Irreversible heat-sensitive composition

A heat-sensitive ink comprising an irreversible heat-sensitive composition, which 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, said heat-fusible substance being at least one member selected from the group consisting of fatty acid derivatives, alcohol derivatives, ether derivatives, aldehyde derivatives, ketone derivatives, amine derivatives, amide derivatives, nitrile derivatives, hydrocarbon derivatives, thiol derivatives and sulfide derivatives, through dispersion or dissolution;

• and an ink vehicle capable of diffusing the fused heat-fusible substance therein.

A heat-sensitive ink comprising microcapsules, which encapsulate an irreversible heat-sensitive composition comprising 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, and an ink vehicle capable of diffusing the fused heat-fusible substance therein.

A heat-sensitive indicator comprising a substrate provided thereon with a printed heat-sensitive ink layer, wherein the heat-sensitive ink comprises an irreversible heat-sensitive composition, which 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, said heat-fusible substance being at least one member selected from the group consisting of fatty acid derivatives, alcohol derivatives, ether derivatives, aldehyde derivatives, ketone derivatives, amine derivatives, amide derivatives, nitrile derivatives, hydrocarbon derivatives, thiol derivatives and sulfide derivatives, through dispersion or dissolution, and an ink vehicle capable of diffusing the fused heat-fusible substance therein.

A heat-sensitive indicator comprising a substrate provided thereon with a printed heat-sensitive ink layer, wherein the heat-sensitive ink comprises microcapsules, which encapsulate an irreversible heat-sensitive composition comprising 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, and an ink vehicle capable of diffusing the fused heat-fusible substance thereto.