Core/skin type capsules and preparation method

• Main Authors: PRIGENT, FANNY, SIMMONET, JEAN-THIERRY, BIATRY, BRUNO
• Format: Patent
• Language: English; French; German
• Published: 03.11.2010
• Subjects: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOIDCHEMISTRY; HUMAN NECESSITIES; HYGIENE; MEDICAL OR VETERINARY SCIENCE; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; PREPARATIONS FOR MEDICAL, DENTAL, OR TOILET PURPOSES; THEIR RELEVANT APPARATUS; TRANSPORTING

Preparation of a suspension of core/shell type capsule comprises: (a) preparing a heterogeneous mixture, at room temperature, comprising an oil phase and water- and oil-immiscible polymers; (b) homogenizing the oil phase and polymers by heating at a homogenization temperature (T h); (c) dispersing, at T h, the homogeneous mixture in an aqueous phase to obtain a direct pre-emulsion; (d) subjecting the pre-emulsion to a set of shearing forces; (e) cooling the emulsion at a temperature favorable for the coacervation of the polymers; and (f) cooling the obtained suspension. Preparation of a suspension of core/shell type capsule comprises: (a) preparing a heterogeneous mixture, at room temperature, comprising an oil phase and water- and oil-immiscible polymers, where at least one polymer is an oligomer having a molecular weight of less than 10000 and a hydroxyl index of >= 10 mg potassium hydroxide/g; (b) homogenizing the oil phase and polymers of the mixture obtained from step (a), by heating at a homogenization temperature (T h), which is less than 100[deg] C, and the mixture has a viscosity = 17 mPa.s -> 1>at T h; (c) dispersing, at T h, the homogeneous mixture obtained from step (b) in an aqueous phase to obtain a direct pre-emulsion, where the oil phase of the pre-emulsion comprises the polymers; (d) subjecting the pre-emulsion to a set of shearing forces suitable to reduce the particle diameter of the dispersed mixture to an average size = 50 mu m; (e) cooling the emulsion obtained from step (d) at a temperature (T c) favorable for the coacervation of the polymers and coating the oil drops by the coacervates; and (f) cooling the suspension obtained from step (e) at a temperature (T p) favorable for the formation of capsules by precipitation and/or crystallization of coacervates, where the oil phase is favorable for the formation of a homogeneous mixture with the polymers at T h, and for the manifestation of the phenomenon of polymer coacervation at T c. Independent claims are included for capsules and aqueous suspension obtained by the method.