JPWO2018066314A1 - Method of manufacturing tempered glass plate, film-coated glass plate and tempered glass plate - Google Patents

Abstract

The method suppresses or prevents the exchange of ions on at least a part of the second main surface Sb, which suppresses or prevents the exchange of ions on at least a part of the first main surface Sa in the glass plate G1. The mask process which provides the 2nd mask Mb each, The ion exchange process made to immerse the glass plate G2 in the molten salt for exchanging ion after a mask process is provided. In the mask process, the formation area of the first mask Ma on the first main surface Sa and the formation area of the second mask Mb on the second main surface Sb are set to different sizes according to the cross-sectional shape of the glass plate G1. .

Description

  The present invention relates to a method for producing a tempered glass sheet, and more specifically to a method for producing a tempered glass sheet which chemically strengthens a glass sheet by an ion exchange method, a film-coated glass sheet and a tempered glass sheet.

  In recent years, chemically strengthened tempered glass plates have been used for electronic devices such as mobile phones and cameras, display surfaces such as large displays and personal computers, and cover glasses for wearable terminals such as watches.

  Such a tempered glass sheet is generally manufactured by chemically treating a glass sheet containing an alkali metal as a composition with a reinforcing liquid to form a compressive stress layer on the surface. Such a tempered glass sheet has improved impact resistance and the like because it has a compressive stress layer on the surface. However, even with such a tempered glass plate, the impact resistance at the edge portion and the peripheral portion is lower than the impact resistance at the main surface, which causes the breakage of the tempered glass plate. When the compressive stress layer on the surface of the tempered glass plate is made deep as a whole to prevent such breakage, the tensile stress formed inside the glass plate becomes excessive, and the breakage caused by the tensile stress (so-called self-destruction) Problem is likely to occur.

  In order to solve the above problems, a technology has been developed to selectively form a deep compressive stress layer only on a portion of the surface of a strengthened glass sheet. For example, in the method disclosed in Patent Document 1, by shielding only the central portion of the main surface with the mask material, only the non-shielded peripheral portion can be ion-exchanged and reinforced (first reinforcement processing) . Thereafter, by removing the shielding and performing the strengthening treatment (the second strengthening treatment) again, the compressive stress layer can be formed deeper than the main surface at the edge portion subjected to the strengthening treatment in advance.

JP-A-2014-510012 gazette

  However, when a method like patent document 1 was used, there existed a possibility that a deformation might arise in a glass plate and productivity might fall.

  For example, as shown in FIG. 9, when the cross-sectional shape of the glass plate is asymmetrical in the thickness direction, there is a possibility that the glass plate may be bent and deformed so as to be warped when ion exchange is performed. Hereinafter, with reference to FIG. 9, the manufacturing method of the conventional tempered glass board and its problem are concretely demonstrated.

  FIG. 9A shows a process of preparing a glass sheet 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 a central line (dotted line in the figure) X10 in the thickness direction as an axis. FIG. 9B shows a step of obtaining a film-coated glass plate G20 in which shields Mc having the same thickness and the same area are provided on the front and back main surfaces of the glass plate G10. FIG. 9C shows a strengthening step (first strengthening treatment) of immersing the film-coated glass plate G20 in molten salt T10 and performing ion exchange treatment to obtain a strengthened glass plate G30 having a compressive stress layer CP in the surface layer portion.

  According to these processes, although the cross-sectional shape of the strengthened glass sheet G30 is asymmetrical in the thickness direction, that is, although the front and back surface shapes are different, the area etc. of the shield Mc formed is the same on the front and back. It will be in the state which the stress balance of the front and back of glass plate G30 is not balanced. As a result, the tempered glass sheet G30 naturally deforms to a shape in which the stress balance is balanced (see FIG. 9C).

  The present invention has been made in consideration of such circumstances, and a method for producing a tempered glass capable of stably producing a tempered glass sheet having high flatness and partially high strength, and It aims at providing a film-coated glass plate. Another object of the present invention is to provide a tempered glass sheet having high flatness and partially high strength.

  The present invention is to solve the above-mentioned problems, and exchanges ions of the surface layer of a glass plate having a first main surface and a second main surface on the front and back and having a cross-sectional shape asymmetric in the thickness direction. It is a manufacturing method of a tempered glass board, Comprising: The first mask which controls or prevents exchange of the ion in at least one copy of the 1st main surface, and suppresses the exchange of the ion at least one copy of the second main surface And an ion exchange step of immersing the glass plate in a molten salt for exchanging the ions after the mask step, and a mask step of providing a second mask for preventing each of the first and second mask steps. The formation area of the first mask on the main surface and the formation area of the second mask on the second main surface may be set to different sizes according to the cross-sectional shape.

  As described above, by forming the first mask and the second mask having different areas on the respective main surfaces according to the asymmetrical shape, with respect to the glass plate (original glass plate) having the asymmetrical shape in the thickness direction, In the case of strengthening by ion exchange, deformation of the glass plate can be reduced as much as possible. This makes it possible to stably manufacture a tempered glass sheet having high flatness and partially high strength.

