Development of A New Process for Manufacturing Micro-Capsule by Using Binderless Granulation and Coating

以玉米淀粉和乳糖粉为原料，开展了无粘结造粒和包衣的实验研究，研究了玉米淀粉包覆乳糖薄膜微胶囊的制备工艺。然而，由于涂层过程中颗粒的机械强度不足，这项工作不得不被迫停止。因此，通过进行无粘结剂造粒实验来检验颗粒的性质（尺寸分布，机械强度）和产量与操作变量之间的关系，以获得基本发现，作为该新工艺发展的初步阶段。结果总结如下：1。实验设备和条件：用于造粒实验的由丙烯酸树脂制成的二维锥形流化床柱（喷淋床型）。柱的厚度和锥度分别为10mm和15度。进气口为10mm见方。柱宽在150mm到500mm之间变化较大。配气采用开口44 μ m的不锈钢网，流化气采用空气。采用0.3、0.6和1.0 μ m窄切的氧化铝颗粒作为进料粉。在粉料投入量、气速、操作时间、柱宽等不同操作条件下进行了造粒实验。通过筛分来测定颗粒的大小，通过称量每次运行后从塔中排出的颗粒量来计算颗粒的得率。结果：(1)颗粒呈球形，粒径服从对数正态分布；(2)利用柱干舷区的分级现象，可获得所需最小粒径的颗粒。(3)在保证平滑流化状态的情况下，无论粉体装药量、气速、床层宽度等操作变量如何，均可得到物理性质基本相似的颗粒。(4)对于较大的颗粒（1.0 μ m颗粒），易形成通道，成为造粒的阻碍。(5)颗粒的表观抗压强度随颗粒粒度的增大而减小，随进料粒度的减小而增大，与操作条件无关。少

To develop a process for manufacturing micro-capsule of cornstarch covered with thin lactose film, experimental work on binder1ess granulation and coating using cornstarch and lactose powder as feeding materials was started. However this work had to be stopped unwillingly because of insufficient mechanical strength of granules in the coating process. Consequently, the relations between the properties (size distribution, mechanical strength) and yield of granules and operational variables were examined by performing binderless granulation experiments for obtaining fundamental findings as a preliminary stage of the development of this new process. The summary of the results is described as follows.1.Experimental apparatus and conditions : A two dimensional tapered-fluidized bed column (spouted bed type) made of acrylic resin as used for granulation experiments. The thickness and taper angle of the column were 10mm and 15 degrees. The gas inlet was 10mm square. The column wideness was var … More iable from 150mm to 500mm. Stainless steel mesh with opening of 44 mu m was used as gas distributor and air was used as fluidizing gas. Alumina particles with narrow cut of 0.3, 0.6 and 1.0 mu m were used as feeding powder. Granulation experiments were conducted at various operational conditions such as charge amount of powder, gas velocity, operation time and column wideness. Granule size was measured by sieving and yield of granules was obtained by weighing the amount of granules discharged from the column after each run.2.Results : (1) The granules were spherical and their size distribution obeyed log-normal distribution. (2) The granules having a required minimum size could be obtained by utilizing classification phenomena in the freeboard region of the column. (3) When the smooth fluidizing state is ensured, the granules with almost similar physical properties were obtained irrespective of operational variables such as charge amount of powder, gas velocity and bed wideness. (4) For relatively large particLes (1.0 mu m particles), the channeling as an obstruction of granulation is liable to set in. (5) Apparent compressive strength of granules which was almost independent of the operational conditions, decreased with the increase of granule size and increased with the decrease of feed particle size. Less