Glass plate for chemical strengthening, method for manufacturing strengthened glass plate, and glass plate

Abstract

A glass plate 12 for chemical reinforcement, having the thickness of 0.1 mm or less, is formed in an overall warped shape or is provided with a portion that is partially warped. When the glass plate 12 is placed on a horizontal plane with one main surface 12a thereof being oriented upward, and a position in the glass plate 12 at which the height from the horizontal plane is the highest is denoted as a first peak position D1, and a 10 mm-width portion of the glass plate 12 along the peripheral edge thereof is denoted as a peripheral edge section 12e, the first peak position D1 is present in a portion further inward than the peripheral edge section 12e of the glass plate 12.

Description

[Technical Field]

[0001] The present disclosure relates to a glass sheet for chemical strengthening (an ion-exchangeable glass sheet), a method for producing a strengthened glass sheet from the glass sheet, and the glass sheet. [Background technology]

[0002] In recent years, the screens of portable electronic devices such as smartphones and tablet PCs have become larger. However, increasing the screen size increases the overall size of the device, making it less portable. Therefore, foldable devices have been proposed to combine large screens with good portability.

[0003] The cover glass used in such foldable devices needs to be thinner than conventional ones so that it can be bent, and for example, an ultra-thin tempered glass plate is used as disclosed in Patent Document 1. The tempered glass plate is manufactured from an ultra-thin glass plate for chemical strengthening (for example, a thickness of 0.1 mm or less). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-188360 Summary of the Invention [Problem to be solved by the invention]

[0005] Before being made into a tempered glass sheet, the above-mentioned glass sheet for chemical strengthening undergoes various manufacturing processes, such as a cleaning process for cleaning the surface and a cutting process for cutting into product sizes. During these processes, the glass sheet warps more due to its thinness. Because the warp of a glass sheet is inversely proportional to the square of the thickness, the warp becomes more pronounced when the thickness is 0.1 mm or less, further 0.05 mm or less, or even 0.04 mm or less, making handling and transportation more difficult. Here, the thinner the tempered glass sheet to be manufactured, the greater the difference in thickness between the glass pool portions at the widthwise ends of the glass ribbon and the effective portion (including the portion that will later become the product) at the widthwise center during the forming process of the glass sheet for chemical strengthening, which is the source of the tempered glass sheet. Therefore, when attempting to manufacture an ultrathin glass sheet having a uniform thickness across the entire width of the effective portion, discontinuous wavy warpage is likely to occur near both ends of the effective portion in the width direction when adjusting the forming conditions such as the temperature distribution, making it difficult to manufacture a flat glass sheet with uniformly little warpage. Furthermore, there has been a problem in that the glass sheet is prone to breakage during the manufacturing process due to the warpage present in the glass sheet during or after forming.

[0006] Here are some examples of how such ultra-thin glass plates for chemical strengthening may break. For example, glass plates for chemical strengthening used as cover glass for foldable devices are preferably formed by the overflow downdraw method. In this case, since the glass plate is continuously formed, after the melting, forming, and annealing processes, relatively thick glass pools are present at both ends of the glass ribbon in the width direction. The non-useful portion (a portion that is not used as a product and is discarded) including this glass pool is then cut and removed using a cutting method such as diamond scribing or laser scribing, leaving behind the above-mentioned useful portion with a relatively uniform thickness. However, as described above, if warping exists near both ends of the width direction of the useful portion, the scribe will not be uniform when cutting and removing the non-useful portion, which may cause unintended breakage in the useful portion.

[0007] Another example of a mode in which an ultrathin glass plate for chemical strengthening may break is when a glass plate cut from a glass ribbon is adsorbed or placed on a flat plate such as a surface plate, and then cut to a desired size, and breakage occurs from a partially unadsorbed portion (a raised portion) due to warping. Another example of a mode in which a glass plate for chemical strengthening may break is when a glass plate for chemical strengthening is cleaned while being transported, and the warp added in combination with the deflection of the glass plate causes the glass plate to get caught on a cleaning brush or a transport roller, or the edge of the glass plate sags and gets into a gap between adjacent transport rollers.

[0008] In view of the above circumstances, a technical problem to be solved is to prevent, as much as possible, breakage of glass plates, including ultra-thin glass plates for chemical strengthening, during the manufacturing process due to warping. [Means for solving the problem]

[0009] As a result of extensive research, the inventors have obtained the following findings (A) and (B). (A) In an ultra-thin glass plate for chemical strengthening, such as one having a thickness of 0.1 mm or less, it is extremely difficult to prevent warping itself. (B) Although the occurrence of warping itself cannot be prevented, if, when a glass plate is placed on a horizontal surface, the position of the warp that is highest from the horizontal surface (the warp that protrudes most upward) contained in the glass plate is located in a position farther inward from the periphery of the glass plate, breakage of the glass plate during the manufacturing process can be avoided as much as possible.

[0010] Based on the above findings, a glass plate for solving the above problems is a glass plate for chemical strengthening having a thickness including warpage of 0.1 mm or less, characterized in that a first peak position is present in a region of the glass plate that is more inward than the peripheral edge thereof, under the following conditions (1) to (8): (1) The thickness of the glass plate is t [mm]. (2) When the glass plate is placed on a horizontal surface with one main surface facing up in a first placement configuration, the position of the glass plate that is highest above the horizontal surface is defined as the first peak position. (3) The height of the glass plate from the horizontal plane at the first peak position is W 1MAX [mm]. (4) When the second mounting configuration is adopted in which the glass plate is placed on a horizontal surface with the other main surface on the back side of the one main surface facing up, the second peak position is the position of the glass plate that is highest above the horizontal surface. (5) The height of the glass plate from the horizontal plane at the second peak position is W 2MAX [mm]. (6) The 10 mm wide area along the periphery of the glass plate is defined as the periphery. (7) When the first mounting configuration is adopted, the height of the highest position from the horizontal plane within the peripheral portion is defined as W 1OUT [mm]. (8) When the second mounting configuration is adopted, the height of the highest position from the horizontal plane within the peripheral portion is defined as W 2OUT [mm].

[0011] In this glass plate, the first peak position is located in a region inside the peripheral edge of the glass plate. The first peak position is a position corresponding to the apex of the warp having the highest height from the horizontal plane (the warp that protrudes most upward) among the warps contained in the glass plate under the first mounting configuration. Therefore, when the first peak position is located in a region inside the peripheral edge, the position of the warp having the highest height from the horizontal plane is located in a region farther inward from the peripheral edge of the glass plate. This makes it possible to prevent breakage of the glass plate during the manufacturing process as much as possible. In another embodiment of the present invention, for example, a region having a width of 20 mm along the peripheral edge of the glass plate may be set as the peripheral edge, or a region having a width of 30 mm may be set as the peripheral edge. When the width of the peripheral edge is changed in this manner, the width of the peripheral edge of the glass plate is preferably within a range of, for example, 10 mm to 50 mm.

[0012] In the glass plate above, t 2 / W 1OUT It is preferable that the relationship of W > 0.005 is satisfied. 1OUT It is preferable that the relationship W≦0.20 mm is satisfied. 1OUT It is preferable that the relationship / t<5 is satisfied.

[0013] As a result of extensive research, the inventors have obtained the following finding (C). (C) Regarding the warp present in the peripheral portion under the first mounting configuration, the higher the height from the horizontal plane (the dimension of the upward protrusion), the more likely the glass sheet is to be broken during the manufacturing process. 1OUT The larger the value, the more likely the glass plate is to break. Furthermore, the thinner the glass plate, the more likely it is to bend at the edges during the manufacturing process, making the glass plate more susceptible to breakage. The magnitude of the bending is inversely proportional to the square of the thickness of the glass plate. 1OUT The smaller the value of , the smaller the value of t and t 2 The smaller the value of W 1OUT If the value of is small, it is advantageous in avoiding breakage of the glass sheet. If the above relationship is satisfied, breakage of the glass sheet can be more suitably avoided.

[0014] In the above glass plate, W 1MAX It is preferable that the relationship / t<15 is satisfied.

