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

近年来，为了提高利用闪速加热的激光打印机的打印速度，通过闪速加热来澄清高聚合物颗粒的熔融过程中的现象变得非常重要。但是，由于这种熔化过程存在着流变学、相变和传热等问题，即当颗粒温度超过熔点时，发生了部分由固态到液态的相变，因此，对这种熔化机理几乎没有任何理论和唯象的解释。自然对流将在颗粒内部与液化同步进行。最后，聚合物颗粒的变形将通过熔融聚合物的流动性以及聚合物颗粒所处材料的重力和表面张力之间的功率平衡而发生。 ...更多信息 连续辐射供暖此外，为了阐明聚合物颗粒内部的熔融过程，研究了测量固液界面移动的方法。150 W），可以控制功率和曝光时间。光束通过反射镜会聚到直径为5 mm的平面分布。本研究中所用的聚合物粒子是一种丙烯酸类聚合物，其形状为球形。颗粒直径为0.15-0.5mm，为30-100倍。与真实的墨粉颗粒一样大。通过显微镜和CCD摄像机观察熔化过程，并将连续图像通过视频存储。记录的图片被数字化为像素（512 × 512）和光照度（256），并将其传送到微机的存储器中进行分析，用聚焦的激光束测量界面的移动，用半导体传感器测量激光束穿透颗粒的光强，结果表明，聚合物颗粒的外部变形随时间的变化规律与颗粒大小和辐射加热功率无关，但具有明显的相似性。但是，变形过程并不是单调的，而是出现了与熔化过程相对应的奇异点（即固液界面）。实验结果表明，用激光束测量界面位移的方法是有效的。结果与模拟结果定性一致。少

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