Microcapsules of low-formaldehyde melamine/formaldehyde resins
AssigneeBASF SE
InventorsGabriele Frank, Ralf Biastoch, Matthias Kummer
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Abstract
Microcapsules are prepared by polycondensation of a melamine/formaldehyde resin mixture in water, in which essentially water-insoluble material forming the capsule core is dispersed, in the presence of an anionic protective colloid, by a process wherein the melamine/formaldehyde resin mixture is composed of: a) an aqueous solution of a condensate of a1) 1 mol of melamine, a2) from 2 to 5 mol of formaldehyde and a3) from 0 to 0.5 mol of a melamine derivative which can undergo an addition or condensation reaction with formaldehyde and a4) from 1 to 5 mol of a C1-C3-alkanol and b) from 0.01 to 1 mol of a water-soluble primary, secondary or tertiary amine or ammonia.
Claims7
A process for the preparation of microcapsules by polycondensation of a melamine/formaldehyde resin mixture in water, in which the material, which is a water-insoluble or essentially undissolved gas, solid or liquid, forming the capsule core is dispersed, in the presence of an anionic protective colloid, wherein the melamine/formaldehyde resin mixture is composed of:
- a) an aqueous solution of a condensate which is composed of
- a1) 1 mol. of melamine,
- a2) from 2 to 5 mol. of formaldehyde,
- a3) from 0 to 0.5 mol. of a melamine derivative which can undergo an addition or condensation reaction with formaldehyde, and
- a4) from 1 to 5 mol. of a C1-C3-alkanol, and
- b) from 0.01 to 1 mol. of a water-soluble primary, secondary or tertiary amine or ammonia.
A process for the preparation of microcapsules by polycondensation of a melamine/formaldehyde resin mixture, which forms the shell of the microcapsules, in water, in which the material, which is a water-insoluble or essentially undissolved gas, solid or liquid, forming the capsule core is dispersed, in the presence of an anionic protective colloid and from 10 to 200% by weight, based on the amount of melamine/formaldehyde resin, of urea, thereby forming microcapsules, wherein the melamine/formaldehyde resin mixture is composed of:
- a) an aqueous solution of a condensate which is composed of
- a1) 1 mol. of melamine,
- a2) from 2 to 5 mol. of formaldehyde,
- a3) from 0 to 0.5 mol. of a melamine derivative which can undergo an addition or condensation reaction with formaldehyde, and
- a4) from 1 to 5 mol. of a C1-C3-alkanol, and
- b) from 0.01 to 1 mol. of a water-soluble primary, secondary or tertiary amine or ammonia;
- and
- curing the shell of the microcapsules at a temperature above 50° C.
Dependencies are inferred from the claim text.