Glass, display device, and method for producing glass

Abstract

A glass 10 according to the present invention has sufficient bending properties and breakage resistance and attains a reduction in the number of broken pieces. The glass 10 includes a thick portion 20 having a thickness t2 of 0.5 mm or larger and a thin portion 30 adjoining to the thick portion 20 and having a thickness of 0.15 mm or larger but less than 0.5 mm. A first main surface 20A of the thick portion 20 and a first main surface 30A of the thin portion 30 are flush with each other in the state in which a first main surface 10A of the glass 10 is fixed in contact with a flat surface. The thin portion 30 has an internal tensile stress CT which is higher than the internal tensile stress CT of the thick portion 20. A compressive stress layer of the thin portion 30 has a DOL which is less than the DOL of a compressive stress layer of the thick portion 20. The thin portion 30 has a surface compressive stress CS of 550 MPa or greater.

Description

Glass, display device, and glass manufacturing method

[0001] The present invention relates to glass, a display device, and a method for manufacturing glass.

[0002] A cover glass may be disposed to protect an object such as a display. For example, Patent Document 1 describes a cover member having recesses on both main surfaces, one of which is curved.

[0003] International Publication No. 2018 / 116981

[0004] Here, glass used for cover members and the like is required to have sufficient bendability and breakage resistance, and, even if it does break, to reduce the number of shatters (number of fragments).

[0005] An object of the present invention is to provide glass, a display device, and a method for manufacturing glass that have sufficient bendability and breakage resistance while reducing the number of breakages.

[0006] The glass according to the present disclosure is glass having a thick portion having a thickness of 0.5 mm or more, and a thin portion adjacent to the thick portion and having a thickness of 0.15 mm or more and less than 0.5 mm, wherein a first main surface of the thick portion and a first main surface of the thin portion are flush with each other when the first main surface of the glass is fixed so that it is in contact with a flat surface, the internal tensile stress CT of the thin portion is higher than the internal tensile stress CT of the thick portion, the DOL of the compressive stress layer of the thin portion is smaller than the DOL of the compressive stress layer of the thick portion, and the surface compressive stress CS of the thin portion is 550 MPa or more.

[0007] A display device according to the present disclosure includes a display and the glass.

[0008] The method for manufacturing glass according to the present disclosure includes preparing glass having a thick portion having a thickness of 0.5 mm or more and a thin portion adjacent to the thick portion and having a thickness of 0.15 mm or more and less than 0.5 mm, wherein a first main surface of the thick portion and a first main surface of the thin portion are flush with each other when the first main surface of the glass is fixed so that the first main surface of the glass is in contact with a flat surface; and chemically strengthening the glass such that the time for chemically strengthening the thick portion is longer than the time for chemically strengthening the thin portion, thereby manufacturing glass in which the DOL of the compressive stress layer in the thin portion is smaller than the DOL of the compressive stress layer in the thick portion, the internal tensile stress CT of the thin portion is higher than the internal tensile stress CT of the thick portion, and the surface compressive stress CS of the thin portion is 550 MPa or more.

[0009] According to the present invention, it is possible to reduce the number of breakages while maintaining sufficient bendability and breakage resistance.

[0010] FIG. 1 is a cross-sectional view of a display device according to the present embodiment. FIG. 2 is a schematic cross-sectional view of glass according to the present embodiment. FIG. 3 is a schematic cross-sectional view of glass according to the present embodiment. FIG. 4 is a schematic top view of glass according to the present embodiment. FIG. 5 is a flowchart illustrating a method for manufacturing glass according to the present embodiment. FIG. 6 is a schematic cross-sectional view of glass according to another example of the present embodiment. FIG. 7 is a schematic cross-sectional view of glass according to another example of the present embodiment. FIG. 8 is a schematic cross-sectional view of glass according to another example of the present embodiment. FIG. 9 is a schematic cross-sectional view of glass according to another example of the present embodiment. FIG. 10 is a schematic view illustrating a method for evaluating bendability. FIG. 11 is a schematic view showing an evaluation of warpage.

[0011] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Note that the present invention is not limited to these embodiments, and when there are multiple embodiments, the present invention also includes configurations that are made by combining the respective embodiments. Furthermore, numerical values ​​include the range of rounding.

[0012] (Display Device) The display device according to this embodiment includes a display and the glass according to this embodiment. FIG. 1 is a cross-sectional view of the display device according to this embodiment. The display device 1 according to this embodiment is a display device provided in a vehicle. The display device 1 includes a glass 10, a display 12, and a base 14 that supports the display 12. The glass 10 has a first main surface 10A that is one main surface and a second main surface 10B that is the other main surface, and will be described in detail below. The glass 10 is used as a cover member that protects the display 12. The glass 10 is attached to the display 12 so that the second main surface 10B faces the display surface of the display 12. The second main surface 10B of the glass 10 may be bonded to the display 12 via an OCA (Optical Clear Adhesive) or an OCR (Optical Clear Resin), not shown. The display 12 is a panel that displays images and may be, for example, a liquid crystal panel, an organic EL panel, a PDP, an electronic ink panel, or the like, or may have a touch panel, etc. In the example of Fig. 1, multiple displays 12 are provided, each with its display surface facing in a different direction. The glass 10, in a folded state, covers the display surface of each display 12.

[0013] However, the configuration in FIG. 1 is an example, and the display device 1 to which the glass 10 is applied may have any configuration. For example, the number of displays 12 in the display device 1 is not limited to two and may be any number. The display 12 may be deformable. A deformable display may be a so-called rollable display, the shape of the screen of which can be changed by rolling up and unrolling. The display 12 may also be a movable display, part or all of which is folded and unfolded by a mechanism provided in the display device 1. The display device 1 is not limited to being provided in a vehicle, and may be used for any purpose. The glass 10 is not limited to being used as a cover member for the surface of the display device 1, and may be used for any purpose.

[0014] The glass according to this embodiment is glass having a thick portion having a thickness of 0.5 mm or more, and a thin portion adjacent to the thick portion and having a thickness of 0.15 mm or more and less than 0.5 mm, wherein a first main surface of the thick portion and a first main surface of the thin portion are flush with each other when the first main surface of the glass is fixed so that it is in contact with a flat surface, the internal tensile stress CT of the thin portion is higher than the internal tensile stress CT of the thick portion, the DOL of the compressive stress layer of the thin portion is smaller than the DOL of the compressive stress layer of the thick portion, and the surface compressive stress CS of the thin portion is 550 MPa or more.

[0015] (Glass) FIG. 2 is a schematic cross-sectional view of the glass according to this embodiment. FIG. 2 shows the glass 10 in a bent state. As shown in FIG. 2, the glass 10 has a thick portion 20 and a thin portion 30 that is thinner than the thick portion 20. The glass 10 is bent at the thin portion 30. In this embodiment, as shown in FIG. 2, the glass 10 is bent so that the second main surface 10B is concave. However, this is not limited thereto, and the glass 10 may be bent so that the second main surface 10B is convex. Furthermore, when the glass 10 is mounted on a display device 1, the first main surface 10A is the side exposed to the outside, and the second main surface 10B is the side facing the display 12.

