JP2013212965A - Apparatus and method for treating surface of sheet glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute simply surface treatments of an end face and a rear surface of a sheet glass, and to execute inexpensively a series of surface treatments by reducing minimally the used amount of a treatment liquid at that time.SOLUTION: When applying surface treatment by a treatment liquid onto an end face Ga by supplying the treatment liquid onto the end face Ga of a sheet glass G, vaporized gas of the treatment liquid generated when supplying the treatment liquid onto the end face Ga is guided to the rear surface Gb side of the sheet glass G, to thereby apply surface treatment onto the rear surface Gb by the vaporized gas.

Description

  The present invention relates to a sheet glass surface treatment apparatus and a surface treatment method, and more particularly, to an apparatus and method for performing a surface treatment on an end surface and a back surface of a sheet glass.

  As is well known, image display devices in recent years are flat panel displays (hereinafter simply referred to as FPDs) represented by liquid crystal displays (LCDs), plasma displays (PDPs), field emission displays (FEDs), organic EL displays (OLEDs) and the like. Is the mainstream. Since weight reduction is promoted about these FPD, the request | requirement with respect to thickness reduction is also increasing about the glass substrate used for FPD.

  The glass substrate mentioned above cut | disconnects the plate-shaped glass (band-shaped plate glass) shape | molded by the strip shape by the shaping | molding method of the plate-shaped glass represented by various downdraw methods, for example to the predetermined dimension, and the width direction ( This refers to the direction parallel to the front and back surfaces of the belt-shaped plate glass and perpendicular to the longitudinal direction, hereinafter the same.) After further cutting both end portions, it is obtained by subjecting each cut surface to a polishing process, if necessary.

  By the way, when this type of glass substrate is manufactured, electrostatic charging in the manufacturing process may be a problem. That is, the glass that is an insulator has a property that is very easily charged, and in the manufacturing process of the glass substrate, for example, when the glass substrate is placed on a mounting table made of metal or an insulator and subjected to predetermined processing, The glass substrate peeled off by contact peeling between the glass substrate and the mounting table may be charged (this may be referred to as peeling charging). When a conductive object approaches the charged glass substrate, a discharge occurs, and this discharge causes damage to various elements formed on the surface of the glass substrate and electrode wires constituting the electronic circuit, or damage to the glass substrate itself. There are fears (sometimes referred to as dielectric breakdown or electrostatic breakdown). Further, the charged glass substrate is likely to stick to the mounting table, and there is a possibility that the glass substrate may be damaged by forcibly peeling it off. Since these naturally cause display defects, they should be avoided as much as possible.

  In this regard, for example, Patent Document 1 below proposes a method in which a chemical treatment is performed on the back surface by supplying a chemical solution to the back surface of the glass substrate, thereby roughening the back surface. The larger the contact area between the glass substrate and the mounting table, the greater the amount of charge when peeling, so the glass substrate can be roughened by roughening the back surface of the glass substrate in contact with the mounting surface of the mounting table. The contact area between the surface and the mounting table is reduced to suppress charging during peeling. Further, in view of the fact that a glass substrate having a smooth contact surface (back surface) is more likely to stick to a smooth surface such as a mounting surface, as described above, the glass substrate is affixed to the mounting surface by roughening the back surface. This prevents the glass substrate from being damaged during peeling.

JP 2010-275167 A JP 2007-51017 A

  On the other hand, in this type of glass substrate, the influence of deformation in the manufacturing process becomes a problem. That is, there is a concern that the glass substrate is damaged due to deformation such as local bending of the glass substrate in the manufacturing process. This type of breakage is likely to occur starting from minute defects such as scratches, scratches, and microcracks, as well as minute irregularities present on the end surface of the glass substrate. Thus, it is considered possible to improve the bending strength of the end face by removing these minute irregularities and defects.

  Here, the above-mentioned Patent Document 2 is a method in which a chemical treatment is applied to the end face by applying a chemical solution to the end face of the glass substrate, and the glass powder, polishing powder, etc. existing in the minute recesses of the end face by this treatment. A technique for improving the cleanliness of the end surface and the front and back surfaces by dissolving or washing away the foreign matter with a chemical solution is described. Therefore, for example, by using the treatment method described in Patent Document 2 and adjusting the type and concentration of the chemical solution to be used, not only the dissolution of glass powder and the like but also the outermost surface layer portion of the end surface is dissolved to smooth the end surface. It is also possible to make it.

  Therefore, when both the above-described charging suppression and damage prevention due to deformation are desired, the chemical solution is applied to the back surface and the end surface of the glass substrate by combining the method described in Patent Document 1 and the method described in Patent Document 2, respectively. It seems to be sufficient to apply a chemical treatment such as for example. However, in this case, in addition to the equipment for applying the chemical liquid to the end face, it is necessary to provide another equipment for supplying the back surface to the chemical liquid, resulting in an increase in equipment cost. In addition, as a result of performing the surface treatment using separate equipment, the work space and the number of man-hours are increased, so that it is not necessarily appropriate in terms of productivity.

  In addition, a treatment solution (chemical solution) used for this type of surface treatment is generally a treatment solution containing a component that is very polar (strongly acidic, etc.) and is designated as a poisonous and deleterious substance. Not a few. Therefore, from the viewpoint of safety and hygiene, and also from the viewpoint of processing cost, there is a technique for appropriately smoothing the end face and roughening the back face while minimizing the amount of chemical used. desired.

  In view of the above circumstances, the surface treatment on the end surface and the back surface of the sheet glass by the surface treatment is simply performed, and the above surface treatment is performed at a low cost by minimizing the amount of treatment liquid used at that time. This is a technical problem to be solved by the present invention.

  The solution of the above-mentioned problem is achieved by the surface treatment method for sheet glass according to the present invention. That is, this surface treatment method occurs when supplying a treatment liquid to the end face in a surface treatment method for a plate glass in which a treatment liquid is supplied to the end face of the plate glass to perform a surface treatment with the treatment liquid on the end face. By inducing the vaporized gas of the treatment liquid to the back side of the plate-like glass, the surface is treated with vaporized gas on the back side (claim 7).

