Aqueous dispersions of at least one biodegradable polymer

A process for preparing an aqueous dispersion of at least one biodegradable polymer comprising an organic phase dispersed in a dispersing aqueous phase comprising a stabilizer and free of volatile organic compounds, comprising:

• at least one viscosity-reducing agent with a solubility parameter of between 15 and 28 (J.cm−3)0.5, and a hydrogen bonding parameter δH of between 3.5 and 15 (J.cm−3)0.5,
• at least one biodegradable polymer in a polymer/viscosity-reducing agent weight ratio of from 99.8/0.2 to 60/40, wherein the biodegradable polymer is polylactic acid, said process comprising the steps of:
• 1) preparing the organic phase to be dispersed by melting a blend of polylactic acid and of viscosity-reducing agent, at a temperature above the glass transition temperature of polylactic acid so as to obtain a homogeneous melt, the weight ratio between the polylactic acid and the viscosity-reducing agent being between 99.8/0.2 and 60/40;
• 2) totally dissolving in the dispersing aqueous phase no more than 5% by weight of a stabilizer selected from the group consisting of polyols, oligosaccharides and polysaccharides derived from celluloses, starches and natural and fermenting gums, in native form or modified form, peptides and polypeptides, and optionally modified polyvinyl alcohols;
• 3) simultaneously and continuously introducing the dispersing aqueous phase and the dispersed organic phase thus obtained into a blender of an emulsifying unit, the rates of introduction of the two phases having been adjusted beforehand such that the dispersed organic phase represents at least 80% by weight of the dry matter of the said aqueous dispersions;
• and
• 4) recovering the aqueous dispersion thus obtained.