TW201538441A - Glass substrate manufacturing method and glass substrate manufacturing device - Google Patents

Abstract

The object of the present invention is to inhibit the oxidation and volatilization of platinum group metal. This invention provides a glass substrate manufacturing method using a processing device for processing molten glass to process the molten glass. By means of forming a vapor space in the upper portion of liquid surface of the molten glass, the method comprises the following steps: molten glass is supplied to the interior of a processing device having an inner wall, at least one portion of which comprises a material containing platinum group metal, so that a gas which acts as an inert gas to the platinum group metal may flow into the vapor space; an exhaust port at the external space connecting the processing device with the vapor space is used for sucking the gas in the vapor space; the oxygen concentration of the gas sucked from the exhaust port is measured, and the inflow of gas that acts as an inert gas to the platinum group metal is adjusted in a manner of maintaining the oxygen concentration in a range below 5.0%.

Description

Method for producing glass substrate and device for manufacturing glass substrate

The present invention relates to a method for producing a glass substrate for producing a glass substrate and a device for producing a glass substrate.

In general, a glass substrate is produced by the step of forming molten glass from a glass raw material, and molding the molten glass into a glass substrate. In the above steps, the step of removing minute bubbles contained in the molten glass (hereinafter also referred to as clarification) is included. The clarification is carried out by heating the body of the clarification tube while passing the molten glass containing the clarifying agent through the clarification tube body, and removing the bubbles in the molten glass by the redox reaction of the clarifying agent. More specifically, the temperature of the molten glass which is coarsely melted is further increased, and the clarifying agent functions to defoam the bubble, and then the temperature is lowered, whereby the molten glass is absorbed by the defoaming and remains relatively low. Small bubble. That is, the clarification includes a treatment for defoaming the bubble (hereinafter also referred to as a defoaming treatment or a defoaming step) and a treatment for absorbing the vesicles to the molten glass (hereinafter also referred to as an absorption treatment or absorption step).

The inner wall of the member that is in contact with the high-temperature molten glass before molding needs to be composed of a suitable material depending on the temperature of the molten glass that is in contact with the member, the quality of the desired glass substrate, and the like. For example, it is known that a material constituting the above-mentioned clarification pipe body is generally a simple substance or an alloy of a platinum group metal (Patent Document 1). The platinum group metal has a high melting point and is excellent in corrosion resistance to molten glass.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2010-111533

When the molten glass passes through a treatment apparatus using a platinum group metal on the inner wall surface, the platinum group metal volatilizes as an oxide in a portion in contact with the vapor phase space (oxygen-containing atmosphere) of the heated inner surface. On the other hand, the oxide of the platinum group metal is reduced at a position where the temperature of the treatment apparatus is locally lowered, and the reduced platinum group metal adheres to the inner wall surface. The platinum group metal adhered to the inner wall surface is dropped and mixed into the molten glass in the defoaming step to be mixed as a foreign matter into the glass substrate.

An object of the present invention is to provide a method and a device for producing a glass substrate which can suppress oxidation of a platinum group metal and volatilize it to produce a glass substrate having high quality.

In order to solve the above problems, a first aspect of the present invention provides a method for producing a glass substrate, which is characterized in that a molten glass is treated by a treatment apparatus for treating molten glass, and a molten glass is used when the molten glass is treated. The upper portion forms a gas phase space, and the inside of the inner wall is provided with a treatment device for containing a material containing a platinum group metal, and the molten glass is supplied from the outer space of the gas phase space and the outer space of the processing device. The gas in the gas phase space is sucked, and a gas inert to the platinum group metal flows into the gas phase space, and the oxygen concentration in the gas sucked from the exhaust port is measured so that the oxygen concentration becomes 5.0% or less. In the manner of the range, the inflow amount of the gas inert to the platinum group metal toward the gas phase space is adjusted.

