KR20130113973A - Method and apparatus for making glass sheet - Google Patents

Abstract

PURPOSE: A glass plate manufacturing method is provided to control the temperature for heating a refining pipe to be low, thereby manufacturing a glass plate while suppressing the volatilization of platinum from the refining pipe composed of platinum or a platinum alloy. CONSTITUTION: A glass plate manufacturing method includes the following steps of: manufacturing molten glass by melting a glass row material; and refining the molten glass by heating the molten glass. The refining process of the molten glass is performed inside a transfer pipe and a refining pipe. The transfer pipe is composed of platinum or a platinum alloy and heats the molten glass from an outer wall. The refining pipe composed of platinum or a platinum alloy has a cross section larger than that of the transfer pipe and includes a virtual space for the defoamation of the molten glass. The transfer pipe is fully filled with the molten glass, and the molten glass flows inside the transfer pipe. The first maximum temperature of the molten glass when the molten glass flows in the transfer pipe is the second maximum temperature of the molten glass or greater. [Reference numerals] (202) Clarifying pipe; (204) Glass supply pipe; (AA) Temperature

Description

The manufacturing method of a glass plate, and the manufacturing apparatus of a glass plate {METHOD AND APPARATUS FOR MAKING GLASS SHEET}

This invention relates to the manufacturing method and manufacturing apparatus of the glass plate which manufactures a glass plate.

Conventionally, when manufacturing a glass plate, a glass raw material is melted in a dissolution tank, a molten glass is produced, and this molten glass is supplied to the clarification pipe | tube comprised of platinum or a platinum alloy through a transfer pipe.

In the conveyance pipe which supplies a molten glass to a clarification pipe | tube, the molten glass is heated so that the molten glass produced by the melting tank may not fall, ie, the temperature of a molten glass is maintained.

In a clarification pipe | bubble, the bubble in a molten glass flows in the oxygen gas discharged | emitted by the reducing effect of the clarifier contained in a molten glass, grows the bubble in a molten glass, floats to the liquid level of a molten glass, and defoases. ) In order to perform the reducing effect of the said clarifier effectively, and to lower | hang the viscosity of a molten glass and to carry out the floating of the bubble in the liquid level effectively, the clarification pipe | tube heats its outer wall and heats up a molten glass. Thereafter, the bubbles remaining in the molten glass are lowered by the molten glass in order to absorb the oxygen gas in the bubbles and dissipate the bubbles by the oxidation action of the clarifier.

When the molten glass is supplied to the clarification tube by such a conveying tube, and the molten glass clarified by the clarification tube is seen in the temperature profile along the flow of the molten glass, since the molten glass raises a temperature and then descends, it is clarified In the tube, the molten glass reaches its maximum temperature.

The following patent document 1 is mentioned as an example of the manufacturing method of the said glass plate. In patent document 1, the molten glass which flowed out from the melting furnace heats up in the clarification pipe | tube 22 shown in FIG. 1 of the said document, and reaches | attains the highest temperature.

On the other hand, in recent years, the temperature of the molten glass in a clarification pipe | tube is often made high temperature compared with the past. As those factors, the glass sheet, in terms of reduction of the one used for the glass substrate for a flat panel display such as a liquid crystal display or organic EL display, and the environmental load, without using a refining agent such as As ₂ O _3, SnO ₂ The use of clarifiers, such as these, is mentioned.

When used for glass plates for flat panel displays such as liquid crystal displays and organic EL displays, alkali metal components such as Li, Na, and K are not used at all in order to prevent damage to TFTs (Thin Film Transistors) formed on the glass plates for flat panel displays. Alkali trace amount containing glass which is an alkali free glass which does not contain or is a trace amount even if it contains an alkali metal component is used. This alkali free glass or alkali trace amount containing glass is low in solubility and high temperature viscosity. For this reason, in order to perform the defoaming of the molten glass in the clarification pipe mentioned above effectively, and to eliminate an air bubble effectively, a molten glass is heated up higher than the conventional thing in a clarification pipe.

In addition, from the viewpoint of reducing the environmental load, SnO ₂ or the like having less toxicity as a clarifier is less than that of As ₂ O ₃ , but is preferably used. However, in order to function such a clarifier suitably, it is necessary to make temperature of a molten glass higher than before.

 For this reason, the highest temperature of the molten glass which flows in the clarification pipe mentioned above also becomes high compared with the past.

Japanese Patent Publication No. 2010-523457

Thus, in order to make molten glass high temperature, the clarification pipe comprised from platinum or a platinum alloy needs to be heated at high temperature compared with the past. For example, when using a SnO ₂ as a fining agent, the temperature of the molten glass in order to effectively function the refining capabilities of the SnO ₂ is raised to about 1700 ℃. For this reason, a part of the platinum or platinum alloy which comprises the clarification pipe heated at high temperature compared with the prior art volatilizes, and there exists a problem that the life of a clarification pipe | tube becomes short compared with the conventional one, since the thickness of a clarification pipe becomes thin easily.

In addition, although a gaseous phase for defoaming molten glass exists in a clarification pipe | platform, platinum is volatilized from the clarification pipe inner wall surface which contact | connects this gaseous phase, a part of it cools and solidifies, and the inside of a clarification pipe It is attached to the wall (ceiling part) as a crystal. This deposit may fall as microparticles | fine-particles in the molten glass which flows through a clarification pipe | tube, and may flow as a foreign material in a molten glass to a downstream process, and may cause the defect of a glass plate.

Therefore, an object of this invention is to provide the manufacturing method and manufacturing apparatus of the glass plate which can manufacture a glass plate, suppressing volatilization of platinum from the clarification pipe comprised from platinum or a platinum alloy, in order to solve the conventional problem. do.