  In the above 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 is Preferably, the first mask is provided in a first flat surface, the second mask is provided in the second flat surface, and a formation area of the second mask is larger than a formation area of the first mask.

  Thus, the first mask having a small area is formed on the first flat surface with respect to the original glass plate in which the area of the first flat surface is small and the area of the second flat surface is large. By forming the second mask on the second flat surface, it is possible to minimize the deformation of the glass plate when strengthening by the ion exchange method.

  Furthermore, in the present manufacturing method, the first flat surface is located at the central portion of the first main surface, the first mask is provided at the central portion of the first flat surface, and the second flat surface is the first flat surface. Located at the center of two major surfaces, the second mask is provided at the center of the second flat surface, and the first major surface is a first chamfer provided along the outer edge of the first flat surface A second chamfered surface provided along an outer edge of the second flat surface, the area of the first chamfered surface being larger than the area of the second chamfered surface Is preferred.

  According to this configuration, the first flat surface and the second flat surface are formed 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 a smaller area than the second flat surface. The ion exchange treatment can be performed in a well-balanced manner on the first main surface having one chamfered surface and the second main surface having the second flat surface and the second chamfered surface.

In the above manufacturing method, it is desirable that the first mask and the second mask be an inorganic film layer containing 60 to 100% of SiO _{2 and} 0 to 40% of Al ₂ O _{3 in} terms of mass% as a composition. By using the first mask and the second mask of such composition, it becomes possible to reliably block or suppress the permeation of ions during ion exchange.

  The thickness of the first mask and the thickness of the second mask may be the same or different. For example, in the above manufacturing method, the thickness of the second mask is preferably 0.8 to 1.2 times the thickness of the first mask.

  In the above manufacturing method, the ion of the surface layer of the glass plate is a sodium ion, the molten salt contains a potassium ion, and the molten salt has a pH when mixed with water to form an aqueous solution having a concentration of 20% by mass. It is desirable that it is 6.5-11. Thus, the strength required for the glass plate can be secured by suitably performing the ion exchange.

In the above manufacturing method, the glass plate, by mass% as a glass plate _{composition, SiO 2 45~75%, Al 2} O 3 1~30%, Na 2 O 1~20%, K 2 O 0~20% It is desirable that it is a glass plate containing This makes it easy to achieve both ion exchange performance and devitrification resistance at high levels.

  The glass plate may be formed into various shapes, but in consideration of its processability and the like, it is desirable that the glass plate be formed particularly in a disk shape or a rectangular shape in plan view.

  The present invention is to solve the above-mentioned problems, and is a film-coated glass plate having a first main surface and a second main surface on the front and back and having an asymmetrical cross-sectional shape in the thickness direction, A first mask that is formed on at least a portion of the first main surface and that suppresses or prevents ion exchange, and is formed on at least a portion of the second main surface, and suppresses or prevents ion exchange And 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 are set to different sizes according to the cross-sectional shape. It is characterized by

  As described above, for the glass plate having an asymmetric shape in the thickness direction, the first mask and the second mask having different areas are formed on each main surface according to the asymmetric shape, thereby strengthening by the ion exchange method Deformation of the glass plate in the case where This makes it possible to stably manufacture a tempered glass sheet having high flatness and partially high strength.

  In the above-mentioned 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 mask is Preferably, the first mask is provided in the first flat surface, the second mask is provided in the second flat surface, and a formation area of the second mask is larger than a formation area of the first mask. Thus, a first mask having a small area is formed on the first flat surface, and a second area having a large area is formed on the glass plate having a small first flat surface area and a large second flat surface area. By forming the mask on the second flat surface, it is possible to minimize the deformation of the glass plate when strengthening by the ion exchange method.

  The present invention is to solve the above-mentioned problems, and is a tempered glass plate having a first main surface and a second main surface on the front and back and having an asymmetrical cross-sectional shape in the thickness direction, 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 is formed on the periphery thereof It has a first compressive stress layer, and a second compressive stress layer formed in the central portion thereof and having a layer depth smaller than that of the first compressive stress layer, and the second flat surface is formed on the periphery thereof First compressive stress layer, and a second compressive stress layer formed in a central portion thereof and having a layer depth smaller than that of the first compressive stress layer, and the second compression on the second flat surface In particular, the formation area of the stress layer is larger than the formation area of the second compressive stress layer on the first flat surface. To.

  As described above, according to the asymmetric shape of the tempered glass sheet, the second compressive stress layer having different areas is formed on the first flat surface and the second flat surface of different areas, so that the flat surface is highly flat. Can be given. Furthermore, by forming the first compressive stress layer having a layer depth larger than that of the second compressive stress layer on the peripheral portion of each flat surface, the strengthened glass sheet partially has high strength.

  According to the present invention, it is possible to stably manufacture a tempered glass sheet having high flatness and partially high strength.

