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，开展了无粘结剂造粒包衣玉米淀粉微胶囊的工艺研究。然而，由于包衣过程中颗粒的机械强度不足，这项工作不得不勉强停止。因此，通过进行无粘结剂造粒实验，考察了颗粒的性质(粒度分布、机械强度)与成粒率和操作变量之间的关系，以获得基本的结果，作为这一新工艺开发的初步阶段。实验结果总结如下：1.实验装置和条件：造粒实验用的是由丙烯酸树脂制成的二维锥形流态化柱(喷动床式)。柱子厚度为10 mm，锥角为15度。进气口为10 mm见方。列宽是可变的…更适合从150毫米到500毫米。气体分布器采用开口为44 mm的不锈钢网，流态化气体为空气。给粉采用窄切径分别为0.3、0.6和1.0微米的氧化铝颗粒。在不同的操作条件下进行了造粒实验，如粉料加入量、气速、操作时间和柱宽。结果：(1)颗粒呈球形，粒度分布服从对数正态分布。(2)利用柱体干壁区的分级现象，可获得所需的最小粒度颗粒。(3)在保证平稳流态化状态的情况下，无论粉料装药量、气速、床层宽度等操作变量如何，均可得到物性相近的颗粒。(4)对于较大的颗粒(1.0微米颗粒)，易发生沟道堵塞造粒。(5)颗粒的表观抗压强度几乎与操作条件无关，随颗粒尺寸的增大而减小，随料粒尺寸的减小而增大。较少

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