WO2018032389A1

WO2018032389A1 - Herbicide composition comprising clomazone and use thereof

Info

Publication number: WO2018032389A1
Application number: PCT/CN2016/095621
Authority: WO
Inventors: Yifan Wu; James Timothy Bristow
Original assignee: Jiangsu Rotam Chemistry Co., Ltd.
Priority date: 2016-08-17
Filing date: 2016-08-17
Publication date: 2018-02-22
Also published as: GB2567099A; CN109640651B; GB201901591D0; EP3500098A4; GB2567099B; CN109640651A; EP3500098A1

Abstract

A composition comprising a water-immiscible material or high volatile material encapsulated within a microcapsule is provided, the microcapsules having a shell comprising a polyurea cross-linked by epoxy resin polymer. The method for preparing the same, and the use of the same in the control of unwanted plant growth are also provided.

Description

HERBICIDE COMPOSITION COMPRISING CLOMAZONE AND USE THEREOF

Field of Invention

The present invention concerns an improved microcapsules having epoxy resin incorporated in the polyurea shell wall. The material to be encapsulated is water-immiscible material or high volatile material. The capsule can be dispersed in an aqueous phase. The capsules may be produced to any desired size, for example, of the order of 1 micron up to 100 microns or larger, preferably the size of the microcapsules will range from about 1 to about 50 microns in diameter.

Description of Related Art

Technology has been available for many years to effectively provide microcapsules with liquid oleophilic ingredients and many methods of preparing capsules have been developed. Most methods of encapsulation require two phases and make use of a dispersion or emulsion of one phase in another. Usually, the phases are a polar phase and a non-polar phase. Although in principle two immiscible organic phases could be used, in practice there is generally an aqueous (polar) phase and an oil containing organic (non-polar) phase. Most commonly, the fill material is the material to be encapsulated and is contained in the organic phase. Two methods of encapsulation that have achieved commercial utility are referred to as in-situ polymerization and interfacial polymerization.

Matson, U.S. Pat. No. 3,516,941, discloses in-situ polymerization reactions in which the material to be encapsulated is dissolved in an organic, hydrophobic oil phase which is dispersed in an aqueous phase. The aqueous phase has dissolved resin precursors, particularly aminoplast resin precursors, which upon polymerization will form the wall of the microcapsule. A dispersion of fine oil droplets is prepared using high shear agitation. The degree of shear has a major effect on the droplet size and may serve to keep the capsule size small. Addition of an acid catalyst initiates the polycondensation of the aminoplast precursors within the aqueous phase, resulting in the formation of an aminoplast polymer which is insoluble in both phases. As the polymerization advances, the aminoplast polymer separates from the aqueous phase and deposits on the surface of the dispersed droplets of the oil phase to form a capsule shell at the interface of the two phases, thus encapsulating the fill materials. This process produces the microcapsules. Polymerizations that involve amines and aldehydes, such as those described herein, are also known as aminoplast encapsulations. Urea-formaldehyde (UF) , urea-resorcinol-formaldehyde (URF) , urea-melamine-formaldehyde (UMF) , and melamine-formaldehyde (MF) , capsule formations proceed in this manner.

In interfacial polymerization, the materials to form the capsule wall are in separate phases, one in an aqueous phase and the other in a fill phase. Polymerization occurs at the phase boundary. Thus, a polymeric capsule shell wall forms at the interface of the two phases thereby encapsulating the fill materials. Wall formation of polyester, polyamide, and polyurea capsules proceeds via interfacial polymerization.

Attempts to use water soluble polymers to control droplet size and subsequent capsule size were carried out by Sinclair, U.S. Pat. No. 4,396,670. Sinclair used water soluble polymers such as acrylamide-acrylic acid copolymers, anionic starch solutions, and sodium alginate in the aqueous phase during encapsulations employing melamine-formaldehyde. These water soluble polymers stabilize the dispersion of the oil phase with respect to the pre-condensate and inhibit droplet coalescence, thus controlling droplet size as well as stabilizing the dispersion. The water soluble polymer also reacts with the melamine/formaldehyde pre-condensate to form the capsule shell wall.

Solubilized inorganic materials have been used to modify the surface of particles to be encapsulated. Ugro, U.S. Pat. No. 4,879,175, encapsulated inorganic pigment particles in microcapsules prepared by in-situ polymerization (such as aminoplast polymerization) , interfacial polymerization, and coacervation. Because the pigment particles were insoluble in both the oil and water phases, Ugro used surface modifying agents to control the relative wettability of the solids by the organic and aqueous phases. Surface modifying agents such as titanates and silanes were used to modify the surface of the pigment, render it oleophilic, and thus encapsulable in the capsule fill (oil phase) . Control of the relative wettability enabled the deposition of smooth, relatively fault free shells and could be used to control the location of the pigments within the microcapsule structure. Pigments such as metal oxides, carbon black, phthalocyanines, and particularly oil and water insoluble cosmetic colorants were successfully encapsulated by this method.

None of the above cited references disclose the incorporation of epoxy resin materials into polyurea capsule walls. None of the above work uses epoxy resin materials to control the release rate of the capsule.

SUMMARY OF THE INVENTION

The present invention provides an improved herbicide composition comprising water-immiscible material or high volatile material contained within an encapsulating polymer skin material comprising a polyurea cross-linked by epoxy resin.

The microcapsules of the present invention have a polymer wall of a polyurea cross-linked by epoxy resin polymer. The polyurea cross-linked by epoxy resin polymer is formed interfacial polymerization occurring at the interface of a dispersed organic phase and a continuous aqueous phase.

The polyurea cross-linked by epoxy resin polymer is preferably formed by the reaction of an isocyanate, in particular a polyfunctional isocyanate, an epoxy and a polyfunctional amine. The microcapsules are formed by interfacial polymerization reaction. In particular, a water immiscible organic phase is provided comprising water-immiscible material or high volatile material, one or more polyfunctional isocyanates and an epoxy resin polymer. An aqueous phase is provided comprising one or polyfunctional amines. The organic phase is dispersed in known manner in the aqueous phase, as a result of which formation of the polyurea cross-linked by epoxy resin polymer occurs at the interface of the dispersed organic phase and the aqueous phase. It is an advantage of the present invention that the mixture of components, once dispersed, does not need to be heated to induce the interfacial polymerization reactions.

One or more surfactants and/or stabilizers may be included in the mixture, as required, as described hereinafter.

