JP2014069983A - Method and apparatus for producing glass substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress bubble formation in molten glass, vaporization of platinum, and thermal deformation of an apparatus made of platinum or a platinum alloy in production of a glass substrate.SOLUTION: An apparatus for producing a glass substrate includes a melting furnace for heating a raw glass material to produce molten glass, a molding device for molding a glass pane from the molten glass, and a pipe made of platinum or a platinum alloy that is installed between the melting furnace and the molding device and used to transfer or treat the molten glass. The pipe has a throughhole for leaking the molten glass. Firebricks are provided spaced apart from the outer periphery of the pipe. The apparatus for producing a glass substrate is used for producing the glass substrate.

Description

  The present invention relates to a glass substrate manufacturing method and a manufacturing apparatus for manufacturing a glass substrate.

Today, a semiconductor element such as a thin film transistor (TFT) is formed on a glass plate for a flat panel display. α-Si (amorphous silicon) TFT, p-Si (low temperature polysilicon) TFT and oxide semiconductor are formed on the glass substrate. For this reason, a non-alkali glass containing no alkali metal such as Li or K as a glass composition or a glass containing a trace amount of alkali even if contained is used so as not to affect the characteristics of the semiconductor element. Further, as the refining agent, As ₂ O ₃ has been generally used, but SnO ₂ or the like has been used from the viewpoint of environmental load in recent years.

  Such a glass substrate is generally manufactured through a process of forming molten glass from a glass raw material and then forming the molten glass into a glass substrate. The above process includes a clarification treatment for removing minute bubbles contained in the molten glass. In addition, the glass components are homogenized in order to reduce the non-uniformity of the glass composition, which is a cause of striae, by stirring the molten glass using a stirrer with respect to the molten glass after the refining process. Is included.

  A tube made of platinum or a platinum alloy is used as a clarification tube for performing the clarification treatment, a stirring tank for performing the homogenization treatment, and a glass conduit from the melting furnace to the forming apparatus through the clarification tube and the stirring tank. Is used. In tubes made of platinum or platinum alloys, if the hydrogen concentration on the inner surface of the tube is higher than the hydrogen concentration on the outer surface of the tube, hydrogen diffuses inside the platinum or platinum alloy of the tube and Move to the surface. As a result, oxygen is left inside the tube, and oxygen bubbles are easily formed in the molten glass. Since the bubbles remain on the glass substrate as the final product, the yield is lowered.

Under such circumstances, there is known a glass manufacturing apparatus and a glass manufacturing method that can prevent generation of bubbles in a glass region in the vicinity of a platinum container without incurring high costs (Patent Document 1).
In the manufacturing apparatus and the manufacturing method, in the glass manufacturing apparatus used for at least a part of the melting process, the clarification process, the supply process, the homogenization process, and the forming process, an electric current is provided outside the platinum container made of platinum or a platinum alloy. While providing a cast refractory, a platinum container and an electrocast refractory are closely attached through a glass layer.
That is, by making the platinum container and the electrocast refractory adhere to each other with the glass layer, the hydrogen permeation rate can be surely lowered and the joint of the electrocast refractory can be blocked. In this case, in order to form the glass layer, a gap is previously provided between the platinum container and the electroformed refractory, and then the gap is filled with glass powder and subjected to heat treatment.

Japanese Unexamined Patent Publication No. 2012-111667

  However, when the formation of the glass layer described in Patent Document 1 is used, the apparatus configuration itself is likely to be complicated because it is necessary to separately fill the glass powder. Further, it is impossible to prevent the platinum container from being deformed due to thermal expansion due to temperature rise. Furthermore, it is difficult to reliably fill glass powder into every corner of a complex platinum device. Once an unfilled void is formed, it does not perform its intended function. The container deforms and in the worst case breaks.

  Therefore, the present invention suppresses the generation of bubbles in the molten glass by a method different from the conventional method, suppresses the volatilization of platinum, and suppresses the deformation due to heat of the apparatus composed of platinum or a platinum alloy. An object of the present invention is to provide a glass substrate manufacturing apparatus and a glass substrate manufacturing method.

One embodiment of the present invention is a glass substrate manufacturing apparatus for manufacturing a glass substrate. The device is
A melting furnace for heating glass raw material to produce molten glass;
A molding apparatus for molding a glass plate from the molten glass;
A tube made of platinum or a platinum alloy, which is provided between the melting furnace and the molding apparatus and used for transferring or processing the molten glass;
Is provided.
The tube is provided with a through-hole for allowing the molten glass to leak, and a refractory brick spaced from the outer peripheral surface of the tube is provided on the outer periphery of the tube.
The refractory brick is preferably made of a refractory material having sufficient corrosion resistance with respect to the molten glass at the operating temperature of the pipe.
When manufacturing a glass substrate by flowing molten glass through the tube using the glass substrate manufacturing apparatus, the outer periphery of the tube is provided with the refractory bricks separated from the outer peripheral surface of the tube. The molten glass leaking from the through hole tends to accumulate between the tube and the refractory brick. Molten glass generally has a slower hydrogen permeation rate than platinum or platinum alloys. For this reason, it is difficult to form oxygen bubbles in the molten glass, which has been a problem in the past. Furthermore, since the platinum or platinum alloy in the tube comes into contact with the molten glass, the chance of contact with oxygen is extremely reduced, and volatilization of platinum can be prevented. In addition, since the inside of the tube and the outer periphery of the tube are maintained at substantially the same pressure by the through hole, the tube is not deformed and further is not damaged. Moreover, since the refractory brick is not in direct contact with and supported by the pipe as in the prior art, there is no breakage due to thermal distortion of the pipe.

It is preferable that the molten glass which the molten glass flowed through the pipe and leaked from the through hole is held in at least a part between the pipe and the refractory brick.
Since the molten glass is held between the tube and the refractory brick, the above-described effects of the molten glass accumulated on the outer periphery of the tube can be continuously exhibited during the production of the glass substrate. That is, during the production of the glass substrate, oxygen bubbles in the molten glass are hardly formed at all times, and further, volatilization of platinum can be continuously prevented, and damage due to thermal distortion of the tube is difficult.

