Continuous process for producing aqueous dispersions of microcapsules with melamine-formaldehyde condensation product walls

摘要

1. A continuous process for preparing microcapsules having melamine-formaldehyde condensate capsule walls in aqueous dispersion starting from appropriate water-soluble melamine-formaldehyde precondensates in the presence of water-soluble high polymers containing strongly acid groups, which comprises either 1) continuously mixing the water-soluble precondensate, the hydrophobic material to be encapsulated and the aqueous solution of the high polymer containing strongly acid groups, 2) further condensing the water-soluble precondensate in this mixture at pH 3.0-6.5 until the solution starts to become cloudy, 3) continuously dispersing the hydrophobic material in the aqueous dispersion formed, the fine droplets of the hydrophobic material being enveloped by the water-insoluble condensate resulting from the precondensate, or 1a) continuously mixing the water-soluble precondensate and the aqueous solution of the high polymer containing strongly acid groups, 2a) further condensing the water-soluble precondensate in the mixture at pH 3.0-6.5 until the solution starts to become cloudy, then 3a) continuously dispersing the hydrophobic material in the aqueous dispersion formed, the fine droplets of the hydrophobic material being enveloped by the water-insoluble condensate resulting from the precondensate, and then 4) condensing the wall material of the resulting microcapsules to completion.