| 摘要 |
PURPOSE:To simply obtain a lithographic plate having superior printing resistance with an output signal from a computer or the like, that is, by exposure or heat application by forming an image forming layer contg. a specified tetrazolium salt (co)polymer and a photoreducing agent or a thermal reducing agent on a hydrophilic support. CONSTITUTION:A (co)polymer represented by formulaIor II (where each of R1 and R2 is H, CH3, NO2, OH or COOH, X is Cl or Br, and n is 10-10,000) is used. The copolymerizable monomer is styrene, a styrene deriv., acrylic acid or the like. An image forming layer contg. the (co)polymer and a photoreducing agent such as quinone combined with an active hydrogen feeding source such as disulfide or polyethylene glycol or a thermal reducing agent such as polyphenol is formed on a hydrophilic support such as an Al plate provided with a hydrophilic property to obtain a water-developable original plate for lithography. The plate is imagewise exposed, or heat is imagewise applied to the plate by means of a thermal head. By immersing the plate in water, the unexposed part or the unheated part is dissolved and removed to manufacture a lithographic plate having superior printing resistance and giving clear prints. |
