JP2013010672A - Glass sheet manufacturing apparatus and method for manufacturing glass sheet using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass sheet manufacturing apparatus suitable for preventing the deformation of a vessel made of a platinum group metal and constituting a clarifier tank.SOLUTION: The clarifier tank 30 for removing bubbles in molten glass 5 includes: the vessel 1 made of a platinum group metal and housing the molten glass 5; a refractory support 7 supporting the vessel 1; and a refractory fiber layer 2 disposed in contact with the outer circumferential face of the vessel 1 and the refractory support 7 between the vessel 1 and the refractory support 7. The refractory fiber layer 2 allows expansion of the vessel 1 to the refractory support 7 through interfacial slippage and deformation of the layer 2 and shrinkage of the layer 2. As a result, stress applied to the vessel 1 is relieved and the deformation of the vessel 1 is prevented. The refractory support 7 may have a refractory protective layer 3 having such airtightness as to block oxygen permeation in the thickness direction. The refractory protective layer 3 suppresses oxidation and vaporization of the platinum group metal constituting the vessel 1.

Description

  The present invention relates to a glass plate manufacturing apparatus and a manufacturing method for manufacturing a glass plate by forming a molten glass produced by melting a glass raw material.

  Generally, a glass plate manufacturing apparatus includes a melting tank that generates molten glass from a glass raw material, and a molding device that forms the molten glass into a glass plate. Depending on the type of glass plate to be manufactured, a glass plate manufacturing apparatus further including a clarification tank for removing minute bubbles contained in the molten glass is used. For example, a glass plate suitable for a substrate of an active matrix type liquid crystal display (hereinafter sometimes referred to as “TFT-LCD”) using a thin film transistor (TFT) is manufactured using an apparatus equipped with a clarification tank.

  In order to mass-produce glass plates with excellent quality, it is desirable that foreign substances that cause defects in the glass plates do not enter the molten glass from the glass plate manufacturing apparatus. For this reason, in the glass plate manufacturing apparatus, 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, the required quality of the glass plate, and the like. In a glass plate manufacturing apparatus for manufacturing a glass plate for a TFT-LCD substrate, platinum is usually used on the inner wall of a clarification tank, and on the inner wall of a transfer pipe for introducing molten glass into or from the clarification tank. Group metals (typically platinum) are used.

  In this specification, the “platinum group metal” means a metal composed of a platinum group element, and is used as a term including not only a metal composed of a single platinum group element but also an alloy of the platinum group element. Here, the platinum group element refers to six elements of platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), osmium (Os), and iridium (Ir). Platinum group metals are expensive, but have a high melting point and excellent corrosion resistance against molten glass.

  A transfer pipe in which a platinum group metal is used as a material constituting the inner wall is usually provided with a conduit made of platinum group metal through which molten glass passes, and a refractory support for supporting the conduit. . The refractory support is typically composed of refractory bricks. Since expensive platinum group metals are used by being thinly stretched, the refractory brick serves as a support for reinforcing the conduit having insufficient strength and also as a heat insulator for keeping the conduit warm.

  When the outer peripheral surface of the conduit made of a platinum group metal is in close contact with the refractory brick, the conduit is likely to buckle when a temperature change occurs. The buckling of the conduit occurs because the thermal expansion coefficient of the platinum group metal is larger than that of the refractory brick. FIG. 7 shows a cross section of the transfer tube 110 including the buckled conduit 101. When the transfer pipe 110 transitions from a low temperature state to a high temperature state as the molten glass passes, expansion of the conduit 101 to the outer peripheral side is limited by the inner surface of the refractory brick 104, and as a result, the conduit 101 is partially internal. A buckled portion 120 that is bent toward the circumferential side is generated. Buckling of the conduit 101 can result in unexpected damage to the device.

  Patent Document 1 discloses that a castable cement such as cellular alumina is filled between a conduit and a refractory brick (paragraph 0023, FIG. 3). The castable cement is “glued” to the conduit to allow “slight relative movement” between the conduit (the descending tube) and the refractory brick (paragraph 0023). However, this castable cement basically does not provide a drastic measure to prevent conduit buckling because it only allows “slight” relative movement of the conduit.

JP 2002-87826 A

  So far, a deformation called buckling of a member made of a platinum group metal has been manifested in a conduit formed as a long tubular body. However, the clarification tank is also provided with a member (container) made of a platinum group metal and a refractory support that supports this member as basic components, like a transfer pipe having a conduit. Up to now, there has been no report on examples of member deformation in the clarification tank or examples of countermeasures thereof, but deformation of a member made of a platinum group metal is a problem that can occur in the clarification tank.

