| 摘要 |
PROBLEM TO BE SOLVED: To improve an image reproducibility and printability of a lithographic printing plate by a solid ink jet type by treating a surface of the plate on which a solid ink is printed with an alkaline solution. SOLUTION: A solid ink 4 is printed in an image-like state by a solid ink jet type printer or the like on a printing plate 3 obtained by providing an alkali soluble resin layer 2 on a support having a hydrophilic surface. Then, a plate surface is hand etched by a sponge in which an alkaline solution such as, for example, a potassium silicate aqueous solution is impregnated. And, the layer 2 of a non-image part to which the ink 4 is not adhered is dissolved and removed. Thereafter, the plate 3 is heated as needed. When it is thereafter printed, the ink 4 of a part diffused on the non-image part is easily released due to high hydrophilic property and weak adhesive strength of the surface of the plate 3, and becomes an initial dot size. And, it is brought into contact with the solution after the printing, and the plate surface is rubbed by a scraping blade under a predetermined pressure. |
