MANUFACTURE OF LITHOGRAPHIC PLATE

摘要

PROBLEM TO BE SOLVED: To provide a printing plate suppressed in etch pit and excellent in ink receiving property and printing resistance by developing an aluminum lithographic plate having a silver halide emulsion layer containing a specified mole % or more of silver bromide at a specified temperature or more for a specified time or less. SOLUTION: An aluminum lithographic plate formed of a silver halide emulsion layer containing 10 mole % or more and 40 mole % or less of silver bromide is developed at a temperature of 25 deg.C or more for a time of 15 seconds or less. The upper limit of the developing temperature is up to about 35 deg.C where gelatin is not hardened, since gelatin is melted at an excessive high temperature. The lower limit of the developing time is up to about 3 seconds from the viewpoint of stable development of the whole plate. Thus, a high- temperature short-time development is performed even with a high pH developer, whereby etch pit is suppressed, and transfer silver excellent in ink receiving property and printing resistance can be provided. pH is preferably within a range of about 12.5 to about 13.5.