Here, the gas system which is inert to the platinum group metal refers to a gas which is inert to the platinum group metal at a temperature of the gas phase space when the molten glass is treated in the treatment apparatus, and which is less reactive with the platinum group metal than oxygen. For example, nitrogen (N ₂ ), a rare gas (for example, argon (Ar)), carbon monoxide (CO), or the like.

Preferably, the suction pressure from the exhaust port is adjusted so that the oxygen concentration is in the range of 5.0% or less. Furthermore, it is preferable to adjust the supply amount of the gas inert to the platinum group metal so that the oxygen concentration is in the range of 0.1% or more and 3.0% or less.

Preferably, the treatment device supplies the gas inert to the platinum group metal to the gas phase space from the upstream side and the downstream side of the molten glass.

Preferably, the gas which is supplied to the upstream side of the molten glass and which is inert to the platinum group metal is supplied with more gas which is inert to the platinum group metal than the gas supplied from the downstream side of the molten glass.

Preferably, the gas inert to the platinum group metal is preheated before flowing into the gas phase space. For example, it is preferred to preheat the gas inert to the platinum group metal to 500 ° C or higher before flowing into the gas phase space.

Preferably, the treatment device clarifies the clarification treatment device for the molten glass, and the maximum temperature of the molten glass in the clarification treatment device is 1600 to 1720 °C.

A second aspect of the present invention provides a glass substrate manufacturing apparatus characterized by treating a molten glass using a clarification treatment apparatus for clarifying molten glass, and comprising: a clarification treatment apparatus, wherein at least a part of an inner wall thereof contains platinum a material of a group metal, which is internally supplied with molten glass, and forms a gas phase space above the liquid surface of the molten glass; a gas supply device that supplies a gas other than oxygen to the gas phase space; and an exhaust port that connects the above a gas phase space and an outer space of the clarification treatment device; a suction device that sucks gas in the gas phase space from the exhaust port, Flowing a gas other than oxygen into the gas phase space; an oxygen concentration meter measuring the oxygen concentration in the gas sucked from the exhaust port; and a control device according to the measurement result of the oxygen concentration meter to make the above The suction pressure from the above-mentioned exhaust port is adjusted in such a manner that the oxygen concentration becomes a specific range.

According to the present invention, by adjusting the suction pressure from the exhaust port in such a manner that the oxygen concentration in the gas sucked from the exhaust port becomes a specific range, the oxygen concentration in the gas phase space in the processing apparatus can be adjusted to The required range. Thereby, the volatilization of the platinum group metal due to the increase in the oxygen concentration in the gas phase space can be suppressed, and the amount of the platinum group metal which is volatilized can be reduced.

100‧‧‧melting device

101‧‧‧melting tank

103‧‧‧Stirring tank

103a‧‧‧Agitator

104‧‧‧Transfer tube

105‧‧‧Transfer tube

106‧‧‧Glass supply tube

120‧‧‧Clarification tank

120a‧‧‧ gas phase space

121a‧‧‧electrode

121b‧‧‧electrode

122‧‧‧Power supply unit

123‧‧‧Control device

124a‧‧‧ flushing gas supply pipe

124b‧‧‧ flushing gas supply pipe

125a‧‧‧ flushing gas supply device

125b‧‧‧ flushing gas supply device

127‧‧‧Exhaust pipe

128‧‧‧Oxygen concentration meter

129‧‧‧ suction device

200‧‧‧Forming device

300‧‧‧ cutting device

MG‧‧‧ molten glass

ST1‧‧‧melting step

ST2‧‧‧Clarification steps

ST3‧‧‧ homogenization steps

ST4‧‧‧ supply steps

ST5‧‧‧ forming steps

ST6‧‧‧ Slow cooling step

ST7‧‧‧ cutting steps

Fig. 1 is a view showing the flow of a method of manufacturing a glass substrate.

2 is a schematic view showing a manufacturing apparatus of a glass substrate.

Figure 3 is a schematic view of the clarification tube shown in Figure 2.

