glass matrix

Abstract

The present invention provides a glass substrate in which chamfering of a bend portion is suppressed. The glass substrate of the present invention has: a first main surface; a second main surface, which is a main surface on the opposite side from the first main surface; an end surface, which is interposed between the first main surface and the second main surface; a first boundary surface, which connects the first main surface and the end surface; a second boundary surface, which connects the second main surface and the end surface; and a bend portion, which is formed by bending the first main surface into a concave shape and bending the second main surface into a convex shape. The bend portion includes a portion in which a distance D1 in a tangential direction of the end surface of the glass substrate with respect to the first main surface from the end surface to the first main surface is longer than a distance D2 in a tangential direction of the end surface of the glass substrate with respect to the second main surface from the end surface to the second main surface, and a difference between the distance D1 and the distance D2 is 50 μm or more.

Description

[0001] This application is a divisional application of the parent application filed by AGC Corporation, entitled "Glass Substrate", filed on June 15, 2020, with application number "202080042950.4". Technical Field

[0002] This invention relates to glass substrates. Background Technology

[0003] Cars and other vehicles are equipped with in-vehicle display devices such as vehicle navigation systems.

[0004] In vehicle display devices, from the viewpoint of protecting the display panel, glass protective components (protective glass) are used (see, for example, Patent Documents 1-2).

[0005] Patent Document 1: International Publication No. 2016 / 027812

[0006] Patent Document 2: International Publication No. 2017 / 208995

[0007] For convenience, the main surface of one of the two main surfaces of the glass substrate used as protective glass will be referred to as the "first main surface", and the main surface opposite to the first main surface will be referred to as the "second main surface".

[0008] The first main surface is the side for the driver or other user (hereinafter referred to as "user") who uses the in-vehicle display device. The second main surface is the side for the display panel.

[0009] There are cases where a frame-shaped printing section is provided on the outer edge of the second main surface (see Patent Document 1). The printing section is hidden from wiring and other components around the display surface (display area) of the display panel, so that the user cannot see it visually from the first main surface side.

[0010] However, typically, a so-called chamfer is formed at the end of the glass substrate (see Patent Document 2). No printing portion is provided on the surface of the chamfer.

[0011] Therefore, the light emitted from the second main surface shines through near the chamfer, resulting in a situation where the user on the first main surface experiences "glare from the chamfer." This will be referred to as "chamfer glare" below. If chamfer glare occurs, it may impede driving, for example, if the user is a driver.

[0012] In recent years, there have been cases where a portion of the protective glass is bent according to the shape of the vehicle display device, etc. That is, there are cases where the glass substrate used as protective glass has a bent portion in addition to a flat portion (unbent portion). In the bent portion, for example, the first main surface is bent into a concave shape, and the second main surface is bent into a convex shape.

[0013] Users typically observe the protective glass, i.e., the glass substrate, from a position opposite to the flat portion of the glass substrate. In this case, even if no light emission is produced at the chamfered portion on the flat portion, there is a possibility that light emission will occur at the chamfered portion, which has a different shape from the flat portion. Summary of the Invention

[0014] The present invention was made in view of the above points, and its object is to provide a glass substrate that can suppress luminescence of the chamfered portion of the buckling portion.

[0015] The inventors conducted in-depth research and discovered that the above-mentioned objectives could be achieved by adopting the following structure, thus completing the present invention.

[0016] That is, the present invention provides the following [1] to

[10] .

[0017] [1] A glass substrate comprising: a first main surface; a second main surface, which is a main surface opposite to the first main surface; an end face sandwiched between the first main surface and the second main surface; a first interface connecting the first main surface and the end face; a second interface connecting the second main surface and the end face; and a buckling portion formed by buckling the first main surface into a concave shape and the second main surface into a convex shape, wherein the buckling portion includes a portion in which the distance D1 from the end face to the first main surface in the tangential direction relative to the first main surface is longer than the distance D2 from the end face to the second main surface in the tangential direction relative to the second main surface, and the difference between the distance D1 and the distance D2 is 50 μm or more.

[0018] [2] According to the glass substrate described in [1] above, a printed portion is provided on the second main surface at the buckled portion, and the distance D3 from the printed portion to the second interface from the end face of the glass substrate in the tangential direction relative to the second main surface is 150 μm or less.

[0019] [3] According to the glass substrate described in [1] or [2] above, in addition to having the buckled portion, the glass substrate also has a flat portion where the first main surface and the second main surface are planar.

