GB723624A - Encapsulating method and apparatus therefor - Google Patents

Abstract

723,624. Moulding capsules. SOC, GENERALE D'ENROBAGE. Oct. 24, 1951 [Nov. 10, 1950; Dec. 6, 1950], No. 24904/51. Class 87 (2) [Also in Group VI]. A process of encapsulating a material comprises the steps of suspending a film of a viscous capsule-forming medium by its peripheral edges and discharging discontinuous portions of said material to be encapsulated onto said film in such a way that it passes unsuspended before impinging on said film. Apparatus comprises a means for discharging the capsule-forming medium as an annular film, said discharge means being adapted to permit said medium to form a transverse film suspended at its periphery by said discharge means, and means for discharging discontinuous portions of the material to be encapsulated onto said film, the last said means being removed from the point where said film is formed to a sufficient distance to permit said discharge material to pass unsuspended before impinging on said film. As shown, an outer conduit 10 is situated concentrically with an inner conduit 11 so as to form an annular passageway 12 through which the encapsulating medium passes to an orifice 13 where a film 14 is formed. The material to be encapsulated passes down an inner conduit 16 which terminates at a sufficient distance above the orifice 13 to permit the said material to fall in desired portions upon the encapsulating film 14. Air pressure sufficient to extend the film 14 to form a pocket without rupture and to assist the discharge of the filled capsule, is applied through the conduit 17. A vessel 19 containing the capsule hardening fluid is situated beneath the annual orifice 13 and is provided with baffles 20 to prevent splashing of the film 14, the filled capsules falling into the bath through openings 22 of the baffles 21. For large scale operation, a closed vessel (not shown) has a lower plate 30, Fig. 7, provided with openings 31 having inwardly converging shoulders 32. An upper plate 33 has openings 34 coaxial with openings 31 but of small cross section through which the material to be encapsulated flows, a lip 34a being provided by counterboring the plate at 35. An intermediate plate 36 provides a passageway 37 for the pressure producing gas, and a passageway 38 for the encapsulating liquid. Tubes 39 having openings 41 through which air pressure is applied to the film 40a, depend from the upper plate 33 and are spaced from openings 31 in the lower plate by peripheral protrusions 42. The capsules are washed free from excess hardening medium by a rinse or spray of water. The encapsulating medium may be an aqueous solution of a water-soluble salt of alginic acid e.g. sodium, potassium, lithium or ammonium salt especially a 2 per cent solution. To produce uniform capsules air in the encapsulating medium is replaced by an inert gas e.g. carbon-di-oxide. Specification 544,507, [Group VI],. is referred to.