JP2016069241A - Manufacturing method of glass substrate, and manufacturing apparatus of glass substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a glass substrate and a manufacturing apparatus of a glass substrate capable of reducing temperature difference of molten glass in the cross sectional direction of a transfer pipe, the molten glass flowing in the transfer pipe made of platinum or a platinum alloy.SOLUTION: A manufacturing method of a glass substrate includes a step for transferring molten glass G produced by melting glass-making feedstock through a transfer pipe 43. The transfer pipe 43 is equipped with a conduit tube 61, a support member 63, and a heat radiation adjusting member 64. The conduit tube 61 in which the molten glass G flows is made of platinum or a platinum alloy. The support member 63 is provided on the outer peripheral surface of the conduit tube 61 and supports the conduit tube 61. The heat radiation adjusting member 64 is provided on the outer peripheral surface of the support member 63 and adjusts a heat radiation amount of the molten glass G flowing in the conduit tube 61. The support member 63 has a thermal resistance changing along the circumferential direction of the conduit tube 61. The heat radiation adjusting member 64 has a thermal resistance adjusted so as to compensate for the change of the thermal resistance of the support member 63.SELECTED DRAWING: Figure 2

Description

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

  In general, a glass substrate manufacturing apparatus heats a glass raw material to produce a molten glass, a molding apparatus that forms a glass substrate from the molten glass, and transfers the molten glass from the melting tank to the molding apparatus. A transfer pipe for carrying out the operation. The glass substrate manufacturing apparatus further includes a clarification tank for removing minute bubbles contained in the molten glass and a stirring tank for stirring and homogenizing the molten glass as necessary. The melting tank, the clarification tank, the stirring tank, and the molding apparatus are each connected by a transfer pipe. The temperature of the molten glass passing through the inside of the transfer tube varies depending on the composition of the glass substrate to be molded, the configuration of the glass substrate manufacturing apparatus, and the like. For example, the temperature of the molten glass in the step of producing a glass substrate having a composition suitable for a glass substrate for display such as a liquid crystal display (LCD) by the overflow down draw method is about 1000 ° C. to 1750 ° C.

  When manufacturing a glass substrate for a display such as an LCD, it is desirable that foreign substances or the like that cause defects in the glass substrate do not enter the molten glass. Therefore, the inner wall of the member in contact with the molten glass needs to be made of an appropriate material according to the temperature of the molten glass in contact with the member and the required quality of the glass substrate. In an apparatus for manufacturing a glass substrate for manufacturing a glass substrate for LCD, for example, platinum or a platinum alloy is used for the inner wall of a member in contact with molten glass.

  Moreover, in the manufacturing apparatus of a glass substrate, it is preferable to make uniform the temperature of the molten glass which passes the inside of a transfer pipe in the cross-sectional direction of a transfer pipe. This is because, for example, in a transfer tube for supplying molten glass to a forming apparatus, if the temperature of the molten glass differs in the cross-sectional direction of the transfer tube, the temperature of the molten glass supplied to the molded body is not uniform, This is because the problem of poor flatness occurs. Moreover, in a molded object, it is because molten glass may stagnate in the area | region where temperature is lower than another area | region, and there also exists a possibility that the problem of causing the striae of a glass substrate may also generate | occur | produce.

  Therefore, in order to make the temperature of the molten glass passing through the inside of the transfer pipe uniform in the cross-sectional direction of the transfer pipe, Patent Document 1 (Japanese Patent Laid-Open No. 2009-298671) discloses a flange made of an annular conductor. An apparatus for manufacturing a glass substrate attached to a transfer tube is disclosed. The flange has an inner ring portion made of a material having high electrical resistance, and the inner ring portion is eccentric toward the power source. In this glass substrate manufacturing apparatus, power concentration in the flange can be relaxed, and the difference in heating amount in the circumferential direction of the transfer tube can be reduced.

  However, even if the power concentration in the flange is relaxed and the amount of heating in the circumferential direction of the transfer pipe is made uniform, the temperature of the molten glass flowing in the transfer pipe is caused by the difference in the amount of heat released in the circumferential direction of the transfer pipe. There is a problem that the cross-sectional direction becomes non-uniform. In addition, with recent high-definition displays, demands on the flatness and striae of glass substrates have become increasingly severe.

  The objective of this invention is the manufacturing method of the glass substrate which can reduce the temperature difference of the cross-sectional direction of a transfer tube of the molten glass which flows through the inside of the transfer tube comprised from platinum or a platinum alloy, and manufacture of a glass substrate. Is to provide a device.

  The manufacturing method of the glass substrate which concerns on this invention is equipped with a melting process, a transfer process, and a formation process. The melting step is a step of melting glass raw material to produce molten glass. A transfer process is a process of transferring molten glass by letting the inside of a transfer pipe pass. The forming step is a step of forming the molten glass into a plate shape. The transfer pipe includes a conduit, a support member, and a heat radiation amount adjusting member. The conduit is a tube made of platinum or a platinum alloy through which molten glass flows. The support member is provided on the outer peripheral surface of the conduit and is a member for supporting the conduit. The heat dissipation amount adjusting member is a member that is provided on the outer peripheral surface of the support member and adjusts the heat dissipation amount of the molten glass flowing inside the conduit. The support member necessarily has a thermal resistance that varies along the circumferential direction of the conduit for ease of installation. The heat radiation amount adjusting member has a thermal resistance adjusted so as to cancel the change in the thermal resistance of the support member.

  In this glass substrate manufacturing method, the transfer pipe for transferring the molten glass includes a support member for supporting the conduit through which the molten glass flows, and a heat release amount of the molten glass flowing inside the conduit. And a heat dissipation amount adjusting member. For example, the conduit is a cylindrical member having a circular cross section, and the support member is a prismatic member having a quadrangular cross section. In this case, the thickness of the support member in the radial direction of the conduit is not uniform in the circumferential direction of the conduit. Since the thermal resistance of the support member in the radial direction of the conduit increases as the thickness of the support member in the radial direction of the conduit increases, the thermal resistance of the support member is not uniform in the circumferential direction of the conduit. The heat radiation amount adjusting member makes the thermal resistance of the support member uniform in the circumferential direction of the conduit. Due to the heat radiation amount adjusting member, the thermal resistance of the entire transfer pipe becomes uniform in the circumferential direction of the conduit. Therefore, this glass substrate manufacturing method can reduce the temperature difference in the cross-sectional direction of the transfer glass of the molten glass flowing inside the transfer pipe made of platinum or a platinum alloy.

