TW201615569A - Method for manufacturing glass substrate and device for manufacturing glass substrate - Google Patents

Abstract

Provided are a method for manufacturing a glass substrate, and the like, the method being capable of preventing end portions of sheet glass from separating and preventing shrinkage in a width direction of the sheet glass. The present invention is a method for manufacturing a glass substrate by overflowing molten glass from a molded body by a down-draw method and molding sheet glass. The sheet glass has a widthwise central region sandwiched between end portions in the width direction, and a pair of rollers are provided so as to be in contact with the end portions in a position opposing the end portions having a thickness greater than the plate thickness of the widthwise central region. A first cooling speed for cooling the end portions upstream of the pair of rollers from a lower end of the molded body is slower than a second cooling speed for cooling the end portions downstream of the pair of rollers in a temperature region in which the temperature of the widthwise central region is at an annealing point or higher.

Description

Method for producing glass substrate and device for manufacturing glass substrate

The present invention relates to a method for producing a glass substrate and a device for producing a glass substrate.

A method of manufacturing a TFT (Thin Film Transistor) type display using a pull-down method has been proposed. In the down-draw method, after the molten glass is poured into the molded body, the molten glass is allowed to overflow from the top of the molded body. The overflowed molten glass flows down along both side faces of the molded body and joins at the lower end portions of the molded body, thereby forming a sheet-like glass (flat glass). The flat glass is cooled while being pulled down by the stretching roller. The cooled flat glass is cut to a desired length to become a glass substrate. Patent Document 1 discloses a method in which the thickness of the flat glass is maintained to be uniform by cooling by the tensile stress acting on the width direction of the flat glass obtained by joining the lower end portions of the molded body.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2013-212987

The flat glass obtained by molding the molded body has an end portion on both sides in the width direction and a central portion in the width direction between the end portions on both sides. The thin plate having a thickness of 0.4 mm or less in the central region in the width direction of the flat glass (the region serving as the product of the glass substrate) In the glass, since the thickness of the end portion is also thin, the heat retained at the end portion is small, so that the lower end portion of the molded body is quenched, and the ends at which the lower end portions of the molded body are joined are separated from each other. On the other hand, if the amount of cooling of the flat glass at the lower end portion of the molded body is suppressed in order to prevent the end portions from being separated from each other, the viscosity of the flat glass at the lower end portion of the molded body is also increased, causing the flat glass to shrink in the width direction. After that. Therefore, it is necessary to suppress the flat glass from being contracted in the width direction while suppressing the end portions of the flat glass from being separated from each other.

Therefore, an object of the present invention is to provide a method for producing a glass substrate and a glass substrate manufacturing apparatus which can suppress the shrinkage of the flat glass in the width direction while suppressing the separation of the end portions of the flat glass.

The present invention provides the following (1) to (4).

(1) A method of producing a glass substrate according to the present invention, characterized in that the molten glass is formed into a flat glass by a down-draw method, and the flat glass is stretched while flowing downward. Cooling, thereby producing a glass substrate; and the flat glass has an end portion in the width direction and a central portion in the width direction between the end portions, and is at the end of the thickness of the plate having a thickness thicker than the central portion in the width direction a position of the opposite portion is provided to be in contact with the end portion, and a pair of rollers are provided to cool the first cooling rate from the lower end of the molded body to the end portion of the upstream of the pair of rollers. The second cooling rate for cooling the end portion of the temperature region in which the temperature in the central portion in the width direction is equal to or higher than the slow cooling point is slow.

(2) In the above (1), preferably, the viscosity of the end portion of the lower end of the molded body is less than 10 ^5.7 Poise, and the viscosity of the end portion is maintained at a viscosity corresponding to the softening point. In this manner, the end portion is cooled at the first cooling rate of less than 8.3 ° C / sec, and is cooled at the second cooling rate in the range of 8.3 ° C / sec to 17.5 ° C / sec.

(3) In the above (1) or (2), it is preferable that the thickness of the central portion in the width direction is 0.4 mm or less.

(4) Another aspect of the present invention is a method for producing a glass substrate, characterized in that a molten glass is poured from a molded body by a down-draw method to form a flat glass, and the flat glass is stretched in a downward direction. Cooling, thereby producing a glass substrate; and the flat glass has an end portion in the width direction and a central portion in the width direction between the end portions, and is thicker than the thickness of the sheet having a thickness in the central portion in the width direction The position at which the end portion faces is provided with a pair of rollers in contact with the end portion, and the first cooling rate for cooling the end portion from the lower end of the molded body from the upstream position of the pair of rollers is relatively The second cooling rate at which the temperature of the central portion in the width direction downstream of the pair of rolls and the temperature in the central portion in the width direction is equal to or higher than the slow cooling point is slow.

According to the present invention, it is possible to suppress the flat glass from shrinking in the width direction while suppressing the end portions of the flat glass from being separated from each other.

