JPWO2020009143A1 - Manufacturing method, manufacturing equipment and glass substrate for glass articles - Google Patents

Abstract

A melting step of producing the molten glass Gm, a transfer step of transferring the molten glass Gm by a transfer device 3 having a clarification tank 5 and a stirring pot 7, and a molding step of molding the transferred molten glass Gm by a molding means 4. In the step of introducing the molten glass Gm into the clarification tank 5, the molten glass Gm is blocked by a resistance member 16 arranged in the flow path 6 between the clarification tank 5 and the stirring pot 7. It is provided with a maintenance step of maintaining the liquid level height of the molten glass Gm in 5 at the liquid level height at the time of executing the transfer step and the molding step.

Description

The present invention relates to a method for manufacturing a glass article, and more particularly to a technique for bringing a transfer device having a clarification tank and a stirring pot into an appropriate state at the time of start-up before the start of operation.

As is well known, when manufacturing a glass article, a transfer device is used to supply the molten glass flowing out of the melting furnace to the molding device. This transfer device has a transfer container for transferring the molten glass.

As an example, Patent Document 1 discloses a transfer device including a clarification tank, a stirring pot, a cooling pipe, a pot, and the like in order from the upstream side as a transfer container. The transfer flow path, including these transfer vessels, is typically formed of a member made of a noble metal (eg, platinum or platinum alloy).

On the other hand, Patent Document 2 discloses that molten glass is introduced into a transfer container, a glass supply pipe 1, a clarification tank, a glass supply pipe 2, a stirring pot, and a glass supply pipe 3 in this order at the time of start-up. ing. Further, the document describes that in the process of introducing the molten glass into each of these transfer containers, the temperature rise control for raising the temperature of each transfer container to the operating temperature is performed.

Japanese Unexamined Patent Publication No. 2014-19629 JP-A-2017-178733

However, as disclosed in Patent Document 2, there is still a problem to be solved no matter how strict the temperature rise control for raising the temperature of each transfer container to the operating temperature at the time of startup is performed.

That is, among the transfer containers, the clarification tank can have the highest operating temperature. Along with this, the temperature of the clarification tank tends to be higher than that of other transfer containers even in the process in which the molten glass begins to be introduced at the time of startup. Therefore, in the process of introducing the molten glass into the clarification tank at the time of start-up, the clarification tank is in an empty-cooked state and oxidation is likely to occur. As a result, platinum foreign matter or the like may be mixed into the molten glass in the clarification tank, resulting in product defects or quality deterioration.

In addition, when considering the mixing of platinum foreign matter into the molten glass, in order to improve the quality of the glass substrate in particular, the form and amount of the platinum foreign matter contained in the glass substrate should be appropriately adjusted. It is important to do.

From the above viewpoint, the first object of the present invention is to create a state in which oxidation is unlikely to occur in the clarification tank in the process of introducing the molten glass into the clarification tank at the time of startup, and to mix foreign matter into the molten glass in the clarification tank. Is to be suppressed as much as possible. A second object of the present invention is to improve the quality of the glass substrate by appropriately adjusting the form and amount of the platinum foreign matter contained in the glass substrate.

The method according to the present invention, which was devised to solve the first problem, includes a melting step of heating and melting a glass raw material in a melting furnace to produce molten glass, and clarification arranged on the downstream side of the melting furnace. A transfer step of transferring the molten glass flowing out of the melting furnace to a molding means by a transfer device having a tank and a stirring pot arranged on the downstream side of the clarification tank, and the molding of the molten glass supplied from the transfer device. An introduction method for manufacturing a glass article including a molding step of molding into a predetermined shape by means, in which the molten glass flowing out of the melting furnace is introduced into the transfer device before the start of the transfer step and the molding step. The introduction step further comprises a step, in which the resistance member arranged in the flow path between the clarification tank and the stirring pot blocks the molten glass, thereby increasing the liquid level of the molten glass in the clarification tank. It is characterized by comprising a maintenance step of maintaining the glass at the liquid level at the time of execution of the transfer step and the molding step.

According to this method, the molten glass that has flowed out of the melting furnace and has begun to be introduced into the clarification tank in the introduction step at the time of start-up is blocked by a resistance member between the clarification tank and the stirring pot. Therefore, the molten glass is stored in the clarification tank on the upstream side of the resistance member, and the liquid level height of the molten glass in the clarification tank can be adjusted to the liquid level during operation (during the transfer process and the molding process) in a short time. Can be reached and maintained. As a result, it is possible to quickly prevent the clarification tank, which tends to have a higher temperature than other transfer containers even at the time of startup, from being in an empty cooking state. As a result, oxidation in the clarification tank is less likely to occur, and a situation in which devitrified foreign matter (platinum foreign matter or the like) is mixed in the molten glass can be efficiently avoided at a suitable place.

In this case, the resistance member is a gate that opens and closes the flow path, and by adjusting the opening degree of the flow path with the gate, the liquid level height of the molten glass in the clarification tank can be adjusted in the transfer step and the transfer step. It is preferable to maintain the liquid level at the time of executing the molding step.

In this way, it is possible to finely adjust the flow rate of the molten glass at the arrangement portion of the gate simply by providing a simple configuration in which the gate is slid (for example, up and down). Thereby, the degree of obstructing the flow of the molten glass can be easily variably controlled.

In the above method, in the maintenance step, it is preferable to transfer the molten glass in the clarification tank to the stirring pot and discharge it from the drain hole opened in the inner bottom surface of the stirring pot.

In this way, the molten glass in the clarification tank can be kept flowing at all times. As a result, the molten glass stays in the clarification tank for a long period of time and becomes boiled (cooked), which makes it difficult for the molten glass to change to foreign glass.

In the above method, it is preferable that the clarification tank in the maintenance step is filled with molten glass as in the clarification tank in the transfer step at the time of executing the molding step.

By doing so, since the vapor phase space is not formed in the clarification tank in either the maintenance step or the transfer step, it is possible to reduce the wear due to the volatilization of the noble metal constituting the clarification tank. In addition, it is possible to further reduce the generation of precious metal lumps caused by the precious metal volatilizing and then aggregating and mixing with the molten glass. In the present invention, when the clarification tank is filled with molten glass, the liquid level height of the molten glass in the clarification tank is the height of the top of the inner surface of the clarification tank.

In the above method, the temperature of the molten glass in the clarification tank in the maintenance step is preferably lower than the temperature of the molten glass in the clarification tank in the transfer step at the time of executing the molding step.

