WO2009081740A1

WO2009081740A1 - Process and apparatus for producing glass plate

Info

Publication number: WO2009081740A1
Application number: PCT/JP2008/072450
Authority: WO
Inventors: Noritomo Nishiura; Koki Ueda; Hidetaka Oda; Tomonori Kano; Daisuke Nagata
Original assignee: Nippon Electric Glass Co., Ltd.
Priority date: 2007-12-25
Filing date: 2008-12-10
Publication date: 2009-07-02

Abstract

A process for producing a glass plate (C) which comprises: a forming step in which a molten glass (A) is fed to a trough (10) disposed in a forming furnace (11) and the molten glass (A) is caused to flow down from the trough (10) through a conveyance passage (18) extending vertically to thereby stretch and form the glass (A) into a platy glass ribbon (B); an annealing step in which internal strain in the glass ribbon (B) is removed in an annealing lehr (12); a cooling step in which the glass ribbon (B) is cooled to around room temperature; and a cutting step in which the glass ribbon is cut into a given size, the pressure of the atmosphere surrounding the forming furnace (11) and/or annealing lehr (12) being elevated.

Description

Glass plate manufacturing method and manufacturing equipment

The present invention relates to a method for manufacturing a glass plate and a manufacturing facility therefor, in which molten glass is caused to flow down from a molded body and a glass ribbon is stretch-formed in the vertical direction.

As a manufacturing method of flat glass for flat panel displays such as various electronic devices, particularly liquid crystal displays, a down draw method is known in which glass glass is drawn by flowing molten glass from a molded body and drawing a glass ribbon in a vertical direction. Yes.

There are two types of downdraw methods: the overflow downdraw method and the slot downdraw method. In particular, the overflow downdraw method has a very small surface waviness and roughness and provides a glass plate with excellent surface quality. It is widely known as a method that can

In the overflow down draw method, molten glass continuously supplied to the top of a molded body having a wedge-shaped cross-sectional shape is caused to flow down from the top of the molded body along both side surfaces, and is fused at the lower end of the molded body. Thus, a plate-like glass ribbon is formed, and both edges of the glass ribbon are stretched and formed into a glass ribbon by flowing down a conveying path extending in the vertical direction while being sandwiched by a plurality of pulling rollers. As a result, the glass ribbon gradually solidifies and becomes a glass plate having a predetermined width and thickness. Further, the ambient temperature in the transport path is strictly controlled, and thereby the internal strain (thermal strain) of the glass plate is sufficiently reduced, and then cooled to near room temperature.

In particular, in the case of a glass plate for liquid crystal display, if even a slight internal strain remains inside the glass plate, a homogeneous image cannot be obtained due to birefringence. Various ideas for cooling have been proposed.

For example, in Japanese Patent Laid-Open No. 5-124826, in order to prevent internal deformation of the glass plate due to the influence of cooling of the roller shaft, and to prevent the glass plate from being deformed, the roller is supported in one piece, or in the conveyance path of the glass ribbon. In order to prevent internal distortion caused by thermal convection, a convection prevention plate that partitions the inside of the conveyance path horizontally is disclosed.

In JP-A-10-53427, a plurality of chambers are formed by horizontally dividing the inside of a forming furnace or an annealing furnace, each room is provided with a room temperature adjusting function, and sufficient slow cooling is performed. A method for producing a glass plate with low internal strain is disclosed.

Furthermore, Japanese Patent Application Laid-Open No. 2001-31435 discloses a technique for suppressing minute internal distortion and deformation by forming the temperature distribution of an annealing furnace in the width direction of the glass ribbon.
Japanese Patent Laid-Open No. 5-124826 Japanese Patent Laid-Open No. 10-53426 JP 2001-31435 A

In recent years, liquid crystal displays are required to have higher definition and higher image quality, and glass plates used therefor are required to have a maximum internal strain of 1.0 MPa or less. Moreover, the glass plate for liquid crystal displays has been rapidly increased in size, and for example, glass ribbons having a width dimension (effective width) of 2000 mm or more at a part finally becoming a glass product have been formed. Yes. However, as the size of the glass plate to be produced increases, the internal strain of the glass plate also tends to increase, making it difficult to reduce the internal strain to 1.0 MPa or less.

