Glass, display device, and method for manufacturing glass

Abstract

This glass (10) has sufficient bendability and breakage resistance, and is capable of reducing the number of fractures. The glass (10) has a thick portion (20) having a thickness (t2) 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 but less than 0.5 mm, the first main surface (20A) of the thick portion (20) is flush with the first main surface (30A) of the thin portion (30) in a state where the first main surface (10A) of the glass (10) is fixed in contact with a flat surface, and the internal tensile stress CT of the thin portion (30) is higher than the internal tensile stress CT of the thick portion (20). The DOL of the compressive stress layer of the thin section (30) is smaller than the DOL of the compressive stress layer of the thick section (20), and the surface compressive stress (CS) of the thin section (30) is 550 MPa or more.

Description

TECHNICAL FIELD

[0001] The present application relates to a glass, a display device, and a manufacturing method of a glass. BACKGROUND

[0002] In order to protect a display or the like as a protection object, a cover glass is sometimes arranged. For example, a cover member in which recesses are provided on both main surfaces and one of the recesses is formed in a curved shape is described in Patent Literature 1.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: International Publication No. 2018 / 116981 SUMMARY

[0006] Here, for a glass for a cover member or the like, it is required to have sufficient bendability and breakage resistance, and to be able to reduce the number of breakage (the number of fragments) even at the time of breakage.

[0007] An object of the present application is to provide a glass having sufficient bendability and breakage resistance and capable of reducing the number of breakage, a display device, and a manufacturing method of a glass.

[0008] The glass according to the present disclosure has a thick wall portion having a thickness of 0.5 mm or more and a thin wall portion adjacent to the thick wall portion and having a thickness of 0.15 mm or more and less than 0.5 mm, a first main surface of the thick wall portion is flush with a first main surface of the thin wall portion in a state where the first main surface of the glass is fixed to be in contact with a flat surface, an internal tensile stress CT of the thin wall portion is higher than an internal tensile stress CT of the thick wall portion, a DOL of a compressive stress layer of the thin wall portion is smaller than a DOL of a compressive stress layer of the thick wall portion, and a surface compressive stress CS of the thin wall portion is 550 MPa or more.

[0009] The display device according to the present disclosure has a display and the glass described above.

[0010] The manufacturing method of a glass according to the present disclosure includes the steps of:

[0011] A glass having a thick wall portion with a thickness of 0.5 mm or more, and a thin wall portion adjoining the thick wall portion and having a thickness of 0.15 mm or more and less than 0.5 mm, the first main surface of the thick wall portion being flush with the first main surface of the thin wall portion in a state where the first main surface of the glass is fixed in contact with a flat surface, and the glass being chemically strengthened in a manner such that the time for chemically strengthening the thick wall portion is longer than the time for chemically strengthening the thin wall portion, thereby producing a glass in which the DOL of the compressive stress layer of the thin wall portion is less than the DOL of the compressive stress layer of the thick wall portion, the internal tensile stress CT of the thin wall portion is higher than the internal tensile stress CT of the thick wall portion, and the surface compressive stress CS of the thin wall portion is 550 MPa or more.

[0012] According to the present application, sufficient bendability and breakage resistance are achieved, and the number of breakages can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a cross-sectional view of a display device to which the present embodiment relates.

[0014] Figure 2 is a schematic cross-sectional view of a glass to which the present embodiment relates.

[0015] Figure 3 is a schematic cross-sectional view of a glass to which the present embodiment relates.

[0016] Figure 4 is a schematic plan view of a glass to which the present embodiment relates.

[0017] Figure 5 is a flowchart illustrating a method of producing a glass to which the present embodiment relates.

[0018] Figure 6 is a schematic cross-sectional view of a glass to which another example of the present embodiment relates.

[0019] Figure 7 is a schematic cross-sectional view of a glass to which another example of the present embodiment relates.

[0020] Figure 8 is a schematic cross-sectional view of a glass to which another example of the present embodiment relates.

[0021] Figure 9 is a schematic cross-sectional view of a glass to which another example of the present embodiment relates.

[0022] Figure 10 is a schematic view illustrating an evaluation method of bendability.

[0023] Figure 11 is a schematic view illustrating an evaluation of warpage. DETAILED DESCRIPTION

[0024] The preferred embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be noted that the present application is not limited to the embodiments, and that, when there are a plurality of embodiments, a combination of the embodiments is also included. In addition, the numerical values include a range of rounding.

[0025] (Display device)

[0026] The display device according to the present embodiment has a display and the glass according to the present embodiment.

[0027] Figure 1 is a cross-sectional view of the display device according to the present embodiment. The display device 1 according to the present embodiment is a display device provided in a vehicle. The display device 1 has a glass 10, a display 12, and a base 14 that supports the display 12. The glass 10 is a glass having a first main surface 10A as one main surface and a second main surface 10B as the other main surface, the details of which will be described later. The glass 10 serves as a cover member that protects the display 12. The glass 10 is mounted to the display 12 in such a manner that the second main surface 10B faces the display surface side of the display 12. The second main surface 10B of the glass 10 can be attached to the display 12 via an optical clear adhesive (OCA) or an optical clear resin (OCR), which are not shown.

[0028] The display 12 is a panel that displays an image, and can be, for example, a liquid crystal panel, an organic EL panel, a PDP, an electronic ink type panel, or the like, and can have a touch panel or the like. In the example of Figure 1 , a plurality of displays 12 are provided, and the directions in which the respective display surfaces face are different. The glass 10 covers the display surfaces of the respective displays 12 in a bent state.

[0029] Among them, Figure 1 The configuration of the display device 1 to which the glass 10 is applied is one example, and the display device 1 to which the glass 10 is applied can have any configuration. For example, in the display device 1, the number of displays 12 is not limited to two, and can be any number. In addition, the display 12 can be deformable. As a deformable display, it can be a so-called rollable display, and the shape of the screen can be changed by winding and unwinding. In addition, the display 12 can be a movable display, and a part or the whole thereof is folded and unfolded by a mechanism provided in the display device 1.

[0030] In addition, the display device 1 is not limited to being provided in a vehicle, and can be used for any purpose. In addition, the glass 10 is not limited to being used as a cover member of the surface of the display device 1, and can be used for any purpose.

[0031] The glass according to the present embodiment has:

[0032] a thick wall portion having a thickness of 0.5 mm or more, and

[0033] a thin wall portion adjacent to the thick wall portion and having a thickness of 0.15 mm or more and less than 0.5 mm,

[0034] a first main surface of the thick wall portion is flush with a first main surface of the thin wall portion in a state where the first main surface of the glass is fixed in contact with a flat surface,

[0035] an internal tensile stress CT of the thin wall portion is higher than an internal tensile stress CT of the thick wall portion,

[0036] a DOL of a compressive stress layer of the thin wall portion is smaller than a DOL of a compressive stress layer of the thick wall portion,

[0037] a surface compressive stress CS of the thin wall portion is 550 MPa or more.

[0038] (Glass)

[0039] Figure 2 is a schematic cross-sectional view of a glass according to the present embodiment. Figure 2 The glass 10 in a bent state is shown. As shown in Figure 2 , the glass 10 has a thick wall portion 20 and a thin wall portion 30 having a thickness smaller than the thick wall portion 20. In the glass 10, a part of the thin wall portion 30 is bent. In the present embodiment, as shown in Figure 2 , the glass 10 is bent in a manner that the second main surface 10B is concave, but is not limited thereto, and can be bent in a manner that the second main surface 10B is convex. In addition, when the glass 10 is mounted on the display device 1, the first main surface 10A becomes a side exposed to the outside, and the second main surface 10B becomes a side facing the display 12.

[0040] Figure 3 is a schematic cross-sectional view of a glass according to the present embodiment, Figure 4 is a schematic plan view of a glass according to the present embodiment. Figure 3 and Figure 4 The glass 10 when fixed in a state in contact with a flat surface is shown.

