DEVELOPER COMPOSITION FOR PRINTING PLATE, DEVELOPER AND METHOD FOR MANUFACTURING PRINTING PLATE

摘要

The present invention provides a water-based developer where the dispersibility of an image mask layer in a developer is good in a developing step of a water-developable printing original plate of a CTP system. Also, the present invention also provides a water-based developer where the scum dispersibility in the developer is good even the developing is repeatedly conducted in large quantities using the same developer in a developing step of a water-developable printing original plate of a negative system. According to the present invention, there is provided a developer composition for a printing plate containing (a) alkali metal salt of saturated fatty acid having carbon number of 12 to 18 and (b) alkali metal salt of unsaturated fatty acid having carbon number of 12 to 18 in a weight ratio of from 20:80 to 80:20 in terms of (a):(b). The developer composition may further contain an alkali agent (c). In this case, a weight ratio of (a):(b) may be from 20:80 to 80:20, and the alkali agent (c) may be contained in amount of 0.01 to 10 part(s) by weight to 100 parts by weight in total of the components (a) and (b).