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Abstract

Process for preparing aqueous dispersions of a somewhat water-soluble low-molecular organic material, in which swellable particles prepared in a first step are swelled with the organic material in the second step. When the organic material is a polymerizable monomer the dispersion prepared is converted to a polymer dispersion. In the first step swellable oligomer or oligomer-polymer particles are prepared by (a) dispersing an aqueous mixture containing an oil-soluble initiator or a solution of an oil soluble initiator in an organic solvent, and then swelling the dispersed initiator-containing droplets with monomer and effecting polymerization, or (b) swelling polymer particles in aqueous dispersion with vinyl monomer and an oil-soluble initiator and effecting polymerization, the ratio between initiator and monomer used being so high that in the polymerization an oligomer having a degree of polymerization of 5-200 is formed. In the second step, optionally after dilution with water and addition of emulsifier, the organic material is added which has a solubility in water of >10, preferably >100 times higher than that of the oligomer and which diffuses through the aqueous phase and swells the oligomer or oligomer-polymer particles in a ratio by volume of >20:1. When the organic material is a polymerizable monomer, initiator is also added in the second step, and polymerization is effected.

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