[0041] The first main surface 10A of the glass 10 is preferably flat in a state where it is fixed in contact with a flat surface. Here, the state where the first main surface 10A is fixed in contact with a flat surface means that approximately the entire area of ​​the first main surface 10A is in contact with the flat surface solely by its own weight, thus making the first main surface 10A lie along the flat surface. This can also be described as a state where it is not subjected to external loads and does not undergo elastic deformation due to external loads. It should be noted that "approximately the entire area of ​​the first main surface 10A" can refer to the entire area of ​​the first main surface 10A, but is not limited to this; for example, it can refer to an area of ​​more than 95% of the entire area of ​​the first main surface 10A.

[0042] Unless otherwise specified, in the following description, glass 10 refers to glass that is fixed in a state in which the first main surface 10A is in contact with the flat surface.

[0043] Furthermore, the direction connecting the first main surface 10A and the second main surface 10B (perpendicular to the flat surface), i.e., the thickness direction of the glass 10, when the first main surface 10A is in contact with the flat surface, is designated as the Z direction. A direction orthogonal to the Z direction is designated as the X direction, and a direction orthogonal to both the Z and X directions is designated as the Y direction. Additionally, among the orientations parallel to the Z direction, the orientation from the first main surface 10A to the second main surface 10B is designated as orientation Z1, and the other orientation is designated as orientation Z2. Furthermore, among the orientations parallel to the X direction, one orientation (… Figure 3 In the example, the orientation of one side (facing right) is set as X1, and the orientation of the other side is set as orientation X2. Similarly, in orientations parallel to the Y direction, the orientation of one side ( Figure 3 In the example, the direction of the paper's inner side is set as Y1, and the direction of the other side is set as Y2.

[0044] In the example of this implementation, such as Figure 4 As shown, when viewed from the Z1 direction, glass 10 is rectangular. However, the shape of glass 10 is not limited to being rectangular when viewed from the Z1 direction; it can be any shape.

[0045] like Figure 3 As shown, the glass 10 has a thick-walled portion 20 and a thin-walled portion 30 with a thickness less than that of the thick-walled portion 20. Here, thickness refers to the length of the thick-walled portion 20 or the thin-walled portion 30 in the Z direction. The thick-walled portion 20 and the thin-walled portion 30 are arranged along the X direction. In this embodiment, the thin-walled portion 30 is provided on the X2-facing side of the thick-walled portion 20.

[0046] The thin-walled portion 30 is a recess formed by recessing the second main surface 10B of the glass 10. That is, if the main surface on the side of the second main surface 10B of the thick-walled portion 20 is designated as the second main surface 20B, and the main surface on the side of the second main surface 10B of the thin-walled portion 30 is designated as the second main surface 30B, then the thick-walled portion 20 refers to the portion in the glass 10 where the second main surface 20B and the second main surface 10B of the glass 10 are on the same surface. Moreover, the thin-walled portion 30 refers to the portion in the glass 10 where the second main surface 30B is located on the side of the first main surface 10A relative to the second main surface 10B of the glass 10 (i.e., the second main surface 20B of the thick-walled portion 20).

[0047] Furthermore, the main surface on the side of the first main surface 10A of the thick-walled portion 20 is designated as the first main surface 20A, and the main surface on the side of the first main surface 10A of the thin-walled portion 30 is designated as the first main surface 30A. It can be said that the first main surface 20A is the area in the entire region of the first main surface 10A of the glass 10 where the thick-walled portion 20 is formed, and the first main surface 30A is the area in the entire region of the first main surface 10A of the glass 10 where the thin-walled portion 30 is formed.

[0048] First main surface 20A is flush with first main surface 30A. Flush means a smooth connection without any step difference. For example, if the overall flatness of first main surface 10A is less than 0.05mm, then first main surface 20A and first main surface 30A can be considered flush.

[0049] It should be noted that flatness can be measured using a three-dimensional measuring instrument, such as a contact probe or a laser probe, according to the definition and representation of geometric deviations in JIS B 0621. Similarly, the position of each location relative to the reference point in the Z direction can also be measured using a three-dimensional measuring instrument using a contact probe or a laser probe.

[0050] like Figure 4 As shown, the thin-walled portion 30 extends in the Y direction. The thin-walled portion 30 is formed in the Y direction from one end of the glass 10 to the other end. Figure 4 In this process, the glass 10 can be bent about the Y-axis. However, the shape of the thin-walled portion 30 is not limited to this. For example, the thin-walled portion 30 can extend in a direction inclined relative to the Y-axis, and the extension direction can be curved rather than straight. In addition, the thin-walled portion 30 can be provided in a portion of the section from one end of the glass 10 to the other end in the Y-axis.

[0051] (thickness)

[0052] The thickness t2 of the thick wall portion 20 is 0.5 mm or more, preferably 0.5 mm or more and less than 5.0 mm, and more preferably 1.0 mm to 3.0 mm. By making the thickness t2 within this range, it is possible to ensure breakage resistance. Note that 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 wall portion 20.

[0053] The thickness t3 of the thin wall portion 30 is 0.15 mm or more and less than 0.5 mm, preferably 0.20 mm to 0.45 mm, and more preferably 0.25 mm to 0.40 mm. By making the thickness t3 within this range, it is possible to ensure bendability and breakage resistance. 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 wall portion 30.

[0054] The ratio (t3 / t2) of the thickness t3 of the thin wall portion 30 to the thickness t2 of the thick wall portion 20 is preferably 5% to 60%, more preferably 10% to 50%, and further preferably 15% to 40%. By making the ratio of the thickness within this range, it is possible to ensure bendability and breakage resistance.

[0055] (Compressive stress layer)

[0056] The glass 10 is formed with a compressive stress layer on the first main surface 10A side and the second main surface 10B side. That is, the compressive stress layer 22 is formed on the first main surface 20A side and the second main surface 20B side of the thick wall portion 20. Similarly, the compressive stress layer 32 is formed on the first main surface 30A side and the second main surface 30B side of the thin wall portion 30. The compressive stress layers 22, 32 are formed by subjecting the glass 10 to a chemical strengthening treatment.

[0057] (Surface compressive stress CS)

[0058] The surface compressive stress CS of the thick wall portion 20 is preferably 550 MPa or more, more preferably 650 MPa to 1300 MPa, and further preferably 750 MPa to 1200 MPa. By making the surface compressive stress CS of the thick wall portion 20 within this range, it is possible to ensure breakage resistance. The method of measuring the surface compressive stress CS is arbitrary, and for example, it is possible to measure it using a surface stress meter FSM-6000LE manufactured by Kojundo

[0059] The surface compressive stress CS of the thin wall portion 30 is 550 MPa or more, preferably 650 MPa to 1300 MPa, and more preferably 750 MPa to 1200 MPa. By making the surface compressive stress CS of the thin wall portion 30 within this range, it is possible to ensure breakage resistance.

[0060] 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 further preferably 50 MPa or less. By reducing the difference in the surface compressive stress CS in this way, the number of processes for chemical strengthening can be reduced, the processes can be shortened, and thus the cost can be further reduced.

[0061] Note that the surface compressive stress CS of the thick-walled portion 20 described above is the surface compressive stress of the first main surface 20A of the thick-walled 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-walled portion 20 (the surface compressive stress of the compressive stress layer 22 on the second main surface 20B side) can be the same as described above.

[0062] Similarly, the surface compressive stress CS of the thin-walled portion 30 described above is the surface compressive stress of the first main surface 30A of the thin-walled 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-walled portion 30 (the surface compressive stress of the compressive stress layer 32 on the second main surface 30B side) can be the same as described above.

[0063] 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 further preferably 10 MPa or less. By reducing the difference in the surface compressive stress CS in this way, warping can be more appropriately suppressed.

[0064] In addition, the surface compressive stress CS of the thick-walled portion 20 described above can refer to a measured value of the surface compressive stress CS of the thick-walled portion 20 at a central position in the X direction (a direction in which the thick-walled portion 20 and the thin-walled portion 30 are adjacent to each other). Similarly, the surface compressive stress CS of the thin-walled portion 30 described above can refer to a measured value of the surface compressive stress CS of the thin-walled portion 30 at a central position in the X direction.

