JP2012031053A - Apparatus for manufacturing glass plate, and method for manufacturing glass plate using the same - Google Patents

Abstract

A new glass plate manufacturing apparatus having a structure suitable for preventing buckling of a conduit is provided.
A transfer pipe 10 through which molten glass transferred from a melting tank to a forming apparatus passes is made of a platinum group metal, and a conduit 1 constituting a flow path 5 of the molten glass, and a refractory supporting the conduit 1. A support 7 and a refractory fiber layer 2 disposed between the conduit 1 and the refractory support 7 so as to be in contact with the outer peripheral surface of the conduit 1 and the refractory support 7 are provided. The refractory fiber layer 2 allows the expansion of the conduit 1 relative to the refractory support 7 by slippage due to the interface of the layer 2 and deformation of the layer 2 and contraction of the layer 2. As a result, the stress applied to the conduit 1 is relaxed and the buckling of the conduit 1 is prevented. The refractory support 7 may include a refractory protective layer 3 having airtightness that shields permeation of oxygen in the thickness direction. The refractory protective layer 3 suppresses oxidation of the platinum group metal constituting the conduit 1 and volatilization accompanying the oxidation.
[Selection] Figure 2

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.

  The glass plate is industrially manufactured by molding a molten glass produced by melting a glass raw material. Generally, a glass plate manufacturing apparatus includes a melting part (melting tank) that generates molten glass from a glass raw material, a forming part (forming apparatus) that forms molten glass into a glass plate, and a space between the melting part and the forming part. And a transfer part (transfer pipe) connected so that the molten glass can be transferred, and further provided with an intermediate part constituted by a clarification tank or the like for removing minute bubbles contained in the molten glass, if necessary. . In the apparatus provided with the intermediate part, the transfer part connects between the melting part and the intermediate part, the intermediate part and the molding part, and in some cases between the tanks constituting the intermediate part. Glass having a composition suitable for a substrate of a flat panel display (FPD) such as a liquid crystal display (LCD), although the temperature of the molten glass passing through the transfer portion varies depending on the composition of the glass plate to be molded, the configuration of the apparatus, and the like. In an apparatus for producing a plate by the downdraw method, the temperature is usually about 1000 to 1650 ° C.

  In order to mass-produce high-quality glass plates from high-temperature molten glass, 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. Generally, a platinum group metal (typically platinum) is used on the inner wall of a glass plate manufacturing apparatus for manufacturing a glass plate for an LCD substrate.

  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.

  The transfer part (transfer pipe) in which 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 further, a refractory that supports the conduit. A support is provided. 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. 8 shows a cross section of the transfer tube 110 including the buckled conduit 101. When the transfer pipe 110 shifts 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 inside. A buckled portion 120 that is bent toward the circumferential side is generated. The buckling portion 120 may be formed in a row in a region extending along the longitudinal direction of the conduit 101, or may be formed in a concentrated manner in a region that circulates in the circumferential direction of the conduit 101. is there. It is considered that the former buckling is caused by restricting the expansion of the conduit 101 in the radial direction and the latter buckling is restricting the expansion of the conduit in the longitudinal direction. 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.

  For this reason, Patent Document 1 discloses, as means for solving the problems associated with the expansion of the conduit, providing the conduit with a convolution that compresses as the conduit expands (Claim 1). According to Patent Literature 1, the longitudinal expansion of the conduit is absorbed by the convolution portion. However, the formation of convolutions greatly increases the processing and material costs of the conduit. Further, the convolution portion basically does not serve to prevent the buckling of the conduit that occurs due to the limited expansion in the radial direction of the conduit.

JP 2002-87826 A

  The present invention relates to a glass plate manufacturing apparatus including a transfer pipe including a conduit made of a platinum group metal that constitutes a flow path of molten glass and a refractory support that supports the conduit. It aims at providing the new glass plate manufacturing apparatus which has a structure suitable for prevention.

