PANE HAVING HEATABLE TCO COATING

Abstract

A pane having a heatable coating, includes a substrate and a heatable coating on an exposed surface of the substrate, which heatable coating at least includes an electrically conductive layer, which contains a transparent, electrically conductive oxide (TCO) and has a thickness of 1 nm to 40 nm, and above the electrically conductive layer, a dielectric barrier layer for regulating oxygen diffusion, which dielectric barrier layer contains a metal, a nitride, or a carbide and has a thickness of 1 nm to 20 nm, wherein the pane has transmittance in the visible spectral range of at least 70% and the coating has sheet resistance of 50 ohms/square to 200 ohms/square.

Claims

1. Pane having a heatable coating, comprising a substrate and a heatable coating on an exposed surface of the substrate, which heatable coating at least comprises an electrically conductive layer, which contains a transparent, electrically conductive oxide and has a thickness of 1 nm to 40 nm, and above the electrically conductive layer, a dielectric barrier layer for regulating oxygen diffusion, which dielectric barrier layer contains a metal, a nitride, or a carbide and has a thickness of 1 nm to 20 nm, wherein the pane has transmittance in the visible spectral range of at least 70% and the coating has sheet resistance of 50 ohms/square to 200 ohms/square.

2. The pane according to claim 1, wherein the electrically conductive layer contains indium tin oxide.

3. The pane according to claim 1, wherein the electrically conductive layer has a thickness of 10 nm to 35 nm.

4. The pane according to claim 1, wherein the barrier layer contains silicon nitride or silicon carbide.

5. The pane according to claim 1, wherein the barrier layer has a thickness of 2 nm to 10 nm.

6. The pane according to claim 1, wherein the coating contains an optical matching layer below the electrically conductive layer and an antireflection layer above the barrier layer and wherein the optical matching layer and the antireflection layer have a refractive index of 1.3 to 1.8.

7. The pane according to claim 6, wherein the optical matching layer and/or the antireflection layer contains at least one oxide.

8. The pane according to claim 6, wherein the optical matching layer has a thickness of 5 nm to 50 nm, and wherein the antireflection layer has a thickness of 10 nm to 100 nm.

9. The pane according to claim 1, wherein the coating contains, below the electrically conductive layer, a blocking layer against alkali diffusion.

10. The pane according to claim 9, wherein the blocking layer contains silicon nitride.

11. The pane according to claim 9, wherein the blocking layer has a thickness of 5 nm to 50 nm.

12. The pane according to claim 1, wherein the substrate is a thermally prestressed glass pane.

13. Method for producing a pane having a heatable coating, comprising (a) successively applying on a surface of a substrate at least an electrically conductive layer that contains a transparent, electrically conductive oxide and has a thickness of 1 nm to 40 nm, and a dielectric barrier layer for regulating oxygen diffusion that contains at least a metal, a nitride, or a carbide; (b) subjecting the substrate with the coating to a temperature treatment at at least 100° C., after which the pane has transmittance in the visible spectral range of at least 70% and the coating has sheet resistance of 50 ohms/square to 200 ohms/square.

14. The method according to claim 13, wherein the temperature treatment is done in the context of thermal prestressing.

15. A method comprising utilizing a pane according to claim 1 with an operating voltage of 40 V to 250 V as a refrigerator door, oven door, partition, bathroom mirror, or window.

16. The pane according to claim 4, wherein the barrier layer contains silicon nitride.

17. The pane according to claim 7, wherein the at least one oxide is a silicon oxide that is optionally aluminum-doped, zirconium-doped, or boron-doped.

18. The pane according to claim 8, wherein the optical matching layer has a thickness of 5 nm to 30 nm, and wherein the antireflection layer has a thickness of 15 nm to 50 nm.

19. The pane according to claim 10, wherein the blocking layer contains silicon nitride that is optionally aluminum-doped, zirconium-doped, or boron-doped.