  In particular, in recent years, in consideration of the environment, in place of arsenic oxide that has been used as a clarifier, a clarifier that needs to be heated to a higher temperature tends to be used in order to obtain a clarification action. . Further, in order to cope with the transition from amorphous TFT to polysilicon TFT, a glass plate having a higher strain point is required. In order to produce glass plates with higher strain points, it is usually necessary to apply higher melting and fining temperatures. In order to stably manufacture a glass plate over a long period of time while dealing with these circumstances, it is desirable to prevent deformation of a member (container) made of a platinum group metal even in a clarification tank.

  Therefore, the present invention provides a glass plate manufacturing apparatus including a clarification tank provided with a container made of a platinum group metal for containing molten glass and a refractory support that supports the container. An object of the present invention is to provide a new glass plate manufacturing apparatus having a suitable structure.

The present invention
A glass plate is formed from a melting tank that heats a glass raw material to produce molten glass, a clarification tank that reduces bubbles contained in the molten glass supplied from the melting tank, and a molten glass supplied from the clarification tank. A molding device,
The clarification tank is
A container made of a platinum group metal and containing the molten glass;
A refractory support for supporting the container;
Between the container and the refractory support, provided with a refractory fiber layer disposed so as to contact the outer peripheral surface of the container and the refractory support,
A glass plate manufacturing apparatus is provided.

  According to the present invention, since the refractory fiber layer allows relative movement between the container and the refractory support in the clarification tank, deformation of the container is prevented.

It is a figure which shows an example of a structure of the glass plate manufacturing apparatus of this invention. It is a partial cutaway side view for demonstrating an example of the structure of a clarification tank. It is sectional drawing for showing an example of the structure of a clarification tank. It is a side view for demonstrating an example of the method of forming a refractory fiber layer. In an example of the method of manufacturing a clarification tank, it is a figure which shows the process of forming a lower refractory material protective layer on the concave surface of a lower refractory brick. It is a figure which shows the process of arrange | positioning the container which coat | covered the outer peripheral surface with the refractory fiber layer on the lower refractory protective layer following the process shown to FIG. 5A. It is a figure which shows the process of forming an upper refractory protective layer so that the exposed part of the outer peripheral surface of a refractory fiber layer may be covered following the process shown to FIG. 5B. It is a figure which shows the process of arrange | positioning an upper refractory brick so that the outer peripheral surface of an upper refractory protective layer may be covered and the outer wall of a clarification tank may be comprised with a lower refractory brick following the process shown to FIG. 5C. It is sectional drawing for showing an example of the structure of a clarification tank. It is sectional drawing which shows the transfer pipe | tube with which buckling produced.

  Hereinafter, embodiments of the present invention will be illustrated with reference to the drawings.

  FIG. 1 shows an outline of the configuration of a glass plate manufacturing apparatus, and shows a simplified configuration of the apparatus. The glass plate manufacturing apparatus 100 includes a melting tank 10 that heats a glass raw material to produce a molten glass, a clarification tank 30 that clarifies the molten glass, a molding apparatus (not shown) that molds the molten glass, and a space between them. The transfer pipes 20 and 40 are connected to each other. The transfer pipe 20 connects the melting tank 10 and the clarification tank 30, and supplies the molten glass derived from the melting tank 10 to the clarification tank 30. The transfer pipe 40 supplies the molten glass led out from the clarification tank 30 to the molding apparatus. In addition, between the clarification tank 30 and a shaping | molding apparatus, the stirring tank for stirring and homogenizing a molten glass may be arrange | positioned.

The glass raw material thrown into the melting tank 10 is suitably prepared according to the composition of the glass plate to be manufactured. When manufacturing the glass plate used as a substrate for TFT type LCD, the glass composition is expressed by mass% of the glass composition constituting the manufactured glass plate, for example, SiO ₂ : 50 to 70%, B _2. O ₃ : 5 to 18%, Al ₂ O ₃ : 10 to 25%, MgO: 0 to 10%, CaO: 0 to 20%, SrO: 0 to 20%, BaO: 0 to 10%, RO: 5 to 5% It is preferable to prepare so as to contain 20% (wherein R is at least one selected from Mg, Ca, Sr and Ba). In the case of using a glass plate production apparatus of the present invention, the glass composition, in addition to the above components, and in _{wt%, SnO 2: 0.01~1%,} Fe 2 O 3: 0~ It is preferable to prepare the glass raw material so that it contains 1% (preferably 0.01 to 0.08%) and does not substantially contain As ₂ O ₃ , Sb ₂ O ₃ and PbO. As ₂ O ₃ , Sb ₂ O ₃ and PbO have high environmental loads, and therefore are preferably excluded from the glass composition.