One of the causes of the internal distortion of the glass plate is an air flow rising along the surface of the glass ribbon (hereinafter referred to as a low temperature air flow). That is, in the glass ribbon conveyance path, the low-temperature air flow always rises along the surface of the glass ribbon, and the ambient temperature in the annealing furnace is likely to fluctuate. Japanese Patent Application Laid-Open No. 5-139766 discloses that a convection prevention plate is formed in the annealing furnace. However, since the low-temperature air flow rises in the vicinity of the surface of the glass ribbon, the convection prevention plate is sufficiently blocked. Can not do it. In order to completely prevent low-temperature airflow with the convection prevention plate, it is necessary to make the distance between the glass ribbon and the convection prevention plate very small, but the glass ribbon comes into contact with the convection prevention plate and the surface is scratched. There is a risk of formation.

The present invention has been made in view of the above circumstances, and provides a method for obtaining a high-quality glass plate with high productivity by avoiding the problem of internal distortion that increases as the glass plate becomes larger. Technical issue.

As a result of various studies to solve the above problems, the present inventors have heated the low temperature air flow rising from the cooling chamber and the cutting chamber into the annealing furnace through the glass ribbon conveyance path in the annealing furnace. After that, leaking to the outside atmosphere through the gap between the furnace walls of the forming furnace and annealing furnace, and suppressing the leakage of the internal air of the forming furnace and annealing furnace, increasing the low-temperature air flow in the glass ribbon transport path The inventors have found that it is possible to suppress the problem and have proposed the present invention.

That is, in order to solve the above-mentioned problem, the invention according to claim 1 is to supply molten glass to a molded body provided in a molding furnace and to flow the molten glass from the molded body to a conveying path extending in a vertical direction. Forming a sheet-shaped glass ribbon, forming an annealing process, removing the internal distortion of the glass ribbon in an annealing furnace, cooling the glass ribbon to near room temperature, and fixing the glass ribbon to a predetermined level. A method of manufacturing a glass plate, comprising: a step of cutting to a size, wherein the atmospheric pressure of an external atmosphere of the forming furnace and / or the annealing furnace is pressurized.

In order to solve the above-mentioned problems, the invention according to claim 2 is to supply molten glass to a molded body provided in a molding furnace and to let the molten glass flow down from the molded body to a conveying path extending in a vertical direction. A forming process for drawing and forming into a plate-shaped glass ribbon, an annealing process for removing internal distortion of the glass ribbon in an annealing furnace, a cooling process for cooling the glass ribbon to near room temperature, and the glass ribbon having a predetermined size A method of manufacturing a glass plate, comprising: adjusting the atmospheric pressure in the molding furnace to be higher than the atmospheric pressure in the cooling step. Exist.

Invention of Claim 3 made | formed in order to solve the said subject introduces air from the exterior, and pressurizes the atmospheric pressure of the external atmosphere of a shaping | molding furnace and / or an annealing furnace, It is characterized by the above-mentioned It exists in the manufacturing method of the glass plate of description.

The invention according to claim 4 made to solve the above-mentioned problems is characterized in that the forming step is a step of forming a glass ribbon by an overflow down draw method or a slot down draw method. The glass plate manufacturing method according to any one of the above.

The invention according to claim 5 made to solve the above-mentioned problems is characterized in that the short side of the glass plate has a length of 2000 mm or more. Lies in the manufacturing method.

The glass plate according to any one of claims 1 to 5, characterized in that the maximum value of internal strain of the glass plate is 1.0 MPa or less. Exist in the manufacturing method.

The invention according to claim 7, which was made to solve the above-mentioned problems, is that the glass plate has a mass percentage of SiO ₂ 40 to 70%, Al ₂ O ₃ 2 to 25%, B ₂ O ₃ 0 to 20%, MgO 0-10%, CaO 0-15%, SrO 0-10%, BaO 0-15%, ZnO 0-10%, ZrO ₂ 0-10%, fining agent 0-2% The glass plate manufacturing method according to any one of claims 1 to 6 is characterized.

In order to solve the above-mentioned problems, the invention according to claim 8 is to supply molten glass to a molded body and to flow the molten glass from the molded body down to a conveying path extending in a vertical direction to form a plate-shaped glass ribbon. A forming furnace for drawing and forming, an annealing furnace for removing internal strain of the glass ribbon, a cooling chamber for cooling the glass ribbon to near room temperature, and for cutting the glass ribbon to a predetermined dimension A glass plate manufacturing facility comprising: a cutting chamber; and a pressurizing means for increasing the atmospheric pressure of the external atmosphere of the forming furnace and / or the annealing furnace. Exist.

