Preparation and Dispersion Performance of Hydrophobic Fumed Silica Aqueous Dispersion

Hydrophobic fumed silica (HFS) is a commonly used rheology additive in waterborne coatings. A series of experiments were conducted on the HFS-dispersing technology in this study. The size and structure of HFS primary particles were observed via transmission electron microscopy (TEM). The measurement results of the TEM were D₅₀ = 13.6 nm and D₉₀ = 19.7 nm, respectively. The particle size and dispersion performance of HFS were tested via dynamic light scattering (DLS). Additionally, the HFS aqueous dispersion was prepared and compounded with waterborne polyacrylic latex and polyurethane resin. The elemental distribution of the coatings was characterized using energy dispersive spectroscopy (EDS). The results show that the HFS in a non-ionic polymer dispersant had the best dispersion performance. The particle size of the HFS in the aqueous dispersion is related to the dispersion conditions. Under optimized conditions, the HFS aqueous dispersion can be prepared with a particle size of D₅₀ = 27.2 nm. The HFS aqueous dispersion has stable storage stability. Even after storage for 47 d, the particle size still did not change significantly.