PHOTOINITIATOR, PHOTOPOLYMERIZATION COMPOSITION, RADICAL GENERATION METHOD, PHOTOSENSITIVE MATERIAL FOR LITHOGRAPHIC PRINTING PLATE, AND PRINTING PLATE FORMING METHOD

摘要

PROBLEM TO BE SOLVED: To obtain a photopolymerizable composition capable of forming an image good in resolution and sensitivity by incorporating a radical generator and a specified dye. SOLUTION: The photopolymerizable composition contains the radical generator and the dyes represented by formulae I-III in which each of R1 and R2 is an H atom or a monovalent substituent; X is an oxygen or sulfur atom; each of L1 -L5 is a methine group; and each of B1 -B3 is a 5- or 6-membered aromatic or heterocyclic group. This photosensitive composition may optionally contain other components, such as a sensitizer, a polymerization accelerator, a thermopolymerization inhibitor, a heat meltable compound, an oxygen replenishing agent, and a plasticizer, so long as these do not obstruct attainment of the objects, thus permitting the obtained photopolymerizable composition to be written in by a light near a wavelength of 488nm or 532nm and to form an image.