Drop penetration time in heterogeneous powder beds
Drop penetration time in heterogeneous powder beds
复制标题
液滴在异质粉末床中的渗透时间
DOI：
10.1016/j.ces.2009.08.038
复制
发表时间：
2009
影响因子：
4.7
通讯作者：
K. Hapgood
中科院分区：
文献类型：
--
作者：
Thanh;W. Shen;K. Hapgood
湿法制粒是一种通过细颗粒的聚结产生增大的颗粒或“颗粒”的技术，其目的是改善粉末特性。高剪切造粒机通常用于进行造粒过程，其中通过机械方式在容器中搅拌粉末团，同时将液体从上方喷射到粉末床表面上。当粘合剂液滴撞击粉末表面时，液滴进入粉末的液滴渗透时间对于粘合剂均匀分散以及从成核图中预测颗粒核的形成非常重要，这取决于无量纲喷雾通量。先前对液滴渗透时间的研究是在主要是亲水性的粉末床上进行的。虽然这很好地预测了造粒中的成核行为，但它并不能反映在不含表面活性剂的配方中使用疏水性药物的情况。本文旨在研究粉末床疏水性对液滴渗透时间的影响。使用注射器和小粉末床对不同比例的水杨酸和乳糖粉末进行单滴成核实验，以研究滴渗透的动力学。正如预期的那样，随着粉末混合物中疏水性组分比例的增加，液滴渗透时间增加。然而，对于低载药量，观察到较长的液滴渗透时间，这表明疏水性强烈影响液滴渗透时间。粉末混合物的润湿性也对颗粒性质有显着影响，其中粉末混合物的疏水性与颗粒强度成正比，与颗粒尺寸成反比。这些发现对于造粒工艺的设计具有重要意义，其中建议使用最小喷雾通量或有效机械力的条件来生产更均匀的造粒批次。
Wet granulation is a technique in which enlarged particles or ‘granules’ are produced from the coalescence of fine particles, with the intention of improving the powder properties. High shear granulators are often used to carry out the granulation process where the powder mass is agitated in a vessel by mechanical means while liquid is sprayed from above onto the powder bed surface. When the binder droplets impact the powder surface, the drop penetration time of the droplet into the powder is important for uniform binder dispersion and the prediction of the formation of granule nuclei from the nucleation map, which depends on the dimensionless spray flux. Previous studies on the drop penetration time were carried out on predominantly hydrophilic powder beds. Although this gives a good prediction of the nucleation behaviour in granulation, it does not reflect the condition where hydrophobic drugs are used in the formulation without surfactants. This paper aims to look at the effects of powder bed hydrophobicity on the drop penetration time. Single drop nucleation experiments using a syringe and a small powder bed were carried out on varying ratios of salicylic acid and lactose powders to study the kinetic of drop penetration. As expected, the drop penetration time increased as the proportion of hydrophobic component increased in the powder mixture. However, long drop penetration times were observed for low degrees of drug loading, showing that hydrophobicity strongly influences the drop penetration time. The wettability of the powder mixture also has a pronounced affect on the granule properties in which the hydrophobicity of the powder mixture is proportional to the granule strength and inversely proportional to the granule size. These findings have important implications in terms of the design of the granulation process where conditions of minimum spray flux or efficient mechanical forces are recommended to produce a more uniform granulation batch.