US-12623958-B2 - Method for manufacturing reinforced glass, and reinforced glass

US12623958B2US 12623958 B2US12623958 B2US 12623958B2US-12623958-B2

Abstract

Provided is a method of manufacturing a tempered glass, including an etching step of etching a plate-shaped or sheet-shaped chemically tempered glass having a compressive stress layer in a surface thereof. The method further includes a step of preparing, as the chemically tempered glass before the etching, a chemically tempered glass, which has in at least part thereof a bendable thin portion having a thickness t1 a , in which the thickness t1 a is 150 μm or less, in which a maximum compressive stress CSa in the compressive stress layer before the etching is 1,100 MPa or less, and in which a depth DOLa of the compressive stress layer before the etching is less than 15 μm. The etching step includes etching the chemically tempered glass so that an etching amount Δt on one surface of the chemically tempered glass is 0.25 μm or more and 3 μm or less.

Inventors

Takayuki Noda
Shigeyoshi Ito

Assignees

NIPPON ELECTRIC GLASS CO., LTD.

Dates

Publication Date: 20260512
Application Date: 20210714
Priority Date: 20200730

Claims (9)

1 . A method of manufacturing a tempered glass, the method comprising: an etching step of etching a plate-shaped or sheet-shaped chemically tempered glass having a compressive stress layer in a surface thereof, and a step of preparing, as the chemically tempered glass before the etching, a chemically tempered glass, which has in at least part thereof a bendable thin portion having a thickness t1a, in which the thickness t1a is 150 μm or less, in which a maximum compressive stress CSa in the compressive stress layer before the etching is 1,100 MPa or less, and in which a depth DOLa of the compressive stress layer before the etching is less than 15 μm, wherein the etching step comprises etching the chemically tempered glass so that an etching amount Δt on one surface of the chemically tempered glass is 0.25 μm or more and 3 μm or less, wherein the etching causes a maximum value CTb of an internal tensile stress of the chemically tempered glass after the etching, which is determined by the following equation (A), where t1b represents a thickness of the bendable thin portion after the etching, CSb represents a maximum compressive stress in the compressive stress layer after the etching, and DOLb represents a depth of the compressive stress layer after the etching, to be 240 MPa or more and 450 MPa or less, CTb=CSb ×DOLb/( t 1 b− 2×DOLb) (A), and wherein the etching causes the depth DOLb of the compressive stress layer after the etching to be 14.75 μm or less.
2 . The method of manufacturing a tempered glass according to claim 1 , wherein the etching causes the thickness t1b of the bendable thin portion after the etching to be 149.5 μm or less, and the maximum compressive stress CSb in the compressive stress layer after the etching to be 400 MPa or more and 950 MPa or less.
3 . The method of manufacturing a tempered glass according to claim 1 , wherein the chemically tempered glass before the etching comprises a plurality of thick portions each having a thickness t2a larger than the thickness t1a of the bendable thin portion before the etching, wherein the thickness t2a is more than 150 μm, and wherein the bendable thin portion before the etching extends in a band shape between the plurality of thick portions.
4 . The method of manufacturing a tempered glass according to claim 1 , wherein the chemically tempered glass before the etching has a substantially uniform sheet thickness.
5 . The method of manufacturing a tempered glass according to claim 1 , wherein the etching is wet etching, and wherein the etching is performed by bringing an etching medium into contact with all surfaces of the chemically tempered glass.
6 . The method of manufacturing a tempered glass according to claim 5 , wherein the etching medium is an aqueous solution containing HF, wherein the aqueous solution containing HF is an aqueous solution containing only HF at a concentration of from 0.1 mol/L to 30 mol/L, or an aqueous solution containing HF at a concentration of from 0.1 mol/L to 30 mol/L, and one substance selected from the group consisting of: HCl; HNO 3 ; H 2 SO 4 ; and NH 4 F, the one substance having a concentration of from 0.1 mol/L to 30 mol/L, and wherein the etching is performed by immersing the chemically tempered glass in the aqueous solution having a temperature of from 10° C. to 30° C. for from 0.1 minute to 60 minutes.
7 . The method of manufacturing a tempered glass according to claim 5 , wherein the etching medium is an alkaline aqueous solution.
8 . The method of manufacturing a tempered glass according to claim 7 , wherein the alkaline aqueous solution is an aqueous solution containing NaOH or KOH as an alkali component, and wherein the etching is performed by immersing the chemically tempered glass in the aqueous solution, which has a concentration of the alkali component of from 1 mol/L to 20 mol/L and a temperature of from 10° C. to 130° C., for from 0.5 minute to 120 minutes.
9 . The method of manufacturing a tempered glass according to claim 1 , wherein main surfaces of the chemically tempered glass before the etching are non-polished surfaces.