  Moreover, in the manufacturing method of the glass substrate which concerns on this invention, it is preferable that a transfer pipe is further provided with an electrode and a selective heat radiation amount adjustment member. The electrode is a member that is attached to the conduit and adjusts the temperature of the molten glass flowing inside the conduit by causing the conduit to generate heat by passing an electric current through the conduit. The selective heat radiation adjustment member is a member that is selectively provided around the electrode in the longitudinal direction of the conduit.

  In this method for manufacturing a glass substrate, in the longitudinal direction of the conduit, the area around the electrode has a higher heat dissipation than the other areas. This is because the electrode is in contact with the outer peripheral surface of the conduit, and the heat radiation amount adjusting member is divided at the position of the electrode in the longitudinal direction of the conduit. The selective heat dissipation amount adjusting member is provided around the electrode in the longitudinal direction of the conduit, and adjusts the heat dissipation amount of the molten glass flowing inside the conduit. Thereby, the heat radiation amount of the entire transfer pipe becomes uniform in the longitudinal direction of the transfer pipe. Therefore, the manufacturing method of this glass substrate can reduce the temperature difference of the molten glass which flows through the inside of a transfer pipe in the longitudinal direction of a transfer pipe.

  In the method for manufacturing a glass substrate according to the present invention, the electrode is connected to a power source for flowing a current through the conduit, and the selective heat radiation adjustment member is on the side opposite to the side to which the power source is connected. It is preferable to attach at least to the outer peripheral surface of the calorie adjusting member.

  In this glass substrate manufacturing method, the selective heat radiation amount adjusting member is provided, for example, on the side opposite to the side where the power source of the electrode is connected. This is because, near the electrodes, the current flowing through the conduit is biased toward the side to which the power source is connected, so that the temperature on the side to which the power source is connected becomes higher than the temperature on the opposite side. Therefore, by providing the selective heat radiation amount adjusting member at least on the side opposite to the side to which the power supply is connected, the heat radiation amount of the entire transfer tube becomes uniform in the cross-sectional direction of the transfer tube. Therefore, this glass substrate manufacturing method can reduce the temperature difference in the cross-sectional direction of the transfer glass of the molten glass flowing inside the transfer pipe made of platinum or a platinum alloy.

  Note that the heat of the support member relative to the sum of the thermal resistances of the members (for example, the support member and the heat radiation adjustment member, or the support member, the heat radiation adjustment member, and the selective heat radiation adjustment member) provided on the outer peripheral surface of the conduit. When the ratio of the resistance is 50 to 100%, the problem that the temperature of the molten glass becomes non-uniform due to the change in the thermal resistance in the circumferential direction of the support member becomes significant. Therefore, the ratio of the thermal resistance of the support member to the total thermal resistance of the members provided on the outer peripheral surface of the conduit is suitable for the present invention when it is 50 to 100%, and when it is 70 to 99%. This is preferred by the present invention.

  Moreover, in the manufacturing method of the glass substrate which concerns on this invention, it is preferable that a supporting member is the cement formed by casting. At this time, the heat dissipation amount adjusting member becomes a mold. Further, when alumina cement is used as the support member, thermal stress generated in the conduit at the time of temperature rise can be reduced. More specifically, it is preferable to form the support member by pouring cement dissolved in water between the conduit and the support member, and sintering at a temperature rise.

  Moreover, in the manufacturing method of the glass substrate which concerns on this invention, it is preferable that a supporting member has prismatic shape. Thereby, construction of a support member can be made easier.

  The manufacturing method of the glass substrate which concerns on this invention is equipped with a melting process, a transfer process, and a formation process. The melting step is a step of melting glass raw material to produce molten glass. A transfer process is a process of transferring molten glass by letting the inside of a transfer pipe pass. The forming step is a step of forming the molten glass into a plate shape. The transfer pipe includes a conduit, a support member, and a heat radiation amount adjusting member. The conduit is a tube made of platinum or a platinum alloy through which molten glass flows. The support member is provided on the outer peripheral surface of the conduit and is a member for supporting the conduit. The heat dissipation amount adjusting member is a member that is provided on the outer peripheral surface of the support member and adjusts the heat dissipation amount of the molten glass flowing inside the conduit. The support member necessarily has a thermal resistance that varies along the circumferential direction of the conduit for ease of installation. The heat resistance of the heat radiation amount adjusting member and the selective heat radiation amount adjusting member is adjusted so that the change in the thermal resistance of the support member is canceled by at least one of the heat radiation amount adjusting member and the selective heat radiation amount adjusting member.

  Moreover, in this glass substrate manufacturing method, the support member is preferably cement formed by casting. At this time, the heat dissipation amount adjusting member becomes a mold. Further, when alumina cement is used as the support member, thermal stress generated in the conduit at the time of temperature rise can be reduced. More specifically, it is preferable to form the support member by pouring cement dissolved in water between the conduit and the support member, and sintering at a temperature rise.

  Moreover, in this glass substrate manufacturing method, the support member preferably has a prismatic shape. Thereby, construction of a support member can be made easier.

  The manufacturing apparatus of the glass substrate which concerns on this invention is provided with a melting tank, a transfer pipe, and a shaping | molding apparatus. A melting tank melts a glass raw material and produces | generates molten glass. The transfer pipe transfers the molten glass generated in the melting tank. The forming apparatus forms the molten glass into a plate shape. The transfer pipe includes a conduit, a support member, and a heat radiation amount adjusting member. The conduit is a tube made of platinum or a platinum alloy through which molten glass flows. The support member is provided on the outer peripheral surface of the conduit and is a member for supporting the conduit. The heat dissipation amount adjusting member is a member that is provided on the outer peripheral surface of the support member and adjusts the heat dissipation amount of the molten glass flowing inside the conduit. The support member has a thermal resistance that varies along the circumferential direction of the conduit. The heat radiation amount adjusting member has a thermal resistance adjusted so as to cancel the change in the thermal resistance of the support member.

