Manufacture of a planographic printing plate by making silver halide areas of emulsion oleophicic

Claim 1

A method for the preparation of a planographic printing plate containing the step of: image-wise photo-exposing a photographic material containing a silver halide emulsion layer, in which the silver halide is present in a water-permeable colloid binder to form in said material exposed image regions and unexposed background regions, developing the information-wise photo-exposed photographic silver halide material to leave a poorly water-soluble silver salt in one of said image and background regions, and treating said developed material containing said poorly water-soluble silver salt in said region with an aqueous liquid to render the regions thereof containing said silver salt receptive to lithographic printing ink, said treating liquid containing dissolved therein at least one organic cationic onium compound, iodide ions, and a sufficient amount of hydronium ions (H 3 O + ) for creating an acidic medium, said liquid being capable upon overall contact for 30 sec at 22° C of making an unexposed and undeveloped photographic silver halide test material sufficiently receptive to a test lithographic ink to form when used for lithographic printing with said lithographic ink, a printed ink deposit on lithographic printing paper having a spectral density of at least 0.5 measured at the absorption maximum of said ink, said photographic test material comprising a flexible polymeric film or paper support carrying a silver halide emulsion layer with the following characteristics: 1. said silver halide is silver chlorobromide (75:25 mole % chloride to bromide), 2. the average grain size of the silver halide is 0.35 micron, 3. the silver halide coverage, expressed as silver nitrate, is 10 g per sq.m., 4. the ratio by weight of gelatin to silver halide, expressed as silver nitrate, is 5.8:10, 5. the thickness of the emulsion layer is 8 microns, and 6. the emulsion layer is coated with an anti-abrasion layer having a thickness of 0.6 micron applied from a coating composition containing gelatin, silica particles and formaldehyde, the formaldehyde being present in a weight ratio of 6:100 with respect to the gelatin, the silica particles having an average grain size of 5 microns, the coverage of silica particles being 0.01 g per sq.m, and the gelatin coverage being 0.6 g per sq.m; and said test lithographic ink has the following composition: ______________________________________ parts by weight ______________________________________ Lake Red C (C.I. 15,585) 80 Styrenated linseed-tung oil alkyd of 60 per cent oil length and 10 per cent styrene content 100 aliphatic petroleum having a boiling range of 260-290° C 50 lead metal (as naphthenate) 1 cobalt metal (as naphthenate) 0.12. ______________________________________

Claim 2

A method for the preparation of a planographic printing plate containing the step of: image-wise photo-exposing a photographic material containing a silver halide emulsion layer, in which the silver halide is present in a water-permeable colloid binder to form in said material exposed image regions and unexposed background regions, developing the information-wise photo-exposed photographic silver halide material to leave a poorly water-soluble silver salt in one of said image and background regions, and treating said developed material containing said poorly water-soluble silver salt in said region with an aqueous liquid to render the regions thereof containing said silver salt receptive to lithographic printing ink, said treating liquid containing dissolved therein at least one organic cationic onium compound, iodide ions, and a sufficient amount of hydronium ions (H 3 O + ) for creating an acidic medium, said liquid being capable upon overall contact for 30 sec at 22° C of making an unexposed and undeveloped photographic silver halide test material sufficiently receptive to a test lithographic ink to form when used for lithographic printing with said lithographic ink, a printed ink deposit on lithographic printing paper having a spectral density of at least 0.5 measured at the absorption maximum of said ink, said photographic test material comprising a flexible polymeric film or paper support carrying a silver halide emulsion layer with the following characteristics: 1. said silver halide is silver chlorobromide (75:25 mole % chloride to bromide), 2. the average grain size of the silver halide is 0.35 micron, 3. the silver halide coverage, expressed as silver nitrate, is 10 g per sq.m., 4. the ratio by weight of gelatin to silver halide, expressed as silver nitrate, is 5.8:10, 5. the thickness of the emulsion layer is 8 microns, and 6. the emulsion layer is coated with an anti-abrasion layer having a thickness of 0.6 micron applied from a coating composition containing gelatin, silica particles and formaldehyde, the formaldehyde being present in a weight ratio of 6:100 with respect to the gelatin, the silica particles having an average grain size of 5 microns, the coverage of silica particles being 0.01 g per sq.m, and the gelatin coverage being 0.6 g per sq.m; and said test lithographic ink has the following composition: ______________________________________ parts by weight ______________________________________ Lake Red C (C.I. 15,585) 80 Styrenated linseed-tung oil alkyd of 60 per cent oil length and 10 per cent styrene content 100 aliphatic petroleum having a boiling range of 260-290° C 50 lead metal (as naphthenate) 1 cobalt metal (as naphthenate) 0.12. ______________________________________