  As described above, the present invention focuses on the vaporized gas of the processing liquid generated when the processing liquid is supplied to the end surface of the sheet glass, and uses this to perform surface treatment on the back surface of the sheet glass. It is characterized by that. That is, in the present invention, since the surface treatment of the glass sheet is performed by the vaporized gas of the processing liquid supplied to the end face, the vaporized gas of the processing liquid generated when the processing liquid is supplied to the end face is effectively used. By utilizing this, the back surface can be treated. Therefore, it is not necessary to separately provide a means for supplying the processing liquid to the back surface, and it is not necessary to newly provide a process for that purpose. Of course, compared to the case where the surface treatment is performed by supplying the treatment liquid to the back surface, the amount of the treatment liquid used can be significantly reduced, which is economical. Further, in the present invention, the surface treatment is performed on the back surface by inducing the vaporized gas of the processing liquid supplied to the end surface to the back surface side, so that the surface of the sheet glass is subjected to the surface treatment on the end surface and the back surface. However, it is possible to prevent a situation where the liquid is exposed to the vaporized gas of the treatment liquid to such an extent that the surface treatment is substantially performed. Therefore, the back surface can be appropriately roughened to suppress or prevent electrification, and the surface can be maintained with surface roughness immediately before the surface treatment (for example, during molding) to ensure high surface accuracy. It becomes.

  Furthermore, according to the present invention, the end surface of the sheet glass is subjected to a surface treatment with a treatment liquid, and the rear surface of the sheet glass is subjected to a surface treatment with a vaporized gas of the treatment liquid. Thereby, on the end face, minute irregularities and foreign matters are dissolved by the treatment liquid supplied from the treatment liquid supply unit, and foreign matters such as glass powder held in the minute depressions are washed away. Therefore, the end face can be smoothed. Moreover, since the back surface is subjected to surface treatment by exposing the back surface to the vaporized gas of the processing liquid on the back surface, even if the back surface has a relatively large supply area, the vaporized processing solution is uniformly distributed. It can be supplied and a uniform surface treatment can be applied. Therefore, it is possible to perform appropriate surface treatment on the end surface and the back surface, which require different surface properties, respectively, and to achieve smoothing of the end surface and roughening of the back surface by one surface treatment at the same time. Is possible.

  Moreover, the surface treatment method according to the present invention is applied to the back surface by the vaporized gas so that the surface roughness Ra [nm] of the back surface is improved in the range of 0.1 nm or more and 1.8 nm or less before and after the surface treatment. The surface treatment conditions may be set (claim 8).

  The surface treatment method according to the present invention prevents charging in the manufacturing process, particularly peeling charging, by roughening the back surface of the sheet glass, and even if it is charged, the charge amount at that time is substantially reduced. This is intended to keep at a problem-free level (in other words, a level at which it is not necessary to remove electricity with an ionizer after charging). In this case, the degree to which the amount of charge can remain at a level that is not substantially problematic is determined before and after the surface treatment, based on the size of the surface roughness Ra of the back surface before the standard surface treatment in this type of sheet glass. When expressed by the degree of improvement of the surface roughness Ra of the back surface, Ra ≧ 0.1 nm. Therefore, by setting the surface treatment conditions on the back surface with the vaporized gas so that the surface roughness Ra [nm] of the back surface is improved in the range of 0.1 nm or more and 1.8 nm or less before and after the surface treatment, In the manufacturing process after the surface treatment, it is possible to avoid a situation in which the sheet-like glass generates a level of charge that is substantially a problem. Examples of the surface treatment conditions on the back surface with the vaporized gas include the concentration and temperature of the treatment liquid, the atmospheric temperature, or the conveyance speed and exhaust amount of plate glass described later as influence factors. Therefore, by adjusting these influencing factors to appropriate values, the degree of improvement in the surface roughness Ra of the back surface of the sheet glass before and after the surface treatment can be controlled within the above range.

  Moreover, the solution of the above-mentioned problem is also achieved by the surface treatment apparatus for sheet glass according to the present invention. That is, this surface treatment apparatus is a plate-like glass surface treatment apparatus that includes a treatment liquid supply unit that supplies a treatment liquid to the end surface of the plate glass, and covers the periphery of the treatment liquid supply unit and the back surface of the plate glass. Characterized in that it further comprises a casing portion that covers the casing, and a guiding means that guides the vaporized gas of the processing liquid generated by vaporization of the processing liquid supplied to the end surface from the processing liquid supply portion into the gap between the casing portion and the back surface. (Claim 1).

  According to this surface treatment apparatus, similarly to the surface treatment method according to the present invention described above, the surface treatment is performed on the back surface of the sheet glass by the vaporized gas of the treatment liquid supplied to the end surface of the sheet glass. Therefore, the surface treatment can be performed on the back surface by effectively using the vaporized gas of the treatment liquid generated when the treatment liquid is supplied to the end face. Therefore, it is not necessary to separately provide a means for supplying the processing liquid to the back surface, and it is not necessary to newly provide a process for that purpose. Of course, compared to the case where the surface treatment is performed by supplying the treatment liquid to the back surface, the amount of the treatment liquid used can be significantly reduced, which is economical. Furthermore, in the present invention, since the vapor treatment gas supplied to the end surface is guided to the gap between the casing portion and the back surface, the surface treatment is performed on the back surface. While being applied, it is possible to prevent the surface of the sheet glass from being exposed to the vaporized gas of the treatment liquid to such an extent that the surface of the plate glass is substantially treated. Therefore, the back surface can be appropriately roughened to suppress or prevent electrification, and the surface can be maintained with the surface roughness just before the surface treatment to ensure high surface accuracy.

  Furthermore, according to the surface treatment apparatus according to the present invention, the end surface of the sheet glass is subjected to a surface treatment with the treatment liquid, and the rear surface of the sheet glass is subjected to a surface treatment with a vaporized gas of the treatment liquid. I did it. Thereby, on the end face, minute irregularities and foreign matters are dissolved by the treatment liquid supplied from the treatment liquid supply unit, and foreign matters such as glass powder held in the minute depressions are washed away. Therefore, the end face can be smoothed. Moreover, since the back surface is subjected to surface treatment by exposing the back surface to the vaporized gas of the processing liquid on the back surface, even if the back surface has a relatively large supply area, the vaporized processing solution is uniformly distributed. It can be supplied and a uniform surface treatment can be applied. Therefore, it is possible to perform appropriate surface treatment on the end surface and the back surface, which require different surface properties, and to achieve smoothing of the end surface and roughening of the back surface by one surface treatment at the same time. Is possible. In addition, since a gap is formed between the casing portion and the back surface, and the vaporized gas is induced in the gap, the vaporized gas of the processing liquid is supplied to the back surface without diffusing. Therefore, it is possible to ensure a gas concentration capable of surface treatment and to perform an appropriate surface treatment on the back surface.