  The method for manufacturing a glass substrate and the apparatus for manufacturing a glass substrate according to the present invention can reduce the temperature difference in the cross-sectional direction of the transfer tube of the molten glass flowing inside the transfer tube made of platinum or a platinum alloy. it can.

It is a whole block diagram of the glass substrate manufacturing apparatus which concerns on 1st Embodiment. It is an external view of the transfer pipe concerning a 1st embodiment. It is sectional drawing of the transfer pipe which concerns on 1st Embodiment. It is an external view of the transfer pipe concerning a 2nd embodiment. It is an external view of the conduit | pipe where the electrode is attached based on 2nd Embodiment. It is sectional drawing of the transfer pipe which concerns on 2nd Embodiment.

<First Embodiment>
(1) Overall Configuration of Glass Manufacturing Apparatus A glass substrate manufacturing method and a glass substrate manufacturing apparatus according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of a glass manufacturing apparatus 200 of the present embodiment. The glass manufacturing apparatus 200 includes a melting tank 40, a clarification tank 41, a stirring device 100, and a molding device 42. The melting tank 40 and the clarification tank 41 are connected by a transfer pipe 43a. The clarification tank 41 and the stirring device 100 are connected by a transfer pipe 43b. The stirring device 100 and the molding device 42 are connected by a transfer pipe 43c. The molten glass G produced | generated by the melting tank 40 flows into the clarification tank 41 through the transfer pipe 43a. The molten glass G clarified in the clarification tank 41 passes through the transfer pipe 43b and flows into the stirring device 100. The molten glass G stirred by the stirring device 100 passes through the transfer pipe 43 c and flows into the molding device 42. In the forming apparatus 42, the glass ribbon 44 is formed from the molten glass G by the overflow downdraw method.

Although not shown, the melting tank 40 includes heating means such as a burner. In the melting tank 40, the glass raw material is melted by the heating means, and the molten glass G is generated. The glass raw material is prepared so that a glass having a desired composition can be substantially obtained. As an example of the composition of the glass, non-alkali glass and fine alkali glass are SiO ₂ : 57 mass% to 70 mass%, Al ₂ O ₃ : 15 mass% to 25 mass%, B ₂ O ₃ : 0 mass% to 13 mass. wt%, MgO: 0% to 15 wt%, CaO: 0% to 20 wt%, SrO: 0% to 20 wt%, BaO: 0 wt% to 10 wt%, Na ₂ O: 0 wt% To 1% by mass, K ₂ O: 0% by mass to 1% by mass, As ₂ O ₃ : 0% by mass to 1% by mass, Sb ₂ O ₃ : 0% by mass to 1% by mass, SnO ₂ : 0% by mass to 1% by mass, Fe ₂ O ₃ : 0% by mass to 1% by mass, ZrO ₂ : 0% by mass to 1% by mass. Here, “substantially” means that the presence of other trace components is allowed in the range of less than 0.1% by mass. Moreover, regarding the glass having the above composition, each content of Fe ₂ O ₃ , As ₂ O ₃ , Sb ₂ O ₃ and SnO ₂ is a component of Fe, As, Sb or Sn having a plurality of valences, The values are respectively converted as Fe ₂ O ₃ , As ₂ O ₃ , Sb ₂ O ₃ or SnO ₂ .

  The glass raw material prepared as described above is put into the melting tank 40. In the melting tank 40, the glass raw material is melted at a temperature corresponding to its composition. Thereby, in the melting tank 40, the high temperature molten glass G of 1500 degreeC-1620 degreeC is obtained, for example.

  The molten glass G obtained in the melting tank 40 passes through the transfer pipe 43a from the melting tank 40 and flows into the clarification tank 41. The clarification tank 41 is a tubular member similar to the transfer pipes 43a, 43b, and 43c. Although not shown in the figure, the clarification tank 41 is provided with a heating means like the melting tank 40. In the clarification tank 41, the molten glass G is clarified by further raising the temperature of the molten glass G. In the clarification tank 41, the temperature of the molten glass G is preferably raised to 1600 ° C to 1800 ° C, more preferably from 1630 ° C to 1750 ° C, and even more preferably from 1650 ° C to 1750 ° C.

  The molten glass G clarified in the clarification tank 41 passes through the transfer pipe 43b from the clarification tank 41 and flows into the stirring device 100. Since the molten glass G is cooled when it passes through the transfer pipe 43 b, the molten glass G having a temperature lower than that of the molten glass G in the clarification tank 41 is stirred in the stirring device 100. Regarding the glass having the above composition, in the stirring device 100, the temperature of the molten glass G is set within a range of 1400 ° C to 1550 ° C, and the viscosity of the molten glass G is within a range of 2500 dPa · s to 450 dPa · s. It is preferable that the molten glass G is stirred after adjustment. The molten glass G is homogenized by being stirred in the stirring device 100.

  The molten glass G stirred and homogenized by the stirrer 100 flows from the stirrer 100 through the transfer pipe 43 c and flows into the molding device 42. When the molten glass G passes through the transfer tube 43c, it is cooled to a temperature suitable for molding in the molding device 42, for example, 1200 ° C. In the forming apparatus 42, the glass ribbon 44 is formed from the molten glass G by the overflow downdraw method. Specifically, the molten glass G overflowing from the upper part of the forming device 42 flows downward along the side wall of the forming device 42, so that the glass ribbon 44 is continuously formed from the lower end of the forming device 42. The glass ribbon 44 is gradually cooled as it goes downward, and is finally cut into a glass substrate of a desired size.

(2) Structure of transfer pipe The detailed structure of the transfer pipes 43a, 43b, and 43c for transferring the molten glass G from the melting tank 40 toward the molding apparatus 42 will be described. The configuration of the transfer pipe 43 described below is applied to at least one of the transfer pipe 43a, the transfer pipe 43b, and the transfer pipe 43c.

