KR20150037609A - Method for manufacturing glass substrate, apparatus for manufacturing glass substrate, and molten glass processing device - Google Patents

Abstract

Disclosure of the Invention [0008] It is an object of the present invention to provide a glass processing apparatus, which is used at least in part in manufacturing a glass substrate, and which is made of a material containing a platinum group metal, which suppresses volatilization of the platinum group metal from the inner wall made of a platinum group metal, It is possible to prevent a part of the platinum metal agglomerates from being mixed into the molten glass.
The solution means of the present invention is characterized by comprising a liquid phase of a molten glass obtained by melting a raw material of glass and a vapor phase space formed by the liquid surface and the inner wall of the molten glass before forming the glass substrate by molding the molten glass, Is to treat the molten glass using a molten glass processing apparatus in which at least a part of the inner wall is made of a material containing a platinum group metal. At this time, in order to reduce volatilization of the platinum group metal in the molten glass processing apparatus, the ratio of the area of the platinum group metal on the inner wall contacting the vapor space to the volume of the vapor space, or the ratio of the volume of the molten glass To control the level of the liquid.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a glass substrate manufacturing method, a glass substrate manufacturing apparatus, and a molten glass processing apparatus,

The present invention relates to a method of manufacturing a glass substrate for producing a glass substrate by molding a molten glass produced by melting a glass raw material, a glass substrate manufacturing apparatus, and a molten glass processing apparatus for processing molten glass.

A glass substrate is generally manufactured by forming a molten glass from a glass raw material, and then molding the molten glass into a glass substrate through a refining process and a homogenizing process.

In order to mass-produce a glass substrate having a high quality from molten glass at a high temperature, it is desired to consider that foreign matter or the like which is a defective factor of the glass substrate is not mixed into the molten glass from any apparatus for manufacturing the glass substrate. For this reason, the inner wall of the member in contact with the molten glass in the process of manufacturing the glass substrate needs to be made of a suitable material depending on the temperature of the molten glass in contact with the member, the quality of the required glass substrate, and the like. For example, since the molten glass is in a high temperature state until the molten glass is produced and supplied to the molding process, it is necessary to use a cleaning device for performing a cleaning process, a stirring device for performing a homogenization process, Is made of a platinum group metal having high heat resistance. However, the platinum group metal is liable to volatilize due to the high temperature of the molten glass. Volatiles of the platinum group metal coagulate on the inner wall surrounding the vapor phase to form an aggregate, and a part of the aggregate is separated and becomes a foreign matter in the molten glass, which may cause deterioration of the quality of the glass substrate.

On the other hand, there is known a glass melting furnace capable of obtaining high-quality glass with less risk of incorporation of foreign matter of platinum and less optical defects such as cracks and foreign matter defects (Patent Document 1).

In the glass melting furnace, the lower portion of the inner wall surface of the bath main body closed with a ceiling portion is formed of a platinum surface made of platinum or a platinum alloy, and the upper end of the platinum surface is exposed Is formed.

Japanese Patent Application Laid-Open No. 2010-202444

As in Patent Document 1, when the contact area between the atmosphere of the vapor phase space above the liquid surface of the molten glass and the wall surface of the platinum group metal is removed, the volatilization of the platinum group metal does not occur. It is also believed that volatilization of the platinum group metal can be reduced by reducing the inner wall contact area of the platinum group metal in contact with the atmosphere of the vapor phase space. However, even when the inner wall contact area of the platinum group metal in contact with the atmosphere of the gas phase space is made small, the platinum group metal can not sufficiently reduce volatilization from the wall surface.

Accordingly, it is an object of the present invention to provide a process for producing a glass substrate, which is capable of suppressing the volatilization of the platinum group metal from the inner wall constituted of the platinum group metal when the molten glass is processed in a molten glass processing apparatus composed of a material containing at least a platinum group metal, It is another object of the present invention to provide a method of manufacturing a glass substrate, an apparatus for manufacturing a glass substrate, and an apparatus for processing a molten glass, wherein a part of agglomerates of platinum metal volatilized in the vapor phase space can be prevented from being mixed into molten glass .

The present invention has the following aspects.

(Form 1)

A melting step of melting a glass raw material to produce a molten glass;

A molten glass processing apparatus composed of a material having a liquid phase of the molten glass and at least a part of the inner wall surrounding the gas phase being made of a material containing a platinum group metal, And a processing step of,

The ratio of the area of the platinum group metal on the inner wall contacting the vapor phase space to the volume of the vapor phase space is controlled so as to reduce the volatilization of the platinum group metal in the molten glass processing apparatus. Wherein the glass substrate is a glass substrate.

(Form 2)

And controlling the liquid level of the molten glass to control the ratio.

(Form 3)

A correlation between the number of platinum defects in advance and the level of the liquid surface of the molten glass in the molten glass processing apparatus is determined in advance and the level of the liquid surface of the molten glass processing apparatus corresponding to the tolerance of the number of platinum defects is determined as the reference liquid level, And the liquid level is controlled based on the reference liquid level in the processing step.

(Mode 4)

A method of manufacturing a glass substrate,

A melting step of melting a glass raw material to produce a molten glass;

1. A molten glass treatment apparatus comprising a vapor phase space formed by a liquid surface and an inner wall of a molten glass and a liquid phase of the molten glass and at least a part of an inner wall surrounding the vapor phase is made of a material containing a platinum group metal, A processing step of processing the substrate,

And a molding step of molding the molten glass processed in the processing step into a sheet glass,

A correlation between the number of platinum defects in advance and the level of the liquid level of the molten glass processing apparatus is determined in advance and the level of the liquid level of the molten glass processing apparatus corresponding to the allowable value of the number of platinum defects is determined as the reference level level, Wherein the level of the liquid level is controlled based on the reference liquid level.

(Mode 5)

Wherein the liquid level is controlled based on a target liquid level range determined to include the reference liquid level in the processing step.

(Form 6)

Wherein the level of the liquid level is controlled by controlling at least one of an amount of the molten glass supplied to the molten glass processing apparatus and a molding amount of the sheet glass to be molded in the molding step, / RTI >

(Form 7)

Wherein the volume of the vapor space is S [m 3] and the area of the platinum group metal in contact with the vapor space is L [m 2], the ratio S / L is 17 [m] Wherein the glass substrate is a glass substrate. At this time, it is sufficient that the molten glass occupies 50% or more of the entire space in the vapor phase space.

(Form 8)

The ratio

(1) the oxygen concentration in the vapor phase space,

(2) the maximum temperature of the inner wall of the molten glass processing apparatus,

(3) an amount of oxygen released from the molten glass to the vapor phase space,

(4) a temperature difference between the maximum temperature of the molten glass in the dissolution step and the maximum temperature of the molten glass in the processing step, and

(5) the vapor pressure of the platinum group metal in the vapor phase space

Of the glass substrate is a value determined on the basis of at least one of the following formulas (1) to (7).

(Mode 9)

Wherein the oxygen concentration in the vapor phase is controlled by the content of tin oxide contained in the molten glass.

(Mode 10)

Wherein the temperature difference between the maximum temperature and the minimum temperature of the platinum group metal portion of the inner wall contacting the vapor space is 50 DEG C or more.

(Mode 11)

10. The method of manufacturing a glass substrate according to any one of modes 1 to 10, wherein the molten glass processing apparatus is a refining apparatus for refining the molten glass.

(Form 12)

The method of manufacturing a glass substrate according to any one of modes 1 to 11, wherein the processing is a fining process of the molten glass, and oxygen is released from the molten glass to the vapor phase space.

(Form 13)

The method for producing a glass substrate according to any one of Forms 1 to 12, wherein the molten glass flows in the liquid phase, and a temperature distribution is formed in the inner wall along the flow direction of the molten glass.

(Form 14)

The method for producing a glass substrate according to any one of the above-mentioned 13 to 13, wherein the glass substrate is a glass substrate for display.

(Form 15)

A method of manufacturing a glass substrate,

A melting step of melting a glass raw material to produce a molten glass;

A molten glass processing apparatus composed of a material having a liquid phase of the molten glass and at least a part of the inner wall surrounding the gas phase being made of a material containing a platinum group metal, And a processing step of,

The ratio of the area of the platinum group metal on the inner wall contacting with the vapor phase space to the volume of the vapor phase space is adjusted so as to reduce the volatilization of the platinum group metal in the molten glass processing apparatus. Wherein the glass substrate is a glass substrate.

(Form 16)

A method of manufacturing a glass substrate,

A melting step of melting a glass raw material to produce a molten glass;

1. A molten glass treatment apparatus comprising a vapor phase space formed by a liquid surface and an inner wall of a molten glass and a liquid phase of the molten glass and at least a part of an inner wall surrounding the vapor phase is made of a material containing a platinum group metal, A processing step of processing the substrate,

And a molding step of molding the molten glass processed in the processing step into a sheet glass,

A correlation between the number of platinum defects in advance and the level of the liquid level of the molten glass processing apparatus is determined in advance and the level of the liquid level of the molten glass processing apparatus corresponding to the allowable value of the number of platinum defects is determined as the reference level level, Wherein the level of the liquid level is adjusted based on the reference liquid level.

(Mode 17)

And the oxygen concentration in the vapor phase space is 1% or less.

