TW201819333A - Method for manufacturing reinforced glass plate, film-coated glass plate, and reinforced glass plate - Google Patents

Abstract

The present method comprises: a mask step of providing a first mask Ma for ion exchange inhibition or prevention purposes on at least a portion of a first main surface Sa of a glass plate G1, and also providing a second mask Mb for ion exchange inhibition or prevention purposes on at least a portion of a second main surface Sb of the glass plate G1; and, subsequent to the mask step, an ion exchange step of immersing a glass plate G2 in a molten salt for ion exchange use. In the mask step, the area of the first mask Ma-formed portion in the first main surface Sa and the area of the second mask Mb-formed portion in the second main surface Sb are set to different values from each other depending on the cross-sectional shape of the glass plate G1.

Description

Manufacturing method of strengthened glass plate, coated glass plate and strengthened glass plate

[0001] The present invention relates to a method for manufacturing a strengthened glass plate, and more specifically, to a method for manufacturing a strengthened glass plate that is chemically strengthened by an ion exchange method, a coated glass plate, and a strengthened glass plate.

[0002] In recent years, the cover glass of electronic devices such as mobile phones, cameras, display surfaces such as large displays, personal computers, and wearable terminals such as watches uses chemically strengthened glass plates. [0003] Generally, such a strengthened glass plate is produced by forming a compressive stress layer on the surface of a glass plate containing an alkali metal as a composition through chemical treatment with a strengthening liquid. Since such a strengthened glass plate has a compressive stress layer on the surface, impact resistance and the like are improved. However, even with such a strengthened glass plate, the impact resistance of the edge portion or the peripheral portion is lower than the impact resistance of the main surface, which may cause the damage of the strengthened glass plate. When the entire compressive stress layer on the surface of the strengthened glass sheet is deepened in order to prevent such breakage, the tensile stress formed inside the glass sheet becomes excessively large, and there is damage due to the tensile stress (so-called Self-destructive). [0004] In order to solve the above-mentioned problems, a technology for selectively forming a deep compressive stress layer only on a part of the surface of a strengthened glass plate has been developed. For example, in the method disclosed in Patent Document 1, only the central portion of the main surface is shielded with a masking material, whereby the peripheral portion that is not shielded can be strengthened by ion exchange (first strengthening treatment). ). After that, the shield is removed, and the strengthening process (second strengthening process) is performed again, so that a compressive stress layer deeper than the main surface can be formed on the edge portion that has been strengthened in advance. [Prior Art Literature] [Patent Literature] [0005] [Patent Literature 1] Japanese Patent Publication No. 2014-510012

