| 摘要 |
PROBLEM TO BE SOLVED: To provide a positive lithographic printing plate which is excellent in scratch resistance, sensitivity, fouling preventive properties during printing, and plate wear properties and has a heat sensitive layer which is made alkali- soluble by the photothermal conversion of laser light. SOLUTION: In the lithographic printing plate, the heat sensitive layer containing a water-insoluble, alkali-soluble resin and an infrared absorbent dye and increasing its solubility in an alkaline aqueous solution by heating is formed on a support in which aluminum or an aluminum alloy is subjected to surface roughening and anodic oxidation treatment. The surface-roughened shape of the support has a pebble shape of at least large and small double complex structures comprising a large-wave structure and a small-wave structure. The large wave structure has an average wavelength of 0.5-30 μm, and the small wave structure has a pit structure 0.05-0.2 μm in average diameter. |
