Process of manufacturing light-sensitive copying material based on diazonium salt condensation products

Claim 1

In a process for the manufacture of a negative-working, presensitized planographic printing plate developable in pure water at room temperature by applying an aqueous coating mixture without any addition of organic solvent to an aluminum plate support and drying the coating, said coating mixture containing (a) a water-soluble light-sensitive condensation product of an aromatic diazonium salt, (b) a stable dispersion of a water-insoluble macromolecular polymer, and (c) about 0.01 to 0.6 part by weight of a surface-active agent per part by weight of the water-insoluble polymer, over and above the amount of surface-active agent required to manufacture and stabilize the dispersion, the improvement which comprises drying the coating mixture at a temperature between about 45° C. and the decomposition temperature of the diazonium compound and under conditions such that an optically homogeneous light-hardenable coating with no discrete particles visible at 30,000-fold magnification is formed.