FIG. 1A shows a method of manufacturing a tempered glass sheet according to a first embodiment of the present invention. FIG. 1B shows the manufacturing method of the tempered glass board which concerns on 1st embodiment of this invention. FIG. 1C shows the manufacturing method of the tempered glass board which concerns on 1st embodiment of this invention. FIG. 1D shows a method of manufacturing a tempered glass sheet according to a first embodiment of the present invention. FIG. 1E shows the manufacturing method of the tempered glass board which concerns on 1st embodiment of this invention. FIG. 2 is a perspective view of the original glass plate. FIG. 3 is a plan view of a film-coated glass plate. FIG. 4 is a bottom view of the film-coated glass plate. FIG. 5A is a sectional view of an essential part showing another example of the film-coated glass plate. FIG. 5B is a sectional view of an essential part showing another example of the film-coated glass plate. FIG. 6 is a diagram showing a finishing process. FIG. 7A shows a method of manufacturing a tempered glass sheet according to a second embodiment of the present invention. FIG. 7B shows a method of manufacturing a tempered glass sheet according to a second embodiment of the present invention. FIG. 7C shows a method of manufacturing a tempered glass sheet according to a second embodiment of the present invention. FIG. 7D shows a method of manufacturing a tempered glass sheet according to a second embodiment of the present invention. FIG. 8A is a plan view showing an embodiment and an embodiment of a tempered glass sheet. FIG. 8B is a plan view showing an example and a comparative example of a tempered glass sheet. FIG. 9A shows a method of manufacturing a conventional tempered sheet glass. FIG. 9B shows a method of manufacturing a conventional tempered sheet glass. FIG. 9C shows a method of manufacturing a conventional tempered sheet glass.

  Hereinafter, the form for enforcing the manufacturing method of the tempered glass board concerning the present invention is explained, referring to drawings. 1 to 6 show a first embodiment of the method for producing a tempered glass sheet according to the present invention.

  The method for producing a flat glass according to the present invention comprises the steps of preparing a base glass, a selective strengthening step of selectively strengthening a part of the original glass plate, and overall strengthening of the glass plate after the selective strengthening step. And a strengthening process. Each step will be described below. First, the process of the preparation process shown in FIG. 1A is performed. This preparation process is a process of preparing the original glass plate G1 of a predetermined shape.

  The original glass plate G1 is a glass plate which can be strengthened using an ion exchange method, and whose cross-sectional shape is asymmetric in the thickness direction. In this embodiment, the case where the original glass plate G1 is a disk-shaped glass plate as shown in FIG. 2 will be described as an example. The original glass plate G1 includes a first main surface Sa and a second main surface Sb which are in a front-back relationship with each other. In the present embodiment, the first main surface Sa side is described as the surface side, and the second main surface Sb side is described as the back surface side.

  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 the 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.

  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 the center of the second main surface Sb. The second chamfered surface Ca is a flat inclined surface provided along the outer edge of the second flat surface Fb.

  The first chamfered surface Ca and the second chamfered surface Cb are flat surfaces formed by so-called C-chamfering. The area of the first chamfered surface Ca is larger than the area of the second chamfered surface Cb. In addition, the area of the first flat surface Fa is smaller than the area of the second flat surface Fa. With this configuration, as shown in FIG. 1A, the cross section of the original glass plate G1 is on the first main surface Sa side and the second main surface Sb side with respect to the center line X in the thickness direction (dotted line in FIG. 1). It becomes an asymmetric shape on the front and back.

  The above-described shape is an example, and the first chamfered surface Ca and the second chamfered surface Cb may be curved surfaces formed by so-called R-chamfering, and may be configured by curved surfaces having a plurality of curvature radii. . Further, the original glass plate G1 is not limited to a disk shape, and may be an arbitrary shape, for example, a rectangular glass plate. The original glass plate G1 may be configured to have a hole penetrating from the first flat surface Fa to the second flat surface Fb.

The original glass plate G1 may contain 45 to 75% of SiO ₂ , 1 to 30% of Al ₂ O _3, 1 to 20% of Na ₂ O, and 0 to 20% of K ₂ O by mass% as a glass plate composition. preferable. By regulating the glass sheet composition range as described above, it is easy to achieve both ion exchange performance and devitrification resistance at high levels.

  The thickness of the original 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, particularly 0.1. It is 1 mm or less. As the thickness of the original glass plate G1 is smaller, the tempered glass plate substrate can be reduced in weight, and as a result, reduction in thickness and weight of the device can be achieved. The thickness of the original glass plate G1 is preferably 0.01 mm or more in consideration of productivity and the like.

  The original glass plate G1 is formed, for example, using an overflow downdraw method, cut using a scribe chip, and chamfered and edge-polished with a rotary grinding tool. In addition, the forming method and processing method of the original glass plate G1 may be arbitrarily selected. For example, the original glass plate G1 may be formed using a float method, may be cut using a laser beam, and may be polished using an abrasive tape.

  Then, after the above-mentioned preparation process, the process of the selective strengthening process shown in FIG. 1B and FIG. The selective strengthening process includes the mask process shown in FIG. 1B and the selective ion exchange process shown in FIG. 1C.