The invention according to claim 9 made to solve the above-mentioned problems resides in the glass plate manufacturing facility according to claim 8, wherein the pressurizing means is a blower.

According to invention of Claim 1, while supplying molten glass to the molded object provided in the molding furnace, it is made to flow down from the molded object to the conveyance path | route extended in a perpendicular direction, and it is made into a plate-shaped glass ribbon. A forming step for stretch molding, an annealing step for removing internal strain of the glass ribbon in an annealing furnace, a cooling step for cooling the glass ribbon to near room temperature, a cutting step for cutting the glass ribbon to a predetermined dimension, In order to pressurize the atmospheric pressure outside the forming furnace and / or the annealing furnace, the air inside the forming furnace and the annealing furnace leaks to the outside atmosphere outside the furnace through the gap between the furnace walls. As a result, it is possible to suppress an increase in the low-temperature air flow in the conveyance path of the glass ribbon. As a result, variation in the atmospheric temperature in the annealing furnace can be minimized, and the internal strain can be sufficiently reduced even when the size of the glass plate is increased.

Here, pressurizing the atmospheric pressure of the molding furnace and / or the annealing furnace means that the pressure of the external space (chamber) surrounding either or both of the molding furnace and the annealing furnace is increased by the pressurizing means. . That is, it means that the pressure is adjusted so that the pressure is higher than the pressure when the pressurizing means is not used. The degree of pressurization may be set as appropriate so as to reduce the amount of leakage of the internal air of the molding furnace or annealing furnace to the outside of the furnace.

Also, the external space surrounding the molding furnace and the annealing furnace may be composed of one chamber or may be divided into two chambers, but it is necessary to maintain an airtight state. When the chamber is divided into two chambers, for example, when the molding furnace is surrounded by the molding chamber and the annealing furnace is surrounded by the annealing chamber, the pressure in the molding chamber and the annealing chamber is adjusted independently. .

According to invention of Claim 2, while supplying molten glass to the molded object provided in the molding furnace, it is made to flow down to the conveyance path | route which extends molten glass from this molded object to a perpendicular direction to a plate-shaped glass ribbon. A forming step for stretch molding, an annealing step for removing internal strain of the glass ribbon in an annealing furnace, a cooling step for cooling the glass ribbon to near room temperature, a cutting step for cutting the glass ribbon to a predetermined dimension, In the method for producing a glass plate including the above, the atmospheric pressure in the molding furnace is adjusted to be higher than the atmospheric pressure in the cooling step, so that an increase in the low-temperature air flow in the glass ribbon conveyance path can be suppressed. it can. As a result, variation in the atmospheric temperature in the annealing furnace can be minimized, and the internal strain can be sufficiently reduced even when the size of the glass plate is increased. As a means for adjusting the atmospheric pressure in the molding furnace to be higher than the atmospheric pressure in the cooling process below it, the pressure of the external atmosphere of the molding furnace is increased, or the air from the molding furnace to the external atmosphere For example, there can be used a method of suppressing the leakage of air, exhausting the atmosphere of the cooling process to the outside, and reducing the amount of air rising from the annealing furnace in the transfer path. Further, the difference between the atmospheric pressure in the molding furnace and the atmospheric pressure in the cooling process may be appropriately selected depending on the size of the equipment and the temperature conditions. A predetermined effect can be obtained by providing the difference.

According to the third aspect of the present invention, air is introduced from the outside and the atmospheric pressure of the external atmosphere of the molding furnace and / or annealing furnace is increased. It is possible to press. That is, by installing a blower outside the chamber surrounding the molding furnace and the annealing furnace and introducing air from the outside by the blower, the atmospheric pressure in the external atmosphere of the molding furnace and the annealing furnace can be easily increased.

According to the invention described in claim 4, since the forming step is a step of forming a glass ribbon by an overflow down draw method or a slot down draw method, it is possible to efficiently form a thin glass sheet. In particular, when obtaining a plate glass having excellent surface quality, it is desirable to employ the overflow downdraw method rather than the slot downdraw method. The slot down draw method is a method in which molten glass is supplied to a molded body having an elongated hole-shaped (slot-shaped) opening, and then the molten glass is drawn out from the opening of the molded body to form a plate-like glass ribbon. In this method, a glass ribbon is produced by stretching a glass ribbon in the vertical direction.

