NEGATIVELY CHARGEABLE TONER FOR ELECTROSTATIC CHARGE IMAGE DEVELOPMENT, ITS PRODUCTION AND DEVELOPER USING THE SAME

摘要

PURPOSE:To provide the production of the toner, with which reduction in particle size of the toner can be attained and the negatively chargeable toner excellent in color tone reproducibility, chargeability and environmental resistance can be produced by granulating a solution contg. as a constituent of the toner material a polyester resin dissolved into a solvent in an aqueous medium contg. an inorganic dispersant that has specified average particle size and removing the solvent from the granules. CONSTITUTION:In this production, the toner material contg. a polyester resin and a colorant is dissolved into a solvent in which the polyester resin is soluble and this toner material solution (toner mother liquor) contg. the dissolved polyester resin and the colorant is granulated into granules having prescribed particle size in an aqueous medium contg. an inorganic dispersant that has 0. 7 to 5mum average particle size. At this time, the mixing ratio of the aqueous medium to the toner mother liquor is preferably 90:10 to 50:50 ((aqueous medium):(toner mother liquor)) by weight. As the inorganic dispersant having 0.7 to 5mum average particle size, calcium tertiary phosphate and/or hydroxyapatite are preferred. After the granulation the solvent is removed from the granules under prescribed conditions of pressure and temp.