Transfer of azo dyes having a pyridine coupling component

摘要

Azo dyes are transferred from a substrate to a plastic-coated paper by diffusion with the aid of a thermal printing head, these azo dyes having the formula where D is the radical of a diazo component and R1, R2 and R3 are each independently of the others hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted phenyl or substituted or unsubstituted cyclohexyl and R4 is alkyl.