TEMPERATURE HISTORY INDICATOR

摘要

PROBLEM TO BE SOLVED: To provide a flat temperature history indicator superior in resistance to water, oil, and abrasion used for accurately displaying whether a predetermined temperature is exceeded in temperature history or not by a clear change in a tone of color. SOLUTION: A concealing ink layer 11 containing a heat fusing substance with a recording temperature as a fusing point is added to the temperature history indicator. A paper substrate 12 capable of irreversibly absorbing the heat substance in a fused state is fitted in a hole of an intermediate sheet 14 of the approximately same thickness as that of the paper substrate 12 and pasted to a support sheet 16. The ink layer 11 and the intermediate sheet 14 are flatly coated with a protecting film 10 made of a transparent resin. COPYRIGHT: (C)2003,JPO