Abstract
Photoconductive metal-free phthalocyanine was dispersed in positive-working-type photopolymer and coated on an aluminum plate, and a plate-making process was applied, which consisted of corona charging, image exposure, liquid toner development, uniform UV exposure and alkaline development steps.
The plate could be charged either positively or negatively to 227 or 203V, respectively. When exposed by a tungsten lamp, the incident energies E1/2 required to discharge the photoreceptor to one-half its maximum surface potential were 99 and 127 erg/cm2 for positively and negatively charged cases respectively. The electrophotographic sensitivity is increased by doping of electron acceptors in this layer. The incident energies E1/2 were 44 and 80 erg/cm2 for the layer doped with 2, 4, 5, 7-tetranitro-9-fluorenone, in positively and negatively charged cases respectively.
The layer could be easily dissolved into alkaline solution, due to the use of positive-type photopolymer as the binder resin. The layer exposed to UV light was dissolved away by the aqueous alkaline solution as same as the conventional presensitized plate. The present plate has an excellent photosensitivity suitable for projection-type and laser scanning-type platemaking.
