JP2015083531A - Method of manufacturing glass substrate, molten glass processing device, and device of manufacturing glass substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress cohesion of volatile matter of vaporized platinum, platinum alloy, etc., used in a process of manufacturing a glass substrate by a molten glass processing device for molten glass made of the platinum or platinum alloy.SOLUTION: Molten glass is guided to a molding device by using a molten glass processing device which has a liquid-phase space which has molten glass, a vapor-phase space located above the liquid level of the molten glass, and an inner wall which forms the liquid-phase space and vapor-phase space such that at least a part of the vapor-phase space is formed of a material including platinum group metal, and forms an air current in the vapor-phase space so that the air current does not pass through a region lower than the temperature at which the platinum group metal included in the vapor-phase space reaches saturation vapor pressure.

Description

  TECHNICAL FIELD The present invention relates to a glass substrate manufacturing apparatus, a glass substrate manufacturing method, and a molten glass processing apparatus used in a glass substrate manufacturing apparatus for manufacturing a glass substrate by molding a molten glass produced by melting a glass raw material. .

  Generally, a glass substrate is produced through a process of forming molten glass from a glass raw material and then forming the molten glass into a glass substrate.

  By the way, in order to mass-produce high-quality glass substrates from high-temperature molten glass, consideration should be given so that foreign substances that cause defects in the glass substrate do not enter the molten glass from any apparatus that manufactures the glass substrate. Is desired. For this reason, the inner wall of the member in contact with the molten glass in the manufacturing process of the glass substrate needs to be made of an appropriate material according to the temperature of the molten glass in contact with the member, the required quality of the glass substrate, and the like. For example, it is known that the material of the tube constituting the clarification tube is usually a platinum group metal or an alloy of a plurality of metals contained in the platinum group metal (hereinafter simply referred to as platinum or a platinum alloy). (Patent Document 1). Platinum or a platinum alloy is expensive but has a high melting point and excellent corrosion resistance against molten glass, and thus is suitably used for a clarification tube or a stirring tank.

JP 2006-522001 Gazette

However, platinum or platinum alloys have a problem of volatilization at high temperatures. Then, a part of the crystal (platinum foreign matter or platinum alloy foreign matter) obtained by agglomerating the volatile matter such as platinum or platinum alloy on the wall surface surrounding the gas phase space is mixed in the molten glass as fine particles, and the quality of the glass substrate There was a risk of lowering.
The problem of mixing fine particles derived from aggregates of volatiles such as platinum or platinum alloys into the molten glass is a flat panel represented by liquid crystal displays whose quality requirements are becoming increasingly severe with the recent high definition. It becomes larger in a glass substrate for a display (FPD).

  Therefore, in view of the above points, the present invention suppresses aggregation of volatiles such as volatilized platinum or a platinum alloy in an apparatus in which at least a part used in the glass substrate manufacturing process is made of a material containing a platinum group metal. An object of the present invention is to provide a glass substrate manufacturing apparatus, a glass substrate manufacturing method, and a molten glass processing apparatus used for the glass substrate manufacturing apparatus.

  The present invention includes the following forms.

(Form 1)
A melting step of melting glass raw material to produce molten glass;
It has a liquid phase having the molten glass and a gas phase space formed from the liquid surface and inner wall of the molten glass, and at least a part of the inner wall surrounding the gas phase space is made of a material containing a platinum group metal. A processing step of processing the molten glass in a molten glass processing apparatus,
In the gas phase space of the molten glass processing apparatus, an air flow is formed,
The method of manufacturing a glass substrate, wherein the air flow is formed so as to pass through a region having a temperature equal to or higher than a temperature at which a platinum group metal contained in the gas phase space has a saturated vapor pressure.

(Form 2)
A melting step of melting glass raw material to produce molten glass;
It has a liquid phase having the molten glass and a gas phase space formed from the liquid surface and inner wall of the molten glass, and at least a part of the inner wall surrounding the gas phase space is made of a material containing a platinum group metal. A processing step of processing the molten glass in a molten glass processing apparatus,
In the gas phase space of the molten glass processing apparatus, an air flow is formed,
The said air flow is formed so that it may not pass through the area | region which falls below the temperature from which the platinum group metal contained in the said gaseous-phase space becomes saturated vapor pressure, The manufacturing method of the glass substrate characterized by the above-mentioned.

(Form 3)
The said air flow is a manufacturing method of the glass substrate of the form 1 or 2 which is an air flow which flows toward the high part from the low temperature part of the inner wall of the said molten glass processing apparatus which contact | connects the said gaseous-phase space.

(Form 4)
The said air flow is a manufacturing method of the glass substrate as described in any one of the forms 1-3 formed by adjusting the pressure in the said gaseous-phase space.

(Form 5)
The said airflow is a manufacturing method of the glass substrate as described in any one of the forms 1-4 formed by introduce | transducing gas in the said gaseous-phase space.

(Form 6)
The manufacturing method of the glass substrate of the form 5 which adjusts the pressure distribution in the said gaseous-phase space by changing the gas amount which the said gas introduce | transduces.

(Form 7)
The manufacturing method of the glass substrate of the form 5 or 6 which adjusts the direction of the said airflow by the position on the said gaseous-phase space in which the gas inlet for introducing gas into the said gaseous-phase space is provided. The direction of airflow is adjusted by generating forced convection.

(Form 8)
The manufacturing method of the glass substrate as described in any one of form 5-7 which adjusts the direction of an airflow with the direction of the introduction of the gas when gas is introduced into the gas phase space. The direction of airflow is adjusted by generating forced convection.

(Form 9)
The gas is introduced into the gas phase space from a portion of the inner wall of the molten glass processing apparatus in contact with the gas phase space, the temperature of which is lower than the surrounding temperature. The manufacturing method of the glass substrate of description.

(Form 10)
The said gas is a manufacturing method of the glass substrate of the forms 5-9 which is an inert gas with respect to the said molten glass and the said platinum group metal.

(Form 11)
The glass substrate according to any one of aspects 1 to 10, wherein the air flow is formed by adjusting a pressure distribution in the gas phase space by a suction device provided so as to be connected to the gas phase space. Manufacturing method.

(Form 12)
The manufacturing method of the glass substrate of the form 11 which adjusts the magnitude | size of the pressure distribution in the said gaseous-phase space by changing the suction pressure of the said suction device. As the size of the pressure distribution changes, the size of the air flow toward the suction device changes.

(Form 13)
The manufacturing method of the glass substrate of the form 11 or 12 which adjusts the pressure distribution in the said gaseous-phase space by the change of the position of the suction port of the said suction device in the said gaseous-phase space.

(Form 14)
In the molten glass processing apparatus, the molten glass is clarified, and a gas discharge amount of the gas released from the molten glass in the gas phase space or a discharge region for releasing the gas in the gas phase space is adjusted. The manufacturing method of the glass substrate as described in any one of the forms 1-4 which adjusts the said air flow. The air flow is adjusted by adjusting the pressure distribution or pressure in the gas phase space by adjusting at least one of the gas discharge amount and the discharge region.

(Form 15)
The glass substrate manufacturing method according to mode 14, wherein the adjustment of at least one of the gas release amount and the discharge region is performed by adjusting the temperature history of the molten glass in the molten glass processing apparatus.

