FACTORS AFFECTING THE PARTICLE SIZE AND SIZE DISTRIBUTION OF POLYUREA MICROCAPSULES BY INTERFACIAL POLYMERIZATION OF POLYISOCYANATES

Abstract

The interfacial polymerization method was used to prepare fragrant microcapsules. The wall material was a polyurea formed by the reaction of triphenyl methane triisocynate (JQ-1) and TDI (2,4-toulene diisocyanate) with amines that were the reaction results of isocyanates with water. During the preparation, An emulsifier (GPE2040), protective colloid (PVA) and catalyst (dibutyltin dilaurate) were used. The influences of the phase ratio (organic/aqueous), core/wall ratio, the amounts of emulsifier and protective colloid and the radio of triphenyl methane triisocyanate (JQ-1)/TDI (2,4-toluene diisocyanate) on particle size and size distribution of the microcapsules prepared were studied. A mechanism of the process of wall forming is suggested i.e. it might be that the isocyanate migrates outwards through the forming microcapsule's wall and reacts there with water to form amines, which in turn react with isocyanate groups nearby, resulting in the formation of polyurea and the polyurea formed accumulates on the wall of surface.