[0020] [4] According to the glass substrate described in [3] above, in the flat portion, the distance D1 is the same as the distance D2.

[0021] [5] The glass substrate according to any one of [1] to [4] above has a functional layer on the buckled portion, on the first main surface and on the first interface.

[0022] [6] In the glass substrate according to any one of [1] to [5] above, the distance D1 in the buckling portion is 250 μm or more.

[0023] [7] According to any one of [1] to [6] above, in the buckled portion, the ratio of the distance D1 to the length L1 of the first main surface is 0.250% or more. Wherein, the length L1 is the length along the extension line of the distance D1.

[0024] [8] According to any one of [1] to [7] above, the first interface and the second interface are planar.

[0025] [9] The glass substrate described in any one of [1] to [8] above is used as a protective glass for a display device.

[0026]

[10] Based on the glass substrate described in [9] above, the above display device is an in-vehicle display device.

[0027] According to the present invention, a glass substrate capable of suppressing luminescence from the chamfered portion of the buckled portion can be provided. Attached Figure Description

[0028] Figure 1 This is a top view showing the glass substrate.

[0029] Figure 2 yes Figure 1 The A-A line sectional view is a sectional view of the buckling portion of the glass matrix.

[0030] Figure 3 It is a cross-sectional view showing the grinding of a glass plate using a grinding wheel. Detailed Implementation

[0031] The following is based on Figures 1-3 The preferred embodiments of the present invention will be described below.

[0032] However, the present invention is not limited to the following embodiments. Various modifications and substitutions can be made to the following embodiments without departing from the spirit of the present invention.

[0033] [Glass substrate]

[0034] First, based on Figure 1 as well as Figure 2 Let's explain glass substrate 1.

[0035] Figure 1 This is a top view showing the glass substrate 1. The following explanation will use the case where the glass substrate 1 is used as a protective glass for an in-vehicle display device (not shown) as an example. However, the glass substrate 1 can also be used as a protective glass for display devices other than in-vehicle display devices.

[0036] <First Main Face and Second Main Face>

[0037] like Figure 1 As shown, the glass substrate 1 is a plate-shaped glass having a pair of main surfaces, including a first main surface 2 and a second main surface 3 opposite to the first main surface 2. Furthermore, in Figure 1 The illustrations of the printing section 7 and the functional layer 8, which will be described later, are omitted.

[0038] The first main surface 2 is the main surface on the side of the driver or other user (hereinafter referred to as "user") using the vehicle display device. The second main surface 3 is the main surface on the side of the display panel (not shown) of the vehicle display device.

[0039] <Plain parts and curved parts>

[0040] like Figure 1 As shown, at least a portion of the glass substrate 1 buckles. That is, the glass substrate 1 has a flat portion 11 and a buckled portion 12.

[0041] In the flat portion 11, the first main surface 2 and the second main surface 3 are planes.

[0042] In the buckling portion 12, the first main surface 2 is buckled (bent) in a concave shape, while the other second main surface 3 is buckled (bent) in a convex shape.

[0043] The radius of curvature of the buckling portion 12 is, for example, 10 mm or more and 1000 mm or less, preferably 20 mm or more and 800 mm or less, and more preferably 30 mm or more and 600 mm or less.

[0044] <First interface, second interface, and end face>

[0045] Figure 2 yes Figure 1 The A-A line sectional view is a sectional view of the buckled portion 12 of the glass substrate 1.

[0046] like Figure 2 As shown, the glass substrate 1 has an end face 4 sandwiched between the first main surface 2 and the second main surface 3.

[0047] Furthermore, the buckled portion 12 of the glass substrate 1 has a first interface 5 connected to the first main surface 2 and the end surface 4, and a second interface 6 connected to the second main surface 3 and the end surface 4.

[0048] exist Figure 2In the diagram, end face 4, first interface 5, and second interface 6 are shown as planes, but the shape of each face is not limited to a plane; for example, it can also be a curved surface that is bent into a convex shape. In addition, end face 4 can also be a shape without a plane, such as an R-shaped chamfer. In this case, "end face" is referred to as "top".

[0049] Considering the excellent durability of the functional layer 8 described later, the surface roughness Sa (arithmetic mean height) of the first interface 5 is preferably 0.02 μm or more, more preferably 0.05 μm or more, and even more preferably 0.1 μm or more. The upper limit is not particularly limited, for example, it is 1 μm or less, and preferably 0.5 μm or less.

[0050] The surface roughness Sa of the second interface 6 is not particularly limited and can be the same as the surface roughness Sa of the first interface 5.

