Investigation of Ultra Faster Melting Process of Very Fine High-Polymer Particle.

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In order to improve the print speed of Laser Beam Printer with flash heating, the clarification of phenomena in the melting process of a high polymer particle by flash heating has become very important in recent years. But, almost no theoretical and phenomenological explanations are given about this melting mechanism, because there are the rheological, phase change and the heat transfer problems in this melting process; that is, the temperature of a particle becomes over the melting point, the phase change from solid to liquid partially happen. The natural convection will proceed inside the particle in step with the liquefied. Finally, deformation of the polymer particle will be occurred by fluidity of fusing polymer and power balance between gravity and surface tension onto the material on which the polymer particle is put.From this viewpoint, the present study as the first stage was designed to clarify the external deformation process of a high polymer particle under the condition of … More continuous radiant heating. Furthermore, in order to clarify a melting process inside the polymer particle, the method of measuring the moving of the interface between solid and liquid was investigated.The heating source is used a xenon lamp ( max. 150W ) which can be controlled the power and the exposure time. The beam is converged by a reflector to in 5mm diameter with flat distribution. The polymer particle used in the present study is one kind of acrylic polymer and its shape is spherical. The diameter of particles are 0.15-0.5mm which are 30-100 times. as large as real toner particles. The melting process is observed by a micro-scope and a CCD camera, and the continuous pictures are stored by video. The recorded pictures are digitalized to pixels ( 512x512 ) and light degrees ( 256 ) by the image board and transfer on memory of microcomputer for analysis.The focused laser beam is used in the measurement for moving of inter-face and the light intensity of laser beam penetrated the particle is measured by a semi-conductor transducer, and digitized by A-D transducer board to transfer to micro-computer for analysis.The results show that the external deformation pattern of a polymer particle with time is apparently similar regardless of the size of particle and radiant heating power. But, the deformation process is not monotonous with time and shows the singular point corresponding to progress of melting (that is, interface between solid and liquid). The method of measuring for moving of the interface by using laser beam was proved effective. The results are agreed with one of simulation qualitatively. Less