| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a scratch sheet having novel constitution employing a method incapable of discriminating the data applied to the surface of a sheet to be concealed from the surface thereof though a transparent film used in a coating layer removable by scratching. SOLUTION: Secret data is formed to the predetermined part on the surface of a sheet base material using a color changeable coloring matter composition reversely generating a hue change accompanied by the presence and absence of oxygen and covered with an oxygen impermeable transparent film.</p> |
