Property enhancing fillers for transparent coatings and transparent conductive films
Optically transparent films can comprise a coating of nanodiamonds to introduce desirable properties, such as hardness, good thermal conductivity and an increased dielectric constant. In general, transparent conductive films can be formed with desirable property enhancing nanoparticles included in a transparent conductive layer and/or in a coating layer. Property enhancing nanoparticles can be formed from materials having a large hardness parameter, a large thermal conductivity and/or a large dielectric constant. Suitable polymers are incorporated as a binder in the layers with the property enhancing nanoparticles. The coatings with property enhancing nanoparticles can be solution coated and corresponding solutions are described.
1. An optical structure comprising a transparent substrate, a transparent conductive layer and a transparent coating comprising a polymer binder and nanodiamonds wherein the transparent coating has an average thickness from about 25 nm to about 25 microns and has no more than about 10 weight percent nanodiamonds, wherein the nanodiamonds have an average particle diameter of no more than about 50 nm, wherein the haze of the optical structure increases by no more than about 1 percent relative to an equivalent optical structure without the nanodiamonds, wherein the polymer binder comprises crosslinked acrylic resin, and wherein the transparent conductive layer comprises a sparse metal conductive element and a polymer binder and wherein the transparent coating is in direct contact with the transparent conductive layer.
2. The optical structure of claim 1 wherein the transparent coating has from about 0.01 weight percent to about 10 weight percent nanodiamonds.
3. The optical structure of claim 1 wherein the transparent coating has from about 0.1 weight percent to about 10 weight percent nanodiamonds.
4. The optical structure of claim 1 wherein the transparent substrate comprises a polymer film having an average thickness from about 5 microns to 2 millimeters.
5. The optical structure of claim 1 wherein the transparent coating has an average thickness from about 100 nm to about 10 microns.
6. The optical structure of claim 1 wherein the substrate comprises polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyacrylate, poly(methyl methacrylate), polyolefin, polyvinyl chloride, fluoropolymers, polyamide, polyimide, polysulfone, polysiloxane, polyetheretherketone, polynorbornene, polyester, polystyrene, polyurethane, polyvinyl alcohol, polyvinyl acetate, acrylonitrile-butadiene-styrene copolymer, cyclic olefin polymer, cyclic olefin copolymer, polycarbonate, copolymers thereof, or blends thereof.
7. The optical structure of claim 1 wherein the polymer binder further comprises polysiloxanes, polysilsesquioxanes, polyurethanes, acrylic copolymers, cellulose ethers and esters, nitrocellulose, other water insoluble structural polysaccharides, polyethers, polyesters, polystyrene, polyimide, fluoropolymer, styrene-acrylate copolymers, styrene-butadiene copolymers, acrylonitrile butadiene styrene copolymers, polysulfides, epoxy containing polymers, copolymers thereof, or mixtures thereof.
8. The optical structure of claim 1 wherein the polymer binder comprises acrylic resin, acrylic copolymers, epoxy containing polymers, copolymers thereof, or mixtures thereof.
9. The optical structure of claim 1 wherein the nanodiamonds have an average particle diameter of no more than about 20 nm.
10. The optical structure of claim 1 wherein the transparent coating is not scratched when rubbed with superfine grade steel wool under a 50 gram weight.
11. The optical structure of claim 1 wherein the transmittance for visible light decreases by no more than about 5 percent relative to an equivalent optical structure without the nanodiamonds.
12. The optical structure of claim 1 wherein the transmittance for visible light decreases by no more than about 1 percent relative to an equivalent optical structure without the nanodiamonds.
13. The optical structure of claim 1 wherein the haze of the optical structure increases by no more than about 0.25 percent relative to an equivalent optical structure without the nanodiamonds.
14. The transparent conductive film of claim 7 wherein the sparse metal conductive element comprises a fused metal nanostructured network.
15. The optical structure of claim 1 wherein the transparent coating has a pencil hardness of at least about 1H and at least about 1 grade harder than the pencil hardness of an equivalent transparent coating without the nanodiamonds.
16. The optical structure of claim 1 wherein the optical structure has a total transmission of visible light of at least about 85%.
17. The optical structure of claim 14 wherein the optical structure has a total transmission of visible light of at least about 90%.
18. The optical structure of claim 14 wherein the optical structure has a total haze of no more than about 0.8% and a sheet resistance of no more than about 90 ohms/sq.