GLASS COMPOSITIONS HAVING HIGH THERMAL AND CHEMICAL STABILITY AND METHODS OF MAKING THEREOF

• US 20110048074A1
• Filed: 11/10/2010
• Published: 03/03/2011
• Est. Priority Date: 02/10/2006
• Status: Active Grant

• Current Assignee: Adam J.G. Ellison, Natesan Venkataraman, Paul S. Danielson
• Original Assignee: Adam J.G. Ellison, Natesan Venkataraman, Paul S. Danielson
• Inventors: Danielson, Paul S., Ellison, Adam J.G., Venkataraman, Natesan
• Granted Patent: US 8,763,429 B2
• Time in Patent Office: Days
• US Class Current: 65/90
• CPC Class Codes: C03B 17/06 Forming glass sheets
• CPC Class Codes: C03B 17/064 by the overflow downdraw fusion process; Isopipes therefor
• CPC Class Codes: C03C 3/091 containing aluminium
• CPC Class Codes: C03C 3/095 containing rare earths

Abstract

Described herein are alkali-free, boroalumino silicate glasses exhibiting desirable physical and chemical properties for use as substrates in flat panel display devices, such as, active matrix liquid crystal displays (AMLCDs). In accordance with certain of its aspects, the glasses possess good dimensional stability as a function of temperature.

Claims

1-20. -20. (canceled)

21. A method for producing alkali-metal free glass sheets by a downdraw process comprising selecting, melting, and fining batch materials so that the glass making up the sheets comprises SiO₂, Al₂O₃, B₂O₃, MgO, CaO and BaO, and, on an oxide basis, comprises:

(i) a MgO content greater than or equal to 2.0 mole percent;

(ii) a CaO content greater than or equal to 3.0 mole percent; and

(iii) a BaO content greater than or equal to 1.0 mole percent,

wherein;

(a) the glass has a Σ

(MgO+CaO+SrO+BaO)/(Al₂O₃) ratio greater than or equal to 1.15, where Al₂O₃, MgO, CaO, SrO, and BaO represent the mole percents of the respective oxide components;

(b) the fining is performed without the use of substantial amounts of arsenic; and

(c) a population of 50 sequential glass sheets produced by the downdraw process from the melted and fined batch materials has an average gaseous inclusion level of less than 0.10 gaseous inclusions/cubic centimeter, where each sheet in the population has a volume of at least 500 cubic centimeters.

22. The method of claim 21 wherein the downdraw process comprises a fusion draw process.

38. The method of claim 21 further comprising using the glass sheets as substrates for liquid crystal displays.

23. A method for producing alkali-metal free glass sheets by a downdraw process comprising selecting, melting, and fining batch materials so that the glass making up the sheets comprises in mole percent on an oxide basis:

24. The method of claim 23 wherein the downdraw process comprises a fusion draw process.

25. The method of claim 23 wherein the glass making up the sheets comprises in mole percent on an oxide basis:

26. The method of claim 23 wherein the glass making up the sheets satisfies the relationship:

1.20≦

Σ

(MgO+CaO+SrO+BaO+3La₂O₃)/(Al₂O₃)≦

1.45.

27. The method of claim 23 wherein the glass making up the sheets has a strain point which satisfies the relationship:

700°

C.≦

strain point≦

730°

C.

28. The method of claim 23 wherein the glass making up the glass sheets exhibits a dimensional change of less than 30 ppm for a 5 minute heat treatment at 600°

C.

29. The method of claim 23 wherein the glass making up the glass sheets satisfies at least one of the following properties:

(a) SiO₂ is 66.5-70.5 mole percent; and

/or

(b) B₂O₃ is 1.0-4.0 mole percent; and

/or

(c) MgO is 2.0-6.0 mole percent; and

/or

(d) CaO is 2.0-6.5 mole percent.

30. The method of claim 23 wherein the glass making up the glass sheets has the following properties:

(a) Σ

(MgO+CaO+SrO+BaO+3La₂O₃)/(Al₂O₃)≦

1.55;

(b) the glass has a strain point greater than or equal to 700°

C.;

(c) the glass has a temperature at 200 poise viscosity less than or equal to 1,665°

C.; and

(d) the glass has a viscosity at the liquidus temperature greater than or equal to 85,000 poise.

31. The method of claim 23 wherein the glass making up the glass sheets has one or more of the following properties:

(a) Σ

(MgO+CaO+SrO+BaO+3La₂O₃)/(Al₂O₃)≧

1.25; and

/or

(b) Σ

(MgO+CaO+SrO+BaO+3La₂O₃)/(Al₂O₃)≦

1.55; and

/or

(c) 1.25≦

Σ

(MgO+CaO+SrO+BaO+3La₂O₃)/(Al₂O₃)≦

1.45.

32. The method of claim 23 wherein the glass making up the glass sheets has one or more of the following properties:

(a) a liquidus viscosity greater than or equal to 100,000 poise; and

/or

(b) a linear coefficient of thermal expansion (CTE) of 28×

10<sup>−

7</sup>/°

C.≦

CTE≦

40×

10<sup>−

7</sup>/°

C. over the temperature range of 0 to 300°

C.; and

/or

(c) a strain point greater than or equal to 710°

C.; and

/or

(d) a Young'"'"'s modulus/density ratio greater than 30.0 GPa·

cm³/g; and

/or

(e) the glass is substantially free of Sb₂O₃.

39. The method of claim 23 further comprising using the glass sheets as substrates for liquid crystal displays.

33. A method for producing alkali-metal free glass sheets by a downdraw process comprising selecting, melting, and fining batch materials so that the glass making up the sheets comprises SiO₂, Al₂O₃, B₂O₃, MgO, CaO, optionally La₂O₃, and at least one of SrO and BaO,

wherein:

(a) the glass making up the sheets satisfies the following relationships;

(i) Σ

(MgO+CaO+SrO+BaO+3La₂O₃)/(Al₂O₃)≧

1.15, and

(ii) [MgO];

[CaO];

[SrO+BaO]=1±

0.15;

1±

0.15;

1±

0.15,

 

where Al₂O₃, MgO, CaO, SrO, BaO, and La₂O₃ represent the mole percents of the respective oxide components;

(b) the fining is performed without the use of substantial amounts of arsenic; and

(c) a population of 50 sequential glass sheets produced by the downdraw process from the melted and fined batch materials has an average gaseous inclusion level of less than 0.10 gaseous inclusions/cubic centimeter, where each sheet in the population has a volume of at least 500 cubic centimeters.

34. The method of claim 33 wherein the downdraw process comprises a fusion draw process.

35. The method of claim 33 wherein the glass making up the glass sheets satisfies the relationship:

[MgO];

[CaO];

[SrO+BaO]=1±

0.1;

1±

0.1;

1±

0.1.

36. The method of claim 33 wherein the B₂O₃ content of the glass making up the glass sheets is less than or equal to 4.0 mole percent.

37. The method of claim 33 wherein the glass making up the glass sheets has a BaO/SrO ratio in mole percent that is equal to or greater than 2.0.

40. The method of claim 33 further comprising using the glass sheets as substrates for liquid crystal displays.