In the present invention, when the glass ribbon is cut into a predetermined length, the glass ribbon flowing down in the vertical direction from the cooling step may be cut in the width direction (direction perpendicular to the flowing direction of the glass ribbon) The ribbon may be bent from the vertical direction to the horizontal direction and cut in the width direction while moving in the horizontal direction.

According to invention of Claim 5, since the length of the short side of a glass plate is 2000 mm or more, many glass plates for display panels can be cut out from one glass plate (original plate), and production is carried out. Efficiency can be improved. As the size of the glass plate increases, the internal strain tends to increase, and one reason is that as the size of the glass plate increases, the manufacturing equipment becomes larger, and low-temperature air is introduced into the transport path of the glass ribbon. This is considered to be due to the fact that the ambient temperature in the annealing furnace tends to fluctuate. Therefore, the present invention is particularly useful for producing a large glass plate, specifically, a glass plate having a short side of 2000 mm or more, preferably 2500 mm or more, and more preferably 3000 mm or more.

According to the invention described in claim 6, since the maximum value of the internal strain of the glass plate is 1.0 MPa or less, the image of the liquid crystal display can be prevented from becoming inhomogeneous due to birefringence. According to the present invention, since the fluctuation of the atmospheric temperature in the annealing furnace can be minimized, the occurrence of internal strain can be suppressed even if the size of the glass plate is increased. Specifically, the maximum value of internal strain can be set to 1.0 MPa or less, 0.8 MPa or less, and further 0.7 MPa or less.

According to the invention of claim 7, wherein a glass plate, by mass _{_{_{_{percentage, SiO 2 40 ~ 70%,}}}} Al 2 O 3 2 ~ 25%, B 2 O 3 0 ~ 20%, MgO 0 ~ 10%, CaO Contains 0-15%, SrO 0-10%, BaO 0-15%, ZnO 0-10%, ZrO ₂ 0-10%, fining agent 0-2%, chemical resistance (good acid resistance , Alkali resistance, buffered hydrofluoric acid), heat resistance (strain point 630 ° C. or higher), meltability (temperature corresponding to a viscosity of 10 ^2.5 poise, 1600 ° C. or lower), moldability (liquidus temperature 1150 ° C. or lower) ), A thermal expansion coefficient (25 to 45 × 10 ⁻⁷ / ° C. at a temperature of 30 to 380 ° C.) and the like, and a glass plate for a liquid crystal display that can easily suppress internal distortion after molding can be obtained. .

The reason why the above glass composition is preferable is as follows.

SiO ₂ is a component that forms a network of glass, reduces the thermal expansion coefficient of glass, reduces internal strain, improves the acid resistance of glass, increases the strain point of glass, There is an effect of reducing thermal shrinkage. However, when the content of SiO ₂ increases, the high-temperature viscosity of the glass increases, the meltability deteriorates, and the devitrification blisters of cristobalite tend to precipitate. Therefore, the content of SiO ₂ is 40 to 70%, preferably 50 to 67%, more preferably 57 to 64%.

Al ₂ O ₃ is a component that lowers the thermal expansion coefficient of glass or reduces the internal strain of the glass plate. It also has the effect of raising the strain point of the glass and suppressing the devitrification of cristobalite. However, when the content of Al ₂ O ₃ increases, the buffered hydrofluoric acid resistance of the glass deteriorates, or the liquidus temperature rises and it becomes difficult to mold. Therefore, Al ₂ O ₃ is 2 to 25%, preferably 10 to 20%, more preferably 14 to 17%.

B ₂ O ₃ is a component that acts as a flux, lowers the viscosity of the glass, and improves the meltability. Moreover, it is a component which reduces the thermal expansion coefficient of glass or makes the internal distortion of a glass plate small. However, when the content of B ₂ O ₃ increases, the strain point of the glass decreases and the acid resistance tends to deteriorate. Therefore, the content of B ₂ O ₃ is 0 to 20%, preferably 5 to 15%, more preferably 7.5 to 12%.

MgO is a component that improves the meltability of the glass by reducing only the high temperature viscosity without reducing the strain point of the glass. However, when the content of MgO increases, devitrification bumps are likely to precipitate in the glass. Further, the resistance to buffered hydrofluoric acid is lowered, and when the glass plate is treated with buffered hydrofluoric acid, the surface thereof is eroded and the reaction product adheres, and it tends to become cloudy. Therefore, the content of MgO is 0 to 10%, preferably 0 to 5%, more preferably 0 to 3.5%.

