| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an ink for scratch color development, hardly coloring an invisible information printed part in usual treatment but easily made visible the invisible information even by rubbing with the finger nail when it is unwanted to use tools such as a coin, increased in color density, hardly generating whittlings when the invisible information is made visible, much difficult in visually checking the invisible information-printed part without scratch color development, and excellent in light resistance, and to provide invisible sheets using the ink. <P>SOLUTION: An electron-donating dye precursor is defined, which precursor is used in the ink for scratch color development and comprises the electron-donating dye precursor, an electron-accepting compound and a varnish, and which precursor is used in an invisible information printed sheet manufactured by printing on a support the invisible information with the ink. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