1 aspect of this invention is a manufacturing method of the glass plate which manufactures a glass plate. In the above manufacturing method,

Melting the glass raw material to make molten glass,

It includes the process of clarifying the said molten glass by heating up the said molten glass.

Clarification of the said molten glass is a tube which consists of platinum or a platinum alloy, The transfer tube of the said molten glass heated up by heating the said molten glass from an outer wall, and the tube which consists of platinum or a platinum alloy, and is larger than the cross section of the said transfer tube. It has a cross section, is supplied in the said fusion glass from the said transfer pipe, and it is performed in the clarification pipe which has the gaseous-phase space for defoaming of the said molten glass with flow.

In the said transfer pipe, the said molten glass fills and flows in the whole inside end surface of the said transfer pipe.

The 1st highest temperature of the said molten glass when the said molten glass flows through the said conveyance pipe is equal to or higher than the 2nd highest temperature of the said molten glass when flowing the said clarification pipe.

Since the 1st highest temperature of the said molten glass is equal to or higher than the 2nd highest temperature of the said molten glass at the time of flowing the said clarification pipe | bubble, the bubble in a molten glass grows large in the said transfer pipe. For this reason, a bubble floats on the liquid level of a molten glass in the said clarification pipe | tube, and it is easily defoamed. When the molten glass moves from the transfer pipe to the clarification tube, the temperature of the molten glass is sufficiently high and maintained above the temperature at which the reduction reaction of the clarifier occurs, so that the clarification tube needs heating to further raise the molten glass. Do not For this reason, the said clarification pipe heating temperature can be suppressed lower than before. Therefore, the volatilization of platinum is suppressed from the said clarification tube which consists of platinum or a platinum alloy, and the glass plate with few defects resulting from a foreign material, such as a platinum crystal which adheres to the inner wall surface in a clarification tube by volatilization of platinum, can be manufactured. have.

It is preferable that the temperature of the said molten glass reaches | attains the said 1st highest temperature while the said molten glass flows through the said conveyance pipe.

In this case, since the heating temperature of the said clarification pipe | tube becomes low compared with the case where the molten glass reaches the said 1st highest temperature and the said 2nd highest temperature in the connection position of the said transfer pipe and the said clarification pipe, it consists of platinum or a platinum alloy. The volatilization of platinum can be suppressed more easily from the said clarification pipe | tube which becomes.

SnO ₂ may be included in the molten glass as a clarifier.

SnO ₂ has a lower clarification function than As ₂ O ₃ , which is a conventional clarifier, but can be suitably used as a clarifier from a low environmental load. However, the SnO ₂ is because the refining function is lower than the As ₂ O _3, SnO _2, if using the above-mentioned, should raise the temperature of the molten glass during the refining process of molten glass than the prior art. In the production method of the above-mentioned glass sheet, it is possible to suppress lowering the heating temperature in the fining tube than in the prior art, even when using a molten glass comprising the SnO ₂ as a fining agent, the consisting of platinum or platinum alloy fining tube Volatilization of platinum can be suppressed, and the glass plate with few defects resulting from foreign substances, such as a platinum crystallization, can be manufactured.

The glass used for the said glass plate can make temperature in 10 ^2.5 poise to 1500 degreeC or more. Furthermore, the said temperature can be 1550 degreeC or more, Furthermore, it can be 1600 degreeC or more.

Such molten glass is glass with high viscosity. In the said manufacturing method, since the heating temperature of the said clarification pipe | tube can be suppressed below conventionally, even if it is glass with high viscosity, platinum volatilization can be suppressed more easily from the said clarification pipe | tube comprised by platinum or a platinum alloy.

The time (minutes) that the molten glass passes through the said transfer pipe is Time, and the temperature rises from the temperature of the said molten glass in the inlet of the said transfer pipe to the said 1st highest temperature of the said molten glass which flows through the said transfer pipe. When the temperature difference is ΔT (° C), it is preferable that ΔT / Time is 3 to 10 (° C / minute).

In order to make the temperature of a molten glass into the said 1st highest temperature in the said transfer pipe, a molten glass is heated. In this case, increasing the heating temperature of the transfer tube made of platinum or platinum alloy promotes the volatilization of platinum, which is undesirable from the viewpoint of the life of the transfer tube. For this reason, by making (DELTA) T / Time into 3-10 (degreeC / min), the temperature difference between the heating temperature of the said transfer pipe and the temperature of a molten glass is made small. As a result, the degree of increase in the heating temperature of the transfer pipe can be suppressed to increase the life of the transfer pipe.

Moreover, another 1 aspect of this invention is a manufacturing method of the glass plate which manufactures a glass plate. In the above manufacturing method,

Melting the glass raw material to make molten glass,

After the temperature of the said molten glass is raised, the temperature of the said molten glass is clarified by temperature-falling continuously or continuously.

Clarification of the said molten glass is a tube which consists of platinum or a platinum alloy, The transfer tube of the said molten glass heated up by heating the said molten glass from an outer wall, and the tube which consists of platinum or a platinum alloy, and is larger than the cross section of the said transfer tube. It has a cross section, it is supplied at least from the said conveying pipe, and the said molten glass is performed at least in the clarification pipe which has the gaseous-phase space for defoaming of the said molten glass with flow.

In the said transfer pipe, the said molten glass fills and flows in the whole inside end surface of the said transfer pipe.

In the said transfer pipe, after making the temperature of the said molten glass into the maximum temperature in the said clarification by the said temperature rising of the said molten glass, in the said clarification pipe | tube, the temperature of the said molten glass is said highest by the said temperature fall of the said molten glass. Maintain at or below the temperature.