Figure 4 is a vertical cross-sectional view of the longitudinal direction of the clarification tube.

Hereinafter, a method of producing a glass substrate and a glass substrate manufacturing apparatus of the present invention will be described.

Further, the "processing apparatus" of the present invention includes a melting tank, a clarification tube, a stirring tank or a forming device, and a transfer pipe for transferring molten glass between the devices, and a supply pipe for supplying the glass to the devices. The "treatment" in the processing apparatus includes melting treatment of glass, clarification treatment of molten glass, stirring treatment, molding processing, transfer processing of molten glass, and supply processing.

(Overall outline of the manufacturing method of the glass substrate)

Fig. 1 is a view showing an example of a procedure of a method for producing a glass substrate of the present embodiment. The manufacturing method of the glass substrate mainly includes a melting step (ST1), a clarification step (ST2), a homogenization step (ST3), a supply step (ST4), a forming step (ST5), and a slow cooling step. (ST6), and a cutting step (ST7). Further, it may have a grinding step, a grinding step, a washing step, an inspection step, a packing step, and the like. It is also possible to laminate the produced glass substrate in the packing step as needed and to transport it to the buyer.

In the melting step (ST1), molten glass is produced by heating a glass raw material. The heating of the molten glass can be performed by electric heating, and the electric heating causes the molten glass itself to be energized to generate heat and to be heated. Further, the glass raw material may be melted by the flame assisted heating of the burner.

Further, the molten glass contains a clarifying agent. As the clarifying agent, tin oxide, arsenious acid, cerium, or the like is known, but is not particularly limited. However, in terms of reducing environmental load, it is preferred to use tin oxide as a fining agent.

In the clarification step (ST2), by heating the molten glass, a bubble containing oxygen, CO ₂ or SO ₂ contained in the molten glass is produced. The bubble absorbs and grows due to oxygen generated by the reduction reaction of the clarifying agent, floats and is released to the liquid surface of the molten glass. Thereafter, in the clarification step, the reducing substance obtained by the reduction reaction of the clarifying agent is oxidized by lowering the temperature of the molten glass. Thereby, the gas component such as oxygen in the bubble remaining in the molten glass is reabsorbed into the molten glass to cause the bubble to disappear. The oxidation reaction and the reduction reaction using the clarifying agent are carried out by controlling the temperature of the molten glass.

Further, the clarification step may also be a vacuum defoaming method in which the bubbles present in the molten glass are grown in a reduced pressure atmosphere to defoam. The vacuum defoaming mode is effective in not using a clarifying agent. However, the decompression and defoaming method causes the device to be complicated and enlarged. Therefore, it is preferred to use a clarifying method using a clarifying agent to raise the temperature of the molten glass.

In the homogenization step (ST3), the glass component is homogenized by stirring the molten glass using a stirrer. Thereby, the composition unevenness of the glass which causes streaks etc. can be reduced.

In the supplying step (ST4), the molten glass after the stirring is supplied to the forming apparatus.

The molding step (ST5) and the slow cooling step (ST6) are performed by a molding apparatus.

In the forming step (ST5), the molten glass is formed into a sheet glass to form a flow of the sheet glass. Forming uses an overflow down-draw method.

In the slow cooling step (ST6), the sheet glass which is formed and flows is made to have a desired thickness, and the inner strain is not generated, and the film is cooled without causing warpage.

In the cutting step (ST7), a plate-shaped glass substrate is obtained by cutting the slowly cooled sheet glass into a specific length. Further, the cut glass substrate is cut into a specific size to produce a glass substrate of a target size.

Fig. 2 is a schematic view showing a manufacturing apparatus of a glass substrate which performs the melting step (ST1) to the cutting step (ST7) in the present embodiment. As shown in FIG. 2, the manufacturing apparatus of a glass substrate mainly includes the melting apparatus 100, the shaping apparatus 200, and the cutting apparatus 300. The melting apparatus 100 includes a melting tank 101, a clarification pipe 120, a stirring tank 103, transfer pipes 104 and 105, and a glass supply pipe 106.