It is preferable that the refractory brick is an electroformed brick containing zirconia.
Regarding the refractory brick, any material may be used as long as it has sufficient corrosion resistance to the molten glass at the temperature on the inner surface side of the refractory brick. For example, when the inner surface temperature of the refractory brick is 1580 ° C. or higher, a high zirconia electroformed brick having a zirconia content of 90% by mass or more is suitable. On the other hand, when the temperature on the inner surface side of the refractory brick is less than 1580 ° C., an alumina-zirconia electrocast brick can also be used. Furthermore, when the temperature on the inner surface side of the refractory brick is less than 1500 ° C., a mullite brick having an alumina content of 60% by mass or more and an electrofused mullite brick having an alumina content of 70% by mass or more are used. it can. Furthermore, when the temperature on the inner surface side of the refractory brick is less than 1400 ° C., a high alumina brick having an alumina content of about 50% by mass can be used. Of course, it is possible to use a high zirconia electroformed brick, which is the most excellent in corrosion resistance to molten glass, at all locations of the pipe, but the high zirconia electroformed brick is very expensive and abnormal. Due to thermal expansion, the manufacturing apparatus will be damaged if attention is not paid to the temperature rising / falling process when the temperature is raised and lowered. For this reason, it is more preferable to select the material of the said refractory brick according to the temperature of the inner surface of the said refractory brick from both sides of suppression of the investment amount of capital investment, and workability | operativity at the time of manufacture of a glass substrate.

A heat retaining member can be provided on the outside of the refractory brick as necessary.
When the tube is a tube corresponding to, for example, a step of rapidly cooling the molten glass, it is not necessary to provide the heat retaining member. However, when the tube is a tube that raises the temperature of the molten glass, maintains the temperature, or slowly cools the tube, the heat retaining member is provided. At this time, by providing the heat retaining member, even if the thermal conductivity of the refractory brick is high, the amount of heat released from the outer surface of the refractory brick is suppressed, and the temperature of the molten glass in the pipe is wasted energy. It can be adjusted to the target temperature without consumption.

Although the construction of the refractory brick is not particularly limited, the electrocast brick is a structure assembled by a plurality of blocks, and a portion other than the joint between the blocks is covered with the heat retaining member, and the block It is preferable that the joint portion in between is not covered with the heat insulating member and the joint portion is exposed. The portion other than the joint between the blocks is covered with the heat insulating member, and the joint portion between the blocks is exposed to the outside without being covered with the heat insulating member, so that the molten glass enters the joint. However, the molten glass that has entered solidifies due to heat dissipation by the refractory bricks around the joints and closes the joints. For this reason, molten glass can be prevented from flowing out to the outer periphery of the refractory brick.
In particular, it is suitable when a high zirconia electrocast refractory material containing 90% by mass or more of zirconia is used for the refractory brick. The thermal expansion of the high zirconia electrocast refractory material does not increase linearly as the temperature increases when the high zirconia electrocast refractory material is heated to a temperature of 1600 ° C. or higher, but 1100 to 1200 ° C. It exhibits a behavior called abnormal thermal expansion, in which it rapidly contracts once in the temperature region, and then resumes expansion in a higher temperature region. For this reason, when the refractory brick is composed of one integrally formed member, it is extremely difficult to raise the temperature so that cracks due to thermal strain do not occur, and an inappropriate rise is required. When temperature is applied, a crack (crack) due to thermal distortion may occur in the integrally formed electroformed refractory material. Further, the high zirconia electrocast refractory material integrally formed in the shape of the refractory brick is very expensive and expensive. However, the refractory brick can suppress the cost applied to the refractory brick by adopting a structure in which a plurality of blocks made of high zirconia electrocast refractory material are assembled, and the high zirconia electrocast refractory material It is difficult for cracks to occur.
On the other hand, when the high-alumina brick or the electrofused mullite brick is used, there is no abnormal expansion. Further, for example, since it is relatively easy and inexpensive to produce a brick having a cross-sectional shape (U-shaped), a configuration of a brick and a cover brick may be used instead of stacking a plurality of blocks.

The molten glass has a viscosity at a temperature of 1500 ° C. of 10 ^2.5 poise or more. Thereby, even if the refractory brick is an assembly of a plurality of blocks, it is possible to effectively suppress the seepage from the joints of the blocks.

  A hollow space is formed in advance between the pipe and the refractory brick. By forming the intermediate space, the molten glass can be collected and held in the hollow space.

  Further, a castable refractory may be filled in advance between the pipe and the refractory brick. Since the castable refractory is easily melted into the molten glass at a high temperature and enters a liquid state, the formation of oxygen bubbles is suppressed, the volatilization of platinum in the tube is prevented, and the deformation of the tube is prevented. it can. As the castable refractory, for example, alumina cement is used, but the molten glass produced by melting the molten glass and the alumina cement has a higher alumina concentration and higher viscosity than the glass composition of the original molten glass. Since it becomes glass, even if the refractory brick has joints, it is difficult to ooze from the joints.

Moreover, the molten glass (molten glass B) which is a composition different from the said molten glass (molten glass A) may be previously filled into at least one part between the said pipe | tube and the said refractory bricks.
The molten glass B is easily in a liquid state at a high temperature, and is mixed with the molten glass A to become a molten glass C having a new glass composition, thereby suppressing the formation of oxygen bubbles, preventing platinum volatilization and preventing deformation of the tube. Can be achieved. The composition of the new molten glass C is not particularly limited. For example, by selecting the viscosity at 1500 ° C. to be 10 ^3.0 poise or more, even if there is a joint in the refractory brick, the molten glass is removed from the joint. C bleeding can be effectively suppressed.

  Furthermore, the other one aspect | mode of this invention is a manufacturing method of a glass substrate which manufactures a glass substrate using the manufacturing apparatus of the said glass substrate. Also in the said manufacturing method, since the manufacturing apparatus of the said glass substrate is used, the production | generation of the bubble in molten glass can be suppressed. Moreover, volatilization of platinum can be suppressed. Deformation due to heat of a tube made of platinum or a platinum alloy can be suppressed.

