NZ201342A - Encapsulating water immiscible material within polyurea shell wall - Google Patents

Description

New Zealand Paient Spedficaiion for Paient Number £01 34£ 20134: / / Priority Date(s): Q&.'. r?..'3! Complete Specification Filed: Class: Publication Date: ... 11 A MAR 1986 P.O. Journal, No: .../Ml ADDITION TO NO. 193,261 HO DRAlflNSS NEW ZEALAND PATENTS ACT, 1953 No: Date: COMPLETE SPECIFICATION ENCAPSULATION BY INTERFACIAL POLYCONDENSATION We, MONSANTO COMPANY, a corporation organized and existing under the laws of the State of Delaware, United States of America of 800 North Lindbergh Boulevard, St. Louis, Missouri 63167, United States of America hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: (followed by page -la-) tt-Z- PATENT OFFICE ' 2 t JUL 1982 ^ "" " £ 20 -lc* » FNrapsnT.ftTTOM RY IMTBBTACIM. POLYCOMDj BACKGROUND OF THE INVENTION This invention rela.tes to a process for producing small or minute capsules containing a water-immiscible material which comprises dissolving polymethylene polyphenylisocyanate in said water-immiscible material, the material to be encapsulated, dispersing the resulting mixture in an aqueous phase containing an emulsifier selected from the group consisting of the salts of lignin sulfonate and thereafter adding a polyfunctional amine, whereby the amine reacts with polymethylene polyphenylisocyanate to form oil-insoluble polyurea microcapsule walls abeut the water-immiscible material at the oil/water interface. 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.

Capsules of this character have a variety of uses, as for containing dyes, inks, chemical reagents, pharmaceuticals, flavoring materials, pesticides, herbicides and the like. Any liquid, oil, meltable solid or solvent soluble material into which polymethylene polyphenylisocyanate can be dissolved and which is non-reactive with said isocyanate, may be encapsulated v/ith this process. Once encapsulated, the liquid or other form is preserved until it is released by some means, or instrumentality that breaks, crushes, melts, dissolves, or otherwise removes the capsule skin or until release by diffusion is effected under suitable conditions. The process of the■invention is particularly suitable for the production of herbicide containing microcapsules of v.ery small particle size, suspended in an aqueous solution.

Aqueous dispersions of pesticide and herbicide microcapsules are particularly useful in controlled release pesticide and herbicidal formulations because they can be diluted with water or liquid fertilizer and sprayed using ■ 2 6TS42 conventional equipment, thereby producing uniform field coverage of the pesticide or herbicide. Additives such as film forming agents can be added directly to the finished formulation to improve the adhesion of microcapsules to 5 foliage. In some cases, reduced toxicity and extended activity of encapsulated herbicides and pesticides have been noted. .

• A variety of techniques have heretofore been used or proposed for encapsulation purposes. In one such 10 process, known as "simple coacervation", a polymer separates from a solvent solution of the- polymer by the action of a-precipitating agent that reduces the solubility of the polymer in the solvent (e.g., a salt .or a non-solvent for the polymer). Patents describing such processes and their 15 shell wall material include U. S„ Patent Numbers- 2,800,458 (hvdrophilic colloids); 3,069,370 .and 3 ,116, 216 {polymer ic zein); 3,137,.631 (denatured proteins); 3,418,250 (hydrophobic .thermoplastic resins); and others.

Another method involves.microencapsulation based 20 on _in situ interfacial condensation polymerization. British Patent 1,371,179 discloses a process which consists of dispersing an organic pesticide phase containing a polymethylene polyphenyli-socyanat'e or toluene diisocyanate monomer into an aqueous phase. The wall forming reaction is 25 initiated by heating the batch to an elevated temperature at which point, the isocyanate monomers are hydrolyzed at the interface to- form amines, which in turn react with" unhycrolyzed isocyanate monomers to form .the polyurea microcapsule wall. One difficulty with this method' is the 30 possiblity of continued reaction of monomer after packaging. Unless all monomer is reacted during the preparation, there will be continued hydrolysis of the isocyanate monomer with evolution of CO2/ resulting in the development of pressure when the . formulation is packaged. - ✓ Various methods of encapsulation by interfacial 2^3 42 T' condensation between direct-acting, conplinentary reactions are known. Within these methods are reactions for producing various types of polymers as the capsule-walls. Many of such reactions to produce the coating substance occur . between an amine, which must be.of at least difunctional character and a second reactant intermediatewhich for producing.a polyurea is a difunctional or polyfunctional isocyanate. The amines chiefly used or proposed in these methods are typified by ethylene diamine, having at least 2 primary amino groups. U.S. Patent No. 3/429,827 and U.S. Patent No. 3,577,515 are illustrative of encapsulation by interfacial condensation.

For Exairple, U.S. Patent No. 3,577,515 describes a continuous - or batch method which requires a first reactant and a second reactant complimentary to .the first reactant, with each 15 reactant in separate phases, such' that the first and second • reactants react at the interface between the dropl'ets to form encapsulated dropiets. The pro'cess is applicable to a large variety of polyc'ondensation reactions, i.e., to many different pairs of reactants capable of interfaoial 2o ' condensation from respective carrier liquids to yield solid film at the -liquid interface. The resulting capsule skin may be produced as a polyamide, polysulfonamide, polyester, polycarbonate, polyurethane, polyurea or mixtures of reactants in one or both phases so as to yield corresponding 25 condensation copolymers. 'The reference describes the formation of a polyurea skin when, diamines or polyamines (e.g., ethylene diamine, phenylene diamine, toluene diamine, hexamethylene diamine and the like) are present in the water phase and diisocyanates or polyisocyanates (e.g., toluene 30 aiisocyanate , hexamethylene diisocyanate and polymethylene polyphenylisocyanate) are present in the organic/oil phase. In-the practice of U. S. Patent 3,577,515, the liquid which preponderates becomes the continuous phase liquid. That is', in forming oil containing microcapsules, the aqueous"-1 iquid 35 would preponderate; when water encapsulated microcapsules — 4 — AG 12 88 ► are formed, the oil phase-would preponderate.

Although a- number of methods are available in the art for producing microencapsulated pesticide and herbicide formulations there are various disadvantages associated with 5 the prior art methods. The encapsulated materials formed by the _in situ interfacial polymerization process of British Patent 1,371,179, require post-tr.eatment to prevent continued carbon dioxide evolution and excessive caking, thereby increasing the costs of the finished product. For 10 many processes of encapsulation, it is oftentimes necessary to separate the encapsulated material from the forming media. During the separation process, the capsule wall is s subjected to great stresses and strains which can result in premature rupture of ~the capsules with concomitant loss of 15 encapsulated material. These efforts also fall short of practical value in various other respects. Various experiments have indicated the difficulty in establishing the desired capsules in discreet form and avoiding coalescence of the partially formed capsules into a 20 heterogenous mass of materials lacking distinct capsule formation. Very low concentrations of intended .product relative to the total mixture are often obtained.

The present invention provides a new and improved • encapsulation process which is rapid and effective and which 25 avoids the necessity of separation of the encapsulated material from the continuous phase liquid. The present invention also, eliminates the need for using a strong solvent in the organic phase resulting in a savings of energy, and packaging and equipment ware. In addition, 30 direct combination of water-based herbicide and pesticide formulations are possible with other water-based pesticides.

The critical feature of the present invention resides in the use of lignin sulfonate emulsifiers, in 201342 -5- -AS 12 CC particular,- the salts of lignin sulfonate, as for example, the.sodium, potassium, magnesium, calcium or ammonium salts, to achieve emulsions wherein a concentrated amount of water-immiscible material is present in the water-immiscible phase. Generally there will be greater than 480 grams of water-irmus cible material present per liter of total composition. By use of the particular emulsifiers described herein, it is possible to retain the finished microcapsules.in the original aqueous solution, thus avoiding the additional step of separation of 10 the microcapsules froiti the original aqueous environment.

Further, the finished microcapsules do not agglomerate nor does the aqueous capsule mass solidify when stored for . extended periods of time or when exposed for short-terms to elevated temperatures.