  Further, in the surface treatment apparatus according to the present invention, the guiding means communicates the gap and the outer space of the casing part, and the vaporized gas connected to the communicating path and guided to the gap is transferred to the outer space of the casing part. It is also possible to have an exhaust device that discharges the gas.

  According to this configuration, the vaporized gas of the treatment liquid is guided to the gap between the casing portion and the back surface of the sheet glass, and the vaporized gas after being guided and subjected to the surface treatment on the back surface is introduced into the outer space of the casing portion. It can be discharged (exhaust). By exhausting in this way, the vaporized gas of the treatment liquid flows without staying in the gap between the casing part and the back surface, and is guided to the gap without interruption, so the surface treatment of the back surface with the vaporized gas Can be carried out continuously under certain conditions.

  Moreover, the surface treatment apparatus which concerns on this invention may have a 1st opening part in the location where a casing part opposes the surface of sheet glass (Claim 3).

  According to this configuration, when the vaporized gas of the processing liquid is guided to the gap between the casing portion and the back surface by the guiding means, the outside air (the casing) is provided via the first opening provided at a location facing the surface of the plate glass. Gas in the outer space of the part) can be generated in a direction in which the gas is drawn into the gap between the casing part and the back surface. Therefore, this flow can effectively suppress a situation in which the vaporized gas of the processing liquid generated when supplied to the end face flows to the surface side of the sheet glass.

  Moreover, the surface treatment apparatus according to the present invention may be configured such that the width dimension of the gap between the casing portion and the back surface of the sheet glass can be varied (Claim 5).

  According to the said structure, the volume of the clearance gap between the casing part used as the space where a back surface is exposed to the vaporization gas of a process liquid, and a back surface can be adjusted. If the volume of the gap is too large, the vaporized gas that has been guided to flow into the gap may diffuse and its concentration may decrease, but as described above, by making the width dimension of the gap variable. The volume of the gap can be adjusted to an appropriate size corresponding to a desired surface treatment level. Therefore, the surface roughness of the back surface after processing can be controlled by adjusting the level of the surface treatment for the back surface. In particular, the width dimension of the gap does not significantly affect the surface treatment level of the end surface, and mainly affects the surface treatment level of the back surface. Therefore, by adjusting the gap volume as described above, the surface treatment level of the back surface can be controlled separately from the surface treatment of the end surface.

  Further, from the same viewpoint as described above, when the guiding means according to the surface treatment apparatus of the present invention includes the exhaust device, the exhaust device is configured to be capable of adjusting the exhaust amount per unit time of the vaporized gas. (Claim 6).

  According to the above configuration, it is possible to adjust the time during which the back surface of the sheet glass is exposed to the vaporized gas of the processing liquid, that is, the time during which the surface treatment is performed by the vaporized gas, so the level of the surface treatment on the back surface is controlled. can do. In particular, the time during which the back surface is exposed to the vaporized gas does not significantly affect the surface treatment level of the end surface, as with the gap width dimension, but mainly affects the surface treatment level of the back surface. Therefore, it is possible to control the surface treatment level of the back surface separately from the surface treatment of the end surface by this means.

  Further, in the surface treatment apparatus according to the present invention, when the sheet glass is conveyed in a predetermined direction, the treatment liquid supply units are disposed on both sides in the width direction of the sheet glass, and the casing unit is disposed on both treatment liquids. While covering the circumference | surroundings of a supply part and the back surface of plate glass, it may have a 2nd opening part in the location which opposes plate glass in the conveyance direction (Claim 4). Here, the “width direction” refers to a direction orthogonal to the conveying direction of the sheet glass and along the front and back surfaces.

  According to this configuration, the surface treatment of the back surface with the vaporized gas of the treatment liquid can be simultaneously performed on the inline (conveyance line) together with the surface treatment of the end face with the treatment liquid. In addition, by adjusting the conveyance speed of the glass sheet, the time when the end surface receives supply of the processing liquid from the processing liquid supply unit and the time when the back surface is exposed to the vaporized gas of the processing liquid generated during the supply are adjusted. Can do. Therefore, it is possible to easily control the surface treatment level for the end face and the back face.

Moreover, as a plate-like glass obtained by the surface treatment method according to the above description, for example, a glass substrate having a surface treatment applied to the end surface and the back surface, the plate thickness T [mm] is 0.5 mm or less, the back surface The roughness Ra [nm] is 0.3 nm or more and 2.0 nm or less, and the bending stress σ [MPa] at the time of bending deformation along the end surface is 50 × (0.7 / T) ² A glass substrate that exceeds MPa and is less than 200 × (0.7 / T) ² MPa can be provided (claim 9).

  Alternatively, as the plate-like glass obtained by the surface treatment method according to the above description, for example, a strip-like plate glass having a surface treatment applied to the end face and the back face, the plate thickness T [mm] is 0.2 mm or less, and the back face surface Bending stress at break σ when bending deformation along the end face occurs when the roughness Ra [nm] is 0.3 nm or more and 2.0 nm or less, and the Young's modulus of the sheet glass is E [MPa]. It is possible to provide a strip-shaped plate glass having [MPa] exceeding 2.5 × (E × T) /152.4 [MPa] and less than 2.5 × (E × T) /25.4 MPa (claimed) Item 10).

  As described above, according to the present invention, the surface treatment for the end surface and the back surface of the sheet glass by the surface treatment is simply performed, and the amount of the treatment liquid used at that time is reduced as much as possible, thereby Surface treatment can be performed at low cost.

It is a perspective view which shows the whole structure of the surface treatment apparatus of the sheet glass which concerns on one Embodiment of this invention. It is a front view of the surface treatment apparatus shown in FIG. It is principal part sectional drawing which looked at the surface treatment apparatus shown in FIG. 1 from the same direction as FIG. It is a top view of the surface treatment apparatus shown in FIG. It is a side view of the surface treatment apparatus shown in FIG. It is principal part sectional drawing for demonstrating an example of the surface treatment using the surface treatment apparatus which concerns on this invention, Comprising: It is for demonstrating the flow of the vaporization gas of the process liquid generated when a process liquid is supplied to an end surface It is principal part sectional drawing. It is a top view of the surface treatment apparatus of the sheet glass concerning other embodiments of the present invention. It is a front view of the surface treatment apparatus of the sheet glass concerning other embodiments of the present invention. It is a side view of the surface treatment apparatus which shows an example in the case of performing the surface treatment which concerns on this invention with respect to the end surface and back surface of strip | belt-shaped plate glass.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. In the present embodiment, a case will be described as an example in which surface treatment is performed on the end surface and the back surface of a glass substrate cut out to a predetermined size from a formed strip-shaped plate glass as the plate-shaped glass.