[Technical Problems to be Solved by the Invention] [0006] However, when a method such as Patent Document 1 is used, the glass plate may be deformed unexpectedly and productivity may be reduced. [0007] For example, as shown in FIG. 9, when the cross-sectional shape of the glass plate is asymmetric in the thickness direction, the glass plate may be warped and deformed during the ion exchange. Hereinafter, a conventional method for manufacturing a strengthened glass plate and its problems will be specifically described with reference to FIG. 9. [0008] FIG. 9A shows a step of a glass plate G10 whose cross-sectional shape is asymmetric in the thickness direction. The glass plate G10 has an asymmetrical shape on the front and back with the central line (one-dot chain line in the figure) X10 as the axis in the thickness direction. FIG. 9B shows a step of obtaining a film-coated glass plate G20 having a shield Mc having the same thickness and the same area on the main surface of the glass plate G10. FIG. 9C shows a strengthening step (first strengthening treatment) in which a coated glass plate G20 is immersed in molten salt T10 and subjected to ion exchange treatment to obtain a strengthened glass plate G30 having a compressive stress layer CP in the surface layer portion. [0009] If according to these treatments, although the cross-sectional shape of the strengthened glass plate G30 is asymmetric in the thickness direction, that is, the shape of the front and back surfaces is different, but because the area of the shield Mc formed is the same on the front and back, the strengthened glass plate G30 The internal and external stress balance will become unbalanced. Therefore, the tempered glass plate G30 deforms itself toward a shape where the stress balance is balanced (see FIG. 9C). [0010] The present invention has been made in consideration of such circumstances, and an object thereof is to provide a method for manufacturing a strengthened glass and a film-coated glass plate capable of stably manufacturing a strengthened glass plate having high flatness and locally high strength. Moreover, this invention aims at providing the tempered glass plate which has high flatness and high strength locally. [Technical Solution to Solve the Problem] [0011] The present invention is to solve the aforementioned problem, and is a method for manufacturing a strengthened glass plate, which is exchanged in the surface with a first main surface and a second main surface, respectively, in thickness. The manufacturing method of an ion-reinforced glass plate with a glass surface layer having an asymmetrical cross-sectional shape in the direction includes a masking step in which at least a part of the first main surface is provided to suppress or prevent the ions. An exchanged first mask is provided with at least a part of the second main surface to provide a second mask that suppresses or prevents the exchange of the ions; and an ion exchange step is performed after the mask step is immersed in the glass plate The molten salt used to exchange the aforementioned ions; in the aforementioned masking step, the formation area of the first mask on the first main surface and the formation area of the second mask on the second main surface correspond to The cross-sectional shape is set to different sizes. [0012] As described above, for the glass plate (raw glass plate) having an asymmetric shape in the thickness direction, the first mask and the second mask having different areas are formed on the main surfaces in accordance with the asymmetric shape, Thereby, the deformation | transformation of the glass plate at the time of strengthening by the ion exchange method can be made as small as possible. Thereby, a tempered glass plate having high flatness and locally high strength can be stably manufactured. [0013] In the manufacturing method, the first main surface has a first flat surface, the second main surface has a second flat surface larger than the first flat surface, and the first mask has The second mask is disposed in the first flat surface, and the second mask is disposed in the second flat surface. The formation area of the second mask is preferably larger than the formation area of the first mask. [0014] In this way, for a raw glass plate having a small area on the first flat surface and a large area on the second flat surface, a first mask having a small area is formed on the first flat surface, and a second area having a large area is formed. The mask is formed on the second flat surface, thereby making it possible to minimize the deformation of the glass plate when the strengthening by the ion exchange method is performed. [0015] Furthermore, in the manufacturing method, the first flat surface is located at a central portion of the first main surface, the first mask is provided at a central portion of the first flat surface, and the second flat surface is The second mask is located at a central portion of the second main surface, and the second mask is provided at a central portion of the second flat surface. The first main surface includes a first cover disposed along an outer edge of the first flat surface. The corner surface, the second main surface includes a second chamfered surface provided along an outer edge of the second flat surface, and an area of the first chamfered surface is larger than an area of the second chamfered surface. Better. [0016] According to this configuration, by forming the first chamfered surface having a larger area than the second chamfered surface along the outer edge of the first flat surface having an area smaller than that of the second flat surface, the first chamfered surface having the first chamfered surface can be formed. The first main surface of the flat surface and the first chamfered surface, and the second main surface having the second flat surface and the second chamfered surface are uniformly subjected to ion exchange treatment. [0017] In the aforementioned manufacturing method, the first mask and the second mask are composed of an inorganic film layer having a composition of SiO ₂ 60 to 100% and Al ₂ O ₃ 0 to 40% in mass% as follows: good. By using the first mask and the second mask of this composition, it is possible to reliably shield or suppress the penetration of ions during ion exchange. [0018] The thickness of the first mask and the thickness of the second mask may be set to be the same or different. For example, in the manufacturing method, the thickness of the second mask is preferably 0.8 to 1.2 times the thickness of the first mask. [0019] In the aforementioned manufacturing method, when the ionic sodium ions on the surface of the glass plate, the molten salt system contains potassium ions, and the molten salt is mixed with water to form an aqueous solution at a concentration of 20% by mass, the pH value is 6.5 to 11 is preferred. In this way, by performing the ion exchange appropriately, it is possible to ensure that the glass plate has the required strength. [0020] In the aforementioned manufacturing method, the glass plate contains 45 to 75% by mass of SiO ₂ , Al ₂ O ₃ 1 to 30%, Na ₂ O 1 to 20%, and K ₂ O 0 to 20 % A glass plate composed of a glass plate is preferred. This makes it easy to achieve a high degree of balance between ion exchange performance and devitrification resistance. [0021] Although the glass plate can be configured in various shapes, in consideration of workability and the like, it is particularly preferably configured in a disc shape or a rectangular shape in plan view. [0022] The present invention is intended to solve the aforementioned problems, and is a film-coated glass plate having a first main surface and a second main surface on the surface and an asymmetrical cross-sectional shape in the thickness direction, respectively. , Characterized in that it includes a first mask formed on at least a part of the first main surface and inhibiting or preventing ion exchange, and a first mask formed on at least a part of the second main surface and inhibiting or preventing ions Exchanged second mask; the formation area of the first mask of the first main surface and the formation area of the second mask of the second main surface are set to different sizes corresponding to the cross-sectional shape . [0023] As described above, for a glass plate having an asymmetric shape in the thickness direction, corresponding to the asymmetric shape, the first mask and the second mask having different areas are formed on the main surfaces, thereby enabling the The deformation of the glass plate during the strengthening by the ion exchange method is as small as possible. Thereby, a tempered glass plate having high flatness and locally high strength can be stably manufactured. [0024] In the film-coated glass plate, the first main surface has a first flat surface, the second main surface has a second flat surface larger than the first flat surface, and the first cover The cover is disposed in the first flat surface, the second mask is disposed in the second flat surface, and a formation area of the second mask is larger than that of the first mask. good. In this way, for a glass plate configured to have a small area on the first flat surface and a large area on the second flat surface, a first mask having a small area is formed on the first flat surface, and a second mask having a large area is formed on the glass plate. The second flat surface can thereby minimize the deformation of the glass plate during the strengthening by the ion exchange method. [0025] The present invention is intended to solve the aforementioned problems, and is a strengthened glass plate having a first main surface and a second main surface on the surface thereof and an asymmetric cross-sectional shape in the thickness direction. It is characterized in that the first main surface has a first flat surface, the second main surface has a second flat surface larger than the first flat surface, and the first flat surface has a shape formed on A first compressive stress layer on the peripheral edge portion thereof, and a second compressive stress layer formed on the central portion thereof with a layer depth smaller than that of the first compressive stress layer, and the second flat surface has a first compressive stress layer formed on the peripheral edge portion. A compressive stress layer, and a second compressive stress layer formed at a central portion thereof with a layer depth smaller than that of the first compressive stress layer, and an area of formation of the second compressive stress layer on the second flat surface is larger than that of the first The formation area of the second compressive stress layer on a flat surface is larger. [0026] As described above, in accordance with the asymmetric shape of the strengthened glass plate, the second compressive stress layers having different areas are formed on the first flat surface and the second flat surface having different areas, so that the strengthened glass plate can be processed. Gives high flatness. Furthermore, a first compressive stress layer having a layer depth greater than that of the second compressive stress layer is formed on the peripheral edge portion of each flat surface, whereby the strengthened glass sheet has high strength locally. [Effects of the Invention] According to the present invention, it is possible to stably produce a strengthened glass plate having high flatness and locally high strength.