The present*" invention is particularly advantageous- when- employed to encapsulate herbicides, especially acetanilide and th'iocarbamate herbicides 1 ike • alachlor, butachlor, propachlor', triallate, dialiate and the like. Experiments indicate that conventional oil/water herbicide "20 emulsifiers fail to produce sufficiently stable emulsions to attain microencapsulation of concentrated amounts of herbicide-material and avoiding solidification of the oil/water mass when amine is added. Additionally, attempts to encapsulate concentrated amounts of acetanilide and thiocarbamate herbicides, for example, four to five pounds per gallon (480 grains to 700 grams per liter) using traditional interfacial polymerization techniques, as for example that disclosed in U. S. Patent No. 3,577,515, have resulted in unsatisfactor formulations because of the problem of excessive herbicide pj!0 ' crystal growth, as well as agglomeration or solidification of the finished.suspensions. It is thought that herbicide crystal growth- results from either incomplete encapsulation of the herbicidal materia -s- 2 0 134,2 or from the passage of small amounts of herbicide through the polymeric' shell wall. The problem is particularly acute with the acetanilide herbicides.

Crystal growth is very undesirable because once it 5 occurs, the final formulations cannot be used directly; rather the microcapsules must be separated from the aqueous ' solution and resuspended in water before they can be sprayed in conventional agricultural herbicide and fertilizer spraying apparatus.

- It is accordingly a particular object of this invention to provide a process whereby greater than 4S0 grams of acetanilide .herbicides, e.g., alachlor, propachlor, butachlor and the like and thiocarbamste herbicides, e.g.,. triallate, diallate and the like, per liter of total composition, 15 is encapsulated in a polyurea shell wall' with the • r finished microcapsules being suspended' in the original aqueous solution. The suspended microcapsules may be stored for extended periods of time and may be exposed for short-terms to elevated temperatures without the occurrence 20 of.agglomeration .or solidification of the aqueous capsule formulation or excessive herbicide crystal formation. v— DETAILED DESCRIPTION OF THE INVENTION The invention relates.to a process of encapsulating a water-immiscible material within a shell 25 . wall of polyurea. The procedure of the invention involves first providing an aqueous solution containing an emulsifier selected from the group consisting of the salts of lignin 2 01342 AO 1200 sulfonate, for example, the sodium, potassium, magnesium, calcium or ammonium salts. Particularly effective for use herein, is the sodium salt of lignin sulfonate. A water-immiscible (organic) phase, which consists of a 5 water-immiscible material (the material to be encapsulated) and polymethylene polyphenylisocyanate, is added to. the aqueous phase, with agitation, to form a dispersion of small . droplets of water-immiscible phase within the aqueous phase. Thereafter, a polyfunctional amine, preferably, 1,6-hexa-10 methylene diamine, is added, with continued agitation, to the organic/aqueous d-ispersion. The polyfunctional amine reacts with polymethylene polyphenylisocyanate to form a capsular polyurea .shell about the water-immiscible material.-The__water-immiscible material referred to herein, 15 is the material to be encapsulated and is suitably, any liquid, oil, meltable solid or solvent soluble material, into which polymethylene polyphenylisocyanate can be dissolved and is non-reactive thereto. Such water-immiscible materials as herbicides, e.g., c<-chloro-20 2',61-diethyl-N-methoxymethyl acetanilide (commonly known as alachlor), N-butoxymethyl-©C-chloro-2',6'-diethylacetanilide (commonly known as butachlor), o^-chloro-N-isopropyl acetanilide (commonly known as propachlor), 2'-methyl-61-ethyl-N-(l-methoxyprop-2-y.l )-2-chloroacetanilide 25 (commonly known as metolachlor), 2'-t-butyl-2-chloro-N-rnethoxymethyl-6 ' -methylacetanilide , o<L-chloro-N- (2-methoxy-6-methylphenyl)-N-(1-methylethoxymethyl) acetamide, c<-chloro-N-methyl-N-[2-methyl-6-(3-methylbutoxy)phenyl]-acetamide ,c?c_-chloro-N- [2-methyl-6- (2-methylpropoxy)phenyl] -30 N-(propoxymethyl)acetamide, N-[ (acetylamino)methyl]-- chlorc-N-(2,6-diethylphenyl)acetamide, c*l-chloro-N-methyl-N- (2-methyl-6-propoxyphenyl )'acetamide , N- ( 2-butoxy-6-methyl-" phenyl) <=*--chloro-N-methyl acetamide, isobutyl ester of 2 , 4--(d ichlorophenoxy) acetic acid, 2-'chloro-N-(ethoxymethyl )-35 61-ethyl-o-acetatoluidide (commonly known as acetochlor), 2 0 1 34: ii1, ■ V -— * 1 y H- l-(l-cyclohexen-l-yl)-3-(2-fluorophenyl)-l-meth,yl urea, S-2,3,3-trichloroallyl-diisopropyl thiocarbamate (commonly known as triallate), S-2,3-dichloroallyl-diisopropylthiocar-bamate (commonly known as diallate), ^ ,oC,®C-trifluoro-5 2,6-dinitro-N,N-dipropyl-£-toluidine (commonly known as trifluralin), 2-chloro-4-ethylamino-6-isopropylamino-l,3,5-triazine (commonly known as atrazine), 2-chloro-4,6-bis-(ethylamino)-£-triazine (commonly known as simazine), 2-chloro-4,6-bis(isopropylamino)-s-triazine (commonly known as 10 propazine), 4-amino-6-(l,l-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H) one (commonly known as metribuzin), N'-(3,4-dichlorophenyl)-N-methoxy-N-methylurea (commonly known as linuron); _ od-chloro-N-(ethoxymethyl)-N-[2-methyl-6- (,trifluoromethyl )phenyl] acetamide and ^-chloro-N-(ethoxy-methyl)-N-[2-ethyl-6-(trifluoromethyl)phenyl]acetamide; insecticides, e.g., methyl and ethyl parathion, pyrethrin and pyrethroids (e.g., permethrin and fenvalerate); herbicidal safeners (antidotes), e.g., ethyl 2-chloro-4-20 (trifluoromethyl)-5-thiazolecarboxylate? benzyl 2-chloro-4-(trifluoromethyl)-5-thiazolecarboxylate and organic solvents, e.g., xylene and monochlorobenzene are specifically contemplated herein.

AG1 '1208- In the practice of the preferred embodiment of the present invention, the material to be encapsulated is a herbicideparticularly an acetanilide or thiocarbamate herbicide and more particularly alachlor, butachlor,. 5" propachlor, triallate'and diallate herbicides.

The material to be encapsulated utilizing the process of the present invention need not consist of only one type, but may be a combination of two or more various types of water-immiscible materials. For example, employing 10 an appropriate water-fmmiscible.material, such a combination is an active herbicide with another active herbicide or an active herbicide and an- active insecticide. Also contemplated i's a water-immiscible material to be encapsulated which comprises an active ingredient, such as a 15 herbicide, and an inactive ingredient, such as a solvent or adjuvant.

The water-immiscible material containing the dissolved polymethylene polyphenylisocyanate comprises the water-imm'iscible or organic phase. The water-immiscible 20 material acts as the solvent for polymethylene polyphenylisocyanate thus avoiding the use of other water-immiscible organic solvents and allowing for a concentrated amount of water-immiscible material in the final encapsulated product. The water-immiscible material 25' ana polymethylene polyphenylisocyanate are added simultaneously .to the aqueous phase in a pre-mixed state. That is, the water-immiscible material and polymethylene polyphenylisocyanate are pre-mixed to obtain a homogeneous water-immiscible phase before addition to and emul si f icat io.n 30 in the aqueous phase. 2 01342 -IQ- AG 1280' The concentration of water-immiscible material initially present in the water-immiscible phase should be sufficient to provide at least 480 grams of water-immiscible material per liter of aqueous solution. However, this is by no means limiting and a greater amount can be used. In practical "operation, as will be recognized by those skilled in the art, the use of extremely high concentrations of water-immiscible material will result in very thick suspensions of microcapsules. In general, the. concentration of water-immiscible material will range from about 480 grams to about 700 grams per liter of total composition. The preferred range is from about 4S0 grans to about 600 grams per liter of total•composition.

The polyisocyanate useful in this process is polymethylene polyphenylisocyanate. Suitable for use herein-are the following commercially available polymethylene polyphenylisocyanates: PAPI© and PAPI-135® (registered trademarks of the Upjohn Co.) and Mondur-MR® (registered trademark of the Mobay Chemical Company).

