TWI704115B - Method for manufacturing glass substrate and glass substrate manufacturing apparatus - Google Patents

Abstract

The present invention stops the operation of the manufacturing equipment of the glass substrate at an appropriate time in a manner that does not reduce the productivity of the glass substrate. The manufacturing method of the glass substrate includes: a manufacturing step, which uses a processing device to process the molten glass, and the processed molten glass is shaped into a glass plate; an analysis step, which analyzes the gas component in the bubbles contained in the glass plate The determination step, which uses the analysis result of the gas composition to determine whether to stop the manufacturing step; and the execution step, which executes the stop of the manufacturing step based on the determination result in the determination step. In the manufacturing method of the glass substrate, the concentration of two or more components of CO ₂ , N ₂ , SO ₂ , and Ar in the above-mentioned gas components is changed to be the condition for stopping the above-mentioned manufacturing step.

Description

Manufacturing method of glass substrate and glass substrate manufacturing device

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

The glass substrate for a display is generally produced through a manufacturing process of forming molten glass from glass raw materials, removing (clarifying) the minute bubbles contained in the molten glass, and forming the molten glass into a glass substrate. The manufacturing step is performed using a manufacturing furnace (manufacturing facility) formed by connecting processing devices such as a glass supply pipe and a clarification tank. Since the processing device is connected to the high-temperature molten glass before forming, it must be constructed of appropriate materials according to the temperature of the molten glass and the required quality of the glass substrate. Platinum group metals such as platinum and platinum alloys are generally used as materials constituting the processing device (Patent Document 1). The platinum group metal has a high melting point and has excellent corrosion resistance to molten glass.

On the other hand, platinum group metals are easily oxidized and volatilized in high temperature environments. Therefore, if platinum group metal is used as the material of the processing device, part of the platinum group metal may be thinned and deformed or damaged. If the processing device is deformed or damaged, the molten glass may leak from the processing device, causing damage to the surrounding processing device. Therefore, it is expected that the operation of the manufacturing furnace should be stopped before the processing device is deformed or damaged. [Prior Technical Literature] [Patent Literature]

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

[The problem to be solved by the invention]

However, if the manufacturing furnace of the glass substrate is stopped, the glass substrate cannot be manufactured, and therefore the productivity of the glass substrate decreases. On the other hand, the processing equipment for molten glass is usually covered with refractories such as refractory bricks, and it is difficult to confirm the state of the processing equipment from the outside. Therefore, it is difficult to stop the manufacturing furnace at an appropriate point before the processing device is deformed or damaged.

Therefore, the object of the present invention is to provide a glass substrate manufacturing method and a glass substrate manufacturing device that can stop the glass substrate manufacturing equipment at an appropriate time without reducing the productivity of the glass substrate. [Technical means to solve the problem]

One aspect of the present invention is a method for manufacturing a glass substrate, which is characterized by comprising: a manufacturing step of using a processing device to process molten glass, and forming the processed molten glass into a glass plate; an analysis step, Analyze the concentration of the gas components in the bubbles contained in the glass plate; a judging step, which uses the analysis results of the gas components to determine whether to stop the manufacturing step; and an execution step, which executes based on the judgment result in the judgment step The stopping of the above-mentioned manufacturing step; the conditions for stopping the above-mentioned manufacturing step by changing the concentration of two or more components of CO ₂ , N ₂ , SO ₂ , and Ar in the above-mentioned gas component.

It is preferable that the concentration of the above-mentioned two or more components exceeds the allowable concentration range of each as a condition for stopping the above-mentioned manufacturing step.

It is preferable to set the specific period as an interval, and each time the specific period elapses, the above-mentioned concentration changes in the moving average obtained by calculating the average value of the concentration of the above-mentioned gas components in the entire plurality of consecutive intervals while shifting the above-mentioned interval one by one. The conditions used to stop the above manufacturing steps.

Preferably, in the determination step, the time to stop the manufacturing step is determined based on the amount of change in the concentration of the gas component, and In the aforementioned execution step, the aforementioned manufacturing step is stopped based on the aforementioned period determined in the aforementioned judgment step.

Preferably, in the above analysis step, at least any one of the internal pressure of the gas component and the depth position of the bubble from the surface of the glass plate is further analyzed, and In the judgment step, the analysis result related to the one of the internal pressure and the depth position is further used to make the judgment.

Preferably, in the above analysis step, the above-mentioned bubbles with a size exceeding 1 mm are set as the analysis object.

