TWI557081B - Manufacture of glass plates - Google Patents

Description

Glass plate manufacturing method

The present invention relates to a method of manufacturing a glass sheet for producing a glass sheet.

Previously, in the production of glass sheets, glass sheets were formed using an overflow down-draw method. In the overflow down-draw method, the glass raw material is melted in a melting tank to prepare molten glass, and the molten glass is subjected to a clarification treatment and a homogenization treatment, and then the molten glass is supplied to the elongated molded body through a transfer pipe.

In the elongated molded body, a groove portion extending in the longitudinal direction is provided on the upper portion of the molded body, and the molten glass is supplied to one end of the groove portion. In the groove portion, the supply side of the molten glass advances toward the opposite side in the longitudinal direction, and the shallower the groove depth, the molten glass overflows from the groove portion of the molded body, and flows downward along the side walls on both sides of the molded body. The molten glass which flows down along the side wall of the both sides of the molded body is joined to the lower end of the molded body to form a flat glass.

Further, the cross-sectional shape of the flow path for supplying the molten glass to the transfer tube of the molded body is generally a circular shape, and the cross-sectional shape of the flow path of the groove portion of the molded body is a rectangular or polygonal shape. The reason why the cross-sectional shape of the flow path of the transfer pipe is a circular shape is that it is preferable that even if the molten glass is filled with a high temperature in the transfer pipe, the bent portion is not formed and the strength can be maintained. On the other hand, the cross-sectional shape of the flow path of the molded body groove portion is a rectangular or polygonal shape for the ease of processing the groove portion.

For example, in the following Patent Document 1 and FIG. 3, a molded body having a circular cross-sectional shape of a flow path and a groove having a rectangular cross-sectional shape is disclosed. In this case, when the molten glass is supplied from the circular-shaped conveying pipe to the groove part of the molded object, the flow path cross section of the molten glass has a step difference and is rapidly expanded.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2008-501609

As described above, in general, the cross-sectional shape of the flow path in which the molten glass is supplied to the transfer tube of the molded body is a circular shape, and the cross-sectional shape of the flow path of the groove portion of the molded body is a rectangular or polygonal shape, and thus the transfer tube is formed into a molded body. When the molten glass is supplied to the groove portion, the flow path cross section of the molten glass has a step difference and is rapidly expanded. Therefore, the flow path of the molten glass is rapidly expanded, and the flow of the molten glass in the groove portion of the molded body is likely to partially stay. The residence of the flow of molten glass is liable to cause devitrification of the molten glass. Further, the residence of the flow of the molten glass tends to cause a foreign material to be generated, which tends to cause the generation of the ribs. More specifically, when the flow of the molten glass stays, the time of contact with the molded body becomes longer than that of the molten glass in other portions, and thus the components of the molded body are melted from the surface of the molded body, and the glass of the molten glass is melted. The composition is easily changed in part. Further, the viscosity of the molten glass is likely to partially change due to the influence of the temperature of the molded body. That is, a foreign material is likely to be generated in the molten glass, and as a result, a rib is easily generated in the glass plate of the final product, and the thickness of the glass plate tends to be uneven.

Further, in a glass plate for a flat panel display, a semiconductor element such as a TFT (Thin Film Transistor) is formed on a glass substrate. In recent years, in order to achieve further high definition of display display, it is required to form a p-Si (low temperature polysilicon) ‧ TFT or an oxide semiconductor on a glass plate instead of the α-Si‧ TFT which has been used in the past. In the formation step of the p-Si‧TFT or the oxide semiconductor, there is a heat treatment step in which the temperature is higher than the α-Si‧ TFT formation step. Therefore, for the formation of p-Si (low temperature polysilicon) TFT or oxide Semiconductor glass sheets require a small heat shrinkage rate. In order to reduce the heat shrinkage rate, it is preferred to increase the strain point of the glass, but the glass having a higher strain point tends to have a higher liquidus temperature, and the liquidus viscosity (viscosity at the liquidus temperature) tends to be lower. . Therefore, there is also a case where the difference between the viscosity (forming viscosity) of the molten glass required for the formation of the flat glass and the liquidus viscosity is small, or the forming viscosity is larger than the liquidus viscosity, and as a result, the glass is easily devitrified. Therefore, in the case of producing flat glass using p-Si (low temperature polysilicon) ‧ TFT formation or glass having a particularly low liquid viscosity such as oxide semiconductor formation, it is necessary to prevent the flow of a part of the molten glass from being easily formed. The body component stays in the groove portion of the molded body after the surface of the molded body is melted and the liquidus viscosity is increased (the formation of devitrification is formed).

Therefore, in order to solve the problems of the prior art, an object of the present invention is to provide a method for producing a glass sheet which is characterized in that the flow of molten glass passing through the groove portion of the molded body is hard to stay when the molten glass using the molded body is formed, and the molten glass is used. It does not produce devitrified and heterogeneous billets, and can produce high-quality glass sheets with no corrugated and uniform thickness.

One aspect of the present invention is a method of producing a glass sheet for producing a glass sheet. The production method includes a step of melting a glass raw material to produce molten glass, a supply step of supplying the molten glass to a molded body through a transfer pipe, and a molding step of molding the molten glass by using the molded body. plate glass.

In the supply step, when the molten glass is supplied from the transfer pipe to the groove portion of the molded body, the molten glass does not stay on the bottom surface of the groove portion and melts so as to have a velocity component toward the molded body. The glass flows.

Therefore, the flow of the molten glass from the transport pipe to the groove portion of the molded body can be made smooth, and the residence time of the molten glass in the groove portion can be unified within a fixed range to cause the molten glass to overflow from the groove portion. Thereby, it is possible to manufacture a devitrification which is less likely to cause glass or A high quality glass plate with a heterogeneous billet, no corrugated and uniform thickness.