[0051] Surface roughness Sa is measured according to ISO 25178.

[0052] Hereinafter, the first interface 5 and the second interface 6 at the buckled portion 12 of the glass substrate 1 are referred to together as the "bevel portion".

[0053] Furthermore, it is preferable to have a flat portion 11 in the glass substrate 1 (refer to...) Figure 1 It also forms the first sub-interface 5 and the second sub-interface 6.

[0054] Printing Department

[0055] like Figure 2 As shown, a printing section 7 made of black ink or the like is provided on the second main surface 3. The printing section 7 is a component arranged in a frame shape on the outer edge of the second main surface 3, and is formed, for example, using a screen printing device or an inkjet device.

[0056] As described above, a display panel is disposed on the second main surface 3 side of the glass substrate 1. The printing section 7 conceals the wiring and other wiring disposed around the display surface (display area) of the display panel, making it invisible to the user from the first main surface 2 side.

[0057] However, as Figure 2 As shown, in most cases, the printing part 7 is not provided on the second interface 6, which is the chamfered part of the glass substrate 1.

[0058] Therefore, the light emitted from the second main surface 3 side of the glass substrate 1 is transmitted near the chamfer (the second interface 6 and the first interface 5), resulting in a situation where a user located on the first main surface 2 side of the glass substrate 1 experiences "glare from the chamfer." That is, there is a situation where light is emitted from the chamfer.

[0059] The chamfered part emits light, for example, in the following situations.

[0060] That is, sunlight enters the vehicle display device (not shown) from the first main surface 2 side of the glass substrate 1, passes through or is reflected by the housing (not shown) disposed on the second main surface 3 side near the chamfered portion (first interface 5 and second interface 6) of the glass substrate 1. The reflected light passes through from the second main surface 3 side to the first main surface 2 side near the chamfered portion (second interface 6 and first interface 5) of the glass substrate 1. This is the situation described above.

[0061] The boundary between the first interface 5 and the first main surface 2 is often an edge (hereinafter also referred to as "edge portion"). When reflected light passes through the chamfered portion, especially the edge portion, the light is scattered at the edge portion, and some light may enter the eyes. In this case, the edge portion on the side of the first main surface 2 appears to be luminous, and sometimes the driver feels dazzled.

[0062] Users typically start from position P (refer to) opposite the flat portion 11. Figure 1 ) Observe the protective glass, i.e., the glass substrate 1. At this time, even if the chamfered portion does not emit light in the flat portion 11, there is a situation where the chamfered portion 12, which has a different shape from the flat portion 11, emits light in the chamfered portion.

[0063] <Distance D1 and distance D2>

[0064] Therefore, as Figure 2 As shown, in this embodiment, the buckling portion 12 of the glass substrate 1 includes a portion in which the distance D1 from the end face 4 to the first main face 2 in the tangential direction (i.e., the extension direction of the buckling portion 12) of the end face 4 of the glass substrate 1 relative to the first main face 2 is longer than the distance D2 from the end face 4 to the second main face 3 in the tangential direction (the extension direction of the buckling portion 12) of the end face 4 of the glass substrate 1 relative to the second main face 3, and the difference between the distance D1 and the distance D2 is 50 μm or more (hereinafter, for convenience, it is referred to as the "specific portion").

[0065] Therefore, compared to the case where distances D2 and D1 are the same throughout the buckled portion 12, the printed portion 7 is positioned closer to the end face 4. As a result, the opposite side of the first interface 5 (the side of the second main surface 3) is largely covered. In particular, the ridge portion of the first main surface 2 side is covered by the printed portion 7 when viewed from above the glass substrate 1. In this way, light from the second main surface 3 side can be suppressed from passing through the chamfered portion (the second interface 6 and the first interface 5), especially at the ridge portion. That is, light emission from the chamfered portion can be suppressed.

[0066] The buckling portion 12 may also include portions other than the specific portions mentioned above (e.g., portions where the difference between distance D1 and distance D2 is not greater than 50 μm).

[0067] For the purpose of further suppressing the emission of light from the chamfered portion of the buckled portion 12, the difference between the distance D1 and the distance D2 in the aforementioned specific portion of the buckled portion 12 is preferably 70 μm or more, and more preferably 150 μm or more. The upper limit is not particularly limited, for example, it is 300 μm or less, and preferably 250 μm or less.

