The creper for molten glass according to claim 1, wherein the crepe is a sleeve. 4. The crepe for molten glass according to claim 1, wherein the crepe is a plunger rod. 5. The molten glass cleats according to claim 1, wherein the cleats are stirrers.