20. The pane according to claim 11, wherein the blocking layer has a thickness of 5 nm to 30 nm.

Description

[0043] They depict:

[0044] FIG. 1 a cross-section through an embodiment of the pane according to the invention having a heatable coating,

[0045] FIG. 2 a flowchart of an embodiment of the method according to the invention.

[0046] FIG. 1 depicts a cross-section through an embodiment of the pane according to the invention with the substrate 1 and the heatable coating 2. The substrate 1 is, for example, a glass pane made of soda lime glass and has a thickness of 4 mm. The pane is, for example, a component of a refrigerator door. The coating is applied on the refrigerator-side surface of the pane. When the coating is heated, condensation on the outer surface of the refrigerator door as well as condensation and icing on the refrigerator-side surface can be removed. The pane can be a component of an insulating glazing unit, in particular the outer pane of an insulating glazing unit such that the coating 2 is arranged protected in the interior of the glazing unit.

[0047] The coating 2 comprises, starting from the substrate 1, a blocking layer 7 against alkali diffusion, an optical matching layer 3, an electrically conductive layer 4, a barrier layer 5 for regulating the oxygen diffusion layer 5, and an antireflection layer 6. The materials and the layer thicknesses are summarized in Table 1. The individual layers of the coating 2 were deposited by magnetron-enhanced cathodic sputtering.

TABLE-US-00001 TABLE 1 Layer Reference No. Material Thickness Antireflection layer 6 2 SiO.sub.2:Al 20 nm Barrier layer 5 Si.sub.3N.sub.4:Al 10 nm Electrically conductive layer 4 ITO 22 nm Optical matching layer 3 SiO.sub.2:Al 11 nm Blocking layer 7 Si.sub.3N.sub.4:Al  5 nm Substrate 1 Glass .sup. 4 mm

[0048] Despite the low thickness of the conductive layer 4, it was possible to obtain a good heating effect with the coating 2, connected to a voltage source of 230 V. The coating 2 also proved to be corrosion resistant and stable over the long-term on the exposed refrigerator-side surface of the substrate 1.

[0049] FIG. 2 depicts a flowchart of an exemplary embodiment of the production method according to the invention.

EXAMPLES

[0050] Various coatings 2 were produced and investigated. The materials and layer thicknesses of the Examples 1 to 3 are presented in Table 2. The transmittance T.sub.L and reflectivity R.sub.L in the visible spectral range as well as the sheet resistance R.sub.sq are summarized in Table 3.

TABLE-US-00002 TABLE 2 Thickness Reference No. Material Example 1 Example 2 Example 3 2 6 SiO.sub.2:Al 20 nm 25 nm 38 nm 5 Si.sub.3N.sub.4:Al 10 nm 10 nm 10 nm 4 ITO 22 nm 27 nm 32 nm 3 SiO.sub.2:Al 11 nm 11 nm 11 nm 7 Si.sub.3N.sub.4:Al  5 nm  5 nm  5 nm 1 Glass .sup. 4 mm .sup. 4 mm .sup. 4 mm

TABLE-US-00003 TABLE 3 T.sub.L/% R.sub.L/% R.sub.sq/Ohm Example 1 83.9 13.2 81 Example 2 83.4 13.8 63 Example 3 83.7 13.5 55

[0051] The coatings of the Examples 1 to 3 had high transmittance and low reflectivity such that they do not critically reduce vision through the glass pane. In addition, their sheet resistance was suitable for obtaining a good heating effect with a voltage supply of approx. 230 V. The fact that this can be obtained with such thin conductive ITO layers 4 was unexpected and surprising for the person skilled in the art.

LIST OF REFERENCE CHARACTERS

[0052] (1) substrate [0053] (2) heatable coating [0054] (3) optical matching layer [0055] (4) electrically conductive layer [0056] (5) barrier layer for regulating oxygen diffusion [0057] (6) antireflection layer [0058] (7) blocking layer against alkali diffusion