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KR101798292B1 - Method for making glass substrate for display - Google Patents

Method for making glass substrate for display Download PDF

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Publication number
KR101798292B1
KR101798292B1 KR1020150137944A KR20150137944A KR101798292B1 KR 101798292 B1 KR101798292 B1 KR 101798292B1 KR 1020150137944 A KR1020150137944 A KR 1020150137944A KR 20150137944 A KR20150137944 A KR 20150137944A KR 101798292 B1 KR101798292 B1 KR 101798292B1
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South Korea
Prior art keywords
glass
glass plate
cooling
plate
convex portion
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KR1020150137944A
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Korean (ko)
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KR20160038861A (en
Inventor
도모히데 시바하라
다까아끼 우부까따
Original Assignee
아반스트레이트 가부시키가이샤
아반스트레이트 타이완 인크
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    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B17/00—Forming molten glass by flowing-out, pushing-out, extruding or drawing downwardly or laterally from forming slits or by overflowing over lips
    • C03B17/06—Forming glass sheets
    • C03B17/064—Forming glass sheets by the overflow downdraw fusion process; Isopipes therefor
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B17/00—Forming molten glass by flowing-out, pushing-out, extruding or drawing downwardly or laterally from forming slits or by overflowing over lips
    • C03B17/06—Forming glass sheets
    • C03B17/067—Forming glass sheets combined with thermal conditioning of the sheets

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Re-Forming, After-Treatment, Cutting And Transporting Of Glass Products (AREA)

Abstract

A problem to be solved by the present invention is to provide a method of manufacturing a glass substrate capable of suppressing fogging of sheet glass. A forming step of forming a glass plate by flowing molten glass from below the formed body after lowering the molten glass along both side surfaces of the formed body, a cooling step of cooling while the formed glass plate is conveyed downward, And a detecting step of detecting a position in the width direction of the glass plate of the convex portion generated on the surface of the glass plate. When the plate thickness deviation is higher than the reference value, the viscosity of the glass plate at the widthwise position where the convex portion is detected is lowered to adjust the plate thickness deviation by the convex portion to be equal to or smaller than the reference value.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing a glass substrate for a display,

The present invention relates to a method of manufacturing a glass substrate for display.

An overflow down-draw method may be used in manufacturing a glass substrate (hereinafter referred to as "glass substrate for display") used for a flat panel display such as a liquid crystal display or a plasma display. The overflow downdraw method includes a step of forming a sheet glass in the form of a plate under the molded body by flowing over the molten glass from the upper portion of the molded body in the molding furnace and the step of cooling the sheet glass in the slow cooling furnace Cooling process. In the slow cooling furnace, the sheet glass is drawn between the pair of rollers, and after the sheet glass is conveyed downward by the rollers, the sheet glass is cooled to a desired thickness. Thereafter, the sheet glass is cut into a predetermined size to form a glass plate.

The molten glass flowing down along the side surface of the molded body is separated from the molded body and shrinks in the width direction of the sheet glass due to the surface tension. Patent Document 1 discloses a technique of adjusting the temperature of a rim portion of a sheet glass by using a cooling unit provided separately from a sheet glass in the vicinity of a rim portion in a width direction of the sheet glass between a formed body and a tension roller below the formed body, A method for suppressing shrinkage of glass is disclosed. Thereafter, the sheet glass whose shrinkage is suppressed is formed through the slow cooling space. In this slowly cooled space, the atmosphere temperature is controlled so as to be a desired temperature profile (temperature distribution in which no deformation occurs on the glass plate), so that the plate thickness deviation, warping, and deformation of the glass plate are suppressed.

[Patent Document 1] JP-A-5-124827

In recent years, in glass substrates for liquid crystal display devices, the required specifications (quality) have become strict. The surface of the glass substrate is required to have a high degree of flatness, and in order to satisfy the requirement specification, it is necessary to suppress the generation of specks (or local plate thickness variations) due to particularly sharp concave or convex. This molten iron is unevenness in which the thickness (height) of the glass plate is varied in a predetermined width, and when the molten glass contained in the molten glass supplied to the molten glass is elongated or the molten glass flows down the molten glass, Or occurs continuously in a stripe shape in the transport direction of the glass plate.

Accordingly, it is an object of the present invention to provide a method of manufacturing a glass substrate capable of suppressing fogging of sheet glass.