[0029] Hereinafter, an embodiment of a method for manufacturing a strengthened glass plate according to the present invention will be described with reference to the drawings. Figures 1 to 6 show the first embodiment of the method for manufacturing a strengthened glass plate of the present invention. [0030] The method for producing a sheet glass of the present invention includes: a step of preparing a raw glass sheet; a selective strengthening step of selectively strengthening a part of the raw glass sheet; and, after the selective strengthening step, strengthening the entire glass sheet Overall strengthening steps. Each step will be described below. First, the processing of the preparation steps shown in FIG. 1A is performed. This preparation step is a step of preparing a raw glass plate G1 having a predetermined shape. [0031] The raw glass plate G1 is a glass plate that can be strengthened by an ion exchange method and has an asymmetric cross-sectional shape in the thickness direction. In this embodiment, a case where the raw glass plate G1 is a disc-shaped glass plate as shown in FIG. 2 will be described as an example. The raw glass plate G1 includes a first main surface Sa and a second main surface Sb, which are in a front-back relationship. In the present embodiment, the first main surface Sa side is referred to as the surface side, and the second main surface Sb side is referred to as the back side. [0032] The first main surface Sa includes a first flat surface Fa and a first chamfered surface Ca. The first flat surface Fa is a flat circular surface provided at a central portion of the first main surface Sa. The first chamfered surface Ca is a flat inclined surface provided along the outer edge of the first flat surface Fa. [0033] The second main surface Sb includes a second flat surface Fb and a second chamfered surface Cb. The second flat surface Fb is a flat circular surface provided at a central portion of the second main surface Sb. The second chamfered surface Cb is a flat inclined surface provided along the outer edge of the second flat surface Fb. [0034] The first chamfered surface Ca and the second chamfered surface Cb are flat surfaces formed by a so-called C-chamfering process. The area of the first chamfered surface Ca is larger than the area of the second chamfered surface Cb. The area of the first flat surface Fa is smaller than the area of the second flat surface Fb. With this configuration, the cross section of the raw glass plate G1 is as shown in FIG. 1A with respect to the center line in the plate thickness direction (a single dotted line in the figure) X on the first main surface Sa side and the second main surface Sb The sides are asymmetrical on the front and back. [0035] Moreover, the aforementioned shape is an example. The first chamfered surface Ca and the second chamfered surface Cb may be curved surfaces formed by a so-called R-chamfering process, and may also be formed by a curved surface having a plurality of curvature radii. can. In addition, the raw glass plate G1 is not limited to a disc-shaped arbitrary shape, and for example, a rectangular glass plate may be used. In addition, the raw glass plate G1 may have a structure having a hole penetrating from the first flat surface Fa to the second flat surface Fb. [0036] The raw glass plate G1 contains 45 to 75% by mass of SiO ₂ , Al ₂ O ₃ 1 to 30%, Na ₂ O 1 to 20%, and K ₂ O 0 to 20% as a glass plate group. Become better. When the composition range of the glass plate is limited as described above, it is easy to achieve both ion exchange performance and devitrification resistance to a high degree. [0037] The thickness of the raw glass plate G1 is, for example, 2.0 mm or less, preferably 1.5 mm or less, 1.3 mm or less, 1.0 mm or less, 0.8 mm or less, 0.7 mm or less, 0.6 mm or less, 0.5 mm or less, 0.4 mm or less, 0.3 mm or less, 0.2 mm or less, and especially 0.1 mm or less. The smaller the thickness of the raw glass plate G1 is, the more the tempered glass plate substrate can be made lighter. Therefore, the device can be made thinner and lighter. Moreover, considering productivity and the like, the thickness of the raw glass plate G1 is preferably 0.01 mm or more. [0038] The raw glass plate G1 is formed by, for example, an overflow down-draw method, is cut by a cutting edge, and is subjected to chamfering and end surface grinding processing by a rotary grindstone tool. The method of forming or processing the raw glass plate G1 can be arbitrarily selected. For example, the raw glass plate G1 may be formed by a float method, may be cut by laser light, or may be subjected to a grinding process using a polishing tape. [0039] Next, after the aforementioned preparatory steps, the processing of the selective strengthening step shown in FIGS. 1B and 1C is performed. The selective enhancement step includes a masking step shown in FIG. 1B and a selective ion exchange step shown in FIG. 1C. [0040] The masking step is a step of forming a first mask Ma and a second mask Mb on a part of the first main surface Sa and the second main surface Sb of the raw glass plate G1 to obtain a film-coated glass plate G2. The first mask Ma and the second mask Mb are film layers that suppress or shield the penetration of ions during the ion exchange of the surface layer of the raw glass plate G1 in a selective ion exchange step described later. [0041] As shown in FIG. 3, the first mask Ma covers the central portion Fa1 of the first flat surface Fa and exposes the peripheral edge portion Fa2 of the first flat surface Fa and the first chamfered surface Ca. Is formed on the first main surface Sa. The peripheral edge portion Fa2 of the first flat surface Fa is a first flat surface Fa including a boundary portion of the first flat surface Fa to the first chamfered surface Ca, and a range of several mm to several tens mm from the boundary portion. (Hereinafter, the same applies to the second flat surface Fb). [0042] The peripheral edge portion Fa2 of the first flat surface Fa is configured in a ring shape so as to surround the periphery of the central portion Fa1 of the first flat surface Fa. When the first flat surface Fa is circular, the peripheral edge portion Fa2 is also formed in a circular shape (ring shape) according to the shape. Of course, in