  According to the manufacturing method and manufacturing apparatus of the glass substrate of the above-mentioned aspect, the production | generation of the bubble in molten glass can be suppressed. Moreover, according to the manufacturing method and manufacturing apparatus of the glass substrate of the above-mentioned aspect, it is possible to suppress the volatilization of platinum in a tube made of a constituent member containing platinum or a platinum alloy. According to the manufacturing method and the manufacturing apparatus of the glass substrate of the above-mentioned aspect, the deformation | transformation by the heat | fever of the pipe | tube comprised with platinum or a platinum alloy can be suppressed.

It is a figure which shows an example of the process of the manufacturing method of the glass substrate of this invention. It is a figure which shows typically an example of the apparatus which performs the melting process-cutting process in this embodiment. It is a figure explaining the structure before the preparatory process of the apparatus surrounding the glass supply pipe | tube used for the apparatus of this embodiment and this pipe | tube. It is a figure explaining the state after the preparatory process of the apparatus surrounding the glass supply pipe | tube used for the apparatus of this embodiment and this pipe | tube. It is a figure explaining the modification of this embodiment.

  Hereinafter, the manufacturing method and manufacturing apparatus of the glass substrate of this embodiment are demonstrated. FIG. 1 is a diagram showing an example of steps of a method for producing a glass substrate according to the present invention.

  The glass substrate manufacturing method includes a melting step (ST1), a preparatory treatment / clarification step (ST2), a homogenization step (ST3), a molding step (ST5), a slow cooling step (ST6), and a cutting step ( ST7). In the preparatory treatment / clarification step (ST2) and the homogenization step (ST3), molten glass is poured into a tube using platinum or a platinum alloy at least in part and melted from a melting furnace described later into a molding apparatus for molding a glass substrate. A supply process (ST4) for supplying glass is formed. In addition, a plurality of glass substrates that have a grinding process, a polishing process, a cleaning process, an inspection process, a packing process, and the like and are stacked in the packing process are transported to a supplier.

In the manufacturing method and the manufacturing apparatus of the glass substrate of this embodiment, the molten glass is poured into the glass supply pipe that connects between the melting furnace and the tube body of the clarification tank, and the through-hole provided in advance on the wall surface of the glass supply pipe A hollow space formed in advance between a glass supply pipe and a refractory support (refractory brick) provided on the outer periphery of the glass supply pipe. To hold. Moreover, in a supply process, the state which hold | maintains the leaked molten glass in the hollow space between a glass supply pipe and the refractory support body provided in the outer periphery of a glass supply pipe is maintained.
In the present embodiment, the object for causing the molten glass to leak and holding the molten glass in the hollow space formed between the refractory support and the support is the glass supply pipe. However, in the present invention, it is limited to the glass supply pipe. Not. For example, in a tube constituting a processing vessel in the middle of supplying molten glass from a melting furnace performing a melting step to a molding apparatus performing a molding step, for example, a vessel of a clarification tank (clarification tube) or a vessel of a stirring tank, It is also possible to leak the molten glass to the outside of the tube constituting the processing container, hold the molten glass in the hollow space formed between the refractory support and further maintain this state.
Further, the glass supply tube may be a tube using platinum or a platinum alloy for at least a part thereof. In this case, the molten glass is leaked out at a part of the place using the platinum or the platinum alloy, and the refractory support is used. It is possible to hold the molten glass in the hollow space formed between the two and maintain this state.
In the present embodiment, a hollow space is formed in advance between the glass supply pipe and the refractory support, but a castable refractory or molten glass is previously provided between the glass supply pipe and the refractory support. Can also be filled.

  The melting step (ST1) is performed in a melting furnace. In the melting step, a molten glass is made by charging a glass material into the liquid surface of the molten glass stored in the melting furnace and heating the glass material. Further, the molten glass in the melting furnace is heated to a predetermined temperature, and the molten glass flows from the outlet provided at the bottom of the melting furnace toward the subsequent process.

In addition to the method in which electricity flows through the molten glass itself and heats itself by heating, the glass raw material can be melted by supplementing a flame with a burner. A clarifier is added to the glass raw material. SnO ₂ , As ₂ O ₃ , Sb ₂ O _{3 and the} like are known as fining agents, but are not particularly limited. However, it is preferable to use SnO ₂ (tin oxide) as a clarifying agent from the viewpoint of reducing environmental burden.

The preparation process / clarification step (ST2) is performed at least in the glass supply pipe and the clarification tank. The preparation process / clarification process includes a process of performing a preparation process before performing a clarification process, which will be described later, and a process of performing a clarification process. The preparatory process is performed by flowing molten glass through a glass supply pipe connecting the melting furnace and the tube body of the clarification tank. The preparation process will be described later. In the clarification step, a clarification process of the molten glass is performed using a clarification tank. In the clarification treatment, when the molten glass in the clarification tank is heated, bubbles containing O ₂ , CO ₂ or SO ₂ contained in the molten glass absorb O ₂ generated by the reductive reaction of the clarifier. Then, the bubbles rise to the liquid surface of the molten glass, and the gas contained in the bubbles is released into the gas phase space in the clarification tank. Furthermore, in the clarification step, the reducing substance obtained by the reduction reaction of the clarifier undergoes an oxidation reaction by lowering the temperature of the molten glass. Thereby, gas components such as O ₂ in the foam remaining in the molten glass are reabsorbed in the molten glass, and the foam disappears. The oxidation reaction and reduction reaction by the fining agent are performed by controlling the temperature of the molten glass. In addition, the clarification tank includes a vent pipe communicating with the atmosphere in order to release the gas released from the molten glass into the gas phase space to the atmosphere.

In the homogenization step (ST3), the glass components are homogenized by stirring the molten glass in the stirring tank supplied through the pipe extending from the clarification tank using a stirrer. Thereby, the composition unevenness of the glass which is a cause of striae or the like can be reduced.
Thus, molten glass is poured from the melting furnace described later, and is supplied to a molding apparatus for molding a glass substrate through a clarification process and a homogenization process.

