TWI576318B - Method for manufacturing glass substrates - Google Patents

Description

Method for manufacturing glass substrate

The present invention relates to a method of manufacturing a glass substrate using a down-draw method.

In the manufacturing step of the glass substrate, a down-draw method is used as a method of forming the glass. The pull-down method is such that after the molten glass flows into the groove of the formed body, the molten glass overflows from the groove. Thereafter, the molten glass flows down the side of the formed body. The molten glass is joined to the lower end portion of the molded body, and then separated from the molded body to form a sheet-shaped glass (flat glass). The flat glass is stretched and conveyed downward by a roll, and is cooled by the environment inside the furnace. Thereafter, the flat glass is cut into a desired size and further processed to form a glass substrate.

The apparatus for manufacturing a glass sheet described in Patent Document 1 below includes an internal partition that partitions the heat generating body in the furnace chamber from the molded body. The heat between the molten glass in the furnace chamber and the internal partition heated by the heating element is mainly exchanged by radiant heat transfer. Therefore, if there is a temperature distribution on the inner partition wall, the surface of the opposite molten glass is also wide. The direction produces a temperature distribution. Therefore, as the material of the inner partition wall, it is preferable that the thermal conductivity is large and the homogeneity is high. Patent Document 1 describes a case where a plate made of, for example, SiC can be used for the inner partition wall.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Registered Utility Model No. 2530060

However, even in the case where a SiC plate having a large thermal conductivity and a high degree of homogeneity is used as the inner partition wall, the inner partition wall made of a material having a high porosity has the following conditions. : If it is exposed to the high temperature environment in the forming furnace for a long time, inside the internal partition wall, the internal pores cause Si to oxidize to form SiO ₂ , thereby causing abnormal expansion, which may cause deformation or crack or crack on the surface. . When the deformation of the internal partition wall, the cracking of the surface, and the cracking occur as described above, the heat equalization effect of the internal partition wall is lowered, the quality of the glass substrate is lowered, or the internal partition wall needs to be replaced, and the productivity of the glass substrate is lowered.

Accordingly, an object of the present invention is to provide a method for producing a glass substrate capable of suppressing oxidative expansion of an internal partition wall when a glass substrate is produced by a down-draw method.

The method for producing a glass substrate of the present invention has the following aspects.

[Scenario 1]

A method for producing a glass substrate, comprising: forming a molten glass into a flat glass by a down-draw method; and providing a heating element, the molded body, and the heat generating body and the molded body in a forming furnace chamber; In the internal partition, an SiC sintered body having an open porosity of 1% or less is used for the internal partition, and the molten glass flowing through the molded body is heated by the heat generating body and interposed between the internal partitions.

[Surface 2]

A method of producing a glass substrate according to aspect 1, wherein the inner partition wall has a thermal conductivity of 20 W/(m.K) or more at 1200 °C.

[Surface 3]

The aspect of the method of producing a glass substrate of 1 or 2, wherein the viscosity of the melt when the glass based on ¹⁰⁵ poises (Poise) of less than 1000 ℃.

[Surface 4]

The method for producing a glass substrate according to any one of the aspects 1 to 3, wherein the glass substrate is an alkali-free glass or a glass containing a trace amount of alkali.

[Surface 5]

The method for producing a glass substrate according to any one of the aspects 1 to 4, wherein a space between the furnace wall of the forming furnace chamber and the inner partition wall is partitioned into a plurality of small spaces adjacent to each other by a horizontal partition wall, and The heat generating body is disposed in each of the small spaces.

[Figure 6]

In the method of producing a glass substrate according to the aspect 5, the temperature of the wall surface facing the side of the molded body of the inner partition wall is adjusted so as to proceed in a direction in which the molten glass flows, and the heat generating body is adjusted. Calorie.

According to the method for producing a glass substrate which is one aspect of the present invention, when the glass substrate is produced by the down-draw method, the problem of oxidative expansion accompanying the internal partition walls can be suppressed.

