Microcapsules with readily adjustable release rates
US5925595A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 5, 1997 |
| Grant date | Jul 20, 1999 |
| Priority date | — |
| Expiry date | Sep 5, 2017 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08G18/765
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
A process for the preparation of a microencapsulated composition comprises: (a) combining (i) a triisocyanate that is an adduct of linear aliphatic isocyanates having the formula O.dbd.C.dbd.N--(CH.sub.2).sub.n --N.dbd.C.dbd.O, where 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, 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 at 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, the rate of release of the core materials from the microcapsules can be adjusted. When the core contains two or more materials to be released,…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.