A heating mechanism such as a burner (not shown) is provided in the melting tank 101 shown in Fig. 2 . A glass raw material to which a clarifying agent is added is introduced into the melting tank, and a melting step (ST1) is performed. The molten glass to be melted in the melting tank 101 is supplied to the clarification pipe 120 via the transfer pipe 104.

In the clarification pipe 120, the temperature of the molten glass MG is adjusted, and the clarification step (ST2) of the molten glass is performed by the oxidation-reduction reaction of the clarifying agent. The clarified molten glass is supplied to the stirring tank via the transfer pipe 105.

In the stirring tank 103, the molten glass is stirred by the stirrer 103a, and the homogenization process (ST3) is performed. The molten glass which has been homogenized in the agitation tank 103 is supplied to the molding apparatus 200 via the glass supply pipe 106 (supply step ST4).

In the molding apparatus 200, the molten glass is formed into a sheet glass by the overflow down-draw method (forming step ST5), and gentle cooling is performed (slow cooling step ST6).

In the cutting device 300, a plate-shaped glass substrate cut out from the sheet glass is formed (cutting step ST7).

(constitution of clarification pipe)

Next, the configuration of the clarification pipe 120 will be described with reference to Figs. 3 and 4 . 3 is a schematic view showing the configuration of the clarification pipe 120 of the embodiment, and FIG. 4 is a vertical cross-sectional view of the clarification pipe 120 in the longitudinal direction.

As shown in FIGS. 3 and 4, electrodes 121a and 121b are provided on the outer peripheral surface of both ends of the clarification pipe 120 in the longitudinal direction, and an exhaust pipe 127 is provided on the wall of the clarification pipe 120 that is in contact with the gas phase space.

The body of the clarification tube 120, the electrodes 121a, 121b, and the exhaust pipe 127 are made of a platinum group metal. In the present specification, the term "platinum group metal" means a metal containing a platinum group element, and is used as a term which includes not only a metal composed of a single platinum group element but also an alloy containing a platinum group element. Here, the platinum group element means six elements such as platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), osmium (Os), and iridium (Ir). Although the platinum group metal is expensive, it has a high melting point and is excellent in corrosion resistance to molten glass.

Further, in the present embodiment, the case where the clarification pipe 120 is composed of a platinum group metal will be described as a specific example, but a part of the clarification pipe 120 may be composed of a refractory or other metal.

The electrodes 121a and 121b are connected to the power supply device 122. A voltage is applied between the electrodes 121a and 121b to cause a current to flow to the clarification tube 120 between the electrodes 121a and 121b, and the clarification tube 120 is electrically heated. By the electric heating, the maximum temperature of the main body of the clarification pipe 120 is heated to, for example, 1600 ° C to 1750 ° C, more preferably 1630 ° C to 1750 ° C, and the maximum temperature of the molten glass supplied from the transfer pipe 104 is heated. The temperature suitable for defoaming is, for example, 1600 ° C to 1720 ° C, more preferably 1620 ° C to 1720 ° C.

Further, by controlling the temperature of the molten glass by electric heating, the viscosity of the molten glass is adjusted, whereby the flow rate of the molten glass passing through the clarification pipe 120 can be adjusted.

Further, a temperature measuring device (such as a thermocouple) (not shown) may be provided on the electrodes 121a and 121b. The temperature measuring device measures the temperatures of the electrodes 121a, 121b, and outputs the measured results to the control device 123.

The control device 123 controls the amount of current that the power supply unit 122 energizes the clarification tube 120, thereby controlling the temperature and flow rate of the molten glass passing through the clarification tube 120. The control device 123 is a computer including a CPU (Central Processing Unit), a memory, and the like.

