CA1165636A - Encapsulation by interfacial polycondensation of polymethylene polyphenylisocyanate with a poly- functional amine in presence of a lignin sulfonate emulsifier - Google Patents
Encapsulation by interfacial polycondensation of polymethylene polyphenylisocyanate with a poly- functional amine in presence of a lignin sulfonate emulsifierInfo
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- CA1165636A CA1165636A CA000404365A CA404365A CA1165636A CA 1165636 A CA1165636 A CA 1165636A CA 000404365 A CA000404365 A CA 000404365A CA 404365 A CA404365 A CA 404365A CA 1165636 A CA1165636 A CA 1165636A
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Abstract
ENCAPSULATION BY INTERFACIAL POLYCONDENSATION
ABSTRACT OF THE DISCLOSURE
This invention relates to a process for encapsulation, and particularly to the production of small or minute capsules constituted by a skin or thin wall of polyurea, which involves bringing together an aqueous phase containing a lignin sulfonate emulsifier and a water-immiscible phase containing a water-immiscible material, the material to be encapsulated, plus polymethylene polyphenylisocyanate, dispersing the water-immiscible phase in the aqueous phase followed by addition of a polyfunctional amine. Polymethylene polyphenylisocyanate reacts with the amine to form a solid polyurea shell wall about the encapsulated material. The capsules formed may be directly used as aqueous suspensions.
ABSTRACT OF THE DISCLOSURE
This invention relates to a process for encapsulation, and particularly to the production of small or minute capsules constituted by a skin or thin wall of polyurea, which involves bringing together an aqueous phase containing a lignin sulfonate emulsifier and a water-immiscible phase containing a water-immiscible material, the material to be encapsulated, plus polymethylene polyphenylisocyanate, dispersing the water-immiscible phase in the aqueous phase followed by addition of a polyfunctional amine. Polymethylene polyphenylisocyanate reacts with the amine to form a solid polyurea shell wall about the encapsulated material. The capsules formed may be directly used as aqueous suspensions.
Description
B KGROU~D OF THE INVENTION
This invPntion relates 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 yroup consisting of the salts of lignin sulfonate and ~hereaftter adding a polyfunctional amine~
whereby the amine reacts with polymethylene polyphenylisocyanate to form oil-insoluble polyurea microcapsule walls about 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 micxons 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 r meltable solid or sol~ent soluble material in which polymethylene pGlyphenylisocyanate can be dissolved and which is non-reactive with said isoc~anate, may be encapsulated with 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~ r~he process of the invention is particularly suitable for the production of herbicide containing microcapsules of very 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 the~ can be diluted with water or liquid fertilizer and sprayed using '7~
This invPntion relates 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 yroup consisting of the salts of lignin sulfonate and ~hereaftter adding a polyfunctional amine~
whereby the amine reacts with polymethylene polyphenylisocyanate to form oil-insoluble polyurea microcapsule walls about 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 micxons 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 r meltable solid or sol~ent soluble material in which polymethylene pGlyphenylisocyanate can be dissolved and which is non-reactive with said isoc~anate, may be encapsulated with 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~ r~he process of the invention is particularly suitable for the production of herbicide containing microcapsules of very 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 the~ can be diluted with water or liquid fertilizer and sprayed using '7~
- 2 -conventional equipment, thereby producing uniform ield 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 foliage. In some cases, reduced toxicity and extended activity of encapsulated herbicides and pesticides have heen noted.
A variety of techniques have heretofore been used or proposed for encapsulation purposes. In one such process, known as "slmple coacervationl', a polymer separates from a solvent solut~on 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 shell wall material include U.S. Patent Numbers 2,800,458 (Hydrophilic colloids); 3,069,370 and 3,116,216 (polymeric zein); 3,137,631 (denatured proteins); 3,418,250 (hydrophobic thermoplastic resins); and others.
Another method involves microencapsulation based 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 polyphenylisocyanate or toluene diisocyanate monomer into an aqueous phase7 The wall forming reaction is 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 unhydrolyzed isocyanate monomers to orm the polyurea microcapsule wall. One difficulty with this method is the possibility 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 packagedO
Various methods of encapsulation by interfacial
A variety of techniques have heretofore been used or proposed for encapsulation purposes. In one such process, known as "slmple coacervationl', a polymer separates from a solvent solut~on 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 shell wall material include U.S. Patent Numbers 2,800,458 (Hydrophilic colloids); 3,069,370 and 3,116,216 (polymeric zein); 3,137,631 (denatured proteins); 3,418,250 (hydrophobic thermoplastic resins); and others.
Another method involves microencapsulation based 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 polyphenylisocyanate or toluene diisocyanate monomer into an aqueous phase7 The wall forming reaction is 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 unhydrolyzed isocyanate monomers to orm the polyurea microcapsule wall. One difficulty with this method is the possibility 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 packagedO
Various methods of encapsulation by interfacial
- 3 condensation between direct-acting, complimentary reactlons are known. Within these me-thods are reactions for produciny various types of polyn~ers as the capsule walls. Many o~
such reactions to produce the coating substance occur between an amine, which must be of at least difunctional character and a second reactant intermediate, which 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. Fatent No. 3,429,827 and U.SO Patent No.