A first aspect of the present invention is a manufacturing method of a glass substrate for display,

A molding step of lowering molten glass overflowing from an upper portion of a sectioned wedge shaped molded article having a tip portion at a lower portion along both side surfaces thereof and then joining the molten glass under the molded body to form a glass plate;

A cooling step of cooling the shaped glass plate while conveying it downward,

And a detecting step of detecting a plate thickness deviation of the glass plate by the convex portion along with a widthwise position of the glass plate of the convex portion generated on the surface of the cooled glass plate,

When the plate thickness deviation is higher than the reference value,

And adjusting the thickness of the glass plate to be less than the reference value by lowering the viscosity of the glass plate at the widthwise position where the convex portion is detected in a temperature region higher than the softening point of the glass plate.

Here, the " reference value " is arbitrarily determined depending on the specifications required for the glass plate. The reference value may be, for example, 0.06 mu m.

In the cooling step, it is preferable to lower the viscosity by suppressing the cooling of the glass plate at the widthwise position where the convex portion is detected.

In the cooling step, it is preferable to suppress the cooling of the glass plate by disposing the insulating material at the widthwise position where the convex portion is detected.

It is preferable to lower the viscosity of the glass plate at the widthwise position where the convex portion is detected in the region where the viscosity of the glass plate is in the range of 10 7.5 to 10 9. 67 Poise.

Wherein the detecting step detects the plate thickness deviation of the glass plate by the concave portion and the convex portion along with the position in the width direction of the glass plate of the concave portion generated on the surface of the cooled glass plate,

When the plate thickness deviation is higher than the reference value,

Adjusting the thickness of the glass plate at the widthwise position where the concave portion is detected to increase the thickness deviation of the concave portion and the convex portion to be equal to or less than the reference value at a temperature region higher than the softening point of the glass plate desirable.

It is preferable to increase the viscosity of the joining portion of the molten glass by promoting cooling of the glass plate at the widthwise position where the concave portion is detected.

It is preferable that a coolant for promoting cooling of the glass plate is brought close to the widthwise position where the concave portion is detected in the confluence portion of the molten glass.

In an area in the range of the viscosity of the glass sheet 10 5.7 to 10 7. 5 Poise, it is desirable to increase the viscosity of the glass plate in the recess is detected in the width direction position.

A second aspect of the present invention is a manufacturing method of a glass substrate for display,

A molding step of lowering molten glass overflowing from an upper portion of a sectioned wedge shaped molded article having a tip portion at a lower portion along both side surfaces thereof and then joining the molten glass under the molded body to form a glass plate;

A cooling step of cooling the molded glass plate while conveying the molded glass plate downward in a space defined by a space in which the molding step is performed by a partition plate provided below the molded body;

And a detecting step of detecting a plate thickness deviation of the glass plate by the concave portion and the convex portion together with the position in the width direction of the glass plate of the concave portion and the convex portion generated on the surface of the cooled glass plate,

When the plate thickness deviation is higher than the reference value,

In the forming step, the cooling of the glass plate at the widthwise position where the concave portion is detected is promoted to increase the viscosity,

By reducing the viscosity by suppressing the cooling of the glass plate at the widthwise position where the convex portion is detected in the cooling step,

And the plate thickness deviation caused by the concave portion and the convex portion is adjusted to be equal to or less than the reference value.

According to the method of producing a glass plate and the apparatus for manufacturing a glass plate described above, the viscosity of the glass plate at the position in the width direction where the concave portion is detected is increased in the temperature region higher than the softening point of the glass plate, By reducing the viscosity of the glass plate at the directional position, the plate thickness deviation due to the concave portion and the convex portion is adjusted to be equal to or less than the reference value, so that the fining of the glass plate can be suppressed.

1 is a view showing a flow of the manufacturing method of the present embodiment.
2 is a schematic view of an apparatus for manufacturing a glass substrate.
3 is a schematic view of a molding apparatus.
4 is a sectional view taken along the line IV-IV in Fig.
5 is a view showing the positional relationship between the sheet glass and the insulating material.
6 is a diagram showing the positional relationship between the sheet glass and the insulating material.
7 is a diagram showing the positional relationship between the sheet glass and the coolant.

Hereinafter, a method of manufacturing the glass substrate of the present invention will be described.

(Overview of Manufacturing Method of Glass Substrate)

Fig. 1 is a view showing an example of a process of a manufacturing method of a glass substrate according to the present embodiment. The manufacturing method of the glass substrate mainly includes a melting step (ST1), a clarifying step (ST2), a homogenizing step (ST3), a supplying step (ST4), a molding step (ST5), a slow cooling step (ST6) and a cutting step . In addition, it may have a grinding step, a grinding step, a cleaning step, an inspection step, a packing step, and the like. The produced glass substrate is laminated in a packaging process as necessary and returned to the supplier of the destination.

In the melting step (ST1), the glass raw material is heated to produce molten glass.