The polyfunctional amines suitable for use in the present invention are those amines which are capable of reacting with polymethylene polyphenylisocyanate to form a polyurea shell wall. The polyfunctional amines should be water-soluble per se or in water soluble salt form. The usable polyfunctional amines can be selected from a wide range of such materials. Suitable examples of polyfunctional amines which may be used in this invention include, but are by no means limited to the following: ethyleneaiamine, propylenediamine, isopropylenediamine, hexamethylenediamine, tolueneaiamine, ethenediamine , tri'ethylenetetraamine , tetraethylenepentamine , pentaethyl enehexamine , diethylenetrianine, bis-nexa-methylenetriamine and the like. The amines nay be used alcne or in combination with each other, preferably in combination wi th- 1, S-hexame thyl enedi an ine (Hi-iDA) .

-II - 2JU3 4 1,5^hexemethylenedismine is preferred for use in the process of the present invention.

Polymethylene polyphenylisocyanate and the polvfunctional amine form the shell wall which ultimately 5 encapsulates the water-immiscible material. The shell wall content of-the capsules formed by.the present process may vary from about 5 percent to about 30 percent, preferably 8 to 20 percent and more particularly, 10 percent by weight, of the water-immiscible material.

The amount of polymethylene polyphenylisocyanate • and polyfunctional amine used in the process is determined by the percent shell wall content produced. Generally, th.ere. will be present^ in the reaction, from about 3.5 percent to about 21.0 percent polymethylene polyphenylisocya .nate and from about 1.5 percent to about 9.0 percent amine, relative to the weight of the weter—irimiscible material. Preferably,, there will be from .about 5-.S to about 13.9 percent polymethylene polyphenylisocyanate and from about '2.4 to about 6.1 percent amine and more particularly, 7.0 20 percent polymethylene polyphenylisocyanate and 3.0 percent amine relative to the weight of the water-immiscible material, present in the • reaction. Although an excess amount of polyfunctional amine relative to the amount of polymethylene polyphenylisocyanate has been used herein, 2 5 it should be recognized that a stoichiometric amount of polyfunctional amine may be used without departing from the spirit or scope of the present invention.

The emulsifying agents, being generally referred to herein as emulsifiers, which are critical for use in the 30-practice .of the present invention are the salts of lignin sulfonate, e.g., the sodium, potassium, magnesium, calcium or ammonium salts. In the practice of the process of the 201342 -l%- AG" 1200 • •present invention, the sodium selt of lignin sulfonate is the preferred enulsifier. Any commercially available emulsifier of the.type previously described which does not contain added surfactant, nay be conveniently employed and 5 many are described in McCUTCHEON's DETERGENTS AND EMULSIFIER'S, North American Edition 1978 (McCutcheon Div., MC Publishing Co., Glen Rock, N. J.) . Commercially available emulsifiers which nay be mentioned are: Treax® r LTS, LTK and LTH, respectively, the potassium, magnesium and •10 sodium salts of 1ignosulfonate (50% aqueous solutions), Scott Paper Co., Forest Chemical Products; Marasperse CR© and Marasperse CBOS-3© , sodium lignosulfonate, American Can , Co.; Polyfon 0® , Polyfon T® , Reax 88B© , Reax 85B®, sodium salts of lignin sulfonate and Rea* C-21© , calcium salt of 15 lignin sulfonate, Westvaco Polychemic'als.

The range of emulsifier concentration found most acceptable in the system will vary from about 1/2 percent to about 15 percent and preferably from about 2 percent to about 6 percent, based on the weight of the 20' water-immiscible material. Sodium 1ignosulfonate emulsifier is.preferentially employed at a concentration of 2 percent relative to the weight of the water-immiscible material. Higher concentrations of emulsifier may be used without increased ease of aispersabi1ity.. 25 The microcapsules of the present invention require no additional treatment such' as. separation from the aqueous liquid, but may be directly utilized or combined with, e.g., liquid fertilizers, insecticides or the like to form aqueous solutions which nay be conveniently applied in agricultural 30 uses. Most often it is most convenient to bottle or can the aqueous suspension containing the encapsulated vater-inmiscible material-, in which case, it may be desirable to add formulation additives to the -finished" - 2 01342 -[3- aqueous solution of microcapsules. Fbrmulation additives such as thickeners, density balancing agents, biocides, surfactants, dispersants, dyes, salts, anti-freeze agents, anti-corrosion agents and the like can be added to inprove stability and ease of application.

Those skilled in the art of formulations will recognize that the preceding examples of formulation, additives are only illustrative and other additives may be advantageously enployed in the coirpositions described herein.

The process of the present invention is capable of satisfactory per-' formanoe and production of encapsulated material without adjustment to a specific pH value. That is, no adjustment of the pH of the system need be made during the encapsulation process. If it is desired to adjust the pH' of the finished microcapsule formulation, as, for exanple, when the aqueous solution of finished microcapsule is combined with other herbicides, pesticides, etc., conventional cooperating reagents or additions for adjustment of acidity or alkalinity, or like characteristics, may be used, e.g., such substances as hydrochloric acid, sodium hydroxide, sodium carbcnate, sodium bicarbonate and the like.

In the practice of the process of the invention, the temperature should be maintained above the melting point of the water-immiscible material but below the temperature wherein the polymeric shell wall will begin to hydrolyze excessively. For exanple, where it is desired to encapsulate a liquid organic solvent the tenperature of the process may be maintained at room temperature; where it is desired to encapsulate a solid herbicide, it will be necessary to heat the herbicide to its molten state. Alachlor herbicide, for' example, melts at 39.5°C to 41.5°C and the temperature of the process should accordingly be maintained above about 41.5°C. In general, the temperature of the reaction should not exceed above about 80°C, since the polymeric isocyanate monomer will begin to rapidly A 2 013 4 2 hycrolyze above this temperature, with resulting loss of formation of shell wall material.

The agitation' employed to establish the dispersion of vater-immiscible phase droplets in the aqueous phase may be. supplied by any means capable of providing suitably high shear, that is, any variable shear mixing apparatus (e.g., blender) can be usefully employed to provide the desired a.g i tat ion,.

The desired condensation reaction at the interface 10 between the water-inuniscible phase droplets and the aqueous phase occurs very rapidly and within minutes, the ■condensation reaction is complete. That is, the formation of the polyurea capsule wall has been completed, thereby • encapsulating the water-immiscible material within a skin of 15 polyurea and there exists a useable encapsulated product suspended in an aqueous liquid.

The particlei size of the microcapsules will range from about 1 micron up to about 100 mi-crons*'in diameter. In general, the smaller the particle size the better. From 20. about 1 to about 10 microns is an optimum range. From about 5 to about 5>0 microns is satisfactory for formulating.

Particle size is^controlled by the emulsifier used end the dcjree of agitation employed. One convenient'manner . of controlling the size of the microcapsules is by adjusting 25 the speed of agitation employed, which is supplied to form .the dispersion- of the water-immiscible phase droplets in the aqueous phase. The greater the speed of agitation at this stage, the smaller the capsules being obtained. Control of capsule size by adjustment of the rate o'f agitation is well 30 within the skill of the art.

The 'present invention, will be further explained by reference to the following examples which are merely illustrative and not limiting in nature. Unless otherwise 201342 stated, no change in particle size of the finished microcapsules in the aqueous suspending medium was observed with passage of time.

EXAMPLE 1 Ingredients Percent G rams Technical triallate (95%) .5 200. 0 PAPI-135© 2.7 13. 9 40% HMDA 3.0 .1 Reax 88 B® 0.8 4.0 Ammonium Sulfate 26.1 132. 0 Water 27.9 141. 3 TOTAL 100.0 506.3 200 g of technical triallate containing 13.9 g of PAPI-135®- was emulsified into 141.3'g- of water containing 4.0 g of Reax 88 B© sodium lignosul fonate. "[Technical triallate and PA'PI-135® were maintained at 50°C; the aqueous solution containing the sodium 1ignosulfonate emulsifier was at 50°C. The emulsion was formed with a VJaring blender operated at high shear. To the emulsion was added 15.1 g of 40% H>5DA with concurrent reduction of shear. After 20 minutes, 132.0 g of ammonium sulfate was added and the formulation was bottled. The particle size of the resulting microcapsules ranged from 1 to 10 microns in diameter. The resulting formulation contains 500 grams of encapsulated technical triallate per liter of aqueous solution.