[0068] Considering the excellent durability of the functional layer 8 described later, the distance D1 in the buckling portion 12 (especially the specific portion mentioned above) is preferably 150 μm or more, more preferably 250 μm or more, and even more preferably 300 μm or more. The upper limit is not particularly limited, for example, it is 1 mm or less, preferably 750 μm or less, and even more preferably 500 μm or less.

[0069] Considering the excellent durability of the functional layer 8 described later, in the buckling portion 12 (particularly the aforementioned specific portion), it is preferable that the ratio ((D1 / L1)×100) of the distance D1 (in μm) from the end face 4 of the glass substrate 1 relative to the first main surface 2 along the tangential direction to the length L1 (in μm) of the first main surface 2 is relatively large. Specifically, it is preferable that the ratio of the distance D1 to the length L1 of the first main surface 2 is 0.250% or more, more preferably 0.290% or more, and even more preferably 0.320% or more. The upper limit is not particularly limited, for example, it is 0.500% or less. Furthermore, the length L1 of the first main surface 2 is also the length along the extension of the distance D1.

[0070] Furthermore, in the flat portion 11 of the glass substrate 1 (refer to...) Figure 1 In this context, the distances D1 (hereinafter, D1 is also referred to as "the length of the first interface 5") and D2 (hereinafter, D2 is also referred to as "the length of the second interface 6") may not be different as in the buckling portion 12; they may be the same. "Same" means consistent within the range of processing error. "Processing error" refers, for example, to 5% or less, preferably 3% or less, and more preferably 1% or less, of either distance D1 or distance D2. Alternatively, "processing error" refers to the difference between distance D1 and distance D2 being 30 μm or less, preferably 10 μm or less.

[0071] When the distances D1 and D2 at the flat portion 11 of the glass substrate 1 are the same, the aesthetics are excellent, and therefore it is preferred.

[0072] When multiple flat portions 11 exist in the glass substrate 1, the distances D1 and D2 in each flat portion 11 can be different or the same. Under the same conditions, it offers excellent aesthetics and good manufacturability, and is therefore preferred.

[0073] <Distance D3>

[0074] like Figure 2 As shown, in order to further suppress the light emission of the chamfered portion, in the buckled portion 12 (especially the specific portion mentioned above), it is preferable that the distance D3 from the end face 4 of the glass substrate 1 to the second interface 6 in the tangential direction (the extension direction of the buckled portion 12) relative to the second main surface 3 is shorter. Specifically, it is preferably 150 μm or less, more preferably 120 μm or less, and more preferably 100 μm or less.

[0075] Furthermore, it does not prevent the printing section 7 from being positioned on the second interface 6.

[0076] Distances D1, D2, and D3 were measured by observing the glass substrate 1 at 20x magnification using a microscope (MS100, manufactured by Asahi Optical Manufacturing Co., Ltd.).

[0077] Distances D1, D2, and D3 are defined as follows.

[0078] Please refer to Figure 1 as well as Figure 2 .

[0079] Let any point on the intersection line X1 of the first main surface 2 and the first interface 5 be designated as point Y1. Let the plane (section) passing through point Y1 and intersecting the intersection line X1 perpendicularly in the extension direction of the buckling portion 12 be designated as section Z. Section Z is also the plane (section) perpendicular to the tangent of the intersection line X1 at point Y1. Let the longest distance on section Z in the direction parallel to the first main surface 2 from point Y1 to end face 4 be defined as distance D1.

[0080] Next, the point on section Z among the points on the intersection line X2 of the second main surface 3 and the second interface 6 is designated as point Y2. The longest distance on section Z from point Y2 to end face 4 in the direction parallel to the second main surface 3 is defined as distance D2.

[0081] Here, the "longest distance" is set because: end face 4 is a curved surface, and there may be cases where the boundary line between end face 4 and the first interface 5 or the second interface 6 is unclear.

[0082] Distance D3 is defined as the shortest distance along the direction parallel to the second main surface 3 from point Y2 to the printing section 7 on section Z. It is set as the "shortest distance" because there may be cases such as bulging at the end face of the printing section 7.

[0083] Chemically strengthened glass

[0084] When the glass substrate 1 is used as protective glass, it is preferable that the glass substrate 1 is glass that has undergone chemical strengthening treatment (chemically strengthened glass).

[0085] A compressive stress layer is formed on the surface of chemically strengthened glass.

[0086] The depth (DOL) of the compressive stress layer is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 25 μm or more.

[0087] The compressive stress (CS) value of the compressive stress layer is preferably 500 MPa or more, more preferably 650 MPa or more, and even more preferably 750 MPa or more. On the other hand, it is preferably 1200 MPa or less.

