Flexible foam resistive heaters and methods of making flexible resistive heaters
Flexible foam resistive heaters prepared with conductive coatings are described. The invention also includes methods of making flexible lead (busbar) connections with low contact resistance for superior uniformity and lower power utilization than conventional technology.
1. A resistively-heatable flexible, foam, comprising:
a flexible, polymeric solid foam;
a resistively-heatable CNT, graphene, or graphene oxide layer disposed on the exterior and at least partly within the foam;
wherein the resistively-heatable layer is characterizable by an average resistance of 10 to 200 ohms/square as measurable on the surface of the resistively-heatable layer with a 4 point probe; and a polymeric film disposed over the CNT, graphene, or graphene oxide layer.
2. The resistively-heatable flexible, foam of claim 1 , further comprising a composition disposed within the foam and in thermal contact with the resistively-heatable CNT layer; wherein the composition is a composition which, when heated, generates a gas or aerosol.
3. The resistively-heatable flexible, foam of claim 2 , wherein the heat releasable composition comprises a chemoattractant.
4. The resistively-heatable flexible, foam of claim 3 , wherein the heat releasable composition comprises octenol.
5. The resistively-heatable flexible, foam of claim 1 , further comprising a heat releasable composition adsorbed on the polymeric film; wherein the heat releasable composition is a composition which, when heated, generates a gas or aerosol.
6. A fragrance-releasing wall plug comprising the foam of claim 2 wherein the heat releasable composition comprises a fragrance; wherein the heat releasable composition is a composition which, when heated, generates a gas or aerosol.
7. An inhaler, comprising the foam of claim 2 wherein the heat releasable composition comprises a drug or prodrug; wherein the heat releasable composition is a composition which, when heated, generates a gas or aerosol.
8. The resistively-heatable flexible, foam of claim 1 , wherein the resistively-heatable CNT, graphene, or graphene oxide layer comprises at least 2 mm into the foam.
9. The resistively-heatable flexible, foam of claim 8 , wherein the resistively-heatable CNT, graphene, or graphene oxide layer has a thickness of at least 1 cm wherein at least 90 mass % of the CNTs are in the outermost 5 mm.
10. The resistively-heatable flexible, foam of claim 1 , wherein the resistively-heatable CNT, graphene, or graphene oxide layer is in the form of a sheet having a width in the range of 0.5 to 5 m, length of at least 1 m, and thickness of at least 1 cm.
11. The resistively-heatable flexible, foam of claim 1 , wherein the resistively-heatable CNT, graphene, or graphene oxide layer is covered with an elastomeric dielectric film having a thickness in the range of 10 μm to 3 mm.
12. An article comprising the resistively-heatable flexible, foam of claim 1 , wherein the article is selected from the group consisting of: pillow, blanket, mattress, operating room table, guerney cover, seat warmer, heatable clothing, diving undergarment, and wound healing cover.
13. The article of claim 12 comprising at least two electrical leads attached to the foam and electrically connected to the resistively-heatable layer.
14. A resistively-heatable flexible, foam, comprising:
a flexible, polymeric solid foam;
a resistively-heatable layer disposed on the exterior and at least partly within the foam;
at least two electrical leads attached to the foam and electrically connected to the resistively-heatable layer; and further characterizable by: a surface hardness, measured according to ASTM D2240 on the exterior of the heatable flexible foam that is nearest the heatable layer, of 10 to 50; the leads having a contact resistance of 50 to 600 ohms when current is applied to the electrodes; the exterior having an average surface resistance of 10 to 200 ohms; a power density of 0.1 to 0.5 W/in 2 necessary to increase the average temperature of the resistively-heatable layer from 75° F. (24 C.) to 107° F. (41.7° C.); and/or where the electrical leads are separated by at least three inches and having a maximum variation of temperature between the leads of 20° F. (16.7° C.) or less of the resistively-heatable layer when the average temperature of the resistively-heatable layer between the leads is raised to 107° F. (41.7° C.).
15. The resistively-heatable flexible, foam of claim 14 where the exterior of the heatable flexible foam that is nearest the heatable layer, having a surface hardness of 20 to 40.
16. The resistively-heatable flexible, foam of claim 14 wherein the leads have a contact resistance of 50 to 400 ohms when current is applied to the electrodes sufficient to raise the temperature of the layer to 107° F. (41.7° C.).
17. The resistively-heatable flexible, foam of claim 15 wherein the electrical leads are separated by at least five inches and wherein a maximum variation of temperature between the leads and a surface of the heated area is 20° F. (11.1° C.) or less when the average temperature of the layer is raised to 107° F. (41.7° C.).
18. The resistively-heatable flexible, foam of claim 14 characterizable by a power density of 0.2 to 0.4 W/in 2 necessary to increase the average temperature of the layer from 75° F. (24 C.) to 107° F. (41.7° C.).
19. The resistively-heatable flexible, foam of claim 14 characterizable by electrical leads that are separated by at least five inches and wherein a maximum variation of temperature between the leads and a surface of the heated area is 20° F. (11.1° C.) or less when the average temperature of the layer is raised to 107° F. (41.7° C.).