At this time, the above supply step can be realized by the following preferred embodiment.

In other words, it is preferable that the transfer pipe is connected to the open end of the groove portion, and the cross-sectional area of the flow path of the molten glass flowing through the transfer pipe is close to the open end of the transfer pipe and the groove of the molded body. The connection position of the open end of the portion is gradually widened. Preferably, when the molten glass is supplied from the transfer pipe to the groove portion of the molded body in the supply step, the width of the cross section of the flow path of the molten glass flowing through the transfer pipe is close to the transfer pipe. The opening end is gradually widened at a position where it is connected to the opening end of the groove portion of the formed body. The area or width of the flow path cross section gradually becomes wider as it approaches the connection position, and the molten glass does not stay on the bottom surface of the groove portion and flows to the above-mentioned shape so as to have a velocity component toward the molded body. body.

In this case, it is preferable that the groove width of the groove portion is reached at the connection position, and at the connection position, the edge of the open end of the transfer tube has at least a bottom surface of the open end of the groove portion of the molded body. The shape of the edge shape is the same, and the wall surface of the conveying pipe is connected to the bottom surface of the groove portion without a step.

Furthermore, it is preferable that the edge of the opening end of the conveying pipe has a shape that matches a part of the shape of the edge of the side surface of the opening end of the groove portion.

The edge of the opening end of the conveying pipe has a shape that matches the shape of at least the bottom surface of the opening end of the groove portion of the molded body, and further has a shape that matches a part of the shape of the side surface of the opening end of the groove portion. Therefore, the flow of the molten glass from the conveying pipe to the groove portion of the formed body can be made smoother.

Preferably, the conveying pipe has an end portion in which the width of the flow path cross section continuously extends to the connecting position.

Thereby, the flow of the molten glass is less likely to stay.

Preferably, the flow path cross section of the molten glass in the groove portion of the molded body gradually decreases as the groove portion of the molded body approaches the connection position.

Therefore, even when the flow path cross section of the transfer pipe is extremely smaller than the flow path cross section of the groove portion of the molded body, the flow of the molten glass from the transfer pipe to the groove portion can be made smooth.

Preferably, the groove portion has a portion at a lower portion of the groove including the bottom surface, that is, the groove width is narrowed as it advances in the depth direction of the groove portion, and the groove width is narrowed as it approaches the connection position. The starting position of the above depth direction becomes shallow.

Thereby, the flow of the molten glass in the lower portion of the groove can be made smoother.

Even if the strain point of the molten glass is 655 ° C or more, it can be applied to the method for producing the above glass plate.

Such a glass is a glass having a high strain point and has a tendency to increase the liquidus temperature (devitrification temperature). In the case where the glass having a strain point of 655 ° C or more is used, the appropriate viscosity (for example, 40,000 poise or more) of the molten glass in the forming step is similar to the liquid phase viscosity of the glass, and thus it is easy to devitrify. In particular, if the molten glass stays at the time of molding, the components of the molded body are melted from the surface of the molded body, and are more likely to devitrify. In the above production method, since the flow of the molten glass is less likely to stay in the groove portion of the molded body, devitrification of the glass can be suppressed.

Even if the glass has a strain point of 675 ° C or higher, the glass sheet can be applied to the method for producing the glass sheet described above, and devitrification is less likely to occur. Further, even if the glass has a strain point of 680 ° C or higher, the glass sheet can be applied to the method for producing the glass sheet described above, and devitrification is less likely to occur. Further, even if the glass has a strain point of 690 ° C or higher, the glass sheet can be applied to the method for producing the glass sheet described above, and devitrification is less likely to occur. The upper limit of the strain point is, for example, 750 ° C, preferably 730 ° C.

The liquid viscosity of the molten glass can be set to 60,000 poise or less, and can be set to 50,000 poise or less. Further, the liquidus viscosity may be set to 45,000 poise or less. Such a glass is a glass which is easily devitrified due to its close proximity to the viscosity of the molten glass required in the forming step. In particular, if the molten glass stays in the molded body, it is a glass which is more likely to devitrify. but In the method for producing a glass sheet, the flow of the molten glass is less likely to stay in the groove portion of the molded body, and therefore the liquid phase viscosity is 60,000 poise or less, 50,000 poise or less, and further 45,000 poise or less. The glass is devitrified and can be used to make glass sheets. The lower limit of the liquidus viscosity is, for example, 40,000 poise.

The glass plate is, for example, a glass plate for a flat panel display, and is, for example, a glass plate for forming a p-Si (low temperature polysilicon) TFT or a glass plate for forming an oxide semiconductor.

The p-Si (low temperature polysilicon) glass plate for forming a TFT or the glass plate for forming an oxide semiconductor has a high strain point. When the strain point is high, the liquidus temperature tends to be high, and the liquidus viscosity (viscosity at the liquidus temperature) tends to be low. Therefore, there is also a case where the difference between the viscosity (forming viscosity) of the molten glass required for the formation of the flat glass and the liquidus viscosity is reduced, or the forming viscosity is greater than the liquidus viscosity, and as a result, the glass is easily devitrified. In particular, if the molten glass stays in the molded body, it is more likely to devitrify. Therefore, the method for producing a glass sheet of the above-described aspect in which the molten glass can smoothly flow even in the groove portion of the molded body is applied to a glass plate for a flat panel display, in particular, a glass for forming a p-Si (low-temperature polysilicon) TFT. A glass plate for forming a plate or an oxide semiconductor is also less likely to cause devitrification.