Accordingly, in a further aspect, the present invention provides a method of preparing a microencapsulated composition, the method comprising:

(a) providing a first water-immiscible organic phase comprising an epoxy resin, such as amine-terminated diglycidyl ether of biphenyl-A (DGEBA) prepolymers； an active ingredient to be encapsulated and a polyisocyanate；

(b) providing an aqueous phase comprising emulsifier, surfactant and an antifoam；

(c) dispersing the first organic phase into the aqueous phase； and

(d) allowing an interfacial polymerization reaction to occur at the interface of the organic phase and the aqueous phase to form a polyurea shell when polyamines was added, having the active component encapsulated therein.

In one particular embodiment, the process comprises the steps of:

(a) providing at room temperature, a water-immiscible organic phase comprising:

(i) amine-terminated diglycidyl ether of biphenyl-A (DGEBA) prepolymers suspended in organic phase.

(ii) isocyanate terminated diglycidyl ether of biphenyl-A (DGEBA) prepolymers formed with the introduction of polyisocyanate into the organic phase.

(iii) an active ingredient to be encapsulated, such as clomazone,

(b) providing at room temperature, a aqueous phase comprising:

(i) a solution of water, emulsifier, surfactant and a antifoam；

(c) dispersing the water-immiscible organic phase into aqueous phase；

(d) adding polyfunctional polyamine； and

(e) heating and maintaining the dispersion from about 40℃ to about 60℃, preferably at about 50℃. whereupon the water-immiscible material is encapsulated within discrete polyurea capsule enclosures directly usable without further separation or purification.

(f) adding necessary adjuvant, such as PH adjustor, thickening agent, antifreeze agent when the temperature was cooled down from about 35℃ to about 20℃, preferably cooled down to about 30℃.

The microcapsules of the present invention are formed by the reaction of a polyfunctional isocyanate. Suitable polyfunctional isocyanates have two or more isocyanate groups. Examples of compounds providing reactive isocyanate groups include para-phenylene diisocyanate, meta-phenylene diisocyanate, naphthalene-1, 5-diisocyanate, tetrachloro-m-phenylene diisocyanate, 2, 4-toluene diisocyanate, 2, 6-toluene diisocyanate, 4, 4-diphenyl diisocyanate, the dichloro diphenyl methane diisocyanates, bibenzyl diisocyanate, bitolylene diisocyanate, the diphenyl ether diisocyanates, the dimethyldiphenyl diisocyanates, the polymethylene polyphenyl isocyanates, triphenylmethane-4, 4', 4"-triisocyanate, isopropylbenzene α-diisocyanate and the like.

The microcapsules of the present invention are further formed from a polyfunctional amine. Suitable amines for use have two or amine groups. Examples of suitable amines for use in the present invention are diamine and higher polyamine reactants, including ethylene diamine, phenylene diamine, toluene diamine, hexamethylene diamine, diethylene triamine, triethylenetetramine, piperazine, 1, 3, 5-benzenetriamine trihydrochloride, 2, 4, 6-triaminotoluene trihydrochloride, tetraethylene pentamine, pentaethylene hexamine, polyethylene imine, 1, 3, 6-triaminonaphthlene, 3, 4, 5-triamino-1, 2, 4-triazole, melamine, and 1, 4, 5, 8-tetraminoanthraquinone.

The microcapsules of the present invention are formed to have a shell of a cross-linked polymer, in particular a polyurea cross-linked by epoxy resin polymer. The cross linking agent is a surfaced modified epoxy resin. Epoxy resin can be selected from diglycidyl ether of biphenyl-A (DGEBA) and its derivative.

Surface-modified means that the epoxy resin surface has been (chemically) modified so as to have cross-linkable, reactive functional groups. The surface of the epoxy resin may be modified using modifying agents selected from a wide variety of chemicals.

With regard release rates, normal knowledge for the chemist specialized in controlled release formulations is enough in order to select the appropriate isocyanates, amine and crosslinker. Obviously, amine-terminated epoxy resin with longer alkyl-groups will lead to faster release, because bigger pores. Accordingly, the smaller the particle size (obtained also by higher shear stress and use of surfactants in the oil phase) the faster the release rate. Also, the more quantity of wall material in weight ％with respect weight of whole filled microcapsule, the slower will be the release.

The following epoxide compounds are particularly suitable for the process according to the invention: epoxidised diolefins, dienes or cyclic dienes, such as butadiene dioxide, 1, 2, 5, 6-diepoxyhexane and 1, 2, 4, 5-diepoxycyclohexane； epoxidised diolefinically unsaturated carboxylic acid esters, such as methyl 9, 10, 12, 13-diepoxystearate； the dimethyl ester of 6, 7, 10, 11-diepoxyhexadecane-1, 16-dicarboxylic acid； and epoxidised compounds containing two cyclohexenyl radicals, such as diethylene glycol bis- (3, 4-epoxycyclohexanecarboxylate) and 3, 4-epoxycyclohexylmethyl 3, 4-epoxycyclohexanecarboxylate.

Further compounds which can be used are polyglycidyl esters such as are accessible by reacting a dicarboxylic acid with epichlorohydrin or dichlorohydrin in the presence of alkali. Such polyesters can be derived from aliphatic dicarboxylic acids, such as oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid and sebacic acid, and especially from aromatic dicarboxylic acids, such as phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, 2, 6-naphthylene-dicarboxylic acid, diphenyl-o, o'-dicarboxylic acid, ethylene glycol bis- (p-carboxyphenyl) ether and others.

Further compounds which can be used are polyglycidyl ethers such as are accessible by etherification of a dihydric or polyhydric alcohol or diphenol or polyphenol with epichlorohydrin or dichlorohydrin in the presence of alkali. These compounds can be derived from glycols, such as ethylene glycol, diethylene glycol, triethylene glycol, 1, 2-propylene glycol, 1, 3-propylene glycol, 1, 4-butylene glycol, pentane-1, 5-diol, hexane-1, 6-diol, hexane-2, 4, 6-triol and glycerol, and especially from diphenols or polyphenols, phenol novolacs or cresol novolacs, resorcinol, pyrocatechol, hydroquinone, 1, 4-dihydroxynaphthalene, phenol/formaldehyde condensation products, bis- (4-hydroxyphenyl) -methane (bisphenol F) , bis (4-hydroxyphenyl) -methylphenylmethane, bis- (4-hydroxyphenyl) tolylmethane, 4, 4'-dihydroxydiphenyl, bis- (4-hydroxyphenyl) sulphone and especially 2, 2-bis- (4-hydroxyphenyl) -propane (bisphenol A) .