  The transfer pipe 43 mainly includes a conduit 61, a support member 63, and a heat dissipation amount adjustment member 64. FIG. 2 is an external view of the transfer pipe 43. FIG. 3 is a cross-sectional view of the transfer pipe 43. Hereinafter, the “longitudinal direction” means the longitudinal direction of the transfer pipe 43, that is, the direction in which the molten glass G is transferred in the transfer pipe 43, and the “cross-sectional direction” is orthogonal to the longitudinal direction of the transfer pipe 43. It means the direction in the plane. FIG. 3 is a cross-sectional view of the transfer pipe 43 in the cross-sectional direction.

  The conduit 61 is a cylindrical member formed of a platinum group metal. “Platinum group metal” means a metal composed of a single platinum group element and an alloy of a metal composed of a platinum group element. The platinum group elements are six elements of platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), osmium (Os) and iridium (Ir). The platinum group metal is expensive but has a high melting point and excellent corrosion resistance against the molten glass G. In this embodiment, the conduit | pipe 61 is shape | molded with platinum or a platinum alloy, for example, has thickness of 0.5 mm-1.5 mm. The inner diameter of the conduit 61 of the transfer pipes 43a, 43b, 43c is, for example, 100 mm to 250 mm. The molten glass G flows through the internal space of the conduit 61 in the longitudinal direction. In the following, “radial direction” means the radial direction of a circle that is the cross-sectional shape of the conduit 61 in the cross-sectional direction, and “circumferential direction” means the circumferential direction of the circle that is the cross-sectional shape of the conduit 61 in the cross-sectional direction. .

  The support member 63 is provided to support the conduit 61. The support member 63 is provided in contact with the outer peripheral surface of the conduit 61. The support member 63 has a substantially prismatic shape, and the cross-sectional shape of the support member 63 in the cross-sectional direction is a substantially square shape. The support member 63 is molded from cement formed by casting or sintering.

  Since the conduit 61 has a cylindrical shape and the support member 63 has a substantially prismatic shape, the radial thickness of the support member 63 is not uniform along the circumferential direction, as shown in FIG. . For example, in FIG. 3, the radial thickness t1 of the support member 63 at the point P1 on the outer peripheral surface of the support member 63 is larger than the radial thickness t2 of the support member 63 at the point P2 on the outer peripheral surface of the support member 63. . The point P1 corresponds to a substantially rectangular vertex that is a cross section of the support member 63. The point P2 corresponds to the midpoint of each side of the substantially rectangular shape that is the cross section of the support member 63. And, as the radial thickness of the support member 63 is larger, the thermal resistance of the support member 63 is larger in the radial direction, so that the thermal resistance of the support member 63 is not uniform in the circumferential direction. That is, the support member 63 has a thermal resistance that varies along the circumferential direction.

  The heat radiation amount adjusting member 64 is provided to adjust the heat radiation amount of the molten glass G flowing inside the conduit 61. The heat radiation amount adjusting member 64 is provided so as to be in contact with at least a part of the outer peripheral surface of the support member 63. The heat radiation amount adjusting member 64 is formed of fire brick, for example. The dimension of the heat dissipation amount adjusting member 64 is determined by the material of the heat dissipation amount adjusting member 64, the temperature of the molten glass G transferred through the transfer pipe 43, and the like.

  The heat radiation amount adjusting member 64 functions as a mold for casting the support member 63 when the support member 63 is constructed. When the transfer pipe 43 is used in the process of lowering the temperature of the molten glass G, the heat dissipation amount adjustment member 64 has a high thermal conductivity so that the heat resistance of the heat dissipation amount adjustment member 64 is as small as possible in order to increase the cooling efficiency. It is desirable to use a member having a small thickness. Specifically, the material for the heat radiation adjustment member 64 is preferably an alumina electrocast refractory. At this time, the ratio of the thermal resistance of the support member 63 to the total thermal resistance of the support member 63 and the heat radiation amount adjusting member 64 provided on the outer peripheral surface of the conduit 61 is 50% to 100%, preferably 70%. ~ 99%. In this case, most of the total thermal resistance of the support member 63 and the heat radiation amount adjusting member 64 provided on the outer peripheral surface of the conduit 61 depends on the support member 63 having a smaller thermal conductivity. Heat resistance is uneven in

  The heat radiation adjustment member 64 has a thermal resistance adjusted so as to cancel out a change in the circumferential direction of the thermal resistance of the support member 63. Specifically, the heat radiation amount adjusting member 64 is provided in the circumferential direction so that the thermal resistance in the radial direction of the support member 63 is larger than that in the other region in the region where the radial thermal resistance is smaller than that in the other region. For example, in FIG. 3, the thermal resistance in the radial direction of the support member 63 at the point P2 is smaller than the thermal resistance in the radial direction of the support member 63 at the point P1. Therefore, in this embodiment, the heat radiation amount adjusting member 64 is provided in the vicinity of the point P2 in the circumferential direction, as shown in FIG. By providing the heat radiation amount adjusting member 64, the thermal resistance in the radial direction of the entire transfer pipe 43 at the location where the heat radiation amount adjusting member 64 is provided increases. Therefore, the difference between the radial thermal resistance of the entire transfer pipe 43 at the point P 1 and the radial thermal resistance of the entire transfer pipe 43 at the point P 2 is reduced by providing the heat radiation amount adjusting member 64. Thus, the heat radiation amount adjusting member 64 is a member for making the thermal resistance of the support member 63 uniform in the circumferential direction.

(3) Features (3-1)
In the glass manufacturing apparatus 200 according to the present embodiment, the heat radiation amount adjusting member 64 makes the thermal resistance of the support member 63 uniform in the circumferential direction. Therefore, the heat radiation amount adjusting member 64 can reduce the temperature difference in the cross-sectional direction of the molten glass G flowing in the conduit 61 by making the thermal resistance in the circumferential direction of the entire transfer pipe 43 uniform.

  Therefore, the glass manufacturing apparatus 200 according to the present embodiment can reduce the temperature difference in the cross-sectional direction of the transfer tube 43 of the molten glass G flowing inside the transfer tube 43 made of platinum or a platinum alloy. And since the temperature of the molten glass G supplied to the shaping | molding apparatus 42 becomes uniform because the temperature difference of the cross-sectional direction of the molten glass G reduces, the flatness of a glass substrate improves and the striae of a glass substrate is improved. Occurrence is suppressed.

