GLASS PLATE FOR DISPLAY DEVICES

• US 20090298669A1
• Filed: 05/29/2009
• Published: 12/03/2009
• Est. Priority Date: 05/30/2008
• Status: Active Grant

• Current Assignee: AGC, Inc.
• Original Assignee: Asahi Glass Company, Limited (AGC, Inc.)
• Inventors: Maeda, Kei, Hayashi, Kazutaka, AKIBA, Shusaku
• Granted Patent: US 8,715,829 B2
• Time in Patent Office: Days
• US Class Current: 501/70
• CPC Class Codes: C03C 3/085 containing an oxide of a divalent metal
• CPC Class Codes: C03C 3/087 containing calcium oxide, e.g. common sheet or container glass
• CPC Class Codes: Y10T 428/315 Surface modified glass [e.g., tempered, strengthened, etc.]

Abstract

To provide a glass plate for display devices wherein without carrying out a post treatment, the depth of a compression stress layer is increased, while the surface compression stress is prevented from being excess only by chemical tempering.

A glass plate for display devices, which is obtained by chemically tempering a glass plate comprising, as represented by mol % based on the following oxides, from 50 to 74% of SiO₂, from 1 to 10% of Al₂O₃, from 6 to 14% of Na₂O, from 3 to 15% of K₂O, from 2 to 15% of MgO, from 0 to 10% of CaO and from 0 to 5% of ZrO₂, wherein the total content of SiO₂ and Al₂O₃ is at most 75%, the total content of Na₂O and K₂O, i.e. Na₂O+K₂O, is from 12 to 25%, and the total content of MgO and CaO, i.e. MgO+CaO, is from 7 to 15%.

Claims

1. A glass plate for display devices, which is obtained by chemically tempering a glass plate comprising, as represented by mol % based on the following oxides, from 50 to 74% of SiO₂, from 1 to 10% of Al₂O₃, from 6 to 14% of Na₂O, from 3 to 15% of K₂O, from 2 to 15% of MgO, from 0 to 10% of CaO and from 0 to 5% of ZrO₂, wherein the total content of SiO₂ and Al₂O₃ is at most 75%, the total content of Na₂O and K₂O, i.e. Na₂O+K₂O, is from 12 to 25%, and the total content of MgO and CaO, i.e. MgO+CaO, is from 7 to 15%.

2. The glass plate for display devices according to claim 1, wherein in the glass plate, Na₂O is at most 12%, K₂O is at least 4%, Na₂O+K₂O is at least 14%, the difference obtained by deducting the content of Al₂O₃ from Na₂O+K₂O is at least 10%, MgO+CaO is at least 8%, and in a case where the glass plate contains BaO, the content of BaO is less than 1%.

3. The glass plate for display devices according to claim 2, wherein in the glass plate, SiO₂ is from 60 to 70%, Al₂O₃ is from 2 to 8%, Na₂O is at most 11%, K₂O is from 6 to 12%, MgO is from 4 to 14%, CaO is from 0 to 8%, ZrO₂ is from 0 to 4%,and Na₂O+K₂O is from 16 to 20%.

4. The glass plate for display devices according to claim 1, wherein in the glass plate, SiO₂ is from 60 to 70%, Al₂O₃ is from 2 to 8%, K₂O is at most 8%, MgO is at least 6%, Na₂O+K₂O is at most 18%, and the sum of the content of K₂O multiplied by 1.7 and the content of Na₂O, i.e. Na₂O+1.7K₂O, is less than 19%.

5. The glass plate for display devices according to claim 2, wherein in the glass plate, SiO₂ is at least 63%, Al₂O₃ is at least 3%, Na₂O is at least 8%, K₂O is at most 8%, MgO is from 6 to 14%, CaO is from 0 to 1%, ZrO₂ is from 1 to 4%, and Na₂O+K₂O is from 14 to 17%.

6. The glass plate for display devices according to claim 5, wherein the sum of the content of K₂O multiplied by 1.7 and the content of Na₂O, i.e. Na₂O+1.7K₂O, is less than 19%.

7. The glass plate for display devices according to claim 1, wherein in the glass plate, MgO is at least 6.5%.

8. The glass plate for display devices according to claim 1, wherein the glass plate contains SrO or BaO, and the total content of alkaline earth metal oxides is at most 15%.

9. The glass plate for display devices according to claim 1, which contains no Li₂O or at most 2% of Li₂O.

10. The glass plate for display devices according to claim 1, wherein the glass plate to be chemically tempered is produced by a float process.