Developer for photopolymerizable presensitized plate for use in making lithographic printing plate and method for preparing lithographic printing plate

摘要

A developer for a photopolymerizable presensitized plate for use in making a lithographic printing plate characterized in that it comprises an alkali silicate and a nonionic compound represented by the following general formula (I), it has a molar ratio: SiO2/M2O (wherein M represents an alkali metal or an ammonium group) ranging from 0.75 to 4.0, a pH value ranging from 11.5 to 12.8 and a conductivity ranging from 3 to 30 mS/cm: A-W wehrein A represents a hydrophobic organic group whose logP as determined for A-H is not less than 1.5 and W represents a nonionic hydrophilic organic group whose logP as determined for W-H is less than 1.0; a method for preparing a lithographic printing plate comprising the steps of imagewise exposing, to light, a presensitized plate for use in making a lithographic printing plate, which comprises a substrate provided thereon with a photopolymerizable light-sensitive layer containing a compound having at least one addition-polymerizable ethylenically unsaturated double bond and a photopolymerization initiator; and then developing the exposed presensitized plate using the above developer. The developers and the method for making a lithographic printing plate according to the present invention can prevent scumming during printing and simultaneously attain sufficient printing durability without impairment of image-forming performance, and the developer can dissolve or disperse stably for a long period of time the compounds which are not soluble in the developer, and therefore the running performance of the developer can be excellent and stabilized.