Charge control capability of trianilino-triphenylmethane (TATPM: a positive type CCA) for a styrene-acryl (St-Ac) model toner is evaluated using two types of two-component developer samples. One of the samples is a mixture of St-Ac model toner TP which has a TATPM coating layer on its surface and a ferrite carrier C, and the other is a mixture of CCA-free St-Ac model toner T and a ferrite carrier CP which has a TATPM coating layer on its surface. The toner charge q/m of the developers having TP-C and T-CP combinations is measured by the blow-off method. Both of toner brown off from the developer of the TP-C combination and that from the developer of the T-CP combination show a positive charge. The positive charge on the toner T from the developer of the T-CP combination, (that is, the toner first brought in contact with and then separated from the carrier) CP having a strongly positive charge, is contrary to expectation. The values of the toner charge q/m for the developers are nearly equal if the amount of TATPM on the TP surface or on the CP surface is identical. The q/m values increase linearly with an increase in the amount of TATPM coated on the two surfaces and reach a saturation value. On the surface of a carrier CS, which was collected after the blowoff measurements of the developer of the TP-C combination, a small amount of TATPM was detected by a calorimetric method.From the above results, it is confirmed that, in the toner charging of the two component developer of the TP-C or T-CP combination, the TATPM particles from the TATPM coating layer of the TP or CP surface served as a positive charge messenger according to the following steps; a) the TATPM layer coated on the TP surface or CP surface is peeled off by a mixing operation, b) the generated TATPM fine particles adhere on the carrier C or carrier CP surface and acquire a positive charge, c) the positively charged TATPM particles adhere to the toner T or toner TP surface to provide positively charged toner particles.
Atsushi Suka, Manabu Takeuchi, Keiki Suganami, Toshihiko Oguchi, "Evaluation of Toner Charging Capability of Trianilinotriphenylmethane (TATPM) Coating Layer on Toner or Carrier Surface" in Proc. IS&T Int'l Conf. on Digital Printing Technologies (NIP22), 2006, pp 165 - 168, https://doi.org/10.2352/ISSN.2169-4451.2006.22.1.art00041_1