In the molding apparatus, a molding step (ST5) and a slow cooling step (ST6) are performed.
In the forming step (ST5), the molten glass is formed into a sheet glass to make a flow of the sheet glass. For forming, an overflow downdraw method is used.
In the slow cooling step (ST6), the sheet glass that has been formed and flowed is cooled to a desired thickness, so that internal distortion does not occur and warpage does not occur.
In a cutting process (ST7), a plate-shaped glass plate is obtained by cutting the sheet glass supplied from the forming device into a predetermined length in the cutting device. The cut glass plate is further cut into a predetermined size to produce a glass substrate of a target size. After this, the end surface of the glass substrate is ground and polished, the glass substrate is cleaned, and after checking for abnormal defects such as bubbles, a glass plate that has passed the inspection is packed as a final product. The

  Drawing 2 is a figure showing typically an example of the manufacture device of the glass substrate which performs the melting process (ST1)-cutting process (ST7) in this embodiment. As shown in FIG. 2, the apparatus mainly includes a melting apparatus 100, a forming apparatus 200, and a cutting apparatus 300. The melting apparatus 100 includes a melting furnace 101, a clarification tank 102, a stirring tank 103, and glass supply pipes 104, 105, and 106.

In the melting furnace 101 shown in FIG. 2, the glass raw material is charged using the bucket 101d, and molten glass MG is generated. In the clarification tank 102, the temperature of the molten glass MG is adjusted, and the clarification of the molten glass MG is performed using the oxidation-reduction reaction of the clarifier. Further, in the stirring vessel 103, the molten glass MG is stirred and homogenized by the stirrer 103a. In the forming apparatus 200, the sheet glass SG is formed from the molten glass MG by the overflow down draw method using the formed body 210.
In the present embodiment, the flow path of the molten glass MG from the melting furnace 101 to the forming apparatus 200 shown in FIG. 2, specifically, the glass supply pipe 104, the pipe body described later of the clarification tank 102, and the glass supply pipe 105. The flow path forming the container of the stirring tank 103 and the flow path of the molten glass MG of the glass supply pipe 106 is made of platinum or a platinum alloy, but at least a part thereof is made of platinum or a platinum alloy. Also good.

(Glass supply tube 104)
The glass supply pipe 104 is a glass supply pipe that connects the melting furnace 101 and the clarification tank 102. In order to perform the defoaming process in the clarification tank 102, the glass supply pipe 104 is provided with an electrode (not shown) for heating the molten glass MG to a high temperature. By passing an electric current from this electrode to the glass supply tube 104, the glass supply tube 104 generates heat, so that the glass supply tube 104 serves as a heating source for the molten glass MG. When the molten glass MG flows into the clarification tank 102, the temperature is raised to, for example, 1630 ° C. or higher using the heating source. For the glass supply pipe 104, for example, platinum or a platinum alloy having high heat resistance and high temperature corrosion resistance is used.
A refractory support that is a refractory brick is provided around the glass supply pipe 104. A hollow space is provided between the refractory support and the glass supply pipe 104. Specifically, the refractory support 110a is an assembly assembled by a plurality of rectangular parallelepiped blocks made of an electroformed refractory material, and supports the glass supply pipe 104 from the outer periphery. The configuration of the refractory support will be described later.

On the other hand, a through hole 104a (see FIG. 3) for communicating with the outside of the glass supply tube 104 and allowing the molten glass MG to leak to the outside is provided at the bottom of the substantially central portion of the glass supply tube 104. The through hole 104a is used to perform a preparation process described later. The through hole 104a is preferably provided at a position where the strength of the glass supply tube 104 is not reduced as much as possible.
The shape of the through hole 104a is not particularly limited. However, in order to prevent the generation of cracks starting from the through hole, or when the glass supply tube 104 is heated by energization, the hot due to the concentration of current density. In order to prevent the generation of spots, a circular shape or an elliptical shape parallel to the energizing direction is desirable. The size of the through hole 104a is not particularly limited, but a diameter of 5 mm or less is sufficient to achieve the purpose of forming the through hole 104a, and it is necessary to provide an unnecessarily large opening. It is not preferable because hot spots are generated due to the concentration of the refractory material, and there is a joint in the above-mentioned refractory support, and when the molten glass leaks from this joint, the amount of leakage is likely to increase. Absent.
As will be described later, the position of the through hole 104a may be provided at the bottom of the glass supply pipe 104 so that the molten glass MG efficiently flows into the hollow space between the refractory support 110a and the glass supply pipe 104. preferable. However, the position of the through hole 104a is not particularly limited. Other through holes may be provided in the glass supply pipe 104 in addition to the through holes 104a. For example, it is preferable that the glass glass MG is provided with the same size at the same height direction position on both sides of the side portion of the glass supply pipe 104 so that the molten glass MG flows uniformly into the hollow space.

(Configuration surrounding the outer periphery of the glass supply pipe 104)
FIG. 3 is a cross-sectional view illustrating the configuration before the preparatory process described later, which surrounds the outer periphery of the glass supply pipe 104 and the glass supply pipe 104. FIG. 4 is a diagram for explaining the state after the preparatory processing of the apparatus surrounding the glass supply tube 104 and the outer periphery of the glass supply tube 104.
As shown in FIG. 3, the glass supply pipe 104 is provided with a through hole 104 a that communicates with the outside of the glass supply pipe 104 in the middle of the pipe. A refractory support 110 a spaced from the outer peripheral surface of the glass supply tube 104 is provided on the outer periphery of the glass supply tube 104. The inner surface of the refractory support 110 a is not in contact with the outer peripheral surface of the glass supply tube 104. The refractory support 110a corresponds to the refractory brick in the present invention. A heat-insulating brick layer 110b and a heat insulating layer 110c are provided on the outer periphery of the refractory support 110a. A hollow space 120 is formed in advance between the glass supply pipe 104 and the refractory support 110a. The hollow space 120 is filled with molten glass leaking from the glass supply tube 104 when the glass substrate is manufactured. The glass supply pipe 104 is fixed to a predetermined position of the hollow space 120 surrounded by the refractory support 110a by a member (not shown).
The refractory support 110 a is made of an electroformed refractory material that supports the glass supply pipe 104. Specifically, the refractory support 110a is an assembly formed by assembling a plurality of rectangular parallelepiped blocks made of an electroformed refractory material. In the form shown in FIG. 3, the refractory support 110a is configured by assembling a plurality of blocks in a cross-beam shape. When assembling multiple blocks in a cross-beam shape, they are assembled so that the joint gap does not become large.