Another aspect of the invention is a method of making a glass sheet for making a glass sheet. The production method includes a step of melting a glass raw material to produce molten glass, a supply step of supplying the molten glass to a molded body through a transfer pipe, and a molding step of molding the molten glass by using the molded body. In the above-described supplying step, when the molten glass is supplied from the conveying pipe to the groove portion of the molded body, the width of the cross section of the molten glass flowing in the conveying pipe is close to the opening of the conveying pipe The end portion is gradually widened at a position connecting the opening end of the groove portion of the molded body, and reaches a groove width of the groove portion at the connection position, and at the connection position, the edge of the open end of the conveying pipe has the molded body Opening of the above groove portion The shape of at least the bottom surface of the end is uniform, and the wall surface of the conveying pipe is connected to the bottom surface of the groove portion without a step.

Therefore, the flow of the molten glass from the transport pipe to the groove portion of the molded body can be made smooth, and the residence time of the molten glass in the groove portion can be unified within a fixed range to cause the molten glass to overflow from the groove portion. Therefore, it is possible to manufacture a high-quality glass plate which is less likely to cause devitrification of the glass or a foreign material, a corrugated material, and a uniform thickness.

According to the method for producing a glass sheet according to the above aspect, when the molten glass using the molded body is molded, the flow of the molten glass passing through the groove portion of the molded body is less likely to stay, and the molten glass does not cause devitrification and a foreign material, and can be produced without A high-quality glass plate with a uniform thickness and uniform thickness.

100‧‧‧melting device

101‧‧‧melting tank

101d‧‧‧ hopper

102‧‧‧Clarification tank

103‧‧‧Stirring tank

103a‧‧‧Agitator

104, 105, 106‧‧‧ glass supply tube

106a‧‧‧glass supply tube body

106b‧‧‧ Tube Expansion Department

200‧‧‧Forming device

210‧‧‧Formed body

210a‧‧‧Slots

210b‧‧‧ sidewall

210c‧‧‧ bottom front

210d‧‧‧ bottom

210e‧‧‧ slot slope

300‧‧‧cutting device cutting step

MG‧‧‧ molten glass

SG‧‧ ‧ flat glass

ST1~ST7‧‧‧Steps

W, W ₁ , W ₂ ‧ ‧ width

Z ₁ ‧‧‧Connected area

Fig. 1 is a view showing an example of a procedure of a method for producing a glass sheet of the embodiment.

Fig. 2 is a view schematically showing an example of an apparatus for performing a melting step to a cutting step in the embodiment.

Fig. 3 (a) is an exploded perspective view showing a connecting portion between the molded body and the glass supply pipe in the embodiment, and (b) is a view showing a connection between the connecting portion and the groove portion when the pipe expanding portion of the embodiment is connected to the groove portion. A map of the relative position.

Fig. 4 is a view for explaining the flow of the molten glass when the vicinity of the connection position of the glass supply tube and the molded body in the embodiment is viewed from above.

Fig. 5 (a) and (b) are views showing a state in which the groove portion of the former molded body and the glass supply tube are connected.

Fig. 6(a) is a view showing a modification 1 of the connection between the groove portion of the molded body and the tube expansion portion, and Fig. 6(b) is a view showing a modification 2 of the connection between the groove portion of the molded body and the tube expansion portion.

7(a) and 7(b) are views showing the form of the modification 3.

Hereinafter, a method of producing the glass sheet of the present embodiment will be described. Fig. 1 is a view showing an example of a procedure of a method for producing a glass sheet of the embodiment.

(Overall summary of the manufacturing method of glass plate)

The manufacturing method of a glass plate mainly has a melting step (ST1), a clarification step (ST2), a homogenization step (ST3), a supply step (ST4), a molding step (ST5), a slow cooling step (ST6), and a cutting step ( ST7). Further, there are a grinding step, a grinding step, a washing step, an inspection step, a packing step, and the like, and a plurality of glass sheets laminated in the packing step are conveyed to a supplier of the receiving side.

The melting step (ST1) is carried out in a melting tank. In the melting tank, molten glass is produced by putting the glass raw material into the liquid surface of the molten glass accumulated in the melting tank and heating it. Further, the molten glass flows from the outlet opening provided at one bottom of the inner side wall of the melting tank to the downstream step.

In the heating of the molten glass of the melting tank, in addition to the method of heating the molten glass itself to heat itself and heating it, it is also possible to additionally provide a flame generated by the burner to melt the glass raw material. Further, a clarifying agent is added to the glass raw material. As the clarifying agent, SnO ₂ , As ₂ O ₃ , Sb ₂ O ₃ and the like are known, and are not particularly limited. However, SnO ₂ (tin oxide) can be used as a fining agent from the viewpoint of reducing the environmental burden.

The clarification step (ST2) is carried out at least in the clarification tank. In the clarification step, by raising the temperature of the molten glass in the clarification tank, the bubbles containing O ₂ , CO ₂ or SO ₂ contained in the molten glass absorb the O ₂ generated by the reduction reaction of the clarifying agent, and the bubbles float up to the melting. The liquid level of the glass is released. Further, in the clarification step, the reducing substance obtained by the reduction reaction of the clarifying agent is oxidized by lowering the temperature of the molten glass. Thereby, the gas component such as O ₂ remaining in the bubbles of the molten glass is again absorbed into the molten glass, and the bubbles disappear. The oxidation reaction and the reduction reaction by the clarifying agent are carried out by controlling the temperature of the molten glass. Further, in the clarification step, a vacuum degassing method may be employed in which a space for forming a reduced pressure environment is formed in the clarification tank, and bubbles existing in the molten glass are grown in a reduced pressure environment to be defoamed. This case is effective in that no clarifying agent is used. Further, in the clarification step, a clarification method using tin oxide as a clarifying agent is used.

