JP2002128528A - Method of manufacturing glass and apparatus for melting glass therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing high-quality glass by using raw materials having high reactivity and an apparatus for melting glass therefor. SOLUTION: In the method of manufacturing glass by adding glass raw materials to a molten glass in a heated container and melting, (1) an oxidizing gas is bubbled to the molten glass and the glass raw materials, which show reductivity in the melting process, are added into the bubbling position, or (2) a dry atmosphere gas is filled in the container and the atmosphere gas is fed to the surface of molten glass liquid along the path for adding the glass raw materials, and the glass raw materials are added. The apparatus for melting glass in the method is also claimed.

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 glass and a glass melting apparatus used for the method. More specifically, the present invention relates to a method for producing glass for obtaining high-quality glass using a raw material having particularly high reactivity, and a glass melting apparatus used for the method.

[0002]

2. Description of the Related Art The refractive index [nd] is low and the Abbe number [ν]
d] is large and the optical glass exhibiting positive anomalous dispersion is
It is one of the important glasses for optical design used to modify the secondary spectrum. Examples of such optical glass include JP-A-60-81042 and JP-A-62-10045.
Fluorophosphate glass described in Japanese Patent Publication No. 2 (Kokai) No. 2 is cited. The fluorophosphate glass is a metaphosphate compound M (PO ₃ ) x
And fluorinated compound MFx (where M is an alkali metal element,
The alkaline earth metal element or another metal element, x represents the valence of M. ) Is used as a raw material, and the raw material can be melted to produce the compound.

[0003] This fluorophosphate glass is a useful glass, but exhibits extremely strong corrosiveness when melting glass raw materials. Therefore, even if it is melted using a container made of platinum with excellent erosion resistance, it erodes platinum, and the eroded platinum becomes fine particles and mixes into the molten glass to become a scattering source of light, and the quality of the glass There was a problem that it reduced.

[0004] Therefore, a method for producing a glass containing a large amount of fluorine for the purpose of reducing the contamination of the glass due to the embrittlement damage of the melting vessel and defoaming and homogenizing the glass has been proposed (Japanese Patent Publication No. 8-25749). ). However, in this production method, even if the defoaming promoting effect is obtained, it is not possible to completely prevent the glass contamination caused by the container erosion. Further, this method has a problem that the raw material composition cannot be avoided.

[0005] Further, there has been reported a method of reducing platinum contamination by melting a metaphosphate M (PO ₃ ) x, which is a raw material of phosphate glass, after heat treatment [“Platinum Metals Review”]. Vol. 36, No. 1, 14
~ 25 pages (1992)]. In this method, a glass material is heated at 920 to 1050 ° C. and then melted. However, in this method, there may be no problem in the case of using only a metaphosphoric acid raw material having a vitrification temperature as high as 1100 to 1200 ° C.
It cannot be used as a raw material mixed with a fluorine compound raw material which is vitrified at ° C. Therefore, it cannot be applied to glass composition raw materials having a vitrification temperature of 1000 ° C. or lower, such as fluorophosphate glass. If you try to apply it, M (P
Heating the O ₃ ) x raw material, and heating the M (PO)
₃ ) A step of mixing the x raw material and another raw material, a fluorine compound MFx raw material, is required, which causes a problem that the manufacturing process is complicated and the manufacturing cost is inevitably high.

Further, in the melting of the fluorophosphate glass, a reaction product of the glass vapor at the time of melting and moisture in the atmosphere solidifies in the melting vessel, reacts with the glass raw material to block the raw material inlet, or The coagulated material falls into the molten glass, violently foams, or remains in the glass as an undissolved material, causing undesirable situations. As a result, problems such as deterioration of glass quality and productivity are caused. At present, it is difficult to produce high-quality fluorophosphate glass at a mass production level for the above reasons.

On the other hand, even when borosilicate glass is melted, a large amount of water is released when the glass material is melted to clog the material inlet, or boric acid volatilizes and solidifies in a melting vessel to melt the fluorophosphate glass. A similar problem has occurred.

[0008]

SUMMARY OF THE INVENTION Under such circumstances, the present invention aims to remove components which exhibit high reactivity or easily volatilize during the melting process, such as the production of fluorophosphate glass and borosilicate glass. It is an object of the present invention to provide a method for producing glass for producing high-quality glass using a glass raw material containing the same, and a glass melting apparatus used for the method.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, while bubbling an oxidizing gas into the molten glass, the molten glass was melted at the bubbling position during the melting process. A method of charging a glass material exhibiting reducibility, or a method of filling a container with a dry atmosphere gas and charging the glass material while flowing the atmosphere gas to a molten glass liquid surface along a glass material charging path, The inventor has found that the object can be achieved by a glass melting apparatus having a specific structure capable of implementing these methods, and based on this finding, the present invention has been completed.

That is, the present invention provides: (1) a method for producing glass comprising a step of charging a molten glass in a heated vessel with the raw material of the glass and melting the molten glass; , And a glass material exhibiting reducibility in a melting process is introduced into the bubbling position (hereinafter, referred to as a manufacturing method I).

