Heat-sensitive imaging element

摘要

A heat-sensitive imaging element comprises an IR dye having a structure according to formula I,
wherein at least one of the R d groups is a group which is transformed by a chemical reaction, induced by exposure to IR-radiation or heat, into a group which is a stronger electron-donor than said R d ; or wherein at least one of the R a groups is a group which is transformed by a chemical reaction, induced by exposure to IR-radiation or heat, into a group which is a stronger electron-acceptor than said R a . The imaging element is able to form a visible print-out image with a high contrast directly after image-wise exposure by IR-radiation or heating.