Since the temperature of a molten glass becomes the maximum temperature in the said clarification in the said conveyance pipe | bubble, the bubble in a molten glass grows in the said conveying pipe, floats on the liquid level of a molten glass in the said clarification pipe | tube, and is easily defoamed. When the molten glass moves from the transfer pipe to the clarification pipe, the temperature of the molten glass in the clarification pipe is kept at a temperature lower than the maximum temperature, so that heating for further raising the molten glass is not necessary. For this reason, the heating temperature of the said clarification pipe | tube can be suppressed lower than before. Therefore, the volatilization of platinum is suppressed from the said clarification tube which consists of platinum or a platinum alloy, and the glass plate with few defects resulting from a foreign material, such as a platinum crystal which adheres to the inner wall surface in a clarification tube by volatilization of platinum, can be manufactured. have.

Another embodiment of the present invention is a manufacturing apparatus for a glass plate for producing a glass plate. The manufacturing apparatus,

A melting tank for melting glass raw materials to make molten glass,

A clarification tube made of platinum or a platinum alloy to clarify the molten glass while flowing;

A tube composed of platinum or a platinum alloy includes a transfer tube for melting the molten glass by connecting the dissolution tank and the clarification tube and heating the outer wall to raise the molten glass to clarify the molten glass.

The said clarification pipe | tube has a cross section larger than the cross section of the said transfer pipe, and has a gaseous-phase space for defoaming of the said molten glass.

The said 1st highest temperature of the said molten glass when the said molten glass flows through the said conveyance pipe is the said transfer so that it may become equal to or higher than the 2nd highest temperature of the said molten glass when the said molten glass flows through the said clarification pipe | tube. The tube is heated and adjusted.

In the said manufacturing apparatus, since the said conveyance pipe is heat-adjusted so that the 1st highest temperature of a molten glass may be equal to or higher than the said 2nd highest temperature, the bubble in the molten glass which grew in the said conveyance pipe is a It floats on the liquid level of the molten glass and is easily defoamed. When the molten glass moves from the transfer pipe to the clarification tube, the temperature of the molten glass is sufficiently high and maintained above the temperature at which the reduction reaction of the clarifier occurs, so that the clarification tube is heated to further heat the molten glass. I don't need it. For this reason, the heating temperature of the said clarification pipe | tube can be suppressed lower than before. Therefore, the said manufacturing apparatus can suppress volatilization of platinum from the said clarification pipe | tube comprised from platinum or a platinum alloy. Moreover, the glass plate with few defects resulting from foreign matters, such as a platinum crystal substance which arises by volatilization of platinum, can be manufactured.

According to the manufacturing method and manufacturing apparatus of the glass plate of this invention, volatilization of platinum can be suppressed from the clarification pipe | tube comprised from platinum or a platinum alloy, and the glass plate with few defects resulting from foreign substances, such as a platinum crystallization, can be manufactured.

BRIEF DESCRIPTION OF THE DRAWINGS The process chart of the manufacturing method of the glass plate of this embodiment.
It is a figure which shows typically the apparatus which performs the melting process-the cutting process of the manufacturing method of the glass plate of this embodiment.
3 is a diagram mainly showing an apparatus configuration for performing a clarification step of the method for manufacturing a glass plate of the present embodiment.
The figure which shows the example of the temperature profile of the flow direction of the molten glass in the glass supply pipe and clarification pipe which are used by the manufacturing method of the glass plate of this embodiment.

Hereinafter, the manufacturing method of the glass plate of this embodiment is demonstrated.

(Full summary of the manufacturing method of the glass plate)

1 is a flowchart of a method of manufacturing the glass plate of the present embodiment.

The manufacturing method of a glass plate is a melting process (ST1), a clarification process (ST2), a homogenization process (ST3), a supply process (ST4), a molding process (ST5), a slow cooling process (ST6), a cutting process It mainly has (ST7). In addition, the some glass plate which has a grinding process, a grinding process, a washing process, an inspection process, a packing process, etc., and was laminated by the packing process is conveyed to the supplier of a delivery destination.

FIG. 2: is a figure which shows typically the apparatus which performs melt | dissolution process (ST1)-cutting process (ST7).

As shown in FIG. 2, the apparatus mainly includes a melting apparatus 200, a molding apparatus 300, and a cutting apparatus 400. The dissolution apparatus 200 mainly has a dissolution tank 201, a clarification pipe 202, a stirring tank 203, and glass supply pipes 204, 205, and 206. In addition, the glass supply pipes 204 and 205 are tubes which flow molten glass MG as mentioned later, and also have a clarification function. The glass supply pipe 204 is a transfer pipe made of platinum or a platinum alloy, and is heated by heating the molten glass from the outer wall. In the glass supply pipe 204, a molten glass fills and flows in the whole inside end surface of the glass supply pipe 204. In addition, after the dissolution tank 201, the glass supply pipes 204, 205, 206 to the shaping | molding apparatus 300, and the main-body part of the clarification pipe tank 202 and the stirring tank 203 are comprised by platinum or a platinum alloy pipe. have.

Dissolving step (ST1) In, SnO ₂ is added as a refining agent to obtain a molten glass by MG dissolves in the glass raw material fed into the melting vessel 201, with the flame and the electrode, not shown, energization heating. Specifically, a glass raw material is supplied to the liquid level of molten glass MG using a raw material input device (not shown). The glass raw material is heated by heat radiation in a gaseous phase to a high temperature with a flame emitted from an oxygen burner or an air burner, and gradually melts, and melts in molten glass MG. In addition, the molten glass MG is heated up by Joule heat generated by the energization heating of the alternating current using the electrode inserted in the side wall of the dissolution tank 201. For example, molybdenum, platinum or tin oxide is used as the electrode material for the electrode.