[0015] To avoid breakage, the thinner the glass plate, the greater the W 1MAXIt is advantageous that the value of (corresponding to the height of the apex of the warp that is highest from the horizontal plane in the first mounting configuration) is small. If the above relationship is satisfied, breakage of the glass sheet can be more effectively avoided. Furthermore, if the above relationship is satisfied, the glass sheet is also suitable for various processes in post-processes for producing a tempered glass sheet from the glass sheet, such as laminating the glass sheet or cutting it into small pieces individually, or post-processing processes such as polishing the edge surface of the peripheral portion or chemical treatment. Reducing the overall warp of the glass sheet for chemical tempering is also advantageous in preventing deformation such as warpage or unevenness beyond the allowable range from occurring in a tempered glass sheet produced from the glass sheet.

[0016] In the above-described glass sheet, one main surface and the other main surface may be fire-polished. In other words, the glass sheet may not have been subjected to a polishing treatment (e.g., a chemical polishing treatment such as a slimming treatment to reduce thickness) on the front and back surfaces after forming. Alternatively, an ultrathin glass sheet for chemical strengthening may be obtained by chemically slimming (reducing the thickness) a relatively thick glass sheet (e.g., greater than 0.1 mm to 0.4 mm) using a glass-corrosive chemical such as hydrofluoric acid. In this case, it is difficult to achieve a uniform thickness reduction in the slimming process, and it is difficult to obtain a uniform thickness in the resulting glass sheet, which may result in a large variation in thickness or induce warping of the resulting glass sheet. Such thickness variation and warping further exacerbate the warping in the subsequent tempering process and induce surface irregularities. Therefore, directly forming an ultrathin glass sheet for chemical strengthening is highly advantageous for obtaining a flatter glass sheet.

[0017] The glass plate may have a thickness of 0.05 mm or less. The glass plate may have a substantially uniform thickness throughout. Even with such an extremely thin glass plate, breakage of the glass plate during the manufacturing process can be minimized.

[0018] In the glass plate, the second peak position is preferably present in a region on the inside of the peripheral edge of the glass plate.

[0019] As described above, if not only the first peak position is located in a region inside the peripheral edge of the glass sheet, but also the second peak position is located in a region inside, it is more advantageous in avoiding breakage of the glass sheet during the manufacturing process. In this case, for example, it is more advantageous in preventing the peripheral edge of the glass sheet from being caught on the conveying rollers when the glass sheet is conveyed by the conveying rollers.

[0020] In the glass plate above, t 2 / W 2OUT It is preferable that the relationship of W > 0.005 is satisfied. 2OUT It is preferable that the relationship W≦0.20 mm is satisfied. 2OUT It is preferable that the relationship of W / t<5 is satisfied. 2MAX It is preferable that the relationship / t<15 is satisfied.

[0021] If these relationships are satisfied, then, as mentioned above, t 2 / W 1OUT >0.005, W 1OUT ≦0.20mm, W 1OUT / t<5 and W 1MAX For the same reasons as explained above regarding the desirability of satisfying the relationships / t<15, breakage of the glass plate can be more suitably avoided.

[0022] The glass plate may be an aluminosilicate glass, and may contain, in mass %, 50 to 80% SiO2, 5 to 25% Al2O3, 0 to 15% B2O3, 1 to 20% Na2O, and 0 to 10% K2O as a glass composition.

[0023] The glass plate may be an aluminosilicate glass, and may contain, in mass %, 60 to 80% of SiO2, 8 to 20% of Al2O3, 0 to 5% of B2O3, 4 to 16% of Na2O, and 0.01 to 10% of K2O as a glass composition.

[0024] The glass plate may be rectangular and have a size of 150 mm×150 mm to 1100 mm×1300 mm.

[0025] The effect of the above-mentioned glass plate (the effect of being able to avoid breakage as much as possible) is not only obtained in the cutting process and cleaning process after molding, or when the glass plate is transported during these processes, but also in the process of cutting to the desired size before chemical strengthening to obtain cover glass for foldable devices, the process of film formation, or post-processing processes in which the glass plate is laminated or the peripheral edge surfaces are polished or chemically treated individually.

[0026] The glass plate for chemical strengthening of the present invention may include an embodiment in which the warpage peak is not present in the peripheral portion, particularly near the corners. Specifically, another embodiment of the glass plate for chemical strengthening of the present invention is a glass plate for chemical strengthening having a thickness of 0.1 mm or less, which has an overall warped shape or a partially warped portion, and when the glass plate is placed on a horizontal surface with one main surface facing up in a first mounting configuration, the position of the glass plate that is highest from the horizontal surface is set as a first peak position, and the first peak position is preferably present in a portion of the glass plate outside a region within a radius of 10 mm from the corner.

[0027] In this configuration, when a second mounting configuration is adopted in which the glass plate is placed on the horizontal plane with the other main surface on the back side of the one main surface facing up, it is preferable that the position of the glass plate that is highest from the horizontal plane be set as a second peak position, and that the second peak position be located at a position outside a region with a radius of 10 mm from the corner of the glass plate.

[0028] Furthermore, a method for producing a tempered glass plate of the present invention includes a preparation step of preparing the above-mentioned glass plate for chemical tempering, a cutting step of cutting a glass plate of product size from the glass plate, and a tempering step of chemically tempering the glass plate of product size to obtain a tempered glass plate. According to such a method for producing a tempered glass plate, it is easy to prevent the produced tempered glass plate from warping beyond an allowable range.

[0029] Furthermore, the present invention is also applicable to glass plates other than those intended for chemical strengthening. That is, a glass plate other than a glass plate for chemical strengthening has a thickness of 0.1 mm or less, is warped overall or has a partially warped portion, and is characterized in that, when the glass plate is placed on a horizontal surface with one main surface facing up in a first mounting configuration, the position of the glass plate that is highest from the horizontal surface is defined as a first peak position, and a 10 mm-wide portion along the periphery of the glass plate is defined as a peripheral portion, the first peak position is located in a portion of the glass plate that is more inward than the peripheral portion.

[0030] In this glass plate, when a second mounting configuration is adopted in which the glass plate is placed on the horizontal plane with the other main surface on the back side of the one main surface facing up, and the position of the glass plate that is highest from the horizontal plane is defined as a second peak position, the second peak position may be located in a portion of the glass plate that is more inward than the peripheral edge portion.

[0031] The other configurations and properties of the glass plates other than the glass plate for chemical strengthening are the same as the configurations and properties of the glass plate for chemical strengthening already described. Therefore, the glass plate here may be used as a glass plate for chemical strengthening. [Effects of the Invention]

[0032] According to a glass plate including a glass plate for chemical strengthening according to the present disclosure, it is possible to avoid breakage during the manufacturing process due to warping as much as possible. [Brief explanation of the drawings]

[0033] [Figure 1] FIG. 2 is a cross-sectional view showing a preparation step in a method for manufacturing a strengthened glass sheet. [Figure 2] FIG. 2 is a cross-sectional view showing a preparation step in a method for manufacturing a strengthened glass sheet. [Figure 3] FIG. 1 is a plan view showing a glass plate for chemical strengthening. [Figure 4] FIG. 1 is a plan view showing a glass plate for chemical strengthening. [Figure 5] FIG. 10 is a diagram showing the distribution of warpage at Y=105 when the first mounting configuration is adopted in Example 5. [Figure 6] FIG. 20 is a diagram showing the warpage distribution when the first mounting configuration is adopted in Example 14. [Figure 7] FIG. 13 is a diagram showing the distribution of warpage at Y=55 when the first mounting configuration is adopted in Example 14. [Figure 8] FIG. 13 is a diagram showing the warpage distribution when the second mounting configuration is adopted in Example 14. [Figure 9] FIG. 16 is a diagram showing the warpage distribution when the first mounting configuration is adopted in Example 15. [Figure 10] FIG. 16 is a diagram showing the warpage distribution when the second mounting configuration is adopted in Example 15. [Figure 11] FIG. 20 is a diagram showing the warpage distribution when the first mounting configuration is adopted in Example 16. [Figure 12] FIG. 13 is a diagram showing the warpage distribution when the second mounting configuration is adopted in Example 16. [Figure 13] FIG. 13 is a diagram showing the warpage distribution when the first mounting configuration is adopted in Example 17. [Figure 14] FIG. 13 is a diagram showing the warpage distribution when the second mounting configuration is adopted in Example 17. [Figure 15] FIG. 20 is a diagram showing the warpage distribution when the first mounting configuration is adopted in Example 18. [Figure 16] FIG. 13 is a diagram showing the warpage distribution when the second mounting configuration is adopted in Example 18. [Figure 17] FIG. 10 is a diagram showing the warpage distribution when the first mounting configuration is adopted in Comparative Example 4. [Figure 18]FIG. 10 is a diagram showing the warpage distribution when the second mounting configuration is adopted in Comparative Example 4. [Figure 19] FIG. 20 is a diagram showing the warpage distribution when the first mounting configuration is adopted in Example 19. [Figure 20] FIG. 20 is a diagram showing the warpage distribution when the second mounting configuration is adopted in Example 19. DETAILED DESCRIPTION OF THE INVENTION

[0034] Hereinafter, a glass plate for chemical strengthening and a method for manufacturing a strengthened glass plate according to an embodiment will be described with reference to the accompanying drawings.