In the homogenization step (ST3), the molten glass in the stirring tank supplied through the pipe extending from the clarification tank is stirred by a stirrer to homogenize the glass component. Thereby, it is possible to reduce the compositional unevenness of the glass which is a cause of the ribs or the like.

In the supply step (ST4), the molten glass is supplied to the forming apparatus through a pipe extending from the stirring tank.

The forming step (ST5) and the slow cooling step (ST6) are performed in the molding apparatus.

In the molding step (ST5), the molten glass is formed into a flat glass to prepare a fluid for the flat glass. The forming system uses an overflow down-draw method.

In the slow cooling step (ST6), the flat glass which flows after molding has a desired thickness, and does not cause internal deformation, and further cools without causing warpage.

In the cutting step (ST7), the plate glass supplied from the forming device is cut into a specific length in the cutting device to obtain a plate-shaped glass plate. The cut glass sheet is further cut into a specific size to produce a glass sheet of a desired size. Thereafter, the glass plate end face is ground and polished, the glass plate is cleaned, and the presence or absence of abnormal defects such as bubbles or ribs is checked, and then the glass plate of the qualified product is packaged as a final product.

Fig. 2 is a view schematically showing an example of an apparatus for performing the melting step (ST1) to the cutting step (ST7) in the present embodiment. As shown in FIG. 2, the apparatus mainly has a melting apparatus 100, a forming apparatus 200, and a cutting apparatus 300. The melting apparatus 100 has a melting tank 101, a clarification tank 102, a stirring tank 103, and glass supply pipes 104, 105, and 106.

In the melting apparatus 101 shown in Fig. 2, the input of the glass raw material is performed using the hopper 101d. In the clarification tank 102, the temperature of the molten glass MG is adjusted, and the clarification of the molten glass MG is performed by the oxidation-reduction reaction of a clarifier. Further, in the stirring tank 103, the molten glass MG is stirred and homogenized by the agitator 103a. In the forming apparatus 200, the sheet glass SG is formed from the molten glass MG by the overflow down-draw method using the formed body 210.

(connection of glass supply tube and formed body)

Fig. 3 (a) is an exploded perspective view showing a portion where the molded body 210 and the glass supply pipe 106 are connected.

The molded body 210 is formed in an elongated structure in which one of the groove portions 210a is formed in the upper direction (the X direction in the drawing). The groove portion 210a becomes shallower in the groove depth as it advances in the X direction. Therefore, the molten glass MG supplied to the groove portion 210a overflows from the groove portion 210a, and flows downward along the side wall 210b provided on both sides of the molded body 210. The molten glass MG which flows down the side wall 210b of both sides is merged by the lower end 210c provided in the vertical direction below the molded object 210, and is bonded together and becomes the sheet glass SG.

In the groove portion 210a of the molded body 210, it is preferable to smoothly supply the molten glass MG (the flow of the molten glass MG is not easily stopped) from the viewpoint that devitrification or ribs do not occur. Especially for glass which has a high liquidus temperature and a liquidus viscosity close to the viscosity of the molten glass at the forming step (forming viscosity) or a liquid phase viscosity which is less than the viscosity of the forming, it is necessary to avoid the glass supply tube. The flow of the molten glass MG supplied to the groove portion 210a is stopped.

The flow path of the groove portion 210a of the molded body 210 has a rectangular cross section. On the other hand, the glass supply pipe 106 connected to the groove portion 210a of the molded body 210 is a transfer pipe including a glass supply pipe main body 106a having a constant flow path cross section, and a pipe expansion provided at the end of the glass supply pipe main body 106a. Part 106b. The flow path of the glass supply pipe main body 106a has a circular cross section. Moreover, the diameter of the circle which is the cross-sectional shape of the flow path of the glass supply pipe main body 106a is smaller than the groove width of the groove part 210a.

When the molten glass MG is supplied from the glass supply tube main body 106a to the groove portion 210a of the molded body 210 through the tube expansion portion 106b, the area of the flow path cross section of the molten glass MG flowing through the glass supply tube 106 is close to the glass supply tube. The open end of 106 is gradually enlarged at the position where it is connected to the open end of the groove portion 210a of the formed body 210. Further, the cross-sectional width of the flow path section of the molten glass MG flowing through the glass supply pipe 106 is close to the open end of the glass supply pipe 106. The connection position of the open end of the groove portion 210a of the body 210 is gradually enlarged. Further, the flow path cross section is wider than the connection position to the groove width of the groove portion 210a. Further, at the connection position, the edge of the open end of the glass supply tube 106 has a shape that matches the shape of at least the bottom surface of the open end of the groove portion 210a (the linear shape in the case of Fig. 3(a)), and the glass supply tube The wall surface of the 106 (tube expansion portion 106b) is connected to the bottom surface of the groove portion 210a without a step. Here, the lateral width of the flow path cross section of the molten glass MG means the width in the groove width direction of the groove portion 210a.

Specifically, the cross-sectional shape of the tube expansion portion 106b is changed from the circular flow path cross-sectional shape of the glass supply tube main body 106a to a shape in which one of the cross-sectional shapes coincides with the linear shape of the edge shape of the bottom surface of the groove portion 210a. Here, the bottom surface of the groove portion 210a is not limited to the planar portion of the groove bottom when the cross-sectional shape of the groove portion 210a is a rectangular shape, but also includes a portion extending in the depth direction with a certain groove width and lower. The groove width is gradually or continuously narrowed to the face of the portion where the groove terminates. In the examples shown in Figs. 6(a) and 6(b) below, the V-shape or the arc-shaped portion formed by the inclined faces 210b and 210c is also suitable for the edge shape of the bottom face.

Further, the cross-sectional shape of the open end of the tube-expanded portion 106b has a shape that matches one of the edge shapes (linear shapes) of the side surface (side wall surface) of the opening end of the groove portion 210a.

