PRODUCTION OF ELECTROPHOTOGRAPHIC TONER

摘要

PROBLEM TO BE SOLVED: To obtain a spherical toner of a small particle diameter excellent in balance of thermal characteristics by forming fine particles by forced emulsification with a hydrophobic org. solvent and glowing them by the combination of pulverization with association. SOLUTION: A mixture contg. an acid group-contg. polyester resin, a colorant and a hydrophobic org. solvent as essential components and an aq. medium are mixed, stirred and emulsified by high shearing action in the presence of a neutralizing agent to form colorant-contg. fine particles (a). The particles (a) are then associated to form colorant-contg. spherical fine particles (b) and the particles (b) dispersed in the liq. medium are taken out as dry powder. The self-water dispersibility (hydrophilic property) of the acid group-contg. polyester resin dissolved or dispersed in the hydrophobic org. solvent is increased by neutralization and phase inversion emulsification is forcedly caused by applying shear under practically soap-free conditions to form the fine particles (a) in the aq. medium.