Plant protecting and regulating compositions – Plant growth regulating compositions – Plural active ingredients
Reexamination Certificate
1999-08-13
2002-08-27
Pryor, Alton (Department: 1616)
Plant protecting and regulating compositions
Plant growth regulating compositions
Plural active ingredients
C504S139000
Reexamination Certificate
active
06440902
ABSTRACT:
The present application relates to the field of active ingredient formulations for use in agricultural or pharmaceutical applications.
Microencapsulated formulations have been developed to answer issues concerning controlled release, volatility, or toxicity of certain active ingredients, thereby providing a means for using such ingredients. Formulations of this type that have been described for the herbicide clomazone (see U.S. Pat. No. 5,597,780), for example, are fragile when in concentrated form. The fragility of the microcapsules interferes with preparing concentrated compositions containing with a second component, because the preparation process tends to release the formerly microencapsulated active ingredient. The present invention describes methods and materials for making such two component concentrates. Also, hitherto microcapsules having two or more different active ingredients have not been described. The present invention provides methods and materials for making such two component microcapsules.
SUMMARY OF THE INVENTION
The invention provides a method of encapsulating clomazone and a second biological agent comprising:
mixing (i) an aqueous phase, (ii) an emulsifier and (iii) a water-immiscible phase containing clomazone, the second biological agent, and at least one first polyfunctional compound;
forming a dispersion of water-immiscible droplets throughout the aqueous phase; and
adding at least one second polyfunctional compound into the dispersion and reacting the second polyfunctional compound(s) with the first polyfunctional compound(s) to form a polymer shell around the water-immiscible droplets.
The first or second polyfunctional compounds are “polyfunctional” in the sense that each has the capacity to react to form a covalent bond with two or more compounds of the same class as the other polyfunctional compound. For instance, the first polyfunctional compound can be a polyfunctional isocyanate, while the second polyfunctional compound can be an amine.
Also provided is an agricultural composition comprising capsules containing, together, clomazone and a second biological agent.
The invention further provides a method of preparing an agricultural composition comprising encapsulated clomazone and a second biological agent, the method comprising:
(a) providing a suspension of clomazone capsules comprising solutes, diluents or carriers;
(b) providing a composition of suspended particles of the second biological agent;
(c) adjusting solutes, diluents or carriers in the particle suspension so that the osmolarity of the particle suspension is sufficiently like that of the capsule suspension so that the capsules are not disrupted when the suspensions of steps (a) and (b) are mixed; and
(d) mixing the suspensions of steps (a) and (b).
In one embodiment, the method further comprises:
(e) milling composition of suspended particles at least until the particles are no more than about 100 &mgr;m, in some cases as small as 1 &mgr;m, in size.
Accordingly, also provided is an agricultural composition comprising an aqueous suspension of (a) capsules of clomazone and (b) particles, which are distinct from the clomazone capsules, comprising a second biological agent.
DEFINITIONS
The following terms shall have, for the purposes of this application, the respective meanings set forth below.
Agricultural agent shall mean a bioactive agent used in agriculture, such as a herbicide, insecticide or fungicide.
Bioactive agent shall mean a substance such as a chemical that can act on a cell, virus, organ or organism, including but not limited to insecticides, fungicides and herbicides, which substance creates a change in the functioning of the cell, virus, organ or organism.
A particle (which may be liquid) containing a bioactive agent is encapsulated if it is coated with or admixed with an amount of polymer which slows release of the encapsulated agent, reduces the toxicity of the agent to mammals, stabilizes the form of the agent, inhibits crystallization of the agent, reduces the volatility of the agent or produces any other benefit of coating a chemical agent with a polymer or admixing the chemical agent with the polymer.
A microcapsule shall mean an encapsulated particle which is no more than about 1,000 &mgr;m in size, preferably no more than about 20 &mgr;m in size.
A particle size limit for a composition shall mean that at least about 90% of the particles in the composition shall be within the size range cited, where size is measured by light scattering using an instrument, such as a Laser Scattering Particle Size Distribution Analyser, Horiba Instrument Corp., Irvine, Calif.
The use of the modifier “about” with respect to pH is used herein to indicate a variance of at least one half a pH unit, and preferably indicates a variance of one half a pH unit. In other contexts herein where the modifier “about” is used to qualify a non-log unit, the “about” is intended to indicate a variance of ±15%, yet more preferably a variance of ±10%.
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the invention involves the co-microencapsulation of clomazone and another agricultural agent such as a herbicide (for example, dimethachlor). In one preferred embodiment, the co-microencapsulated formulations of the invention are made according to the following steps:
mixing (i) an aqueous phase, (ii) an emulsifier and (iii) a water-immiscible phase (also referred to as an “organic” phase) containing clomazone, a second agricultural agent, and a polyfunctional isocyanate;
forming a dispersion of water-immiscible droplets throughout the aqueous phase; and
adding an amine, preferably a polyfunctional amine, into the dispersion and reacting the amine with the polyfunctional isocyanate to form a polyurea shell around the water-immiscible droplets.
Note that while an amine can be a “polyfunctional compound” as described above, the term “polyfunctional amine” refers to compounds with two or more amine functional groups. In a particular embodiment, the invention can comprise the steps of (a) preparing an aqueous phase containing an emulsifier and an antifoam agent; (b) preparing a water-immiscible phase containing clomazone, a second agricultural agent, and a polyfunctional isocyanate; (c) emulsifying the aqueous phase with the water-immiscible phase to form a dispersion of water-immiscible droplets throughout the aqueous phase; and (d) agitating the dispersion while adding to it, either neat or in an aqueous solution, an amine or mixture of amines, thus forming a polyurea shell around the water-immiscible droplets. Once the microcapsules are formed, the suspension can be cured, i.e., incubated over time under polymerization supporting conditions, including, for example, moderate heating. One or more additives, such as propylene glycol, xanthan gum, urea, bactericides, amphoteric surfactants, dyes or ionic dispersing agents (e.g., alkyl naphthalene sulfonate), can be added to the microcapsules. The pH of the formulation is then, in some preferred embodiments, adjusted to neutral, e.g. about pH 6.5 to about 7.5, for example, to improve stability.
The clomazone/herbicide combination is preferably at a ratio of from about 1 to about 20 (~1:~20) to about 20 to about 1 (~20:~1) clomazone to herbicide. For example the ratio of clomazone to dimethachlor can be about 1 to about 12.5 clomazone to dimethachlor. In addition the clomazone/herbicide combination can be, for example, about 5 to about 40, preferably about 31.0, weight percent of the total formulation.
The co-microencapsulated formulations can contain, for example, one or more of the following additional components in the following amounts (in weight percent) based on the total weight of the formulation: 1) emulsifier—up to about 1.5, preferably about 1, weight percent; 2) antifoam agent—up to about 0.5, preferably about 0.25, weight percent; 3) polyfunctional isocyanate—about 2 to about 5, preferably about 4, weight percent; 4) polyfunctional amine—about 1.5 to about 4, preferably about 2.4, weight percent; 5) water—about 40 to about
FMC Corporation
FMC Corporation
Pryor Alton
LandOfFree
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