Lithographic printing plate and method for its' manufacture using laser irradiation

摘要

Imaging of lithographic printing plates with reduced fluence requirements is accomplished using printing members that have a solid substrate (20), gas-producing and radiation-absorptive layers (12, 14) over the substrate, and a topmost layer (10) that contrasts with the substrate in terms of lithographic affinity. Exposure of the radiation-absorptive layer (12) to laser light causes this layer to become intensely hot. This, in turn, activates the gas-producing layer (14), causing rapid evolution and the expansion of gaseous decomposition products. The gases stretch the overlying topmost layer to create a bubble (60) over the exposure region, where the imaging layers have been destroyed. If this process is sufficiently explosive, the neck of the bubble expands beyond the diameter of the incident laser beam, tearing the topmost layer and the underlying imaging layers away from the substrate outside the exposed region. The entire affected area is easily removed during a post-imaging cleaning process, resulting in an image spot larger than the incident beam diameter.