Abstract: A process is described for making sterically stabilized non-aqueous dispersions of composite polymer microparticles, in which (1) monomers including at least one crosslinking monomer are polymerized in an aqueous medium at a temperature at least 10.degree. higher than the glass transition temperature of the polymer to be formed, in the presence of a block or graft copolymer stabilizing agent, under conditions such that there is at no time present a separate monomer phase, (2) further monomers, not including any crosslinking monomer, are polymerized in the dispersion thus obtained, the presence of a separate monomer phase again being avoided, and (3) the microparticles are transferred from the resulting dispersion into a non-aqueous medium which is a solvent for the non-crosslinked polymer generated in (2). The microparticles are of value for incorporation into coating compositions the main film-forming constituent of which is compatible with the non-crosslinked component of the particles.

Abstract: A crosslinkable coating composition is described which is miscible in all proportions with water and consists of crosslinked water-insoluble polymer microparticles sterically stabilised in dispersion in a liquid blend of a water-soluble crosslinking agent and a water-soluble, non-volatile substance of molecular weight less than 1000 which can take part in the crosslinking reaction but does not dissolve or swell the polymer, the amounts of the crosslinking agent and of the water-soluble non-volatile substance being up to 30% and 40% respectively of the total weight of film-forming material.

Abstract: A process is described for making sterically stabilized non-aqueous dispersions of polymer microparticles, in which (1) monomers including at least one crosslinking monomer are polymerized in an aqueous medium at a temperature at least 10.degree. higher than the glass transition temperature of the polymer to be formed, in the presence of a block or graft copolymer stabilizing agent containing in the molecule, as the component solvated by the aqueous medium, a polymer chain derived from a polyethylene glycol of molecular weight at least 1000, under conditions such that there is at no time present a separate monomer phase and (2) the microparticles thus obtained are transferred into a non-aqueous medium which is capable of dissolving the polyethylene glycol in question, when the latter is in the non-hydrated state, to the extent of at least 10% by weight at room temperature.

Abstract: A process is described for making sterically stabilized non-aqueous dispersions of composite polymer microparticles, in which (1) monomers including at least one crosslinking monomer are polymerized in an aqueous medium at a temperature at least 10.degree. higher than the glass transition temperature of the polymer to be formed, in the presence of a block or graft copolymer stabilizing agent, under conditions such that there is at no time present a separate monomer phase, (2) further monomers, not including any crosslinking monomer, are polymerized in the dispersion thus obtained, the presence of a separate monomer phase again being avoided, and (3) the microparticles are transferred from the resulting dispersion into a non-aqueous medium which is a solvent for the non-crosslinked polymer generated in (2). The microparticles are of value for incorporation into coating compositions the main film-forming constituent of which is compatible with the non-crosslinked component of the particles.