Lithographic matl. contg. anionic wetting agent and hydroquinone - in sub-coat, suitable for automatic processing in alkaline activator bath

摘要

In the prdn. of half-tone images by treating a photographic material contng. a developer substance with an alkaline activator soln., the photographic material has a layer contng. 2-5 g./m.2 hydroquinone (I) and 10-35, pref. 16-20% anion-active wetting agent (II), w.r.t. (I), in a binder, between the base and the emulsion layer. It is treated with an activator bath with pH 11.5 after exposure. (II) pref. is the Na salt (IIa) of the methyltarude of oleic acid. Treatment with the activator bath pref. takes place in the presence of an aldehyde- or ketone-bisulphite cpd. (III), a polyalkylene oxide cpd. (IV) with mol. wt. 1500-12,000 and 5-nitroindazole (V). The material can be handled easily, does not necessitate constant supervision and is suitable for automatic activation, giving great constancy of the development process. Excellent dot quality is obtd. over the entire dot size range and the activator bath has good stability and a long useful life.