Fining agents for silicate glasses

• US 8,158,543 B2
• Filed: 02/25/2009
• Issued: 04/17/2012
• 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): Group, Karl
• Assistant Examiner(s): Bolden, Elizabeth A
• Application Number:
  US12/392,577
• Publication Number:
  US 20090215607A1
• Time in Patent Office: 1,147 Days
• Field of Search: 501/27, 501 55- 79, 651341-1349, 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: 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, the silicate glass having a seed concentration of less than about 1 seed/cm³, 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;

0-8 mol % MgO;

0-10 mol % CaO;

0-5 mol % ZrO₂;

0-1 mol % SnO₂;

0-1 mol % CeO₂;

less than 50 ppm As₂O₃; and

less than 50 ppm Sb₂O₃;

wherein 12 mol %≦

Li₂O+Na₂O+K₂O≦

20 mol % and 0 mol %≦

MgO+CaO≦

10 mol %, wherein the silicate glass is formed from a batch or raw materials that includes at least one fining agent, wherein the fining agent comprises at least one inorganic compound and is substantially free of antimony and arsenic.

2. The silicate glass according to claim 1, wherein the silicate glass is down-drawable and ion exchangeable.

3. The silicate glass according to claim 2, wherein the silicate glass, when ion exchanged, has a surface compressive stress of at least about 200 MPa and a surface compressive layer having a depth of at least about 30 μ

m.

4. The silicate glass according to claim 1, wherein the silicate glass forms a cover plate for a mobile electronic device.

5. The silicate glass according to claim 1, wherein the silicate glass is substantially free of seeds.

6. The silicate glass according to claim 1, wherein the silicate glass has a liquidus viscosity of at least 100 kilopoise.

7. The silicate glass according to claim 6, wherein the silicate glass has a liquidus viscosity of at least 220 kilopoise.

8. The silicate glass according to claim 3, wherein surface compressive stress is at least 600 MPa.