THERMAL COLOR DEVELOPING/ERASING TYPE WHITE BOARD AND COLOR DEVELOPING AND ERASING METHOD THEREOF

摘要

PROBLEM TO BE SOLVED: To form an image having a clear contour and sufficient contrast and to make the marks after erasure inconspicuous without damaging a merit such that no dust is generated at a time of erasure. SOLUTION: A conventional thermal recording agent is changed in transparency by a change of a temp. condition but, by utilizing the color developing and erasing phenomenon accompanied by the change of the temp. condition, a clear contour and sufficient contrast are obtained. Further, the surface hardness of a thermal recording layer is controlled so as to make marks after erasure inconspicuous to set the diameter dimension of the dent generated when a steel ball of 0.5ϕ is pressed to the reversible thermal recording layer 2 formed on a base film under gravity of 300g to 0.1mm or less.