The present invention
A melting tank that heats a glass raw material to produce a molten glass, a molding apparatus that forms a glass plate from the molten glass, and a transfer pipe through which the molten glass that is transferred from the melting tank to the molding apparatus passes. ,
The transfer pipe is
A conduit made of a platinum group metal and constituting a flow path of the molten glass;
A refractory support that supports the conduit;
A refractory fiber layer disposed between the conduit and the refractory support so as to be in contact with the outer peripheral surface of the conduit and the refractory support;
A glass plate manufacturing apparatus is provided.

  According to the present invention, the refractory fiber layer allows relative movement between the conduit and the refractory support, thereby preventing the conduit from buckling.

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 the glass plate manufacturing apparatus of this invention. It is sectional drawing for showing an example of the structure of the glass plate manufacturing apparatus of this invention. It is a side view for demonstrating an example of the method of forming a refractory fiber layer. It is a side view for demonstrating the method of winding a refractory fiber elongate sheet around the curved part of a conduit | pipe, and forming a refractory fiber layer. It is process drawing for showing an example of the manufacturing method of the glass plate manufacturing apparatus of this invention. It is sectional drawing about the pipe longitudinal direction which shows an example of the structure of the glass plate manufacturing apparatus of this invention. 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 20 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. And a transfer pipe 10 for connecting the two. In addition to the clarification tank 30, the intermediate part between the melting tank (melting part) 20 and the shaping | molding apparatus may further contain other tanks, such as a stirring tank. In this case, the tanks constituting the intermediate portion are also connected by the transfer pipe 10.

The melting tank 20 supplies molten glass by heating and melting glass raw materials. The glass raw material thrown into the melting tank 20 is suitably prepared according to the composition of the glass plate which should be manufactured. When manufacturing the glass plate used as a substrate for LCD, the glass material constituting the glass plate to be manufactured is expressed in mass%, for example, SiO ₂ : 50 to 70%, B ₂ O _{3. : 5~18%, Al 2 O 3} : 10~25%, MgO: 0~10%, CaO: 0~20%, SrO: 0~20%, BaO: 0~10%, RO: 5~20% (However, it is preferable that 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 20 is sent to the clarification tank 30 through the transfer pipe 10. In the clarification tank 30, the molten glass is maintained at a predetermined temperature (in the case of glass having the above composition, for example, 1500 ° C. or more), and clarification, that is, removal of fine bubbles encased in the molten glass is performed.

  Further, the molten glass clarified in the clarification tank 30 is sent to the molding apparatus via the transfer pipe 10. 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 pipe 10 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 transfer tube 10 of the glass plate manufacturing apparatus 100 will be described with reference to FIGS. 2 and 3. The transfer pipe 10 includes a conduit 1, 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. The inside of the conduit 1 becomes a flow path 5 through which the molten glass passes.

  The conduit | pipe 1 is comprised from a platinum group metal, and is a pipe body typically comprised from platinum. The conduit 1 is preferably cylindrical as shown in the figure, but the shape thereof is not limited as long as the flow path 5 is secured in the inside thereof. For example, the outer shape thereof may be a polygonal column.

  The outer peripheral surface of the conduit 1 is covered with a refractory fiber layer 2. The refractory fiber layer 2 is disposed between the conduit 1 and the refractory support 7 so as to come into contact with the outer peripheral surface of the conduit 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 conduit 1, the refractory fiber layer 2, and the refractory protective layer 3. In other words, the transfer pipe 10 shown in the figure includes a conduit 1, a refractory brick 4 as a support structure, and refractory members 2 and 3 disposed between the conduit 1 and the refractory brick 4. Includes a refractory fiber layer 2 disposed so as to cover the outer peripheral surface of the conduit 1 and a refractory protective layer 3 disposed so as to cover the outer peripheral surface of the refractory fiber layer 2.