[0035] The method for manufacturing a tempered glass plate includes a preparation step of preparing a glass plate for chemical tempering, a cutting step of cutting a glass plate of product size from the prepared glass plate, and a tempering step of chemically tempering the cut glass plate of product size to obtain a tempered glass plate.

[0036] [Preparation process] The glass sheet for chemical strengthening according to this embodiment is manufactured by a known forming method involving sheet drawing, such as a downdraw method (e.g., overflow downdraw, slot downdraw, or redraw), or a float method. The overflow downdraw method has the advantage that both the front and back surfaces of the formed glass ribbon are formed without contacting any part of the forming body during the forming process, resulting in a very smooth, fire-polished surface with a very flat surface texture due to appropriate temperature control. In particular, for ultra-thin tempered glass sheets, scratches on the glass surface during bending can become fracture origins, so the overflow downdraw method is the most suitable forming method because it is non-contact and less likely to cause scratches. In this embodiment, a glass ribbon is formed by the overflow downdraw method, and rectangular glass sheets of a predetermined size are obtained by cutting from this glass ribbon. The preparation process includes a forming step P1, an annealing step P2, a cooling step P3, and a cutting step (not shown) as shown in FIGS. 1 and 2 .

[0037] In the preparation step, first, the forming step P1 to the cooling step P3 are carried out using the manufacturing apparatus 1 shown in FIGS. 1 and 2, thereby obtaining a belt-shaped glass film 2 that will be the base of a glass plate to be chemically strengthened.

[0038] The forming step P1 is carried out in the forming zone ZN1. In the forming step P1, a glass ribbon 5 is continuously formed from molten glass 4 using a forming body 3 for the overflow downdraw process. The forming body 3 is housed in a forming furnace 6, and the forming furnace 6 is equipped with a heating device (e.g., a panel heater) or the like (not shown) for heating the forming body 3.

[0039] The forming body 3 has a groove 3a for allowing the molten glass 4 to flow in, a pair of side portions 3b, 3b for allowing the molten glass 4 overflowing on both sides from the groove 3a to flow down, and a bottom end portion 3c for fusing (merging) the molten glass 4 that has flowed down along each side portion 3b. The forming body 3 forms a glass ribbon 5 from the molten glass 4 fused at the bottom end portion 3c.

[0040] The glass ribbon 5 has a useful portion 5a located in the center of its width direction (the left-right direction in FIG. 1 , and the direction perpendicular to the paper surface in FIG. 2 ), and non-useful portions 5b located at both ends in the width direction, sandwiching the useful portion 5a. The useful portion 5a is a portion that includes a part that will later become a product, while the non-useful portion 5b is a portion that will not become a product and will later be discarded. Of the non-useful portions 5b that form the width direction ends of the glass ribbon 5, portions that correspond to the width direction edges (edges) of the glass ribbon 5 have glass pool portions (also called ear portions) that are thicker than other portions.

[0041] Immediately after forming, the glass ribbon 5 is prevented from shrinking in the width direction by using edge rollers 7 (cooling rollers) arranged directly below the formed body 3.

[0042] A pair of edge rollers 7 are arranged to sandwich the glass ribbon 5 in the thickness direction. Each of the pair of edge rollers 7, 7 includes a shaft 7a extending in the width direction of the glass ribbon 5, and a first roll 7b and a second roll 7c connected to each other via the shaft 7a. Both rolls 7b, 7c are made of a heat-resistant material (e.g., platinum or a platinum alloy), and both come into contact with the non-effective portion 5b of the glass ribbon 5. By sandwiching the glass ribbon 5 in the thickness direction between the first rolls 7b, 7b and the second rolls 7c, 7c of this pair of edge rollers 7, 7, the glass ribbon 5 is fed downward while suppressing shrinkage of the glass ribbon 5 in the width direction.

[0043] The annealing process P2 is performed in the annealing zone ZN2. In the annealing process P2, the glass ribbon 5 descending from the forming zone ZN1 is guided downward and slowly cooled to a temperature below the strain point. The annealing process P2 is performed using an annealing furnace 8 and annealer rollers 9 arranged in multiple vertical stages (five vertical stages in the illustrated example).

[0044] The annealing furnace 8 is disposed below the forming furnace 6. The annealing furnace 8 is equipped with a heating device (e.g., a panel heater) (not shown) for adjusting the atmospheric temperature within the annealing furnace 8. For example, in the case of a glass sheet material for chemical strengthening, it is preferable to provide a heating device or heat-retaining member capable of adjusting the temperature by creating a temperature gradient in the width direction of the glass sheet in a temperature range between a temperature lower than the softening point (e.g., 860°C) and the strain point (e.g., 560°C). In the annealing step P2, the annealing rate is relatively faster in the region closer to the width direction ends (closer to the glass pool), particularly in the early stage of the annealing step P2, where the temperature of the glass ribbon 5 is relatively high, and the annealing rate is relatively slower in the region closer to the width direction center. Specifically, the annealing step P2 is performed at a temperature drop rate of 1 to 10°C / sec in the center and 3 to 20°C / sec in the end portions. This makes it possible to suppress warping of the peripheral edge portion of the glass plate (see FIGS. 3 and 4) obtained in the cutting step that is performed later.

[0045] In each of the upper and lower multiple stages, a pair of annealer rollers 9 are arranged to sandwich the glass ribbon 5 in the thickness direction. Each of the pair of annealer rollers 9, 9 includes a shaft 9a extending in the width direction of the glass ribbon 5, and a first roll 9b and a second roll 9c connected to each other via the shaft 9a. As an example, both rolls 9b, 9c are made of ceramic, and both are capable of contacting the non-useful portion 5b of the glass ribbon 5. The glass ribbon 5 is guided downward by the first rolls 9b, 9b of each pair of annealer rollers 9, 9 and the second rolls 9c, 9c of each pair of annealer rollers 9, 9.

[0046] Here, the first rolls 9b, 9b and the second rolls 9c, 9c do not sandwich the glass ribbon 5 from both the front and back sides, but simply restrict the oscillation of the glass ribbon 5 in the thickness direction. In other words, a gap is formed between the first roll 9b and the glass ribbon 5 and between the second roll 9c and the glass ribbon 5.

[0047] Another method for suppressing warpage in the peripheral portion of the glass sheet obtained by the cutting step is to change the tension in the width direction acting on the glass ribbon 5 by sandwiching the non-useful portion 5b of the glass ribbon 5 from both the front and back sides with annealer rollers 9 in the annealing furnace 8. For example, by increasing the tension in the width direction acting on the glass ribbon 5, it is possible to suppress warpage of the glass ribbon 5, particularly at both ends in the width direction of the useful portion 5a. As a result, warpage in the peripheral portion of the glass sheet can be suppressed.

[0048] The cooling step P3 is performed in the cooling zone ZN3. In the cooling step P3, the glass ribbon 5 that has passed through the annealing zone ZN2 is cooled while being pulled downward by support rollers 10. The support rollers 10 are disposed in a cooling chamber 11 that is disposed below the annealing furnace 8.