(Form 16)
Adjustment of the temperature history of the said molten glass is a manufacturing method of the glass substrate of the form 15 performed by adjustment of the calorie | heat amount supplied to the said molten glass in order to heat the said molten glass.

(Form 17)
The molten glass flows through a tube that is energized and heated in the molten glass processing apparatus,
Adjustment of the temperature history of the molten glass is performed by adjusting the current flowing through the tube to energize and heat the tube, or by adjusting the current according to the location of the tube. Production method.

(Form 18)
The gas discharge amount or the discharge region is adjusted by adjusting the difference between the molten glass temperature in the melting step and the molten glass temperature in the treatment step, according to any one of embodiments 14 to 17. A method for producing a glass substrate.

(Form 19)
A glass substrate is a manufacturing method of the glass substrate as described in any one of the forms 1-18 containing 0.01-0.3 mol% of tin oxides. The gas release amount is adjusted by the content of tin oxide.

(Form 20)
The maximum temperature of the temperature of the said inner wall is a manufacturing method of the glass substrate as described in any one of the forms 1-19 which are 1400 degreeC or more and 1750 degrees C or less.

(Form 21)
The minimum temperature of the temperature of the said inner wall is a manufacturing method of the glass substrate as described in any one of form 1-20 which is 1200 to 1630 degreeC.

(Form 22)
The temperature difference between the highest temperature part and the lowest temperature part of the said inner wall is a manufacturing method of the glass substrate as described in any one of the forms 1-21 which is 50 to 300 degreeC.

(Form 23)
The molten glass processing device is a clarification tank that clarifies the molten glass and discharges a gas generated by the clarification to the atmosphere through a vent pipe connecting the gas phase space and the atmosphere. The manufacturing method of the glass substrate as described in any one of the forms 1-22 which is the flow which goes to a trachea.

(Form 24)
The molten glass processing device is a clarification tank that clarifies the molten glass and discharges the gas generated by the clarification to the atmosphere through a vent pipe connecting the gas phase space and the atmosphere,
The clarification tank includes an elongate clarification tube,
The said clarification pipe | tube is a manufacturing method of the glass substrate as described in any one of the forms 1-23 with which temperature distribution is formed along the flow direction of the said molten glass which flows through the inside of the said clarification pipe | tube.

(Form 25)
The said glass substrate is a manufacturing method of the glass substrate as described in any one of the forms 1-24 which is a glass substrate for displays.

(Form 26)
In the said gaseous-phase space, the manufacturing method of the glass substrate as described in any one of the forms 1-25 which adjusts the pressure in the said gaseous-phase space so that a pressure may become low, so that temperature becomes high.

(Form 27)
The molten glass processing device is a clarification tank that clarifies the molten glass and discharges the gas generated by the clarification to the atmosphere through a vent pipe connecting the gas phase space and the atmosphere,
The clarification tank includes an elongate clarification tube, and the clarification tube is provided with a flange that surrounds an outer periphery of a position of a portion of the clarification tube in the longitudinal direction, and the gas is supplied to the flange of the clarification tube. The manufacturing method of the glass substrate as described in any one of the forms 5-10 introduce | transduced from the part provided.

(Form 28)
At least two flanges are provided so as to surround the outer periphery of at least two positions in the longitudinal direction of the clarification pipe, and at least one of the vent pipes is provided between the at least two positions in the longitudinal direction. The glass according to aspect 27, wherein the gas is introduced into the gas phase space from the at least two locations, creates an air flow that flows in directions opposite to each other, and is discharged from the at least one vent pipe. A method for manufacturing a substrate.
It is preferable.

(Form 29)
The molten glass processing apparatus according to any one of aspects 1 to 28, wherein the molten glass processing apparatus generates heat when the molten glass processing apparatus is energized to adjust the temperature of the molten glass. A method for producing a glass substrate.

(Form 30)
A molten glass processing apparatus for processing molten glass,
An inner wall made of a material containing at least a platinum group metal;
A liquid phase space having a molten glass;
A gas phase space formed from the liquid surface of the molten glass and the inner wall,
An airflow is formed in the gas phase space,
The molten glass processing apparatus, wherein the air flow is formed so as to pass through a region having a temperature equal to or higher than a temperature at which a platinum group metal contained in the gas phase space has a saturated vapor pressure.

(Form 31)
A molten glass processing apparatus for processing molten glass,
An inner wall made of a material containing at least a platinum group metal;
A liquid phase space having a molten glass;
A gas phase space formed from the liquid surface of the molten glass and the inner wall,
An airflow is formed in the gas phase space,
The molten glass processing apparatus, wherein the airflow is formed so as not to pass through a region below a temperature at which a platinum group metal contained in the gas phase space has a saturated vapor pressure.

(Form 32)
The molten glass processing apparatus according to claim 30 or 31, wherein the air flow is an air flow directed from a portion having a low temperature to a portion having a high temperature on the inner wall in the inner wall in contact with the gas phase space.

(Form 33)
The molten glass processing apparatus according to any one of Embodiments 30 to 32, further including a pressure adjusting device that adjusts a pressure in the gas phase space to form the air flow.

(Form 34)
The molten glass processing apparatus according to any one of Embodiments 30 to 33, wherein the pressure in the gas phase space is adjusted so that the pressure becomes lower as the temperature becomes higher in the gas phase space.

(Form 35)
A melting device that melts glass raw materials to produce molten glass;
An apparatus for manufacturing a glass substrate, comprising: the molten glass processing apparatus according to any one of forms 30 to 34.

(Form 36)
A melting device that melts glass raw materials to produce molten glass;
An apparatus for manufacturing a glass substrate, comprising: the molten glass processing apparatus according to any one of forms 30 to 34.

  According to the glass substrate manufacturing method, manufacturing apparatus, and molten glass processing apparatus of the above-described aspect, aggregation of volatilized platinum or platinum alloy or the like can be suppressed.

It is a figure which shows an example of the process of the manufacturing method of the glass substrate of this embodiment. It is a figure which shows typically an example of the apparatus which performs the melting process-cutting process in this embodiment. (A) is a perspective view explaining the clarification tank of this embodiment, (b) is a figure explaining an example of the flow of the gas inside the clarification pipe of this embodiment, (c), It is a figure explaining the other example of the flow of the gas inside a clarification pipe | tube. It is a figure which shows an example of the temperature distribution of the longitudinal direction of the inner wall of the clarification pipe | tube of this embodiment.

Hereinafter, the manufacturing apparatus of the glass substrate of this embodiment, the manufacturing method of a glass substrate, and a molten glass processing apparatus are demonstrated. FIG. 1 is a diagram showing an example of steps of a method for producing a glass substrate according to the present invention.
The platinum or platinum alloy described below is a platinum group metal, and includes platinum, ruthenium, rhodium, palladium, osmium, iridium, and alloys of these metals.

  The glass substrate manufacturing method includes a melting step (ST1), a clarification step (ST2), a homogenization step (ST3), a molding step (ST4), a slow cooling step (ST5), and a cutting step (ST6). , Mainly. In addition, a plurality of glass substrates that have a grinding process, a polishing process, a cleaning process, an inspection process, a packing process, and the like and are stacked in the packing process are transported to a supplier.

  The melting step (ST1) is performed in a melting tank. In the melting step, molten glass is made by introducing a glass raw material to the liquid surface of the molten glass stored in the melting tank. In addition, it is preferable that a clarifier is added to the glass raw material. As for the fining agent, tin oxide is preferably used from the viewpoint of reducing the environmental load.

