Protective film
A protective film has a soluble polyimide polymer base layer and an exterior layer directly contacting the base layer exterior surface. The base layer is less than 12 microns thick, and is at least 2 meters long. The exterior layer includes at least one of a fluorinated polymer, a dielectric layer, one or more metallic layers, a metalloid layer, or a plurality a dielectric layers where each dielectric layer has a dielectric layer thickness that varies no more than 3%. The exterior layer or the base layer can also include additives, as desired.
1. A process for making a protective film comprising:
(a) providing a first carrier film;
(b) coating the first carrier film with a dope comprising a polymer and a solvent;
(c) curing the dope to form a base layer by evaporating the solvent where the base layer has an exterior surface and an interior surface, and wherein the interior surface of the base layer is in contact with the first carrier film;
(d) coating the base layer exterior surface with an exterior surface coating, wherein the exterior surface coating comprises a metal or a metalloid; and
(e) removing the first carrier film; wherein the protective film comprises the base layer with the exterior surface coating;
(f) adding a second carrier film in contact with the coated exterior surface of the base layer;
(g) coating the interior surface of the base layer with an interior surface coating comprising at least one of a fluorinated polymer, a dielectric material, metal, or a metalloid and (h) removing the second carrier film.
2. The process of claim 1 where a total of the base layer thickness and the exterior surface coating thickness is less than 14 microns.
3. The process of claim 1 further comprising adding a reflective pigment to at least one of the base layer and the exterior surface coating.
4. The process of claim 1 further comprising adding an electro-static discharge additive to at least one of the base layer and the exterior surface coating.
5. The process of claim 1 where the protective film forms at least one component of an airship.
6. The process of claim 1 where the protective film has a thermal emissivity greater than a solar absorptivity.
7. The process of claim 1 where the protective film blocks at least 90% of ultraviolet radiation.