Silica and metal oxides are used to modify the physical and triboelectric properties of electrophotographic toners resulting in improvements in key attributes such as image quality and triboelectric charging characteristics. The mixing energy intensity of the powder blending process for toner surface treatment effects the degree of dispersion and embedment of these materials on the toner particle surface. Quantitative surface elemental analysis was used to characterize the toner particle surface composition after surface treatment. Surface treated toner properties such as powder cohesiveness, triboelectric charge level, charging rate, and the charging rate of replenishment toner were evaluated for surface treated toners that had been powder blended over a range of energy intensities. The following effects were observed:For surface treatments that are added to improve powder flow properties, embedment of surface treatment particles increase toner cohesiveness.Embedment of silica particles that are used to increase developer charging rate diminishes this effect.The triboelectric charge level time dependent response of a developer shows that charge level can either increase or decrease as surface treatment particles are embedded in the toner particle during developer agitation. The response was dependent on the relative charge level of the surface treatment particle and the toner particle.
Robert D. Fields, Satya Srinivasan, "Effects of Toner Surface Treatment Powder Blending Parameters on Developer Triboelectric Properties" in Proc. IS&T Int'l Conf. on Digital Printing Technologies (NIP16), 2000, pp 719 - 722, https://doi.org/10.2352/ISSN.2169-4451.2000.16.1.art00075_2