the case where the first flat surface Fa is rectangular, the peripheral edge portion Fa2 is also configured to be rectangular corresponding to this. [0043] As shown in FIG. 4, the second mask Mb covers the central portion Fb1 of the second flat surface Fb and exposes the peripheral edge portion Fb2 and the second chamfered surface Cb of the second flat surface Fb. Is formed on the second main surface Sb. [0044] As shown in FIG. 3 and FIG. 4, the first mask Ma and the second mask Mb are formed in a circular shape so as to correspond to the shapes of the first flat surface Fa and the second flat surface Fb. The diameter Wma of the first mask Ma is smaller than the diameter Wfa of the first flat surface Fa, and the diameter Wmb of the second mask Mb is smaller than the diameter Wfb of the second flat surface Fb. Therefore, the area of the first mask Ma is smaller than the area of the first flat surface Fa, and the area of the second mask Mb is smaller than the area of the second flat surface Fb. The diameter Wmb of the second mask Mb is larger than the diameter Wma of the first mask Ma. Therefore, the area of the second mask Mb is larger than that of the first mask Ma. [0045] The difference (Wfa-Wma) between the diameter Wfa of the first flat surface Fa and the diameter Wma of the first mask Ma is preferably 0.1 mm or more and 5 mm or less. The difference (Wfb-Wmb) between the diameter Wfb of the second flat surface Fb and the diameter Wmb of the second mask Mb is preferably 0.1 mm or more and 10 mm or less. The difference (Wmb-Wma) between the diameter Wma of the first mask Ma and the diameter Wmb of the second mask Mb is preferably 0.1 mm or more and 3 mm or less. However, these numerical values are not limited to the aforementioned range, and can be appropriately set in accordance with the size of the raw glass plate G1. [0046] The first mask Ma is located in the plane of the first flat surface Fa, specifically, it is located in a concentric shape with the first flat surface Fa. Similarly, the second mask Mb is located in the plane of the second flat surface Fb, and is located concentrically with the second flat surface Fb. In FIGS. 3 and 4, in order to emphasize the first mask Ma and the second mask Mb, hatching is applied to these. [0047] As the material of the first mask Ma and the second mask Mb, any material can be used as long as it can suppress or shield the penetration of ions subjected to ion exchange. When the ion being exchanged is an alkali metal ion, the first mask Ma and the second mask Mb are, for example, a metal oxide, a metal nitride, a metal carbide, a metal oxynitride, a metal oxycarbide, or a metal. Carbonitride films and the like are preferred. In addition, a carbon material, a metal, or an alloy excellent in heat resistance or chemical durability can be used as the first mask Ma and the second mask Mb. In more detail, the materials of the first mask Ma and the second mask Mb can include, for example, SiO ₂ , Al ₂ O ₃ , SiN, SiC, AlN, ZrO ₂ , TiO ₂ , Ta ₂ O ₅ , One or more films of Nb ₂ O ₅ , HfO ₂ , SnO ₂ , carbon nanotube, graphene, diamond-like carbon, and stainless steel. [0048] In particular, if SiO _{2 is} used as a main component of the first mask Ma and the second mask Mb, the first mask Ma and the second mask Mb can be formed inexpensively and easily, and can be used as an antimonitor. The function of the reflective film is preferred. The first mask Ma and the second mask Mb may be films made of only SiO ₂ . Specifically, the first mask Ma and the second mask Mb may be a composition having 99% or more of SiO ₂ by mass%. [0049] In a case where the penetration of ions is to be surely shielded, an inorganic film layer containing SiO ₂ as a main component and containing Al ₂ O ₃ is preferably used as the first mask Ma and the second mask Mb. At this time, the first mask Ma and the second mask Mb contain SiO ₂ 20 to 99% and Al ₂ O ₃ 1 to 80%, more preferably SiO ₂ 60 to 99%, and Al ₂ O _{3 has} a composition of 1 to 40%. [0050] The thicknesses of the first mask Ma and the second mask Mb may be any thickness as long as they can shield and suppress ion penetration. However, if the thicknesses of the first mask Ma and the second mask Mb are too large, the film formation time, material cost, and the like may increase. Therefore, it is better to form as thin as possible within a range capable of shielding and suppressing ion penetration . Specifically, the film thicknesses of the first mask Ma and the second mask Mb are, for example, preferably from 1 to 5000 nm, and more preferably from 50 to 4000 nm. The film thickness of the first mask Ma and the film thickness of the second mask Mb may be set to be the same, or may be set to be different. For example, the thickness of the second mask Mb is preferably 0.8 to 1.2 times the thickness of the first mask Ma. [0051] The film formation method of the first mask Ma and the second mask Mb can be a PVD method (physical vapor deposition method) such as a sputtering method or a vacuum evaporation method, a thermal CVD method, or a plasma CVD method. Wet coating methods such as a CVD method (chemical vapor deposition method), a dip coating method, or a slit coating method. Particularly, a sputtering method and a dip coating method are preferred. When the sputtering method is used, the first mask Ma and the second mask Mb can be easily and uniformly formed. The film formation sites of the first mask Ma and the second mask Mb can be set by any method. In addition, the first mask Ma and the second mask Mb, which are formed into a sheet shape in advance, may be bonded to the main surfaces Sa and Sb of the raw glass plate G1 to form a film. [0052] In this embodiment, a first mask Ma and a second mask Mb, which contain SiO ₂ and Al ₂ O ₃ and have a film thickness of 100 nm or more, can shield the penetration of alkali metal ions. The case will be described as an example. [0053] Next, after the aforementioned masking step, the processing of the selective ion exchange step shown in FIG. 1C is performed. The selective ion exchange step is a step of chemically strengthening the coated glass plate G2 by an ion exchange method to obtain a coated glass plate G3. Specifically, ion-exchange is performed by immersing the coated glass plate G2 