JPH1135338A - Antimony based clarificant for melting glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a clarificant for melting glass having no toxicity and capable of releasing gaseous oxygen at a high temp. side by incorporating a multiple oxide of a specified metallic element and pentavalent Sb and a refractory material. SOLUTION: The multiple oxide of at least one kind metallic element selected among Mg, Zn, Ca, Sr, Ba, Li, K, Al, Si, Ti, Sn, Zr, Ce, La, Na and P and the pentavelent Sb and, if necessary, the refractory material selected among alumina, mullite, zirconia and titania are blended so that weight ratio may be 1:(9-7):3, and after subjecting the blended matter to a dry mixing, the mixture is burned, ground and classified to obtain an antimony based clarificant for melting glass. The temp. of converting pentavalent Sb to tervalent Sb is raised and the temp. of liberating the gaseous oxygen is raised since Sb exists stably in the pentavalent state up to more high temp. range as compared to Sb2 O5 in the antimony based clarificant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antimony fining agent used in a step of heating and melting glass raw materials.

[0002]

2. Description of the Related Art In melting glass, various fining agents are used to reduce bubbles contained in the molten glass. Especially, with As ₂ O ₃ and Sb ₂ O ₃ content _of superior refining effect, has been widely used as a fining agent for a long time.

When As ₂ O ₃ or Sb ₂ O ₃ is used, a large amount of O ₂ gas is released in a temperature range where a vitrification reaction starts and a melt is homogenized. When a large amount of O ₂ gas is released,
The O ₂ gas concentration in the glass melt becomes extremely high and becomes large O ₂ bubbles and floats in the glass melt. At this time, minute bubbles existing in the melt are taken in by large O ₂ bubbles. As a result, bubbles in the glass can be significantly reduced.

[0004]

In the case of glass having a high melting temperature, such as crystallized glass and non-alkali glass, it is necessary to select a fining agent capable of releasing O ₂ gas at a high temperature. However, Sb ₂ O ₃ has a relatively low O ₂ gas release temperature, and a sufficient fining effect cannot be obtained at high temperatures. On the other hand, As ₂ O ₃ is capable of releasing O ₂ gas at a high temperature, and is therefore widely used as a fining agent for such glass.

[0005] However, As ₂ O ₃ is highly toxic,
There is a possibility of causing an environmental problem during a glass manufacturing process, at the time of treating waste glass, and the like, and its use is being restricted.

An object of the present invention is to provide a fining agent for glass melting which can release O ₂ gas at a high temperature similarly to As ₂ O ₃ .

[0007]

The antimony fining agent for glass melting of the present invention comprises Mg, Zn, Ca, Sr, Ba,
Li, K, Al, Si, Ti, Sn, Zr, Ce, L
at least one element selected from a, Nb and P and pentavalent Sb
Characterized by comprising a multiple oxide of

The antimony fining agent for melting glass of the present invention comprises a complex of a complex oxide and a refractory material, wherein the complex oxide is Mg, Zn, Ca, Sr, Ba, Li, K, A
It contains one or more elements selected from l, Si, Ti, Sn, Zr, Ce, La, Nb, and P, and pentavalent Sb.

[0009]

[Function] Sb ₂ O ₃ added to the glass raw material composition is
Sb ₂ O ₅ once in the temperature range of 600 to 1000 ° C.
At around 1100 ° C., O ₂ gas is released and returns to Sb ₂ O ₃ again. Glass melting antimony fining agents of the present invention, on the other hand, compared to the Sb ₂ O _5, Sb up to a higher temperature range is 5
Since Sb exists stably in a valence state, the temperature at which Sb changes its valence from pentavalent to trivalent increases, and the temperature at which O ₂ gas is released also increases.

Therefore, the antimony fining agent of the present invention comprises:
Excellent fining effect can be exhibited in a high temperature range.

The antimony fining agent of the present invention comprises Mg, Z
n, Ca, Sr, Ba, Li, K, Al, Si, Ti,
It comprises a complex oxide of at least one element selected from Sn, Zr, Ce, La, Nb, and P and pentavalent Sb. Representative examples of these complex oxides are shown below.

