Zircon compatible glasses for down draw

• US 8,802,581 B2
• Filed: 08/16/2010
• Issued: 08/12/2014
• Est. Priority Date: 08/21/2009
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Dejneka, Matthew John, Ellison, Adam James, Hanson, Benjamin Zain
• Primary Examiner(s): Olsen, Kaj K
• Assistant Examiner(s): Bolden, Elizabeth A
• Application Number:
  US12/856,840
• Publication Number:
  US 20110045961A1
• Time in Patent Office: 1,457 Days
• Field of Search: 501/65, 501/66, 501/68, 501/69, 501/70, 428/410, 428/426
• US Class Current: 501/68
• CPC Class Codes: C03B 17/064 by the overflow downdraw fusion process; Isopipes therefor
• CPC Class Codes: C03C 21/00 Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface
• CPC Class Codes: C03C 21/002 to perform ion-exchange between alkali ions C03C21/005 takes precedence
• CPC Class Codes: C03C 2204/00 Glasses, glazes or enamels with special properties
• CPC Class Codes: C03C 3/083 containing aluminium oxide or an iron compound
• 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: C03C 3/091 containing aluminium
• CPC Class Codes: C03C 3/093 containing zinc or zirconium
• CPC Class Codes: C03C 4/18 for ion-sensitive glass
• CPC Class Codes: Y10T 428/315 Surface modified glass [e.g., tempered, strengthened, etc.]

Abstract

A glass that is down-drawable and ion exchangeable. The glass has a temperature T^35kp at which the viscosity is 35 kilopoise. T^35kp is less than the breakdown temperature T^breakdown of zircon.

Claims

1. A glass comprising SiO₂, Al₂O₃, and Na₂O, wherein SiO₂+B₂O₃≧

66 mol %, Al₂O₃≧

7 mol %, B₂O₃≦

6.27 mol %, Na₂O≧

9 mol %, B₂O₃+Na₂O+K₂O+MgO+CaO≧

18 mol %, and CaO≦

2 mol %, wherein the glass has a temperature T^35kp at which the glass has a viscosity of 35 kpoise and a zircon breakdown temperature T^breakdown at which zircon breaks down to form ZrO₂ and SiO₂, wherein T^breakdown is greater than T^35kp wherein T^margin=T^breakdown−

T^35kp, wherein T^margin (°

C.)=446.6−

50.2[Al₂O₃]+22.6[B₂O₃]−

4.4[Na₂O]−

3.9[K₂O]−

1.2[MgO+CaO] where concentrations [Al₂O₃], [B₂O₃], [Na₂O], [K₂O], [MgO], and [CaO] are expressed in mol %, and wherein T^margin≧

0.

2. The glass of claim 1, wherein the glass comprises:

61 mol %≦

SiO₂≦

75 mol %;

7 mol %≦

Al₂O₃≦

15 mol %;

0 mol %≦

B₂O₃≦

6.27 mol %;

9 mol %≦

Na₂O≦

21 mol %;

0 mol %≦

K₂O≦

4 mol %;

0 mol %≦

MgO≦

7 mol %; and

0 mol %≦

CaO≦

2 mol %.

3. The glass of claim 1, wherein T^margin=T^breakdown−

T^35kp, wherein T^margin=610.6−

41.0[Al₂O₃]+9.9[B₂O₃]−

3.5[Na₂O]−

20.2[K₂O]−

25.6[MgO]+34.2[CaO] where concentrations [Al₂O₃], [B₂O₃], [Na₂O], [K₂O], [MgO], and [CaO] are expressed in mol %, and wherein T^margin≧

0.

4. The glass of claim 1, wherein the glass is down-drawable.

5. The glass of claim 1, wherein the glass is fusion drawn into a glass sheet.

6. The glass of claim 5, wherein the glass sheet has less than one inclusion of solid ZrO₂ per pound of glass sheet.

7. The glass of claim 1, wherein B₂O₃+Na₂O+K₂O−

Al₂O₃≧

0 mol %.

8. The glass of claim 1, wherein the glass has a liquidus viscosity of greater than about 100 kpoise.

9. The glass of claim 1, wherein the glass has a temperature at a viscosity of 350 poise, T³⁵⁰, of less than or equal to 1650°

C.

10. The glass of claim 1, wherein the glass is formed into one of a cover plate, a window, a casing, a display screen, and a touch panel of an electronic device.

11. The glass of claim 1, wherein the glass is ion exchangeable.

12. The glass of claim 11, wherein the glass is ion exchanged to form a compressive layer on at least one surface of the glass.

13. The glass of claim 12, wherein the ion exchanged glass has a compressive stress of at least 350 MPa and a compressive depth of layer of at least 20 microns.

14. The glass of claim 12, wherein the ion exchanged glass has a central tension of at least 10 MPa.

15. A glass, the glass comprising SiO₂, Al₂O₃, and Na₂O and having a temperature T^35kp at which the glass has a viscosity of 35 kpoise, wherein SiO₂+B₂O₃≧

66 mol %, Al₂O₃≧

7 mol %, B₂O₃≦

6.27 mol %, Na₂O≧

9 mol %, B₂O₃+Na₂O+K₂O+MgO+CaO≧

18 mol %, and CaO≦

2 mol %, and having a temperature T^breakdown at which zircon breaks down to form ZrO₂ and SiO₂, wherein T^breakdown is greater than T^35kp, wherein T^margin=T^breakdown−

T^35kp, wherein T^margin (°

C.)=446.6−

50.2[Al₂O₃]+22.6[B₂O₃]−

4.4[Na₂O]−

3.9[K₂O]−

1.2[MgO+CaO] where concentrations [Al₂O₃], [B₂O₃], [Na₂O], [K₂O], [MgO], and [CaO] are expressed in mol %, and wherein T^margin≧

0.