  The mask process is a process of forming the first mask Ma and the second mask Mb on a part of the first main surface Sa and the second main surface Sb of the original glass plate G1 to obtain the film-coated glass plate G2. The first mask Ma and the second mask Mb are film layers that suppress or block the permeation of ions when performing ion exchange of the surface layer of the original glass plate G1 in the selective ion exchange process described later.

  As shown in FIG. 3, the first mask Ma covers the central portion Fa1 of the first flat surface Fa and exposes the peripheral portion Fa2 of the first flat surface Fa and the first chamfered surface Ca. It is formed on the main surface Sa. The peripheral portion Fa2 of the first flat surface Fa includes a boundary portion of the first flat surface Fa with respect to the first chamfered surface Ca, and a portion of the first flat surface Fa in a range of several mm to several tens of mm from this boundary portion (Hereinafter, the same applies to the second flat surface Fb).

  The peripheral portion Fa2 of the first flat surface Fa is annularly configured to surround the center portion Fa1 of the first flat surface Fa. When the first flat surface Fa has a circular shape, the peripheral edge portion Fa2 is also formed in a circular shape (ring shape) according to the shape. Naturally, in the case where the first flat surface Fa is rectangular, the peripheral portion Fa2 is configured to be rectangular accordingly.

  As shown in FIG. 4, the second mask Mb covers the central portion Fb1 of the second flat surface Fb and exposes the peripheral portion Fb2 of the second flat surface Fb and the second chamfered surface Cb. It is formed on the main surface Sb.

  As shown in FIGS. 3 and 4, the first mask Ma and the second mask Mb are configured 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. Also, 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 the area of the first mask Ma.

  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 above range, and may be appropriately set according to the dimension of the original glass plate G1.

  The first mask Ma is located in the plane of the first flat surface Fa, and more specifically, located so as to be concentric with the first flat surface Fa. Similarly, the second mask Mb is located in the plane of the second flat surface Fb, and located so as to be concentric with the second flat surface Fb. In FIGS. 3 and 4, in order to emphasize the first mask Ma and the second mask Mb, these are hatched.

As a material of the first mask Ma and the second mask Mb, any material may be used as long as the permeation of ions to be ion-exchanged can be suppressed or blocked. When the ion to be exchanged is an alkali metal ion, the first mask Ma and the second mask Mb are, for example, metal oxide, metal nitride, metal carbide, metal oxynitride, metal oxycarbide, metal carbonitride film And the like. Further, carbon materials, metals and alloys excellent in heat resistance and chemical durability can also be used as the first mask Ma and the second mask Mb. More specifically, the material of the first mask Ma and the second mask Mb is, for example, SiO ₂ , Al ₂ O ₃ , SiN, SiC, Al ₂ O ₃ , AlN, ZrO ₂ , TiO ₂ , Ta ₂ O ₅ A film containing one or more of Nb ₂ O ₅ , HfO ₂ , SnO ₂ , carbon nanotubes, graphin, diamond like carbon, and stainless steel can be used.

In particular, if SiO ₂ is used as the 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 they can also function as an antireflective film. . The first mask Ma and the second mask Mb may be films made only of SiO ₂ . Specifically, the first mask Ma and the second mask Mb may have a composition containing 99% or more of SiO ₂ in mass%.

Further, in order to reliably block the permeation of ions, it is preferable to use an inorganic film layer mainly composed of SiO ₂ and containing Al ₂ O ₃ as the first mask Ma and the second mask Mb. In this case, the first mask Ma and the second mask Mb are, by mass%, SiO _{2 20 to} 99%, Al ₂ O ₃ 1 to 80%, more preferably SiO ₂ 60 to 99%, Al ₂ O ₃ 1 to The composition contains 40%.

  The thickness of the first mask Ma and the second mask Mb may be any thickness as long as blocking and suppression of ion permeation are possible. However, if the thicknesses of the first mask Ma and the second mask Mb are excessive, the film formation time, material cost, and the like increase, so it is preferable to form the first mask Ma and the second mask Mb as thin as possible. Specifically, the film thickness of the first mask Ma and the second mask Mb is, for example, preferably 1 to 5000 nm, and more preferably 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.

  The film formation method of the first mask Ma and the second mask Mb is a PVD method (physical vapor deposition method) such as a sputtering method or a vacuum evaporation method, a CVD method (chemical vapor deposition method such as a thermal CVD method or a plasma CVD method) Wet coating methods such as dip coating method and slit coating method can be used. Sputtering and dip coating are particularly preferred. When the sputtering method is used, the first mask Ma and the second mask Mb can be easily formed uniformly. The film formation locations of the first mask Ma and the second mask Mb may be set by any method. Alternatively, the first mask Ma and the second mask Mb, which are formed in advance in a sheet shape, may be bonded to the main surfaces Sa and Sb of the original glass plate G1 to form a film.

