Fining agents for silicate glasses

• US 9,073,779 B2
• Filed: 01/02/2014
• Issued: 07/07/2015
• Est. Priority Date: 02/26/2008
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Dejneka, Matthew John, Gomez, Sinue
• Primary Examiner(s): Green, Anthony J
• Assistant Examiner(s): Bolden, Elizabeth A
• Application Number:
  US14/146,377
• Publication Number:
  US 20140113798A1
• Time in Patent Office: 551 Days
• US Class Current: 1/1
• CPC Class Codes: C03B 17/064 by the overflow downdraw fusion process; Isopipes therefor
• CPC Class Codes: C03B 5/225 Refining C03B5/18 takes precedence ; Refining agents C03C1/004
• CPC Class Codes: C03C 1/004 Refining agents refining C03B5/225
• CPC Class Codes: C03C 14/008 the non-glass component being in molecular form
• CPC Class Codes: C03C 21/002 to perform ion-exchange between alkali ions C03C21/005 takes precedence
• 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 3/095 containing rare earths
• CPC Class Codes: Y02A 40/28 specially adapted for farming
• CPC Class Codes: Y10T 428/315 Surface modified glass [e.g., tempered, strengthened, etc.]

Abstract

A fining agent for reducing the concentration of seeds or bubbles in a silicate glass. The fining agent includes at least one inorganic compound, such as a hydrate or a hydroxide that acts as a source of water. In one embodiment, the fining agent further includes at least one multivalent metal oxide and, optionally, an oxidizer. A fusion formable and ion exchangeable silicate glass having a seed concentration of less than about 1 seed/cm³ is also provided. Methods of reducing the seed concentration of a silicate glass, and a method of making a silicate glass having a seed concentration of less than about 1 seed/cm³ are also described.

Claims

1. A silicate glass composition comprising an aluminosilicate glass composition wherein the mol % R₂O>

mol % Al₂O₃, where mol % R₂O=mol % Li₂O+ mol % Na₂O+ mol % K₂O, wherein the silicate glass composition comprises;

a fining agent comprising;

a multivalent metal oxide; and

an oxidizer,

wherein the fining agent is a water source at a temperature at which a silicate glass melt is formed, wherein the water vaporizes and expands existing bubbles in the silicate glass melt and allows the expanded bubbles to rise to the surface of the silicate glass melt and escape the silicate glass melt resulting in a silicate glass comprising less than about 1 seed/cm³, and wherein the fining agent comprises less than 50 ppm arsenic.

2. The silicate glass composition of claim 1, wherein the oxidizer comprises sodium nitrate.

3. The silicate glass of claim 1, wherein the fining agent comprises up to about 4 mol % oxidizer.

4. The silicate glass composition of claim 1, wherein the multivalent metal oxide further comprises CeO₂.

5. The silicate glass composition of claim 4, wherein the fining agent comprises from about 0.05% to about 0.25 mol % CeO₂.

6. The silicate glass composition of claim 1, wherein the multivalent metal oxide comprises SnO₂.

7. The silicate glass composition of claim 6, wherein the fining agent comprises from about 0.05% to about 0.25 mol % SnO₂.

8. The silicate glass composition of claim 1, wherein the fining agent further comprises sodium sulfate.

9. The silicate glass composition of claim 1, wherein the fining agent further comprises one or more components selected from the group consisting of at least one metal hydrate, at least one metal oxide, and combinations thereof.

10. The silicate glass composition of claim 9, wherein the at least one metal hydrate includes one or more selected from the group consisting of clay, zeolites, mica, and combinations thereof.

11. The silicate glass composition of claim 9, wherein the at least one metal oxide includes one or more selected from the group consisting of an aluminum hydroxide, an alkali metal hydroxide, an alkaline earth metal hydroxide, zirconium hydroxide, and combinations thereof.

12. The silicate glass composition of claim 1, wherein the fining agent comprises less than 50 ppm antimony.

13. The silicate glass composition of claim 1, wherein the silicate glass comprises:

60-72 mol % SiO₂;

6-14 mol % Al₂O₃;

0-15 mol % B₂O₃;

0-1 mol % Li₂O;

0-20 mol % Na₂O;

0-10 mol % K₂O;

0-10 mol % CaO; and

0-5 mol % ZrO₂;

wherein 12 mol %≦

Li₂O+Na₂O+K₂O≦

20 mol %.

14. The silicate glass composition of claim 13, wherein the silicate glass comprises 0-8 mol % MgO.

15. The silicate glass composition of claim 14, wherein the silicate glass comprises 0 mol %≦

MgO+CaO≦

10 mol.

16. The silicate glass composition of claim 13, wherein the silicate glass comprises 8-18 mol % Na₂O.