| 摘要 |
PROBLEM TO BE SOLVED: To provide an infrared light excitation type ink composition which can be printed on an article without the deterioration of its appearance to form the printed article that can highly sensitively be detected over a long period, is safe for human bodies, and is not limited by employment environments. SOLUTION: This ink composition contains an organic fluorescent pigment, such as a polymethine pigment, which is substantially invisible or scarcely recognizable in a visible light region and can be excited with infrared light to emit light in the infrared light region. The pigment is contained in a solvent containing >=94 wt.% of water and/or ethanol and having a particle diameter of 10 to 450 nm. |