(Form 18)

And the content of tin oxide in the glass substrate is 0.01 to 0.3 mol%.

(Form 19)

1. A molten glass processing apparatus comprising a vapor phase space formed by a liquid surface and an inner wall of a molten glass and a liquid phase of molten glass and at least a part of an inner wall surrounding the vapor phase comprises a platinum group metal,

And a control section for controlling a ratio of an area of the platinum group metal in the wall contacting the vapor space to a volume of the vapor space so as to reduce the volatilization of the platinum group metal in the vapor space. Device.

(Form 20)

1. A molten glass processing apparatus comprising a vapor phase space formed by a liquid surface and an inner wall of a molten glass and a liquid phase of molten glass and at least a part of an inner wall surrounding the vapor phase comprises a platinum group metal,

And an adjusting section for adjusting a ratio of an area of the platinum group metal of the wall in contact with the vapor space to a volume of the vapor space so as to reduce volatilization of the platinum group metal in the vapor space, Device.

(Form 21)

1. A molten glass processing apparatus comprising a vapor phase space formed by a liquid surface and an inner wall of a molten glass and a liquid phase of molten glass and at least a part of an inner wall surrounding the vapor phase comprises a platinum group metal,

And a control unit for controlling the liquid level of the molten glass processing apparatus to be a predetermined reference liquid level,

The control unit determines the reference liquid level as the liquid level of the glass melt processing apparatus corresponding to the allowable value of the number of platinum defects based on the correlation between the number of platinum defects obtained in advance and the liquid level of the glass melt processing apparatus Wherein the molten glass is a molten glass.

(Form 22)

1. A molten glass processing apparatus comprising a vapor phase space formed by a liquid surface and an inner wall of a molten glass and a liquid phase of molten glass and at least a part of an inner wall surrounding the vapor phase comprises a platinum group metal,

And an adjusting unit that adjusts the liquid level of the molten glass processing apparatus to a predetermined reference liquid level,

The adjusting section determines the reference liquid level as the liquid level of the molten glass processing apparatus corresponding to the allowable value of the number of platinum defects based on the correlation between the number of platinum defects obtained in advance and the level of the liquid level of the glass melt processing apparatus Wherein the molten glass is a molten glass.

(Form 23)

A glass substrate manufacturing apparatus comprising:

A melting apparatus for melting glass raw materials to produce molten glass,

A vapor phase space formed by the liquid surface and the inner wall of the molten glass; a molten glass treatment for treating the molten glass, wherein the molten glass has a liquid phase and at least a part of the inner wall surrounding the vapor phase is made of a material containing a platinum group metal [0001]

A molding apparatus for molding the molten glass processed in the molten glass processing apparatus into a sheet glass,

And a control section for controlling the ratio of the area of the platinum group metal on the inner wall contacting the vapor space to the volume of the vapor space so as to reduce volatilization of the platinum group metal of the molten glass processing apparatus Substrate manufacturing apparatus.

(Form 24)

A glass substrate manufacturing apparatus comprising:

A melting apparatus for melting glass raw materials to produce molten glass,

A vapor phase space formed by the liquid surface and the inner wall of the molten glass; a molten glass treatment for treating the molten glass, wherein the molten glass has a liquid phase and at least a part of the inner wall surrounding the vapor phase is made of a material containing a platinum group metal [0001]

A molding apparatus for molding the molten glass processed in the molten glass processing apparatus into a sheet glass,

And an adjusting section for adjusting a ratio of an area of the platinum group metal on the inner wall contacting the vapor phase space to a volume of the vapor phase space so as to reduce volatilization of the platinum group metal in the molten glass processing apparatus Substrate manufacturing apparatus.

(Form 25)

A glass substrate manufacturing apparatus comprising:

A melting apparatus for melting glass raw materials to produce molten glass,

A vapor phase space formed by the liquid surface and the inner wall of the molten glass; a molten glass treatment for treating the molten glass, wherein the molten glass has a liquid phase and at least a part of the inner wall surrounding the vapor phase is made of a material containing a platinum group metal [0001]

A molding apparatus for molding the molten glass processed in the molten glass processing apparatus into a sheet glass,

And a control unit for controlling the liquid level of the molten glass processing apparatus to be a predetermined reference liquid level,

The control unit determines the reference liquid level as the liquid level of the glass melt processing apparatus corresponding to the allowable value of the number of platinum defects based on the correlation between the number of platinum defects obtained in advance and the liquid level of the glass melt processing apparatus Wherein the glass substrate is a glass substrate.

(Form 26)

A glass substrate manufacturing apparatus comprising:

A melting apparatus for melting glass raw materials to produce molten glass,

A vapor phase space formed by the liquid surface and the inner wall of the molten glass; a molten glass treatment for treating the molten glass, wherein the molten glass has a liquid phase and at least a part of the inner wall surrounding the vapor phase is made of a material containing a platinum group metal [0001]

A molding apparatus for molding the molten glass processed in the molten glass processing apparatus into a sheet glass,

Wherein the molten glass processing apparatus is provided with an adjusting section for adjusting the liquid level of the molten glass processing apparatus to a predetermined reference liquid level,

The adjusting section determines the reference liquid level as the liquid level of the molten glass processing apparatus corresponding to the allowable value of the number of platinum defects based on the correlation between the number of platinum defects obtained in advance and the level of the liquid level of the glass melt processing apparatus Wherein the glass substrate is a glass substrate.

According to the glass substrate manufacturing method, the glass substrate manufacturing apparatus, and the molten glass processing apparatus described above, volatilization of the platinum group metal can be suppressed, and a part of the platinum metal agglomerates volatilized in the vapor phase space becomes foreign matter, Can be suppressed.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a view showing an example of a process of a manufacturing method of a glass substrate of the present embodiment. FIG.
Fig. 2 is a diagram schematically showing an example of a device for performing a dissolving process or a cutting process in the present embodiment.
3 (a) and 3 (b) are views for explaining the flow of the airflow in the vapor phase space of the clarifying apparatus and the liquid level of the clarifying apparatus of the present embodiment.
Figs. 4 (a) and 4 (b) are views for explaining variations in the level of the molten glass in the clarifying apparatus. Fig.
Fig. 5 is a diagram for explaining the line and target level levels used in the present embodiment. Fig.
6 is a diagram showing the relationship between the ratio S / L and the defect density used in the present embodiment.

Hereinafter, a method of manufacturing a glass substrate, a manufacturing apparatus of a glass substrate, and a molten glass processing apparatus according to the present embodiment will be described. Fig. 1 is a view showing an example of the process steps of the glass substrate manufacturing method according to the present embodiment.

Platinum or platinum alloys described later are platinum group metals and include platinum, ruthenium, rhodium, palladium, osmium, iridium, and alloys of these metals.

Further, the foreign substance (platinum defect) of the plated or platinum alloy which is agglomerated is a linear substance which is elongated in one direction. The maximum length of the platinum defect refers to the length of the longest side of the circumscribed rectangle circumscribing the image of the foreign object when the foreign substance (aggregate) of the platinum group metal is imaged. The minimum length of the platinum defect refers to the length of the shortest side of the circumscribed rectangle circumscribing the foreign object on the image of the foreign substance (aggregate) of the platinum group metal. The platinum defect refers to a foreign substance of a platinum group metal having an aspect ratio of 100 or more that is the ratio of the maximum length to the minimum length. For example, the maximum length of the foreign substance (agglomerate) of the platinum group metal is 50 탆 to 300 탆, and the minimum length is 0.5 탆 to 2 탆.

The control in this specification includes adjustment. The adjustment includes at least an adjustment for changing the temperature, a flow rate, a concentration, a pressure, and the like of the object through the apparatus by an operator's input operation and a manual adjustment by the operator.

The glass substrate manufacturing method mainly has a melting step (ST1), a refining step (ST2), a homogenizing step (ST3), a molding step (ST4), a slow cooling step (ST5) and a cutting step (ST6).

The dissolving step (ST1) is carried out in the dissolving tank. In the melting step, molten glass is produced by injecting a glass raw material into the melt surface of the molten glass accumulated in the melting tank. It is preferable that the glass raw material is added with a refining agent. As for the fining agent, tin oxide is suitably used from the viewpoint of environmental load reduction.

The cleaning step ST2 is performed inside a cleaning tube of a cleaning device composed of platinum or a platinum alloy or the like. In the refining step, the molten glass in the tube of the refining apparatus is heated. In this process, the refining agent releases oxygen by a reduction reaction, and later becomes a substance acting as a reducing agent. The bubbles containing O ₂ , CO ₂ or SO ₂ contained in the molten glass are combined with O ₂ generated by the reduction reaction of the fining agent, become bulky, float on the surface of the molten glass, The gas contained in the bubbles is discharged to the outside air through a vapor space provided in the purifying device.

Thereafter, in the refining step, the temperature of the molten glass is lowered. In this process, the reducing agent obtained by the reduction reaction of the fining agent performs the oxidation reaction. As a result, gas components such as O ₂ in the bubbles remaining in the molten glass are dissolved in the molten glass, so that the bubbles disappear.

In the homogenization step (ST3), the molten glass in the stirring apparatus supplied through the pipe extending from the refining apparatus is agitated using a stirrer to homogenize the molten glass. The homogenization step (ST3) may be performed before the fining step.