(3-2)
The glass manufacturing apparatus 200 according to this embodiment is transferred from the melting tank 40 toward the molding apparatus 42 by transfer pipes 43a, 43b, and 43c, and is generated from a glass raw material suitable for manufacturing a glass substrate for display. This is particularly effective when the glass G is transferred.

  A glass substrate for display is required to have high quality in terms of flatness of the glass substrate. However, when the temperature difference in the cross-sectional direction of the molten glass G flowing inside the transfer pipe 43c that supplies the molten glass G to the molding apparatus 42 is high, the molten glass G is moved to a region where the temperature is lower than other regions in the molding apparatus 42. May stagnate and the molten glass G may not uniformly overflow from the forming apparatus 42. In that case, since the plate | board thickness deviation of the glass substrate shape | molded from the shaping | molding apparatus 42 becomes large, the flatness of a glass substrate worsens. Since the glass manufacturing apparatus 200 which concerns on this embodiment can reduce the temperature difference of the cross-sectional direction of the molten glass G supplied to the shaping | molding apparatus 42 from the transfer pipe 43c, the high flatness suitable for the glass substrate for a display. The glass substrate which has can be manufactured.

(3-3)
A semiconductor element such as a TFT is formed on the surface of a glass substrate for display. In recent years, low-temperature p-Si (polysilicon) TFTs and oxide semiconductors are formed on the surface of a glass substrate in place of conventional α-Si TFTs in order to realize higher definition display devices. Technology is required.

  However, the process of forming the low temperature p-Si • TFT and the oxide semiconductor on the surface of the glass substrate requires a higher temperature heat treatment than the step of forming the α-Si • TFT on the surface of the glass substrate. is there. Therefore, a low-temperature p-Si • TFT and a glass substrate on which an oxide semiconductor is formed are required to have a low thermal shrinkage. In order to reduce the thermal shrinkage rate, it is preferable to increase the strain point of the glass. However, glass having a high strain point tends to have a high liquidus temperature and a low liquidus viscosity, which is the viscosity at the liquidus temperature. In this case, since the difference between the viscosity of the molten glass G flowing inside the transfer tube and the liquid phase viscosity is reduced, the risk of devitrification of the molded glass substrate is increased. In particular, when the temperature of the molten glass G is not uniform in the cross-sectional direction, a region in which the temperature of the molten glass G partially decreases occurs, and the risk of devitrification increases.

  Since the glass manufacturing apparatus 200 according to the present embodiment can reduce the temperature difference in the cross-sectional direction of the molten glass G flowing inside the transfer pipe 43 by the heat radiation amount adjusting member 64, the low-temperature p-Si · TFT is adopted. The present invention is particularly suitable for manufacturing a display and a glass substrate for a display using an oxide semiconductor. Specifically, it is particularly suitable for the production of glass substrates for liquid crystal displays or organic EL displays that employ low-temperature p-Si · TFTs, and liquid crystal displays or organic EL displays that employ oxide semiconductors.

The glass substrate on which the low-temperature p-Si • TFT and the oxide semiconductor are formed has, for example, a strain point of 655 ° C. or higher, or a liquid phase viscosity of 45000 poise or higher. The composition of this glass substrate is SiO ₂ : 52 mass% to 78 mass%, Al ₂ O ₃ : 3 mass% to 25 mass%, B ₂ O ₃ : 0 mass% to 15 mass%, RO: 3 mass. It is preferable that it is% -20 mass%. Here, R is at least one component selected from Mg, Ca, Sr and Ba contained in the glass substrate. This glass substrate is preferably alkali-free glass or glass containing a trace amount of alkali having a mass ratio represented by (SiO ₂ + Al ₂ O ₃ ) / B ₂ O ₃ of 7 to 20.

Since the glass substrate on which the low-temperature p-Si • TFT and the oxide semiconductor are formed has a high strain point, the mass ratio represented by (SiO ₂ + Al ₂ O ₃ ) / RO is 5 or more. Yes, preferably 6 or more, more preferably 7.5 or more. In addition, if the β-OH value is too small, the glass substrate has a high viscosity in the high temperature region and the meltability is lowered. If the β-OH value is too large, the strain point is lowered. Therefore, this glass substrate preferably has a β-OH value of 0.05 / mm to 0.3 / mm.

The glass substrate has a high strain point and prevents a decrease in liquid phase viscosity, and the mass ratio represented by CaO / RO is 0.3 or more, preferably 0.5 or more. More preferably, it is 0.65 or more. Further, the glass substrate, in consideration of the environmental burden, it is preferred not to substantially contain _{As 2 O 3, Sb 2 O} 3 , and PbO.

(4) Modification (4-1) Modification 1A
In the glass manufacturing apparatus 200 according to this embodiment, the transfer pipe 43 includes a heat radiation amount adjusting member 64 provided on the outer peripheral surface of the support member 63 that supports the conduit 61. In this embodiment, the heat radiation amount adjusting member 64 is provided in the circumferential direction so that the thermal resistance in the radial direction of the support member 63 is larger than that in the other region in the region where the radial thermal resistance is smaller than that in the other region. Yes.

  However, the heat radiation amount adjusting member 64 may have another configuration as long as it has a thermal resistance adjusted so as to cancel the change in the circumferential direction of the thermal resistance of the support member 63. For example, the heat dissipation amount adjustment member 64 may be a member that covers the entire outer peripheral surface of the support member 63. In that case, the heat radiation amount adjusting member 64 is composed of a plurality of types of members having different values of thermal resistance, and different types of heat radiation amount adjusting members 64 are attached to the outer peripheral surface of the support member 63 depending on the position in the circumferential direction. May be.

  In this case, for example, in FIG. 3, the heat resistance of the heat dissipation amount adjusting member 64 provided in the vicinity of the point P2 in the circumferential direction is larger than the heat resistance of the heat dissipation amount adjusting member 64 provided in the vicinity of the point P1 in the circumferential direction. . Thereby, similarly to this embodiment, the heat radiation amount adjusting member 64 makes the thermal resistance in the circumferential direction of the entire transfer pipe 43 uniform, and reduces the temperature difference in the cross-sectional direction of the molten glass G flowing in the conduit 61. Can do.

