Manufacturing method for ultra-thin glass processed products

Abstract

To provide a method for manufacturing an ultra-thin glass processed product that has high edge strength and is resistant to chipping, and can also be used as a protective cover for a flexible display. [Solution] A method for manufacturing an ultra-thin glass processed product, comprising the steps of: cutting a glass plate having a thickness of 0.2 mm or less; attaching a masking material, which is a resin film substrate with an adhesive layer formed on one side thereof, to both sides of the glass plate with the adhesive layer facing the glass plate so as to cover the entire main surface of the glass plate; and chemically etching the cut surface of the glass plate with the masking material attached to it, to form the edge of the glass plate into a trapezoidal shape in cross section.

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an ultra-thin glass workpiece, and more particularly to a method for manufacturing an ultra-thin glass workpiece having improved edge strength by etching the edges. [Background technology]

[0002] Ultra-thin glass sheets with a thickness of 200 μm or less are used as protective covers for displays of smartphones, etc. In particular, glass sheets with a thickness of 100 μm or less are used as protective covers for flexible displays.

[0003] For example, Patent Document 1 describes a method for producing chemically strengthened glass that can also be used as cover glass for foldable devices, etc., by cutting a glass plate having a thickness of 0.20 mm or less using chemical etching or a short-pulse laser, chemically etching only the cut edge surface, and chemically strengthening the glass by ion exchange. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-150930 Summary of the Invention [Problem to be solved by the invention]

[0005] To reduce the bending radius, it is necessary to thin the glass sheet while maintaining high edge strength. However, if the main surface and edge of the glass sheet are connected at right angles across a single edge, the edge is prone to chipping, causing the glass sheet to break. For this reason, for glass sheets with a thickness of about 0.5 mm or more, the edges are chamfered with a grinding wheel, and then minute cracks at the edges are removed by chemical etching. However, when the glass is 0.2 mm or thinner, it is difficult to mechanically chamfer the edges.

[0006] The present invention has been made in consideration of the above, and aims to provide a method for manufacturing an ultra-thin glass processed product that has high edge strength and is less likely to chip, and can also be used as a protective cover for a flexible display. [Means for solving the problem]

[0007] To address the above-mentioned problem, in the present invention, the edge of the glass plate is formed into a trapezoidal shape in cross section by chemical etching.

[0008] The method for manufacturing an ultra-thin glass processed product of the present invention includes the steps of cutting a glass plate having a thickness of 0.2 mm or less, attaching a masking material having an adhesive layer formed on one side of a resin film substrate to both sides of the glass plate with the adhesive layer facing the glass plate so as to cover the entire main surface of the glass plate, and chemically etching the cut surface of the glass plate with the masking material attached to it, thereby forming the edge of the glass plate into a trapezoidal shape in cross section.

[0009] Here, the main surfaces of the glass plate refer to a pair of surfaces of the glass plate that are much larger in area than the other surfaces of the glass plate. Also, attaching the mask material to both surfaces of the glass plate means attaching the mask material to both main surfaces of the glass plate.

[0010] Preferably, in the method for producing an ultrathin glass processed product, the glass plate has a thickness of 0.1 mm or less. The method for producing an ultrathin glass processed product of the present invention is advantageous when applied to thinner glass plates.

[0011] Preferably, in any of the above methods for manufacturing ultra-thin glass processed products, the film substrate of the mask material is made of polyolefin, polyethylene terephthalate, or polyvinyl chloride and has a thickness of 40 μm or more. This makes the mask material sufficiently strong, preventing the mask materials on both sides of the glass plate from sticking together during handling before etching and during etching. More preferably, the film substrate of the mask material is made of polypropylene. Polypropylene films are particularly resistant to penetration by etching solutions containing hydrofluoric acid, making the main surface of the glass less likely to devitrify during etching.