Particularly suitable epoxy compounds are epoxy resins, for example, of the average formula:

in which Z is a small number and is an integer or fraction, for example between 0 and 25.

The diglycidyl ethers of bisphenol A

The diglycidyl ethers of bisphenol A to be used in accordance with the present invention are diglycidyl ethers having the formula:

wherein z represents 0 or a positive number having a value of 0 to about 25.

Diglycidyl ether of biphenyl-A (DGEBA) prepolymers are prepared by reaction of epichlorohydrin with 2, 2-bis (p-hydroxyphenyl) propane (bisphenol-A) in the presence of an alkali metal hydroxide, characterized by:

(a) gradually feeding an aqueous solution of alkali metal hydroxide into a mixture of epichlorohydrin and bisphenol-A in a molar ratio of at least 10: 1, until the ratio between the moles of alkali metal hydroxide fed in and the number of phenolic hydroxyl groups in said mixture is from 1: 1 to 1.05: 1, while maintaining the reaction medium at boiling point, distilling off water in the form of an azeotropic mixture with epichlorohydrin and recycling the distilled epichlorohydrin into the reaction medium, the addition of alkali metal hydroxide and the distillation conditions being so adjusted as to maintain in the reaction medium a content of liquid water of from 0.1 to 0.7 wt. ％and a pH value between 7 and 9； and

(b) recovering the epoxy resin from the reaction products.

Preferably, the epichlorohydrin/bisphenol-A molar ratio should not exceed 15: 1. Values of the said ratio which are less than 10: 1 do not give epoxy resins with the desired characteristics, especially as regards the values of the viscosity and the hydrolyzable chlorine content. On the other hand no appreciable improvements are obtained by using epichlorohydrin/bisphenol-A molar ratios greater than 15: 1.

The best results are obtained by maintaining said ratio at a value of from 12: 1 to 13: 1.

The aqueous solution of alkali metal hydroxide is fed in until the ratio between the moles of alkali metal hydroxide and the number of phenolic hydroxyl groups is from 1: 1 to 1.05: 1, so as not to enhance those secondary reactions which give rise to the formation of undesirable by-products. It should be noted that it was usual in the art to employ a large excess of alkali metal hydroxide with respect to the stoichiometric value (typically an excess of 10-20％) , with the object of reducing the hydrolyzable chlorine content in the epoxy resin, with consequent diminutions in yield and formation of undesirable by-products.

Preferably, a concentrated aqueous solution of alkali metal hydroxide is used, for example a solution containing from 40 to 50 wt. ％of the said hydroxide. The hydroxide is preferably sodium or potassium hydroxide.

The fundamental feature of the process of this invention consists in keeping an amount of water of from 0.1％to 0.7％by weight and a pH value between 7 and 9 in the reaction medium, during the addition of alkali metal hydroxide.

It has in fact been found that the use of water contents beyond the indicated range leads to the production of epoxy resins with excessively high values of molecular weight and viscosity. These resins typically have a viscosity at 25℃. greater than 8,000 cps.

On the other hand, use of a pH value greater than 9 brings about undesirable effects similar to those encountered in those known methods in which excess alkali metal hydroxide is used.

The best results are obtained by maintaining in the reaction medium a water content of 0.4 to 0.6％by weight and a pH value between 7 and 8.

The water is continuously removed from the reaction medium in the form of an azeotropic mixture with epichlorohydrin； the vapors thus produced are condensed with separation into two layers, the aqueous layer being discharged and the epichlorohydrin layer being recycled into the reaction medium.

The feed rate of the aqueous solution and the rate of evaporation of the water (reaction water and that introduced with the alkali metal hydroxide) are adjusted so as to maintain the water content and pH of the reaction mass within the ranges of values defined above. The addition of the aqueous alkali metal hydroxide is generally effected in a period of from 3 to 6 hours.

In practice it has been found that these conditions are more easily achieved when the reaction mass is boiled at a pressure of from 150 to 350 mm Hg., and at a temperature of from 70℃ to 90℃. It has also been found that the best results, as regards all the characteristics of the liquid epoxy resin, are obtained by avoiding, as far as possible, contact of the reaction mass with the alkali metal chloride obtained as a by-product of the reaction.

To this end the reaction mass may be circulated continuously through a self-cleaning filter or a centrifuge, placed outside the reaction zone. This operation is facilitated by the fact that, in view of the working conditions, the alkali metal chloride precipitates in crystalline form and can therefore be removed without too much difficulty.

Upon completion of the alkali metal hydroxide addition, it is generally convenient to keep the mass boiling for a period of time of from 10 to 20 minutes, thus removing the residual water.

Finally the liquid epoxy resin is recovered from the reaction products by conventional methods. Thus, for example, water can be added to the reaction products to wash out the alkali metal chloride. The aqueous phase is then separated from the organic phase consisting of a solution of the liquid epoxy resin in epichlorohydrin. Obviously this operation may not be necessary when the alkali metal chloride is removed in the course of the reaction.

The unreacted epichlorohydrin is then distilled off, and it is generally convenient to filter off the distillation residue so as to remove any inorganic compound present.

The reaction yields based on the converted epichlorohydrin are in each case 95％or more, whereas in known methods in which an excess of sodium hydroxide of 10-20％over the stoichiometric value is used, these yields are of the order of 85-90％.

Derivative of diglycidyl ethers of bisphenol A

Functionalization of the hydroxyl groups of the bisphenol-A epichlorohydrin derived polymer significantly alters its properties and produces a markedly different material A variety of reactants may be used to modify the bisphenol-A epichlorohydrin derived polymer and form a linear polymer of the following structure having ester, amide, ether, or silyl ether groups in place of the free hydroxyl groups:

where J is --C (O) R¹, --C (O) NHR², --C (O) NR² R³, --CHR⁴OR⁵, or --SiR¹R²R³, and R¹, R², R³, R⁴, and R⁵ are substituted or unsubstituted alkyl, aryl or cycloalkyl groups such as: --CH₃ --CH₂Cl, --CH₂OCH₃, --CH₂CH₃, --CH (CH₃) ₂, --C₄H₉--n, --C₅H₁₁--n, --C₈H₁₇--n, --CH (C₂H₅) ₂, --C₆H₁₁ --c, --CH₂CH₂C₆H₅, --CH₂CH (C₆H₅) ₂, --CH₂OCH₂C₆H₅, --CH₂CH₂C₆H₃ (3, 4--OCH₃) , --CH₂CO₂C₂H₅, --C₆H₅, --C₆H₄ (p--C₅H₁₁) , --C₆H₄ (p--OC₅ H₁₁) , and --C₆H₄ (p--C₁₀H₂₁) . R⁴ and R⁵ may also optionally join together to form a heterocycle. When J is --SiR¹ R² R³, R¹, R², and R³ are preferably chosen from methyl and phenyl groups.

