Transparent films with control of light hue using nanoscale colorants
Nanoscale colorants are introduced to adjust the hue of transparent conductive films, such as to provide a whiter film. The transparent conductive films can have sparse metal conductive layers, which can be formed using silver nanowires. Color of the film can be evaluated using standard color parameters. In particular, values of color parameter b* can be reduced with the nanoscale colorants without unacceptably changing other parameters, such as haze, a* and transparency.
1. A transparent film comprising a substrate, a transparent conductive layer supported by the substrate, a coating layer and one or more nanoscale colorants, wherein a value of b* for the film is reduced at least about 0.1 units and total transmittance of visible light in percent is not decreased by more than about 2 relative to the corresponding film without the nanoscale colorants, the nanoscale colorants comprising gold, wherein the nanoscale colorants in a dilute dispersion have a peak absorption between 525 nm and 675 nm, wherein the transparent conductive layer comprises a fused metal nanostructured network and wherein the transparent film has a value of TT % of at least about 88%.
2. The transparent film of claim 1 wherein the nanoscale colorants are in the transparent conductive layer.
3. The transparent film of claim 1 wherein the coating layer has a thickness from about 25 nm to about 2 microns and comprises from about 0.1 wt % to about 10 wt % nanoscale colorants.
4. The transparent film of claim 1 wherein the nanoscale colorants comprise gold nanoshells, gold nanospheres or gold nanoplates.
5. The transparent film of claim 1 wherein the nanoscale colorants further comprise silver, indium, tin, iron, cobalt, platinum, palladium, nickel, cobalt, titanium, copper or alloys or combinations thereof.
6. The transparent film of claim 1 wherein the nanoscale colorants comprise gold nanoshells having a silica core.
7. The transparent film of claim 1 wherein the nanoscale colorants comprise a polymeric coating.
8. The transparent film of claim 1 wherein the nanoscale colorants comprise a silica coating.
9. The transparent film of claim 1 wherein the nanoscale colorants comprise gold nanoshells having a ceramic core.
10. The transparent film of claim 1 wherein the nanoscale colorants in a dilute dispersion have a peak absorption near 550 nm.
11. The transparent film of claim 1 wherein the film is hue adjusted as expressed as an absolute value of the color scale a* being adjusted by at least about 0.1 relative to an equivalent film without the nanoscale colorants.
12. The transparent film of claim 1 wherein the absolute value of a* and b* in the color scale are each no more than about 1.
13. The transparent film of claim 1 wherein the haze in percent units does not increase by more than 0.5 relative to a corresponding film without the nanoscale colorants.
14. The transparent film of claim 1 wherein the coating layer comprises polysiloxanes, polysilsesquioxanes, polyurethanes, acrylic resins, acrylic copolymers, cellulose ethers and esters (a water insoluble polysaccharide), nitrocellulose (a water insoluble polysaccharide), 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, and mixtures thereof.