The clarification step (ST2) is performed inside a clarification tube made of platinum or a platinum alloy or the like in a clarification tank. In the clarification step, the temperature of the molten glass in the tube of the clarification tank is raised. In this process, the fining agent releases oxygen by a reduction reaction, and becomes a substance that later acts as a reducing agent. Bubbles containing O ₂ , CO _2, or SO ₂ contained in the molten glass coalesce with O ₂ generated by the reductive reaction of the clarifying agent, increase in volume, and float on the liquid surface of the molten glass. Then disappear. The gas contained in the bubbles is released to the outside air through a gas phase space provided in the clarification tank.

Thereafter, in the clarification step, the temperature of the molten glass is lowered. In this process, the reducing agent obtained by the reductive reaction of the clarifying agent undergoes an oxidation reaction. Thus, the gas components such as O ₂ in the foam remaining in the molten glass that melts in the molten glass, bubbles disappear.

  In the homogenization step (ST3), the glass components are homogenized by stirring the molten glass in the stirring tank supplied through the pipe extending from the clarification tank using a stirrer.

In the molding apparatus, a molding step (ST4) and a slow cooling step (ST5) are performed.
In the forming step (ST4), the molten glass is formed into a sheet glass to make a flow of the sheet glass. For forming, an overflow down draw method or a float method can be used. In this embodiment described later, an example in which the overflow downdraw method is used will be described.
In the slow cooling step (ST5), the sheet glass that has been formed and flowed is cooled to a desired thickness so that internal distortion does not occur and warpage does not occur.

  In a cutting process (ST6), a plate-shaped glass plate is obtained by cutting the sheet glass supplied from the forming device into a predetermined length in the cutting device. The cut glass plate is further cut into a predetermined size to produce a glass substrate of a target size.

In the manufacturing method of the glass substrate of this embodiment, the following method is implemented in the apparatus used for a clarification process-a homogenization process.
That is, after a melting step of melting a glass raw material to produce a molten glass, a molten glass processing apparatus for processing the molten glass is passed before the molten glass is formed into a sheet glass. This processing apparatus includes a metal tube or tank containing platinum or a platinum alloy. At that time, the molten glass processing apparatus has a liquid phase having a molten glass and a gas phase space located above the liquid level with respect to the liquid level of the molten glass, and at least a part of the gas phase space is a platinum group. It is an apparatus composed of a material containing metal. In the gas phase space of this molten glass processing apparatus, the temperature of the platinum group metal contained in the gas phase space does not pass through a region below the temperature at which the saturated vapor pressure is reached, or a temperature equal to or higher than the temperature at which the saturated vapor pressure is reached The airflow is formed so that the airflow passes through the region. Preferably, an air flow is formed from a portion having a low temperature to a portion having a high temperature on the inner wall of the molten glass processing apparatus in contact with the gas phase space. At this time, it is preferable to introduce gas into the gas phase space to form an air flow. Moreover, by introducing an inert gas as a gas into the gas phase space, volatilization of platinum or a platinum alloy or the like can be reduced in the gas phase space. Aggregation of volatiles can also be suppressed. This point will be described later.

  In addition, the aggregate of platinum or a platinum alloy is a linear object elongated in one direction. For this reason, the maximum length and the minimum length of platinum or a platinum alloy aggregate (foreign matter) are the length of the long side of the circumscribed rectangle that circumscribes the image of the aggregate when platinum or a platinum alloy aggregate is photographed. And the length of the short side. In the present embodiment, the aggregate of platinum or a platinum alloy refers to a foreign material of a platinum group metal having an aspect ratio exceeding 100, which is a ratio of the maximum length to the minimum length in the shape of the aggregate. For example, the maximum length of the foreign substance (aggregate) of the platinum group metal is 50 μm to 300 μm, and the minimum length is 0.5 μm to 2 μm.

  Such a processing apparatus for molten glass is applied to an apparatus used in a process between a refining process and a homogenization process. For example, it applies to the clarification tank which performs a clarification process, and the stirring tank which performs a homogenization process. In the following, description will be made in a form applied to a clarification tank as a representative.

  FIG. 2 is a diagram schematically illustrating an example of an apparatus that performs the melting step (ST1) to the cutting step (ST6) in the present embodiment. As shown in FIG. 2, the apparatus mainly includes a molten glass production apparatus 100, a molding apparatus 200, and a cutting apparatus 300. The molten glass production | generation apparatus 100 has the melting tank 101, the clarification tank 102, the stirring tank 103, and the glass supply pipes 104,105,106.

The melting tank (melting apparatus) 101 of the example shown in FIG. 2 melts a glass raw material, and makes molten glass. The clarification tank 102 includes a clarification tube 102a (see FIG. 3) made of platinum or a platinum alloy. In the clarification tube 102a, an electric current is passed between a pair of electrode plates provided in the clarification tank 102 while the molten glass MG is passed in a state where a gas phase space is formed so that the molten glass MG has a liquid surface. Then, the clarification tube 102a is energized and heated to perform at least defoaming treatment for releasing the molten glass MG into the gas phase space. The agitation tank 103 agitates the molten glass MG with a stirrer 103a and homogenizes it.
The forming apparatus 200 includes a formed body 210 and forms the molten glass MG processed in the clarification tank 200 and the stirring tank 103 by the overflow down draw method using the formed body 210 to form a sheet glass SG. Furthermore, in the forming apparatus 200, the sheet glass SG is gradually cooled so that plate thickness deviation, distortion, and warpage do not occur in the sheet glass SG.
The cutting device 300 cuts the slowly cooled sheet glass SG to form a glass substrate.

(Clarification process and clarification tank)
Fig.3 (a) is a figure which mainly shows the apparatus structure which performs a clarification process.
The clarification process includes a defoaming process and an absorption process. In the following description, an example using tin oxide as a fining agent will be described. Tin oxide has a lower refining function than arsenous acid that has been generally used in the past, but can be suitably used as a refining agent in terms of low environmental burden. However, since tin oxide has a lower refining function than arsenous acid, when tin oxide is used, the temperature of the molten glass MG during the refining process of the molten glass MG must be higher than before. In this case, for example, the maximum temperature of the molten glass in the clarification step is, for example, 1630 ° C. to 1720 ° C., and preferably 1670 ° C. to 1710 ° C.

  The molten glass MG melted in the melting tank 101 is introduced into the clarification tank 102 through a glass supply pipe 104 (see FIG. 2).

  As shown in FIG. 3A, the clarification tank 102 includes a long clarification tube 102a made of platinum or a platinum alloy or the like, and includes a ventilation tube 102b provided on the top of the clarification tube 102a, an electrode plate 102c, 102d, flanges 102e and 102f, and gas introduction pipes 102h and 102i.