By doing so, the flow rate of the molten glass in the maintenance step is lowered, and the flow rate of the molten glass flowing out of the clarification tank per unit time can be reduced.

The apparatus according to the present invention, which was devised to solve the first problem, includes a melting furnace for producing molten glass by heating and melting a glass raw material, a clarification tank arranged on the downstream side of the melting furnace, and the above. A transfer device having a stirring pot arranged on the downstream side of the clarification tank and transferring the molten glass flowing out of the melting furnace, and a molding means for molding the molten glass supplied from the transfer device into a predetermined shape. It is a glass article manufacturing apparatus provided, and is characterized in that a resistance member is further provided in a flow path between the clarification tank and the stirring pot in order to block the molten glass flowing out from the melting furnace.

According to the device having such a configuration, oxidation in the clarification tank is less likely to occur, and devitrified foreign matter (platinum foreign matter, etc.) is efficiently mixed in the molten glass in the same place as in the above-mentioned method. It can be avoided.

In this case, the resistance member is preferably a gate that opens and closes the flow path.

Even in this case, the degree of obstruction of the flow of the molten glass can be easily variably controlled only by providing a simple configuration in which the gate is slid in the same manner as in the above-described method.

In this device, the gate can be inserted and removed through an opening provided in the upper part of the peripheral wall forming the flow path so that the lid covers the opening when the gate is removed. It is preferable to configure the above.

In this way, when the gate is removed, it is possible to avoid the harmful effects that may occur due to the opening of the opening. Specifically, even if tin oxide or the like remaining in the molten glass of the flow path (inside the peripheral wall) volatilizes during the transfer step and the molding step, the vicinity of the opening is always maintained at a high temperature. It is possible to prevent the volatile matter from liquefying or solidifying and adhering to the inner surface near the opening. Therefore, it is possible to appropriately prevent the adhered volatile matter from falling into the molten glass and becoming a foreign substance. Further, since the amount of heat radiated from the opening is significantly reduced, the effect of preventing devitrification of the molten glass near the liquid surface can be obtained. As a result, it is possible to improve the quality of the glass article as a product or the product yield.

Further, in this device, it is preferable that the lid body has a vent flow path for discharging the gas existing in the flow path.

In this way, the gas existing in the flow path (mainly the vaporized vaporized glass) is positively released to the outside through the vent flow path. Therefore, this gas flows in the vent flow path preferentially over the gap along the lower surface of the lid. As a result, it is possible to avoid the harmful effects that may occur when the flow rate of the gas flowing out from the gap along the lower surface of the lid is large. As an example of this adverse effect, the periphery of the opening on the outer peripheral side of the peripheral wall is covered with a refractory material, and a cooling pipe for cooling the electrode for energizing and heating the peripheral wall is provided around the periphery. Therefore, the gas flowing out from the gap along the lower surface of the lid may erode the refractory and hit the cooling pipe. When such a situation occurs, the cooling pipe may be damaged or damaged due to corrosion due to oxidation. On the other hand, by providing the vent flow path, a small amount of gas can be discharged from the gap along the lower surface of the lid, so that damage to the cooling pipe can be suppressed.

Further, in this device, the lid has a side wall portion that surrounds the space above the opening from the outer peripheral side and a ceiling wall portion that covers the upper side of the side wall portion, and the outlet of the vent flow path is provided. It is preferably provided on the side wall portion.

By doing so, it is possible to effectively avoid the situation where the volatile matter adhering to the vent flow path falls into the molten glass and becomes a foreign substance. More specifically, since the temperature of the vicinity of the outlet of the vent flow path is lowered due to the influence of the outside air, volatile substances such as tin oxide contained in the gas adhere to the inner peripheral surface of the outlet. It is easy and agglomeration of volatile substances after adhesion is likely to occur. Therefore, if the outlet of the vent flow path is formed on the ceiling wall, the volatile matter adhering to the inner peripheral surface of the outlet falls vertically downward with the passage of time and enters the molten glass. It may be mixed as a foreign substance. On the other hand, by providing the outlet of the vent flow path on the side wall, the volatile matter adhering to the inner peripheral surface of the outlet is less likely to fall vertically downward and is mixed as foreign matter in the molten glass. The probability of being done becomes smaller.

The glass substrate according to the present invention, which was devised to solve the second problem, has one platinum foreign substance having a ratio of a major axis dimension to a minor axis dimension of 15 or more and a major axis dimension of 3 μm or more. It is characterized by being less than / kg.

This glass substrate was obtained as a result of intensive research by the present inventor, and found the form and content of platinum foreign matter, which is the most important cause of quality deterioration. Therefore, this glass substrate is of extremely high quality as compared with the conventional glass substrate.

According to the present invention for solving the first problem, in the process of introducing the molten glass into the clarification tank at the time of startup, a state in which oxidation is unlikely to occur in the clarification tank is created, and the molten glass in the clarification tank is formed. Contamination of foreign matter is suppressed as much as possible. According to the present invention for solving the second problem, the form and amount of the platinum foreign matter contained in the glass plate become appropriate, and the quality of the glass plate can be improved.