[0012] · Mg-based _{2MgO · Sb 2 O 5, 7MgO} · Sb 2 O 5, · Zn -based _{2ZnO · Sb 2 O 5, 7ZnO} · Sb 2 O 5, · Ca -based _{3CaO · Sb 2 O 5, 6CaO} · Sb ₂ O _5, · Sr based _{2SrO · Sb 2 O 5, 6SrO} · Sb 2 O 5, · Ba system _{BaO · Sb 2 O 5, 4BaO} · Sb 2 O 5, · Li system _{Li 2 O · Sb 2 O 5} , _{2Li 2 O · Sb 2 O 5} , · K system _{K 2 O · Sb 2 O 5} , · La system LaSbO _4, · Nb system SbNbO _5, · Ca-Sr system _{Sr (Ca 0.33 Sb 0.67) O} 3, · Li -Zn system LiZnSbO _4, · Li-Ti-based _{Li 1.5 Ti 1.0 Sb 0.5 O 4} , · Ba-Al -based _{Ba 2 Al 0.5 Sb 0.5 O 6} , · Ba-Ce -based _{Ba 2 Ce 0.75 SbO 6, ·} Zr-P System ZrSbPO ₇ , Ba-Sn system Ba (Sb _0.5 Sn _0.5 ) O ₃ , Li-Si based LiSiSbO ₅ , Li-Zr-Si based Li ₂ Zr ₂ Sb ₂ SiO ₁₁

In the present invention, in order to obtain a refining effect at a higher temperature, it is preferable to form a complex oxide 1 containing pentavalent Sb with a refractory substance 2 as shown in FIG. . Alumina, mullite, zirconia, titania and the like can be used as the refractory substance. The ratio between the complex oxide and the refractory substance is not particularly limited, but the proportion of the complex oxide to the refractory substance is 1: 9 to 7: 3 by weight.
Is preferably within the range.

When such a complex is used, pentavalent S
The speed at which the mixed oxide containing b melts into the glass is reduced. As a result, the decomposition of the composite oxide is delayed, and the temperature range for releasing the O ₂ gas is further shifted to a higher temperature side, so that a higher fining effect is obtained as compared with the case where the composite oxide containing pentavalent Sb is used alone. be able to.

The antimony fining agent of the present invention can be used in combination with other fining agents (eg, halides such as salt, sulfates such as sodium sulfate, tin oxide, etc.). By using it, the refining effect can be further enhanced.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.

[0017] (Example 1) fining agent, antimony barium _{(BaO · Sb 2 O 5)} , the effect of using lithium antimonate _{(Li 2 O · Sb 2 O} 5),
Antimony trioxide (Sb ₂ O) conventionally used
₃ ) Compare with.

The synthesis of barium antimonate and lithium antimonate was performed as follows. First, antimony trioxide and barium carbonate, or antimony trioxide and lithium carbonate are blended so as to have the above molar ratio, and dry-mixed by a ball mill, and then placed in a ceramic container made of alumina. Temperature at a rate of 1 minute
It was synthesized by firing at 200 ° C. for 3 hours. Subsequently, the fired product was pulverized with a ball mill and classified to obtain a powder having a size of 74 μm or less.

Next, as an oxide glass composition, S
iO ₂ 67.0%, Al ₂ O ₃ 22.0%, Li ₂ O
4.0%, MgO 0.5%, BaO 0.5%, P _{2
O 5 0.9%, TiO 2 1.5} %, ZrO 2 2.
A glass containing barium antimonate as a fining agent using the glass raw materials shown in Table 1 so as to have a low-expansion crystallized glass composition of 5%, 1.1% Na ₂ O, and 1% Sb ₂ O _3. A batch (batch 1), a glass batch containing lithium antimonate (batch 2), and a glass batch containing antimony trioxide (batch 3) were prepared. In batch 3, nitrate (nitrate) was used in an amount three times that of antimony trioxide as usual.

[0020]

[Table 1]

Subsequently, each glass batch was weighed and placed in a platinum crucible to obtain 600 g of glass.
Melted at 0 ° C. for 10 hours. No stirring was performed during the melting.

Thereafter, the molten glass was poured into a stainless plate and formed into a thin plate, and the number of bubbles present in the glass was counted. From the results of the fining test on the laboratory scale and the actual results in the actual glass melting furnace, if the number of bubbles is about 6 × 10 ³ / kg in the test in the laboratory, it is sufficient in the actual operation. It has been found that glass with less bubbles can be obtained.

As a result, the glass produced using Batch 3 had bubbles of 40 × 10 ³ / kg, whereas
5 × 10 ³ glass / k produced using batch 1
g, batch 2 produced 6 × 10 ³ glass /
kg.

Example 2 The effect of using a composite of barium antimonate and alumina as a fining agent was as follows:
Compare with antimony trioxide (Sb ₂ O ₃ ).

The composite of barium antimonate and alumina was synthesized as follows. First, barium antimonate powder was prepared in the same manner as in Example 1. Next, 45% by weight of barium antimonate powder and 55% by weight of alumina powder were mixed, and 3 parts by weight of polyvinyl alcohol as a binder and an appropriate amount of water were added to form a slurry. Thereafter, the particles were granulated to a size of about 50 μm in outer diameter using a spray drier to obtain composite particles of barium antimonate and alumina.