In the present embodiment, an example in which the first mask Ma and the second mask Mb, which contain SiO ₂ and Al ₂ O _3, have a thickness of 100 nm or more, and can block the transmission of alkali metal ions, is formed. Explain as.

  Next, after the mask process, the process of the selective ion exchange process shown in FIG. 1C is performed. The selective ion exchange step is a step of chemically strengthening the membrane-coated glass plate G2 by an ion exchange method to obtain a membrane-reinforced glass sheet G3. Specifically, the film-coated glass plate G2 is immersed in the molten salt T1 containing an alkali metal ion for ion exchange. The molten salt T1 in the present embodiment is, for example, a potassium nitrate molten salt. The molten salt T1 preferably has a pH of 6.5 to 11 when it is mixed with water to form a 20% by mass aqueous solution.

  In this selective ion exchange step, a portion of each of the main surfaces Sa and Sb covered by the masks Ma and Mb is a non-selection region, and a portion exposed without being covered by the masks Ma and Mb is a selection region. Specifically, the non-selected region is the central portion Fa1 of the first flat surface Fa and the central portion Fb1 of the second flat surface Fb. The selected region is the peripheral portion Fa2 of the first flat surface Fa, the peripheral portion Fb2 of the second flat surface Fb, the first chamfered surface Ca, the second chamfered surface Cb, and the end surface E.

  The temperature of the molten salt T1 in the selective ion exchange step may be arbitrarily determined, but is, 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. The time for immersing the film-coated glass plate G2 in the molten salt T1 may be arbitrarily determined, but for example, 0.1 to 150 hours, preferably 0.3 to 100 hours, more preferably 0.5 to 50 It's time.

  In the selective ion exchange step, sodium ions in the glass plate and potassium ions in the molten salt T1 are selected in the selected region where the first mask Ma and the second mask Mb are not provided on the surface of the film-coated glass plate G2. Will be exchanged. Thereby, the first compressive stress layer CP1 is formed in the selected region. On the other hand, in the central portions Fa1 and Fb1 provided with the first mask Ma and the second mask Mb in the surface of the film-coated glass plate G2, ions are blocked, and thus no compressive stress layer is formed. By the above selective ion exchange process, a film-reinforced glass sheet G3 having the first compressive stress layer CP1 formed in the selected region is obtained.

  Then, after the selective ion exchange step, the process of the mask removal step shown in FIG. 1D is performed. The mask removing step is a step of removing the masks Ma and Mb from the film-coated tempered glass plate G3. Specifically, the masks Ma and Mb are removed by polishing. A well-known polisher can be used as a polisher, It is preferable to use especially a double-sided polisher.

Note that the masks Ma and Mb may be removed using another method other than polishing. For example, the etching solution may be attached to remove the masks Ma and Mb. When each mask Ma and Mb is a film containing SiO ₂ , for example, a solution containing fluorine, TMAH, EDP, KOH, NAOH and the like can be used as an etching solution, and in particular, a hydrofluoric acid solution is used as an etching solution Is preferred. When only the masks Ma and Mb are removed using a hydrofluoric acid solution without changing the glass dimensions, the concentration of HF in the hydrofluoric acid solution is preferably 10% or less.

  When the masks Ma and Mb are removed by the process of the mask removal step, the compression stress layer is not formed on the central portions Fa1 and Fb1 of the flat surfaces Fa and Fb, and the peripheral portions of the flat surfaces Fa and Fb A tempered glass sheet G4 is obtained in which a first compressive stress layer CP1 is formed on Fa2, Fb2, chamfered surfaces Ca and Cb, and an end surface E (see FIG. 1D).

  Next, in order to strengthen the tempered glass sheet G4 as a whole, the process of the entire tempering step is performed. The whole strengthening step is a step of bringing the molten salt T2 into contact with the entire surface of the strengthened glass sheet G4 to exchange ions in the surface layer, as shown in FIG. 1E. Specifically, the strengthened glass plate G4 is immersed in the molten salt T2 containing alkali metal ions for ion exchange, and the second compressive stress layer CP2 is formed at each of the central portions Fa1 and Fb1 of the flat surfaces Fa and Fb. Furthermore, ion exchange is performed also in the first compressive stress layer CP1, and the depth thereof is increased. The molten salt T2 is, for example, a potassium nitrate molten salt.

  The temperature of the molten salt T2 in the overall strengthening step may be arbitrarily determined, but is, for example, 350 to 500 ° C, preferably 370 to 480 ° C, and more preferably 380 to 450 ° C. The time for which the tempered glass sheet G4 is immersed in the molten salt T2 may be arbitrarily determined, but for example, 0.1 to 72 hours, preferably 0.3 to 50 hours, more preferably 0.5 to 24 hours It is.

  The molten salt T2 may be similar to the above-described molten salt T1. That is, the tempered glass plate G4 may be dipped again in the molten salt T1 used in the selective strengthening step. In this case, since processing of a plurality of steps can be performed in a single salt bath, the cost of manufacturing facilities can be suppressed.