Specifically, the clarification tube 102a of the clarification tank 102 has a liquid phase having a molten glass, a gas phase space formed by the liquid surface of the molten glass and the inner wall of the clarification tube 102a. At least a part of the inner wall of the fining tank 102 surrounding the gas phase space is made of a material such as platinum or a platinum alloy. In the gas phase space of the clarification tube 102a, an air flow is formed so that the platinum group metal contained in the gas phase space does not pass through a region below the temperature at which the saturated vapor pressure is reached. Alternatively, in the gas phase space of the clarification tube 102a, an air flow is formed so as to pass through a region having a temperature equal to or higher than the temperature at which the platinum group metal contained in the gas phase space has a saturated vapor pressure. Preferably, the air flow is formed so that the air flow is generated from a portion having a low temperature to a portion having a high temperature on the inner wall of the clarification tube 102a in contact with the gas phase space. The air flow is preferably generated using an air flow forming device. As the air flow forming device, it is preferable to use a pressure adjusting device that adjusts (controls) the pressure in the gas phase space. By forming a pressure difference in the gas phase space, an air flow can be generated from the high pressure region toward the low pressure region. Examples of the pressure adjusting device include a gas introduction pipe for introducing gas into the gas phase space, a suction device for sucking gas in the gas phase space, and gas. In the gas introduction pipe and the suction device, by intentionally creating a pressure distribution in the gas phase space, the platinum group metal does not pass through the region below the temperature at which the saturated vapor pressure is reached, or the platinum group metal is saturated. An air flow is formed so as to pass through a region having a temperature equal to or higher than the temperature at which the vapor pressure is reached. Or you may form an airflow by generating forced convection by introduce | transducing gas into gaseous-phase space. By introducing forced convection in the gas phase space by introducing gas, the platinum group metal does not pass through a region below the temperature at which the saturated vapor pressure is reached, or the platinum group metal has a saturated vapor pressure. An air flow is formed so as to pass through a region having a temperature higher than the temperature.
In the case of a gas introduction pipe, the pressure distribution in the gas phase space can be adjusted by changing the amount of gas introduced into the gas phase space. Further, the direction of the airflow can be adjusted by the position on the gas phase space where the gas inlet for introducing the gas into the gas phase space is provided. Furthermore, the direction of the airflow can be changed depending on the direction of gas introduction when the gas is introduced into the gas phase space. The direction of airflow can be adjusted by the state of pressure distribution generated by gas introduction or forced convection.
In the case of the suction device, the size of the pressure distribution in the gas phase space (pressure difference in the pressure distribution) can be adjusted by changing the suction pressure of the suction device. Further, the pressure distribution in the gas phase space can be adjusted by changing the position of the suction port of the suction device in the gas phase space. Moreover, the pressure in the gas phase space is adjusted by adjusting at least one of the gas release amount of the gas (gas) released from the molten glass by the defoaming treatment of the molten glass and the discharge region for releasing the gas in the gas phase space. Distribution or pressure can also be adjusted. The airflow can also be adjusted by adjusting at least one of the gas release amount and the gas release region. The pressure distribution or pressure in the gas phase space can be adjusted by adjusting at least one of the gas release amount and the discharge region, and the airflow can be adjusted by this adjustment. The pressure distribution or the pressure can be adjusted by adjusting the temperature history of the molten glass in the clarification tank 102 which is a molten glass processing apparatus. Adjustment of the temperature history of the molten glass is carried out in order to energize and heat the tube through which the molten glass flows as described later, that is, the amount of heat supplied to the molten glass by the refining tube to heat the molten glass, for example, the tube through which the molten glass flows. This can be done by adjusting the current flowing through the tube or adjusting the current according to the location of the tube. Alternatively, the temperature history of the molten glass can be adjusted by adjusting the amount of heat released from the pipe by adjusting a heat insulating member (for example, a refractory brick) provided around the pipe. As adjustment of a heat insulation member, the change of the kind, thickness, etc. of a heat insulation member can be considered. In addition, it is preferable to adjust the gas discharge amount in the gas phase space by the fining and the gas discharge region in the gas phase space by adjusting the temperature of the molten glass before the molten glass flows into the tube. Thereby, the amount of gas emission in the gas phase space and the gas emission region in the gas phase space can be adjusted more effectively and larger. The higher the temperature of the molten glass, the more the refining reaction of the clarifier progresses and the viscosity of the molten glass decreases, so the amount of outgassing increases, and in the region where the temperature of the molten glass suddenly increases, the refining agent is reduced. Become active. As a result, the gas discharge amount increases. That is, as the temperature difference between the temperature of the molten glass before the refining process and the temperature of the molten glass during the refining process is increased, the amount of gas released can be increased. That is, in order to adjust the gas release amount, it is preferable to adjust the difference between the temperature of the molten glass in the melting step, which is a previous step before the molten glass flows into the tube, and the temperature of the molten glass flowing in the tube in the treatment step. For example, the difference between the maximum temperature of the molten glass in the melting tank 101 and the maximum temperature of the molten glass in the clarification tank 102 is preferably 50 ° C. or more, more preferably 50 to 200 ° C., and 70 to 150 ° C. It is preferable that
Further, in order to increase the gas release amount, in addition to the temperature adjustment of the molten glass, it can be adjusted by the content of a fining agent such as tin oxide. For example, when the fining agent is tin oxide, the content is preferably 0.01 to 0.3 mol%, preferably 0.03 to 0.2 mol%. If the content of the clarifying agent is too large, a secondary crystal problem in which the clarifying agent volatilized from the molten glass aggregates on the inner wall of the clarifying tank 102 is not preferable. When the content of the fining agent is small, the fining effect is small and the number of bubbles increases.

  In the form shown in FIG. 3A, as a preferred form, the clarification tank 102 has gas introduction pipes 102h and 102i for introducing gas into the gas phase space. As the gas, it is preferable to use a gas inert to molten glass and platinum or a platinum alloy, for example, nitrogen gas, rare gas such as argon gas, helium gas, neon gas, or a mixed gas of these gases. By introducing these gases, the oxygen concentration in the gas phase space is preferably 5% or less. The gas introduction pipes 102h and 102i are connected to gas introduction ports 102j and 102k provided on the inner wall of the clarification pipe 102a. Therefore, as shown in FIG. 3B, the inert gas is introduced into the gas phase space through the gas inlets 102j and 102k. FIG. 3B is a diagram illustrating the gas flow inside the clarification tube 102a.

  In this embodiment, the inert gas introduced from the gas introduction pipes 102h and 102i is introduced from a nozzle such as the gas introduction ports 102j and 102k. However, the inert gas is not necessarily limited to the nozzle, and is inert by a known method. Various gases may be introduced. The introduced inert gas is preferably preheated to near the temperature of the portion of the introduced gas phase space so that the temperature difference between the temperature and the temperature in the gas phase space does not increase.

  As shown in FIG. 3B, the vent tube 102b connects the gas phase space of the clarification tube 102b and the atmosphere, and discharges the gas in the gas phase space or an inert gas to the atmosphere. The shape of the vent pipe 102b of the present embodiment is a shape that extends straight like a chimney, but is not limited to this shape. The shape etc. which bend in the middle may be sufficient.

  As described above, the clarification tank 102 is preferably provided with a suction device for sucking the gas in the gas phase space. The suction device is preferably provided so as to be connected to the vent pipe 102b. A desired air flow can be generated in the gas phase space by adjusting (controlling) the pressure of the gas phase space using the gas introduction pipe, the suction device, or both.

