| abstract |
(57) [Abstract] [Problem] It is colorless under visible light and cannot be recognized by the naked eye, It is a printing ink composition that can be colored and visualized under UV irradiation. Development of an aqueous ink composition that does not cause a significant decrease in light emission intensity Europium compound represented by the following formula (1): (Wherein X represents an aromatic ring or a heterocyclic group which may have a substituent, and Y represents a fluorocarbon group having 1 to 10 carbon atoms, respectively), a polymer having at least a cyclic amide group in the structure And an aqueous ink composition containing water. |