Glass sheet and method for manufacturing the same

Abstract

To efficiently remove the mating surfaces of glass sheets manufactured by overflow molding.SOLUTION: A method for manufacturing a glass sheet comprises a processing step S5 of manufacturing a glass sheet by subjecting a mother glass sheet G1 to predetermined processing. The processing step S5 comprises a first removal step S52 of removing a first main surface Ga of the mother glass sheet G1; and the first removal step S52 comprises removing the first main surface Ga of the mother glass sheet G1 so that a distance d1 between the mating surface Gd of the mother glass sheet G1 and the center position O1 of the mother glass sheet G1 is larger than before the first removal step S52.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a glass plate and a method for producing the same. [Background technology]

[0002] As is well known, glass plates are used in various fields, including substrates and cover glasses for displays such as liquid crystal displays and organic EL displays, and chemically strengthenable cover glasses used in mobile devices such as smartphones, tablets, and notebook PCs, particularly foldable devices. For the production of this type of glass plate, a known method such as the overflow downdraw method is used.

[0003] In the overflow downdraw method, molten glass is poured into an overflow groove provided on the top of a forming body having a roughly wedge-shaped cross section, and the molten glass overflowing on both sides of the overflow groove is allowed to flow down along both side wall surfaces of the forming body, and then fused and integrated at the lower end of the forming body, thereby continuously forming a glass ribbon (see, for example, Patent Document 1).

[0004] After the glass ribbon has been subjected to a predetermined cooling process, the middle portion of the glass ribbon is cut in the width direction, whereby individual glass sheets are cut out from the glass ribbon. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-80130 Summary of the Invention [Problem to be solved by the invention]

[0006] The molded body used in the overflow downdraw method is made of a refractory material such as an alumina-based or zirconia-based material. In conventional glass sheet manufacturing methods, components contained in the molded body (e.g., Al, Zr, etc.) diffuse and are mixed into the molten glass that contacts and flows down the side wall surface of the molded body. When the molten glass fuses at the lower end of the molded body, the components derived from the molded body remain on the mating surface of the glass ribbon formed by this fusion.

[0007] If the mating surface containing the components derived from the molded body remains on the glass sheet as described above, the function and strength of the glass sheet may be impaired, causing a deterioration in the quality of the glass sheet. For this reason, it has been necessary to remove the mating surface of the glass sheet.

[0008] The present invention has been made in view of the above circumstances, and has as its technical object to efficiently remove the joining surfaces of glass sheets produced by overflow forming. [Means for solving the problem]

[0009] (1) The present invention is intended to solve the above problems, and is a method for manufacturing a glass plate, comprising: a forming step of forming a glass ribbon from molten glass by a forming body that performs overflow forming; a cutting step of cutting a mother glass plate from the glass ribbon; and a processing step of manufacturing a glass plate by performing a predetermined processing on the mother glass plate, wherein the forming body has a pair of side wall surfaces through which the molten glass flows down, and a lower end portion that fuses the molten glass flowing down the pair of side wall surfaces, and the thickness of the mother glass plate is 150 μm or more and 1300 μm or less. The mother glass plate has a first main surface, a second main surface, an end surface connecting the first main surface and the second main surface, and a mating surface formed by fusing the molten glass at the lower end of the molded body, and the processing step includes a first removal step of removing and processing the first main surface of the mother glass plate, and in the first removal step, the first main surface of the mother glass plate is removed so that the distance between the mating surface and the center position of the first main surface and the second main surface in the thickness direction of the mother glass plate is larger than before the first removal step.

[0010] In this method, in the treatment step, the first main surface of the mother glass plate is removed in the first removal step so that the distance between the mating surface and the center position of the glass plate is increased, and the mating surface is positioned biased toward the first main surface side. In this way, by biasing the mating surface in the plate thickness direction of the mother glass plate toward the first main surface side and, for example, simultaneously performing an etching treatment on the first main surface and the second main surface of the mother glass plate, it becomes possible to efficiently remove the mating surface from the mother glass plate.

[0011] (2) In the method for producing a glass plate according to the above (1), in the first removal step, an etching treatment may be performed on the first main surface of the mother glass plate, thereby enabling the mother glass plate to be processed with high accuracy.

[0012] (3) In the method for producing a glass plate according to the above-mentioned (1) or (2), in the first removal step, a groove portion extending parallel to the second main surface may be formed in the end face of the mother glass plate at a position corresponding to the joining surface.

