| 摘要 |
A process for the preparation of a microencapsulated composition comprises: (a) combining (i) a trusocyanate that is an adduct of linear aliphatic isocyanates having the formula O=C=N~(CH2)n~N=C=O, where n is from about 4-18, (ii) an aliphatic diisocyanate that contains a cycloaliphatic or aromatic ring moiety, the aliphatic diisocyanat e having from about 6-32 carbon atoms, most preferably from about 8-18 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 a t least a major portion of the core chemical encapsulated within the capsule wall of the microcapsules. Suitable core chemicals include agricultural chemicals such as herbicides and safeners. By adjusting the composition of the capsule walls and the contents of the capsule core, t he rate of release of the core materials from the microcapsules can be adjusted. When the core contains two or more materials to be released , the microcapsules can provide a more rapid rate of release for one core material than for another.
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