| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a water-soluble infrared fluorescent ink which has high light-emitting power, can show improved light resistance without adding any quencher or the like and has low cost by using a cyanine dye in an amount to give a concentration higher than that in which the initial light emission power is maximum. SOLUTION: This invention provide a water-soluble infrared fluorescent ink mainly consisting of water, a water-soluble resin, a wetting agent and a cyanine dye being a fluorescent substance, wherein (A) the concentration of the cyanine dye is 0.075 pts.wt. or above higher than that in which the initial light emission power is maximum, (B) the water-soluble resin is a styrene/acrylic resin, a styrene/maleic acid resin or the like neutralized with ammonia and is used in an amount of 5-15 pts.wt. based on the total ink, (C) the wetting agent comprises 10-50 pts.wt. polyhydric alcohol (e.g. ethylene glycol, propylene glycol or diethylene glycol) and 1 pts.wt. surfactant, and (D) the balance comprises water, and the amount of water and that of the wetting agent are determined according to the properties, viscosity and surface tension of the ink.</p> |