The refractory support 110a is held in the hollow space 120 between the refractory support 110a and the glass supply pipe 104 so that the molten glass MG leaking from the through hole 104a provided at the bottom of the glass supply pipe 104 is held. Is provided. Since the electroformed refractory material has a small porosity and is dense, the molten glass MG does not squeeze out. As the electrocast refractory material, a high zirconia electrocast brick having a zirconia content of 90% by mass or more is suitable when the inner surface temperature of the refractory support 110a is 1580 ° C. or higher. On the other hand, when the inner surface temperature of the refractory support 110a is less than 1580 ° C., an alumina-zirconia electrocast brick having a zirconia content of about 30 to 40% by mass can be used.
In addition, although the structure demonstrated in FIG. 3 is the glass supply pipe | tube 104 which connects the melting furnace 101 and the clarification tank 102, the glass supply pipe | tube 105 which connects the clarification tank 102 and the stirring tank 103, the stirring tank 103, or stirring A similar configuration can be used for the glass supply pipe 106 that connects the tank 103 and the molding apparatus 200. In this case, unlike the glass supply pipe 104 that connects the melting furnace 101 and the clarification tank 102, the glass supply pipe 105 that connects the clarification tank 102 and the stirring tank 103, the stirring tank 103, or the stirring tank 103 and the molding apparatus 200, Since the inner surface temperature of the refractory support becomes lower with respect to the glass supply pipe 106 connecting the two, the material of the refractory support may not be an electroformed brick containing zirconia. For example, when the inner surface temperature of the refractory support is less than 1500 ° C., a mullite brick having an alumina content of 60% by mass or more and an electrofused mullite brick having an alumina content of 70% by mass or more may be used. For example, when the temperature of the inner surface of the refractory support is less than 1400 ° C., a high-alumina brick having an alumina content of about 50% by mass may be used.

In addition, although the refractory support 110a of this embodiment is comprised with the assembly which assembled the several block of the rectangular parallelepiped shape comprised with the electrocast refractory material, the refractory support 110a is such a block. It is based on the following reason that it comprises with the assembly by. That is, from the viewpoint of preventing the molten glass MG from flowing out from the refractory support 110a, there is no joint as a joint between the blocks, and the shape of the refractory support 110a is integrally formed by one member. Is preferably used. However, the size of such integrally formed electroformed refractory material is extremely large, and has a cross-shaped cross section as shown in FIG. Furthermore, the production cost is very high. Moreover, the coefficient of thermal expansion of the high zirconia electroformed refractory material is relatively large. Moreover, the thermal expansion of the high zirconia electrocast refractory material does not increase linearly as the temperature rises when the temperature of the high zirconia electrocast refractory material is raised to a temperature of 1600 ° C. or higher, but 1100 It exhibits a behavior called abnormal thermal expansion, in which it rapidly contracts once in a temperature range of 1200 ° C. and then resumes expansion in a higher temperature range. For this reason, when the refractory support 110a is constituted by one integrally formed member, it is extremely difficult and inappropriate to raise the temperature so as not to cause a crack due to thermal strain. When the temperature is raised appropriately, there may be a case where a crack (crack) due to thermal strain occurs in the integrally formed member of the electroformed refractory material. Since the refractory support 110a of this embodiment employs a structure in which a plurality of blocks made of an electroformed refractory material are assembled, the electroformed refractory material, that is, the refractory support 110a has cracks. It becomes difficult to occur. In particular, by providing the heat insulating brick layer 110b and the heat insulating layer 110c having a heat retaining function on the outer periphery of the refractory support 110a, even if it is an electrocast refractory material having a high thermal conductivity as will be described later, The temperature distribution of the refractory support 110a made of a material approaches uniformly, and cracks due to thermal strain are less likely to occur.
Similar to the glass supply pipe 104, when a refractory support is provided on the outer periphery of the glass supply pipe 105, the stirring tank 103, or the glass supply pipe 106, the glass supply pipe 104 is different from the glass supply pipe 104. 105, the stirring tank 103, or the glass supply pipe 106, since the inner surface temperature of the refractory support becomes low, the material of the refractory support is mullite brick having an alumina content of 60% by mass or more, Electrofused mullite bricks having an alumina content of 70% by mass or more and high alumina bricks having an alumina content of about 50% by mass can be used. When these bricks are used, there is no abnormal expansion, and for example, it is relatively easy and inexpensive to produce a brick with a cross-sectional shape (U-shaped), so instead of stacking a plurality of blocks It is good also as a structure of a saddle type brick and a lid brick.

  By the way, since the heat conductivity of the electrocast refractory material constituting the refractory support 110a is high, when the heat insulating brick layer 110b and the heat insulating layer 110c are not provided, the inside of the refractory support 110a outside the glass supply pipe 104 is provided. The heat of the molten glass MG held in is transferred to the electroformed refractory material and dissipated to the outside, and the heat dissipation amount is large. For example, a high zirconia electrocast refractory material containing 90% by mass or more of zirconia has a thermal conductivity at 1500 ° C. of 4 [W / m / K], and an alumina-zirconia-silica electrocast refractory The thermal conductivity of the material at 1400 ° C. is 6 [W / m / K], which is higher than that of a refractory material having a high porosity. For this reason, in the glass supply pipe 104 which heats the molten glass MG by energization heating for the defoaming treatment of the molten glass MG, it is necessary to increase the energization heating amount in consideration of the heat radiation amount. It is not preferable from the point.

For this reason, in order to suppress the amount of heat radiation from which the heat of the molten glass MG held in the refractory support 110a escapes to the outside, a heat insulating brick layer 110b functioning as a heat retaining member is provided on the outer periphery of the refractory support 110a. A heat insulating layer 110c is provided.
Further, by providing the heat insulating brick layer 110b and the heat insulating layer 110c on the outer periphery of the refractory support 110a, the temperature difference depending on the location of the electroformed refractory material of the refractory support 110a is small when the clarification tank 102 is heated. Thus, cracks and the like due to thermal expansion of the electroformed refractory material can be suppressed. Since the heat insulating brick layer 110b is provided so as to be in contact with the refractory support 110a, it also has a function of reinforcing the refractory support 110a from the outside.

