| 摘要 |
PROBLEM TO BE SOLVED: To obtain a positive linear lithographic printing original plate without the necessity of complicated steps after a laser beam is illuminated by incorporating a photothermal conversion substance and a metal chelate compound in a thermosensitive layer. SOLUTION: At least a photothermal conversion substance and a metal chelate compound are contained in a thermosensitive layer. According to this constitution, at the time of illuminating a laser beam, a heat is generated by an operation of the substance in the layer to thereby react the chelate compound with an active hydroxyl group-containing compound. As a result, an adhesive force of a hydrophilic swelling layer to the thermosensitive layer is improved in a laser beam illuminated part. Meanwhile, since such an adhesive forced is not improved in an unilluminated part, the swelling layer or the swelling layer and the thermosenstive layer can be removed by its following developing. Thus, a positive linear lithographic printing plate can be obtained merely by developing after the laser is illuminated. |
