| 摘要 |
A method of preparing a lithographic printing plate which involves providing a plate precursor comprising a grained and anodised aluminium substrate coated with a metallic silver layer, imagewise exposing the precursor to a high intensity laser beam, to the metallic silver layer in the exposed areas and treating the plate by chemical and mechanical means in order to remove stains on the plate surface. The method provides press ready plates free of background stain, which give a clean, even appearance in exposed areas and show high image resolution and excellent durability on press, whilst eliminating the requirement for the use of intermediate film and developer chemistry. The chemical treatment preferably involves an oxidant, such as a ceric salt or a mereapto compound, and an enzyme, surfactant, sequestering agent (e.g. EDTA), and a buffer may also be present. Scrubbing with a rotating brush or roller is the preferred mechanical treatment.
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