Further, in the present embodiment, the electrode 121a may be provided with a flushing gas supply pipe 124a for supplying the gas phase space 120a above the liquid surface of the molten glass in the clarification pipe 120. A gas other than oxygen (flush gas). Similarly, the electrode 121b may be provided with a flushing gas supply pipe 124b for supplying a flushing gas to the gas phase space 120a above the liquid surface of the molten glass in the clarification pipe 120.

The flushing gas supply pipe 124a is connected to the flushing gas supply device 125a, and the flushing gas supply device 125a supplies the flushing gas from the upstream side of the molten glass to the vapor phase space 120a in the clarification pipe 120 via the flushing gas supply pipe 124a. Similarly, the flushing gas supply pipe 124b is connected to the flushing gas supply device 125b, and the flushing gas supply device 125b supplies the flushing gas from the downstream side of the molten glass to the vapor phase space 120a in the clarification pipe 120 via the flushing gas supply pipe 124b.

The amount of the flushing gas supplied from the flushing gas supply pipes 124a, 124b can be adjusted by adjusting the inner diameters of the flushing gas supply pipes 124a, 124b.

As the flushing gas, a gas other than oxygen can be used, and in particular, a gas which is inert to the platinum group metal and a gas which is less reactive with the platinum group metal than oxygen. Specifically, nitrogen (N ₂ ), a rare gas (for example, argon (Ar)), carbon monoxide (CO), or the like can be used. In terms of ease of handling, it is preferred to use N ₂ gas. On the other hand, the flushing gas is dissolved in the molten glass in the step of lowering the glass temperature after the clarification step or clarification. Ar or CO tends to move in the glass structure compared to N ₂ . Therefore, even when the flushing gas dissolved in the molten glass is generated as a bubble, it is easily sucked into the glass again during the transfer of the molten glass, and Ar can also be used in terms of the bubble quality. In addition, in FIG. 4, nitrogen gas is mentioned as a flushing gas as an example.

The flushing gas supply devices 125a and 125b are controlled by the control device 123 to adjust the supply amount and supply pressure of the flushing gas.

An exhaust pipe 127 is provided in the wall of the clarification pipe 120 that is in contact with the gas phase space. The exhaust pipe 127 is disposed above the gas phase space 120a. The exhaust pipe 127 is preferably disposed between the upstream end portion and the downstream end portion in the flow direction of the molten glass in the clarification pipe 120. The exhaust pipe 127 may also have a shape protruding from the outer wall surface of the clarification pipe 120 toward the outer side in a chimney shape. The exhaust pipe 127 communicates the gas phase space 120a (refer to FIG. 4) with the outer space of the clarification pipe 120.

A suction device 129 for sucking gas in the gas phase space 120a is provided in the exhaust pipe 127. By decompressing the exhaust pipe 127 side by the suction device 129 (for example, a pressure reduction of about 10 Pa by a large air pressure), the oxygen gas and the flushing gas in the gas phase space 120a can be efficiently discharged. The suction device 129 is controlled by the control device 123. By controlling the suction pressure of the suction device 129, the concentration of oxygen (oxygen partial pressure) in the gas phase space 120a can be lowered. Further, by controlling the suction pressure, the amount of the flushing gas supplied from the flushing gas supply means 125a, 125b to the gas phase space 120a can be adjusted.

An oxygen concentration meter 128 is provided in the exhaust pipe 127. The oxygen concentration meter 128 measures the oxygen concentration of the gas sucked from the exhaust pipe 127, and outputs a measurement signal thereof to the control device 123. Further, when the flushing gas is not supplied to the gas phase space 120a, the partial pressure of oxygen in the gas sucked from the exhaust pipe 127 can also be measured.

In the present embodiment, the oxygen released from the molten glass in the clarification pipe 120 can be discharged by sucking the gas in the gas phase space 120a from the exhaust pipe 127. Further, by supplying the flushing gas to the gas phase space 120a from the flushing gas supply pipe 124a and the flushing gas supply pipe 124b, the oxygen concentration in the gas phase space 120a can be lowered. Thereby, the platinum group metal can be suppressed from being volatilized by oxidation, thereby reducing the amount of precipitation of the platinum group metal caused by the reduction of the volatilized platinum group metal.

