Method of imaging and developing positive-working imageable elements

摘要

A method of making imaged elements such as lithographic printing plates is achieved by imagewise exposing a positive-working imageable element using energy of less than 300 mJ/cm2 to provide exposed and non-exposed regions. The imaged element is developed using an alkaline, silicate-free solution containing a carbonate to remove predominantly only the exposed regions to provide an image. The imageable element comprises a substrate and a radiation absorbing compound, and has an imageable layer on the substrate that comprises a developability-enhancing compound and a poly(vinyl acetal) in which at least 25 mol % of its recurring units comprise pendant nitro-substituted phenolic groups.