| 摘要 |
The present invention provides a method for making an offset printing plate according to the silver salt diffusion transfer process comprising the steps of: image-wise exposing an imaging element comprising in the order given on a hydrophilic surface of a support (i) an image receiving layer containing physical development nuclei and (ii) a photosensitive layer comprising one or more photosensitive silver halide emulsions said photosensitive layer being in water permeable relationship with said image receiving layer, applying an aqueous alkaline solution to the imaging element comprising at least 0.05 mole/l of ascorbic acid as the main developer, at least 0.010 mole/l of an auxiliary developer of the class of the 1-phenyl-3-pyrazolidones and an aminoalcohol in an amount from 0.1 ml to 10 ml as silver halide solvent to form a silver image in said image receiving layer, treating the imaging element to remove the layer(s) on top of the image receiving layer, thereby exposing the imaged surface of the support by uncovering said silver image formed in said image receiving layer, characterized in that said aqueous alkaline solution contains sodium ions but no potassium ions or sodium and potassium ions in which case the molar ratio of sodium ions to potassium ions in said aqueous alkaline solution is at least 3:1. |