14‧‧‧Formed body

14b‧‧‧ side

14c‧‧‧ sloped surface

14d‧‧‧Bottom

16‧‧‧Internal partition

18‧‧‧ Groove Department

20‧‧‧Parts

22‧‧‧Cooling roller

24‧‧‧ furnace wall

26‧‧‧ horizontal partition

28‧‧‧heating body

30‧‧‧Forming furnace room

100‧‧‧Glass substrate manufacturing equipment

200‧‧‧melting device

201‧‧‧melting tank

202‧‧‧Clarification tank

203‧‧‧Stirring tank

204‧‧‧1st piping

205‧‧‧2nd piping

300‧‧‧Forming device

G‧‧‧ flat glass

MG‧‧‧ molten glass

Fig. 1 is a flow chart showing a part of a method of manufacturing a glass substrate of the present embodiment.

Fig. 2 is a schematic view showing a glass substrate manufacturing apparatus used in the method for producing a glass substrate of the embodiment.

Fig. 3 is a side view showing a part of a molding apparatus included in the glass substrate manufacturing apparatus shown in Fig. 2;

Fig. 4 is a view for explaining the temperature distribution around the heating element of the embodiment.

Hereinafter, a method of manufacturing a glass substrate of the present embodiment will be described with reference to the drawings.

Fig. 1 is a flow chart showing a part of a method of manufacturing a glass substrate of the present embodiment.

As shown in FIG. 1, the glass substrate is manufactured through various steps including a melting step ST1, a clarification step ST2, a homogenization step ST3, a molding step ST4, a cooling step ST5, and a cutting step ST6.

In the melting step ST1, the glass raw material is heated and melted. The glass raw material contains a composition of SiO ₂ , Al ₂ O ₃ or the like. The glass material that has been completely melted becomes molten glass.

In the clarification step ST2, the molten glass is clarified. Specifically, the gas component contained in the molten glass is released from the molten glass, or the gas component is absorbed into the molten glass.

In the homogenization step ST3, the molten glass is homogenized.

In the molding step ST4, the molten glass is formed into a sheet-shaped glass, that is, a flat glass by a down-draw method (specifically, an overflow down-draw method).

In the cooling step ST5, the formed flat glass in the forming step ST4 is slowly cooled. In this cooling step ST5, the plate glass is cooled to near room temperature.

In the cutting step ST6, the plate glass which has been cooled to near room temperature is cut at a specific length to form a plain glass.

Further, the plain plate glass cut at a specific length is further cut, ground, polished, washed, and inspected to form a glass substrate, and used for a flat panel display such as a liquid crystal display.

Next, a glass substrate manufacturing apparatus used in the method of manufacturing a glass substrate of the present embodiment will be described.

FIG. 2 is a schematic view showing a glass substrate manufacturing apparatus 100.

The glass substrate manufacturing apparatus 100 mainly has a melting apparatus 200 and a molding apparatus 300.

The melting device 200 is configured to perform a melting step ST1, a clarification step ST2, and a homogenization The device of step ST3. As shown in FIG. 2, the melting apparatus 200 has a melting tank 201, a clarification tank 202, a stirring tank 203, a first piping 204, and a second piping 205.

The melting tank 201 is a tank for melting glass raw materials. In the melting tank 201, a melting step ST1 is performed.

The clarification tank 202 is a tank for removing bubbles from the molten glass which has been melted in the melting tank 201. Defoaming of the molten glass is promoted by further heating the molten glass fed from the melting tank 201 in the clarification tank 202. In the clarification tank 202, a clarification step ST2 is performed.

The stirring tank 203 stirs the molten glass by a stirrer. In the stirring tank 203, a homogenization step ST3 is performed.

The first pipe 204 and the second pipe 205 are pipes made of an alloy of a platinum group element or a platinum group element. The first pipe 204 is a pipe connecting the clarification tank 202 and the stirring tank 203. The second pipe 205 is connected to the pipe of the stirring tank 203 and the molding apparatus 300.

The forming apparatus 300 is a device for performing the forming step ST4 and the cooling step ST5.

FIG. 3 is a schematic side view showing the forming furnace chamber 30 included in the forming apparatus 300.

As shown in FIG. 3, the molding apparatus 300 is provided with the shaping furnace chamber 30 in the uppermost part. The forming furnace chamber 30 is provided with a furnace wall 24 as an outer wall, and is distinguished from the lower furnace chamber by the partition member 20. Inside the forming furnace chamber 30, a molded body 14 and a plurality of heat generating bodies 28 are disposed. An inner partition wall 16 that partitions the molded body 14 and the heat generating body 28 is provided around the molded body 14.

