| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a fluorescent ink which can give prints which produce sufficient visible luminescent outputs when irradiated with ultraviolet light and can be recognized regardless of the type of the substrate on which they are printed by dissolving in a solution three kinds of fluorescent materials having different luminescent wavelengths and being capable of being excited in turn upon irradiation with ultraviolet light. SOLUTION: Three fluorescent materials which are related with each other in such a way that the first fluorescent material emits excitation light which excites the second fluorescent material upon being irradiated with ultraviolet light, the second fluorescent material excites the third fluorescent material with the aid of irradiation with ultraviolet light and the excitation light from the first fluorescent material, and the third fluorescent material emits visible light with the aid of irradiation with ultraviolet light and the excitation light from the second fluorescent material and satisfies the relationship:λ<λ2<λ3 (whereinλ3 is the luminescent wavelength of the first fluorescent material,λ2 is the luminescent wavelength of the second fluorescent material andλ1 is the luminescent wavelength of an optical whitening agent being the third fluorescent material) are dissolved in a solution containing water, a wetting agent, a water-soluble resin, a surfactant, an antifoam, an antimold, etc.</p> |
