Necessary requirements for an industrial application of the in situ coating process

Different products of the daily life are coated as e. g. foodstuffs, pharmaceuticals or fertilizers. In those cases, the coating can have different functions. It can be used to improve the appearance or as protection for an active ingredient against environmental influences like humidity. Also, by coating a controlled release of an active ingredient can be realized. In conventional coating technologies the coating is realized as an additional process step after the shaping of the product. The in situ coating overcomes this problem by combining the shaping and the coating of the product in only one process step. Therefor a drop forming (pastillation) process for shaping is used together with a controlled crystallization to achieve a separation between the coated and the coating material. For an industrial use of the in situ coating process a constant product quality is crucial. This means that a constant crystallization procedure for the drops (the later coated pastilles) has to be guaranteed. In this work the application of different nucleation techniques and the role of a controlled initiation of nucleation on the process is discussed. Furthermore, the necessary requirements for an industrial application of the in situ coating process are evaluated by the means of two case studies.