Method of forming fluoropolymer binders for carbon nanotube-based transparent conductive coatings
This invention relates to flexible, transparent and conductive coatings and films formed using carbon nanotubes (CNT) and, in particular, single wall CNT, with polymer binders. Preferably, coatings and films are formed from CNT applied to transparent substrates forming one or multiple conductive layers at nanometer level of thickness. Polymer binders are applied to the CNT network coating having an open structure to provide protection through infiltration, and may comprise a basecoat, a topcoat, or a combination thereof, providing enhanced optical transparency, conductivity, moisture resistance, thermal resistance, abrasion resistance and interfacial adhesion. Polymers may be thermoplastics, thermosets, insulative, conductive or a combination thereof. A fluoropolymer containing binder is applied onto a CNT-based transparent conductive coating at nanometer level of thickness on a clear substrate. The fluoropolymers or blend can be either semi-crystalline or amorphous. This binder coating and the resulting products can be used for display and electronic applications.
1. A method of forming a conductive optically transparent coating or film comprising applying to a substrate a layer of carbon nanotubes having an open structure and a separate layer of a applying another layer of material to said carbon nanotube layer that interpenetrates and compresses said carbon nanotubes and increases sheet conductivity across a surface of said conductive film.
2. The method of claim 1 , wherein the coating or film has a transmittance value to light at 550 nm of greater than 65%.
3. The method of claim 2 , wherein the transmittance value is greater than 90%.
4. The method of claim 2 , wherein the transmittance value to light at 550 nm is greater than the corresponding transmittance value of the coating or film without said binder.
5. The method of claim 2 , wherein the transmittance value is at least 5% greater than the corresponding transmittance value of the coating or film without said binder.
6. The method of claim 5 , wherein the transmittance value is up to 50% greater than the corresponding transmittance value of the coating or film without said binder.
7. A method of increasing the conductivity of a conductive film comprising: applying a layer of carbon nanotubes having an open structure to a surface to form a conductive film; applying another layer of material to said carbon nanotube layer that interpenetrates and compresses said carbon nanotubes and increases sheet conductivity across a surface of said conductive film.
8. The method of claim 7 , wherein the another layer contains a fluoropolymer or fluoromonomer binder.
9. The method of claim 8 , wherein the film is at least 75% transparent to visible light.
10. The method of claim 8 , wherein the film is at least 90% transparent to visible light.
11. The method of claim 9 , wherein the film has a sheet resistance of from 10 −1 to 10 4 Ω/□.
12. The method of claim 10 , wherein the film has a sheet resistance of from 10 1 to 10 3 Ω/□.
13. The method of claim 11 , wherein the sheet resistance is up to 10% less than the corresponding sheet resistance of the film without said binder.
14. The method of claim 12 , wherein the sheet resistance is up to 50% less than the corresponding sheet resistance of the film without said binder.