It is a schematic side view which shows the whole structure of the manufacturing apparatus for carrying out the manufacturing method of the glass article which concerns on embodiment of this invention. It is a longitudinal side view which shows the transfer apparatus which is the main part of the manufacturing apparatus for carrying out the manufacturing method of the glass article which concerns on embodiment of this invention. It is a schematic vertical sectional side view of the main part which shows the state at the time of startup in the manufacturing apparatus for carrying out the manufacturing method of the glass article which concerns on embodiment of this invention. It is a schematic longitudinal front view of a main part cut along the line AA of FIG. It is a schematic vertical sectional side view of the main part which shows the state at the time of startup in the manufacturing apparatus for carrying out the manufacturing method of the glass article which concerns on embodiment of this invention. It is a perspective view which shows the superstructure of the attachment tank which is a component of the manufacturing apparatus for carrying out the manufacturing method of the glass article which concerns on embodiment of this invention. It is a perspective view which shows the 1st example of the superstructure of the attachment tank which is a component of the manufacturing apparatus for carrying out the manufacturing method of the glass article which concerns on embodiment of this invention. It is a vertical sectional front view cut according to line BB of FIG. It is a perspective view which shows an example of the lid used in the 1st example of the superstructure of the attachment tank which is a component of the manufacturing apparatus for carrying out the manufacturing method of the glass article which concerns on embodiment of this invention. It is a perspective view which shows the other example of the lid used in 1st example of the superstructure of the attachment tank which is a component of the manufacturing apparatus for carrying out the manufacturing method of the glass article which concerns on embodiment of this invention. It is a longitudinal front view for demonstrating the problem of the 1st example of the superstructure of the attachment tank which is a component of the manufacturing apparatus for carrying out the manufacturing method of the glass article which concerns on embodiment of this invention. It is a side view of the whole attachment tank for demonstrating the problem of the superstructure of the attachment tank which is a component element of the manufacturing apparatus for carrying out the manufacturing method of the glass article which concerns on embodiment of this invention. It is a perspective view which shows the 2nd example of the superstructure of the attachment tank which is a component of the manufacturing apparatus for carrying out the manufacturing method of the glass article which concerns on embodiment of this invention. It is a vertical sectional front view cut along the line CC of FIG. It is a vertical sectional front view which shows the 3rd example of the superstructure of the attachment tank which is a component of the manufacturing apparatus for carrying out the manufacturing method of the glass article which concerns on embodiment of this invention. It is a vertical sectional front view which shows the 4th example of the superstructure of the attachment tank which is a component of the manufacturing apparatus for carrying out the manufacturing method of the glass article which concerns on embodiment of this invention. It is a perspective view which shows the 5th example of the superstructure of the attachment tank which is a component of the manufacturing apparatus for carrying out the manufacturing method of the glass article which concerns on embodiment of this invention. It is a vertical sectional front view cut according to the DD line of FIG. It is a perspective view which shows the glass plate which concerns on embodiment of this invention.

Hereinafter, a method for manufacturing a glass article, a manufacturing apparatus, and a glass plate according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[Manufacturing method and equipment for glass articles]
FIG. 1 illustrates an apparatus for manufacturing a glass article according to the present invention. As shown in the figure, the manufacturing apparatus 1 is roughly divided into a melting furnace 2 which is deployed at the upstream end and heats and melts the glass raw material, and a molten glass Gm flowing out from the melting furnace 2 is transferred toward the downstream side. The transfer device 3 is provided, and the forming means 4 for forming the molten glass Gm supplied from the transfer device 3 into a strip-shaped flat glass Gp is provided.

The transfer device 3 includes a clarification tank 5, an attachment tank 6 attached to the clarification tank 5, a plurality of (two in the example) stirring pots 7 and 8, and a cooling pipe 9 in order from the upstream side as a transfer container. , With a pot 10. Each of these transfer containers 5 to 10 includes an inflow port into which the molten glass Gm flows in and an outflow port into which the molten glass Gm flows out.

More specifically, the clarification tank 5 removes air bubbles in the molten glass, and an attached tank 6 is connected to the downstream side of the clarification tank 5. On the downstream side of the attachment tank 6, a first stirring pot 7 on the upstream side and a second stirring pot 8 on the downstream side for homogenizing the molten glass Gm are arranged. Stirrers 7x and 8x rotating around the axis are housed in the stirring pots 7 and 8 during the operation of the manufacturing apparatus 1, respectively. A cooling pipe 9 is arranged adjacent to the downstream side of the second stirring pot 8, and a pot 10 as a volume portion mainly for adjusting the viscosity of the molten glass Gm is arranged adjacent to the downstream side of the cooling pipe 9. Has been done. The downstream side of the cooling pipe 9 is inclined upward.

The molding means 4 includes a molded body 11 that is formed by flowing molten glass Gm down by an overflow down draw method, and a large-diameter introduction pipe 12 that guides the molten glass Gm to the molded body 11. The molten glass Gm is supplied to the introduction pipe 12 from the pot 10 of the transfer device 3.

FIG. 2 is an enlarged vertical sectional view of the transfer device 3. As shown in the figure, the outlet 2b of the melting furnace 2 communicates with the inlet 5a of the clarification tank 5 via the upstream connecting pipe 13. Although not shown, a vent is provided on the upper surface portion 5n of the clarification tank 5 mainly for discharging gas generated from bubbles in the molten glass. The outlet 5b of the clarification tank 5 overlaps with the inlet 6a of the attachment tank 6 and communicates with the inlet 5b. The outflow port 6b of the attachment tank 6 communicates with the inflow port 7a of the first stirring pot 7 via the intermediate connection pipe 14. The inflow port 7a of the first stirring pot 7 is provided in the upper part of the peripheral wall thereof. The outflow port 7b of the first stirring pot 7 communicates with the inflow port 8a of the second stirring pot 8 via the downstream connecting pipe 15. The outflow port 7b of the first stirring pot 7 is provided in the lower part of the peripheral wall thereof, and the inflow port 8a of the second stirring pot 8 is provided in the upper part of the peripheral wall thereof. These stirring pots 7 and 8 are arranged at the same height. The downstream side of the downstream connecting pipe 15 is inclined upward. The outlet 8b of the second stirring pot 8 overlaps with and communicates with the inlet 9a of the cooling pipe 9. The outlet 8b of the second stirring pot 8 is provided at the lower part of the peripheral wall thereof. The downstream side of the cooling pipe 9 is inclined upward. The outlet 9b of the cooling pipe 9 overlaps with and communicates with the inlet 10a of the pot 10. The pot 10 has an upper large diameter portion 10x and a lower small diameter portion 10y. The inflow port 10a of the pot 10 is provided on the peripheral wall of the large diameter portion 10x, and the outflow port 10b is provided at the lower end of the small diameter portion 10y. The small diameter portion 10y of the pot 10 is inserted into the introduction pipe 12 of the molding means 4. The lower end of the small diameter portion 10y is immersed in the molten glass Gm in the introduction pipe 12.

In the transfer flow path composed of the transfer containers 5 to 10 and the connection pipes 13 to 15 described above, at least the portion in contact with the molten glass Gm (in this embodiment, the entire inner surface of the transfer flow path) is a thin-walled noble metal (in this embodiment). For example, it is made of a member made of platinum or a platinum alloy). The perimeter of these members is covered with a refractory material (not shown). The transfer flow path is energized and heated, and the temperature can be adjusted for each of the transfer containers 5 to 10 and the connection pipes 13 to 15.