[0012] Preferably, in any of the above methods for producing an ultrathin glass processed product, the adhesive layer has an adhesive strength of 1 N / 25 mm or less. Here, the adhesive strength of the adhesive is a value measured using glass as a test plate by the 90-degree peel method in accordance with JIS Z 0237. By weakening the adhesive strength, it is possible to prevent the mask materials on both sides of the glass plate from sticking to each other during handling before etching and during etching, and to make the edge shape of the glass plate after etching a trapezoidal shape in cross section.

[0013] Preferably, in any of the above methods for manufacturing an ultrathin glass processed product, the mask material is attached to the glass plate so that it protrudes from the cut surface of the glass plate by 0.5 mm or less. The smaller the protrusion of the mask material, the less likely the mask material will stick to both sides of the glass plate during handling before etching and during etching, and the easier it is to control the flow of the etching solution that hits the cut surface of the glass plate.

[0014] More preferably, in any of the above methods for manufacturing an ultrathin glass processed product, the mask material is applied to the glass plate so that it protrudes from the cut surface of the glass plate by 0.05 mm or more and 0.5 mm or less. By setting the protrusion of the mask material to 0.05 mm or more, the mask material can be cut with practical accuracy and applied so as to cover the entire main surface of the glass plate.

[0015] Preferably, in any of the above methods for producing an ultra-thin glass product, the glass plate is cut using a scribing tool. [Effects of the Invention]

[0016] According to the method for manufacturing an ultra-thin glass product of the present invention, ultra-thin glass sheets that are difficult to chamfer using a grinding wheel can be chamfered by etching and fine cracks can be removed, thereby maintaining high edge strength. As a result, it is possible to manufacture ultra-thin glass sheets suitable for use as protective covers for flexible displays. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a process flow diagram of a method for manufacturing an ultra-thin glass processed product according to one embodiment. [Figure 2] 1 is a cross-sectional view illustrating a method for cutting a glass plate, where A is a glass plate on which scribe lines have been formed, and B is a glass plate after cutting. [Figure 3] FIG. 2 is a cross-sectional view showing the configuration of a glass plate and a mask material. [Figure 4] FIG. 1 is a cross-sectional view showing a state in which mask materials are attached to both surfaces of a glass plate. [Figure 5] A and B are cross-sectional views showing the edge of an ultra-thin glass workpiece after etching. [Figure 6] 1 is a photograph of a cross section of an end portion of an ultra-thin glass processed product of an example. DETAILED DESCRIPTION OF THE INVENTION

[0018] An embodiment of the method for producing an ultra-thin glass sheet product of the present invention will be described with reference to FIGS. 2 to 5 along the flow chart of FIG.

[0019] First, the manufacturing method of the ultra-thin glass processed product of this embodiment is roughly as follows: A glass plate 10 having a thickness of 0.2 mm or less is cut, a mask material 20 is attached to both main surfaces of the glass plate 10 (FIGS. 3 and 4), and the cut surface 12 of the glass plate is chemically etched. After etching, the edge of the glass plate 10 is formed into a trapezoidal shape in cross section (FIG. 5). Each step will be described in detail below. In this specification, when the "surface" of a glass plate is simply referred to, it means the main surface.

[0020] The thickness of the glass plate 10 is 0.2 mm or less, preferably 0.1 mm or less, and more preferably 0.06 mm or less. The thinner the glass plate, the smaller the bending radius that can be achieved, making it preferable as a protective cover for a flexible display. In particular, for foldable displays installed in folding mobile communication devices and the like, ultra-thin glass having a thickness of 0.06 mm or less is used. Furthermore, the manufacturing method of the ultra-thin glass processed product of this embodiment is applicable even when the glass thickness is 0.1 mm or less or 0.06 mm or less. On the other hand, the thickness of the glass plate 10 is preferably 0.01 mm or more, and more preferably 0.03 mm or more. If the glass plate is too thin, the surface strength evaluated by a pen drop test or the like may be insufficient.

[0021] There are no particular limitations on the composition or manufacturing method of the glass plate 10. For example, the glass plate 10 may be made of aluminosilicate glass or alkali-free glass formed by a fusion method or an overflow method.