(2) To the molten glass in the heated container,
A method for producing glass, comprising a step of charging and melting a raw material of the glass, wherein the container is filled with a dry atmosphere gas, and the atmosphere gas is supplied to a molten glass liquid surface along a charging path of the glass raw material. A method for producing glass characterized by introducing a glass raw material while flowing (hereinafter referred to as a production method)
Called II. ),

(3) A glass melting apparatus for charging a glass raw material, heating and melting to obtain a molten glass, comprising a container for melting the glass raw material, and an oxidizing gas for supplying an oxidizing gas to the molten glass in the container. A glass melting device (hereinafter, referred to as a glass melting device I) comprising, as main components, a gas supply port and a raw material charging port for charging a glass raw material disposed above the oxidizing gas supply port. ), And

(4) A glass melting apparatus for charging a glass raw material, heating and melting to obtain a molten glass, wherein the glass raw material is heated and melted, and a container for storing the obtained molten glass; An atmosphere gas supply port for supplying a dry atmosphere gas that fills the container, an atmosphere gas exhaust port for exhausting the atmosphere gas, and an atmosphere gas supply port provided as a main component; A glass melting apparatus characterized in that the inside of the container is divided so that a flow path of an atmospheric gas is formed from a mouth to a molten glass liquid surface along a glass raw material charging path and reaches an exhaust port. (Hereinafter, referred to as a glass melting apparatus II).

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing glass according to the present invention is a method for producing glass comprising a step of charging a raw material for glass into a molten glass in a heated container and melting the glass.
Two modes, namely, (1) a method in which an oxidizing gas is bubbled into a molten glass and a raw material exhibiting reducibility in a melting process is introduced into the bubbling position (manufacturing method I), and (2) the above method There is a method (manufacturing method II) of charging a glass material while filling the inside of the container with a dry atmosphere gas and flowing the atmosphere gas to a molten glass liquid surface along a glass material charging path.

In the above-mentioned production method I, the glass raw material which exhibits a reducing property in the course of melting is a raw material which produces a substance which corrodes the above-mentioned container (particularly a container made of platinum or a platinum alloy) in the course of melting. And the raw material of phosphate glass and the like correspond to such a raw material. The oxidizing gas is
A gas capable of oxidizing a reducing substance generated from the glass raw material, and corresponds to an oxygen gas or the like. The above-mentioned production method I is preferably applied when a metaphosphate compound is used as a glass raw material and a phosphate glass is melted, particularly when a metaphosphate compound and a fluorine compound are used as glass raw materials and a fluorophosphate glass is melted.

On the other hand, in the production method II, a fluorine compound is used as a glass raw material and a fluoride glass is melted, particularly a fluorine compound and a metaphosphate compound are used, and a fluorophosphate glass is melted or a borate compound is used. ,
It is preferably applied when melting boric acid-containing glass.

Fluorophosphate glass is an optical glass having a large νd value due to elemental fluorine and showing a large positive anomalous dispersibility, and is made of a fluorine compound MFx and a metaphosphate compound M ′ (PO ₃ ) x ′. It is made by melting these. Here, M and M 'each represent a metal element, and are, for example, one or more metal elements composed of an alkali metal element, an alkaline earth metal element, or another metal element, and x and x' Represents the valence of M and M ', respectively.

The raw materials of the fluorophosphate glass include aluminum fluoride AlF ₃ , magnesium fluoride MgF ₂ , calcium fluoride CaF ₂ , strontium fluoride Sr
For example, a mixture of F ₂ , yttrium fluoride YF ₃ (above, a fluorine compound), aluminum metaphosphate Al (PO ₃ ) ₃ , and barium metaphosphate Ba (PO ₃ ) ₂ (above, a metaphosphate compound) can be exemplified. it can. In addition, KPO
₃ , NaPO ₃ , H ₃ PO ₄ , P ₂ O ₅ , Nd ₂ (PO ₃ ) ₃ or the like may be used. The phosphate compound is a raw material for phosphate glass.

This glass raw material is put into molten glass in a container heated to about 800 to 1000 ° C.,
Among the glass raw materials, the metaphosphate compound M (PO ₃ ) x is decomposed at the time of melting to generate free phosphorus having a strong reducing action.
The free phosphorus erodes the container made of platinum, and the eroded platinum fine particles are mixed into the molten glass, and serve as a light scattering source, thereby deteriorating the quality of the glass.

In order to solve such a problem, in the present invention, the above-mentioned manufacturing method I and manufacturing method II can be applied. First, the manufacturing method I will be described. In the production method I of the present invention, an oxidizing gas is supplied to the molten glass and bubbling is performed. Then, a metaphosphoric acid compound is introduced into a position where the oxidizing gas is bubbled. The introduced metaphosphate compound is decomposed to generate free phosphorus exhibiting a strong reducing action, but the free phosphorus is quickly oxidized by bubbles of an oxidizing gas before coming into contact with the inner surface of the container, thereby preventing erosion of the container.

By oxidizing free phosphorus, which is a decomposition product of the metaphosphate compound, melting of the glass is promoted, and phosphate glass can be obtained efficiently.
Oxidizing gases not only oxidize free phosphorus,
An upward convection is generated at the position where the metaphosphate compound is charged. Usually, the charged raw material settles and reaches the bottom of the container, but the convection due to bubbling slows down the settling speed of the raw material. Therefore, the raw material is decomposed before reaching the container bottom, and the generated free phosphorus is also oxidized, so that erosion of the container bottom can be effectively prevented.

