GLASS SUBSTRATE FOR DISPLAY COVER GLASS AND ITS PRODUCTION PROCESS

• US 20120219792A1
• Filed: 05/08/2012
• Published: 08/30/2012
• Est. Priority Date: 11/25/2009
• Status: Active Grant

• Current Assignee: AGC, Inc.
• Original Assignee: Asahi Glass Company, Limited (AGC, Inc.)
• Inventors: Yamamoto, Hiroyuki, Matsuo, Yusaku
• Granted Patent: US 8,869,558 B2
• Time in Patent Office: Days
• US Class Current: 428/336
• CPC Class Codes: C03C 21/002 to perform ion-exchange between alkali ions C03C21/005 takes precedence
• CPC Class Codes: C03C 21/005 to introduce in the glass such metals or metallic ions as Ag, Cu
• CPC Class Codes: C03C 2204/02 Antibacterial glass, glaze or enamel
• CPC Class Codes: C03C 3/087 containing calcium oxide, e.g. common sheet or container glass
• CPC Class Codes: C03C 3/093 containing zinc or zirconium
• CPC Class Codes: C03C 4/0092 for glass with improved high visible transmittance, e.g. extra-clear glass
• CPC Class Codes: G02F 1/133331 Cover glasses
• CPC Class Codes: Y10T 428/265 1 mil or less
• CPC Class Codes: Y10T 428/315 Surface modified glass [e.g., tempered, strengthened, etc.]

Abstract

To provide a glass substrate for a display cover glass not only having excellent strength and antibacterial properties but also having a high transparency and a high visible transmittance suitable as a cover glass for a display device. A glass substrate for a display cover glass, which comprises a surface compressive stress layer and an antibacterial substance-containing layer formed on the glass substrate surface, characterized by having a ratio (T1/T2) of the transmittance T1 at a wavelength of 428 nm to the transmittance T2 at a wavelength of 650 nm of the glass substrate of at least 0.95, and a transmittance at a wavelength of 428 nm of at least 86% when the thickness of the glass substrate is from 0.1 to 3.0 mm.

Claims

1. A glass substrate for a display cover glass, which comprises a surface compressive stress layer and an antibacterial substance-containing layer on the glass substrate surface, characterized by having a ratio (T1/T2) of the transmittance T1 at a wavelength of 428 nm to the transmittance T2 at a wavelength of 650 nm of the glass substrate of at least 0.95, and a transmittance at a wavelength of 428 nm of at least 86% when the thickness of the glass substrate is from 0.1 to 3.0 mm.

2. The glass substrate for a display cover glass according to claim 1, wherein the glass substrate has a glass composition comprising, as represented by mol % as calculated as oxides, from 55 to 80% of SiO₂, from 0.1 to 15% of Al₂O₃, from 0 to 15% of B₂O₃, from 0 to 10% of ZnO, from 0.1 to 15% of Na₂O, from 0 to 10% of K₂O, and from 0 to 16% of MgO+CaO.

3. The glass substrate for a display cover glass according to claim 1, wherein the surface compressive stress layer on the glass substrate surface is formed by chemical tempering, and the surface compressive stress layer has a depth of at least 3 μ

m and a surface compressive stress of a least 250 MPa.

4. The glass substrate for a display cover glass according to claim 1, wherein the antibacterial substance-containing layer is a silver ion diffusion layer having silver ions diffused in the glass substrate surface.

5. The glass substrate for a display cover glass according to claim 4, wherein the silver ion diffusion layer has a silver amount of from 0.2 to 100 μ

g/cm² at a depth of 40 μ

m from the glass substrate surface.

6. The glass substrate for a display cover glass according to claim 1, wherein the glass substrate is plate-formed by a float process.

7. The glass substrate for a display cover glass according to claim 1, which is used for a cover glass of a touch panel display.

8. A display device, which uses the glass substrate for a display cover glass as defined in claim 1 as a front glass of a display.

9. A process for producing a glass substrate for a display cover glass, which comprises a step of chemically tempering a glass substrate in a molten salt containing at least KNO₃, a step of cleaning the chemically tempered glass substrate, a step of forming a silver film on the surface of the cleaned glass substrate, a step of subjecting the glass substrate having the silver film formed thereon to heat treatment to diffuse silver ions from the glass substrate surface to the inside, and a step of washing and removing silver remaining on the surface, not diffused in the inside of the glass substrate in the above step of diffusing silver ions.

12. The process for producing a glass substrate for a display cover glass according to claim 9, wherein the step of diffusing silver ions involves a step of subjecting the glass substrate having the silver film formed thereon to heat treatment at from 300 to 475°

C.

10. A process for producing a glass substrate for a display cover glass, which comprises a step of plate-forming a glass substrate, a step of chemically tempering the plate-formed glass substrate in a molten salt containing at least KNO₃, a step of cleaning the chemically tempered glass substrate, a step of forming a silver film on the surface of the cleaned glass substrate, a step of subjecting the glass substrate having the silver film formed thereon to heat treatment to diffuse silver ions from the glass substrate surface to the inside, and a step of washing and removing silver remaining on the surface, not diffused in the inside of the glass substrate in the above step of diffusing silver ions.

11. The process for producing a glass substrate for a display cover glass according to claim 10, wherein the step of plate-forming a glass substrate is carried out by a float process.