Next, as an oxide glass composition, S
iO ₂ 60.0%, Al ₂ O ₃ 15.0%, B ₂ O ₃
10.0%, CaO 5%, SrO 5%, BaO
A glass batch containing a composite of barium antimonate and alumina as a fining agent using the glass raw materials shown in Table 2 so as to have an alkali-free glass composition of 5.0% and Sb ₂ O ₃ 1.5% ( Batch 4) and a glass batch containing antimony trioxide (batch 5) were prepared.

[0027]

[Table 2]

Subsequently, each glass batch was weighed so as to obtain 600 g of glass, and the glass was melted and formed in the same manner as in Example 1, and the number of bubbles present in the glass was counted.

As a result, the glass produced using Batch 5 had bubbles of 50 × 10 ³ / kg, whereas
6 × 10 ³ glass / kg made using batch 4
Met.

[0030]

The antimony-based fining agent for glass melting of the present invention does not use highly toxic As ₂ O ₃ , and therefore does not easily cause environmental problems during the glass production process or the treatment of waste glass. Moreover, since O ₂ gas is released on the higher temperature side than Sb ₂ O _3, it has an excellent fining effect and can be suitably used as a fining agent for high-temperature molten glass.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an antimony-based fining agent for glass melting of the present invention.

[Explanation of symbols]

 1. Double oxide containing pentavalent Sb 2. Refractory material not containing Sb

Claims (5)

[Claims] 1. Mg, Zn, Ca, Sr, Ba, Li,
K, Al, Si, Ti, Sn, Zr, Ce, La, N
An antimony fining agent for melting glass, comprising a double oxide of at least one element selected from b and P and pentavalent Sb. 2. 2MgO.Sb ₂ O ₅ , 7MgO.Sb
₂ O ₅ , ₂ ZnO · Sb ₂ O ₅ , 7 ZnO · Sb ₂ O
_{5, 3CaO · Sb 2 O 5} , 6CaO · Sb 2 O 5, 2
_{SrO · Sb 2 O 5, 6SrO} · Sb 2 O 5, BaO ·
Sb ₂ O ₅ , 4BaO.Sb ₂ O ₅ , Li ₂ O.Sb _{2
O 5, 2Li 2 O · Sb} 2 O 5, K 2 O · Sb 2 O 5,
LaSbO ₄ , SbNbO ₅ , Sr (Ca _0.33 S
b _0.67 ) O ₃ , LiZnSbO ₄ , Li _1.5 Ti _1.0 S
b _0.5 O ₄ , Ba ₂ Al _0.5 Sb _0.5 O ₆ , Ba ₂ Ce
_0.75 SbO ₆ , ZrSbPO ₇ , Ba (Sb _0.5 Sn
_0.5 ) O ₃ , LiSiSbO ₅ , Li ₂ Zr ₂ Sb ₂ S
antimony fining agent for glass melting of claim 1, characterized in that either iO _11. 3. A composite of a complex oxide and a refractory material, wherein the complex oxide is Mg, Zn, Ca, Sr, Ba, Li,
K, Al, Si, Ti, Sn, Zr, Ce, La, N
An antimony fining agent for melting glass, comprising at least one element selected from b and P and pentavalent Sb. 4. The composite oxide is 2MgO.Sb ₂ O ₅ , 7
_{MgO · Sb 2 O 5, 2ZnO} · Sb 2 O 5, 7ZnO
_{· Sb 2 O 5, 3CaO ·} Sb 2 O 5, 6CaO · Sb
₂ O ₅ , 2SrO.Sb ₂ O ₅ , 6SrO.Sb ₂ O
_{5, BaO · Sb 2 O 5} , 4BaO · Sb 2 O 5, Li
₂ O.Sb ₂ O ₅ , 2Li ₂ O.Sb ₂ O ₅ , K ₂ O.
Sb ₂ O ₅ , LaSbO ₄ , SbNbO ₅ , Sr (Ca
_0.33 Sb _0.67 ) O ₃ , LiZnSbO ₄ , Li _1.5 Ti
_1.0 Sb _0.5 O ₄ , Ba ₂ Al _0.5 Sb _0.5 O ₆ , Ba
₂ Ce _0.75 SbO ₆ , ZrSbPO ₇ , Ba (Sb _0.5
Sn _0.5 ) O ₃ , LiSiSbO ₅ , Li ₂ Zr ₂ Sb
₂ antimony fining agent for glass melting in claim 3, characterized in that either SiO _11. 5. The antimony fining agent for glass melting according to claim 3, wherein the refractory substance is any one of alumina, mullite, zirconia and titania.