EXAMPLE"2 Ingredients Percent Grams • Technical ala'chlor (91%) 49. 2 200. 0 PAPI® 3-7 . 0 %. HMDA 4.9 . 0 Reax 88 B® 0.9 3.8 Water 41.3 168. 0 Total 100.0 406.8 200- g of technical alachlor maintained at 50°C., 10 containing 15.0 grams of PAPI© was poured into 168.0 g of water containing 3.8 ~g of Reax 88 Ks> , sodium 1 ignosulfonate . emulsifier. An emulsion was formed in a square.beaker utilizing a Brinkraan Polytron Homogenizer, at high shear (the temperature inside the beaker rose to 6.0°C as a result 15, of the shear'rate) . To the emulsion was added 20.0 g of 35% KMDA with simultaneous reduction of shear to a slow rate. The resulting formulation contained 527 grasns of encapsulated technical alachlor per liter of aqueous solution. The resulting microcapsules were 1-10 microns in 20 diameter, particle size; About 20% liquid layer occurred with time but was resuspended with gentle shaking. 201342 EXAMPLE 3 Ingredient Percent G r ams Technical alachlor ' (91%) 49. 0 200. 0 PAPI®. 3.7 .0 40% HMDA 4. 0 16. 5 Reax 88 EP 0. 9 3.8 Water 38. 2 155.9 Ethylene Glycol 4.2 17 .1 Total 100. 0 408. 3 200.0 g of technical alachlor containing 15.0 g of .PAPI®was emulsified into-155.9 g of water containing 3.8 g of Reax 885® sodium 1ignosulfonate. Technical alachlor and PAPI®were maintained at 50°C; the aqueous solution containing the sodium 1ignosulfonate- emulsifier was at room 15 temperature. ".. The emulsion was formed with a -Waring blender .. operated'at high shear. To the emulsion was added 16.5 g of "40% KMDA with concurrent reduction of shear. After 20 « minutes, 17.-1 g of ethylene glycol was added and the formulation was bottled. Settling occurred with time but 20 gentle agitation fully resuspended the settled layer. - Only a trace of material greater than 45 microns was observed when the formulation was passed through a 325 mesh screen (45 micron opening).

The procedure of Example 3 was repeated using various 25 lignin sulfonate emulsifiers in place of Reax S8B© ; the lignin sulfonate emulsifiers were: Reax 85A0, Reax C-21®, Marasperse CB®, Polyfon K®, Polyfon 0°, Polyfon TO, Reax 84A an Marasperse CBOS-3®. ■ f -It- 29JJ42 EXAMPLE 4 Iriqredients Percent Grans Technical propachlor (96.6%) PAPi© . 8% HMDA Heax 8 8 B® Wa ter 46.'4 3.5 4. 3 0.9 4'4. 9 100. 0 7.5 9.3 2.0 96. 6 Total 100. 0 \ 215.4 ' starting materials and the Waring blender cups were maintained at 7o'°C. 100.0 g of technical propachlor (96.6%) containing 7.5 g of PAPI® was emulsified into 96.6 g of water containing 2.0 g of Reax 88 B®, sodium lignosulfonate using a Uaririg blender operating at high shear. To the emulsion was added 1-5 9.3 g of 35.8% HMDA with concurrent reduction of shear.

Capsules ranging from 1 to 60 microns in diameter, with the majority being 1 to 20 microns, were produced.

EXAMPLE 5 Ingredients Percent Gram "20 Technical butachlor (90%) PAPI© 3 5.8% HMDA Reax 88 Water 50. 8 3. 8 4.7 1.0 39. 7 100.0 7.5 9.3 2.0 77.9 Total 100. 0 196.7 201342 -tq- AC -1288- 100.0 g of technical butachlor (90%) containing 7.5 g of PAPI© (both at room temperature) was emulsified into 152.4 g of H^O containing 2.0 g of Reax 88 SO sodium 1ignosulfonate emulsifier using high shear. To the emulsion was added 9.3 g of 35.8% HMDA with concurrent reduction of shear.

Spherical and irregularly-shaped particles ranging in size of from 1 to 30 microns in diameter, with the majority being 1-20 microns, were observed. •10 Ingredients EXAMPLE 6 Percent Grams Technical alachlor (90%) 49. 4 200. 0 PAPI® 3. 7 .. 0 4 0% HMDA 4. 1' 16. 7 Reax 88 B© 0. 9 3. 8 Water 37. 7 152. 4 Ethylene glycol 4. 2 ' 17. 1 Total 100. 0 405.0 This example was prepared as in Example 2 except that a Ross Model 100L Homogenizer was used and the beaker was placed in an ice bath so that the temperature did not rise above 50°C. ' High shear was continued throughout. Shear was continued for 20 minutes and thereafter 17.1 grams of ethylene glycol was added just prior to bottling. Approximately all particles produced vere less than 45 microns in diameter,- only a trace of material did not pass through a 325 mesh screen (45 micron maximum openings). 2 0 1342 -2.0- EXAKPLE 7 Ingredients Percent Grams Technical alachlor (93%) 45. 5 200 PAPI-135® 3.2 ' 13.9 BHMTA (70%) 3.4 .1 Reax 88 B® " 0.9 4.0 NaCl 9.3 41.0 Water 37 .7 166 .1 Total 100. 0. 44 0.1 200.0 g of technical alachlor containing 13.9 g of ■ • PAPI-135® was emulsified into 166.1 g of water containing 4.0. g- of Reax 88 S® sodium 1 ignosul fonate. All ingredients were maintained at 50°C. The emulsion was formed with a •Waring blender* operated at high shear. . To the emulsion was 15 added 15.1 g of 70% BKMTA with concurrent reduction of shear. After 20 minutes, 41.0 g of sodium chloride was added and the formulation was bottled. The resulting m ic rocapsules. were primarily spherical., with some • irregularly shaped particles, and ranged in size from 1 20 micron to 15 microns in diameter, with the majority of the particles being 1 to 10 microns in diameter.

EXAMPLE 8 Ingredients Percent Grams Technical alachlor (90%) 47. 8 200.0 Mondur MR© 3.6 .0 HMDA (40%) 4. 0 16.7 Re ax 8 8 B2> 0.9 3 ,8 Water 39. 6 165. 4 Ethylene glycol 4.1 17.1 Total 100. 0 418. 0 201342 -a\- Into 165.4 grams of water containing 3.S grams Reex 8 8-5© (both at room temperature) was emulsified 200.0 grams of technical "alachlor (90%) containing 15.0 grains of Mondur MR© at 50°C. The emulsion was formed with a Waring blender operating at high shear. To the emulsion was added 16.7 grams of liMDA (40%) with concurrent reduction of shear to provide gentle stirring. After 20 minutes, ethylene glycol was added. Irregular-shaped particles were 1-20 microns in diameter, with the majority being 1-10 microns in diameter.

EXAMPLE 9 1.5 Ingred ients Technical alachlor (90%) PAPI® HMDA (4 0%') Reax 88 B® Water Ethylene glycol Percent 49. 4 .3.7 4.4 0. 9 " 37. 4 ■ 4. 2 Pounds 100.0 7.5 9.0 1.9 75.5 8.6 Total 100.0 202.5 Into a 55 gallon drum was added 100 pounds of. 20 technical alachlor (90%) at 60°C and into the alachlor was dissolved 7.5 pounds of PAPI© utilizing a Ross Model ME-105 Homogenizer. 75.5 pounds of water containing 1.9 pounds of Reax 88 3© was added to the drum without shear. Thereafter, an emulsion was formed using the Ross Homogenizer to provide 25 shear. To the emulsion was aacea 9.0 pounds of 40% HMDA.

After 20 minutes, 8.6 pounds of ethylene glycol was added and--the formulation was packaged in gallon containers. 2 01342 -XL- I-'ostly spherical particles with some irregular shapes were formed which were 1-60 microns in diameter with the majority being 1-20 microns in diameter.

EXAMPLE 10 Ingredients . Percent G rams Technical alachlor (90%) 46. 8 200. C PAPI -135® 1.6 7.0 HMDA (4 0%) 1.8 7.6 Reax 88 B© 0. 9 3.8 Water 39.6 169.0 Sodium chloride 9.3 . 39.7 Total 10 0.0 427.1 In this example all materials except the sodium chloride and 40%' HjIDA were at 50°C. Into 169.0 grams of 15 water contain-ing. 3.8 grams of Reax-88 B® was emulsified 200 grams of technical alachlor (90%) containing 7.0 grains of PAPI-135® with a Waring blender operating at high shear. To the emulsion was added 7.6 grams of KMDA (40%) with concurrent reduction of-shear sufficient to provide gentle 20 stirring. After 20 minutes, 39.7 grams of sodium chloride was added to balance the density of the aqueous phase with that of the suspended microcapsules. Both spherical snd irregular-shaped microcapsules were produced ranging in size frori 1 to 20 microns in diameter with some particles being up to 80 microns in diameter.

