Abstract: The present invention relates to the use of calcium salts for reducing the formaldehyde emission of microcapsule dispersions based on melamine-formaldehyde resins. The invention also relates to a process for the preparation of a dispersion of microcapsules by condensation of partly methylated melamine-formaldehyde resin in water, in which the substantially water-insoluble material forming the capsule core is dispersed, in the presence of an anionic protective colloid, and to the dispersions of microcapsules which are obtained by this process and to the use thereof for the preparation of printing inks and paper coating materials.

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.

Abstract: A process for the preparation of microcapsules by the condensation of melamine-formaldehyde resins and/or the methyl ethers thereof in water, in which the substantially water-insoluble material forming the core of the capsule is dispersed, in the presence of an anionic protective colloid at pH's of from 3 to 6.5 by the formation of the microcapsules at temperatures of from 20° to 50° C. followed by curing of the shell of the capsules at from >50° to 100° C., in which, prior to curing, from 10 to 200 wt % of urea, whose amino groups are optionally linked to an ethylene or propylene bridge, based on the melamine-formaldehyde resin are added, the microcapsules produced by this process and also the use thereof in a pressure-sensitive recording system.

Abstract: The microcapsules containing bleaching agents are obtainable by polymerizing monomer mixtures which comprise5-100% by weight of at least one ethylenically unsaturated carboxylic anhydride (a),0-95% by weight of at least one monoethylenically unsaturated monomer (b) different from the monomers of group (a),0-80% by weight of crosslinking monomers (c) which have at least two nonconjugated monoethylenic double bonds in the molecule, and0-20% by weight of water-soluble monoethylenically unsaturated monomers (d),where the total of components (a) to (d) is 100% by weight. The polymerization takes place in the oil phase of a stable oil-in-water emulsion in the presence of free-radical polymerization initiators, where the temperature of the polymerizing reaction mixture is, where appropriate, increased continuously or periodically during the polymerization. The oil phase contains or consists of the bleaching aid.

Abstract: The stabilizer mixture comprises(a) one or more chroman derivatives of the formula I ##STR1## where R.sup.1 is ##STR2## in which Z is C.sub.7 - to C.sub.30 -alkyl, --CH.sub.2 CH.sub.2 --S--(C.sub.1 - to C.sub.30 -alkyl) or ##STR3## and (b) an inert organic solvent for the chroman derivatives I from the group consisting of aliphatic, cycloaliphatic or aromatic hydrocarbons or halogenated hydrocarbons, silicone oils and vegetable and animal fats,where components (a) and (b) are in a weight ratio of from 99:1 to 1:99.

Abstract: The invention relates to copolymers containinga) 20-90% of 2-acrylamido-2-methylpropanesulfonic acid, sulfoethyl or sulfopropyl (meth) acrylate or vinylsulfonic acid,b) 0-50% of a vinylic acid,c) 0-70% of methyl or ethyl acrylate or methacrylate, C.sub.2 --C.sub.4 -hydroxyalkyl acrylate or N-vinylpyrrolidone andd) 0.1-10% of styrene or C.sub.4 --C.sub.18 -alkyl acrylate or C.sub.4 --C.sub.18 -alkyl methacrylate.The copolymers according to the invention are particularly suitable as protective colloids for microencapsulation.