Gel-coated microcapsules

DETAILED DESCRIPTION OF THE INVENTION The coated microcapsules of the invention feature microcapsules coated with a gel, specifically a gel produced by the sol-gel process.
The gel coating provides certain resistances to the microcapsules, resulting in enhanced protection for their contents.
Microcapsules containing different types of materials are known, as are microencapsulation techniques to prepare such materials, which are used as starting materials in the process of this invention.
Microcapsules can be used in many applications in which materials are to be contained either indefinitely or temporarily.
Microcapsules have been designed to allow the slow release of pharmaceutical preparations, cosmetic products and food products such as flavoring agents.
The microcapsules used in the present invention on the other hand, are adapted to contain materials that interact indirectly with the environments in which they are used.
Microcapsules are prepared according to known procedures.
The material which makes up the microcapsule wall can be chosen from a wide variety of materials.
The choice of materials depends primarily on the physical and chemical characteristics of the contents, and on the intended use of the microcapsules.
The microcapsules should also be readily coatable with the metal oxide gel.
Preferred microcapsule wall-forming materials include various thermoplastic materials, such as natural or synthetic fatty alcohols, fatty acids, fatty esters and waxes.
Natural waxes include the vegetable waxes such as carnuba, cauassu, candelilla, farria, palm, esparto, sugar cane and cotton waxes; animal waxes such as beeswax, ghedda, chinese insect, shellac, spermaceti and lanolin waxes; and mineral wax such as paraffin, microcrystalline, ozokerite, montan and syncera waxes.
Synthetic and modified waxes useful as microcapsule wall-forming materials include the Carbowaxes, Abril waxes, Armid and Armowaxes (Armour & Co.
) and Chlorax chlorinated paraffin wax (Watford Chemical Co.
).
It will be appreciated that waxes are a mixture of various components, and that each type of wax is itself available in a number of different grades