Azo pigments and their intermediaries. A study of the structure-sensitivity relationship of photogenerating bisazo pigments in bilayer xerographic devices

The structure-sensitivity relationships of several series of bisazo pigments have been studied in bilayer xerographic devices using a common charge (hole) transporting layer (CTL). For a given bisazo pigment series, a correlation is found between the E0.5 value for each pigment and the Hammet constant σp. The data consistently show that neither electron-withdrawing substituents nor electron-releasing substituents promote high photosensitivity. …