[0088] The compressive stress value (CS) and depth (DOL) of the compressive stress layer were measured using a surface stress meter (FSM-6000, manufactured by Orihara Manufacturing Co., Ltd.).

[0089] <Functional Layer>

[0090] like Figure 2 As shown, a functional layer 8 can also be provided on the first main surface 2 of the glass substrate 1. Examples of functional layers 8 include anti-reflective layers and anti-fouling layers.

[0091] When a functional layer 8 is provided on the first main surface 2 at the buckled portion 12 of the glass substrate 1, such as Figure 2 As shown, functional layers 8 can also be continuously set above the first interface 5.

[0092] <Haze>

[0093] The haze of the glass substrate 1 is preferably 30% or less, and more preferably 10% or less.

[0094] The haze is the transmittance haze specified in JIS K7136.

[0095] <Plate thickness, shape, and size>

[0096] The thickness of the glass substrate 1 is preferably 0.5 mm to 2.5 mm, and more preferably 0.7 mm to 2.0 mm.

[0097] The shape and size of the main surfaces (first main surface 2 and second main surface 3) of the glass substrate 1 are appropriately determined, for example, according to the shape of the vehicle display device used.

[0098] [Method for manufacturing glass substrate]

[0099] Next, also refer to Figure 3 The method for manufacturing the glass substrate 1 described above (hereinafter, for convenience, also referred to as "this manufacturing method") will be explained.

[0100] <Preparation of the glass plate>

[0101] First, such as Figure 3 As shown, a glass plate 31 is prepared. The glass plate 31 has one main surface, namely the first main surface 32, the other main surface, namely the second main surface 33, and an end surface 34 connected to the first main surface 32 and the second main surface 33.

[0102] The first main surface 32 of the glass plate 31 becomes the first main surface 2 of the glass substrate 1. The second main surface 33 of the glass plate 31 becomes the second main surface 3 of the glass substrate 1.

[0103] The thickness of glass plate 31 is the same as the thickness of glass substrate 1.

[0104] Furthermore, the glass plate 31 has a buckled portion (not shown) that buckles in the same way as the buckled portion 12 of the glass substrate 1.

[0105] Examples of glass types for glass plate 31 include soda-lime glass and aluminosilicate glass (SiO2-Al2O3-Na2O series glass).

[0106] As for the glass composition of glass plate 31, for example, the glass composition described in paragraph

[0019] of Japanese Patent Application Publication No. 2019-006650 can be cited.

[0107] When performing the chemical strengthening treatment described later, it is preferable to use, for example, chemically strengthened glass (Dragon Track (registered trademark), manufactured by AGC Corporation) with aluminosilicate glass as the matrix.

[0108] Grinding

[0109] Figure 3 This is a cross-sectional view showing the grinding of the glass plate 31 using the grinding wheel 35.

[0110] Next, as Figure 3 As shown, the end of the glass plate 31 is ground using a grinding wheel 35. This results in a so-called chamfering of the glass plate 31.

[0111] A circumferentially extending annular grinding groove is formed on the outer peripheral surface of the grinding wheel 35, i.e., the grinding surface 36. The grinding surface 36 includes abrasive grains such as alumina, silicon carbide, and diamond. The grit size (JIS R6001) of the abrasive grains is not particularly limited, and for example, it can be selected from the range of #300 to #2000.

[0112] The grinding wheel 35 rotates around its center line and moves relative to the end of the glass plate 31, grinding the end of the glass plate 31 through the grinding surface 36. A coolant such as water can also be used during grinding.

[0113] For example, grinding is performed using a grinding wheel 35 with a diameter d1 that is smaller than the radius of curvature of the glass plate 31. Thus, firstly, the distance D1 (length of the first interface 5) and the distance D2 (length of the second interface 6) are machined to the same length (not shown).

[0114] Next, using a different grinding tool than the grinding wheel 35 (e.g., a grinding machine), only the portion that forms the buckling portion 12 is ground, and the distance D1 (the length of the first interface 5) is made longer than the distance D2 (the length of the second interface 6) (see reference). Figure 2 ).

[0115] In this way, the glass substrate 1 described above is obtained.

[0116] Alternatively, the glass substrate 1 can be obtained using only the grinding wheel 35 without using other grinding tools such as grinding machines.