In the refining step (ST2), the temperature of the molten glass is raised to generate bubbles containing oxygen, CO 2 or SO 2 contained in the molten glass. The bubbles absorb oxygen generated by the reduction reaction of a fining agent (tin oxide or the like) contained in the molten glass and grow, and are floated on the surface of the molten glass and discharged. Thereafter, in the refining step, the reducing material obtained by the reducing reaction of the refining agent undergoes the oxidation reaction by lowering the temperature of the molten glass. As a result, gas components such as oxygen in the bubbles remaining in the molten glass are reabsorbed in the molten glass, and the bubbles disappear.

In the homogenization step (ST3), the molten glass is stirred using a stirrer to homogenize the glass component. Thus, it is possible to reduce unevenness in the composition of the glass, which is a cause of spalling or the like. The homogenization process is performed in a stirring tank described later.

In the supplying step ST4, the molten glass which has been stirred is supplied to the molding apparatus.

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

In the molding step (ST5), the molten glass is formed into a sheet glass, and a flow of the sheet glass is made. An overflow downdraw method is used for forming.

In the gradual cooling step (ST6), the formed sheet glass is cooled to a desired thickness so that internal deformation does not occur and no warping occurs.

In the cutting step (ST7), the sheet glass after the slow cooling is cut to a predetermined length to obtain a plate-like glass substrate. The cut glass substrate is further cut to a predetermined size to produce a glass substrate having a target size.

Fig. 2 is a schematic view of an apparatus for producing a glass substrate for performing the dissolving step (ST1) to cutting step (ST7) in the present embodiment. As shown in Fig. 2, the apparatus for manufacturing a glass substrate mainly has a dissolving apparatus 100, a molding apparatus 200, and a cutting apparatus 300. Fig. The melting apparatus 100 has a melting vessel 101, a clarifying tube 102, a stirring vessel 103, feeding tubes 104 and 105, and a glass feeding tube 106.

The melting tank 101 shown in Fig. 2 is provided with a heating means such as a burner (not shown). A glass raw material to which a refining agent is added is introduced into the melting tank, and a dissolution step (ST1) is performed. The melted glass melted in the melting tank 101 is supplied to the cleaning tube 102 through the transfer tube 104.

In the purifying tube 102, the temperature of the molten glass MG is adjusted, and the smelting step (ST2) of the molten glass is performed using the redox reaction of the fining agent. The molten glass after refining is supplied to the stirring tank 103 through the transfer pipe 105.

In the stirring tank 103, the molten glass is stirred by the stirrer 110 and homogenization step (ST3) is performed. The molten glass homogenized in the stirring tank 103 is supplied to the molding apparatus 200 through the glass supply pipe 106 (supply step ST4).

In the molding apparatus 200, the sheet glass SG is formed from the molten glass by the overflow down-draw method (molding step ST5), and then slowly cooled (gradual cooling step ST6).

In the cutting apparatus 300, a plate-shaped glass substrate cut out from the sheet glass SG is formed (cutting step ST7).

(Molding apparatus)

Next, the molding apparatus 200 according to the present embodiment will be described. Fig. 3 is a schematic view showing the molding apparatus 200, and Fig. 4 is a sectional view taken along the line IV-IV in Fig.

The furnace wall of the molding apparatus 200 is formed by a combination of a refractory material such as a SiC member having an oxide coating, a refractory brick, a refractory heat insulating brick, a fiber-based heat insulating material, and a metal such as stainless steel. 3 and 4, the inner space of the molding apparatus 200 is divided into a molding furnace 201 and a lower annealing furnace 202 of the molding furnace 201. As shown in Fig. In the molding furnace 201, the molding step ST5 is performed, and in the annealing furnace 202, the slow cooling step ST6 is performed.

The molding furnace 201 is divided into an upper molding furnace 201A and a lower molding furnace 201B by an atmosphere dividing member 260 (0).

A molding body 210 and a plurality of coolants 220 are provided in the upper molding furnace 201A.

The molten glass is supplied from the dissolving apparatus 100 to the molded body 210 through the glass supply pipe 106 shown in Fig.

The molded body 210 is a thin and long structural body made of refractory bricks or the like, and has a wedge-shaped cross section as shown in Fig. A groove 212 serving as a flow path for guiding the molten glass MG is formed in the upper portion of the molded body 210. The groove 212 is connected to the third pipe 106 and the molten glass MG flowing through the third pipe 106 flows along the groove 212. The molten glass MG flowing through the grooves 212 slowly starts to overflow from the grooves 212 and the molten glass MG flowing over the both side walls 212 of the mold body 210 And merges at the lower end 213 of the formed body 210, and fuses and flows down vertically downward. Thereby, a sheet glass SG which is vertically downward directed from the molded body 210 is produced in the molding apparatus 200.

