In electrophotography, the choice of polymer as toner binder is primarily limited to polyester or styrene–acrylate type vinyl copolymers. Each type of resin provides several unique advantages over the other. Although, the printer segment market once defined the choice of toner
polymer, it is no longer the case now. Both types of polymers are now being used from low speed to very high-speed printers as toner binders. Similar trends are found in color and monochrome applications as well. An attempt was made to compare both types of toner resins across numerous performance
criteria. Various toner samples were prepared using each type of binders and evaluated for different attributes. It was found that, at low molecular weights, higher Tg and toughness can be more easily achieved with polyesters resins based on bis-phenol A. These low MW resins are especially
desirable in color toners where low melt viscosities are preferred for higher speed fusing and richer color reproduction. Although broad fusing latitude could be obtained with either type of polymer binder, the polyester based toner show better adhesion and fusing quality than vinyl counterparts.
Styrenics, on the other hand, are less expensive and provide improved dispersion of waxes. Some differences in the tribocharging performance of the two resins were observed but comparable charges can be achieved with either resin by proper selection of toner formulation. Many attempts have
been made to reduce existing performance gap between the two polymers by either using a blend approach or by chemical bonding these two dissimilar and incompatible polymers. However, the desired results have been far from satisfactory. With the recently increasing trend in toner manufacturing
towards chemically prepared toners, the choice of polymer has also become an issue. The choice of suitable toner binder is now restricted entirely by the manufacturing technique selected. Depending on the application, a case can be made for each polymer as the best choice for toner application.
Document Type: Research Article
Publication date: January 1, 2006
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