In this production method I, it is preferable that an oxidizing gas is bubbled at the center of the liquid surface of the molten glass, and that a metaphosphoric acid compound is introduced into the bubbling position.
By doing so, it is possible to make it difficult for free phosphorus generated by the decomposition of the raw material to reach the container wall surface, and to stir the molten glass in the container.

The oxidizing gas used for bubbling is preferably a dry gas containing an oxygen gas such as an oxygen gas or a mixed gas of an oxygen gas and an inert gas. The oxidizing gas is desirably used in a dry state for the reason described later, and the content of moisture in the bubbling gas is set to 4.
It is preferable to use a gas which has a dew point of not more than 25 ppm by volume or -70 ° C or less. The amount of oxygen gas is 50 ~ 5
It is preferably set to 00 cc / min.

The bond dissociation energy between fluorine and a metal in a fluorine compound as a glass raw material is 51% for F-Mg.
1.7 kJ / mol, 587.7 kJ / m for F-Al
ol and F-Ca are 556.17 kJ / mol, which is about 5
It is more than 00 kJ / mol. On the other hand, the bond dissociation energy of O—Mg is 336.87 kJ / mol,
In Al, which is smaller than the bond dissociation energy with F, such as 478.7 kJ / mol, the bubbled oxygen gas does not cut off the bond between fluorine and the metal and does not drive fluorine out of the glass. Therefore, oxygen gas oxidizes free phosphorus, but it is difficult to oxidize fluorine to reduce the fluorine content in the glass, so that it is suitable as a bubbling gas for producing fluorophosphate glass. In particular, when fluorophosphate glass is used as the optical glass, low refractive index and low dispersion properties are required. However, if fluorine is replaced with oxygen, the νd value (Abbe number) decreases. However, by selecting dry oxygen gas as the oxidizing gas, it is possible to prevent this decrease in the νd value.

The flow rate of the oxidizing gas is preferably 1 to 4 liters / minute, although it depends on the input amount of the raw material and the production amount of the molten glass. Preferably, the temperature is 20 to 60 ° C, and the temperature at the time of supplying the molten glass is 700 to 800 ° C.

By increasing the depth of the molten glass at the raw material charging position (the height difference between the bottom of the container and the liquid glass surface at this position) and lowering the height at which the raw material is charged based on the molten glass liquid surface, In addition, it is possible to prolong the time for the input raw material to reach the bottom of the container, thereby preventing the erosion of the container wall surface even if a large amount of the erodible raw material is input. In order to obtain the above effect without the raw material inlet being too close to the liquid level of the molten glass, the depth of the molten glass at the position where the glass raw material is to be input is adjusted by setting the raw material input height based on the liquid level of the molten glass to one. It is preferably from 0.5 to 3 times, more preferably from 1.6 to 2.5 times. The height of the liquid level of the molten glass can be controlled by controlling the supply amount of the glass raw material to the molten glass, the discharge amount of the molten glass from the container, or both the supply amount and the discharge amount.

It is preferable that the glass material is supplied continuously. When producing a certain amount of glass,
In the method of intermittently charging the glass raw material, the raw material charging amount increases at one time, and a large amount of free phosphorus is generated at one time. In the continuous charging, the charging amount can be averaged with respect to time, and the generated free phosphorus can be oxidized steadily, which is advantageous from the viewpoint of preventing corrosion of the container and accelerating the melting of glass. Therefore, in order to maintain the liquid level of the molten glass within the above-mentioned predetermined range, it is preferable that the glass material is continuously charged and the molten glass is continuously discharged.

The molten glass is sent from a discharge port of the container to a refining tank, where the glass is refined and agitated, and becomes a high-quality glass that is uniform and does not contain fine particles or bubbles serving as a light scattering source. Since this glass is of high quality, it is suitably used as an optical glass, and can be used as an optical element such as a lens, a prism, an optical fiber, or a laser glass. Although the above method is an example of melting fluorophosphate glass, it can be applied to melting phosphate glass.

Next, the manufacturing method II will be described. Fluorine compounds, which are raw materials for fluorophosphate glass, include AlF
₃ (sublimation at 1260-1272 ° C.). AlF ₃ is partially decomposed when exposed to water vapor at 300 to 400 ° C. to produce hydrogen fluoride and aluminum oxide. The vapor pressure of AlF ₃ is 2.19 kPa (109 kPa).
8 ° C.) and 0.102 MPa (1294 ° C.). P ₂ O ₅ has a property of being easily vaporized. Therefore, if there is OH group or water vapor in the atmosphere where the molten glass touches,
The AlF ₃ vapor and the P ₂ O ₅ vapor react with the OH group or H ₂ O vapor to produce hardly soluble AlPO ₄ and condense above the molten glass liquid level in the melting vessel. Solidified AlPO
₄ falls and mixes irregularly into the glass, but when AlPO ₄ falls into the molten glass, it reacts while violently foaming, leaving bubbles in the glass. Also, Al
PO _{4 has} an extremely high melting point of 1500 ° C. or higher, and is hardly melted even when dropped into molten glass. Therefore, the dropped AlPO ₄ remains as a minute substance, causing scattering of fine particles, and significantly lowering the quality of glass. In order to melt these fine particles, the melting temperature of the glass is set to 1100 to 1150.
If the temperature is higher than about ° C., a raw material that easily sublimates may escape from the glass, so that it becomes difficult to obtain a glass having a desired composition.

