Abstract: An imaged and developed element, such as a lithographic printing plate, is provided by infrared radiation imaging of a negative-working imageable element having an outermost imageable layer that includes an acid generating compound that generates acid upon exposure to imaging infrared radiation, an infrared radiation absorbing compound, an acid activatable crosslinking agent that has acid activatable reactive groups, and a polymeric binder that is capable of undergoing an acid-catalyzed condensation reaction with the crosslinking agent. The imaged element is heated at from about 120 to about 150° C. for up to two minutes, and then developed with a single processing solution to remove only the non-exposed regions and to provide a protective layer prior to lithographic printing.

Abstract: Both single-layer and multi-layer positive-working imageable compositions can be used in positive-working elements having a substrate and at least one imageable layer. These elements can be used to prepare lithographic printing plates. The imageable elements include a radiation absorbing compound and a hydroxystyrene polymer having repeating branched hydroxystyrene units.