Microcapsules in which release of active substance is mediated by an acid

Mikrokapsle tvorené polymocovinovým pláštem a obsahující složku nebo složky uzavrené v plášti, kde stena plášte obsahuje alespon jednu oligomerní acetalovou skupinu vzorce I, kde R je a) skupina obsahující retezec od 5 do 40 volitelne substituovaných atomu uhlíku, b) skupina obsahující retezec od 5 do 40 atomu uhlíku a jeden nebo více interne navázaných atomu kyslíku nebo síry nebo NH-skupin, nebo c) volitelne substituovaná ethylenová nebo propylenová skupina; Z je a) volitelne substituovaná fenylová skupina, b) volitelne substituovaný C1 až C20alkyl, C2 až C20alkenyl, C3 až C8cykloalkyl nebo C5 až C8 cykloalkenyl nebo c) benzoyl; n je 1, pokud R je a) nebo b), nebo je 2 až 20, pokud R je c). Mikrokapsle jsou citlivé na pusobení kyseliny a stena kapsle se relativne snadno degraduje nebo desintegruje a složky se uvolnují do okolního prostredí. Mikrokapsle jsou vhodné pro enkapsulaci biologicky aktivních substancí a agrochemikálií, nejlépe pesticidu pro ošetrování rostlin. In the present invention, there are disclosed microcapsules 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 group represented by formula I in which R represents (a) a group containing a chain of from 5 to about 40 optionally substituted carbon atoms, (b) a group 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 group; Z denotes (a) an optionally substituted phenyl group, (b) an optionally substituted alkyl group containing 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group containing 3 to 8 carbon atoms or a cycloalkenyl group having 5 to 8 carbon atoms 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 microcapsules of the present invention are particularly suitable for encapsulation of biologically active substances and agrochemicals, and most preferably pesticides for foliar treatment.