Heating element, and heatable pane comprising a heating element

• US 9,332,593 B2
• Filed: 01/10/2008
• Issued: 05/03/2016
• Est. Priority Date: 01/26/2007
• Status: Active Grant

• Current Assignee: Tesa SE (Maxingvest AG)
• Original Assignee: Tesa SE (Maxingvest AG)
• Inventors: Keite-Telgenbscher, Klaus, Lhmann, Bernd, Prenzel, Alexander
• Primary Examiner(s): Shamsuzzaman, Mohammed
• Application Number:
  US12/523,583
• Publication Number:
  US 20100059494A1
• Time in Patent Office: 3,036 Days
• Field of Search: 219201-270, 219383-442, 2194431-4682
• US Class Current: 1/1
• CPC Class Codes: H05B 2203/013 Heaters using resistive films or coatings
• CPC Class Codes: H05B 2214/04 Heating means manufactured by using nanotechnology
• CPC Class Codes: H05B 3/12 characterised by the composition or nature of the conductive material
• CPC Class Codes: H05B 3/86 the heating conductors being embedded in the transparent or reflecting material H05B3/845 takes precedence

Abstract

A heating element including a current conductor through which electric power is conducted and electricity converted into heat by a voltage drop across an ohmic resistor. The heating element is a planar or a strip-shaped structure and is provided with at least one support layer and an adhesive layer, while the current conductor is designed as an additional, current-conducting layer which is arranged between the support layer and the adhesive layer. The support layer, the current-conducting layer, and the adhesive layer are transparent.

Claims

1. A heating element comprising:

a backing layer, an adhesive layer, a first current-conducting layer for conducting electrical current, wherein, as a result of a drop in voltage, the electrical current is convertible into heat,

wherein the first current-conducting layer is disposed between the backing layer and the adhesive layer,

wherein the backing layer, the adhesive layer and the first current-conducting layer form a transparent structure,

wherein the heating element is in the form of a planar structure defined by a plane,

wherein a portion of the first current-conducting layer directly contacts the adhesive layer, and electrical contacts are located at edges of first current-conducting layer apart from the adhesive layer and covered with electrically conductive layer with a greater electrical conductivity than the electrical contacts;

wherein each of the backing layer, the adhesive layer and the first current-conducting layer is transparent, the first current-conducting layer comprises carbon nanotubes, and a drop of voltage results in substantially uniform heating throughout the planar structure;

wherein a temperature difference in the plane of the planar structure, apart from marginal regions in a region of contacting, is no greater than 20% of a maximum final temperature attained in the plane of the planar structure.

2. The heating element according to claim 1, wherein the carbon nanotubes are embedded in a transparent matrix.

3. The heating element according to claim 2, wherein the transparent matrix has a polymeric binder.

4. The heating element according to claim 1, wherein the backing layer is configured such that the heating element, as a whole, is flexible.

5. The heating element of claim 1, wherein the first current conductive layer has regions of varying electrical resistance providing different heating power.

6. The heating element of claim 2, wherein the transparent matrix is prepared from at least one monomer selected such that the resulting polymer is a pressure-sensitive adhesive.

7. The heating element of claim 2, wherein the transparent matrix material is a pressure-sensitive acrylate adhesive.

8. The heating element of claim 1, wherein the carbon nanotubes have an average length of at least 10 μ

m.

9. The heating element of claim 8, wherein the carbon nanotubes have an average outer diameter of less than 40 nm.

10. The heating element of claim 8, wherein the carbon nanotubes have an average ratio of length to outer diameter of at least 250.

11. The heating element of claim 8, wherein at least one surface of the carbon nanotubes is chemically modified.

12. The heating element of claim 8, wherein the carbon nanotubes are single-walled.

13. The heating element of claim 8, wherein the carbon nanotubes are multi-walled.

14. The heating element of claim 1, wherein the carbon nanotubes comprise a plurality of nanotubes positioned in the direction of the current flow directed by positions of contact electrodes.

15. The heating element of claim 1, wherein the first current-conducting layer further comprises an intrinsically conductive polymer.

16. The heating element of claim 1, wherein the adhesive layer is designed as a self-adhesive layer.

17. The heating element of claim 16, wherein the self-adhesive layer is an acrylate adhesive layer.

18. The heating element of claim 16, wherein the self-adhesive layer is a styrene block copolymer adhesive layer.

19. The heating element of claim 16, wherein the self-adhesive layer has a transparency of greater than 70%.

20. The heating element of claim 1, wherein the first current-conducting layer has a transparency of not more than 80%.

21. The heating element according to claim 14, wherein the first current-conducting layer has regions of varying concentration and/or types of carbon nanotubes.

22. The heating element of claim 1, wherein the first current-conducting layer contains a binder prepared from a solution or dispersion in an organic solvents or in water.

23. The heating element of claim 15, wherein the first current-conducting layer comprises conductive components.

24. The heating element of claim 23, wherein the conductive components are intrinsically conductive polymers.