  The refractory fiber layer 2 allows the conduit 1 and the refractory support 7 to move relative to each other (actually, the movement of the conduit 1 relative to the fixed refractory support 7). It is interposed between the support 7. The movement of the conduit 1 with the longitudinal expansion is mainly due to the relative movement between the conduit 1 and the refractory fiber layer 2 ("slip" at the interface between the conduit 1 and the fiber layer 2). Permissible. The refractory fiber layer 2 usually has a higher frictional resistance at the interface with the refractory (refractory support 7) than at the interface with the metal (conduit 1). In other words, the refractory fiber layer 2 receives a greater restraining force from the refractory support 7. Moreover, 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 conduit 1. For this reason, the refractory fiber layer 2 is usually fixed to the refractory support 7 while slipping at the interface with the conduit 1, and in some cases, in addition to slipping at the interface, the layer 2 has shear stress. The deformation of the tube contributes to allow expansion of the conduit 1 in the longitudinal direction.

  Movement of the conduit 1 due to expansion in the radial direction is allowed by contraction of the refractory fiber layer 2. 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.

  As described above, the refractory fiber layer 2 has an effect of allowing expansion of the conduit 1 in the length direction and the radial direction of the conduit 1. By this effect, when the refractory fiber layer 2 is interposed between the conduit 1 and the refractory support 7, the restriction on expansion of the conduit 1 is relaxed and its buckling is suppressed.

  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 conduit 1, the outer peripheral surface of the conduit 1 can be reliably covered and protected, and the work is also easy. It is. The refractory fiber sheet may be wound around the outer peripheral surface of the conduit 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 arranged so as to cover the entire outer peripheral surface of the conduit 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 expansion of the conduit 1 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 conduit 1 is preferably 5.0 mm or less.

  The refractory protective layer 3 plays a role of reliably supporting the conduit 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 conduit 1, its arrangement is a preferred layer. In order to reduce the material cost, the conduit 1 is often formed so that the thickness of the tube wall is, for example, not less than 0.5 mm and not more than 2 mm, typically about 1 mm. In particular, when the conduit 1 having a thin tube wall is used, it is preferable to dispose the refractory protective layer 3 in order to ensure that the conduit 1 can withstand the internal pressure caused by the molten glass passing through the conduit 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, the oxidation of the platinum group metal constituting the conduit 1 can be suppressed. 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 conduit 1 heated to a high temperature, the platinum group metal becomes a metal oxide such as PtO ₂ . Since this metal oxide tends to volatilize at high temperatures, the oxidation of the platinum group metal results in thinning of the conduit 1. When the thickness of the conduit 1 is reduced, the risk of the conduit 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 for preventing the buckling of the conduit 1, but cannot sufficiently shield the permeation of oxygen in the thickness direction. Therefore, it is preferable to further dispose the conduit 1 by further disposing the refractory protective layer 3 having airtightness.

  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 conduit 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 conduit 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 transfer pipe 10 shown in the figure, when the refractory protective layer 2 is formed using an indeterminate refractory, the surface of the layer 3 on the side of the conduit 1 is refractory brick 4 side from the state at the time of formation. There is a slight retreat. This retreat may be a factor that secures a space around the conduit 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 effective in preventing volatilization of the platinum group metal constituting the conduit 1 while preventing the conduit 1 from buckling. Is suitable.

  It should be noted that, as described in Patent Document 1, shrinkage of a layer formed using an amorphous refractory material may allow “slightly” movement of a conduit to which this layer is directly “adhered”. 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 conduit using a layer formed using an irregular refractory, the conduit is locally bound to the irregular refractory, or locally 1 may face a space large enough to act with the heat insulating material. Therefore, in the form in which the layer 3 formed using the irregular refractory is directly bonded to the outer periphery of the conduit 1, even if the relative movement of the conduit 1 is allowed, the degree is only “slightly”. In this configuration, when the relative movement of the conduit 1 is sufficiently allowed, the breakage of the conduit 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 | pipe 1 moves only "slightly", the convolution part is formed in the conduit | pipe. On the other hand, in the present invention, it is not necessary to form a convolution portion in the conduit that causes an increase in processing cost. For example, a conduit having a shape whose cross-sectional shape is the same in the longitudinal direction, as represented by a cylinder, is used. Can be used.