Example 10 was repeated using diethylenetriamine, trietnylenetetraamine, tetraetnylenepentarnine and pentamethylenehexamine singly and in combination with 1,6-hexamethylenediamine. The amine combinations and concentration of each are described in Table I along with the additional water required, if any. 201342 TABLE I 40% 1, 6-Hexamethylenediamine Dietbylenetriamine Water • (grams) (grans) (grains) 16.4 0.1 0 15.8 0.22 0.7 15.0 0.43 1.3 12.5 1.1 " 3.1 8.4 2.2 6.1 . 0 4.3 13.4 Triethylaminetetramine 16.4 0.1 * 0 15.8 ' • 0.24 .7 15.0 - 0.4 8 1.2 12.5 1.2 3 8.4 2.4 5.9 0 4.8 13.9* Tetraethylenepentsinine 16.4' 0.1 0 .8 0.26 0.6 .0 0.52 1.2 12.5 1.3. 2.9 .8.4 2.6 5.7 0 5.2 11.5 Pentanethylenehexamine 16.4 0.1 0 " 15.8 0.28 .7 15.0 ' 0.55 1.2 12.5 1.4 2.S 8.4 2.8 ■ -"5.5 0 5.5 11.2 -llf- 2 01 EXAMPLE 11 The microcapsules of this example were prepared according to the procedure of Example 10, except that the amount of PAPI® and 40% HMDA was varied, to produce from 6% to 30% shell wall content relative to the amount of herbicide 5 encapsulated.

% Shell Wall Content Grams 6 7 8,9 10 11 12 15 20 30 PAPI® 8.3 9.8 11.2 12.5 13.9 15.3 16.7 20.9 27.8 41.7 HHDA 9.1 10.6 12.1 13.6 15.0 16.6 18.2 22.8 30.0 45.3 (40%) H20 166.6 164.0 161.5 159.0 156.7 154.2 151.4 142.8 132.1 125.4 EXAMPLE "12 Ingredients Monochlorobenzene 20 PAPI® HMDA (40%) Reax 88 3® Water.

Percent G rams 52. 2 200.0 3.6 13.9 3.9 .1 1. 0' 4.0 39.3 150.0 Total- 100.0 383.0 This example illustrates the encapsulation of an organic solvent. The order of addition of ingredients was the.same as that described in'Example 1. All steps of this 30 example were carried out at room temperature. A Waring blender was used to provide medium shear which was reduced " to gentle agitation after diamine was added. The particle size of the microcapsules produced, ranged from 1-15 microns in diameter • EXAMPLE 13 I nqredi ents ■ Percent G raras Alach'lor (93%) 33.8 1351.4 Metribuzin (95%) 11.0 44 0.6' PAPI-135®- 3.1 124.6 KrtDA 40% 3.4 135. 3 Reax 38 B® 0. 9 .8 NaCl 11.3 452.7 Water 36.5 1459 .6 Total 100. 0 3975.0 Into 1459.6 g water containing 35.8 g of Reax 38B® sodium 1ignosulfonate emulsifier, was emulsified a solution of 1351.4 g of alachlor, 440.6 g of metribuzin and 124.6 g •of PAPI-135® , all at 50°C. An emulsion was formed with a Folytron PT 1020 and "Premier dispersator in a square vessel.. To- the emulsion was added 13 5.3 g of .40%. HMDA and immediately thereafter Polytron shear was stopped. . After 10 minutes, 452.-7 g of NaCl was dissolved into the suspension which was then Bottled. The particle size of the resulting spherical microcapsules ranged from 1-10 microns in a iameter .

EXAMPLE 14 Ingred i ents Percent G rams Alachlor (93%) 32. 0 1254.4 Linuron (92%) ' 12. 0 46 9. 2 PAPI-135® 3.

I 119. 8 EM DA 40% 3. 3 130.1 Reax 88 B® 0. 9' 34. 5 NaCl 11. 8 460.0 Wa ter 36 . 9 1446 .4 Total 100. 0 3914.4 preparation conditions were identical to Example 12. The resulting microcapsules were spherical and ranged from 1-10 microns in diameter. : 2 0Uu42 EXAMPLE 15 Ing red i ents Percent G rams Parathion (98.5%) 38.3 0.0 PAPI-1355 2.7 13.9 HMDA 40% 2.9 ' .1 Reax 8833 1.7 8.6 NaN03 17.7 91.1 Water 3 6 .2 187.0 Total 100.0 515.7 Into 187.0 g of water con taining S.6 g SS 3® sodium 1ignosulfonate was emulsified 200.0 g. of parathion containing 13.9 g of PAPI-135® dissolved therein; all ingredients we.re at 50°C. An .emulsion was formed in a Waring blender using a Polytron PT 1020 to provide shear. To the emulsion was added 15.1 g of 40% KMDA and Polytron shear was stopped. After 5 minutes 91.1 g of NaK'O^ was dissolved into the suspension using the blender to provide gentle shear. The resulting microcapsules were spherical and ranged from 1-10 microns in diameter.

-It- 2 0134 • ttG-1388 I Example 16 Ingredients Percent Grains 21-t-Butyl-2-chloro-N-methoxymethyl-61-methyl-5 acetanilide (93%) 45.75 304.00 PAPI-135® 3.20 21.22 HMDA (43.26%) 3.20 21.22 Reax 88B® .98 6J50 Water _ 38.77 257.66 • NaCl 8.11 53.92 Total 100.00 664.52 In this example, the temperature of the reaction was maintained at 50°C". 304.0 g of the acetanilide herbicide (93%. technical material) containing 21.22 g of PAPI-135® was 15 emulsified into 257.66 g of water containing 6.50 g of Reax 88B®, sodium 1ignosulfonate, using a Waring blender * operating at medium shear and a Brinkman Polytron PT-10-20-3500 operating at maximum speed. Twenty seconds after the emulsion was formed 21.22 g of HMDA was added 20 concurrently~with elimination of shear. After five minutes 53.92 g of NaCl was added and dissolved with Waring blender shear. Spherical particles ranging from 4 to 10 microns in diameter were produced. The formulation was stable with time. • - Example 17 Ingredients Percent Grams 2-Chloro-N-(ethoxymethyl)-- 6'-ethyl-o-acetotoluidide (95.3%) 44.98 303.00 PAPI-135® 3.14 21.15 HMDA (43.26%) 3.14 21.15 Reax 88B® 0.96 6.48 Water 39.89 268.71 • NaCl 7.88 53.12 Total 100.00 673.61 All reaction conditions were in accordance with Exa-ple 16-except that, all reactants were at room 2013 -%s- temperature. The majority of uniformly spherical microcapsules were 4-10 microns in diameter. The formulation was stable with time.

Example 18 Ingredients , Percent Grams 1-(1-Cyclohexen-l-yl)-3-(2-fluorophenyl)-l- methylurea (95%) 44.03 .304.00 PAPI-135® - 3.07 21.22 HMDA (43.26%). 3.07 21.22 Reax 88B® . 0.94 6.50 Water 39.14 270.24 NaCl *" 9.74 67.24 Total 100.00 690.42 Reaction conditions were in accordance with Example 16. The majority ~of the microcapsules were 4-15 microns in diameter. The formulation was stable with time.

Example 19 -*■ Ingredients Percent Grams 5-Thiazolecarboxylic acid, 2-chloro-4-(trifluoromethyl )-, (phenylmethyl ) ester (98%) 39.08 304.00 PAPI-135® 2.73 ' 21.22 ' HMDA (43.26%) 2.73 21.22 Reax 88B® 0.84 6.50 Water ' 41.49 322.77 NaCl 13. 14 102. 20 Total 100.00 777.91 .

Reaction conditions were in accordance with Example 16, except that the starting materials were at 60°C. The majority of spherical microcapsules were 4-10 microns in diameter. The formulation was stable with time. 1342 ' AG-1200- ' Example 20 Ingredients Percent o£-Chloro-N-(2-methoxy-6-methylphenyl)-N-(1-methyl-ethoxymethyl)acetamide (93%) 51.53 PAPI-135® -3.58 HMDA (40.0%) 3.89 Reax 88B® 1.03 Water ^ 39.00 "NaCl 0.96 Grams 2063.0 143.4 155.8 41.3 1561.2 38. 5 Total 100.00 4003.2 Reaction conditions were in accordance with Example 16, except that a Premier dispersator and a square stainless steel container we're used with the polytron. Spheri-cal microcapsules were' 1-10 microns in size. The formulation was stable with time.

