| abstract |
A method and composition for the in-flight encapsulation of particles such as insecticides, herbicides, molluscicides, acaricides, fungicides, nutrients, pheromenes, odorants, fragrances, attractants, repellants, trace elements, and the like. The composition comprises, by weight, from 1 to 40 percent of said particles, from 0.3 to 25 percent of a film-forming polymer and from 35 to 99 percent of a solvent which renders said polymers soluble. Often, other compounds may be added to impart desirable properties such as a second film-forming polymer, crosslinking agents, film modifying agents, and adhesives to improve adhesion to a target. The particle may be in a true solution suspended or emulsified through the action of surfactants and/or emulsifying agents. The film-forming polymer is selected from the class consisting of polyvinyl ethers, polyvinyl acetate, and interpolymers of alpha-beta olefinically unsaturated carboxylic acids and N-methylol acrylic amides, as set forth in U.S. Pat. No. 3,007,887. Upon ejection from a spray apparatus and during flight through the intervening atmosphere, the solution rapidly loses the solvent component via evaporation, coacervation occurs, and a polymeric membrane forms about the particle. Control of the encapsulated particle size can be achieved through selection of the spray system and of the non-volatiles in the spray at the moment of droplet formation. |