In addition, large ν such as fluorophosphate glass
In order to obtain the d value, glass containing a large amount of fluorine instead of oxygen easily reacts with water, and it is necessary to avoid direct contact of the molten glass with water in the melting step and mixing of water vapor into the melting atmosphere. When the fluorophosphate glass in a molten state comes into contact with OH groups or water vapor, fluorine ions are replaced with oxygen ions, and fluorine escapes from the glass as HF gas. Therefore, when the stability as glass is impaired or when used as optical glass, νd
The value decreases. The generated HF gas is harmful,
It also has an adverse effect on the environment.

In order to solve these problems and obtain a high quality fluorophosphate glass, it is necessary to reduce the amount of water and OH groups in the molten glass and the molten atmosphere. Therefore, in the production method II, the raw material of the fluorophosphate glass is charged into the molten fluorophosphate glass accumulated in the heated container, and in the step of melting, the interior of the container is filled with a dry atmosphere gas. The glass material is charged while flowing the atmosphere gas to the molten glass liquid surface along the glass material charging path.

According to this method, the inside of the container is filled with the dry atmosphere gas, and the moisture in the atmosphere can be reduced. In addition, since the atmosphere gas is introduced into the molten glass liquid surface along the glass material introduction path, even if the glass material slightly adsorbs moisture, the input material is adsorbed by being mixed with the atmosphere gas. It is possible to reduce the amount of water that is made. After reaching the liquid surface of the molten glass, the atmospheric gas is exhausted to the outside of the container, the atmosphere in the container is kept in a dry state, and the reaction between the molten glass and OH groups or moisture can be suppressed.

Further, since the atmosphere gas flows along the glass material supply path, the gas generated from the molten glass reaches the glass material supply port, solidifies the glass material and closes the glass material supply port, The glass material can be prevented from soaring by the rising airflow and blocking the material supply port. As a dry atmosphere gas, a dry inert gas,
Dry oxygen gas or a dry mixture of inert gas and oxygen gas is preferred.

Further, in order to prevent the above-mentioned vaporized glass vapor comprising AlPO ₄ , AlF ₃ , and other glass components of a fluorine compound from solidifying and closing the exhaust port for exhausting the atmosphere gas from the container, the exhaust gas is exhausted. It is preferable to heat the mouth so that the temperature is preferably 600 ° C. or higher, more preferably 700 ° C. or higher.

When the glass raw material is continuously charged, by keeping the inside of the container at a positive pressure with respect to the outside of the container by the dry atmosphere gas, it is possible to prevent water vapor from entering the container together with the supply of the raw material. The pressure difference between the inside and outside of the container is 10-3
The pressure is preferably 0 Pa or more.

The molten glass is sent from a discharge port of the container to a refining tank, where the glass is refined and agitated, and becomes a high-quality glass that is uniform and does not contain fine particles or bubbles serving as a light scattering source. Since this glass is of high quality, it is suitably used as an optical glass, and can be used as an optical element such as a lens, a prism, an optical fiber, or a laser glass. Although the above method is an example of melting fluorophosphate glass, it can be applied to melting phosphate glass.

The above method can also be applied to the melting of boric acid-containing glass, for example, borosilicate glass. The boric acid-containing glass generates a large amount of water at the time of melting, and has a problem that glass vapor is easily solidified above the glass liquid surface of the melting vessel because boric acid has volatility. In the production of boric acid-containing glass, the problem of glass vapor coagulation is solved by flowing an atmospheric gas in the same manner, forming a predetermined flow path in the melting vessel, and making the glass raw material supply method as described above. In addition, glass raw materials can be supplied smoothly, and high-quality glass can be manufactured with high productivity.

Further, in this production method II, as in the above-mentioned production method I, an oxidizing gas is bubbled through the molten glass, and the inside of the container is filled with a dry atmosphere gas. It is also possible to melt the glass by pouring a glass material exhibiting a reducibility in the course of melting into a position where the oxidizing gas of the molten glass is bubbled while flowing along the molten glass liquid surface along.

At the position where the bubbling gas springs out (which is also the charging position of the glass raw material), an ascending airflow is generated in the atmosphere. However, the flow of the atmospheric gas along the raw material charging path causes the glass raw material to rise. Can be suppressed. The atmospheric gas serves to send out the bubbling gas that has flowed out from the liquid surface of the molten glass to the exhaust port, and there is no possibility that the oxidizing gas will remain in the container. This method is suitable for producing boric acid-containing glass such as phosphate glass, fluoride glass, fluorophosphate glass, and borosilicate glass, and can also be used for producing low-viscosity silicate glass.

The molten glass obtained by this method is sent from the outlet of the container to the fining tank, where it is clarified and agitated, and becomes a high-quality glass that is uniform and does not contain fine particles or bubbles serving as a light scattering source. Since this glass is of high quality, it is suitably used as an optical glass, and can be used as an optical element such as a lens, a prism, an optical fiber, or a laser glass.