Although it is not illustrated around the clarification tank 102, it may be covered with a refractory brick. A vent pipe 102b is provided between the flange 102e and the flange 102f at a substantially central portion of the clarification tank 102.
The clarification tube 102a is provided with electrode plates 102c and 102d via flanges 102e and 102f. The flange 102e is provided at one end of the clarification tube 102a. The flange 102f is provided at a position in the middle of the clarification tube 102a in the longitudinal direction. Of course, the flange 102f may also be provided at the other end of the clarification tube 102a. The electrode plates 102c and 102d are connected to an AC power source 102g that is a power supply source, and a predetermined voltage is applied thereto. The flanges 102e and 102f are made of conductive metal, and flow current from the electrode plates 102c and 102d so as to be evenly distributed on the circumference of the clarification tube 102a. The electrode plates 102c and 102d raise the temperature of the molten glass MG flowing through the clarification tube 102a to, for example, 1630 ° C. or higher by passing an electric current through the clarification tube 102a and energizing and heating the clarification tube 102a.

On the other hand, the molten glass MG flows in the clarification tube 102a so that the molten glass MG has a liquid surface. The molten glass MG having a viscosity of, for example, 120 to 400 poise by energization heating of the clarification tube 102a described above causes the bubbles expanded by the action of the clarifier in the molten glass MG to break up at the liquid surface of the molten glass MG. The gas contained in the bubbles is released into the gas phase space. That is, a defoaming process is performed. Therefore, the clarification tube 102a has a gas phase space so that the molten glass MG has a liquid surface.
The gas released by breaking bubbles in the gas phase space of the clarification tube 202 is released from the vent tube 102b to the atmosphere outside the clarification tube 102.
The temperature of the molten glass MG flowing through the clarification tube 102a is maintained at, for example, 1630 ° C. or higher, and then gradually (stepwise or continuously) after the latter half of the clarification tube 102a or subsequent glass supply tube 105. Then, a foam absorption process is performed. In the absorption process, as described above, the bubbles are absorbed into the molten glass MG due to the temperature drop of the molten glass MG and disappear.
FIG. 3A shows an example in which a pair of electrode plates 102c and 102d is provided. For example, when the temperature is lowered in the latter half of the clarification tube 102a, one or more pairs of electrode plates 102c and 102d are used. An electrode plate may be provided.

  Since the clarification tube 102a is heated to a high temperature (for example, about 1700 ° C.) by energization heating as described above, platinum or platinum alloy or the like volatilizes from the inner wall of the clarification tube 102a made of platinum or platinum alloy or the like. easy. In addition, as described above, the gas phase space of the clarification tube 102a communicates with the atmosphere, so that oxygen exists in the gas phase space, and oxygen is also included as a component in the gas generated by defoaming. Therefore, the oxygen concentration in the gas phase space is higher than the oxygen concentration in the atmosphere. Therefore, volatilization of platinum or a platinum alloy is promoted. Thus, the gas phase space contains a large amount of platinum or platinum alloy volatiles volatilized from the inner wall of the clarification tube 102a.

In the clarification tank 102 of this embodiment, as shown to Fig.3 (a), gas introduction ports 102j and 102k are provided in the part which provided the flanges 102e and 102f. This is for the purpose of allowing the inert gas introduced from the gas inlets 102j and 102k to flow toward the vent pipe 102b as shown in FIG. The flanges 102e and 102f are provided to uniformly diffuse the current from the electrode plates 102c and 102d on the periphery of the clarification tube 102a, but the flanges 102e and 102f radiate heat transmitted from the clarification tube 102a to the outside. In addition, since a cooling device (not shown) for suppressing damage to the flanges 102e and 102f due to heat is provided adjacent to the flanges 102e and 102f to cool the flanges 102e and 102f, the inner wall of the clarified tube 102a provided with the flanges 102e and 102f The temperature of this portion, that is, the flange corresponding portion is lower than the temperature around this flange corresponding portion.
FIG. 4 is a diagram schematically showing an example of a temperature distribution of the temperature of the inner wall of the clarification tube 102a along the longitudinal direction of the clarification tube 102a. Such a temperature can be obtained by arranging and measuring a thermocouple or the like in the inner wall of the clarification tube 102a or in a gas phase space close to the inner wall. In the case of the clarification tube 102a, the temperature corresponding to the flange-corresponding portion where the flanges 102e and 102f are provided is lower than the temperature of the surrounding portion, more specifically, the temperature is lowest, and the temperature gradually increases as it proceeds to the vent tube 102b. . However, since the vent pipe 102b is a pipe protruding in a region close to the atmosphere, heat radiation to the atmosphere is inevitable. For this reason, temperature falls in the part in which the vent pipe 102b is provided. However, the temperature of this portion is higher than the temperature of the flange corresponding portion. The clarification tube 102a has such a temperature distribution.
Thus, in the flange corresponding part where the flanges 102e and 102f are provided, the temperature is lower than the surroundings. Therefore, when volatiles such as platinum or a platinum alloy volatilized around the flange-corresponding portion touch the flange-corresponding portion at a low temperature, the volatiles are likely to aggregate according to the temperature dependence of the saturated vapor pressure of the volatile material. . For this reason, from the flange corresponding part, the volatiles such as platinum or platinum alloy volatilized around the flange corresponding part where the flanges 102e and 102f are provided do not touch the flange corresponding part at a low temperature. An air flow caused by an inert gas is forcibly generated toward a portion where the temperature is higher than the portion corresponding to the flange. That is, molten glass and platinum are formed so that the air flow in the longitudinal direction of the long clarification tube 102a is generated from the low temperature portion to the high temperature portion of the inner wall of the clarification tube 102a in contact with the gas phase space. Alternatively, an inert gas such as platinum alloy is introduced into the gas phase space. In the present embodiment, the gas inlets 102j and 102k are provided at the flange corresponding portions where the flanges 102e and 102f are provided as described above.
In addition, as shown in FIG. 4, when the temperature is lowered at the portion where the vent pipe 102b is provided, a heater or the like is provided around the vent pipe 102b to heat the vent pipe 102b. It is possible to prevent volatile substances such as platinum or a platinum alloy from aggregating on the inner wall of the clarification tube 102a in the vicinity of the trachea 102b.

Further, in addition to the gas released from the molten glass, an inert gas that does not react with the clarification tube 102a and the molten glass is introduced into the gas phase space, so that the atmospheric pressure in the gas phase space becomes higher than the atmosphere. Due to this pressure difference, gas generated by clarification in the gas phase space, and further volatiles such as platinum or platinum alloy can be quickly discharged to the atmosphere via the vent pipe 102b. For this reason, aggregation of volatile substances such as platinum or a platinum alloy hardly occurs. Alternatively, a suction device (not shown) may be connected to the vent pipe 102b so that gas generated by clarification in the gas phase space, and further volatile substances such as platinum or platinum alloy can be quickly discharged from the vent pipe 102b. At this time, the atmospheric pressure in the gas phase space is lower than the atmospheric pressure or the pressure of the external atmosphere surrounding the clarification tank 103. Specifically, the atmospheric pressure in the gas phase space may be more than 0 to 10 Pa smaller than the atmospheric pressure (0 Pa <atmospheric pressure−inner pressure in the gas phase space <10 Pa). In addition, since an inert gas is introduced into the gas phase space, the partial pressure of oxygen in the gas phase space that easily volatilizes platinum or a platinum alloy can be reduced. For this reason, volatilization of platinum or a platinum alloy can be suppressed.
In this embodiment, since the temperature distribution of the inner wall is generated in the longitudinal direction of the clarification tube 102a, the air flow created by the introduction of the inert gas is along the longitudinal direction of the clarification tube 102a as shown in FIG. Yes. However, the air flow is not limited to being along the longitudinal direction of the clarification tube 102a, and an air flow is generated from a portion of the inner wall of the clarification tube 102a in contact with the gas phase space toward a portion where the temperature of the inner wall is high. Just do it.

