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Encapsulating particles with coatings that conform to size and shape of the particles

  • US 6,558,665 B1
  • Filed: 05/18/2000
  • Issued: 05/06/2003
  • Est. Priority Date: 05/18/1999
  • Status: Expired due to Fees
First Claim
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1. A method for encapsulating particles, the method comprising:

  • providing a container having two liquids therein, said liquids having different densities and being substantially immiscible relative to each other and being situated in said container such that an interface exists between the liquids, the liquid of lesser density comprising an upper liquid and the liquid of greater density comprising a lower liquid, the lower liquid comprising a coating liquid and having said particles to be coated entrained therein, the upper liquid having a greater viscosity than the lower liquid;

    inserting a tube having an orifice into the container such that said orifice is positioned in the upper liquid above said interface, said tube being operably connected to a pump for withdrawing liquid from the container;

    activating said pump and establishing a pumping rate sufficient to form a spout extending between said interface and said orifice of said tube, said spout substantially comprising said lower liquid being withdrawn from said container, said spout having a maximum diameter base portion at said interface and decreasing in diameter as the spout approaches said tube, said base portion diameter being greater than the diameters of the particles to be coated, said pumping rate being sufficient to draw said particles from said lower liquid and through the spout;

    coating a particle by drawing the particle upwardly through said spout from said base portion wherein the particle is engulfed by a coating of said spout liquid, to an upper spout portion, said upper spout portion having a diameter less than the diameter of the particle, thereby causing a break in said spout and freeing said coated particle for flow through said tube;

    re-establishing said spout by continuing said pumping at said sufficient pumping rate, and coating additional particles by drawing each particle to be coated upwardly through said spout from said base portion to an upper portion of said re-established spout having a diameter less than the diameter of the particle being coated, thereby causing a break in said spout and freeing said coated particle;

    repeating said coating process until all of said particles to be coated have been drawn upwardly through said spout and coated with said spout liquid; and

    collecting said coated particles.

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