Further, the temperature of sheet glass (SG) in the immediately below the lower end 213 of the molded body 210 is 10 5.7 to 10 7. The temperature corresponding to a viscosity of 5 poise, for example, from 1000 to 1130 / RTI >

3 and 4, the plurality of coolants 220 are arranged at the same height as the portion where the molten glass MG joins the lower portion of the formed body 210 and the sheet glass SG is produced Is installed. Each coolant 220 is a rod-like member extending in the direction perpendicular to the width direction of the sheet glass SG and is arranged side by side in the width direction of the sheet glass SG. Each coolant 220 is installed on the wall surface of the upper molding furnace 201A so as to adjust the distance to the sheet glass SG by moving in the direction perpendicular to the width direction of the sheet glass SG by a moving mechanism .

The coolant 220 locally suppresses the heating amount of the sheet glass SG by shielding radiant heat from a heater (not shown) provided in the upper molding furnace 201A. Radiant heat from the sheet glass SG is absorbed by the coolant 220, thereby promoting local cooling of the sheet glass SG.

It is preferable that the viscosity of the glass constituting the sheet glass SG at the position of the same height as the coolant 220 is in the range of 10 5.7 to 10 7.5 Poise.

Further, the coolant 220 may be provided on only one side of the sheet glass SG, or on both sides of the sheet glass SG.

The coolant 220 is excellent in heat resistance and erosion resistance and is made of a material (for example, a refractory material such as refractory bricks, alumina, platinum, or a platinum alloy) having a higher thermal conductivity than the atmosphere in the upper molding furnace 201A. By adjusting the distance between the coolant 220 and the sheet glass SG, the width direction of the sheet glass SG can locally promote heat radiation from an arbitrary position.

The shape and position of each coolant 220 and the number of coolants 220 are determined by the positions of the concave and convex portions detected by the detecting device 290 to be described later and the concave amount from the reference plane of the concave portion and the protrusion Depending on the amount.

Here, the " reference surface " is a surface based on a flat region where the plate thickness deviation falls within a predetermined reference value when the plate thickness deviation of the sheet glass SG is measured by an optical surface inspection apparatus described later. The surface based on the flat area may be, for example, an average surface of the flat area, or may be a convex part whose protrusion amount in the flat area is not more than the reference value or a surface that passes through the concave part whose concave amount is equal to or smaller than the reference value and is parallel to the average surface.

The " reference value " is arbitrarily determined depending on the specifications required for the glass plate. The reference value may be, for example, 0.06 mu m.

The atmosphere dividing member 260 (0) is provided in the vicinity of the lower end 213 of the molded body 210 and the inner space of the molding furnace 201A is divided into the upper molding furnace 201A and the lower molding furnace 201B ). The atmosphere partitioning member 260 (0) is a pair of plate-shaped heat insulating materials and is provided on both sides in the thickness direction of the sheet glass SG so as to sandwich the sheet glass SG on both sides in the thickness direction Respectively. A gap is formed between the sheet glass SG and the atmosphere partitioning member 260 (0) so that the atmosphere dividing member 260 (0) does not contact the sheet glass SG. The atmosphere partitioning member 260 (0) divides the internal space of the molding apparatus 200 to separate the space between the molding path 201 above the atmosphere dividing member 260 (0) and the lower cooling path 202 Block movement.

In the lower molding furnace 201B, a pair of cooling rollers 230 and a cooling device 240 are provided.

The cooling roller 230 and the cooling device 240 are provided below the atmosphere dividing member 260 (0).

The pair of cooling rollers 230 are provided on both sides of the sheet glass SG in the thickness direction so as to sandwich the sheet glass SG on both sides in the thickness direction as shown in Figs. Cooling roller 230 is a temperature corresponding to the widthwise end portions of the sheet glass (SG), 9. 0 to about 10 poise or more viscosity (e.g. 900 ℃) is cooled to down to a temperature below. The cooling roller 230 is hollow and is quenched by supplying a cooling medium (for example, air or the like) to the inside. The cooling roller 230 is smaller in diameter than the conveying members 2501, 2502, ..., and 250n described below, has a short insertion length into the furnace, and is quenched quickly, so that there is less risk of deformation (eccentricity).

The cooling apparatus 240 includes a plurality of cooling units (the end cooling unit 241 and the central cooling unit 242) and cools the sheet glass SG.

The end cooling unit 241 is cooled so as to lower both ends in the width direction of the sheet glass SG to a temperature equivalent to a viscosity of 10 14 5 poise or more.

