Chemistry: fertilizers – Processes and products – Forms or conditioning
Patent
1991-02-06
1992-11-03
Lovering, Richard D.
Chemistry: fertilizers
Processes and products
Forms or conditioning
71DIG1, 264 43, 264 433, 264 47, 424408, 424457, 424497, 42840221, 514963, A01N 3718, B01J 1318
Patent
active
051605295
ABSTRACT:
Microcapsules containing a substantially water-insoluble liquid material, such as an anilide herbicide, and optionally also a herbicide antidote, within a porous shell to effect a slow rate of release of said herbicide (and optionally said antidote) through said shell, are produced by a process which comprises (a) providing an organic solution comprising said material and an etherified amino resin prepolymer dissolved therein which from about 50% to about 98% of the methylol groups of said prepolymer have been etherified with a C.sub.4 -C.sub.10 alcohol; (b) creating an emulsion of said organic solution in a continuous phase aqueous solution comprising water and a surface-active agent, wherein said emulsion comprises discrete droplets of said organic solution, there being formed thereby an interface between the discrete droplets of organic solution and the surrounding continuous phase aqueous solution; and (c) causing in situ self-condensation and curing of said amino resin prepolymer in the organic phase of said discrete droplets adjacent to said interface by simultaneously heating said emulsion to a temperature between about 20.degree. C. to about 100.degree. C., and adding to said emulsion an acidifying agent and maintaining said 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 said resin prepolymers to convert the liquid droplets of said organic solution to capsules consisting of solid permeable polymer shells enclosing said liquid material.
Also disclosed are the microcapsules formed by the above-described process.
REFERENCES:
patent: 4105823 (1978-08-01), Hasler et al.
patent: 4157983 (1979-06-01), Golden
patent: 4272282 (1981-06-01), Hansen et al.
patent: 4557755 (1985-12-01), Takahashi
patent: 4956129 (1990-09-01), Scher et al.
"50 Years of Amino Coating Resins", (Albert J. Kirsch, ed.), (1986).
Rodson Marius
Scher Herbert B.
Ackerman Joel G.
Imperial Chemical Industries plc
Lovering Richard D.
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