| abstract |
Microcapsules of a microcapsule formed of a polyurea shell wall and an encapsulated ingredient or ingredients enclosed within the wall, the wall comprising at least one oligomeric acetal having the moietyin which R is (a) a moiety containing a chain of from 5 to about 40 optionally substituted carbon atoms, (b) a moiety containing a chain of from 4 to about 40 carbon atoms and one or more internally linked oxygen or sulfur 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, and n is 1 if R is (a) or (b), or is 2-20 if R is (c). The microcapsules are acid-sensitive and the capsule walls are relatively readily degraded or disintegrated by contacting the microcapsules with an acidic substance, preferably an organic or inorganic acid whereby the encapsulated ingredient or ingredients are released into the surrounding environment. The invention is particularly suitable for encapsulation of biologically active substances and agrochemicals, and most preferably pesticides for foliar treatment. |