The heat-insulating brick layer 110b may be composed of heat-insulating bricks in one layer, but more preferably, the next layer of the refractory support 110a is a brick having a high heat-resistant temperature, for example, a heat-resistant temperature of 1650 ° C., heat A brick having a conductivity of 0.4 W / m / K is arranged, and on the outside, the heat resistant temperature is lowered, but the brick having a lower thermal conductivity, for example, a heat resistant temperature of 1300 to 1500 ° C., and a heat conductivity of 0.1. The bricks with a thermal conductivity of 2 to 0.3 W / m / K are arranged such that the heat resistance temperature decreases as the distance from the outside increases.
The heat retaining layer 110c is made of a known ceramic fiber board or blanket having a thermal conductivity of about 0.05 to 0.15 W / m / K.

In addition, since the refractory support 110a is an assembly in which a plurality of blocks made of an electroformed refractory material are assembled, joints always exist between the blocks. In order for the molten glass MG not to enter the joints between the blocks of the refractory support 110a, the viscosity of the molten glass MG in the glass supply tube 104 at a temperature of 1500 ° C. is preferably 10 ^2.5 or more. The joint width is preferably narrow so that the molten glass MG does not flow out of the refractory support 110a, and the joint gap is preferably 0.4 mm or less, more preferably 0.3 mm or less. Preferably, it is more preferably 0.2 mm or less. In order to limit such a joint gap to the above numerical range, it is necessary to assemble the blocks with high accuracy in a cross-beam shape.
Moreover, the heat insulation brick layer 110b and the heat insulation layer 110c of this embodiment do not cover the joint part between the blocks of the refractory support 110a, but cover the part other than the joint part between the blocks. The joint portion is exposed to the outside of the heat insulating brick layer 110b and the heat insulating layer 110c. Therefore, the amount of heat radiation at the joint portion between the blocks of the refractory support 110a is high. By adopting such a configuration, even if the molten glass MG held in the refractory support 110a enters the joint between the blocks, the molten glass that has entered is high in the refractory support 110a around the joint. It solidifies by heat dissipation due to thermal conductivity and plays a role in closing joints. That is, it is possible to prevent the molten glass MG from flowing out to the outer periphery of the refractory support 110a by solidifying the molten glass that has entered the joint using heat dissipation. Here, the joint portion not covered by the heat insulating brick layer 110b and the heat insulating layer 110c is preferably a region including a joint having a width of 5 cm or less, more preferably a region including a joint having a width of 4 cm or less. More preferably, the region includes a joint having a width of 3 cm or less.
As described above, when the viscosity at a temperature of 1500 ° C. in the glass supply pipe 104 is 10 ^2.5 poise or more, the molten glass MG hardly enters the joint, but even if it enters, the molten glass MG is solidified. Therefore, it is possible to prevent the molten glass MG from flowing out to the outer periphery of the refractory support 110a through the joint.
Unlike the glass supply pipe 104 that connects the melting furnace 101 and the clarification tank 102 described so far, for example, the inside of the glass supply pipe 105 that connects the clarification tank 102 and the stirring tank 103 is actively added. If you want to lower the temperature of the molten glass flowing, of course, do not install the heat-insulating brick layer and / or heat insulation layer, or the amount of heat insulation by the installation, the temperature of the molten glass will be a predetermined temperature Adjust as follows.

  As indicated by arrows in FIG. 3, the heat insulating layer 110c in FIG. 3 is pressed in the direction of the arrow by a pressing metal not shown, and the refractory support 110a tends to spread outward due to the pressure of the molten glass MG. Opposes force. Thereby, the shape of the refractory support 110a is maintained.

(Glass supply pipe preparation process)
When a glass substrate is manufactured using the components surrounding the glass supply tube 104, the following glass supply tube 104 is subjected to a preparation process. In the preparation process, a part of the molten glass MG is leaked to the outside of the glass supply pipe 104 from the through hole 104a provided in the glass supply pipe 104, and a hollow space between the glass supply pipe 104 and the refractory support 110a is formed. In this process, the molten glass MG leaked into the space 120 is retained. That is, when the glass substrate is manufactured, first, in the melting furnace 101, the glass raw material is melted in the melting step (step ST1) to generate a molten glass MG. At this time, as shown in FIG. 3, a hollow space 120 is formed in advance between the glass supply pipe 104 and the refractory support 110a. Thereafter, the generated molten glass MG is caused to flow through the glass supply pipe 104, and the glass supply pipe 104 is subjected to a preparation process using the molten glass MG. At this time, the glass supply tube 104 is in a state of being heated to approximately 1000 ° C. or higher.
As the amount of molten glass MG flowing through the glass supply pipe 104 increases, the liquid level in the glass supply pipe 104 rises. In accordance with this, the molten glass MG leaks from the through-hole 104a provided on the outer periphery of the glass supply pipe 104 and accumulates in the hollow space between the refractory support 110a and the glass supply pipe 104. At this time, the liquid level of the molten glass MG in this portion rises so as to coincide with the liquid level in the glass supply pipe 104. Finally, the molten glass MG flows while being fully filled in the glass supply pipe 104. Similarly, the leaked molten glass MG is filled in the hollow space 120 between the glass supply pipe 104 and the refractory support 110a. At this time, since the heat-insulating brick layer 110b and the heat insulating layer 110c are provided on the outer periphery of the refractory support 110a, even if the heat conductivity of the refractory support 110a is high, the outer surface of the refractory support 110a The amount of heat released is suppressed, and the temperature of the molten glass MG in the glass supply tube 104 can be adjusted to the target temperature without wasting energy. Thus, the leaked molten glass MG is held in the hollow space 120 between the glass supply pipe 104 and the refractory support 110a.