(4-2) Modification 1B
In the modified example 1A, when the heat dissipation amount adjusting member 64 is a member that covers the entire outer peripheral surface of the support member 63, the heat dissipation amount adjusting member 64 is composed of a plurality of types of members having different thicknesses, depending on the position in the circumferential direction. Different types of heat radiation adjustment members 64 may be attached to the outer peripheral surface of the support member 63.

In this case, for example, in FIG. 3, the thickness of the heat dissipation amount adjusting member 64 provided in the vicinity of the point P2 in the circumferential direction is larger than the thickness of the heat dissipation amount adjusting member 64 provided in the vicinity of the point P1 in the circumferential direction. Thereby, similarly to this embodiment, the heat radiation amount adjusting member 64 makes the thermal resistance in the circumferential direction of the entire transfer pipe 43 uniform, and reduces the temperature difference in the cross-sectional direction of the molten glass G flowing in the conduit 61. Can do.
Second Embodiment
The manufacturing method of the glass substrate as 2nd Embodiment of this invention is demonstrated referring drawings. The difference between the first embodiment and the present embodiment is only the configuration of the transfer pipe. Therefore, the description regarding the configuration common to the first embodiment is omitted.

(1) Configuration of Transfer Pipe The transfer pipe 143 of this embodiment mainly includes a conduit 161, an electrode 162, a support member 163, a heat dissipation amount adjustment member 164, and a selective heat dissipation amount adjustment member 165. FIG. 4 is an external view of the transfer pipe 143. FIG. 5 is an external view of the conduit 161 to which the electrode 162 is attached. FIG. 6 is a cross-sectional view of the transfer pipe 143. FIG. 6 is a cross-sectional view at a position where the selective heat radiation amount adjusting member 165 is provided in the longitudinal direction. The conduit 161 is the same as the conduit 61 of the first embodiment. In addition, the transfer pipe 143 of this embodiment can be used as the clarification tank 41. In this case, the inner diameter of the conduit 161 is, for example, 300 mm to 500 mm.

  The electrode 162 is attached to the outer peripheral surface of the conduit 161. The electrode 162 is a flange made of an annular conductor. As shown in FIGS. 4 and 5, two electrodes 162 are attached to the conduit 161. However, the number and position of the electrodes 162 attached to the conduit 161 may be appropriately determined according to the material, inner diameter and length of the conduit 161, the installation location of the transfer pipe 143, and the like.

  The electrode 162 has a power supply terminal 162a connected to a power source (not shown). Power is supplied from the power source to the electrode 162 through the power supply terminal 162 a, and a current flows through the electrode 162. The current flowing through the electrode 162 is transmitted to the conduit 161. When the current flows through the conduit 161, the conduit 161 is heated, and the temperature of the molten glass G flowing inside the conduit 161 is adjusted. Therefore, the temperature of the molten glass G flowing inside the conduit 161 can be controlled by controlling the current flowing through the electrode 162. In the present embodiment, the feeding terminals 162a of the two electrodes 162 attached to the conduit 161 are arranged on the upper side of the conduit 161 as shown in FIGS.

  The support member 163 is the same as the support member 63 of the first embodiment except that the support member 163 is divided at a position where the electrode 162 is provided in the longitudinal direction.

  The heat radiation amount adjusting member 164 is the same as the heat radiation amount adjusting member 64 of the first embodiment except that the heat radiation amount adjusting member 164 is divided at a position where the electrode 162 is provided in the longitudinal direction.

  The selective heat radiation adjustment member 165 is selectively provided around the electrode 162 in the longitudinal direction. The selective heat radiation amount adjusting member 165 is provided so as to be in contact with a part of the outer peripheral surface of the support member 163 and the heat radiation amount adjusting member 164. The selective heat radiation adjustment member 165 is formed of, for example, a refractory brick. The size of the selective heat radiation adjustment member 165 is determined by the material of the selective heat radiation adjustment member 165, the temperature of the molten glass G transferred through the transfer pipe 143, and the like.

(2) Features (2-1)
In the glass manufacturing apparatus 200 according to the present embodiment, the transfer tube 143 includes a conduit 161 made of platinum or a platinum alloy, and a flange-shaped electrode 162 that is used to pass an electric current through the conduit 161. The molten glass G flows inside the conduit 161. By passing an electric current through the electrode 162 through the electrode 162, the conduit 161 is heated, and the temperature of the molten glass G flowing inside the conduit 161 is adjusted.

  Further, the electrode 162 is in contact with the outer peripheral surface of the conduit 161, and the support member 163 and the heat radiation amount adjusting member 164 are separated at a position where the electrode 162 is provided in the longitudinal direction. Therefore, the heat radiation amount of the molten glass G by the support member 163 and the heat radiation amount adjusting member 164 is larger in the region around the electrode 162 in the longitudinal direction than in other regions.

  In this embodiment, by providing the selective heat radiation amount adjusting member 165 in the region around the electrode 162 in the longitudinal direction, the heat radiation amount of the molten glass G in the region is reduced. Thereby, the heat radiation amount of the entire transfer pipe 143 is uniform in the longitudinal direction of the transfer pipe 143. Therefore, this glass substrate manufacturing method can reduce the temperature difference in the longitudinal direction of the transfer tube 143 of the molten glass G flowing inside the transfer tube 143.

(2-2)
The glass manufacturing apparatus 200 according to the present embodiment uses a transfer tube 143 as a clarification tank 41 made of platinum or a platinum alloy, and in the clarification tank 41, a glass substrate for a display such as a liquid crystal display, a plasma display, and an organic EL display. This is particularly effective when refining molten glass G produced from a glass raw material suitable for the production of

  In the clarification tank 41, the molten glass G is clarified by adjusting the viscosity of the molten glass G to a viscosity at which minute bubbles contained in the molten glass G can easily float on the liquid surface. However, alkali-free glass and alkali-containing glass suitable for display glass substrates have high viscosity at high temperatures, and the temperature of the molten glass needs to be higher than the temperature of ordinary alkali glass molten glass. Therefore, the problem that platinum or a platinum alloy volatilizes from the clarification tank 41 becomes remarkable. Therefore, it is not preferable to heat the clarification tank 41 excessively.