Further, the glass composition is expressed in mass%, and R ′ ₂ O: more than 0.20% and 2.0% or less (where R ′ is at least one selected from Li, Na and K) It is more preferable to prepare the glass raw material so as to further contain. However, the composition of the glass plate manufactured by the glass plate manufacturing apparatus of the present invention is not limited to the above.

  The molten glass generated in the melting tank 10 is sent to the clarification tank 30 through the transfer pipe 20. In the clarification tank 30, the molten glass is kept at a predetermined temperature (in the case of glass having the above composition, for example, 1500 ° C. or higher, preferably 1550 ° C. or higher, more preferably 1600 ° C. or higher) and is clarified, that is, wrapped in molten glass. Fine bubbles are removed.

  Further, the molten glass clarified in the clarification tank 30 is sent to the molding apparatus via the transfer pipe 40. The molten glass is cooled to a temperature suitable for molding (for example, about 1200 ° C. in the case of glass having the above composition) in the transfer tube 40 when it is sent from the clarification tank 30 to the molding apparatus. In the forming apparatus, the molten glass is formed into a glass plate.

  Hereinafter, the clarification tank 30 of the glass plate manufacturing apparatus 100 will be described with reference to FIGS. 2 and 3. The clarification tank 30 includes a container 1 for containing molten glass, a refractory fiber layer 2, and a refractory support 7 and has a laminated structure in which these are sequentially arranged from the inner peripheral side to the outer peripheral side. During the operation of the manufacturing apparatus 100, the molten glass 5 from which bubbles are to be removed is supplied into the container 1. In addition, in FIG. 1, although only the container 1 was shown as the clarification tank 30, as shown in FIG.2 and FIG.3, since the refractory material support body 7 etc. exist in the outer periphery of the container 1, in reality, The outer periphery of the container 1 cannot be visually recognized from the outside.

  The container 1 is composed of a platinum group metal, and is typically a tubular body composed of platinum. The container 1 is preferably cylindrical as shown in the figure, but the shape is not limited as long as a space for accommodating the molten glass 5 is secured therein. For example, the outer shape is a rectangular parallelepiped or the like. Good.

  The clarification tank 30 includes exhaust pipes 31 and 32 that connect the internal space of the container 1 and the outside air. Through the exhaust pipes 31 and 32, the gas removed from the molten glass is discharged to the outside of the clarification tank. In addition, in order to accelerate | stimulate the removal of the bubble contained in molten glass, it is good also as reducing the internal space of the clarification tank 30 as needed. In this case, the exhaust pipes 31 and 32 are connected to a vacuum pump (not shown).

  The refractory fiber layer 2 is disposed between the container 1 and the refractory support 7 so as to be in contact with the outer peripheral surface of the container 1 and the inner wall of the refractory support 7. The refractory support 7 includes a refractory protective layer 3 in contact with the refractory fiber layer 2 and a refractory brick 4 in contact with the refractory protective layer 3. The refractory brick 4 is a structure that supports the container 1, the refractory fiber layer 2, and the refractory protective layer 3. The clarification tank 30 shown in the figure includes a container 1, a refractory brick 4 that is a support structure, and refractory members 2 and 3 disposed between the container 1 and the refractory brick 4, and the refractory member. Includes a refractory fiber layer 2 disposed so as to contact the outer peripheral surface of the container 1 and a refractory protective layer 3 disposed so as to contact the outer peripheral surface of the refractory fiber layer 2.

  The refractory fiber layer 2 allows the container 1 and the refractory support 7 to move relative to each other (actually, the container 1 moves relative to the fixed refractory support 7). It is interposed between the support 7. The movement of the container 1 due to the expansion is allowed mainly by the relative movement between the container 1 and the refractory fiber layer 2 ("slip" at the interface between the container 1 and the fiber layer 2). The refractory fiber layer 2 usually has a greater frictional resistance at the interface with the refractory (refractory support 7) than at the interface with the metal (container 1). In other words, the refractory fiber layer 2 receives a greater restraining force from the refractory support 7. Further, since the refractory fiber layer 2 is composed of fibers, unlike the refractory layer formed using, for example, castable cement, the refractory fiber layer 2 does not have a large restraining force on the container 1. For this reason, the refractory fiber layer 2 is usually fixed to the refractory support 7 while slipping at the interface with the container 1, and in some cases, the inside of the layer 2 due to shear stress in addition to slipping at the interface. This deformation contributes to allow the container 1 to expand.