The manufacturing apparatus 1 having the above configuration executes the following steps. That is, the method for producing a glass article according to the present invention includes a melting step of heating and melting a glass raw material in a melting furnace 2 to generate molten glass Gm, and a molding means for molding the molten glass Gm flowing out of the melting furnace 2 by a transfer device 3. It includes a transfer step of transferring to 4 and a molding step of molding the molten glass Gm supplied from the transfer device 3 into a predetermined shape by the molding means 4. This manufacturing method further includes an introduction step of introducing the molten glass Gm flowing out of the melting furnace 2 into the transfer device 3 before the start of the transfer step and the molding step (at the time of start-up before the start of operation). In this introduction process, the following is performed.

3 and 4 illustrate a state in which the molten glass Gm does not flow out from the melting furnace 2 to the transfer device 3 and the molten glass Gm does not exist in the transfer device 3 before the start of the transfer process. As shown in each of these figures, a gate 16 as a resistance member is inserted in the attached tank 6. The gate 16 plays a role of obstructing the flow of the molten glass Gm. In this case, the gap 17 between the bottom surface portion 16 m of the gate 16 and the bottom surface portion 6 m of the attached tank 6 is a passage (narrowed passage) through which the molten glass Gm flows. The gate 16 moves up and down by an elevating mechanism (not shown) to open and close the attached tank 6 and adjust the opening degree of the attached tank 6. As a result, the gate 16 can adjust the flow rate of the molten glass Gm. A thin plate 18 made of platinum or a platinum alloy is attached to the front surface portion 16a and the back surface portion 16b of the refractory forming the gate 16, the side surface portions 16c, and the bottom surface portion 16m. The gate 16 has a U shape from both side surface portions 16c to the bottom surface portion 16m.

The clarification tank 5 has a pipe shape. The attached tank 6 has a pipe shape, but only the portion where the gate 16 is inserted has a U shape as shown in FIG. The flow path area of the clarification tank 5 is larger than the flow path area of the attachment tank 6, and the flow path area of the attachment tank 6 is larger than the flow path area of the intermediate connection pipe 14. Specifically, the lowest portion of the lower surface portion 5 m of the clarification tank 5, the lowest portion of the lower surface portion 6 m of the attachment tank 6, and the lowest portion of the lower surface portion 14 m of the intermediate connection pipe 14 are at the same height position. The uppermost portion of the upper surface portion 5n of the clarification tank 5 is higher than the uppermost portion of the upper surface portion 6n of the attachment tank 6, and the uppermost portion of the upper surface portion 6n of the attachment tank 6 is the highest portion of the upper surface portion 14n of the intermediate connection pipe 14. Higher than the top.

In the introduction step of this embodiment, first, a temperature raising step of individually raising the temperature of each of the transfer containers 5 to 10 and each of the connecting pipes 13 to 15 which are components of the transfer device 3 and each transfer container 5 which has undergone the temperature raising step are performed. A connection step of connecting 10 to 10 and each of the connecting pipes 13 to 15 and connecting the melting furnace 2 and the transfer device 3 is executed. After that, the molten glass Gm is discharged from the melting furnace 2 toward the downstream side and introduced into the transfer device 3.

FIG. 5 illustrates a state in which the molten glass Gm flowing out of the melting furnace 2 is introduced into the clarification tank 5 and then flows into the first stirring pot 7 and is discharged (first inflow step). In this state, the stirring blade 7x is removed from the first stirring pot 7 (the same applies to the stirring blade 8x of the second stirring pot 8).

As an initial stage, the molten glass Gm flowing out of the melting furnace 2 passes through the upstream connecting pipe 13 and flows into the clarification tank 5. Immediately after this inflow, the liquid level height of the molten glass Gm in the clarification tank 5 is low. Therefore, the molten glass Gm passes around the lower surface portion 6 m of the clarification tank 5 and flows into the attached tank 6. The molten glass Gm that has flowed into the attached tank 6 is blocked by the gate 16 and blocked. As a result, the molten glass Gm is stored on the upstream side of the gate 16. Then, as shown in FIG. 5, the inside of the clarification tank 5 is filled with the molten glass Gm in a short time (maintenance step).

Since the molten glass Gm reaches the maximum temperature in the clarification tank 5 of the transfer device 3 at the time of executing the transfer step and the molding step, the molten glass Gm is kept in the clarification tank 5 even in the introduction step before the start of the transfer step. Must be the maximum temperature. In the introduction step, the temperature of the molten glass Gm in the clarification tank 5 is, for example, 1500 to 1650 ° C. Therefore, the clarification tank 5 is most likely to be oxidized in the transfer device 3. However, after the molten glass Gm begins to flow into the clarification tank 5, the clarification tank 5 is filled with the molten glass Gm in a short time. Therefore, the oxidation of the clarification tank 5 can be suppressed. As a result, it is possible to avoid a situation in which foreign matter such as platinum lumps is mixed in the molten glass Gm in the clarification tank 5. The portion of the attached tank 6 on the upstream side of the gate 16 is also filled with the molten glass Gm in the same manner.

The molten glass Gm that has passed through the gate 16 flows into the first stirring pot 7 via the downstream portion of the attachment tank 6 and the intermediate connecting pipe 14. Then, the molten glass Gm is discharged downward through the drain hole 7g opened in the inner bottom surface 7m of the first stirring pot 7. The molten glass Gm at this time is maintained at a low liquid level (lower than during operation) in the downstream portion of the attached tank 6, the intermediate connecting pipe 14, and the first stirring pot 7. In the introduction step, the temperature of the molten glass Gm of the intermediate connection pipe 14 and the first stirring pot 7 is, for example, 1200 to 1400 ° C. Therefore, since the intermediate connection pipe 14 and the first stirring pot 7 are less likely to be oxidized than the clarification tank 5, foreign substances such as platinum lumps are less likely to be mixed in, and even if they are generated, they are minor.

In this introduction step (maintenance step), the molten glass Gm is constantly discharged from the first stirring pot 7, so that the molten glass Gm always flows in the clarification tank 5. As a result, the molten glass Gm stays in the clarification tank 5 for a long period of time and is in a boiled state (cooked state), which makes it difficult for the molten glass Gm to be deteriorated into foreign glass.

In this introduction step (maintenance step), the temperature of the molten glass Gm in the clarification tank 5 is, for example, only 50 to 200 ° C. higher than the operating temperature during the period when the flow of the molten glass Gm is obstructed by the gate 16. It has been lowered. As a result, the flow rate of the molten glass Gm is reduced, and the flow rate of the molten glass Gm flowing out of the clarification tank 5 per unit time can be reduced.

