Precise deposition of complex particles for structured functional products

点击翻译按钮获取中文摘要

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.