Plastic and nonmetallic article shaping or treating: processes – Encapsulating normally liquid material – Liquid encapsulation utilizing an emulsion or dispersion to...
Patent
1995-02-21
1997-09-30
Nutter, Nathan M.
Plastic and nonmetallic article shaping or treating: processes
Encapsulating normally liquid material
Liquid encapsulation utilizing an emulsion or dispersion to...
264 43, 264 47, 4272133, 42721331, 42721332, 42721333, 42721334, 42721335, B01J 1302
Patent
active
056723016
DESCRIPTION:
BRIEF SUMMARY
The present invention relates essentially to a process for the manufacture of microparticles in emulsion by modification of the chemical composition of the disperse phase after emulsification. Advantageously, these microparticles are manufactured by a chemical or physicochemical reaction within the disperse phase of an emulsion of a substance or mixture of substances by modification of the chemical composition of the disperse phase after emulsification, said reaction being caused by the incorporation of a chemical which is essentially insoluble in the dispersing liquid.
The formation of microparticles by a chemical reaction is known for example from the documents FR-A-2 444 497 Mars, FR-A-2 527 438 CNRS or else 89 01221 BIOETICA, which describe the preparation of microcapsules by the interfacial crosslinking of an aqueous solution of a protein or a protein/polysaccharide mixture within a hydrophobic phase using a difunctional agent such as an acid dichloride.
It is also known to manufacture microparticles from solutions of polymers by physicochemical modifications, but these processes are so-called simple or complex coacervation processes (for example the document EP 0 273 823 A1 MERO ROUSSELOT SATIA), according to whether one or two types of polymers are involved. In said document, the coacervation reaction takes place in the continuous phase, resulting in the formation of a membrane which deposits on the droplets of the dispersed hydrophobic liquid or on the particles of the dispersed solid. The process described in said document is furthermore limited to the encapsulation of a hydrophobic liquid or a solid, the encapsulation of an aqueous phase being impossible.
The document U.S. Pat. No. 4,217,370 RAWLINGS describes a process for the trapping of lipidic microdroplets dispersed in a continuous phase based on a protein substance, which is precipitated by modification of the pH. This process thus consists in trapping droplets in a rigidified matrix by precipitation of the continuous phase.
The document U.S. Pat. No. 4,187,194 WELLMAN describes a process for encapsulation by solvent evaporation.
The document U.S. Pat. No. 4,497,593 SIMKIN relates to a conventional interfacial crosslinking process in which no chemical modification is carried out within the disperse phase.
The present invention makes it possible to manufacture microparticles by a different method from the conventional interfacial crosslinking or simple and complex coacervation methods.
The object of the present invention is to manufacture microparticles, in particular microcapsules, by an extremely simple and inexpensive manufacturing process which has a good reproducibility and hence a good reliability, which makes it possible to adjust the size of the particles obtained within a wide range of values, and which, in particular, affords the possibility of avoiding the use of difunctional crosslinking agents whose residual presence or whose reaction products are liable to jeopardize the biocompatibility of the microparticles or microcapsules formed in this way, thereby making said process very competitive on the industrial scale and preferentially suitable for use in cosmetics or pharmaceuticals or else foodstuffs. The object of the invention is to modify the chemical or physicochemical composition of the disperse phase in order to manufacture microparticles, in particular microcapsules.
The present invention makes it possible to meet these demands simultaneously.
Thus the present invention provides a process for the manufacture of microparticles, in particular microcapsules, characterized in that an essentially homogeneous solution of a substance or mixture of substances in a solvent is first prepared, an emulsion of the solution is produced in a dispersing liquid forming a continuous phase, in which said substance or said mixture is essentially insoluble, and forming a disperse phase, and a chemical or physicochemical reaction is then initiated in the disperse phase by modification of the in situ chemical composition of said substance or sai
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Levy Marie-Christine
Orly Isabelle
Perrier Eric
Coletica
Nutter Nathan M.
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