Further, the change in the width of the cross section of the flow path of the molten glass MG in the glass supply tube 106 may be continuously or stepwise, but from the viewpoint of not stopping the flow of the molten glass MG as much as possible, continuity is preferred. The width varies.

FIG 3 (b) are diagrams showing the relative position between the opening end 210a of the connection portion 106b of the tube expansion and the open end of the groove portion 210a of the connecting region Z ₁ and the groove portion. As described above, when the tube expansion portion 106b is connected to the groove 210a, it has a width equal to the groove width of the groove portion 210a and is connected to the groove portion 210a. As shown in Fig. 3 (b), the tube expansion portion 106b is provided so that the edge of the open end of the tube expansion portion 106b coincides with the edge of the groove portion including the bottom surface of the groove portion 210a. As a result, the molten glass MG that has flowed into the groove portion 210a from the tube expansion portion 106b smoothly flows into the groove 210a from the tube expansion portion 106b, so that the flow of the molten glass MG is less likely to stay. In the case of the tubeless expansion portion 106b, when the glass supply tube body enters the groove portion, the flow path section is rapidly enlarged, and thus the flow of the molten glass MG is stopped. In this case, the molten glass MG particularly tends to stay on the bottom surface, which tends to cause devitrification and generation of a foreign material. Therefore, the tube expansion portion 106b is provided such that the edge of the opening of the glass supply tube 106 coincides with the shape of the edge of the lower portion of the groove including the bottom surface of the groove portion 210a.

Further, as shown in Fig. 3(b), in the groove portion 210a of the molded body 210, the molten glass MG is supplied from the lower portion of the groove including the bottom surface of the groove portion 210a, and at the connection position, the groove portion 210a is located above the lower portion of the groove. The upper part of the groove is closed by a plate-like member as shown in Fig. 3 . Therefore, the molten glass MG is supplied from the lower portion of the groove of the groove portion 210a, and the molten glass MG does not stay on the bottom surface and smoothly flows toward the speed component of the molded body 210, so that the molten glass MG smoothly overflows from the groove portion 210a. .

4 is a view for explaining the flow of the molten glass MG when the glass supply tube 106, the tube expansion portion 106b, and the molded body 210 are connected to each other from the top. As shown in FIG. 4, when the molten glass MG is supplied from the glass supply pipe 106 to the molded body 210, the width of the cross section of the flow path of the molten glass MG flowing through the glass supply pipe 106 is close to the glass supply pipe 106 and the formed body 210. changes gradually, the glass supply tube 106 cross-sectional view of the road ilk lateral width of the body from the glass supply tube 106b ilk path cross-sectional width of W ₁ to W 210a to the passage cross section of the groove portion ilk article 210. ₂ gradually changes, and therefore The retention of the molten glass MG is suppressed, and it can smoothly flow into the groove part 210a of the molded object 210.

5(a) and 5(b) are views showing a state in which the groove portion 210a of the former molded body 210 is connected to the glass supply pipe 106. As shown in Figs. 5(a) and 5(b), the flow path cross section of the connection position of the glass supply pipe 106 is smaller than the flow path cross section of the groove portion 210a, so that the flow path cross section of the molten glass MG is rapidly expanded at the connection position. Therefore, as shown in Fig. 5 (b), a flow of the molten glass MG having a velocity component in a direction inclined with respect to the extending direction (X direction) of the groove portion 210a is generated, and the molten glass MG fails in the groove portion 210a. The X direction flows smoothly. In particular, since the bottom surface of the groove portion 210a is connected to the wall surface of the glass supply tube 106 in a stepped manner, The flow of the molten glass MG flowing near the bottom surface is largely maintained.

As described above, in the present embodiment, the glass supply tube 106 includes the tube expansion portion 106b at its end portion. At this time, the width of the cross section of the flow path of the molten glass MG flowing through the glass supply pipe 106 gradually increases as it approaches the connection position between the open end of the glass supply pipe 106 and the open end of the groove portion 210a of the molded body 210. The position reaches the groove width of the groove portion 210a. At the connection position, the edge of the open end of the glass supply tube 106 (tube expansion portion 106b) has a shape conforming to the shape of the edge of at least the bottom surface of the open end of the groove portion 210a of the molded body 210, and the wall surface and the groove of the glass supply tube 106. The bottom surface of the portion 210a is connected without a step. Therefore, in the present embodiment, the flow of the molten glass MG from the glass supply tube 106 to the groove portion 210a of the molded body 210 can be made smooth, and the residence time of the molten glass MG in the groove portion 210a can be unified within a relatively fixed range. The molten glass MG overflows from the above-described groove portion 210a. In other words, when the molten glass MG is supplied from the glass supply tube 106 to the groove portion 210a of the molded body 210 in the supply step, the molten glass MG does not stay at the bottom of the groove portion 210a and has a velocity component toward the molded body 210. The molten glass MG is caused to flow. Thereby, it is possible to manufacture a high-quality glass plate which is less likely to cause devitrification of the glass, a foreign material, a corrugated material, and a uniform thickness.

