Process for producing pressure-fixable electrophotographic toners

Claim 1

A process for producing a pressure-fixable toner which comprises the steps of: dispersing or dissolving a starting material mixture containing (a) a colorant and/or magnetic particles, (b) a pressure-fixable binding material selected from the group consisting of higher fatty acids, metallic salts of higher fatty acids, derivatives of higher fatty acids, amides of higher fatty acids, natural waxes, synthetic waves, rosin derivatives, polyolefins, olefin copolymers, silicone resins, alkyd resins, natural resin-modified phenol resins, maleic acid-modified phenol resins, phenol resins, rubber and styrene resins; and (c) a capsule wall-forming resin selected from the group consisting of homopolyumers of styrene or vinyl monomers, copolymers of styrene and vinyl monomers, and epoxy resins in an organic solvent; dispersing the resulting dispersion or solution in an aqueous dispersion-stabilizing solution; then gradually heating the thus-obtained dispersion up to the azeotropic temperature of the water-organic solvent to drive off the major portion of the organic solvent from the dispersed droplets and phase-separating the capsule wall-forming resin dissolved in the organic solvent on the surface of the dispersed toner droplets containing components (a) and (b) to form a capsule wall around the surface of the droplets; dispersing the resulting encapsulated toner in a lower alcohol to extract and remove the organic solvent remaining within the encapsulated toner; and thereafter drying the encapsulated toner.