As the resin particles which are dispersed in the nonaqueous dispersion of resin particles, desired are those having a narrow particle size distribution and high dispersion stability. Above all, in such fields as the liquid developer for electrophotography, the liquid developer for electrostatic recording, the oil-based ink for inkjet printer, the ink for electronic paper, and the like, there are demands for resin particles having a small particle diameter and a narrow particle size distribution.
In addition, in the field of electrophotography, there is a strong desire for decreasing power consumption by printing machines such as printers and the like by fixing toners at lower temperatures.
Therefore, in order to solve these problems, there has been proposed a method wherein a fatty acid monoester is added in the nonaqueous dispersion medium and, at the same time, a polyester resin is selected as the main component of the toner (see Patent Document 1). This method was intended to improve the fixing property of the toner by plasticizing the polyester resin with the fatty acid monoester. However, the toner particles obtained showed poor dispersion stability and were not entirely satisfactory in either particle size distribution or fixing property.