Example 21 Ingredients .. Percent <K-Chloro-N-(ethoxymethyl)-N-[2-methyl-6-(trifluoromethyl) phenyl]-acetamide (92.4%) 42.58 PAPI-135® 2.97 HMDA (4 3.26%) 2.97 Reax 88B® 0.85 ' Water 37.97 NaCl 12.65 Total Grams 266.66 18. 61 18. 61 5.33 237.73 79. 24 100.00 626.18 Reaction conditions were in accordance with Example 16. Spherical microcapsules were 4-10 microns in diameter, formulation was stable with time; The 2 0 4 2 Example 22 Ingredients Percent Grams o<-Chloro-N-methyl-N-[2-methyl-6-(3-methylbutoxy)phenyl]- acetamide (92.5%) 46.83 222.50 PAPI-135® 3.27 15.53 HMDA (43.26%) 3.27 15.53 Reax 88B® 1.00 4.76 Water 39.02 185.40 NaCl 6.60 31.38 Total 100.0 475.10 Reaction conditions were in accordance with Example 16, except that, all reactants were at room temperature.. The majority of Spherical microcapsules were 4-10 microns in diameter. The formulation was stable with time.

Example 23 Ingredients Percent Grams oC-Chloro-N-methyl-N-(2-methyl-6"-propoxyphenyl) acetamide (96.2%) 44.11 225.00 PAPI-135® • 3.08 15.71 HMDA (43.26%) 3.08 15.71 Reax 88B® 0.94 4.81 Water 40.14 204.74 . NaCl 8.65 44.12 Total 100.00 510.09 All' process conditions were in accordance with Example 16. The majority of spherical microcapsules were 4-10 microns in diamter. The formulation was stable with time.

Example 24 Ingredients Percent Grams N- (2-butoxy-6-rnethylphenyl) -e<-chloro-N-methyl)acetamide (92.2%) 47.93 225.00 PAPI-135® 3.35 15.71 HMDA (43.26%) 3.35 15.71 Reax 88B® 1.02 4.81 Water 39.31 184.54 NaCl 5. 04 23.68 Total 100.00 469.45 201342 - AG 1200 Process conditions were in accordance with Example 16, except that all components were at room temperature. The majority of spherical microcapsules were 4-10 microns in diameter. The formulation was stable with 5 t ime.

Example 25 Ingredients Percent Grams Isobutyl ester of (2,4-di-chlorophenoxy)-acetic 10 acid (76.4% acid) 50.96 200.00 PAF*I ® 3.56 13.96 HMDA (43.26%) 3.56 13.96 REAX 88B® ^ 1.09 4.28 Water 29.04 113.96 NaCl ' 10.72 42.06 CaCl- 1.07 4.21 Total 100.00 . 392.43 This is an example of microencapsulation of an organic acid (2,4-D) which can be rendered either water soluble by 20 reaction with- amines or mineral cations, or water insoluble by reaction with organic esters. The formulation was stable with time.

.Example 26 Ingredients Percent Grams Alachlor (-92.4%) .30.22 120.88 Propachlor (95.0%) ,14.70 58.80 PAPI-135® 3. 10 12.40 HMDA (4 3.26%) 3.10 . 12.40 Reax 88B® 1. 00 4.00 Water 38.58 154.32 ' NaCl 9.30 37. 20 Total 100.00 400.00 Process conditions were exactly as in Example 16 except;that, the emulsion was formed using only a Waring blender operated 35 at high shear. After diamine addition shear was reduced. The starting materials were at 60CC. The formulation was stable with time. 20134 AG-12 88- Example 27 Ingredients Percent Alachlor (92.4%) 17.40 Propachlor (95.0%) 28.25 Xylene .6.20 PAPI-135® 3.61 HMDA (43.26%) 3.61 Reax 88B® 1.00 Water 33.73 NaCl 6.20 Total.

All conditions were identical to formulation was stable~with time. solvent odor.

Grams 70.47 114.41 25.11 14.58 14.58 4.05 136.61 25.11 100.00 Example 25. There was Example 28 Ingredients Alachlor (93.0%) PAPI-135® HMDA (43.26%) Reax 88B® Water NaCl CaCl - Percent 45. 30 3.16 ' 3.16 0. 97 38. 49 ' 8.10 0. 81 405.00 The no detectable Grams 200.00 13.95 13. 95 4.28 169.93 35.76 3.58 Total 100.00 441.45 All conditions were identical to Example 16. The formulation was stable with time. 201342 -•3$- ' AG-12 88 EXAMPLE 29 Comparisons of the herbicidal activity of alachlor encapsulated according to the process of this invention versus non-encapsulated alachlor indicate that in general, encapsulated alachlor exhibits comparable herbicidal activity against grass and'broaaleaf weeds. The crop safety of encapsulated alachlor was similar to that of non-encapsulated alachlor with.microencapsulated alachlor exhibiting a greater degree of safety on cotton than the non-encapsulated alachlor.' Table II summarizes the results observed at 6 weeks after application of encapsulated and non-encapsulated alachlor, at three rates of application, in tests done in Brazil according to standard agricultural procedures..

• • • • TABLE II r • • • % Control (Injury) lloubicicle (Kg Act. Ingr./Ha) Soybeans Cotton Peanuts Corn Acanthos. pemium hispidim 2 Gonchrus • echinatus Bidens"^ pilosa Digitaria sangui-nalis 4 . . 5 Brachiaria plantaginae Alachlor 3.36 0 53 0 0 97 75 • 100 100 .0 II .04 0 93 2 0 . 99 95 50 90 43 H 6.72 0 92 3 \ 0 • 93 97 100 ' 99 75 Alachlor -Encapsulated 3.36 0 3 0 50 . . 03 100 90 68 II .04 0 50 0 2 05 . 92 100 90 94 II 6.72 0 7 0 0 99 99 100 100 99 3 -2 Acanthospermum hispiclum: Average infestation 12 plants/m 2 Conchnis echinatus Hidens pilosa: 'nigltaria sanguinalis: >H).*ach.i.a.i:ia planbaglnae: Average infestation 7 plants /m , missing in sane plots 2 Average infestation 6 plants/m , " " " " 2 Average infestation 11 plants/m , " " " " Average infestation <10 plants/m^ . " " " -F"- i N) ,o 2 01342 AC-1288 EXAMPLE 30 Barnyardgrass, rough pigweed, yellow nutsedge, large crabgrass and green foxtail were planted in 9 1/2" x 5 1/2" aluminum pan's. Alachlor* and microencapsulated technical grade alachlor were applied to duplicate pans at various rates. Both'encapsulated and unencapsulated alachlor were applied to the pans using a belt sprayer utilizing water as a carrier. Two weeks after treatment (WAT) visual estimates of percent inhibition were made and recorded. The pans were allowed to dry out ana the surface vegeta'tion was removed. After removing the top 1/2 inch of soil from each pan, the pans were" replanted and covered with their original top 1/2 inch of soilv No additional herbicide was applied. Two wee.ks after this second planting a second reading was taken. The replanting procedure was followed for an additional cycle for rates of 1, 1/2' and 1/4 lb/acre. To improve fertility for the third cycle,' 10 ml of standard nutrient solution was added to each pan. Final observations were made 48 days after initial treatment, i.e., % approximately 7 weeks after treatment. The results are summarized in Table III and indicate that microencapsulated alachlor exhibits longer.soil longevity than does unencapsulated alachlor, where applied at the same rates.

*The alachlor used in this example was a commercially-available emulsifisble concentrate sold by Monsanto Company under the trace name Lasso0" .

TABLE III % Inhibition (WAT)* llo irbi.cicle Lb/A'.' Barn.

Grass R. Pig Weed Y. Nut Sedge L. Crab Grass Gr. Tail Fox 2 4 7 2 4 7 2 4 7 2 4 7 2 4 7 Alachlor 1.0 100 70 0 90 0 50 0 0 100 . 60 0 99 05 0.