The glass melting apparatus of the present invention is a glass melting apparatus in which a glass raw material is charged, heated and melted to obtain a molten glass, and has two modes, namely, (1) a container for melting the glass raw material, and a container. A glass material having an oxidizing gas supply port for supplying an oxidizing gas to the molten glass therein, and a raw material charging port for charging a glass raw material disposed above the oxidizing gas supply port as main components (glass A melting apparatus I) and (2) a vessel for heating and melting the glass raw material, a container for storing the obtained molten glass, a raw material charging port provided in connection with the container, and a dry atmosphere gas filling the container. An atmosphere gas supply port for supplying the gas, and an atmosphere gas exhaust port for exhausting the atmosphere gas are provided as main components. And opposite, so the flow path of the atmospheric gas reaches the exhaust port is formed, which the interior of the container is partitioned is (glass melter II).

First, the glass melting apparatus I will be described. In the glass melting apparatus I, a molten glass stored in the container and a heater for heating the glass material charged into the container are attached to the outside of the container for melting the glass raw material. One or more oxidizing gas supply ports for supplying an oxidizing gas such as a dry oxygen gas are provided at the bottom of the portion of the container where the molten glass is stored. Above the oxidizing gas supply port, a raw material input port for charging a glass raw material into a container is provided.
The number of raw material inlets is not limited to one. During operation of the present apparatus, molten glass is stored in a container, and an oxidizing gas is supplied into the molten glass from the above-described oxidizing gas supply port to perform bubbling.

Then, the glass raw material is supplied from the raw material charging port, and falls to a position bubbled with the oxidizing gas of the molten glass. The charged glass raw material decomposes and generates an intermediate product exhibiting a strong reducing action, but is quickly oxidized by bubbling with an oxidizing gas to prevent erosion of the inner wall of the container and promote melting of the glass. .

The inlet for the glass raw material is preferably provided above the center of the container so that the charged raw material does not easily touch the wall of the container.
It is preferable that the oxidizing gas supply port is also provided at the center of the container.

The apparatus I of the present invention is suitable for melting and producing fluorophosphate glass from a fluorine compound and a metaphosphate compound as raw materials, and the oxidizing gas is oxygen gas in a dry state or a dry gas containing oxygen gas. It is desirable to use. The temperature, supply amount, and other conditions of the oxidizing gas are the same as those described above with respect to the glass manufacturing method I. In addition, it is desirable that at least a portion of the container that is in contact with the molten glass is made of platinum or a platinum alloy.

The apparatus I desirably has a charging mechanism for controlling the amount of glass raw material charged to the container and a discharge amount control mechanism for controlling the discharge amount of molten glass from the container. By these control mechanisms, the depth at the position where the glass material of the molten glass is charged in the container is 1.5 to 3 times, preferably 1.times. The raw material charging height based on the liquid level of the molten glass.
The raw material supply amount and the molten glass discharge amount can be controlled so as to be 6 to 2.5 times, and the raw material can be melted before the charged glass raw material reaches the bottom of the container. Thereby, the erosion of the container can be prevented, and the substance constituting the container wall surface can be prevented from being mixed into the molten glass and contaminating the glass.

Further, it is desirable that the above-mentioned raw material feeding mechanism is of a type that continuously feeds raw materials. By continuously charging the raw materials, the amount of raw materials charged is made uniform over time,
It is possible to avoid that a large amount of reducing substances are generated by decomposition at one time. One example of a continuous material input mechanism is as follows. In order to keep the raw material in a dry state, a preliminary chamber filled with a dry atmosphere and a raw material supply passage connected from the preliminary chamber to the raw material inlet are provided, and a screw is provided in the preliminary chamber and the supply passage, and the screw is rotated at a constant rotation. By continuously rotating the raw materials, the raw material accumulated in the preliminary chamber is pushed out to the raw material input port through the supply passage, and the raw material is continuously input into the container from the input port. The device I can be suitably used for the production of phosphate glass.

Next, the glass melting apparatus II will be described. In the glass melting apparatus II, the manufacturing method described above is used.
As described in II, since the inside of the container is filled with the dry atmosphere gas, the moisture in the atmosphere can be reduced. Also, since the atmosphere gas flows along with the glass raw material along the charging path to the molten glass liquid surface, even if the glass raw material slightly adsorbs moisture, it is injected by being mixed with the atmosphere gas. The amount of water adsorbed by the raw material can be reduced. After reaching the liquid surface of the molten glass, the atmospheric gas is exhausted to the outside of the container, the atmosphere in the container is kept in a dry state, and the reaction between the molten glass and OH groups or moisture can be suppressed.

Further, since the atmosphere gas flows along the glass material supply path, the gas generated from the molten glass reaches the glass material supply port and solidifies the glass material to close the glass material supply port. The glass material can be prevented from soaring by the rising airflow and blocking the material supply port.

This apparatus II is suitable as an apparatus which uses a fluorine compound and a metaphosphate compound as raw materials and melts them to obtain a fluorophosphate glass. At this time, a dry inert gas and a dried inert gas are used as a dry atmosphere gas. It is preferable to supply oxygen gas or a dry mixed gas of an inert gas and oxygen gas.

Further, the above-mentioned hardly soluble AlPO_FourBut
Prevents solidification from the vessel to the exhaust port of atmospheric gas and blockage
Exhaust gas to heat the ambient gas exhaust gas
It is desirable to provide a motor. Heated by heater
AlPO _FourIs not solidified and is in gaseous state
Is exhausted out of the container together with the atmospheric gas. Atmosphere gas
The part that exhausts air is heated to 600 ° C or higher.
Is preferred.

