Patent attributes
An improved process for the preparation of microcapsules consisting essentially of a wall material and a core material in condensing a melamine-formaldehyde precondensate and/or methyl ethers thereof in an aqueous dispersion of a water-insoluble core material and in the presence of an acrylic acid/acrylamide copolymer at acidic pH and at a temperature in the range of from 20° to 100° C., and hardening thereafter the melamine-formaldehyde precondensate to form the walls of the microcapsules at an elevated temperature, wherein the core material is dispersed in the precondensate/copolymer solution without initial partial condensation of the precondensate and copolymer and wherein the hydrophobe point of the precondensate and/or its methyl esters is less than 90° C., as well as microcapsules, paper and pressure-sensitive recording material comprising such microcapsules.
