| 摘要 |
A method of making a planographic printing plate, the method includes, in this order, image-wise exposing, to infrared light, a positive-working planographic printing plate precursor including a positive-working recording layer provided on a substrate; and developing the positive-working planographic printing plate precursor after the exposure using an aqueous alkaline solution, in which the positive-working recording layer comprises a copolymer containing a structural unit derived from (meth)acrylonitrile and a structural unit derived from styrene, a water-insoluble and alkali-soluble resin, and an infrared absorbing agent, the solubility of the positive-working recording layer in the aqueous alkaline solution being increased by the exposure to infrared light, and in which the aqueous alkaline solution has a pH of from 8.5 to 10.8 and contains a betaine-based amphoteric surfactant and an ammonium salt represented by the following Formula (I):
wherein, R 1 , R 2 , R 3 , and R 4 each independently represent an alkyl group or an aryl group; the total number of carbon atoms contained in R 1 , R 2 , R 3 , and R 4 is not more than 20; and X - represents a counter anion. |
