Method for treating lithographic printing plates
AssigneeMitsubishi Paper Mills Limited
InventorsEiji Kanada, Toshiro Kondo, Shoji Yamada
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Abstract
Surface treatment of lithographic printing plate which utilizes as ink receptive areas a photographically formed image silver per se or image silver halide per se is carried out in the presence of an organic compound having at least one mercapto or thione group and at least one hydrophilic group in the same molecule and an inorganic water-insoluble fine powder having a particle size of 0.1.mu. or less after imagewise exposure of a silver halide emulsion layer and processing thereof to develop an image, whereby ink receptivity, anti-staining property and printing endurance of the plate can be improved.
Claims10
In a method for treating a lithographic printing plate which utilizes as ink receptive areas a photographically formed silver image or silver halide image wherein after imagewise/exposure of a silver halide emulsion layer and processing thereof to develop an image, the printing plate surface treatment is carried out at pH7 or below in the presence of an organic compound having at least one mecapto or thione group and at least one hydrophillic group in the same molecule and an inorganic water-insoluble colloidal silica or colloidal alumina powder having a particle size of 0.1 micron or below which are present in at least one printing plate treating solution selected from neutralizing solution, etch solution and dampening solution, said powder being present in an amount sufficient to prevent the ink-staining of said lithographic printing plate, said organic compound being present in an amount sufficient to promote effective absorption of said powder on said lithographic printing plate.
Dependencies are inferred from the claim text.