[0016] FIG. 3 is a schematic cross-sectional view of the glass according to this embodiment, and FIG. 4 is a schematic top view of the glass according to this embodiment. FIGS. 3 and 4 show the glass 10 when fixed in contact with a flat surface. The first main surface 10A of the glass 10 is preferably flat when the first main surface 10A is fixed in contact with the flat surface. Here, the state in which the first main surface 10A is fixed in contact with the flat surface refers to a state in which substantially the entire area of ​​the first main surface 10A is in contact with the flat surface due to its own weight alone, so that the first main surface 10A conforms to the flat surface. This can also be described as a state in which the first main surface 10A is not subjected to an external load and is not elastically deformed by an external load. Note that substantially the entire area of ​​the first main surface 10A may refer to the entire area of ​​the first main surface 10A, but is not limited thereto and may refer to, for example, a region of 95% or more of the entire area of ​​the first main surface 10A. In the following description, unless otherwise specified, the glass 10 refers to a glass plate in a state where the first main surface 10A is fixed in contact with a flat surface. Furthermore, the direction connecting the first main surface 10A and the second main surface 10B when the first main surface 10A is in contact with the flat surface (the direction perpendicular to the flat surface), i.e., the thickness direction of the glass 10, is referred to as the Z direction. The direction perpendicular to the Z direction is referred to as the X direction, and the direction perpendicular to the Z direction and the X direction is referred to as the Y direction. Furthermore, among the directions parallel to the Z direction, one direction from the first main surface 10A toward the second main surface 10B is referred to as direction Z1, and the other direction is referred to as direction Z2. Furthermore, among the directions parallel to the X direction, one direction (toward the right in the example of FIG. 3 ) is referred to as X1, and the other direction is referred to as direction X2. Similarly, among the directions parallel to the Y direction, one direction (toward the depth of the paper in the example of FIG. 3 ) is referred to as Y1, and the other direction is referred to as Y2.

[0017] In this embodiment, the glass plate 10 has a rectangular shape when viewed from the Z1 direction, as shown in Fig. 4. However, the shape of the glass plate 10 is not limited to a rectangular shape when viewed from the Z1 direction, and may have any shape.

[0018] As shown in FIG. 3 , the glass 10 has a thick portion 20 and a thin portion 30 that is thinner than the thick portion 20. Here, the "thickness" refers to the length of the thick portion 20 or the thin portion 30 in the Z direction. The thick portion 20 and the thin portion 30 are aligned in the X direction, and in this embodiment, the thin portion 30 is provided on the X2 side of the thick portion 20. The thin portion 30 is a recess formed by recessing the second main surface 10B of the glass 10. That is, if the main surface of the thick portion 20 facing the second main surface 10B is defined as the second main surface 20B and the main surface of the thin portion 30 facing the second main surface 10B is defined as the second main surface 30B, the thick portion 20 refers to the portion of the glass 10 where the second main surface 20B is flush with the second main surface 10B of the glass 10. The thin portion 30 refers to the portion of the glass 10 where the second main surface 30B is located on the first main surface 10A side relative to the second main surface 10B of the glass 10 (i.e., the second main surface 20B of the thick portion 20).

[0019] The main surface of the thick portion 20 on the first main surface 10A side is referred to as the first main surface 20A, and the main surface of the thin portion 30 on the first main surface 10A side is referred to as the first main surface 30A. The first main surface 20A is the region of the entire first main surface 10A of the glass 10 where the thick portion 20 is formed, and the first main surface 30A is the region of the entire first main surface 10A of the glass 10 where the thin portion 30 is formed. The first main surface 20A and the first main surface 30A are flush with each other. "Flush" refers to a smooth connection without any steps. For example, the first main surface 20A and the first main surface 30A may be considered flush with each other if the flatness of the entire first main surface 10A is 0.05 mm or less. Note that flatness complies with the definition in JIS B 0621, "Definition and Display of Geometric Deviation," and can be measured, for example, using a three-dimensional measuring device using a contact probe or laser probe. Similarly, the position of each position in the Z direction relative to the reference point can be measured by a three-dimensional measuring device using a contact probe or a laser probe.

[0020] As shown in Figure 4, the thin-walled portion 30 extends in the Y direction. The thin-walled portion 30 is formed from one end of the glass 10 to the other end in the Y direction. In Figure 4, the glass 10 can be bent with the Y direction as its axis. However, the shape of the thin-walled portion 30 is not limited to this. For example, the thin-walled portion 30 may extend in a direction inclined with respect to the Y direction, or the extending direction may be curved rather than linear. Furthermore, the thin-walled portion 30 may be provided in a portion of the section from one end of the glass 10 to the other end in the Y direction.

[0021] (Thickness) The thickness t2 of the thick portion 20 is 0.5 mm or more, preferably 0.5 mm or more but less than 5.0 mm, and more preferably 1.0 mm or more and 3.0 mm or less. Having the thickness t2 in this range ensures breakage resistance. The thickness t2 refers to the length in the Z direction from the first main surface 20A to the second main surface 20B of the thick portion 20.

[0022] The thickness t3 of the thin-walled portion 30 is 0.15 mm or more and less than 0.5 mm, preferably 0.20 mm or more and 0.45 mm or less, and more preferably 0.25 mm or more and 0.40 mm or less. By setting the thickness t3 within this range, bendability and breakage resistance can be ensured. Note that the thickness t3 refers to the length in the Z direction from the first main surface 30A to the second main surface 30B of the thin-walled portion 30.

[0023] The ratio (t3 / t2) of the thickness t3 of the thin-walled portion 30 to the thickness t2 of the thick-walled portion 20 is preferably 5% to 60%, more preferably 10% to 50%, and even more preferably 15% to 40%. By keeping the thickness ratio within this range, bendability and breakage resistance can be ensured.

[0024] (Compressive Stress Layer) The glass 10 has compressive stress layers formed on the first main surface 10A side and the second main surface 10B side. That is, the thick portion 20 has compressive stress layers 22 formed on the first main surface 20A side and the second main surface 20B side. Similarly, the thin portion 30 has compressive stress layers 32 formed on the first main surface 30A side and the second main surface 30B side. The compressive stress layers 22, 32 are formed by subjecting the glass 10 to a chemical strengthening treatment.

[0025] (Surface compressive stress CS) The surface compressive stress CS of the thick portion 20 is preferably 550 MPa or more, more preferably 650 MPa or more and 1300 MPa or less, and even more preferably 750 MPa or more and 1200 MPa or less. When the surface compressive stress CS of the thick portion 20 is in this range, breakage resistance can be ensured. The method for measuring the surface compressive stress CS is arbitrary, but it may be measured, for example, using a photoelastic analysis method. In this embodiment, the surface compressive stress CS may be measured, for example, using an FSM-6000LE, a surface stress meter manufactured by Orihara Seisakusho.

[0026] The surface compressive stress CS of the thin-walled portion 30 is 550 MPa or more, preferably 650 MPa or more and 1300 MPa or less, and more preferably 750 MPa or more and 1200 MPa or less. When the surface compressive stress CS of the thin-walled portion 30 is in this range, breakage resistance can be ensured.

[0027] The difference between the surface compressive stress CS of the thin-walled portion 30 and the surface compressive stress CS of the thick-walled portion 20 is preferably 100 MPa or less, more preferably 70 MPa or less, and even more preferably 50 MPa or less. By reducing the difference in surface compressive stress CS in this manner, the number of chemical strengthening steps can be reduced, shortening the steps and further reducing costs.

[0028] The surface compressive stress CS of the thick portion 20 described above is the surface compressive stress of the first main surface 20A of the thick portion 20 (the surface compressive stress of the compressive stress layer 22 on the first main surface 20A side). However, the surface compressive stress of the second main surface 20B of the thick portion 20 (the surface compressive stress of the compressive stress layer 22 on the second main surface 20B side) may also be similar to the above description. Similarly, the surface compressive stress CS of the thin portion 30 described above is the surface compressive stress of the first main surface 30A of the thin portion 30 (the surface compressive stress of the compressive stress layer 32 on the first main surface 30A side). However, the surface compressive stress of the second main surface 30B of the thin portion 30 (the surface compressive stress of the compressive stress layer 32 on the second main surface 30B side) may also be similar to the above description. However, the difference between the surface compressive stress CS on the first main surface 30A side of the thin-walled portion 30 and the surface compressive stress CS on the second main surface 30B side of the thin-walled portion 30 is preferably 50 MPa or less, more preferably 30 MPa or less, and even more preferably 10 MPa or less. By making the difference in surface compressive stress CS small in this manner, warpage can be more suitably suppressed.