Another aspect of the present invention is a glass substrate manufacturing apparatus, which is characterized by comprising: manufacturing equipment that uses a processing device to process molten glass and shape the processed molten glass into a glass plate; an analysis device for The concentration of the gas components in the bubbles contained in the glass plate is analyzed; a judging device that uses the analysis results of the gas components to determine whether to stop the operation of the manufacturing equipment; and an execution device based on the results obtained by the judging device As a result of the judgment, the operation of the above-mentioned manufacturing equipment is stopped; the concentration of two or more components of CO ₂ , N ₂ , SO ₂ , and Ar in the above-mentioned gas composition is changed to be used as the conditions for stopping the operation of the above-mentioned manufacturing equipment. [Effects of Invention]

According to the present invention, it is possible to stop the operation of the glass substrate manufacturing equipment at an appropriate time without reducing the productivity of the glass substrate.

(Outline of manufacturing method of glass substrate) FIG. 1 is a diagram showing an example of manufacturing steps performed by the method of manufacturing a glass substrate of this embodiment. The manufacturing method of the glass substrate of this embodiment is equipped with the manufacturing process which processes the molten glass using the processing apparatus of a molten glass, and shapes the processed molten glass into a glass plate. More specifically, the manufacturing method of the glass substrate of this embodiment mainly has a melting step (S1), a forming step (S2), a slow cooling step (S3), and a cutting step (S4). Among them, at least the melting step (S1) and the forming step (S2) are performed in the manufacturing step. In the melting step (S1), a production step, a clarification step, a stirring step, and a supply step are performed. The glass substrate manufacturing method also has a grinding step, a polishing step, a cleaning step, an inspection step, a packing step, etc. In the packing step, a plurality of laminated glass substrates are shipped to the supplier of the ordering party.

The generation step is carried out in the melting tank. In the production step, the glass raw material is put into a melting tank in which molten glass is stored and heated, thereby producing molten glass. The clarification step is carried out at least in the clarification tank. In the clarification step, the temperature of the molten glass is adjusted, and the molten glass is clarified by the oxidation-reduction reaction of the clarifier. As the clarifying agent, tin oxide is used, for example.

In the stirring step, a stirrer is used to stir the molten glass in the stirring tank, thereby homogenizing the glass components. In the supply step, the molten glass is supplied to the forming device through the pipe extending from the stirring tank.

In the forming step (S2), the molten glass is formed into flake glass to produce a flake glass stream. The forming can use the overflow down-draw method or the float method. In the slow cooling step (S3), cooling is performed in such a way that the flowed flake glass after forming becomes the required thickness without internal deformation and no warpage.

In the cutting step (S4), in the cutting device, the sheet glass supplied from the forming device is cut into a specific length, thereby obtaining a plate-shaped glass plate. The cut glass plate is then cut into a specific size to produce a glass substrate of the target size.

In the inspection step, internal defects or deformations such as bubbles, foreign objects, etc. contained in the glass plate that become the glass substrate are inspected, and as a result, non-conforming products that do not meet the criteria are excluded from self-made products.

Furthermore, the manufacturing method of the glass substrate of this embodiment has the following analysis process, a judgment process, and execution process as another process performed during the period (in operation) from the melting process (S1) to the cutting process (S4).

(Outline of glass substrate manufacturing equipment) Fig. 2 is a diagram schematically showing an example of a glass substrate manufacturing apparatus that performs the melting step (S1) to the cutting step (S4) in this embodiment. This device mainly includes a melting device 100, a forming device 200, and a cutting device 300 as shown in FIG. The melting apparatus 100 has a melting tank 101, a clarification tank 102, a stirring tank 103, and glass supply pipes 104, 105, and 106. The molding device 200 has a molded body 210. The glass substrate manufacturing apparatus further has an analysis device, a judgment device, and an execution device as devices for performing the analysis step, the judgment step, and the execution step.

In the melting device 100 of the example shown in FIG. 2, the glass raw material is dispersed and poured into the surface of the molten glass MG stored in the melting tank 101 by the bucket 101d. The melting tank 101 is provided with a heating device for heating molten glass. Thereby, the molten glass obtained by melting the glass material in the melting tank 101 is produced. At this time, a specific flow (convection) of molten glass is formed in the melting tank 101. The molten glass of the melting tank 101 flows out of the outflow port 104a provided on the inner wall of the melting tank 101 opposite to the input port of the glass material through the glass supply pipe 104 toward the next step. Thereby, a fixed amount of molten glass is stored in the melting tank 101. The heating of molten glass can be carried out, for example, by using combustion heating in the gas phase of combustion gas formed by a burner, and energization heating by passing an electric current through the molten glass, and the ratio can be adjusted by adjusting the ratio. The amount of water contained.