  Also, the molten salt T2 may be different from the molten salt T1, and the treatment temperature and treatment time in the overall strengthening step may be different from the treatment temperature and treatment time in the selective ion exchange step. For example, the treatment time of ion exchange in the overall strengthening step is preferably shorter than the treatment time in the selective ion exchange step. According to such processing, it is possible to suppress an increase in tensile stress without the depth of the second compressive stress layer CP2 in the central portions Fa1 and Fb1 of the flat surfaces Fa and Fb becoming excessive.

  By the above-described overall strengthening process, the first compressive stress layer CP1 having a large layer depth (DOL1) is formed at the end portions in the radial direction (the peripheral portions Fa2 and Fb2, the chamfered surfaces Ca and Cb, and the end face E) A strengthened glass sheet G5 is obtained in which 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 main surface Sa, Sb of the strengthened glass sheet G5 so as to correspond to the area of the first mask Ma and the second mask Mb. That is, the formation area of the second compressive stress layer CP2 on the second flat surface Fb of the strengthened glass sheet G5 is larger than the formation area of the second compressive stress layer CP2 on the first flat surface Fa. The layer depth (DOL1) of the first compressive stress layer CP1 is preferably set to 1/4 or less of the thickness of the strengthened glass sheet 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 sheet G5.

  As described above, in the method of manufacturing the strengthened glass sheet G5 according to the present embodiment, the first mask Ma and the second mask having different areas with respect to the original glass sheet G1 having an asymmetric shape in the thickness direction By forming the two masks Mb on the respective main surfaces Sa and Sb, it is possible to minimize the deformation of the glass plate (glass plate with film G2) in the case of strengthening by the ion exchange method. Specifically, in the case of the original glass plate G1 in which the area of the first flat surface Fa is small and the area of the second flat surface Fb is large, the first mask Ma having a small area is used as the first flat surface Fa. It is desirable to form the film-coated glass plate G2 by forming the second mask Mb having a large area on the second flat surface Fb. This makes it possible to stably manufacture a tempered glass sheet G5 having high flatness and partially high strength.

  In the case of the present embodiment, since the area of the first flat surface Fa and the second flat surface Fb is larger than the chamfered surfaces Ca and Cb, the original glass plate G1 is formed on the chamfered surfaces Ca and Cb during ion exchange. The effect of the compressive stress layer on the deformation of the film-coated glass sheet G2 is considered to be extremely small compared to that of the compressive stress layer formed on the first flat surface Fa and the second flat surface Fb. Therefore, in the present embodiment, the first mask Ma and the second mask Mb having different areas are formed on 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. The deformation of the film-coated glass plate G2 can be prevented only by the above.

  Further, ion exchange is performed by immersing the tempered glass plate G4 formed by removing the masks Ma and Mb in the molten salt T2 also in the overall strengthening step, but the selected region is strengthened in the selective strengthening step. Thus, the deformation of the tempered glass sheet G4 in the overall tempering process is extremely minor.

  The above matters can be applied not only to the case of forming the disk-shaped strengthened glass plate G5 having the chamfered surfaces Ca and Cb, but also to the case of manufacturing the strengthened glass plate G5 of various shapes. FIG. 5 shows an example of the original glass sheet G1 and the film-coated glass sheet G2 in the case of producing a strengthened glass sheet G5 not having the chamfered surfaces Ca and Cb.

  As shown to FIG. 5A, as for the original glass board G1, the thickness of the edge part of radial direction is comprised more largely than the thickness of the middle part. This end portion is configured in a substantially circular shape in a cross sectional view, and the diameter thereof is configured to be larger than the thickness of the middle portion of the original glass plate G1. With this configuration, the original glass plate G1 has a convex curved surface CS connected to the first flat surface Fa on the first main surface Sa. Further, the first mask Ma of the film-coated glass plate G2 is formed 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. Further, in the original glass plate G1 shown in FIG. 5B, the inclined surface IS is formed so as to be connected to the first flat surface Fa of the first main surface Sa. Also in this example, the first mask Ma in the film-coated glass plate G2 is formed not only on the first flat surface Fa but also on part of the inclined surface IS.

  In addition, you may implement the process of a finishing process further after a whole reinforcement | strengthening process. According to the manufacturing method of tempered glass board G5 concerning this embodiment, in the selective ion exchange process of a selective strengthening process, not only the modification of tempered glass board with a film G3 is prevented, but also the first mask Ma and the second mask Mb It is also possible to adjust the amount of deformation of the film-reinforced glass sheet G3 by adjusting the size relationship of the area with the above. For this reason, it is also possible to make the tempered glass board G5 which passes through a whole strengthening process into the state which slightly deformed, and to give a finishing process to this.

  Hereinafter, this finishing process will be described with reference to the case where the tempered glass sheet G5 is polished by the double-side polishing apparatus PA. As shown in FIG. 6, the double-side polishing apparatus PA includes a carrier CA for holding a strengthened glass plate G5, an upper polishing plate SP1 for polishing a first main surface Sa of the strengthened glass plate G5, and a second main surface Sb. And a lower polishing plate SP2 for polishing. Carrier CA has holding holes CAh for holding tempered glass sheet G5 in a non-rotatable manner.

