Transparent glass ceramic and cover pane

Patent metadata

Field	Value
Publication number	US-12466765-B2
Application number	US-202318542213-A
Country	US
Kind code	B2
Filing date	Dec 15, 2023
Priority date	Dec 16, 2022
Publication date	Nov 11, 2025
Grant date	Nov 11, 2025

Abstract

A transparent, chemically prestressable or chemically prestressed glass ceramic has a high transmittance, a low haze and a high crystal phase content of keatite solid solution. A method of making such a glass ceramic includes producing a silicate green glass with a melting process and subsequent hot shaping, temperature treating the silicate green glass with at least one nucleation step carried out in the temperature range of 690° C. to 850° C. for a period of 5 min to 72 h and at least one ceramization step carried out in the temperature range of 780° C. to 1100° C. for a period of 3 min to 150 h, and performing at least one ion exchange in an exchange bath at a temperature of the exchange bath between 370° C. and 500° C. for a period of between 2 hours and 50 hours.

First claim

What is claimed is:

1 . A glass ceramic that is transparent and chemically prestressable or chemically prestressed with keatite as the main crystal phase, the glass ceramic comprising:
a transmittance of τ vis ≥85% at a thickness of 0.7 mm, a haze value≤5, and a crystal phase content of at least 80% by weight of keatite solid solution based on all crystal phases in the glass ceramic.

2 . The glass ceramic according to claim 1 , further comprising: a total content of SiO 2 , Al 2 O 3 and Li 2 O that is 85% or more in percent by weight of the glass ceramic, wherein SnO 2 and ZrO 2 are nucleating agents.

3 . The glass ceramic according to claim 2 , wherein the SiO 2 content is 58 to 72% by weight.

4 . The glass ceramic according to claim 2 , wherein the Al 2 O 3 content is 18 to 23% by weight.

5 . The glass ceramic according to claim 2 , wherein the Li 2 O content is 2 to 5.5% by weight.

6 . The glass ceramic according claim 2 , wherein the content of SnO 2 is 1 to 2% by weight, and/or the content of ZrO 2 is 2.1 to 3% by weight.

7 . The glass ceramic according to claim 2 , further comprising a ratio of the Al 2 O 3 to the SiO 2 that is <0.33.

8 . The glass ceramic according to claim 2 , further comprising: 0 to 2% by weight of B 2 O 3 .

9 . The glass ceramic according to claim 2 , further comprising: less than 2% by weight of P 2 O 5 .

10 . The glass ceramic according to claim 2 , further comprising less than 2% by weight of a total content of Na 2 O and K 2 O.

11 . The glass ceramic according to claim 2 , further comprising a total content of MgO, Li 2 O, SrO, CaO, and BaO according to the expression: MgO+Li 2 O—SrO—CaO—BaO is <5% by weight.

12 . The glass ceramic according to claim 2 , further comprising 0.1 to 2% by weight of MgO.

13 . The glass ceramic according to claim 2 , further comprising a total content of MgO and Li 2 O that is less than 5.5% by weight.

14 . The glass ceramic according to claim 2 , further comprising 0-2% by weight of BaO and/or 0-2% by weight of CaO and/or 0-2% by weight of SrO.

15 . The glass ceramic according to claim 2 , further comprising 0 to 2% by weight of ZnO.

16 . The glass ceramic according to claim 2 , further comprising a total content of ZrO 2 and SnO 2 that is >3.6% by weight.

17 . The glass ceramic according to claim 1 , wherein the glass ceramic is substantially free of TiO 2 .

18 . The glass ceramic according claim 1 , wherein the glass ceramic is substantially free of V 2 O 5 , Nd 2 O 3 , and CoO.

19 . The glass ceramic according to claim 1 , further comprising up to 2% of one or more fining agents selected from the group consisting of: As 2 O 3 , Sb 2 O 3 , a halide, and SO 3 .

20 . A cover pane, the cover pane comprising:
a thickness of 0.4 mm to 1 mm; and the glass ceramic according to claim 1 , wherein the glass ceramic is a prestressed glass ceramic.

21 . A display device comprising:
a digital display; the cover pane according to claim 20 , wherein the cover pane covers the digital display.

22 . A method for producing a prestressed glass ceramic, further comprising the steps of: producing a silicate green glass by a melting process and subsequent hot shaping; temperature treating the silicate green glass with at least one nucleation step carried out in a temperature range of 690° C. to 850° C. for a period of 5 minutes to 72 hours and at least one ceramization step carried out in a temperature range of 780° C. to 1100° C. for 3 minutes to 150 hours; performing at least one ion exchange in an exchange bath having a composition of: 100% by weight to 0% by weight KNO 3 , 0% by weight to 100% by weight NaNO 3 , and 0% by weight to 5% by weight LiNO 3 at a temperature of the exchange bath between 370° C. and 500° C. and for between 2 hours and 50 hours.

23 . The method according to claim 22 , wherein the hot shaping comprises floating, rolling, drawing or ingot casting.

Assignees

• Schott Ag

Inventors

• Schneider Meike
• Rüdinger Bernd
• Martens Uwe

Classifications

• H05K5/03

  Covers · CPC title

• C03C2204/00

  Glasses, glazes or enamels with special properties · CPC title

• C03C21/002

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

• C03C10/0054

  containing PbO, SnO2, B2O3 · CPC title

• C03B32/02

  Thermal crystallisation, e.g. for crystallising glass bodies into glass-ceramic articles {(C03B27/012 takes precedence)} · CPC title