In this embodiment, when the maximum temperature of the inner wall of the clarification tube 102a is 1400 ° C. or more and 1750 ° C. or less, in this embodiment, volatiles such as platinum or a platinum alloy due to an air flow in the clarification tube 102a or the ventilation tube 102b. The effect of suppressing the aggregation is increased. Further, the effect of suppressing aggregation of volatile substances such as platinum or a platinum alloy increases in this order as the maximum temperature of the inner wall of the clarification tube 102a is 1600 ° C. or higher, 1630 ° C. or higher, and 1650 ° C. or higher. When the maximum temperature of the inner wall of the clarification tube 102a is less than 1400 ° C., volatilization of platinum or a platinum alloy is not likely to be a problem, and the above effect of the present embodiment is small. The maximum temperature of the inner wall of the clarification tube 102a is more preferably 1630 ° C. or higher and 1750 ° C. or lower, and more preferably 1650 ° C. or higher and 1750 ° C. or lower. If the maximum temperature is too low, the clarification of the molten glass cannot be obtained sufficiently. On the other hand, the minimum temperature of the inner wall of the clarification tube 102a is more preferably 1200 ° C. or more and 1630 ° C. or less, still more preferably 1300 ° C. or more and 1600 ° C. or less, and particularly preferably 1400 ° C. or more and 1500 ° C. or less. . If the minimum temperature is too high, the flanges 102e and 102f are melted. On the other hand, if the minimum temperature is too low, aggregation of volatile substances such as platinum or a platinum alloy tends to occur.
In addition, if the temperature difference between the minimum temperature and the maximum temperature of the inner wall of the clarification tube 102a is large, the difference in saturation vapor pressure of platinum or platinum alloy or the like becomes large, and aggregation tends to occur. Among the inner walls, when the temperature difference between the highest temperature of the highest temperature portion and the lowest temperature of the lowest temperature portion is 50 ° C. or more and 300 ° C. or less, aggregation of volatiles such as platinum or platinum alloy in this embodiment The effect of suppressing is increased. When the temperature difference is less than 50 ° C., the degree of aggregation of volatiles such as platinum or platinum alloy is small, and the problem of aggregation hardly occurs. When the temperature difference is 150 ° C. or higher, and further 250 ° C. or higher, the effect of suppressing the aggregation of volatiles is significantly increased.
In the gas phase space of the present embodiment, adjusting (controlling) the pressure in the gas phase space so that the pressure becomes lower as the temperature becomes higher or the temperature becomes higher as the pressure becomes lower is possible. It is preferable from the viewpoint of suppressing the aggregation of.

(Glass composition)
As such a glass substrate, the glass substrate of the following glass compositions is illustrated. Accordingly, the glass raw material is used so that the glass substrate has the following glass composition. SiO _2: 55~75 mol%,
Al ₂ O _3: 5~20 mol%,
B ₂ O ₃ : 0 to 15 mol%,
RO: 5 to 20 mol%
(R is all elements contained in the glass substrate among Mg, Ca, Sr and Ba),
R ′ ₂ O: 0 to 0.8 mol% (R ′ is all elements contained in the glass substrate among Li, K, and Na).
The glass is an example of a glass having a high temperature viscosity. In such a glass, the molten glass is heated to a high temperature in order to perform defoaming with an appropriate viscosity of the molten glass in the fining tube 102a. For this reason, a large amount of volatile substances are volatilized from the inner wall of the clarification tube 102a, and aggregation of the volatile substances becomes a problem. In such a case, the effect of this embodiment that suppresses aggregation of volatiles such as platinum or a platinum alloy becomes remarkable.
At this time, at least one of SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , and RO (R is all elements contained in the glass substrate among Mg, Ca, Sr, and Ba) is included in a molar ratio. ((2 × SiO ₂ ) + Al ₂ O ₃ ) / ((2 × B ₂ O ₃ ) + RO) may be 4.0 or more. That is, a glass having a molar ratio ((2 × SiO ₂ ) + Al ₂ O ₃ ) / ((2 × B ₂ O ₃ ) + RO) of 4.0 or more is an example of a glass having a particularly high high temperature viscosity. Therefore, the effect of this embodiment which suppresses aggregation of volatiles, such as platinum or a platinum alloy, becomes more remarkable. In addition, since the glass viscosity tends to increase as the content of the alkali metal oxide decreases, the glass having a total amount of R ′ ₂ O of 0 to 0.8 mol% is particularly viscous. high. In order to sufficiently clarify glass with high viscosity, it is necessary to increase the temperature of the fining tank temperature (platinum or platinum alloy), but even in the case of manufacturing such glass with high viscosity, this embodiment The effect of suppressing the aggregation of volatiles such as platinum or a platinum alloy can be obtained.

In addition, the effect of suppressing the aggregation of volatiles such as platinum or platinum alloy of the present embodiment becomes remarkable not only when the glass having a high temperature viscosity described above is used but also when a glass having a high melting temperature is used. For example, when producing a glass having a temperature of 1500 ° C. or higher when the viscosity, which is an index of melting temperature, is 10 ^2.5 poise, the aggregation of volatiles such as platinum or platinum alloy of the present embodiment is suppressed. The effect to do becomes remarkable.

The strain point of the glass substrate may be 650 ° C. or higher, more preferably 690 ° C. or higher, and even more preferably 730 ° C. or higher. Moreover, since the glass having a high strain point tends to increase the temperature of the molten glass at a viscosity of 10 ^2.5 poise, the effect of the present embodiment becomes remarkable.

Further, when the glass raw material is melted so that the temperature of the molten glass containing tin oxide and the viscosity of 10 ^2.5 poise is 1500 ° C. or higher, the effect of this embodiment becomes more remarkable, and the viscosity is 10 The temperature of the molten glass at ^2.5 poise is, for example, 1500 to 1700 ° C, and may be 1550 to 1650 ° C.

The glass substrate manufactured by this embodiment is suitable for the glass substrate for a display containing the glass substrate for flat panel displays. It is suitable for an oxide semiconductor display glass substrate using an oxide semiconductor such as IGZO (indium, gallium, zinc, oxygen) and an LTPS display glass substrate using an LTPS (low temperature polysilicon) semiconductor. Moreover, the glass substrate manufactured by this embodiment is suitable for the glass substrate for liquid crystal displays by which it is calculated | required that content of an alkali metal oxide is very small. Moreover, it is suitable also for the glass substrate for organic EL displays. In other words, the manufacturing method of the glass substrate of this embodiment is suitable for manufacture of the glass substrate for displays, and is especially suitable for manufacture of the glass substrate for liquid crystal displays.
Moreover, the glass substrate manufactured by this embodiment is applicable also to a cover glass, the glass for magnetic discs, the glass substrate for solar cells, etc.