[0029] Furthermore, the surface compressive stress CS of the thick portion 20 described above may refer to the measured value of the surface compressive stress CS at the center position of the thick portion 20 in the X direction (the direction in which the thick portion 20 and the thin portion 30 are adjacent to each other). Similarly, the surface compressive stress CS of the thin portion 30 described above may refer to the measured value of the surface compressive stress CS at the center position of the thin portion 30 in the X direction. That is, the surface compressive stress CS of the thick portion 20 does not have to be the value described above throughout the entire area, as long as the effects of the invention are achieved. For example, the surface compressive stress CS of the thick portion 20 in a region near the thin portion 30 (e.g., a region within 15 mm in the X1 direction from the boundary between the thick portion 20 and the thin portion 30) may be the same value as the surface compressive stress CS of the thin portion 30. Similarly, the surface compressive stress CS of the thin portion 30 does not have to be the value described above throughout the entire area. For example, the surface compressive stress CS in the region of the thin-walled portion 30 near the thick-walled portion 20 (for example, the region within 15 mm in the X2 direction from the boundary position between the thick-walled portion 20 and the thin-walled portion 30) may be the same value as the surface compressive stress CS of the thick-walled portion 20.

[0030] (DOL of Compressive Stress Layer) The DOL of the compressive stress layer 32 of the thin portion 30 is smaller than the DOL of the compressive stress layer 22 of the thick portion 20. While appropriately ensuring the breakage resistance of the thick portion 20, the DOL of the thin portion 30 is smaller than the DOL of the thick portion 20, thereby appropriately ensuring the bendability starting from the thin portion 30, and even if breakage occurs, the number of fractures (number of fragments) can be reduced. Any method for measuring the DOL may be used, but for example, it may be measured using a photoelastic analysis method. In this embodiment, the DOL may be measured using, for example, an FSM-6000LE, a surface stress meter manufactured by Orihara Seisakusho.

[0031] The difference between the DOL of the thick portion 20 and the DOL of the thin portion 30 is preferably 3 μm or more and 35 μm or less, more preferably 5 μm or more and 30 μm or less, and even more preferably 7 μm or more and 25 μm or less. By setting the DOL difference within this range, bendability and breakage resistance can be ensured.

[0032] The DOL of the compressive stress layer 22 of the thick portion 20 is preferably 15 μm or more and 50 μm or less, more preferably 20 μm or more and 45 μm or less, and even more preferably 25 μm or more and 40 μm or less. Furthermore, the DOL of the compressive stress layer 22 of the thick portion 20 preferably satisfies the following formula (1). When formula (1) is applied to the DOL of the thick portion 20, t in formula (1) refers to the thickness t2 of the thick portion 20, and CS refers to the surface compressive stress CS of the thick portion 20. By setting the DOL of the thick portion 20 within this range, breakage resistance can be appropriately ensured.

[0033]

[0034] The DOL of the compressive stress layer 32 of the thin-walled portion 30 is preferably 5 μm or more and 30 μm or less, more preferably 7 μm or more and 25 μm or less, and even more preferably 10 μm or more and 20 μm or less. When the thickness t3 of the thin-walled portion 30 is 0.3 mm or more, the DOL of the compressive stress layer 32 of the thin-walled portion 30 preferably satisfies the above-mentioned formula (1). When formula (1) is applied to the DOL of the thin-walled portion 30, t in formula (1) refers to the thickness t3 of the thin-walled portion 30, and CS refers to the surface compressive stress CS of the thin-walled portion 30. When the thickness t3 of the thin-walled portion 30 is less than 0.3 mm, the DOL of the compressive stress layer 32 of the thin-walled portion 30 preferably satisfies the following formula (2). In formula (2), t refers to the thickness t3 of the thin-walled portion 30, and CS refers to the surface compressive stress CS of the thin-walled portion 30. By setting the DOL of the thin-walled portion 30 within this range, it is possible to appropriately ensure bendability and breakage resistance.

[0035]

[0036] That is, it is preferable that the DOL (mm) of the compressive stress layer 22 of the thick portion 20 satisfies the above formula (1), and the DOL (mm) of the compressive stress layer 32 of the thin portion 30 satisfies the above formula (1) when the thickness of the thin portion is 0.3 mm or more, and satisfies the above formula (2) when the thickness of the thin portion is less than 0.3 mm.

[0037] The DOL of the thick portion 20 described above is the DOL of the compressive stress layer 22 on the first main surface 20A side of the thick portion 20. The DOL of the compressive stress layer 22 on the second main surface 20B side of the thick portion 20 may also be the same as described above. Similarly, the DOL of the thin portion 30 described above is the DOL of the compressive stress layer 32 on the first main surface 30A side of the thin portion 30. The DOL of the compressive stress layer 32 on the second main surface 30B side of the thin portion 30 may also be the same as described above. However, the difference between the DOL of the compressive stress layer 32 on the first main surface 30A side of the thin portion 30 and the DOL of the compressive stress layer 32 on the second main surface 30B side of the thin portion 30 is preferably 5 μm or less, more preferably 3 μm or less, and even more preferably 1 μm or less.

[0038] Furthermore, the DOL of the thick portion 20 described above may refer to the measured value of the DOL at the central position of the thick portion 20 in the X direction. Similarly, the DOL of the thin portion 30 described above may refer to the measured value of the DOL at the central position of the thin portion 30 in the X direction. In other words, the DOL of the thick portion 20 does not have to be the value described above throughout the entire area. For example, the DOL of the thick portion 20 in a region near the thin portion 30 (for example, a region within 15 mm in the X1 direction from the boundary position between the thick portion 20 and the thin portion 30) may be the same value as the DOL of the thin portion 30. Similarly, the DOL of the thin portion 30 does not have to be the value described above throughout the entire area. For example, the DOL in the region of the thin-walled portion 30 near the thick-walled portion 20 (for example, the region within 15 mm in the X2 direction from the boundary position between the thick-walled portion 20 and the thin-walled portion 30) may be the same value as the DOL of the thick-walled portion 20.

[0039] (Compressive Stress Integration Value) The compressive stress integration values ​​of both surfaces (first main surface 20A and second main surface 20B) of thick portion 20 are calculated from the following formula (2A): Similarly, the compressive stress integration values ​​of both surfaces (first main surface 30A and second main surface 30B) of thin portion 30 are also calculated from the following formula (2A):

[0040] 1 / 2×(CS×DOL)...(2A)

[0041] That is, for example, the integral value of the compressive stress of the first main surface 30A of the thin-walled portion 30 is obtained by substituting the surface compressive stress CS of the first main surface 30A of the thin-walled portion 30 into CS in equation (2A) and substituting the DOL on the first main surface 30A side of the thin-walled portion 30 into DOL in equation (2A).

[0042] The difference between the compressive stress integral value of the compressive stress layer 32 on the first main surface 30A side of the thin-walled portion 30 and the compressive stress integral value of the compressive stress layer 32 on the second main surface 30B side of the thin-walled portion 30 is preferably 6000 MPa μm or less, more preferably 2000 MPa μm or less, and even more preferably 1000 MPa μm or less. Such a small difference in the compressive stress integral values ​​on both sides can suppress warping of the thin-walled portion 30.

[0043] (Internal Tensile Stress CT) The internal tensile stress CT of the thin-walled portion 30 is higher than the internal tensile stress CT of the thick-walled portion 20. When the internal tensile stress CT of the thin-walled portion 30 is higher than the internal tensile stress CT of the thick-walled portion 20, it is possible to appropriately ensure the fracture resistance of the thick-walled portion 20 while also appropriately ensuring the bendability starting from the thin-walled portion 30, and even if fracture occurs, the number of fractures can be reduced. The internal tensile stress CT is calculated using the following formula (3).