In the molding apparatus, the molding step (ST4) and the slow cooling step (ST5) are performed.

In the molding step (ST4), the molten glass is formed into a sheet glass, and a flow of the sheet glass is made. For the molding, an overflow down-draw method or a float method can be used. In the present embodiment to be described later, an example in which an overflow down-draw method is used will be described.

In the slow cooling step (ST5), the formed sheet glass is cooled to a desired thickness so that internal deformation does not occur and no warping occurs.

In the cutting step (ST6), in the cutting apparatus, the sheet glass supplied from the molding apparatus is cut to a predetermined length to obtain a plate-like glass plate. The cut glass plate is further cut to a predetermined size to produce a glass substrate having a target size.

In the glass substrate manufacturing method of the present embodiment, the following methods are applied to the apparatus used for the clarifying step or the homogenizing step.

That is, the molten glass is passed through a molten glass processing apparatus for processing the molten glass, before the molten glass is formed into the sheet glass, after the dissolving step of dissolving the glass raw material to produce the molten glass. The treatment apparatus includes a metal tube or bath having an inner wall containing platinum or a platinum alloy or the like. The tube or bath has a liquid phase of the molten glass, a vapor phase space formed by the liquid surface and the inner wall of the molten glass, and the inner wall surrounding the vapor phase space is made of a material containing a platinum group metal. In this molten glass treatment apparatus, the ratio of the area of the platinum group metal on the inner wall of the molten glass treatment apparatus in contact with the vapor phase space to the volume of the vapor phase space, or the ratio of the volume of the vapor phase space in contact with the vapor phase space, The level of the molten glass in the molten glass processing apparatus is controlled (adjusted). By appropriately controlling (adjusting) the ratio or the level of the liquid level, the volatilization of the platinum group metal can be suppressed from the inner wall of the molten glass processing apparatus. This point will be described later. Such a processing apparatus for molten glass is applied to a device used in a process between a dissolving process and a forming process. It is applied to the apparatus used in the process between the fining process and the homogenization process. For example, the present invention is applied to a refining apparatus that performs a refining process and an agitating apparatus that performs a homogenization process. Hereinafter, this embodiment will be described in a form applied to a clarifying apparatus as a representative.

Fig. 2 is a diagram schematically showing an example of a glass substrate producing apparatus for performing the dissolving step (ST1) to cutting step (ST6) in the present embodiment. As shown in Fig. 2, this apparatus mainly has a molten glass producing apparatus 100, a molding apparatus 200, and a cutting apparatus 300. [ The molten glass producing apparatus 100 has a melting apparatus 101, a clarifying apparatus 102, a stirring apparatus 103 and a glass supply pipe 104, 105 and 106.

The dissolution apparatus 101 of the example shown in Fig. 2 dissolves a glass raw material to make a molten glass. The clarifying apparatus 102 includes a purifying pipe 102a (see FIG. 3) including platinum or a platinum alloy or the like. A current flows between the electrode plates provided on the cleaning apparatus 102 while the molten glass MG passes through the cleaning tube 102a while the vapor space is formed so that the molten glass MG has the liquid surface, To heat the molten glass MG to release the bubbles into the vapor phase space. In the present embodiment, a method of energizing the cleaning tube 102a for defoaming the molten glass is used, but heating of the cleaning tube 102a is not limited to energization heating. For example, a method in which a heat source such as a heater is provided around the tube and the cleaning tube 102a is indirectly heated by heat conduction or heat radiation may be used.

The stirring apparatus 103 stirs and homogenizes the molten glass MG by an agitator 103a.

The molding apparatus 200 includes a molded body 210 and the molten glass MG processed by the clarifying apparatus 102 and the stirring apparatus 103 is formed by the overflow down draw method using the molded body 210 Sheet glass (SG). Further, in the molding apparatus 200, the sheet glass SG is slowly cooled so that the sheet thickness deviation, deformation and warpage do not occur in the sheet glass SG.

The cutting device 300 cuts the cold sheet glass SG to form a glass substrate.

(Clarification process and clarification device)

3 (a) and 3 (b) are views for explaining the flow of the airflow in the vapor phase space in the cleaning apparatus 102 and the liquid level of the cleaning apparatus 102 of the present embodiment. Fig. 3 (a) shows a case where the airflow W1 generated in the vapor phase space is fast, and Fig. 3 (b) shows a case where the velocity of the airflow W2 generated in the vapor phase space is slow.

The refining process includes defoaming treatment and absorption treatment. In the following description, tin oxide is used as a fining agent. Although tin oxide has a lower refining ability than that of abiic acid generally used in the past, it can be suitably used as a refining agent in view of low environmental load. However, tin oxide has a lower refining function than that of avic acid, and therefore, when tin oxide is used, the temperature of the molten glass (MG) in the refining process of the molten glass (MG) must be higher than the conventional one. In this case, for example, the maximum temperature of the molten glass in the refining step is, for example, 1630 캜 to 1720 캜, preferably 1670 캜 to 1710 캜.

The molten glass MG dissolved in the melting apparatus 101 is introduced into the clarifying apparatus 102 by the glass supply pipe 104 (see Fig. 2).

3 (a) and 3 (b), the purifying device 102 includes a long purifying purifying pipe 102a including platinum or a platinum alloy, and is provided with a purifying pipe 102a disposed at the top of the purifying pipe 102a, (102b).

The purifying pipe 102a is connected to the glass pipe 104 extending from the melting tank 101 to the wall surface at one end of the purifying pipe 102a and the glass pipe 105 . Therefore, the molten glass MG flowing in the substantially horizontal direction from one wall surface of the purifying pipe 102a is refined when flowing toward the other wall surface, and flows out in a substantially horizontal direction from the other wall surface. Therefore, since the cleaning tube 102a is located at a high level of the liquid level of the molten glass of the melting apparatus 101, the vertical glass supply pipe and the vertical glass discharge pipe, which are connected to the purifying pipe, Pressure defoaming device.

The pressure of the vapor phase space in the purifying tube 102a is equal to or slightly higher than the atmospheric pressure due to the release of gas due to defoaming or the like. As described later, the vent pipe 107 is connected to the exhaust pump to lower the atmospheric pressure than the atmospheric pressure. In this case, the difference between the atmospheric pressure and the atmospheric pressure in the vapor phase space is larger than 0 Pa and less than 10 Pa.

Specifically, the cleaning tube 102a of the cleaning apparatus 102 has a vapor phase formed by the liquid phase of the molten glass MG, the liquid surface of the molten glass MG, and the inner wall of the cleaning apparatus 102a. The inner wall of the clarifying apparatus 102 surrounding the vapor space is made of a material such as platinum or a platinum alloy. Since the gas emitted from the molten glass MG or the gas such as platinum or platinum alloy volatilized from the inner wall of the purifying pipe 102a is present in the vaporizing space of the purifying pipe 102a, The pressure in the gas-phase space is higher than the atmospheric pressure. As a result, air flows W1 and W2 that flow from the gas-phase space to the atmosphere through the vent pipe 107 are formed.

In this cleaning tube 102a, the area L [m2] of the platinum group metal on the inner wall of the cleaning tube 102a in contact with the vapor space and the volume S [V] of the vapor space in order to reduce volatilization of platinum or platinum alloy in the vapor space, M3] is controlled or adjusted. Alternatively, the liquid level of the molten glass is controlled or adjusted so as to reduce volatilization of platinum or platinum alloy or the like in the vapor phase space.

As described above, the air flows W1 and W2 toward the vent pipe 107 flow in the vapor phase space. As shown in Fig. 3 (a), in the case of the airflow W1 having a high flow velocity, volatiles such as platinum or platinum alloy contained in the vapor phase space are quickly discharged. Therefore, the partial pressure of the platinum or platinum alloy is lower than the saturated vapor pressure and the amount of the platinum or the platinum alloy is reduced from the portion of the inner wall in contact with the vapor space of the cleaning tube 102a, because the concentration of volatiles such as platinum or platinum alloy in the vapor- The volatilization of the alloy or the like continues. Conversely, as shown in Fig. 3 (b), in the case of the air flow W2 with a slow flow rate, the discharge of volatiles such as platinum or platinum alloy contained in the vapor phase is delayed. Therefore, the vapor pressure of volatiles such as platinum or platinum alloy in the vapor phase tends to reach a saturated vapor pressure, and the volatilization of platinum or platinum alloy or the like is suppressed from the portion of the inner wall contacting the vapor phase space of the purifying tube 102a.

Therefore, in order to suppress the volatilization of platinum or platinum alloy into the vapor phase space, the flow velocity of the airflow may be lowered. In order to reduce the flow rate of the airflow, it is preferable to increase the volume of the vapor phase space and reduce the air pressure difference between the vapor phase space and the atmosphere. When the volume of the vapor phase space in the purifying tube 102a is increased, the level of the molten glass MG is lowered to reduce the amount of the purifying glass 102a flowing per unit time of the purifying tube 102a. The amount of gas discharged from the glass (MG) by defoaming is reduced. As a result, the pressure difference between the gas-phase space and the atmosphere becomes smaller, and the flow rate of the airflow is lowered.