The formed body 14 is a device for performing the forming step ST4 and is disposed in the forming furnace chamber 30. The molded body 14 has a function of molding the molten glass flowing from the melting device 200 into a sheet-shaped glass substrate (flat glass G) by an overflow down-draw method. The formed body 14 has a wedge shape in a cross-sectional shape cut in the vertical direction, and is composed of, for example, refractory bricks including zircon, zirconia, YPO ₄ , Al ₂ O ₃ , SiO ₂ , SiC, SiN, and the like. . A groove portion 18 that accommodates the molten glass MG flowing from the melting device 200 is formed in the upper portion of the molded body 14. The side surface 14b of the molded body 14 is formed in the vertical direction so that the molten glass MG overflowing from the groove portion 18 flows down. The inclined surface 14c of the molded body 14 is inclined with respect to the side surface 14b such that the molten glass MG flowing down the both side faces 14b and 14b of the molded body 14 merges with the lowermost end portion 14d which is the apex of the wedge-shaped cross section of the molded body 14.

The inner partition wall 16 is disposed between the heat generating body 28 and the molded body 14 and is disposed around the molded body 14 so as to surround the molded body 14 . The inner partition wall 16 is composed of a SiC sintered body, and more specifically, a high-density sintered SiC plate. The inner partition wall 16 is preferably made of a SiC sintered body having a SiC content of 95% by weight or more. Further, from the viewpoint of improving the uniformity of the temperature of the internal partition wall 16, it is preferable to use a thermal conductivity of 20 W/(m.K) or more, more preferably 25 W/(m.K) or more at 1200 °C. Further, a SiC sintered body of 30 W/(m.K) or more is preferable. The upper limit of the above thermal conductivity is, for example, 490 W/(m.K). Moreover, from the viewpoint of preventing oxidative expansion of the inner partition wall 16, the open porosity of the SiC sintered body constituting the inner partition wall 16 is set to 1% or less. The open porosity of the SiC sintered body is preferably 0.8% or less, and more preferably 0.6% or less. Moreover, the open porosity of the SiC sintered body is set to, for example, more than 0%. Here, the open porosity is a percentage of the volume of the open pore portion in the case where the external volume of the sample is set to 1, for example, the measurement method specified in JIS R 1634:1998. The measurement was carried out.

Between the furnace wall 24 and the internal partition wall 16, a horizontal partition wall 26 that partitions the space between the furnace wall 24 and the internal partition wall 16 in the lateral direction is provided. The horizontal partition wall 26 is a plate-shaped member that divides the space between the furnace wall 24 and the inner partition wall 16 of the forming furnace chamber 30 into a plurality of spaces adjacent to each other, and includes, for example, zircon, zirconia, YPO ₄ , A heat insulating member of Al ₂ O ₃ , SiO ₂ , SiC, SiN, and the like. A heating element 28 is disposed in each of the small spaces partitioned by the horizontal partition walls 26. The forming furnace chamber 30 is divided into a plurality of spaces, and the temperature of each space partitioned by the heating element 28 can be controlled, and the position and number of the horizontal partition walls 26 are arbitrary. For example, at predetermined intervals, the horizontal partition wall 26 is disposed at a position where the distance from the adjacent heat generating body 28 is constant. Further, the thickness of the horizontal partition wall 26 can be arbitrarily set, for example, the same as the thickness of the inner partition wall 16, or the same as the thickness of the furnace wall 24. In the case where the horizontal partition wall 26 and the inner partition wall 16 are the same material, the heat transfer amount of the horizontal partition wall 26 and the inner partition wall 16 can be made equal by setting the thicknesses to be the same, and the molten glass MG is made to have a width. Heat evenly in the direction. In the case where the SiC sintered body is used for the inner partition 16 and the horizontal partition 26, the inner partition wall provided closer to the molten glass MG may be used in order to uniformly heat the molten glass MG in the width direction. The thermal conductivity of 16 is higher than the thermal conductivity of the horizontal partition wall 26. Further, the open porosity of the inner partition wall 16 may be made lower than the open porosity of the horizontal partition wall 26. Further, in order to increase the uniformity of the temperature of the molten glass MG located at the lowermost end portion 14d of the molded body 14, the thermal conductivity of the inner partition wall 16 located at a position opposed to the lowermost end portion 14d may be higher than that of the two sides. The thermal conductivity of the inner partition wall 16 at the position opposite to 14b, 14b. Further, the opening ratio of the inner partition wall 16 located at a position opposed to the lowermost end portion 14d may be lower than the open porosity of the inner partition wall 16 located at a position opposed to the side surfaces 14b and 14b.

