ELECTROPHOTOGRAPHIC COLOR TONER

摘要

PURPOSE:To enable the adequate electrostatic charge of toner particles even under a high humidity environment without being affected by an environmental humidity change by consisting coloring agents of org. pigments which are of a specific value or below in the specific electric conductivity of the extract by ion exchange water. CONSTITUTION:The org. pigments are required to be <=150mus/cm in the specific electric conductivity of the extract obtd. by extracting these pigments with the ion exchange water. The toners are easily affected by the humidity change of the environment and do not exhibit the adequate electrostatic chargeability under the high humidity environment if the specific electric conductivity is larger than 150mus/cm. The org. pigments having <=150mus/cm specific electric conductivity of the extract by the ion exchange water are obtd. by repeating washing with water in a washing stage in the final stage of the synthesis process thereof, then dehydrating the pigments and drying the resulted pigment paste. This process may be made master batchwise by kneading the pigments in the state of wet cake with a part of a binder resin without passing the cake to the drying state after dehydrating in such a case.