On the other hand, in order to reduce the absolute amount of volatilization of platinum or platinum alloy on the inner wall in contact with the vapor space, the area of the inner wall made of platinum or platinum alloy in contact with the vapor space may be reduced.

Therefore, in order to suppress the volatilization of platinum or platinum alloy or the like, it is preferable to increase the volume of the above-mentioned vapor phase space and reduce the area of the inner wall constituted of platinum or platinum alloy and the like in contact with the vapor phase space.

In order to suppress the volatilization of platinum or platinum alloy, it is also preferable to control or adjust the liquid level of the molten glass (MG) such that the level of the liquid surface is controlled so as to suppress the volatilization of platinum or platinum alloy.

Hereinafter, the adjustment of the volume and the inner wall area of the vapor phase space and the adjustment of the level of the liquid level will be described.

(Control and adjustment of the volume and inner wall area of the meteorological space)

In view of the above, in the present embodiment, in order to reduce volatilization of platinum or platinum alloy in the vapor phase space, the area L [m2] of the platinum group metal on the inner wall of the cleaning tube 102a contacting the vapor phase space and the volume S [M < 3 >] is controlled or adjusted. This suppresses the volatilization of the platinum group metal from the inner wall made of the platinum group metal, so that a part of the platinum metal agglomerates volatilized in the vapor phase space can be prevented from being mixed into the molten glass (MG) by becoming a foreign matter (platinum defect) . Hereinafter, the control is mainly described, but the adjustment is applied in the same manner as the control.

Regarding the control (adjustment) of the ratio S / L, it is preferable to control (adjust) the level of the liquid level of the molten glass MG of the cleaning tube 102a when the glass substrate is continuously produced. For example, in the molding apparatus 200, since the sheet glass formed from the molten glass MG is slowly cooled while being stretched on the conveying roller (not shown), the amount of the molten glass MG in the cleaning tube 102a is controlled, The level of the liquid level of the molten glass MG in the pipe 102a can be controlled (adjusted). As a method of controlling the amount of the molten glass MG in the purifying pipe 102a, for example, the amount of the glass raw material for forming the molten glass MG is adjusted in the melting apparatus 101, The temperature of the molten glass MG is adjusted by adjusting the introduction amount of the glass or the temperature of the molten glass MG when the molten glass MG moves from the melting apparatus 101 to the purifying pipe 102a, The amount of molten glass introduced into the purifying pipe 102a may be adjusted by changing the moving speed of the glass MG or by adjusting the flow rate of the molten glass MG between the melting device 100 and the purifying pipe 102a Adjusting the amount of molten glass introduced into the purifying pipe 102a by adjusting the amount of the molten glass flowing out of the purifying pipe 102a by adjusting the throughput by the molding device 200 . As described above, the screw feeder 101d for changing the amount of the glass raw material, the temperature adjusting device, the flow rate controlling part, and the throughput adjusting instruction device for adjusting the throughput of the molding device 200, (Control unit) for controlling the operation of the apparatus.

In the case of controlling (adjusting) the level of the liquid level in the purifying pipe 102a of the molten glass MG, when the level of the liquid level is increased, the volume S and the area L are simultaneously reduced. Thereby, a preferable range for the ratio S / L is set.

It is preferable that the ratio S / L is set to 17 [m] or more from the viewpoint of reducing volatilization of platinum or platinum alloy in the gas phase space, and more preferably 25 [m] or more. However, if the ratio S / L is excessively large, the amount of molten glass flowing through the cleaning tube 102a is small, which is not preferable from the viewpoint of production efficiency of the glass substrate. When the level of the liquid level in the cleaning tube 102a is lower than the uppermost level of the glass tube 105, an airflow is generated from the glass tube 105 toward the cleaning tube 102a to increase the airflow velocity in the cleaning tube 102a . Therefore, it is preferable that the lower limit of the liquid level is higher than the uppermost portion of the glass supply pipe 105. From the above, it is preferable that the ratio S / L is 17 to 65 [m]. That is, the ratio S / L is preferably set in the range of 17 to 65 [m] in the case of the cleaning tube 102a, and more preferably in the range of 25 to 65 [m]. This numerical value range of the ratio S / L is realized in a purifying tube whose cross section is circular or elliptical.

The flow velocity of the airflow is preferably in the range of 5 m / min or less, more preferably 1 m / min or less, still more preferably 0.5 m / min or less.

The level of the molten glass MG in the cleaning tube 102a can be adjusted by adjusting the level of the molten glass MG in the cleaning tube 102a when the impact of the glass raw material in the melting apparatus 100 is transmitted or when the rotating vibration of the agitator 103a So that it may fluctuate. 4 (a) and 4 (b) are views for explaining the level fluctuation of the level of the molten glass in the cleaning tube 102a. It is premised that the molten glass MG occupies 50% or more of the entire space inside the purifying pipe 102a in the purifying pipe 102a. As shown in Fig. 4 (a), when the molten glass MG occupies about 70% of the entire space inside the cleaning tube 102a whose cross section is a circular tube shape, As shown in Fig. 4 (b), the fluctuation is larger than the case where the molten glass MG occupies about 55% of the entire space inside the cleaning tube 102a. In the case shown in Fig. 4 (a), a large part of the aggregate such as platinum or platinum alloy adhering to the inner wall is easily separated and mixed into the molten glass MG due to a large fluctuation of the liquid level. In this respect, it is preferable that the ratio of the molten glass MG in the cleaning tube 102a to the entire space inside the cleaning tube 102a of the vapor phase space is smaller. In consideration of this point, the ratio S / L is controlled (adjusted) to an appropriate numerical value range.

In the case where the ratio S / L is controlled (adjusted) to the level of the molten glass MG of the cleaning tube 102a, as described later, the number of platinum defects and the level of the molten glass in the molten glass treatment apparatus And the liquid level of the molten glass processing apparatus corresponding to the allowable value of the number of platinum defects is determined as the reference liquid level. In the processing such as the clarification process, the liquid level is controlled based on the reference liquid level ). Further, at this time, in the processing step, it is preferable to control (adjust) the level of the liquid level based on the target liquid level range range determined to include the reference liquid level. It is preferable that the liquid level is controlled (adjusted) by controlling or adjusting at least one of the amount of the molten glass to be supplied to the molten glass processing apparatus and the amount of molding of the sheet glass to be molded in the molding step.

In the case of controlling (adjusting) the above-mentioned S / L in the case of continuous production of the glass substrate, foreign matter as a coagulation product of platinum or platinum metal (platinum Defects) are detected, and it is preferable to control (adjust) the ratio S / L according to the result of detection of the number of foreign objects. In the defect inspection, defects such as a plurality of kinds of foreign matters are identified, and the aggregates such as platinum or platinum metal have a unique shape with respect to other foreign matters or defect shapes, so that they can be easily identified.

(Level control, adjustment)

From the above-described point of view, it is also possible in the present embodiment to control (adjust) the level of the molten glass in the cleaning tube 102a so as to suppress the volatilization of the platinum group metal. Hereinafter, the control is mainly described, but the adjustment is applied in the same manner as the control.

The level of the molten glass MG in the purifying pipe 102a can be controlled by adjusting the amount of molten glass MG supplied to or discharged from the purifying pipe 102a. For example, in the molding apparatus 200, since the sheet glass is usually formed from the molten glass MG per unit time supplied from the molten glass producing apparatus 100, the molten glass MG introduced into the purifying pipe 102a The level of the molten glass MG in the cleaning tube 102a can be controlled (adjusted). Examples of the method for adjusting the amount of the molten glass MG introduced (supplied) into the cleaning tube 102a include adjusting the amount of the glass raw material for forming the molten glass MG in the dissolution apparatus 101, When the molten glass MG moves from the melting apparatus 101 to the purifying tube 102a, the temperature of the molten glass MG is adjusted by using a temperature adjusting apparatus to change the viscosity so that the moving speed of the molten glass MG And a flow control unit for reducing the flow rate of the molten glass MG is provided between the melting apparatus 100 and the purifying pipe 102a. As described above, the raw material feeding device 101d for changing the amount of the glass raw material, the temperature adjusting device, and the flow rate controlling part can be a control part (adjusting part) for controlling (adjusting) the liquid level of the molten glass MG. The level of the molten glass in the cleaning tube 102a can also be controlled (adjusted) by adjusting the molding amount (throughput) of the sheet glass by the molding apparatus 200. [ Alternatively, the level of the molten glass in the cleaning tube 102a can be controlled (adjusted) by adjusting the molten glass MG supplied to the molding apparatus 200 from the inside of the cleaning tube 102a. Examples of the method for adjusting the molding amount (processing amount) of the sheet glass by the molding apparatus 200 include, for example, the speed control of the conveying roller to convey the sheet glass, the sheet thickness control of the sheet glass, and the like. On the other hand, as a method for controlling the amount of molten glass (MG) supplied from the purifying tube 102a to the molding apparatus 200, when the molten glass MG moves from the purifying tube 102a to the molding apparatus 200 The moving speed of the molten glass MG is changed by adjusting the temperature of the molten glass MG by using a temperature adjusting device or by changing the viscosity of the molten glass MG or changing the moving speed of the molten glass MG between the cleaning tube 102a and the molding machine 200 And a flow control unit for reducing the flow rate of the gas MG. As described above, the speed adjusting device, the temperature adjusting device, and the flow rate controlling part of the conveying roller can be a control part (adjusting part) for adjusting the liquid surface level of the molten glass MG.