In the clarification tank 102, the molten glass is heated, and oxygen is released by the reduction reaction of the clarifier. After that, in the clarification tank 102 or the glass supply pipe 105 extending from the clarification tank 102, the temperature of the molten glass is lowered, and the gas components remaining in the bubbles in the molten glass are absorbed again by the oxidation reaction of the clarifier. It disappears in the molten glass. The oxidation reaction and the reduction reaction of the clarifier are carried out by controlling the temperature of the molten glass.

In the stirring tank 103, the molten glass supplied through the glass supply pipe 105 is stirred and homogenized by the stirrer 103a. Furthermore, one stirring tank may be installed as shown in the figure, or two may be installed. The molten glass obtained by homogenization in the stirring tank 103 is supplied to the forming device 200 through the glass supply pipe 106.

Furthermore, the clarification tank 102, the stirring tank 103, and the glass supply pipes 104, 105, and 106 of the devices constituting the melting device 100 are processing devices for processing molten glass. The clarification tank 102, the stirring tank 103, and the glass supply pipe 104, 105, 106 are mutually connected, and are connected to the melting tank 101 and the forming apparatus 200, and comprise a manufacturing furnace (manufacturing equipment). For the clarification tank 102, the stirring tank 103, and the glass supply pipes 104, 105, and 106, for example, a container or pipe using a platinum group metal as a constituent material is used.

In the forming apparatus 200, the sheet glass SG is formed from the molten glass MG by the overflow down-draw method using the forming body 210. The molten glass supplied to the forming body 210 overflows from the upper part of the forming body 210, flows down along the sides of the forming body 210, and merges at the lower end of the forming body 210, thereby forming a molten flow of the sheet glass SG. The constituent material of the molded body 210 is, for example, refractories such as heat-resistant bricks. The molded body 210 is a processing device for processing molten glass.

(Analysis step, judgment step, execution step) The other steps performed in the manufacturing method of the glass substrate of this embodiment are shown in FIG. The manufacturing method of a glass substrate includes an analysis step (S11), a judgment step (S12), and an execution step (S13).

In the analysis step (S11), the concentration of gas components in the bubbles contained in the glass plate is analyzed. In the analysis step (S11), the glass plate in which the size of the bubbles in the glass plate judged as a defective product in the inspection step does not meet the standard is set as the analysis object. The defective products are usually generated constantly within a certain ratio range, so the analysis step can be performed at a fixed time interval (for example, once a day). Furthermore, the ratio of glass plates that are not defective products to the glass plates produced (yield rate) changes frequently during the operation, but usually moves at a ratio higher than the target ratio to ensure the productivity of the glass substrate.

The concentration of the gas component can be measured using, for example, laser Raman spectroscopy or mass analysis. In the laser Raman spectroscopy method, the bubbles contained in the glass plate are irradiated with laser light, and the Raman scattered light generated by the gas in the bubbles is detected, thereby detecting the gas composition, and calculating the concentration based on the intensity of the wave peak. In the mass analysis method, the glass plate is broken in a vacuum chamber to release the gas components in the bubbles, and the mass analyzer is used to measure the concentration of the released gas components. The mass analysis method is suitable for detecting rare gases such as Ar. In this specification, concentration refers to volume %.

In the judgment step (S12), the analysis result of the gas composition is used to judge whether to stop the manufacturing step. Specifically, in the judging step (S12), it is studied whether the concentration change of the gas component when comparing a certain analysis result with the analysis result of the comparison target satisfies the conditions for stopping the manufacturing step (work stop conditions). As a result, if the above-mentioned change satisfies the work stop condition, it is judged to stop the manufacturing step, and if the above-mentioned change does not satisfy the work stop condition, it is judged to continue the manufacturing step. The analysis result mentioned here can be the analysis result of one bubble or the analysis result of multiple bubbles. On the other hand, the concentration of gas components usually differs between bubbles of glass substrates produced in the same period. Therefore, from the viewpoint of accurate judgment, it is better to compare the analysis results of multiple bubbles with each other , That is, compare the analysis results of the two parent groups. The plural bubbles are randomly extracted from, for example, the bubbles contained in the area of the glass plate as the analysis target. The plurality of bubbles may be a plurality of bubbles contained in the same glass plate, or may be a plurality of bubbles contained in different glass plates. In the following description, a case where the analysis result of a plurality of bubbles is used for the judgment step (S12) will be described as an example. As the above-mentioned "a certain analysis result", for example, the average value of the concentration of gas components in the most recent specific period (for example, 1 to several weeks, 1 to several months) during the period when the yield rate is lower than the target ratio, or the low yield rate The average value of the concentration of the glass component in the entire period of the target ratio. As the above-mentioned "analysis result to be compared", for example, the average value of the concentration of gas components in the nearest specific period (for example, 1~several weeks, 1~several months) during the period when the yield rate is higher than the target rate, or The good product rate is the average value of the concentration of the gas component in the entire period above the target ratio, or the average value of the concentration of the glass component in the initial specific period (such as 1 to several weeks, 1 to several months) at the beginning of the operation. In addition, as a preferable judgment method in the judgment step (S12), the change in the moving average of the concentration of the gas component can be used as the change in the concentration of the gas component when comparing the above two analysis results. For example, moving average is by setting a specific period (for example, 1~several weeks, 1~several months) as one interval, and each time a specific period passes, it shifts the interval one by one, and calculates the average value of a plurality of consecutive intervals as a whole. Find out.