  As shown in FIG. 6, when the first flat surface Fa is on the upper side and the second flat surface Fb is on the lower side, as shown in FIG. It is fitted in holding hole CAh. In this state, the upper polishing plate SP1 is brought into contact with the first main surface Sa, and the lower polishing plate SP2 is brought into contact with the second main surface Sb. Thereafter, the upper polishing plate SP1, the lower polishing plate SP2 and the carrier CA are moved relatively to polish both surfaces Sa and Sb of the strengthened glass plate G5.

  As described above, by performing double-sided polishing while leaving a slight deformation to the strengthened glass sheet G5, it is possible to obtain a good polished surface for each of the main surfaces Sa and Sb. For example, when the same double-sided polishing is performed in a state in which the strengthened glass sheet G5 is not deformed, the second main surface Sb located below is more excessive than the first main surface Sa from the positional relationship between the upper and lower The upper first main surface Sa and the lower second main surface Sb may have uneven polishing amounts. On the other hand, since the polishing amounts of the main surfaces Sa and Sb can be made uniform by performing the polishing as described above, double-sided polishing with high accuracy becomes possible.

  FIG. 7 shows a second embodiment of the method for producing a strengthened glass sheet. In the first embodiment described above, the glass plates (the film-coated glass plate G2 and the tempered glass plate G4) are dipped twice in the molten salt T1 and T2 in the selective strengthening step and the entire strengthening step, but in the present embodiment A tempered glass sheet G5 is manufactured by one immersion.

  In this embodiment, as shown to FIG. 7A, after preparing the original glass board G1, as shown to FIG. 7B, 1st mask Ma and the 2nd mask Mb are formed in each main surface Sa and Sb, and a film | membrane The attached glass plate G2 is obtained. Unlike the first embodiment, in the present embodiment, a functional film that suppresses ion permeation is used for the first mask Ma and the second mask Mb.

  Thereafter, as shown in FIG. 7C, the film-coated glass plate G2 having the masks Ma and Mb is immersed in the molten salt T1. Thus, ion exchange is performed on the peripheral portions Fa2 and Fb2 of the flat surfaces Fa and Fb, the chamfered surfaces Ca and Cb, and the end surface E which are not covered by the masks Ma and Mb, and the masks Ma and Mb are used. Also in the central parts Fa1 and Fb1 which are covered, ion exchange is performed in a state in which ion permeation is suppressed. As a result, the first compressive stress layer CP1 having a large layer depth (DOL1) is formed at the end portions in the radial direction (the peripheral portions Fa2 and Fb2, the chamfered surfaces Ca and Cb, and the end face E). A film-reinforced glass sheet G3 is obtained in which a second compressive stress layer CP2 having a small layer depth (DOL2) is formed in the central portions Fa1 and Fb1 of the flat surfaces Fa and Fb, respectively (see FIG. 7C). Thereafter, the first mask Ma and the second mask Mb in the film-coated tempered glass sheet G4 are removed to obtain a tempered glass sheet G5 shown in FIG. 7D.

  In addition, this invention is not limited to the structure of the said embodiment, It is not limited to the effect mentioned above. The present invention can be variously modified without departing from the scope of the present invention.

Although the above-mentioned embodiment illustrated the case of carrying out chemical exchange by ion exchange of sodium ion and potassium ion, it is possible to exchange not only this but arbitrary ion. For example, the strengthened glass plates G4 and G5 may be manufactured by ion exchange of lithium ion and sodium ion, or ion exchange of lithium ion and potassium ion. In this case, the tempered glass plates G4 and G5 desirably contain 0.5 to 7.5% by weight of LiO ₂ as a composition, and more preferably 3.0% or 4.5% of LiO ₂ contains.

  The stress characteristics of the tempered glass sheet can be measured, for example, using FSM-6000 manufactured by Orihara Mfg. When the depth of the compressive stress layer of the aluminosilicate glass exceeds 100 μm, or when ion exchange of lithium ion and sodium ion or ion exchange of lithium ion and potassium ion is performed, the stress characteristics of the tempered glass plate are For example, it can measure using Orihara Mfg. SLP-1000. In the case where a cross-sectional sample can be produced by cutting a tempered glass plate or the like, for example, the internal stress distribution may be observed using a photonic lattice WPA-micro or Tokyo Instruments Abrio to confirm the stress depth. desirable.

  The inventors set a reinforced sheet glass when manufactured using the present manufacturing method as an example, and a reinforced sheet glass when manufactured without applying the present manufacturing method (without forming a mask on the original glass sheet). As a comparative example, the magnitude | size of the curvature (vertical direction displacement) in each case was calculated | required by calculation (simulation). Each tempered glass board in an Example and a comparative example is a disk which has a cross-sectional shape asymmetrical in the thickness direction. The dimension of the tempered glass board which concerns on an Example and a comparative example is 1 mm in thickness, and 40 mm in outer diameter. Moreover, the diameter of the 1st mask used for the Example was 30 mm, and the diameter of the 2nd mask was 36 mm.

