Photoplanographic printing plate and process for its production

891,898. Photoplanographic printing plate production. GENERAL ANTLINE & FILM CORPORATION. Dec 30, 1959 [Jan. 21, 1959], No. 44242/59. Drawings to Specification. Class 98(2). A positive-working process comprises exposing a plate having a hydrophilic base bearing a hardenable light-sensitive coating, removing unhardened portions thereof, applying a water dispersible metallo-organic Werner complex in which trivalent chromium or aluminium is co-ordinated with a carboxylic acido group, "fixing" this complex and removing the hardened coating and complex adhering thereto from the light-struck areas. The Werner complexes are described by reference to various publications, and they have the property of adhering to hydrophilic surfaces but can be made receptive to greasy ink. In Example I an aluminium sheet or foil is cleaned, silicated, provided with a sensitive layer comprising acrylamide, N,N1-methylenebis-acrylamide, gelatine and silver nitrate, at which state it may be stocked for several months when tightly closed; exposed under a pattern by visible light, washed out with warm water or dye solution, treated with an alcoholic solution of a proprietary Werner complex, fixed by making the latter alkaline as by fuming with ammonia, softly brushed to remove coating and complex from the exposed areas, treated with a zinc oleate "developer" comprising this substance along with dimethylformamide, butyl acetate and nigrosine dye in methanol, to make the hydrophilic portions more visible and ink-accepting, and is then ready for mounting on a printing machine. Six further examples describe other sensitive layers and refer to Example 1 for procedure therewith. Two other " developers" and numerous other supports, monomers, polymers, colloids, solvents, sensitisers and such like are quoted. Specifications 721,660, 858,037, 866,631, 867,980, 879,892 and 885,128 are referred to.