  Along with such “slip”, the refractory fiber layer 2 allows the container 1 to expand by its own “compression”. The space | gap which exists between the refractory fibers which comprise the refractory fiber layer 2 is mutually connected, and it is conduct | electrically_connected to the exterior. In addition, the refractory fiber constituting the layer 2 is easily deformed according to stress. For this reason, the refractory fiber layer 2 has the characteristic of being easily compressed in the thickness direction according to the external pressure applied to the layer.

  Due to the “sliding” and “compressing” as described above, the refractory fiber layer 2 has an effect of allowing the container 1 to expand simultaneously in different directions.

  The refractory fiber layer 2 may be a woven fabric, a non-woven fabric, or other forms, and the length of the fibers constituting the layer is not particularly limited. There is no restriction | limiting in particular also in the kind of refractory which comprises the refractory fiber layer 2, Alumina, a silica, a mullite, a zirconia, asbestos etc. can be used.

  When the refractory fiber layer 2 is formed by winding a sheet made of refractory fiber (refractory fiber sheet) around the outer peripheral surface of the container 1, the outer peripheral surface of the container 1 can be reliably covered and protected, and the work is easy. It is. The refractory fiber sheet may be wound around the outer peripheral surface of the container 1 in a single layer, or may be wound so as to overlap with a double triple or more. The refractory fiber sheet is preferably disposed so as to cover the entire outer peripheral surface of the container 1.

  The thickness of the refractory fiber layer 2 is preferably 0.1 mm or more, particularly preferably 1.0 mm or more. This is because if the refractory fiber layer 2 is too thin, the effect of allowing the container 1 to expand may not be sufficiently obtained. On the other hand, if the refractory fiber layer 2 is too thick, the adhesion may decrease as the fiber deteriorates at high temperatures. Considering this, the total thickness of the refractory fiber layer 2 on the outer peripheral surface of the container 1 is preferably 5.0 mm or less.

  The refractory protective layer 3 plays a role of reliably supporting the container 1 as a part of the refractory support 7 between the refractory fiber layer 2 and the refractory brick 4. Although the refractory protective layer 3 is not essential, in order to prevent the non-uniform force from being applied to the container 1, its arrangement is a preferred layer. In order to reduce the material cost, the container 1 is often formed so that the thickness of the tube wall is, for example, 0.5 mm or more and 2 mm or less, typically about 1 mm. In particular, when the container 1 having a thin tube wall is used, it is preferable to dispose the refractory protective layer 3 in order to ensure that the container 1 can withstand the internal pressure caused by the molten glass passing through the container 1. . The refractory protective layer 3 is preferably disposed so as to cover the outer peripheral surface of the refractory fiber layer 2.

  The refractory protective layer 3 can be formed using, for example, an amorphous refractory. The amorphous refractory is not particularly limited as long as the outer peripheral surface of the refractory fiber layer 2 can be protected, but castable cement, particularly alumina cement excellent in fire resistance and corrosion resistance is suitable.

  The refractory protective layer 3 preferably has an airtight property that covers the outer peripheral surface of the refractory fiber layer 2 and shields permeation of oxygen in the thickness direction of the layer 3. By disposing the protective layer 3 having airtightness, it is possible to suppress oxidation of the platinum group metal constituting the container 1. An amorphous refractory, particularly a castable cement, is suitable as a material for imparting airtightness to the refractory protective layer 3.

When oxygen is supplied to the surface of the container 1 heated to a high temperature, the platinum group metal becomes a metal oxide such as PtO ₂ . Since this metal oxide has a tendency to volatilize at a high temperature, the oxidation of the platinum group metal results in the thinning of the container 1. When the container 1 is made thinner, the risk of the container 1 being damaged increases due to the internal pressure of the molten glass passing through the transfer pipe. The refractory fiber layer 2 is effective in preventing the deformation of the container 1, but cannot sufficiently shield the permeation of oxygen in the thickness direction. Accordingly, it is preferable to further dispose the refractory protective layer 3 having airtightness to prevent the container 1 from being thinned.

