| 摘要 |
PURPOSE:To provide a lithographic printing plate suitable for treatment with an alkaline activating soln. and having improved printing resistance by incorporating a developing agent into at least one gelatin-contg. layer and making the ratio of fine powder to hydrophilic colloid highest in an undercoat layer. CONSTITUTION:This lithographic printing plate has gelatin-contg. layers each having a pH value below the isoelectric point of the gelatin. At least one kind of compound selected from dihydroxybenze compounds and 1-phenyl-3-pyrazolidone compounds is used as a developing agent. A silver halide emulsion contains silver chloride, silver bromide, silver chlorobromide or a mixture of the silver halide with silver iodide, and a silver halide mixture contg. >= about 50mol% silver chloride is preferably contained. The base of a gelatin undercoat layer is made of only gelatin, or it is composed of gelatin and hydrophilic colloid of sodium alginate, a cellulose deriv., polyvinyl alcohol or the like. fine powder having 2-10mum average particle size is used in the undercoat layer by about 5-40pts.wt. per 100pts.wt. hydrophilic colloid. |