[0065] That is, in the range having the inventive effect, the surface compressive stress CS of the thick wall portion 20 does not need to reach the above-described value in the entire region. For example, the surface compressive stress CS of a region in the thick wall portion 20 near the thin wall portion 30 (for example, a region within 15 mm in the Xl direction from the boundary position between the thick wall portion 20 and the thin wall portion 30) can be the same value as the surface compressive stress CS of the thin wall portion 30. Similarly, the surface compressive stress CS of the thin wall portion 30 does not need to reach the above-described value in the entire region. For example, the surface compressive stress CS of a region in the thin wall portion 30 near the thick wall portion 20 (for example, a region within 15 mm in the X2 direction from the boundary position between the thick wall portion 20 and the thin wall portion 30) can be the same value as the surface compressive stress CS of the thick wall portion 20.

[0066] (DOL of compressive stress layer)

[0067] The DOL of the compressive stress layer 32 of the thin wall portion 30 is smaller than the DOL of the compressive stress layer 22 of the thick wall portion 20. By appropriately securing the breakage resistance of the thick wall portion 20 and making the DOL of the thin wall portion 30 smaller than the DOL of the thick wall portion 20, the bendability starting from the thin wall portion 30 can be appropriately secured, and the number of broken pieces can be reduced even at the time of breakage. The method of measuring the DOL is arbitrary, and for example, the DOL can be measured using a surface stress meter FSM-6000LE manufactured by Kojima Manufacturing Co., Ltd.

[0068] The difference between the DOL of the thick wall portion 20 and the DOL of the thin wall portion 30 is preferably 3 μm to 35 μm, more preferably 5 μm to 30 μm, and further preferably 7 μm to 25 μm. By making the difference in the DOL within this range, the bendability and the breakage resistance can be secured.

[0069] The DOL of the compressive stress layer 22 of the thick wall portion 20 is preferably 15 μm to 50 μm, more preferably 20 μm to 45 μm, and further preferably 25 μm to 40 μm. In addition, the DOL of the compressive stress layer 22 of the thick wall portion 20 preferably satisfies the following formula (1). Note that, when formula (1) is applied to the DOL of the thick wall portion 20, t of formula (1) refers to the thickness t2 of the thick wall portion 20, and CS refers to the surface compressive stress CS of the thick wall portion 20.

[0070] By making the DOL of the thick wall portion 20 within this range, the breakage resistance can be appropriately secured.

[0071]

[0072] The DOL of the compressive stress layer 32 of the thin wall portion 30 is preferably 5 μm to 30 μm, more preferably 7 μm to 25 μm, and further preferably 10 μm to 20 μm.

[0073] When the thickness t3 of the thin wall portion 30 is 0.3 mm or more, the DOL of the compressive stress layer 32 of the thin wall portion 30 preferably satisfies the above-described formula (1). Note that, when formula (1) is applied to the DOL of the thin wall portion 30, t of formula (1) refers to the thickness t3 of the thin wall portion 30, and CS refers to the surface compressive stress CS of the thin wall portion 30.

[0074] When the thickness t3 of the thin wall portion 30 is less than 0.3 mm, the DOL of the compressive stress layer 32 of the thin wall portion 30 preferably satisfies the following formula (2). Note that, t of formula (2) refers to the thickness t3 of the thin wall portion 30, and CS refers to the surface compressive stress CS of the thin wall portion 30.

[0075] By making the DOL of the thin wall portion 30 within this range, the bendability and the breakage resistance can be appropriately ensured.

[0076]

[0077] That is, it is preferable that the DOL (mm) of the compressive stress layer 22 of the thick wall portion 20 satisfy the above-described formula (1), the DOL (mm) of the compressive stress layer 32 of the thin wall portion 30 satisfy the above-described formula (1) when the thickness of the thin wall portion is 0.3 mm or more, and satisfy the above-described formula (2) when the thickness of the thin wall portion is less than 0.3 mm.

[0078] Note that, the DOL of the thick wall portion 20 described above refers to the DOL of the compressive stress layer 22 on the side of the first main surface 20A of the thick wall portion 20. The DOL of the compressive stress layer 22 on the side of the second main surface 20B of the thick wall portion 20 can also be the same as described above.

[0079] Similarly, the DOL of the thin wall portion 30 described above refers to the DOL of the compressive stress layer 32 on the side of the first main surface 30A of the thin wall portion 30. The DOL of the compressive stress layer 32 on the side of the second main surface 30B of the thin wall portion 30 can also be the same as described above.

[0080] However, the difference between the DOL of the compressive stress layer 32 on the side of the first main surface 30A of the thin wall portion 30 and the DOL of the compressive stress layer 32 on the side of the second main surface 30B of the thin wall portion 30 is preferably 5 μm or less, more preferably 3 μm or less, and further preferably 1 μm or less.

[0081] In addition, the DOL of the thick wall portion 20 described above can refer to a measured value of the DOL at the central position of the thick wall portion 20 in the X direction. Similarly, the DOL of the thin wall portion 30 described above can refer to a measured value of the DOL at the central position of the thin wall portion 30 in the X direction.

[0082] That is, the thick wall portion 20 does not need to have the DOL of the entire region reach the value described above. For example, the DOL of a region in the thick wall portion 20 near the thin wall portion 30 (for example, a region within 15 mm in the X1 direction from the boundary position between the thick wall portion 20 and the thin wall portion 30) can be the same value as the DOL of the thin wall portion 30. Likewise, the thin wall portion 30 does not need to have the DOL of the entire region reach the value described above. For example, the DOL of a region in the thin wall portion 30 near the thick wall portion 20 (for example, a region within 15 mm in the X2 direction from the boundary position between the thick wall portion 20 and the thin wall portion 30) can be the same value as the DOL of the thick wall portion 20.

[0083] (compressive stress integral value)

[0084] The compressive stress integral values of the two faces (the first main face 20A and the second main face 20B) of the thick wall portion 20 are each calculated by the following equation (2A). Likewise, the compressive stress integral values of the two faces (the first main face 30A and the second main face 30B) of the thin wall portion 30 are each calculated by the following equation (2A).

[0085] 1 / 2 x (CS x DOL)...(2A)

[0086] That is, for example, the compressive stress integral value of the first main face 30A of the thin wall portion 30 is a value obtained by substituting the surface compressive stress CS of the first main face 30A of the thin wall portion 30 for CS and substituting the DOL on the first main face 30A side of the thin wall portion 30 for DOL in equation (2A).

[0087] The difference between the compressive stress integral value of the compressive stress layer 32 on the first main face 30A side of the thin wall portion 30 and the compressive stress integral value of the compressive stress layer 32 on the second main face 30B side of the thin wall portion 30 is preferably 6000 MPa pm or less, more preferably 2000 MPa pm or less, and further preferably 1000 MPa pm or less. By reducing the difference between the compressive stress integral values of the two faces in this way, warping of the thin wall portion 30 can be suppressed.

[0088] (internal tensile stress CT)

[0089] The internal tensile stress CT of the thin wall portion 30 is higher than the internal tensile stress CT of the thick wall portion 20. By making the internal tensile stress CT of the thin wall portion 30 higher than the internal tensile stress CT of the thick wall portion 20, the breakage resistance of the thick wall portion 20 can be appropriately ensured, and the bendability from the thin wall portion 30 as a starting point can be appropriately ensured, and the number of breakages can be reduced even at the time of breakage.

[0090] The internal tensile stress CT is calculated by the following equation (3).

[0091] CT = [(1 / 2 x CS x DOL) - (1 / 2 x CS x DOL)]...(3)A × DOL A ) + (1 / 2 x CS B × DOL B ) ] / (t - DOL A - DOL B )...(3)

[0092] In formula (3), the surface compressive stress CS of the first main surface of the two main surfaces is set as CS A , the depth (DOL) of the compressive stress layer of the first main surface is set as DOL A , the surface compressive stress CS of the second main surface is set as CS B , and the depth (DOL) of the compressive stress layer of the second main surface is set as DOL B . That is, for example, when the internal tensile stress CT of the thin-walled portion 30 is calculated, 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 respectively substituted into CS A , DOL A , CS B , and DOL B of formula (3). Similarly, when the internal tensile stress CT of the thick-walled portion 20 is calculated, 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 are respectively substituted into CS A , DOL A , CS B , and DOL B of formula (3).

