US 2002/0004059 A1 · BASE-TRIGGERED RELEASE MICROCAPSULES

Abstract

Microcapsules formed from an aminoplast shell wall and an encapsulated ingredient or ingredients enclosed within the wall in which the wall contains a base-cleavable ester moiety. These capsules have been found to be sensitive to the presence of base such that in the presence of base, the capsule walls are relatively quickly disintegrated or degraded so as to produce a relatively quick release of the encapsulated materials. Microcapsules of this invention are particularly suitable for use in controlling insects having an alkaline gut such as certain lepidoptera in that the capsule shell wall may be designed so as to quickly disintegrate under the alkaline conditions present in the gut of the insect thus providing a microcapsule which is safe to handle but which is selectively effective against certain undesirable insects while not harmful to beneficial insects or insects which do not feed on the capsule materials.

Claims51

Dependent claims

A microcapsule formed of an aminoplast shell wall and an encapsulated ingredient or ingredients enclosed within the wall, the wall containing an ester moiety having the formula:

core(A1—XCH2N<)t(A2—XCH2N<)u . . . (An—XCH2N<)y+B R1OH (IV)
where R1=H, or C1-C4 alkyl;
“core” is derived from a multifunctional C1-C20 aliphatic or cycloaliphatic alcohol containing at least two functional groups capable of esterification;
A1—XH, A2—XH, . . . An—XH each constitute one or more randomly oligomerized esters of 2-hydroxy C2-C6 substituted alkanoic acids and/or 2-thiol C2-C6 substituted alkanoic acids, where XH represents the terminal alcohol or sulfhydryl capable of reacting with an etherified amino formaldehyde prepolymer;
n is the number of functional groups on the core capable of reacting with derivatives of the 2-hydroxy and/or 2-thiol C2-C6 substituted alkanoic acids;
2 ≦B≦t+u+ . . . y;
and t+u+ . . . y≦n.

4 more elements

A process for the production of microcapsules formed of an aminoplast shell wall and containing an encapsulated ingredient or ingredients comprising incorporating into the shell wall an ester moiety having the formula

core(A1—XH)t(A2—XH)u . . . (An—XH)y (I)
where “core” represents a structure derived from a multifunctional C1-C20 aliphatic or cycloaliphatic alcohol containing at least two functional groups capable of esterification;
A1—XH, A2—XH, . . . An—XH each constitute one or more randomly oligomerized esters of 2-(hydroxy or thiol) substituted C2-C6 alkanoic acids and/or 2-thiol C2-C6 substituted alkanoic acids, where XH represents the terminal alcohol or sulfhydryl capable of reacting with an amino-formaldehyde prepolymer;
n is the number of functional groups on the core capable of reacting with derivatives of the 2-hydroxy and/or 2-thiol C2-C6 substituted alkanoic acids;
and t+u+ . . . y≦n.

2 more elements

A process for producing a microcapsule having an aminoplast shell wall comprising (i) reacting an etherified amino resin prepolymer with a cross-linking agent having the formula

core(A1—XH)t(A2—XH)u . . . (An—XH)y (I)
where “core” represents a structure derived from a multifunctional C1-C20 aliphatic or cycloaliphatic alcohol containing at least two functional groups capable of esterification;
A1—XH, A2—XH, . . . An—XH each constitute one or more randomly oligomerized esters of 2-(hydroxy or thiol) substituted C2-C6 alkanoic acids and/or 2-thiol C2-C6 substituted alkanoic acids, where XH represents the terminal alcohol or sulfhydryl capable of reacting with an amino-formaldehyde prepolymer;
n is the number of functional groups on the core capable of reacting with derivatives of the 2-hydroxy and/or 2-thiol C2-C6 substituted alkanoic acids;
and t+u+ . . . y≦n. (ii) providing an organic phase comprising the product of step (i) and a material or materials to be encapsulated;
(iii) creating an emulsion of the organic phase in a continuous phase aqueous solution comprising water and a surface agent, wherein the emulsion comprises discrete droplets of the organic phase dispersed in the continuous phase aqueous solution, there being formed thereby an interface between the discrete droplets of organic solution and the surrounding continuous phase aqueous solution;
and (iv) causing in situ condensation and curing of the amino resin prepolymer and the organic phase of the discreet droplets adjacent to the interface by simultaneously heating the emulsion to a temperature between about 20° C. to about 100° C. and adding to the emulsion an acidifying agent and maintaining the emulsion at a pH of between about 0 to about 4 for a sufficient period of time to allow substantial completion of in situ condensation of the amino resin prepolymer to convert the liquid droplets of the organic phase to capsules consisting of solid permeable polymer shells enclosing the material to be encapsulated.

4 more elements

Dependencies are inferred from the claim text.

Base-triggered release microcapsules

Life of this patent

Base-triggered release microcapsules

Life of this patent

Abstract

Claims51