Reverse photochromic borosilicate glasses

Patent metadata

Field	Value
Publication number	US-10487003-B2
Application number	US-201615347066-A
Country	US
Kind code	B2
Filing date	Nov 9, 2016
Priority date	Oct 9, 2013
Publication date	Nov 26, 2019
Grant date	Nov 26, 2019

Abstract

Borosilicate glasses are disclosed having (in weight %) 66-76% SiO2, 0-8% Al2O3, 10-18% B2O3, 0-4% Li2O, 0-12% Na2O, 0-12% K2O, 1-1.5% Ag, 1.5-2.5% Cl− and 0.01-0.06% of a summed amount of CuO and NiO, wherein the glass composition is bleachable upon exposure to ultraviolet irradiation from a stable state color or shade to a lighter color or shade. Such reverse photochromic borosilicate glass compositions may be thermally darkenable. The borosilicate glasses may be strengthened via ion-exchange strengthening treatment. The borosilicate glasses may retain their reverse photochromic and thermally darkenable properties even after ion-exchange strengthening treatment.

First claim

What is claimed is:

1. A photochromic borosilicate glass composition comprising (in weight %) 66-76% SiO 2 , 0-8% Al 2 O 3 , 10-18% B 2 O 3 , 0-4% Li 2 O, 0-12% Na 2 O, 0-12% K 2 O, 1-1.5% Ag, 1.5-2.5% Cl − , and 0.01-0.06% of a summed amount of CuO and NiO, wherein the glass composition is substantially free of Br − and is bleachable upon exposure to ultraviolet irradiation from a stable state color or shade to a lighter color or shade.

2. The photochromic borosilicate glass composition of claim 1 wherein the glass is thermally darkenable.

3. The photochromic borosilicate glass composition of claim 2 wherein the glass composition is thermally darkenable at a temperature of 150° C. or greater.

4. The photochromic borosilicate glass composition of claim 1 comprising 2-12% Na 2 O.

5. The photochromic borosilicate glass composition of claim 1 which is substantially free of Li 2 O.

6. The photochromic borosilicate glass composition of claim 1 comprising 2-8% Al 2 O 3 , 4-12% Na 2 O, and 0-6% K 2 O, wherein the weight % of Na 2 O is greater than the weight % of K 2 O.

7. The photochromic borosilicate glass of claim 6 which is substantially free of Li 2 O.

8. The photochromic borosilicate glass composition of claim 1 comprising 68.6-71.6% SiO 2 , 3-6% Al 2 O 3 , 13.4% B 2 O 3 , 4.5-9% Na 2 O, 0-4.5% K 2 O, 1.2% Ag, 1.8% Cl − and 0.03% CuO, wherein the weight % of Na 2 O is greater than the weight % of K 2 O and the composition is substantially free of Li 2 O.

9. The photochromic borosilicate glass composition of claim 1 wherein immersion of the photochromic borosilicate glass composition in a molten salt bath for a predetermined time and temperature causes ion-exchange, and after ion-exchange, the glass composition is bleachable upon exposure to ultraviolet irradiation from a stable state color or shade to a lighter color or shade.

10. A multi-layer glass laminate comprising a substrate layer and a photochromic borosilicate glass layer disposed on both sides of the substrate layer and comprising the photochromic borosilicate glass composition of claim 1 .

11. A multi-layer glass laminate, wherein one or more layers of the multi-layer glass laminate comprises the photochromic borosilicate glass composition of claim 1 .

12. A method comprising:
immersing in a molten salt bath the photochromic borosilicate glass composition of claim 1 for a time and at a temperature sufficient to cause ion-exchange.

13. The method of claim 12 wherein the photochromic borosilicate glass is substantially free of Li 2 O.

14. The method of claim 12 , wherein the molten salt bath comprises KNO 3 , the time is about 6 hours to about 10 hours, and the temperature is about 350° C. to about 450° C.

15. The method of claim 12 , wherein after the ion-exchange, the photochromic borosilicate glass is bleachable upon exposure to ultraviolet irradiation from a stable state color or shade to a lighter color or shade.

16. The method of claim 12 , wherein after the ion-exchange, the photochromic borosilicate glass comprises a compressive stress of at least about 250 MPa.

17. The method of claim 12 , wherein after the ion-exchange, the photochromic borosilicate glass comprises a compressive stress of at least about 400 MPa.

18. The method of claim 12 , wherein after the ion-exchange, the photochromic borosilicate glass comprises a depth of compressive layer of at least about 15 microns.

19. The method of claim 12 , wherein:
the photochromic borosilicate glass comprises (in weight %) 2-8% Al 2 O 3 and 2-12% Na 2 O; and
the weight % of Na 2 O in the photochromic borosilicate glass is greater than the weight % of K 2 O in the photochromic borosilicate glass.

20. A photochromic borosilicate glass composition comprising (in weight %) 66-76% SiO 2 , 2-8% Al 2 O 3 , 10-18% B 2 O 3 , 0-4% Li 2 O, 2-12% Na 2 O, 0-12% K 2 O, 1-1.5% Ag, 1.5-2.5% Cl − , and 0.01-0.06% of a summed amount of CuO and NiO, wherein the photochromic borosilicate glass composition is substantially free of Br − , exhibits a lightening in color or shade when exposed to ultraviolet irradiation, and is thermally darkenable.

Assignees

• Corning Inc

Inventors

• Mauro John Christopher
• Thirion Lynn Marie

Classifications

• C03C23/002

  by ultraviolet light · CPC title

• B32B17/06

  comprising glass as the main or only constituent of a layer, next to another layer of a specific {material} · CPC title

• C03C4/06

  for phototropic or photochromic glass · CPC title

• C03C2218/152

  by cvd · CPC title

• C03C8/02

  Frit compositions, i.e. in a powdered or comminuted form · CPC title