  The glass substrate manufacturing method including the clarification step and the homogenization step shown in FIG. 1 is started using the glass supply pipe 104 subjected to such a preparatory process. That is, after performing the preparatory process using the molten glass MG, a part of the molten glass MG leaked to the outside of the glass supply pipe 104 from the through hole 104a using the glass supply pipe 104 subjected to the preparatory process. The molten glass MG is supplied to the forming apparatus 200 while holding in the hollow space 120. The molten glass MG leaked into the hollow space 120 between the glass supply pipe 104 and the refractory support 110a is maintained in a liquid state without being solidified during the supply process.

In the conventional glass substrate manufacturing method and manufacturing apparatus, as described above, oxygen is left behind in the glass supply tube 104, and oxygen bubbles are easily formed in the molten glass, which is the final product. There was a problem of reducing the yield of the glass substrate.
In the conventional glass substrate manufacturing method and manufacturing apparatus, as in this embodiment, platinum or a platinum alloy is used for a tube constituting a processing vessel of a clarification tank or a stirring tank, and further for a glass supply pipe. For this reason, when the temperature of the molten glass is higher than, for example, 1600 ° C., platinum or the platinum alloy is oxidized or volatilized in the presence of oxygen, so that the thickness of the component made of platinum or the platinum alloy is reduced. Thus, there has been a problem that the tube and the glass supply tube constituting the processing container are damaged.
Furthermore, in the conventional method and apparatus for producing a glass substrate, in order to ensure the strength at high temperature of a clarification tank, a stirring tank, or a glass supply pipe made of platinum or a platinum alloy, it has a high heat resistance. A support portion made of a material such as ceramics is disposed on the outer periphery of the tube, and the tube is firmly supported and fixed. The support such as the heat-resistant ceramic is brought into a high temperature state due to the temperature rise for starting the operation of manufacturing the glass substrate. Or depending on the case, a support part receives the change of temperature from a high temperature state by the change of the temperature conditions of the molten glass at the time of operation of manufacture of a glass substrate. At this time, since the thermal expansion coefficient of platinum or platinum alloy which is a constituent member of the clarification tank, the stirring tank or the glass supply pipe is different from the thermal expansion coefficient of the support, platinum or platinum alloy Due to the difference in the coefficient of thermal expansion, there is a problem that it receives thermal stress and, in some cases, is thermally deformed and breaks.

  However, as described above, in the glass substrate manufacturing method and manufacturing apparatus of the present embodiment, a part of the molten glass MG leaked to the outside of the glass supply tube 104 from the through hole 104a provided in the glass supply tube 104, The molten glass MG is supplied to the molding apparatus 200 while being held in the hollow space 120 between the glass supply pipe 104 and the refractory support 110a. For this reason, since the outer periphery of the glass supply pipe 104 is surrounded by a molten glass having a slow hydrogen permeation rate, oxygen bubbles in the molten glass MG, which has been a problem in the past, are hardly formed. Furthermore, since platinum or a platinum alloy has few opportunities to come into contact with oxygen, it is possible to prevent platinum volatilization, which has been a problem in the past. Moreover, since the inside and the outer periphery of the glass supply tube 104 are maintained at substantially the same pressure due to the presence of the tube through-hole, even if the glass supply tube 104 is not mechanically supported by a high-strength support member, The glass supply tube 104 is not deformed and is not damaged. Further, since the refractory support reinforces the tube main body, there is no damage due to thermal distortion of the tube main body that occurs when the support supports and fixes the tube main body from the outer periphery as in the prior art. That is, the problem that has been a problem in the past can be solved.

  In the present embodiment, the glass supply pipe 104 has been mainly described. However, the arrangement of the refractory support 110a, the heat insulating brick layer 110b, and the heat insulating layer 110c is changed to the pipe body of the clarification tank 102 or the processing container of the stirring tank 103. The present invention can also be applied to the constituent tubes and the glass supply tubes 105 and 106. Even in this case, the above-described problems that have conventionally occurred in the clarification tank, the stirring tank, or the glass supply pipe can be solved by increasing the temperature of the molten glass MG.

In the refractory support 110a, an electrocast refractory material containing zirconia, preferably a high zirconia electrocast refractory material, is used, so that the surface of the refractory support 110a is molten glass leaked from the glass supply pipe 104. Difficult to be eroded by MG.
Since the heat insulating brick layer 110b and the heat insulating layer 110c functioning as heat insulating members are provided on the outer periphery of the refractory support 110a, the amount of heat released from the electroformed refractory material having high thermal conductivity can be suppressed, and fire resistance Even if the thermal conductivity of the object support 110a is high, the amount of heat released from the outer surface of the refractory support 110a is suppressed, and the temperature of the molten glass MG in the glass supply pipe 110a is not wasted energy. The target temperature can be adjusted.
Further, the refractory support 110a is an assembly assembled by a plurality of blocks made of an electroformed refractory material, and portions other than joints between the blocks are heat insulating members such as a heat insulating brick layer 110b and a heat insulating layer 110c. The portion of the joint between the blocks that are covered is not covered with the heat insulating member and is exposed to the outside of the heat insulating member. For this reason, even if the molten glass MG enters the joint, the molten glass MG that has entered the joint due to heat dissipation of the electroformed refractory material is easily solidified. For this reason, it is possible to prevent the molten glass MG from entering the joint and flowing out to the outer periphery of the refractory support 110a.
Moreover, since the viscosity of the molten glass MG is 10 ^2.5 poise temperature or more at a temperature of 1500 ° C., it is difficult to enter the joint between the blocks.

(Glass substrate)
The following are mentioned as an example of the glass substrate manufactured with the manufacturing method of this embodiment.
Non-alkali glass suitable as a glass substrate for flat panel display is
SiO ₂ : 50% by mass to 70% by mass,
Al ₂ O ₃ : 0% by mass to 25% by mass,
B ₂ O ₃ : 1% by mass to 15% by mass,
MgO: 0% by mass to 10% by mass,
CaO: 0% by mass to 20% by mass,
SrO: 0% by mass to 20% by mass,
BaO: 0% by mass to 10% by mass,
Containing.
Here, the total content of MgO, CaO, SrO and BaO is 5% by mass to 30% by mass.
Moreover, you may use the alkali trace amount glass which contains a trace amount of alkali metals as a glass substrate for flat panel displays. Alkaline trace containing glass, as component, 'comprises ₂ O, preferably, 0.2 wt% to 0.5 wt% R' of R 0.1 wt% to 0.5 wt% including the ₂ O. Here, R ′ is at least one selected from Li, Na and K. The total content of R ′ ₂ O may be less than 0.1% by mass.
In addition, it is preferable that said glass substrate does not contain arsenic substantially, and it is more preferable that arsenic and antimony are not included substantially. That is, even if these substances are included, they are as impurities. Specifically, these substances include 0.1% by mass including oxides of As ₂ O ₃ and Sb ₂ O _3. The following is preferable.

