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The article presents information on a study which examined the surface properties of talc particles modified by dry coating with hydrophobic silica properties. Variables studied included the concentration of silica properties and the dry coating processing time. It describes the talc powders and their characterization. The quantification of dispersion kinetics is detailed. A discussion on the findings of the study including surface morphology and wettability measurements is detailed.

Dry particle coating is used to modify surface properties and monitor the end use properties of powders. These processes are mainly running in batch mode. In certain cases, continuous processes may present interest for specific applications (limitation of investments, stability, versatility…). In this study, the feasibility of dry coating particles by an innovative way derived from the well-known extrusion process was investigated. Adhesion between host and guest particles is induced by mechanical shear stress during processing. A preliminary parametric study on microcrystalline cellulose particles as host particles was carried out in order to determine the operating condition range. Then, coating was successfully performed using talc and a microcrystalline cellulose system, which demonstrates the feasibility of this novel process and led to different morphologies according to the operating conditions. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study is to get a better understanding of dry powder coating process using experiments and numerical methods. Materials chosen as host particles are SUGLETS® (granules mainly consisting of sugar) and as invited particles, magnesium stearate (MgSt). These two materials are introduced into a high shear mixer (Cyclomix). Operations were performed at various mixing time and rotation speed of the Cyclomix. The surface morphology analysis has confirmed that Suglet particles are coated with MgSt. The product properties such as flowability, wettability and particle size distributions were also characterized. The particle motion in the Cyclomix has been simulated by using Discrete Element Method (DEM). Both number of collisions and the collision force frequency are calculated. The simulation shows an increase of the collision number with the rotational speeds. This result indicates that choosing higher rotation speeds should be better for the dry coating process as long as the particles are not broken down. [Copyright &y& Elsevier]