11‧‧‧ Dissolving device

12‧‧‧Clarification device

20‧‧‧ overflow chamber

23‧‧‧ upstream tube

24‧‧‧ downstream pipe

30‧‧‧Forming chamber

40‧‧‧Forming device

41‧‧‧Formed body

41a‧‧‧Bottom

41b‧‧‧ top

41c‧‧‧ side

42‧‧‧Inlet

43‧‧‧ slots

50‧‧‧ spacer components

51‧‧‧Cooling roller

60‧‧‧Temperature adjustment unit

61~63‧‧‧Central area cooling unit

64, 65‧‧‧ side cooling unit

80‧‧‧Cooling chamber

80a‧‧‧ top board

80b‧‧‧Insulation member

81a~81g‧‧‧ Pull down roller

82a~82g‧‧‧heater

90‧‧‧cutting device

91‧‧‧Control device

100‧‧‧Manufacturing device for glass substrates

380‧‧‧ thermocouple

381‧‧‧Main power switch

390‧‧‧Cooling roller drive motor

391‧‧‧ Pull-down roller drive motor

392‧‧‧cutting device drive motor

C‧‧‧ Central Department

CA‧‧‧Central Area

FG‧‧‧ molten glass

L‧‧‧ side

PG‧‧‧glass plate

R‧‧‧ side

S1‧‧‧ melting step

S2‧‧‧Clarification steps

S3‧‧‧forming steps

S4‧‧‧ Cooling step

S5‧‧‧ cutting step

S31‧‧‧First Forming Step

S32‧‧‧2nd forming step

SG‧‧ ‧ flat glass

TP1‧‧‧1st temperature distribution

TP2‧‧‧2nd temperature distribution

W‧‧‧Width

Fig. 1 is a flow chart showing a method of manufacturing a glass substrate of the present embodiment.

2 is a schematic view showing a manufacturing apparatus of a glass substrate used in a method of manufacturing a glass substrate.

Fig. 3 is a schematic view (cross-sectional view) showing a schematic view of a molding apparatus.

Fig. 4 is a schematic (side view) showing a schematic view of a molding apparatus.

Figure 5 is a control block diagram of the control device.

Fig. 6 is a view showing the temperature distribution at a specific height position of the flat glass.

Fig. 7 is a view showing an example of the cooling rate of the flat glass.

In the method for producing a glass substrate of the present embodiment, for example, a glass substrate for a TFT display in which a TFT is formed on a main surface is produced. The glass substrate is manufactured using a down-draw method. Hereinafter, a method of manufacturing a glass substrate of the present embodiment will be described with reference to the drawings.

(1) Outline of the manufacturing method of the glass substrate

First, a plurality of steps included in a method of manufacturing a glass substrate and a manufacturing apparatus 100 for a glass substrate for a plurality of steps will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, the manufacturing method of a glass substrate mainly includes the melting step S1, the clarification step S2, the molding step S3, the cooling step S4, and the cutting step S5.

The melting step S1 is a step of melting the glass raw material. After the glass raw materials are blended in such a manner as to have a desired composition, as shown in FIG. 2, they are introduced into the melting device 11 disposed upstream. The glass raw material contains, for example, a composition containing SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , CaO, SrO, BaO, or the like. Specifically, a glass raw material having a strain point of 660 ° C or higher is used. The glass raw material is melted by the melting device 11 to become molten glass FG. The melting temperature is adjusted depending on the type of glass. In the present embodiment, the glass raw material is melted at 1500 ° C to 1650 ° C. The molten glass FG is conveyed to the clarification device 12 through the upstream pipe 23.

The clarification step S2 is a step of removing bubbles in the molten glass FG. Thereafter, the molten glass FG from which the bubbles are removed in the clarification device 12 is conveyed to the forming device 40 through the downstream pipe 24.

The forming step S3 is a step of forming the molten glass FG into a sheet-shaped glass (flat glass) SG. Specifically, the molten glass FG is continuously supplied to the molded body 41 included in the molding apparatus 40, and then overflows from the molded body 41. The overflowed molten glass FG flows down the surface of the formed body 41. Thereafter, the molten glass FG is joined to the lower end portion 41a of the molded body 41 to be formed into the sheet glass SG. The flat glass SG has sides at the ends in the width direction (edges) The portion, the end portion, and the central portion in the width direction between the side portions. The plate thickness of the side portion of the flat glass SG is formed to be thicker than the plate thickness of the central portion. The central region of the sheet glass SG is a region of a product having a glass substrate having a fixed thickness. In the case where a sheet having a thickness of 0.4 mm or less is formed in the central portion of the sheet glass SG, the sheet thickness of the side portion of the sheet glass SG is formed to be thinner than before. When the thickness of the side portion of the flat glass SG is thinned, the heat retained in the side portion is reduced, and the lower end portion 41a of the molded body 41 is quenched, and the side portions at the lower end portion 41a of the molded body 41 are separated from each other. Hey. Therefore, it is necessary to control the cooling rate of the side portion of the sheet glass SG in the downstream region from the lower end portion 41a of the molded body 41.

The cooling step S4 is a step of cooling (slow cooling) the sheet glass SG. The glass sheet is cooled to a temperature close to room temperature via the cooling step S4. Further, the thickness (thickness) of the glass substrate, the amount of warpage of the glass substrate, and the amount of strain of the glass substrate are determined according to the cooling state (cooling condition) in the cooling step S4.

The cutting step S5 is a step of cutting the sheet glass SG having reached a temperature close to room temperature into a specific size.

In addition, the sheet glass SG (glass plate PG) cut into a specific size is subjected to a step of processing such as end surface processing to form a glass substrate.