Here, in the present embodiment, the oxygen concentration of the gas discharged from the exhaust pipe 127 is measured by the oxygen concentration meter 128, and the supply of the flushing gas is adjusted so that the oxygen concentration becomes a fixed range (for example, a range of 5.0% or less). the amount. That is, it will be measured by the oxygen concentration meter 128. The signal of the oxygen concentration is output to the control device 123, and the control device 123 controls the flushing gas supply devices 125a and 125b based on the signal of the oxygen concentration to adjust the supply amount and the supply pressure of the flushing gas.

Preferably, the suction pressure from the exhaust port or the supply amount of the flushing gas is adjusted so that the oxygen concentration of the gas sucked from the exhaust pipe 127 is in the range of 5.0% or less. If the oxygen concentration is more than 5.0%, the volatilization of the platinum group metal is promoted, and the precipitation amount of the volatilized platinum group metal is increased.

Moreover, in order to further suppress the volatilization and precipitation of the platinum group, it is preferable to adjust the supply amount of the flushing gas so that the oxygen concentration becomes 3.0% or less. In the glass substrate for manufacturing a high-resolution display, fine defects having a thickness (diameter) of less than 1 μm are not allowed, and by setting the oxygen concentration to 3.0% or less, the thickness (diameter) of less than 1 μm can be prevented from being generated. Needle-shaped platinum defects.

Further, when the flushing gas is supplied so that the oxygen concentration is less than 0.1%, the temperature of the clarification tube 120 is lowered by the flushing gas. Further, by increasing the supply amount and flow rate of the flushing gas, the flushing gas is blown to the liquid surface of the molten glass, and the flushing gas is dissolved in the molten glass. As a result, when the temperature of the molten glass is lowered, there is a bubble which causes a bubble of the dissolved flushing gas. Therefore, it is preferable to adjust the supply amount of the flushing gas so that the oxygen concentration becomes 0.1% or more. In order to suppress the temperature of the clarification pipe 120 from being lowered by the flushing gas and to suppress generation of bubbles by the flushing gas to be dissolved, it is particularly preferable to adjust the supply amount of the flushing gas so that the oxygen concentration becomes 1% or more.

In the above case, it is preferable to adjust the supply amount of the flushing gas so that the oxygen concentration is in the range of 0.1% or more and 3.0% or less, and more preferably, the oxygen concentration is adjusted to be in the range of 1% or more and 3.0% or less. The amount of flushing gas supplied.

In order to prevent the cooling of the molten glass, it is preferable to preheat the flushing gas supplied from the flushing gas supply devices 125a and 125b before flowing into the vapor phase space 120a. The preheating temperature of the flushing gas is preferably, for example, preheated to 500 ° C or higher.

Since the amount of oxygen released from the molten glass in the clarification pipe 120 is more on the upstream side than the downstream side of the molten glass, it is preferable to supply the flushing gas supplied from the upstream side of the molten glass to the downstream side from the molten glass. More gas. That is, it is preferable that the amount of the flushing gas supplied from the flushing gas supply pipe 124a is larger than the amount of the flushing gas supplied from the flushing gas supply pipe 124b. By making the amount of the flushing gas supplied from the flushing gas supply pipe 124a larger than the amount of the flushing gas supplied from the flushing gas supply pipe 124b, it is possible to more efficiently dilute and discharge the oxygen released from the molten glass by the flushing gas.

The method of producing the glass substrate of the present invention has been described in detail above, but the present invention is not limited to the above-described embodiments, and various modifications and changes can be made without departing from the spirit and scope of the invention. In the above description, the clarification pipe has been described as an example of the treatment device. However, the present invention is not limited thereto, and the present invention may be applied to a melting tank, a stirring tank, a molding apparatus, a transfer pipe, and a supply pipe.

