Process for preparing an aqueous emulsion or dispersion of a partly water-soluble material, and optionally further conversion of the prepared dispersion or emulsion to a polymer dispersion when the partly water-soluble material is a polymerizable monomer

A process for preparing an aqueous emulsion or dispersion of a partly water-soluble material which comprises:

• (a) preparing an emulsion or dispersion of particles comprising:
• (i) polymer and
• (ii) Substance I which is one or more materials having a molecular weight of <5000 and a water solubility of <10.sup.-2 g/l and is substantially absorbed by said polymer and
• (b) adding to said emulsion or dispersion, Substance II which is one or more partly water-soluble materials having a water solubility at least 10 times higher than that of Substance I, whereby Substance II diffuses into the polymer particles containing Substance I at a rate substantially in excess of the rate of departure of Substance I from said polymer particles, the amount of said Substance II diffusing into said particles containing Substance I being at least 20 times that of the original polymer particles used in (a) based on volume, and then causing polymerization to take place if Substance II is a monomer.