Photochromic article

An ophthalmic photochromic article consisting essentially of:

• (a) a transparent solid optical polymeric substrate having a front surface and a back surface, wherein the solid optical substrate is prepared from compositions selected from the group consisting of polyurea urethane, the reaction product of polyfunctional isocyanate(s) and polythiol monomer(s), the reaction product of polyfunctional isocyanate(s) and polyepisulfide monomer(s), and combinations thereof,
• (b) a transparent thermoplastic photochromic polyurethane film contiguous to one surface of said substrate, said polyurethane film having (i) a light transmission of at least 80%, (ii) a flexural modulus of less than 2.5 GPa, (iii) a thickness of from 2 to 15 mils, and (iv) being formed from polyurethane material comprising polyether-based polyurethane, polycarbonate-based-polyurethane or mixtures of such polyurethane materials, said polyurethane film further containing a photochromic amount of at least one organic photochromic material that is soluble in the polyurethane film, and
• (c) a transparent thermoplastic protective film of polymeric organic material superposed on said polyurethane film, said polymeric protective film having a light transmission of at least 80%, a thickness of from 1 to 20 mils and a flexural modulus of from 0.5 to 3 Gpa, said ophthalmic photochromic article exhibiting a change in color from colorless to colored when exposed to activating ultraviolet light radiation, and a color fading half-life (T½) of not more than 500 seconds when the ultraviolet light radiation is removed.

A photochromic optical article comprising, in combination:

• (a) a transparent solid optical polyurea urethane substrate having a front surface and a back surface;
• (b) transparent thermoplastic photochromic polyurethane film appended to at least one surface of the optical 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 polyether-based polyurethane materials, polycarbonate-based polyurethane materials and mixtures of said polyurethane materials, said polyurethane film further containing from 0.2 to 10 weight percent of at least one organic photochromic material that is soluble in the polyurethane film, said photochromic material being chosen from naphthoxazines, spiro(indolino) pyridobenzoxazines, naphthopyrans, spiro-9-fluorenopyrans, phenanthropyrans, indeno-fused naphthopyrans and mixtures of such photochromic materials;
• and
• (c) transparent thermoplastic protective film of polymeric organic material superposed on said polyurethane film, said polymeric protective film having a flexural modulus of from 0.1 to 5 GPa, said polymeric protective film being selected from nylon, poly(vinyl acetate), vinyl chloride-vinyl acetate copolymer, poly(lower alkyl)acrylates, poly(lower alkyl)methacrylates, styrene-butadiene copolymer resin, polyurea urethane, lightly cross-linked thermoplastic polyurethane and thermoplastic polycarbonate material, said photochromic optical 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.