[0044] CT=[(1 / 2×CS Ａ ×DOL Ａ ) + (1 / 2 x CS Ｂ ×DOL Ｂ ) ] / (t-DOL Ａ -DOL Ｂ ) ... (3)

[0045] In formula (3), the surface compressive stress CS of the first principal surface of both principal surfaces is CS Ａ The depth (DOL) of the compressive stress layer on the first main surface is DOL Ａ The surface compressive stress CS of the second main surface is CS Ｂ , the depth (DOL) of the compressive stress layer on the second main surface is DOL Ｂ That is, for example, when calculating the internal tensile stress CT of the thin-walled portion 30, CS in Equation (3) is used. Ａ , DOL Ａ , C.S. Ｂ , DOL Ｂ Similarly, when calculating the internal tensile stress CT of the thick-walled portion 20, the surface compressive stress CS of the first main surface 30A, the DOL on the first main surface 30A side, the surface compressive stress CS of the second main surface 30B, and the DOL on the second main surface 30B side are substituted into CS in Equation (3), Ａ , DOL Ａ , C.S. Ｂ , DOL Ｂ are substituted with the surface compressive stress CS of the first main surface 20A, the DOL on the first main surface 20A side, the surface compressive stress CS of the second main surface 20B, and the DOL on the second main surface 20B side, respectively.

[0046] Furthermore, t in formula (3) refers to thickness. When formula (3) is applied to the internal tensile stress CT of the thin-walled portion 30, t in formula (3) refers to the thickness t3 of the thin-walled portion 30, and when formula (3) is applied to the internal tensile stress CT of the thick-walled portion 20, t in formula (3) refers to the thickness t2 of the thick-walled portion 20.

[0047] The difference between the internal tensile stress CT of the thick-walled portion 20 and the internal tensile stress CT of the thin-walled portion 30 is preferably 5 MPa or more and 125 MPa or less, more preferably 10 MPa or more and 80 MPa or less, and even more preferably 15 MPa or more and 60 MPa or less. By keeping the difference in internal tensile stress CT within this range, bendability and breakage resistance can be ensured.

[0048] The internal tensile stress CT of the thick-walled portion 20 is preferably 10 MPa or more and less than 55 MPa, more preferably 15 MPa or more and 50 MPa or less, and even more preferably 20 MPa or more and 45 MPa or less. By setting the internal tensile stress CT of the thick-walled portion 20 in this range, breakage resistance can be appropriately ensured.

[0049] The internal tensile stress CT of the thin-walled portion 30 is preferably 25 MPa or more and 135 MPa or less, more preferably 30 MPa or more and 100 MPa or less, and even more preferably 65 MPa or more and 90 MPa or less. By setting the internal tensile stress CT of the thin-walled portion 30 in this range, bendability and breakage resistance can be appropriately ensured.

[0050] Furthermore, the internal tensile stress CT of the thick portion 20 described above may refer to the internal tensile stress CT at the center position of the thick portion 20 in the X direction. Similarly, the internal tensile stress CT of the thin portion 30 described above may refer to the internal tensile stress CT at the center position of the thin portion 30 in the X direction. That is, the internal tensile stress CT of the thick portion 20 does not have to be the value described above throughout the entire region. For example, the internal tensile stress CT of the thick portion 20 in a region near the thin portion 30 (e.g., a region within 15 mm in the X1 direction from the boundary position between the thick portion 20 and the thin portion 30) may be the same as the internal tensile stress CT of the thin portion 30. Similarly, the internal tensile stress CT of the thin portion 30 does not have to be the value described above throughout the entire region. For example, the internal tensile stress CT in the region of the thin-walled portion 30 near the thick-walled portion 20 (for example, the region within 15 mm in the X2 direction from the boundary position between the thick-walled portion 20 and the thin-walled portion 30) may be the same value as the internal tensile stress CT of the thick-walled portion 20.

[0051] (Glass Material) The material of the glass 10 is arbitrary, but examples thereof include soda lime glass, aluminosilicate glass (SiO ２ -Al ２ O ３ -Na ２ O-based glass or SiO ２ -Al ２ O ３ -Li ２ O-Na ２ Among them, aluminosilicate glass is preferable from the viewpoint of strength. The material of the glass 10 is, for example, SiO 2 in mole % on an oxide basis. ２ 50% or more and 80% or less, Al ２ O ３ 1% or more and 20% or less, Na ２ O is 6% or more and 20% or less, K is ２ O is 0% or more and 11% or less, MgO is 0% or more and 15% or less, CaO is 0% or more and 6% or less, and ZrO ２ Glass materials containing 0% to 5% of SiO ２ 50% or more and 80% or less, Al ２ O ３ 2% or more and 25% or less, Li２ O 0.1% or more 20%, Na ２ O is 0.1% or more and 18% or less, K is ２ O is 0% or more and 10% or less, MgO is 0% or more and 15% or less, CaO is 0% or more and 5% or less, P ２ O ５ 0% or more and 5% or less, B ２ O ３ Between 0% and 5%, Y ２ O ３ 0% or more and 5% or less, and ZrO ２ The glass 10 may be made of a glass material containing 0% to 5% of ammonium nitrate. Alternatively, the glass 10 may be made of a chemically strengthened glass based on aluminosilicate glass (for example, "Dragon Trail (registered trademark)" manufactured by AGC).

[0052] (Glass Manufacturing Method) Next, a method for manufacturing glass 10 according to this embodiment will be described. The method for manufacturing glass according to this embodiment includes: preparing glass having a thick portion having a thickness of 0.5 mm or more and a thin portion adjacent to the thick portion and having a thickness of 0.15 mm or more but less than 0.5 mm, wherein a first main surface of the thick portion and a first main surface of the thin portion are flush with each other when the first main surface is fixed so that the first main surface is in contact with a flat surface; and chemically strengthening the glass so that the time for chemically strengthening the thick portion is longer than the time for chemically strengthening the thin portion, thereby manufacturing glass in which the DOL of the compressive stress layer in the thin portion is smaller than the DOL of the compressive stress layer in the thick portion, the internal tensile stress CT of the thin portion is higher than the internal tensile stress CT of the thick portion, and the surface compressive stress CS of the thin portion is 550 MPa or more. Figure 5 is a flowchart illustrating the method for manufacturing glass according to this embodiment.

[0053] In this manufacturing method, glass having a thick portion 20 and a thin portion 30 is prepared (step S10). The glass in this step is glass before chemical strengthening of the glass 10 described above. That is, the glass in this step has a thick portion 20 having a thickness t2 within the range described above and a thin portion 30 having a thickness t3 within the range described above, and the first main surface 20A of the thick portion 20 and the first main surface 30A of the thin portion 30 are flush with each other. Note that any method may be used to obtain glass having such a thick portion 20 and a thin portion 30, and slimming a plate-shaped glass may be used, for example. In this case, for example, the second main surface of the portion of the plate-shaped glass that will become the thick portion 20 is masked, and the plate-shaped glass is etched. As a result, the portion that will become the thick portion 20 is not etched, and the unmasked portion is etched, forming the thin portion 30. Furthermore, for example, a glass having a thick portion 20 and a thin portion 30 may be obtained by polishing or laser processing a plate glass. In this case, for example, polishing or laser processing is performed on the second main surface of the portion of the plate glass that will become the thin portion 30.

[0054] Next, the glass obtained in step S10 is chemically strengthened so that the thick portion 20 is chemically strengthened for a longer period of time than the thin portion 30, thereby obtaining glass 10 (step S12). The chemical strengthening process is performed using a known method. Examples of molten salts used in the chemical strengthening process include alkali nitrates such as potassium nitrate, sodium nitrate, potassium sulfate, and sodium sulfate, alkali sulfates, and alkali chloride salts. These molten salts are not limited to being used alone; multiple types may be used in combination, and other salts may be mixed to adjust the chemical strengthening characteristics. As a result, alkali ions (Li ions or Na ions) are ion-exchanged (substituted) in the surface layer of glass 10 with other alkali ions (Na ions or K ions) with a larger ionic radius in the molten salt, and the glass is then cooled to near room temperature. This ion exchange allows a layer (compressive stress layer) in the surface layer of glass 10 to be formed due to densification.