  In this embodiment, by providing the heat radiation amount adjusting member 164 and the selective heat radiation amount adjusting member 165, the heat radiation amount from the clarification tank 41 is adjusted, and the cross-sectional direction and the longitudinal direction of the molten glass G flowing inside the clarification tank 41 are adjusted. The temperature difference in the direction can be reduced. In particular, by providing the selective heat radiation amount adjusting member 165, the heat radiation amount of the molten glass G in the region around the electrode 162 in the longitudinal direction is effectively adjusted. Therefore, since the glass manufacturing apparatus 200 which concerns on this embodiment can adjust the heating amount of the clarification tank 41, it is especially effective for the manufacturing process of the glass substrate for a display.

(2-3)
The glass manufacturing apparatus 200 according to the present embodiment is particularly effective when the transfer pipe 143 is used as the clarification tank 41 made of platinum or platinum alloy, and SnO ₂ is used as the clarifier in the clarification tank 41. is there.

In recent years, SnO ₂ is used as a refining agent instead of As ₂ O ₃ from the viewpoint of environmental burden. When SnO ₂ is used, the molten glass G needs to be heated to a higher temperature in the clarification tank 41 than when As ₂ O ₃ is used, so that the problem of volatilization of platinum or a platinum alloy becomes significant. Therefore, it is not preferable to heat the clarification tank 41 excessively.

  In this embodiment, by providing the heat radiation amount adjusting member 164 and the selective heat radiation amount adjusting member 165, the heat radiation amount from the clarification tank 41 is adjusted, and the cross-sectional direction and the longitudinal direction of the molten glass G flowing inside the clarification tank 41 are adjusted. The temperature difference in the direction can be reduced. In particular, by providing the selective heat radiation amount adjusting member 165, the heat radiation amount of the molten glass G in the region around the electrode 162 in the longitudinal direction is effectively adjusted. Therefore, since the glass manufacturing apparatus 200 which concerns on this embodiment can adjust the heating amount of the clarification tank 41, it is especially effective for the manufacturing process of the glass substrate for a display.

(2-4)
The glass manufacturing apparatus 200 according to the present embodiment uses the transfer tube 143 as the clarification tank 41 made of platinum or platinum alloy, and heats the clarification tank 41 to raise the temperature of the molten glass G to clarify the molten glass G. It is particularly effective when doing so.

  In the present embodiment, the temperature difference in the cross-sectional direction of the molten glass G flowing inside the conduit 161 may increase due to factors such as non-uniform current flowing through the conduit 161 depending on the position and orientation of the electrode 162. . In this case, in order to surely raise the temperature of the molten glass G that hardly flows through the space farthest from the power supply terminal 162a inside the conduit 161 of the clarification tank 41, a current flowing through the conduit 161 of the clarification tank 41 is supplied. It is possible to increase it. However, if the current passed through the conduit 161 of the clarification tank 41 is increased, volatilization of platinum or a platinum alloy constituting the conduit 161 is promoted, and the life of the clarification tank 41 may be shortened. Therefore, it is not preferable to heat the clarification tank 41 excessively.

  In this embodiment, by providing the heat radiation amount adjusting member 164 and the selective heat radiation amount adjusting member 165, the heat radiation amount from the clarification tank 41 is adjusted, and the cross-sectional direction and the longitudinal direction of the molten glass G flowing inside the clarification tank 41 are adjusted. The temperature difference in the direction can be reduced. In particular, by providing the selective heat radiation amount adjusting member 165, the heat radiation amount of the molten glass G in the region around the electrode 162 in the longitudinal direction is effectively adjusted. Therefore, since the glass manufacturing apparatus 200 which concerns on this embodiment can adjust the heating amount of the clarification tank 41, it is especially effective for the manufacturing process of the glass substrate for a display.

(3) Modification (3-1) Modification 2A
In the glass manufacturing apparatus 200 according to the present embodiment, the conduit 161 is heated by passing an electric current through the electrode 161 via the electrode 162, and the temperature of the molten glass G flowing inside the conduit 161 is adjusted. However, the current density of the current flowing through the conduit 161 varies depending on the position of the conduit 161 in the cross-sectional direction. Specifically, the portion near the power supply terminal 162a of the electrode 162 has a higher density of current flowing through the conduit 161 than the portion farther from the power supply terminal 162a than the portion, and power tends to concentrate. Therefore, in the inside of the conduit 161, the molten glass G that flows in the space close to the power supply terminal 162a is more easily heated than the molten glass G that flows in other spaces. On the other hand, the molten glass G flowing through the space farthest from the power supply terminal 162a inside the conduit 161 is less likely to be heated than the molten glass G flowing through the other space.

  Therefore, the area around the electrode 162 in the longitudinal direction is more easily radiated than other areas, but by increasing the value of the current flowing through the conduit 161 via the electrode 162, the melt flowing in the space close to the power supply terminal 162a The temperature difference in the longitudinal direction of the glass G can be reduced to some extent. In this case, the selective heat radiation amount adjusting member 165 may be provided at least on the side opposite to the side where the power source of the electrode 162 is connected, that is, on the side farthest from the power supply terminal 162a. This is because, on the side where the power source of the electrode 162 is connected, the molten glass G flowing through the inside of the conduit 161 due to electric power concentration is not easily radiated, while on the side opposite to the side where the power source of the electrode 162 is connected, the conduit This is because the molten glass G flowing through the inside of 161 is easily radiated. Therefore, depending on the value of the current flowing through the conduit 161 via the electrode 162, the heat radiation amount of the entire transfer pipe 143 can be reduced by providing the selective heat radiation amount adjusting member 165 only on the side opposite to the side to which the power source is connected. It can be made uniform in the cross-sectional direction of the transfer pipe 143.

(3-2) Modification 2B
In the glass manufacturing apparatus 200 according to the present embodiment, the conduit 161 is heated by passing an electric current through the electrode 161 via the electrode 162, and the temperature of the molten glass G flowing inside the conduit 161 is adjusted. The current density of the current flowing through the conduit 161 varies depending on the position and direction of the electrode 162, in particular, the position of the feeding terminal 162a and the position in the cross-sectional direction of the conduit 161. For this reason, the temperature of the molten glass G flowing inside the conduit 161 tends to be non-uniform in the cross-sectional direction of the conduit 161.