[0049] A pair of support rollers 10 are arranged to sandwich the glass ribbon 5 in the thickness direction. Each of the pair of support rollers 10, 10 includes a shaft 10a extending in the width direction of the glass ribbon 5, and a first roll 10b and a second roll 10c connected to each other via the shaft 10a. Both rolls 10b, 10c are made of rubber, for example, and both come into contact with the non-effective portion 5b of the glass ribbon 5. The glass ribbon 5 is sandwiched and pulled in the thickness direction by the first rolls 10b, 10b of the pair of support rollers 10, 10, and the second rolls 10c, 10c of the pair of support rollers 10, 10, thereby determining the conveying speed V1 (sheet drawing speed) of the glass ribbon 5. The glass ribbon 5 that passes through the cooling zone ZN3 during conveyance is obtained as a belt-shaped glass film 2.

[0050] After the cooling step P3 is completed, the cutting step is carried out.

[0051] In the cutting step, a first cutting step is performed to cut out an original glass film from the belt-shaped glass film 2, and a second cutting step is performed to cut out a glass plate to be chemically strengthened from the original glass film.

[0052] In the first cutting, the band-shaped glass film 2 is repeatedly cut (cut in the width direction) at predetermined lengths to continuously cut out glass film original plates from the band-shaped glass film 2. Each cut-out glass film original plate includes a valid portion 5a and non-valid portions 5b located on both sides of the valid portion 5a. In the second cutting, the non-valid portions 5b are separated and removed from each glass film original plate, thereby cutting out the valid portions 5a as glass plates for chemical strengthening. The first and second cutting can be performed by known techniques, and detailed descriptions thereof will be omitted.

[0053] In the present embodiment, the non-effective portions 5b of the belt-shaped glass film 2 are divided and removed after the original glass film is cut out. However, this is not limiting, and as another method, first, the non-effective portions 5b of the belt-shaped glass film 2 are continuously divided and removed, and then the belt-shaped glass film 2 from which the non-effective portions 5b have been removed is repeatedly cut (cut in the width direction) at predetermined lengths, thereby continuously cutting glass plates for chemical strengthening from the belt-shaped glass film 2.

[0054] Alternatively, a method may be employed in which non-useful portions of the strip-shaped glass film 2 are continuously cut and removed, and then the strip-shaped glass film 2 is continuously wound into a roll via a strip-shaped buffer material (such as a resin strip-shaped protective sheet). In this case, the strip-shaped glass film 2 is unwound from the roll in increments of a length required in a subsequent process, and the unwound strip-shaped glass film 2 is cut to cut out glass sheets for chemical strengthening. This improves the efficiency of obtaining glass sheets for chemical strengthening, thereby achieving cost reduction. Note that when this method is employed, edge treatments such as polishing, heat treatment, and etching, which will be described later, may be performed after the strip-shaped glass film 2 is cut out.

[0055] When the first and second cuts are performed, the cutting step is completed, and accordingly, the preparation step is completed. In this embodiment, the glass sheet to be chemically strengthened is obtained by the overflow downdraw method, but the glass sheet to be chemically strengthened may also be obtained by other methods such as the slot downdraw method, the float method, the redraw method, etc.

[0056] Here, it is preferable to subject the cut edge surfaces of the glass plate for chemical strengthening to chamfering or strength improvement treatments such as polishing, heat treatment, etching, etc. On the other hand, the front and back surfaces of the glass plate for chemical strengthening are not subjected to polishing treatments or the like (for example, chemical polishing treatments such as slimming treatments that reduce thickness) after forming, so that the front and back surfaces of the glass plate for chemical strengthening are fire-polished surfaces.

[0057] When the preparation process is completed as described above, a glass plate 12 for chemical strengthening (hereinafter simply referred to as glass plate 12) as shown in FIGS. 3 and 4 is prepared. The glass plate 12 shown in FIG. 3 and the glass plate 12 shown in FIG. 4 are the same glass plate. FIG. 3 shows a first mounting configuration in which the glass plate 12 is placed on a horizontal surface with one main surface 12a of the front and back surfaces of the glass plate 12 facing up. On the other hand, FIG. 4 shows a second mounting configuration in which the glass plate 12 is placed on a horizontal surface with the other main surface 12b, which is located on the back side of the one main surface 12a, facing up. Note that the horizontal surface in this embodiment refers to a horizontal support surface provided on a surface plate (not shown).

[0058] In this embodiment, the first main surface 12a is the guaranteed surface, which is the surface of the front and back surfaces of the glass plate 12 that is suitable for film formation and other processes and whose surface quality should be guaranteed, and the other main surface 12b is the non-guaranteed surface that does not require the same level of surface quality as the first main surface 12a. The guaranteed surface and the non-guaranteed surface are determined, for example, as follows: The first main surface 12a, which has been in contact with a conveying roller or the like relatively less frequently up until the completion of the above-described preparation process, is designated as the guaranteed surface, and the other main surface 12b, which has been in contact with a conveying roller or the like relatively more frequently, is designated as the non-guaranteed surface. In this case, comparing the first main surface 12a and the other main surface 12b, the first main surface 12a, which is the guaranteed surface, has fewer defects such as scratches and fewer contaminants.

[0059] Although there is no limitation on the type of glass plate 12, the glass plate 12 in this embodiment is an aluminosilicate glass. The glass plate 12 contains, in mass %, an example of a glass composition of 50 to 80% SiO, 5 to 25% AlO, 0 to 15% BO, 1 to 20% NaO, and 0 to 10% KO.

[0060] More preferably, the glass composition of the glass plate 12 in this embodiment contains, in mass %, 60 to 80% of SiO2, 8 to 18% of Al2O3, 0 to 5% of B2O3, 0.01 to 10% of Li2O, 4 to 16% of Na2O, and 0.01 to 10% of K2O.

[0061] Although increasing the Al2O3 content significantly improves the ion exchange performance of the glass for chemical strengthening, too high an Al2O3 content leads to a worsening of devitrification, i.e., the liquidus temperature becomes too high or the liquidus viscosity becomes too low, making it impossible to form the glass by the overflow downdraw method.

[0062] Na2O is an ion-exchange component, and it also has the effect of reducing the high-temperature viscosity of glass, improving meltability and formability, reducing the incidence of cracks, and lowering the strain point. It is also a component that improves devitrification. However, if the Na2O content is too high, the thermal expansion coefficient becomes too large, which can reduce the thermal shock resistance of the glass and make it difficult to match the thermal expansion coefficient of surrounding materials. Furthermore, if the content is too high, devitrification tends to worsen.

[0063] B2O3 has the effect of lowering the liquidus temperature, high-temperature viscosity, and density of glass. However, if the B2O3 content is too high, there is a risk of surface discoloration due to ion exchange. In addition, the strain point may be too low, which may lead to stress relaxation during ion exchange and prevent the desired compressive stress from being achieved.

[0064] The type of glass plate 12 in this embodiment is not limited to glass for chemical strengthening, and may be applied to other ultra-thin glass plates such as low-alkali glass substrates. Regardless of the material, ultra-thin glass plates are susceptible to warping and breakage during handling processes such as cutting, cleaning, packaging, and chemical strengthening, so shape control is important.

[0065] The glass plate 12 in this embodiment has a melting point of 70 to 100×10 at 30 to 380° C. -7It is desirable for the glass to have a thermal expansion coefficient of 1 / °C. To suppress warping after molding or during chemical strengthening, it is better to have a small thermal expansion coefficient, but if the thermal expansion coefficient is incompatible with that of surrounding materials, problems such as peeling of the glass substrate may occur. For example, when used as a cover glass for a foldable device, since there are organic substances such as metals and adhesives in the vicinity, if the thermal expansion coefficients do not match, the glass substrate will peel when bonded using an organic adhesive. In order to facilitate compatibility with the thermal expansion coefficient of surrounding materials, in the present invention, the thermal expansion coefficient of the glass can be increased by increasing the content of alkali metal oxide components or alkaline earth metal oxide components or decreasing the content of SiO2 or Al2O3. The thermal expansion coefficient can be decreased by reducing the content of alkali metal oxide components or alkaline earth metal oxide components or increasing the content of SiO2 or Al2O3.