CaO is a component that improves the meltability of the glass by lowering only the high temperature viscosity without lowering the strain point of the glass. However, when the content of CaO increases, the resistance to buffered hydrofluoric acid tends to deteriorate. Therefore, the CaO content is 0 to 15%, preferably 0 to 12%, more preferably 3.5 to 9%.

SrO is a component that improves the chemical resistance and devitrification resistance of glass. However, when the SrO content increases, the thermal expansion coefficient of the glass tends to increase and the internal strain of the glass plate tends to increase. Accordingly, the SrO content is 0 to 10%, preferably 0 to 8%, more preferably more than 0.5 to 8%.

BaO is a component that improves the chemical resistance and devitrification resistance of glass in the same manner as SrO. However, when the content of BaO increases, the density and thermal expansion coefficient of the glass tend to increase, and the meltability tends to deteriorate significantly. Therefore, BaO is 0 to 15%, preferably 0 to 10%, more preferably 0 to 8%.

ZnO is a component that improves the buffered hydrofluoric acid resistance and meltability of glass, but when its content increases, the devitrification resistance and strain point of the glass tend to decrease. Therefore, the content of ZnO is 0 to 10%, preferably 0 to 5%, more preferably 0 to 1%.

ZrO ₂ is a component that increases the strain point of the glass. However, when the content of ZrO ₂ increases, the density of the glass increases remarkably, and devitrified materials due to ZrO ₂ tend to precipitate. Therefore, the content of ZrO ₂ is 0 to 10%, preferably 0 to 7%, more preferably 0 to 5%.

As a clarifier, As ₂ O ₃ , Sb ₂ O ₃ , SnO ₂ , SO ₃ , F, Cl, etc. can be used up to 2%. However, As ₂ O ₃ and Sb ₂ O ₃ are environmentally hazardous substances and should not be used. In that case, it is preferable to contain 0.01 to 2% of SnO ₂ .

In the present invention, in addition to the above components, for example, Y ₂ O ₃ , La ₂ O ₃ , Nb ₂ O ₃ , and P ₂ O ₅ are added for the purpose of reducing the liquidus temperature of the glass and improving the formability. It is possible to contain up to 3% of each. However, if an alkali metal oxide (R ₂ O) such as Na ₂ O, K ₂ O, or Li ₂ O is contained, there is a risk of deteriorating the characteristics of various films and TFT elements formed on the liquid crystal display glass plate. Therefore, the inclusion of these components should be avoided. Specifically, it should be regulated to 0.1% or less with R ₂ O.

According to invention of Claim 8, while supplying molten glass to a molded object, it is made to flow down from the molded object to the conveyance path | route extended in a perpendicular direction, and the forming furnace for extending-molding to a plate-shaped glass ribbon And an annealing furnace for removing thermal distortion of the glass ribbon, a cooling chamber for cooling the glass ribbon to near room temperature, and a cutting chamber for cutting the glass ribbon to a predetermined dimension. In the glass plate manufacturing facility, a pressurizing means is provided for increasing the atmospheric pressure of the external atmosphere of the forming furnace and / or the annealing furnace. By making it difficult for the internal air of the furnace or annealing furnace to leak into the external atmosphere, an increase in the low-temperature air flow in the transfer path can be suppressed. As a result, variation in the atmospheric temperature in the annealing furnace can be minimized, and the internal strain can be sufficiently reduced even when the size of the glass plate is increased.

