Patent ID: 7465414

Claim:
A photochromic article consisting essentially of: (a) a transparent solid substrate having a front surface and a back surface, wherein said substrate is prepared from compositions selected from the group consisting of polymerizable allyl glycol carbonate monomer(s), thermoplastic polycarbonate, polyurea urethane, compositions comprising the reaction product of polyfunctional isocyanate(s) and polythiol monomer(s), compositions comprising the reaction product of polyfunctional isocyanate(s) and polyepisulfide monomer(s), optical quality mineral glass, and combinations thereof, (b) a transparent photochromic thermoplastic polyurethane film adjacent to at least one surface of said substrate, said polyurethane film having (i) a thickness of 2 to 15 mils, (ii) a flexural modulus of less than 2.5 GPa, and (iii) being formed from polyurethane material selected from the group consisting of polyether-based polyurethane, polycarbonate-based polyurethane and mixtures of such polyurethane materials, said polyurethane film containing at least one organic photochromic material that is soluble in the polyurethane film, and (c) transparent protective film of thermoplastic polymeric organic material superposed on said polyurethane film, said photochromic article exhibiting (1) a change in color when exposed to activating ultraviolet light radiation, and (2) a color fading half life (T½) of not more than 500 seconds when the ultraviolet light radiation is removed.