Patent ID: 8778109

Claim:
A method for maintaining the temperature of an insulated enclosure, comprising: incorporating a low emissivity, composite film into an insulated enclosure, the 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; and a transparent protective top coat comprising a polysilazane, fluorosilane, 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; wherein the composite film has an emissivity of less than about 0.30 and the underlayer is disposed between the film substrate and the infrared reflective layer.