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Microcapsules with readily adjustable release rates

  • US 5,925,595 A
  • Filed: 09/05/1997
  • Issued: 07/20/1999
  • Est. Priority Date: 09/05/1997
  • Status: Expired due to Term
First Claim
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1. A process for the preparation of a microencapsulated composition, comprising:

  • (a) combining (i) a triisocyanate that is an adduct of linear aliphatic isocyanates having the formula
    
    
    space="preserve" listing-type="equation">O═

    C═

    N--(CH.sub.2).sub.n --N═

    C═

    Owhere n is from about 4-18, (ii) an aliphatic diisocyanate that contains a cycloaliphatic or aromatic ring moiety, the aliphatic diisocyanate having from about 6-32 carbon atoms, and (iii) a water-immiscible composition comprising a core chemical;

    (b) adding an aqueous liquid and forming an oil-in-water emulsion;

    (c) adding a polyamine to the emulsion; and

    (d) reacting the triisocyanate, the diisocyanate, and the polyamine, thereby producing a plurality of microcapsules having a capsule wall, with at least a major portion of the core chemical encapsulated within the capsule wall of the microcapsules.

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