[0093] Further, t of formula (3) means thickness. When formula (3) is applied to the internal tensile stress CT of the thin-walled portion 30, t of formula (3) means 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 of formula (3) means the thickness t2 of the thick-walled portion 20.

[0094] 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 to 125 MPa, more preferably 10 MPa to 80 MPa, and further preferably 15 MPa to 60 MPa. By making the difference in the internal tensile stress CT within this range, the bendability and the breakage resistance can be ensured.

[0095] 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 to 50 MPa, and further preferably 20 MPa to 45 MPa.

[0096] By making the internal tensile stress CT of the thick wall portion 20 fall within this range, the breakage resistance can be appropriately ensured.

[0097] The internal tensile stress CT of the thin wall portion 30 is preferably 25 MPa to 135 MPa, more preferably 30 MPa to 100 MPa, and further preferably 65 MPa to 90 MPa.

[0098] By making the internal tensile stress CT of the thin wall portion 30 fall within this range, the bendability and the breakage resistance can be appropriately ensured.

[0099] Further, the internal tensile stress CT of the thick wall portion 20 described above can refer to the internal tensile stress CT at the central position of the thick wall portion 20 in the X direction. Similarly, the internal tensile stress CT of the thin wall portion 30 described above can refer to the internal tensile stress CT at the central position of the thin wall portion 30 in the X direction.

[0100] That is, the internal tensile stress CT of the thick wall portion 20 need not be the value described above throughout the entire region. For example, the internal tensile stress CT of a region in the thick wall portion 20 near the thin wall portion 30 (for example, a region within 15 mm from the boundary position of the thick wall portion 20 and the thin wall portion 30 in the XI direction) can be the same value as the internal tensile stress CT of the thin wall portion 30. Similarly, the internal tensile stress CT of the thin wall portion 30 need not be the value described above throughout the entire region. For example, the internal tensile stress CT of a region in the thin wall portion 30 near the thick wall portion 20 (for example, a region within 15 mm from the boundary position of the thick wall portion 20 and the thin wall portion 30 in the X2 direction) can be the same value as the internal tensile stress CT of the thick wall portion 20.

[0101] (Material of glass)

[0102] The material of the glass 10 is arbitrary, and for example, soda-lime glass, aluminosilicate glass (SiO2-Al2O3-Na2O glass or SiO2-Al2O3-Li2O-Na2O glass), or the like can be cited. Among them, from the viewpoint of strength, aluminosilicate glass is preferable.

[0103] As the material of the glass 10, for example, a glass material containing 50 to 80% of SiO2, 1 to 20% of Al2O3, 6 to 20% of Na2O, 0 to 11% of K2O, 0 to 15% of MgO, 0 to 6% of CaO, and 0 to 5% of ZrO2in terms of mol% on an oxide basis; and a glass material containing 50 to 80% of SiO2, 2 to 25% of Al2O3, 0.1 to 20% of Li2O, 0.1 to 18% of Na2O, 0 to 10% of K2O, 0 to 15% of MgO, 0 to 5% of CaO, 0 to 5% of P2O5, 0 to 5% of B2O3, 0 to 5% of Y2O3, and 0 to 5% of ZrO2in terms of mol% on an oxide basis can be mentioned.

[0104] In addition, as the material of the glass 10, a chemically strengthened glass using an aluminosilicate glass as a base (for example, "Dragontrail (registered trademark)" manufactured by AGC Inc.) is also preferable.

[0105] (Method for manufacturing glass)

[0106] Next, a method for manufacturing the glass 10 according to the present embodiment will be described.

[0107] The method for manufacturing the glass according to the present embodiment includes the following steps:

[0108] A glass having a thick wall portion with a thickness of 0.5 mm or more and a thin wall portion adjacent to the thick wall portion and having a thickness of 0.15 mm or more and less than 0.5 mm, the first main surface of the thick wall portion being flush with the first main surface of the thin wall portion in a state where the first main surface of the thick wall portion is fixed in contact with a flat surface, is prepared; and

[0109] The glass is chemically strengthened in such a manner that the time for chemically strengthening the thick wall portion is longer than the time for chemically strengthening the thin wall portion, thereby manufacturing a glass in which the DOL of the compressive stress layer of the thin wall portion is smaller than the DOL of the compressive stress layer of the thick wall portion, the internal tensile stress CT of the thin wall portion is higher than the internal tensile stress CT of the thick wall portion, and the surface compressive stress CS of the thin wall portion is 550 MPa or more.

[0110] Figure 5 is a flowchart illustrating the method for manufacturing the glass according to the present embodiment.

[0111] In the present manufacturing method, a glass having a thick wall portion 20 and a thin wall portion 30 is prepared (step S10). The glass in this step is a glass before chemical strengthening is performed on the glass 10 described above. That is, the glass in this step is a glass having a thick wall portion 20 with a thickness t2 in the range described above and a thin wall portion 30 with a thickness t3 in the range described above, and a shape in which the first main surface 20A of the thick wall portion 20 is flush with the first main surface 30A of the thin wall portion 30.

[0112] Note that the method of obtaining the glass having the thick wall portion 20 and the thin wall portion 30 can be arbitrary, and for example, the plate-shaped glass can be thinned. At this time, for example, the second main surface of the portion to be the thick wall portion 20 in the plate-shaped glass can be masked, and the plate-shaped glass can be etched. Thus, the portion to be the thick wall portion 20 is not etched, and the portion not masked is etched to form the thin wall portion 30.

[0113] In addition, for example, the glass having the thick wall portion 20 and the thin wall portion 30 can be obtained by performing grinding processing or laser processing on the plate-shaped glass. At this time, for example, grinding processing or laser processing can be performed on the second main surface of the portion to be the thin wall portion 30 in the plate-shaped glass.

[0114] Next, the glass obtained in step S10 is chemically strengthened in a manner in which the thick wall portion 20 is chemically strengthened for a longer time than the thin wall portion 30, to obtain the glass 10 (step S12).

[0115] The chemical strengthening treatment is performed by a known method. As the molten salt used in the chemical strengthening treatment, for example, an alkali metal nitrate such as potassium nitrate, sodium nitrate, potassium sulfate, sodium sulfate, an alkali metal sulfate, and an alkali metal chloride salt can be given. These molten salts are not limited to be used alone, and a plurality of them can be used in combination. In order to adjust the chemical strengthening characteristics, other salts can be mixed. Thus, in the surface layer of the glass 10, alkali metal ions (Li ions or Na ions) are ion-exchanged (replaced) with other alkali metal ions (Na ions or K ions) having a larger ionic radius than the alkali metal ions in the molten salt, and then cooled to the vicinity of room temperature. By this ion-exchange, a layer (compressive stress layer) in which a compressive stress is generated due to high densification is formed in the surface layer of the glass 10.

[0116] In the present embodiment, the time for which the thin wall portion 30 is chemically strengthened is longer than the time for which the thick wall portion 20 is chemically strengthened. Thus, it is possible to make the DOL of the thin wall portion 30 smaller than the DOL of the thick wall portion 20.

[0117] The method of making the time for which the thick wall portion 20 is chemically strengthened longer than the time for which the thin wall portion 30 is chemically strengthened can employ an arbitrary method.

[0118] For example, the thick wall portion 20 can be first immersed in the molten salt for chemical strengthening alone, and after a prescribed period of time, both the thick wall portion 20 and the thin wall portion 30 (i.e., the entire glass 10) can be immersed in the molten salt.

[0119] In addition, for example, both the thick wall portion 20 and the thin wall portion 30 (i.e., the entire glass 10) can be immersed in the molten salt while the thin wall portion 30 is protected, and after a prescribed period of time, the protection of the thin wall portion 30 is removed and both the thick wall portion 20 and the thin wall portion 30 are immersed in the molten salt. The method of protecting the thin wall portion 30 can be arbitrary, and for example, a method in which the thin wall portion 30 is coated with a masking material that is not impregnated with the molten salt, or the like, can be cited.

[0120] Further, for example, the thick wall portion 20 can be coated with a paste-like molten salt for chemical strengthening, and after a prescribed period of time, the thin wall portion 30 can also be coated with a paste-like molten salt for chemical strengthening.

[0121] (Other Configuration Examples of Glass)

[0122] Next, other configuration examples of the glass 10 will be described.