In addition, although the above description demonstrated the example which melts a glass raw material using burners, such as an oxygen burner or an air burner, and an electrode, you may melt | dissolve a glass raw material only by a burner, and may melt | dissolve a glass raw material only by an electrode. It is preferable that the temperature of molten glass MG in the dissolution tank 201 is a temperature at which the reduction reaction of a clarifier does not generate | occur | produce, and oxygen release does not occur abruptly. Temperature of the molten glass in the melting vessel in the MG 201 as a refining agent, such as a temperature not higher than 1620 ℃ case of using the tin oxide (SnO _2).

The clarification process ST2 is performed in the glass supply pipe 204, the clarification pipe 202, and the glass supply pipe 205. In particular, the clarification step includes a defoaming step and a bubble absorption step. In the degassing process, whereby the molten glass within the glass supply line MG 204 is raised, O _2, CO ₂ or SO ₂ contained in the molten glass MG Bubbles containing such gas components absorb and grow O ₂ generated by a reduction reaction of a clarifier, for example, SnO ₂ . In the clarification pipe | tube 202, the bubble which grew of molten glass MG floats at the liquid level of molten glass MG, and the gas in bubble is discharge | released to gaseous phase. In addition, in a bubble absorption process, the internal pressure of the gas component in the bubble by the fall of the temperature of molten glass MG falls, and the reducing substance obtained by the reduction reaction of a clarifier, for example, SnO, reduces the temperature of molten glass MG. O ₂ in the bubble remaining in molten glass MG by performing oxidation reaction by Gas components, such as these, are reabsorbed in molten glass MG and foam | bubble disappears. Oxidation reaction and reduction reaction by a clarifier are performed by adjusting the temperature of molten glass MG. Adjustment of the temperature of molten glass MG is performed by adjusting the temperature of the glass supply pipe 204, the clarification pipe 202, and the glass supply pipe 205. FIG. Adjustment of the temperature of each pipe | tube is carried out using the direct electric heating which flows electricity to the pipe | tube itself, or using the heater arrange | positioned around the glass supply pipe 204, the clarification pipe | tube 202, and the glass supply pipe 205, respectively. It is performed by indirect heating to heat.

In the adjustment of the temperature of the molten glass MG of this embodiment, direct current heating which is one of the methods mentioned above is used. Specifically, an electric current flows between the metal flange (not shown) provided in the glass supply pipe 204 which supplies molten glass MG to the clarification pipe 202, and the metal flange (not shown) provided in the clarification pipe 202 ( 3) between the metal flange (not shown) provided in the clarification pipe 202 and the metal flange (not shown) provided in the clarification pipe 202 downstream of the molten glass MG with respect to the metal flange. The temperature of molten glass MG is adjusted by flowing an electric current (arrow in FIG. 3). In the present embodiment, the temperature of the molten glass MG is adjusted by energizing the glass supply pipe 204 and the clarification pipe 202 by energizing each constant current in the first area between the metal flanges and the second area between the metal flanges. However, this energization heating is not limited to the temperature adjustment by the energization heating of two area | regions, Electric current heating is performed in three or more areas, and temperature control of molten glass MG can also be performed.

In homogenization process ST3, the glass component is homogenized by stirring molten glass MG in the stirring tank 203 supplied through the glass supply pipe 205 using the stirrer 203a. Two or more stirring tanks 203 may be provided.

In supply process ST4, molten glass is supplied to the shaping | molding apparatus 300 via the glass supply pipe 206. As shown in FIG.

In the molding apparatus 300, a molding step (ST5) and a slow cooling step (ST6) are performed.

In shaping | molding process ST5, molten glass MG is shape | molded by plate glass G, and the flow of plate glass G is created. In this embodiment, the overflow down draw method using the molded object 310 mentioned later is used. In slow cooling process ST6, the plate-shaped glass G shape | flows is cooled so that internal distortion and curvature may not generate | occur | produce.

In cutting process ST7, the glass plate is obtained by cutting the plate-shaped glass G supplied from the shaping | molding apparatus 300 to predetermined length in the cutting device 400. FIG. The cut glass plate is cut into a predetermined size again, and a glass plate of a target size is produced. After that, grinding, polishing, and washing of the glass plate of the end face of the glass are performed, and the presence or absence of defects such as bubbles is examined, and then the glass plate of the inspection pass product is packed as a final product.

(Cleaning Process)

3 is a diagram mainly showing an apparatus configuration for performing a clarification step. The clarification process includes a defoaming process and an absorption process. In the following description, it will be described as an example using a refining agent SnO _2. SnO ₂ has a lower clarification function than conventional As ₂ O ₃ , but can be suitably used as a clarifier from a viewpoint of low environmental load. However, SnO ₂ is, since the refining capability is low compared to As ₂ O _3, the case of using SnO _2, should increase the temperature of the molten glass during fining process MG MG of molten glass than the prior art. In this case, for example, the maximum temperature in the clarification step may be about 1700 ° C, preferably 1710 ° C or less, and more preferably 1720 ° C or less.

According to FIG. 3, clarification is demonstrated.

Liquid molten glass MG which melt | dissolves in the dissolution tank 201 and contains many bubbles B produced | generated by the decomposition reaction of a glass raw material is introduce | transduced into the glass supply pipe 204.