[0022] The method for cutting the glass plate 10 is not particularly limited, but it is preferably cut using a scribing tool. Referring to FIG. 2, the scribing tool is a tool that forms a scribe line (ruled line) 14 on one surface 11a of the glass plate 10, and the glass plate is split along the formed scribe line. Scribing tools include one that rolls an abacus-shaped wheel while pressing it against the glass surface to form a scribe line with the ridge of the wheel, and one that forms a scribe line by sliding a fixed diamond cutting edge against the glass surface while pressing it. When the thickness of the glass plate 10 is 0.1 mm or less, it is preferable to use a scribing tool with a fixed diamond cutting edge, as this makes cutting easier.

[0023] Laser and chemical etching methods are also widely used to cut ultra-thin glass sheets, but the method using a scribing tool has the advantages of lower equipment costs and shorter cutting time than the method using a laser, and higher dimensional accuracy than the method using chemical etching. In addition, the cut surface 12 using a scribing tool is highly smooth, and this smoothness is maintained even on the edge surface (32 in Figure 5) after etching, so the edge strength of the ultra-thin glass sheet product 30 can be increased.

[0024] On the other hand, when a scribing tool is used, a plastic deformation region 15 of the glass is formed near the scribe line 14 on the surface 11a, and vertical cracks 16 extending from the scribe line perpendicular to the surface 11a and horizontal cracks 17 extending from the scribe line substantially parallel to the surface 11a are formed. The length of the horizontal cracks 17 is approximately 5 μm. As described above, when cutting using a scribing tool, many defects that impair edge strength are present near the surface 11a where the scribe line 14 is formed. It is desirable to completely remove these defects by etching. In the method for producing an ultra-thin glass processed product of this embodiment, the edge of the glass plate is formed into a trapezoidal shape in cross section by etching, thereby removing the defects in the region near the surface 11a where the scribe line 14 is formed. Therefore, the method for producing an ultra-thin glass processed product of this embodiment is particularly suitable for cutting the glass plate 10 using a scribing tool.

[0025] 3, a mask material 20 is attached to both surfaces 11a and 11b of the cut glass plate 10. The mask material 20 is made of a resin film substrate 21 and an adhesive layer 22 formed on one surface thereof.

[0026] The material of the film substrate 21 is preferably a dense material that is resistant to etching solutions containing hydrofluoric acid (HF). The film substrate 21 is preferably made of polyolefin, polyethylene terephthalate, or polyvinyl chloride, as these have appropriate flexibility and are easy to apply to glass surfaces. The film substrate 21 is more preferably made of polypropylene, as polypropylene films are particularly resistant to penetration of etching solutions containing HF, and the main surfaces 11a, 11b of the glass are less likely to devitrify during the etching process.

[0027] The thickness of the film substrate 21 is preferably 40 μm or more. If the film substrate 21 is too thin, the mask material 20 will be weak, and the mask material 20 on both sides of the glass plate 10 will stick together during handling before etching and during etching, which may prevent the edge of the glass plate from being formed into a trapezoidal shape in cross section. On the other hand, the thickness of the film substrate 21 is preferably 200 μm or less, and more preferably 100 μm or less. Although there is no problem with the film substrate 21 being thicker than this, there is no particular benefit and the material cost will be wasted.

[0028] The adhesive constituting the adhesive layer 22 may be made of known materials such as acrylic, silicone, or urethane materials.

[0029] The adhesive strength of the adhesive layer 22, measured using glass as a test plate by the 90-degree peel method in accordance with JIS Z0237, is preferably 1 N / 25 mm or less, more preferably 0.5 N / 25 mm or less, and even more preferably 0.2 N / 25 mm or less. Such adhesives are sometimes referred to commercially as weak adhesives. Weak adhesive strength prevents the masking materials 20, 20 on both sides of the glass plate 10 from sticking together even when they come into contact during handling before etching or during etching. Furthermore, weak adhesives are harder than typical adhesives and are less likely to swell in the etching solution, allowing the edge shape of the glass plate after etching to be trapezoidal in cross section. On the other hand, the adhesive strength of the adhesive layer 22 is preferably 0.01 N / 25 mm or more. If the adhesive strength is too weak, there is a risk of peeling during handling before etching.