[0123] (Functional Layer)

[0124] A functional layer can be layered on the first main surface 10A of the glass 10. The functional layer can include any one or more selected from an antiglare layer, an antireflection layer, and a stain-proof layer. Note that when the functional layer includes two or more of the antiglare layer, the antireflection layer, and the stain-proof layer, it is preferable that each layer be layered in the Z direction. The order of layering each layer in the Z direction at this time can be arbitrary, and when the antiglare layer, the antireflection layer, and the stain-proof layer are included, it is preferable that the antiglare layer, the antireflection layer, and the stain-proof layer be layered in that order from the first main surface 10A side of the glass 10.

[0125] The antiglare layer is a layer that imparts antiglare properties to the glass 10. The antiglare layer can have a concave-convex shape. The concave-convex shape can be formed directly on the first main surface 10A of the glass 10, or can be formed by a layer composed of a material different from the glass 10. The surface roughness (root mean square roughness, RMS) of the concave-convex shape is preferably 15 nm to 1000 nm, and more preferably 10 nm to 500 nm. Note that the antiglare layer can be realized by a concave-convex shape imparted by performing an antiglare treatment and an etching treatment on the first main surface 10A of the glass 10. In addition, a coating film in which particles having an arbitrary refractive index are dispersed can be used on the first main surface 10A of the glass 10, or a concave-convex shape can be formed on the main surface of a transparent resin film to be attached, and the antiglare layer can be realized by the concave-convex shape.

[0126] The antireflection layer is a layer for suppressing reflection of light. The antireflection layer brings a reduction in reflectance to the glass 10, and not only reduces the glare caused by the reflection of light, but also improves the visibility of a display device when used for the display device. The configuration of the antireflection layer is not particularly limited as long as it can suppress the reflection of light, and for example, it can be a configuration in which a high-refractive layer having a refractive index of 1.9 or more at a wavelength of 550 nm and a low-refractive layer having a refractive index of 1.6 or less at a wavelength of 550 nm are alternately stacked.

[0127] The stain-proof layer is a layer having a function of making dirt unnoticeable, and can suppress the adhesion of various dirt such as fingerprints, sweat stains, dust, and the like. From the viewpoint of the characteristics of the stain-proof layer, the stain-proof layer is preferably formed on the most surface of the glass 10 on the Z2 side. For example, the stain-proof layer is configured of a fluorine-containing organic compound (a compound having a fluorine-containing organic group) capable of imparting stain-proof properties, water repellency, and oil repellency. As the fluorine-containing organic compound, for example, a fluorine-containing organosilicon compound or the like can be given.

[0128] (Filling material)

[0129] In addition, the filling material can be filled on the second main surface 30B of the thin-walled portion 30. The filling material can be, for example, a cured product of an adhesive (transparent adhesive) such as a thermosetting adhesive, an ultraviolet-curing adhesive, or the like, and can also be a liquid such as water, oil, an organic solvent, a liquid polymer, an ionic liquid, and a mixture thereof. More specifically, propylene glycol, dipropylene glycol, tripropylene glycol, straight-chain silicone oil (dimethyl silicone oil, methylphenyl silicone oil, methyl hydrogen-containing silicone oil, and the like), modified silicone oil, an acrylic polymer, liquid polybutadiene, glycerin cream, a fluorine-based solvent, a fluorine-based resin, acetone, ethanol, xylene, toluene, water, mineral oil, and a mixture thereof can be given.

[0130] (Chamfering)

[0131] In addition, the corner portion (the connecting portion of the main surface and the end surface) of the glass 10 can be chamfered.

[0132] (Configuration having a connecting portion)

[0133] Figure 6 is a schematic cross-sectional view of the glass to which another example of the present embodiment relates. The glass 10 can have a connecting portion 40 connecting the thin-walled portion 30 and the thick-walled portion 20. The connecting portion 40 can be any shape, and for example, as shown in Figure 6 , the connecting portion 40 can have a shape provided between the thin-walled portion 30 and the thick-walled portion 20 in the X direction, and the thickness decreases toward the X2 side, that is, from the side connected to the thick-walled portion 20 to the side connected to the thin-walled portion 30.

[0134] More specifically, in this example, the main surface on the side of the first main surface 10A of the connecting portion 40 is set as the first main surface 40A, and the main surface on the side of the second main surface 10B of the connecting portion 40 is set as the second main surface 40B. That is, the first main surface 40A is a region of the entire region of the first main surface 10A of the glass 10 in which the connecting portion 40 is formed, and the second main surface 40B is a region of the entire region of the second main surface 10B of the glass 10 in which the connecting portion 40 is formed.

[0135] In this case, the first main surface 40A of the connecting portion 40 is flush with the first main surface 20A of the thick wall portion 20 and the first main surface 30A of the thin wall portion 30. In addition, the second main surface 40B of the connecting portion 40 is inclined toward the Z2 side (the first main surface 40A) as facing the X2 direction.

[0136] That is, in a state where the first main surface 10A is fixed to be in contact with a flat surface, the first main surface 40A of the connecting portion 40 is flush with the first main surface 20A of the thick wall portion 20 and the first main surface 30A of the thin wall portion 30, and the thickness of the connecting portion 40 can be smaller as going from the side connected to the thick wall portion 20 to the side connected to the thin wall portion 30.

[0137] The length of the connecting portion 40 in the X direction can be arbitrary, and for example, can be 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 position of the connecting portion 40 and the thick wall portion 20 to the boundary position of the connecting portion 40 and the thin wall portion 30.

[0138] Figure 7 is a schematic cross-sectional view of another example of the glass according to the present embodiment. As shown in Figure 7 the connecting portion 40 can be in a overhanging shape. The overhanging shape refers to a shape in which the first main surface 40A of the connecting portion 40 is flush with the first main surface 20A of the thick wall portion 20 and the first main surface 30A of the thin wall portion 30, and the thickness of the connecting portion 40 is smaller than that of the thin wall portion 30 in at least a part of the region. In other words, for the connecting portion 40 in the overhanging shape, at least a part of the second main surface 40B is recessed toward the Z2 direction (downward) compared to the second main surface 30B of the thin wall portion 30. By providing the connecting portion 40 in the overhanging shape, the bendability can be improved. Figure 7

[0139] That is, the connecting portion 40 can be in an overhanging shape in which, in a state where the first main surface 10A is fixed to be in contact with a flat surface, the first main surface 40A of the connecting portion 40 is flush with the first main surface 20A of the thick wall portion 20 and the first main surface 30A of the thin wall portion 30, and the thickness is smaller than that of the thin wall portion 30 in at least a part of the region.

[0140] ​Note that the chemical tempering of the connecting portion 40 can be arbitrarily set. That is, the surface compressive stress CS, the DOL, and the internal tensile stress CT of the connecting portion 40 can be arbitrary. For example, the surface compressive stress CS, the DOL, and the internal tensile stress CT of the connecting portion 40 can be values between the thin-walled portion 30 and the thick-walled portion 20. Among them, for example, when the connecting portion 40 is in a cantilever shape, the surface compressive stress CS, the DOL, and the internal tensile stress CT of the portion of the connecting portion 40 in which the thickness is smaller than that of the thin-walled portion 30 can be greater than the thin-walled portion 30.

[0141] (Multiple thick-walled portions and thin-walled portions)

[0142] Figure 8 and Figure 9 is a schematic cross-sectional view of another example of the glass according to the present embodiment. In the above-described embodiment, one thick-walled portion 20 and one thin-walled portion 30 are provided in the glass 10, but the present embodiment is not limited thereto. For example, the glass 10 can be provided with multiple thick-walled portions 20 in the X direction, or can be provided with multiple thin-walled portions 30 in the X direction. In this case, the thick-walled portions 20 and the thin-walled portions 30 can be arranged alternately in the X direction. Figure 8 is an example in which two thick-walled portions 20 and one thin-walled portion 30 are provided, and the thick-walled portions 20, the thin-walled portion 30, and the thick-walled portions 20 are arranged in this order in the direction facing X2. In addition, Figure 9 is an example in which three thick-walled portions 20 and two thin-walled portions 30 are provided, and the thick-walled portions 20, the thin-walled portion 30, the thick-walled portions 20, the thin-walled portion 30, and the thick-walled portions 20 are arranged in this order in the direction facing X2.

