Precise deposition of complex particles for structured functional products

在制药工业中，涂料在制造和产品开发中占有非常重要的地位。固体剂型如片剂、丸剂、颗粒剂等通常被包衣，以控制药物在体内的释放，并且还防止外部因素如水分或磨损。这通常通过用细粉末进行干燥涂覆来实现，因为这提供了减少的环境问题（没有挥发性有机溶剂排放）和更低的能量消耗（不需要随后的干燥或蒸发操作）。然而，干式涂覆工艺在所用的涂覆粉末和能量输入方面是浪费的，因为当涂覆均匀性不满足要求时，整个批次被丢弃。为了减轻这一点，通常使用过量的涂层粉末，同时输入过量的能量以确保所有固体都被充分涂覆。我们的目标是解决这些问题，通过确定一个给定的组合的基板和粉末涂料：（i）如何涂层的单一粉末层的颗粒性能的影响？(ii)如何操作混料机以在整个批次中提供均匀的涂层？(iii)确保产品涂层均匀的最小能量输入是多少？在这项研究中，我们将确定涂层是如何实现的基础上，颗粒水平，通过控制和操纵颗粒的物理（尺寸，形状）和表面（粗糙度，界面能）属性的分布和表征所得的涂层质量。涂料粉末通常极细且具有内聚性，因此易于聚集形成大的团簇。工业粉末涂料要求这些涂料粉末团聚体被一致地分解成单个颗粒并精确地输送到主体。我们将确定如何定制该过程，以增强系统的能力，从而实现任何粉末的这一目标。通过确定粉末涂料的基本原理以及材料特性和工艺参数的影响，我们将创建干粉涂料的状态图，这将使行业能够调整涂料操作，以最大限度地减少粉末和能源的使用。

In the pharmaceutical industry, coatings have a very important place in manufacturing and product development. Solid dosage forms like tablets, pellets, granules etc. are typically coated in order to control the drug release within the body, and also to protect against external factors like moisture or attrition. This is often achieved through dry coating with fine powders, since this provides reduced environmental concerns (no volatile organic solvents emitted) and lower energy consumption (no subsequent drying or evaporation operations required). However, the dry coating process is wasteful in terms of coating powder used and energy input, since when the coating uniformity does not meet the requirement, the entire batch is disposed of. To mitigate this, an excess of coating powder is often used, with excessive energy input to ensure all solids are sufficiently coated. We aim to address these problems by determining for a given combination of substrates and powder coatings: (i) How is coating of a single powder layer influenced by particle properties? (ii) How should a mixer operate to provide uniform coating across the entire batch? (iii) What is the minimum energy input to ensure uniform product coating?In this research we will determine how coating is achieved on the fundamental, particle level, by controlling and manipulating the distribution of particle physical (size, shape) and surface (roughness, interface energy) properties and characterising the resulting coating quality. Coating powders are typically extremely fine and cohesive, and hence are prone to agglomerating to form large clusters. Industrial powder coating requires these coating powder agglomerates to be consistently broken down to single particles and precisely delivered to the host. We will establish how the process can be tailored to enhance the ability of the system to achieve this for any powder. By determining the underlying principles of powder coating, and the influences of material properties and process parameters, we will create a regime map for dry powder coating, which will enable industry to tune coating operations to minimise powder and energy use.