[0030] The thickness of the adhesive layer 22 is preferably 5 to 30 μm, and more preferably 5 to 15 μm. If the adhesive layer 22 is too thick, it will swell during etching, making it difficult for the edge of the glass plate 10 to form a trapezoidal shape. On the other hand, if the adhesive layer 22 is too thin, the thickness is likely to be non-uniform, which will result in uneven adhesion to the glass surface and an uneven edge shape after etching.

[0031] 4, when the mask material 20 is attached to the glass plate 10, the overhang H from the cut surface 12 of the glass plate is preferably 0.5 mm or less, more preferably 0.3 mm or less. If the overhang is too large, the gap between the mask materials 20 on both sides of the glass plate will narrow during etching, weakening the flow of the etching solution hitting the cut surface 12, and this may result in uneven etching.

[0032] On the other hand, the protrusion H of the mask material 20 from the cut surface 12 needs to be 0 mm or more; that is, the mask material does not need to protrude as long as the entire main surface of the glass is covered with the mask material. However, considering the dimensional accuracy when cutting the mask material 20 and the alignment accuracy when applying it to the glass plate 10, achieving a protrusion H of 0 mm in the actual process requires cutting the mask material 20 slightly larger and applying it to the glass plate 10, and then trimming the outer peripheral edge of the mask material so that it is flush with the cut surface 12. In contrast, by setting the protrusion H of the mask material 20 from the cut surface 12 to preferably 0.05 mm or more, more preferably 0.1 mm or more, it is possible to cut the mask material using known cutting and application equipment and apply it so that the entire main surface of the glass plate is covered, thereby simplifying the process.

[0033] The glass plate 10 with the mask material 20 attached to both sides is immersed in an etching bath and etched. The etching solution can be a known solution for etching glass, such as hydrofluoric acid or a mixed acid of hydrofluoric acid with hydrochloric acid, nitric acid, sulfuric acid, or the like. Also, known etching equipment and methods can be used.

[0034] The etching solution does not come into contact with the main surfaces 11a and 11b covered with the mask material 20, but only comes into contact with the cut surface 12, so only the cut surface is etched. The flow of the etching solution increases the etching rate near the edge ridges 13a and 13b of the cut surface 12, and both end portions of the cut surface are preferentially etched. If the adhesive layer 22 has weak adhesive strength and appropriate hardness, etching of the corners near the mask material 20 proceeds further, resulting in the edge of the glass plate 10 being trapezoidal in cross section. On the other hand, if the adhesive layer 22 has strong adhesive strength and is too soft, the gap between the main surfaces 11a and 11b and the adhesive layer 22 is filled by the adhesive, and the edge of the etched glass plate 10 does not become trapezoidal in cross section, but maintains its rectangular shape before etching.

[0035] Referring to FIG. 5, the etching amount E is preferably 10 μm or more, more preferably 15 μm or more, so that microcracks such as horizontal cracks 17 are completely removed. On the other hand, the etching amount E is preferably 50 μm or less. Increasing the etching amount beyond this amount provides no particular benefit and increases the time required for the etching process. The shape of the end of the glass sheet 10 is such that the width P of the end face 32, which corresponds to the upper base of the trapezoid and remains parallel to the original cut surface 12, is preferably 30% to 70% of the thickness T of the glass sheet 10. Furthermore, the width C in the main surface direction of the chamfered portions 33 a, 33 b, which correspond to the hypotenuses of the trapezoid, is preferably 50% to 200% of the thickness T of the glass sheet. This removes horizontal cracks 17 formed by the scribing tool and plastically deformed regions 15 near the scribe lines.