The execution step (S13) stops the manufacturing step based on the judgment result in the judgment step (S12). Specifically, when it is determined to stop the manufacturing step in the determination step (S12), the manufacturing step is stopped. The stop of the manufacturing step can be performed at the point when it is determined that the manufacturing step is stopped, or it can be performed at the point when a specific period (for example, 1 to several weeks, 1 to several months) has passed after the determination is to stop the manufacturing step. On the other hand, when it is determined in the determination step (S12) to continue the manufacturing step, the execution step (S13) is not performed. The execution step can be performed by using the control device that controls the operation of the manufacturing equipment as the execution device to stop the operation of the manufacturing equipment. The control device is a computer with a CPU (Central Processing Unit) and memory, etc., and is connected to each processing device of the manufacturing equipment. The control device constitutes a part of the glass substrate manufacturing device.

In this embodiment, the concentration of two or more of CO ₂ , N ₂ , SO ₂ , and Ar in the gas component is changed for the operation stop condition. Since the processing device of molten glass is used under high temperature conditions, it is prone to deterioration with use. Especially when platinum group metals are used in the treatment device, since the platinum group metals are easily volatilized and become thinner, they may be damaged due to holes, deformation, etc. If the processing device is deformed or damaged, molten glass will leak from the processing device, causing damage to the surrounding processing device. Processing devices are usually connected to each other to form one manufacturing furnace. Therefore, even if one processing device is repaired or replaced, the operation of the entire manufacturing furnace has to be stopped. However, if the manufacturing furnace is stopped, the glass substrate cannot be manufactured. Therefore, there is a problem that the productivity of the glass substrate is reduced due to the unnecessary stop. On the other hand, the processing device is covered with refractories such as refractory bricks, and it is difficult to confirm the degree of deterioration from the outside. Therefore, it is difficult to stop the manufacturing furnace at an appropriate point before the processing device is deformed or damaged. In view of this problem, the inventors conducted research, and as a result, obtained the knowledge that there is a correlation between the deterioration degree of the processing device and the bubbles contained in the glass substrate produced using the processing device. In addition, the inventors conducted further studies and found that the concentration of two or more of CO ₂ , N ₂ , SO ₂ , and Ar changes in the gas components in the bubble and the degree of deterioration of the processing device is relatively strong. The relevance. Therefore, in this embodiment, the gas component concentration analysis in the bubble is performed during the operation. As a result, the operation is stopped based on the changes in the concentration of two or more components among CO ₂ , N ₂ , SO ₂ , and Ar. judgment. If the operation is stopped based on the result of this judgment, the processing device may be degraded, and the possibility of stopping the manufacturing furnace at an appropriate time when repair or replacement is necessary increases. Therefore, according to the present embodiment, the glass substrate manufacturing furnace can be stopped at an appropriate time without reducing the productivity of the glass substrate.

Furthermore, if the processing device continues to deteriorate, damage to the processing device such as a clarification tank will occur, which will cause problems such as abnormalities in the bubbles in the flake glass due to leakage of molten glass, breakage of the molded body, or defects.

According to the research of the present inventors, it is found that only one component of CO ₂ , N ₂ , SO ₂ , and Ar concentration changes and the degree of deterioration of the processing device does not necessarily have a correlation. Therefore, even if the concentration of only one component of CO ₂ , N ₂ , SO ₂ , and Ar is used to stop the operation, the possibility of stopping the manufacturing furnace at the appropriate time is low. . In other words, although the processing device can still be used sufficiently, the possibility of stopping the manufacturing furnace is high, which may reduce the productivity of the glass substrate.