In this embodiment, during the execution of the maintenance step, the centering step of centering the molded body 11 and the rough cutting machine (device for cutting glass) arranged below the molded body 11 is executed. .. This centering step takes, for example, 3 to 6 hours. Further, during the period during which the centering step is being executed, as shown in FIG. 5, the molten glass Gm continues to be discharged from the drain hole 7g of the first stirring pot 7 in a state where the clarification tank 5 is filled. Therefore, it is possible to avoid a situation in which foreign matter such as platinum lumps is mixed in the molten glass Gm in the clarification tank 5 during the centering step. In addition, it is possible to prevent the molten glass Gm from boiling and deteriorating in the clarification tank 5.

After that, as shown in FIG. 2, the gate 16 is removed from the attached tank 6 and the drain hole 7 g of the first stirring pot 7 is closed to stop the discharge of the molten glass Gm from the drain hole 7 g. Further, the transfer containers 5 to 10 and the connecting pipes 13 to 15 are heated to the operating temperature. As a result, the molten glass Gm flows into the molding means 4 through the second stirring pot 8, the cooling pipe 9, and the pot 10, and the molten glass Gm in the transfer containers 6 to 10 and the connecting pipes 14 and 15 during operation. It becomes the liquid level of (second inflow step). After that, the transfer process and the molding process (operation) are started.

Next, the structure of the portion of the attached tank 6 where the gate 16 is arranged will be described in detail. As shown in FIG. 6, a rectangular tubular portion 19 having a central axis along the vertical direction is attached to the upper portion of the peripheral wall 6A forming the attachment tank 6. An opening 20 for inserting and removing the gate 16 is provided at the upper end of the tubular portion 19. The opening 20 is covered with a lid when the gate 16 is removed (during the transfer step and the molding step).

Hereinafter, first to fifth examples of the upper portion of the tubular portion 19 of the attachment tank 6 will be described with reference to the drawings.

[First example]
FIG. 7 is a perspective view of a main part showing a first example of the superstructure of the tubular portion 19, and FIG. 8 is a vertical sectional front view cut along the line BB of FIG. As shown in each of these figures, the opening 20 at the upper end of the tubular portion 19 is covered with the lid 21. More specifically, the tubular portion 19 has a flange 22 at the upper end. The lid 21 can be easily attached and detached while covering the opening 20. The tubular portion 19 is made of platinum or a platinum alloy. The flange 22 is made of platinum or a platinum alloy or other metal. Here, in the illustrated example, the opening area of the opening 20 of the tubular portion 19 is substantially the same as the pipeline area of the tubular portion 19, but the former may be smaller than the latter. It can be large.

FIG. 9 is a perspective view showing the configuration of the lid 21. As shown in the figure, the lid 21 is composed of a plurality of refractories 24 (two in the example) and a thin plate 25 as a covering material made of platinum or a platinum alloy covering the refractories 24. To. The thin plate 25 is provided between the lower thin plate 25a that covers the lower surfaces of the two refractories 24, the outer peripheral thin plate 25b that covers the entire outer peripheral surface of the two refractories 24, and the two refractories 24. It has a partition thin plate 25c. Each of these thin plates 25a, 25b, 25c is integrated. As shown in FIG. 10, the two refractories 24 are separately covered with the lower thin plate 25a, the outer peripheral thin plate 25b, and the partition thin plate 25c, and the two partition thin plates 25c are brought into contact with each other so as to be separated from each other. It may be configured to be joined so that it cannot be separated. Further, the thin plate 25 may cover the entire surface including the upper surface of the refractory 24, or may cover only the lower surface of the refractory 24. The covering material is not limited to the thin plate 25, and may be a layer made of platinum or a platinum alloy formed by spraying the refractory material 24. Here, the refractory material 24 is, for example, a refractory material made of dense zircon, mullite, alumina-based, zirconia-based, or the like (the same applies to the “refractory material” described below).

According to the configuration according to the first example, the following effects are exhibited. While the transfer step and the molding step are being executed, the opening 20 of the tubular portion 19 in the attachment tank 6 is covered with the lid 21. Therefore, the harmful effects that may occur when the opening 20 is open are avoided. Specifically, even if tin oxide or the like remaining in the molten glass Gm in the attached tank 6 volatilizes, the vicinity of the opening 20 of the tubular portion 19 is always maintained at a high temperature, so that the volatile matter is liquefied. Alternatively, it can be prevented from solidifying and adhering to the inner surface near the opening 20. Therefore, it is possible to appropriately prevent the adhered volatile matter from falling into the molten glass Gm and becoming a foreign substance. Further, since the amount of heat radiated from the opening 20 is significantly reduced, the effect of preventing devitrification of the molten glass Gm in the vicinity of the liquid level GL can be obtained. As a result, it is possible to improve the quality of the glass article (glass plate) which is a product or the product yield.

Further, since the lower surface of the lid 21, which is a portion easily eroded, is covered with a thin plate (covering material) 25 made of platinum or a platinum alloy, erosion of the lid 21 is efficiently suppressed and durability is achieved. Can be improved. In this case, if the entire lid 21 is made of platinum or a platinum alloy, the cost will increase and the weight will increase. However, the cost can be reduced by covering the refractory 24 with a thin plate 25 made of platinum or a platinum alloy. And can contribute to weight reduction.

In the configuration according to the first example, as shown in an exaggerated manner in FIG. 11, there is a possibility that the internal gas may flow out through the gap 26 between the upper end of the tubular portion 19 and the lid 21. This gas is mainly vaporized vapor of the molten glass Gm, and contains a gas generated from bubbles in the molten glass Gm. When the gas flows out through the gap 26 as shown by the arrow a, the following adverse effects may occur. Strictly speaking, the periphery of the tubular portion 19 has a structure as shown in FIG. As shown in the figure, a peripheral wall flange 27 extending from the peripheral wall 6A to the outer peripheral side is formed on the upstream side of the tubular portion 19, and an electrode (not shown) for energizing and heating the peripheral wall 6A is formed on the peripheral wall flange 27. It is attached. Further, the peripheral wall flange 27 is equipped with a cooling pipe 28 in which a cooling liquid circulates in the pipe. Between the tubular portion 19 and the peripheral wall flange 27, a heat insulating brick 29 made of a refractory material is arranged so as to cover the outer peripheral side of the peripheral wall 6A. The peripheral wall flange 30, the cooling pipe 31, and the heat insulating brick 32 are similarly arranged on the downstream side of the tubular portion 19, and another heat insulating brick 33 is arranged on the outer peripheral side of the heat insulating brick 32 here. Has been done. In this case, the peripheral wall flange 27 on the upstream side is closer to the tubular portion 19 than the peripheral wall flange 30 on the downstream side. Therefore, as described above, the gas flowing out from the gap 26 between the upper end of the tubular portion 19 and the lid 21 in the direction of arrow a erodes the heat insulating brick 29 on the upstream side and the cooling pipe 28 on the upstream side. There is a risk of hitting. When such a situation occurs, since the gas has a high temperature, the cooling pipe 28 on the upstream side may be corroded by oxidation, and the coolant may leak out. If the gas flowing out from the gap 26 erodes a large amount of the heat insulating bricks 32 and 33 on the downstream side, the cooling liquid may leak out to the cooling pipe 31 on the downstream side due to corrosion or the like.