Hereinafter, the configuration of the molding apparatus 40 included in the manufacturing apparatus 100 for a glass substrate will be described with reference to FIGS. 3 to 5 . In the present embodiment, the width direction of the sheet glass SG refers to a direction intersecting the direction (flow direction) in which the sheet glass SG flows down, that is, a horizontal direction.

(2) Composition of the forming device

First, the schematic configuration of the molding apparatus 40 is shown in FIGS. 3 and 4. 3 is a cross-sectional view of the forming device 40. 4 is a side view of the forming device 40.

The forming apparatus 40 has a passage through which the sheet glass SG passes and a space surrounding the passage. The space surrounding the passage includes the overflow chamber 20, the forming chamber 30, and the cooling chamber 80.

The overflow chamber 20 is a space in which the molten glass FG conveyed from the clarification device 12 is formed into a sheet glass SG.

The forming chamber 30 is disposed below the overflow chamber 20 for adjusting the thickness of the sheet glass SG and the amount of warpage. In the forming chamber 30, a portion of the cooling step S4 is performed. Specifically, in the forming chamber 30, the upstream region of the sheet glass SG is cooled (upstream region cooling step). The upstream region of the flat glass SG refers to the region of the flat glass SG where the temperature of the central portion (central region) C of the flat glass SG is higher than the slow cooling point, that is, the region of the flat glass SG shown by A1 and A2 in FIG. The center portion C of the sheet glass SG is the center in the width direction of the sheet glass SG. Specifically, the upstream region includes the first temperature region and the second temperature region. The first temperature region is a temperature region in the first molding step S31 described below, and is a temperature region from the lower end portion 41a of the molded body 41 to the upper end of the cooling roller 51 (the flat glass SG shown in A1 in Fig. 3). Area). Further, the second temperature region is a temperature region in the second molding step S32 described below, and is a temperature region from the upper end of the cooling roller 51 to the center portion C of the sheet glass SG at a slow cooling point or higher (A2 in FIG. 3). The area of the flat glass SG shown). The sheet glass SG flows down the surface of the molded body 41, and is joined to the lower end portion 41a of the molded body 41 to form the sheet glass SG. However, the temperature of the sheet glass SG is gradually lowered on the downstream side of the lower end portion 41a of the molded body 41. . Further, when the sheet glass SG (side portion) is in contact with the cooling roll 51, the temperature of the sheet glass SG is further lowered. When the sheet glass SG which joins and joins the lower end part 41a of the molded object 41 is rapidly cooled, there is a problem that the bonding is peeled off. When the sheet glass SG is in contact with the cooling roll 51, the temperature of the sheet glass SG is rapidly lowered, so that the sheet glass SG (the side portion) is not upstream of the upper end of the cooling roll 51 which is in contact with the cooling roll 51, and the sheet glass SG ( The side portion) is defined by the first temperature region and the second temperature region on the downstream side of the upper end of the cooling roller 51 that is in contact with the cooling roller 51. After passing through the forming chamber 30, the sheet glass SG passes through the cooling chamber 80 described below.

The cooling chamber 80 is disposed below the overflow chamber 20 and the forming chamber 30 for adjusting the space of the strain amount of the flat glass SG. Specifically, in the cooling chamber 80, it has been The sheet glass SG passing through the forming chamber 30 is cooled to a temperature close to room temperature by a slow cooling point and a strain point (downstream region cooling step). Further, the inside of the cooling chamber 80 is partitioned into a plurality of spaces by the heat insulating member 80b.

Further, the molding apparatus 40 mainly includes a molded body 41, a spacer member 50, a cooling roller 51, a temperature adjustment unit 60, pull-down rollers 81a to 81g, heaters 82a to 82g, and a cutting device 90. Further, the molding apparatus 40 is provided with a control device 91 (see FIG. 5). The control device 91 controls the drive units of the respective configurations included in the molding device 40.

Hereinafter, each configuration included in the molding apparatus 40 will be described in detail.

(2-1) Shaped body

The formed body 41 is disposed in the overflow chamber 20. In the molded body 41, the molten glass FG is formed into a sheet-shaped glass (flat glass SG) by overflowing the molten glass FG.

As shown in FIG. 3, the formed body 41 has a shape in which the cross-sectional shape is a substantially pentagon (similar to the shape of a wedge). The front end of the substantially pentagon corresponds to the lower end portion 41a of the formed body 41.

Further, the molded body 41 has an inflow port 42 at the first end portion (see FIG. 4). The inflow port 42 is connected to the downstream pipe 24, and the molten glass FG flowing out of the clarification device 12 flows into the molded body 41 from the inflow port 42. A groove 43 is formed in the formed body 41. The groove 43 extends along the length direction of the formed body 41. Specifically, the groove 43 extends from the first end portion to the second end portion which is an end portion on the opposite side of the first end portion. More specifically, the groove 43 extends in the left-right direction of FIG. The groove 43 is formed deep in the vicinity of the inflow port 42 and gradually becomes shallow as it approaches the second end portion. The molten glass FG that has flowed into the molded body 41 overflows from the one of the molded bodies 41 to the top portions 41b and 41b, and flows down along one of the side surfaces (surfaces) 41c and 41c along one of the molded bodies 41. Thereafter, the molten glass FG merges at the lower end portion 41a of the molded body 41 to become the sheet glass SG.

