An irreversible heat-sensitive composition comprises a mixture of a granular or powdery heat-fusible substance having a melting point corresponding to a temperature to be recorded and a granular or powdery dyestuff diffusible into the fused heat-fusible substance through dispersion or dissolution. A heat-sensitive ink comprises the irreversible heat-sensitive composition and an ink vehicle capable of diffusing the fused heat-fusible substance therein. A heat-sensitive ink according to another embodiment comprises microcapsules, which encapsulate the irreversible heat-sensitive composition. A heat-sensitive indicator comprises a substrate provided thereon with a printed heat-sensitive ink, the heat-sensitive ink being one of these heat-sensitive inks.
不可逆热敏组合物包括熔点与待记录温度相对应的颗粒状或粉状热敏物质与可通过分散或溶解扩散到熔融热敏物质中的颗粒状或粉状
染料的混合物。热敏油墨包括不可逆热敏组合物和能够将熔融热敏物质扩散到其中的油墨载体。根据另一个实施方案,热敏油墨包括封装不可逆热敏组合物的微胶囊。热敏指示器包括一个基板,基板上印有热敏油墨,热敏油墨是这些热敏油墨中的一种。