[Second example]
The second example avoids such a problem. FIG. 13 is a perspective view showing a second example of the superstructure of the tubular portion 19, and FIG. 14 is a vertical sectional front view cut along the line CC of FIG. As shown in each of these figures, the lid 21 is provided with a vent flow path 40. More specifically, the lid 21 has a rectangular flat plate-shaped base wall portion 41 that covers the opening 20 of the tubular portion 19, and a rectangular frame-shaped or rectangular square tubular side wall portion that is installed on the base wall portion 41. 42 and a rectangular flat plate-shaped ceiling wall portion 43 that covers the upper side of the side wall portion 42 are provided. The vent flow path 40 is composed of an inflow port 44, an internal space 45 leading to the inflow port, and an outflow port 46 communicating with the internal space 45. The inflow port 44 is a through hole formed in the central portion of the base wall portion 41. The internal space 45 is a space surrounded by the side wall portion 42 and the ceiling wall portion 43. The outlet 46 is a notch formed in an upper portion around the side wall portion 42 at one location. In this case, the inflow port 44 and the outflow port 46 are different in position in a plan view. Further, the central axis of the inflow port 44 is along the vertical direction, while the central axis of the outflow port 46 is along the horizontal direction. Therefore, the gas flow direction at the inflow port 44 is an upward direction (arrow c direction) substantially along the vertical direction, whereas the gas flow direction at the outflow port 46 is a lateral direction substantially along the horizontal direction. (Direction of arrow d).

Here, the base wall portion 41 has an inflow port 44 formed in the central portion of the lid 21 (see FIGS. 9 and 10) in the first example described above. In this case, the inner peripheral surface of the inflow port 44 is also covered with a platinum or platinum alloy covering material. Further, it is preferable that both the side wall portion 42 and the ceiling wall portion 43 are formed only of a refractory material, but at least a portion of the refractory material in contact with gas is covered with a platinum or platinum alloy covering material. You may. The opening area of the outflow port 46 is smaller than the opening area of the inflow port 44. The outlet 46 is not limited to one location around the side wall portion 42, and may be formed at a plurality of locations around the side wall portion 42.

According to the configuration according to the second example, the following effects are exhibited. The gas in the attached tank 6 flows into the internal space 45 from the inflow port 44 of the vent flow path 40 in preference to the gap 26, and then flows out from the outflow port 46 to the outside. Therefore, the amount of gas flowing out from the gap 26 is very small. Further, since the gas flow direction (d direction) at the outlet 46 is orthogonal to the upstream / downstream direction, the gas flowing out from the outlet 46 is collected from the upstream cooling pipe 28 and the downstream cooling pipe 31. It doesn't go in either direction. Due to these circumstances, the situation where the gas hits the cooling pipes 28 and 31 is avoided.

In this case, since the temperature of the inner peripheral surface of the outlet 46 is lowered due to the influence of the outside air, volatile substances such as tin oxide contained in the gas are liquefied or solidified on the inner peripheral surface. Easy to adhere. If the volatile matter adheres to the inner peripheral surface of the outlet 46, the volatile matter may fall over time. However, since the inflow port 44 and the outflow port 46 have different positions and gas flow directions in a plan view, the inflow port 44 does not exist in the path where the volatile matter falls, and the volatile matter is contained in the outflow port 46. It is received by the bottom of the peripheral surface and the upper surface of the base wall 41. Therefore, the volatile matter is prevented from falling into the molten glass Gm. Since the inner peripheral surface of the inflow port 44 is not easily affected by the outside air, it is maintained at a high temperature. Therefore, it is possible to prevent volatile substances such as tin oxide from adhering to the inner peripheral surface of the inflow port 44.

[Third example]
FIG. 15 is a vertical sectional front view showing a third example of the superstructure of the tubular portion 19. As shown in the figure, the configuration according to the third example is different from the configuration according to the second example described above in that the receiving member 47 is installed on the base wall portion 41 of the lid 21. is there. The receiving member 47 has a hanging portion 47a extending downward from the lower portion of the base wall portion 41, and a receiving portion 47b extending laterally (horizontally) from the lower end of the hanging portion 47a. The receiving portion 47b is arranged in the upper space of the liquid level GL of the molten glass Gm. The area of the receiving portion 47b (area in a plan view) is made larger than the opening area of the inflow port 44, and the inflow port 44 fits within the upper surface region of the receiving portion 47b in a plan view. Since the other configurations are the same as the configurations according to the second example described above, the components common to both examples are designated by the same reference numerals in FIG. 15 and the description thereof will be omitted. According to the configuration according to the third example, due to a large amount of volatile matter adhering to the inner peripheral surface of the inflow port 44, even if the volatile matter falls through the inflow port 44, the volatile matter is received by the receiving member 47. It is received by the stop 47b. Therefore, it is possible to more reliably prevent the situation where the volatile matter falls into the molten glass Gm and becomes a platinum foreign substance or the like. The other effects are substantially the same as those of the second example described above.

