| 摘要 |
PURPOSE:To obtain a planographic printing plate excellent in preservable property without decreasing print wear by incorporating a specified mercapto compd. and specifying the amt. of the sensitizing dyestuff. CONSTITUTION:This planogrpahic printing plate has at least one base coating layer, a silver halide emulsion layer, and physical development nucleus successively applied on a supporting body. The silver halide emulsion layer contains a sensitizing dyestuff showing the max. spectral sensitivity in a long wavelength region over >=700nm. This silver halide emulsion layer contains at least one mercapto compd. expressed by formula I and/or formula II. The amt. of the sensitizing pigment is controlled in a range over the point at which the sensitizing pigment gives the max. spectral sensitivity and the spectral sensitivity decreases, and further the amt. is controlled to between >=1.5 and <=4 times of the amt. which gives the max. spectral sensitivity. In the formula I, R1 and R2 are hydrogen atoms, alkyl groups, aryl groups, sulfone amide groups, etc., and the sum of carbon numbers of R1 and R2 is >=3. In the formula II, R3 is an alkyl group or aryl group having >=3 carbon number. |