(Variation 1)

Fig. 6(a) is a view showing a modification 1 of the connection between the groove portion 210a of the molded body 210 and the tube expansion portion 106b. The flow path cross section of the groove portion 210a is formed by using two groove bottom inclined surfaces 210b and 210c which are inclined at the bottom surface of the groove portion 210a as shown in the drawing. In this case, the width of the cross section of the flow path of the molten glass MG flowing through the glass supply pipe 106 is also close to the opening end of the glass supply pipe 106 and the opening of the groove portion 210a of the formed body 210 by the pipe expansion portion 106b. The connection position of the end is gradually enlarged, and the groove width of the groove portion 210a is reached at the connection position. Further, at the connection position, the edge of the opening end of the glass supply tube 106 (tube expansion portion 106b) has a shape conforming to the shape of the edge of at least the bottom surface of the opening end of the groove portion 210a of the molded body 210, and the wall surface of the glass supply tube 106 It is connected to the bottom surface of the groove portion 210a without a step. Further, the cross-sectional shape of the open end of the tube expansion portion 106b has a shape of a side surface (side wall surface) of the open end of the groove portion 210a. One of the parts of the (straight line shape) has a uniform shape. Therefore, the flow of the molten glass MG to the groove portion 210a of the molded body 210 can be made smooth, and the residence time of the molten glass MG in the groove portion 210a can be unified within a relatively fixed range, and the molten glass MG can be overflowed from the groove portion 210a. . Thereby, it is possible to manufacture a high-quality glass plate which is less likely to cause devitrification of the glass, a foreign material, a corrugated material, and a uniform thickness.

(Variation 2)

Fig. 6(b) is a view showing a second modification of the connection between the groove portion 210a of the molded body 210 and the tube expansion portion 106b.

The flow path section of the groove portion 210a is formed by the bottom surface 210d of the curved surface having a circular bottom surface as shown in the drawing. In this case, the width (diameter) of the cross section of the flow path of the molten glass MG flowing through the glass supply pipe 106 is also close to the open end of the glass supply pipe 106 and the groove portion of the formed body 210 by the pipe expansion portion 106b. The connection position of the open end of 210a is gradually enlarged, and the groove width of the groove portion 210a is reached at the connection position. Further, at the connection position, the edge of the opening end of the glass supply tube 106 (tube expansion portion 106b) has a shape conforming to the shape of the edge of at least the semicircular bottom surface 210d of the opening end of the groove portion 210a of the molded body 210, and the glass supply The wall surface of the tube 106 is connected to the bottom surface of the groove portion 210a without a step. In other words, the tube expansion portion 106b expands the flow path cross section while maintaining the circular shape of the glass supply tube 106 having a circular cross-sectional shape, and has a circular shape corresponding to the size of the bottom surface 210d at the connection position. Therefore, the flow of the molten glass MG to the groove portion 210a of the molded body 210 can be made smooth, and the residence time of the molten glass MG in the groove portion 210a can be unified within a relatively fixed range, and the molten glass MG can be overflowed from the groove portion 210a. . Therefore, in the second modification, it is possible to manufacture a high-quality glass plate which is less likely to cause devitrification of the glass, a foreign material, a corrugated material, and a uniform thickness.

(Variation 3)

7(a) and 7(b) are views showing the form of the modification 3. In the modification 3, the flow path cross section of the molten glass MG in the groove portion 210a of the molded body 210 is gradually reduced as it approaches the connection position where the groove portion 210a of the molded body 210 is connected to the glass supply pipe 106. That is, to form The cross section of the flow path of the molten glass MG in the groove portion 210a of the body 210 flows toward the molten glass MG so as to gradually become smaller as the connection position between the groove portion 210a of the molded body 210 and the glass supply tube 106 is gradually decreased.

A groove inclined surface 210e is provided below the groove portion 210a. In the example shown in FIGS. 7(a) and 7(b), the groove inclined surface 210e is lower than a portion extending in the depth direction with a certain groove width, and the groove width is continuously narrowed to terminate at the bottom of the groove. Face, and is a part of the bottom. The width W (see FIG. 7(b)) of the groove inclined surface 210e becomes larger as it approaches the connection position where the groove portion 210a is connected to the glass supply pipe 106 (it becomes smaller as it goes away from the glass supply pipe 106). That is, the groove portion 210a has a portion at the lower portion of the groove including the bottom surface, that is, the groove width is narrowed as it advances in the depth direction of the groove portion 210a, and the groove width is narrowed as it approaches the connection position with the glass supply pipe 106. The starting position of the groove portion 210a in the depth direction becomes shallow. With this portion, the flow path cross section of the groove portion 210a gradually becomes smaller as it approaches the above-described connection position. In particular, since the flow path cross section at the lower portion of the groove portion 210a is closer to the connection position, the molten glass MG located in the vicinity of the bottom surface of the groove portion 210a can be prevented from staying when the molten glass MG is supplied from the glass supply tube 106. Flow smoothly.

Further, when the flow path cross section in the glass supply tube main body 106a is extremely smaller than the groove portion 210a, the expansion ratio of the flow path cross section of the tube expansion portion 106b becomes large. In this case, in the pipe expansion portion 106b having a large expansion ratio, there is a case where the smooth flow of the molten glass MG (the flow in which the flow of the molten glass MG does not stay) cannot be maintained. Therefore, in the third modification, in order to keep the molten glass MG flowing smoothly, the flow path cross section is reduced in the vicinity of the connection position of the groove portion 210a, and the flow path cross section is gradually enlarged as it is separated from the connection position. The expansion of the flow path profile of the groove portion 210a may be an expansion of continuity or a stepwise expansion. Of course, the tube expansion portion 106b is connected to the groove portion 210a in a shape having a shape corresponding to the bottom surface of the groove portion 210a or the groove inclined surface 210e at the connection position between the tube expansion portion 106b and the groove portion 210a. Therefore, in the third modification, in the groove portion 210a, the molten glass MG is less likely to stay, and it is possible to produce a high quality which is less likely to cause devitrification of the glass or a foreign material, no corrugated, and uniform thickness. Glass plate.