[0066] The glass plate 12 in this embodiment preferably has a melting point of 75 to 92×10 at 30 to 380° C. -7 It is desirable for the glass sheet to have a thermal expansion coefficient of 1 / °C. If the thermal expansion is relatively small, the glass sheet will undergo little thermal deformation during the high-temperature process of strengthening the glass sheet for chemical strengthening, and this can prevent contact with jigs that hold the glass during the chemical strengthening process, or an increase in local warping after strengthening due to partial residue of the strengthening liquid, such as hot potassium nitrate.

[0067] The shape of the glass plate 12 is not particularly limited, but in this embodiment, it is rectangular. An example of the size of the glass plate 12 is 150 mm × 150 mm to 1100 mm × 1300 mm. The glass plate 12 in this embodiment has long sides 12x and short sides 12y, and the length of the long sides 12x is 400 mm or 500 mm, and the length of the short sides 12y is 300 mm or 400 mm. In this glass plate 12, the extending direction of the long sides 12x coincides with the sheet drawing direction (the longitudinal direction of the glass ribbon 5) in the above-described forming step P1 to cooling step P3. As described above, even in the case where the band-shaped glass film 2 after removing the non-effective portions 5b is once wound into a roll and then the band-shaped glass film 2 unwound from the roll is cut to obtain the glass plate 12, the extending direction of the long sides 12x of the glass plate 12 coincides with the sheet drawing direction.

[0068] When the width of the glass ribbon 5 (strip-shaped glass film 2) to be formed is sufficiently large, the glass sheets 12 may be cut from the strip-shaped glass film 2 so that the extension direction of the short sides 12y of the glass sheets 12 coincides with the sheet drawing direction.

[0069] The thickness of the glass sheet 12 is 0.1 mm or less, preferably 0.01 mm or more and 0.095 mm or less, more preferably 0.02 mm or more and 0.085 mm or less, and even more preferably 0.025 mm or more and 0.075 mm or less. To further reduce the thickness of the glass sheet 12, the thickness of the glass sheet 12 can be 0.065 mm or less, 0.055 mm or less, or 0.05 mm or less. On the other hand, the lower limit of the thickness of the glass sheet 12 is 0.025 mm or more, more preferably 0.03 mm or more. If the glass sheet 12 is made too thin, the bending of the glass sheet 12 becomes too large, making it difficult to ensure strength. Furthermore, if the glass sheet 12 is made too thin, the difference between the thickness of the glass pool at the edge of the glass sheet 12 during forming and the thickness of the central portion of the glass sheet 12 to be produced becomes large, making it even more difficult to improve the thickness distribution of the formed glass sheet 12 and suppress warpage.

[0070] In particular, when the glass sheet 12 is thin, the difference in sheet thickness between the ineffective portions 5b at both widthwise ends of the band-shaped glass film 2 and the effective portion 5a at the center in the widthwise direction becomes more pronounced during overflow forming, making warpage more likely to occur near the periphery of the glass sheet 12, particularly near the corners. This makes it difficult to remove the warpage, reducing the effective portion, which can lead to deterioration of the warped shape during chemical strengthening at high temperatures, such as 360°C or higher, or breakage during the processing, significantly reducing the efficiency of producing products as glass for chemical strengthening. Furthermore, it becomes very difficult to maintain the glass shape when the glass sheet 12 for chemical strengthening is subjected to the chemical strengthening process, inducing further increase in glass deformation.

[0071] In this embodiment, the glass plate 12 has a substantially uniform thickness throughout. Here, "substantially uniform thickness" means that the deviation in thickness of the glass plate 12 is ±20% or less. The deviation in thickness of the glass plate 12 is preferably ±10% or less, and more preferably ±5% or less.

[0072] The glass plate 12 includes a warp, and the warp causes unevenness on the first main surface 12a and the other main surface 12b. As a result, in both the first and second mounting configurations, there are portions of the glass plate 12 that rise above the horizontal plane. Here, XY coordinates are taken as shown in Figures 3 and 4 for each of the first and second mounting configurations. That is, with one of the four corners of the glass plate 12 as the origin S, the X axis [mm] is taken in the direction in which the long side 12x extends, and the Y axis [mm] is taken in the direction in which the short side 12y extends. Therefore, the coordinates of points A, B, and C shown in both figures are A(400,0), B(400,300), C(0,300) or A(500,0), B(500,400), C(0,400), taking into account the lengths of the long side 12x and short side 12y (400mm x 300mm or 500mm x 400mm) described above in this embodiment.

[0073] Furthermore, the glass plate 12 is regulated as follows (1) to (8). (1) The thickness of the glass plate 12 is t [mm]. (2) When the first placement configuration (FIG. 3) is adopted, the position on the glass plate 12 that is highest from the horizontal plane is defined as the first peak position D1. (3) The height of the glass plate 12 from the horizontal plane at the first peak position D1 is W 1MAX [mm]. (4) When the second placement configuration (FIG. 4) is adopted, the position on the glass plate 12 that is highest from the horizontal plane is defined as the second peak position D2. (5) The height of the glass plate 12 from the horizontal plane at the second peak position D2 is W 2MAX [mm]. (6) A 10 mm wide portion along the edge of the glass plate 12 (the cross-hatched portion having width L1 shown in FIGS. 3 and 4) is designated as a peripheral portion 12e. (7) When the first mounting configuration (FIG. 3) is adopted, the height of the position D3 (hereinafter referred to as the first peripheral peak position D3) that is the highest from the horizontal plane in the peripheral portion 12e is defined as W 1OUT [mm]. (8) When the second mounting configuration (FIG. 4) is adopted, the height of the position D4 (hereinafter referred to as the second peripheral peak position D4) that is the highest from the horizontal plane in the peripheral portion 12e is defined as W 2OUT [mm].

[0074] In this embodiment, a glass substrate warpage measuring instrument manufactured by Apollo Precision, product name: Model 1313SK, is used as the measuring device to measure the height of each position on the upper surface of the glass plate 12 when the glass plate 12 is placed horizontally, including the first peak position D1 and second peak position D2. Note that the first peak position D1, second peak position D2, first peripheral peak position D3, and second peripheral peak position D4 shown in Figures 3 and 4 are merely examples of these positions.

[0075] Here, the many measurement positions where height is measured by the above-mentioned measuring device are scattered on the XY coordinate system. In other words, the height is not measured at every possible position on the glass plate 12. Therefore, the first peak position D1 and the second peak position D2 simply mean the position where the height is the highest among the positions where measurements are performed. In other words, there is a high probability that there is a positional deviation between the position where the height is truly the highest (the position that protrudes most upward among all positions on the glass plate 12) and the first peak position D1 or the second peak position D2. As a result, the height at the truly highest position and the above-mentioned W 1MAX The value of W 2MAX There is a high probability that there will be a discrepancy between the values. Therefore, it is necessary to narrow the interval between adjacent measurement positions to an extent that this discrepancy can be ignored. The interval between adjacent measurement positions is preferably 100 mm or less in each of the X-axis direction and the Y-axis direction, more preferably 50 mm or less, more preferably 30 mm or less, even more preferably 20 mm or less, and most preferably 10 mm or less, 5 mm or less. However, from the viewpoint of shortening the time required for measurement, the interval between adjacent measurement positions may be made as wide as possible within a range in which the required accuracy can be obtained.

[0076] Under the above provisions (1) to (8), in this glass plate 12, as shown in FIG. 3, the first peak position D1 exists in a part inside the peripheral edge 12e of the glass plate 12 (that is, a region closer to the center than the peripheral edge 12e in plan view). That is, when the coordinates of the first peak position D1 are D1(X1, Y1), when the long side 12x is 400 mm and the short side 12y is 300 mm, 10 < X1 < 390 is satisfied, and 10 < Y1 < 290 is satisfied. Also, when the long side 12x is 500 mm and the short side 12y is 400 mm, 10 < X1 < 490 is satisfied, and 10 < Y1 < 390 is satisfied. Incidentally, preferably, when a portion having a width of 50 mm along the periphery of the glass plate 12 (the hatched portion having the width L2 shown in FIGS. 3 and 4) is defined as the second peripheral edge 12f, the first peak position D1 exists in a part inside the second peripheral edge 12f of the glass plate 12. That is, when the long side 12x is 400 mm and the short side 12y is 300 mm, it is preferable that 50 < X1 < 350 is satisfied, and 50 < Y1 < 250 is satisfied. Also, when the long side 12x is 500 mm and the short side 12y is 400 mm, it is preferable that 50 < X1 < 450 is satisfied, and 50 < Y1 < 350 is satisfied. By doing so, since the top of the warp with the highest height exists more inside the glass plate, when cutting the glass plate into individual small substrates using, for example, a diamond scribe, bending stress, a laser, etc. in a later process for use in a smaller-sized device such as a foldable device, it becomes difficult to induce defects such as breakage occurring near the end face which is the cutting start point and cutting errors due to abnormal laser focus.