At this time, the liquidus temperature of the sheet glass SG at the lower end portion 41a of the molded body 41 is 1100 ° C or more, the liquidus viscosity is 2.5 × 10 ⁵ poise or more, more preferably, the liquidus temperature is 1160 ° C or more, and the liquid phase viscosity is 1.2 × 10 ⁵ poise or more. Further, the side portion (edge portion, end portion) of the sheet glass SG at the lower end portion 41a of the molded body 41 has a viscosity of less than 10 ^5.7 Poise.

(2-2) Spacer member

The spacer member 50 is a member that blocks heat from moving from the overflow chamber 20 to the forming chamber 30. The spacer member 50 is disposed in the vicinity of the junction point of the molten glass FG. Moreover, as shown in FIG. 3, the spacer member 50 is arrange|positioned at the both sides of the thickness direction of the molten glass FG (flat glass SG) which joins the junction point. The spacer member 50 is a heat insulating material. The partition member 50 is configured to separate the upper side environment and the lower side environment of the joining point of the molten glass FG, and the heat is blocked from moving from the upper side to the lower side of the partition member 50.

(2-3) Cooling roller

The cooling roll 51 is disposed in the forming chamber 30. More specifically, the cooling roller 51 is disposed directly under the spacer member 50. Further, the cooling rolls 51 are disposed on both sides in the thickness direction of the sheet glass SG and on both sides in the width direction of the sheet glass SG. The cooling rolls 51 disposed on both sides in the thickness direction of the sheet glass SG operate in pairs. In other words, both side portions (both ends in the width direction) of the sheet glass SG are sandwiched by the pair of cooling rolls 51, 51, .

The cooling roller 51 is air-cooled by an air cooling duct leading to the inside. The cooling roller 51 is in contact with the side portions (edge portions, end portions) R, L of the sheet glass SG (shown in the width direction of the corresponding glass sheet PG for convenience) in FIG. 3, and the flat plate is thermally conducted. The side portions (edge portions, end portions) of the glass SG are quenched by R and L (quick cooling step). The viscosity of the side portions R and L of the sheet glass SG that is in contact with the cooling roll 51 is a specific value (specifically, 10 ^9.0 poise) or more. Here, the side portions R and L of the sheet glass SG refer to the regions at both end portions in the width direction of the sheet glass SG, specifically, the edge from the width direction of the sheet glass SG toward the center portion of the sheet glass SG. C is a range of 200 mm or less in the width direction of the flat glass SG.

The cooling roller 51 is rotationally driven by a cooling roller drive motor 390 (see FIG. 5). The cooling roller 51 cools the side portions R, L of the sheet glass SG, and also has a function of pulling the sheet glass SG downward.

Further, cooling the side portions R and L of the sheet glass SG by the cooling roller 51 affects the uniformity of the width W of the sheet glass SG and the thickness of the sheet glass SG.

(2-4) Temperature adjustment unit

The temperature adjustment unit 60 is disposed in the overflow chamber 20 and in the forming chamber 30 to cool the sheet glass SG to a unit close to the slow cooling point. The temperature adjustment unit 60 is disposed at a position opposed to the lower end portion 41a of the molded body 41 and below the partition member 50 and on the top plate 80a of the cooling chamber 80.

The temperature adjustment unit 60 cools the upstream region of the sheet glass SG (upstream region cooling step). Specifically, the temperature adjustment unit 60 is configured such that the viscosity of the side portion of the sheet glass SG is maintained at a viscosity or higher corresponding to the softening point, and the flat glass is formed such that the temperature of the central portion C of the sheet glass SG approaches the slow cooling point. SG cooling. Thereafter, the center portion C of the sheet glass SG is cooled in the cooling chamber 80 described below by a slow cooling point and a strain point to a temperature close to room temperature (downstream region cooling step). Here, the softening point means that the viscosity η becomes a temperature of log η = 7.65. Further, the slow cooling point of the glass is, for example, 715.0 ° C, and the strain point is, for example, 661 ° C.

The temperature adjustment unit 60 has a plurality of cooling units 61 to 65. The plurality of cooling units 61 to 65 are arranged along the width direction of the sheet glass SG and the flow direction of the sheet glass SG. Specifically, the plurality of cooling units 61 to 65 include central region cooling units 61 to 63 and side cooling units 64 and 65. The central area cooling units 61 to 63 air-cool the central area CA of the sheet glass SG. Here, the central region of the sheet glass SG refers to the central portion in the width direction of the sheet glass SG, that is, the region including the effective width of the sheet glass SG and its vicinity. In other words, the central region of the sheet glass SG is located at a portion between the both side portions (both edge portions and both end portions) of the sheet glass SG. The central region cooling units 61 to 63 are disposed at positions facing the surface of the central region CA of the sheet glass SG along the flow direction. The units included in the central area cooling units 61 to 63 can be independently controlled. Further, the side cooling units 64 and 65 water-cool the side portions (edge portions, end portions) R and L of the sheet glass SG. The side cooling units 64 and 65 are disposed at positions facing the surfaces of the side portions R and L (both ends in the width direction) of the sheet glass SG along the flow direction. Side cooling unit The units included in 64, 65 can be independently controlled. Further, although the temperature adjustment unit 60 disposed at a position opposed to the lower end portion 41a of the molded body 41 is omitted from the boundary between the cooling units 61 to 65, the temperature adjustment unit 60 also has the above-described The cooling units 61 to 65 are configured.

