Low emissivity and EMI shielding window films
View Patent ↗A low emissivity and EMI shielding transparent composite film typically for use in association with window glazing and comprising a transparent film substrate having on one side thereof an underlayer of abrasion resistant hardcoat material with at least one infrared reflective layer covering the underlayer, typically a metallic layer which may be encased in metal oxide layers, which is then covered with a thin external protective top coat of a cured fluorinated resin.
1. A method for reducing emissivity of a structure, the method
comprising:
providing a low emissivity composite film comprising:
a film substrate;
an underlayer of abrasion resistant hardcoat material deposited 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%;
at least one infrared reflective layer;
a transparent protective top coat comprising a polysilazane, fluoro silane, fluoroalkyl silane, or combination thereof, having a thickness of less than about 0.5 microns, wherein the protective top coat is disposed over the infrared reflective layer; and
an adhesive layer;
wherein the composite film has an emissivity of less than about 0.30;
wherein the underlayer is disposed between the film substrate and the infrared reflective layer;
wherein the adhesive layer is disposed on the film substrate opposite the underlayer and infrared reflective layer; and
attaching the adhesive layer to a surface forming at least a portion of a structure.
2. The method of claim 1 wherein the adhesive layer comprises a pressure sensitive adhesive.
3. The method of claim 1 wherein the surface comprises an exterior surface of a window.
4. The method of claim 1 wherein the surface comprises an interior surface of a window.
5. The method of claim 1 wherein the surface is a wall of the structure.
6. The method of claim 1 wherein the structure encloses a refrigerated space.
7. The method of claim 1 wherein the surface is within the air gap of an insulated glazing.
8. The method of claim 1 , wherein the metal oxide nanoparticles have a particle size of 0.1 microns or less.
9. The method of claim 1 , wherein the underlayer comprises about 21 to about 65 weight percent of nanoparticles, based on the total weight of the hardcoat material.
10. The method of claim 1 , wherein the metal oxide nanoparticles comprise silicon dioxide, aluminum oxide, or a combination thereof.