Further, in addition to the components described above, the glass used in the glass substrate of this embodiment contains various other oxides to adjust various physical, melting, fining, and forming properties of the glass. There is no problem. Examples of such other oxides include, but are not limited to, TiO ₂ , MnO, ZnO, Nb ₂ O ₅ , MoO ₃ , Ta ₂ O ₅ , WO ₃ , Y ₂ O ₃ , and La ₂ O ₃ is mentioned. Here, since the glass plate for flat panel displays has particularly severe requirements for bubbles, it is preferable to contain at least SnO ₂ having a high clarification effect among the above oxides.

  Nitrate and carbonate can be used as the RO supply source. In order to increase the oxidizability of the molten glass, it is more desirable to use nitrate as a RO supply source at a ratio suitable for the process.

(Modification)
FIG. 5 is a diagram showing a modification of the present embodiment. In this modification, the refractory support 110a is provided apart from the outer peripheral surface of the glass supply pipe 104a. However, a castable refractory 130 is provided between the refractory support 110a and the glass supply pipe 104a. Filled. The castable refractory 130 is melted into the molten glass MG easily leaking from the through hole 104a at a high temperature, and becomes a liquid state. For this reason, this liquid can suppress the formation of oxygen bubbles in the molten glass, prevent the volatilization of platinum in the glass supply tube 104a, and prevent the deformation of the glass supply tube 104a. As the castable refractory 130, for example, when alumina cement is used, the molten glass liquid formed by melting the molten glass and the alumina cement has a higher alumina concentration and viscosity than the glass composition of the original molten glass. It becomes high glass. For this reason, it is difficult to exude from the joint of the refractory support 110a.
Further, between the refractory support 110a and the glass supply pipe 104a, instead of the castable refractory 130, a molten glass (molten glass B) having a glass composition different from the molten glass used for manufacturing the glass substrate is used. May be filled and held. This molten glass B is easily in a liquid state at a high temperature and mixed with a molten glass (referred to as molten glass A) used for manufacturing a glass substrate to become a molten glass C having a new glass composition. Further, prevention of volatilization of platinum and prevention of deformation of the glass supply pipe 104 can be achieved. The composition of the new molten glass C is not particularly limited. For example, by selecting the viscosity at 1500 ° C. to be 10 ^3.0 poise or more, the molten glass C oozes from the joint of the refractory support 110a. It can be effectively suppressed.
In addition, in this embodiment and the modification mentioned above, in order to clarify the molten glass MG which passed the glass supply pipe | tube 104 in the clarification tank 102, although the preparatory process of the glass supply pipe | tube 104 is performed before a clarification process, The order of the preparation processes is changed according to the pipes to be implemented, such as the glass supply pipe 105 and the processing vessel of the stirring tank 103.

  As mentioned above, although the manufacturing method of the glass substrate and the manufacturing apparatus of the glass substrate of this invention were demonstrated in detail, this invention is not limited to the said embodiment, In the range which does not deviate from the main point of this invention, various improvement and a change are carried out. Of course.

DESCRIPTION OF SYMBOLS 100 Melting apparatus 101 Melting furnace 101a Outlet 102 Clarification tank 103 Stirrer tank 103a Stirrer 104, 105, 106 Glass supply pipe 104a Through hole 110a Refractory support 110b Thermal insulation brick layer 110c Heat insulation layer 120 Hollow space 130 Castable refractory 200 Molding apparatus 210 Molded body 300 Cutting device

Claims (11)

A melting furnace for heating glass raw material to produce molten glass;
A molding apparatus for molding a glass plate from the molten glass;
A tube made of platinum or a platinum alloy, which is provided between the melting furnace and the molding apparatus and used for transferring or processing the molten glass;
A glass substrate manufacturing apparatus comprising:
The tube is provided with a through hole for leaking the molten glass,
An apparatus for producing a glass substrate, characterized in that a fire brick that is spaced apart from the outer peripheral surface of the tube is provided on the outer periphery of the tube.   The glass substrate manufacturing apparatus according to claim 1, wherein the molten glass that has flowed through the tube and leaked from the through hole is held in at least a portion between the tube and the refractory brick.   The said refractory brick is a manufacturing apparatus of the glass substrate of Claim 1 or 2 which is an electrocast brick containing a zirconia.   The said firebrick is a manufacturing apparatus of the glass substrate of any one of Claims 1-3 which is a high alumina brick, a mullite brick, or an electromelting mullite brick.   The glass substrate manufacturing apparatus according to any one of claims 1 to 4, wherein a heat retaining member is further provided outside the refractory brick. The refractory brick is an electroformed brick containing zirconia,
The electrocast brick is a structure assembled by a plurality of blocks,
The glass substrate manufacturing apparatus according to claim 5, wherein a portion other than the joint between the blocks is covered with the heat insulating material, and a joint portion between the black is not covered with the heat insulating member. The said molten glass is a manufacturing apparatus of the glass substrate of any one of Claims 1-6 whose viscosity in the temperature of 1500 degreeC is 10 ^2.5 poise or more.   The glass substrate manufacturing apparatus according to any one of claims 1 to 7, wherein a hollow space is formed in advance between the tube and the refractory brick.   The apparatus for producing a glass substrate according to any one of claims 1 to 7, wherein a castable refractory is filled in advance between the pipe and the refractory brick.   The molten glass having a composition different from that of the molten glass is filled in at least a part between the tube and the refractory brick in advance. The manufacturing apparatus of the glass substrate of description. The manufacturing method of a glass substrate which manufactures a glass substrate using the manufacturing apparatus of the glass substrate of any one of Claims 1-10.

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