It is preferable to perform at least one of the adjustment of the amount of the glass raw material and the adjustment of the molding amount of the sheet glass by the molding apparatus 200 among the control portion (adjusting portion) described above.

In the present embodiment, the level of the molten glass MG can be measured using a liquid level measuring apparatus provided in the purifying apparatus 102, for example. Further, the purifying tube 102a exhibits substantially the same value in any portion in the longitudinal direction. Therefore, the liquid level may be controlled (adjusted) by paying attention to any part of the cleaning tube 102a.

It is preferable that the control (adjustment) of the level of the liquid level is performed at the predetermined reference liquid level or the target liquid level at the cleaning tube 102a. The reference level of the reference level is a level that the level of the molten glass (MG) can take in the cleaning tube (102a). In addition, the target liquid level is a range of the liquid level of the molten glass MG in the purifying pipe 102a. The reference liquid level and the target liquid level are obtained by the fact that a part of the agglomerates such as platinum or platinum alloy volatilized in the vapor phase space becomes a foreign matter and is mixed with the molten glass to become defects (hereinafter also referred to as platinum defects) in the glass substrate From the point of view of restraint. In addition, the target liquid level is also determined from the viewpoint of not lowering the productivity of the glass substrate.

In order to determine the reference liquid level or the target liquid level A, the correlation between the liquid level of the molten glass (MG) and the number of platinum defects is obtained before starting the production of the glass substrate. The reference liquid level is the liquid level of the cleaning tube 102a corresponding to the allowable value of the number of platinum defects and based on the correlation between the liquid level of the molten glass MG in the cleaning tube 102a and the number of platinum defects . The target face level is determined to include the reference face level.

Referring to Fig. 5, the line S and the target level level will be described. The line S shows the correlation between the level of the liquid surface of the molten glass MG and the number of platinum defects as shown in Fig. The liquid level is indicated by the distance (mm) between the liquid surface of the molten glass MG and the upper end of the vapor phase space (the ceiling portion of the inner wall) in the direction orthogonal to the liquid surface.

The correlation between the level of the liquid surface of the molten glass (MG) and the number of platinum defects is determined by the height (liquid level) of the liquid surface in the middle refining step such as manufacturing conditions and measurement items used in the past, And the like, based on the number of platinum defects among the inspection results made on the glass substrate manufactured using the above-described method. At the time of making the correlation, it is considered that these two parameters, that is, conditions other than the liquid level and the number of platinum defects are constant. Other conditions include the size of the clarifying device 102, the temperature of the molten glass MG in the purifying pipe 102a, the temperature of the purifying pipe 102a, the type of the constituent material of the purifying pipe 102a, The introduction of the inert gas, the introduction amount of the inert gas, the content of the refining agent of the molten glass (MG), and the like.

It can be seen that the larger the value of the liquid surface level (the liquid surface height is lower), the smaller the number of platinum defects. This is because, as described above, the airflow velocity in the purifying pipe 102a is slowed and the volatilization of the platinum or platinum alloy of the purifying pipe 102a is suppressed, as described above, This is because the number is decreasing.

The target liquid level A is represented by a range of the liquid level as shown (the shaded portion in the figure). The target liquid level A is created based on the line S. The lower limit value of the target liquid level A is defined as the reference liquid level at the intersection of the line S and the quality reference line Q shown in Fig. The quality reference line (Q) is the allowable value of the number of platinum defects. The quality reference line Q is determined by a quality specification required by a customer who is a purchaser of a glass substrate, for example, and indicates a predetermined number of platinum defects. The specific number of platinum defects is not particularly limited and may be determined in various ways. For example, the number of platinum defects can be set between 0.001 and 0.1 pcs / kg. In Fig. 5, in the region on the left side from the quality reference line Q (tolerance of the number of platinum defects), it is judged that the manufactured glass substrate is good, and the region on the right side is judged as a defective product. The liquid surface level is controlled (adjusted) so that the liquid surface level becomes larger than the lower limit value (the liquid surface height is located lower than the current liquid surface level), so that the number of platinum defects contained in the glass substrate to be produced is always lower than the predetermined value .

On the other hand, the upper limit value of the target liquid level A is determined from the viewpoint of not lowering the productivity of the glass substrate. When the liquid level of the molten glass MG is increased, the volume of the vapor phase space is increased and the volatilization of platinum or platinum alloy is suppressed. On the other hand, as the volume of the vapor phase space is increased, ) Is reduced, and when the amount is large, the productivity of the glass substrate is lowered. From this point of view, the upper limit value of the target liquid level A is determined. The setting of the upper limit value of the target liquid level A is not necessarily required, but is preferably set.

Further, the upper limit value of the target liquid level A may be determined based on the height position of the glass supply pipe 105 connected to the cleaning tube 102a. For example, when the liquid level of the cleaning tube 102a is lower than the top of the glass tube 105, an airflow is generated from the glass tube 105 toward the cleaning tube 102a, The flow rate of the gas is increased. That is, it is difficult to suppress the volatilization of platinum or platinum alloy of the cleaning tube 102a. Therefore, it is preferable that the upper limit value of the target liquid level A is set to be smaller than the liquid level corresponding to the height position of the uppermost portion of the glass supply pipe 105.

The level of the liquid level of the molten glass MG in the cleaning tube 102a is controlled (adjusted) so that the target liquid level is equal to or higher than the target liquid level so that the productivity of the glass substrate can be suppressed from decreasing. Further, by controlling (adjusting) the liquid surface level of the molten glass MG to the target liquid surface level determined as described above, even if the specification required by the customer becomes strict, for example, A glass substrate that meets the specification can be manufactured. In this case, on the paper surface of Fig. 5, the quality reference line Q is set to the left side with respect to the reference line Q shown in Fig. Then, it can be seen that the point of intersection with the line S moves upward with respect to the current intersection point shown in FIG. 5, and it is necessary to make the level of the liquid level large (lower the liquid level).

In the method of the present embodiment, the object to be controlled (adjusted) is the liquid level of the molten glass MG, but the liquid level control (adjustment) may also control (adjust) the volume of the vapor phase space. As described above, in order to suppress the volatilization of platinum or platinum alloy into the gas phase space, the flow velocity of the gas flow can be lowered and the volume of the gas phase space can be increased to lower the flow velocity of the gas flow.

It is preferable that the above-mentioned line and target liquid level are prepared for each of the above-mentioned other conditions. By preparing a plurality of such films, the glass substrate closest to the manufacturing conditions to be performed is selected before starting the production of the glass substrate, and the liquid surface is controlled (adjusted) according to the selected line and target liquid level, It is possible to suppress the volatilization of platinum or platinum alloy or the like and to inhibit the part of the coagulated material from being mixed with the molten glass and generating platinum defects.

The level of the liquid level may be indicated by the height of the liquid level from the bottom of the purifying pipe 102a instead of the distance between the liquid level of the molten glass MG and the upper end of the vapor phase space orthogonal thereto.

The preferable range of the air flow rate is preferably 5 m / min or less, more preferably 1 m / min or less, still more preferably 0.5 m / min or less.

In the case of controlling (adjusting) the level of the liquid surface of the molten glass (MG) in the case of continuous production of the glass substrate, aggregation of platinum or platinum metal or the like by defect inspection of the glass substrate performed after the cutting step (ST6) It is desirable to control (adjust) the level of the liquid surface of the molten glass MG in accordance with the result of detection of the foreign matter. In the defect inspection, defects such as foreign matters of a plurality of kinds are identified, and aggregates such as platinum or platinum metal have a unique shape with respect to other foreign matters or defects, so that they can be easily identified.

Regarding the temperature of the cleaning tube 102a in any of the volume control of the vapor phase space and the control of the area of the inner wall (adjustment) and the control of the level of the liquid level (adjustment), the platinum or platinum alloy The temperature difference between the maximum temperature and the minimum temperature of the inner wall portion of the furnace or the like may be 50 占 폚 or higher, 150 占 폚 or higher, or 250 占 폚 or higher. When the temperature difference is 50 DEG C or higher, the volatiles of platinum or platinum alloy generally tend to easily flocculate due to the temperature dependence of the saturated vapor pressure near the inner wall of the lowest temperature in the vapor phase space. However, as in the present embodiment, by controlling (adjusting) the level of the liquid surface of the molten glass MG, the amount of volatilized platinum or platinum alloy is reduced and the aggregation amount is reduced. In this respect, when the temperature difference is 50 DEG C or more, the effect of suppressing the incorporation of aggregates such as platinum or platinum alloy into the molten glass MG when the cleaning tube 102a of the present embodiment is used has a temperature difference of 50 Lt; RTI ID = 0.0 > C < / RTI >

Further, the maximum temperature of the purifying tube 102a may be 1400 ° C or higher, 1600 ° C or higher, 1630 ° C or higher, and further 1650 ° C or higher. When the maximum temperature is high, the effect of suppressing the incorporation of aggregates such as platinum or platinum alloy into the molten glass MG in the present embodiment is larger than that of a cleaning tube having a maximum temperature of less than 1400 占 폚. Also, if the maximum temperature of the inner wall of the cleaning tube 102a is too low, for example, the reaction as a cleaning agent of tin oxide becomes ineffective and the refining of the molten glass becomes insufficient. Therefore, the maximum temperature of the inner wall of the purifying tube 102a is preferably 1630 캜 to 1720 캜, and more preferably 1650 캜 to 1720 캜.