[0013] According to this configuration, by forming the groove on the end face of the mother glass plate, the position of the mating surface in the plate thickness direction of the mother glass plate can be confirmed.

[0014] (4) In the method for producing a glass plate according to any one of (1) to (3) above, in the first removal step, the first main surface of the mother glass plate may be subjected to mechanical polishing or chemical mechanical polishing, thereby enabling the first main surface to be processed efficiently and accurately.

[0015] (5) In the method for producing a glass plate according to any one of (1) to (4) above, a distance between the joining surface of the mother glass plate and the center position of the first main surface and the second main surface of the mother glass plate before the first removal step may be less than 10 μm.

[0016] When overflow molding is performed, the thickness of the molten glass flowing down from one side wall surface of the molded body may differ slightly from that of the molten glass flowing down from the other side wall surface. In this case, the mating surface of the mother glass plate is formed at a position away from the center position in the plate thickness direction of the glass plate. If the distance between the position of the mating surface and the center position of the mother glass plate is large, the warping and distortion of the mother glass plate may worsen. In this method, the distance between the position of the mating surface and the center position of the mother glass plate is less than 10 μm, so that the warping and distortion of the mother glass plate can be reduced as much as possible. Note that "the distance between the mating surface of the mother glass plate and the center position of the first main surface and the second main surface of the mother glass plate before the first removal step is less than 10 μm" also includes the case where the mating surface and the center position coincide with each other before the first removal step.

[0017] (6) In the method for producing a glass plate according to any one of (1) to (5) above, a distance between the joining surface of the mother glass plate and the center position of the first main surface and the second main surface of the mother glass plate after the first removal step may be 15 μm or more.

[0018] According to this configuration, by setting the distance between the mating surface of the mother glass plate and the center position of the mother glass plate after the first removal step to 15 μm or more, it is possible to efficiently remove the mating surface from the mother glass plate, for example, by subsequently simultaneously performing an etching process on the first main surface and the second main surface of the mother glass plate.

[0019] (7) In the method for manufacturing a glass plate described in any one of (1) to (6) above, the treatment step may include a protection step of attaching a protective film to the second main surface of the mother glass plate before the first removal step, and a peeling step of peeling the protective film from the second main surface after the first removal step.

[0020] According to this configuration, by attaching a protective film to the second main surface of the mother glass plate in the protection step, the second main surface can be protected by the protective film in the first removal step. Also, by peeling the protective film from the second main surface of the mother glass plate in the peeling step, the mating surfaces can be efficiently removed by, for example, subsequently performing an etching process on the first and second main surfaces of the mother glass plate.

[0021] (8) In the method for producing a glass plate according to any one of (1) to (7) above, the treatment step may further include a second removal step of performing an etching treatment on the first main surface and the second main surface of the mother glass plate after the first removal step.

[0022] According to this configuration, by performing the second removing step after the first removing step, the mating surface can be efficiently removed from the mother glass plate.

[0023] (9) In the method for producing a glass plate according to the above (8), the thickness of the glass plate after the second removal step is 10 μm or more and 120 μm or less, and the thickness of the mother glass plate before the first removal step is t 0 (μm), and the distance between the joining surface of the mother glass plate and the center position between the first main surface and the second main surface before the first removal step is d 1 (μm), and the thickness of the mother glass plate after the second removal step is t 2 (μm), the removal amount δ in the first removal step 1 (μm), and the removal amount δ in the second removal step 2 (μm) can satisfy formula (1) and formula (2). t 0 =t 2 +δ 1 +2δ 2 (1) (t 0 / 2)+d 1 <δ 1 +δ 2 (2)

[0024] According to this configuration, the mating surface can be reliably removed from the mother glass plate.

[0025] (10) The present invention is intended to solve the above-mentioned problems, and is characterized in that it comprises a glass plate having a thickness of 90 μm or more and 680 μm or less, comprising a first main surface which is a removal processing surface, a second main surface which is a fire polished surface, an end surface connecting the first main surface and the second main surface, and a mating surface formed by fusion of molten glass between the first main surface and the second main surface, and the mating surface is located 15 μm or more away from a center position between the first main surface and the second main surface toward the first main surface in the plate thickness direction.

[0026] According to this configuration, since the mating surface is separated from the center position between the first main surface and the second main surface by 15 μm or more toward the first main surface, it becomes possible to efficiently remove the mating surface from the mother glass plate.