Furthermore, the so-called "concentrations of two or more components change" in CO ₂ , N ₂ , SO ₂ , and Ar means that the concentrations of two or more components change simultaneously. As the state where the concentration of two or more components change at the same time, in addition to the case where the concentration of one component changes and the concentration of another component changes, the bubble is the same bubble, and it also includes different bubbles with the same period. (E.g. 1 week, 1 month) the analysis of the bubbles with each other. The so-called same period means the above-mentioned "recent specific period".

In addition, as an example of a situation where the "concentration changes" of the gas component, the gas component concentration relative to the change in the bubble analysis result (the above-mentioned "analysis result") after the change in the comparison of the two analysis results The concentration of the same gas component in the previous bubble analysis result (the above-mentioned "analysis result to be compared") exceeds a specific rate of change and changes. Specifically, it refers to an increase in excess of a specific increase rate (for example, hundreds of%) or a decrease in excess of a specific decrease rate (for example, several tens of%) (see FIG. 4(a)). Fig. 4(a) is a diagram showing an example of changes in the concentration of gas components. In FIG. 4, t1 represents the period during which the glass plate for which the bubble analysis result before the change is made is made, and t2 represents the period during which the glass plate for which the bubble analysis result after the change is made the target is made. Furthermore, in the situation called "concentrations of more than two components change", in addition to the increase or decrease in the concentration of two or more components, the concentration of one component increases and the concentration of another component decreases. . As another example of the “concentration change” of the gas component, the concentration of the gas component that changes within the allowable concentration range in the “bubble analysis result before change” among the two compared analysis results exceeds “ The allowed concentration range in "Changed Bubble Analysis Results".

In addition, as another example of the "concentration change" of the gas component, it can be cited among the multiple bubbles of the analysis object set as the "bubble analysis result before change", the concentration of a certain gas component is randomly distributed in In a wide concentration range, in contrast to this, in the "Changed Bubble Analysis Results", it is concentrated in a narrow concentration range (for example, more than 60% of the bubbles in the analysis result are present in the concentration range) (refer to Figure 4(b)). Fig. 4(b) is a diagram showing another example of a change in the concentration of a gas component. In Figure 4(b), A represents a wide concentration range, and B represents a narrow concentration range. On the contrary, in contrast to the concentrated distribution in a narrow concentration range, it is also possible to cite another example where the gas component is randomly distributed in a wide concentration range as a "concentration change".

In addition, as another example of the "concentration change" of the gas component, it can also be cited in the "bubble analysis result before change" within the concentration range where any two or more of the above four bubble components do not exist. The gas component is present in the "Changed bubble analysis result", or vice versa, the gas component does not exist within the concentration range of the gas component of two or more of the above four bubble components. As another example of the "internal pressure change" of the gas composition, the change in the number of bubbles in a certain concentration range can also be cited.

According to the inventor’s research, it was discovered that the type of gas whose concentration changes when the treatment device deteriorates or the way of change (increase or decrease, whether it is within the allowable concentration range, concentrated or dispersed in a narrow concentration range, whether it exists in No longer exists in a certain concentration range) There are different situations depending on the manufacturing furnace. Therefore, the judgment conditions such as the above-mentioned "specific change rate" and "specific concentration range" are preferably set for each manufacturing furnace.

According to one embodiment, it is preferable that in the judgment step (S12), the time to stop the manufacturing step is determined based on the concentration change of the gas component, and in the execution step (S13), based on the time determined in the judgment step (S12) Stop the manufacturing step. According to the research of the inventor, it is found that there is a situation in which the rate of change of the concentration of the gas component changes corresponding to the degree of deterioration of the processing device. For example, depending on the manufacturing furnace, the more the degree of deterioration of the processing device progresses (the closer the life is), the more the rate of change in the concentration of the gas component changes. Regarding this kind of manufacturing furnace, when the rate of change is small (for example, less than 0% to 30%), the stop period of the manufacturing furnace can be set to a later period (for example, a few months to half a year after the judgment step). When the rate of change is large (for example, 30% or more), set the stop period of the manufacturing furnace to an earlier period (for example, one month to one week after the judgment step). Thereby, the processing device can be used as long as possible, and the manufacturing furnace can be stopped at a more appropriate time, thereby improving the effect of suppressing the decrease in the productivity of the glass substrate. In addition, the concentration change amount of the gas component is calculated from the difference between the first concentration (the concentration of the bubble analysis result before the change) and the second concentration (the concentration of the bubble analysis result after the change) determined in the determination step. When the concentration difference obtained from the first concentration to the second concentration is, for example, 20% or more, it is determined that the amount of change is large, and when, for example, it is less than 20%, it is determined that the amount of change is small. It is also possible to change (different) the judgment criterion of the concentration change amount of the gas component (concentration difference calculated from the first concentration-the second concentration) according to the type of gas component. For example, regarding Ar, when the concentration difference is more than 10%, the change is judged to be large, and when the concentration difference is less than 10%, the change is judged to be small. On the other hand, for N ₂ , the concentration difference is 30 If it exceeds %, it is judged that the amount of change is large, and if it is less than 30%, it is judged that the amount of change is small.

