The application of coating films is an important step in the manufacture of pharmaceutical tablets. Understanding the phenomena taking place during coating spray application provides important information that can be used to reduce the number of defective tablets and select the optimal conditions for the coating process. In this work, we investigate spray impact and film spreading on a tablet while this passes through the spray-zone in a rotating coating drum. To simulate spray impingement, we developed an one-dimensional (1D) spreading model that is based on the mechanical energy equation. We assumed the spray to be uniform and we divided it into arrays of droplets that impinge successively on the substrate orthogonally to its surface. In the mechanical energy equation that describes the coating spreading, we accounted for the rate of work done on the surface of the liquid coating film by the impinging droplets that leads to volume change (film spreading and thickness increase). The novel model we propose in this work can calculate the coating spreading rate and thickness. We implemented the mathematical model employing the gPROMS Modelbuilder platform. To study the effect of coating properties and process parameters on the film spreading rate and on the final liquid film thickness, we performed variance-based sensitivity analysis. The model predictions are in good agreement with experimental data found in the literature.

包衣膜的应用是制造药物片剂的重要步骤。了解包衣喷涂过程中发生的现象可提供重要信息，可用于减少有缺陷的片剂数量并选择包衣过程的最佳条件。在这项工作中，我们研究了在平板电脑上的喷雾冲击力和薄膜在通过旋转包衣滚筒中的喷雾区时的散布情况。为了模拟喷雾撞击，我们开发了基于机械能方程的一维（1D）扩展模型。我们假设喷雾是均匀的，然后将其分成液滴阵列，这些液滴依次垂直于其表面撞击在基材上。在描述涂层扩展的机械能方程中，我们通过撞击液滴来解释液体涂膜表面完成的工作速率，这些液滴会导致体积变化（膜铺展和厚度增加）。我们在这项工作中提出的新颖模型可以计算涂层的铺展速率和厚度。我们使用gPROMS Modelbuilder平台实现了数学模型。为了研究涂层性能和工艺参数对薄膜铺展速率和最终液体薄膜厚度的影响，我们进行了基于方差的敏感性分析。模型的预测与文献中的实验数据非常吻合。我们使用gPROMS Modelbuilder平台实现了数学模型。为了研究涂层性能和工艺参数对薄膜铺展速率和最终液体薄膜厚度的影响，我们进行了基于方差的敏感性分析。模型的预测与文献中的实验数据非常吻合。我们使用gPROMS Modelbuilder平台实现了数学模型。为了研究涂层性能和工艺参数对薄膜铺展速率和最终液体薄膜厚度的影响，我们进行了基于方差的敏感性分析。模型的预测与文献中的实验数据非常吻合。