Light-sensitive material for preparing a lithographic printing plate and a process using the same

A process of preparing a lithographic printing plate which comprises:

• (1) imagewise exposing a light-sensitive lithographic printing plate material comprising a support having a hydrophilic surface provided in order with a layer of a positive-working light-sensitive resin composition which comprises an o-quinone diazide compound and which is capable of forming an oleophilic image, a tannable interlayer containing a tanning developing agent, which interlayer is a silver halide emulsion layer wherein the amounts of the tanning developing agent and the silver halide therein are 0.01 to 100 mmols and 0.01 to 10 mmols, respectively, per square meter of area and 1.mu. of dry thickness of the interlayer and a tannable light-sensitive silver halide emulsion layer containing a tannable developing agent such that a silver image is formed in the light-sensitive silver halide emulsion layer by the subsequent activating processing with an alkali solution, wherein the tanning developing developing agent is present in the light-sensitive silver halide emulsion layer in an amount of about 0.01 to 100 mmols per 1.mu. thickness and square meter of the light-sensitive silver halide emulsion layer, and wherein the amounts of tanning developing agent and silver halide in the interlayer are less than the amounts thereof in the light-sensitive silver halide emulsion layer, (2) forming a tanned silver image by activation processing using an alkali solution, (3) washing off portions of the silver halide emulsion layer where no silver images have been formed to thereby leave tanning-hardened silver image portions on said light-sensitive resin composition layer, thus forming a hardened relief silver image, (4) uniformly irradiating with light to which said light-sensitive resin composition is sensitive, in an amount such that the light-sensitive resin composition layer in the areas where the relief silver image is not present will dissolve in an alkaline developer, and (5) developing the material with an alkaline developer capable of dissolving the light-sensitive resin composition layer in areas where the relief silver image does not exist to thereby form a relief image comprising the insoluble portions of the light-sensitive resin composition layer and the hardened relief silver image lying thereon.