According to one embodiment, it is preferable that in the analysis step (S11), at least any one of the internal pressure of the gas component and the depth position of the bubble from the surface of the glass plate is analyzed, and in the judgment step (S12), Furthermore, the analysis result related to at least any one of the internal pressure and the depth position is used for judgment. The internal pressure of the gas component can be calculated by breaking the glass plate in a vacuum chamber to release the gas component in the bubble, using a pressure gauge to detect the total pressure of the released gas component, and using the concentration of the gas component as the partial pressure of the gas component. In the analysis step (S11), the concentration of the gas component is associated with the calculated partial pressure. The depth position of the bubbles can be measured, for example, using a microscope with a function of focusing in the depth direction. According to the research of the present inventor, the bubble whose concentration of two or more of CO ₂ , N ₂ , SO ₂ , and Ar changes has characteristics according to the internal pressure of the gas component or the depth position of the bubble according to the manufacturing furnace . For example, depending on the manufacturing furnace, there is a feature that the internal pressure of most bubbles is low when the concentration of SO ₂ increases, and the internal pressure of most bubbles decreases when the concentration of CO ₂ , Ar, and CO ₂ decreases. Therefore, for example, for bubbles with high SO ₂ concentration but high internal pressure, or bubbles with low CO ₂ , Ar, CO ₂ concentration but high internal pressure, and other bubbles that do not meet the above characteristics, even if the manufacturing furnace is different, CO ₂ , N _{2. When} the concentration of two or more components in SO ₂ and Ar changes, there is also the possibility that it is not related to the degree of deterioration of the processing device. In addition, bubbles in which the concentration of two or more of CO ₂ , N ₂ , SO ₂ , and Ar are changed have the following characteristics: depending on the manufacturing furnace, for example, bubbles are randomly located in the thickness direction of the glass plate. Located in the center of the thickness direction (the area from the center of the thickness along the thickness direction to each side of the thickness direction is 10% of the thickness), or near the main surface (the depth of the main surface is 10% of the thickness Area) (for example, more than 60% of the bubbles in the analysis are located in the depth range), etc. are located at a different depth position than before the concentration change. Therefore, in the judgment step (S12), by excluding the bubbles that do not satisfy the above characteristics from the analysis result, it is possible to judge with high accuracy whether to stop the operation of the manufacturing furnace. By stopping the operation based on the judgment result, the possibility of stopping the manufacturing furnace at an appropriate time is further increased.

According to one embodiment, it is preferable that in the analysis step (S11), bubbles with a size exceeding 1 mm are set as the analysis target. The so-called size means the maximum length of the bubble. Bubbles with a size of more than 1 mm usually have a deformed shape along the extension direction of the main surface of the glass substrate. Therefore, the maximum length of the bubble means the maximum length of the bubble when the glass substrate is viewed in the thickness direction. The upper limit of the bubble size is, for example, 12 mm. The size of the bubbles can be measured using a laser microscope. According to the inventor’s research, the type and composition of gas components are quite different for bubbles with a size of 1 mm or less and bubbles with a size of more than 1 mm. For bubbles with a size of 1 mm or less, there are two or more gas components. The correlation between the change and the degree of deterioration of the processing device is relatively small. Therefore, by setting bubbles with a size of more than 1 mm as the analysis target, high-quality analysis results can be obtained, and the glass substrate manufacturing furnace can be stopped at a more appropriate time. Furthermore, glass substrates containing bubbles with a size of more than 1 mm are obviously defective. If a large number of such glass substrates are included among a plurality of glass substrates cut from the same glass plate, the yield rate decreases, and productivity decreases. Therefore, in terms of improving the productivity of the glass substrate, it is desirable to exclude it from the objects of the grinding step, the polishing step, the cleaning step, and the like. That is, the inspection related to the presence or absence of bubbles with a size exceeding 1 mm is preferably performed after the cutting step (S4) and before the grinding step.