  Further, even in a glass substrate having a thin glass substrate thickness, for example, a glass substrate having a thickness of 0.5 mm or less, further 0.3 mm or less, and further 0.1 mm or less, volatilization of platinum or a platinum alloy of the present embodiment. The effect of suppressing the agglomeration of objects becomes more significant than that of a thick glass substrate. Part of the aggregate such as platinum or a platinum alloy aggregated on the inner wall of the clarification tube 102a or the like becomes fine particles and falls into the molten glass and is mixed into the molten glass and included in the glass substrate. In this case, as the plate thickness of the glass substrate is thinner, fine particles that become defects are often located on the surface of the glass substrate. When the fine particles located on the surface of the glass substrate are detached in the panel manufacturing process using the glass substrate, the detached part becomes a concave portion, and the thin film formed on the glass substrate is not formed uniformly, thereby creating a display defect on the screen. . Therefore, the effect of suppressing aggregation of volatiles such as platinum or a platinum alloy in the clarification tube 102a as in the present embodiment is greater as the glass substrate is thinner.

  In addition, although the example applied to the clarification tank 102 was shown in this embodiment, it can also be applied to the stirring tank 103 that homogenizes the molten glass. In this case, the portion of the inner wall of the stirring vessel 103 where the temperature is low is often the connection portion between the ceiling wall and the side wall of the stirring vessel 103. In this case, it is preferable to supply an inert gas from the connecting portion into the gas phase space. At this time, gas or gas in the gas phase space can be flowed to the outside through the gap between the stirring vessel 103 and the stirrer 103a.

The following can be said by summarizing the present embodiment.
(1) In the present embodiment, an air flow is formed in the gas phase space so that the platinum group metal contained in the gas phase space does not pass through a region below the temperature at which the saturated vapor pressure is reached. Thereby, aggregation of platinum or a platinum alloy in the gas phase space is suppressed. Moreover, aggregation of platinum or a platinum alloy can be further suppressed by creating an air flow from a low temperature region to a high temperature region in the gas phase space. The air flow is preferably formed using an air flow forming device including a pressure adjustment (control) device that adjusts (controls) the pressure in the gas phase space.
As the pressure adjusting device, it is preferable to use a gas introduction pipe for introducing gas into the gas phase space, a suction device for sucking the gas phase space, or a combination thereof.
The pressure in the gas phase space is preferably adjusted (controlled) so as to be lower in a region where the temperature of the gas phase space is higher. Thereby, an air flow can be created from a low temperature region to a high temperature region in the gas phase space.

(2) In this embodiment, it is preferable that the gas introduced from the gas introduction pipe is a gas inert to the molten glass and the platinum group metal. By introducing an inert gas into the gas phase space, it is possible to reduce the oxygen partial pressure in the gas phase space and reduce the volatilization amount of platinum or platinum alloy from the inner wall of the clarification tube 102a. Further, in the present embodiment, an inert gas is introduced into the gas phase space from a portion of the inner wall of the clarification tube 102a in contact with the gas phase space where the temperature of the inner wall is low, and volatilized platinum or platinum alloy is introduced into the gas phase space. It is preferable to create an air flow from a low temperature region to a high temperature in terms of suppressing aggregation of volatile substances such as platinum or a platinum alloy. For example, the inert gas is preferably introduced into the gas phase space from a portion of the inner wall of the clarification tube 102a having a lower temperature than the surrounding temperature, for example, a portion having a minimum temperature. Particularly preferably, it is introduced into the gas phase space from the portion of the inner wall of the clarification tube 102a where the temperature is the lowest.
In the present embodiment, since the inert gas is introduced from the portion of the clarification tube 102a where the temperature of the inner wall where the volatile matter easily aggregates is low, an air flow that allows the volatile matter to flow quickly from a place where the volatile matter easily aggregates, Reduce oxygen partial pressure. Therefore, according to the partial pressure dependence of the saturated vapor pressure of the volatile matter, aggregation of the volatile matter is suppressed.

(3) In the present embodiment, the present invention is applied to a clarification tube 102a that clarifies molten glass. The clarification tube 102a is an apparatus that heats the molten glass at the highest temperature among the apparatuses using platinum or a platinum alloy or the like from clarification to immediately before forming. For this reason, in the clarification tube 102a, the volatilization of platinum or a platinum alloy or the like is the most intense in the above apparatus. In addition, the gas component released into the gas phase space by degassing performed in the clarification tube 102a contains a large amount of oxygen that promotes volatilization, such as platinum or a platinum alloy, so the oxygen partial pressure in the gas phase space is High compared to the atmosphere. For this reason, in the gas phase space, platinum or a platinum alloy is further volatilized from the inner wall. Furthermore, since the clarification tube 102a has a larger difference between the maximum temperature and the minimum temperature of the inner wall and a difference in saturated vapor pressure of volatile matter than other devices such as the stirring vessel 103, the volatile matter is removed from the vent tube 102b. Aggregation of volatiles is likely to occur until they are exhausted through to the atmosphere. Therefore, in order to suppress aggregation of volatiles, an air flow is formed so that the platinum group metal contained in the gas phase space does not pass through a region below the temperature at which the saturated vapor pressure is reached, and is applied to the clarification tube 102a. It is preferable. In this case, the gas generated by the clarification and the air flow of the introduced inert gas flow toward the vent pipe 102b, and therefore the gas generated by the clarification can be easily discharged to the atmosphere.

  Since the ventilation pipe 102b of the clarification pipe 102a is provided at a position close to the atmosphere, the temperature of the ventilation pipe 102b tends to be lower than the temperature of the inner wall of the clarification pipe 102a, and the saturated vapor pressure is reduced. Volatiles passing through 102b are likely to aggregate. For this reason, it is preferable to suppress the aggregation of volatiles by heating the vent pipe 102b so that the saturated vapor pressure becomes larger than the vapor pressure of the volatile substances near the vent pipe 102b.

(4) The clarification tank 102 includes a long clarification tube 102a, and the clarification tube 102a is provided with flanges 102e and 102f surrounding the outer periphery of a part of the clarification tube 102a in the longitudinal direction. And gas is introduce | transduced from the part in which the flanges 102e and 102f of the clarification tube 102a are provided. Since the flanges 102e and 102f are exposed to the temperature outside the clarification tube 102a, heat is released from the flanges 102e and 102f. Therefore, the temperature of the portion of the inner wall of the clarification tube 102a where the flanges 102e and 102f are provided is lowered around the temperature. Since gas is introduced into this portion, the volatile matter that tries to touch the inner wall portion of the clarification tube 102a provided with the flanges 102e and 102f is moved to the surrounding high temperature portion, so that the volatile matter is aggregated. Can be effectively suppressed.

(5) Two flanges 102e and 102f are provided so as to surround the outer periphery at two positions in the longitudinal direction of the clarification tube 102a. One aeration tube 102b is provided between the two locations in the longitudinal direction of the clarification tube 102a. At this time, as shown in FIG. 2 (b), the gas is introduced into the gas phase space from the two locations, creates an airflow that flows in directions opposite to each other, and is discharged from one vent pipe. Therefore, it is possible to simultaneously suppress aggregation of volatile substances at two portions of the inner wall where the temperature is lowered by the flanges 102e and 102f provided at two positions in the longitudinal direction of the clarification tube 102a.