16. The glass of claim 15, wherein the glass comprises:

61 mol %≦

SiO₂≦

75 mol %;

7 mol %≦

Al₂O₃≦

15 mol %;

0 mol %≦

B₂O₃≦

6.27 mol %;

9 mol %≦

Na₂O≦

21 mol %;

0 mol %≦

K₂O≦

4 mol %;

0 mol %≦

MgO≦

7 mol %; and

0 mol %≦

CaO≦

2 mol %.

17. The glass of claim 15, wherein T^margin=T^breakdown−

T^35kp, wherein T^margin=610.6−

41.0[Al₂O₃]+9.9[B₂O₃]−

3.5[Na₂O]−

20.2[K₂O]−

25.6[MgO]+34.2[CaO] where concentrations [Al₂O₃], [B₂O₃], [Na₂O], [K₂O], [MgO], and [CaO] are expressed in mol %, and wherein T^margin≧

0.

18. The glass of claim 15, wherein the glass is down-drawable.

19. The glass of claim 15, wherein the glass is fusion drawn into a glass sheet.

20. The glass of claim 19, wherein the glass sheet has less than one inclusion of solid ZrO₂ per pound of glass sheet.

21. The glass of claim 15, wherein B₂O₃+Na₂O+K₂O−

Al₂O₃≧

0 mol %.

22. The glass of claim 15, wherein the glass has a liquidus viscosity of greater than about 100 kpoise.

23. The glass of claim 15, wherein the glass has a temperature at a viscosity of 350 poise, T³⁵⁰, of less than or equal to 1650°

C.

24. The glass of claim 15, wherein the glass is formed into one of a cover plate, a window, a casing, a display screen, and a touch panel of an electronic device.

25. The glass of claim 15, wherein the glass is ion exchangeable.

26. The glass of claim 19, wherein the glass is ion exchanged to form a compressive layer on at least one surface of the glass.

27. The glass of claim 26, wherein the ion exchanged glass has a compressive stress of at least 350 MPa and a compressive depth of layer of at least 20 microns.

28. The glass of claim 26, wherein the ion exchanged glass has a central tension of at least 10 MPa.

29. A glass comprising SiO₂, Al₂O₃, and Na₂O, wherein SiO₂+B₂O₃≧

66 mol %, Al₂O₃≧

7 mol %, B₂O₃≦

6.27 mol %, Na₂O≧

9 mol %, B₂O₃+Na₂O+K₂O+MgO+CaO≧

18 mol %, and CaO≦

2 mol %, and having a breakdown margin T^margin, wherein T^margin (°

C.)=446.6−

50.2[Al₂O₃]+22.6[B₂O₃]−

4.4[Na₂O]−

3.9[K₂O]−

1.2[MgO+CaO], where concentrations [Al₂O₃], [B₂O₃], [Na₂O], [K₂O], [MgO], and [CaO] are expressed in mol %, and wherein T^margin≧

0.

30. A glass comprising SiO₂, Al₂O₃, and at least one alkali metal oxide which includes Na₂O and, optionally, at least one of K₂O and Rb₂O, wherein SiO₂+B₂O₃≧

66 mol %, Al₂O₃≧

7 mol %, B₂O₃≦

6.27 mol %, Na₂O≧

9 mol %, B₂O₃+Na₂O+K₂O+MgO+CaO≧

18 mol %, and CaO≦

2 mol %, and having a breakdown margin T^margin, wherein T^margin=T^breakdown−

T^35kp, wherein T^margin (°

C.)=446.6−

50.2[Al₂O₃]+22.6[B₂O₃]−

4.4[Na₂O]−

3.9[K₂O]−

1.2[MgO+CaO] where concentrations [Al₂O₃], [B₂O₃], [Na₂O], [K₂O], [MgO], and [CaO] are expressed in mol %, and wherein T^margin≧

0.

31. The glass of claim 30, wherein the glass has a temperature T^35kp at which the glass has a viscosity of 35 kpoise and a zircon breakdown temperature T^breakdown at which zircon breaks down to form ZrO₂ and SiO₂, wherein T^breakdown is greater than T^35kp, and wherein T^margin=T^breakdown−

T^35kp.

32. The glass of claim 30, wherein the glass comprises:

61 mol %≦

SiO₂≦

75 mol %;

7 mol %≦

Al₂O₃≦

15 mol %;

0 mol %≦

B₂O₃≦

6.27 mol %;

9 mol %≦

Na₂O≦

21 mol %;

0 mol %≦

K₂O≦

4 mol %;

0 mol %≦

MgO≦

7 mol %; and

0 mol %≦

CaO≦

2 mol %.

33. The glass of claim 30, wherein the glass has less than one inclusion of solid ZrO₂ per pound of glass.

34. The glass of claim 30, wherein the glass is ion exchanged to form a compressive layer on at least one surface of the glass, and wherein the ion exchanged glass has a compressive stress of at least 350 MPa and a compressive depth of layer of at least 20 microns.

35. The glass of claim 34, wherein the ion exchanged glass has a central tension of at least 10 MPa.