(2-5) pull-down roller

The pull-down rolls 81a to 81g are disposed in the cooling chamber 80, and pull down the sheet glass SG that has passed through the forming chamber 30 toward the flow direction of the sheet glass SG. The pull-down rolls 81a to 81g are disposed inside the cooling chamber 80 at a predetermined interval in the flow direction. The pull-down rolls 81a to 81g are disposed in plural on both sides in the thickness direction of the sheet glass SG (see FIG. 3) and on both sides in the width direction of the sheet glass SG (see FIG. 4). In other words, the pull-down rollers 81a to 81g are in contact with both sides in the width direction of the sheet glass SG (both edge portions and both end portions) R and L and both sides in the thickness direction of the sheet glass SG, and the sheet glass SG faces downward. drop down.

The pull-down rolls 81a to 81g are driven by a pull-down roller drive motor 391 (see Fig. 5). Further, the pull-down rollers 81a to 81g rotate inward with respect to the sheet glass SG (downward in a portion in contact with the sheet glass SG). Regarding the peripheral speed of the pull-down rolls 81a to 81g, the lower the downstream side, the higher the peripheral speed. That is, the peripheral speed of the lower pull roller 81a among the plurality of pull-down rolls 81a to 81g is the smallest, and the peripheral speed of the pull-down roller 81g is the largest. The pull rolls 81a to 81g disposed on both sides in the thickness direction of the sheet glass SG are operated in pairs, and the pair of lower pull rolls 81a, 81a, ... pull the sheet glass SG downward.

(2-6) heater

The heaters 82a to 82g are provided inside the cooling chamber 80 to adjust the temperature of the internal space of the cooling chamber 80. Specifically, the heaters 82a to 82g are disposed in plural in the flow direction of the sheet glass SG and the width direction of the sheet glass SG. More specifically, seven heaters are arranged in the flow direction of the sheet glass SG, and three heaters are arranged in the width direction of the sheet glass. The three heaters disposed in the width direction heat-treat the side portions (edge portions, end portions) R and L of the central portion CA of the sheet glass SG and the sheet glass SG, respectively. The central portion CA includes a central portion C and is located closer to the inner side in the width direction of the flat glass SG than the both side portions (edge portions, end portions) R and L of the flat glass SG, and is in the width direction of the flat glass SG. The area from the center of the width direction of the sheet glass SG within a range of one-half of the width, for example, within 85%. The heaters 82a to 82g are controlled to be output by the following control device 91. Thereby, the ambient temperature in the vicinity of the sheet glass SG passing through the inside of the cooling chamber 80 is controlled. The temperature of the sheet glass SG is controlled by controlling the ambient temperature in the cooling chamber 80 by the heaters 82a to 82g. Moreover, by the temperature control, the flat glass SG is moved from the viscous region to the elastic region through the viscoelastic region. Thus, by the control of the heaters 82a to 82g, in the cooling chamber 80, the temperature of the sheet glass SG is cooled from a temperature close to the slow cooling point to a temperature close to room temperature (downstream region cooling step). Here, the slow cooling point has a viscosity of 10 ¹³ poise, which is 715.0 ° C here.

Further, an ambient temperature detecting means (a thermocouple in the present embodiment) 380 for detecting an ambient temperature is provided in the vicinity of each of the heaters 82a to 82g. Specifically, a plurality of thermocouples 380 are disposed in the flow direction of the sheet glass SG and the width direction of the sheet glass SG. The thermocouple 380 detects the temperature of the center portion C of the sheet glass SG and the temperatures of the side portions R and L of the sheet glass SG, respectively. The outputs of the heaters 82a-82g are controlled based on the ambient temperature detected by the thermocouple 380.

(2-7) cutting device

The cutting device 90 cuts the sheet glass SG that has been cooled to a temperature close to room temperature in the cooling chamber 80 to a specific size. The cutting device 90 cuts the sheet glass SG at specific time intervals. Thereby, the sheet glass SG becomes a plurality of glass sheets PG. The cutting device 90 is driven by a cutting device drive motor 392 (see Fig. 5).

(2-8) Control device

The control device 91 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and a hard disk. Included in 100 Various machines are controlled.

Specifically, as shown in FIG. 5, the control device 91 receives signals of various sensors (for example, thermocouple 380) or switches (for example, main power switch 381) included in the manufacturing apparatus 100 for the glass substrate, and adjusts the temperature. The unit 60, the heaters 82a to 82g, the cooling roller drive motor 390, the pull-down roller drive motor 391, the cutting device drive motor 392, and the like are controlled.

(3) Temperature management

In the method of manufacturing a glass substrate of the present embodiment, the molding step S3 includes a plurality of molding steps S31 and S32. Specifically, the first molding step S31 and the second molding step S32 are sequentially performed along the flow direction of the sheet glass SG.