The temperature distribution of the cleaning tube 102a can be obtained by measuring using a temperature sensor such as a thermocouple or by using thermal conduction simulation.

The above-mentioned preferable range of the non-S / L, or the reference liquid level or the target liquid level A changes when the processing conditions in the cleaning process are different. Thus, for example, a non-S / L, or base face level or target face level A

(1) oxygen concentration in the gas phase space,

(2) the maximum temperature of the inner wall of the molten glass processing apparatus,

(3) the amount of oxygen released from the molten glass to the vapor phase space,

(4) the temperature difference between the maximum temperature of the molten glass in the dissolving step and the maximum temperature of the molten glass in the processing step, and

(5) Vapor pressure of the platinum group metal (platinum or platinum alloy) in the vapor phase space

The value of which is determined based on at least one of the following.

For example, in the case of the oxygen concentration in the vapor phase space of (1) above, when the oxygen concentration in the gas phase changes, a preferable ratio S / L for suppressing the volatilization of platinum or platinum alloy, A is changed. When the oxygen concentration in the gas phase becomes high, volatilization of platinum or platinum alloy becomes active, so that it is preferable that the area L is small. It is also preferable that the level of the molten glass is higher. However, when the area L is made smaller, the volume S of the molten glass becomes higher as the liquid level of the molten glass becomes higher, and the oxygen concentration gradually increases. Accordingly, the oxygen concentration in the gas phase space is one of the major factors in determining the desirable ratio S / L for suppressing the volatilization of platinum or platinum alloy, or the reference liquid level or the target liquid level A.

The oxygen concentration in the gas phase space can be controlled (adjusted) by the amount of the fining agent contained in the molten glass, for example, the content of tin oxide, the temperature or temperature history of the molten glass, and the amount of inert gas introduced into the gas phase space. The temperature or temperature history of the molten glass varies depending on the maximum inner wall temperature of the molten glass processing apparatus. Therefore, the maximum inner wall temperature of the molten glass processing apparatus is also one of the major factors in determining the desirable non-S / L for suppressing the volatilization of platinum or platinum alloy, or the standard liquid level or the target liquid level A .

When the content of the refining agent, for example, tin oxide, contained in the molten glass changes, the amount of oxygen released from the molten glass into the vapor phase also changes. That is, as the content of tin oxide increases, the amount of oxygen released increases and the oxygen concentration in the vapor phase rises. Therefore, the amount of oxygen released from the molten glass to the vapor phase space is also one of the major factors in determining the desired ratio S / L for suppressing the volatilization of platinum or platinum alloy, or the reference liquid level or the target liquid level A . From this point, it is preferable that the oxygen concentration in the vapor phase space is controlled (adjusted) by the content of tin oxide, in view of suppressing volatilization of platinum or platinum alloy. Therefore, from the standpoint of suppressing the volatilization of platinum or platinum alloy, the content of tin oxide is limited to 0.01 to 0.3 mol%, preferably 0.03 to 0.2 mol. If the content of tin oxide is large, secondary crystals are generated in the molten glass in the tin oxide, which is not preferable. If the content of tin oxide is too small, refinement of the molten glass is not sufficient.

With respect to the temperature or the temperature history of the molten glass, when the temperature of the molten glass is changed, the amount of reducing oxidizing agent such as reducing tin oxide and the viscosity of the molten glass are changed by this temperature change. Thereby, the amount of oxygen released from the molten glass to the vapor phase space is also changed.

Further, the larger the temperature difference between the molten glass in the dissolution step before entering the molten glass processing apparatus and the molten glass in the processing step after flowing into the molten glass processing apparatus, the greater the amount of oxygen released from the molten glass processing apparatus. That is, by controlling (adjusting) the temperature history of the molten glass in the molten glass treatment apparatus from before the molten glass treatment apparatus is introduced, the amount of oxygen released from the molten glass to the gas phase also changes. Therefore, the temperature difference between the maximum temperature of the molten glass in the melting step and the maximum temperature of the molten glass in the processing step is preferably set to a preferable value S / L for suppressing the volatilization of platinum or platinum alloy, This is one of the major factors in determining the level A of the face. In this case, the temperature difference is preferably not less than 50 ° C and not more than 200 ° C, more preferably not less than 70 ° C but not more than 150 ° C, in terms of both suppressing volatilization of platinum or platinum alloy and purifying effect.

Further, in determining the vapor pressure of the platinum group metal (platinum or platinum alloy) in the vapor phase space and the preferable ratio S / L for suppressing the volatilization of platinum or platinum alloy or the reference liquid level or the target liquid level A, It is becoming one of the big factors. The vapor pressure of the platinum group metal (platinum or platinum alloy) in the vapor phase space is determined by the volatilization amount of the platinum group metal (platinum or platinum alloy) volatilizing in accordance with the inner wall temperature of the molten glass processing apparatus. Therefore, the inner wall temperature of the molten glass processing apparatus has become one of the major factors in determining the preferable non-S / L for suppressing the volatilization of platinum or platinum alloy, or the standard liquid level or the target liquid level A . In the case where the temperature of the inner wall is high and the amount of volatilization is large and the vapor pressure of the platinum group metal (platinum or platinum alloy) in the vapor phase space is high, when the fast air flow W1 as shown in Fig. , The state in which the vapor pressure of the platinum group metal (platinum or platinum alloy) reaches the saturated vapor pressure is maintained. In this case, it is possible to control (adjust) the non-S / L or the reference liquid level or the target liquid level A in order to reduce the absolute amount of the volatilized amount. The vapor pressure of the platinum group metal in the vapor phase space is preferably 1 Pa to 10 Pa, more preferably 3 Pa to 10 Pa, in view of suppressing volatilization and aggregation of platinum or platinum alloy.

Wherein a vapor pressure of the platinum group metal in the vapor phase is 1 Pa to 10 Pa, a maximum temperature of the inner wall of the molten glass processing apparatus is 1630 to 1720 ° C, a volume of the vapor phase space is S [m 3] When the area is L [m < 2 >], by setting the ratio S / L to 17 [m] or more, volatilization and aggregation of platinum or platinum alloy can be suppressed. At this time, the oxygen concentration in the vapor phase space is preferably 2% or less. The content of tin oxide in the glass substrate to be produced is preferably 0.01 to 0.3 mol%.

In the present embodiment, a method of energizing and heating the cleaning tube 102a for degassing the molten glass is used. In the energization heating method, since the heating tube 102a is directly heated, the heating tube such as a heater is provided around the heating tube to heat the heating tube indirectly. In contrast to the case where the heating tube is indirectly heated, The temperature gradient increases, and the temperature difference between the maximum temperature and the minimum temperature tends to increase. As a result, as described above, in the conventional purifying tube, the amount of aggregate such as platinum or platinum alloy tends to increase. However, in the present embodiment, since the volatilization of platinum or platinum alloy is suppressed, the amount of aggregates of platinum or platinum alloy is small. In this respect, the effect of the present embodiment in suppressing the incorporation of aggregates such as platinum or platinum alloy into the molten glass MG when using a method of energizing and heating the cleaning tube 102a is achieved by using an indirect heating system Compared to a ceremonial tube.

Further, in the case of the conduction heating method of the cleaning tube 102a, the flange may be provided around the cleaning tube 102a in order to uniformly flow the current around the tube of the cleaning tube 102a. The flange is cooled to prevent breakage by heat. Further, the flange functions as a cooling fin. As a result, the inner wall temperature of the portion of the cleaning tube 102a on which the flange is provided is likely to be lowered. That is, in the inner wall of the portion where the flange of the cleaning tube 102a is installed, platinum or platinum alloy is liable to coagulate. Even in such a case, in this embodiment, since the volatilization of platinum or platinum alloy is suppressed, the amount of platinum or platinum alloy coagulum is small. Therefore, even when the flange is used for the cleaning tube 102a, the effect of the present embodiment in suppressing the inclusion of the aggregate such as platinum or platinum alloy into the molten glass MG is larger than the conventional cleaning tube .

Further, a gas introducing device may be provided in the vapor-phase space of the cleaning tube 102a of the present embodiment so as to introduce molten glass, platinum, a platinum alloy, or the like and an inert gas. In this case, for example, a nozzle for introducing an inert gas is provided in the vapor phase space. By introducing an inert gas into the gas phase space, the oxygen partial pressure or the oxygen concentration in the gas phase space can be lowered. Oxygen combines with platinum or platinum alloys to promote volatilization. Therefore, by lowering the oxygen partial pressure, volatilization of platinum or platinum alloy can be suppressed from the inner wall of the purifying pipe 102a. At this time, the inert gas is introduced from the low-temperature portion of the inner wall of the inner wall of the cleaning tube 102a, which is in contact with the vapor-phase space, into the vapor phase space, and the volatilized platinum or platinum alloy moves from the low- Is preferable in that it suppresses aggregation of volatiles such as platinum or platinum alloy. For example, it is preferable that the inert gas is introduced into the vapor phase space from the portion of the inner wall of the cleaning tube 102a where the temperature is lower than the surrounding temperature, for example, the temperature is minimized. Particularly preferably, the portion of the inner wall of the cleaning tube 102a where the temperature is lowest is introduced into the vapor phase space. The oxygen partial pressure is lowered because the inert gas is introduced from the portion of the purifying pipe 102a where the temperature of the inner wall of the purifying column is prone to flocculate. Therefore, depending on the partial pressure dependence of the volatilization saturated vapor pressure, aggregation of volatiles is suppressed.