In the glass supply pipe 204, molten glass MG is heated to 1630 degreeC or more and 1720 degrees C or less by heating of the platinum or platinum alloy tube which is the main body of the glass supply pipe 204, and the reduction reaction of a clarifier is accelerated | stimulated, Large amounts of oxygen are released into the molten glass MG. The existing bubble B in the molten glass MG expands the bubble diameter by the effect of the synergistic effect of the pressure of the gas component in the bubble B caused by the temperature rise of the molten glass MG, and oxygen released by the reduction reaction of the clarifier bubbles. It spreads and inflows into B, and the bubble diameter of the existing bubble B expands by this synergistic effect.

Then, this molten glass MG is introduce | transduced into the clarification pipe | tube 202.

Unlike the glass supply pipe 204, the clarification pipe | tube 202 has a gaseous-phase space in the upper part inside the glass supply pipe 202. As shown in FIG. In the clarification pipe | tube 202, the bubble B in molten glass MG floats at the liquid level of molten glass MG, and is able to discharge | emit out of molten glass MG. In addition, the temperature of molten glass MG may be adjusted low so that the viscosity of glass in this state may be 120-400 poise, for example to the extent which does not prevent the floating of bubble B by the viscosity fall of molten glass MG.

In the clarification pipe | tube 202, the molten-glass MG is maintained at the high temperature of 1630 degreeC or more and 1720 degrees C or less by heating of the platinum or platinum alloy tube which is the main body of the clarification pipe | tube 202. Or although molten glass MG is slightly lower than the temperature of molten glass MG at the time of introduction into the clarification pipe | tube 202, it is still in a defoaming process. For this reason, the bubble B in the molten glass MG floats toward the upper side of the clarification pipe | tube 202, and the molten glass MG is defoamed by removing the bubble from the liquid surface of the molten glass MG.

Here, bubbles are removed from the gas phase space above the clarification pipe 202, and the released gas component is discharged out of the clarification pipe 202 from a gas discharge port (not shown). In the clarification pipe | tube 202, the bubble B of large diameter with a quick float speed is removed by the floating and defoaming of bubble B. As shown in FIG.

 In this embodiment, the highest temperature (first highest temperature) of the molten glass MG when the molten glass MG flows through the glass supply pipe 204 is the highest temperature (second of the molten glass MG when flowing through the clarification pipe 202). Peak temperature) or higher. Equivalent here means an allowable range when the temperature difference between the first highest temperature and the second highest temperature is ± 10 ° C, preferably ± 5 ° C, in addition to the case where the first highest temperature coincides with the second highest temperature. Include. Thus, in the clarification pipe 202, making the 1st highest temperature of the molten glass MG at the time of flowing the glass supply pipe 204 more than the 2nd highest temperature of the molten glass MG at the time of flowing the clarification pipe 202 is carried out. This is for degassing | defoaming efficiently in the clarification pipe | tube 202, suppressing the heating temperature of molten glass MG of this.

That is, in the glass supply pipe 204, the bubble B in the molten glass MG is further expanded by the expansion of the bubble diameter due to the supply of oxygen released by the clarifier and the synergistic effect of the pressure of the gas component in the bubble B. By lowering, bubble B starts to float upwards.

In this state, the molten glass MG is introduced into the clarification pipe 202. In the glass supply pipe 204, since molten glass MG flows and fills the whole inner end surface of the glass supply pipe 204, defoaming of molten glass MG does not occur. On the other hand, in the clarification pipe | tube 202, since the gaseous-phase space is formed above the clarification pipe | tube 202, and is connected with air | atmosphere, the bubble B which grew large rises to the liquid level of molten glass MG, and removes a bubble.

Thereafter, the molten glass MG is gradually lowered (stepwise or continuously) and proceeds to the absorption step of bubbles in the second half portion of the clarification pipe 202 and the glass supply pipe 205. In the absorption step, as described above, the bubble B is absorbed into the molten glass MG and extinguished by the temperature drop of the molten glass MG. The temperature drop of molten glass MG is performed by supplying electric currents other than the electric current shown in FIG. 3 from a metal flange (not shown), and controlling the latter part of the clarification pipe | tube 202 and the glass supply pipe 205 by heat control.

Regarding such molten glass MG, when the temperature profile of the flow direction of the molten glass MG in the glass supply pipe 204, the clarification pipe 202, and the glass supply pipe 205 is seen, the molten glass in the glass supply pipe 204 The 1st highest temperature is more than the temperature which the reduction reaction of a clarifier produces, for example, it is 1720 degrees C or less. On the downstream side of the molten glass MG, the molten glass MG is heat-adjusted so that it may become a temperature equal to or lower than a 1st highest temperature from the position of this 1st highest temperature. Therefore, the 1st highest temperature of molten glass MG when molten glass MG flows through the glass supply pipe 204 is equal to or higher than the 2nd highest temperature of molten glass MG when flowing through the clarification pipe 202. As shown in FIG.

In other words, in a clarification process, after heating up molten glass MG beyond the temperature which the reduction reaction of a clarifier produces, it temperature-falls continuously or continuously. At this time, in the glass supply pipe 204, after the temperature of the molten glass MG is set to the maximum temperature (first highest temperature) in the clarification by the elevated temperature of the molten glass MG, in the clarification pipe 202, the temperature of the molten glass MG As a result, the temperature of the molten glass is maintained at a temperature equivalent to or lower than the maximum temperature.