The heating element 28 is composed of, for example, a package heater that generates heat by resistance heating, dielectric heating, microwave heating, or induction heating, a cartridge heater, or a ceramic heater, and can arbitrarily adjust the amount of heat generation (temperature). ). Each of the heat generating bodies 28 disposed in the forming furnace chamber 30 can independently control the amount of heat generation. For example, a temperature gradient can be formed in such a manner that when the molten glass MG advances downward in the forming furnace chamber 30, the temperature is the groove portion 18 of the formed body 14. The order of the two side faces 14b, 14b, the inclined surface 14c, and the lowermost end portion 14d is sequentially lowered. In other words, it is preferable to adjust the amount of heat generation of the plurality of heat generating bodies 28 such that the temperature of the wall surface of the inner partition wall 16 facing the molded body 14 advances in a direction in which the molten glass MG flows.

The partition member 20 is a plate-shaped member disposed in the vicinity of the lowermost end portion 14d of the molded body 14, and includes, for example, zircon, zirconia, YPO ₄ , Al ₂ O ₃ , SiO ₂ , SiC, SiN, and the like. Insulation member. The partition member 20 is provided with a pair in such a manner that the front ends face each other. The partition member 20 is disposed on both sides in the thickness direction of the sheet glass G flowing down from the lowermost end portion 14d of the molded body 14 so as to be horizontal. The partition member 20 is thermally insulated by retaining the space above and below the gap through which the flat glass passes, and suppresses the heat from moving from the upper side to the lower side of the partition member 20. A cooling roll 22 is disposed below the partition member 20.

The cooling roller 22 is disposed in a furnace chamber located below the partition member 20. Further, the cooling rolls 22 are disposed opposite to each other in the thickness direction of the sheet glass G and at both end portions in the width direction thereof. The cooling roller 22 is air-cooled, for example, by an air cooling pipe passing through the inside thereof. When the plate glass G is passed through the cooling roll 22, the front and back sides of the both end portions in the width direction which are in contact with the air-cooled cooling roll 22 are cooled. Thereby, the viscosity of the both ends is adjusted to a specific value or more, for example, 10 ^9.0 poise (10 poise = 1 Pa. second) or more. The cooling roller 22 stretches the sheet glass G downward by transmitting the driving force of the driving motor.

Below the forming furnace chamber 30, a slow cooling furnace chamber (not shown) that performs the cooling step ST5 is provided. The slow cooling furnace chamber is divided into a plurality of furnace chambers along the flow of the flat glass G, and a plurality of stretching rollers are disposed along the flow of the flat glass G. The stretching roll is driven by a motor, and the flat glass G is pulled while being pulled downward. Further, a heater for adjusting the temperature of the environment around the sheet glass G is provided in each furnace chamber. By using the heater to control the temperature of the environment around the flat glass G, the temperature of the flat glass G is controlled, and the flat glass G is slowly cooled according to the temperature distribution of the sheet thickness deviation, warpage, and strain of the flat glass G. .

The cutting step ST6 is performed by a cutting device (not shown). The cutting device is disposed below the slow cooling furnace chamber. The cutting device is a device that cuts the sheet glass G flowing down in the forming device 300 in a direction perpendicular to the longitudinal surface thereof. The sheet-shaped flat glass G is cut into a plurality of plain plates having a specific length by cutting with a cutting device. The plain plate is further cut, subjected to end surface processing, washed, inspected, and then packaged, and shipped as a glass substrate.

Next, the action of this embodiment will be described.