For the purposes of this invention, a polymer derived from bisphenol-A and epichlorohydrin is considered to be "substantially free of free hydroxyl groups" when at least 50％of the polymer units derived from epichlorohydrin do not contain free hydroxyl groups. Preferably, at least 75％of such units, and more preferably at least 95％of such units, will have their free hydroxyl groups blocked.

Examples of particular polymers of the invention according to the above formula include E-1 through E-19, which are obtained by blocking the free hydroxyl groups of

PKHH Phenoxy Resin:

The polymers of the invention give improved stability as compared to the non-functionalized polymer containing free hydroxyl groups, and compared to bisphenol-A polycarbonate.

The multi-phase reaction mixture used to prepare the microcapsules in the present invention comprises a polyfunctional isocyanate and a polyfunctional amine, in addition to the cross-linking agent. The degree of cross-linking of the polymer wall may be controlled, inter alia, by selection of the polyfunctional reactants. Sufficient polyfunctional reactant, is provided in the reaction mixture to produce microcapsules wherein the polyurea cross-linked by epoxy resin capsule wall is from 3 to 60％cross-linked, more preferably 3 to 30％cross-linked, that is, from 3 to 60％, more preferably from 3 to 30％of the polymer is part of a three dimensional polymer network. In more preferred embodiments the polyurea cross-linked by epoxy resin capsule wall is from 3 to 30％cross-linked.

The microcapsules may have any suitable particle size. The average particle size of the microcapsules will generally range from about 1 to about 130 microns, preferably from 1 to 100 microns, more preferably from 1 to 50 microns, with a preferred average particle size of about 1 to 50 microns. Such relatively fine particles are advantageous to prevent plugging of orifices in the spraying equipment used for field application of the pesticide compositions.

The wall thickness of the microcapsules may be selected according to the intended use of the composition. The wall thickness of the polyurea cross-linked by epoxy resin capsule preferably ranges from about 0.01 micron to 4 microns, with from about 0.01 to 1 microns thickness preferred. The thickness of the capsule wall, as well as the degree of crosslinking of the polymer constituting same, will affect the rate of diffusion of the active ingredient therethrough, and thereby influence the performance of the composition in the field. The microcapsule size may be controlled during the manufacturing process by controlling the degree of dispersion of the material to be encapsulated and the water-immiscible phase in the aqueous phase. This may be achieved, for example, by controlling the degree of agitation of the multi-phase mixture and the number, type and amount of emulsifying agents present in the continuous phase. The microcapsule wall thickness may be further controlled by the quantity of the reactive intermediate present in the water-immiscible phase to be encapsulated.

The multi-phase reaction mixture may contain other components, as required, for example to provide microcapsules of the required size and/or to facilitate other aspects of the process. For example, the aqueous phase may comprise one or more surfactants. Suitable surface active agents are known in the art and include the sodium salt of alkylnaphthalene sulfonic acid, the potassium salt of alkylnaphthalene sulfonic acid, salts of polystyrenesulfonic acid, in particular, the alkali metal, alkaline earth metal and ammonium salts thereof, and salts of condensates of naphthalenesulfonic acids, and mixtures thereof. The dispersant system for the microencapsulation process may also optionally contain one or more non-ionic surfactant, non-ionic protective colloid, or a cationic component. Lignosulfonates are a particularly preferred surfactant for use in the process, in particular sodium lignosulfonate.

The compositions of the present invention may include one or more emulsifiers. The emulsifiers can be cationic, anionic or nonionic, but are more preferably anionic or nonionic. Examples of particularly suitable anionic surfactants for this purpose are sulfonates such as calcium dodecyl benzenesulfonate. Examples of particularly suitable nonionic surfactants are polyoxyethylated (POE) sorbitan esters such as POE (20) sorbitan trioleate and polyoxyethylated (POE) sorbitol esters such as POE (40) sorbitol hexaoleate. Suitable emulsifiers are known in the art and are commercially available. For example Polyvinyl alcohol (

203) , POE (20) sorbitan trioleate is commercially available under the tradename TWEEN 85 marketed by Uniqema. POE (40) sorbitol hexaoleate is commercially available under the tradenames ATLAS G1086 and CIRRASOL G1086 marketed by Uniqema.

The combination of a POE sorbitan ester with a POE sorbitol ester allows the HLB (hydrophilic-lipophilic balance) value of the surfactant to be optimized, so as to obtain the highest quality emulsion (smallest suspended droplets) when the composition is added to water. High quality emulsions typically lead to optimal herbicidal performance. Therefore of particular note for preferred herbicidal performance is a composition of the present invention comprising one or more nonionic surfactants selected from polyoxyethylated (POE) sorbitan esters such as POE (20) sorbitan trioleate and polyoxyethylated (POE) sorbitol esters such as POE (40) sorbitol hexaoleate and mixtures thereof.

The mixture may also comprise an antifoam agent. Again, suitable antifoam agent are known in the art. One preferred agent is a polydimethyl siloxane antifoam agent (Dow

1500) .

The mixture may also comprise one or more antifreezing agent. Again, suitable antifreezing agents are known in the art. One preferred agent is Propylene Glycol.

Other components that may be included in the multi-phase reaction mixture include one or more stabilizers. Suitable stabilizers are known in the art and include calcium chloride, sodium nitrate.

It may also be preferred to include in the reaction mixture a neutralizing agent, in particular to control the pH and prevent the formation of acidic conditions which may arise as a result of the condensation reactions. Suitable neutralizing agents are known in the art and include hydrochloric acid.

An exemplary recipe for preparing the cross-linked polyurea cross-linked by epoxy polymer encapsulating polymer wall for clomazone is as follows:

polyfunctional isocyanate (such as polymethylene polyphenylisocyanate known as "PAPI" ) : x moles, where x is from 0.1 to 0.5；

amine terminated epoxy resin: 1 -x moles；

diethylene triamine (atrifunctional polyamine) : y moles, where y ＝ 0 to 1.5；

difunctional amine (such as ethylene diamine) : n-y moles, where n equals 1 to 3；

hydrochloride acid； 1 –x moles to neutralize the reaction system to be pH 6-9.

Excess amine may be present in the reaction mixture.

