Continuous Production of Melamine-Formaldehyde Microcapsules Using a Mesostructured Reactor

Abstract

A mesostructured NETmix reactor was adapted to develop a continuous process to produce microcapsules, focusing on the steps commonly used in batch formulation: the emulsion and cure. Microcapsules were formed through a polycondensation process by coating Miglyol, a skin-hydrating emollient, with melamine-formaldehyde, which is a resistant shell material with surface smoothness. Different recirculation times were tested for the cure step. Microcapsules show a spherical shape and smooth membrane. Efficiencies of encapsulation of 75%, core contents of 70%, and diameters around 20 μm, ideal range for textile impregnation, were obtained. Scanning electron microscopy shows the integrity of microcapsules on textiles after impregnation and their flexible behavior. The thermogravimetric analysis confirmed the thermal stability of microcapsules up to 210°C. With the NETmix reactor, it is possible to reduce the cure time of traditional batch formulation in 80%, producing microcapsules with similar characteristics in a continuous process.

Continuous production of hydroxyapatite Pickering emulsions using a mesostructured reactor

“…In this respect, Muruganandam, Kunal and Melwyn [34] showed that when a O/W emulsion is prepared in an SMX static mixer the Sauter mean diameter of the oil droplets decreases from 8 μm to 4 μm as the Reynolds number increases. Furthermore, in cellulose acetate microcapsules produced by NETmix reactor, a size reduction was also observed as the Re increases, namely when Re increases from 200 to 500, the average diameter decreased from 30 to 5 μm [29]. The findings reported by these authors are in agreement with the ones obtained in this work.…”

“…Examples include the production of nanocrystalline hydroxyapatite [23], this process already at industrial level [24], metal-organic frameworks [25], magnetic iron oxide nanoparticles [26], and calcium carbonate nanoparticles [27]. Furthermore, this technology has also been employed for the continuous production of nano-hydroxyapatite (n-HAp)/chitosan aqueous dispersions [28] and microencapsulated systems [29].…”

Study of Melamine-Formaldehyde/Phase Change Material Microcapsules for the Preparation of Polymer Films by Extrusion

“…Among them, melamine-formaldehyde (MF) has been selected for this research. MF has already been used for the encapsulation of additives such as oils [ 11 ], perfumes [ 12 , 13 ] or phase change materials (PCMs) [ 14 , 15 ] due several advantages (i.e., low price, easy-to-control preparation, high compatibility and good thermal stability). As encapsulating agents, different PCMs have already been incorporated into MF microcapsules.…”

Mixing in the NETmix Reactor

“…In 2017, a NETmix device coupled to heat exchangers was developed for the continuous production of CO 2 hydrates (Costa et al, 2017;Lopes et al, 2018;Lopes et al, 2019). The NETmix reactor has also been used for microencapsulation (Moreira et al, 2020) and Pickering emulsions (Ribeiro et al, 2021).…”