Treated fine particles of metal oxides such as silica, titania, and alumina are commonly used in toner formulations to help to achieve the necessary level of toner free flow and trboelectrostatic charging. In most cases such particles are treated with hydrophobicity imparting agents such as alkylsilanes or silicone oils and their charging characteristics reflect the acidity of the base oxide and quality of the hydrophobic treatment. So far little has been reported on the effect of different chemical functional groups on charging characteristics of treated metal oxides.This paper describes the treatment and characterization of fine particles of aforementioned oxides with two types of functional silanes containing nitro groups and fluorine atoms. Results of triboelectrostatic charge measurements demonstrate that both treatments significantly enhance negative charge and, in certain cases, greatly reduce tribocharge humidity sensitivity. Observed charge enhancement parallels the amount of functional silane present on the surface. Possible reasons for such behavior are discussed from the point of view of ion-transfer model of contact electrification and in conjunction with the available characterization data.Using external additives modified with nitro and fluorine containing functional groups may allow formulators to reduce the number of formulation components and provide extra flexibility to achieve the target performance.
Jinsong Liu, Hairuo Tu, Amar Pawar, Dmitry Fomitchev, Joachim K. Floess, "External Additives for Toners: Treatment with Functional Silanes for Active Triboelectrostatic Charge Control" in Proc. IS&T Int'l Conf. on Digital Printing Technologies and Digital Fabrication (NIP25), 2009, pp 23 - 26, https://doi.org/10.2352/ISSN.2169-4451.2009.25.1.art00010_1