in a molten salt T1 containing an alkali metal ion. The molten salt T1 in this embodiment is, for example, a potassium nitrate molten salt. When the molten salt T1 is mixed with water to form an aqueous solution at a concentration of 20% by mass, the pH is preferably 6.5 to 11. [0054] In this selective ion exchange step, a part of each of the main surfaces Sa and Sb covered by the masks Ma and Mb is used as a non-selected area, and exposed without being covered by the masks Ma and Mb. As a selection area. Specifically, the non-selected region is a central portion Fa1 of the first flat surface Fa and a central portion Fb1 of the second flat surface Fb. The selection area is a peripheral edge portion Fa2 of the first flat surface Fa2, a peripheral edge portion Fb2 of the second flat surface Fb2, a first chamfered surface Ca, a second chamfered surface Cb, and an end surface E. [0055] The temperature of the molten salt T1 in the selective ion exchange step can be arbitrarily set, for example, 350 to 500 ° C, preferably 370 to 480 ° C, more preferably 380 to 450 ° C, and still more preferably 380 to 400 ° C. In addition, the time for immersing the coated glass plate G2 in the molten salt T1 can be arbitrarily set, for example, 0.1 to 150 hours, preferably 0.3 to 100 hours, and more preferably 0.5 to 50 hours. [0056] In the aforementioned selective ion exchange step, in the surface of the glass-coated glass plate G2, in the selection area where the first mask Ma and the second mask Mb are not provided, the sodium ion and the molten salt T1 in the glass plate Potassium ions are exchanged. Thereby, the first compressive stress layer CP1 is formed in the selected area. On the other hand, in the surface of the film-coated glass plate G2, in the central portions Fa1 and Fb1 where the first mask Ma and the second mask Mb are provided, since the ions are shielded, a compressive stress layer is not formed. Through the above-mentioned selective ion exchange step, a film-reinforced glass plate G3 having a first compressive stress layer CP1 formed in a selected region is obtained. [0057] Next, after the aforementioned selective ion exchange step, the processing of the mask removal step shown in FIG. 1D is performed. The mask removing step is a step of removing each of the masks Ma and Mb from the film-reinforced glass plate G3. Specifically, each of the masks Ma and Mb is removed by polishing. As the polishing device, a well-known polishing device can be used, and it is particularly preferable to use a double-sided polishing device. [0058] It is not limited to polishing, and the masks Ma and Mb may be removed by other methods. For example, the masks Ma and Mb may be removed by attaching an etching solution. When each of the masks Ma and Mb is a film containing SiO ₂ , for example, fluorine, tetramethylammonium hydroxide (TMAH), ethylenediamine catechol (EDP), potassium hydroxide, and hydroxide can be used. A solution such as sodium is used as the etching solution, and a hydrofluoric acid solution is particularly used as the etching solution. When it is desired to use a hydrofluoric acid solution without removing the masks Ma and Mb without changing the glass size, the HF concentration of the hydrofluoric acid solution is preferably 10% or less. [0059] If each of the masks Ma and Mb is removed by the process of the mask removal step, no compressive stress layer is formed on each of the central portions Fa1 and Fb1 of the flat surfaces Fa and Fb, and the flat surfaces Fa, A strengthened glass plate G4 (see FIG. 1D) in which a first compressive stress layer CP1 is formed in each peripheral edge portion Fa2, Fb2, each chamfered surface Ca, Cb, and end surface E of Fb (see FIG. 1D). [0060] Next, in order to strengthen the tempered glass sheet G4 as a whole, the entire tempering step is performed. The whole strengthening step is a step of exchanging the surface of the strengthened glass plate G4 with the molten salt T2 as a whole, as shown in FIG. 1E, to exchange ions on the surface layer. Specifically, the strengthened glass plate G4 is immersed in a molten salt T2 containing an alkali metal ion to perform ion exchange, and a second compressive stress layer CP2 is formed at each central portion Fa1 and Fb1 of each flat surface Fa, Fb. Furthermore, ion exchange is performed on the first compressive stress layer CP1 to increase its depth. The molten salt T2 is, for example, a potassium nitrate molten salt. [0061] The temperature of the molten salt T2 in the overall strengthening step can be arbitrarily set, for example, 350 to 500 ° C, preferably 370 to 480 ° C, and more preferably 380 to 450 ° C. In addition, the time for immersing the strengthened glass plate G4 in the molten salt T2 can be arbitrarily set, for example, 0.1 to 72 hours, preferably 0.3 to 50 hours, and more preferably 0.5 to 24 hours. [0062] The molten salt T2 may be the same as the aforementioned molten salt T1. That is, the tempered glass plate G4 may be immersed again in the molten salt T1 used in the selective tempering step. In this case, since a plurality of steps can be processed by a single salt bath, the cost of manufacturing equipment can be suppressed. [0063] In addition, the molten salt T2 may be different from the molten salt T1, and the processing temperature and processing time in the overall strengthening step may be different from the processing temperature and processing time in the selective ion exchange step. For example, the processing time of the ion exchange in the overall strengthening step is preferably shorter than the processing time of the selective ion exchange step. By doing so, the depth of the second compressive stress layer CP2 of each central portion Fa1, Fb1 of each flat surface Fa, Fb is not excessive, and an increase in tensile stress can be suppressed. [0064] Through the above-mentioned overall strengthening step, a first compressive stress having a large layer depth (DOL1) is formed at the radial end portions (each peripheral edge portion Fa2, Fb2, each chamfered surface Ca, Cb, and end surface E) Layer CP1, and a strengthened glass plate G5 formed by a second compressive stress layer CP2 having a small layer depth (DOL2) is formed in the central portion (the central portions Fa1 and Fb1 of the flat surfaces Fa