[0036] This completes the manufacture of the ultra-thin glass product 30. Thereafter, the mask material 20 is removed, and appropriate processing such as chemical strengthening or lamination with other resin films is carried out according to the required specifications. [Example]

[0037] A 50 μm-thick aluminosilicate glass plate was cut using a scribing tool equipped with a fixed diamond cutting edge, and a masking material consisting of a 60 μm-thick polypropylene film substrate with an adhesive layer made of an acrylic adhesive formed on one side was attached to both sides of the glass plate, with the adhesive layer facing the glass plate, so as to cover the entire main surface of the glass plate. The adhesive layer had a thickness of 10 μm, an adhesive strength of 0.08 N / 25 mm, and the masking material protruded 0.15 mm from the cut surface of the glass plate. The glass plate with the masking material attached to both sides was immersed in an etching tank, and the edge of the glass plate was etched 20 μm using an etching solution containing HF to produce an ultra-thin glass processed product of the example.

[0038] Figure 6 shows the edge shape of the glass plate after etching. It can be seen that the edge is trapezoidal in cross section. Furthermore, the arithmetic mean roughness Ra of the edge surface was in the range of 0.26 to 0.47 nm, confirming that the smoothness of the cut surface was maintained even at the edge surface after etching.

[0039] An ultra-thin glass processed product of the comparative example was produced in the same manner as the ultra-thin glass processed product of the example, except that the adhesive layer of the masking material was changed. The adhesive layer was made of an acrylic UV-curable adhesive, had a thickness of 20 μm, and an adhesive strength of 18 N / 25 mm. This UV-curable adhesive is commonly used as a masking material during glass etching processes, and can be easily peeled off from the glass by irradiating it with UV light after etching to harden it.

[0040] In the comparative example, the edges of the ultra-thin glass sheet were not chamfered and the shape before etching was maintained.

[0041] The present invention is not limited to the above-described embodiments and examples, and various modifications are possible within the scope of the technical concept thereof.

[0042] For example, in the above-described embodiments and examples, one layer of a mask material / glass plate / mask material laminate is etched, but a plurality of laminates may be stacked and etched together.

[0043] Furthermore, the application of the ultra-thin glass processed product of the present invention is not limited to protective covers for displays, and the ultra-thin glass processed product of the present invention can be used for various members that require edge strength. [Explanation of symbols]

[0044] 10 Glass Plate 11a, 11b surface (main surface) 12 Cut surface 13a, 13b Edge ridge 14 Scribe Line 15 Plastic deformation region 16 Vertical crack 17 Horizontal crack 20 Masking material 21 Film substrate 22 adhesive layer 30 Ultra-thin glass processed products 32 End face 33a, 33b chamfered parts T Glass plate thickness H Mask material protrusion amount E Etching amount P Width of the upper base of the trapezoidal cross section C: Width of the oblique side of the trapezoidal cross section in the direction of the main surface of the glass plate

Claims

1. A step of cutting a glass plate having a thickness of 0.2 mm or less; a step of attaching a mask material having a resin film substrate and an adhesive layer formed on one side thereof to both sides of the glass plate with the adhesive layer facing the glass plate so as to cover the entire main surface of the glass plate; chemically etching the cut surface of the glass plate to which the mask material is attached, thereby forming an edge of the glass plate into a trapezoidal shape in cross section; A method for manufacturing an ultra-thin glass processed product having the above structure.

2. The thickness of the glass plate is 0.1 mm or less. The method for producing the ultra-thin glass processed product according to claim 1.

3. The film substrate of the mask material is made of polyolefin, polyethylene terephthalate, or polyvinyl chloride and has a thickness of 40 μm or more. The method for producing the ultra-thin glass processed product according to claim 1.

4. The adhesive strength of the pressure-sensitive adhesive layer is 1 N / 25 mm or less. The method for producing the ultra-thin glass processed product according to claim 1.

5. The mask material is attached to the glass plate so that it protrudes from the cut surface of the glass plate by 0.5 mm or less. The method for producing the ultra-thin glass processed product according to claim 1.

6. The mask material is attached to the glass plate so that it protrudes from the cut surface of the glass plate by 0.05 mm or more. The method for producing the ultra-thin glass processed product according to claim 5.

7. The glass sheet is cut using a scribing tool. The method for producing the ultra-thin glass processed product according to claim 1.

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