[0055] In this embodiment, the time for which the thick portion 20 is chemically strengthened is set longer than the time for which the thin portion 30 is chemically strengthened. This allows the DOL of the thin portion 30 to be smaller than the DOL of the thick portion 20. Any method may be used to make the time for which the thick portion 20 is chemically strengthened longer than the time for which the thin portion 30 is chemically strengthened. For example, only the thick portion 20 may be first immersed in a molten salt for chemical strengthening, and after a predetermined time has passed, both the thick portion 20 and the thin portion 30 (i.e., the entire glass 10) may be immersed in the molten salt. Alternatively, for example, both the thick portion 20 and the thin portion 30 (i.e., the entire glass 10) may be immersed in the molten salt while the thin portion 30 is protected, and after a predetermined time has passed, the protection of the thin portion 30 may be removed, and both the thick portion 20 and the thin portion 30 may be immersed in the molten salt. Any method for protecting the thin-walled portion 30 may be used, and examples thereof include covering the thin-walled portion 30 with a masking material that is impermeable to molten salt. Alternatively, for example, a paste-like molten salt for chemical strengthening may be applied to the thick-walled portion 20, and after a predetermined time has elapsed, the paste-like molten salt for chemical strengthening may also be applied to the thin-walled portion 30.

[0056] (Another Configuration Example of Glass) Next, another configuration example of the glass 10 will be described.

[0057] (Functional Layer) A functional layer may be laminated on the first main surface 10A of the glass 10. The functional layer may include one or more selected from an anti-glare layer, an anti-reflection layer, and an anti-fouling layer. When the functional layer includes two or more of an anti-glare layer, an anti-reflection layer, and an anti-fouling layer, it is preferable that each layer be laminated in the Z direction. In this case, the order in which each layer is laminated in the Z direction may be arbitrary, but when an anti-glare layer, an anti-reflection layer, and an anti-fouling layer are included, it is preferable that the anti-glare layer, the anti-reflection layer, and the anti-fouling layer are laminated in this order from the first main surface 10A side of the glass 10.

[0058] The antiglare layer is a layer that imparts antiglare properties to the glass 10. The antiglare layer may be a layer having an uneven shape. The uneven shape may be formed directly on the first main surface 10A of the glass 10, or may be formed from a layer made of a material different from that of the glass 10. The surface roughness (root mean square roughness, RMS) of this uneven shape is preferably 15 nm to 1000 nm, more preferably 10 nm to 500 nm. The antiglare layer may also be realized by an uneven shape imparted by performing an antiglare treatment and an etching treatment on the first main surface 10A of the glass 10. Alternatively, the antiglare layer may be realized by using a coating film in which particles with a desired refractive index are dispersed on the first main surface 10A of the glass 10, or by forming an uneven shape on the main surface of a transparent resin film to be attached.

[0059] The antireflection layer is a layer that suppresses light reflection. The antireflection layer reduces the reflectance of the glass 10, reducing glare caused by reflected light and, when used in a display device, improving the visibility of the display device. The configuration of the antireflection layer is not particularly limited as long as it can suppress light reflection. For example, the antireflection layer may be configured by alternately stacking high-refractive-index layers having a refractive index of 1.9 or more at a wavelength of 550 nm and low-refractive-index layers having a refractive index of 1.6 or less at a wavelength of 550 nm.

[0060] The anti-fouling layer has the function of making stains less noticeable, and suppresses the adhesion of various stains such as fingerprints, sweat, and dust. From the viewpoint of the properties of the anti-fouling layer, the anti-fouling layer is preferably formed on the outermost surface on the Z2 side of the glass 10. For example, the anti-fouling layer is made of a fluorine-containing organic compound (a compound having a fluorine-containing organic group) that can impart stain resistance, water repellency, and oil repellency. Examples of the fluorine-containing organic compound include fluorine-containing organosilicon compounds.

[0061] (Filler) The second main surface 30B of the thin-walled portion 30 may be filled with a filler. The filler may be, for example, a cured adhesive (transparent adhesive) such as a thermosetting adhesive or an ultraviolet-curing adhesive, or may be a liquid such as water, oil, an organic solvent, a liquid polymer, an ionic liquid, or a mixture thereof. More specifically, examples of the filler include propylene glycol, dipropylene glycol, tripropylene glycol, straight silicone oil (such as dimethyl silicone oil, methylphenyl silicone oil, and methylhydrogen silicone oil), modified silicone oil, acrylic acid-based polymer, liquid polybutadiene, glycerin paste, fluorine-based solvent, fluorine-based resin, acetone, ethanol, xylene, toluene, water, mineral oil, and mixtures thereof.

[0062] (Chamfering) The corners of the glass 10 (connections between the main surface and the end surface) may be chamfered.

[0063] (Configuration Having a Connection Portion) Figure 6 is a schematic cross-sectional view of glass according to another example of this embodiment. The glass 10 may have a connection portion 40 that connects the thin portion 30 and the thick portion 20. The connection portion 40 may have any shape, but as shown in Figure 6 for example, the connection portion 40 may be provided between the thin portion 30 and the thick portion 20 in the X direction, and may have a shape that decreases in thickness as it moves in the X2 direction, i.e., from the side connected to the thick portion 20 to the side connected to the thin portion 30.

[0064] More specifically, in this example, the main surface of the connection portion 40 on the first main surface 10A side is referred to as the first main surface 40A, and the main surface of the connection portion 40 on the second main surface 10B side is referred to as the second main surface 40B. That is, the first main surface 40A is the region of the entire first main surface 10A of the glass 10 where the connection portion 40 is formed, and the second main surface 40B is the region of the entire second main surface 10B of the glass 10 where the connection portion 40 is formed. In this case, the first main surface 40A of the connection portion 40 is flush with the first main surface 20A of the thick portion 20 and the first main surface 30A of the thin portion 30. Furthermore, the second main surface 40B of the connection portion 40 is inclined toward the direction Z2 (first main surface 40A) as it approaches the direction X2. That is, when the first main surface 10A is fixed so as to contact a flat surface, the first main surface 40A of the connecting portion 40 is flush with the first main surface 20A of the thick portion 20 and the first main surface 30A of the thin portion 30, and the thickness of the connecting portion 40 may decrease from the side connected to the thick portion 20 toward the side connected to the thin portion 30. The length of the connecting portion 40 in the X direction may be any length, but may be, for example, 5 mm or less. Note that the length of the connecting portion 40 in the X direction refers to the distance in the X direction from the boundary between the connecting portion 40 and the thick portion 20 to the boundary between the connecting portion 40 and the thin portion 30.

[0065] FIG. 7 is a schematic cross-sectional view of glass according to another example of this embodiment. As shown in FIG. 7 , the connection portion 40 may have an overhanging shape. An overhanging shape refers to a shape in which the first main surface 40A of the connection portion 40 is flush with the first main surface 20A of the thick portion 20 and the first main surface 30A of the thin portion 30, and the connection portion 40 is thinner than the thin portion 30 in at least a portion of its area. In other words, in the overhanging connection portion 40, at least a portion of the second main surface 40B is recessed in the direction Z2 (downward in FIG. 7 ) relative to the second main surface 30B of the thin portion 30. Providing an overhanging connection portion 40 in this manner can improve bendability. That is, when the first main surface 10A of the connection portion 40 is fixed so as to contact a flat surface, the first main surface 40A of the connection portion 40 is flush with the first main surface 20A of the thick portion 20 and the first main surface 30A of the thin portion 30, and may have an overhanging shape in which the thickness is smaller than that of the thin portion 30 in at least some areas.