Description

TECHNICAL FIELD The present invention relates to a method of manufacturing a tempered glass, and a tempered glass. BACKGROUND ART In recent years, a chemically tempered glass having a sheet thickness of from about 0.4 mm to about 1.0 mm has been often used as a cover glass for each of various electronic terminals and display devices. Particularly when used for a portable electronic terminal such as a smartphone, strength of the cover glass is important. For example, in Patent Literature 1, there is a disclosure of a technology for improving the strength, involving subjecting a glass surface to etching treatment after chemical tempering to remove a defect on the glass surface. CITATION LIST Patent Literature 1: JP 2016-102060 A SUMMARY OF INVENTION Technical Problem In recent years, there have been developed devices, such as a smartphone and a tablet PC, of a so-called foldable type, in which a display surface of a display is configured to be foldable. A cover glass to be used for such device needs to have a smaller sheet thickness than in the related art so as to be foldable. In addition, an extremely high internal tensile stress acts on the cover glass at its bent portion at the time of folding, and hence the presence of a defect or a crack on a surface of the bent portion serves as a cause of breakage, and moreover, the glass becomes liable to be shattered at the time of breakage. Accordingly, the cover glass for such application needs to be further suppressed from having a surface defect and reduced in internal tensile stress as compared to the related art. However, the related-art glass like that of Patent Literature 1 described above is supposed to be used for a device of a type not to be folded (so-called straight type), and is not assumed to be applied to a foldable-type smartphone device. Accordingly, even when an attempt was made to apply the related-art glass to such application, sufficient bending performance was not obtained. In addition, bending strength enough to endure bending was not obtained. In addition, the glass was not able to be sufficiently suppressed from bursting and scattering at the time of breakage. An object of the present invention is to provide a method of manufacturing a tempered glass, and a tempered glass, which can simultaneously achieve high bending performance, high bending strength, and suppression of shattering at the time of breakage. Solution to Problem According to one embodiment of the present invention, there is provided a method of manufacturing a tempered glass, comprising an etching step of etching a plate-shaped or sheet-shaped chemically tempered glass having a compressive stress layer in a surface thereof, the method further comprising a step of preparing, as the chemically tempered glass before the etching, a chemically tempered glass, which has in at least part thereof a bendable thin portion having a thickness t1a, in which the thickness t1a is 150 μm or less, in which a maximum compressive stress CSa in the compressive stress layer before the etching is 1,100 MPa or less, and in which a depth DOLa of the compressive stress layer before the etching is less than 15 μm, wherein the etching step comprises etching the chemically tempered glass so that an etching amount Δt on one surface of the chemically tempered glass is 0.25 μm or more and 3 μm or less. In the method of manufacturing a tempered glass according to the one embodiment of the present invention, it is preferred that the etching cause a thickness t1b of the thin portion after the etching to be 149.5 μm or less, a maximum compressive stress CSb in the compressive stress layer after the etching to be 400 MPa or more and 950 MPa or less, and a depth DOLb of the compressive stress layer after the etching to be 14.75 μm or less. In the method of manufacturing a tempered glass according to the one embodiment of the present invention, it is preferred that: the chemically tempered glass before the etching comprise a plurality of thick portions each having a thickness t2a larger than the thickness t1a of the thin portion; the thickness t2a be more than 150 μm; and the thin portion extend in a band shape so as to connect the plurality of thick portions. In the method of manufacturing a tempered glass according to the one embodiment of the present invention, it is preferred that the chemically tempered glass before the etching be entirely formed of the thin portion, and have a substantially uniform sheet thickness. In the method of manufacturing a tempered glass according to the one embodiment of the present invention, it is preferred that: the etching be wet etching; and the etching be performed by bringing an etching medium into contact with all surfaces of the chemically tempered glass. In the method of manufacturing a tempered glass according to the one embodiment of the present invention, it is preferred that: the etching medium be an aqueous solution containing HF; the aqueous solution containing HF b