  FIG. 1: has shown the perspective view of the surface treatment apparatus 10 of the sheet glass which concerns on one Embodiment of this invention. As shown in FIG. 1, the surface treatment apparatus 10 covers a periphery of the processing liquid supply unit 11 that supplies a processing liquid to the end surface Ga of the glass substrate G, and a back surface Gb of the glass substrate G. The casing part 12 to be covered and the vaporized gas of the processing liquid generated by the vaporization of the processing liquid supplied from the processing liquid supply part 11 to the end face Ga are put into a gap 13 between the casing part 12 and the back surface Gb (see FIG. 3 described later). Guidance means 14 for guiding. In this embodiment, the surface treatment apparatus 10 is disposed on an in-line including the conveyance roller 16 in a state accommodated in, for example, a chamber 15 shown in FIG.

  Here, the glass substrate G to be subjected to the surface treatment can be formed into a band shape by a known means such as a down draw method typified by an overflow down draw method or a float method. After the glass sheet (band-shaped plate glass) is cut into a predetermined longitudinal dimension, two or four sides are polished as necessary.

  Further, the composition surface of the glass substrate G is not particularly limited. For example, a glass substrate that does not substantially contain an alkali metal oxide (so-called “non-alkali glass substrate”) is preferably used. Here, “substantially no alkali metal oxide” means that the content of alkali metal oxide in the glass composition is 1000 ppm or less.

  In this embodiment, the processing liquid supply unit 11 is disposed on both sides in the width direction of the glass substrate G to be conveyed, as shown in FIG. Here, the processing liquid supply unit 11 includes, for example, a sponge rubber roller 17 impregnated with the processing liquid, a processing liquid storage tank 18 (see FIG. 2) capable of supplying the processing liquid to the roller 17, and a storage tank. A pump (not shown) that sucks the processing liquid from 18 and supplies it to the roller 17 can be used. In this case, each roller 17 comes into contact with each end face Ga in the width direction to be surface-treated as the glass substrate G is transported, so that the impregnated processing liquid can be applied to the end face Ga in the width direction position. Be placed. The roller 17 may be made of a material that can have a structure that can be impregnated with a treatment liquid, such as a foam rubber, as well as a foamed resin such as foamed polyurethane or foamed polyethylene. Of course, as long as the treatment liquid can be applied to the end face Ga, other application means such as a brush and a brush can be employed. Alternatively, if a means capable of suppressing the dispersion of the processing liquid onto the surface Gc of the glass substrate G can be provided, a spray means provided with a nozzle can be employed.

In addition, as a treatment liquid that can be supplied from the treatment liquid supply unit 11 to the end face Ga, an appropriate chemical solution can be used regardless of whether it is acidic or alkaline. For example, when melting or removing glass powder or the like in a shorter time is desired. It is possible to use an acidic solution having a higher etching ability than an alkaline solution. Specifically, an acidic solution that can be used is a mixture of one or more of HF (hydrofluoric acid), HN ₄ F (ammonium fluoride), HNO ₄ , H ₂ SO ₄ , HCl, H ₂ O ₂ . As an example. Moreover, it is preferable that the density | concentration of these fluoride solutions exists in the range of 3 weight% or more and 40 weight% or less. The above-described treatment liquid is, for example, sucked by the roller 17 from the storage tank 18 or dropped into the roller 17 and impregnated inside the glass substrate G with its concentration and temperature adjusted. Supplied to the end face Ga.

  In this embodiment, the casing portion 12 is connected to a pair of roller casing portions 19 that cover the periphery (end surface and outer peripheral surface) of the roller 17 that constitutes the processing liquid supply portion 11, and the pair of roller casing portions 19. 17 and a plate-like bottom portion 20 that forms a gap 13 having a predetermined dimension between the glass substrate G and the back surface Gb in a state where the end surface Ga is in contact with the glass substrate G. Here, the roller 17 is configured to be drivable. Moreover, the casing part 12 has the 1st opening part 21 in the location which opposes the surface Gc of the glass substrate G in the state which the roller 17 contacted the end surface Ga of the glass substrate G, as shown in FIG. At this time, the end portion including the end face Ga of the glass substrate G is covered with the roller casing portion 19. Moreover, as shown in FIG. 2, this casing part 12 has the 2nd opening part 22 in the location which opposes the glass substrate G conveyed on the conveyance roller 16, and its conveyance direction, thereby, The glass substrate G can be smoothly carried in and out of the surface treatment apparatus 10 on the in-line.

  Moreover, in this embodiment, as shown in FIGS. 1-3, the side part 23 is standingly arranged in the conveyance direction both ends of the bottom part 20, and these are in the state which the roller 17 contacted the end surface Ga of the glass substrate G. The pair of side portions 23, the bottom portion 20, and the back surface Gb of the glass substrate G form a gap 13 that substantially covers the periphery. The side portion 23 may be omitted depending on the width dimension of the gap 13. At this time, for example, the bottom portion 20 is configured to be movable relative to the roller casing portion 19 in the vertical direction, or the entire casing portion 12 including the bottom portion 20 can be moved relative to the roller 17 in the vertical direction. By configuring as above, the width dimension of the gap 13 may be variable.

  The guiding means 14 is connected to the communication path 24 that communicates the gap 13 and the outer space of the casing part 12, and is connected to the communication path 24, and discharges the vaporized gas of the processing liquid guided to the gap 13 to the outer space of the casing part 12. And an exhaust device 25. In this embodiment, the communication passage 24 is formed to open at the center in the width direction of the bottom portion 20 of the casing portion 12, thereby guiding (inflowing) the gap 13 from both sides in the width direction by the exhaust action of the exhaust device 25. The flow rate of the vaporized gas is made as uniform as possible over the entire gap 13. Further, in this embodiment, the exhaust device 25 is provided on the side wall portion of the chamber 15, and discharges the vaporized gas of the processing liquid guided to the gap 13 to the outer space of the chamber 15 through the communication path 24. ing. In addition, an air intake portion 26 is provided at the top of the chamber 15, and when the gas in the casing portion 12 (e.g., vaporized gas of the processing liquid) is discharged to the outer space of the chamber 15 by the exhaust device 25, the chamber 15. By taking outside air into the interior, the generation of negative pressure is suppressed. In this embodiment, since the first opening 21 is provided in the casing portion 12 at a location facing the surface Gc of the glass substrate G, the gas in the gap 13 is discharged out of the chamber 15 by the exhaust device 25. As a result, a gas flow is formed in which the outside air taken into the chamber 15 via the intake portion 26 flows into the gap 13 via the first opening 21. Therefore, for example, by configuring the exhaust device 25 so that the exhaust amount per unit time of the vaporized gas can be adjusted, the flow rate of the vaporized gas of the processing liquid in the gap 13 can be controlled. Further, as described above, the gas flow flowing into the gap 13 through the first opening 21 is formed, thereby preventing the vaporized gas of the processing liquid from coming into contact with the surface Gc of the glass substrate G. .