[0143] Here, a case in which the surface compressive stress CS, the DOL, and the internal tensile stress CT of the thick-walled portion 20 described in the above-described embodiment are defined as satisfying the first chemical tempering condition, and a case in which the surface compressive stress CS, the DOL, and the internal tensile stress CT of the thin-walled portion 30 described in the above-described embodiment are defined as satisfying the second chemical tempering condition.

[0144] In a case in which multiple thin-walled portions 30 are provided, it is preferable that all of the multiple thin-walled portions 30 satisfy the second chemical condition. That is, for example, in the example of Figure 9 it is preferable that both of the two thin-walled portions 30 satisfy the second chemical condition.

[0145] In addition, in a case in which multiple thick-walled portions 20 are provided, it is preferable that all of the multiple thick-walled portions 20 satisfy the first chemical tempering condition. That is, for example, in the example of Figure 8 it is preferable that both of the two thick-walled portions 20 satisfy the first chemical tempering condition.

[0146] However, it is not limited thereto, and only a part of the plurality of thick wall portions 20 can satisfy the first chemical tempering condition. In this case, another part of the plurality of thick wall portions 20 can not satisfy the first chemical tempering condition and satisfy the second chemical tempering condition. The part of the thick wall portions 20 that satisfies the first chemical tempering condition can be any one of the plurality of thick wall portions 20, for example, can be the one closest to the X1 side or the one closest to the X2 side. That is, for example, in the example of Figure 9 the first chemical tempering condition, and another part of the thick wall portions 20 satisfies the second chemical tempering condition. Likewise, only a part of the plurality of thin wall portions 30 can satisfy the second chemical tempering condition. In this case, another part of the plurality of thin wall portions 30 can not satisfy the second chemical tempering condition and satisfy the first chemical tempering condition. The part of the thin wall portions 30 that satisfies the second chemical tempering condition can be any one of the plurality of thin wall portions 30, for example, can be the one closest to the X1 side or the one closest to the X2 side. That is, for example, in the example of Figure 9 the first chemical tempering condition, and another part of the thick wall portions 20 satisfies the second chemical tempering condition. Likewise, only a part of the plurality of thin wall portions 30 can satisfy the second chemical tempering condition. In this case, another part of the plurality of thin wall portions 30 can not satisfy the second chemical tempering condition and satisfy the first chemical tempering condition. The part of the thin wall portions 30 that satisfies the second chemical tempering condition can be any one of the plurality of thin wall portions 30, for example, can be the one closest to the X1 side or the one closest to the X2 side. That is, for example, in the example of

[0147] (EFFECT)

[0148] As described above, the glass 10 according to the first aspect of the present disclosure has a thick wall portion 20 having a thickness of 0.5 mm or more, and a thin wall portion 30 that is adjacent to the thick wall portion 20 and has a thickness of 0.15 mm or more and less than 0.5 mm. In a state where the first main surface 10A is fixed to be in contact with a flat surface, the first main surface 20A of the thick wall portion 20 is flush with the first main surface 30A of the thin wall portion 30. The internal tensile stress CT of the thin wall portion 30 is higher than the internal tensile stress CT of the thick wall portion 20, the DOL of the compressive stress layer 32 of the thin wall portion 30 is smaller than the DOL of the compressive stress layer 22 of the thick wall portion 20, and the surface compressive stress CS of the thin wall portion 30 is 550 MPa or more.

[0149] The glass 10 according to the present disclosure can be appropriately bent by having the thick wall portion 20 and the thin wall portion 30. On the other hand, when chemically tempering a glass provided with a thick wall portion and a thin wall portion and capable of being bent, since the thicknesses of the thick wall portion and the thin wall portion are different, chemical tempering cannot be appropriately performed, and the bending property, the breakage resistance, or the number of pieces at the time of breakage can decrease. In contrast, in the present embodiment, by making the internal tensile stress CT of the thin wall portion 30 higher than the internal tensile stress CT of the thick wall portion 20, making the DOL of the compressive stress layer 32 of the thin wall portion 30 smaller than the DOL of the compressive stress layer 22 of the thick wall portion 20, and making the surface compressive stress CS of the thin wall portion 30 550 MPa or more, the bending property and the breakage resistance can be ensured, and the number of pieces at the time of breakage can be reduced.

[0150] The glass 10 according to the second aspect of the present disclosure is the glass 10 according to the first aspect, and a difference between a compressive stress integral value of the compressive stress layer 32 on the first main surface 30A side of the thin wall portion 30 and a compressive stress integral value of the compressive stress layer 32 on the second main surface 30B side of the thin wall portion 30 is preferably 6000 MPa pm or less. Thereby, warping of the thin wall portion 30 can be suppressed.

[0151] The glass 10 according to the third aspect of the present disclosure is the glass 10 according to the first aspect or the second aspect, and a thickness of the thick wall portion 20 is preferably 0.5 mm or more and less than 5.0 mm. By making the thickness of the thick wall portion 20 in this range, lightness and breakage resistance can be ensured, and the number of pieces at the time of breakage can be reduced.

[0152] The glass 10 according to the fourth aspect of the present disclosure is the glass 10 according to any one of the first aspect to the third aspect, and a difference between the surface compressive stress CS of the thin wall portion 30 and the surface compressive stress CS of the thick wall portion 20 is preferably 100 MPa or less. By making the difference in the surface compressive stress CS in this range, the process can be shortened, and the cost can be further reduced.

[0153] The glass 10 according to the fifth aspect of the present disclosure is the glass 10 according to any one of the first aspect to the fourth aspect, and preferably, a DOL (mm) of the compressive stress layer of the thick wall portion 20 satisfies the above-described formula (1), a DOL (mm) of the compressive stress layer of the thin wall portion satisfies the above-described formula (1) when the thickness of the thin wall portion 30 is 0.3 mm or more, and satisfies the above-described formula (2) when the thickness of the thin wall portion 30 is less than 0.3 mm. By making the DOL in this range, the number of pieces at the time of breakage can be reduced.

[0154] The glass 10 according to the sixth aspect of the present disclosure is the glass 10 according to any one of the first aspect to the fifth aspect, and preferably has a connecting portion 40 that connects the thin wall portion 30 and the thick wall portion 20. By having the connecting portion 40, the thickness can be suppressed from changing sharply, and breakage can be more appropriately suppressed.

[0155] The glass 10 according to the seventh aspect of the present disclosure is the glass 10 according to the sixth aspect, and preferably, in a state where the first main surface 10A is fixed in contact with a flat surface, the first main surface 40A of the connecting portion 40 is flush with the first main surface 20A of the thick wall portion 20 and the first main surface 30A of the thin wall portion 30, and the thickness of the connecting portion 40 decreases from the side connected to the thick wall portion 20 to the side connected to the thin wall portion 30. By having such a connecting portion 40, the thickness can be suppressed from changing sharply, and breakage can be more appropriately suppressed.

[0156] The glass 10 according to the 8th aspect of the present disclosure is the glass 10 according to the 6th aspect of the present disclosure, and preferably the connecting portion 40 has a shape of overhang in which the first main surface 40A of the connecting portion 40 is flush with the first main surface 20A of the thick wall portion 20 and the first main surface 30A of the thin wall portion 30, and the thickness is smaller than that of the thin wall portion 30 in at least a part of the region, in a state where the first main surface 10A is fixed to be in contact with a flat surface. With the connecting portion 40 having such a shape of overhang, bending can be appropriately performed.

[0157] The display device 1 according to the 9th aspect of the present disclosure has the display 12 and the glass 10 according to any one of the 1st to 8th aspects of the present disclosure. According to the present disclosure, it is possible to ensure bendability and breakage resistance, and to reduce the number of fragments at the time of breakage.