The water-immiscible phase may comprise a solvent. However, it is preferred that the active ingredient, in particular clomazone, acts as a water-insoluble organic solvent for the components to be present in the organic phase, in particular the cross-linking agent and the isocyanate.

The water-immiscible phase is dispersed in water and the amine is charged to the reaction as an aqueous solution. The procedure of US 3,577,515 may then be employed to produce the microencapsulated product.

The weight ratio of the active ingredient to the polymer in the microencapsulated composition may be any suitable ratio. Preferably, the weight ratio of the active ingredient, in particular clomazone, to the polymer in the microcapsules is in the range of from about 2: 1 to 50: 1, more preferably from 3: 1 to 8: 1, still more preferably 4: 1 to 7: 1, with a ratio of about 5: 1 being particularly preferred.

The microcapsules once prepared may be formulated in any suitable manner. Suitable formulations and formulating techniques for such microcapsules are known in the art. A suspension or slurry of the microcapsules in a suitable diluent, most preferably water, is one preferred embodiment for shipping, storing, and ultimately dispensing the composition to the area to be treated. Conventional spraying apparatus is used for application of these formulations.

The formulation may be applied directly to the target area. Alternatively, the composition may be further diluted, prior art application. For example, a convenient water dispersion, suspension or slurry for shipping and storage will consist of from about 10 to 30％by weight of microcapsules, more preferably about 25％, of the pesticide-containing microcapsules, which will be diluted with water to about 1％by weight for spraying.

It has been found that the formulations of the present invention exhibit a high level of stability when being shipped and stored.

The compositions of the present invention may be used to control unwanted plant growth at a locus.

Accordingly, in a further aspect, the present invention provides a method of controlling plant growth at a locus, the method comprising applying to the locus a composition as described hereinbefore.

The present invention further provides the use of the compositions described hereinbefore in the control of plant growth.

The compositions may be applied to the area where control of plant growth is desired, prior to or after emergence of the target plants, for example by spraying onto the surface of the soil or onto the foliage of the plants. The user may, if desired, blend the formulation into the upper layer of soil by cultivation.

As noted above, the compositions of the present invention are particularly suitable for the formulation of water immiscible material and high volatile material, such as clomazone, abamectin, pendimethalin, lambda cyhalothrin, spinosad, emamectin benzoate, deltamethrin, cypermethrin, acetochlor, alachlor, metolachlor and their mixture. The active ingredient to be encapsulated can be dissolved in aromatic solvent. One preferred aromatic solvent is SOLVESSO (EXXON MOBIL) .

In order that the concept of the present invention may be more completely understood, the following examples are set forth in which all parts are parts by weight unless otherwise indicated. These examples are set forth primarily for the purpose of illustration and any specific enumeration of detail contained therein should not be interpreted as a limitation in the present case.

EXAMPLES

EXAMPLE 1-13

General Procedure (synthesis of DEGBA)

One uses an apparatus comprising a reaction vessel (flask) , mechanical agitator, electric heater, distillation column, a condenser, a separator for the epichlorohydrin-water distillate fitted with a siphon for recycling the epichlorohydrin, and a system for regulating the pressure in the reaction vessel.

3.000 parts by weight of epichlorohydrin and 585 parts by weight of bisphenol-A (12.6: 1 molar ratio) are fed into the flask.

The pressure in the apparatus is regulated to the desired value and the mass is gradually heated to boiling point.

Then 420 parts by weight of a 49％by weight aqueous solution of sodium hydroxide are introduced gradually over a period of about 5 hours. Upon completion of this addition, the ratio of the number of moles of sodium hydroxide added to the number of phenolic hydroxyl groups is 1.00: 1.

During the addition of sodium hydroxide, the water is removed from the boiling mass in the form of an azeotropic mixture with epichlorohydrin. The resultant vapors are condensed, the denser epichlorohydrin layer is recycled and the aqueous layer is discharged.

In each case the conditions are so regulated as to maintain the water content of the reacting mass at the desired value.

After the addition of the sodium hydroxide the mass is kept boiling for a further 15 minutes. Then about 500 parts by weight of water are added, the mass is agitated for 20 minutes and the aqueous phase removed by decantation, operating at about 50℃.

The organic phase is distilled, working first at atmospheric pressure and then at subatmospheric pressure (about 10 mmHg) in order to remove the unreacted epichlorohydrin completely.

The distillation residue is finally filtered to remove any residual inorganic salts, using diatomaceous earth as a filter aid.

The liquid epoxy resin thus obtained is tested to determine its properties, and the results are recorded in the Table.

More particularly in the Table are recorded:

· under (A) the operating pressure in mm Hg；

· under (B) the temperature of the reacting mass；

· under (C) the average pH of the reacting mass；

· under (D) the average percentage by weight of water present in liquid form in the reacting mass, the determination being carried out by the Karl Fischer method；

· under (E) the rate of distillation expressed in ml of distillate per hour.

The values given in the Table under (A) , (B) , (C) , (D) and (B) are taken during the addition of the aqueous sodium hydroxide.

In the Table are recorded:

· under (F) the viscosity of the epoxy resin at 25℃. expressed in cps；

· under (G) the epoxy equivalent of the resin, as previously defined；

· under (H) the corresponding value of "n" with reference to formula (I) ；

· under (I) the hydrolyzable chlorine content expressed as a percentage by weight of the resin；

Example I is for comparison in that the water content in the reacting mass is less than the minimum value.

Examples 9 to 13 are also for comparison in that the said water content is greater than the maximum limit.

Examples 2 to 8 were carried out according to the process of the invention.

Table

Ex	A	B	C	D	E	F	G	H	I
1	760	112	7	0	500	10700	190	0.14	0.68
2	250	86	7.8	0.1	1000	7965	176	0.04	0.45
3	250	82	7.9	0.22	440	7843	180	0.07	0.29
4	200	75	6.7	0.24	1100	7578	181	0.07	0.28
5	350	90	7.5	0.25	490	7107	178	0.05	0.15
6	160	70	8	0.25	1120	6924	170	0	0.16
7	160	70	7.2	0.43	500	6127	173	0.02	0.12
8	250	80	8.8	0.58	150	6200	170	0	0.12
9	350	90	10	0.8	92	9800	186	0.11	0.61
10	450	100	9.2	1.1	84	10200	194	0.17	0.95
11	250	80	7.6	1.4	113	10120	189	0.13	0.85
12	760	110	14	4.1	190	11519	185	0.1	0.8
13	760	115	--	5	140	--	192	0.15	0.95

EXAMPLE 14 (COMPARISON)

Example 1 is repeated, using a 5％excess molar amount of sodium hydroxide with respect to the number of phenolic hydroxyl groups in the bisphenol-A feed.