[0066] The chemical strengthening of the connection portion 40 may be set arbitrarily. That is, the surface compressive stress CS, DOL, and internal tensile stress CT of the connection portion 40 may be arbitrary. For example, the surface compressive stress CS, DOL, and internal tensile stress CT of the connection portion 40 may be values ​​between those of the thin-walled portion 30 and the thick-walled portion 20. However, for example, if the connection portion 40 has an overhanging shape, the surface compressive stress CS, DOL, and internal tensile stress CT of a portion of the connection portion 40 that is thinner than the thin-walled portion 30 may be greater than those of the thin-walled portion 30.

[0067] (Multiple Thick Portions and Thin Portions) FIGS. 8 and 9 are schematic cross-sectional views of glass according to another example of this embodiment. In the above-described embodiment, the glass 10 is provided with one thick portion 20 and one thin portion 30, but this is not limited thereto. For example, the glass 10 may be provided with multiple thick portions 20 in the X direction, or multiple thin portions 30 in the X direction. In this case, the thick portions 20 and thin portions 30 are arranged alternately in the X direction. FIG. 8 shows an example of a glass having two thick portions 20 and one thin portion 30, in which the thick portions 20, thin portions 30, and thick portions 20 are arranged in this order in the X2 direction. FIG. 9 shows an example of a glass having three thick portions 20 and two thin portions 30, in which the thick portions 20, thin portions 30, thick portions 20, thin portions 30, and thick portions 20 are arranged in this order in the X2 direction.

[0068] Here, the surface compressive stress CS, DOL, and internal tensile stress CT of the thick-walled portion 20 described in the above embodiment are defined as satisfying the first chemical strengthening condition, and the surface compressive stress CS, DOL, and internal tensile stress CT of the thin-walled portion 30 described in the above embodiment are defined as satisfying the second chemical strengthening condition. When multiple thin-walled portions 30 are provided, it is preferable that all of the multiple thin-walled portions 30 satisfy the second chemical strengthening condition. That is, for example, in the example of FIG. 9, it is preferable that both of the two thin-walled portions 30 satisfy the second chemical strengthening condition. Furthermore, when multiple thick-walled portions 20 are provided, it is preferable that all of the multiple thick-walled portions 20 satisfy the first chemical strengthening condition. That is, for example, in the example of FIG. 8, it is preferable that both of the two thick-walled portions 20 satisfy the first chemical strengthening condition. However, this is not limited thereto, and only some of the multiple thick-walled portions 20 may satisfy the first chemical strengthening condition. In this case, other thick portions 20 among the plurality of thick portions 20 may not satisfy the first chemical strengthening condition but may satisfy the second chemical strengthening condition. The portion of the thick portions 20 that satisfy the first chemical strengthening condition may be any of the plurality of thick portions 20, for example, the portion closest to the X1 direction or the portion closest to the X2 direction. That is, for example, in the example of FIG. 9 , the thick portion 20 closest to the X2 direction may satisfy the first chemical strengthening condition, and the other thick portions 20 may satisfy the second chemical strengthening condition. Similarly, only some of the plurality of thin portions 30 may satisfy the second chemical strengthening condition. In this case, other thin portions 30 among the plurality of thin portions 30 may not satisfy the second chemical strengthening condition but may satisfy the first chemical strengthening condition. The portion of the thin portions 30 that satisfy the second chemical strengthening condition may be any of the plurality of thin portions 30, for example, the portion closest to the X1 direction or the portion closest to the X2 direction. That is, for example, in the example of FIG. 9, the thin-walled portion 30 closest to the X2 direction may satisfy the second chemical strengthening condition, and the other thin-walled portions 30 may satisfy the first chemical strengthening condition.

[0069] (Effects) As described above, glass 10 according to the first aspect of the present disclosure has thick portion 20 having a thickness of 0.5 mm or more and thin portion 30 adjacent to thick portion 20 and having a thickness of 0.15 mm or more and less than 0.5 mm. The first main surface 20A of thick portion 20 and the first main surface 30A of thin portion 30 are flush with each other when first main surface 10A is fixed so as to contact a flat surface. The internal tensile stress CT of thin portion 30 is higher than the internal tensile stress CT of thick portion 20, the DOL of compressive stress layer 32 of thin portion 30 is smaller than the DOL of compressive stress layer 22 of thick portion 20, and the surface compressive stress CS of thin portion 30 is 550 MPa or more. Having thick portion 20 and thin portion 30 enables glass 10 according to the present disclosure to be bent appropriately. On the other hand, when chemically strengthening glass that can be bent by providing thick and thin portions, the thicknesses of the thick and thin portions are different, so that appropriate chemical strengthening cannot be performed, which may result in a decrease in bendability and breakage resistance, or an increase in the number of fractures in the event of breakage. In contrast, in this embodiment, the internal tensile stress CT of the thin portion 30 is made higher than the internal tensile stress CT of the thick portion 20, the DOL of the compressive stress layer 32 of the thin portion 30 is made smaller than the DOL of the compressive stress layer 22 of the thick portion 20, and the surface compressive stress CS of the thin portion 30 is made 550 MPa or more, thereby ensuring bendability and breakage resistance while reducing the number of fractures in the event of breakage.

[0070] Glass 10 according to a second aspect of the present disclosure is glass 10 according to the first aspect, wherein the difference between the compressive stress integrated value of the compressive stress layer 32 on the first main surface 30A side of the thin portion 30 and the compressive stress integrated value of the compressive stress layer 32 on the second main surface 30B side of the thin portion 30 is preferably 6000 MPa μm or less. This makes it possible to suppress warpage of the thin portion 30.

[0071] The glass 10 according to a third aspect of the present disclosure is the glass 10 according to the first or second aspect, wherein the thickness of the thick portion 20 is preferably 0.5 mm or more and less than 5.0 mm. By setting the thickness of the thick portion 20 within this range, it is possible to ensure light weight and breakage resistance while reducing the number of fractures in the event of breakage.

[0072] Glass 10 according to a fourth aspect of the present disclosure is glass 10 according to any of the first to third aspects, wherein the difference between the surface compressive stress CS of the thin portion 30 and the surface compressive stress CS of the thick portion 20 is preferably 100 MPa or less. Setting the difference in surface compressive stress CS within this range enables the process to be shortened and costs to be further reduced.

[0073] Glass 10 according to a fifth aspect of the present disclosure is glass 10 according to any of the first to fourth aspects, wherein the DOL (mm) of the compressive stress layer in the thick portion 20 preferably satisfies the above formula (1), and the DOL (mm) of the compressive stress layer in the thin portion preferably satisfies the above formula (1) when the thickness of the thin portion 30 is 0.3 mm or more, and satisfies the above formula (2) when the thickness of the thin portion 30 is less than 0.3 mm. By setting the DOL within this range, the number of fractures in the event of breakage can be reduced.

[0074] Glass 10 according to a sixth aspect of the present disclosure is glass 10 according to any of the first to fifth aspects, and preferably includes a connection portion 40 that connects the thin portion 30 and the thick portion 20. By including the connection portion 40, a sudden change in thickness can be suppressed, and breakage can be more suitably suppressed.

[0075] Glass 10 according to a seventh aspect of the present disclosure is glass 10 according to the sixth aspect, wherein first main surface 40A of connection portion 40 is flush with first main surface 20A of thick portion 20 and first main surface 30A of thin portion 30 in a state in which first main surface 10A is fixed so as to be in contact with a flat surface, and it is preferable that the thickness of connection portion 40 decreases from the side connected to thick portion 20 toward the side connected to thin portion 30. Having such connection portion 40 makes it possible to prevent a sudden change in thickness and more suitably suppress breakage.

[0076] Glass 10 according to an eighth aspect of the present disclosure is glass 10 according to the sixth aspect, wherein connecting portion 40 preferably has an overhanging shape such that, in a state in which first main surface 10A is fixed so as to contact a flat surface, first main surface 40A of connecting portion 40 is flush with first main surface 20A of thick portion 20 and first main surface 30A of thin portion 30, and has a thickness smaller than that of thin portion 30 in at least a partial region. Having connecting portion 40 with such an overhanging shape enables appropriate bending.

