MANUFACTURE OF PLANOGRAPHIC PRINTING ORIGINAL PLATE

摘要

PROBLEM TO BE SOLVED: To enable a printing original plate to be handled in a light room, to unnecessitate development in a photomechanical process and to make manufacturable a planographic printing plate free from a residual color by disposing a physical developing nucleus layer on a hydrophilic layer in such a way that the physical developing nucleus layer has such surface activity as to form a specified amount of physically developed silver by processing with a specified physical developing solution and forming a thin silver film. SOLUTION: A physical developing nucleus layer is disposed on a hydrophilic layer in such a way that the physical developing nucleus layer has such surface activity as to form 0.3-1.3 g/m2 physically developed silver by processing with a physical developing solution at 23 deg.C for 30 min and a thin silver film is formed on the hydrophilic layer to manufacture the objective planographic printing original plate. The physical developing solution is prepared by adding 1 part solution (B) to 5 parts solution (A). The solution A is prepared by adding water to 180 g sodium sulfite anhydride and 75 ml silver nitrate (10% solution) in such an amount as to give 1,000 ml. The solution B is prepared by adding water to 20 g sodium sulfide anhydride and 20 g hydroquinone in such an amount as to give 1,000 ml. A part of the thin silver film corresponding to a non-image area is removed by heat-mode laser exposure to manufacture a planographic printing plate.