According to the invention described in claim 9, since the pressurizing means is a blower, the blower is installed outside the chamber surrounding the molding furnace and the annealing furnace, and air is introduced from the outside by the blower, thereby forming the furnace. In addition, it is possible to easily increase the atmospheric pressure in the external atmosphere of the annealing furnace.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic front view showing equipment for manufacturing a glass plate of the present invention. This manufacturing equipment is for manufacturing a glass plate (glass substrate) for a liquid crystal display by the overflow down draw method, and is supplied from the top to the molten glass 10 having a wedge-shaped cross-sectional shape. Overflowing A from the top and fusing at the lower end thereof, a forming furnace 11 for forming the glass ribbon B, an annealing furnace 12 for removing the internal strain while gradually cooling the glass ribbon B, and A cooling chamber 13 that sufficiently cools the cooled glass ribbon B and a cutting chamber 14 that cuts the cooled glass ribbon B into a predetermined dimension are provided. The molding furnace 11 and the annealing furnace 12 are surrounded by a molding chamber 15, and a blower 16 is installed outside the molding chamber 15. The cooling chamber 13, the cutting chamber 14 and the molding chamber 15 adjacent in the vertical direction are surrounded by an airtight peripheral wall portion 17, and the molding furnace 11, the annealing furnace 12, the cooling chamber 13 and the cutting chamber 14 are made of a glass ribbon B. Are communicated with each other through a conveying path 18 that flows down. The cutting chamber 14 is additionally provided with a transport path for transporting the glass plate C to a subsequent process (for example, an end surface polishing process) that is not shown.

Next, the manufacturing process of the glass plate by the said glass plate manufacturing equipment is demonstrated.

In this manufacturing facility, first, molten glass A is supplied to the top of the molded body 10 provided in the molding furnace 11, and the molten glass A overflows from the top of the molded body 10 and is fused at the lower end thereof. A shaped glass ribbon B is formed. A pair of cooling rollers (edge rollers) 19 are provided in the vicinity of the molded body 10, and both edges of the glass ribbon B are held between the cooling rollers 19, and shrinkage in the width direction is minimized.

Next, the formed glass ribbon B is gradually cooled in the annealing furnace 12 to remove internal strain. In the annealing furnace 12, a plurality of pairs of pulling rollers (annealing rollers) 20 are arranged in the vertical direction, and pulled downward while pulling in the width direction by the pulling roller 20 so that the glass ribbon B does not contract in the width direction due to surface tension or the like. To do. Further, the inside of the annealing furnace 12 is set to have a predetermined temperature gradient by a heater (not shown), and the glass ribbon B is generated inside by gradually decreasing the temperature as it flows through the annealing furnace 12. Internal distortion is removed.

Also, the blower 16 installed outside the molding chamber 15 is operated, and air is introduced into the molding chamber 15 from the outside through the filter 21 attached to the peripheral wall portion. As a result, the pressure in the molding chamber 15, that is, the pressure in the atmosphere outside the molding furnace 11 and the annealing furnace 12 is increased, and the amount of internal air leaking from the gaps between the

furnace walls

11 a and 12 a of the molding furnace 11 and the annealing furnace 12 is reduced. Will do. As a result, the atmospheric pressure in the molding furnace 11 can be made higher than the atmospheric pressure in the cooling step, that is, 0.001 atm or higher than the atmospheric pressure in the cooling chamber 13.

In the cooling chamber 13 below the annealing furnace 12, a plurality of pairs of support rollers 22 are disposed, and the glass ribbon B solidified to a predetermined width and thickness is pulled downward. The glass ribbon B is cooled to approximately room temperature in the cooling chamber 13. The glass ribbon cooled to near room temperature in the cooling chamber 13 is cut into a glass plate C having a predetermined size in the cutting chamber 14 and then conveyed to the subsequent process.

Using the above glass plate manufacturing equipment, by mass%, SiO ₂ 60%, Al ₂ O ₃ 15%, B ₂ O ₃ 10%, CaO 6%, SrO 6%, BaO 2%, fining agent 1 % Glass composition for liquid crystal display (OA-10, manufactured by Nippon Electric Glass Co., Ltd.).

The dimension of the obtained glass plate was 2360 × 2030 × 0.7 mm, and the maximum strain of this glass plate was measured and found to be 0.8 MPa.

Moreover, as a comparative example, the same equipment as in the above embodiment was used, and a glass plate was produced under the same conditions except that the blower 16 was not operated. When the maximum strain of this glass plate was measured, the pressure was 1.1 MPa. there were.

From the above, it can be understood that the glass plate according to the embodiment has a smaller maximum strain than the glass plate according to the comparative example, and thus the present invention has a great effect of reducing the internal strain of the glass plate.

Here, the maximum strain of the glass plate is obtained by measuring the strain stress from the birefringence amount of the glass plate by an optical heterodyne interferometry using a strain meter made by UNIOPTO. The reason why the maximum strain of the glass plate is obtained is that if there is a strong strain even at one place in the glass plate, the product standard of the glass plate for liquid crystal display is not satisfied.

