Discrete element modeling of the transient heat transfer and toner fusing process in the Xerographic printing of coated papers
In this study, a computer model based on discrete element method is employed to simulate the unsteady state heat transfer from the fuser roll to the toner and coating layer during the Xerography printing of coated papers. The model coating layers consisted of randomly arranged spherical pigment and latex particles with commercially relevant size distributions. Effects of coating characteristics, toner size, multiple toner layers, toner melting energy, toner thermal conductivity, coating layer thermal conductivity, and fuser roll temperature and pressure were investigated. Iso-thermal contours of fusing time were generated to demonstrate the relative importance of different fusing conditions and toner properties. Simulation results showed that temperature variation highly depended on the toner size, toner melting energy and the fuser roll temperature. Moreover, simultaneous coupling of the compressive stress and heat transfer indicated that the pressure exerted by the fuser roll did not significantly affect the rate of heat transfer.
Heat Transfer through Calcium Carbonate-Based Coating Structures: Observation and Model for a Thermal Fusing Process
An analysis of thermal conductivity through porous calcium carbonate-based coating structures is made to assist in many areas of coating and printing, such as toner fusing, heat set offset, paper coating and finishing, including drying and calendering, and to support the recent studies into the potential for dry coating methods. Properties of coatings applied in the dry state have been shown in many respects to be able to match those conventionally produced using water-based formulations. There remains, however, in all these processes a need to understand the various fusing steps, in the case of dry coating for internal cohesion and adhesion of the coating to the paper surface, and the design and operation of the system, and in the case of thermal toner adhesion for the application and spatial control of thermal gradients. A method is developed to measure the thermal conductivity of a coating structure directly, and the coefficient of thermal conductivity is reported for several pigment/binder combinations, including a unique latex coated pigment in which the polymer latex binder is distributed in a thin film over the pigment surface. By modelling the pore structures using a network simulator, it is shown that connectivity in cases of inhomogeneous species distribution, such when both pigments and binders are present, is a necessary but not complete descriptor of thermal conductivity. It is shown that the heat conduction at similar skeletal connectivity is strongly dependent on the distribution of polymeric binder: the more uniform the binder distribution the greater is the thermal conductivity. A heat transfer model is described that can be used to predict the thermal transfer via conduction and, hence, simulate thermal processes including the fusing step.
Studies of Regression in a Transplantable Tumor in Mice *
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