  As is well known, the amorphous refractory means a refractory that can be formed into a desired shape when used, and typically represented by clay or powder, as represented by mortar and cement. It is commercially available as a product. On the other hand, as shown by refractory bricks, fixed refractories may be combined as appropriate, or some of them may be scraped, but basically they are used in their state. It is a term that refers to refractories.

  Moreover, refractory is used as a term meaning a nonmetallic material that can withstand high temperatures, specifically, a nonmetallic material having a refractory degree of 1000 ° C. or higher, preferably 1500 ° C. or higher, as usual. As is well known, the refractory is typically composed of an oxide such as silica, alumina, zirconia, or the like, and in some cases, various components are blended with the oxide within a limit that does not impair the fire resistance.

  The thickness of the refractory protective layer 3 is preferably 2.0 mm or more, particularly preferably 10.0 mm or more. Although the refractory protective layer 3 is not too thick even if it is too thick, 50 mm or less is appropriate from the viewpoint of reducing the amount of material used.

  The refractory protective layer 3 is filled between the refractory fiber layer 2 and the refractory brick 4 so as to narrow and preferably completely remove the space between the refractory fiber layer 2 and the refractory brick 4. It is desirable that If the space is removed, the possibility that the platinum group metal constituting the container 1 is oxidized and volatilized is further reduced, and the possibility that the space functions as a heat insulating material and a part of the container 1 is overheated is also reduced.

  An amorphous refractory typified by alumina cement is usually formed by adding water. For this reason, a layer formed using an amorphous refractory generally tends to have a reduced thickness due to desorption of residual moisture when exposed to a high temperature. Therefore, also in the clarification tank 30 shown in the figure, when the refractory protective layer 3 is formed using an irregular refractory, the surface of the layer 3 on the container 1 side is the refractory brick 4 side from the state at the time of formation. There is a slight retreat. This retreat can be a factor that secures a space around the container 1 that acts as a heat insulating material.

  However, the refractory fiber layer 2 can be deformed to follow the shrinkage of the refractory protective layer 3 to some extent. For this reason, arrangement | positioning of the refractory fiber layer 2 is suitable also for prevention of formation of the heat insulation layer (space) accompanying shrinkage | contraction of an amorphous refractory. As described above, the refractory fiber layer 2 is excellent in hermeticity, but the thickness reduction accompanying the shrinkage may promote the oxidation of platinum. It also compensates for the disadvantages of layer 3. On the other hand, the lack of airtightness of the refractory fiber layer 2 is compensated by the airtightness of the irregular refractory. The complementary combination of the refractory fiber layer 2 and the refractory protective layer 3 formed using an amorphous refractory is extremely suitable for preventing volatilization of the platinum group metal constituting the container 1 while preventing deformation of the container 1. ing.

  In addition, as described in Patent Document 1, shrinkage of a layer formed using an irregular refractory material may allow “slightly” movement of a member such as a conduit to which this layer is directly “adhered”. is there. However, it is extremely difficult to accurately and uniformly control the degree of contraction of the amorphous refractory. For this reason, even if an attempt is made to form a void that is not too large around the entire circumference of the container 1 made of a platinum group metal using a layer formed using an irregular refractory, the container 1 is locally restrained by the irregular refractory. Or the container 1 may face a space that is large enough to act locally on the container 1. Therefore, even if the relative movement of the container 1 is allowed in the form in which the layer 3 formed using the irregular refractory is directly adhered to the outer periphery of the container 1, the degree is only “slightly”. In this form, when the relative movement of the container 1 is sufficiently allowed, the damage of the container 1 due to the internal pressure accompanying the passage of the molten glass must be considered as the oxidation of platinum proceeds.

  In Patent Document 1, since the conduit moves relatively “slightly”, a large number of convolutions are formed in the conduit. On the other hand, in the present invention, it is not necessary to form a large number of convolutions that increase the processing cost. The formation of the convolution part is excessively costly for the container 1 having a large cross-sectional area. According to this invention, it can be set as the clarification tank provided with the container which has the shape where cross-sectional shape is the same about a longitudinal direction so that it may be represented by a cylinder, for example.

  The refractory brick 4 is arranged in the outermost layer of the clarification tank 30, supports the container 1, keeps the temperature, and further protects the container 1 from physical force that may be applied from the outside. The clarification tank 30 preferably further includes a refractory brick 4 that supports the refractory protective layer 3. In addition, in this specification, in accordance with common usage, a support body made of refractory bricks is described in a simplified form as “refractory brick”, but in many cases, refractory bricks are composed of a plurality of refractory bricks (refractory materials). It is a support made of a plurality of bricks, which are constructed by stacking bricks in a predetermined shape, and in many cases, a fireproof filler such as mortar is applied and fixed therebetween.