[0158] The glass manufacturing method according to the 10th aspect of the present disclosure includes the steps of:

[0159] A glass having a thick wall portion 20 with a thickness of 0.5 mm or more, and a thin wall portion 30 adjacent to the thick wall portion 20 and having a thickness of 0.15 mm or more and less than 0.5 mm, in which the first main surface 20A of the thick wall portion 20 is flush with the first main surface 30A of the thin wall portion 30 in a state where the first main surface 10A is fixed to be in contact with a flat surface, and the glass is chemically strengthened in such a manner that the time for chemically strengthening the thick wall portion 20 is longer than the time for chemically strengthening the thin wall portion 30, thereby manufacturing a glass in which the DOL of the compressive stress layer 32 of the thin wall portion 30 is smaller than the DOL of the compressive stress layer 22 of the thick wall portion 20, the internal tensile stress CT of the thin wall portion 30 is higher than the internal tensile stress CT of the thick wall portion 20, and the surface compressive stress CS of the thin wall portion 30 is 550 MPa or more.

[0160] According to the present disclosure, it is possible to manufacture a glass 10 that ensures bendability and breakage resistance, and has a small number of fragments at the time of breakage.

[0161] (Examples)

[0162] Next, examples will be described. Tables 1 and 2 are tables showing the glass and the evaluation results in each example. Note that the embodiments can be changed as long as the effects of the present disclosure are exerted.

[0163]

[0164]

[0165] (Example 1)

[0166] In Example 1, a glass substrate (Dragontrail® manufactured by AGC Inc., 120 mm x 60 mm x 1.1 mm (length x width x thickness)) was prepared. TM- Pro, hereinafter also referred to as DT-Pro). After adhering an acid-resistant UV release film to the entire surface of one side of the glass substrate and a region of 20 mm from the end surface in the vertical direction of the other side, the surface of the region between 20 mm and 120 mm from the end surface was immersed in a mixed solution of hydrofluoric acid and hydrochloric acid until the thickness reached 0.3 mm, and thinning was performed by this etching method. Thereafter, the film surface was subjected to UV irradiation, and the film was released from the glass, obtaining a glass substrate having regions of different thicknesses.

[0167] Thick wall portion 20 mm x 60 mm x 1.1 mm (length x width x thickness)

[0168] Thin wall portion 100 mm x 60 mm x 0.3 mm (length x width x thickness)

[0169] A KNO3 molten salt bath at 450°C was further prepared, and the region within 20 mm from the end surface of the glass substrate was first immersed in the molten salt for 30 minutes. Thereafter, the entire surface of the glass substrate was immersed in the molten salt for 1 hour, thereby obtaining the glass of Example 1.

[0170] The internal tensile stress CT, the DOL of the compressive stress layer, and the surface compressive stress CS of the thick wall portion and the thin wall portion of the glass of Example 1 were measured. The measurement methods thereof were the methods described in the above-described embodiments. The measurement results thereof are shown in Table 1.

[0171] In addition, based on the thickness of the thin wall portion and the surface compressive stress CS, the upper limit DOL of the thin wall portion was calculated. The upper limit DOL is the value on the right side of Formula (1) or Formula (2).

[0172] (Examples 2, 3, 5 to Example 12)

[0173] In Examples 2, 3, 5 to Example 12, at least one of the thickness of the thin wall 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, and otherwise, a glass having the same properties as Example 1 was obtained. In Examples 2, 3, 5 to Example 12, a mixed molten salt bath of KNO3 or NaNO3 at 350°C to 450°C was used, and immersion treatment was performed for 0.5 hours to 1.5 hours. Also, the thick wall portion was adjusted so as to have a CS and DOL equivalent to chemical strengthening at 450°C for 1.5 hours.

[0174] (Evaluation)

[0175] In the evaluation, the bendability, the breakage resistance, and the number of fragments at the time of breakage were evaluated.

[0176] (Bendability)

[0177] Figure 10is a schematic view of an evaluation method of the bendability. In the evaluation of the bendability, the 2nd main surface 20B of the thick wall portion 20 of the glass 10 and the 2nd main surface 30B of the thin wall portion 30 are respectively arranged on steel-made plates, the distance between the plates is reduced, and the glass 10 is bent from the position 30P, which is 20 mm away from the boundary position between the thick wall portion 20 and the thin wall portion 30, as a starting point. Then, based on the distance between the plates at the time of breakage of the glass 10, the bend R (radius of curvature) of the glass 10 at the time of breakage is calculated. The calculation result of the bend R is shown in Table 1.

[0178] In the evaluation of the bendability, the case where the bend R is less than 15 mm is recorded as excellent, the case where the bend R is 15 mm to 20 mm is recorded as good, and the case where the bend R is more than 20 mm is recorded as unqualified.

[0179] (Breakage)

[0180] In the evaluation of the breakage, the BOR strength F (N) is measured by a ball on ring (BOR) test. In the ball on ring test, the glass is arranged on a ring made of stainless steel having a diameter of 30 mm and a circular arc of a radius of curvature of 2.5 mm of the contact portion, a load is applied to a ball made of steel having a diameter of 10 mm toward the center of the ring in a state where the glass contacts the ball under a static load condition. Then, the BOR strength F is calculated based on the load at the time of breakage of the glass. The calculation result of the BOR strength F is shown in Table 1.

[0181] In the evaluation of the BOR strength F, the case where the BOR strength F is higher than 300 N is recorded as excellent, the case where the BOR strength F is 200 N to 300 N is recorded as good, and the case where the BOR strength F is less than 200 N is recorded as unqualified.

[0182] (Breakage number)

[0183] In the evaluation of the breakage number, a pressure head is pressed in a perpendicular manner to the surface of the glass in the center of the thin wall portion of the glass under a static load condition by using a press-in testing machine (manufactured by Shimadzu Corporation, EZ-X). The pressure head installed in the press-in testing machine uses an acute pressure head having a face angle of 60°, and is pressed in such a manner that a load of 1.0 kgf is applied to the surface of the glass at a speed of 60 μm / s, is held for 15 seconds in a state where the load is reached, and is then withdrawn, and the glass after 15 seconds is observed. Thus, the number of fragments of the broken glass (breakage number) is measured. The measurement result of the breakage number is shown in Table 1.

[0184] In the evaluation of the breakage number, the case where the breakage number is less than 10 is recorded as good, and the case where the breakage number is 10 or more is recorded as unqualified.

[0185] (Evaluation result)

[0186] As shown in Table 1, the bending property, breakage resistance, and the number of broken pieces of the glasses of Examples 1, 3, 5 to 7, which are examples, were all excellent or good, the bending property and the breakage resistance could be ensured, and the number of broken pieces at the time of breakage could be reduced.

[0187] On the other hand, at least one of the bending property, breakage resistance, and the number of broken pieces of the glasses of Examples 8 to 12, which are comparative examples, was not qualified, the bending property and the breakage resistance could not be ensured, and the number of broken pieces at the time of breakage could not be reduced. For example, in Example 8, the surface compressive stress CS of the thin wall portion was less than 550 MPa, the bending property and the breakage resistance could not be ensured. In Example 9, the surface compressive stress CS of the thin wall portion was less than 550 MPa, the internal tensile stress CT of the thin wall portion was lower than the internal tensile stress CT of the thick wall portion, in Example 10, the thickness of the thin wall portion was thick, the bending property could not be ensured. In Example 11, the thickness of the thin wall portion was thin, the breakage resistance and the number of broken pieces could not be ensured. In Example 12, the DOL of the compressive stress layer of the thin wall portion was greater than the DOL of the compressive stress layer of the thick wall portion, the number of broken pieces could not be ensured.

[0188] (Alternative Evaluation)

[0189] As an alternative evaluation, the warpage of the glasses of Examples 13 to 15 was evaluated.

[0190] (Example 13)

[0191] In Example 13, a glass substrate (DT-Pro manufactured by AGC Inc.) of 50 mm x 50 mm x 0.7 mm (length x width x thickness) was prepared.

[0192] As chemical strengthening, a molten salt bath of KNO3 at 450°C was prepared, and the glass substrate was entirely immersed in the molten salt for 1 hour. Next, after an acid-resistant UV release film was attached to the entire surface of one face of the glass substrate and a region of 20 mm from the end face in the vertical direction of the other face, the face of the region at a distance of 20 mm to 50 mm from the end face was shaken and immersed in a mixed solution of hydrofluoric acid and hydrochloric acid until the thickness reached 0.4 mm, and thinning was performed by such etching. Thereafter, the film surface was subjected to UV irradiation, and the film was peeled from the glass, and a glass substrate having regions of different thicknesses was obtained.

