Low-viscosity, melamine-formaldehyde resin microcapsule dispersions with reduced formaldehyde content

Abstract

Described is a process for preparing a dispersion of microcapsules by condensing a partially methylated melamine-formaldehyde resin having a molar ratio of melamine:formaldehyde:methanol of from 1:3.0:2.0 to 1:6.0:4.0 in water in which the essentially water-insoluble material forming the capsule core is present in dispersion in the presence of an alkali metal salt of a homopolymer or copolymer of 2-acrylamido-2-methylpropanesulfonic acid as protective colloid at a pH of from 3 to 6.5 by preforming the microcapsules at a temperature of from 20 to 50° C. and then curing the capsule wall of the preformed microcapsules at >50 to 100° C., which comprises adding from 5 to 100% by weight of melamine, based on the melamine-formaldehyde resin, in the course of curing. The microcapsule dispersions are formaldehyde-reduced and of low viscosity.

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