and Fb). A second compressive stress layer CP2 having a different area is formed on each of the main surfaces Sa and Sb of the strengthened glass plate G5 so as to correspond to the areas of the first mask Ma and the second mask Mb. That is, the formation area of the second compressive stress layer CP2 of the second flat surface Fb of the strengthened glass plate G5 becomes larger than the formation area of the second compressive stress layer CP2 of the first flat surface Fa. The layer depth (DOL1) of the first compressive stress layer CP1 is preferably 1/4 or less of the thickness of the strengthened glass plate G5. The layer depth (DOL2) of the second compressive stress layer CP2 is preferably 1/8 or less of the thickness of the strengthened glass plate G5. [0065] As described above, in the manufacturing method of the strengthened glass plate G5 of this embodiment, the raw material glass plate G1 having an asymmetric shape in the thickness direction corresponds to the asymmetric shape, and the first masks having different areas are covered. Ma and the second mask Mb are formed on each of the main surfaces Sa and Sb, so that the deformation of the glass plate (film-coated glass plate G2) during the strengthening by the ion exchange method can be made as small as possible. Specifically, in the case of the raw glass plate G1 having a small area of the first flat surface Fa and a large area of the second flat surface Fb, a first mask Ma having a small area is formed on the first flat surface Fa. The second mask Mb having a large area is formed on the second flat surface Fb, and the film-coated glass plate G2 is preferably formed. Thereby, it is possible to stably manufacture a tempered glass plate G5 having high flatness and locally high strength. [0066] In the case of this embodiment, the raw glass plate G1 has a larger area of the first flat surface Fa and the second flat surface Fb than each of the chamfered surfaces Ca and Cb, and thus is formed during ion exchange. The influence of the compressive stress layers on the chamfered surfaces Ca and Cb on the deformation of the coated glass plate G2 is much smaller than the influence of the compressive stress layers formed on the first flat surface Fa and the second flat surface Fb. Therefore, in this embodiment, the first mask Ma and the second mask having different areas are formed only in the central portions Fa1 and Fb1 of the first flat surface Fa and the second flat surface Fb among the main surfaces Sa and Sb. Mb can prevent deformation of the coated glass plate G2. [0067] In the overall strengthening step, although the strengthened glass plate G4 obtained by removing each of the masks Ma and Mb is immersed in molten salt T2 for ion exchange, the selected area is strengthened in the selective strengthening step. Therefore, the deformation system of the strengthened glass plate G4 in the overall strengthening step is extremely slight. [0068] The foregoing matters are not limited to the case of forming a disc-shaped reinforced glass plate G5 having each chamfered surface Ca, Cb, but can be applied to the case of producing a reinforced glass plate G5 of various shapes. FIG. 5 shows an example of a raw glass plate G1 and a coated glass plate G2 when a tempered glass plate G5 having no chamfered surfaces Ca and Cb is manufactured. [0069] As shown in FIG. 5A, the thickness of the end portion of the raw glass plate G1 in the radial direction is configured to be larger than the thickness of the halfway portion. This end portion is configured to have a substantially circular shape in a cross-sectional view, and its diameter is configured to be larger than the thickness of the middle portion of the raw glass plate G1. With this configuration, the raw glass plate G1 is attached to the first main surface Sa and has a convex curved surface CS connected to the first flat surface Fa. In addition, the first mask Ma of the coated glass plate G2 is formed so as to cover not only the first flat surface Fa but also a part of the curved surface CS. In addition, in this example, the area (diameter Wma) of the first mask Ma is set larger than the area (diameter Wmb) of the second mask Mb. In addition, the raw glass plate G1 shown in FIG. 5B is formed with an inclined surface IS so as to be connected to the first flat surface Fa of the first main surface Sa thereof. In this example, the first mask Ma of the coated glass plate G2 is formed not only on the first flat surface Fa, but also on a part of the inclined surface IS. [0070] Further, after the overall strengthening step, a process of further performing a refining processing step may be performed. According to the manufacturing method of the strengthened glass plate G5 of this embodiment, in the selective ion exchange step of the selective strengthening step, not only the deformation of the reinforced glass plate G3 with a film is prevented, but also the The size relationship of the area can also adjust the amount of deformation of the film-reinforced glass plate G3. Therefore, the tempered glass plate G5 that has been subjected to the entire tempering step can also be brought into a deformed state, and a refining process step can be applied to it. [0071] Hereinafter, a case where the tempered glass plate G5 is polished by the double-side polishing device PA will be described as an example of this refining processing step. As shown in FIG. 6, the double-side polishing device PA includes a star wheel CA holding a strengthened glass plate G5, an upper grinding plate SP1 that grinds the first main surface Sa of the strengthened glass plate G5, and a second grinding surface SPb Lower grinding plate SP2. The star wheel CA is provided with a holding hole CAh for holding the tempered glass plate G5 so as not to rotate. [0072] As shown in FIG. 6, the tempered glass plate G5 is deformed in a manner that it protrudes slightly above the first flat surface Fa as the upper side and the second flat surface Fb as the lower side. It fits into the holding hole CAh of the star wheel CA. In this state, the upper polishing platen SP1 is brought into contact with the first main surface Sa, and the lower polishing platen SP2 is brought into contact with the second main surface Sb. Thereafter, the upper polishing platen SP1, the