4 shows an example of a temperature profile in the flow direction of the molten glass MG in the glass supply pipe 204 and the clarification pipe 202. In the temperature profile A shown in FIG. 4, the molten glass MG is rapidly heated in at least the first half portion of the glass supply pipe 204, and on the downstream side of the flow of the molten glass MG thereafter, the heating of the glass supply pipe 204 is maintained. May be inhibited. Thereby, in position X, molten glass MG becomes a 1st highest temperature. The first highest temperature is at least the temperature at which the reduction reaction of the clarifier occurs, and the temperature of the molten glass MG is at least the temperature at which the reduction reaction of the clarifier occurs until at least the molten glass MG proceeds to the clarifier tube 202. It is. For this reason, when molten glass MG advances from the glass supply pipe 204 to the clarification pipe | tube 202, oxygen is discharge | released from the clarifier to the molten glass MG.

On the other hand, in the clarification pipe | tube 202, the molten glass MG is in the state of a defoaming process at least in the first half part of the clarification pipe | tube 202. Therefore, in the clarification pipe | tube 202, it floats to the liquid level of molten glass MG, and bubble removal of bubble B is performed. Thereafter, as shown in the temperature profile A, the molten glass MG is gradually lowered to temperature and proceeds to the absorption step. The temperature drop of the molten glass MG may continue not only in the glass supply pipe 205 but also in the stirring vessel 203 and the glass supply pipe 206. And when molten glass MG advances to the shaping | molding apparatus 300, it is temperature-falled so that it may become a viscosity suitable for a shaping | molding process.

The position of the highest temperature (2nd highest temperature) of the molten glass MG in the clarification pipe | tube 202 in temperature profile A is the connection part to which the glass supply pipe 204 and the clarification pipe | tube 202 are connected. Therefore, in the temperature profile A, the highest temperature (first highest temperature) of the molten glass MG when the molten glass MG flows through the glass supply pipe 204 is the highest temperature of the molten glass MG when flowing through the clarification pipe 202 ( 2nd highest temperature) is equivalent to or higher.

Regarding the temperature profile of the molten glass MG, the position of the highest temperature (first highest temperature) of the molten glass MG when the molten glass MG flows through the glass supply pipe 204 and the molten glass MG when flowing through the clarification pipe 202. The position of the highest temperature (second highest temperature) may be a connecting portion between the glass supply pipe 204 and the clarification pipe 202. In this case, the first highest temperature is equivalent to the second highest temperature. That is, in this case, the temperature profile becomes the same as the temperature profile C shown in FIG. However, like the temperature profile A, while molten glass MG flows through the glass supply pipe 204, it is preferable that the temperature of the molten glass MG reaches the 1st highest temperature from the point which can suppress the heating of the clarification pipe 202. Do.

Thus, in the glass supply pipe 204, the molten glass in the glass supply pipe 204 by providing the position of the highest temperature of molten glass MG in the place of the glass supply pipe 204 among the glass supply pipe 204, the clarification pipe 202, and the glass supply pipe 205. Bubble B in MG grows large. For this reason, bubble B floats on the liquid level of molten glass MG in the clarification pipe | tube 202, and is easily defoamed. For this reason, the bubble B can be defoamed by the clarification pipe | tube 202 similarly conventionally.

When the molten glass MG moves from the glass supply pipe 204 to the clarification pipe 202, since the temperature of the molten glass MG is maintained above the temperature at which the reduction reaction of a clarifier occurs, in the clarification pipe 202, the molten glass It is not necessary to make MG higher. For this reason, the heating temperature of the clarification pipe | tube 202 can be suppressed lower than before.

Moreover, in the molten glass MG in the clarification process which flows through the glass supply pipe 204, the clarification pipe 202, and the glass supply pipe 205, when the molten glass MG flows through the glass supply pipe 204, the outer wall of the glass supply pipe 204 By accelerating the molten glass MG from the molten glass MG reaches the maximum temperature.

Conventionally, in the clarification pipe | tube 202 whose inner cross-sectional area is larger than the glass supply pipe | tube 204, the outer wall of the clarification pipe | tube 202 was heated so that the temperature of molten glass MG may reach the maximum temperature in a clarification process. For this reason, the ratio of the contact area which contacts the outer wall with respect to the volume of the molten glass MG is small, and the temperature increase effect of the molten glass MG with respect to the heating of an outer wall is not large. In addition, since the clarification pipe | tube 202 has the gaseous-phase space which molten glass MG does not flow, the temperature rising effect of molten glass MG is small. However, in the glass supply pipe 204 like the present embodiment, the molten glass MG is filled and flows in the entire inner end surface of the glass supply pipe 204, and therefore, the inner cross-sectional area of the glass supply pipe 204 is the clarification pipe 202. Since it is small compared with the inner cross-sectional area of, in the glass supply pipe 204, the temperature increase effect of the molten glass MG by the heating from an outer wall is large.

In addition, since the outer wall of the clarification pipe | tube 202 was heated so that the temperature of molten glass MG may reach the maximum temperature in the clarification process in the clarification pipe | tube 202 which has a gaseous-phase space, the platinum which comprises the clarification pipe | tube 202 is conventionally made. Alternatively, the platinum alloy was volatilized, a part of which was partially cooled and solidified, and adhered to the inner wall surface (ceiling portion) in the clarification pipe 202 as a crystal. This deposit fell as foreign matter in the molten glass MG flowing through the clarification pipe | tube 202, and flowed into the downstream process as a foreign material in the molten glass MG, and may cause mixing of microparticles | fine-particles to a glass plate.

On the other hand, in this embodiment, since the position where molten glass MG reaches the maximum temperature in a clarification process does not exist in the clarification pipe | tube 202, platinum or a platinum alloy volatilizes and the inner wall surface (ceiling part) in the clarification pipe | tube 202 is carried out. Adhering to the crystal as a crystal is suppressed. For this reason, it is suppressed that it flows into a downstream process as a foreign material in molten glass MG.

