| abstract |
Flexible filters capable of transmitting radiation in the spectral range of 315 to 380 nm and absorbing radiation in the spectral range of 400 to 550 nm consist essentially of a thin flexible film, e.g., polyethylene terephthalate containing or having coated thereon a dye in a concentration of 15 to 60 mg/dm2 and optionally, as a component of the coating, a thermoplastic organic binder, e.g., cellulose acetate butyrate, present in the coating with the dye, said dye being of the formula: <IMAGE> where R1 is lower alkyl of 1 to 5 carbon atoms; R2 and R3, which may be the same or different, are selected from the group consisting of R1, 2-cyanoethyl, 2-hydroxyethyl and <IMAGE> or form a saturated 5- or 6- membered ring; R4 is taken from the class consisting of lower alkyl of 1 to 5 carbon atoms, aryl or alkaryl of 6 to 9 carbon atoms, and aralkyl. The filters are useful in exposing dual response photosensitive materials with ultraviolet radiation sources which contain appreciable quantities of visible radiation. |