SOME FACTORS AFFECTING THE SIZE OF NYLON-6-10 MICROCAPSULES PREPARED BY INTERFACIAL POLYMERIZATION IN A HIGH-VOLTAGE ELECTRIC-FIELD

The effect of process variables such as nozzle size, flow-rate of disp ersed phase, inter-electrode distance, and presence of an acid accepto r and a thickening agent in the dispersed phase, on the production and size distribution of nylon 6-10 microcapsules prepared by interfacial polymerization in a high-voltage electric field was studied. Factors which increased the intensity of the electrostatic forces acting upon the droplets formed, such as increasing nozzle diameter at constant aq ueous phase flow-rate and decreasing inter-electrode distance, were fo und to decrease the capsule size while those which enhanced the availa bility of the aqueous phase monomer for the polymerization reaction, s uch as the addition of an acid acceptor and a thickening agent, result ed in an increase in the average size of the capsules obtained. Free f lowing capsules and a reduction in the rate of diacid chloride hydroly sis during the process were also obtained with increasing concentratio n of the thickening agent in the aqueous phase.