To provide a temperature history indicator capable of precisely discriminating the length of time during which it is exposed to a certain temperature.
This temperature history indicator has a lamination structure wherein a dye layer containing a dye which diffuses and moves while it is exposed to a set temperature condition, a dye diffusion control layer which controls the diffusing moving speed of the dye from the dye layer, and a coloring layer which is dyed by the dye having diffused and moved through the dye diffusion control layer from the dye layer and increases its concentration of coloring as time passes, are laminated on one surface of a support in order from the side of the support, and discriminates the length of time during which it is exposed to the set temperature condition.
Akira Inoue
Hiroshi Nakamoto
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