  In order to reduce the temperature difference in the cross-sectional direction of the molten glass G, in the modified example 2A, the selective heat radiation amount adjusting member 165 is the most opposite from the side where the power source of the electrode 162 is connected, that is, from the power supply terminal 162a. At least on the remote side. However, the heat radiation amount of the molten glass G flowing inside the conduit 161 is adjusted according to the position and orientation of the electrode 162 using a plurality of types of selective heat radiation adjustment members 165 having different thermal resistance values. Thus, the temperature difference in the cross-sectional direction of the conduit 161 may be reduced. Further, by using a plurality of selective heat radiation amount adjusting members 165 having different thicknesses, the heat radiation amount of the molten glass G flowing inside the conduit 161 is adjusted according to the position and orientation of the electrode 162, so that the conduit You may reduce the temperature difference of the cross-sectional direction of the molten glass G which flows through the inside of 161. FIG. In this case, the material of the selective heat radiation adjustment member 165 may be one type.

  In this modification, for example, the thermal resistance of the selective heat radiation adjustment member 165 provided on the side opposite to the side where the power source of the electrode 162 is connected is selectively supplied on the side where the power source of the electrode 162 is connected. It is larger than the thermal resistance of the heat radiation adjustment member 165. Thereby, similarly to this embodiment, the heat dissipation amount of the molten glass G flowing in the space close to the power supply terminal 162a becomes larger than the heat dissipation amount of the molten glass G flowing in the space farthest from the power supply terminal 162a. Therefore, the temperature difference in the cross-sectional direction of the molten glass G flowing inside the conduit 161 can be reduced.

  Similarly, in this modification, for example, the thickness of the selective heat radiation adjustment member 165 provided on the side opposite to the side where the power source of the electrode 162 is connected is provided on the side where the power source of the electrode 162 is connected. It is larger than the thickness of the selective heat radiation adjustment member 165. Thereby, similarly to this embodiment, the heat dissipation amount of the molten glass G flowing in the space close to the power supply terminal 162a becomes larger than the heat dissipation amount of the molten glass G flowing in the space farthest from the power supply terminal 162a. Therefore, the temperature difference in the cross-sectional direction of the molten glass G flowing inside the conduit 161 can be reduced.

DESCRIPTION OF SYMBOLS 40 Melting tank 42 Molding apparatus 43 Transfer pipe 61 Conduit 63 Support member 64 Heat radiation amount adjustment member 162 Electrode 165 Selective heat radiation amount adjustment member 200 Glass manufacturing apparatus (glass substrate manufacturing apparatus)
G Molten glass

JP 2009-298671 A

Claims (7)

A glass substrate comprising a melting step of melting glass raw material to produce molten glass, a transfer step of transferring the molten glass by passing through the inside of a transfer tube, and a forming step of forming the molten glass into a plate shape A manufacturing method of
The transfer pipe is
The molten glass flows inside, a conduit made of platinum or a platinum alloy;
A support member provided on an outer peripheral surface of the conduit for supporting the conduit;
A heat dissipation amount adjusting member for adjusting the heat dissipation amount of the molten glass provided on the outer peripheral surface of the support member and flowing inside the conduit;
With
The support member inevitably has a thermal resistance that varies along the circumferential direction of the conduit for ease of installation;
The heat dissipation amount adjustment member has a thermal resistance adjusted to cancel the change in thermal resistance of the support member.
A method for producing a glass substrate. A glass substrate comprising a melting step of melting glass raw material to produce molten glass, a transfer step of transferring the molten glass by passing through the inside of a transfer tube, and a forming step of forming the molten glass into a plate shape A manufacturing method of
The transfer pipe is
The molten glass flows inside, a conduit made of platinum or a platinum alloy;
A support member provided on an outer peripheral surface of the conduit for supporting the conduit;
A heat dissipation amount adjusting member for adjusting the heat dissipation amount of the molten glass provided on the outer peripheral surface of the support member and flowing inside the conduit;
Selectively provided on the outer peripheral surface of the heat dissipation amount adjusting member, and a selective heat dissipation amount adjusting member for selectively adjusting the heat dissipation amount of the molten glass flowing through the conduit;
With
The support member inevitably has a thermal resistance that varies along the circumferential direction of the conduit for ease of installation;
The heat resistance of the heat radiation adjustment member and the selective heat radiation adjustment member is adjusted so that the change in the thermal resistance of the support member is canceled by at least one of the heat radiation adjustment member and the selective heat radiation adjustment member. The
A method for producing a glass substrate. The transfer pipe is
An electrode attached to the conduit for adjusting the temperature of the molten glass flowing through the conduit by passing an electric current through the conduit;
A selective heat dissipation amount adjusting member selectively provided around the electrode in the longitudinal direction of the conduit;
Further comprising
The manufacturing method of the glass substrate of Claim 1. The electrode is connected to a power source for passing a current through the conduit;
The selective heat dissipation amount adjusting member is opposite to the side to which the power source is connected, and is provided at least on the outer peripheral surface of the heat dissipation amount adjusting member.
The manufacturing method of the glass substrate of Claim 3. The support member is a cement formed by casting.
The manufacturing method of the glass substrate of any one of Claim 1 to 4. The support member has a prismatic shape.
The manufacturing method of the glass substrate of any one of Claim 1 to 5. A melting tank for melting glass raw material to produce molten glass;
A transfer pipe for transferring the molten glass generated in the melting tank;
A molding device for molding the molten glass into a plate shape;
With
The transfer pipe is
The molten glass flows inside, a conduit made of platinum or a platinum alloy;
A support member provided on an outer peripheral surface of the conduit for supporting the conduit;
A heat dissipation amount adjusting member for adjusting the heat dissipation amount of the molten glass provided on the outer peripheral surface of the support member and flowing inside the conduit;
With
The support member inevitably has a thermal resistance that varies along the circumferential direction of the conduit for ease of installation;
The heat dissipation amount adjustment member has a thermal resistance adjusted to cancel the change in thermal resistance of the support member.
Glass substrate manufacturing equipment.

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