| 摘要 |
PURPOSE:To prevent unclear printing by forming a photosensitive diazo resin layer and a silicone rubber layer on a support and by further forming a light transmitting coating layer after piercing through holes each having a specified diameter in the layer. CONSTITUTION:A photosensitive layer of a diazo resin such as the condensation product of p-diazodiphenylamine with aldehyde is formed on an Al support having an anodically oxidized surface, and a silicone rubber layer contg. dimethylpolysiloxane having terminal hydroxyl groups, a cross-linking agent, etc. is formed to obtain a lithographic plate requiring no dampening water. A light transmitting coating layer obtd. by piercing 0.1-300/cm<2> holes each having 20-500mum diameter in a transparent polyester film or the like is further formed on the silicone rubber layer. When the resulting original plate for a photosensitive printing plate is exposed, gaseous N2 generated from the photosensitive diazo resin layer is removed from the holes of the coating layer to prevent unclear printing. |
