Dual-walled microcapsules and a method of forming same
US4076774A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 27, 1976 |
| Grant date | Feb 28, 1978 |
| Priority date | — |
| Expiry date | Feb 27, 1996 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08G18/16
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
In accordance with a preferred embodiment of this invention, an active agent, such as a catalyst or a cocatalyst, is encapsulated in a dual-walled microcapsule. Both walls of the microcapsule are polymerization reaction products and both are formed in one basic process. The active agent is initially dissolved in a slowly polymerizing liquid monomer mixture such as a solution of toluene diisocyanate and a polyoxyalkylene polyol. The "monomer solvent" and the active agent combination is selected so that the active agent is nonreactive but soluble in the liquid monomer and insoluble in the polymer formed therefrom. However, before the active agent precipitates, the solution is dispersed in a nonreactive medium and the outer polymeric wall is formed by vigorously stirring the dispersion and then adding a reactive polyfunctional monomer. This polyfunctional monomer, which preferably has two primary aliphatic amine functionalities in terminal or near terminal positions, such as ethylene diamine, quickly reacts with the isocyanate of the initial monomer solution, via an interfacial polymerization reaction, to form the outer polyurea wall around each bead in the dispersion. Then the active…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.