Laser diffraction measurements of pigment size distributions of coatings and mill bases: implications of dilution medium and dispersion process parameters

Abstract

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Population Balance Modeling and Mechanistic Analysis of Inorganic Pigment Dispersion in a High-Speed Disk Disperser and a Vertical Bead Mill

“…When using scanning transmission electron microscopy (STEM) to estimate the particle size and shape of the welldispersed particles, the same conclusion was obtained. 28 After dispersion, the majority of the agglomerates for both Cu 2 O and TiO 2 pigments were found to be duplets and triplets. However, due to the images being 2-D and a rather limited number of particles analyzed for each recording, the STEM approach failed to estimate the volume ratio of these aggregates.…”

“…According to the procedure in, 28 three individual samples are taken from the dispersion tank and diluted in the prediluted chamber. From the pre-diluted chamber, a small coating sample size (0.5 mL) was transferred to the measurement cell.…”

“…For validation of model simulations, experimental procedures and PSD data from an earlier work were used. 28 ters were considered. The pigments were dispersed in a laboratory-scale high-speed disk disperser (the rotation speed was set to be either 7000 or 8000 rpm, and the volume of the mill base was controlled to be around 200 mL) and a vertical bead mill (using either 1 or 3 mm diameter glass beads or ceramic beads and with a process rotation speed of 4000 or 5000 rpm).…”

“…However, the entire PSD of pigments plays a role in the performance of coatings, and a more quantitative method is needed for industrial quality control. As shown in earlier work, when using the proper procedure, it is possible with the principle of laser diffraction (more correctly expressed as low-angle laser light scattering) to measure the full PSD of pigments. ,,, …”

“…For validation of model simulations, experimental procedures and PSD data from an earlier work were used . In the four experimental series, acrylic-based mill bases with TiO 2 or Cu 2 O pigments and perturbations in the formulation and dispersion parameters were considered.…”