Abstract: To improve the image quality of the positive-type diazo photosensitive materials’ a series of studies related to the colour efficiency of the formed azo dye, the activities of the coupling reaction between diazonium salts and its couplers, the self-coupling effect, the solvent effect, The spectral sensitivity and the fastness of the image have been carried out. In consequence, a kind of diazo film with excellent image quality was developed.

Key words: Diazo photosensitive Materials, Colour Efficiency, Coupling Activity, Self-Coupling Effect