II 0.5 100 0 95 0 0 50 0 0 100 0 90 50 0 II 0.25 100 0 0 90 0 0 0 " 0 0 9.9. 0 0 00 a • II 0.125 100 0 80 0 0 0 95 0 75 0 . II 0.0625 100 0 60 0 / 0 0 90 0 70 0 II 0.0312 95 0 60 0 0 0 » 85' 0 ...... 70 0 II 0.0156 80 0 0 0 0 60 0 40 0 II 0.0070 50 0 0 0 0 60 0 0 Alachlor Jf. 11 c a p r, vi .1 a L cd 1.0 100 05 40 90 50 0 40 00 100 0 5 95 95 70 II 0.5 93 7 0 0 05 40 0 99 05 0 95 90 II 0.25 05 65 0 05 0 0 85 75 • 0 00 95 0 II 0.125 90 0 0 0 60 40 40 II 0.0625 0 05 0 0 0 0 II 0.0312 0 . 70 0 0 0 0 0 II .0.0156 0 0 65 0 0 ' 0 . 50 0 0 0 II 0.0070 0 0 40 0 0 0 0 0 0 *Weeks After Treatment -3^- EXAMPLE 31 2^04*6 4 2 The herbicidal activity of microencapsulated and non-encapsulated .triallate.was compared on wild oats and blackgrass weeds in wheat stands at three European locations. The results summarized in Table IV indicate that encapsulated 5 triallate exhibits comparable herbicidal activity as non--encapsulated triallate on wild oats and blackgrass. Encapsulated triallate exhibits as good or better crop safety on whea as does non-encapsulated triallate. In the results summarized in Table IV the aqueous suspension of microencapsulated 10 triallate and the nonencapsulated triallate were applied' by" . spraying according"to' standard agricultural procedures.

TABLE IV % Inhibition (Injury) Herbicide Triallate Sprayed Rate (Kg/ha) 1.5 ' 2.25 Wild Oats - 57 ' 17 23 70. 37 24 • Blackgrass 26 0 40 34 Encapsulated Triallate- Spr.ayed 1.5 2.5 77 77 24 85 85 62 26 22 3S 4 0 In addition to the previously described advantages of the present invention, microencapsulation of herbicides or pesticides may, in general, offer several advantages: over conventional herbicide or pesticide formulations. Thus, for 5 example, microencapsulated herbicide formulations may reduce mammalian toxicity and extend the activity of the herbicide. Where volatility of the herbicide is a problem, microencapsulation can reduce evaporative losses and thus prevent reduction in .herbicide activity associated with such 10 losses. Microencapsulated herbicide formulations may, in some cases, be less phytotoxic to certain crop plants, thereby enhancing the crop safety of the herbicide.-Microencapsulation of herbicides nay also protect the herbicides from environmental degradation, reduce leaching 15 of the herbicide into the soil and prolong or increase the soil life of the herbicide. It can be appreciated that microencapsulated herbicide formulations have several advantages which make such microencapsulated herbicide formulations a desirable and beneficial alternative to 20 conventional herbicide formulations.

Accordingly, one object of the present invention is to provide a herbicidal composition consisting essentially of a suspension in water of microcapsules comprised of a herbicide contained within an encapsulating '25 wall of polyurea. Herbicides of the type previously described are expressly contemplated for use in such compositions, preferably the acetanilide and thiolcarbamate type herbicides and particularly alachlor, butachlor, propachlor and triallate. The concentration of herbicide 30 present in such compositions will be about 480 grams per liter of total composition or greater, preferably from about 4 SO' crams to about 700 grams per liter of total composition and more preferably, from about 4S0 crams to about 6C0 crams per liter of total composition. 2 013 42 _3q,- AG 1280 The encapsulating wall of polyurea is the reaction product of polymethylene polyphenylisocyanate and a polyfunctional amine of the type previously described. The concentration of polymethylene polyphenylisocyanate will 5 range from about 3.5, percent to about 21.0 percent relative to the Weight of herbicide present in the composition and the concentration of polyfunctional amine will range from about 1.5 percent to about 9.0 percent relative to the weight of herbicide present in the composition. 10 Present in the water, in addition to the microcapsules, is a lignin sulfonate emulsifier of the type previously described ^and optionally, formulation ingredients such as. anti-freeze ■'agents , dispersing agents, salts, biocices and the like. The concentration of lignin 15 sulfonate emulsifier may range from 'about 1/2 percent to about 15.0 percent relative to the weight of' herbicide present in the' composition.

It is to be understood that the present invention t is not limited to the specific embodiments shown and 20 described herein, but may be carried out in other ways without departure from its spirit or scope. 201342

Claims (27)

WHAT WE CLAIM IS: 10 15 20 25 16DEC1985:

1. A process of encapsulating water-immiscible material within a shell wall of polyurea which comprises: (a) providing an aqueous phase containing an emulsifier selected from the group consisting of sodium, potassium, magnesium, calcium and ammonium salts of lignin sulfonate;. dispersing in said aqueous phase, a (b) water-immiscible phase consisting V essentially of polymethylene polyphenylisocyanate dissolved in said water-immiscible material, to form a * dispersion of water-immiscible phase droplets throughout the aqueous phase; (c) adding, with agitation, to said •dispersion a polyfunctional amine, whereby said amine reacts with polymethylene polyphenylisocyanate to form a polyurea shell wall about said water-immiscible material; wherein said water-immiscible material is selected from the group consisting of I 27chloro-N-isopropyl acetanil ide, o£-chloro-2' -ethyl-6 ' -methy.l-N- (1-methyl-2-methoxyethyl)acetanilide, -chloro-N-(2-methoxy-6-methylphenyl) -N- (1-me thy le'thoxyme thyl) acetamide, oC-chloro-N-methyl-N- [2-methyl-6- (3-methylbutoxy) phenyl]-acetamide, ©£ -chloro-N-[2-niethyl-6-(2-methyl-propoxy)phenyl]-N-(propoxymethyl)acetamide, N- [ (acetyl-amino )me thyl] - -chloro-N- (2 , 6-diethvlphenyl) . acetamide, oc -chloro-N-methyl-N-(2-methyl-6-propoxy-pheny1)acetamide, N-(2-butoxy-6-methvlphenyl)-cX.-chloro-N—methylacetamide, isobutyl ester of (2,4-dichlorophenoxv)acetic acid, 2-chloro-N- 201342 (ethoxymethyl)-6'-ethyl-j2-acetatoluid-ide, 1-(1-cyclohexen-l-yl)-3-(2-fluorophenyl)-l-methyl urea, c<!-chloro-N-(ethoxymethyl)-N-[2-methyl-6-(trifluoromethyl )phenyl]acetamide, e^-chloro-N-(ethoxymethyl)-N-[2-ethyl-6-(trifluoromethyl)-phenyl]acetamide; ethyl 2-chloro-4-(trifluoromethyl ) -5-thiazolecarboxylate and benzyl 2-chloro-4-(trifluoromethyl)-5-thiazolecarboxylate.

2. A process as described in Claim 1 wherein the concentration of said water-immiscible material is from 480 grams to 700 grams per liter of composition.

3. A process as described in Claim 2 wherein the concentration of polymethylene polyphenylisocyanate is from 3.5% to 21.0% by weight of said water-immiscible material, wherein the concentration of said polyfunctional amine is from • ' 1.5% to 9% by weight of said water-immiscible material and wherein the concentration of said emulsifier is from 1/2% to 15% by weight of said water-immiscible material.

4. A process according to Claim 3 wherein the concentration of said water-immiscible material is from 480 grams to . 600 grams per liter of composition, wherein the concentration of polymethylene polyphenylisocyanate is from 5.0% to' 15.0% by weight of said water-immiscible material, wherein the concentration of said polyfunctional amine is from 2.0% to 7.5% by weight of said water-immiscible 201342 - 42 - material, and wherein the concentration of*said emulsifier is from £.0% to \6.0% by weight of said water-immiscible material.

5. A process as described in Claim 4 wherein the concentration of polymethylene polyphenylisocyanate is j7. 0% relative to the weight of said water-immiscible material, wherein the concentration of said polyfunctional amine is |3.0% relative.to the weight of said water-immiscible material and wherein the-concentration of said emulsifier is j (2.0% relative to the weight of said v^ater-immiscible material.

6. A process as described in any of Claims 1. to 5 wherein said emulsifier is. the sodium salt of lignin sulfonate.

7. A process as described in Claim 6 wherein said amine is 1,6-hexamethylene diamine.

8. A process as described in Claim 1 wherein the temperature of the reaction is maintained above the melting, point of said water-immiscible material but below 80°C.

9. A process as described in Claim 1 wherein the average particle size of the microcapsules is in the range of from 1 micron to 50 microns in diameter..

