Patent ID: 6827769
Filing Date: 2004-12-07
Classification: C09D

Abstract:
A heterogeneous aqueous ink capable of producing dark, machine-readable markings exhibiting fluorescence when exposed to fluorescent-exciting radiation, said ink being of suitable viscosity and surface tension for use in ink jet printing, comprising:a. a first colorant comprising a fluorescent dye embedded in a polymeric matrix, said fluorescent dye emitting light within a characteristic emission band when excited by fluorescent-exciting radiation; b. a second colorant comprising at least one of a dye and a pigment having a light absorption band at longer wavelengths than the characteristic emission band of the first colorant; and c. an aqueous liquid vehicle comprising water and a water-soluble vehicle in sufficient amounts to achieve an ink viscosity and surface tension effective for application of the ink to a substrate in a predetermined pattern by ink jet printing; wherein, the colorants are present in combination in the aqueous ink in amounts effective to cause the ink, when dry, to exhibit a dark color due to the net absorption spectra of the colorants in the visual range and machine-readable or visually-discernable fluorescence when subjected to fluorescent-exciting radiation.