Abstract: Water-soluble, photosensitive, optically variable (POV) inks exhibit improved OCR readability due to improved infrared absorption properties. The inks can produce images that can be viewed with both visible and ultraviolet light to have physically coincident positive and negative images. The new inks contain at least two types of colorants in addition to the IR absorber and other suitable ingredients. The first colorant comprises a fluorescent dye or pigment emitting light within a characteristic emission band when excited by fluorescent-exciting radiation. The second colorant comprises a carbon black infrared radiation absorbing composition alone or with one or more dyes or pigments having a light absorption band at longer wavelengths than the characteristic emission band of the first colorant or also overlapping the emission wavelength of the first colorant in such a way as to result in a dark color.

Abstract: New photosensitive optically variable inks are capable of printing images having improved resistance to water. The inks produce images which can be viewed with both visible and ultraviolet light to have physically coincident positive and negative images. They contain at least two types of colorants and other suitable ingredients to enable preparation for printing. The first colorant comprises a fluorescent dye emitting light within a characteristic emission band when excited by fluorescent-exciting radiation. The second colorant, which comprises a colloidal pigment alone or with a dye, has a light absorption band at longer wavelengths than the characteristic emission band of the first colorant or overlapping the emission wavelength of the first colorant, effectively to result in a dark color.