As described above, in the present embodiment and the modifications 1 to 3, the glass supply tube 106 includes the tube expansion portion 106b at the end portion thereof. At this time, the width of the cross section of the flow path of the molten glass MG flowing through the glass supply pipe 106 gradually increases as it approaches the connection position between the open end of the glass supply pipe 106 and the open end of the groove portion 210a of the molded body 210. The position reaches the groove width of the groove portion 210a. Further, at the connection position, the edge of the opening end of the glass supply tube 106 (tube expansion portion 106b) has a shape conforming to the shape of the edge of at least the bottom surface of the opening end of the groove portion 210a of the molded body 210, and the wall surface of the glass supply tube 106 It is connected to the bottom surface of the groove portion 210a without a step. Therefore, in the present embodiment, the flow of the molten glass MG from the glass supply tube 106 to the groove portion 210a of the molded body 210 can be made smooth, and the residence time of the molten glass MG in the groove portion 210a can be unified within a relatively fixed range. The molten glass MG is allowed to overflow from the groove portion 210a. Therefore, it is difficult to produce a devitrified or heterogeneous blank of glass.

The cross-sectional shape of the flow path of the glass supply pipe 106 is continuously changed by the pipe expansion portion 106b which is a part of the glass supply pipe 106, but the cross-sectional shape of the flow path may be changed stepwise. However, from the viewpoint of smooth flow of the molten glass MG, it is preferable that the lateral width of the flow path cross section of the molten glass MG continuously changes from the lateral width of the glass supply tube 106 to the groove width of the groove portion 210a.

(Characteristics and application of glass plates)

In the case where the glass plate of the present embodiment is used for a glass plate for a flat panel display, it is exemplified that the glass raw material is mixed so as to have the following glass composition.

An alkali-free glass containing the following components: SiO ₂ : 50 to 70% by mass, Al ₂ O ₃ : 0 to 25% by mass, B ₂ O ₃ : 1 to 15% by mass, MgO: 0 to 10% by mass, CaO: 0 to 20% by mass, SrO: 0 to 20% by mass, BaO: 0 to 10% by mass, and RO: 5 to 30% by mass (wherein R is the total amount of Mg, Ca, Sr, and Ba).

Further, in the present embodiment, the alkali-free glass is used, but the glass plate may be a glass containing a trace amount of an alkali metal and containing a small amount of alkali. In the case of containing an alkali metal, the total amount of R' ₂ O contained is preferably 0.10% by mass or more and 0.5% by mass or less, preferably 0.20% by mass or more and 0.5% by mass or less (wherein R' is selected At least one of Li, Na and K is a component contained in the glass plate). Of course, the total of R' ₂ O may also be less than 0.10% by mass.

Further, in the case of applying the method for producing a glass plate of the present invention, the glass composition may contain, in addition to the above components, SnO ₂ : 0.01 to 1% by mass (preferably 0.01 to 0.5% by mass), Fe _{2 .} O ₃ : 0 to 0.2% by mass (preferably 0.01 to 0.08% by mass), and a glass raw material may be prepared in such a manner that substantially no As ₂ O ₃ , Sb ₂ O _{3 or} PbO is contained in consideration of environmental burden.

Further, in recent years, in order to achieve further high definition of the screen display of a flat panel display, it is required to use a display of p-Si (low temperature polysilicon) ‧ TFT or an oxide semiconductor without using an α-Si (amorphous germanium) ‧ TFT. Here, in the step of forming a p-Si (low temperature polysilicon) TFT or an oxide semiconductor, there is a heat treatment step in which the temperature is higher than the formation step of the α-Si‧ TFT. Therefore, the glass plate forming the p-Si‧ TFT or the oxide semiconductor is required to have a small heat shrinkage rate. In order to reduce the heat shrinkage rate, it is preferable to increase the strain point, but the glass having a high strain point tends to have a high liquidus temperature and a low liquid phase viscosity as described above. That is, the liquid phase viscosity is close to the appropriate viscosity of the molten glass in the forming step. Therefore, in order to suppress devitrification, it is more strongly required not to cause the flow of the molten glass MG to stay in the groove portion 210a of the molded body 210. In the present embodiment and the modifications 1 to 3, the flow of the molten glass MG is less likely to stay. Therefore, the method for producing a glass sheet of the present invention can also be applied to a glass sheet using, for example, glass having a strain point of 655 ° C or higher. In particular, the method for producing a glass plate of the present invention can also be applied to a p-Si‧ TFT or an oxide semiconductor using a strain point of 655 ° C. A glass plate with a strain point of 680 ° C or higher and a strain point of 690 ° C or higher is less likely to cause devitrification.

Further, the glass sheet of the present invention can also be applied to a glass sheet using a glass having a liquidus viscosity of 60,000 poise or less and a glass having a liquidus viscosity of 50,000 poise or less, particularly a glass having a liquidus viscosity of 45,000 poise or less. The method is not easy to cause devitrification.

In the case where the glass having a strain point of 655 ° C or higher or a liquid phase viscosity of 45,000 poise or less is used for the glass plate, for example, the glass plate is exemplified as containing the following components by mass%.

Preferably, the following alkali-free glass or glass containing a small amount of alkali contains: SiO ₂ 52 to 78% by mass, Al ₂ O ₃ 3 to 25% by mass, B ₂ O ₃ 3 to 15% by mass, RO (where R is all components contained in the glass plate selected from the group consisting of Mg, Ca, Sr, and Ba, and is at least one of 3 to 20% by mass; and mass ratio (SiO ₂ + Al ₂ O ₃ ) / B ₂ O ₃ In the range of 7~20.

Further, in order to further increase the strain point, the mass ratio (SiO ₂ + Al ₂ O ₃ )/RO is preferably 7.5 or more. Further, in order to increase the strain point, it is preferable to set the β-OH value to 0.1 to 0.3 mm ^-1 . Further, in order to achieve a high strain point and prevent a decrease in liquid phase viscosity, it is preferred to set CaO/RO to 0.65 or more. The glass raw material can also be prepared in a manner that does not substantially contain As ₂ O ₃ , Sb ₂ O _{3 ,} and PbO in consideration of environmental burden.