4, the central cooling unit 242 is provided with a cooling pipe 244 such as an air-cooling pipe or a water-cooled pipe. The central cooling unit 242 has a central portion in the width direction of the sheet glass SG, Cool from a high temperature to near the cold point. Here, the central portion of the sheet glass SG is an area excluding the object to be cut after the sheet glass is formed, and is an area produced so that the sheet thickness of the sheet glass SG becomes uniform.

The central cooling unit 242 rapidly cooling the sheet glass SG separated from the lower end 213 of the formed body 210 to the vicinity of the softening point and then gently cooling the sheet glass SG from the vicinity of the softening point to the vicinity of the cooling point do. For example, the central cooling unit 242 is divided into a plurality of sections in the flow direction, and the cooling speed in the flow direction of the sheet glass SG is adjusted.

3 and 4, a heat insulating material 243 is provided between the sheet glass SG and the cooling pipe 244 at an arbitrary position in the width direction of the sheet glass SG Respectively.

The heat insulating material 243 is excellent in heat resistance and erosion resistance and includes a material having a thermal conductivity lower than that of the atmosphere in the upper molding furnace 201A (for example, a heat insulating material such as a refractory insulating brick or a fiber thermal insulating material). The heat radiation from an arbitrary position in the width direction of the sheet glass SG can locally be suppressed by providing the heat insulating material 243 at an arbitrary position in the width direction of the sheet glass SG.

It is preferable that the viscosity of the glass constituting the sheet glass SG at the position of the same height as the heat insulating material 243 is in the range of 10 7.5 to 10 9.67 Poise.

The position at which the heat insulating material 243 is provided in the width direction of the sheet glass SG will be described later.

The shape of the heat insulating material 243 and the number of the heat insulating materials 243 are determined depending on the position of the concave portion and the convex portion detected by the detecting device 290 described later and the amount of concave from the reference surface of the concave portion and the amount of protrusion from the reference surface of the convex portion , As appropriate.

The annealing furnace 202 has a wall 203. The wall 203 separates the inside of the furnace in which the sheet glass SG of the annealing furnace 202 is conveyed and the furnace outside of the outside space. In the slow cooling furnace 202, a plurality of conveying members 250 (1), 250 (2), ... , The plurality of temperature regulating devices 270 (1), 270 (2), 270 (n), and the plurality of partition plates 260 (1), 260 , And 260 (n), respectively.

The slow cooling furnace 202 is partitioned by the lower molding furnace 201B by the partition plate 260 (1) and the inner space of the soft annealing furnace 202 is partitioned by a plurality of partition plates other than the partition plate 260 (1) And are partitioned into a plurality of spaces in the height direction by the first to third switches 2022, ..., and 202n. A plurality of partition plates 260 (1), 260 (2), ... , 250 (n), and 260 (n), respectively. , 250 (n), and a plurality of temperature regulating devices 270 (1), 270 (2), and 270 (n). Specifically, the conveying member 250 (1) and the temperature adjusting device 270 (1) are provided in the space partitioned by the partition plate 260 (1) and the partition plate 260 (2) The transporting member 250 (2) and the temperature regulating device 270 (2) are provided in the space defined by the plate 260 (2) and the not-shown partition plate 260 (3)

(Not shown) is also partitioned by partition plates 260 (4) to 260 (n-1) not shown between the partition plate 260 (3) and the partition plate 202n, The members 250 (4) to 250 (n-1) and the temperature adjusting devices 270 (4) to 270 (n-1) are similarly provided. In addition, the lowermost conveying member 250n and the temperature adjusting device 270n are provided in the space below the lowermost partition plate 260 (n).

Each of the conveying members 250 (1), 250 (2), ... , 250 (n) are provided on both sides in the thickness direction of the sheet glass SG, and include a pair of rotation shafts cantilevered by bearings (not shown) outside the furnace wall, and a pair of And a conveying roller. Each of the temperature regulating devices 270 (1), 270 (2), ... , 270 (n) include a pair of heaters provided on both sides in the thickness direction of the sheet glass SG. Each of the heaters has a plurality of heat sources in the width direction of the sheet glass SG, and the amount of heating can be adjusted individually. The plurality of heat sources is, for example, a chromium-based heating wire or the like.

In the lower molding furnace 201B and the annealing furnace 202, the cooling roller 230, the cooling device 240 and the temperature adjusting devices 270 (1), 270 (2), ... , 270 (n)] so that the sheet glass SG has a temperature distribution corresponding to a pre-designed temperature profile.

In the viscous region, for example, the temperature profile at the widthwise end of the sheet glass SG is lower than the temperature of the central region, and the temperature profile of the central region becomes uniform (first profile). Thereby, the sheet thickness of the sheet glass SG can be made uniform while suppressing the shrinkage in the width direction.