A liquid epoxy resin is obtained with a hydrolyzable chlorine content of 0.3％by weight, whilst the other characteristics of the said resin remain practically unchanged.

EXAMPLES 15-21

Examples 2 to 8 are repeated using a 5％excess molar amount of sodium hydroxide with respect to the number of phenolic hydroxyl groups in the bisphenol-A feed.

Liquid epoxy resins are obtained with a hydrolyzable chlorine content of from 0.02 to 0.09％by weight, whilst the other characteristics remain practically unchanged.

EXAMPLES 22-26 (COMPARISON)

Examples 9 to 13 are repeated using a 5％excess molar amount of sodium hydroxide with respect to the number of phenolic hydroxyl groups in the bisphenol-A feed.

Liquid epoxy resins are obtained with a hydrolyzable chlorine content of 0.1-0.4％by weight whilst the other characteristics remain practically unchanged.

In Examples 14 and 22-26 the Hazen colour of the liquid epoxy resin is of the order of 200； in Examples 15-21 the Hazen colour is of the order of 80-120.

EXAMPLE 27

The apparatus described in the previous Examples is used, the flask being filled with 3,000 parts by weight of epichlorohydrin and 585 parts by weight of bisphenol-A (12.6: 1 molar ratio) .

The pressure in the apparatus is regulated to 160 mm Hg and the mixture is heated to boiling point.

439 parts by weight of a 49％by weight aqueous solution of sodium hydroxide are gradually introduced over 5 hours, the ratio between the moles of sodium hydroxide fed in and the number of hydroxyl groups being then of 1.048: 1. During this addition the water is removed in the form of an azeotrope with epichlorohydrin and the distilled epichlorohydrin is recycled.

Moreover the sodium chloride is formed as a by-product of the reaction, is removed by circulating the reaction mass continuously through a centrifuge placed outside the reactor.

After the addition of the sodium hydroxide solution, the unreacted epichlorohydrin is distilled off and the distillation residue is filtered in the manner already described.

Thus a liquid epoxy resin is obtained having the following characteristics:

· epoxy equivalent: 172

· viscosity at 25℃. (cps) : 7,000

· hydrolyzable chlorine (％by weight) : 0.003

· "pot-life" at 25℃. (minutes) : 100

· Hazen color: 60

· volatile substances (％by weight) : 0.

The reaction yield is equal to 95.3％of the theoretical.

The epoxy resin is represented by Formula (I) with "n" equal to 0.014.

EXAMPLE 28

Example 27 is repeated, 420 parts by weight of an aqueous 49％by weight solution of sodium hydroxide being fed in.

The epoxy resin thus obtained has a hydrolyzable chlorine content equal to 0.06％by weight whilst the other characteristics are practically unchanged.

EXAMPLE 29

General method to Synthesis amine-terminated Amine terminated DEGBA resin

1.5 g tetraoctylammonium bromide was mixed with 100 ml of dry toluene and the mixture was sonicated for 30 min, under a flow of dry Ar. 100 ml of DEGBA resin was added via a gas-tight syringe and sonication was continued for 30 min allowing entry into the micelles.

Alkylamine-terminated DEGBA resin with three different alkyl chain lengths were obtained in the reactions of degassed allylamine (2.7 g) , hex-5-en-1-amine (2.4 g) and undec-10-en-1-amine (4.4 g) to each flask with hydrogen-terminated DEGBA resin under Ar, in the presence of 40 ml of 0.05 M H₂PtCl₆ catalyst. After 30 min, sonication, 3-aminopropyl, 6-aminohexyl and 11-aminododecyl DEGBA resin were extracted with water, washed with ethyl acetate and filtered twice through syringe membrane filters (Millex, Millipore, PVDF, 0.45 mm) . The resulting amine-terminated DEGBA resin were further purified by dialysis against water (MWCO 7000, SERVA, Membra-Cel dialysis tubing, diameter 22 mm) to remove any residual nonreacted aminoalkene and surfactant.

Synthesis of alkeneamines

Hex-5-en-1-amine.

6-Bromo-1-hexene (5 ml； 0.04 mol) was dissolved in 50 ml DMF. After addition of NaN₃ (0.20 mol) the mixture was stirred at 35 ℃ for 24 hours. Cold water was added and 6-azido-hex-1-ene was extracted with petroleum ether (PE 40/60) and washed 3 times with brine. Pure 6-azido-hex-1-ene has been obtained with 75％yield. 1H NMR (300 MHz, CDCl3, 293 K) : d (ppm) 5.81 (m, 1H) , 4.99 (m, 2H) , 3.26 (t, 2H) , 2.07 (m, 2H) , 1.60–1.36 (m, 6H) .

NH4Cl [0.09 mol, in 120 ml of ethanol–water (3 : 1) mixture] was added to 6-azido-hex-1-ene. Upon addition of 3.4 g of Zn powder, the reaction mixture was refluxed for 30 min. The mixture was filtered and ethanol was evaporated under reduced pressure. 12 ml of aqueous ammonia solution and 120 ml of ethyl acetate were added in order to extract hex-5-enylamine. The amine solution in ethyl acetate was washed 3 times with brine and the solvent was removed under reduced pressure and dried over magnesium sulfate. Pure hex-5-en-1-amine is obtained with 62％yield. 1H NMR (300 MHz, CDCl₃, 293 K) :d (ppm) 5.81 (m, 1H) , 4.98 (m, 2H) , 2.71 (t, 2H) , 1.40–1.10 (m, 8H) .

Undec-10-en-1-amine.

11-Bromoundecene-1-ene (10 ml； 0.05 mol) was dissolved in 50 ml of DMF. After addition of NaN₃ (0.20 mol) the mixture was stirred at 90℃ for 24 hours. Cold water was added and 11-azidoundec-1-ene was extracted with petroleum ether (PE 40/60) and washed 3 times with brine. Pure 11-azidoundec-1-ene has been obtained with 90.3％yield. 1H NMR (300 MHz, CDCl3, 293 K) : d (ppm) 5.80 (m, 1H) , 4.99 (m, 2H) , 3.26 (t, 2H) , 2.09 (m, 2H) , 1.61 (m, 2H) , 1.39 (m, 12H) .