(6) In this embodiment, at least one of the flanges provided at two locations is provided at the end of the clarification tube 102a, so that the molten glass can be heated from the end of the clarification tube 102a. In particular, by providing the molten glass at the end of the clarification tube 102a on the upstream side in the direction in which the molten glass flows toward the stirring vessel 103, the molten glass can be efficiently heated.
The clarification tank 102 adjusts the temperature of the molten glass when the clarification tube 102a generates heat by energization heating of the clarification tube 102a. Thereby, clarification of molten glass can be performed quickly. However, since the clarification tube 102a is energized and heated, the temperature of the inner wall of the clarification tube 102a becomes extremely high. For this reason, volatilization of platinum or a platinum alloy is extremely severe. Even in such a case, the clarification tank 102 of the present embodiment creates the air flow as described above in the gas phase space, and thus can suppress aggregation of volatile substances in the clarification tube 102a.
The clarification tube 102a of the clarification tank 102 is provided with flanges 102 and 102f surrounding the outer periphery of a portion of the clarification tube 102a in the longitudinal direction, and a current is passed from the flanges 102e and 102f to the clarification tube 102a of the clarification tank 102 for clarification. Since the tube 102a has a power supply source for adjusting the temperature of the molten glass by generating heat, the clarified tube 102a generates relatively uniform heat on the periphery of the clarified tube 102a and does not cause unevenness in the temperature of the molten glass. . For this reason, clarification of molten glass can be performed efficiently.

  In the present embodiment, an electric heating method is used for heating the molten glass by causing an electric current to flow directly through the clarification tube 102a, but the method is not limited to the electric heating method. For example, the temperature of the molten glass may be adjusted by indirectly heating the clarification tube 102a by providing a heat source such as a heater around the clarification tube 102a. In the current heating system in which a current is passed through the clarification tube 102a, it is easy to adjust the temperature of the molten glass. However, since the inner wall of the clarification tube 102a is also heated at the same time, temperature unevenness is likely to occur on the inner wall of the clarification tube 102a, and aggregation of volatile substances such as platinum or a platinum alloy is likely to occur. However, by adopting this embodiment, aggregation of volatiles such as platinum or a platinum alloy can be suppressed even in the case of such a current heating method. Therefore, in the case of the current heating method, the effect of suppressing aggregation of volatiles such as platinum or platinum alloy is greater than when the clarification tube 102a is indirectly heated by a heater or the like.

(7) In the present embodiment, the gas is injected from the gas inlets 102j and 102k into the gas phase space in the direction perpendicular to the liquid surface of the molten glass, but the gas injection direction is not particularly limited. FIG. 3C illustrates another example of the gas flow inside the clarification tube 102a. As shown in FIG. 3 (c), it is possible to inject gas obliquely so that the gas injection direction is directed toward the center in the longitudinal direction where the ventilation pipe 102b of the clarification pipe 102a is provided. This is preferable in that the flow toward 102b can be easily made. Alternatively, gas may be introduced into the gas phase space toward both ends of the clarification tube 102a, and the gas may be reflected by the wall surfaces at both ends of the clarification tube 102a, and then a flow toward the vent 102b may be created.

  As mentioned above, although the manufacturing apparatus of the glass substrate of the present invention, the manufacturing method of the glass substrate, and the molten glass processing apparatus were explained in detail, the present invention is not limited to the above-mentioned embodiment, and in the range which does not deviate from the main point of the present invention, Of course, various improvements and changes may be made.

DESCRIPTION OF SYMBOLS 100 Molten glass production | generation apparatus 101 Melting tank 101d Screw feeder 102 Clarification tank 102a Clarification pipe 102b Venting pipe 102c, 102d Electrode plate 102e, 102f Flange 102g AC power supply 102h, 102i Gas introduction pipe 102j, 102k Gas introduction port 103 Stirrer tank 103a Stirrer 104 , 105, 106 Glass supply pipe 200 Molding device 210 Molded body 300 Cutting device

Claims (13)

A melting step of melting glass raw material to produce molten glass;
It has a liquid phase having the molten glass and a gas phase space formed from the liquid surface and inner wall of the molten glass, and at least a part of the inner wall surrounding the gas phase space is made of a material containing a platinum group metal. A processing step of processing the molten glass in a molten glass processing apparatus,
In the gas phase space of the molten glass processing apparatus, an air flow is formed,
The method of manufacturing a glass substrate, wherein the air flow is formed so as to pass through a region having a temperature equal to or higher than a temperature at which a platinum group metal contained in the gas phase space has a saturated vapor pressure. A melting step of melting glass raw material to produce molten glass;
It has a liquid phase having the molten glass and a gas phase space formed from the liquid surface and inner wall of the molten glass, and at least a part of the inner wall surrounding the gas phase space is made of a material containing a platinum group metal. A processing step of processing the molten glass in a molten glass processing apparatus,
In the gas phase space of the molten glass processing apparatus, an air flow is formed,
The said air flow is formed so that it may not pass through the area | region which falls below the temperature from which the platinum group metal contained in the said gaseous-phase space becomes saturated vapor pressure, The manufacturing method of the glass substrate characterized by the above-mentioned.   The said air flow is a manufacturing method of the glass substrate of Claim 1 or 2 which is an air flow which flows toward the high part from the low temperature part of the inner wall of the said molten glass processing apparatus which contact | connects the said gaseous-phase space.   The said air flow is a manufacturing method of the glass substrate of Claim 1 or 2 formed by adjusting the pressure in the said gaseous-phase space.   The said air flow is a manufacturing method of the glass substrate of any one of Claims 1-4 formed by introduce | transducing gas in the said gaseous-phase space.   The said gas is manufacture of the glass substrate of Claim 5 introduced into the said gaseous-phase space from the part whose temperature is low compared with the surrounding temperature among the inner walls of the said molten glass processing apparatus which contact | connects the said gaseous-phase space. Method.   The glass according to any one of claims 1 to 6, wherein the air flow is formed by adjusting a pressure distribution in the gas phase space by a suction device provided so as to be connected to the gas phase space. A method for manufacturing a substrate.   The manufacturing method of the glass substrate of any one of Claims 1-7 whose temperature difference between the part with the highest temperature of the said inner wall and the lowest part is 50 to 300 degreeC.   The molten glass processing device is a clarification tank that clarifies the molten glass and discharges a gas generated by the clarification to the atmosphere through a vent pipe connecting the gas phase space and the atmosphere. The manufacturing method of the glass substrate of any one of Claims 1-8 which is the flow which goes to a trachea.   The said glass substrate is a manufacturing method of the glass substrate of any one of Claims 1-9 which is a glass substrate for displays. A molten glass processing apparatus for processing molten glass,
An inner wall made of a material containing at least a platinum group metal;
A liquid phase space having a molten glass;
A gas phase space formed from the liquid surface of the molten glass and the inner wall,
An airflow is formed in the gas phase space,
The molten glass processing apparatus, wherein the air flow is formed so as to pass through a region having a temperature equal to or higher than a temperature at which a platinum group metal contained in the gas phase space has a saturated vapor pressure. A molten glass processing apparatus for processing molten glass,
An inner wall made of a material containing at least a platinum group metal;
A liquid phase space having a molten glass;
A gas phase space formed from the liquid surface of the molten glass and the inner wall,
An airflow is formed in the gas phase space,
The molten glass processing apparatus, wherein the airflow is formed so as not to pass through a region below a temperature at which a platinum group metal contained in the gas phase space has a saturated vapor pressure. A melting device that melts glass raw materials to produce molten glass;
An apparatus for manufacturing a glass substrate, comprising: the molten glass processing apparatus according to claim 11.

Images