Further, in addition to the above components, the glass used in the glass plate of the present embodiment may contain other various oxides in order to adjust various physical, melting, clarifying, and forming properties of the glass. Examples of such other oxides are not limited to the following, but examples thereof include SnO ₂ , TiO ₂ , MnO, ZnO, Nb ₂ O ₅ , MoO ₃ , Ta ₂ O ₅ , WO ₃ , Y ₂ O _{3 ,} and La. ₂ O ₃ . Here, since the glass plate for a flat panel display such as a liquid crystal display or an organic EL display is particularly strict with air bubbles, it is preferable that at least the above-mentioned oxide contains SnO _{2 having a} large clarification effect.

A nitrate or a carbonate may be used as a supply source of the above RO. Further, in order to increase the oxidizing property of the molten glass, it is more preferable to use nitrate as a supply source of RO in a ratio suitable for the step.

In the above, the method for producing the glass sheet of the present invention has been described in detail. However, the present invention is not limited to the above-described embodiments, and various modifications and changes can be made without departing from the spirit and scope of the invention.

106‧‧‧Glass supply tube

106a‧‧‧glass supply tube body

106b‧‧‧ Tube Expansion Department

210‧‧‧Formed body

210a‧‧‧Slots

210b‧‧‧ sidewall

210c‧‧‧ bottom front

Claims (12)

A method for producing a glass sheet, comprising: flowing a molten glass in a groove portion of a molded body to produce a glass sheet, and comprising: a step of melting a glass raw material to produce molten glass; and a supplying step of The molten glass is supplied to the molded body through a transfer pipe; and a forming step of forming the molten glass by using the molded body to form a flat glass; and the transfer tube has a tube expansion portion in which a flow path of the molten glass gradually expands, and the tube One end of the expansion portion is connected to the groove portion of the molded body, and when the molten glass is supplied from the transfer pipe to the groove portion of the molded body in the supplying step, the molten glass does not stay on the bottom surface of the groove portion. The molten glass is caused to flow so as to have a velocity component toward the molded body. The method of manufacturing a glass sheet according to claim 1, wherein the conveying pipe is connected to the open end of the groove portion, and an area of a cross section of the flow path of the molten glass flowing through the conveying pipe is close to an opening end of the conveying pipe and the above The connection position of the opening end of the groove portion of the molded body is gradually widened. The method for producing a glass sheet according to claim 1, wherein in the supplying step, when the molten glass is supplied from the conveying pipe to the groove portion of the molded body, a width of a cross section of a flow path of the molten glass flowing through the conveying pipe The tape is gradually widened as it approaches the connection position between the open end of the transfer tube and the open end of the groove portion of the molded body. The method for producing a glass sheet according to claim 3, wherein in the supplying step, the molten glass is supplied from the conveying pipe to the groove portion of the molded body, and flows through The width of the cross section of the flow path of the molten glass of the transfer pipe reaches the groove width of the groove portion at the connection position, and at the connection position, the edge of the open end of the transfer pipe has an open end with the groove portion of the molded body At least the shape of the edge of the bottom surface is uniform, and the wall surface of the conveying pipe is connected to the bottom surface of the groove portion without a step. The method for producing a glass sheet according to any one of claims 1 to 4, wherein the molten glass is supplied to the molded body from a lower portion of a groove including a bottom surface of the groove portion. The method for producing a glass sheet according to any one of claims 1 to 4, wherein the edge of the opening end of the conveying pipe has a shape that matches a part of a shape of a side edge of the side surface of the opening end of the groove portion. The method for producing a glass sheet according to any one of claims 1 to 4, wherein the conveying pipe has a width of the flow path section continuously extending to an opening end of the conveying pipe and an opening end of the groove portion of the forming body The end of the position. The method for producing a glass sheet according to any one of claims 1 to 4, wherein the groove portion of the molded body is close to a connection position between an open end of the transfer tube and an open end of the groove portion of the molded body, The cross-section of the flow path of the molten glass in the groove portion of the molded body is gradually reduced. The method of manufacturing a glass sheet according to claim 8, wherein the groove portion has a portion at a lower portion of the groove including the bottom surface, that is, the groove width is narrowed as it advances in a depth direction of the groove portion, and is close to the connection At the position, the initial position in the depth direction in which the groove width is narrowed becomes shallow. The method for producing a glass sheet according to any one of claims 1 to 4, wherein the molten glass has a strain point of 655 ° C or higher. The method for producing a glass sheet according to any one of claims 1 to 4, wherein the glass sheet is a glass sheet for a flat panel display. A method for manufacturing a glass plate, characterized in that it is a glass plate, and The method includes: a step of melting a glass raw material to produce molten glass; a supplying step of supplying the molten glass to a molded body through a transfer pipe; and a forming step of molding the molten glass using the molded body to form a flat glass; Further, the transfer pipe has a pipe expansion portion in which a cross section of the molten glass flow path is gradually expanded, and one end of the pipe expansion portion is connected to the groove portion of the molded body, and the molten glass is supplied from the transfer pipe to the above-described supply step. In the groove portion of the molded body, the width of the cross section of the flow path of the molten glass flowing through the transfer pipe is gradually widened as it approaches the connection position between the open end of the transfer pipe and the open end of the groove portion of the molded body. a groove width of the groove portion at the connection position, and an edge of the opening end of the conveying pipe has a shape conforming to an edge shape of at least a bottom surface of the opening end of the groove portion of the molded body at the connection position, and the conveying The wall surface of the tube is connected to the bottom surface of the groove portion without a step.