  As a result of the calculation, it was found that the warpage of the comparative example was 23.7 μm while the warpage of the example was 0.0 μm. FIG. 8 shows the result of this operation visualized in grayscale. FIG. 8A shows an example, and FIG. 8B shows a comparative example. As shown in FIGS. 8A and 8B, in the tempered glass plate according to the comparative example, the amount of warpage (vertical displacement) increases as going radially outward, whereas in the tempered glass plate according to the example, the warpage occurs. It can be seen that no The tempered glass sheet according to the embodiment shown in FIG. 8A is displayed with its edge bordered by a solid line. This solid line is given to clarify the boundary of the tempered glass sheet, and is not related to the warpage of the tempered glass sheet.

Ca first chamfered surface Cb second chamfered surface Fa first flat surface Fb second flat surface G1 original glass plate G2 glass plate with film G3 tempered glass plate with film G4 tempered glass plate G5 tempered glass plate Ma first mask Mb second Mask Sa First major surface Sb Second major surface T1 Molten salt T2 Molten salt

Claims (11)

A method for producing a strengthened glass sheet, which exchanges ions of the surface layer of a glass sheet having a first main surface and a second main surface on the front and back sides and having a cross-sectional shape asymmetric in the thickness direction,
A mask provided with a first mask for suppressing or preventing the exchange of ions on at least a part of the first main surface, and a second mask for suppressing or preventing the exchange of ions on at least a part of the second main surface Process,
An ion exchange step of immersing the glass plate in a molten salt for exchanging the ions after the mask step;
In the mask 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 are set to different sizes according to the cross-sectional shape. A method for producing a tempered glass sheet, characterized by The first major 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 provided in the first flat surface,
The second mask is provided in the second flat surface,
The method according to claim 1, wherein a formation area of the second mask is larger than a formation area of the first mask. The first flat surface is located at a central portion of the first major surface,
The first mask is provided at the center of the first flat surface,
The second flat surface is located at the center of the second main surface,
The second mask is provided at a central portion of the second flat surface,
The first main surface includes a first chamfered surface provided along the outer edge of the first flat surface,
The second main surface includes a second chamfered surface provided along the outer edge of the second flat surface,
The method for producing a tempered glass sheet according to claim 2, wherein the area of the first chamfered surface is larger than the area of the second chamfered surface. 4. The inorganic film according to claim 1, wherein the first mask and the second mask are inorganic film layers containing 60 to 100% of SiO _{2 and} 0 to 40% of Al ₂ O _{3 by} mass% as a composition. The manufacturing method of the tempered glass board as described in any one.   The thickness of the said 2nd mask with respect to the thickness of the said 1st mask is 0.8 to 1.2 times, The manufacturing method of the tempered glass board as described in any one of Claim 1 to 4 characterized by the above-mentioned. The ions on the surface of the glass plate are sodium ions,
The molten salt contains potassium ion,
The reinforced salt according to any one of claims 1 to 5, wherein the molten salt has a pH of 6.5 to 11 when mixed with water to form a 20% by mass aqueous solution. Method of manufacturing glass plate. The glass plate is in mass% as a glass plate _{composition, SiO 2 45~75%, Al 2} O 3 1~30%, Na 2 O 1~20%, a glass plate containing K ₂ O 0 to 20% The manufacturing method of the tempered glass board as described in any one of the Claims 1 to 6 characterized by being.   The said glass plate is planar view disk shape or rectangular shape, The manufacturing method of the tempered glass board as described in any one of Claim 1 to 7 characterized by the above-mentioned. A film-coated glass plate having a first main surface and a second main surface on the front and back sides and having a cross-sectional shape asymmetric in the thickness direction,
A first mask that is formed on at least a portion of the first main surface and that suppresses or prevents ion exchange, and is formed on at least a portion of the second main surface, and suppresses or prevents ion exchange And a second mask to
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 are set to different sizes according to the cross-sectional shape, Glass plate attached. The first major 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 provided in the first flat surface,
The second mask is provided in the second flat surface,
The film forming glass plate according to claim 9, wherein a formation area of the second mask is larger than a formation area of the first mask. It is a tempered glass board which has a first main surface and a second main surface on the front and back and has a cross-sectional shape asymmetric in the thickness direction,
The first major surface has a first 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 in the peripheral portion, and a second compressive stress layer formed in the central portion and having a layer depth smaller than that of the first compressive stress layer. And
The second flat surface has a first compressive stress layer formed at the periphery thereof, and a second compressive stress layer formed at the central portion thereof and having a layer depth smaller than that of the first compressive stress layer. And
The formation area of the said 2nd compression stress layer in the said 2nd flat surface is larger than the formation area of the said 2nd compression stress layer in the said 1st flat surface, The tempered glass board characterized by the above-mentioned.