| 摘要 |
PURPOSE:To obtain a raw plate for lithographic printing capable of forming a superior image through imagewise exposure or heat application, and development using an aq. developing soln., by providing an image forming layer containing tetrazolium salt and causing reducing action by light or heat on a hydrophilic support. CONSTITUTION:A raw lithographic plate is prepared by forming on a hydrophilic support, such as an aluminum plate an image-forming layer consisting essentially of a photoreducing agent, such as aromatic disulfide or quinones, or a heat reducing agent, such as polyphenols, or hydroxylamines, and tetrazolium salt having general formulaI, II in which R1, R2, R4-R7 are aryl or heterocyclic; R3 is alkyl, aryl, heterocyclic, COOH, carboxyester, SH, OH, NH2, carbamyl, sulfo, or sulfamoyl; X is Br, Cl, or BF4; and A has formula III-VI. This raw plate is subjected to imagewise exposure or heat application, and freed of nonimage areas through water washing to disclose a hydrophilic face, thus permitting a superior printing plate to be obtained. |
