Online particle size measurement of pigment dispersions during the milling process using dynamic light scattering

 
Particle size is one of the key aspects influencing the performance of a suspension, such as the rheological behavior, transparency, stability and color strength. There is a wide range of characterization methods, which are normally used in a laboratory and therefore away from the processing facilities, due to their temperature and vibration sensitivity, long measurement time and precise sample preparation. In order to improve productivity, to implement autonomous process control and/or to enhance the quality control of the product, there is a growing need on directly employing such measurement techniques in the processing environment. The authors will present a new in-situ measurement technique based on dynamic light scattering. The potential and limitations of this method as well as the respective measurable particle size range will be discussed. Exemplary results with this innovative in-situ method will also be presented for the dispersion of a pigment suspension processed in a beads mill.