lower polishing platen SP2, and the star wheel CA are relatively moved, and both sides Sa and Sb of the tempered glass plate G5 are polished. [0073] As described above, by performing double-side polishing in a state where some deformation of the tempered glass plate G5 remains, it is possible to obtain a good polished surface for each of the main surfaces Sa and Sb. For example, when the same double-side polishing is performed without deforming the strengthened glass plate G5, the second main surface Sb located on the lower side is excessively polished than the first main surface Sa due to its vertical positional relationship, so There is a possibility that the polishing amounts of the first main surface Sa on the upper side and the second main surface Sb on the lower side may become uneven. On the other hand, since the polishing amount of each of the main surfaces Sa and Sb can be averaged by polishing as described above, it is possible to perform high-precision double-sided polishing. [0074] FIG. 7 shows a second embodiment of the method for manufacturing a strengthened glass plate. In the aforementioned first embodiment, the glass plate (film-coated glass plate G2, strengthened glass plate G4) is immersed in the molten salt T1 and T2 twice by selecting the strengthening step and the overall strengthening step. In this embodiment, the system A tempered glass plate G5 is produced by one-time dipping. [0075] In this embodiment, after preparing the raw glass plate G1 as shown in FIG. 7A, as shown in FIG. 7B, a first mask Ma and a second mask Mb are formed on each of the main surfaces Sa and Sb. A film-coated glass plate G2 was obtained. Different from the first embodiment, in this embodiment, a functional film that suppresses ion penetration is used as the first mask Ma and the second mask Mb. [0076] Thereafter, as shown in FIG. 7C, the coated glass plate G2 having the respective masks Ma and Mb is immersed in the molten salt T1. Thereby, ion exchange is performed on the peripheral edges Fa2, Fb2, the chamfered surfaces Ca, Cb, and the end face E of the flat surfaces Fa, Fb not covered by the respective masks Ma, Mb, and when receiving the respective masks Ma, The Mb-covered central portions Fa1 and Fb1 are also ion-exchanged in a state where ion penetration is suppressed. As a result, a first compressive stress layer CP1 having a large layer depth (DOL1) is formed at the radial end portions (each peripheral edge portion Fa2, Fb2, each chamfered surface Ca, Cb, and end surface E), and the central portion is formed at the central portion thereof. (The central portions Fa1 and Fb1 of each of the flat surfaces Fa and Fb) are formed with a film-reinforced glass plate G3 (see FIG. 7C) with a second compressive stress layer CP2 having a small layer depth (DOL2). Thereafter, by removing the first mask Ma and the second mask Mb of the film-reinforced glass plate G3, a tempered glass plate G4 shown in FIG. 7D is obtained. [0077] The present invention is not limited to the configuration of the aforementioned embodiment, nor is it limited to the aforementioned effects. The present invention can be variously modified without departing from the gist of the present invention. [0078] In the embodiment described above, the case where the sodium ion and the potassium ion are ion-exchanged to chemically strengthen it is exemplified. However, the present invention is not limited to this, and arbitrary ions can be exchanged. For example, tempered glass plates G4 and G5 may be produced by ion exchange of lithium ions and sodium ions, or ion exchange of lithium ions and potassium ions. At this time, the tempered glass plates G4 and G5 preferably contain LiO ₂ in an amount of 0.5 to 7.5% by mass%, and more preferably contain 3.0% or 4.5% LiO ₂ as a composition. [0079] The stress characteristics of the strengthened glass plate can be measured using, for example, FSM-6000 manufactured by Ohara Corporation. When the depth of the compressive stress layer of aluminosilicate glass exceeds 100 μm, or when ion exchange between lithium ions and sodium ions, or ion exchange between lithium ions and potassium ions, the stress characteristics of the glass plate are strengthened. The measurement can be performed using, for example, SLP-1000 manufactured by Ohara Corporation. When a cross-section sample can be produced by cutting a strengthened glass plate or the like, it is preferable to use WPA-micro manufactured by Photonic Lattice or Abrio manufactured by Tokyo Instruments to observe the internal stress distribution and confirm the stress depth. [Examples] [0080] The present inventors took the reinforced sheet glass produced using the present manufacturing method as an example, and manufactured the sheet without using the present manufacturing method (without forming a mask on the raw glass sheet). The tempered glass was used as a comparative example, and the magnitude of the warpage (displacement in the vertical direction) in each example was obtained by calculation (simulation). Each of the tempered glass plates of Examples and Comparative Examples is a disc having a cross-sectional shape that is asymmetrical in the thickness direction. The dimensions of the tempered glass plates of the examples and comparative examples were 1 mm in thickness and 40 mm in outer diameter. In addition, the diameter of the first mask used in the examples was 30 mm, and the diameter of the second mask was 36 mm. [0081] As a result of the calculation, it was found that the warpage with respect to the example was 0.0 μm, and the warpage with the comparative example was 23.7 μm. Fig. 8 is a visualization of the operation result by gray scale. FIG. 8A shows an example, and FIG. 8B shows a comparative example. As shown in FIGS. 8A and 8B, it can be seen that the warped amount (displacement in the vertical direction) of the tempered glass sheet of the comparative example becomes larger as it goes outward in the radial direction, and the tempered glass sheet of the example has no warp at all. In addition, the tempered glass plate of the embodiment shown in FIG. 8A is shown with a solid border. This solid line is used to make the boundary of the tempered glass sheet clear and appended, and has nothing to do with the warping of the tempered glass sheet.

