Method for coating with dispersions of active ingredients coated in a polymer layer

A process of forming a coating based on at least one active ingredient at a surface of a substrate, said process comprising:

• (1) obtaining an aqueous dispersion of nanoparticles comprising a core consisting of one or more active ingredient(s), the core is directly coated with an outer layer formed of one or more hydrophilic polymer(s), said active ingredient(s) and hydrophilic polymer(s) being combined in an active ingredient(s)/hydrophilic polymer(s) ratio by weight varying from 0.2 to 0.4;
• (2) bringing said surface of said substrate into contact with said aqueous dispersion;
• and
• (3) exposing said substrate obtained on conclusion of (2) to conditions propitious to the formation, at the surface of said substrate, of a polymeric film formed of said nanoparticles;
• wherein said one or more active ingredient(s) is (are) chosen from organic UV-absorbing compounds, inorganic UV screening agents and fluorescent agents,
• wherein said nanoparticles of (1) are prepared according to a process comprising:
• obtaining an organic phase comprising said one or more active ingredient(s) in a solute state;
• obtaining an aqueous phase comprising the one or more hydrophilic polymer(s);
• adding the organic phase to the aqueous phase under conditions propitious to the formation of an emulsion, wherein the organic phase is dispersed in the aqueous phase, and wherein the emulsion includes at least one surfactant capable of stabilizing the emulsion;
• carrying out a thermal quenching of the emulsion thus obtained in order to form said nanoparticles;
• and
• isolating said nanoparticles.