  The refractory bricks 4 are arranged in the outermost layer of the transfer pipe 10 and support and keep the conduit 1 warm, and further protect the conduit 1 from physical forces that may be applied from the outside. It is preferable that the transfer pipe 10 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 and FIG. 5, the preferable example of the method of forming the refractory fiber layer 2 using a refractory fiber sheet is demonstrated. In order to completely cover and protect the outer peripheral surface of the conduit 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 conduit 1. is there. In this case, the refractory fiber long sheet 2a may be wound on the outer peripheral surface of the conduit 1 so that adjacent sheets partially overlap in the width direction (see FIG. 4). This method, which is performed in the manner of wrapping the wrapping bag, is reliable and simple as a method of covering the entire outer peripheral surface of the conduit 1 at the portion where the conduit 1 is bent. As shown in FIGS. 4 and 5, the refractory fiber layer 2 is preferably formed by spirally winding the refractory fiber sheet 2a around the outer peripheral surface of the conduit.

  With reference to FIG. 6, the manufacturing method of the transfer pipe 10 is illustrated. First, the lower refractory brick 4a which prepared the recessed part previously in the site | part which should arrange | position a conduit | pipe is prepared. Next, an amorphous refractory is placed on the surface of the concave portion of the lower refractory brick 4a to form the lower refractory protective layer 3a (FIG. 6A). The lower refractory protective layer 3a can be formed, for example, by applying a refractory slurry. Further, the conduit 1 in which the refractory fiber layer 2 is arranged in advance on the outer periphery thereof is installed on the lower refractory protective layer 3a (FIG. 6B). 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. 6C). Here too, a refractory slurry is suitable as the amorphous refractory. Thereafter, the upper refractory brick 4b is placed over the upper refractory protective layer 3b and integrated with the lower refractory brick 4a (FIG. 6D). In this way, the transport comprising the conduit 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. Tube 10 is obtained.

  In the step (B) of disposing the conduit 1 on the lower refractory protective layer 3a and the step (D) of disposing the upper refractory brick 4b on the upper refractory protective layer 3b, the amorphous refractory maintains fluidity. In this state, the conduit 1 or the refractory brick 4b is sufficiently pressed against the lower or upper refractory protective layers 3a and 3b so that no space is left between the refractory fiber layer 2 and the refractory brick 4 and the fire resistance. It is preferable to adhere the refractory protective layer 3 to the outer peripheral surface of the physical fiber layer 2.

  However, the method of configuring the transfer pipe 10 is not limited to the above manufacturing method. For example, a through-hole is formed in the refractory brick 4, and the conduit 1 in which the refractory fiber layer 2 is previously arranged on the outer periphery thereof is inserted into the through-hole, and the conduit 1 is placed around the conduit 1 and the refractory brick 4 in the through-hole. The refractory protective layer 3 may be formed by holding a gap between the refractory material and filling the void with an irregular refractory prepared in a slurry form.

  When the molten glass passes through the inside of the transfer pipe 10, the refractory fiber layer 2 is not only exposed to a high temperature, but also subjected to stress accompanying expansion of the conduit 1. This stress will be described with reference to FIG. 7. At the contact surface 12 with the conduit 1, the refractory fiber layer 2 is subjected to compressive stress in the radial direction of the conduit (the vertical direction in the drawing) and the longitudinal direction of the conduit (the left and right in the drawing). Subject to shear stress due to differences in thermal expansion between the refractory protective layer 3 (and refractory brick 4) and the conduit 1 in the direction). 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 such a layer is a layer composed of refractory fibers disposed in contact with the outer peripheral surface of the conduit 1 and the refractory support 7, the layer is referred to as a "refractory fiber layer" in the present 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 higher the temperature of the molten glass, the higher the risk of buckling of the conduit. 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,
A method for producing a glass plate, comprising: a melting step for heating a glass raw material to produce a molten glass; and a molding step for forming a glass plate from the molten glass, wherein both the melting step and the molding step are performed. It implements using the glass plate manufacturing apparatus by this invention, The manufacturing method of the glass plate in which the said glass raw material contains a tin containing compound as a clarifier 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 addition, when implementing the manufacturing method of this invention, it is sufficient to use the general-purpose raw material conventionally used also about glass raw materials other than a tin containing compound.

