US Patent 7922941 Photochromic plastic object

A photochromic plastic object which is composed of a transparent polymeric synthetic resin material, into or onto which at least one substantially mesoporous inorganic host structure is introduced or applied containing one or more embedded organic photochromic dye molecules so as to form a photochromic nanocomposite material. In contrast to prior techniques of adding or applying the photochromic organic dyes to the monomer mixture or prepolymer of a transparent synthetic resin material in a molecular form, in the photochromic plastic article of the present invention color is generated by using the photochromic nanocomposite particles or photochromic nanocomposite structures.