NH4Cl [0.14 mol dissolved in 200 ml ethanol–water (3 : 1) ] was added to 11-azidoundec-1-ene. Upon addition of 3.9 g of Zn powder, the reaction mixture was refluxed for 30 min. The mixture was filtered and ethanol was evaporated under reduced pressure. 20 ml of aqueous ammonia solution and 200 ml of ethyl acetate were added in order to extract dodec-11-enylamine. The amine solution in ethyl acetate was washed 3 times with brine and the solvent was removed under reduced pressure and dried over magnesium sulfate. Pure undec-10-en-1-amine is obtained with 85％yield. 1H NMR (300 MHz, CDCl₃, 293 K) : d (ppm) 5.87 (m, 1H) , 4.97 (m, 2H) , 2.71 (t, 2H) , 1.42–1.17 (m, 18H) .

EXAMPLE 30

Preparation of microencapsulated clomazone.

A. A water-immiscible organic phase, prepared just prior to use having the following components:

· 9.36 g technical clomazone

· 0.28 g amine terminated DEGBA resin crosslinker from Example 29

· 0.77 g. polymethylene polyphenylisocyanate (PMPPI, Suprasec-5005 )

· 1.47g SOLVESSO (EXXON MOBIL)

B. An aqueous solution having the following components:

· 1.60 g POE (20) sorbitan trioleate

· 0.16g Lignosulfonic acid, sodium salt (Reax 88B)

· 0.16g Sulfonated aromatic polymer, sodium salt (MORWET D-425 POWDER)

· 0.03 g Antifoam (Dow

1500)

· 6.18 g Water

Step 1

0.28g amine terminated DEGBA resin crosslinker (from example 29) was dispersed in 1.47g SOLVESSO (EXXON MOBIL) . The mixture was mixed well at high speed in a high-shear mixer. 0.77g isocyanate (Suprasec-5005) was then added and the mixture was stirred for 10min. 9.36g clomazone was finally added.

Step 2

1.60g POE (20) sorbitan trioleate, 0.16g lignosulfonic acid, sodium salt (Reax 88B) , 0.16g sulfonated aromatic polymer, sodium salt (MORWET D-425 POWDER) and 0.03g antifoam (Dow

1500) was added in 6.18g water to be aqueous phase

Step 3

Water-immiscible organic phase was added dropwise into aqueous phase. After mixing by high-shear mixer, oil in water dispersion was formed.

Step 4

The oil in water dispersion was transferred into an Erlenmeyer flask. 0.77g diethylenetriamine aqueous solution (0.77g diethylenetriamine in 1.73g water) was added dropwise with stirring. The dispersion was heated and maintained at about 50℃ for 4 hours. Adjuvant, such as stabilizers (1.69g calcium chloride, 0.70g sodium nitrate) , thickening agent (2％Xanthan gum, 0.67g) , antifreeze agent (1.60g propylene glycol) was added when the temperature was cooled down to about 30℃. pH adjustor (hydrochloric acid 36-38％) was added to keep pH at 6-9.

EXAMPLE 31

Preparation of microencapsulated clomazone

A. A water-immiscible organic phase, prepared just prior to use having the following composition:

· 9.36 g technical Clomazone

· 0.28 g Amine terminated DEGBA resin crosslinker from Example 29

· 0.46 g. polymethylene polyphenylisocyanate (PMPPI, Suprasec-5005 )

· 1.47g SOLVESSO (EXXON MOBIL)

B. An aquous solution having the following composition:

· 1.60 g POE (20) sorbitan trioleate

· 0.16 g Lignosulfonic acid, sodium salt (Reax 88B)

· 0.16g sulfonated aromatic polymer, sodium salt (MORWET D-425 POWDER)

· 0.03 g antifoam (Dow

1500)

· 6.18 g Water

Step 1

0.28g amine terminated DEGBA resin crosslinker (from example 29) was dispersed in 1.47g SOLVESSO (EXXON MOBIL) . The mixture was mixed well at high speed in a high-shear mixer. 0.46g isocyanate (Suprasec-5005) was then added and the mixture was stirred for 10min. 9.36g Clomazone was finally added.

Step 2

1500) was added in 6.18g water to be aqueous phase.

Step 3

Step 4

The oil in water dispersion was transferred into an Erlenmeyer flask. 0.46g diethylenetriamine aqueous solution (0.46g diethylenetriamine in 2.04g water) was added dropwise with stirring. The dispersion was heated and maintained at about 50℃ for 4 hours. Adjuvant, such as stabilizers (1.69g calcium chloride, 0.70g sodium nitrate) , thickening agent (2％Xanthan gum, 0.67g) , antifreeze agent (1.60g propylene glycol) was added when the temperature was cooled down to about 30℃. pH adjustor (hydrochloric acid 36-38％) was added to keep pH at 6-9.

EXAMPLE 32

Preparation of microencapsulated clomazone

· 9.36 g technical Clomazone

· 0.77 g polymethylene polyphenylisocyanate (PMPPI, Suprasec-5005 )

· 1.47g SOLVESSO (EXXON MOBIL)

B. An aqueous solution having the following composition:

· 0.28 g amine terminated DEGBA resin crosslinker from example 29

· 1.60 g POE (20) sorbitan trioleate

· 0.16 g lignosulfonic acid, sodium salt (Reax 88B)

· 0.16 g sulfonated aromatic polymer, sodium salt (MORWET D-425 POWDER)

· 0.03 g antifoam (Dow

1500)

· 6.18 g water

Step 1

0.77g isocyanate (Suprasec-5005) was dispersed in 1.47g SOLVESSO (EXXON MOBIL) and the mixture was mixed well at high speed in a high-shear mixer for 10min. 9.36g clomazone was finally added.

Step 2

0.28g amine terminated DEGBA resin crosslinker (from example 29) , 1.6g POE (20) sorbitan trioleate, 0.16g lignosulfonic acid, sodium salt (Reax 88B) , 0.16g sulfonated aromatic polymer, sodium salt (MORWET D-425 POWDER) and 0.03g antifoam (Dow

1500) was added in 6.18g water to be aqueous phase.

Step 3

Step 4

EXAMPLE 33

Preparation of microencapsulated clomazone

· 9.36 g technical Clomazone

· 0.77 g. polymethylene polyphenylisocyanate (PMPPI, Suprasec-5005 )

· 1.47g SOLVESSO (EXXON MOBIL)

B. An aqueous solution having the following composition:

· 1.60 g POE (20) sorbitan trioleate

· 0.16g lignosulfonic acid, sodium salt (Reax 88B)

· 0.16g sulfonated aromatic polymer, sodium salt (MORWET D-425 POWDER)

· 0.03 g antifoam (Dow

1500)

· 6.18 g water

Step 1

0.77g isocyanate (Suprasec-5005) was dispersed in 1.47g SOLVESSO (EXXON MOBIL) . The mixture was mixed well at high speed in a high-shear mixer. 9.36g clomazone was finally added.