In the forming step ST4, the molten glass MG flowing in the groove portion 18 of the formed body 14 It overflows at the top of the groove portion 18 and flows down the two side faces 14b, 14b of the formed body 14. Then, the molten glass G which flows down along the both side surfaces 14b and 14b of the molded object 14 passes through the inclined surfaces 14c and 14c, and merges at the lowermost end portion 14d of the molded body 14 to become the sheet glass G. The sheet glass G is supplied to the slow cooling furnace chamber below the forming furnace chamber 30 through a slit-like gap between the pair of partition members 20 and 20.

At this time, the internal partition 16 is heated by the heating element 28, and heat is exchanged between the heated internal partition 16 and the molten glass MG flowing through the molded body 14, and the molten glass MG is cooled.

The atmosphere containing oxygen in the forming furnace chamber 30 is maintained at a temperature of about 1000 ° C or higher, for example, about 1200 ° C, but the inner partition wall 16 is formed by exposing the inner partition wall 16 to such a high temperature and containing oxygen. The SiC sintered body starts to oxidize from the portion in contact with oxygen to become SiO ₂ . At this time, if the open porosity of the SiC sintered body is more than 1%, the oxidation is not only easy to proceed from the surface but also easily from the inside. In places where internal oxidation has taken place, the volume increases, which may cause deformation or further cause cracking. In particular, in the case where an alkali-free glass having a high temperature and high viscosity or a glass containing a trace amount of an alkali metal is formed in the forming furnace chamber 30, the temperature in the forming furnace chamber 30 must be kept higher than the previous temperature. . If the temperature in the forming furnace chamber 30 is made higher than before, the deformation of the inner partition wall 16 is promoted to cause cracking. The SiC sintered system is excellent in resistance to high temperatures and excellent in heat resistance and oxidation resistance. However, the oxidation initiation temperature of the SiC sintered body reacted with oxygen is about 700 ° C, and if it is above this temperature, oxidation starts, causing deformation or further causing cracking. Since the temperature in the forming furnace chamber 30 is 1000 ° C or more as described above, the SiC sintered body is easily oxidized in the forming furnace chamber 30.

In the present embodiment, the inner partition wall 16 is a SiC sintered body having an open porosity of 1% or less. Therefore, only the surface is in contact with the environment containing the high temperature of oxygen, so that SiC oxidation inside the tissue can be suppressed. Thereby, abnormal expansion due to internal oxidation of the internal partition wall 16 can be suppressed, and deformation, surface cracking, and cracking can be suppressed. Therefore, the uniform heat effect of the inner partition wall 16 can be prevented from being lowered, and the quality of the glass substrate can be improved. Further, the life of the inner partition wall 16 can be prolonged, and the productivity of the glass substrate can be improved. Further, when the SiC sintered body is oxidized, the oxide SiO ₂ completely covers the surface of the SiC sintered body and becomes a protective film for oxidation, so that oxidation of the inside of the internal partition 16 can be suppressed.

Further, the molten glass MG on the molded body 14 does not directly exchange heat with the heat generating body 28 but exchanges heat through the inner partition wall 16 . Therefore, even if the temperature of each of the heat generating bodies 28 is uneven depending on the place, the temperature unevenness of the molten glass MG on the molded body 14 is hardly affected by the heat equalizing effect of the inner partition walls 16. Fig. 4 is a view for explaining the temperature distribution around the heating element 28, and is a view of the molten glass MG, the internal partition 16 and the heating element 18 as viewed from the upper side in Fig. 3 . When the heating element 28 generates heat, the heat generated from the heating element 28 is diffused in a spherical shape around the heating element 28, and is formed in a small space surrounded by the internal partition wall 16, the horizontal partition wall 26, and the furnace wall 24. The spherical temperature distribution centering on the heating element 28. When the heat that has spread in a spherical shape reaches the inner partition wall 16, heat is absorbed by the inner partition wall 16, and heat is accumulated in the inner partition wall 16. Since the soaking effect is present in the inner partition wall 16, the heat accumulated in the inner partition wall 16 is released in a planar shape along the side wall of the inner partition wall 16. Therefore, in the space inside the inner partition wall 16, a substantially constant temperature distribution is formed along the inner partition wall 16 at least along the width direction of the molten glass MG. By the substantially constant temperature distribution along the inner partition wall 16, the temperature of the molten glass MG becomes uniform in the width direction of the molten glass MG, and at the lowermost end portion 14d of the molded body 14, the temperature of the flat glass G is, for example, approximately 1150 ° C and became uniform in the width direction.