[0082]

Ca‧‧‧First chamfered surface

Cb‧‧‧Second chamfered surface

Fa‧‧‧First flat surface

Fb‧‧‧ second flat surface

G1‧‧‧ raw glass plate

G2‧‧‧ with glass

G3 ‧‧‧ with strengthened glass plate

G4‧‧‧Tempered glass

G5‧‧‧Tempered glass

Ma‧‧‧First Mask

Mb‧‧‧Second Mask

Sa‧‧‧First major surface

Sb‧‧‧Second major surface

T1‧‧‧ molten salt

T2‧‧‧ molten salt

[0028] [FIG. 1A] FIG. 1A illustrates a method for manufacturing a strengthened glass plate according to a first embodiment of the present invention. [Fig. 1B] Fig. 1B shows a method for manufacturing a strengthened glass plate according to the first embodiment of the present invention. [FIG. 1C] FIG. 1C shows a method for manufacturing a strengthened glass plate according to the first embodiment of the present invention. [Fig. 1D] Fig. 1D shows a method for manufacturing a strengthened glass plate according to the first embodiment of the present invention. [Fig. 1E] Fig. 1E shows a method for manufacturing a strengthened glass plate according to the first embodiment of the present invention. [Fig. 2] Fig. 2 is a perspective view of a raw glass plate.第 [Fig. 3] Fig. 3 is a plan view of a film-attached glass plate.第 [Fig. 4] Fig. 4 is a bottom view of the attached glass plate. [Fig. 5A] Fig. 5A is a special cross-sectional view showing another example of a coated glass plate. [FIG. 5B] FIG. 5B is a special partial cross-sectional view showing another example of the coated glass plate.第 [FIG. 6] FIG. 6 is a view showing a refining process step. [FIG. 7A] FIG. 7A shows a method for manufacturing a strengthened glass plate according to a second embodiment of the present invention. [FIG. 7B] FIG. 7B shows a method for manufacturing a strengthened glass plate according to a second embodiment of the present invention. [FIG. 7C] FIG. 7C shows a method for manufacturing a strengthened glass plate according to a second embodiment of the present invention. [FIG. 7D] FIG. 7D shows a method for manufacturing a strengthened glass plate according to a second embodiment of the present invention. [FIG. 8A] FIG. 8A is a plan view showing an example of a tempered glass plate. [FIG. 8B] FIG. 8B is a plan view showing a comparative example of a tempered glass plate. [Fig. 9A] Fig. 9A shows a method for manufacturing a conventional tempered glass sheet. [Fig. 9B] Fig. 9B shows a method for manufacturing a conventional tempered glass sheet. [Fig. 9C] Fig. 9C shows a conventional method for manufacturing tempered glass.

Claims (11)

A method for manufacturing a strengthened glass plate, which is a method for manufacturing an ion-reinforced glass plate that exchanges ions of a glass plate surface layer having a first main surface and a second main surface on the surface and an asymmetric cross-sectional shape in the thickness direction, characterized in The method includes: (1) A masking step, wherein a first mask for suppressing or preventing the exchange of the ions is provided on at least a part of the first main surface, and a mask for suppressing or preventing the ions is provided on at least a part of the second main surface; An exchanged second mask; and an ion exchange step, after the aforementioned masking step, immersing the glass plate in a molten salt used to exchange the aforementioned ions; in the aforementioned masking step, the first The formation area of a mask and the formation area of the second mask on the second main surface are set to different sizes corresponding to the cross-sectional shape. The method for manufacturing a strengthened glass plate according to claim 1, wherein: the first main surface has a first flat surface, and the second main surface has a second flat surface larger than the first flat surface. The first mask is disposed in the first flat surface, The second mask is disposed in the second flat surface, and the formation area of the second mask is larger than that of the first mask. The formation area is larger. The method for manufacturing a strengthened glass plate according to claim 2, wherein: the first flat surface is located at a central portion of the first main surface, the first mask is provided at a central portion of the first flat surface, the first The second flat surface is located at the central portion of the second main surface. The second mask is provided at the central portion of the second flat surface. The first main surface is provided with an outer edge along the first flat surface. The first chamfered surface provided is: the second main surface is provided with a second chamfered surface provided along the outer edge of the second flat surface; the area of the first chamfered surface is larger than the second chamfered surface. The surface area is larger. The method for manufacturing a strengthened glass plate according to any one of claims 1 to 3, wherein the first mask and the second mask include 60 to 100% by mass of SiO ₂ and Al ₂ O ₃ 0 to 40% is an inorganic film layer having a composition. The method for manufacturing a strengthened glass plate according to any one of claims 1 to 3, wherein the thickness of the second mask is 0.8 to 1.2 times the thickness of the first mask. The method for producing a strengthened glass plate according to any one of claims 1 to 3, wherein: the ionic sodium ions on the surface of the glass plate, the molten salt system contains potassium ions, the molten salt system, with a concentration of 20 mass When the% method is mixed with water to form an aqueous solution, the pH is 6.5 to 11. The method for manufacturing a strengthened glass plate according to any one of claims 1 to 3, wherein the glass plate contains 45 to 75% by mass of SiO ₂ , Al ₂ O ₃ 1 to 30%, and Na ₂ O 1 to 20% and K ₂ O 0 to 20% are glass plates composed of glass plates. The method for manufacturing a strengthened glass plate according to any one of claims 1 to 3, wherein the glass plate is disc-shaped or rectangular when viewed from above. A film-coated glass plate is a film-coated glass plate having a first main surface and a second main surface on the surface and an asymmetrical cross-sectional shape in the thickness direction, and is characterized in that: formed on the first main surface At least a part of the first mask that inhibits or prevents ion exchange, and a second mask that is formed on at least a part of the second major surface and inhibits or prevents ion exchange; The formation area of the first mask and the formation area of the second mask on the second main surface are set to different sizes corresponding to the cross-sectional shape. The coated glass plate according to claim 9, wherein: ， the first main surface has a first flat surface, the second main surface has a second flat surface larger than the first flat surface, The first mask is disposed in the first flat surface, the second mask is disposed in the second flat surface, and the formation area of the second mask is larger than the formation area of the first mask. Bigger. A reinforced glass plate is a reinforced glass plate having a first main surface and a second main surface on the surface and an asymmetrical cross-sectional shape in the thickness direction, and is characterized in that: The first main surface has the first surface. A flat surface, the second main surface has a second flat surface larger than the first flat surface, the first flat surface has a first compressive stress layer formed at a peripheral portion thereof, and is formed at a center thereof A second compressive stress layer having a layer depth smaller than that of the first compressive stress layer; the second flat surface includes a first compressive stress layer formed at a peripheral portion thereof, and a layer depth ratio formed at a central portion thereof; The second compressive stress layer having a smaller first compressive stress layer, and the formation area of the second compressive stress layer on the second flat surface is larger than the area of formation of the second compressive stress layer on the first flat surface. .