Hybrid coacervate capsules
The invention relates to a process for preparing a hybrid coacervate capsule by mixing a first polymer with particles to form particle/polymer complexes; interacting a second polymer with the particle/polymer complexes to form a mixture comprising hybrid complex coacervates which contain particulate inclusions; and adding a core material to the mixture so that the hybrid complex coacervates deposit as a coating layer around the core material. The capsules form another embodiment of the invention.
1. A process for preparing a hybrid coacervate capsule which comprises:
(a) mixing a solution of a first polymer with a first dispersion of at least one type of solid particles at a temperature that is above the gelling temperature of the first polymer, wherein the first polymer adsorbs onto the at least one type of solid particles to produce a second dispersion of particle/polymer complexes;
(b) adding a solution of a second polymer to the second dispersion, wherein the second polymer interacts with the particle/polymer complexes to form hybrid complex coacervates containing homogeneously distributed particulate inclusions, wherein the first polymer is gelatine and the second polymer is gum arabic and wherein the gelatine and gum arabic are present in a weight ratio of 1.5;
(c) adding a core material to the hybrid complex coacervates, wherein the hybrid complex coacervates deposit as a coating layer around the core material active/solution interface to form core/shell capsules each containing the core material encapsulated by a hybrid coacervate shell; and
(d) reducing the temperature of the core/shell capsules to a temperature that is below the gelling temperature of the first polymer;
(e) optionally, cross-linking the hybrid coacervate shells of the capsules, wherein the hybrid coacervate shell has a dry matter composition such that the ratio of the total mass of solid particles to total mass of the first and second polymers is between 0.01 and 1.85.
2. The process according to claim 1 , wherein the solution of the first polymer is mixed with the first dispersion of the at least one type of solid particles under conditions sufficient for the first polymer to adsorb readily onto the at least one type of solid particles.
3. The process according to claim 1 , wherein the pH value and ionic strength of the solution of the first polymer are optimized for the formation of the particle/polymer complexes.
4. The process according to claim 1 , wherein the hybrid coacervate has a suitable viscosity that allows the hybrid coacervate to deposit on the core material to form the capsule shell.
5. The process according to claim 4 , wherein the viscosity of the hybrid coacervate is between 100 mPa*s and 2,500,000 mPa*s at a temperature that is between 30° C. and 70° C., and at shear rates between 0.01/s and 100/s.
6. The process according to claim 1 , wherein the hybrid coacervate contains two or more types of solid particles.
7. The process according to claim 6 , wherein the shell contains two or more different types of solid particles selected from the group consisting of silicon oxides and other metal oxides, silicates, silver nanoparticles, magnesium and aluminum silicates (clays), sheet silicates (mica), diatomite, perlite, vermiculite, crystals of fats, fatty acids or fatty alcohols and mixtures thereof.
8. The process according to claim 1 , wherein the core comprises a solid active ingredient and/or a liquid active ingredient of an oil.
9. The process according to claim 1 , wherein the particles have coverage by the first polymer of at least 0.1 molecules of polymer per square millimeter of particle surface.
10. The process according to claim 1 , wherein the particles have coverage by the first polymer of at least 0.1 molecules of polymer per square millimeter of particle surface.