In this apparatus II, like the above-mentioned apparatus I, the raw material charging mechanism is preferably of a continuous type. However, in order to prevent the intrusion of moisture from the outside of the container together with the supply of the raw material, the inside of the container is kept It is preferable to provide a mechanism for adjusting the pressure of the dry atmosphere gas so that the pressure becomes positive with respect to the outside.

Further, the inside of the container is divided by a partition wall extending to the vicinity of the molten glass liquid level so as to surround the raw material charging path from the raw material charging port, and the atmosphere gas exhaust port is separated from the raw material charging port by the partition wall. Is desirably provided. By providing the partition walls in this manner, the atmosphere in the container can be constantly replaced, and the atmospheric gas can be surely flowed along the predetermined flow path. Also, the input raw material is surely input into the molten glass,
It is possible to prevent the raw material from being directly discharged from the exhaust port.

The container preferably has a cylindrical shape, and preferably has a heating portion attached to a side surface thereof for heating the molten glass stored in the container. Further, the glass is maintained so that the height of the liquid level of the molten glass with respect to the bottom of the container is kept within a range of preferably 2.5 to 10 times, more preferably 3 to 6 times the inner diameter of the container. It is desirable to have a control mechanism for controlling at least one of the input amount of the raw material and the discharge amount of the molten glass, and it is preferable to have a control mechanism for controlling both the input amount of the glass raw material and the discharge amount of the molten glass. More desirable. The features of this apparatus are that the ratio of the area of the molten glass in contact with the atmosphere gas to the volume of the molten glass in the container can be reduced, and the area of the molten glass in contact with the container relative to the volume of the molten glass can be increased. With these features, the area where the molten glass is in contact with the atmosphere can be reduced, the reaction with moisture and the volatilization amount of the glass component can be reduced, and the molten glass can be efficiently heated.

If the height of the liquid surface of the molten glass with respect to the bottom of the container is less than 2.5 times the diameter of the bottom of the container, the above-mentioned effects are not sufficiently obtained, and if the height exceeds 10 times, the atmosphere gas becomes less dense. It becomes difficult to perform stable supply and exhaust.

The molten glass is sent from the outlet of the container to the fining tank, where it is clarified and agitated, and becomes a high-quality glass which is uniform and does not contain fine particles or bubbles serving as a light scattering source. Since this glass is of high quality, it is suitably used as an optical glass, and can be used as an optical element such as a lens, a prism, an optical fiber, or a laser glass. The above device II
Can be suitably used not only for the production of fluorophosphate glass but also for the production of fluoride glass and the production of boric acid-containing glass such as borosilicate glass.

Further, in the melting apparatus II, an oxidizing gas supply port for supplying a dried oxidizing gas into the molten glass can be provided, and a material input port can be disposed above the oxidizing gas supply port. . As described above, by providing the configuration of the melting device I, it also has the features of the melting device I, and as described in the above-described manufacturing method II, phosphate glass, fluoride glass, fluorophosphate glass, and borosilicate glass. It is suitably used for producing boric acid-containing glass such as acid glass, and can also be used for producing low-viscosity silicate glass. In addition, the glass melting apparatuses I and II of the present invention can be connected to the melting apparatus and provided with a fining tank or a stirring tank as needed.

[0058]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Embodiment 1 FIG. 1 is a schematic vertical sectional view of the glass melting apparatus of the present invention used in this embodiment. The container 10 for melting glass is a platinum cylindrical container having an inner diameter of 0.28 m and a height of 0.95 m. At the center of the upper portion of the container 10, a raw material input port 5 for inputting a raw material into the container is provided, and a raw material input mechanism 1 and an atmosphere gas supply port 6 are provided so as to communicate with the raw material input port 5.

The raw material charging mechanism 1 includes a preliminary chamber 13 in which raw materials prepared in advance are stored, a raw material supply passage 14 for supplying raw materials to the charging port 5, and a screw inserted into the raw material supply passage 14 and the preliminary chamber 13. 2, a motor 3 for rotating the screw 2, and a control mechanism (not shown) for controlling the supply amount of the raw material. The glass raw material stored in the preliminary chamber 13 is pushed out to the supply passage 14 by the screw 2 by driving the motor 3, and the raw material discharge port 4
Through the material inlet 5 and into the container 10. Since the supply amount of the raw material is determined by the rotation speed of the motor 3, the control mechanism can increase or decrease the rotation speed of the motor 3 to increase or decrease the supply amount of the raw material. The preliminary chamber 13 is also provided with an atmosphere gas supply port 6 'for supplying a dry atmosphere gas. A dry atmosphere gas is supplied to the container 10 from the atmosphere gas supply port 6 'together with the atmosphere gas supply port 6 described above.

A cylindrical partition wall 9 is provided at the center and upper portion of the container 10 so as to surround the charging path of the glass raw material charged from the charging port 5. In addition, an upper portion and a peripheral portion of the container 10 are provided with a raw material input port 5 and an exhaust port 7 for exhausting the atmospheric gas supplied from the atmosphere gas supply ports 6 and 6 ′ and passing through the inside of the container 10. I have. In the exhaust port 7,
A heating device 8 is provided so that glass vapor or the like generated at the time of melting the glass cools and solidifies and does not block the exhaust port. Note that the partition wall 9 must have a length that does not hinder the flow of the atmospheric gas when the molten glass is stored in the container 10.