  With reference to FIG. 4, the preferable example of the method of forming the refractory fiber layer 2 using a refractory fiber sheet is demonstrated. In order to cover and protect the outer peripheral surface of the container 1, it is convenient to prepare a refractory fiber long sheet 2 a and gradually shift it in the longitudinal direction while winding it around the outer periphery of the container 1. In this case, the refractory fiber long sheet 2a may be wound on the outer peripheral surface of the container 1 so that adjacent sheets partially overlap in the width direction (see FIG. 4). As shown in FIG. 4, the refractory fiber layer 2 is preferably formed by spirally winding the refractory fiber sheet 2 a around the outer peripheral surface of the container 1.

  In addition, a clarification tank and a transfer pipe join the flange of the edge part of the connection pipe protruded from the container 1 which comprises a clarification tank, and the flange part of the end part of the molten glass conduit | pipe which comprise a transfer pipe, for example. Can be connected. At this time, it is preferable to form at least one, preferably two or more expansion portions (expansion rings) in the connecting pipe so that the displacement due to thermal expansion of the container 1 is absorbed. The expansion ring usually has a shape in which a part of the outer peripheral surface of the connection pipe is projected to the outer peripheral side. Displacement due to thermal expansion of the container 1 is reversibly absorbed by contraction of the connecting pipe at the site where the expansion ring is formed.

  With reference to FIG. 5A-FIG. 5D, the manufacturing method of the clarification tank 30 is illustrated. First, the lower refractory brick 4a which prepared the recessed part previously in the site | part which should arrange | position the container 1 is prepared. Next, an amorphous refractory is placed on the surface of the recess of the lower refractory brick 4a to form the lower refractory protective layer 3a (FIG. 5A). The lower refractory protective layer 3a can be formed, for example, by applying a refractory slurry. Furthermore, the container 1 which has arrange | positioned the refractory fiber layer 2 previously in the outer periphery on the lower refractory protective layer 3a is installed (FIG. 5B). Subsequently, an amorphous refractory is disposed on the exposed surface of the refractory fiber sheet 2 to form the upper refractory protective layer 3b (FIG. 5C). Here too, a refractory slurry is suitable as the amorphous refractory. Thereafter, the upper refractory brick 4b is covered from above the upper refractory protective layer 3b and integrated with the lower refractory brick 4a (FIG. 5D). Thus, the clarification comprising the container 1, the refractory fiber layer 2, the refractory protective layer 3 composed of the lower refractory protective layer 3a and the upper refractory protective layer 3b, and the refractory brick 4 composed of the lower refractory brick 4a and the upper refractory brick 4b. A tank 30 is obtained.

  In the step of placing the container 1 on the lower refractory protective layer 3a (FIG. 5B) and the step of placing the upper refractory brick 4b on the upper refractory protective layer 3b (FIG. 5D), the amorphous refractory is fluid. The container 1 or the refractory brick 4b is sufficiently pressed against the lower or upper refractory protective layers 3a and 3b in the state where the refractory is held so that no space remains between the refractory fiber layer 2 and the refractory brick 4. At the same time, the refractory protective layer 3 is preferably adhered to the outer peripheral surface of the refractory fiber layer 2.

  However, the method of configuring the clarification tank 30 is not limited to the above manufacturing method. For example, the refractory brick 4 is assembled in a shape having a through hole, and a container 1 in which the refractory fiber layer 2 is previously arranged on the outer periphery thereof is inserted into the through hole, and the container 1 is placed around the container 1 in the through hole. The refractory protective layer 3 may be formed by filling the void with an irregular refractory prepared in a slurry state while holding the void such that a void is formed between the refractory brick 4.

  During the operation of the glass plate manufacturing apparatus, the refractory fiber layer 2 is not only exposed to high temperatures, but also subjected to stress accompanying expansion of the container 1. Hereinafter, the stress when the container 1 is cylindrical and the influence of the stress on the fiber layer 2 will be described with reference to FIG. At the contact surface 12 with the container 1, the refractory fiber layer 2 is subjected to compressive stress in the cylindrical radial direction (vertical direction in the figure) and the refractory protective layer 3 (in the horizontal direction in the figure) ( And subjected to shear stress due to the difference in thermal expansion between the refractory brick 4) and the container 1. During the operation of the glass plate manufacturing apparatus, since it continues to be exposed to compression and shear stress at high temperature, the fibers constituting the layer are separated in the refractory fiber layer 2 or the fibers themselves lose flexibility and break up. There are things to do. For this reason, even if it is the refractory fiber layer 2 formed using the refractory fiber sheet, when the refractory brick 4 is opened and visually confirmed when the repair time of the glass plate manufacturing apparatus is reached, the original sheet shape is damaged. In some cases, the fiber may become brittle and a part of the fiber may be divided into short fibers and collapsed. Even if it is such a layer, as long as it is a layer which consists of a refractory fiber arrange | positioned in contact with the outer peripheral surface of the container 1 and the refractory support body 7, the layer is a "refractory fiber layer" in this specification. Applicable.

