Method for producing chemically strengthened glass

Patent metadata

Field	Value
Publication number	US-9828286-B2
Application number	US-201615000675-A
Country	US
Kind code	B2
Filing date	Jan 19, 2016
Priority date	Jul 19, 2013
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

A method for producing a chemically strengthened glass, including a step of bringing a glass containing sodium into contact with an inorganic salt containing potassium nitrate, thereby performing ion exchange of a Na ion in the glass with a K ion in the inorganic salt, in which the inorganic salt contains at least one salt selected from the group consisting of K 2 CO 3 , Na 2 CO 3 , KHCO 3 , NaHCO 3 , K 3 PO 4 , Na 3 PO 4 , K 2 SO 4 , Na 2 SO 4 , KOH and NaOH, and the method includes: a step of washing the glass after the ion exchange; a step of subjecting the glass to an acid treatment after the washing; and a step of subjecting the glass to an alkali treatment after the acid treatment.

First claim

The invention claimed is:

1. A method for producing a chemically strengthened glass, comprising:
bringing a glass comprising sodium into contact with an inorganic salt comprising potassium nitrate, thereby performing ion exchange of a Na ion in the glass with a K ion in the inorganic salt;
washing the glass after the ion exchange;
bringing the glass into contact with an acid after the washing such that a low-density layer is formed in a surface portion of the glass; and
bringing the glass into contact with an alkali after contacting the acid such that at least part of the low-density layer is removed,
wherein the inorganic salt comprises at least one salt selected from the group consisting of K 2 CO 3 , Na 2 CO 3 , KHCO 3 , NaHCO 3 , K 3 PO 4 , Na 3 PO 4 , K 2 SO 4 , Na 2 SO 4 , KOH and NaOH.

2. The method according to claim 1 , wherein the inorganic salt has a sodium content of 500 ppm by weight or more.

3. The method according to claim 1 , wherein the inorganic salt comprises K 2 CO 3 in an amount of 0.1 mol% or more.

4. The method according to claim 1 , further comprising washing the glass after contacting the acid and before contacting the alkali.

5. The method according to claim 1 , further comprising washing the glass after contacting the alkali.

6. The method according to claim 1 , wherein the acid is an acid solution having a pH of less than 7.

7. The method according to claim 6 , wherein the acid solution is a weak acid.

8. The method according to claim 6 , wherein the acid solution is a strong acid.

9. The method according to claim 1 , wherein the glass is brought into contact with the acid at a temperature of 100° C. or lower.

10. The method according to claim 1 , wherein the glass is brought into contact with the acid for from 10 seconds to 5 hours.

11. The method according to claim 6 , wherein the acid solution has an acid concentration of from 0.1 wt % to 20 wt %.

12. The method according to claim 1 , wherein the alkali is an alkali solution having a pH of more than 7.

13. The method according to claim 12 , wherein the alkali solution is a weak base.

14. The method according to claim 12 , wherein the alkali solution is a strong base.

15. The method according to claim 1 , wherein the glass is brought into contact with the alkali at a temperature of from 0 to 100° C.

16. The method according to claim 1 , wherein the glass is brought into contact with the alkali for from 10 seconds to 5 hours.

17. The method according to claim 12 , wherein the alkali solution has an alkali concentration of from 0.1 wt % to 20 wt %.

18. The method according to claim 1 , wherein the chemically strengthened glass has a thickness of 5 mm or less.

19. The method according to claim 1 , wherein a thickness of the low-density layer before contacting the alkali is 20 nm or more.

20. The method according to claim 1 , further comprising drying the glass after contacting the acid and before contacting the alkali.

Assignees

• Asahi Glass Co Ltd

Inventors

• Kashima Izuru
• Fujiwara Yusuke
• Tamai Kiyoshi
• Suzuki Yuichi
• Kobayashi Daisuke
• Sera Yoichi
• Yamada Taku

Classifications

• C03C21/002 Primary

  to perform ion-exchange between alkali ions (C03C21/005 takes precedence) · CPC title

• C03C3/091

  containing aluminium · CPC title

• C03C21/008

  in solid phase, e.g. using pastes, powders · CPC title

• C03C3/087

  containing calcium oxide, e.g. common sheet or container glass · CPC title

• C03C15/00

  Surface treatment of glass, not in the form of fibres or filaments, by etching (etching or surface-brightening compositions, in general C09K13/00) · CPC title