  Hereinafter, the surface treatment method of the glass substrate G using the surface treatment apparatus 10 having the above configuration will be described.

  First, as shown in FIGS. 4 and 5, the glass substrate G is transported into the chamber 15 by the transport roller 16, and the glass substrate G is rotated while the roller 17 of the processing liquid supply unit 11 disposed in the chamber 15 is rotationally driven. Then, the treatment liquid impregnated in the roller 17 is applied to the end face Ga. As a result, the treatment liquid is continuously applied to the end face Ga from the front end in the transport direction, and the surface treatment of the end face Ga with the treatment liquid is performed. At this time, a part of the processing liquid supplied from the roller 17 to the end face Ga is vaporized, so that a vaporized gas of the processing liquid is generated around the end face Ga. The vaporized gas is guided to the gap 13 between the bottom portion 20 of the casing portion 12 and the back surface Gb of the glass substrate G by the exhaust device 25, so that the back surface Gb is exposed to the vaporized gas of the processing liquid. Thereby, the back surface Gb is continuously exposed to the vaporized gas of the processing liquid from the front end in the transport direction, and the surface treatment of the back surface Gb with the vaporized gas is performed.

In this case, it is more preferable that the surface roughness Ra [nm] of the back surface Gb is improved in the range of 0.1 nm or more and 1.8 nm or less (roughening here) before and after the surface treatment. The surface treatment conditions for the back surface Gb with the vaporized gas are set so that is improved in the range of 0.1 nm or more and 0.8 nm or less. Alternatively, in the glass substrate G after the surface treatment, the bending stress σ [MPa] at the time of bending deformation along the end face Ga exceeds 50 × (0.7 / T) ² MPa and is 200 ×. Surface treatment conditions for the end face Ga by the treatment liquid are set so as to be less than (0.7 / T) ² MPa. Here, for example, the surface treatment conditions for the end face Ga and the back face Gb are appropriately adjusted not only by adjusting the concentration and temperature of the treatment liquid described above, but also by adjusting the atmospheric temperature (temperature in the chamber 15) and the conveyance speed of the glass substrate G. Is set. Further, the surface treatment condition for the back surface Gb is appropriately set by adjusting the width dimension of the gap 13 and the exhaust amount per unit time of the vaporized gas by the exhaust device 25.

The glass substrate G subjected to a series of surface treatments as described above has, for example, a plate thickness T [mm] of 0.5 mm or less, a surface roughness Ra [nm] of the back surface Gb of 0.3 nm or more, and 2. The bending stress at break σ [MPa] when bending deformation along 0 mm or less and along the end face Ga exceeds 50 × (0.7 / T) ² MPa and 200 × (0.7 / T) ² Less than MPa.

  As described above, in the present invention, the processing liquid is supplied to the end surface Ga of the glass substrate G. Therefore, the end surface Ga of the glass substrate G has a minute unevenness or the like with the processing liquid supplied from the roller 17. Foreign matters are dissolved, and foreign matters such as glass powder held in the minute recesses are washed away. Therefore, the end face Ga can be smoothed. The casing 12 covers the periphery of the roller 17 and the back surface Gb of the glass substrate G, and the vaporization gas of the processing liquid generated by the vaporization of the processing liquid supplied from the roller 17 to the end face Ga by the guiding means 14. Is guided to the gap 13 between the casing portion 12 and the back surface Gb. Thereby, the surface treatment of the back surface Gb is performed by exposing the back surface Gb to the vaporized gas of the processing liquid. Therefore, the treatment liquid in a vaporized state can be supplied uniformly over the entire back surface Gb, and uniform surface treatment can be performed. Further, since the gap 13 is formed between the casing portion 12 and the back surface Gb, and the vaporized gas is guided into the gap 13, the vaporized gas of the processing liquid is supplied to the back surface Gb without being diffused. Therefore, it is possible to ensure a gas concentration capable of surface treatment and to perform an appropriate surface treatment on the back surface Gb. In addition, in the present invention, since the back surface Gb is subjected to the surface treatment by effectively using the vaporized gas of the processing liquid generated when the processing liquid is supplied to the end face Ga, the processing liquid is supplied to the back surface Gb. There is no need to provide a separate means, and a new process is not required. Of course, compared with the case where the surface treatment is performed by supplying the treatment liquid to the back surface Gb, the amount of treatment liquid used can be significantly reduced, which is economical.

  Furthermore, in the present invention, since the vapor treatment gas supplied to the end face Ga is guided to the gap 13 between the casing portion 12 and the back face Gb to perform the surface treatment on the back face Gb, the end face Ga of the glass substrate G is used. While the surface treatment is applied to the back surface Gb, it is possible to prevent the surface Gc of the glass substrate G from being exposed to the vaporized gas of the treatment liquid to such an extent that the surface treatment is substantially performed. Therefore, the back surface Gb can be appropriately roughened to suppress or prevent charging, and the surface Gc can maintain high surface accuracy by maintaining the surface roughness immediately before the surface treatment.

  In particular, in this embodiment, the width direction end portion of the glass substrate G including the roller 17 and the end surface Ga in contact with the roller 17 is covered with the roller casing portion 19, and thus the contact portion between the roller 17 and the end surface Ga is generated. The vaporized gas of the treatment liquid can be guided to the gap 13 without leakage. Further, by providing the first opening 21 at a location facing the surface Gc of the glass substrate G in the casing portion 12, when the gas for the treatment liquid is guided to the gap 13 by the exhaust device 25, the first opening 21 is provided. A flow in a direction that draws outside air into the gap 13 can be generated through the opening 21 and the contact portion between the roller 17 and the end face Ga. Therefore, this flow can effectively suppress a situation in which the vaporized gas of the processing liquid generated when supplied to the end face Ga flows toward the surface Gc of the glass substrate G.