In the viscoelastic region, for example, a temperature profile (second profile) in which the temperature of the sheet glass SG gradually decreases in the width direction from the center portion toward the end portion is designed.

The temperature profile in the vicinity of the glass deformation point is designed such that the temperature at the end portion in the width direction of the sheet glass SG and the temperature at the central portion become substantially uniform.

The warpage and deformation (residual stress) of the sheet glass SG can be reduced by controlling the temperature of the sheet glass SG in accordance with the designed temperature profile. The central region of the sheet glass SG is a region including a portion of the object to make the plate thickness uniform, and the end portion of the sheet glass SG is a region including a portion of the object to be cut after manufacturing.

A detecting device 290 is provided below the slow cooling furnace 202. The detection device 290 is, for example, an optical surface inspection device, and is a device for detecting the positions of the concave and convex portions generated in the surface of the sheet glass SG carried out from the lower portion of the annealing furnace 202 in the width direction, The concave amount from the reference surface, the amount of protrusion from the reference surface of the convex portion, and the plate thickness deviation due to the concave portion and the convex portion are detected. The concave portion and the convex portion are formed by varying the thickness (height) of the sheet glass SG, and are continuously formed in a stripe shape in the conveying direction of the sheet glass SG. The reason that concave and convex portions are formed on the surface of the sheet glass SG is that a heterogeneous material contained in the molten glass supplied to the formed body 210 is elongated and a temperature change due to airflow occurs in the sheet glass descending from the molded body .

In the present embodiment, when the plate thickness deviation detected by the detecting device 290 exceeds a predetermined reference value, the plate thickness deviation is adjusted to be equal to or lower than the reference value by using the coolant 220 and the heat insulating material 243 do. It is possible to prevent the display irregularities in the display panel from occurring by adjusting the concavity or convexity of the concave or convex portion to be gentle.

Specifically, when the plate thickness deviation detected by the detecting device 290 exceeds a predetermined reference value and the concave portion is detected by the detecting device 290, in the joining portion of the molten glass, Locally promoting heat radiation from the sheet glass SG by bringing the coolant 220 close to the widthwise position where the concave portion of the sheet SG is detected. As a result, the portion of the sheet glass SG in the widthwise direction where the concave portion is detected is locally cooled, and the viscosity of the glass in this portion is locally increased. Thereafter, when the sheet glass SG is stretched, the locally cooled portion of the sheet glass SG becomes difficult to elongate, making it difficult for the sheet glass SG to be thin.

The distance between the coolant 220 and the sheet glass SG at this time is adjusted by the concave amount from the reference surface of the detected concave portion.

On the other hand, when the plate thickness deviation detected by the detecting device 290 exceeds a predetermined reference value and the convex portion is detected by the detecting device 290, as shown in Fig. 5, in the cooling step , The cooling of the sheet glass SG is locally suppressed by arranging the heat insulating material 243 at the position in the width direction where the convex portion of the sheet glass SG is detected. Thereby, the partial temperature of the widthwise position where the convex portion of the sheet glass SG is detected becomes relatively higher than the ambient temperature, and the viscosity of the glass in this portion becomes relatively lower than the ambient temperature. Thereafter, when the sheet glass SG is stretched, the locally heat-retained portion of the sheet glass SG becomes easy to stretch, and the thickness tends to become thin.

At this time, the thickness or the material of the heat insulating material 243 and the distance between the heat insulating material 243 and the sheet glass SG are adjusted by the amount of protrusion from the reference surface of the detected convex portion.

6, the distance between the heat insulating material 243 and the sheet glass SG is set shorter in the central portion of the width direction position where the convex portion C is detected, The distance between the heat insulating material 243 and the sheet glass SG may be increased.

As shown in Fig. 7, both ends of the widthwise position where the convex portion C is detected may be cooled more locally than the coolant 220 than the central portion. In this case, the sheet glass SG at both ends of the widthwise position at which the convex portion C is detected is difficult to elongate, and the amount of protrusion is smaller than the convex portion C at both ends of the widthwise position where the convex portion C is detected Small convex portions C1 and C2 (indicated by a one-dot chain line in Fig. 7) are formed. As a result, the protruding shapes of the both end portions in the width direction position of the convex portion C can be made gentle.

When a sharp concave portion (narrow concave portion) is detected at the position in the width direction of the sheet glass SG and the generation of the concave portion is suppressed by the cooling material 220, There is a possibility that the periphery of the position where the generation of the concave portion is suppressed is elongated and thinned and the position where the generation of the concave portion is suppressed becomes relatively thick and is detected as a slightly wider convex portion. In this case, it is also possible to finely adjust the plate thickness deviation to be equal to or less than the reference value by suppressing the occurrence of convex portions of the sheet glass SG by arranging the heat insulating material 243 in the width direction position where the convex portions are detected.

