The present invention provides a photosensitive composition comprising an infrared absorbing agent represented by the following formula (I) and a polymer compound which is insoluble in water and soluble in an aqueous alkali solution and becoming soluble in an aqueous alkali solution by radiation of an infrared laser. In the formula described below, R1 and R2 independently represent an alkyl group having 1 to 18 carbon atoms or an alkyl group having 9 to 30 carbon atoms and Z represents a heptamethine group which may have a substituent. The definitions of other substituents are shown in the specification. According to the present invention, a photosensitive composition having high development latitude and storage stability, together with a positive type planographic printing plate for direct plate-making which can form an image with high sensitivity by using an infrared laser, are provided.
本发明提供了一种光敏组合物,该组合物包括下式(I)所代表的红外线吸收剂和一种聚合物化合物,该聚合物化合物不溶于
水,溶于碱
水溶液,在红外线激光的照射下可溶于碱
水溶液。在下述式中,R1 和 R2 独立地代表具有 1 至 18 个碳原子的烷基或具有 9 至 30 个碳原子的烷基,Z 代表可能具有取代基的庚基。其他取代基的定义见说明书。根据本发明,提供了一种具有高显影纬度和储存稳定性的感光组合物,以及一种用于直接制版的正片式平面印刷版,它可以通过使用红外激光形成高感光度的图像。