In recent years, the glass plate tends to be manufactured by making the temperature of molten glass MG high in the clarification process using glass with high high temperature viscosity conventionally.

Specifically, in the case of a glass plate used for a flat panel display (liquid crystal display, organic EL display, etc.) using a TFT (Thin Film Transistor), in the present embodiment, from the viewpoint of suppressing the influence of the TFT, no alkali-free glass is used. An alkali trace glass plate using the alkali trace glass plate or the alkali trace amount containing glass which contains a trace amount of an alkali component suitably is manufactured. However, the solubility of an alkali trace amount containing glass plate or an alkali free glass plate is low. Specifically, the temperature at which the logeta = 2.5 is at the viscosity η of the molten glass MG is 1500 ° C to 1750 ° C, and this temperature is higher than that of the alkali glass. The molten glass which has such a viscosity should make temperature of molten glass MG in a clarification process higher than when manufacturing the glass plate of conventional alkali glass.

Further, as the refining agent, such that the environmental load, such as SnO ₂ Eg As ₂ O ₃ It is used instead of the back. However, SnO ₂ with low environmental load Etc., in order to accelerate the reduction reaction, the temperature of the molten glass MG must be higher than in the related art.

Thus, since the clarification pipe | tube 202 tends to be heated to higher temperature, in order to make temperature of molten glass MG higher than before, volatilization of the platinum which comprises a clarification pipe | tube is easy to generate | occur | produce. However, in this embodiment, the position where the molten glass MG reaches the maximum temperature in the clarification process is not the clarification pipe 202 but the glass supply pipe 204. Therefore, even if it is glass with high temperature viscosity, for example, even if it is glass whose temperature in 10 ^2.5 poise is 1500 degreeC or more, in this embodiment, heating of the clarification pipe | tube 202 can be suppressed rather than before. Thereby, since volatilization of the platinum of the clarification pipe | tube 202 can be suppressed, there are few crystal | crystallizations adhering to the inner wall surface (ceiling part) of the clarification pipe | tube 202. As a result, a part of a crystal | crystallization becomes a microparticle in the clarification pipe | tube 202, falls out in molten glass MG, is mixed in molten glass MG, and it can suppress that microparticles | fine-particles mix in the glass plate which is a final product.

That is, in glass with high temperature viscosity, the effect of this embodiment becomes remarkable compared with the past. The high temperature viscosity of glass is 10 the temperature at ^2.5 poise but more than 1500 ℃, at 10 the temperature at ^2.5 poise or more 1550 ℃ glass, and even more than 1600 ℃ glass, the effect of the present embodiment becomes more significant as compared with the conventional . Further, by using a SnO ₂ as a fining agent, when it is necessary to increase the temperature of the molten glass MG in the refining process, the effects of the embodiment becomes remarkable compared to the prior art.

In order to implement this manufacturing method of a glass plate more concretely, the time which the molten glass MG passes through the glass supply pipe 204 makes Time (minute), and the inlet (outlet of the melting tank 201) of the glass supply pipe 204 is made. When the temperature difference of the temperature rising from the temperature of the molten glass MG in to the 1st highest temperature of the molten glass MG which flows through the glass supply pipe 204 is (DELTA) T (degreeC), (DELTA) T / Time is 3-10 (degreeC). / Min) is preferred. In order for the temperature of the molten glass MG to reach the 1st highest temperature in the glass supply pipe 204, the platinum or platinum alloy which comprises the glass supply pipe 204 is heated, but heat transfer from platinum or platinum alloy to molten glass MG is efficiently performed. In order to make it (in order to make temperature of molten glass MG into 1st highest temperature in a short time), what is necessary is just to heat a platinum or a platinum alloy higher. However, heating the platinum or the platinum alloy higher promotes volatilization of the platinum and is not preferable in view of the life of the glass supply pipe 204 composed of expensive platinum or the platinum alloy. For this reason, instead of reducing the temperature difference between the heating temperature of the glass supply pipe 204 and the temperature of the molten glass MG, melting the glass supply pipe 204 by making molten glass lengthen the passage time Time (minute) compared with the past, It is desirable for the temperature of the glass MG to reach the first maximum temperature. Therefore, it is preferable to set said (DELTA) T / Time to 3-10 (degreeC / min). As for said DELTA T / Tim, it is more preferable to set it as 3-9 (degreeC / min), and it is more preferable to set it as 3-8 (degreeC / min). Here, time (minutes) is the information of the manufacturing amount MG (ton / day) which manufactures a glass plate in one day using molten glass MG, the dimension of the glass supply pipe 204 (flow path cross section and the length of a pipe), It can determine using the density of molten glass MG.

(Glass composition)

As for the glass composition of the glass plate used for this embodiment, the following are mentioned by the mass% display, for example.

SiO ₂ : 50 to 70%,

Al ₂ O ₃ : 0-25%,

B ₂ O ₃ : 1-15%,

MgO: 0-10%,

CaO: 0-20%,

SrO: 0-20%,

BaO: 0-10%,

RO: 5 to 30%, with R being the sum of Mg, Ca, Sr and Ba

Alkali-free glass.

In addition, in this embodiment, although demonstrated the alkali free glass as an example, alkali trace amount containing glass containing a trace amount of alkali metal may be sufficient as a glass substrate. In the case of containing an alkali metal, the sum of R ' ₂ O is 0.10% or more and 0.5% or less, preferably 0.20% or more and 0.5% or less (wherein R' is at least one selected from Li, Na and K, It is preferable to include what the substrate contains). Of course, the sum of the R _'2 O is low, than 0.10%.

