As a method for producing a toner, there is known a production method called “aggregation method”. The aggregation method is carried out according to the following procedure. First, toner components such as a binder resin, a colorant, and a release agent are aggregated using an aggregating agent such as a metal salt in a medium such as water by intentionally destroying the dispersed state of the respective particles, whereby aggregated particles are obtained. Subsequently, the obtained aggregated particles are fused by a heating treatment, whereby a toner is obtained. The fusing step and the aggregation step are sometimes performed simultaneously.
In this aggregation method, a toner is produced by, for example, aggregating particles in the nanometer order, and therefore, the particle diameter of the toner can be reduced and also the shape of the toner can be changed according to the conditions for the heating treatment for fusing the particles, and therefore, this method is very suitable as the method for producing a toner.
However, the aggregation method in the related art has a problem that, among the constituent components of the toner, a component in the form of particles having higher hydrophilicity than the binder resin or a component in the form of particles having a micron-order particle diameter is easily exposed on a toner surface.
Further, as a decolorizable colorant, there is known a colorant obtained by microencapsulation of a color developable agent including a leuco dye or the like and a color developing agent. The coloring power of a leuco dye-based material is much lower than that of a pigment, and therefore, in order to form a toner having a sufficient coloring power, it is necessary to incorporate a large amount of the colorant in the toner. However, when a toner is produced by the aggregation method using such a microencapsulated colorant, the above-described problem of exposure of the component on the toner surface or detachment of the component is liable to occur, and thus, it is not easy to incorporate a large amount of such a microencapsulated colorant in the binder resin.