As the inert gas, for example, a nitrogen gas or a rare gas such as argon gas, helium gas or neon gas or a mixed gas of these gases can be used.

The portion where the vapor phase space in the cleaning tube 102a of the present embodiment is connected to the atmosphere is the vent pipe 107. [ The shape of the vent pipe 107 is a shape extending linearly from the ceiling portion of the purifying pipe 102a in the form of a chimney. The vent pipe 107 is not limited to this shape but may be a bent shape. It is preferable that the vent pipe 107 is provided with a temperature regulating device such that volatiles such as platinum or platinum alloy do not contact with the low temperature portion of the vent pipe 107 and flocculate.

Although the clarifying apparatus 102 has been described as the molten glass processing apparatus, the molten glass processing apparatus can be applied to the stirring apparatus 103 as well. However, application to the cleaning tube 102 is preferable for the following reasons.

That is, the finishing apparatus 102 is an apparatus for heating the temperature of the molten glass to the highest level among a plurality of types of apparatuses using platinum or platinum alloy from purifying to immediately before molding. As a result, in the purifying tube 102a, the volatilization of platinum or platinum alloy is the most severe among the apparatuses. In addition, since the component of the gas released into the vapor phase space by defoaming performed in the purifying tube 102a contains a large amount of oxygen which promotes volatilization of platinum or a platinum alloy, the partial pressure of oxygen in the vapor phase space is higher than that in the atmosphere . As a result, in the gas phase space, platinum or a platinum alloy or the like is further volatilized from the inner wall. Since the purifying pipe 102a has a larger difference between the maximum temperature and the minimum temperature of the inner wall and the difference in the saturated vapor pressure of the volatilized product compared to other devices such as the stirring device 103, Volatilization of the volatiles tends to occur. Further, in the purifying tube 102a, the flow of airflow is larger than in other apparatuses. Therefore, in order to suppress aggregation of volatiles, it is preferable to apply control (adjustment) of the non-S / L or liquid level to the clarification apparatus 102.

Further, even in a glass substrate having a thin glass substrate, for example, a glass substrate having a thickness of 0.5 mm or less, more preferably 0.3 mm or less, or even 0.1 mm or less, the aggregation of volatiles such as platinum or platinum alloy of the present embodiment is suppressed Is remarkable in comparison with a glass substrate having a large thickness. A part of the aggregate such as platinum or platinum alloy coagulated on the inner wall of the cleaning tube 102a or the like becomes fine particles and drops into the molten glass and is mixed into the molten glass to be contained in the glass substrate. In this case, the thinner the plate thickness of the glass substrate, the more often the defective fine particles are located on the surface of the glass substrate. When the fine particles located on the surface of the glass substrate are removed, for example, in a panel manufacturing process using a glass substrate, the separated portion is recessed, and the thin film formed on the glass substrate is not uniformly formed, Lt; / RTI > Therefore, as in the present embodiment, the effect of suppressing the volatilization of platinum or platinum alloy in the cleaning tube 102a and allowing a part of the agglomerates such as platinum or platinum alloy to become foreign substances and being incorporated into the molten glass is a thin The larger the glass substrate, the larger.

(Glass composition)

In the present embodiment, the effect of the present embodiment becomes remarkable if the substrate is a non-alkali glass substrate containing tin oxide or a micro alkali glass substrate containing tin oxide. The alkali-free glass or the alkali-alkali glass has a higher glass viscosity than the alkali glass. Therefore, it is necessary to increase the melting temperature in the melting step, and since a large amount of tin oxide is reduced in the dissolving step, in order to obtain the clarifying effect, the temperature of the molten glass in the refining step is increased, It is also necessary to lower the viscosity of the molten glass. That is, when a non-alkali glass substrate containing tin oxide or a micro alkali glass substrate containing tin oxide is to be produced, it is necessary to raise the temperature of the molten glass in the refining step, so that volatilization of platinum or platinum alloy It is easy to occur. Herein, in the present specification, the alkali-free glass substrate is a glass substantially free of alkali metal oxides (Li ₂ O, K ₂ O and Na ₂ O). The alkali alkali glass is a glass having an alkali metal oxide content (a total amount of Li ₂ O, K ₂ O and Na ₂ O) of more than 0 and less than 0.8 mol%.

As the glass substrate manufactured in the present embodiment, a glass substrate having the following glass composition is exemplified. Therefore, the glass raw materials are combined so that the following glass composition is contained in the glass substrate. The glass substrate to be produced in this embodiment is, for example, 55 to 75 mol% of SiO ₂ , 5 to 20 mol% of Al ₂ O ₃ , 0 to 15 mol% of B ₂ O ₃ , 5 to 20 mol% of RO MgO, CaO, SrO and BaO), R ' ₂ O 0 to 0.4 mol% (R' is the sum of Li ₂ O, K ₂ O and Na ₂ O) and 0.01 to 0.4 mol% of SnO ₂ .

At this time, the glass substrate contains at least any one of SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ and RO (R is an element contained in the glass substrate among Mg, Ca, Sr and Ba) ₂ ) + Al ₂ O ₃ ) / ((2 x B ₂ O ₃ ) + RO) may be 4.0 or more, and the effect of reducing the generation of bubbles and non- can do. That is, the glass having a molar ratio ((2 x SiO ₂ ) + Al ₂ O ₃ ) / ((2 x B ₂ O ₃ ) + RO) of 4.0 or more is an example of a glass having a high- Generally, in a glass having a high temperature viscosity, it is necessary to raise the temperature of the molten glass in the refining step, so that volatilization of platinum or a platinum alloy is likely to occur. That is, in the case of producing a glass substrate having such a composition, the effect of the present embodiment in suppressing the incorporation of aggregates such as platinum or platinum alloy into the molten glass as foreign matters becomes remarkable. The high-temperature viscosity refers to the glass viscosity at a high temperature of the molten glass, and the high temperature referred to herein means, for example, 1300 ° C or higher.

According to the present embodiment, even if the content of the alkali metal oxide in the glass substrate is 0 to 0.8 mol%, it is possible to suppress the incorporation of aggregates such as platinum or platinum alloy into the molten glass as foreign matters. The lower the content of the alkali metal oxide, the higher the high-temperature viscosity. Thus, the glass having the alkali metal oxide content of 0 to 0.8 mol% has a higher high-temperature viscosity than the glass having the alkali metal oxide content exceeding 0.8 mol% . Generally, in a glass having a high temperature viscosity, it is necessary to raise the temperature of the molten glass in the refining step, so that volatilization of platinum or a platinum alloy is likely to occur. That is, when the glass having a high temperature viscosity is used, the effect of the present embodiment in suppressing the incorporation of aggregates such as platinum or platinum alloy into the molten glass as a foreign matter becomes remarkable.

The molten glass used in the present embodiment may be a glass composition having a viscosity of 1500 to 1700 占 폚 when the viscosity is 10 ^2.5 poise. As described above, glass having a high temperature viscosity generally needs to have a high molten glass temperature in the refining step, and therefore volatilization of platinum or a platinum alloy is likely to occur. That is, even if the glass composition has a high-temperature viscosity, the above effect of the present embodiment becomes remarkable.

The deformation point of the molten glass used in the present embodiment may be 650 ° C or higher, more preferably 660 ° C or higher, more preferably 690 ° C or higher, and particularly preferably 730 ° C or higher. In addition, a glass having a high strain point tends to have a high temperature of the molten glass at a viscosity of 10 ^2.5 poise. That is, the more the glass substrate having a high strain point is produced, the more remarkable the effect of the present embodiment becomes.

Further, when the glass raw material is melted so as to be a glass containing tin oxide and having a viscosity of 10 ^2.5 poise and a molten glass temperature of 1500 ° C or higher, the above effect of the present embodiment becomes more remarkable and the viscosity becomes 10 ^2.5 The temperature of the molten glass in the case of Poisson is, for example, 1500 to 1700 占 폚, and may be 1550 to 1650 占 폚.

The glass substrate manufactured in this embodiment is suitable for a glass substrate for a display including a glass substrate for a flat panel display. It is suitable for glass substrates for oxide semiconductor displays using oxide semiconductors such as IGZO (indium, gallium, zinc, oxygen) and glass substrates for LTPS displays using LTPS (low temperature polysilicon) semiconductors. In addition, the glass substrate produced in this embodiment is suitable for a glass substrate for a liquid crystal display which requires a very small content of alkali metal oxide. It is also suitable for a glass substrate for an organic EL display. In other words, the method of manufacturing a glass substrate of the present embodiment is suitable for manufacturing a glass substrate for a display, and is particularly suitable for manufacturing a glass substrate for a liquid crystal display.

