Polyester resin is the most popular binder for full color toners, because of the excellent dispersibility of colorants, the higher fixing ability, durability and transparency on OHP film. However, it is not easy to use polyester resin as positively chargeable color toners, because polyester resin has carboxylic groups, which show itself negative charge polarity.Polyester resin, which has lower acid value and styrene-acrylic resin would be useful for positive charged toners, but the dispersibility of colorants is not sufficient. That causes poor chroma in the print images.In this paper, the positive charged full color toners, which have the excellent dispersibility of colorants and the good charge stabilization, are investigated. Binder formulation consisted of polyester resin and styrene-acrylic resin. Polyester resin had high acid value for the better dispersibility of colorants and styrene-acrylic resin had alkyl-amino groups for highly positive charge. It was found that the dispersibility and the charged level are controlled by changing the ratio of two kinds of resins.
Yutaka Kanamaru, Koji Akiyama, "Positively Chargeable Full Color Toners Using Polyester Resin" in Proc. IS&T Int'l Conf. on Digital Printing Technologies (NIP15), 1999, pp 553 - 555, https://doi.org/10.2352/ISSN.2169-4451.1999.15.1.art00044_2