| 摘要 |
PROBLEM TO BE SOLVED: To provide an offset printing method which enables easy plate making without the necessity to use an alkaline developing solution and shows a printed image quality of a practical use level with a printed face highly distinguishable as an image part and a non-image part and high resistance to plate wear and further, enables an original printing plate to be repeatedly used. SOLUTION: The surface of an original printing plate having a photocatalytic activity or high-temperature hydrophilic developing properties is made hydrophobic and then made hydrophilic like an image so as to form an iamgewise distribution of a hydrophobic region and hydrophilic region. Further, on the surface of the original printing plate, a layer of an aqueous solution containing a metallic compound and an electrolyte is formed and the original printing plate is used as one of electrodes with the formation of a metal film in the hydrophilic region on the original printing plate. After that, a non-electrodeposition region which is made hydrophobic is subjected to a treatment to make the region hydrophobic according to necessity. Finally, the original printing plate is brought into contact with ink to perform the printing.
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