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 moiety
1
in 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 C
1
-C
20
alkyl, C
2
-C
20
alkenyl, C
3
-C
8
cycloalkyl or C
5
-C
8
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.
一种微胶囊,由聚
脲壳壁和包封在壳壁内的一种或多种包封成分构成,壳壁包括至少一种低聚
缩醛,其分子式为
1
其中 R 是(a)含有 5 至约 40 个任选取代的碳原子链的分子,(b)含有 4 至约 40 个碳原子链和一个或多个内部连接的氧或
硫原子或 -NH- 基团的分子,或(c)任选取代的
乙烯或
丙烯分子 Z 是(a)任选取代的苯基,(b)任选取代的 C
1
-C
20
烷基、C
2
-C
20
烯基,C
3
-C
8
环烷基或 C
5
-C
8
环烷基,或 (c) 苯甲酰基,如果 R 为 (a) 或 (b),则 n 为 1,如果 R 为 (c),则 n 为 2-20。
微胶囊对酸敏感,通过将微胶囊与酸性物质(最好是有机酸或
无机酸)接触,胶囊壁相对容易降解或崩解,从而将封装成分释放到周围环境中。本发明特别适用于
生物活性物质和农用
化学品的封装,最理想的是用于叶面处理的
杀虫剂。