PROCESS FOR PRODUCING SPHERICAL COMPOUND HARDENED MELAMINE RESIN PARTICLES

摘要

A process for producing spherical compound hardened melamine resin particles with excellent water resistance having colloidal silica localized around the surface, whereby the particle diameter can be controlled over a broad range of from the order of submicron to the order of micron. More specifically, the process comprises: the step (a) wherein, in a suspension of colloidal silica having an average particle diameter of 5 to 70 nm in an aqueous medium, a melamine compound is reacted with an aldehyde under basic conditions to thereby form an aqueous solution of primary condensation product of a water-soluble melamine resin; and the step (b) wherein an acid catalyst is added to the aqueous solution obtained in (a) and thus spherical compound hardened melamine resin particles are precipitated; optionally followed by the step (c) wherein the surface of the spherical compound hardened melamine resin particles is coated with inorganic compound particles.