A heater (not shown) is provided on the outer surface of the container 10 for heating the glass to melt the glass. The heating of the molten glass is performed through the side surface of the container 10. A discharge port 12 for discharging the glass melted in the container is provided at the bottom peripheral edge of the container 10, and the molten glass discharged from the container 12 is sent to a refining tank and refined. A bubbling pipe 11 for supplying an oxidizing gas is provided at the center of the bottom of the container 10, and a dry oxygen gas is supplied to the molten glass from the bubbling pipe 11 so that the bubbling by the oxygen gas is performed. I have.

The container 10 and the inside of the raw material charging mechanism 1 connected thereto contain steam from the outside except for the atmosphere gas supplied from the atmosphere gas supply ports 6 and 6 ′ and the oxidizing gas supplied from the bubbling pipe 11. It is maintained at a positive pressure to prevent air from entering. Using such a glass melting apparatus, melting and production of fluorophosphate glass were performed. The container 10 has a heater provided on the outer surface of the container.
The molten glass heated to 800 to 1000C, preferably 950 to 1000C is stored. The dried oxygen gas is supplied into the molten glass from the bubbling pipe 11, and the central portion of the molten glass is bubbled with the oxygen gas.

In the preparatory chamber 13 of the raw material charging mechanism 1, a dried and mixed glass raw material is put, and the atmosphere gas supply port 6 is provided.
A dry gas (dry oxygen gas, dry inert gas, or a mixed gas of dry oxygen gas and dry inert gas) is continuously supplied from 6 '. The raw material of the fluorophosphate glass is Al
F ₃ , MgF ₂ , CaF ₂ , SrF ₂ , YF ₃ (or more, fluorine compound), Al (PO ₃ ) ₃ , Mg (PO ₃ ) ₂ , Ca (P
A mixture of O ₃ ) ₂ , Sr (PO ₃ ) ₂ , and Ba (PO ₃ ) ₂ (above, a metaphosphate compound) was used.

The atmosphere gas passes through the raw material inlet 5 and is guided to the partition wall 9 toward the molten glass liquid surface, passes between the partition wall 9 and the molten glass liquid surface, and flows between the inner wall side surface of the container 10 and the partition wall 9. Through the exhaust port 7. With the container 10 filled with the dry atmosphere gas in this way, the motor 3 of the raw material charging mechanism 1 is rotated at a constant speed to
The glass material of No. 3 is continuously extruded into the inlet 5 at a constant supply amount. The glass raw material passes through the portion surrounded by the partition wall 9 from the charging port 5 and falls to the liquid level at the center of the molten glass in which oxygen gas is bubbled. At this time, since the atmospheric gas is flowing along the raw material charging path, the raw material is not sowed by the convection in the container 10 or the rising air flow due to the bubbling gas. Further, it is possible to prevent the glass vapor generated from the molten glass from adsorbing on the glass raw material and adhering to the raw material input port, thereby preventing the raw material input from being hindered.

Among the glass raw materials charged, the metaphosphate compound is decomposed in the molten glass to produce free phosphorus having a very strong reducing property, but is rapidly oxidized by oxygen gas bubbled into the molten glass, and Is done. Therefore, the melting of the glass can be performed efficiently, and the metaphosphate compound and free phosphorus can be prevented from reaching the inner wall of the platinum container 10, and the erosion of the container 10 can be prevented. Therefore, the platinum fine particles in the container 10 do not enter the molten glass.

The atmosphere gas flowing from the liquid surface of the molten glass toward the space between the inner wall side surface of the container 10 and the partition wall 9 contains glass vapor generated from the molten glass. It becomes aluminum phosphate and goes to the exhaust port 7 together with the atmospheric gas. Since the exhaust port 7 is heated, the aluminum phosphate does not solidify in the exhaust port 7, the flow of the atmosphere gas is not hindered, and the solidified aluminum phosphate does not drop or mix into the molten glass. Also, problems such as foaming can be avoided.

The depth of the molten glass (the height of the molten glass liquid level measured from the center of the bottom of the vessel) is controlled by controlling the amount of the raw material supplied by the raw material supply amount control mechanism and the amount of the molten glass discharged by the molten glass discharge amount control mechanism. ) Is the height of the raw material inlet 5 with respect to the molten glass liquid level, preferably 1.6.
It is kept to be 2.5 times. Therefore, the raw material supplied from the raw material charging port 5 is melted before reaching the bottom of the container 10, and there is no possibility that the platinum on the inner surface of the container is eroded.

Further, by controlling the height of the liquid level of the molten glass, the depth of the molten glass is maintained preferably 3 to 6 times the inner diameter of the container 10 without obstructing the flow path of the atmosphere gas. In addition, the area of the molten glass that comes into contact with the ambient gas per volume can be reduced.

The molten glass obtained in the container 10 is sent from an outlet 12 to a fining tank (not shown) for fining.
High quality optical glass containing no impurities such as residual bubbles and platinum fine particles is obtained. As described above, while continuously supplying the atmosphere gas and the bubbling gas, the glass material is continuously charged, and the high-quality optical glass containing no impurities such as platinum fine particles and bubbles is continuously manufactured with high productivity. I was able to.

