Design and scale up of a mixing process for the manufacture of a novel automotive coating

The study performed is part of a larger project aiming to develop high performance automotive coatings and associated processes to enable large scale manufacture of the new product. This part of the project relates to process development with the objective of establishing the comparative blending performance of two types of impeller, a sawtooth and a pitched blade turbine, at different scales. Comparable blending performance is noted in the turbulent and transitional regimes in tanks up to and including T= 0.30 m. In the large scale of T= 0.58 m diameter tank, mixing times were much longer with the sawtooth impeller. Measured and predicted mixing time values were in agreement for both impellers in T=0.30 m and for the PBT also in T= 0.58 m, but much longer for the sawtooth impeller at large scale. This deviation in the performance at large scale has highlighted the complexity of design and scale up using a sawtooth impeller.