[4th example]
FIG. 16 is a vertical sectional front view showing a fourth example of the superstructure of the tubular portion 19. As shown in the figure, the configuration according to the fourth example is different from the configuration according to the second example described above at a position deviated from the central portion of the base wall portion 41 of the lid 21 to one side. The inflow port 44 is formed in the ceiling wall portion 43, and the outflow port 46 is formed at a position deviated from the central portion of the ceiling wall portion 43 to the other side. Therefore, the inflow port 44 and the outflow port 46 are different in position in a plan view. In this case, the gas flow direction at the inflow port 44 and the gas flow direction at the outflow port 46 are the same, and both are upward directions (arrow e direction and arrow f direction) substantially along the vertical line. Is. A notch is not formed in the side wall portion 42. Further, the internal space 45 of the vent flow path 40 is wider in the lateral direction than in the second example described above. Since the other configurations are the same as those in the second example described above, the components common to both examples are designated by the same reference numerals in FIG. 16 and the description thereof will be omitted. According to the configuration according to the fourth example, since the inflow port 44 and the outflow port 46 have different positions in a plan view, the inflow port 44 does not exist in the path where the volatile matter falls, and the volatile matter is the base. It is received by the upper surface of the wall portion 41. Therefore, the volatile matter is prevented from falling into the molten glass Gm. Further, since the gas flowing out from the outflow port 46 goes upward (in the direction of arrow f) immediately after the outflow, it is possible to reliably prevent the gas from hitting the cooling pipes 28 and 31.

[Example 5]
FIG. 17 is a vertical sectional front view showing a fifth example of the superstructure of the tubular portion 19, and FIG. 18 is a vertical sectional front view cut along the DD line of FIG. In the configuration according to the fifth example, the lid 21 has a rectangular frame-shaped or rectangular tubular side wall portion 42 arranged on the flange 22, and a rectangular flat plate-shaped ceiling wall portion that covers the upper side of the side wall portion 42. It includes 43. The ceiling wall portion 43 has the same configuration as the lid 21 (see FIGS. 9 and 10) in the first example described above. The vent flow path 40 is composed of an internal space 45 and an outflow port 46. The internal space 45 is a space surrounded by the side wall portion 42 and the ceiling wall portion 43. The outlet 46 is a notch formed in an upper portion around the side wall portion 42 at one location. According to the configuration according to the fifth example, the gas in the attachment tank 6 passes through the internal space 45 of the vent flow path 40 in preference to the gap 26 between the upper end of the tubular portion 19 and the side wall portion 42. Then, it flows out from the outlet 46 to the outside. In this case, even if the volatile matter adhering to the inner peripheral surface of the outlet 46 falls, the volatile matter is at the bottom of the inner peripheral surface of the outlet 46 or the upper end surface of the tubular portion 19 (upper surface of the flange 22 or the like). It will be accepted. Therefore, the volatile matter is prevented from falling into the molten glass Gm. In this case, the space above the opening 20 (internal space 45) is maintained at a high temperature because it is surrounded by the side wall portion 42 and the ceiling wall portion 43. Therefore, the vicinity of the opening 20 is in a state in which volatile substances such as tin oxide are unlikely to adhere and aggregation of the volatile substances after the adhesion is unlikely to occur. As a result, adhesion or aggregation of volatile substances to the vicinity of the opening 20 can be avoided, and a situation in which the volatile substances fall into the molten glass Gm from the inner surface near the opening 20 can be prevented. The reason why the gas flowing out from the outlet 46 is difficult to hit the cooling pipes 28 and 31 is substantially the same as that of the second example (see FIG. 14) described above.

Next, an embodiment of the glass substrate according to the present invention will be described.

[Glass substrate]
The present inventor obtained a large number of glass substrates by using the manufacturing apparatus and manufacturing method having the above configuration. Furthermore, the present inventor has focused on the morphology and amount of the platinum foreign matter contained in those glass substrates, and found a high-quality glass substrate Gpx as shown in FIG. 19 from among those glass substrates. In this high-quality glass substrate Gpx, the ratio of the major axis dimension to the minor axis dimension is 15 or more, and the number of platinum foreign substances having the major axis dimension of 3 μm or more is 1 piece / kg or less. In this case, the number of the platinum foreign substances is preferably 0.05 pieces / kg or less, and more preferably 0.01 pieces / kg or less. The lower limit of the number of platinum foreign substances may be, for example, 0.0001 / kg or more. According to the research results by the present inventor, when a large number of glass substrates are obtained by using a conventional manufacturing apparatus or manufacturing method, the number of the above-mentioned platinum foreign substances contained in the glass substrates is a good quality glass substrate. Also, it was about 3 pieces / kg. On the other hand, when a large number of glass substrates are obtained by using the manufacturing apparatus and manufacturing method according to the present invention, the number of the above-mentioned platinum foreign substances contained in those glass substrates is as long as it is the best glass substrate. It was 0.0005 pieces / kg.

This glass substrate can be used for flat panel displays such as liquid crystal displays and organic EL displays, organic EL lighting, solar cells, and the like. The thickness of the glass substrate is, for example, 0.01 to 10 mm, preferably 0.1 to 3 mm, more preferably 0.2 mm to 1.8 mm, and even more preferably 0.2 mm to 0.5 mm. is there. The glass substrate has a rectangular shape, and the lengths of the short side and the long side are preferably 1100 mm or more, and more preferably 2200 mm or more.

The glass substrate is made of, for example, alkali-free glass, soda glass, soda-lime glass, borosilicate glass, aluminosilicate glass, and alkali-containing glass. When the glass substrate is made of non-alkali glass, for example, in mass%, SiO ₂ 50 to 70%, Al ₂ O ₃ 12 to 25%, B ₂ O _{30 to} 12%, Li ₂ O + Na ₂ O + K ₂ O (Li) ₍ Total amount of 2 O, Na ₂ O and K ₂ O) A composition containing 0 to less than 1%, MgO 0 to 8%, CaO 0 to 15%, SrO 0 to 12%, and BaO 0 to 15% can be adopted.

It is preferable that both surfaces of the glass substrate are fire-made surfaces, that is, a glass substrate formed by the overflow downdraw method.

The present invention is not limited to the above embodiment, and various variations are possible as illustrated below.

In the above embodiment, the gate 16 is arranged in the attached tank 6, but the location where the gate 16 is arranged is any other place as long as it is a flow path between the clarification tank 5 and the first stirring pot 7. May be good.

In the above embodiment, the gate 16 is used as the resistance member. For example, a container having an inflow port on the peripheral wall and an outflow port on the bottom wall is arranged between the clarification tank 5 and the first stirring pot 7. , A configuration including a plunger for adjusting the amount of molten glass flowing out from the outlet (this configuration itself is well known) may be adopted, and the plunger may be used as a resistance member.

In the above embodiment, the resistance member 16 obstructs the flow of the molten glass Gm so that the molten glass Gm is filled in the clarification tank 5, but the liquid level height of the molten glass Gm in the clarification tank 5 is high. If the liquid level is equal to the liquid level during operation, it does not have to be filled.