  The present invention is particularly suitable for application to an apparatus for producing a glass plate by applying high temperature conditions. This is because the risk of deformation of the container increases as the temperature of the molten glass increases. It is known that the glass plate has a different temperature (clarification temperature) at which the clarification action is effectively exhibited depending on the clarifier used. For example, arsenic oxide has an excellent ability to remove bubbles, and a clarification temperature is sufficient in a range of about 1500 ° C. or more. However, arsenic oxide has a very high environmental impact and should be avoided. On the other hand, there are many clarifiers whose clarification ability is limited unless a high clarification temperature is applied to clarifiers that do not have a high environmental load. For example, the fining temperature of tin oxide is 1600 ° C to 1750 ° C, preferably 1650 ° C to 1700 ° C.

Thus, the present invention is particularly suitable for the production of glass plates that use tin oxide as a fining agent. From another aspect of the present invention,
Comprising a melting step of heating a glass raw material to produce a molten glass, a clarification step of reducing bubbles contained in the molten glass, and a molding step of forming a glass plate from the molten glass with reduced bubbles. A glass plate manufacturing method, wherein the melting step, the clarification step and the molding step are carried out using a glass plate manufacturing apparatus according to the present invention, and the glass raw material contains a tin-containing compound as a clarifier. A method for manufacturing a board is provided. The tin-containing compound is preferably tin oxide, but is not limited thereto, and any tin material that can supply tin oxide to the molten glass may be used. Moreover, tin oxide is good also as making it contain in molten glass by the elution from the tin oxide member (electrode) used for a melting tank.

  In carrying out the production method of the present invention, it is sufficient to use conventionally used raw materials as the respective glass raw materials.

  In this production method, the molten glass is preferably heated to 1600 ° C. or higher in the clarification tank. According to this preferable example, tin oxide produced from the tin-containing compound can sufficiently function as a fining agent. The temperature of the molten glass in the clarification tank is more preferably 1650 ° C. or higher, and the upper limit is not particularly limited, but may be 1750 ° C. or lower.

As described above, in the present invention, it is preferable that the glass composition constituting the glass plate is represented by mass% and contains the following components.
SiO ₂ : 50 to 70%
B ₂ O _3: 5~18%
Al ₂ O ₃ : 10 to 25%
MgO: 0 to 10%
CaO: 0 to 20%
SrO: 0 to 20%
BaO: 0 to 10%
RO: 5-20%
SnO ₂ : 0.01 to 1%
Fe ₂ O ₃ : 0 to 1%
Here, R is at least one selected from Mg, Ca, Sr and Ba (the content shown by RO is the sum of the content of MgO, CaO, SrO and BaO). However, this glass composition does not substantially contain As ₂ O ₃ , Sb ₂ O ₃ and PbO. Incidentally, the content of Fe ₂ O ₃ is more preferably 0.01 to 0.08%.

More preferably, the glass composition further includes R ′ ₂ O that is greater than 0.20% by mass and not greater than 2.0% by mass, expressed in mass%. However, R ′ is at least one selected from Li, Na and K. R ′ ₂ O has a function of reducing the viscosity of the molten glass and promoting clarification, but is eluted from the glass plate when added in excess. R ′ ₂ O eluted from the glass plate may undesirably affect the thin film transistor formed on the surface of the glass plate when used as an LCD substrate.

In the present specification, “substantially not containing” means that the content is less than 0.01% by mass, preferably less than 0.005% by mass. In this specification, when determining the composition of the glass plate, the oxides that can take different valences in the glass plate are converted into oxides of the chemical formula specified in this specification and the content rate is calculated. I decided to. For example, iron exists as a divalent or trivalent oxide in a glass plate, but the content of divalent oxide (FeO) is calculated in terms of trivalent oxide (Fe ₂ O ₃ ). .