[0117] In this case, for example, a grinding wheel 35 with a diameter d1 having a radius of curvature larger than usual relative to the glass plate 31 is used to grind the glass plate 31. Such a grinding wheel 35 can be obtained, for example, as a custom part. Thus, only the portion that will become the buckled portion 12 is machined so that the distance from D1 (the length of the first interface 5) is longer than the distance from D2 (the length of the second interface 6) (see reference). Figure 2 ).

[0118] Chemical Enhancement Treatment

[0119] Alternatively, the ground glass plate 31 can be chemically strengthened. In this case, the chemically strengthened glass plate 31 becomes the glass substrate 1.

[0120] In the case of chemical strengthening treatment, chemically strengthened glass is used as glass plate 31.

[0121] In chemical strengthening treatment, existing known methods can be used, typically by immersing the glass plate 31 in molten salt. This causes an ion exchange (displacement) between basic ions (Li ions and / or Na ions) and other basic ions (Na ions and / or K ions) with larger ionic radii in the molten salt on the surface of the glass plate 31. Through this ion exchange, a layer (compressive stress layer) is formed on the surface of the glass plate 31 due to the increased density. This strengthens the glass plate 31.

[0122] When the alkaline ion contained in the glass plate 31 is Na ion, it is preferable that the molten salt (inorganic salt composition) contains potassium nitrate (KNO3).

[0123] The processing conditions, such as the temperature of the molten salt and the immersion time, can be set to the desired values ​​for the compressive stress value (CS) and the thickness (DOL) of the compressive stress layer.

[0124] <Formation of Functional Layers>

[0125] Next, functional layers 8, such as anti-reflective layers and anti-fouling layers, are arbitrarily formed on the first main surface 2 of the obtained glass substrate 1. For example, a coating that will become functional layer 8 is applied to the first main surface 2 of the glass substrate 1 using a known method. Thus, functional layer 8 is formed.

[0126] At this point, the following method can also be used: temporarily planarize the glass substrate 1 having the buckled portion 12, apply a coating while maintaining this state to form the functional layer 8, and then remove the planarization (see Japanese Patent Publication No. 2015-522506). Hereinafter, for convenience, this method will be referred to as the "planarization method". In the planarization method, if the planarization of the glass substrate 1 is removed, the glass substrate 1 is restored, and the first main surface 2 buckles into a concave shape.

[0127] When the functional layer 8 is formed on the first main surface 2 using the planarization method, the formed functional layer 8 buckles into a concave shape in the buckling portion 12 after formation, resulting in stress concentration and making it easy to peel off from the first main surface 2.

[0128] Therefore, as Figure 2 As shown, preferably, the functional layer 8 is not only continuously provided on the first main surface 2, but also continuously provided on the first interface 5 connected to the first main surface 2.

[0129] Compared to the functional layer 8 formed only on the first main surface 2, the functional layer 8 formed on both the first main surface 2 and the first interface 5 is difficult to peel off (i.e., the functional layer 8 has excellent durability). This is presumably because: the area of ​​the latter functional layer 8 is relatively large compared to the former, and it also produces an anchoring effect at the first interface 5.

[0130] Preferably, when the functional layer 8 is disposed on the first main surface 2 and the first interface 5, the surface roughness Sa of the first interface 5 at the buckling portion 12, the distance D1 (the length of the first interface 5), and the ratio of the distance D1 to the length L1 of the first main surface 2 are within the ranges described above. As a result, the durability of the functional layer 8 at the buckling portion 12 is superior.

[0131] Example

[0132] Hereinafter, embodiments of the present invention will be specifically described through examples, etc. However, the present invention is not limited to the following examples. Hereinafter, Examples 1 to 5 are embodiments, and Example 6 is a comparative example.

[0133] 〈Example 1~Example 6〉

[0134] AGC's "Dragon Tracks" were prepared as glass plate 31 (see reference). Figure 3The dimensions of the main surfaces (first main surface 32 and second main surface 33) of glass plate 31 are 800mm × 100mm. The thickness of glass plate 31 is 1.1mm.

[0135] The glass plate 31 bends towards the first main surface 32 in a concave direction at approximately a 5:3 ratio along its long side. The radius of curvature (in mm) of the portion forming the bend 12 is shown in Table 1 below.

[0136] The end of the prepared glass plate 31 was ground using a grinding wheel 35. The diameter d1 (unit: mm) of the grinding wheel 35 is shown in Table 1 below. Next, in Examples 1 to 5, only the portion that becomes the buckled portion 12 was ground using a grinding machine. In this way, a glass substrate 1 having a first interface 5 and a second interface 6 (see reference) was obtained. Figure 1 ).

