New Generation of NPH, Thermal CTP Plates

The mechanism of commercial, positive-working, thermal CTP plates is based on physical insolubilization within a single layer between a polymer and an insolubilizer. Rapid heating on exposure causes the insoluble, hydrogen-bonded structure to break and solubility in a high pH developer is restored. Fast imaging speeds are achieved, but shelf life is limited. Crucially, the plates have limited resistance to aggressive blanket wash, plate cleaning agents and alcohol substitutes in fountain water. Attempts to improve solvent resistance by modification of the polymers, or addition of alternative polymers, will fail. Resulting plates have neither blanket wash resistance nor fast imaging speed. We will discuss a new generation of CTP plates where solvent resistance and fast imaging speed are obtained through use of distinct layers. This two-layer, physical deformation mechanism also demonstrates excellent shelf life, and development can be tailored through material choice for either high or low pH developers.