Low emissivity and EMI shielding window films

1. A method for selectively reducing emissivity through a surface, the method comprising:

providing a low emissivity composite film, comprising:

a film substrate;

an underlayer of abrasion resistant hardcoat material coated on the film substrate and comprising a crosslinked acrylate polymer and metal oxide nanoparticles, the underlayer having a dried thickness of about 2 to about 6 microns and an abrasion delta haze of about 3 to about 5%; and

at least one infrared reflective layer;

a transparent protective top coat comprising a polysilazane, fluoro silane, fluoroalkyl silane, or combination thereof, wherein the protective top coat has a thickness of less than about 0.5 microns and is disposed over the infrared reflective layer;

wherein the composite film has an emissivity of less than about 0.30; and

wherein the underlayer is disposed between the film substrate and the infrared reflective layer; and

selectively positioning the low emissivity composite film relative to a generally planar surface so that either;

the low emissivity composite film is arranged in a first position generally coplanar with the surface to reduce emissivity through the surface; or

the low emissivity composite film is arranged in a second position generally non-coplanar with the surface to not reduce emissivity through the surface.

2. The method of claim 1 wherein the surface comprises an exterior surface of a window.

3. The method of claim 1 wherein the surface comprises an interior surface of a window.

4. The method of claim 1 wherein the surface comprises a surface of a skylight.

5. The method of claim 1 wherein the surface comprises a surface of a wall.

6. The method of claim 1 wherein the low emissivity film is only in proximity to the surface when in the first position.

7. The method of claim 6 wherein the low emissivity composite film is rolled when moved from the first to the second position.

8. The method of claim 1 wherein the low emissivity film is in proximity to the surface when in both the first position and the second position.

9. The method of claim 8 wherein the low emissivity film is adhered to a shade which is positioned in proximity to the generally planar surface.

10. The method of claim 8 wherein the low emissivity film is adhered to a blind which is positioned in proximity to the generally planar surface.

11. The method of claim 1 wherein the infrared reflecting layer comprises at least one core metallic layer selected from aluminum, copper, gold, nickel, silver, platinum, palladium, tungsten, titanium, and alloys thereof.

12. The method of claim 11 wherein the infrared reflecting layer further comprises at least one thin metal film having a thickness of about 1 to about 5 nm and comprising at least one metal selected from nickel, chromium, niobium, gold, platinum, cobalt, zinc, molybdenum, zirconium, vanadium, mixtures thereof, and alloys thereof.

13. The method of claim 12 wherein the thin metal film comprises a nickel-chromium alloy.

14. The method of claim 11 wherein the infrared reflective layer comprises at least one spacer layer comprising a transparent conductive layer, a dielectric layer, or combinations thereof.

15. The method of claim 1 wherein the infrared reflective layer comprises at least one transparent conductive layer comprising indium zinc oxide.

16. The method of claim 1 , wherein the metal oxide nanoparticles have a particle size of 0.1 micron or less.

17. The method of claim 1 , wherein the underlayer comprises about 21 to about 65 weight percent nanoparticles, based on the total weight of the hardcoat material.

18. The method of claim 1 , wherein the metal oxide nanoparticles comprise silicon dioxide, aluminum oxide, or a combination thereof.