In addition, this invention is not limited to said embodiment, In the range which does not deviate from the summary of this invention, it can implement with a various form further.

For example, in the above-described embodiment, the case where the present invention is applied to the production of a glass plate by the overflow downdraw method has been described. However, the present invention is similarly applied to the production of a glass plate by, for example, the slot downdraw method. Can be applied.

In the embodiment, the case where the molding furnace and the annealing furnace are surrounded by one chamber (molding chamber) has been described. However, the molding furnace and the annealing furnace are respectively surrounded by different chambers (for example, the molding chamber and the annealing chamber). May be. In that case, an air blower is installed only in one chamber or outside both chambers, and the air pressure is adjusted independently.

The glass plate manufacturing method and manufacturing equipment of the present invention includes a glass plate used for various flat panel displays such as a liquid crystal display glass plate, an electroluminescence display such as a plasma display, an organic EL, a field emission display, and the like. It can use for manufacture of the glass plate used as a base material for forming an electronic display functional element and a thin film.

It is a schematic front view which shows the manufacturing equipment of the glass plate of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Molded object 11 Molding furnace 11a Molding furnace wall 12 Annealing furnace 12a Annealing furnace wall 13 Cooling chamber 14 Cutting chamber 15 Molding chamber 16 Blower 17 Peripheral wall portion 18 Transport path 19 Cooling roller (edge roller)
20 Pulling roller (annealing roller)
22 Support roller A Molten glass B Glass ribbon C Glass plate

Claims

A molding step of supplying molten glass to a molded body provided in a molding furnace and drawing the molten glass from the molded body to a conveying path extending in the vertical direction to draw a glass ribbon, and the glass ribbon. In the method for producing a glass plate, comprising: an annealing step for removing the internal distortion of the glass ribbon in an annealing furnace; a cooling step for cooling the glass ribbon to near room temperature; and a cutting step for cutting the glass ribbon to a predetermined dimension. A method for producing a glass plate, comprising pressurizing an atmospheric pressure of an external atmosphere of a forming furnace and / or an annealing furnace.
A molding step of supplying molten glass to a molded body provided in a molding furnace and drawing the molten glass from the molded body to a conveying path extending in the vertical direction to draw a glass ribbon, and the glass ribbon. In the method for producing a glass plate, comprising: an annealing step for removing the internal distortion of the glass ribbon in an annealing furnace; a cooling step for cooling the glass ribbon to near room temperature; and a cutting step for cutting the glass ribbon to a predetermined dimension. A method for producing a glass plate, comprising adjusting the atmospheric pressure in the molding furnace to be higher than the atmospheric pressure in the cooling step.
3. The method for producing a glass plate according to claim 1 or 2, wherein air is introduced from the outside and the atmospheric pressure of the external atmosphere of the forming furnace and / or the annealing furnace is pressurized.
4. The method for producing a glass plate according to claim 1, wherein the forming step is a step of forming a glass ribbon by an overflow down draw method or a slot down draw method.
The method for producing a glass plate according to any one of claims 1 to 4, wherein the short side of the glass plate has a length of 2000 mm or more.
The method for producing a glass plate according to any one of claims 1 to 5, wherein the maximum value of internal strain of the glass plate is 1.0 MPa or less.
Glass plate, by mass percentage, SiO 2 40 ~ 70%, Al 2 O 3 2 ~ 25%, B 2 O 3 0 ~ 20%, MgO 0 ~ 10%, CaO 0 ~ 15%, SrO 0 ~ 10% The glass plate according to any one of claims 1 to 6, comprising a composition of BaO 0 to 15%, ZnO 0 to 10%, ZrO 2 0 to 10%, and fining agent 0 to 2%. Production method.
The molten glass is supplied to the molded body, and the molten glass flows down from the molded body to a conveying path extending in the vertical direction so as to be stretch-formed into a plate-shaped glass ribbon, and internal distortion of the glass ribbon is removed. An apparatus for manufacturing a glass sheet, comprising: an annealing furnace for cooling, a cooling chamber for cooling the glass ribbon to near room temperature, and a cutting chamber for cutting the glass ribbon to a predetermined dimension. An apparatus for producing a glass plate, comprising a pressurizing means for increasing the atmospheric pressure of an atmosphere outside a furnace and / or an annealing furnace.
The glass plate manufacturing facility according to claim 8, wherein the pressurizing means is a blower.