Composition comprising surface modified high index nanoparticles suitable for optical coupling layer
Presently described is a method for coupling an optical film to a substrate, laminated optical constructions comprising an optical film and an optical coupling layer disposed on a surface layer of the optical film, and coating compositions useful for optical an optical coupling layer. The coating compositions comprise at least 40 wt.-% inorganic nanoparticles having a refractive index of at least 1.85 and a polymeric silane surface treatment.
1. A method for coupling an optical film comprising:
providing an optical film;
providing a substrate;
applying an optical coupling layer to a surface layer of the optical film, the substrate, or a combination thereof; wherein the optical coupling layer comprises
at least 40 wt.-% inorganic nanoparticles having a refractive index of at least 1.85, and
a polymeric silane surface treatment, wherein the polymeric silane surface treatment is the sole polymeric component of the optical coupling layer; and
laminating the optical film to the substrate forming a laminated optical construction.
2. The method of claim 1 wherein the surface layer of the optical film has a refractive index of at least 1.60.
3. The method of claim 2 wherein the light extraction film comprises
a substantially transparent substrate;
extraction elements on the substantially transparent substrate; and
a planarizing backfill layer applied over the extraction elements, forming a substantially planar surface of the backfill layer, wherein an index of refraction of the backfill layer is higher than an index of refraction of the extraction elements.
4. The method of claim 3 wherein the extraction elements comprise engineered nanostructures having multi-periodic zones, the multi-periodic zones comprising a repeating zone of the nanostructures where the zone comprises a first set of nanostructures having a first plurality of periodic characteristics and a second set of nanostructures having a second plurality of periodic characteristics different from the first plurality of periodic characteristics.
5. The method of claim 3 wherein the extraction elements comprise periodic structures and a layer of light scattering nanoparticles applied over the periodic structures.
6. The method of claim 3 wherein the optical coupling layer is applied to the backfill layer.
7. The method of claim 1 wherein the optical film is a light extraction film and the substrate is a top emitting organic light emitting diode (OLED) device.
8. The method of claim 7 wherein the optical coupling layer is applied to the top emitting organic light emitting diode (OLED) device.
9. The method of claim 1 wherein the optical coupling layer is substantially solvent free when laminated.
10. The method of claim 1 wherein the optical coupling layer is substantially free of (meth)acrylate components having a molecular weight of 1,000 g/mole or less.
11. The method of claim 1 wherein the polymeric silane surface treatment comprises a random acrylic copolymer comprising at least 50 wt.-% of repeat units derived from one or more alkyl (meth)acrylate monomers comprising 4 to 18 carbon atoms and a terminal alkoxy silane group.
12. The method of claim 1 wherein the polymeric silane surface treatment has a Tg ranging from −20° C. to −80° C.
13. The method of claim 1 wherein the polymeric silane surface treatment has a weight average molecular weight ranging from 1000 to 5000 g/mole.
14. The method of claim 1 wherein the inorganic nanoparticles further comprise a non-polymeric surface treatment.
15. The method of claim 14 wherein the non-polymeric surface treatment has a refractive index of at least 1.50.
16. The method of claim 14 wherein the optical coupling layer has a refractive index of at least 1.65.
17. The method of claim 1 wherein the optical coupling layer has a refractive index of at least 1.65.
18. A method for coupling an optical film comprising:
providing an optical film;
providing a substrate;
applying an optical coupling layer to a surface layer of the optical film, the substrate, or a combination thereof; wherein the optical coupling layer comprises
at least 40 wt.-% inorganic nanoparticles having a refractive index of at least 1.85, and
a polymeric silane surface treatment, wherein the polymeric silane surface treatment comprises a random acrylic copolymer comprising at least 50 wt.-% of repeat units derived from one or more alkyl (meth)acrylate monomers comprising 4 to 18 carbon atoms and a terminal alkoxy silane group; and
wherein the optical coupling layer further comprises non-silane polymeric binder in an amount up to 10 wt-% of the optical coupling layer; and
laminating the optical film to the substrate forming a laminated optical construction.
19. The method of claim 18 wherein the surface layer of the optical film has a refractive index of at least 1.60.
20. The method of claim 18 wherein the optical film is a light extraction film and the substrate is a top emitting organic light emitting diode (OLED) device.
21. The method of claim 20 wherein the light extraction film comprises
a substantially transparent substrate;
extraction elements on the substantially transparent substrate; and
a planarizing backfill layer applied over the extraction elements, forming a substantially planar surface of the backfill layer, wherein an index of refraction of the backfill layer is higher than an index of refraction of the extraction elements.
22. The method of claim 21 wherein the extraction elements comprise engineered nanostructures having multi-periodic zones; the multi-periodic zones comprising a repeating zone of the nanostructures where the zone comprises a first set of nanostructures having a first plurality of periodic characteristics and a second set of nanostructures having a second plurality of periodic characteristics different from the first plurality of periodic characteristics.
23. The method of claim 21 wherein the extraction elements comprise periodic structures and a layer of light scattering nanoparticles applied over the periodic structures.
24. The method of claim 21 wherein the optical coupling layer is applied to the backfill layer.
25. The method of claim 20 wherein the optical coupling layer is applied to the top emitting organic light emitting diode (OLED) device.
26. The method of claim 18 wherein the optical coupling layer is substantially solvent free when laminated.
27. The method of claim 18 wherein the optical coupling layer is substantially free of (meth)acrylate components having a molecular weight of 1,000 g/mole or less.
28. The method of claim 18 wherein the polymeric silane surface treatment comprises a random acrylic copolymer comprising at least 50 wt.-% of repeat units derived from one or more alkyl (meth)acrylate monomers comprising 4 to 18 carbon atoms and a terminal alkoxy silane group.
29. The method of claim 18 wherein the polymeric silane surface treatment has a Tg ranging from -20° C. to -80° C.
30. The method of claim 18 wherein the polymeric silane surface treatment has a weight average molecular weight ranging from 1000 to 5000 g/mole.
31. The method of claim 18 wherein the inorganic nanoparticles further comprise a non-polymeric surface treatment.
32. The method of claim 31 wherein the non-polymeric surface treatment has a refractive index of at least 1.50.
33. The method of claim 31 wherein the optical coupling layer has a refractive index of at least 1.65.
34. The method of claim 18 wherein the optical coupling layer has a refractive index of at least 1.65.