The glass substrate produced by the production method of the present embodiment is preferably used, for example, as a glass substrate for a liquid crystal display, a glass substrate for an organic EL (electroluminescence) display, or a cover glass. Further, it can also be used as a cover glass for a mobile terminal device or the like, a cover glass for a casing, a glass substrate for a solar cell, or a cover glass. In particular, it is suitable for a glass substrate for a liquid crystal display using a polycrystalline silicon TFT (Thin Film Transistor).

104‧‧‧Transfer tube

105‧‧‧Transfer tube

120‧‧‧Clarification tank

121a‧‧‧electrode

121b‧‧‧electrode

122‧‧‧Power supply unit

123‧‧‧Control device

124a‧‧‧ flushing gas supply pipe

124b‧‧‧ flushing gas supply pipe

125a‧‧‧ flushing gas supply device

125b‧‧‧ flushing gas supply device

127‧‧‧Exhaust pipe

128‧‧‧Oxygen concentration meter

129‧‧‧ suction device

Claims (9)

A method for producing a glass substrate, which comprises treating a molten glass by using a processing device for treating molten glass, and when processing the molten glass, forming a gas phase space at a portion above the liquid surface of the molten glass, and including at least a part of the inner wall The inside of the processing device for the material containing the platinum group metal is supplied with the molten glass, and the gas in the gas phase space is sucked from the exhaust port connecting the gas phase space and the outer space of the processing device, so that the platinum group metal is The inert gas flows into the gas phase space, and the oxygen concentration in the gas sucked from the exhaust port is measured, so that the gas having the inertness to the platinum group metal is adjusted so that the oxygen concentration is in the range of 5.0% or less. The inflow amount of the above gas phase space. The method for producing a glass substrate according to claim 1, wherein the suction pressure from the exhaust port is adjusted so that the oxygen concentration is in a range of 5.0% or less. The method for producing a glass substrate according to claim 2, wherein the supply amount of the gas inert to the platinum group metal is adjusted so that the oxygen concentration is in a range of 0.1% or more and 3.0% or less. The method for producing a glass substrate according to claim 2 or 3, wherein the processing means supplies a gas inert to the platinum group metal to the gas phase space from the upstream side and the downstream side of the molten glass. The method for producing a glass substrate according to claim 4, wherein the gas which is inert to the platinum group metal supplied from the upstream side of the molten glass is supplied to the gas which is inert to the platinum group metal from the downstream side of the molten glass many. The method for producing a glass substrate according to any one of claims 1 to 5, wherein The gas inert to the platinum group metal is preheated before flowing into the gas phase space. The method of producing a glass substrate according to claim 6, wherein the gas inert to the platinum group metal is preheated to 500 ° C or higher before flowing into the gas phase space. The method for producing a glass substrate according to any one of claims 1 to 7, wherein the processing device is a clarification processing device for clarifying the molten glass, and wherein the maximum temperature of the molten glass in the clarification treatment device is 1600 to 1720 °C. A glass substrate manufacturing apparatus for treating molten glass using a clarification treatment apparatus for clarifying molten glass, and comprising: a clarification treatment apparatus, wherein at least a part of an inner wall thereof contains a material containing a platinum group metal, and the inside is supplied with molten glass And forming a gas phase space above the liquid surface of the molten glass; a gas supply device supplying a gas other than oxygen to the gas phase space; and an exhaust port connecting the gas phase space and the outside of the clarification treatment device a suction device that draws gas in the gas phase space from the exhaust port to cause a gas other than oxygen to flow into the gas phase space; an oxygen concentration meter that measures the suction from the exhaust port The oxygen concentration in the gas; and a control device that adjusts the suction pressure from the exhaust port so that the oxygen concentration is within a specific range based on the measurement result of the oxygen concentration meter.