[0193] The thick wall portion became 50 mm x 20 mm x 0.7 mm (length x width x thickness), and the thin wall portion became 50 mm x 30 mm x 0.4 mm (length x width x thickness).

[0194] (Example 14)

[0195] In Example 14, a glass substrate (DT-Pro manufactured by AGC Inc.) of 50 mm x 50 mm x 0.7 mm (length x width x thickness) was prepared.

[0196] As the first chemical tempering, a molten salt bath of KNO3 at 450°C was prepared, and the glass substrate was entirely immersed in the molten salt for 0.5 hours. Next, after attaching an acid-resistant UV release film to the entire surface of one face of the glass substrate and a region 20 mm from the end face in the vertical direction of the other face, the face of the region between 20 mm and 50 mm from the end face was shaken and immersed in a mixed solution of hydrofluoric acid and hydrochloric acid until the thickness reached 0.4 mm, and thinning was performed by this etching method. Thereafter, the film surface was subjected to UV irradiation, and the film was peeled from the glass, and a glass substrate having regions of different thicknesses was obtained. Further, the glass substrate was entirely immersed in the molten salt for 0.5 hours, and the glass of Example 14 was obtained.

[0197] The thick wall portion became 50 mm x 20 mm x 0.7 mm (length x width x thickness), and the thin wall portion became 50 mm x 30 mm x 0.4 mm (length x width x thickness).

[0198] (Example 15)

[0199] In Example 15, a glass substrate (DT-Pro manufactured by AGC Inc.) of 50 mm x 50 mm x 0.7 mm (length x width x thickness) was prepared.

[0200] After attaching an acid-resistant UV release film to the entire surface of one face of the glass substrate and a region 20 mm from the end face in the vertical direction of the other face, the face of the region between 20 mm and 50 mm from the end face was shaken and immersed in a mixed solution of hydrofluoric acid and hydrochloric acid until the thickness reached 0.4 mm, and thinning was performed by this etching method. Thereafter, the film surface was subjected to UV irradiation, and the film was peeled from the glass, and a glass substrate having regions of different thicknesses was obtained.

[0201] Next, as the first chemical tempering, a molten salt bath of KNO3 at 450°C was prepared, and only the inner thick wall portion of the glass substrate was immersed in the molten salt for 0.5 hours. Then, the glass substrate was further entirely immersed in the molten salt for 0.5 hours.

[0202] The thick wall portion became 50 mm x 20 mm x 0.7 mm (length x width x thickness), and the thin wall portion became 50 mm x 30 mm x 0.4 mm (length x width x thickness).

[0203] The DOL and the surface compressive stress CS of the compressive stress layer were measured for the first main face and the second main face of the thin wall portion of the glass of Examples 13 to 15. The measurement method thereof was the method described in the above-described embodiment. In addition, the compressive stress integral values of the first main face and the second main face were calculated using formula (2A) of the present embodiment, and the difference between the compressive stress integral value of the first main face and the compressive stress integral value of the second main face was calculated. The measurement results thereof are shown in Table 2.

[0204] (warping)

[0205] Figure 11 is a schematic view of evaluation of warping. As shown in Figure 11 , in the evaluation of warping, the length L of the thin wall portion in the direction parallel to the first main surface 10A and the distance from the flat surface to the front end of the thin wall portion, that is, the warping amount d are measured in a state where the first main surface 10A of the glass is pressed against the flat surface ST. Then, the ratio (d / L) of the warping amount d to the length L is calculated as the warping rate. The calculation result of the warping rate is shown in Table 2.

[0206] As shown in Table 2, it is found that in Example 15, the difference in the compressive stress integral value between the first main surface and the second main surface is 6000 MPa·µm or less, and the warping rate can be reduced, and warping can be suppressed.

[0207] The above describes the embodiment of the present application, but the embodiment of the present application is not limited to the content of the embodiment. In addition, the above-described constituent elements include those which are easily conceived by those skilled in the art, those which are substantially the same, and those in the range of so-called equivalents. Furthermore, the above-described constituent elements can be appropriately combined. In addition, various omissions, substitutions, or changes of the constituent elements can be made within the scope of the gist of the above-described embodiment.

[0208] Industrial applicability

[0209] According to the present application, it is possible to provide a glass having sufficient bendability and breakage resistance, and capable of reducing the number of breakage, a display device, and a manufacturing method of the glass.

[0210] The present application has been described in detail with reference to specific embodiments, but it is obvious for those skilled in the art that various changes, modifications can be made without departing from the spirit and scope of the present application.

[0211] This application is based on Japanese Patent Application (JP 2023-150100) filed on September 15, 2023, the content of which is incorporated herein by reference in its entirety.

[0212] Explanation of symbols

[0213] 1 display device

[0214] 10 glass

[0215] 12 display

[0216] 10A, 20A, 30A, 40A first main surface

[0217] 10B, 20B, 30B, 40B second main surface

[0218] 14 base

[0219] 20 thick wall portion

[0220] 22 compressive stress layer

[0221] 30 thin wall portion

[0222] 32 compressive stress layer

[0223] 40 connecting portion

Claims

1. A glass having: a thick wall portion having a thickness of 0.5 mm or more, and a thin wall portion adjoining the thick wall 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 wall portion is flush with a first main surface of the thin wall portion in a state where the first main surface of the glass is fixed in contact with a flat surface, the internal tensile stress CT of the thin wall portion is higher than the internal tensile stress CT of the thick wall portion, the DOL of the compressive stress layer of the thin wall portion is smaller than the DOL of the compressive stress layer of the thick wall portion, and the surface compressive stress CS of the thin wall portion is 550 MPa or more. wherein the difference between the compressive stress integral value of the compressive stress layer on the first main surface side of the thin wall portion and the compressive stress integral value of the compressive stress layer on the second main surface side of the thin wall portion is 6000 MPa pm or less, the thickness of the thick wall portion is 0.5 mm or more and less than 5.0 mm, the difference between the surface compressive stress CS of the thin wall portion and the surface compressive stress CS of the thick wall portion is 100 MPa or less, the DOL of the compressive stress layer of the thick wall portion satisfies formula (1), the DOL of the compressive stress layer of the thin wall portion satisfies formula (1) when the thickness of the thin wall portion is 0.3 mm or more and satisfies formula (2) when the thickness of the thin wall portion is less than 0.3 mm, wherein t represents the thickness of the thick wall portion or the thin wall portion, the unit of thickness is mm, and the unit of DOL is mm.

6. The glass according to claim 1 or 2, having a connecting portion connecting the thin wall portion and the thick wall portion, wherein a first main surface of the connecting portion is flush with the first main surface of the thick wall portion and the first main surface of the thin wall portion in a state where the first main surface of the glass is fixed in contact with a flat surface, and the thickness of the connecting portion decreases from the side connected to the thick wall portion to the side connected to the thin wall portion.

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

10. A method for producing a glass, comprising the steps of: preparing a glass having a thick wall portion having a thickness of 0.5 mm or more and a thin wall portion adjoining the thick wall 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 wall portion is flush with a first main surface of the thin wall portion in a state where the first main surface of the glass is fixed in contact with a flat surface; and chemically strengthening the glass in such a manner that the time for chemically strengthening the thick wall portion is longer than the time for chemically strengthening the thin wall portion, thereby producing a glass in which the DOL of the compressive stress layer of the thin wall portion is smaller than the DOL of the compressive stress layer of the thick wall portion, the internal tensile stress CT of the thin wall portion is higher than the internal tensile stress CT of the thick wall portion, and the surface compressive stress CS of the thin wall portion is 550 MPa or more. ​ ​ ​ 2. The glass of claim 1, wherein, ​ 3. The glass according to claim 1 or 2, wherein, ​ 4. The glass of claim 1 or 2, wherein, ​ 5. The glass of claim 1 or 2, wherein, ​ ​ ​ ​ 7. The glass of claim 6, wherein, ​ ​ 8. The glass of claim 6, wherein, ​ ​ ​ ​ ​

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