| 摘要 |
PROBLEM TO BE SOLVED: To provide an offset printing method which satisfies the suitability for simple plate-making not using a developer, the printed image quality backed with the discriminability between an image part and a non-image part of a printing surface and a sufficient resistance to printing altogether. SOLUTION: An original plate for printing which has on the surface a metal having characteristics of high-temperature hydrophilic nature development is made hydrophobic and then the surface is subjected to image-pattern heating at the temperature of the high-temperature hydrophilic nature development, so as to form a hydrophilic/hydrophobic regional image-pattern distribution thereon. A water solution containing a water-soluble compound of a metal having a lower ionization tendency than the metal having the characteristics of the high-temperature hydrophilic nature development is brought into contact with the original plate and a metal thin layer is formed in an image pattern in the hydrophilic region by metal substitution. Moreover, a treatment for giving the hydrophilic nature to the hydrophobic region is executed and the original plate for printing thus treated is brought into contact with ink. Thereby a printing surface having received the ink is formed in the region having the metal thin layer and printing is conducted. |