Further, the thermal conductivity of the internal partition 16 of the present embodiment is 20 W/(m.K) or more at 1200 ° C, more preferably 25 W/(m.K) or more, and still more preferably 30 W/(m.K). the above. Therefore, even if the temperature of each of the heat generating elements 28 is uneven depending on the place, the temperature of the inner partition wall 16 is less likely to be uneven in the width direction of the molten glass MG, and the temperature is liable to change in the width direction of the molten glass MG. Evenly. That is, the soaking effect of the inner partition wall 16 can be increased, and the temperature of the molten glass MG flowing to the molded body 14 can be increased to the molten glass MG. More uniform cooling in the width direction improves the quality of the glass substrate.

The environment between the furnace wall 24 and the internal partition wall 16 in the forming furnace chamber 30 is maintained at a desired temperature by the heating element 28. On the other hand, the molten glass MG flowing in the molded body 14 must gradually decrease in temperature accompanying the flow down.

In the present embodiment, a horizontal partition wall 26 that partitions the forming furnace chamber 30 into a plurality of spaces adjacent to each other is provided between the furnace wall 24 of the forming furnace chamber 30 and the internal partition wall 16. A plurality of heat generating bodies 28 are provided in a plurality of spaces partitioned by the horizontal partition walls 26, and each of the heat generating bodies 28 can independently control the amount of heat generation. The horizontal partition wall 26 is made of a material having a high heat insulating property, for example, a material having a higher heat insulating property than the inner partition wall 16. Thereby, the temperature of the inner partition wall surface of the opposing surface of the molten glass flowing down the surface of the molded body can be arbitrarily changed in the downward flow direction, and the required temperature difference can be added to the molten glass below the flow of the molten glass. Can improve the quality of the glass substrate. Further, in order to add a required temperature difference to the molten glass below the flow, the temperature measured by a temperature sensor (not shown) such as a temperature measuring resistor or a thermocouple provided in the forming furnace chamber 30 may be used. The heat generated by the heating element 28 is adjusted. For example, when the temperature measured by the temperature sensor is the same on both side faces 14b, 14b and the inclined surface 14c of the molded body 14, the heat generating body 28 located at a position opposed to the both side faces 14b, 14b is increased. The amount of heat generated or the amount of heat generated by the heat generating body 28 located at a position facing the inclined surface 14c is increased, and a temperature difference can be added to the molten glass MG flowing between the both side faces 14b and 14b and the inclined surface 14c in the downward direction.

The manufacturing method of this embodiment is suitable for the case where it is necessary to maintain the inside of the forming furnace at a high temperature. Specifically, it is suitable for a case where the inside of the forming furnace is 1000 ° C or higher, and is more suitable for the case of 1200 ° C or higher, and particularly suitable for the case of 1300 ° C or higher.

When a glass substrate is produced using a glass having a high temperature viscosity (molten glass), it is necessary to maintain the inside of the forming furnace at a high temperature. Therefore, the present embodiment is suitable for producing glass using glass having a high viscosity and high viscosity (molten glass). When the substrate is used. Specifically, in the present embodiment, when a glass substrate is produced using glass (molten glass) having a viscosity of glass (melted glass) of 10 ⁵ poise and 1000 ° C or more. Further, the upper limit of the temperature of the molten glass at a viscosity of 10 ⁵ poise is, for example, 1700 °C.

Further, since the alkali-free glass or the glass containing a trace amount of an alkali metal has a high temperature viscosity, the present embodiment is suitable for producing a glass substrate composed of an alkali-free glass or a glass containing a small amount of alkali. As an example of the alkali-free glass, the glass substrate of the following composition range is shown by mass %.

SiO ₂ : 50 to 70%, Al ₂ O ₃ : 0 to 25%, B ₂ O ₃ : 1 to 15%, MgO: 0 to 10%, CaO: 0 to 20%, SrO: 0 to 20%, BaO: 0 to 10%, RO: 5 to 30% (wherein R is a combination of Mg, Ca, Sr, and Ba) of alkali-free glass.