Step 2

1500) was added in 6.18g water to be aqueous phase.

Step 3

Step 4

Comparison the stability of polyurea cross-linked by epoxy resin in table 1 below:

Table 1

*in Example 32, crosslinker was added in aqueous phase.

EXAMPLE 34-36

Example 2 was repeated for the mixture of clomazone and any one of acetochlor, alachlor and metolachlor.

EXAMPLE 37-43

Example 2 were repeated for the following active ingredients: abamectin, pendimethalin, lambda cyhalothrin, spinosad, emamectin benzoate, Deltamethrin and cypermethrin.

Claims

A composition comprising a water-immiscible material or high volatile material encapsulated within a microcapsule having a wall comprising a polyurea cross-linked by epoxy resin polymer.
The composition according to claim 1, wherein the water-immiscible material or high volatile material is selected from clomazone, abamectin, pendimethalin, lambda cyhalothrin, spinosad, emamectin benzoate, deltamethrin, cypermethrin, acetochlor, alachlor, metolachlor and combination thereof.
The composition according to claim 1, wherein the water-immiscible material or high volatile material is clomazone.
The composition according to claim 1, wherein the weight ratio of the water-immiscible material or high volatile material to the polyurea cross-linked by epoxy resin polymer is in the range of from about 2: 1 to about 50: 1.
The composition according to claim 1, wherein the polyurea cross-linked by epoxy resin polymer is formed by the reaction of an isocyanate, an epoxy resin and a polyfunctional amine.
The composition according to claim 1, wherein the epoxy resin has an average formula:

in which Z is a small number and is an integer or fraction, for example between 0 and 25.
The composition according to claim 6, wherein the epoxy resin is selected from the group consisting of diglycidyl ether of biphenyl-A (DGEBA) and its derivative.
The composition according to claim 5, wherein the isocyanates is selected from the group consisting of include para-phenylene diisocyanate, meta-phenylene diisocyanate, naphthalene-1, 5-diisocyanate, tetrachloro-m-phenylene diisocyanate, 2, 4-toluene diisocyanate, 2, 6-toluene diisocyanate, 4, 4-diphenyl diisocyanate, the dichloro diphenyl methane diisocyanates, bibenzyl diisocyanate, bitolylene diisocyanate, the diphenyl ether diisocyanates, the dimethyldiphenyl diisocyanates, the polymethylene polyphenyl isocyanates, triphenylmethane-4, 4', 4"-triisocyanate, isopropylbenzene α-diisocyanate and the like.
The composition according to claim 5, wherein the polyfunctional amine is selected from the group consisting of ethylene diamine, phenylene diamine, toluene diamine, hexamethylene diamine, diethylene triamine, triethylenetetramine, piperazine, 1, 3, 5-benzenetriamine trihydrochloride, 2, 4, 6-triaminotoluene trihydrochloride, tetraethylene pentamine, pentaethylene hexamine, polyethylene imine, 1, 3, 6-triaminonaphthlene, 3, 4, 5-triamino-1, 2, 4-triazole, melamine, and 1, 4, 5, 8-tetraminoanthraquinone.
The composition according to any preceding claim, wherein the polymer of the microcapsule wall is from 3 to 30 ％ cross-linked.
The composition according to any preceding claim, wherein the microcapsules have an average size of from 1 to 50 microns.
The composition according to any preceding claim, wherein the average thickness of the polymer wall of the microcapsules is from 0.01 to 4 microns.
The composition according to any preceding claim, wherein the composition comprises one or more surfactants, and/or one or more emulsifiers, and/or an antifoam agent, and/or one or more antifreezing agent, and/or one or more stabilizers, and/or a neutralizing agent.
The composition according to any preceding claim, prepared from the following components:

polymethylene polyphenylisocyanate ( "PAPI" ) : x moles, where x is from 0.1 to 0.5；

amine terminated epoxy resin: 1 -x moles；

diethylene triamine (atrifunctional polyamine) : y moles, where y ＝ 0 to 1.5；

difunctional amine (such as ethylene diamine) : n-y moles, where n equals 1 to 3；

hydrochloride acid； 1 –x moles to neutralize the reaction system to be pH 6-9.
The composition according to any preceding claim, wherein the active compound is herbicidally active.
A formulation for controlling plant growth comprising a composition according to any preceding claim.
The formulation of claim 16, comprising a water dispersion, a suspension or a slurry of the microcapsules.
A method of preparing a microencapsulated composition, comprising:

(a) providing a first water-immiscible organic phase comprising an epoxy resin, an active ingredient and a polyisocyanate；

(b) providing an aqueous phase comprising emulsifier, surfactant and an antifoam；

(c) dispersing the first water-immiscible organic phase into the aqueous phase； and

(d) allowing an interfacial polymerization reaction to occur at the interface of the organic phase and the aqueous phase to form a polyurea shell when polyamines was added, having the active ingredient encapsulated therein.
A method of preparing a preparing a microencapsulated composition, comprising steps of:

(a) providing at room temperature, a water-immiscible organic phase comprising:

(i) amine-terminated diglycidyl ether of biphenyl-A prepolymers suspended in organic phase,

(ii) isocyanate terminated diglycidyl ether of biphenyl-A prepolymers formed with the introduction of polyisocyanate into the organic phase,

(iii) an active ingredient to be encapsulated；

(b) providing at room temperature, a aqueous phase comprising:

(i) a solution of water, emulsifier, surfactant and a antifoam；

(c) dispersing the water-immiscible organic phase into aqueous phase；

(d) adding polyfunctional polyamine； and

(e) heating and maintaining the dispersion from about 40℃ to about 60℃, preferably at about 50℃, whereupon the water-immiscible material is encapsulated within discrete polyurea capsule enclosures directly usable without further separation or purification；

(f) adding adjuvant, such as pH adjustor, thickening agent, antifreeze agent when the temperature was cooled down from about 35℃ to about 20℃, preferably cooled down to about 30℃.
A method of controlling plant growth at a locus, comprising applying to the locus a composition according to any of claims 1-8 or a composition obtained by the method according to any of claims 9-10.
A use of the composition according to any of claims 1-8 or the herbicide microcapsule obtained by the method according to any of claims 9-10 in the control of unwanted plant growth.