The Effect of Toner Blend Conditions on Charge Admix Performance

Abstract

Even for a fixed composition, the charging performance of a toner may show discernable differences between different production batches, and this can be a practical problem for commercial toners that are produced in multiple, worldwide production facilities. This effect may be especially evident in toners based on external additives — variations in the level and distribution of external additives can be a major source of variability in toner performance, since external additives enhance the basic properties of the base toner. As a result, the additive-blending production process can be a significant source of toner performance variability. Furthermore, toner particles experience additional mixing forces during the final packaging operation, during the developer production process (i.e., during the production mixing of toner and carrier particles to create a final developer at a specified toner concentration), and during actual operation in a xerographic development module, and these secondary mixing events can also create changes in toner performance.While external toner additives can affect several key toner properties such as flow, cohesivity, humidity sensitivity, cleanability, etc., the effect of minor variations in blend conditions on performance is often most evident from a toner's charge admix response. This latter property is a measure of the rate at which uncharged, dispensed toner equilibrates with charged toner in a working developer). Since uncharged or poorly-charged toner particles will tend to develop in background, non-image areas, a rapid rate of charge admix is necessary for acceptable xerographic performance.In this present study, charge admix measurements on a single toner design were used to illustrate how changes in toner blend conditions can create a range of charge admix performance, from unacceptably slow to an excellent rapid rate. The major blender topics considered include modes of mixing, along with a range of blend conditions for a single blender.