Patent NZ-604043-A (NZ)
Title: Microcapsule suspensions including high levels of agriculturally active ingredients
Inventor: TANK HOLGER
IPC: A01N25/28
Filed: 2011-04-11
Abstract: The disclosure relates to methods for the formation of microcapsules that include (i) a high concentration of agriculturally active ingredients selected from the group consisting of fungicides, insecticides, nematocides, miticides, biocides, termiticides, rodenticides, arthropodicides, and herbicides; and (ii) a lipophilic polymer encapsulated within a polymeric shell formed via an interfacial polycondensation reaction, wherein the monomer of the lipophilic polymer is selected from the group consisting of methyl acrylate, ethyl acrylate, or butyl acrylate, and the polymeric shell forming material is selected from the group consisting of polymethylene polyphenylisocyanate, ethylene diamine, diisocyanates or polyisocyanates. Particularly disclosed is a method of synthesizing a microcapsule, comprising the steps of: (a) creating a lipophilic phase, said lipophilic phase including: (i) a lipophilic polymer selected from the group consisting of polymeric acrylates, preferably selected from the group consisting of methyl acrylate, ethyl acrylate, or butyl acrylate, polyvinyl acetate homopolymers and copolymers and styrene butadiene latex; (ii) a dissolved solid lipophilic agriculturally active ingredient dissolved in an oil solvent wherein the agriculturally active ingredient is selected from the group consisting of fungicides, insecticides, nematocides, miticides, termiticides, rodenticides, arthropodicides, herbicides, and biocides, and (iii) a lipophilic shell forming material, wherein the lipophilic shell forming material is selected from the group consisting of: diisocyanates and polyisocyanates, preferably selected from the group consisting of polymethylene polyphenylisocyanate, ethylene diamine, diisocyanates or polyisocyanates; (b) emulsifying said lipophilic phase in the presence of water to from an oil-in water emulsion; and (c) forming a microcapsule suspension via an interfacial polycondensation reaction including the steps of adding a water soluble shell forming material to the oil-in water emulsion, wherein the water soluble shell forming material is selected from the group consisting of diamines, polyamines, water soluble diols and water soluble polyols; wherein the microcapsule suspension includes polymeric shells, wherein the polymeric shells encapsulate said lipophilic polymer, said oil solvent, and the agriculturally active ingredient, wherein the polymeric shells includes polyurea and wherein said microcapsules comprises between 25 weight percent to 45 weight percent active ingredient based on the total weight of the microcapsule suspension. The method may further include the steps: (d) controlling the temperature of the lipophilic phase such that the temperature of the lipophilic phase and the temperature of the emulsion is 5° C to 10° C below the initiator activation temperature of the lipophilic monomer during the forming step; (e) raising the temperature to the initiation activation temperature of the lipophilic monomer; and (f) polymerizing the lipophilic monomer into a lipophilic polymer. Under some conditions, these microcapsules may be formed using less lipophilic solvent than is required using convention microencapsulation techniques.