[0077] Also, in this glass plate 12, t 2 / W 1OUT >0.005, W 1OUT ≦0.20 mm (preferably W 1OUT ≦0.10 mm), W 1OUT / t < 5, W 1MAX / t < 15 are preferably satisfied.

[0078] Furthermore, in this glass plate 12, as shown in FIG. 4, the second peak position D2 exists in a portion inside the peripheral edge portion 12e of the glass plate 12. That is, when the coordinates of the second peak position D2 are D2(X2, Y2), when the long side 12x is 400 mm and the short side 12y is 300 mm, 10 < X2 < 390 is satisfied, and 10 < Y2 < 290 is satisfied. Also, when the long side 12x is 500 mm and the short side 12y is 400 mm, 10 < X2 < 490 is satisfied, and 10 < Y2 < 390 is satisfied. Preferably, the second peak position D2 exists in a portion inside the second peripheral edge portion 12f of the glass plate 12. That is, when the long side 12x is 400 mm and the short side 12y is 300 mm, it is preferable that 50 < X2 < 350 is satisfied, and 50 < Y2 < 250 is satisfied. Also, when the long side 12x is 500 mm and the short side 12y is 400 mm, it is preferable that 50 < X2 < 450 is satisfied, and 50 < Y2 < 350 is satisfied.

[0079] In addition, in this glass plate 12, t 2 / W 2OUT > 0.005, W 2OUT ≦ 0.20 mm (preferably W 2OUT ≦ 0.10 mm), W 2OUT / t < 5, W 2MAX / t < 15 are preferably satisfied.

[0080] According to this glass plate 12, in the manufacturing process that the glass plate 12 undergoes before becoming a tempered glass plate, it is possible to avoid breakage caused by warping as much as possible.

[0081] [Cutting process] The cutting process is performed on the glass plate 12 prepared in the preparation process. Since the cutting process can be performed by a known method, detailed description thereof is omitted. When the cutting process is completed, a product-size glass plate (for example, a glass plate having a size suitable for the screen of a smartphone or a tablet PC) is obtained. Note that, in some cases, a single product-size glass plate may be cut out from one glass plate 12, and in other cases, a plurality of product-size glass plates may be cut out.

[0082] [Strengthening process] In the tempering process, the glass plate of product size obtained in the cutting process is chemically tempered to obtain a tempered glass plate having compressive stress layers (layers subjected to compressive stress) formed on both the front and back sides. Specific aspects of chemical tempering are well known, so a detailed description will be omitted. The tempering process is thus completed, and a tempered glass plate is produced. [Example]

[0083] As a first example, glass plates for chemical strengthening (Examples 1 to 18, Comparative Examples 1 to 4) having the parameters shown in Tables 1 to 4 below were prepared, and the rate at which the glass plates were broken due to warping (breakage rate) during the manufacturing process before being made into tempered glass plates was calculated. Specifically, the manufacturing process included a cutting process for cutting glass plates for chemical strengthening from glass film originals, a cleaning process after cutting, and an appearance inspection process. The glass plates for chemical strengthening in the examples contained, in mole percent, 61.6% SiO2, 18.0% Al2O3, 0.5% BO3, 3.0% MgO, 14.5% Na2O, 2.0% KO, and 0.4% SnO2, had a strain point of 564°C, and exhibited a strain of 91 × 10 at 30 to 380°C. -7 The glass plate has a thermal expansion coefficient of 1 / °C and is formed by the overflow downdraw method. The glass plate for chemical strengthening in the examples has its thermal history during annealing, its cutting position from the glass film original, and the like adjusted.

[0084] The parameters shown in Tables 1 to 4 are all the same indicators as the parameters described in the above embodiments. In Tables 1 to 4, the term "first surface" refers to the case where the glass sheet is placed on a horizontal surface with the guaranteed side (one of the main surfaces) facing up (the first placement configuration). Meanwhile, the term "second surface" refers to the case where the glass sheet is placed on a horizontal surface with the non-guaranteed side (the other main surface) facing up (the second placement configuration). Furthermore, in the "maximum value is inside" section, "◯" means that the first peak position (second peak position) is located inside the peripheral edge of the glass sheet, and "×" means that the first peak position (second peak position) is located within the peripheral edge of the glass sheet. Here, the height from the horizontal plane of the glass sheet (long side × short side: 400 mm × 300 mm) was measured at each coordinate where a line parallel to the Y axis and a line parallel to the X axis intersected, which were set in 5 mm increments on the XY coordinate system. In this first example, the case where the width of the peripheral edge of the glass plate is 10 mm was considered. Therefore, if at least one of the conditions that the X coordinate of the first peak position is either 10 mm or less or 390 mm or more and the Y coordinate of the first peak position is either 10 mm or less or 290 mm or more is satisfied, the "Maximum value is on the inside" item for the first peak position is marked with an "X." If neither of the conditions is satisfied, the "Maximum value is on the inside" item for the first peak position is marked with an "O." Similarly, if at least one of the conditions that the X coordinate of the second peak position is either 10 mm or less or 390 mm or more and the Y coordinate of the second peak position is either 10 mm or less or 290 mm or more is satisfied, the "Maximum value is on the inside" item for the second peak position is marked with an "X." If neither of the conditions is satisfied, the "Maximum value is on the inside" item for the second peak position is marked with an "O."

[0085] A specific method for determining the breakage rate will be described using Example 1 as an example. First, a large number of glass plates for chemical strengthening manufactured under the same conditions as the glass plate of Example 1 were prepared. Then, for each glass plate, the presence or absence of breakage at the time of completion of the cleaning process among the above-mentioned manufacturing processes was determined by a visual inspection process, and the breakage rate was determined by calculating the proportion of broken glass plates among the large number of glass plates. The breakage rates were also determined for Examples 2 to 18 and Comparative Examples 1 to 4 using a similar method. Note that the number of glass plates for chemical strengthening manufactured under the same conditions as each Example and Comparative Example was 200 to 500 (the number differed depending on each Example and Comparative Example).

[0086] [Table 1]

[0087] The breakage rates shown in Table 1 indicate that no glass breakage occurred in Examples 1 to 5, in which the first peak position was located inside the peripheral edge of the glass plate. Fig. 5 shows the warpage distribution (the distribution of irregularities on the guaranteed surface) at Y=105, which includes the first peak position, when the first mounting configuration was adopted in Example 5. Fig. 5 also shows excerpts of heights measured at X=5, 55, 105, 155, 205, 255, 305, 355, and 395.

[0088] [Table 2]

[0089] The breakage rates shown in Table 2 reveal that, among Examples 6 to 9 in which the first peak position was located inside the peripheral edge of the glass sheet, no breakage of the glass sheet occurred in Examples 6 and 7. Furthermore, even in Examples 8 and 9 in which breakage occurred, it was found that the breakage rate of the glass sheet was significantly reduced compared to Comparative Examples 1 and 2 in which the first peak position was located within the peripheral edge of the glass sheet.

[0090] [Table 3]

[0091] The breakage rates shown in Table 3 show that no breakage of the glass sheet occurred in Examples 10 to 13, in which the first peak position was located inside the peripheral edge of the glass sheet. In contrast, in Comparative Example 3, in which the first peak position was located within the peripheral edge of the glass sheet, breakage of the glass sheet occurred, even though the sheet thickness was the same as in Examples 10 to 13.

[0092] [Table 4]

[0093] The breakage rates shown in Table 4 indicate that when the plate thickness is as very thin as 0.03 mm, it becomes difficult to completely suppress breakage during the process. However, in Examples 14 to 18, in which the first peak position is located inside the peripheral portion of the glass plate, the breakage rate of the glass plate is significantly suppressed compared to Comparative Example 4, in which the first peak position is located within the peripheral portion of the glass plate.