  Hereinafter, the experimental result which confirmed the oxygen shielding function by the refractory protective layer 3 formed using the amorphous refractory is shown.

  First, as an experimental example, a 2.0 mm thick refractory fiber sheet (ITM Corporation “Fiber Max Cloth”; woven fabric of alumina long fibers) on a platinum plate having a length of 20 mm, a width of 20 mm, and a thickness of 0.2 mm. Arranged to form a refractory fiber layer, and further coated with alumina cement ("A-1-S-30" manufactured by Nikkato) on this sheet, followed by drying at 100 ° C to protect the refractory with a thickness of 2 mm A layer was formed to obtain Sample A.

  As Comparative Example 1, Sample B was obtained in the same manner as in the experimental example (ie, by directly applying alumina cement on a platinum plate) except that the refractory fiber sheet was not disposed.

  As Comparative Example 2, only the platinum plate was prepared and used as Sample C.

  Samples A to C were left in an electric furnace in an atmosphere at about 1600 ° C. for 80 hours, and the change in weight was measured. As a result, the rate of weight change is −4.58% for sample A (experimental example), −4.24% for sample B (comparative 1), and −6.09% for sample C (comparative 2). It was. The effect of suppressing the volatilization of platinum in the protective material (alumina cement) in sample A is slightly lower than the effect of the protective material in sample B. However, when compared with Sample C, it can be seen that even if a refractory protective layer is provided via a refractory fiber layer, this layer can sufficiently suppress oxidation and volatilization of platinum.

DESCRIPTION OF SYMBOLS 1 Container 2 Refractory fiber layer 2a Refractory fiber (long) sheet 3 Refractory protective layer 3a Lower refractory protective layer 3b Upper refractory protective layer 4 Refractory brick 4a Lower refractory brick 4b Upper refractory brick 7 Refractory support 10 Melting tank 20, 40 Transfer pipe 30 Clarification tank 100 Glass plate manufacturing equipment

Claims (9)

A glass plate is formed from a melting tank that heats a glass raw material to produce molten glass, a clarification tank that reduces bubbles contained in the molten glass supplied from the melting tank, and a molten glass supplied from the clarification tank. A molding device,
The clarification tank is
A container made of a platinum group metal and containing the molten glass;
A refractory support for supporting the container;
Between the container and the refractory support, provided with a refractory fiber layer disposed to contact the outer peripheral surface of the container and the refractory support,
Glass plate manufacturing equipment. The refractory support was provided with a refractory protective layer having an airtightness that covers the outer peripheral surface of the refractory fiber layer and shields permeation of oxygen in the thickness direction thereof.
The glass plate manufacturing apparatus according to claim 1. The refractory protective layer is formed using an amorphous refractory,
The glass plate manufacturing apparatus according to claim 2. The refractory support further comprises a refractory brick that supports the refractory protective layer;
The glass plate manufacturing apparatus according to claim 2 or 3. The refractory fiber layer is formed by winding a refractory fiber sheet around the outer peripheral surface of the container,
The glass plate manufacturing apparatus of any one of Claims 1-4. Comprising a melting step of heating a glass raw material to produce a molten glass, a clarification step of reducing bubbles contained in the molten glass, and a molding step of forming a glass plate from the molten glass with reduced bubbles. A method of manufacturing a glass plate,
The melting step, the refining step, and the forming step are performed using the glass plate manufacturing apparatus according to claim 1,
The manufacturing method of the glass plate in which the said glass raw material contains a tin containing compound as a clarifier.   The manufacturing method of the glass plate of Claim 6 which heats the said molten glass to 1600 degreeC or more in the said clarification tank. The manufacturing method of the glass plate of Claim 6 or 7 with which the glass composition which comprises the said glass plate displays with the mass%, and contains the following components.
SiO ₂ : 50 to 70%
B ₂ O _3: 5~18%
Al ₂ O ₃ : 10 to 25%
MgO: 0 to 10%
CaO: 0 to 20%
SrO: 0 to 20%
BaO: 0 to 10%
RO: 5-20%
SnO ₂ : 0.01 to 1%
Fe ₂ O ₃ : 0 to 1%
Here, R is at least one selected from Mg, Ca, Sr and Ba.
However, the glass composition is substantially free of _{As 2 O 3, Sb 2 O} 3 , and PbO. It said glass composition, and in wt%, further comprising the following R _'2 O 2.0 wt% greater than 0.20 wt%, the manufacturing method of a glass plate according to claim 8.
R ′ is at least one selected from Li, Na and K.

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