  In this manufacturing method, the glass plate manufacturing apparatus further includes a clarification tank connected to each of the melting tank and the forming apparatus by the transfer pipe, and the glass composition is heated to 1600 ° C. or higher in the clarification tank. It is preferable to do. According to this preferable example, tin oxide produced from the tin-containing compound can sufficiently function as a fining agent. Since the glass plate manufacturing apparatus according to the present invention has a structure that is difficult to buckle even if the transfer tube is heated to a high temperature, the manufacturing of heating the molten glass to the above high temperature in order to make tin oxide function as a fining agent. Especially suitable for the method. The temperature of the glass composition (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.

  The present invention is most effective when applied to a transfer pipe that connects a melting tank and a clarification tank, particularly a transfer pipe that connects the melting tank and the clarification tank and the temperature of the molten glass that passes through reaches 1500 ° C to 1650 ° C. I can expect. However, the present invention is not limited to an apparatus that heats the molten glass to a high temperature as described above, and the present invention has an effect of application as long as the apparatus is a glass plate manufacturing apparatus in which the temperature of the molten glass that passes through the transfer tube is 1000 ° C. or higher. I can expect.

As described above, in the present invention, it is preferable that the glass composition to be produced contains the following components expressed in mass%.
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%
However, R is at least one selected from Mg, Ca, Sr and Ba (the content shown by RO is the total content of MgO, CaO, SrO and BaO), and this glass composition is: As ₂ O ₃ , Sb ₂ O ₃ and PbO are not substantially contained. Incidentally, the content of Fe ₂ O ₃ is more preferably 0.01 to 0.08%.

More preferably, the glass composition further contains R ′ ₂ O of more than 0.20 mass% and not more than 2.0 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, “not containing substantially” 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 Conduit 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 Transfer pipe 20 Melting tank 30 Clarification tank 100 Glass plate manufacturing equipment

Claims (10)

A melting tank that heats a glass raw material to produce a molten glass, a molding apparatus that forms a glass plate from the molten glass, and a transfer pipe through which the molten glass that is transferred from the melting tank to the molding apparatus passes. ,
The transfer pipe is
A conduit made of a platinum group metal and constituting a flow path of the molten glass;
A refractory support that supports the conduit;
A refractory fiber layer disposed between the conduit and the refractory support so as to be in contact with the outer peripheral surface of the conduit 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 conduit.
The glass plate manufacturing apparatus of any one of Claims 1-4. The refractory fiber layer is formed by spirally winding the refractory fiber sheet around the outer periphery of the conduit.
The glass plate manufacturing apparatus according to claim 5. A method for producing a glass plate, comprising: a melting step for melting a glass raw material to produce a molten glass; and a molding step for forming the molten glass into a glass plate,
Both the melting 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 glass plate manufacturing apparatus further includes a clarification tank connected to each of the melting tank and the forming apparatus by the transfer pipe,
The manufacturing method of the glass plate of Claim 7 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 7 or 8 in 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%
However, R is at least one selected from Mg, Ca, Sr and Ba,
The glass composition is substantially free of As ₂ O ₃ , Sb ₂ O ₃ and PbO. The method for producing a glass plate according to claim 9, wherein the glass composition further contains R ′ ₂ O which is expressed by mass% and exceeds 0.20 mass% and is 2.0 mass% or less.
R ′ is at least one selected from Li, Na and K.

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