[0094] Here, in Examples 14 and 15, in addition to satisfying the condition that the first peak position is present in a region inside the peripheral portion of the glass plate, the following relationships, namely, W 1OUT ≦0.20mm, t 2 / W 1OUT >0.005, W 1OUT / t<5, W 1MAX / t<15, W 2OUT ≦0.20mm, t 2 / W 2OUT >0.005, W 2OUT / t<5, W 2MAX On the other hand, in Example 16, among the relationships listed above, W 1OUT Only the relationship / t<5 is not satisfied. 2OUT ≦0.20mm, t 2 / W 2OUT >0.005, W2OUT / t<5. In Example 18, W 2OUT ≦0.20mm, t 2 / W 2OUT >0.005, W 2OUT / t<5, W 2MAX / t<15. In Example 18, the second peak position was located within the peripheral portion of the glass plate. From these results, it can be seen that in glass plates thinned to a thickness of 0.03 mm, glass plates that satisfy more of the relationships listed above tend to have a lower breakage rate.

[0095] Table 5 below shows the heights [μm] of the glass plate from the horizontal plane measured at each of the coordinates shown in the table when the first mounting configuration was adopted in Example 14. FIG. 6 also shows the distribution of warpage (distribution of irregularities on the guaranteed surface) in the same case. Table 5, Tables 6 to 16 shown later, and FIG. 6 and FIGS. 8 to 18 shown later show excerpts of heights measured at some of the coordinates. Specifically, the heights shown are excerpts of heights measured at each of the coordinates where nine lines parallel to the Y axis, represented by X=5, 55, 105, 155, 205, 255, 305, 355, and 395, intersect with seven lines parallel to the X axis, represented by Y=5, 55, 105, 155, 205, 255, and 295, respectively. Furthermore, Figure 7 shows the distribution of warpage (distribution of unevenness on the guaranteed surface) at Y=55, which includes the first peak position. Figure 7 also shows excerpts of heights measured at X=5, 55, 105, 155, 205, 255, 305, 355, and 395. In these cases, the average height was 45 μm (0.045 mm). The standard deviation of the height was 0.050.

[0096] [Table 5]

[0097] Table 6 below shows the heights [μm] of the glass plate from the horizontal plane measured at each coordinate shown in the table when the second mounting configuration was adopted in Example 14. FIG. 8 also shows the distribution of warpage (distribution of irregularities on the non-guaranteed surface) in the same case. In this case, the average height was 69 μm (0.069 mm). The standard deviation of the height was 0.058.

[0098] [Table 6]

[0099] Table 7 below shows the heights [μm] of the glass plate from the horizontal plane measured at each coordinate shown in the table when the first mounting configuration was adopted in Example 15. FIG. 9 also shows the distribution of warpage (distribution of irregularities on the guaranteed surface) in the same case. In this case, the average height was 63 μm (0.063 mm). The standard deviation of the height was 0.055.

[0100] [Table 7]

[0101] Table 8 below shows the heights [μm] of the glass plate from the horizontal plane measured at each coordinate shown in the table when the second mounting configuration was adopted in Example 15. FIG. 10 also shows the distribution of warpage (distribution of irregularities on the non-guaranteed surface) in the same case. In this case, the average height was 64 μm (0.064 mm). The standard deviation of the height was 0.083.

[0102] [Table 8]

[0103] Table 9 below shows the heights [μm] of the glass plate from the horizontal plane measured at each coordinate shown in the table when the first mounting configuration was adopted in Example 16. FIG. 11 also shows the distribution of warpage (distribution of irregularities on the guaranteed surface) in the same case. In this case, the average height was 46 μm (0.046 mm). The standard deviation of the height was 0.048.

[0104] [Table 9]

[0105] Table 10 below shows the heights [μm] of the glass plate from the horizontal plane measured at each coordinate shown in the table when the second mounting configuration was adopted in Example 16. FIG. 12 also shows the distribution of warpage (distribution of irregularities on the non-guaranteed surface) in the same case. In this case, the average height was 48 μm (0.048 mm). The standard deviation of the height was 0.037.

[0106] [Table 10]

[0107] Table 11 below shows the heights [μm] of the glass plate from the horizontal plane measured at each coordinate shown in the table when the first mounting configuration was adopted in Example 17. FIG. 13 also shows the distribution of warpage (distribution of irregularities on the guaranteed surface) in the same case. In this case, the average height was 84 μm (0.084 mm). The standard deviation of the height was 0.076.

[0108] [Table 11]

[0109] Table 12 below shows the heights [μm] of the glass plate from the horizontal plane measured at each coordinate shown in the table when the second mounting configuration was adopted in Example 17. FIG. 14 also shows the distribution of warpage (distribution of irregularities on the non-guaranteed surface) in the same case. In this case, the average height was 90 μm (0.09 mm). The standard deviation of the height was 0.098.

[0110] [Table 12]

[0111] Table 13 below shows the heights [μm] of the glass plate from the horizontal plane measured at each coordinate shown in the table when the first mounting configuration was adopted in Example 18. FIG. 15 also shows the distribution of warpage (distribution of irregularities on the guaranteed surface) in the same case. In this case, the average height was 70 μm (0.07 mm). The standard deviation of the height was 0.078.

[0112] [Table 13]

[0113] Table 14 below shows the height [μm] of the glass plate from the horizontal plane measured at each coordinate shown in the table when the second mounting configuration is adopted in Example 18. Also, FIG. 16 shows the distribution of warpage in the same case (distribution of irregularities on the non-guaranteed surface). As shown in the figure, in this case, the second peak position D2 and the second peripheral peak position D4 coincide (W 2MAX and W 2OUT In this case, the average height was 72 μm (0.072 mm). The standard deviation of the height was 0.094.

[0114] [Table 14]

[0115] Table 15 below shows the height [μm] of the glass plate from the horizontal plane measured at each coordinate shown in the table when the first mounting configuration was adopted in Comparative Example 4. Also, FIG. 17 shows the distribution of warpage in the same case (distribution of irregularities on the guaranteed surface). As shown in the figure, in this case, the first peak position D1 and the first peripheral peak position D3 coincide (W 1MAX and W 1OUT In this case, the average height was 101 μm (0.101 mm). The standard deviation of the height was 0.128.

[0116] [Table 15]

[0117] Table 16 below shows the height [μm] of the glass plate from the horizontal plane measured at each coordinate shown in the table when the second mounting configuration was adopted in Comparative Example 4. Also, FIG. 18 shows the distribution of warpage in the same case (distribution of irregularities on the non-guaranteed surface). As shown in the figure, in this case, the second peak position D2 and the second peripheral peak position D4 coincide (W 2MAX and W 2OUT In this case, the average height was 73 μm (0.073 mm). The standard deviation of the height was 0.077.

[0118] [Table 16]

[0119] As described above, among Examples 14 to 18, it can be seen that breakage of the glass sheet can be suppressed even in Examples 17 and 18, in which the average height and standard deviation of the height are relatively large (see also Table 4 above). In other words, breakage can be suppressed even in glass sheets that have portions that are higher in height from the horizontal plane due to warping, or glass sheets in which the unevenness between the guaranteed surface and the non-guaranteed surface is significantly changed due to warping. It is presumed that such results were obtained because, in each Example, the first peak position was located in a region on the inside of the peripheral edge of the glass sheet.

[0120] Next, as a second example, another glass plate for chemical strengthening (Example 19) having the parameters shown in Table 17 below was prepared, and the rate at which the glass plate was broken due to warping (breakage rate) during the manufacturing process before being made into a tempered glass plate was calculated. Specifically, the manufacturing process included a cutting process for cutting a glass plate for chemical strengthening from a glass film base, a cleaning process after cutting, and an appearance inspection process. The glass plate for chemical strengthening in the second example contained, in mole percent, 66.1% SiO, 14.0% AlO, 2.5% BO, 3.0% MgO, 13.4% NaO, and 0.6% KO, had a strain point of 551°C, and had a melting point of 79 × 10 between 30 and 380°C. -7 The glass plate has a thermal expansion coefficient of 1 / °C and is formed by the overflow downdraw method.

