| 摘要 |
PROBLEM TO BE SOLVED: To provide a photosensitive planographic printing plate which is good in plate wear, small dot reproducibility, the opening of the mesh of dots and dot gain when printing is executed under high-speed and severe conditions like those of rotary offset printing, is excellent in ball-point pen adaptability and obviates the erosion of the plate when printing is executed by using moistening water devoid of isopropyl alcohol. SOLUTION: An aluminum base is provided with undulations of 3 to 30μm in the average wavelength of roughness or approximately spherical projections which are superposed with small pits having an average opening diameter of 0.2 to 3.0μm in a congested form on large pits having an average opening diameter of 3 to 30μm and has an average diameter of >=0.01μm and below 1/2 the average opening diameter of the small pits within the small pits. This aluminum base is, thereupon, provided with a photosensitive layer contg. a o-naphthoquinone diazido sulfonic acid ester of an polycondensation resin of polyhydroxyphenol having a number average mol.wt. of 3.00×10<2> to 2.00×10<3> and a weight average mol.wt. of 5.00×10<2> to 4.00×10<3> and ketone or aldehyde and an alkali-soluble resin, by which this printing plate is obtd. |