Conversely, when a steep convex portion (narrow convex portion) is detected at the position in the width direction of the sheet glass SG, if generation of the convex portion is suppressed by the heat insulating material 243, As a result, the position where the generation of the convex portion is suppressed is elongated and thinner than the circumference, and there is a possibility that the position is detected as a slightly wider concave portion. In this case, it is also possible to finely adjust the plate thickness deviation to be equal to or smaller than the reference value by suppressing the occurrence of the concave portion of the sheet glass SG by arranging the coolant 220 at the position in the width direction where the concave portion is detected.

As described above, according to the present embodiment, when the sheet thickness deviation is higher than the reference value, the sheet glass SG is cooled by bringing the coolant close to the widthwise position where the concave portion is detected in the merged portion of the molten glass, It is difficult to locally elongate the sheet glass SG at the widthwise position where the concave portion is detected, so that the thickness of the sheet glass SG is less likely to be thinned, so that the remaining concave portion can be suppressed. On the other hand, since the cooling of the sheet glass SG is suppressed by arranging the heat insulating material 243 at the widthwise position where the convex portions are detected, the viscosity is relatively lowered and the sheet glass SG is stretched at the widthwise position where the convex portions are detected By making it easier, the thickness tends to become thin, so that it is possible to suppress the remnant of the convex portion. This makes it possible to adjust the plate thickness deviation caused by the concave portion and the convex portion to be equal to or smaller than the reference value.

Although the method of manufacturing the glass substrate of the present invention has been described in detail, the present invention is not limited to the above-described embodiment, and various modifications and changes may be made without departing from the gist of the present invention.

For example, in the present embodiment, a plurality of tubes (magnetic tubes) including a magnetic body around which a coil is wound are arranged in the width direction of the sheet glass SG in the upper shaping furnace 201A, The sheet glass SG may be locally heated by discharging the eddy current to the magnetic tube by shedding and heating the magnetic tube by the juxtaposition of eddy currents. In this case, when the current is not supplied to the magnetic tube, the magnetic tube can be used as the coolant 220 of the present embodiment.

In the above embodiment, adjustment of the convex portion by promoting cooling by using the coolant 220 from both sides of the sheet glass SG, and adjustment of the concave portion by suppressing cooling by using the heat insulating material 243 are performed However, the present invention is not limited to this. For example, when concave or convex portions are detected on only one side of the sheet glass SG, the concave and convex portions may be adjusted only on one side of the sheet glass. In addition, even when concave and convex portions are detected on both sides of the sheet glass SG, the concave portion and the convex portion are first adjusted on the side of the convex portion from the reference surface and on the side where the convex portion is projected from the reference surface , And if the plate thickness deviation does not become equal to or smaller than the reference value, the concave portion and the convex portion may be adjusted on the opposite side.

An alkali-free boroaluminosilicate glass or a glass containing an alkali trace amount is used as the glass substrate produced by the glass substrate manufacturing method of the present embodiment, which has a high strain point and a stand-by point, and has good dimensional stability.

The glass substrate to which the present embodiment is applied includes, for example, alkali-free glass containing the following composition.

SiO 2 : 56-65 mass%

Al 2 O 3 : 15-19 mass%

B 2 O 3 : 8 - 13 mass%

MgO: 1-3 mass%

CaO: 4-7 mass%

SrO: 1-4 mass%

BaO: 0-2 mass%

Na 2 O: 0-1 mass%

K 2 O: 0-1 mass%

As 2 O 3 : 0-1 mass%

Sb 2 O 3 : 0-1 mass%

SnO 2: 0-1 wt%

Fe 2 O 3 : 0-1 mass%

ZrO 2 : 0-1 mass%

The glass substrate manufactured by the manufacturing method of the present embodiment is suitably used for, for example, a glass substrate for a liquid crystal display, a glass substrate for a flat panel display such as a glass substrate for an organic EL display, and a cover glass. It can also be used as a cover glass for a display or a housing of a mobile terminal device or the like, a touch panel plate, a glass substrate of a solar cell, or a cover glass.

In particular, glass substrates for liquid crystal displays using polysilicon TFTs, glass substrates for oxide semiconductor displays using oxide semiconductors such as IGZO (indium, gallium, zinc, oxygen), and glasses for LTPS display using LTPS (low temperature polysilicon) Suitable for substrates.

