Patent ID: 7495036
Filing Date: 2009-02-24
Classification: A61K,A61Q,C08J

Abstract:
1. A process of making a dry powder formed of primary particles, or aggregates of primary particles, or a polymer wherein the primary particles have a size below 20 μm and the powder can dissolve or swell in water to form a clear gel, the process comprising forming an emulsion of aqueous ethylenically unsaturated cationic monomer in non-aqueous liquid optionally in the presence of an emulsifier, initiating polymerisation and allowing polymerisation to complete, distilling water from the emulsion until the emulsion is substantially dry, the distillation being conducted while maintaining a sufficient amount of non-aqueous liquid in the emulsion to prevent breakage of the emulsion, separating the non-aqueous liquid from the polymer particles by a process comprising washing the substantially dry emulsion, or a slurry or cake of dry polymer particles separated from it, with a volatile organic solvent which is a solvent for the non-aqueous liquid and for the emulsifier (if used) and which does not dissolve or swell the polymer particles and which is substantially miscible with water, separating the washed polymer particles as a cake or slurry of the polymer particles wetted by the solvent, and evaporating the solvent from the cake or slurry and thereby providing the dry powder, wherein the powder is swellable in water to form a gel with optical clarity.