| 摘要 |
The present invention pertains to a process for the preparation of a toner powder, in which particles of one or more toner base compositions are combined into larger particles. The toner base compositions may be in the form of dry powders, e.g., manufactured by jet milling or by freeze drying powder dispersions. In that case, the combination of the toner base compositions into larger particles may be done by, e.g., mechanofusion. The toner base composition may also be in the form of an aqueous emulsion or dispersion. In that case, the combination of the base compositions into larger particles can be effected by spray-drying the emulsion or dispersion. In a preferred embodiment, the toner base composition in aqueous form is prepared via phase inversion emulsification, which preferably is carried out in an extruder. The invention also pertains to a toner powder comprising composite particles in which individual particles of toner base composition(s) are fused or bonded together in the form of cluster structures that do not break down under the mechanical and electrostatic forces encountered during toner use. This can be obtained by mechanofusion of dry toner base powders. The invention also pertains to a toner powder comprising composite particles in which individual particles of toner base composition(s) are fused or bonded together to form single substantially spherical particles. This can be obtained by spray drying of an aqueous emulsion or dispersion. The toner powders of the present invention have increased fluidity as compared to conventional powders. Toners with different colours can be prepared in a simple and convenient manner. |
