To provide a heat-sensitive coloring material in which fine particles of metal are dispersed in the matrix material, the matrix material has a glass transition point (Tg), the rate of the coloring reaction differs from each other at a higher and a lower temperatures than the transition point (Tg), thus the coloring reaction is retarded, when it is permitted to stand below a prescribed temperature, while the coloring reaction is promoted above a prescribed temperature, further provide a heat-sensitive coloring element and production processes therefor.

A heat-sensitive coloring layer having a structure in which fine particles of metal 2 are dispersed in a matrix polymer material is supported on the substrate, the matrix material 1 shows the glass transition at an arbitrarily prescribed temperature. The metal fine particles 2 in the matrix diffuse and flocculate in the matrix by the thermal energy and the metal articles growing up to a diameter larger than several nm and contribute to the color development. The heat-sensitively coloring element is used for the temperature control in the field of the low-temperature distribution industry, for example, refrigeration and frozen food.