According to this embodiment, the concentration of gas components in the bubbles is analyzed during operation, and the result is based on changes in the concentrations of two or more components among CO ₂ , N ₂ , SO ₂ , and Ar to make a judgment to stop the operation. If the operation is stopped based on the judgment result, the possibility of stopping the manufacturing furnace may increase at an appropriate time when the processing device is deteriorated and must be repaired or replaced. Therefore, according to the present embodiment, the glass substrate manufacturing furnace can be stopped at an appropriate time without reducing the productivity of the glass substrate. In addition, according to the present embodiment, by stopping the operation before the processing device is deformed or broken, it is possible to prevent the glass from leaking from the processing device, etc., thereby preventing damage to the surrounding processing device. Therefore, you can continue to use peripheral processing devices. In addition, when repairing or replacing the processing device, there is no need to process the leaked glass or repair or replace the surrounding processing device, so the period of stopping the operation can be shortened.

The glass substrate to which this embodiment is applied includes, for example, alkali-free glass having the following composition. SiO ₂ : 55-80 mass% Al ₂ O ₃ : 8-20 mass% B ₂ O ₃ : 0-18 mass% RO 0-17 mol% (RO is the total amount of MgO, CaO, SrO and BaO), R _'2 O 0 ~ ₂ mole% (R' ₂ O-based Li ₂ O, Na ₂ O and K ₂ O of the total).

From the viewpoint of reducing the thermal shrinkage rate, SiO _{2 is} preferably 60 to 75% by mass, and more preferably 63 to 72% by mass. Preferably, among RO, MgO is 0-10% by mass, CaO is 0-10% by mass, SrO is 0-10% by mass, and BaO is 0-10% by mass.

In addition, it may include at least SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , and RO and a molar ratio ((2×SiO ₂ )+Al ₂ O ₃ )/((2×B ₂ O ₃ )+ RO) is 4.5 or more glass. Moreover, it is preferable to contain at least any one of MgO, CaO, SrO, and BaO, and the molar ratio (BaO+SrO)/RO is 0.1 or more.

In addition, the total of twice the content of B ₂ O ₃ expressed by mass% and the content of RO expressed by mass% is preferably 30 mass% or less, more preferably 10 to 30 mass %. Furthermore, it is preferable that a total of 0.05 to 1.5% by mass of metal oxides (tin oxide, iron oxide) of varying valence are contained in the molten glass. Preferably, AS ₂ O ₃ , Sb ₂ O ₃ , and PbO are not substantially included, but these may be included arbitrarily. In addition, the glass contains metal oxides (tin oxide, iron oxide) with valence fluctuations of 0.05 to 1.5% by mass in total, and substantially does not contain As ₂ O ₃ , Sb ₂ O _3, and PbO. It is optional but not essential.

The glass substrate manufactured in this embodiment is suitable for a glass substrate for a display including a glass substrate for a flat panel display. Suitable for glass substrates for oxide semiconductor displays using oxide semiconductors such as IGZO (indium, gallium, zinc, and oxygen) and glass substrates for LTPS displays using LTPS (low temperature polysilicon) semiconductors. Moreover, the glass substrate manufactured in this embodiment is suitable for the glass substrate for liquid crystal displays which requires very little content of alkali metal oxide. It is also suitable for glass substrates for organic EL (Electroluminescence) displays. In other words, the manufacturing method of the glass substrate of this embodiment is suitable for the manufacture of glass substrates for displays, and is particularly suitable for the manufacture of glass substrates for liquid crystal displays. Furthermore, it can also be used as cover glass for display or housing of mobile terminal equipment, touch panel, glass substrate or cover glass for solar cell. Especially suitable for glass substrates for liquid crystal displays using polysilicon TFT (thin-film transistor). In addition, the glass substrate manufactured in this embodiment can also be applied to cover glass, glass for magnetic disks, glass substrates for solar cells, and the like.

(Experimental example) Perform the manufacturing steps of the above embodiment to make a glass plate. For the glass plate with bubbles with a size of more than 1 mm, analyze the concentration of gas components in the bubbles on a regular basis. Next, set 1 month as 1 interval, and monitor the moving average of 3 intervals (3 months) for the concentration of each component of CO ₂ , N ₂ , SO ₂ , and Ar. The average value of the concentration in each interval is set as the average value of the concentration of 30 bubbles randomly selected from the glass plate produced in 1 month. When the moving average of two or more of CO ₂ , N ₂ , SO ₂ , and Ar changes beyond the predetermined concentration range for each component, the operation of the manufacturing furnace is stopped (Example). After removing the refractory and confirming the degree of deterioration of each treatment device, it was confirmed that the main body of the clarification tank, that is, the part of the clarification tube that does not contact the molten glass (the wall connected to the gas phase space) had holes. In addition, the size of the hole is a hole that will not hinder the continued operation. It is thought that the air entering the tube from the hole affects the molten glass as the reason why the moving average of two or more components changes as described above. On the other hand, the glass plate was produced with the same points as the examples, and when one of CO ₂ , N ₂ , SO ₂ , and Ar changed over the above temperature range, the operation of the production furnace was stopped (comparative example). The refractory was removed and the degree of deterioration of each treatment device was confirmed. No holes or deformation were confirmed in any treatment device, and it was in a fully usable state. Furthermore, the glass plate was produced by the same method as the example, and the production was not stopped when the moving average of two or more components of CO ₂ , N ₂ , SO ₂ , and Ar was confirmed to be the same as the example. The operation of the furnace, and furthermore, the yield rate dropped significantly when the operation was continued for 6 to 9 months, so the operation was stopped (reference example). After confirming the degree of deterioration of each processing device, in addition to confirming that the size is larger than the hole confirmed in the example and obstructing the continued operation, confirm that the above-mentioned wall of the clarification tube sags as it approaches the liquid level position of the molten glass Deformed parts.

