| 摘要 |
Process of microencapsulation employing acid precursor (type A) gelatin as the encapsulating macrocolloid, particularly applicable to the formation of liquid center microcapsules containing a basic (cationic) nitrogen compound. For example, an aqueous solution of acid-precursor gelatin is mixed at an alkaline pH with a water-immiscible organic solvent solution of the nitrogen compound, such as an amine or quaternary. The pH of the mixture and the gelatin phase is reduced to at least 4.0 and preferably 3.0 or below, the liquid phases being intermixed to disperse and emulsify the organic solvent phase in the aqueous phase, thereby providing minute droplets of the basic nitrogen containing organic solvent surrounded by the aqueous solution of the acid-precursor gelatin. On the completion of the pH reduction, the gelatin will have formed a coating around the individual droplets to provide encapsulating skins therefor. While the encapsulated droplets can be recovered with some success at the lowest acid pH, it is much preferred to raise the pH to a pH at least above 5.5 and preferably to an alkaline pH before recovering the microcapsules. An auxiliary coating can be applied to the recovered microcapsules by contacting them with an aqueous solution of alkali-precursor gelatin.
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