Heated planar element
View Patent ↗The invention provides a planar element which is intrinsically heatable and which is particularly suitable for attachment to multi-dimensionally curved surfaces. For this purpose the planar element features particularly high deformability, achieved in accordance with the invention through a planar element having a layer sequence comprising a heating layer and a contacting layer, each of these two layers being composed of a polymeric material based on elastomers and/or on plastic polymers which have a particular elongation at break and at the same time a particular tensile elasticity modulus. Furthermore, the invention provides an adhesively bonded assembly comprising a bonding substrate and a planar element of the aforesaid kind, a method of producing a planar element of the aforesaid kind, and the use of such a planar element for heating an adhesively bonded assembly.
1. Self-adhesive planar element comprising a heating layer and a contacting layer, the heating layer being in contact with one of two side faces of the contacting layer and being in electrically conducting communication therewith, and being composed of an intrinsically heatable first polymeric material formed as a conductor which heats up when an electric current is passed through, wherein the contacting layer is comprised of an electrically conducting second polymeric material, the first polymeric material and the second polymeric material each being a polymeric material based on elastomers and/or on plastic polymers, and each having, at a stretching velocity of 300 mm/min and a temperature of 23° C., an elongation at break of more than 20%, and further possessing a tensile elasticity modulus of less than 1000 MPa.
2. The self-adhesive planar element according to claim 1 , wherein at least one the first or second polymeric material is a self-adhesive.
3. The self-adhesive planar element according to claim 2 , wherein the self-adhesive is a pressure-sensitive adhesive based on acrylates and/or methacrylates, polyurethanes, natural rubbers, synthetic rubbers and/or silicones.
4. The self-adhesive planar element according to claim 2 , wherein the self-adhesive is a hotmelt adhesive based on polyolefins and copolymers of polyolefins and/or on their acid-modified derivatives, on ionomers, on thermoplastic polyurethanes, on polyamides and their copolymers and/or on block copolymers.
5. The self-adhesive planar element according to claim 1 , wherein the planar element further comprises a layer of adhesive comprising a self-adhesive, which is in contact with the other of the two side faces of the contacting layer.
6. The self-adhesive planar element according to claim 1 , wherein the first polymeric material is a posistor.
7. The self-adhesive planar element according to claim 1 , wherein the second polymeric material is not a posistor.
8. The self-adhesive planar element according to claim 1 , wherein the electrical resistance of the contacting layer is less than one tenth of the electrical resistance of the heating layer.
9. The self-adhesive planar element according to claim 1 , wherein the electrical resistance of the contacting layer, when the contacting layer is stretched by more than 20% goes up by not more than three times.
10. The self-adhesive planar element according to claim 1 , wherein the contacting layer has a branched comb structure or finger structure.
11. The self-adhesive planar element according to claim 1 , wherein at least one of the first or second polymeric material comprise at least one electrically conducting filler.
12. The self-adhesive planar element according to claim 11 , wherein the electrically conducting filler is selected from the group consisting of metal particles, graphite, carbon nanoparticles carbon black, and conductive carbon black.
13. The self-adhesive planar element according to claim 1 , wherein the planar element is of carrier-free form.
14. The self-adhesive planar element according to claim 1 , wherein the planar element comprises a carrier which, at a stretching velocity of 300 mm/min and a temperature of 23° C., has an elongation at break of more than 20%, and further has a tensile elasticity modulus of less than 1000 MPa.
15. Adhesively bonded assembly comprising a bonding substrate and a planar element according to claim 1 , wherein the bonding substrate is a viewing sheet or mirror sheet.
16. The self-adhesive planar element of claim 1 wherein the polymeric materials have, at a stretching velocity of 300 mm/min and a temperature of 23° C., and elongation at break of more than 50%.
17. The self-adhesive planar element of claim 1 wherein the tensile elasticity modulus is not more than 100 MPa.
18. The self-adhesive planar element of claim 4 wherein the block copolymer is a styrene block copolymer.