[0027] (11) The present invention is aimed at solving the above-mentioned problems, and is characterized in that it provides a glass plate having a thickness of 90 μm or more and 680 μm or less, comprising: a first main surface which is a removal processing surface; a second main surface which is a fire polished surface; an end surface connecting the first main surface and the second main surface; and a mating surface formed by fusion of molten glass between the first main surface and the second main surface, wherein the end surface has a groove portion extending parallel to the first main surface at a position corresponding to the mating surface, and the groove portion is 15 μm or more away from a center position between the first main surface and the second main surface toward the first main surface in the plate thickness direction.

[0028] According to this configuration, a groove portion corresponding to the position of the mating surface is formed in the edge face of the glass plate, and the position of the groove portion is separated from the center position between the first main surface and the second main surface by 15 μm or more toward the first main surface, which makes it possible to efficiently remove the mating surface from the mother glass plate. Effect of the Invention

[0029] According to the present invention, the joining surfaces of glass sheets produced by overflow forming can be efficiently removed. [Brief description of the drawings]

[0030] [Figure 1] FIG. 2 is a cross-sectional view showing a glass sheet manufacturing apparatus. [Diagram 2] FIG. 2 is a cross-sectional view showing a molded body. [Diagram 3] 1 is a flowchart showing a method for manufacturing a glass plate. [Figure 4] FIG. 4 is a cross-sectional view showing the glass plate after a cutting step. [Diagram 5] 1 is a flowchart showing processing steps in a method for producing a glass plate. [Figure 6] FIG. 11 is a cross-sectional view showing a protection step in the processing steps. [Figure 7] FIG. 2 is a cross-sectional view showing a first removal step in the processing process. [Figure 8] FIG. 2 is a cross-sectional view showing the glass plate after a peeling step in the processing step. [Figure 9]FIG. 2 is a cross-sectional view showing the glass sheet after a second removal step in the processing process. [Figure 10] FIG. 2 is a comparison of a glass plate before and after a processing step. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Figures 1 to 10 show an embodiment of a method for producing a glass plate according to the present invention.

[0032] Fig. 1 shows a manufacturing apparatus for a glass sheet used in this method. The manufacturing apparatus includes a forming device 1 that continuously forms a glass ribbon GR from a molten glass GM, and a cutting device 2 that cuts out a mother glass sheet (hereinafter referred to as a "first glass sheet") G1 from the glass ribbon GR.

[0033] The forming apparatus 1 includes a forming furnace 3 for forming the glass ribbon GR, an annealing furnace 4 for annealing the glass ribbon GR to reduce internal distortion of the glass ribbon GR, a cooling zone 5 for cooling the glass ribbon GR to approximately room temperature, and roller pairs 6 provided in multiple stages above and below each of the forming furnace 3, the annealing furnace 4, and the cooling zone 5. The roller pairs 6 hold both ends of the glass ribbon GR in the width direction, and convey and lower the glass ribbon GR while applying an appropriate tension to the glass ribbon GR.

[0034] A forming body 7 for forming a glass ribbon GR from the molten glass GM by an overflow down-draw method is disposed in the internal space of the forming furnace 3. The forming body 7 is made of, for example, an alumina-based or zirconia-based refractory brick, but the material of the forming body 7 is not limited to that in this embodiment.

[0035] 1 and 2, the forming body 7 has an overflow groove 8 for overflowing the molten glass GM at its upper portion. In addition, the forming body 7 has a pair of side wall surfaces 9, 10 through which the molten glass GM flows down, and a lower end portion 11 through which the molten glass GM flowing down the pair of side wall surfaces 9, 10 is fused.

[0036] Both widthwise ends of the glass ribbon GR formed by the forming apparatus 1 include ears (unnecessary portions) that are thicker than the widthwise central portion due to the influence of shrinkage during the forming process, etc.

[0037] As shown in FIG. 1, the cutting device 2 cuts the glass ribbon GR in a vertical position below the forming device 1 in the width direction at predetermined lengths, thereby sequentially cutting out first glass sheets G1 from the glass ribbon GR.

[0038] The cutting device 2 includes a scribing device (not shown) that forms a scribe line SL1 along the width direction on one surface of the glass ribbon GR, a contact portion 12 that supports the other surface of the glass ribbon GR at a position corresponding to the scribe line SL1, and a stress applying portion 13 that holds a portion of the glass ribbon GR that corresponds to the first glass plate G1 to be cut out (the portion below the scribe line SL1) and applies a bending stress to the scribe line SL1.

[0039] The scribing device includes, for example, a wheel cutter. The scribing device is not limited to the wheel cutter, and may be one that forms the scribe line SL1 by other methods such as laser irradiation.

[0040] The contact unit 12 is composed of a plate-like body (plate) having a contact surface that contacts the surface of the glass ribbon GR along the width direction of the glass ribbon GR while descending following the descending glass ribbon GR. The stress applying unit 13 includes gripping units (e.g., chucks) that grip both ends of the glass ribbon GR in the width direction.

[0041] A method for manufacturing a glass sheet using the manufacturing apparatus having the above configuration will be described below. As shown in Fig. 3, the method includes a forming step S1, an annealing step S2, a cooling step S3, a cutting step S4, and a treatment step S5.

[0042] 1, in the forming step S1, a glass ribbon GR is continuously formed from molten glass GM by a forming device 1. The forming body 7 causes the molten glass GM to overflow from an overflow groove 8 and flow down along side wall surfaces 9, 10 on both sides of the forming body 7.

[0043] Furthermore, the forming body 7 fuses (converges) the flowing molten glass GM at the lower end 11. This forms a glass ribbon GR having a predetermined width. At this time, as shown in Fig. 2, the molten glass GM flowing down one side wall surface 9 of the forming body 7 and the molten glass GM flowing down the other side wall surface 10 of the forming body 7 fuse together, and the fused portion remains inside the glass ribbon GR as a layered mating surface Gd.

[0044] In the annealing step S2, the glass ribbon GR is conveyed downward by a pair of rollers 6 arranged in the annealing furnace 4. A predetermined temperature gradient is set in the annealing furnace 4, and the glass ribbon GR is annealed by passing through the annealing furnace 4. In the cooling step S3 after the annealing step S2, the glass ribbon GR is cooled to near room temperature while passing through a cooling zone 5 arranged below the annealing furnace 4.

[0045] The cutting step S4 includes a first cutting step and a second cutting step. In the first cutting step, the cutting device 2 cuts the middle part of the glass ribbon GR along the width direction to cut out a first glass sheet G1 of a predetermined size. That is, in the first cutting step, a scribe line SL1 along the width direction is formed by a scribing device in the middle part of the glass ribbon GR moving downward (scribing step), and a part of the glass ribbon GR is bent and split along the scribe line SL1 to form a sheet-like first glass sheet G1 (bending and splitting step).

[0046] In the scribing process, the wheel cutter of the scribing device descends following the descending glass ribbon GR, forming a scribe line SL1 in the width direction of the glass ribbon GR. In the bending and splitting process, the stress applying unit 13 performs an operation for bending the glass ribbon GR with the contact unit 12 as a fulcrum, while descending following the descending glass ribbon GR. This operation of the stress applying unit 13 applies a bending stress to the scribe line SL1. As a result, the glass ribbon GR is bent and split in the width direction along the scribe line SL1, and a first glass sheet G1 is cut out from the glass ribbon GR.

[0047] In the second cutting step, an end portion (unnecessary portion) in the width direction of the first glass plate G1 is cut and removed by a cutting device (not shown).

[0048] 4 shows the first glass plate G1 after the second cutting step and before the processing step S5. The first glass plate G1 has a first main surface Ga, a second main surface Gb, an end surface Gc connecting the first main surface Ga and the second main surface Gb, and a joining surface Gd. The thickness t of the first glass plate G1 is 0 The upper limit of the thickness t of the first glass plate G1 is preferably 1,300 μm or less, more preferably 700 μm or less, and further preferably 500 μm or less. 0 The lower limit is preferably 150 μm or more, more preferably 200 μm or more, and further preferably 250 μm or more.

[0049] The first principal surface Ga and the second principal surface Gb of the first glass sheet G1 are formed as fire-polished surfaces by the above-mentioned overflow downdraw method. Here, the "fire-polished surface" refers to a surface formed without contacting the forming body 7 of the forming device 1. Such a fire-polished surface has excellent surface properties despite being unpolished.

[0050] 4, a dashed dotted line indicates an intermediate position between the first principal surface Ga and the second principal surface Gb, i.e., a center line passing through a center position O1 in the thickness direction T of the first glass plate G1. The distance from the center position O1 to the first principal surface Ga is equal to the distance from the center position O1 to the second principal surface Gb.

[0051] The mating surface Gd of the first glass sheet G1 is formed when the glass ribbon GR is formed. As shown in FIG. 4, the mating surface Gd is located away from the center position O1 of the first glass sheet G1. The misalignment between the mating surface Gd and the center position O1 is caused by the difference in thickness between the molten glass GM flowing on one side wall surface 9 of the forming body 7 and the other side wall surface 10 in the forming step S1. The distance d between the mating surface Gd of the first glass sheet G1 and the center position O1 of the first glass sheet G1 is 1 is preferably less than 10 μm, more preferably less than 5 μm. In this example, the distance d 2 is the distance d in the thickness direction T from the mating surface Gd to the second main surface Gb 3 Smaller than (d 2 <d 3 ).

[0052] As shown in FIG. 5, the processing step S5 includes a protection step S51, a first removal step S52, a peeling step S53, and a second removal step S54.

[0053] 6, in the protection step S51, a protection film 14 is attached to the second main surface Gb of the first glass plate G1 before the first removal step S52 is performed. As the protection film 14, for example, a resin film such as a polyethylene film, a polypropylene film, a polyimide film, or an acrylic film is used.

[0054] In the first removal step S52, the distance d between the mating surface Gd and the center position O1 between the first main surface Ga and the second main surface Gb in the sheet thickness direction T is 1 In other words, in the first removal step S52, the first main surface Ga of the first glass plate G1 is removed so that the distance d between the first main surface Ga of the first glass plate G1 and the mating surface Gd becomes large. 2 This first principal surface Ga is removed so that

[0055] In this embodiment, a polishing process is performed as a method for removing the first main surface Ga of the first glass plate G1. Examples of the polishing process include mechanical polishing, chemical mechanical polishing, and chemical polishing. In this embodiment, an example is shown in which the first main surface Ga of the first glass plate G1 is removed by chemical polishing (etching).

[0056] In the first removal step S52, the first main surface Ga of the first glass sheet G1 is subjected to, for example, a wet etching process. The first glass sheet G1 is immersed in an etching solution contained in, for example, an etching tank. As the etching solution, for example, an acidic aqueous solution containing hydrofluoric acid, hydrochloric acid, or the like is used. By this etching process, the first main surface Ga and the end surface Gc of the first glass sheet G1 are removed at a predetermined etching rate. On the other hand, the second main surface Gb of the first glass sheet G1 is protected by the protective film 14, and therefore is not subjected to the etching process. Therefore, the second main surface Gb maintains the state of a fire-polished surface even when the first removal step S52 is performed.

[0057] 7 shows a mother glass plate (hereinafter referred to as a "second glass plate") G2 after the first removal step S52 has been performed. The second glass plate G2 has a first main surface Ga as a removed surface (polished surface) newly formed by the first removal step S52, a second main surface Gb as a fire polished surface, an edge surface Gc newly formed by the first removal step S52, and a mating surface Gd.

[0058] As shown in Fig. 7, the first removal step S52 forms a groove Ge extending parallel to the first principal surface Ga and the second principal surface Gb at a position corresponding to the joining surface Gd on the edge surface Gc of the second glass sheet G2. The joining surface Gd contains a component (e.g. Zr) derived from the formed body 7 mixed into the molten glass GM in the forming step S1. Therefore, in the first removal step S52, the etching rate is different between the portion where the joining surface Gd is formed and the other portion on the edge surface Gc of the first glass sheet G1. The groove Ge is formed in a part of the edge surface Gc of the first glass sheet G1 (second glass sheet G2) according to the difference in etching rate.

[0059] 7, the first removal step S52 forms an inclined surface Gf that is inclined with respect to the second main surface Gb at the boundary between the second main surface Gb and the end surface Gc of the second glass plate G2. The inclined surface Gf is formed by the infiltration of an etching solution between the protective film 14 and the second main surface Gb of the first glass plate G1 in the first removal step S52.

[0060] Thickness t of second glass sheet G2 1 is the thickness t of the first glass plate G1 0 The thickness t of the second glass sheet G2 is smaller than 1 The upper limit of the thickness t of the second glass plate G2 is preferably 680 μm or less, and more preferably 400 μm or less. 1 The lower limit is preferably 90 μm or more, and more preferably 150 μm or more.

[0061] The groove portion Ge is preferably at least 15 μm away from the center position O1 of the second glass plate G2 toward the first main surface Ga in the plate thickness direction T. The distance between the groove portion Ge and the center position O1 of the second glass plate G2 is a distance d between the joining surface Gd of the second glass plate G2 and the center position O1 of the second glass plate G2 after the first removal step S52. 1 This distance d 1 is larger than that before the first removal step S52. 1 The upper limit of the distance d is preferably 300 μm or less, and more preferably 200 μm or less. 1 The lower limit is preferably 15 μm or more, and more preferably 30 μm or more.

[0062] In the second glass sheet G2, the distance d between the joining surface Gd and the first principal surface Ga in the sheet thickness direction T 2 is the distance d before the first removal step S52 2 On the other hand, in the second glass sheet G2, the distance d between the joining surface Gd and the second main surface Gb in the sheet thickness direction T is smaller than 3 is the distance d before the first removal step S52 3 is equal to.

[0063] 8, in the peeling step S53, the protective film 14 is peeled off from the second main surface Gb of the second glass plate G2 after the first removing step S52. In the peeling step S53, the protective film 14 may be peeled off from the second main surface Gb of the second glass plate G2, or the protective film 14 may be removed by an organic solvent.

[0064] In the second removal step S54, after the peeling step S53, an etching process is performed on the first main surface Ga, the second main surface Gb, and the end surface Gc of the second glass plate G2. In this case, the second glass plate G2 may be cut into small glass plates, and each glass plate may be subjected to the etching process. In addition, the inclined surface Gf and the groove portion Ge may be cut out from the second glass plate G2.

[0065] In the second removal step S54, the second glass sheet G2 is immersed in an etching solution in an etching tank, and the first principal surface Ga, the second principal surface Gb, and the edge surface Gc are removed at the same etching rate, thereby removing the mating surface Gd from the second glass sheet G2.

[0066] 9 shows a glass plate (hereinafter referred to as "third glass plate") G3 after the second removal step S54. The third glass plate G3 has a first main surface Ga, a second main surface Gb, and an end surface Gc newly formed by the second removal step S54. The plate thickness t 2 is the thickness t of the second glass plate G2 1 The thickness t of the third glass plate G3 is smaller than 2 The upper limit of the thickness t of the third glass plate G3 is preferably 120 μm or less, and more preferably 90 μm or less. 2 The lower limit is preferably 10 μm or more, and more preferably 25 μm or more.

[0067] This third glass plate G3 is used, for example, as glass substrates for devices such as panel displays such as liquid crystal displays, plasma displays, and organic electroluminescence displays, solar cells, lithium ion batteries, digital signage, touch panels, and electronic paper, or as chemically strengthenable cover glass used in mobile devices such as smartphones, tablets, and notebook PCs, particularly foldable devices, or as cover glass used in bendable thin-film solar cells and organic electroluminescence lighting, and also as glass containers for medical products, window panes, lightweight laminated window glass, and glass for digital signage or glass resin laminates used as protective substrates for protective glasses, etc., but is not limited to these uses.

[0068] The third glass plate G3 is, for example, an alkali aluminosilicate glass, and has a glass composition, in mass %, of SiO 2 50-80%, Al 2 O 3 5~25%, B 2 O 3 0-15%, Na 2 O 1-20%, K 2 O may be contained in an amount of 0 to 10%. In addition, in the case of this composition, Li 2 It is preferable that the material is substantially free of O.

[0069] As another composition example, the third glass plate G3 has a glass composition, in mass%, of SiO 2 40%~70%, Al 2 O 3 10%~30%, B 2 O 3 0%~3%, Na 2 O 5%~25%, K 2 O 0%~5.5%, Li 2 O 0.1%~10%, MgO 0%~5.5%, P 2 O 5 It may contain 2% to 10%.

[0070] The third glass plate G3 may be subjected to a chemical strengthening treatment (strengthening step) after the second removal step S54. The chemical strengthening treatment may involve one stage of ion exchange, or may involve two stages or three or more stages of ion exchange.

[0071] As described above, in order to reliably remove the mating surface Gd of the first glass plate G1, the distance d between the mating surface Gd and the center position O1 is 1 and the amount of removal δ of the first principal surface Ga in the first removal step S52. 1 and the removal amount δ of each of the main surfaces Ga and Gb in the second removal step S54. 2 It is necessary to appropriately control the above.

[0072] Hereinafter, the distance d between the mating surface Gd and the center position O1 in the first removal step S52 and the second removal step S54 will be referred to as 1 and the removal amount δ of each of the main surfaces Ga and Gb. 1 , δ 2 The relationship between the above will be described with reference to FIG.

[0073] Fig. 10(a) shows an example in which the treatment step S5 is performed on a first glass plate G1 whose mating surface Gd is away from the center position O1 toward the first main surface Ga. Fig. 10(b) shows an example in which the treatment step S5 is performed on a first glass plate G1 whose mating surface Gd is away from the center position O1 toward the second main surface Gb. In the example shown in Fig. 10(b), the distance d from the mating surface Gd of the first glass plate G1 to the first main surface Ga is 2 is the distance d from the mating surface Gd to the second principal surface Gb 3 It is larger than that.

[0074] As shown in Fig. 10(a) and (b), the plate thickness t 0 The first main surface Ga of the first glass plate G1 having a removal amount δ 1 The plate thickness t 1 That is, the second glass sheet G2 having the plate thickness t 0 is the sheet thickness t of the second glass sheet G2 after the first removal step S52. 1and the removal amount δ in the first removal step S52 1 It is equal to the sum of (t 0 =t 1 +δ 1 ).

[0075] Plate thickness t 1 The first main surface Ga and the second main surface Gb of the second glass plate G2 having the same removal amount δ 2 The plate thickness t 2 That is, a third glass sheet G3 having a thickness t 0 and the thickness t of the third glass plate G3 2 and each removal amount δ in each removal step S52, S54 1 , δ 2 The relationship is expressed by the following equation (1). t 0 =t 2 +δ 1 +2δ 2 (1)

[0076] In addition, in the first glass sheet G1 before the treatment step S5, the distance in the sheet thickness direction T from the first principal surface Ga or the second principal surface Gb to the mating surface Gd is (t 0 / 2)+d 1 In order to remove the mating surface Gd from the first glass plate G1, the amount (thickness) δ of glass removed from the first principal surface Ga in each of the removing steps S52 and S54 is 1 , δ 2 This distance (t 0 / 2)+d 1 That is, the condition for reliably removing the mating surface Gd by the first removal step S52 and the second removal step S54 is expressed by the following formula (2). (t 0 / 2)+d 1 <δ 1 +δ 2 (2)

[0077] According to the present embodiment described above, in the first removal step S52 of the processing step S5, the first principal surface Ga of the first glass plate G1 is removed so that the distance between the mating surface Gd and the center position O1 of the first glass plate G1 becomes large, and thus the mating surface Gd is positioned biased toward the first principal surface Ga.

[0078] By distributing the mating surface Gd toward the first principal surface Ga in the thickness direction T of the first glass sheet G1 in this manner, the first principal surface Ga and the second principal surface Gb of the second glass sheet G2 are simultaneously etched in the second removal step S54, thereby making it possible to reliably and efficiently remove the mating surface Gd from the second glass sheet G2. This makes it possible to efficiently produce a high-strength third glass sheet G3 that does not have a mating surface Gd.

[0079] The present invention is not limited to the configuration of the above embodiment, nor is it limited to the above-mentioned effects and advantages. Various modifications of the present invention are possible without departing from the spirit and scope of the present invention.

[0080] In the above embodiment, the first removing step S52 and the second removing step S54 are performed in the same processing factory, but the present invention is not limited to this configuration. For example, the method may include a conveying step (transporting step) of conveying the second glass sheet G2 to a processing factory (a factory performing the second removing step S54) other than the processing factory performing the first removing step S52 after performing the first removing step S52.

[0081] In the above embodiment, the first removal step S52 of the processing step S5 is performed by etching, but the present invention is not limited thereto. When the first removal step S52 is performed by mechanical polishing, the first main surface Ga of the first glass plate G1 can be removed by a polishing tool such as a grindstone. When the first removal step S52 is performed by chemical mechanical polishing, the first main surface Ga of the first glass plate G1 can be removed by an abrasive such as cerium oxide powder.

[0082] In the above embodiment, the first glass sheet G1 is immersed in the etching solution in the etching tank in the first removal step S52 of the processing step S5, but the present invention is not limited to this configuration. In the first removal step S52, the etching solution may be applied to the first main surface Ga of the first glass sheet G1 by spraying, showering, or the like while the first glass sheet G1 is transported in a horizontal or vertical position.

[0083] In the above embodiment, an acidic aqueous solution is used as the etching solution in the first removal step S52 of the processing step S5, but the present invention is not limited to this configuration. An alkaline aqueous solution such as a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution may also be used.

[0084] In the above embodiment, the distance between the mating surface Gd and the center position O1 before the first removal step S52 is d 1 However, the present invention is not limited to this configuration. The mating surface Gd and the center position O1 before the first removal step S52 may coincide with each other. [Explanation of symbols]

[0085] 7 Molded body 9 Side wall 10 Side wall 11 Lower end 14 Protective film d 1 Distance between the mating surface and the center position G1 First glass plate G2 Second glass plate G3 Third Glass Pane Ga first principal surface Gb second principal surface Gc end face Gd mating surface Ge Groove GM Molten Glass GR Glass Ribbon O1: Center position between the first and second principal surfaces S1 Molding process S2 cutting process S5 Processing S51 Protection process S52 First removal process S53 stripping process S54 Second removal process T Plate thickness direction

Claims

1. A method for producing a glass plate, comprising: a forming step of forming a glass ribbon from molten glass using a forming body that performs overflow forming; a cutting step of cutting a mother glass plate from the glass ribbon; and a processing step of manufacturing a glass plate by performing a predetermined processing on the mother glass plate, The molding body has a pair of side wall surfaces through which the molten glass flows down, and a lower end portion through which the molten glass flowing down the pair of side wall surfaces is fused, The thickness of the mother glass plate is 150 μm or more and 1300 μm or less, The mother glass plate has a first main surface, a second main surface, an end surface connecting the first main surface and the second main surface, and a joining surface formed by fusing the molten glass at the lower end of the molding body, The processing step includes a first removal step of removing the first main surface of the mother glass plate, a first removal step of removing the first main surface of the mother glass plate such that a distance between the joining surface and a center position of the first main surface and the second main surface in a thickness direction of the mother glass plate is larger than that before the first removal step.

2. The method for manufacturing a glass plate according to claim 1 , wherein in the first removal step, an etching treatment is performed on the first main surface of the mother glass plate.

3. The method for manufacturing a glass plate according to claim 2 , characterized in that in the first removal step, a groove portion extending parallel to the second main surface is formed in the end face of the mother glass plate at a position corresponding to the joining surface.

4. The method for producing a glass plate according to claim 1 , wherein in the first removal step, the first main surface of the mother glass plate is subjected to mechanical polishing or chemical mechanical polishing.

5. 5. The method for manufacturing a glass plate according to claim 1, wherein a distance between the joining surface of the mother glass plate and the center position between the first main surface and the second main surface of the mother glass plate before the first removal step is less than 10 μm.

6. 5. The method for manufacturing a glass plate according to claim 1, wherein a distance between the joining surface of the mother glass plate and the center position between the first main surface and the second main surface of the mother glass plate after the first removal step is 15 μm or more.

7. 5. The method for manufacturing a glass plate according to claim 1, wherein the processing step includes a protection step of attaching a protective film to the second main surface of the mother glass plate before the first removal step, and a peeling step of peeling the protective film from the second main surface after the first removal step.

8. The method for manufacturing a glass plate according to claim 6 , characterized in that the processing step further includes a second removal step of performing an etching process on the first main surface and the second main surface of the mother glass plate after the first removal step.

9. The thickness of the glass plate after the second removal step is 10 μm or more and 120 μm or less, The thickness of the mother glass plate before the first removal step is t ０ (μm), and the distance between the joining surface of the mother glass plate before the first removal step and the center position between the first main surface and the second main surface is d １ (μm), and the thickness of the mother glass plate after the second removal step is t ２ (μm), the removal amount δ in the first removal step １ (μm), and the removal amount δ in the second removal step ２ The method for producing a glass plate according to claim 8, characterized in that (μm) satisfies formula (1) and formula (2). t ０ =t ２ +δ １ +2δ ２ ・・・(1) (t) ０ / 2)+A １ <d １ +d ２ ・・・(2)

10. A glass plate having a plate thickness of 90 μm or more and 680 μm or less, The glass mold has a first main surface which is a removal processing surface, a second main surface which is a fire polished surface, an end surface which connects the first main surface and the second main surface, and a mating surface formed by fusion of molten glass between the first main surface and the second main surface, The glass plate, wherein the joining surface is spaced from a center position between the first main surface and the second main surface by 15 μm or more toward the first main surface in a plate thickness direction.

11. A glass plate having a plate thickness of 90 μm or more and 680 μm or less, The glass mold has a first main surface which is a removal processing surface, a second main surface which is a fire polished surface, an end surface which connects the first main surface and the second main surface, and a mating surface formed by fusion of molten glass between the first main surface and the second main surface, The end surface includes a groove portion extending parallel to the first main surface at a position corresponding to the mating surface, The glass plate, wherein the groove portion is located 15 μm or more away from a center position between the first main surface and the second main surface toward the first main surface in a plate thickness direction.

12. A preparation step of preparing a glass plate according to claim 10 or 11; a second removal step of performing an etching treatment on the first main surface and the second main surface of the glass plate.

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