Method of encapsulating active agents with inorganic coatings
US4464317A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 24, 1982 |
| Grant date | Aug 7, 1984 |
| Priority date | — |
| Expiry date | Mar 24, 2002 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB01J13/04
- WIPO fieldPharmaceuticals
- WIPO sectorChemistry
Abstract
A method for forming discrete capsules that contain an active agent, such as a pesticide, involves first forming a suspension of the active agent suspended in a solution of an alkali metal silicate such as sodium silicate or a suspension of the active agent suspended in a liquid coacervate resulting from the addition of a coacervation agent such as acetone to the alkali metal silicate solution. The suspension, preferably in the form of droplets formed by ejecting the suspension through an orifice (e.g. a needle), is then contacted with an aqueous solution of a salt such as calcium chloride which reacts with the alkali metal silicate to form an insoluble silicate (e.g., calcium silicate) coating for the active agent while hardening the dispersed active agent in a silicate core matrix. Thus, capsules of the active agent are produced with an insoluble silicate coating. The capsules are maintained in the aqueous salt solution for a sufficient period of time to permit a high degree of conversion of soluble silicate to insoluble silicate. The capsules are then isolated and dried thereby providing structurally intact capsules which act as a free-flow powder. The capsules provide controlle…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.