[0077] A display device 1 according to a ninth aspect of the present disclosure includes a display 12 and the glass 10 according to any one of the first to eighth aspects. According to the present disclosure, it is possible to reduce the number of shatters in the event of breakage while ensuring bendability and breakage resistance.

[0078] A method for manufacturing glass according to a tenth aspect of the present disclosure includes preparing glass having a thick portion 20 having a thickness of 0.5 mm or more and a thin portion 30 adjacent to the thick portion 20 and having a thickness of 0.15 mm or more and less than 0.5 mm, wherein a first main surface 20A of the thick portion 20 and a first main surface 30A of the thin portion 30 are flush with each other when the first main surface 10A is fixed so that the first main surface 10A is in contact with a flat surface; and chemically strengthening the glass such that the time for chemically strengthening the thick portion 20 is longer than the time for chemically strengthening the thin portion 30, thereby manufacturing glass in which the DOL of the compressive stress layer 32 of the thin portion 30 is smaller than the DOL of the compressive stress layer 22 of the thick portion 20, the internal tensile stress CT of the thin portion 30 is higher than the internal tensile stress CT of the thick portion 20, and the surface compressive stress CS of the thin portion 30 is 550 MPa or more. According to the present disclosure, glass 10 can be manufactured that ensures bendability and breakage resistance while reducing the number of fractures in the event of breakage.

[0079] Examples Next, examples will be described. Tables 1 and 2 show the glasses and evaluation results in each example. The embodiment may be modified as long as the effects of the invention are achieved.

[0080]

[0081] (Example 1) In Example 1, a glass substrate (Dragontrail manufactured by AGC) having a size of 120 mm x 60 mm x 1.1 mm (length x width x thickness) was used. ＴＭ A glass substrate with regions of different thicknesses was prepared. An acid-resistant UV-peelable film was attached to the entire surface of one side of the glass substrate and to a region 20 mm from the edge of the other side in the vertical direction. The region between 20 mm and 120 mm from the edge was then thinned by an etching method in which the film was swung and dipped in a mixed solution of hydrofluoric acid and hydrochloric acid until the thickness reached 0.3 mm. The film surface was then irradiated with UV light to peel it off from the glass, yielding a glass substrate with regions of different thicknesses. The thick portion was 20 mm x 60 mm x 1.1 mm (length x width x thickness), and the thin portion was 100 mm x 60 mm x 0.3 mm (length x width x thickness). Furthermore, a 450°C KNO ３ A molten salt bath was prepared, and a region of the glass substrate extending vertically from the edge to 20 mm was first immersed in the molten salt for 30 minutes. Thereafter, the entire glass substrate was immersed in the molten salt for 1 hour, thereby obtaining the glass of Example 1.

[0082] The internal tensile stress CT, the DOL of the compressive stress layer, and the surface compressive stress CS of the thick and thin portions of the glass of Example 1 were measured. The measurement methods used were those described in the above-mentioned embodiment. The measurement results are shown in Table 1. In addition, the upper limit DOL of the thin portion was calculated based on the thickness and surface compressive stress CS of the thin portion. The upper limit DOL is the value on the right side of formula (1) or formula (2).

[0083] (Examples 2, 3, 5 to 12) In Examples 2, 3, 5 to 12, glass having the same properties as Example 1 was obtained, except that at least one of the thickness of the thin-walled portion, the internal tensile stress CT, the DOL of the compressive stress layer, and the surface compressive stress CS was changed as shown in Table 1. In Examples 2, 3, 5 to 12, glass was obtained by heating in a KNO atmosphere at 350°C to 450°C. ３ or NaNO ３ The thick-walled section was immersed in a molten salt bath containing 100% ammonium hydroxide for 0.5 to 1.5 hours. The CS and DOL of the thick-walled section were adjusted to be equivalent to those of chemical strengthening at 450°C for 1.5 hours.

[0084] (Evaluation) In the evaluation, bending property, breakability, and the number of fragments (number of fragments) upon breakage were evaluated.

[0085] (Bendability) FIG. 10 is a schematic diagram illustrating a method for evaluating bendability. In the evaluation of bendability, the second main surface 20B of the thick portion 20 of the glass sheet 10 and the second main surface 30B of the thin portion 30 were each placed on a steel plate, the distance between the plates was reduced, and the glass sheet 10 was bent from a position 30P 20 mm toward the thin portion 30 from the boundary between the thick portion 20 and the thin portion 30. The bending radius (radius of curvature) of the glass sheet 10 at the time of breakage was calculated based on the distance between the plates at the time of breakage. The calculation results of the bending radius are shown in Table 1. In the evaluation of bendability, a bending radius of less than 15 mm was rated as excellent, a bending radius of 15 mm to 20 mm was rated as good, and a bending radius of more than 20 mm was rated as unacceptable.

[0086] (Breakability) Breakability was evaluated by measuring the BOR strength F (N) using a ball-on-ring (BOR) test. In the ball-on-ring test, a glass was placed on a stainless steel ring having a diameter of 30 mm and a rounded contact portion with a curvature radius of 2.5 mm. A steel sphere having a diameter of 10 mm was brought into contact with the glass, and a load was applied to the sphere toward the center of the ring under static loading conditions. The BOR strength F was calculated based on the load at which the glass broke. The calculation results of the BOR strength F are shown in Table 1. In the evaluation of the BOR strength F, a BOR strength F of more than 300 N was rated as excellent, a BOR strength F of 200 N to 300 N was rated as good, and a BOR strength F of less than 200 N was rated as unsuccessful.

[0087] (Number of fractures) To evaluate the number of fractures, an indenter was pressed into the center of the thin-walled portion of the glass under static load conditions, perpendicular to the surface of the glass, using an indentation tester (Shimadzu Corporation, EZ-X). The indenter attached to the indentation tester was an acute-angle indenter with a facing angle of 60°, and pressed into the surface of the glass at a speed of 60 μm / s so that a load of 1.0 kgf was applied. The state in which this load was reached was maintained for 15 seconds, and then the indenter was unloaded and the glass was observed 15 seconds later. The number of broken glass fragments (number of fractures) was counted. The results of the measurement of the number of fractures are shown in Table 1. In the evaluation of the number of fractures, a number of fractures less than 10 was considered good, and a number of fractures of 10 or more was considered unsuccessful.

[0088] (Evaluation Results) As shown in Table 1, the glasses of Examples 1, 3, 5 to 7, which are working examples, all achieved excellent or good ratings for bendability, breakage resistance, and number of fractures, ensuring bendability and breakage resistance while reducing the number of fractures in the event of breakage. On the other hand, the glasses of Examples 8 to 12, which are comparative examples, achieved poor ratings for at least one of bendability, breakage resistance, and number of fractures, ensuring bendability and breakage resistance while not reducing the number of fractures in the event of breakage. For example, in Example 8, the surface compressive stress CS of the thin-walled portion was less than 550 MPa, making it impossible to ensure bendability and breakage resistance. In Example 9, the surface compressive stress CS of the thin-walled portion was less than 550 MPa, making it impossible to ensure bendability and breakage resistance. In Example 10, the thin-walled portion was too thick to ensure bendability. In Example 11, the thin-walled portion was too thin to ensure breakage resistance and number of fractures. In Example 12, the DOL of the compressive stress layer in the thin portion is larger than the DOL of the compressive stress layer in the thick portion, and the number of fractures cannot be guaranteed.

[0089] (Optional Evaluation) As an optional evaluation, the glasses of Examples 13 to 15 were evaluated for warpage.