  Further, in this embodiment, the periphery (end surface and outer peripheral surface) of the roller 17 impregnated with the processing liquid is covered with the roller casing portion 19, and the back surface Gb of the glass substrate G with the bottom portion 20 continuous with the roller casing portion 19. Since the gap 13 having a predetermined width is formed between the surface of the roller 17 and the treatment liquid impregnated in the roller 17 (end surface and outer peripheral surface) as well as the contact portion between the roller 17 and the end surface Ga. The vaporized gas of the treatment liquid generated by vaporization can be effectively used without leakage and guided to the gap 13 between the bottom 20 and the back surface Gb. Therefore, the surface treatment of the back surface Gb with vaporized gas can be performed more effectively. This also makes it possible to more effectively suppress the flow of the vaporized gas toward the surface Gc.

  Although one embodiment of the present invention has been described above, the surface treatment apparatus or the surface treatment method according to the present invention can naturally take any form within the scope of the present invention.

  For example, in the above-described embodiment, the case where the plate-like glass surface treatment apparatus 10 including the pair of treatment liquid supply units 11 (rollers 17) is disposed inside the chamber 15 is illustrated. It is also possible to take. FIG. 7 shows an example, and a sheet glass surface treatment apparatus 10 according to the same drawing shows a pair of treatment liquid supply unit 11, casing unit 12, and guiding means 14 along the conveyance direction of glass substrate G. Arranged in a plurality of rows. In this case, first, the pair of processing liquid supply units 11, the pair of processing liquid supply units 11, the casing unit 12, and the guiding unit 14 arranged on the upstream side (right side in FIG. 7) As described above, the end surface Ga of the glass substrate G is subjected to the surface treatment with the treatment liquid, and the back surface Gb is subjected to the surface treatment with the vaporized gas of the treatment liquid. In this way, the glass substrate G on which the end surface Ga and the back surface Gb are subjected to the surface treatment is further provided with a pair of processing liquid supply units 11 and a pair of processing liquid supply units arranged on the downstream side (left side in FIG. 7). 11, the casing portion 12, and the guiding means 14 receive the surface treatment on the end face Ga with the treatment liquid and the surface treatment on the back surface Gb with the vaporized gas of the treatment liquid as described above. Accordingly, both the end face Ga and the back face Gb can be subjected to surface treatment a plurality of times in one chamber 15, so that necessary and sufficient surface treatment can be applied to the end face Ga and the back face Gb without reducing the conveyance speed of the glass substrate G. Can be applied.

  Moreover, in the said embodiment, the casing part 12 which covers the circumference | surroundings of the process liquid supply part 11 and covers the back surface Gb of the glass substrate G as a surface treatment method of plate glass is provided, and this casing part 12 and back surface Gb A case has been described in which a gap 13 having a predetermined width is provided between them, and the vaporized gas of the processing liquid is induced in the gap 13. Of course, the gap 13 may be formed between the back surface Gb other than the casing portion 12. I do not care. FIG. 8 shows an example, and the surface treatment apparatus 10 according to FIG. 8 is mainly formed by arranging a plate-shaped gap forming portion 27 at a position facing the back surface Gb of the glass substrate G. In a state where the processing liquid supply unit 11 (roller 17) and the end face Ga of the glass substrate G are in contact with each other, a gap 13 having a predetermined width can be formed between the gap forming part 27 and the back surface Gb. In addition, a pair of partitions 28 are disposed between the surface Gc of the glass substrate G excluding the end portion in the width direction and the pair of processing liquid supply units 11 (rollers 17), and contact between the rollers 17 and the end surface Ga. It is possible to suppress a situation in which the vaporized gas of the processing liquid generated around the part or the roller 17 flows into the surface Gc (quality assurance surface) side of the glass substrate G. In the illustrated example, a slit 29 extending in the transport direction is formed at the center of the gap forming portion 27 in the width direction, and an exhaust device 25 is disposed below the slit 29. Thereby, the vaporized gas of the processing liquid generated when the processing liquid is supplied from the roller 17 to the end face Ga is guided to the gap 13 between the gap forming portion 27 and the back surface Gb, and the surface treatment of the back surface Gb with the induced vaporized gas is performed. Implementation is possible.

  In the above-described embodiment, the case where the end surface Ga which is the long side of the glass substrate G is subjected to the surface treatment with the treatment liquid has been described. However, the present invention is not limited to this. For example, after the surface treatment with the treatment liquid is performed on the end surface Ga on the long side, the glass substrate G is inverted by 90 degrees to the end surface Gd on the short side of the glass substrate G (see FIG. 1 and the like). The surface treatment with the above-described treatment liquid may be performed. Further, at this time, the surface treatment (surface treatment with the vaporized gas of the treatment liquid) according to the present invention is performed on the back surface Gb only during the surface treatment of either one of the end surface Ga on the long side and the end surface Gd on the short side. Alternatively, the surface treatment with the vaporized gas may be performed on the back surface Gb during the surface treatment of both end faces Ga and Gd.

  Moreover, although the above description demonstrated the case where predetermined surface treatment was performed with respect to the end surface Ga and back surface Gb of the glass substrate G cut out from the strip-shaped plate glass, of course, this invention is applied to the end surface and back surface of a strip-shaped plate glass. Is also possible. FIG. 9 shows an example. The surface treatment apparatus 10 shown in FIG. 9 is a glass film GF (one end or both ends in FIG. The end surface Ga and the back surface Gb are illustrated at positions where the surface treatment according to the present invention can be performed. Therefore, for example, an operation of winding the glass film GF on one glass film roll GR from this state is performed, and a pair of treatments is performed on the end surface Ga of the glass film GF moving in the winding direction on the conveying roller 16 at that time. Surface treatment is performed by the liquid supply part 11, the casing part 12, and the guiding means 14. Thereby, the surface treatment with the treatment liquid can be performed on the end surface Ga of the glass film GF during the winding operation, and the surface treatment with the vaporized gas of the treatment liquid can be performed on the back surface Gb.