[0137] The distances D1 (length of the first interface 5), D2 (length of the second interface 6), and the difference between distances D1 and D2 in the flat portion 11 and the buckled portion 12 of the obtained glass substrate 1 are shown in Table 1 below (all units are μm).

[0138] Furthermore, the length L1 (in mm) of the first main surface 2 and the ratio (in %) of the distance D1 to the length L1 of the buckled portion 12 of the obtained glass substrate 1 are shown in Table 1 below.

[0139] A frame-shaped printing portion 7 made of black ink is formed on the outer edge of the second main surface 3 of the glass substrate 1. The distance D3 (unit: μm) from the printing portion 7 to the second interface 6 at the buckled portion 12 from the end face 4 of the glass substrate relative to the tangential direction of the second main surface 3 is shown in Table 1 below.

[0140] The following evaluations were conducted using glass substrates 1 from Examples 1 to 6 respectively.

[0141] Suppression of light emission from the chamfered portion of the buckled section

[0142] A metal plate (not shown) formed with the same shape as the glass substrate 1 is placed on the second main surface 3 side of the glass substrate 1. Under an illuminance of 1500 lux, from position P opposite to the flat portion 11 (refer to...) Figure 1 The buckling portion 12 of the glass substrate 1 was observed.

[0143] If the chamfered portion (first interface 5 and second interface 6) does not emit light, "A" is recorded in Table 1 below; if the chamfered portion emits light but is not dazzling, "B" is recorded in Table 1 below; and if the chamfered portion emits light and is dazzling, "C" is recorded in Table 1 below. If it is "A" or "B", it can be evaluated that the emission of light from the chamfered portion 12 of the buckled portion has been suppressed.

[0144] <Durability of the functional layer in the buckling section>

[0145] According to the method described in Japanese Patent Publication No. 2015-522506, a functional layer 8 was formed on the first main surface 2 and the first interface 5 of the glass substrate 1 using a planarization method.

[0146] That is, the glass substrate 1 with the buckled portion 12 is temporarily planarized, and the functional layer 8 is formed while maintaining this state, and then the planarization is de-planarized. Due to the de-planarization, the glass substrate 1 is restored, and the first main surface 2 buckles into a concave shape again.

[0147] As functional layer 8, an anti-reflective layer and an anti-fouling layer are formed as follows.

[0148] First, using a niobium oxide cylindrical target (trade name: NBO target, manufactured by AGC Ceramics), oxygen and argon are introduced into the vacuum chamber while magnetron sputtering is performed to form a 13nm thick high refractive index layer (layer 1) composed of niobium oxide.

[0149] Next, using a silicon cylindrical target (manufactured by AGC Ceramics), magnetron sputtering was performed while oxygen and argon were introduced into the vacuum chamber to form a 35nm thick low refractive index layer (second layer) made of silicon oxide on the first layer.

[0150] Then, on the second layer, a high refractive index layer (third layer) of niobium oxide with a thickness of 115 nm was formed, similar to the first layer. And, on the third layer, a low refractive index layer (fourth layer) of silicon oxide with a thickness of 80 nm was formed, similar to the second layer.

[0151] This results in a four-layer antireflective layer consisting of alternating layers of high-refractive-index niobium oxide and low-refractive-index silicon oxide.

[0152] Next, an antifouling layer was formed. First, a heating container containing the antifouling layer material, namely KY-185 (manufactured by Shin-Etsu Chemical Co., Ltd.), was heated to 270°C. Next, a glass substrate 1 with the antireflective layer formed thereon was placed inside a vacuum chamber. Then, the antifouling layer material was sprayed from a nozzle connected to the heating container containing the antifouling layer material toward the antireflective layer of the glass substrate 1 inside the vacuum chamber, and a film was formed. The film thickness was measured using a quartz crystal oscillator monitor installed inside the vacuum chamber until the film thickness reached 4 nm. Then, the glass substrate 1 was removed from the vacuum chamber.

[0153] In this way, an anti-reflective layer and an anti-fouling layer are formed on the glass substrate 1 as functional layers 8.

[0154] The glass substrate 1 on which the functional layer 8 is formed was continuously subjected to vibration at 100-150 Hz for one week. Through this vibration, a shear force was applied between the functional layer 8 and the surface of the glass substrate 1, and the functional layer 8, which has weak adhesion, was easily peeled off. Then, the functional layer 8 disposed on the first main surface 2 and the first interface 5 of the buckling portion 12 was rubbed 100 times with a load of 200g using steel wool #0000.