Moreover, in the forming step S3, temperature management in the flow direction and the width direction of the sheet glass SG is performed. The temperature management is performed based on a plurality of temperature distributions TP1, TP2 (see Fig. 6). The temperature distributions TP1 and TP2 are temperature distributions along the width direction of the sheet glass SG regarding the ambient temperature in the vicinity of the sheet glass SG. In other words, the temperature distributions TP1, TP2 are the target temperature distributions. That is, the temperature management is performed in such a manner as to realize a plurality of temperature distributions TP1, TP2. The temperature management is performed using the above-described cooling roll 51 and temperature adjustment unit 60.

The temperature of the flat glass SG is managed by controlling the ambient temperature in the vicinity of the flat glass SG. Here, the temperature of the sheet glass SG is substantially the same as the ambient temperature controlled by the cooling roll 51 and the temperature adjusting unit 60.

Further, in each of the forming steps S31 and S32, the sheet glass SG is cooled while being formed at a specific cooling rate, and temperature management in the flow direction of the sheet glass SG is performed. Here, the specific cooling rate refers to the cooling rate corresponding to each of the forming steps S31 and S32. Specifically, the cooling rate (first cooling rate) of the first forming step among the cooling rates of the side portions (edge portions, end portions) R and L of the sheet glass SG in the forming steps S31 and S32 is smaller than that in the second forming step. The cooling rate (second cooling rate) is slow, for example, the first cooling rate is 8.3 ° C / sec or less, and the second cooling rate is 8.3 ° C / sec to 17.5 ° C / sec.

Further, in the molding step S3 of the present embodiment, the center portion C of the sheet glass SG is The cooling rate (central cooling rate) is set to be different from the cooling speed (side cooling rate) of the side portions (edge portions, end portions) R and L of the sheet glass SG. The cooling rate of the center portion is calculated based on the amount of temperature change of the center portion C of the sheet glass SG and the time required for the temperature change. The side cooling rate is calculated based on the amount of temperature change of the side portions R and L of the sheet glass SG and the time required for the temperature change.

Hereinafter, temperature management of the sheet glass SG in each of the forming steps S31 and S32 will be described in detail with reference to FIGS. 6 and 7. Figure 6 shows the temperature distribution at a particular height position of the sheet glass SG. Fig. 7 shows the cooling rate of the sheet glass SG (0.2 mm to 0.4 mm).

(3-1) First forming step

The first molding step S31 is a step of cooling the molten glass (plate glass SG) that is merged directly under the molded body 41 until the molten glass (flat glass SG) reaches the upper end of the cooling roll 51 that is not in contact with the cooling roll 51. . Specifically, in the first molding step, the side of the sheet glass SG of about 1,100 ° C to 1,200 ° C is maintained such that the viscosity of the side portions (edge portions, end portions) R and L is maintained at a viscosity or higher corresponding to the softening point. The cooling is performed at a cooling rate of 8.3 ° C /sec or less (see Fig. 7).

In the first molding step S31, temperature management of the sheet glass SG is performed based on the first temperature distribution TP1. Hereinafter, the temperature distribution TP1 executed in the first molding step S31 and the cooling rate (first cooling rate) in the first molding step will be described in detail.

(3-1-1) 1st temperature distribution

The first temperature distribution TP1 is a temperature distribution that is realized on the most upstream side of the sheet glass SG in the downstream region of the lower end portion 41a of the molded body 41 (see FIG. 6). In the first temperature distribution TP1, the temperature of the central region CA of the sheet glass SG is uniform, and the side portions R and L of the sheet glass SG are lower than the central portion CA of the sheet glass SG. Here, the uniform temperature of the central region CA means that the temperature of the central region CA is included in a specific temperature region. The specific temperature range is the range of the reference temperature ± 20 ° C. The reference temperature is the average temperature in the width direction of the central area CA.

The first temperature distribution TP1 is achieved by controlling the temperature adjustment unit 60 in the overflow chamber 20 and in the forming chamber 30. Specifically, the side portions R and L of the sheet glass SG are cooled by the temperature adjustment unit 60 (the side cooling units 64 and 65). The temperature of the side portions R and L of the sheet glass SG is cooled to a temperature lower than the temperature of the central portion CA by a specific temperature. In the first temperature distribution TP1, the thickness of the central region CA is made uniform, and the thickness of the central region CA of the sheet glass SG is made uniform. Further, by further cooling the side portions R and L of the sheet glass SG compared to the central region CA, the side portions R and L of the sheet glass SG have a higher viscosity than the central portion CA. This is because if the viscosity of the side portions R and L of the sheet glass SG is higher than that of the central portion CA, it is possible to suppress the sheet glass SG from shrinking in the width direction. Further, in the first temperature distribution TP1, the side portions R and L of the sheet glass SG are cooled more slowly than the second temperature distribution TP2. By suppressing the amount of cooling of the side portions R and L of the sheet glass SG, it is possible to prevent the side portions R and L which are joined and bonded to the lower end portion 41a of the molded article 41 from being peeled off and separated.