10. A process as described in Claim 7 wherein said .water-immiscible material is oCrchloro-2'-ethyl-6'-methyl-N-(l-methyl-2-methoxyethyl) acetanilide, o<. -chloro-N- (2-me thoxy-6-methy lphenyl)-N-(1-methylethoxymethyl)acetamide^' << -chloro-N-(ethoxymethyl )-N- [2-methy1-6-(trifluoromethyl)phenyl)]acetamide, cC -chloro-N-(ethoxymethyl)-N-[2^ethyl-6-(tri-fluoromethyl)phenyl]acetamide, and N-[(acetylaminojmethyl]-oC-chloro-N-(2,6-aiethylphenyl) acetamide.

11. A process as described in Claim 10 wherein said water-immiscible material is «^-chloro-N-(ethcxy-methyl)-N-[2-methyl-6-(trifluoromethyl)phenyl]acetamice. - 43 - 2.01342

12. A process as described .in Cl^im 10 wherein said water-immisc ible material is <=?^-chloro-2' -e thyl-6 ' -methyl-N- (1-methy 1-2-me thoxye thyl) acetanilide.

13. A process as described in Claim 10 wherein-said water-immiscible material is N-[(acetylamino)-methyl]- <=< -chloro-N- (2,6-diethylphenyl)acetamide. 201342 -44-

14. A composition consisting essentially of a mixture of water and microcapsules containing a water-immiscible material, said mixture being produced by a process which comprises.the steps of: (a) providing an aqueous phase containing an emulsifier selected from the group consisting of sodium, potassium, magnesium, calcium and ammonium salts of lignin sulfonate; (b) dispersing in said aqueous phase, a water-immiscibl^ phase consisting ' essentially of polymethylene polyphenylisocyanate dissolved in said water-immiscible material, to form a - dispersion of water-immiscible phase droplets throughout the aqueous phase; (c) adding, with agitation, to said dispersion a polyfunctional amine, whereby said amine reacts with polymethylene polyphenylisocyanate to form a polyurea shel-l wall about said water-immiscible material; ■ wherein the concentration of said water-immiscible material is from 480 grams to 600 grams per liter of said composition, wherein the concentration of polymethylene polyphenylisocyanate is from 3.5%' to j15- 0% by weight of said water-immiscible material, wherein the concentration of said polyfunctional amine •is from 1.5% to 9.0% by weight of said water-immiscible material , and wherein the concentration of said emulsifier is from 1/2% to 15% by weight of said water-immiscible material; and wherein said water-'immiscible material "is selected "from the group consisting of 201342 oC -chloro-21-ethyl-6'-methyl-N-(1-methyl-2-methoxyethyl)acetanilide, -chloro-N-(2-methoxy-6-methylphenyl) -N- (1-me thyle thoxymethyl) acetamide, cX -chloro-N-methyl-N--[2-methyl-6- (3-methylbutoxy) phenyl]-acetamide, c<-chloro-N-[2-methy1-6-(2-methyl-propoxy)phenyl] -N-(propoxymethyl)acetamide, N- [ (acetyl-amino) me thyl] - <=<-chloro-N— (2,6-diethylphenyl) acetamide, °<- —chloro-N-methyl-N-(2-methy1-6-propoxy-phenyl)acetamide , N-(2-5utoxy-6-methylphenyl)-c^-chloro-N-methylacetamide, isob-utyl ester of (2,4-dichlorophenoxy)acetic acid, 2-chloro-N-(ethoxymethyl)-6'-ethyl-o-acetatoluidide, 1- (1-cyclohexen-l-yl) -3- (2-f luorophenyl) -1-me thy 1 urea, ©4!-chloro-N- (ethoxymethyl) -N- ['2-methy 1-6- (trif luoromethyl )phenyl] acetamide, -chloro-N-(ethoxymethyl)-N- [2-eth.y 1-6- (trif luoromethyl) -phenyl] acetamide, ,„.1 ethyl 2-chloro-4-(trifluoro-methyl)-5-thiazolecarboxylate and benzyl 2-chloro-4-(trifluoromethyl)-5-thiazolecarboxylate.

15., A composition as described in Claim 14 wherein said polyfunctional amine is 1,6-hexamethylene diamine.

16. A composition as described in Claim 14 wherein said emulsifier is the sodium salt of lignin sulfonate.

17. A'composition as described in Claim 14 wherein the concentration of polymethylene .polyphenylisocyanate is from 5.6% to 13.9% relative to the weightof said water-immiscible — Lv^o 201342 material, wherein the concentration of said polyfunctional amine is from 12.4% to (6-1% relative to the weight of said water-immiscible material, and wherein the concentration of said "' I' emulsifier is from 2.0% to ,6- 0% relative to the weight of said water-immiscible material.

18. A composition as described in Claim^I7/ wherein the concentration of polymethylene polyphenylisocyanate is ,'7.0% relative to the weight of said herbicide, wherein the concentration of said polyfunctional amine is 3.0% relative to the weight, of said herbicide and wherein-the concentration of said emulsifier is 2% relative to the weioht of said herbicide.

19. j A composition as described in Claim wherein the average particle size of the microcapsules is in the range of from . j 1 micron to | |S0 microns in diameter. . .

20. | A process as described in Claim 17 'wherein said wa£er-immiscible material is o -chloro-N-(ethoxymethyl) -N-[2-methyl-6- (trifluoromethyl)phenyl3acetamide." ^ " ' ' • ' 11 /

21.j A process as described in Claim L/ wherein said water-immiscible material is N-[(acetylamino)-methyl]- o -chloro-N- (2 , 6-diethylphenyl)acet.amide. t -47- 201342

22. A composition consisting essentially of a suspension in water of microcapsules comprised of a water-immiscible material contained within an encapsulating vail of polyurea wherein: (a) the concentration of said water-immiscible material is from 4 80 grams to 6 00 grams per liter of total composition; (b) wherein said encapsulating wall of polyurea 'is the reaction product of polymethylene polyphenylisocyanate and a polyfunctional amine, wherein the concentration of polymethylene polyphenylisocyanate is from 3.5% to 21.0% relative to the weight of said water-immiscible material and wherein the concentration of said polyfunctional amine is from 1.5% to 9.0% relative to the weight of said water-immiscible material; (c) wherein said water contains from 1/2% to 6% of an emulsifier relative to the weight of said water immiscible material, said emulsifier being selected from the group consisting of sodium, potassium, magnesium, calcium and ammonium salts of lignin sulfonate; and ^T£^. c • 6D£C/985 - 48 - 201342 wherein said water-immiscible material is selected from the group consisting of «<-chloro-2' ..-^.thyl-6' -methyl-N- (1-methy 1-2-methoxyethyl)acetanilide, <=^ -chloro-N-(2-methoxy-6-methylphenyl)-N-(1-methylethoxymethyl)acetamide, oC -chloro-N-methyl-N- [2-methyl-6-(3-methylbutoxy) phenyl]-acetamide, -chloro-N-[2-methy1-6-(2-methy1-propoxy)phenyl]-N-(propoxymethyl)acetamide, N- [ (acetyl-amino)methyl]- c*C-chloro-N—(2,6-aiethylpheriyl) acetamide, c*- -chrbro-N-methyl-N-(2-methyl-6-propoxy-phenyl)acetamide, N-(2-butoxy-6-methylphenyl)- -oC-chloro-N-methylacetamide, isobutyl ester of (2,4-dichlorophenoxy)acetic acid, 2-chloro-N-(ethoxymethyl)-6'-ethyl-o-acetatoluidide, 1-(1-cyclohexen-l-yl)-3-(2-fluoropheriyl)-l-methyl ureaj -chloro-N-'(ethoxymethyl)-N- 12-me thyl-6.- (trifluoro-~~methyl) phenyl]acetamide, oC-chloro-N-(ethoxymethyl)-_N—[2—ethy1-6-(trifluoromethyl)—phenyl]acetamide, j ]ethyl 2-chloro-4-(trifluoromethyl )-5-thiazolecarboxylate and benzyl 2-chloro-4-(trj.f luoromethyl )-5-thiazolecarboxylate. j

23. A process as described in Claim 22 jwherein sa'id emulsifier is the sodium salt of licnin sulfonate.

24.j A process as described in ClaL-n 23 therein said amine is 1,6-hexamethylene diamine. i

25.j. A process as described in Claim 22 vherein the average particle size .of .said microcapsules is .in the range of from 1 micron to ^50 microns in diameter. 201342 -49-

26. A process as claimed in any one of claims 1 to 13 when performed substantially as hereinbefore described with or without reference to any example thereof.

27. A composition as claimed in any one of claims 14 to 19 substantially as hereinbefore described with reference to any example thereof. By His/Their authorised Agent A. J. PARK & SON Per: