Glass plate, method for manufacturing glass plate, and device for manufacturing glass plate

Abstract

The rectangular glass plate (1) has a first side (1y) along the plate pulling direction (Y) and a second side (1x) along the width direction (X), the lengths of the first side (1y) and the second side (1x) are 1000 mm or more, and the plate thickness of the glass plate (1) is 0.1 mm to 2.0 mm (inclusive). When five evaluation regions (A-E) having rectangular shapes of the same size are sequentially set from one end side in the width direction (X), the absolute value of the average value of the front and back deflection differences (X1-X2) in the width direction (X) of these evaluation regions (A-E) is 0.06-0.8 mm.

Description

Technical Field

[0001] The present invention relates to a glass sheet in a curved shape and a manufacturing technology thereof. Background Art

[0002] In the manufacturing process of electronic devices such as panel displays (for example, liquid crystal displays, organic EL displays, and plastic organic EL displays), a film forming process of forming a film on a glass plate (mother glass) is performed.

[0003] As an example of the film forming process, according to Patent Document 1, a technology is disclosed in which a metal film is formed on the convex surface of a glass plate having a dome-shaped or bowl-shaped curved shape by a film forming process accompanied by heating to produce a thin film device, and the thin film device is cooled (including natural cooling) to near room temperature.

[0004] According to this method, while the thin film device having the metal film formed thereon is being cooled, tensile stress acts on the metal film because the thermal expansion coefficient of the metal film is larger than that of the glass plate, and it is expected that the shape of the glass plate and thus the thin film device can be flattened.

[0005] In addition, this document discloses, as a method for producing a curved glass sheet, adjusting a thermal curve and a thermal history during forming of a glass ribbon by an overflow down-draw method or the like.

[0006] Furthermore, this document discloses that in order to know the shape of a glass sheet cut out from the glass ribbon, the shape of the glass sheet is measured in a zero-gravity state.

[0007] On the other hand, Patent Document 2 discloses the concept of introducing the front and back deflection difference in evaluating the curved shape of a glass plate.

[0008] Specifically, the document discloses setting a plurality of evaluation areas on a glass plate, determining the front and back deflection difference by measuring the deflection of sample glasses corresponding to these areas, and evaluating the curved shape of the glass plate based on the front and back deflection difference.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent Application No. 2018-506497

[0012] Patent Document 2: International Publication No. 2022 / 097537 Summary of the invention

[0013] Problems to be solved by the invention

[0014] In addition, Patent Document 1 discloses only a general structure of manufacturing a glass sheet by an overflow down-draw method as a manufacturing apparatus for a curved glass sheet (see FIG. 13 of the document). Therefore, it is difficult to obtain a glass sheet with an appropriate curved shape for performing a film-forming process accompanied by heating simply by adjusting the thermal curve and thermal history during the forming of the glass ribbon as described above.

[0015] Here, the film forming process involving heating refers to, for example, a process of applying a film material on the main surface of a glass plate and then firing to harden the film material. In the following description, "film forming process involving heating" is simply referred to as "heating film forming process".

[0016] In addition, as disclosed in Patent Document 1, when the shape of a glass plate is measured in a zero-gravity state, there is a risk of large measurement errors, and measurement and post-processing take time, making it difficult to accurately and quickly measure the shape of the glass plate and obtain a glass plate with a suitable curved shape for performing a heat film-forming process.

[0017] Furthermore, a glass sheet formed by a down-draw method or a float method has a drawing direction and a width direction orthogonal thereto, but the drawing direction and the width direction are not distinguished when measuring and evaluating a glass sheet in Patent Document 1. Therefore, the measurement and evaluation are insufficient to obtain a glass sheet having an appropriate curved shape for performing a heat film forming process.

[0018] On the other hand, in Patent Document 2, the plate pulling direction and the width direction are distinguished for measurement and evaluation, but the technical solution disclosed in the document enables the adsorption platform to properly adsorb the convex surface of the curved glass plate. Therefore, even if the technical solution disclosed in the document is applied to the technical solution of performing a heating film forming process on the curved glass plate, an appropriate structure and effect cannot be obtained.

[0019] In addition, the present inventors have conducted a study in which a resin film is formed on the convex surface of a curved glass plate by a heat film forming process, and after the glass plate is flattened by cooling, the resin film is peeled off from the glass plate, and the film is used in the manufacture of electronic devices. In this study, if the shape of the glass plate is not flattened when it is cooled to near room temperature, it becomes difficult to peel off the resin film from the glass plate. Therefore, in this case, it is also important to obtain a glass plate with an appropriate curved shape for performing the heat film forming process.

[0020] From the above viewpoints, an object of the present invention is to provide a glass sheet having an appropriate curved shape for performing a heat film-forming process and a technology for producing the same.

[0021] Solutions to Solve Problems

[0022] (a) A first aspect of the present invention made to solve the above-mentioned problems is a glass plate having a rectangular shape, having a first main surface and a second main surface on the back side of the first main surface, and having a first side along a plate pulling direction and a second side along a width direction orthogonal to the plate pulling direction, wherein the length of the first side and the second side is 1000 mm or more, and the plate thickness of the glass plate is 0.1 mm or more and 2.0 mm or less, and the glass plate is characterized in that:

[0023] When five rectangular evaluation areas of the same size are set in order from one end in the width direction, the absolute value of the average value of the front and back deflection differences in the width direction of the five evaluation areas calculated by the following formula (1) is 0.06 mm or more and 0.8 mm or less.

[0024] Deflection difference between front and back = (X1 - X2) (1)

[0025] X1: Deflection in the width direction when the first main surface is facing downward, of the sample glass corresponding to the evaluation area for measuring the front and back deflection difference [mm]

[0026] X2: Deflection in the width direction when the second main surface is facing downward, of the sample glass corresponding to the evaluation area for measuring the difference in front and back deflection [mm]

[0027] According to this structure, the glass plate has a curved shape in which the main surface of either the first main surface or the second main surface is convex in the width direction. In addition, the absolute value of the average value of the above-mentioned front and back deflection difference is greater than 0.06 mm and less than 0.8 mm, so the curvature of the glass plate in the width direction is large. Therefore, in the case where the convex surface of the glass plate is subjected to a heat film forming treatment, even if the thermal expansion coefficient of the film is much larger than that of the glass plate, the shape of the glass plate can be flattened at the time of cooling to near room temperature. Therefore, it is possible to avoid the situation where the shape of the glass plate becomes an inappropriate curved shape due to the thermal expansion difference between the film and the glass plate even when cooled to near room temperature. Thus, a glass plate with an appropriate curved shape for the heat film forming treatment can be obtained.

[0028] (b) In the configuration of (a) above, preferably, an average value of the difference in front and back deflection in the width direction of the five evaluation areas is 0.15 mm or more.

[0029] In this manner, a glass sheet having an appropriate curved shape for performing a thermal film-forming process can be obtained more reliably.

[0030] (c) In the configuration of (a) or (b) above, preferably, the average value of the front and back deflection differences in the width direction of the five evaluation areas is positive, and the front and back deflection differences in the width direction of the five evaluation areas are all -0.2 mm to 1.0 mm.

[0031] In this way, the glass plate has a curved shape in which the first main surface becomes a convex surface because the average value of the above-mentioned front and back deflection difference is positive (a value greater than 0). In addition, the above-mentioned front and back deflection differences are all greater than -0.2 mm and less than 1.0 mm, so the deviation of the front and back deflection difference in the width direction of the glass plate can be reduced. As a result, the first main surface can be set as a convex surface that is smoothly curved over the entire length or approximately the entire length in the width direction. Therefore, in the case where the glass plate is used to form a film on the first main surface to produce a device with a film, the first main surface is appropriately subjected to a heating film-forming treatment, and a high-quality device with a film is obtained. In addition, in the case where the glass plate is used to peel off a film from a glass plate with a film obtained by forming a film on the first main surface, in addition to the appropriateness of the heating film-forming treatment, the film peeling operation can also be appropriately performed.

[0032] (d) In the configuration of (c) above, preferably, the first main surface is a guaranteed surface, and the second main surface is a non-guaranteed surface.

[0033] In this way, a film can be formed on the guaranteed surface of the glass plate, which is a preferred embodiment.

[0034] (e) In any one of the above structures (a) to (d), preferably, the difference between the maximum value and the minimum value of the front and back deflection difference in the width direction of the five evaluation areas is 2.0 mm or less.

[0035] Thus, the deviation of the front and back deflection difference in the width direction of the glass plate can be more reliably reduced. Therefore, the convex surface of the glass plate can be made to be smoothly curved over the entire length or substantially the entire length in the width direction, and the same advantages as described above can be further reliably obtained.

[0036] (f) In any one of the above structures (a) to (e), it is preferred that the linear thermal expansion coefficient at 30 to 380°C is 30×10 -7 / ℃ and above 50×10 -7 / ℃ below.

[0037] Here, a polyimide resin film is sometimes formed on the convex surface of the glass plate of the first aspect of the present invention. In this case, the linear thermal expansion coefficient of the resin film is within the above-mentioned numerical range. Therefore, the shape of the glass plate when cooled to near room temperature can be more reliably flattened by appropriately coping with the thermal expansion difference between the resin film and the glass plate.

[0038] (g) In any one of the above structures (a) to (f), preferably, the thermal shrinkage rate when held at 500° C. for 1 hour is 30 ppm or less.

[0039] In this way, the shrinkage (compression) of the glass plate when the convex surface of the glass plate is subjected to a heat film forming process is suppressed. This characteristic is particularly required for high-definition displays. Therefore, according to the structure here, the glass plate can be suitably used for high-definition displays.

[0040] (h) In any one of the above structures (a) to (g), preferably, the transmittance in the plate thickness direction at a wavelength of 308 nm is 60% or more and 85% or less.

[0041] Here, sometimes a polyimide resin film is formed on the convex surface of the glass plate of the first aspect of the present invention by a heating film-forming process, and in this case, the glass plate is sometimes used for the purpose of peeling a film from a glass plate with a film obtained by forming a film on the glass plate. In this case, as a method for peeling the polyimide resin film from the glass plate, an ultraviolet laser is sometimes used. In this case, considering that the wavelength of the ultraviolet laser is 308nm, the glass plate has an appropriate transmittance in the plate thickness direction in this wavelength region. Thus, the operation of peeling the polyimide resin film from the glass plate can be appropriately and reliably performed.

[0042] (i) In any one of the structures (a) to (h) above, it is preferred that the glass composition contains 60 to 70% by mol% of SiO 2 9.5-17% Al 2 O 3 , 0~9% B 2 O 3 , 0% or more and less than 1% Li 2 O+Na 2 O+K 2 O, 0-8% MgO, 2-15% CaO, 0-10% SrO, 0.1-5% BaO.

[0043] In this way, the liquid phase viscosity and Young's modulus can be increased.

[0044] (j) In any one of the structures (a) to (h) above, it is preferred that the glass composition contains 62 to 72% SiO in mol%. 2 9.5-16% Al 2 O 3 1-8% B 2 O 3 , 0% or more and less than 1% Li 2 O+Na 2 O+K2 O, 1-9% MgO, 2-10% CaO, 0.1-5% SrO, 0.1-5% BaO.

[0045] In this way, the liquid phase viscosity and Young's modulus can be increased.

[0046] (k) In any one of the structures (a) to (h) above, it is preferred that the glass composition contains 67 to 77% SiO in mol%. 2 , 9~14%Al 2 O 3 , 0-3% B 2 O 3 , 0% or more and less than 1% Li 2 O+Na 2 O+K 2 O, 0-5% MgO, 0-10% CaO, 0-5% SrO, 0-7% BaO.

[0047] In this way, the strain point can be easily increased to 730° C. or higher.

[0048] (l) A second aspect of the present invention made to solve the above-mentioned problems is a method for manufacturing a glass plate, comprising: a forming step of forming a glass ribbon from molten glass; an annealing step of annealing the glass ribbon while being conveyed by a conveying device; and a cutting step of cutting the annealed glass ribbon into a rectangular glass plate, wherein the glass plate manufacturing method is characterized in that the glass ribbon has a first main surface and a second main surface on the back side of the first main surface, and the plate thickness is not less than 0.1 mm and not more than 2.0 mm, and in the annealing step, both ends of the glass ribbon in the width direction are supported from the first main surface side and the second main surface side by a plurality of roller pairs in the conveying device, and at least one position in the conveying direction of the glass ribbon in the conveying device, both ends of the glass ribbon in the width direction are supported only from the second main surface side by a deflection roller deflected toward the first main surface side of the glass ribbon.

[0049] According to this structure, the glass sheet of the first aspect of the present invention described above can be appropriately manufactured. Specifically, according to this manufacturing method, for example, compared with the case where the two ends of the glass ribbon in the width direction are supported from both main surface sides by a pair of deflection rollers deflected toward the first main surface side of the glass ribbon at at least one portion of the conveying path, a glass ribbon and thus a glass sheet having an appropriate curved shape can be obtained. That is, in the case where the two ends of the glass ribbon in the width direction are supported from both main surface sides by a pair of deflection rollers, even if the shape is curved in the middle part of the width direction of the glass ribbon so that the first main surface becomes a convex surface, the two ends in the width direction are clamped by the pair of deflection rollers and become a flat shape. In contrast, in the case where the two ends of the glass ribbon in the width direction are supported only from the second main surface side by the deflection rollers, the two ends in the width direction are not clamped, so not only the middle part in the width direction but also the two ends in the width direction become a shape curved toward the first main surface side. As a result, a glass sheet having the same advantages as the glass sheet of the first aspect of the present invention described above can be obtained.

[0050] (m) In the configuration of (l) above, preferably, the first main surface is a guaranteed surface, and the second main surface is a non-guaranteed surface.

[0051] In this manner, a glass sheet having a curved shape in which the secured surface is a convex surface can be obtained, and thus a film can be formed on the secured surface, which is a preferred embodiment.

[0052] (n) In the configuration of (l) or (m) above, it is preferred that the deflection amount of the deflection roller is 1 mm or more and 20 mm or less.

[0053] In this manner, the degree of curvature in the width direction of the obtained glass sheet can be sufficiently increased.

[0054] (o) A third aspect of the present invention, which is made to solve the above-mentioned problems, is a glass plate manufacturing device, comprising: a forming furnace, which forms a glass ribbon having a first main surface and a second main surface on the back side of the first main surface from molten glass; an annealing furnace, which anneals the glass ribbon while being conveyed by a conveying device; and a cutting device, which cuts the annealed glass ribbon into a rectangular glass plate, the glass plate manufacturing device being characterized in that the conveying device comprises: a plurality of roller pairs, which support both end portions of the glass ribbon in the width direction from the first main surface side and the second main surface side; and a deflection roller, which is arranged at at least one portion of the conveying path of the glass ribbon and is deflected toward the first main surface side of the glass ribbon and supports both end portions of the glass ribbon in the width direction only from the second main surface side.

[0055] According to this manufacturing apparatus, the manufacturing method according to the second aspect of the present invention described above can be implemented, and thus substantially the same operational effects as those of the manufacturing method can be obtained.

[0056] Effects of the Invention

[0057] According to the present invention, a glass sheet having an appropriate curved shape for performing a thermal film-forming process and a technology for producing the same are provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is a top view which shows the glass plate which concerns on embodiment of this invention.

[0059] Figure 2 It is a plan view for explaining a method for measuring the difference in front and back deflection in the width direction of a sample glass cut out from a glass plate.

[0060] Figure 3 It is observed from the direction of arrow I. Figure 2 Side view of a sample glass having a difference in front and back deflection when measured using the method shown.

[0061] Figure 4 It is a plan view for explaining a method for measuring the difference in front and back deflection in the pulling direction of a sample glass cut out from a glass plate.

[0062] Figure 5 It is observed from the direction of arrow II. Figure 4 Side view of a sample glass having a difference in front and back deflection when measured using the method shown.

[0063] Figure 6 This is a longitudinal sectional side surface for explaining a usage example of the glass plate according to the embodiment of the present invention.

[0064] Figure 7 It is a longitudinal sectional side view which shows the schematic structure of the manufacturing apparatus of the glass plate which concerns on embodiment of this invention.

[0065] Figure 8 This is a longitudinal sectional front view showing the schematic structure of the manufacturing apparatus of the glass plate according to the embodiment of the present invention, and is viewed from the right side. Figure 7 Figure 2. A diagram of the manufacturing device.

[0066] Fig. 9 It is an enlarged longitudinal sectional side view which shows the main part of the manufacturing apparatus of the glass sheet and the shape of the glass ribbon which concerns on embodiment of this invention.

[0067] Fig.10 is in accordance with Fig. 9 A cross-sectional top view taken along the D-D line.

[0068] Fig.11It is an enlarged longitudinal sectional side view showing the main part of the manufacturing apparatus of the glass sheet and the shape of the glass ribbon for explaining the conventional problems.

[0069] Fig.12 is in accordance with Fig.11 A cross-sectional top view taken along line E-E. DETAILED DESCRIPTION

[0070] Hereinafter, a glass plate, a glass plate manufacturing apparatus, and a glass plate manufacturing method according to embodiments of the present invention will be described with reference to the drawings.

[0071] <Glass plate>

[0072] like Figure 1 As shown, the glass sheet 1 of this embodiment is manufactured by a known forming method such as overflow down-draw method, slot down-draw method, re-draw method, float method, etc. In this embodiment, a glass ribbon is formed by overflow down-draw method, and a glass sheet 1 of a predetermined size is obtained by cutting out the glass ribbon.

[0073] The glass sheet 1 has a first side 1y along a drawing direction Y and a second side 1x along a width direction X orthogonal to the drawing direction Y. The drawing direction Y of the glass sheet 1 can be observed as a stripe pattern by, for example, irradiating light from a light source (e.g., a xenon lamp) while adjusting the angle of the glass sheet 1 in a dark room and projecting the transmitted light onto a screen. Therefore, even for the cut glass sheet 1, the drawing direction Y during forming can be determined.

[0074] The first main surface of the glass plate 1 is a guaranteed surface 1a, and the second main surface on the back side of the first main surface of the glass plate 1 is a non-guaranteed surface 1b. The guaranteed surface 1a is guaranteed to have a predetermined quality, and is kept in a non-contact state as much as possible during each process such as transportation and processing of the glass plate 1. In contrast, the non-guaranteed surface 1b becomes a contact surface with which a transport device or the like contacts during each process such as transportation or processing.

[0075] As the glass plate 1, for example, a low-alkali glass plate for a display can be cited. Here, as a "display", for example, a liquid crystal display, an organic EL display, a plastic organic EL display, etc. can be cited. In addition, "low-alkali glass" means glass with a small amount of alkali components (alkali metal oxides) or glass that substantially does not contain alkali components.

[0076] As a specific composition of the low-alkali glass, it is preferred that 60 to 75% of SiO is contained in mol%. 2 , 5~20%Al 2 O 3 , 0~15% B 2 O 3 , 0% or more and less than 1% Li2 O+Na 2 O+K 2 O(Li 2 O、Na 2 O and K 2 O), 0-10% MgO, 0-15% CaO, 0-10% SrO, and 0-10% BaO. Among them, the following glass composition examples are particularly preferred.

[0077] As an example of the first glass composition, 60 to 70% SiO is contained in mol%. 2 , 9.5-17% (especially 11-15%) Al 2 O 3 , 0-9% (especially 5-7%) B 2 O 3 , 0% or more and less than 1% (especially 0 to 0.5%) of Li 2 O+Na 2 O+K 2 O, 0-8% (especially 2-6%) MgO, 2-15% (especially 6-11%) CaO, 0-10% (especially 0.1-3%) SrO, 0.1-5% BaO. In this way, the liquidus viscosity and Young's modulus can be increased.

[0078] As an example of the second glass composition, 62 to 72% SiO is contained in mol%. 2 , 9.5-16% (especially 11-15%) Al 2 O 3 1-8% (especially 2-4%) B 2 O 3 , 0% or more and less than 1% (especially 0 to 0.5%) of Li 2 O+Na 2 O+K 2 O, 1-9% (especially 4-8%) MgO, 2-10% (especially 3-8%) CaO, 0.1-5% (especially 1-3%) SrO, 0.1-5% (especially 1-3%) BaO. In this way, the liquidus viscosity and Young's modulus can be increased.

[0079] As an example of the third glass composition, 67 to 77% SiO is contained in mol%. 2 , 9~14%Al 2 O 3 , 0-3% (especially 0% or more and less than 1%) B 2 O 3 , 0% or more and less than 1% (especially 0 to 0.5%) of Li 2 O+Na2 O+K 2 O, 0-5% (especially 2-5%) MgO, 0-10% (especially 6-9%) CaO, 0-5% SrO, 0-7% (especially 3-6%) BaO. In this way, the strain point can be easily increased to 730°C or more.

[0080] SiO 2 It is a component that forms the skeleton of glass, and it is also a component that increases the strain point and acid resistance. 2 When the content is high, in addition to the high-temperature viscosity becoming higher and the solubility decreasing, devitrified crystals such as cristobalite are more likely to precipitate, and the liquidus temperature becomes higher.

[0081] Al 2 O 3 It is a component that forms the skeleton of glass, and it is also a component that increases the strain point and the Young's modulus. 2 O 3 When the content is high, mullite and feldspar-based devitrified crystals are likely to precipitate, and the liquidus temperature becomes higher.

[0082] B 2 O 3 It is a component that improves melting properties and resistance to devitrification. 2 O 3 When the content of is high, the strain point and Young's modulus are lowered, so that the heat shrinkage rate is increased and the pitch deviation in the panel production process is likely to occur.

[0083] MgO is a component that reduces high temperature viscosity, improves melting properties, and increases Young's modulus. On the other hand, when the content of MgO is high, the precipitation of mullite, crystals derived from Mg and Ba, and crystals of cristobalite is promoted. In addition, when the content of MgO is high, the strain point is significantly reduced.

[0084] CaO is a component that significantly improves the solubility without lowering the strain point and reducing the high temperature viscosity. In addition, CaO is a component that reduces the raw material cost because it is relatively cheap to introduce raw materials into alkaline earth metal oxides. It is also a component that improves Young's modulus. In addition, CaO has the effect of suppressing the precipitation of devitrified crystals containing the above-mentioned Mg. On the other hand, when the content of CaO is large, devitrified crystals of calcium feldspar are easily precipitated, and the density is easily increased.

[0085] SrO is a component that suppresses phase separation and improves resistance to devitrification. It is also a component that does not lower the strain point and reduces high-temperature viscosity, thereby improving melting properties. On the other hand, when the content of SrO is high, feldspar-based devitrification crystals are easily precipitated in a glass system that contains a lot of CaO, and resistance to devitrification is easily reduced. Moreover, when the content of SrO is high, there is a tendency for the density to increase or the Young's modulus to decrease.

[0086] BaO is a component that has a high effect of suppressing the precipitation of mullite-based and anorthite-based devitrified crystals among alkaline earth metal oxides. On the other hand, when the content of BaO is high, the density increases or the Young's modulus tends to decrease, and the high-temperature viscosity becomes too high and the meltability tends to decrease.

[0087] The length of the first side 1y and the length of the second side 1x of the glass plate 1 are both 1000 mm or more, preferably 1200 mm or more, and more preferably 1500 mm or more. In addition, their lengths are 4000 mm or less, preferably 3000 mm or less, and more preferably 2000 mm. In this embodiment, the length of the first side 1y is 1500 mm, and the length of the second side 1x is 1850 mm.

[0088] The thickness of the glass plate 1 is 0.1 mm or more, preferably 0.2 mm or more, more preferably 0.3 mm or more, further preferably 0.4 mm or more, and most preferably 0.5 mm or more. In addition, the thickness of the glass plate 1 is 2.0 mm or less, preferably 1.8 mm or less, more preferably 1.5 mm or less, further preferably 1.2 mm or less, and most preferably 0.9 mm or less.

[0089] The shape of the glass plate 1, here, the shape of the glass plate 1 along the width direction X can be evaluated using the front and back deflection difference. Hereinafter, a method for evaluating the shape of the glass plate 1 along the width direction X using the front and back deflection difference X1-X2 will be described.

[0090] like Figure 1As shown, five rectangular evaluation areas A, B, C, D, and E with different positions in the width direction X are set for a glass plate 1. Each evaluation area A to E is set in sequence from one end side of the width direction X. Evaluation areas B, C, and D are arranged in a row along the width direction X without gaps. In addition, the positions of evaluation areas A and E in the plate pulling direction Y are different from those of evaluation areas B to D. The position of evaluation area A in the width direction X partially overlaps with evaluation area B, and the position of evaluation area E in the width direction X partially overlaps with evaluation area D. The five evaluation areas A to E in this embodiment are set over the entire length from one end side to the other end side of the width direction X of the glass plate 1. Here, the five evaluation areas A to E are all rectangular in shape with a length of 400 mm for the side 2x along the width direction X and a length of 500 mm for the side 2y along the plate pulling direction Y.

[0091] The sample glass 3 (see FIG. 1 ) as a glass piece having a position and a size corresponding to each evaluation area A to E is extracted from the glass plate 1 . Figure 2 as well as Figure 4 ), five sample glasses 3 corresponding to the evaluation areas A to E are obtained for one glass plate 1. That is, the sample glass 3 has an edge 3y along the drawing direction Y corresponding to the edge 2y of the evaluation areas A to E and an edge 3x along the width direction X corresponding to the edge 2x of the evaluation areas A to E.

[0092] After five sample glasses 3 are prepared in this manner, the front and back deflection differences X1-X2 in the width direction X of each sample glass 3 are measured. Figure 2 As shown, with the guaranteed surface 3a of the sample glass 3 (the surface on the same side as the guaranteed surface 1a of the glass plate 1) facing downward, the two ends of the sample glass 3 in the width direction X are supported by a pair of supporting members 4. At this time, the supporting span M of the pair of supporting members 4 supporting the sample glass 3 is set to 380 mm when the length of the side 3x along the width direction X is 400 mm and the length of the side 3y along the pulling direction Y is 500 mm, and is set to a value obtained by subtracting 20 mm from the length of the side 3x along the width direction X of the sample glass 3 in other cases. In this state, as Figure 3 As shown, the magnitude of the first deflection X1 (the state shown by the solid line in the figure) in the width direction X of the sample glass 3 is measured. In this measurement, the first deflection X1 is measured for each of the two parallel sides 3x along the width direction X of the sample glass 3, and the larger of the two is adopted as the first deflection X1. The magnitude of the adopted first deflection X1 is converted to the first deflection X1 when the support span M is 350 mm. For example, when the support span M is M1 (arbitrary value) mm, it is converted by X1×(350 / M1).

[0093] Similarly, the sample glass 3 is turned upside down with the non-guaranteed surface 3b of the sample glass 3 (the surface on the same side as the non-guaranteed surface 1b of the glass plate 1) facing downward, and the two ends of the sample glass 3 in the width direction X are supported by a pair of supporting members 4. Figure 3 As shown in the figure, the magnitude of the second deflection X2 (the state shown by the single-dot chain line in the figure) in the width direction X of the sample glass 3 is measured. In this measurement, the second deflection X2 is also measured for the two parallel sides 3x of the sample glass 3 along the width direction X, and the larger value of the two is adopted as the second deflection X2. The magnitude of the adopted second deflection X2 is converted to the second deflection X2 when the support span M is 350mm.

[0094] After the first deflection X1 and the second deflection X2 are measured in this manner, the second deflection X2 is subtracted from the first deflection X1 to obtain the front and back deflection difference X1 − X2 in the width direction X.

[0095] By performing the above operation on all the sample glasses 3 corresponding to the evaluation areas A to E, the shape of the width direction X in each evaluation area A to E can be understood. Figure 3 As shown, when the first deflection X1 is larger than the second deflection X2 and the front-back deflection difference X1-X2 becomes positive (a value larger than 0), the shape of the deflection in the width direction X of the sample glass 3 in the glass plate 1 is such that the surface 3a becomes a convex surface, and its magnitude can be evaluated by the absolute value of the front-back deflection difference X1-X2. On the other hand, when the first deflection X1 is smaller than the second deflection X2 and the front-back deflection difference X1-X2 becomes negative (a value smaller than 0) (not shown), the shape of the deflection in the width direction X of the sample glass 3 in the glass plate 1 is such that the surface 3a becomes a concave surface, and its magnitude can be evaluated by the absolute value of the front-back deflection difference X1-X2. Here, when observing an arbitrary linear region (cross section) along the width direction X of the glass plate 1, the annealing conditions at each point on the linear region can be regarded as substantially the same even if the position in the plate pulling direction Y is different. Therefore, the shape of the entire glass plate 1 in the width direction X can be understood simply by determining the front-back deflection difference X1 - X2 in the sample glass 3 corresponding to each of the evaluation areas A to E.

[0096] By the same procedure as above, the shape of the glass sheet 1 along the pulling direction Y can be evaluated using the front and back deflection difference Y1 - Y2 . Hereinafter, the evaluation method will be described.

[0097] In preparation and Figure 1After preparing five sample glasses 3 corresponding to the evaluation areas A to E shown in the figure, the front and back deflection differences Y1-Y2 of each sample glass 3 in the pulling direction Y are measured. The prepared sample glass 3 may be the sample glass 3 used when evaluating the shape along the width direction X. Specifically, Figure 4 As shown, with the guaranteed surface 3a of the sample glass 3 facing downward, a pair of supporting members 5 are used to support both ends of the sample glass 3 in the plate pulling direction Y. At this time, the support span N of the sample glass 3 supported by the pair of supporting members 5 is set to 480 mm when the length of the side 3y along the plate pulling direction Y is 500 mm and the length of the side 3x along the width direction X is 400 mm, and is set to a value obtained by subtracting 20 mm from the length of the side 3y along the plate pulling direction Y of the sample glass 3 in other cases. In this state, as Figure 5 As shown in the figure, the magnitude of the first deflection Y1 (the state shown by the solid line in the figure) of the sample glass 3 in the pulling direction Y is measured. In this measurement, the first deflection Y1 is measured for each of the two parallel sides 3y of the sample glass 3 along the pulling direction Y, and the larger of the two values ​​is adopted as the first deflection Y1. The magnitude of the adopted first deflection Y1 is converted to the first deflection Y1 when the support span N is 350 mm.

[0098] Similarly, the sample glass 3 is turned upside down with the non-guaranteed surface 3b of the sample glass 3 facing downward, and the two ends of the sample glass 3 in the pulling direction Y are supported by a pair of supporting members 5. Figure 5 As shown in the figure, the magnitude of the second deflection Y2 (the state shown by the single-dot chain line in the figure) of the sample glass 3 in the pulling direction Y is measured. In this measurement, the second deflection Y2 is measured for each of the two parallel sides 3y of the sample glass 3 along the pulling direction Y, and the larger value of the two is adopted as the second deflection Y2. The magnitude of the adopted second deflection Y2 is converted to the second deflection Y2 when the support span N is 350 mm.

[0099] After the first deflection Y1 and the second deflection Y2 are measured in this manner, the second deflection Y2 is subtracted from the first deflection Y1 to obtain the front and back deflection difference Y1 - Y2 in the pulling direction Y.

[0100] By performing the above operation on all the sample glasses 3 corresponding to the evaluation areas A to E, the shape of the plate pulling direction Y in each evaluation area A to E can be understood. Figure 5As shown, when the first deflection Y1 is larger than the second deflection Y2 and the front and back deflection difference Y1-Y2 is positive, the shape of the deflection in the drawing direction Y of the sample glass 3 in the glass plate 1 is such that the surface 3a is convex, and its size can be evaluated by the absolute value of the front and back deflection difference Y1-Y2. On the other hand, when the first deflection Y1 is smaller than the second deflection Y2 and the front and back deflection difference Y1-Y2 is negative (not shown), the shape of the deflection in the drawing direction Y of the sample glass 3 in the glass plate 1 is such that the surface 3a is concave, and its size can be evaluated by the absolute value of the front and back deflection difference Y1-Y2. Here, when observing an arbitrary linear region (cross section) along the width direction X in the glass plate 1, the annealing conditions at each point on the linear region can be regarded as substantially the same even if the position in the drawing direction Y is different. Therefore, by simply finding the front and back deflection difference Y1-Y2 in the sample glass 3 corresponding to each evaluation area A to E, the shape of the entire glass plate 1 in the drawing direction Y can be understood.

[0101] When the shape of the glass plate 1 of the present embodiment is evaluated using the above-mentioned front and back deflection difference, the glass plate 1 has the following shape quality.

[0102] That is, the absolute value of the average value of the front and back deflection differences X1-X2 in the width direction X corresponding to the five evaluation areas A to E of the glass plate 1 is 0.06 mm or more and 0.8 mm or less. The lower limit of the absolute value is preferably 0.1 mm or more, 0.15 mm or more, 0.17 mm or more, more preferably 0.18 mm or more, and even more preferably 0.2 mm or more. On the other hand, the upper limit of the absolute value is preferably 0.6 mm or less, more preferably 0.5 mm or less, and even more preferably 0.4 mm or less.

[0103] In addition, the average value of the front and back deflection difference X1-X2 in the width direction X corresponding to the five evaluation areas A to E of the glass plate 1 is positive. Moreover, the front and back deflection difference X1-X2 in the width direction X corresponding to the five evaluation areas A to E of the glass plate 1 are all greater than -0.2 mm and less than 1.0 mm. The lower limit value of the front and back deflection difference X1-X2 is preferably greater than -0.1 mm, more preferably greater than 0 mm, and further preferably greater than 0.1 mm. On the other hand, the upper limit value of the front and back deflection difference X1-X2 is preferably less than 0.9 mm, more preferably less than 0.85 mm, and further preferably less than 0.8 mm.

[0104] The difference between the maximum and minimum values ​​of the front and back deflection differences X1 - X2 in the width direction X of the glass plate 1 corresponding to the five evaluation areas A to E is 2.0 mm or less, preferably 1.5 mm or less, more preferably 1.3 mm, and further preferably 1.0 mm.

[0105] According to the above, the average value of the front and back deflection differences X1-X2 of the glass plate 1 is positive, so that the surface 1a is curved in the width direction X. Moreover, since any value of the front and back deflection differences X1-X2 is large, the degree of curvature of the convex surface is large. In addition, since the difference between the maximum value and the minimum value of the front and back deflection differences X1-X2 is small, the convex surface is further reliably smoothly curved over the entire length or substantially the entire length in the width direction X. Such a shape of the glass plate 1 along the width direction X covers the entire length of the pull direction Y.

[0106] Figure 6 The use example of the glass plate 1 is schematically shown. The first use example is to perform a heating film-forming treatment on the guaranteed surface 1a of the glass plate 1 as shown by the reference numeral B1 in the figure. In detail, a film material 6 of a resin such as polyimide is applied to the guaranteed surface 1a of the glass plate 1, and after degassing and drying, the film material 6 is fired to harden, thereby forming a resin film 6a. And, if it is cooled to near room temperature after firing, as shown by the reference numeral B2 in the figure, the shape of the glass plate 1 and the resin film 6a is flattened (becomes a flat shape in the example). Thereafter, the resin film 6a is peeled off from the glass plate 1 using an ultraviolet laser, and the peeled resin film 6a is used for the manufacture of electronic devices such as displays. In this case, when the resin film 6a is peeled off, the shape of the glass plate 1 is flattened, so that the peeling operation is appropriately and reliably performed.

[0107] In the second use, for example, as shown by reference numeral B1 in the figure, a heat film forming treatment is performed on the guaranteed surface 1a of the glass plate 1 in the same manner as described above to form a film 6a such as an organic film (including a resin film) or an inorganic film (including a metal film). Thereafter, as shown by reference numeral B2 in the figure, the shape of the glass plate 1 is flattened by cooling to near room temperature in the same manner as described above. The glass plate 1 with the film 6a thus obtained is used for the manufacture of electronic devices such as displays. The glass plate 1 with the film 6a has a flattened shape and is therefore of high quality.

[0108] In relation to these usage examples, the glass plate 1 has the following characteristics.

[0109] The linear thermal expansion coefficient of the glass plate 1 at 30 to 380°C is 30×10 -7 / ℃ and above 50×10 -7 / °C or less. This is suitable when the polyimide resin film 6a is formed on the guaranteed surface 1a of the glass plate 1 by a heat film forming process. That is, the linear thermal expansion coefficient of the polyimide resin film 6a is within the above-mentioned numerical range, so it is possible to appropriately cope with the thermal expansion difference between the resin film 6a and the glass plate 1 and more reliably flatten the shape of the glass plate 1 when it is cooled to near room temperature.

[0110] The heat shrinkage rate of the glass plate 1 when it is kept at 500°C for 1 hour is less than 30 ppm. In this way, the shrinkage (compression) of the glass plate 1 when the guaranteed surface 1a of the glass plate 1 is subjected to a heat film forming treatment is suppressed. This characteristic is particularly required by high-definition displays. Therefore, the glass plate 1 for high-definition displays can be appropriately used. It should be noted that the "heat shrinkage rate" is measured by the following method. First, a 160mm×30mm long strip sample is prepared as a sample for measurement. A #1000 water-resistant abrasive paper is used to mark the long side of the long strip sample at 20 to 40 mm from the end, and two test pieces are obtained by breaking in a direction orthogonal to the mark. After the test piece obtained by breaking is heat-treated under specified conditions, the other test piece that has not been heat-treated is arranged with the heat-treated test piece and fixed with a belt or the like. It should be noted that the prescribed heat treatment refers to a treatment in which the temperature is raised from room temperature to 500°C at a rate of 5°C / min, maintained at 500°C for 1 hour, and then lowered from 500°C to room temperature at a rate of 5°C / min. In this state, the positional deviation of the mark (ΔL1, ΔL2) is read using a laser microscope, and the thermal shrinkage is calculated using the following formula (4).

[0111] Thermal shrinkage [ppm] = (ΔL1 [μm] + ΔL2 [μm]) / 160 × 10 -3 (4)

[0112] The thermal shrinkage is preferably 30 ppm or less, 20 ppm or less, and particularly preferably 15 ppm or less. In this way, when the glass plate 1 is used for the manufacture of a high-definition display, it is difficult to cause problems such as pattern deviation. It should be noted that when the thermal shrinkage is too low, the production efficiency of the glass plate 1 is likely to decrease. Therefore, the thermal shrinkage is preferably 1 ppm or more, 2 ppm or more, 3 ppm or more, 4 ppm or more, and particularly preferably 5 ppm or more.

[0113] The transmittance of the glass plate 1 in the plate thickness direction at a wavelength of 308 nm is 60% or more and 85% or less. The transmittance can be measured using a spectrophotometer.

[0114] This is suitable when the polyimide resin film 6a is formed on the guaranteed surface 1a of the glass plate 1 by a heat film forming process and the resin film 6a is peeled off using an ultraviolet laser. That is, the wavelength of the ultraviolet laser is 308nm, so the glass plate 1 has an appropriate transmittance in the plate thickness direction in the same wavelength region. As a result, the peeling operation of the polyimide resin film 6a from the glass plate 1 can be further appropriately and reliably performed.

[0115] The glass plate 1 of the above-mentioned embodiment has a curved shape that ensures that the surface 1a is convex in the width direction X, but it can also have a curved shape that ensures that the surface 1a is convex in both the width direction X and the plate pulling direction Y. Such a glass plate 1 can use the method described above and evaluate the shape along the plate pulling direction Y based on the front and back deflection differences Y1-Y2. In this case, the glass plate 1 is preferably a positive average value of the front and back deflection differences Y1-Y2 in the plate pulling direction Y of the five evaluation areas A to E. In addition, the absolute value of the average value of the front and back deflection differences Y1-Y2 in the plate pulling direction Y of the five evaluation areas A to E is preferably equal to the absolute value of the average value of the front and back deflection differences X1-X2 in the width direction X described above.

[0116] <Glass sheet manufacturing device>

[0117] like Figure 7 as well as Figure 8 As shown, the manufacturing device 7 of the glass sheet 1 of the present embodiment includes: a forming furnace 8; an annealing furnace 9, which is located below the forming furnace 8; a cooling zone 10, which is located below the annealing furnace 9; and a cutting device 11, which is located below the cooling zone 10. The forming furnace 8 and the annealing furnace 9, the annealing furnace 9 and the cooling zone 10, and the cooling zone 10 and the cutting device 11 are respectively partitioned by partition members (for example, the floor surface of a building) F1, F2, and F3 having openings (for example, slits) for passing the glass ribbon Gr.

[0118] The forming furnace 8 is a region for forming a glass ribbon Gr from molten glass Gm by an overflow down-draw method. Inside the forming furnace 8, a forming body 12 for forming the glass ribbon Gr from the molten glass Gm and edge rollers 13 for cooling both ends of the glass ribbon Gr formed by the forming body 12 in the width direction X are arranged.

[0119] A groove (overflow groove) 14 formed along the width direction is provided at the top of the forming body 12. A supply pipe 15 is connected to one end of the groove 14. The molten glass Gm is supplied into the groove 14 through the supply pipe 15. The supply method of the molten glass Gm is not limited thereto. For example, the molten glass Gm may be supplied from both ends of the groove 14, or may be supplied from the top of the groove 14.

[0120] The two outer side surfaces of the molded body 12 are respectively provided with a vertical surface 16 in a planar shape along the vertical direction and an inclined surface 17 in a planar shape connected to the bottom of the vertical surface 16 and inclined relative to the vertical direction. Each vertical surface 16 is a plane parallel to each other. Each inclined surface 17 is a plane inclined so as to approach each other as it goes downward. That is, the molded body 12 is formed with each inclined surface 17 so that it is a wedge shape that becomes thinner at the front end when viewed from the side, and the corner where each inclined surface 17 intersects forms the lower end 12a of the molded body 12. It should be noted that the vertical surface 16 can be changed in shape to an inclined surface, a curved surface, etc., or can be omitted.

[0121] The edge roll 13 is configured as a pair of rolls that clamp each end of the glass ribbon Gr in the width direction just below the forming body 12. The edge roll 13 is a cantilever type roll, and the inside is always cooled during the forming process. Therefore, the edge roll 13 is sometimes also called a cooling roll.

[0122] The annealing furnace 9 is an area for reducing the warping and internal strain of the glass ribbon Gr. A first conveying device 18 is provided inside the annealing furnace 9. The first conveying device 18 includes annealing rollers 19. The annealing rollers 19 are basically configured as a pair of rollers that clamp the two end portions of the glass ribbon Gr in the width direction. The annealing rollers 19 may also be rollers of the two end support type that are configured in a manner that spans the entire area in the width direction of the glass ribbon Gr, but in this embodiment, they are cantilever type rollers. The annealing rollers 19 are provided in multiple stages (9 stages in the example) along the conveying path of the glass ribbon Gr in the up and down direction.

[0123] The cooling zone 10 is a zone for cooling the glass ribbon Gr to near room temperature. A second conveying device 20 is provided inside the cooling zone 10. The second conveying device 20 includes conveying rollers 21. The conveying rollers 21 are configured as a pair of rollers that clamp both ends of the glass ribbon Gr in the width direction. The conveying rollers 21 may also be rollers of both end support type that are arranged in a manner that spans the entire area in the width direction of the glass ribbon Gr, but in this embodiment, they are cantilever type rollers. The conveying rollers 21 are provided in multiple stages (five stages in the example) in the up and down direction.

[0124] The cutting device 11 includes a scoring line forming device 22. The scoring line forming device 22 is a device that forms a scoring line S on the first main surface Ga of the glass ribbon Gr descending from the cooling zone 10 at the scoring line forming position P1. In the present embodiment, the scoring line forming device 22 includes: a cutter wheel 23 that forms a scoring line S along the width direction on the first main surface Ga of the glass ribbon Gr; and a supporting member 24 (for example, a supporting rod, a supporting roller) that supports the second main surface Gb of the glass ribbon Gr at a position corresponding to the cutter wheel 23. The cutter wheel 23 and the supporting member 24 are configured to form the scoring line S on the entire area or a part of the width direction of the glass ribbon Gr while following the movement of the glass ribbon Gr that continuously moves downward. It should be noted that the scoring line S may also be formed by irradiation of a laser or the like.

[0125] Furthermore, the cutting device 11 includes a breaking device 25. The breaking device 25 is a device for breaking the glass ribbon Gr along the score line S at a breaking position P2 set below the score line forming position P1 to cut out a glass plate 1r. In the present embodiment, the breaking device 25 includes: a breaking member 26 that contacts the area where the score line S is formed from the second main surface Gb side; and a holding mechanism 27 that holds the lower area of ​​the glass ribbon Gr at a position lower than the breaking position P2. The breaking member 26 is composed of a plate-like body having a contact surface that contacts the entire area or a part of the width direction of the glass ribbon Gr. The holding mechanism 27 includes: chucks 28 that are provided at multiple locations in the up-down direction at both ends of the glass ribbon Gr in the width direction; and arms 29 that hold these multiple chucks 28 at both ends in the width direction.

[0126] The breaking member 26 and the holding mechanism 27 perform the following operations. First, after the plurality of clamps 28 hold the glass ribbon Gr, the arm 29 moves the plurality of clamps 28 to follow the descent of the glass ribbon Gr. At this time, the breaking member 26 also moves to follow the descent of the glass ribbon Gr. During these movements, the arm 29 performs an operation for bending the glass ribbon Gr with the breaking member 26 as a fulcrum ( Figure 1 Thus, bending stress is applied to the score line S and its vicinity, and the glass ribbon Gr is broken in the width direction along the score line S. As a result of the cutting by the breaking, a glass sheet 1r is cut out from the glass ribbon Gr.

[0127] In the present embodiment, the glass ribbon Gr and the glass plate 1r obtained by the manufacturing device 7 have ear portions at both ends in the width direction X, which are thicker than the central portion in the width direction X. The ear portions are formed under the influence of shrinkage and the like during the forming process. The glass plate 1r is removed from the ear portions in a subsequent step to become the glass plate 1 described above. The guaranteed surface (first main surface) 1a of the glass plate 1 is the surface on the same side in the plate thickness direction as the first main surface Ga of the glass ribbon Gr.

[0128] Here, the first conveying device 18 provided inside the above-mentioned annealing furnace 9 will be described in detail. Figure 7 As shown, the annealing rollers 19 of the first to fourth stages from the upper side and the annealing rollers 19 of the sixth stage from the upper side are provided in the nine stages in the vertical direction to support both ends of the glass ribbon Gr in the width direction from the first principal surface Ga side and the second principal surface Gb side. Therefore, these annealing rollers 19 clamp both ends of the glass ribbon Gr in the width direction.

[0129] On the other hand, the annealing rollers 19 of the 5th and 7th annealing rollers 19 from the upper side, which are located on the second principal surface Gb side of the glass ribbon Gr, are deflected toward the first principal surface Ga side (hereinafter, the annealing rollers 19 are referred to as deflection rollers 19a). Furthermore, both ends of the glass ribbon Gr in the width direction are supported by these deflection rollers 19a only from the second principal surface Gb side. In other words, these deflection rollers 19a press both ends of the glass ribbon Gr in the width direction only from the second principal surface Gb side. The deflection rollers 19a of the 5th level from the upper side are deflected toward the first principal surface Ga side with reference to the annealing rollers 19 of the 4th level from the upper side, which are located on the second principal surface Gb side. The deflection rollers 19a of the 7th level from the upper side are deflected toward the first principal surface Ga side with reference to the annealing rollers 19 of the 6th level from the upper side, which are located on the second principal surface Gb side. As shown in FIG. Fig. 9 As shown in FIG. 1 , the deflection amount Lz of the deflection rollers 19a toward the first main surface Ga is set to be greater than 1 mm and less than 20 mm based on the annealing roller 19 closest to the upper side. The lower limit of the deflection amount Lz is more preferably greater than 3 mm, and further preferably greater than 5 mm. In addition, the upper limit of the deflection amount Lz is more preferably less than 15 mm, and further preferably less than 10 mm. In this case, Figure 7 As shown, the annealing roller 19 located on the second main surface Gb side among the annealing rollers 19 located in the sixth stage from the top is not deflected toward either the first main surface Ga side or the second main surface Gb side with reference to the deflecting roller 19 a located in the fifth stage from the top.

[0130] Moreover, if Figure 7 as well as Fig. 9As shown, at positions opposite to the two deflection rollers 19a in the thickness direction of the glass ribbon Gr, deflection opposing rollers 19b are respectively provided. These deflection opposing rollers 19b are separated from both ends of the width direction of the glass ribbon Gr to the first main surface Ga side. It should be noted that, in the present embodiment, the annealing rollers 19 of the 8th and 9th levels from the upper side do not clamp both ends of the width direction of the glass ribbon Gr, and in the example, they are separated from both ends of the width direction of the glass ribbon Gr to both the first main surface Ga side and the second main surface Gb side. Therefore, inside the annealing furnace 9, the annealing rollers 19a and the deflection opposing rollers 19b disposed at the bottom are used as a reference, and the annealing rollers 19 disposed below them do not clamp the glass ribbon Gr.

[0131] The two deflection rollers 19a are preferably installed in a region where the temperature of the glass ribbon Gr is a strain point to a softening point. Alternatively, the two deflection rollers 19a are preferably installed in a region where the viscosity of the glass ribbon Gr is 10 14.5 ~10 7.6 dPa・s area. In other words, both deflection rollers 19a are preferably arranged at a position lower than the central position of the conveying path in the up-down direction in the annealing furnace 9. It should be noted that, instead of arranging the deflection rollers 19a at two locations of the conveying path in the annealing furnace 9 as shown in the example, they can also be arranged at one location of the conveying path, or at three or more locations. In this case, these deflection rollers 19a are also preferably arranged at a position lower than the central position of the conveying path in the up-down direction in the annealing furnace 9. In addition, when the deflection rollers 19a are arranged at two locations of the conveying path in the annealing furnace 9, the annealing rollers 19 other than the 5th and 7th levels can also be deflected.

[0132] <Method for producing glass plate>

[0133] The manufacturing method of the glass sheet 1 of the present embodiment is mainly performed using the manufacturing apparatus 7 having the above-mentioned structure. The present manufacturing method includes a forming step, an annealing step, a cooling step, and a cutting step.

[0134] In the forming step, in the forming furnace 8, molten glass Gm is supplied to the groove 14 of the forming body 12, and the molten glass Gm overflowing from the groove 14 to both sides flows down along the vertical surface 16 and the inclined surface 17 and merges again at the lower end 12a. Thus, the glass ribbon Gr is continuously formed from the molten glass Gm.

[0135] In the annealing step, the glass ribbon Gr is annealed in the annealing furnace 9 while being conveyed downward by the first conveying device 18 .

[0136] In the cooling step, in the cooling zone 10 , the glass ribbon Gr is cooled to near room temperature while being conveyed downward by the second conveying device 20 .

[0137] In the cutting step, the glass ribbon Gr is cut to obtain the glass plate 1. Specifically, the cutting step includes a first cutting step of cutting the glass ribbon Gr at predetermined lengths in the width direction X to obtain the glass plate 1r, and a second cutting step of cutting and removing the ears at both ends of the glass plate 1r in the width direction to obtain the glass plate 1.

[0138] Here, in the above-mentioned annealing step, the first conveying device 18 includes a deflection roller 19a and a deflection counter roller 19b, so that the glass sheet 1 cut out from the glass ribbon Gr through the first and second cutting steps can be set to the curved shape described above. Fig. 9 as well as Fig.10 As shown in FIG. 1 , the deflection roller 19a supports the second main surface Gb side of both ends Gd in the width direction of the glass ribbon Gr, and the deflection opposing roller 19b is separated from both ends Gd in the width direction of the glass ribbon Gr, so that the width direction center Gc of the glass ribbon Gr can be greatly convexly curved toward the first main surface Ga side. In other words, Fig.10 As shown, the widthwise end portions Gd of the glass ribbon Gr are not clamped by the deflection roller 19a and the deflection opposing roller 19b, so that not only the widthwise central portion Gc of the glass ribbon Gr but also the widthwise end portions Gd can be bent toward the first principal surface Ga. Thus, the first principal surface 1a of the obtained glass sheet 1 can be made a convex surface with a large degree of curvature in the widthwise direction.

[0139] In contrast, assuming that Fig.11 as well as Fig.12 As shown in FIG. 1 , when both ends Gd in the width direction of the glass ribbon Gr are clamped by the deflection roller 19a and the deflection opposing roller 19b, both ends Gd in the width direction become flat. In addition, due to this influence, only the narrow area of ​​the central portion Gc in the width direction of the glass ribbon Gr is convexly curved toward the first main surface Ga. Therefore, the first main surface 1a of the obtained glass plate 1 becomes a convex surface with a small degree of curvature in the width direction.

[0140] Furthermore, in the annealing furnace 9 of the present embodiment, the deflection roller 19a and the deflection opposing roller 19b are respectively provided at two locations of the conveyance path of the glass ribbon Gr, so that the first main surface 1a of the obtained glass sheet 1 can be made into a convex surface with a further greater curvature in the width direction.

[0141] If the above matters are taken into consideration, the deflection opposing roller 19b may not be provided, but when the deflection opposing roller 19b is provided, the following advantages are obtained. The deflection roller 19a and the deflection opposing roller 19b are provided so as to be movable in the plate thickness direction of the glass ribbon Gr. By providing the deflection opposing roller 19b, the deflection annealing roller 19 can be selected according to the manufacturing conditions of the glass plate 1.

[0142] In the annealing process of the present embodiment, the deflection roller 19a is provided, so that the glass ribbon Gr is also curved convexly toward the first main surface Ga in the pulling direction. Therefore, the first main surface 1a of the obtained glass sheet 1 can also be convex in the pulling direction. Therefore, in the annealing process, the shape of the glass sheet 1 along the pulling direction can be set to the shape described above.

[0143] Example 1

[0144] Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples.

[0145] The inventors of the present invention conducted a comparative test to confirm the effect of the present invention. In this test, glass plates of Examples 1 to 6 and glass plates of Comparative Examples 1 and 2 were produced, and the front and back deflection difference X1-X2 in the width direction X of each example was evaluated. The glass plates in each example were produced using the manufacturing device 7 described above. In addition, the front and back deflection difference X1-X2 in each example was evaluated based on the method described above. Moreover, in each example, a polyimide solution was coated on the first main surface of the glass plate, and after a heating film forming treatment was performed at 500°C for 5 hours, it was cooled to near room temperature to determine whether the glass plate was warped. Their evaluation results and determination results are shown in Table 1 below. It should be noted that in each example, as a low-alkali glass plate for display, a strain point of 780 to 830°C, a Young's modulus of 80 to 85 GPa, a thermal shrinkage of about 9 to 12 ppm when heat-treated at 500°C for 1 hour, and a thermal expansion coefficient of 35 to 40×10 -7 / °C OA-31 material manufactured by Nippon Electric Glass Co., Ltd. In each example, the thickness of the polyimide film after heat film formation was about 10 μm.

[0146] [Table 1]

[0147]

[0148] According to the above Table 1, the glass sheets of Examples 1 to 6 have all positive average values ​​of the front and back deflection differences X1-X2 in the width direction X of the five evaluation areas A to E, and the average values ​​are all within the numerical range of 0.06 to 0.4 mm, so no warping occurs after firing. On the other hand, the average value of the front and back deflection differences X1-X2 in the width direction X of the five evaluation areas A to E is 0.05 mm, which is smaller than that of Examples 1 to 6, so warping occurs after firing in a manner convex to the non-guaranteed surface (second main surface) side. In addition, the average value of the front and back deflection differences X1-X2 in the width direction X of the five evaluation areas A to E in Comparative Example 2 is 0.9 mm, which is larger than that of Examples 1 to 6, so warping occurs after firing in a manner convex to the guaranteed surface (first main surface) side. Taking this into consideration, it can be estimated that the upper limit value of the average value of the front and back deflection differences X1 - X2 in the width direction X of the five evaluation areas A to E may be 0.8 mm and the lower limit value may be 0.06 mm.

[0149] In addition, according to the above Table 1, the glass sheets of Examples 1 to 6 have a difference between the maximum and minimum values ​​of the front and back deflection differences X1-X2 in the width direction X of the five evaluation areas A to E in the numerical range of 0.2 to 0.8 mm, so they have a shape that is smoothly curved over the entire length of the width direction of the glass sheet, and do not warp after firing. Comparative Example 1 has a difference between the maximum and minimum values ​​of the front and back deflection differences X1-X2 in the width direction X of the five evaluation areas A to E of 0.2 mm, so although it has a shape that is smoothly curved over the entire length of the width direction of the glass sheet, as described above, the average value is 0.05 mm, so warping occurs after firing. On the other hand, Comparative Example 2 has a difference between the maximum and minimum values ​​of the front and back deflection differences X1-X2 in the width direction X of the five evaluation areas A to E of 2.3 mm, which is larger than Examples 1 to 6, so it does not have a shape that is smoothly curved over the entire length of the width direction of the glass sheet, and warping occurs after firing.

[0150] Description of Reference Numerals

[0151] 1 Glass Pane

[0152] 1a The first main surface of the glass plate (guaranteed surface)

[0153] 1b Second main surface of glass plate (non-guaranteed surface)

[0154] 1x Glass pane edge along width

[0155] 1y The edge of the glass plate along the pulling direction

[0156] 7 Manufacturing equipment

[0157] 8 Forming furnace

[0158] 9 Annealing furnace

[0159] 18 First transport device (transport device in annealing furnace)

[0160] 19 Annealing roller

[0161] 19a Deflection roller

[0162] First main surface of Ga glass ribbon

[0163] Gb Second main surface of glass ribbon

[0164] Gd Both ends of the glass ribbon in the width direction

[0165] Gr Glass Ribbon

[0166] Lz is the deflection value of the deflection roller

[0167] X width direction

[0168] X1 Deflection in width direction

[0169] Y pull direction

[0170] Y1 Deflection in the pulling direction.

Claims

1. A glass plate having a rectangular shape, comprising a first main surface and a second main surface on the back side of the first main surface, and comprising a first side along a plate pulling direction and a second side along a width direction orthogonal to the plate pulling direction, wherein the lengths of the first side and the second side are greater than 1000 mm, and the plate thickness of the glass plate is greater than 0.1 mm and less than 2.0 mm, The glass sheet is characterized in that When five rectangular evaluation areas of the same size are set in order from one end side in the width direction, the absolute value of the average value of the front and back deflection differences in the width direction of the five evaluation areas calculated by the following formula (1) is 0.06 mm or more and 0.8 mm or less, Deflection difference between front and back = (X1 - X2) (1) X1: Deflection in the width direction when the first main surface is facing downward, of the sample glass corresponding to the evaluation area for measuring the front and back deflection difference [mm] X2: Deflection (mm) in the width direction when the second main surface is facing downward, of the sample glass corresponding to the evaluation region for measuring the difference in front and back deflection.

2. The glass sheet according to claim 1, characterized in that The average value of the difference in front and back deflection in the width direction of the five evaluation areas is 0.15 mm or more.

3. The glass sheet according to claim 1, characterized in that The average value of the front and back deflection difference in the width direction of the five evaluation areas is positive, The front and back deflection differences in the width direction of the five evaluation areas were all greater than or equal to −0.2 mm and less than or equal to 1.0 mm.

4. The glass sheet according to claim 3, characterized in that The first main surface is a guaranteed surface, and the second main surface is a non-guaranteed surface.

5. The glass sheet according to any one of claims 1 to 4, characterized in that The difference between the maximum value and the minimum value of the front and back deflection difference in the width direction of the five evaluation areas is 2.0 mm or less.

6. The glass sheet according to any one of claims 1 to 4, characterized in that The linear thermal expansion coefficient at 30-380°C is 30×10 -7 / ℃ and above 50×10 -7 / ℃ below.

7. The glass sheet according to any one of claims 1 to 4, characterized in that The thermal shrinkage rate when maintained at 500° C. for 1 hour was 30 ppm or less.

8. The glass sheet according to any one of claims 1 to 4, characterized in that The transmittance in the plate thickness direction at a wavelength of 308 nm is 60% or more and 85% or less.

9. The glass sheet according to any one of claims 1 to 4, characterized in that As for the glass composition, it contains, in mol %, 60-70% SiO2, 9.5-17% Al2O3, 0-9% B2O3, 0% or more and less than 1% Li2O+Na2O+K2O, 0-8% MgO, 2-15% CaO, 0-10% SrO, and 0.1-5% BaO.

10. The glass sheet according to any one of claims 1 to 4, characterized in that As for the glass composition, it contains, in mol %, 62-72% SiO2, 9.5-16% Al2O3, 1-8% B2O3, 0% or more and less than 1% Li2O+Na2O+K2O, 1-9% MgO, 2-10% CaO, 0.1-5% SrO, and 0.1-5% BaO.

11. The glass sheet according to any one of claims 1 to 4, characterized in that As for the glass composition, it contains, in mol %, 67-77% SiO2, 9-14% Al2O3, 0-3% B2O3, 0% or more and less than 1% Li2O+Na2O+K2O, 0-5% MgO, 0-10% CaO, 0-5% SrO, and 0-7% BaO.

12. A method for manufacturing a glass plate, comprising: A forming process for forming a glass ribbon from molten glass; an annealing step of annealing the glass ribbon while being conveyed by a conveying device; and a cutting step of cutting the annealed glass ribbon into a rectangular glass plate. The method for manufacturing the glass plate is characterized in that: The glass ribbon has a first main surface and a second main surface on the back side of the first main surface, and has a thickness of 0.1 mm to 2.0 mm. In the annealing step, a plurality of roller pairs in the conveying device are used to support both end portions in the width direction of the glass ribbon from the first main surface side and the second main surface side, and at least one portion in the conveying direction of the glass ribbon in the conveying device is used to support both end portions in the width direction of the glass ribbon only from the second main surface side by a deflection roller deflected toward the first main surface side of the glass ribbon.

13. The method for manufacturing a glass plate according to claim 12, wherein: The first main surface is a guaranteed surface, and the second main surface is a non-guaranteed surface.

14. The method for manufacturing a glass plate according to claim 12 or 13, characterized in that: The deflection amount of the deflection roller is greater than or equal to 1 mm and less than or equal to 20 mm.

15. A glass sheet manufacturing device, comprising: a forming furnace for forming a glass ribbon having a first main surface and a second main surface on the back side of the first main surface from molten glass; an annealing furnace for annealing the glass ribbon while being conveyed by a conveying device; and a cutting device for cutting the annealed glass ribbon into a rectangular glass sheet, The glass sheet manufacturing device is characterized in that: The conveying device includes: a plurality of roller pairs that support both ends of the glass ribbon in the width direction from the first main surface side and the second main surface side; and a deflection roller that is arranged at at least one position of the conveying path of the glass ribbon and is deflected toward the first main surface side of the glass ribbon and supports both ends of the glass ribbon in the width direction only from the second main surface side.

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