Further, as described above, the glass substrate may be a glass containing a trace amount of an alkali metal containing a trace amount of alkali. In the case of containing an alkali metal, the total content of R' ₂ O is preferably 0.10% or more and 0.5% or less, preferably 0.20% or more and 0.5% or less (wherein R' is selected from the group consisting of Li, Na, and K. At least one of them is a glass substrate.) Of course, the total of R' ₂ O may also be less than 0.10%. That is, the present invention is suitable for the case of producing a flat panel display using a glass substrate having an alkali-free glass or a trace amount of alkali.

The embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described above, and various modifications and changes can be made without departing from the spirit and scope of the invention.

[Examples]

A glass substrate was produced using the glass substrate manufacturing apparatus described in the above embodiment. As the internal partition, the content of SiC used is 99 wt%, and the thermal conductivity is High density sintered SiC at 25 W/(m.K) at 1200 ° C and an open porosity of 1%.

Within two years after the start of the use of the internal partition, there is no case where deformation due to oxidative expansion of the internal partition wall occurs, and the glass substrate can be stably produced.

A glass substrate was produced using the apparatus for manufacturing a glass substrate described in the above embodiment. As the internal partition, sintered SiC having a high content density of 98 wt% of SiC, a heat conductivity of 30 W/(m.K) at 1200 ° C, and an open porosity of 0.6% was used.

A glass substrate was produced using the apparatus for manufacturing a glass substrate described in the above embodiment. As the internal partition, sintered SiC having a high content of SiC of 95% by weight, a thermal conductivity of 35 W/mK at 1200 ° C, and an open porosity of 0.5% was used.

After three years from the start of the use of the internal partition, no deformation was observed due to oxidative expansion of the internal partition, and the glass substrate was stably produced.

[Comparative example]

The internal partition was made of a nitrogen-niobium bond SiC having a SiC content of 74 wt%, a thermal conductivity of 12.6 W/(m.K) at 350 ° C, and an open porosity of 14.6%. A glass substrate was produced in the same manner.

About 18 months after the start of the use of the internal partition wall, the deformation due to the oxidative expansion of the internal partition wall becomes large to the extent that it is unacceptable, and the frequency of about 30% is required to generate the internal partition.

Based on the above results, the effects of the above embodiments are clear.

14‧‧‧Formed body

14b‧‧‧ side

14c‧‧‧ sloped surface

14d‧‧‧Bottom

16‧‧‧Internal partition

18‧‧‧ Groove Department

20‧‧‧Parts

22‧‧‧Cooling roller

24‧‧‧ furnace wall

26‧‧‧ horizontal partition

28‧‧‧heating body

30‧‧‧Forming furnace room

300‧‧‧Forming device

G‧‧‧ flat glass

MG‧‧‧ molten glass

Claims (5)

A method for producing a glass substrate, comprising: forming a molten glass into a flat glass by a down-draw method; and providing a heating element, a molded body, and a heat separating body and the molded body in the forming furnace chamber; In the inner partition wall, the inner partition wall is a SiC sintered body having an open porosity of 1% or less, and the molten glass flowing through the molded body is heated by the heat generating body and interposed between the inner partition walls, and the inner partition The thermal conductivity of the partition wall is 20 W/(m.K) or more at 1200 ° C, and the SiC content of the SiC sintered body is 95% by weight or more. The method of producing a glass substrate of the requested item 1, wherein when the melt viscosity of the glass based on ¹⁰⁵ poises (Poise) less than 1000 ℃. The method for producing a glass substrate according to claim 1 or 2, wherein the glass substrate is an alkali-free glass or a glass containing a trace amount of alkali. The method of manufacturing the glass substrate of claim 1 or 2, wherein the space between the furnace wall of the forming furnace chamber and the inner partition wall is partitioned into a plurality of small spaces adjacent to each other by a horizontal partition wall, and in the small space Each of the heat generating bodies is disposed. The method for producing a glass substrate according to claim 4, wherein the temperature of the wall surface facing the side of the molded body of the inner partition wall is adjusted so as to proceed in a direction in which the molten glass flows, and the heat generating body is adjusted. Calorie.