  At this time, before and after the surface treatment, the surface roughness Ra [nm] of the back surface Gb of the glass film GF is improved (roughened) in the range of 0.1 nm to 1.8 nm. More preferably, the surface treatment conditions for the back surface Gb with the vaporized gas are set so as to improve within a range of 0.1 nm or more and 0.8 nm or less. Alternatively, in the glass film GF after the surface treatment, when the Young's modulus of the glass film GF is E [MPa], the bending stress σ [MPa] at the time of bending deformation along the end face Ga is 2 The surface treatment conditions for the end face Ga by the treatment liquid are set so as to exceed 0.5 × (E × T) /152.4 [MPa] and less than 2.5 × (E × T) /25.4 MPa. The

  The glass film GF subjected to a series of surface treatments as described above has, for example, a plate thickness T [mm] of 0.2 mm or less and a surface roughness Ra [nm] of the back surface Gb of 0.3 nm or more and The bending stress σ [MPa] at the time of bending deformation along the end face Ga when the Young's modulus of the glass film GF is 2.0 [nm] or less is 2.5 × (E × T) /152.4 [MPa] is exceeded and less than 2.5 × (E × T) /25.4 MPa.

Five types of glass sheets (Examples 1 to 5) having different forms (glass substrates and glass films) and thicknesses are prepared, and surface treatment is performed on the end surface and the back surface using the surface treatment apparatus shown in FIG. 1 of the present invention. After that, the surface roughness of the back surface and the bending stress at breakage when bending deformation along the end surface occurred were measured. In addition, as a comparative example, six types of plate-like glasses that were not subjected to the surface treatment according to the present invention or were subjected to a surface treatment only on the end surface were prepared. The bending stress at the time of fracture due to bending deformation was measured. Hereinafter, details of each example and comparative example will be described.
Example 1
After forming into a strip shape and cutting out to a predetermined size (730 × 920 × 0.5 t unit: mm), the end surface of the alkali-free glass substrate whose end surface is ground and chamfered is impregnated with a treatment liquid described later. The glass substrate was conveyed while being in contact with a roller (made of urethane rubber), whereby the end surface was subjected to a surface treatment with a treatment liquid. Also, by providing a guiding means having one end of an exhaust duct as a communication passage connected to the casing portion and the other end connected to an exhaust device, the gas in the casing portion (vaporized gas of the processing liquid) is brought out of the chamber. It was possible to evacuate, whereby the vaporized gas of the processing liquid generated when the processing liquid was supplied to the end surface was guided to the gap between the back surface and the casing part, and the back surface was subjected to surface treatment with the vaporized gas of the processing liquid. At this time, a hydrofluoric acid (HF) aqueous solution adjusted to a liquid temperature of 30 ° C. and a concentration of 10 wt% was used as the treatment liquid. In addition, the treatment liquid can be always applied to the end surface in contact with the roller by dropping and supplying the treatment liquid to the roller at a rate of 1 ml / 1 min. Further, regarding the gap between the back surface of the glass substrate and the casing part, the width dimension is 10 mm, the transport direction dimension (opposite distance of the side part 23 in FIG. 1) is 100 mm, and the back surface by the vaporized gas of the processing liquid Processing was carried out. The above operation (surface treatment) was performed under the conditions of an atmospheric temperature of 25 ° C., a displacement of 0.5 m ³ / min, and a glass substrate transfer speed of 1 m / min.
(Example 2)
The end surface of the alkali-free glass substrate which differs only in thickness compared to Example 1 (0.3 t) was subjected to a surface treatment with a treatment liquid, and the back surface was subjected to a surface treatment with a vaporized gas of the treatment liquid. The surface treatment conditions are the same as those in Example 1 except that the conveyance speed of the glass substrate is set to 0.5 m / min.
(Example 3)
After forming into a strip shape and cutting with a carbon dioxide laser, the end surface of a non-alkali glass film (500 × 0.05 t unit: mm) wound up in a roll shape is subjected to surface treatment with a treatment solution, and the treatment solution is applied to the back surface. The surface treatment was performed using the vaporized gas. The surface treatment conditions are the same as in Example 1.
Example 4
The end surface of the alkali-free glass film that differs only in thickness compared to Example 3 (0.2 t) was subjected to a surface treatment with a treatment liquid, and the back surface was subjected to a surface treatment with a vaporized gas of the treatment liquid. The surface treatment conditions are the same as those in Example 1 except that the conveyance speed (winding speed) of the glass film is 0.5 m / min.
(Example 5)
The end surface of the same alkali-free glass film as in Example 4 was subjected to a surface treatment with a treatment liquid, and the back surface was subjected to a surface treatment with a vaporized gas of the treatment liquid. The surface treatment conditions are the same as in Example 1 except that the glass film conveyance speed is 1.5 m / min.
(Comparative Example 1)
An alkali-free glass substrate having a thickness different from that of Example 1 (0.7 t) was formed, and the surface roughness and the bending stress at break were measured without subjecting the end surface and the back surface to surface treatment.
(Comparative Example 2)
The same alkali-free glass substrate as in Example 1 was formed, and the surface roughness and the bending stress at break were measured without subjecting the end surface and the back surface to surface treatment.
(Comparative Example 3)
A surface treatment apparatus having the same configuration as in Example 1 is used except that the same alkali-free glass substrate as in Example 1 is formed and the casing part and the guiding means are not provided, and only the end surface is subjected to surface treatment with the treatment liquid. did. The surface treatment conditions are the same as in Example 1 except that the displacement is 1.0 m ³ / min.
(Comparative Example 4)
The same alkali-free glass film as in Example 3 was formed, and the surface roughness and the bending stress at break were measured without subjecting the end surface and the back surface to surface treatment.
(Comparative Example 5)
The same alkali-free glass film as in Example 4 was formed, and the surface roughness and the bending stress at break were measured without subjecting the end surface and the back surface to surface treatment.
(Comparative Example 6)
The same alkali-free glass film as in Example 3 was formed, and using the same equipment as in Comparative Example 3, only the end surface was subjected to surface treatment with the treatment liquid. The surface treatment conditions are the same as in Comparative Example 3.

