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 E_1/2 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.

抄録全体を表示

Corona charging characteristics such as rates of charging, dark decay, and photo-induced discharge, and leakage currents have been measured on β-type metal-free phthalocyanine-polymer photoreceptor by a turn-table type corona charging apparatus. The leakage currents through the layer during the positive corona charging were shown to exhibit the feature of spacecharge-limited currents and they increased dramatically near the saturated surface potential.
The photoreceptor exhibited a high photosensitivity even at low surface potentials of 200 to 300 V. During corona charging, the leakage charge did not accumulate in the layer. This suggests that the sensitization by doping with electron acceptors such as tetranitrofluorenone, TENF, was caused mainly by interactions between phthalocyanine crystallites and the molecular dopants.

抄録全体を表示

In the preceding paper, it has reported that the photo-sensitivity of electrophotographic layer consisting of β-metal-free phthalocyanine and polymer is increased by the doping of the electron acceptor molecule. In this paper, energy level and density of traps are discussed from the results of thermally stimulated current (TSC) for these layers. The nondoped layers have the single trapping center for hole located at 0.35 eV above the valence band and the density is approximately 10¹⁷ 1/cm³. The large peak of TSC was observed for the layer doped with electron acceptor molecule but not for the nondoped layer without the optical excitation to fill the trapping centers. It is postulated that the surface traps are occupied by the holes due to the interaction between phthalocyanine pigments and electron acceptor molecules.

抄録全体を表示