| 摘要 |
PROBLEM TO BE SOLVED: To provide an invisible information printed sheet, such that visualization of invisible information can be easily performed while eliminating scratching dust in visualization of the invisible information, and the invisible information is never illicitly detected before scratching. SOLUTION: The invisible information printed sheet comprises an image printed on a support by use of a scratch coloring ink containing a colorless or pale color electron-donating dye precursor, an electron-donating compound and vanish. The image is composed of an information part and a non-information part, and the non-information part is provided on the same surface of the sheet as the information part. The absolute value of difference in print area ratio between the information part and the non-information part preferably ranges between 10% and 30%. COPYRIGHT: (C)2009,JPO&INPIT |