Example 2 Using the same apparatus as used in Example 1, borosilicate glass was melted in the same manner as in Example 1. The borosilicate raw material, the silicate raw material, and other raw materials are mixed and supplied to the raw material charging mechanism 1, and the borosilicate glass is obtained by continuously charging the molten glass from the raw material charging port 5 while flowing a dry atmosphere gas. Was. Also in this example, high-quality optical glass containing no bubbles or impurities could be continuously obtained with high productivity.

[0072]

By using the method for producing glass and the glass melting apparatus of the present invention, high-quality glass, particularly phosphate glass, fluoride glass, fluorophosphate glass, and boric acid-containing material can be used using highly reactive raw materials. Glass and the like can be manufactured with high productivity.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional view of a glass melting apparatus of the present invention used in Examples.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 raw material feeding mechanism 2 screw 3 motor 4 raw material discharge port 5 raw material input port 6 atmosphere gas supply port 6 ′ atmosphere gas supply port 7 exhaust port 8 heating device 9 partition wall 10 container 11 bubbling pipe 12 molten glass discharge port 13 preliminary chamber 14 raw material Supply passage

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuko Kato 2-7-5 Nakaochiai, Shinjuku-ku, Tokyo Inside the Hoya Corporation (72) Inventor Rieko Kudo 2-7-5, Nakaochiai, Shinjuku-ku, Tokyo Within Hoya Corporation

Claims (15)

[Claims] 1. A method for producing glass, comprising a step of charging a molten glass in a heated vessel with a raw material of the glass and melting the glass, wherein the oxidizing gas is bubbled through the molten glass and the bubbling is performed. A method for producing glass, wherein a glass raw material that exhibits reducibility in the course of being melted is introduced into a position. 2. A method for producing glass, comprising a step of introducing a raw material of glass into a molten glass in a heated container and melting the molten glass, wherein oxygen gas is bubbled through the molten glass, and the bubbling position is adjusted. A method for producing phosphate glass, wherein a raw material for phosphate glass is added to the mixture. 3. The method for producing glass according to claim 1, wherein a metaphosphate compound is used as a glass raw material, and the phosphate glass is melted. 4. The method for producing glass according to claim 3, wherein a fluorine compound is further used as a glass raw material to melt the fluorophosphate glass. 5. The supply amount and / or the supply amount of the glass raw material such that the depth of the molten glass at the position where the glass raw material is charged is 1.5 to 3 times the raw material charging height based on the liquid level of the molten glass. Or controlling the discharge amount of the molten glass.
5. The method for producing glass according to any one of items 4 to 4. 6. A method for producing glass, comprising a step of charging a raw glass material into a molten glass in a heated vessel and melting the glass, wherein the vessel is filled with a dry atmosphere gas and the atmosphere is dried. A method for producing glass, wherein a glass raw material is charged while flowing a gas to a molten glass liquid surface along a glass raw material charging path. 7. Use of a fluorine compound as a glass raw material,
The method for producing glass according to claim 6, wherein the fluoride glass is melted. 8. The method for producing glass according to claim 7, wherein a metaphosphate compound is further used as a glass raw material, and the fluorophosphate glass is melted. 9. Use of a boric acid compound as a glass raw material,
The method for producing glass according to claim 6, wherein the boric acid-containing glass is melted. 10. An oxidizing gas is bubbled through the molten glass, and a glass material exhibiting a reducibility in the course of melting is introduced into the bubbling position.
The method for producing glass according to any one of the above items. 11. A glass melting apparatus for charging a glass material, heating and melting to obtain a molten glass, comprising: a container for melting the glass material; and an oxidizing gas for supplying an oxidizing gas to the molten glass in the container. A supply port, a raw material input port for charging a glass raw material disposed above the oxidizing gas supply port,
A glass melting apparatus provided as a main component. 12. Supply of glass raw material so that the depth of the molten glass in the container at the position where the glass raw material is charged is 1.5 to 3 times the raw material charging height based on the liquid level of the molten glass. The glass melting apparatus according to claim 11, further comprising a control mechanism for controlling an amount and / or a discharge amount of the molten glass. 13. A glass melting apparatus for charging a glass raw material, heating and melting to obtain a molten glass, wherein the container is configured to heat and melt the glass raw material and store the obtained molten glass, and connected to the container. An atmosphere gas supply port for supplying a dry atmosphere gas that fills the container, an atmosphere gas exhaust port for exhausting the atmosphere gas, and an atmosphere gas supply port. Wherein the inside of the container is divided so that a flow path of an atmospheric gas is formed from the liquid to a molten glass liquid surface along a glass raw material charging path and reaches an exhaust port. 14. A heating unit for heating the molten glass from a side surface of the cylindrical container, and a height of the liquid level of the molten glass with respect to a bottom surface of the container is 25 to 10 of an inner diameter of the container.
14. The glass melting apparatus according to claim 13, further comprising a control mechanism for controlling the input amount of the glass raw material and / or the discharge amount of the molten glass so as to be maintained within the doubled range. 15. The method according to claim 13, further comprising an oxidizing gas supply port for supplying a dry oxidizing gas into the molten glass, and a raw material input port being disposed above the oxidizing gas supply port. Glass melting equipment.