In the case of applying the method of manufacturing a glass substrate according to the present invention, the glass composition, the addition of each component, and represented by mass%, SnO _2: 0.01 to 1% (preferably 0.01 to 0.5%), Fe ₂ O ₃ : It may contain 0 to 0.2% (preferably 0.01 to 0.08%), and in consideration of environmental load, the glass raw material may be prepared so as not to substantially contain As ₂ O ₃ , Sb ₂ O _3, and PbO. .

In this embodiment, in order to make the temperature profile of the molten glass MG in a clarification process like the temperature profile A shown in FIG. 4, the electricity supply heating of the glass supply pipe 204 and the clarification pipe | tube 202 is carried out, but heating is controlled. In some cases, the temperature profile cannot be represented by the temperature profile A. For example, by the cooling effect of the flange which supports the electrode for energizing and heating the glass supply pipe 204 and the clarification pipe | tube 202, the temperature of molten glass MG may fall partially at the position where an electrode is installed. . In this case, the temperature profile of the molten glass MG is represented by the temperature profile B. FIG. In other words, the temperature is locally lowered at the position of the end portion on the upstream side of the clarification pipe 202 on which the flange and the electrode are provided, and on the middle of the clarification pipe 202 on which the flange and the electrode are provided. Also in this case, the highest temperature (first highest temperature) of the molten glass MG when the molten glass MG flows through the glass supply pipe 204 is the highest temperature (second highest) of the molten glass MG when flowing through the clarification pipe 202. Temperature) or higher.

As mentioned above, although the manufacturing method of the glass substrate of this invention and the manufacturing apparatus of a glass plate were explained in full detail, this invention is not limited to the said embodiment, Even if it improves or changes variously in the range which does not deviate from the main point of this invention. Of course it becomes.

200: melting device
201: melting bath
202: clarification
203: stirring tank
203a: stirrer
204, 205, 206: glass feed pipe
300: forming device
310: molded body
312: supply groove
400: cutting device

Claims (7)

As a manufacturing method of a glass plate,
Melting the glass raw material to make molten glass,
It includes the process of clarifying the said molten glass by heating up the said molten glass,
Clarification of the said molten glass is a tube which consists of platinum or a platinum alloy, The transfer tube of the said molten glass heated up by heating the said molten glass from an outer wall, and the tube which consists of platinum or a platinum alloy, and is larger than the cross section of the said transfer tube. At least in a clarification tube having a cross section and having the molten glass supplied from the conveying tube so that the molten glass flows and having a gaseous phase space for defoaming of the molten glass,
In the said conveyance pipe, the said molten glass fills and flows in the whole inside end surface of the said conveyance pipe,
The 1st highest temperature of the said molten glass when the said molten glass flows through the said conveyance pipe is equal to or higher than the 2nd highest temperature of the said molten glass when flowing the said clarification pipe | tube, The manufacturing method of the glass plate characterized by the above-mentioned. . The method of claim 1,
The temperature of the said molten glass reaches the said 1st highest temperature while the said molten glass flows through the said conveyance pipe. 3. The method according to claim 1 or 2,
The molten glass includes a method for producing a glass plate containing SnO ₂ as a clarifier. 4. The method according to any one of claims 1 to 3,
The glass used for the said glass plate is a manufacturing method of the glass plate whose temperature in 10 ^2.5 poise is 1500 degreeC or more. 5. The method according to any one of claims 1 to 4,
The time (minutes) that the molten glass passes through the said transfer pipe is Time, and the temperature rises from the temperature of the said molten glass in the inlet of the said transfer pipe to the said 1st highest temperature of the said molten glass which flows through the said transfer pipe. When temperature difference is made into (DELTA) T (degreeC), (DELTA) T / Time is a manufacturing method of the glass plate which is 3-10 (degreeC / min). As a manufacturing method of a glass plate,
Melting the glass raw material to make molten glass,
After the temperature of the said molten glass is raised, the temperature of the said molten glass is clarified by temperature-falling continuously or continuously,
Clarification of the said molten glass is a tube which consists of platinum or a platinum alloy, The transfer tube of the said molten glass heated up by heating the said molten glass from an outer wall, and the tube which consists of platinum or a platinum alloy, and is larger than the cross section of the said transfer tube. At least in a clarification tube having a cross section and having the molten glass supplied from the conveying tube so that the molten glass flows and having a gaseous phase space for defoaming of the molten glass,
In the said conveyance pipe, the said molten glass fills and flows in the whole inside end surface of the said conveyance pipe,
In the said transfer pipe, after making the temperature of the said molten glass into the maximum temperature in the said clarification by the said temperature rising of the said molten glass, in the said clarification pipe | tube, the temperature of the said molten glass is said highest by the said temperature fall of the said molten glass. The manufacturing method of the glass plate characterized by maintaining at the temperature equivalent to or lower than temperature. As a manufacturing apparatus of a glass plate,
A melting tank for melting glass raw materials to make molten glass,
A clarification tube made of platinum or a platinum alloy to clarify the molten glass while flowing;
A tube made of platinum or a platinum alloy, comprising a transfer tube for connecting the dissolution tank and the clarification tube and heating the outer wall to raise the molten glass to clarify the molten glass,
The clarification pipe has a cross section larger than the cross section of the transfer pipe, and has a gas phase space for defoaming of the molten glass.
The said 1st highest temperature of the said molten glass when the said molten glass flows through the said conveyance pipe is the said transfer so that it may become equal to or higher than the 2nd highest temperature of the said molten glass when the said molten glass flows through the said clarification pipe | tube. An apparatus for producing a glass plate, wherein the tube is heated.

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