To provide a method of preparing a lithographic printing plate which prevents the occurrence of development scum, achieves both of good developing property and good printing durability, and is free from the odor generation, even when development with a developer of an acidic to weak alkaline range is conducted.
A method of preparing a lithographic printing plate comprises: exposing imagewise a lithographic printing plate precursor having a photosensitive layer containing (A) a hexaarylbisimidazole compound, (B) a polymerizable compound having a hydrocarbon group having 6 or more carbon atoms in its molecule, (C) a sensitizing dye and (D) a binder polymer and a protective layer on a hydrophilic support in this order using laser; and removing the protective layer and an unexposed area of the photosensitive layer of the exposed lithographic printing plate precursor using a processing solution having pH of 2 to 11, wherein the processing solution contains (E) a compound represented by general formula (I) or (II). In the general formula (I) or (II), R1 represents a k-valent straight-chain, branched or cyclic aliphatic hydrocarbon group having from 6 to 25 carbon atoms, R2 represents a k-valent straight-chain, branched or cyclic aliphatic hydrocarbon group, R3 represents a monovalent straight-chain, branched or cyclic aliphatic hydrocarbon group, wherein each may be substituted with a hydroxy group, an alkoxy group, an acyl group or an alkoxycarbonyl group, R2 and R3 may be combined with each other to form a ring, provided that a total number of carbon atoms included in R2 and R3 is from 5 to 25, L1 represents -C(=O)-O-, -C(=O)- or -O-, and k represents an integer of 1 or more.
INNO NORIBUMI
ARIMURA KEISUKE
TAGUCHI TAKANORI
Kiyozumi Yazawa
Next Patent: IMAGE FORMING METHOD AND ELECTROPHOTOGRAPHIC PHOTORECEPTOR