Process Intensification in Particle Technology: Production of Powder Coatings by Nonisothermal Flow-Induced Phase Inversion

Résumé fourni par la source

A novel intensive granulation process for the production of powder coatings is described. The method is based on nonisothermal flow-induced phase inversion (FIPI) phenomenon. A powder coating composition in melt state is transformed to coating particles in a purpose-built granulator that operates in a rotor−stator configuration in which rotor−stator elements have cavities to achieve mixing, pumping, particulate conveying, heat transfer, and crumbling (phase inversion) which takes place at a certain distance (radius) from the center of the disk. The rotor disk is sandwiched between two stator disks. Heat transfer is further improved and melt quenching under deformation is achieved by injecting water or carbon dioxide into the melt while a temperature gradient is maintained across the upper rotor and stator. Injection of fluids reduced the average particle size of the product considerably and also intensified the granulation process through crumbling in a small volume when the coating melt is transformed to particles. The product was characterized by particle size analysis. Methods to control the crumbling radius and average particle size well-below the rotor−stator gap are discussed. The influence of fluid (water or carbon dioxide) injection on the granulation mechanism and the extension of the method to cylindrical rotor−stator system are also discussed.

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