[0155] Visually inspect the rubbed area. If no significant changes are observed, record "A" in Table 1 below; if several scratches (less than 10) are observed, record "B" in Table 1 below; if more than 10 scratches are observed but the functional layer has not peeled off, record "C" in Table 1 below; if the functional layer has peeled off, record "D" in Table 1 below. If it is "A", "B", or "C", then the durability of the functional layer 8 of the buckling portion 12 can be evaluated as excellent.

[0156] [Table 1]

[0157] Table 1

[0158]

[0159] <Summary of Evaluation Results>

[0160] As shown in Table 1 above, compared with Example 6, in which the distance D1 is longer than the distance D2 and the difference between the distance D1 and the distance D2 is 80 to 150 μm, the chamfered portion of the buckling portion 12 can suppress light emission.

[0161] Comparative Examples 1 to 5 show the following trend: the greater the difference between distance D1 and distance D2, the more the light emission of the chamfered portion 12 can be further suppressed.

[0162] In addition, in Examples 1 to 5, the durability of the functional layer 8 at the buckling portion 12 is also excellent.

[0163] Furthermore, although the present invention has been described in detail 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 invention. This application is based on Japanese Patent Application No. 2019-113466, filed on June 19, 2019, the contents of which are incorporated herein by reference.

[0164] Explanation of reference numerals in the attached figures:

[0165] 1…glass substrate; 2…first main surface; 3…second main surface; 4…end face; 5…first interface; 6…second interface; 7…printed section; 8…functional layer; 11…flat section; 12…buckling section; 31…glass plate; 32…first main surface of the glass plate; 33…second main surface of the glass plate; 34…end face of the glass plate; 35…grinding wheel; 36…grinding surface; D1…distance from the end face of the glass substrate to the first main surface in the tangential direction relative to the first main surface; D2…distance from the end face of the glass substrate to the second main surface. D1… Distance from the end face of the glass substrate relative to the tangent direction of the second main surface; D2… Distance from the printing section to the second interface from the end face of the glass substrate relative to the tangent direction of the second main surface; d1… Diameter of the grinding wheel; L1… Length of the first main surface; P… Position relative to the flat portion of the glass substrate; X1… Intersection line of the first main surface and the first interface; X2… Intersection line of the second main surface and the second interface; Y1… Point on the intersection line of the first main surface and the first interface; Y2… Point on the intersection line of the second main surface and the second interface; Z… Section.

Claims

1. A glass substrate comprising: a first main surface; a second main surface which is a main surface on the side opposite to the first main surface; an end surface which is sandwiched between the first main surface and the second main surface; a first boundary surface which is connected to the first main surface and the end surface; a second boundary surface which is connected to the second main surface and the end surface; and a bent portion which is formed by bending the first main surface into a concave shape and bending the second main surface into a convex shape, wherein the bent portion includes a portion in which a distance Dl from the end surface to the first main surface in a tangential direction of the end surface with respect to the first main surface is longer than a distance D2 from the end surface to the second main surface in a tangential direction of the end surface with respect to the second main surface, and a difference between the distance Dl and the distance D2 is 50 μm or more, and a surface roughness Sa of the first boundary surface and the second boundary surface is 0.02 μm or more.

2. The glass substrate according to claim 1, wherein the bent portion has a printed portion on the second main surface, and a distance D3 from the printed portion to the second boundary surface in the tangential direction of the end surface with respect to the second main surface is 150 μm or less.

3. The glass substrate according to claim 1 or 2, wherein the glass substrate further comprises a flat portion in which the first main surface and the second main surface are flat, in addition to the bent portion.

4. The glass substrate according to claim 3, wherein the distance Dl and the distance D2 are the same in the flat portion.

5. The glass substrate according to claim 1 or 2, wherein the bent portion has a functional layer on the first main surface and the first boundary surface.

6. The glass substrate according to claim 1 or 2, wherein the distance Dl is 250 μm or more in the bent portion.

7. The glass substrate according to claim 1 or 2, wherein a ratio of the distance Dl with respect to a length Ll of the first main surface is 0.250% or more in the bent portion, wherein the length Ll is a length on an extension line of the distance Dl.

8. The glass substrate according to claim 1 or 2, wherein the first boundary surface and the second boundary surface are flat.

9. The glass substrate according to claim 1 or 2, wherein the glass substrate is used as a protective glass for a display device.

10. The glass substrate according to claim 9, wherein the display device is a vehicle-mounted display device. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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