100: dissolution apparatus
101: Melting bath
102: Blue sign
103: stirring tank
104, 105: transfer pipe
106: glass supply pipe
200: forming device
201: Molding furnace
202: slow cooling
210: molded article
212: Home
213: Lower end
220: coolant
230: cooling roller
240: cooling device
241: End cooling unit
242: Central cooling unit
243: Insulation
244: Cooling tube
250 (1), 250 (2), ... , 250 (n): conveying member
260 (0): atmosphere partition member
260 (1), 260 (2), ... , 260 (n): partition member
270 (1), 270 (2), 270 (n)
290: Detecting device
300: Cutting device

Claims (9)

A molding step of lowering molten glass overflowing from an upper portion of a sectioned wedge shaped molded article having a tip portion at a lower portion along both side surfaces thereof and then joining the molten glass under the molded body to form a glass plate;
A cooling step of cooling the shaped glass plate while conveying it downward,
And a detecting step of detecting a plate thickness deviation of the glass plate by the convex portion along with a widthwise position of the glass plate of the convex portion generated on the surface of the cooled glass plate,
When the plate thickness deviation is higher than the reference value, a heat insulating material is disposed at a widthwise position where the convex portion is detected in a region in the cooling space where the viscosity of the glass plate is in the range of 10 7.5 to 10 9.67 Poise, And adjusting the thickness of the convex portion to be less than or equal to the reference value by lowering the viscosity by suppressing the cooling. The method according to claim 1,
Wherein the detecting step detects the plate thickness deviation of the glass plate by the concave portion and the convex portion along with the position in the width direction of the glass plate of the concave portion generated on the surface of the cooled glass plate,
When the plate thickness deviation is higher than the reference value,
And adjusting the thickness of the glass plate at the widthwise position where the concave portion is detected to increase the thickness deviation of the concave portion and the convex portion to be equal to or less than the reference value in a temperature region higher than the softening point of the glass plate, A method of manufacturing a glass substrate for display. 3. The method of claim 2,
And the viscosity of the glass substrate is increased by promoting the cooling of the glass plate at the widthwise position where the concave portion is detected in the merging portion of the molten glass. The method of claim 3,
Wherein a cooling material for promoting cooling of the glass plate is brought close to a widthwise position where the concave portion is detected in the merging portion of the molten glass. 5. The method according to any one of claims 2 to 4,
Wherein the viscosity of the glass plate at the widthwise position where the concave portion is detected is increased in the region where the viscosity of the glass plate is in the range of 10 5.7 to 10 7.5 Poise. A molding step of lowering molten glass overflowing from an upper portion of a sectioned wedge shaped molded article having a tip portion at a lower portion along both side surfaces thereof and then joining the molten glass under the molded body to form a glass plate;
A cooling step of cooling the formed glass plate while conveying the formed glass plate in a cooling space defined by a space in which the molding step is performed by the partition plate provided below the molded body,
And a detecting step of detecting a plate thickness deviation of the glass plate by the concave portion and the convex portion together with the position in the width direction of the glass plate of the concave portion and the convex portion generated on the surface of the cooled glass plate,
When the plate thickness deviation is higher than the reference value,
In the forming step, the cooling of the glass plate at the widthwise position where the concave portion is detected is promoted to increase the viscosity,
By reducing the viscosity by suppressing the cooling of the glass plate at the widthwise position where the convex portion is detected in the cooling step,
And adjusting the plate thickness deviation by the concave portion and the convex portion to be equal to or less than the reference value,
The process of lowering the viscosity is performed by placing a heat insulating material in a widthwise position where the convex portion is detected in a region in the cooling space where the viscosity of the glass plate is in a range of 10 7.5 to 10 9.67 Poise to cool the glass plate Wherein the glass substrate for display is formed on a glass substrate. delete delete delete
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WO2017002626A1 (en) * 2015-06-30 2017-01-05 ＡｖａｎＳｔｒａｔｅ株式会社 Glass substrate production method and glass substrate production device
US20190375668A1 (en) * 2017-02-28 2019-12-12 Corning Incorporated Glass article with reduced thickness variation, method for making and apparatus therefor
JP6497407B2 (en) * 2017-03-31 2019-04-10 Ａｇｃ株式会社 Alkali-free glass substrate
WO2020005555A1 (en) 2018-06-28 2020-01-02 Corning Incorporated Continuous methods of making glass ribbon and as-drawn glass articles from the same
JP2022547308A (en) 2019-09-13 2022-11-11 コーニング インコーポレイテッド A continuous method for forming a glass ribbon using a gyrotron microwave heating device
JP2022548842A (en) * 2019-09-13 2022-11-22 コーニング インコーポレイテッド Systems and methods for forming glass ribbons using heating devices

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