As mentioned above, the present embodiment has been described based on the drawings, but the specific configuration is not limited to the above-mentioned embodiment, and can be changed without departing from the spirit of the invention.

100‧‧‧Melting Device 101‧‧‧Melt Tank 101d‧‧‧ Bucket 102‧‧‧Clarification tank 103‧‧‧Stirring tank 103a‧‧‧Agitator 104‧‧‧Glass Supply Pipe 104a‧‧‧Outlet 105‧‧‧Glass Supply Pipe 106‧‧‧Glass Supply Pipe 200‧‧‧Forming device 210‧‧‧Form 300‧‧‧Cutting device A‧‧‧Wide concentration range B‧‧‧Narrow concentration range MG‧‧‧Molten glass SG‧‧‧Slice glass t1‧‧‧period t2‧‧‧period

Fig. 1 is a flowchart showing an example of the manufacturing steps of the manufacturing method of the glass substrate. Fig. 2 is a schematic diagram showing a glass substrate manufacturing apparatus. Fig. 3 is a flowchart showing the analysis step to the execution step of the glass substrate manufacturing method. Figures 4(a) and (b) are diagrams showing an example of changes in the concentration of gas components.

Claims (7)

A method of manufacturing a glass substrate, characterized by comprising: a manufacturing step of processing molten glass using a processing device, and shaping the processed molten glass into a glass plate; an analysis step of processing the molten glass contained in the glass plate Analyze the concentration of the gas components in the bubbles; a determination step, which uses the analysis results of the above gas components to determine whether to stop the above manufacturing step; and an execution step, which executes the stop of the above manufacturing step based on the determination result in the above determination step; The change in the concentration of two or more of CO ₂ , N ₂ , SO ₂ , and Ar in the above-mentioned gas components is used as a condition for stopping the above-mentioned manufacturing step. The method for manufacturing a glass substrate according to claim 1, wherein the concentration of the above two or more components exceeds the allowable concentration range of each as a condition for stopping the above manufacturing step. For example, the method for manufacturing a glass substrate of claim 1 or 2, wherein a specific period is set as one interval, and each time the specific period elapses, one side is shifted from the interval one by one while calculating the total gas composition of the plurality of consecutive intervals In the moving average obtained from the concentration average, the change in the above-mentioned concentration is used to stop the above-mentioned manufacturing step. Such as the manufacturing method of the glass substrate of claim 1 or 2, wherein in the above determination step, According to the concentration change amount of the gas component, the time to stop the manufacturing step is determined, and in the execution step, the manufacturing step is stopped based on the time determined in the judging step. The method for manufacturing a glass substrate according to claim 1 or 2, wherein in the analysis step, at least any one of the internal pressure of the gas component and the depth position of the bubble from the surface of the glass plate is analyzed, and In the judgment step, the analysis result related to the one of the internal pressure and the depth position is further used to make the judgment. The method for manufacturing a glass substrate of claim 1 or 2, wherein in the above analysis step, the above-mentioned bubbles with a size exceeding 1 mm are set as the analysis object. A glass substrate manufacturing device, characterized by comprising: manufacturing equipment that uses a processing device to process molten glass and shape the processed molten glass into a glass plate; an analysis device that detects air bubbles contained in the glass plate Analyze the concentration of the gas component in the gas composition; a judgment device that uses the analysis result of the gas component to judge whether to stop the operation of the manufacturing equipment; and an execution device that executes the stop of the operation of the manufacturing equipment based on the judgment result of the judgment device ; The change in the concentration of two or more of CO ₂ , N ₂ , SO ₂ , and Ar in the above-mentioned gas components is used for the above-mentioned conditions for stopping the operation of the manufacturing equipment.

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