printing ink, its use for article authentication, articles thus obtained, system and method of authentication

摘要

printing ink comprising a first fluorescent dye acting as a donor and a second fluorescent dye acting as a recipient is described. the first fluorescent dye, by excitation by electromagnetic radiation, falling within a wavelength range ¿1a of the first fluorescent dye, is capable of emitting electromagnetic radiation in at least a first wavelength range of ¿1e emission, said first emission wavelength range - 1e of the first fluorescent dye being overlaid with at least one excitation wavelength range - 2a of the second fluorescent dye, to thereby excite the second fluorescent dye to emit electromagnetic radiation in a second emission wavelength range 2e.