Dispersion of microcapsules with low formaldehyde content from melamine-formaldehyde resins

摘要

Microcapsules are prepared by addition of urea to a melamine-formaldehyde dispersion prior to hardening. Microcapsules (I) are produced by condensation of melamine-formaldehyde resins and/or their methyl ethers in water, in which the water insoluble capsule forming material is dispersed, in the presence of an anionic protective colloid at pH 3-6.5 and 20-50 degrees C followed by hardening of the capsule wall at 50-100 degrees C. Prior to the hardening 10-200 wt.% urea, (w.r.t. melamine formaldehyde resin) optionally bound with an ethylene or propylene bridges is added. An Independent claim is included for a pressure sensitive recording system that contains the microcapsules (I).