[0121] In the second example, the height from the horizontal plane of a glass plate (long side x short side: 500 mm x 400 mm) was measured at each coordinate where a line parallel to the Y axis, set in 5 mm increments on the XY coordinate system, intersected with a line parallel to the X axis. In this second example, the width of the peripheral edge of the glass plate was considered to be 50 mm. Therefore, if at least one of the following conditions is met: the X coordinate of the first peak position is either 50 mm or less or 450 mm or more; and the Y coordinate of the first peak position is either 50 mm or less or 350 mm or more, the "maximum value is on the inside" item for the first peak position is marked with an "X." If neither of these conditions is met, the "maximum value is on the inside" item for the first peak position is marked with an "O." Similarly, if at least one of the conditions that the X coordinate of the second peak position is either 50 mm or less or 450 mm or more, and the Y coordinate of the second peak position is either 50 mm or less or 350 mm or more is met, the ``Maximum value is inside'' item for the second peak position will be marked ``X'', and if neither condition is met, the ``Maximum value is inside'' item for the second peak position will be marked ``O''.

[0122] [Table 17]

[0123] The breakage rates shown in Table 17 show that in Example 19, in which the first peak position was located inside the peripheral edge (width 50 mm) of the glass plate, no breakage of the glass plate occurred.

[0124] Table 18 below shows the height [μm] of the glass plate from the horizontal plane measured at each coordinate shown in the table when the first mounting configuration was adopted in Example 19. Also, FIG. 19 shows the distribution of warpage ( WarrantyThe graph shows the distribution of unevenness at the surface. Specifically, the heights measured at the coordinates where 11 lines parallel to the Y axis, represented by X=15, 65, 115, 165, 215, 265, 315, 365, 415, 465, and 485, intersect with 9 lines parallel to the X axis, represented by Y=15, 65, 115, 165, 215, 265, 315, 365, and 385, respectively, are shown. In this case, the average height was 51 μm (0.051 mm). The standard deviation of the height was 0.062.

[0125] [Table 18]

[0126] Table 19 below shows the heights [μm] of the glass plate from the horizontal plane measured at each coordinate shown in the table when the second mounting configuration was adopted in Example 19. FIG. 20 also shows the distribution of warpage (distribution of irregularities on the non-guaranteed surface) in the same case. In this case, the average height was 67 μm (0.067 mm). The standard deviation of the height was 0.077.

[0127] [Table 19] [Explanation of symbols]

[0128] D1 First peak position D2 Second peak position D3 First peripheral peak position D4 Second peripheral peak position 12 Glass plates for chemical strengthening 12a One main surface 12b Other main surface 12e Periphery

Claims

1. A glass plate for chemical strengthening having a thickness of 0.1 mm or less, The product has a curved shape as a whole or a curved portion in part, The thickness of the glass plate is t [mm], When a first mounting configuration is adopted in which the glass plate is mounted on a horizontal surface with the one main surface facing up, a position on the glass plate that is highest from the horizontal surface is defined as a first peak position, When a 10 mm wide portion along the periphery of the glass plate is defined as the periphery, A glass plate to be chemically strengthened, characterized in that the first peak position is present in a region of the glass plate that is more inward than the peripheral edge portion.

2. When the first mounting configuration is adopted, the height of the highest position from the horizontal plane within the peripheral portion is defined as W 1OUT When expressed in [mm], t 2 / W 1OUT The glass plate for chemical strengthening according to claim 1, wherein the glass plate satisfies the relationship of σ > 0.

005.

3. When the first mounting configuration is adopted, the height of the highest position from the horizontal plane within the peripheral portion is defined as W 1OUT [mm], W 1OUT 3. The glass plate for chemical strengthening according to claim 1, wherein the relationship of ≦0.20 mm is satisfied.

4. When the first mounting configuration is adopted, the height of the highest position from the horizontal plane within the peripheral portion is defined as W 1OUT [mm], W 1OUT The glass plate for chemical strengthening according to any one of claims 1 to 3, wherein the relationship of / t<5 is satisfied.

5. The height of the glass plate from the horizontal plane at the first peak position is defined as W 1MAX When expressed in [mm], W 1MAX The glass plate for chemical strengthening according to any one of claims 1 to 4, characterized in that the relationship of / t<15 is satisfied.

6. 6. The glass plate for chemical strengthening according to claim 1, wherein the one main surface and the other main surface on the back side of the one main surface are fire-polished surfaces.

7. The glass plate for chemical strengthening according to any one of claims 1 to 6, wherein the glass plate has a thickness of 0.05 mm or less.

8. The glass plate for chemical strengthening according to any one of claims 1 to 7, characterized in that the glass plate has a substantially uniform thickness throughout the glass plate.

9. When a second mounting configuration is adopted in which the glass plate is mounted on the horizontal plane with the other main surface on the back side of the one main surface facing up, when a position of the glass plate at a highest height from the horizontal plane is defined as a second peak position, The glass plate for chemical strengthening according to any one of claims 1 to 8, wherein the second peak position is present in a portion of the glass plate that is more inward than the peripheral portion.

10. When the second mounting configuration is adopted, the height of the highest position from the horizontal plane within the peripheral portion is defined as W 2OUT When expressed in [mm], t 2 / W 2OUT The glass plate for chemical strengthening according to claim 9, wherein the glass plate satisfies the relationship of ∫ ...

11. When the second mounting configuration is adopted, the height of the highest position from the horizontal plane within the peripheral portion is defined as W 2OUT When expressed in [mm], W 2OUT The glass plate for chemical strengthening according to claim 9 or 10, which satisfies the relationship of ≦0.20 mm.

12. When the second mounting configuration is adopted, the height of the highest position from the horizontal plane within the peripheral portion is defined as W 2OUT When expressed in [mm], W 2OUT The glass plate for chemical strengthening according to any one of claims 9 to 11, wherein the relationship of / t<5 is satisfied.

13. The height of the glass plate from the horizontal plane at the second peak position is defined as W 2MAX When expressed in [mm], W 2MAX The glass plate for chemical strengthening according to any one of claims 9 to 12, wherein the relationship of / t<15 is satisfied.

14. the glass plate is an aluminosilicate glass, The glass composition is, in mass%, SiO 2 :50~80%, Al 2 O 3 : 5-25%, B 2 O 3 : 0-15%, Na 2 O: 1 to 20%, K 2 The glass plate for chemical strengthening according to any one of claims 1 to 13, characterized in that it contains O: 0 to 10%.

15. The glass plate is an aluminosilicate glass, and the glass composition is, in mass %, SiO 2 60-80%, Al 2 O 3 8-20%, B 2 O 3 0-5%, Na 2 O 4-16%, K 2 The glass plate for chemical strengthening according to claim 14, characterized in that it contains 0.01 to 10% of O.

16. The glass plate is rectangular, The glass plate for chemical strengthening according to any one of claims 1 to 15, wherein the glass plate has a length of 150 mm to 1100 mm and a width of 150 mm to 1300 mm.

17. A method for manufacturing a tempered glass plate, comprising: a preparation step of preparing the glass plate for chemical strengthening according to any one of claims 1 to 16; a cutting step of cutting a product-sized glass plate from the glass plate; and a tempering step of chemically strengthening the product-sized glass plate to obtain a tempered glass plate.

18. A glass plate having a thickness of 0.1 mm or less, The product has a curved shape as a whole or a curved portion in part, When a first mounting configuration is adopted in which the glass plate is mounted on a horizontal surface with the one main surface facing up, a position on the glass plate that is highest from the horizontal surface is defined as a first peak position, When a 10 mm wide portion along the periphery of the glass plate is defined as the periphery, The glass plate, wherein the first peak position is present in a region of the glass plate that is more inward than the peripheral edge portion.

19. When a second mounting configuration is adopted in which the glass plate is mounted on the horizontal plane with the other main surface on the back side of the one main surface facing up, when a position of the glass plate at a highest height from the horizontal plane is defined as a second peak position, The glass plate according to claim 18, wherein the second peak position is present in a region of the glass plate that is more inward than the peripheral edge portion.

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