The first center portion cooling rate in the first molding step S31 is 5.0 ° C / sec to 50.0 ° C / sec. If the cooling rate is lower than 5.0 ° C / sec, the productivity is deteriorated. If the cooling rate exceeds 50 ° C / sec, there is a case where the sheet glass SG is broken. Further, the warpage value and the plate thickness deviation of the sheet glass SG are deteriorated. Preferably, the central portion cooling rate in the first molding step S31 is 8.0 ° C / sec to 16.5 ° C / sec. Moreover, the first cooling rate in the first molding step S31 is 8.3 ° C / sec or less.

(3-2) Second forming step

In the second molding step S32, the sheet glass SG having the viscosity of the side portions (edge portions, end portions) R and L maintained at a viscosity corresponding to the softening point is cooled until the temperature at which the sheet glass SG reaches the central region CA becomes a slow cooling point. The steps up to the above temperature range (see Fig. 7). Specifically, in the second molding step S32, the side portions R and L are cooled at a cooling rate of 8.3 ° C such that the side portions (edge portions, end portions) R and L of the sheet glass SG have a viscosity of 10 ^9.0 poise or more. Cool down in the range of / sec to 17.5 ° C / sec (see Figure 7).

In the second molding step S32, the sheet glass SG is performed based on the second temperature distribution TP2. Temperature management. Hereinafter, the temperature distribution TP2 executed in the second molding step S32 and the cooling rate (second cooling rate) in the second molding step will be described in detail.

(3-2-1) second temperature distribution

The second temperature distribution TP2 is a temperature distribution which is realized on the downstream side of the upper end of the cooling roll 51 which is in contact with the flat glass SG and the cooling roll 51 (refer to FIG. 6). Similarly to the first temperature distribution TP1, the second temperature distribution TP2 has a uniform temperature in the central region CA of the sheet glass SG, and the temperatures of the side portions R and L of the sheet glass SG are lower than the central region CA of the sheet glass SG.

The second temperature distribution TP2 is achieved by controlling the temperature adjustment unit 60 in the forming chamber 30. Specifically, the side portions R and L of the sheet glass SG are cooled by the temperature adjustment unit 60 (the side cooling units 64 and 65). The temperature of the side portions R and L of the sheet glass SG is cooled to a temperature lower than the temperature of the central portion CA by a specific temperature. In the second temperature distribution TP2, the temperature of the central area CA is made uniform. Moreover, the amount of cooling of the side portions R, L of the cooling plate glass SG is made larger than that of the central region CA. When the viscosity of the side portions R and L of the sheet glass SG is higher than the central portion CA, it is possible to suppress the sheet glass SG from contracting in the width direction. Further, in the second temperature distribution TP2, the side portions R and L of the sheet glass SG are cooled at a cooling rate faster than the cooling rates of the side portions R and L in the first temperature distribution TP1. By increasing the amount of cooling of the side portions R and L of the sheet glass SG, the viscosity of the side portions R and L is increased, and the sheet glass SG can be prevented from shrinking in the width direction.

The second center portion cooling rate in the second molding step S32 is 5.0 ° C / sec to 50.0 ° C / sec. If the cooling rate is lower than 5.0 ° C / sec, the productivity is deteriorated. If the cooling rate exceeds 50 ° C / sec, there is a case where the sheet glass SG is broken. Further, the warpage value and the plate thickness deviation of the sheet glass SG are deteriorated. Preferably, the central portion cooling rate in the second molding step S32 is 8.0 ° C / sec to 16.5 ° C / sec. Further, the second cooling rate in the second molding step S32 is 5.5 ° C / sec to 52.0 ° C / sec. Preferably, the second cooling rate is 8.3 ° C / sec to 17.5 ° C / sec.

Further, in the first temperature distribution TP1 and the second temperature distribution TP2, the temperature of the central portion C of the central region CA may be the highest and the temperatures of the edge portions R and L may be the lowest. The center portion C forms a gradient (temperature gradient) toward the edge portions R, L. In other words, the first temperature distribution TP1 and the second temperature distribution TP2 may also form a gentle parabola having a convex portion above. Here, the temperature gradient means that the value obtained by dividing the ambient temperature of the center portion C by the ambient temperature of the edge portions R and L by the width W of the sheet glass SG (for example, 1650 mm, see FIG. 6) divided by 2 is obtained. The result ((the ambient temperature of the center portion C - the ambient temperature of the edge portions R, L) / (the width of the flat glass W/2)).

In the present embodiment, the temperature from the lower end portion 41a of the molded body 41 to the upper end of the cooling roll 51 and the temperature from the upper end of the cooling roll 51 to the center portion C of the sheet glass SG become a slow cooling point or higher. In the second temperature region, the cooling rate of the side portions (edge portions, end portions) R, L of the sheet glass SG in the first temperature region is higher than the side portion (edge portion, end portion) of the sheet glass SG in the second temperature region. Part) The cooling rate of R and L is slow. In the vicinity of the lower end portion 41a of the molded body 41 having a high temperature at the side portion of the sheet glass SG, the cooling rate of the end portion is slowed to prevent quenching, whereby the end portions where the joining and bonding are suppressed from being peeled off from each other can be suppressed, and the cooling rolls are cooled. On the downstream side of 51, the cooling rate of the end portion is increased to quench the end portion, whereby the flat glass SG can be suppressed from contracting in the width direction.

[Examples]

Hereinafter, the present invention will be described in more detail by way of examples. Furthermore, the invention is not limited to the following examples.

