| 摘要 |
<p>Microcapsule formed of a polyurea shell wall and an encapsulated ingredient or ingredients, where the wall comprises at least one oligomeric acetal moiety of the formula: in which R is (a) a moiety containing a chain of 5 to about 40 optionally substituted carbon atoms, (b) a moiety containing a chain of 4 to about 40 carbon atoms and one or more internally linked oxygen or sulphur atoms or -NH- groups, or (c) an optionally substituted ethylene or propylene moiety; Z is (a) an optionally substituted phenyl group, (b) an optionally substituted C1-C20 alkyl, C2-C20 alkenyl, C3-C8 cycloalkyl or C5-C8 cycloalkenyl group, or (c) benzoyl, while n is 1 if R is (a) or (b) or is 2-20 if R is (c). According to the invention, the microcapsule wall is hydrolysable under acid conditions, thereby releasing the encapsulated ingredient into the environment. The invention is particularly suitable for the encapsulation of biologically active substances employed in agriculture.</p> |
