| 摘要 |
Light-sensitive materials are known which have a support carrying one or more layers of (a) an inorganic material (such as a chalcogenide or a halide) and (b) a metal or sulphide, halide or oxide of a metal; upon exposure to light a reaction occurs which alters the hydrophilic nature of the surface of the layer so as to make the material suitable after imagewise exposure for use directly as a lithographic printing plate. The invention provides a process of treating such a material after imagewise exposure (i.e. a printing plate) so as to increase the hydrophilic or oleophilic nature of an exposed or unexposed part of the plate, by wetting the exposed surface with an aqueous solution of (i) thiourea or a substituted thiourea preferably of a specified general formula (I) e.g. N-ethylthiourea, preferably in concentration of 0.1 to 30%, and (ii) an acid or an acidic inorganic salt, preferably 0.01 to 20% of the solution, possibly with an organic solvent. The light-sensitive layer(s) may also include various organic additives, e.g. benzotriazole, dyes, and sulfur- containing compounds. |