Further, the glass substrate manufactured in this embodiment can be applied to a cover glass, a glass for a magnetic disk, a glass substrate for a solar cell, and the like.

(Experimental Example 1)

In order to confirm the effect of the control (adjustment) of the non-S / L in the present embodiment, the number of foreign matters including aggregates such as platinum or platinum alloy mixed in the molten glass is checked by varying the ratio S / .

Specifically, the glass raw material in the dissolving apparatus was melted and made into molten glass so that the glass substrate to be produced had the above-mentioned glass composition, and then the molten glass was refined in the refining apparatus 102. Subsequently, homogenization, molding by overflow down-draw method, gradual cooling and cutting were carried out to obtain a glass substrate for a flat display. The maximum temperature of the clarifying apparatus 102 was 1710 占 폚 and the difference between the maximum temperature and the minimum temperature of the clarifying apparatus 102 was 250 占 폚. Fig. 6 shows the relationship between the foreign matter including the aggregate such as platinum or platinum alloy when the ratio S / L is varied in various ways with time (the abscissa in Fig. 6 is the time). 6 is a diagram showing the relationship between the ratio S / L and defect density. The defect density in the figure indicates the number of aggregates such as platinum or platinum alloy per unit weight. In Fig. 6, the case where the defect density is the largest is denoted by 1, and the defect density is denoted by the ratio in other cases. The dotted line in FIG. 6 is an approximate curve of the defect density ratio. As shown in Fig. 6, when the ratio S / L is 17 [m] or more, the defect density ratio can be 0.5 or less. When the ratio S / L was set to 25 [m] or more, the defect density ratio could be reduced to 0.3 or less.

(Experimental Example 2)

In order to confirm the effect of the level control (adjustment) of the liquid level in this embodiment, the liquid level of the molten glass is varied in various ways to check the number of foreign matters including aggregates such as platinum or platinum alloy incorporated in the molten glass .

Specifically, the glass raw material in the dissolving apparatus was melted and made into molten glass so that the glass substrate to be produced had the above composition, and then the molten glass was refined in the refining apparatus. Subsequently, molding by stirring, overflow down-draw method, gradual cooling and cutting were carried out to obtain a glass substrate for a flat display. The maximum temperature of the clarifying apparatus was 1710 캜, and the difference between the maximum temperature and the minimum temperature of the purifying apparatus was 250 캜. (100) glass substrates manufactured by controlling (adjusting) the liquid level to a range of the target liquid level A, the liquid level is not controlled (adjusted) so as to be within the range of the target liquid level A, The number of platinum defects can be reduced to 1/3 or less as compared with that of 100 glass substrates produced in the case of smaller size.

Although the glass substrate manufacturing method, the glass substrate manufacturing apparatus, and the molten glass processing apparatus of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the gist of the present invention. It is of course possible to make changes.

100 Melting Glass Generator
101 Dissolution apparatus
101d screw feeder
102 Clarification apparatus
102a purifying pipe
102b vent
103 Stirring apparatus
103a stirrer
104, 105, 106 Glass feed pipe
200 molding device
210 shaped body
300 cutting device

Claims (15)

A melting step of melting a glass raw material to produce a molten glass;
A molten glass processing apparatus composed of a material having a liquid phase of the molten glass and at least a part of the inner wall surrounding the gas phase being made of a material containing a platinum group metal, And a processing step of,
The ratio of the area of the platinum group metal on the inner wall contacting the vapor phase space to the volume of the vapor phase space is controlled so as to reduce the volatilization of the platinum group metal in the molten glass processing apparatus. Wherein the glass substrate is a glass substrate. The method of manufacturing a glass substrate according to claim 1, wherein the ratio is controlled by controlling a liquid level of the molten glass. The method according to claim 2, wherein the correlation between the number of platinum defects and the level of the molten glass in the molten glass processing apparatus is determined in advance, and the level of the molten glass processing apparatus corresponding to the allowable value of the number of platinum defects And the liquid level is controlled based on the reference liquid level in the processing step. A method of manufacturing a glass substrate,
A melting step of melting a glass raw material to produce a molten glass;
1. A molten glass treatment apparatus comprising a vapor phase space formed by a liquid surface and an inner wall of a molten glass and a liquid phase of the molten glass and at least a part of an inner wall surrounding the vapor phase is made of a material containing a platinum group metal, A processing step of processing the substrate,
And a molding step of molding the molten glass processed in the processing step into a sheet glass,
A correlation between the number of platinum defects in advance and the level of the liquid level of the molten glass processing apparatus is determined in advance and the level of the liquid level of the molten glass processing apparatus corresponding to the allowable value of the number of platinum defects is determined as the reference level level, Wherein the level of the liquid level is controlled based on the reference liquid level. 5. The method according to claim 3 or 4, wherein in the processing step, the level of liquid level is controlled based on the target liquid level range determined to include the reference liquid level. The method according to claim 1 or 4, wherein the volume of the vapor space is S [m 3], and the area of the platinum group metal in contact with the vapor space is L [m 2] ] Or more. The method of claim 1,
(1) the oxygen concentration in the vapor phase space,
(2) the maximum temperature of the inner wall of the molten glass processing apparatus,
(3) an amount of oxygen released from the molten glass to the vapor phase space,
(4) a temperature difference between the maximum temperature of the molten glass in the dissolution step and the maximum temperature of the molten glass in the processing step, and
(5) the vapor pressure of the platinum group metal in the vapor phase space
Wherein the glass substrate is a value determined based on at least one of the following. 5. The method of claim 4, wherein the reference face level is
(1) the oxygen concentration in the vapor phase space,
(2) the maximum temperature of the inner wall of the molten glass processing apparatus,
(3) an amount of oxygen released from the molten glass to the vapor phase space,
(4) a temperature difference between the maximum temperature of the molten glass in the dissolution step and the maximum temperature of the molten glass in the processing step, and
(5) the vapor pressure of the platinum group metal in the vapor phase space
Wherein the glass substrate is a value determined based on at least one of the following. The method for producing a molten glass treatment apparatus according to any one of claims 1 to 4, wherein the vapor pressure of the platinum group metal in the vapor phase is 1 Pa to 10 Pa, the maximum temperature of the inner wall of the molten glass processing apparatus is 1630 to 1720 캜, And S / L is 17 [m] or more when the area of the platinum group metal in contact with the vapor phase is L [m < 2 >]. The method of manufacturing a glass substrate according to claim 1 or 4, wherein a temperature difference between a maximum temperature and a minimum temperature of the platinum group metal portion of the inner wall in contact with the vapor phase space is 50 DEG C or more. The method of manufacturing a glass substrate according to claim 1 or 4, wherein the molten glass processing apparatus is a refining apparatus for refining molten glass. 1. A molten glass processing apparatus comprising a vapor phase space formed by a liquid surface and an inner wall of a molten glass and a liquid phase of molten glass and at least a part of an inner wall surrounding the vapor phase comprises a platinum group metal,
And a control section for controlling a ratio of an area of the platinum group metal in the wall contacting the vapor space to a volume of the vapor space so as to reduce the volatilization of the platinum group metal in the vapor space. Device. 1. A molten glass processing apparatus comprising a vapor phase space formed by a liquid surface and an inner wall of a molten glass and a liquid phase of molten glass and at least a part of an inner wall surrounding the vapor phase comprises a platinum group metal,
And a control unit for controlling the liquid level of the molten glass processing apparatus to be a predetermined reference liquid level,
The control unit determines the reference liquid level as the liquid level of the glass melt processing apparatus corresponding to the allowable value of the number of platinum defects based on the correlation between the number of platinum defects obtained in advance and the liquid level of the glass melt processing apparatus Wherein the molten glass is a molten glass. A glass substrate manufacturing apparatus comprising:
A melting apparatus for melting glass raw materials to produce molten glass,
A vapor phase space formed by the liquid surface and the inner wall of the molten glass; a molten glass treatment for treating the molten glass, wherein the molten glass has a liquid phase and at least a part of the inner wall surrounding the vapor phase is made of a material containing a platinum group metal [0001]
A molding apparatus for molding the molten glass processed in the molten glass processing apparatus into a sheet glass,
And a control section for controlling the ratio of the area of the platinum group metal on the inner wall contacting the vapor space to the volume of the vapor space so as to reduce volatilization of the platinum group metal of the molten glass processing apparatus Substrate manufacturing apparatus. A glass substrate manufacturing apparatus comprising:
A melting apparatus for melting glass raw materials to produce molten glass,
A vapor phase space formed by the liquid surface and the inner wall of the molten glass; a molten glass treatment for treating the molten glass, wherein the molten glass has a liquid phase and at least a part of the inner wall surrounding the vapor phase is made of a material containing a platinum group metal [0001]
A molding apparatus for molding the molten glass processed in the molten glass processing apparatus into a sheet glass,
And a control unit for controlling the liquid level of the molten glass processing apparatus to be a predetermined reference liquid level,
The control unit determines the reference liquid level as the liquid level of the glass melt processing apparatus corresponding to the allowable value of the number of platinum defects based on the correlation between the number of platinum defects obtained in advance and the liquid level of the glass melt processing apparatus Wherein the glass substrate is a glass substrate.

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