Moreover, the measurement test of the bending stress at the time of the bending deformation along the end surface with respect to each test piece (Examples 1 to 5 and Comparative Examples 1 to 6) obtained as described above was performed under the following conditions. It carried out in. Each test piece was subjected to a measurement test of N = 20 (times).
(In the case of glass substrate)
A 15 × 60 strip-shaped test piece having an end surface subjected to surface treatment with a treatment liquid as a long side is cut out, and the back surface of the strip-shaped test piece is supported by a span of 45 mm. The bending stress at the time of breakage was calculated by applying a stroke load of / min (3 point bending) and measuring the load at the time when the breakage (breakage) occurred. In this case, the bending stress at break σ [MPa] is B [mm] for the width of the test piece, P [N] for the measurement load at break, h [mm] for the thickness of the test piece, and support for the test piece. When the span is L [mm], it is calculated from the following formula: σ = 3 × P × L / 2 × B × h ² .
(In the case of glass film)
With the pair of plate-shaped jigs sandwiching the folded glass film, the distance between the opposed surfaces of the pair of plate-shaped jigs is reduced at a rate of 50 mm / min. The bending stress at the time of fracture was calculated by measuring the interval. The bending stress at break σ [MPa] at this time is that the Young's modulus of the test piece is E [MPa], the thickness dimension of the test piece is T [mm], and the distance between opposing surfaces at the time of break is D [mm] It is calculated from the following formula: σ = 1.198 × (E × T) / (DT).

Table 1 shows the test results for the glass substrate, and Table 2 shows the test results for the glass film.

  First, in the case of a glass substrate, it can be seen that when no surface treatment is applied to the end face (Comparative Examples 1 and 2), sufficient bending stress at break cannot be obtained. It can also be seen that this bending stress decreases in proportion to the square of the thickness dimension. Further, even when the end surface is subjected to a surface treatment with a treatment liquid, when the vaporized gas of the treatment liquid generated when the treatment liquid is supplied is not guided to the back side of the glass substrate (Comparative Example 3). It can be seen that the vaporized gas fills the chamber and is roughened not only on the back surface but also on the front surface. On the other hand, when the surface treatment according to the present invention is performed (Examples 1 and 2), it is understood that the required bending stress at break can be obtained by smoothing the end face. Moreover, it turns out that a back surface can be roughened, maintaining the surface roughness of a surface.

  Moreover, in the case of a glass film, when no surface treatment is applied to the end face (Comparative Examples 4 and 5), sufficient bending stress at break (in this case, long-term strength required at the time of application application) It turns out that it cannot be obtained. Further, even when the end surface is subjected to a surface treatment with the treatment liquid, when the vaporized gas of the treatment liquid generated when the treatment liquid is supplied is not guided to the back side of the glass film (Comparative Example 6). It can be seen that the vaporized gas fills the chamber and is roughened not only on the back surface but also on the front surface. On the other hand, in the case where the surface treatment according to the present invention is performed (Examples 3 and 4), it is understood that the required bending stress at breakage can be obtained by smoothing the end face. Moreover, it turns out that a back surface can be roughened, maintaining the surface roughness of a surface. It can also be seen that the minimum necessary bending stress at break can be obtained even when the glass substrate transport speed, in other words, the surface treatment speed of the end face and the back face is increased (Example 5). Therefore, in this case, it can be seen that an appropriate surface treatment can be performed while greatly reducing the amount of the treatment liquid to be used.

DESCRIPTION OF SYMBOLS 10 Surface treatment apparatus 11 Process liquid supply part 12 Casing part 13 Crevice 14 Guidance means 15 Chamber 16 Conveyance roller 17 Roller 18 Storage tank 19 Roller casing part 20 Bottom part 21, 22 Opening part 23 Side part 24 Communication path 25 Exhaust device 26 Intake part 27 Gap formation part 28 Partition 29 Slit G Glass substrate Ga, Gd End surface Gb Back surface Gc Surface GF Glass film GR Glass film roll

Claims (10)

In the sheet glass surface treatment apparatus provided with the treatment liquid supply unit for supplying the treatment liquid to the end surface of the sheet glass,
A casing portion that covers the periphery of the processing liquid supply unit and covers the back surface of the plate glass,
The apparatus further comprises guiding means for guiding the vaporized gas of the processing liquid generated by vaporization of the processing liquid supplied from the processing liquid supply unit to the end surface into the gap between the casing and the back surface. Sheet glass surface treatment equipment.   The guiding means communicates the gap and the outer space of the casing part, and the exhaust device is connected to the communicating path and discharges the vaporized gas induced in the gap to the outer space of the casing part. The surface treatment apparatus of the sheet glass of Claim 1 which has these.   The surface treatment apparatus for plate glass according to claim 1, wherein the casing portion has a first opening at a position facing the surface of the plate glass. The plate glass is conveyed in a predetermined direction,
The treatment liquid supply unit is disposed on both sides in the width direction of the plate glass,
The casing according to any one of claims 1 to 3, further comprising a second opening that covers the periphery of both of the processing liquid supply units and the back surface of the sheet glass and is capable of passing the sheet glass in the transport direction. A sheet glass surface treatment apparatus according to claim 1.   The surface treatment apparatus for sheet glass according to any one of claims 1 to 4, wherein the width dimension of the gap is configured to be variable.   The surface treatment apparatus for plate glass according to claim 2, wherein the exhaust device is configured to be capable of adjusting an exhaust amount per unit time of the vaporized gas. In the surface treatment method of the plate glass, which performs surface treatment with the treatment liquid on the end face by supplying the treatment liquid to the end face of the plate glass,
A plate characterized in that a surface treatment with the vaporized gas is performed on the back surface by guiding the vaporized gas of the processing liquid generated when the processing liquid is supplied to the end surface to the back surface side of the plate glass. For surface treatment of glassy glass.   Before and after the surface treatment, conditions for surface treatment of the back surface with the vaporized gas are set so that the surface roughness Ra [nm] of the back surface is improved in a range of 0.1 nm to 1.8 nm. The surface treatment method of the sheet glass of Claim 7. A glass substrate having a surface treatment applied to the end surface and the back surface by the surface treatment method according to claim 7 or 8,
Plate thickness T [mm] is 0.5 mm or less,
The surface roughness Ra [nm] of the back surface is 0.3 nm or more and 2.0 nm or less, and the bending stress σ [MPa] at the time of bending deformation along the end surface is 50 × (0. 7 / T) exceed ² MPa and 200 × (0.7 / T) glass substrate and less than ² MPa. A strip-shaped plate glass having a surface treatment applied to the end surface and the back surface by the surface treatment method according to claim 7 or 8,
Plate thickness T [mm] is 0.2 mm or less,
When the surface roughness Ra [nm] of the back surface is 0.3 nm or more and 2.0 nm or less, and when the Young's modulus of the sheet glass is E [MPa], bending deformation occurs along the end surface The bending stress at break σ [MPa] is more than 2.5 × (E × T) /152.4 [MPa] and less than 2.5 × (E × T) /25.4 MPa. Strip glass sheet.

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