Synthesis and characterization of N‐methyl‐2,6‐dinitrodiphenylamine‐4‐diazonium salt and its diazoresin

A new photosensitive agent, dinitro derivatives of diphenylamine diazonium salt (N‐methyl‐2,6‐dinitrodiphenylamine‐4‐diazonium salt, MDNDDS), and its diazoresin were synthesized. Their photoreactivities and thermostabilities were investigated. Our results revealed that MDNDDS and MDNDDS‐resin exhibited greatly improved thermostability both in solid state and in coating film comparing with the conventional unsubstituted and mononitro substituted diphenylamine diazonium salts (DDS and MNDDS, respectively) and their diazoresins. The photosensitivity of MDNDDS was found to be slightly lower than DDS but still comparable with MNDDS. As a result of its improved thermostability, both MDNDDS‐resin as a photosensitive agent and lithographic printing plate prepared by MDNDDS‐resin will have a long shelf‐life, which is very important to reduce waste and factory running‐cost. MDNDDS also has a maximum absorption wavelength (λ_max) at 425 nm, which means that an iodine gallium lamp (main emission wavelength λ_em = 420 nm), is better than conventional mercury lamp (λ_em = 360 nm), to be used as the irradiation source in the photoimaging process. Compared with the mercury lamp, iodine gallium lamp is cheaper and greener. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013