In the above embodiment, the case where two stirring pots 7 and 8 are provided as the transfer container is illustrated, but even when three or more stirring pots are provided, only the drain hole of the stirring pot located on the most upstream side is used. The molten glass may be discharged from. Further, when having one stirring pot, the molten glass may be discharged from the drain hole of the stirring pot.

In the above embodiment, the start-up time before the start of operation after replacing the existing transfer device 3 has been described, but the start-up time after replacing the melting furnace 2 and the transfer device 3 or the start-up time after replacing the transfer device 3 and the transfer device 3 It may be at the time of start-up after exchanging the forming means 4, or at the time of starting up after exchanging the melting furnace 2, the transfer device 3, and the forming means 4. Further, it may be at the time of start-up after newly installing the melting furnace 2, the transfer device 3, and the molding means 4.

In the above embodiment, the molding means 4 molds the strip-shaped flat glass Gp, but it may be molded into another shape corresponding to the glass article.

In the above embodiment, the molten glass Gm is blocked by the resistance member 16 in the introduction step (maintenance step) before the start of the transfer step, and the molten glass Gm is stored in the clarification tank 5. , The resistance member 16 may be used to adjust the flow rate of the molten glass Gm of the transfer device 3. In other words, the transfer step may include a step of adjusting the flow rate of the transfer device 3 by the resistance member 16.

If the flow rate of the transfer device 3 is adjusted by using the resistance member 16 arranged in the flow path 6 between the clarification tank 5 and the stirring pot 7 as shown in FIG. 3, the inside of the clarification tank 5 is adjusted before and after the flow rate adjustment. The liquid level height of the molten glass Gm can be maintained. Therefore, it is possible to prevent the liquid level height of the molten glass Gm in the clarification tank 5 from decreasing and oxidation of the clarification tank 5 from occurring. Further, in order to adjust the flow rate of the transfer device 3, it is conceivable to arrange a resistance member on the downstream side of the stirring pot 7, for example, on the cooling pipe 9, but in this case, the resistance member, the molten glass Gm, and air are formed. Due to devitrification at the three-phase interface, streaks may occur on the glass ribbon Gr. On the other hand, if the flow rate of the transfer device 3 is adjusted by the resistance member 16 arranged in the flow path 6 between the clarification tank 5 and the stirring pot 7, it is possible to prevent the glass ribbon Gr from being streaked.

In the above embodiment, the lid 21 covering the opening 20 of the tubular portion 19 provided in the upper part of the attachment tank 6 is rectangular in a plan view, but may be elliptical or polygonal in a plan view. ..

1 Manufacturing equipment 2 Melting furnace 3 Transfer equipment 4 Molding means 5 Clarification tank 6 Flow path (attached tank)
6A peripheral wall
7 Stirring pot 7g Drain hole 7m Inner bottom surface 8 Stirring pot 9 Cooling pipe 11 Mold 16 Resistance member (gate)
Gm Fused glass 19 Cylindrical part 20 Opening part 21 Lid body 40 Vent flow path 42 Side wall part 43 Ceiling wall part 46 Outlet Gpx glass plate

Claims (11)

By a melting step of heating and melting a glass raw material in a melting furnace to produce molten glass, and a transfer device having a clarification tank arranged on the downstream side of the melting furnace and a stirring pot arranged on the downstream side of the clarification tank. A method for manufacturing a glass article, comprising a transfer step of transferring the molten glass flowing out of the melting furnace to a molding means and a molding step of molding the molten glass supplied from the transfer device into a predetermined shape by the molding means. hand,
Prior to the start of the transfer step and the molding step, an introduction step of introducing the molten glass flowing out of the melting furnace into the transfer device is further provided.
In the introduction step, the resistance member arranged in the flow path between the clarification tank and the stirring pot blocks the molten glass, so that the liquid level height of the molten glass in the clarification tank is changed to the transfer step. A method for producing a glass article, which comprises a maintenance step of maintaining the liquid level at the time of executing the molding step. The resistance member is a gate that opens and closes the flow path, and by adjusting the opening degree of the flow path with the gate, the liquid level height of the molten glass in the clarification tank can be adjusted in the transfer step and the molding step. The method for producing a glass article according to claim 1, wherein the liquid level is maintained at the liquid level at the time of execution. The glass article according to claim 1 or 2, wherein in the maintenance step, the molten glass in the clarification tank is transferred to the stirring pot and discharged from a drain hole opened in the inner bottom surface of the stirring pot. Production method. The clarification tank in the maintenance step is filled with molten glass, similarly to the clarification tank in the transfer step at the time of executing the molding step, according to any one of claims 1 to 3. Manufacturing method of glass articles. Any of claims 1 to 4, wherein the temperature of the molten glass in the clarification tank in the maintenance step is lower than the temperature of the molten glass in the clarification tank in the transfer step at the time of executing the molding step. The method for manufacturing a glass article according to. It has a melting furnace that heats and melts the glass raw material to produce molten glass, a clarification tank arranged on the downstream side of the melting furnace, and a stirring pot arranged on the downstream side of the clarification tank, and from the melting furnace. A glass article manufacturing apparatus including a transfer device for transferring the flowed molten glass and a molding means for molding the molten glass supplied from the transfer device into a predetermined shape.
An apparatus for manufacturing a glass article, characterized in that a resistance member is further provided in a flow path between the clarification tank and the stirring pot in order to block the molten glass flowing out of the melting furnace. The apparatus for manufacturing a glass article according to claim 6, wherein the resistance member is a gate that opens and closes the flow path. The gate can be inserted and removed through an opening provided in the upper part of the peripheral wall forming the flow path.
The apparatus for manufacturing a glass article according to claim 7, wherein the opening is covered with a lid when the gate is removed. The apparatus for manufacturing a glass article according to claim 8, wherein the lid body has a vent flow path for discharging gas existing in the flow path. The lid has a side wall portion that surrounds the space above the opening from the outer peripheral side, and a ceiling wall portion that covers the upper side of the side wall portion, and an outlet of the vent flow path is provided in the side wall portion. The apparatus for manufacturing a glass article according to claim 9. A glass substrate characterized in that the ratio of the major axis dimension to the minor axis dimension is 15 or more and the number of platinum foreign substances having a major axis dimension of 3 μm or more is 1 piece / kg or less.

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