| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and apparatus for negative type offset printing by carrying out plate making readily without the necessity of alkaline developer, and having a practical printing image quality of high discrimination in the image part and nonimage part of a printing surface, and also enabling printing paper to be used repeatedly. SOLUTION: The method and apparatus for offset printing is effected such that a printing original plate being composed in its surface of a heat reactive substance such as titanium oxide and zinc oxide is heated at a hydrophobic developing temperature to make a surface hydrophobic before being subjected to image-like heating at a high temperature hydrophilic developing temperature to form an image like distribution of a hydrophilic area and hydrophobic area; which thereby printing ink is accepted in the hydrophobic area. Furthermore, this is the reusing method of a printing original plate employing the printing original plate again by cleaning and removing ink staying on the face of a print-finished printing plate, thus, in particular, improving printing quality by making a hydrophobic property in the presence by a volatile organic compound. |
