| 摘要 |
<p>An object of the present invention is to provide a planographic printing original plate which can be used as an offset printing master, particularly a planographic printing original plate (which can be formed by a so-called direct plate-making process) which can be directly inscribed based on digital signals of a computer or the like by using an infrared laser. The above-described object is achieved by the planographic printing original plate of the present invention, which comprises an intermediate layer which contains a polymer including, as a monomer unit, at least a monomer having an acid group and a monomer having an onium group; and a photosensitive layer comprised of a positive-type photosensitive composition for an infrared laser which contains: (A) at least an alkali-soluble polymeric compound; (B) a compound which has a function to deteriorate the solubility of the alkali-soluble polymeric compound in an alkaline aqueous solution due to compatibility with the alkali-soluble polymeric compound, the function deteriorating by compound (B) being heated; and (C) a compound which generates heat by absorbing light, the intermediate layer and the photosensitive layer being formed sequentially on a support which has been subjected to a hydrophilizing treatment.</p> |