(Example 1)

Using the glass substrate manufacturing apparatus 100 and the glass substrate manufacturing method, the glass substrate was manufactured under the following conditions. In the composition (% by mass) of the glass, the content of each component is 60% SiO ₂ , 17% Al ₂ O ₃ , 10% B ₂ O ₃ , 3% CaO, 3% SrO, and 1%. BaO. The liquid phase temperature of the glass is 1,100 ° C, and the liquid viscosity is 2.5 × 10 ⁵ poise. The slow cooling point of the glass is 715.0 ° C and the strain point is 661 ° C. Further, the width of the flat glass SG is 1600 mm. Further, the sheet glass SG having different thicknesses (0.2 mm, 0.3 mm, 0.4 mm) was produced while satisfying the above conditions.

The first cooling rate in the first molding step S31 and the second cooling rate in the second molding step S32 are changed, and the presence or absence of peeling of the side portions R and L is visually confirmed. The first molding step S31 has a shape of 0.4 mm. The side portions (edge portions, end portions) R and L of the sheet glass SG at the time of the plate glass SG having a thickness of 0.3 mm and 0.2 mm are cooled. The results are shown in Table 1.

As shown in Table 1, the first cooling rate was set to less than 8.3 ° C / sec and the second cooling rate was set to 8.3 ° C / sec to 17.5 ° C / sec, even if the plate thickness was 0.2 to 0.4 mm. The glass SG also prevents side peeling. On the other hand, when the first cooling rate was much faster than the second cooling rate (Comparative Examples 1 to 9), peeling of the side portion occurred. Again, at the first cooling rate In the case of the second cooling rate, when the first cooling rate is 8.3 ° C / sec or more (Examples 5, 10, 15) or the second cooling rate is less than 8.3 ° C / sec (Examples 4, 9, 14), peeling occurs in one of the side portions. In this case, peeling occurred in one of the side portions, but since it was not completely peeled off as shown in the comparative example, peeling did not occur in the product region of the glass substrate, thereby overcoming the previous problems. According to the above, it can be confirmed that the side portions are separated from each other even if the first cooling rate is lower than the second cooling rate.

According to the above results, it is confirmed that the first cooling rate for cooling the side portions R and L which are started from the lower end 41a of the molded body 41 and upstream of the pair of cooling rolls 51 is less than 8.3 ° C / sec, and The second cooling rate for cooling the side portions R and L in the temperature region in which the temperature in the central portion C of the flat glass SG in the width direction is lower than the pair of cooling rolls 51 is 8.3 ° C / sec to 17.5 ° C / sec, and it is better to prevent side peeling.

The present embodiment has been described above with reference to the drawings. However, the specific configuration is not limited to the above-described embodiments, and modifications may be made without departing from the spirit and scope of the invention.

20‧‧‧ overflow chamber

30‧‧‧Forming chamber

C‧‧‧ Central Department

CA‧‧‧Central Area

L‧‧‧ side

R‧‧‧ side

S31‧‧‧First Forming Step

S32‧‧‧2nd forming step

TP1‧‧‧1st temperature distribution

TP2‧‧‧2nd temperature distribution

W‧‧‧Width

Claims (5)

A method for producing a glass substrate, which is characterized in that a molten glass is poured from a molded body by a down-draw method to form a flat glass, and the flat glass is cooled while being drawn downward, thereby producing a glass substrate; The flat glass has an end portion in the width direction and a central portion in the width direction between the end portions, and is opposed to the end portion having a thickness thicker than the thickness of the central portion in the width direction, and the end portion The first contact cooling method is configured to include a pair of rollers, and the first cooling rate for cooling the end portion from the lower end of the molded body from the upstream position of the pair of rollers is downstream of the pair of rollers and the central portion in the width direction The second cooling rate at which the end portion of the temperature region in which the temperature becomes the slow cooling point is cooled is slow. The method for producing a glass substrate according to claim 1, wherein the viscosity of the end portion of the lower end of the molded body is set to be less than 10 ^5.7 Poise, and the viscosity of the end portion of the lower end of the molded body is maintained at a softening point. The end portion is cooled at a first cooling rate of less than 8.3 ° C / sec, and is cooled at the second cooling rate in the range of 8.3 ° C / sec to 17.5 ° C / sec. The method for producing a glass substrate according to claim 1 or 2, wherein the thickness of the central portion in the width direction is 0.4 mm or less. The method for producing a glass substrate according to any one of claims 1 to 3, wherein the viscosity of the central portion in the width direction of the lower end of the molded body is set to be 120000 Poise or less. A manufacturing device for a glass substrate, characterized in that: The molten glass is formed into a flat glass by a down-draw method, and the flat glass is cooled while being stretched in a downward direction to produce a glass substrate; and the flat glass has an end portion in the width direction and is located above a central portion in the width direction between the end portions, and a pair of rollers are provided in contact with the end portion at a position opposed to the end portion having a thickness thicker than the thickness in the central portion in the width direction, and a first cooling rate for cooling from the lower end of the molded body from the upstream end of the pair of rolls is lower than a temperature range of the downstream of the pair of rolls and the temperature of the central portion in the width direction becomes a slow cooling point or higher The second cooling rate at which the end portion is cooled is slow.