Coated substrates having undercoating layers that exhibit improved photocatalytic activity
View Patent ↗A coated substrate is disclosed. The coated substrate includes a substrate; an undercoating layer comprising at least one layer selected from a mixture of silica and zirconia; a mixture of silica and alumina; or a mixture of silica, alumina and titania overlaying at least a portion of the substrate; and a functional coating overlaying at least a portion of the undercoating. The coated substrates of the invention exhibit improved properties such as increased durability, photocatalytic activity, etc. as a result of the undercoating layer.
1. A coated substrate comprising:
a glass substrate;
at least one undercoating layer consisting essentially of a mixture of silica and alumina or a mixture of silica and zirconia, wherein the undercoating layer is selected from the group consisting of:
(a) a mixture of silica and alumina having a molar ratio of about 4 moles of silica to about 1 mole of alumina; and
(b) a mixture of silica and zirconia having a molar ratio of about 8 to about 20 moles of silica to about 1 mole of zirconia; and
a photocatalytic functional coating overlaying at least a portion of the undercoating layer, wherein the photocatalytic functional coating comprises titania, and wherein the coated substrate with the undercoating layer has a higher photocatalytic activity than without the undercoating layer.
2. The coated substrate according to claim 1 , wherein the undercoating layer has a thickness ranging from 1 nm to 300 nm.
3. The coated substrate according to claim 1 , wherein the undercoating layer consists essentially of the mixture of silica and alumina.
4. The coated substrate according to claim 3 , wherein the undercoating layer has a thickness of about 104 nm to about 337 nm.
5. The coated substrate according to claim 1 , wherein the substrate is a glass ribbon.
6. The coated substrate according to claim 1 , wherein the coated substrate exhibits the following reflected color coordinates according to the CIE 1967 as measured from the coated side: a* ranging from −20 to 20; b* ranging from −20 to 20; and L* ranging from 40 to 60.
7. The coated substrate according to claim 1 , wherein the undercoating layer has a thickness of about 20 nm to about 73 nm.
8. The coated substrate according to claim 1 , wherein the undercoating layer consists essentially of the mixture of silica and zirconia.
9. A coated substrate comprising:
a glass substrate;
a first undercoating layer overlaying at least a portion of the substrate, the first undercoating layer comprising a first mixture of about 54.8 to about 70.6 volume % of silica and about 29.4 to about 45.2 volume % of zirconia;
a second undercoating layer overlaying at least a portion of the first undercoating layer, the second undercoating layer comprising a second mixture of about 10.3 to about 20.0 volume % of silica and about 80.0 to about 89.7 volume % of zirconia; and
a photocatalytic functional coating overlaying at least a portion of the undercoating layer, wherein the photocatalytic functional coating comprises titania.
10. The coated substrate according to claim 9 , wherein the first undercoating layer has a thickness of about 23.76 nm to about 36.93 nm.
11. The coated substrate according to claim 9 , wherein the second undercoating layer has a thickness of about 40.29 nm to about 56.61 nm.
12. The coated substrate according to claim 9 , wherein the photocatalytic functional coating has a thickness of about 76 nm to about 118 nm.
13. The coated substrate according to claim 9 , wherein the substrate is a glass ribbon.
14. The coated substrate according to claim 9 , wherein the coated substrate exhibits the following reflected color coordinates according to the CIE 1967 as measured from the coated side: a* ranging from −20 to 20; b* ranging from −20 to 20; and L* ranging from 40 to 60.