[0090] (Example 13) In Example 13, a glass substrate (DT-Pro manufactured by AGC) having a size of 50 mm × 50 mm × 0.7 mm (length × width × thickness) was prepared. ３A molten salt bath was prepared, and the entire glass substrate was immersed in the molten salt for 1 hour. Next, an acid-resistant UV-release film was attached to the entire surface of one side of the glass substrate and to a region 20 mm vertically from the edge of the other side. The surface between 20 mm and 50 mm from the edge was then thinned by an etching method in which the film was swung and dipped in a mixed solution of hydrofluoric acid and hydrochloric acid until the thickness reached 0.4 mm. The film surface was then irradiated with UV light, and the film was peeled from the glass, resulting in a glass substrate with regions of different thicknesses. The thick portion measured 50 mm x 20 mm x 0.7 mm (length x width x thickness), and the thin portion measured 50 mm x 30 mm x 0.4 mm (length x width x thickness).

[0091] Example 14 In Example 14, a glass substrate (DT-Pro manufactured by AGC) having dimensions of 50 mm x 50 mm x 0.7 mm (length x width x thickness) was prepared. The first chemical strengthening was performed by KNO ３ A molten salt bath was prepared, and the entire glass substrate was immersed in the molten salt for 0.5 hours. Next, an acid-resistant UV-release film was attached to the entire surface of one side of the glass substrate and to a region 20 mm vertically from the edge of the other side. The surface between 20 mm and 50 mm from the edge was then thinned by an etching method in which the film was swung and dipped in a mixed solution of hydrofluoric acid and hydrochloric acid until the thickness reached 0.4 mm. The film surface was then irradiated with UV light to peel the film from the glass, yielding a glass substrate with regions of different thicknesses. The entire glass substrate was then immersed in the molten salt for 0.5 hours to obtain the glass of Example 14. The thick portion measured 50 mm x 20 mm x 0.7 mm (length x width x thickness), and the thin portion measured 50 mm x 30 mm x 0.4 mm (length x width x thickness).

[0092] (Example 15) In Example 15, a glass substrate (DT-Pro manufactured by AGC) measuring 50 mm x 50 mm x 0.7 mm (length x width x thickness) was prepared. An acid-resistant UV-peelable film was attached to the entire surface of one side of the glass substrate and to an area 20 mm from the edge of the other side in the vertical direction. The area between 20 mm and 50 mm from the edge was then thinned by an etching method in which the surface was swung and dipped in a mixed solution of hydrofluoric acid and hydrochloric acid until the thickness reached 0.4 mm. The film surface was then irradiated with UV light to peel the film from the glass, yielding a glass substrate with areas of different thicknesses. Next, the first chemical strengthening was performed using KNO at 450°C. ３ A molten salt bath was prepared, and only the thick portion of the glass substrate was immersed in the molten salt for 0.5 hours. The entire glass substrate was then immersed in the molten salt for 0.5 hours. The thick portion had dimensions of 50 mm × 20 mm × 0.7 mm (length × width × thickness), and the thin portion had dimensions of 50 mm × 30 mm × 0.4 mm (length × width × thickness).

[0093] The DOL and surface compressive stress CS of the compressive stress layer were measured for the first and second principal surfaces of the thin-walled portions of the glass of Examples 13 to 15. The measurement methods used were the same as those described in the above embodiment. Furthermore, using equation (2A) of this embodiment, the compressive stress integrals of the first and second principal surfaces were calculated, and the difference between the compressive stress integrals of the first and second principal surfaces was calculated. The measurement results are shown in Table 2.

[0094] (Warpage) FIG. 11 is a schematic diagram showing the evaluation of warpage. As shown in FIG. 11, in the evaluation of warpage, the length L of the thin-walled portion in a direction parallel to the first main surface 10A of the glass was pressed against the flat surface ST, and the warpage d, which is the distance from the flat surface to the tip of the thin-walled portion, was measured. The ratio (d / L) of the warpage d to the length L was then calculated as the warpage rate. The calculation results of the warpage rate are shown in Table 2. As shown in Table 2, in Example 15, the difference in the compressive stress integral between the first main surface and the second main surface was 6000 MPa μm or less, indicating that the warpage rate could be reduced and warpage could be suppressed.

[0095] Although the embodiments of the present invention have been described above, the embodiments are not limited to the contents of these embodiments. Furthermore, the above-described components include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the scope of what is called equivalents. Furthermore, the above-described components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the above-described embodiments.

[0096] According to the present invention, it is possible to provide glass, a display device, and a method for manufacturing glass that have sufficient bendability and breakage resistance while reducing the number of breakages.

[0097] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2023-150100) filed on September 15, 2023, the contents of which are incorporated herein by reference.

[0098] REFERENCE SIGNS LIST 1 display device 10 glass 12 display 10A, 20A, 30A, 40A first main surface 10B, 20B, 30B, 40B second main surface 14 base 20 thick portion 22 compressive stress layer 30 thin portion 32 compressive stress layer 40 connection portion

Claims

1. A glass having a thick portion having a thickness of 0.5 mm or more, and a thin portion adjacent to the thick portion and having a thickness of 0.15 mm or more and less than 0.5 mm, wherein a first main surface of the thick portion and a first main surface of the thin portion are flush with each other when the first main surface of the glass is fixed so as to be in contact with a flat surface, the internal tensile stress CT of the thin portion is higher than the internal tensile stress CT of the thick portion, the DOL of a compressive stress layer of the thin portion is smaller than the DOL of a compressive stress layer of the thick portion, and the surface compressive stress CS of the thin portion is 550 MPa or more.

2. The glass according to claim 1, wherein the difference between the compressive stress integral value of the compressive stress layer on the first principal surface side of the thin-walled portion and the compressive stress integral value of the compressive stress layer on the second principal surface side of the thin-walled portion is 6000 MPa·μm or less.

3. The glass according to claim 1 or 2, wherein the thick portion has a thickness of 0.5 mm or more and less than 5.0 mm.

4. The glass according to claim 1 or 2, wherein the difference between the surface compressive stress CS of the thin portion and the surface compressive stress CS of the thick portion is 100 MPa or less.

5. The glass according to claim 1 or 2, wherein the DOL (mm) of the compressive stress layer in the thick portion satisfies formula (1), and the DOL (mm) of the compressive stress layer in the thin portion satisfies formula (1) when the thickness of the thin portion is 0.3 mm or more, and satisfies formula (2) when the thickness of the thin portion is less than 0.3 mm. Here, t indicates the thickness (mm) of the thick or thin portion.

6. The glass according to claim 1 or 2, further comprising a connecting portion connecting the thin portion and the thick portion.

7. The glass according to claim 6, wherein a first main surface of the connection portion is flush with the first main surface of the thick portion and the first main surface of the thin portion in a state in which the first main surface of the glass is fixed so as to be in contact with a flat surface, and the thickness of the connection portion decreases from the side connected to the thick portion toward the side connected to the thin portion.

8. The glass according to claim 6, wherein the first main surface of the connection portion is flush with the first main surface of the thick portion and the first main surface of the thin portion in a state in which the first main surface of the glass is fixed so as to contact a flat surface, and has an overhanging shape having a thickness smaller than that of the thin portion in at least a portion of the region.

9. A display device comprising a display and the glass according to claim 1 or 2.

10. A method for manufacturing glass, comprising: preparing glass having a thick portion having a thickness of 0.5 mm or more, and a thin portion adjacent to the thick portion and having a thickness of 0.15 mm or more and less than 0.5 mm, wherein a first main surface of the thick portion and a first main surface of the thin portion are flush with each other when the first main surface of the glass is fixed so that it is in contact with a flat surface; and chemically strengthening the glass such that a time for chemically strengthening the thick portion is longer than a time for chemically strengthening the thin portion, thereby manufacturing glass such that the DOL of the compressive stress layer of the thin portion is smaller than the DOL of the compressive stress layer of the thick portion, the internal tensile stress CT of the thin portion is higher than the internal tensile stress CT of the thick portion, and the surface compressive stress CS of the thin portion is 550 MPa or more.

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