3,577,515 are illustrative of encapsulation by interfacial condensation.
For example, U.S. Patent No. 3,577,515 describes a con inuous or batch method which requires a first reactant and a second reactant complimentary to the first reactant, with each reactant in separate phases, such that the Eirst and second reactants react at the interface between the droplets to form encapsulated droplets. The process is applicable to a large variety of polycondensation reactions, i.e., to many different pairs of reactants capable of interfacial 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 condensation copolymers. The re~erence describes the ~ormation of a polyurea skin when aiamines 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 diisocyanate, hexamethylene diisocyanate and polymethylene polyphenylisocyanate) are present in the organic/oil phase.
In the practice of U.S. Patent 3,577,515l the liquid w~ich preponderates becomes the continuous phase liquid. That is, in forming oil containing microcapsules, the aqueous liquid would preponderate; when water encapsulated microcapsules are formed, the oil phase would preponderate.
Although a number of methods are available in the art for producing micxoencapsulated pesticide and herbicide formulations there are vaxious disadvantages associated with the prior art methods. The encapsulated materials formed by the in situ interfacial polymerization process of sritish Patent 1,371,179, require post-treatment to prevent continued carbon dio~ide evolution and excessive caking, thereby increasing th~ costs of the finished product. For 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 subjected to great stresses and s-trains which can result in premature rupture of the capsules with concomitant loss of 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 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 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, 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 par-ticular, -the salts oE 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 immiscible 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 adaitional step of separation of the microcapsules from 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 e~posed for short-terms to elevated temperatures.
The present invention is particularly advantageous when employed to encapsulate herbicides. Experiments indicate that conventional oil/water herbicide emulsifiers fail -to produce sufficiently stable emulsions to attain micro-encapsulation of concentrated amounts of herbicide ma-terial and avoiding solidification of -the oil/water mass when amlne is added. Additionally, attempts to encapsulate concentrated amounts of herbicides, for example, four to five pounds per gallon (480 grams to 700 grams per liter~ using traditional interfacial polymerization techni~ues, as for example that disclosed in U.S. Patent No. 3,577,515, have resulted in unsatlsfactory formulatlons because of the problem of excessive herbiclde crystal growth, as well as agglomeration or solidification of the finished suspensions. It is thought that her~icide crystal growth results from either incomplete encapsulation of the herbicidal material or from the passage of small amounts of herblclde through the polymeric shell wall.
The problem is particularly acu-te wi-th the acetanllide herbicides.
Crystal growth is very undesirab]e because once it occurs, the final formulations cannot be used directl~;
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 appara-tus.
It is accordingly a particular object of this invention to provide a process whereby greater than 480 grams of herbicide per liter of total composition is encapsulated in a polyurea shell wall with the 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 tem-peratures without the occurrence of agglomera-tion or solidi-fication of the aqueous capsule Eormulation or excessive herbicide crystal forma-tion.
The lnvention relates to a process of encapsulting a water~immiscible material within a shell wal] of polyurea.
The procedure of the invention involves irst pro~l~ing an aqueous solution containing an emulsifier selected from the group consisting of the salts of lignin sulfonate, for examp~e, the sodlum, potassium, magnesium, calcium or ammonium salts. Particularly effective for use herein, is the sodium salt of lignin sulfona-te. A water-immiscible ~organic) phase, which consists of a water-immiscible material (the material to be encapsulated~ and polymethylene polyphenyl-isocyanate, 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-hexamethylene diamine, is added, with continued a~itation, to the organic/aqueous dispersion. The polyfunctional amine reacts witll polymethylene polyphenyl-isocyana-te to form a capsular polyurea shell about the water-immiscible material.
The water immiscible material referred to herein, 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 herbicidesr e.g., a-chloro-2'-ethyl-6'-methyl-N-(l-methy]~
2-methoxyethyl~acetanilide, 2'-t-butyl-2-chloro-N-methoxy-methyl-6'-methylacetanilide, a-chloro-N-(2-methoxy-6-methyl-phenyl)-N-(l-methylethoxymethyl)acetamide, a-chloro-N-methyl-N-~2-methyl-6-(3-methylbutoxy)phenyl~acetamide, a-chloro-N-[2-methyl-6-(2-methylpropoxy)phenyl~-~J~propoxymethyl)acetamide, N-[(acetylamino~methyl]-a-chloro-N-(2,6-diethylphenyl)acetamide, ~-chloro-N-methyl-N-(2-rnethyl-6-propoxyphenyl)ace-tamide, N-(Z
butoxy-6-methylphenyl)-a-chloro--N-methyl ace-tamide, :isobutyl ester of 2,4-(dichlorophenoxy)acetic acid, 2-chloro~N-(ethoxymethyl)-6'-ethyl-o-acetatoluidide ~commonly known as acetochlor), l~(l-cyclohexen-1-yl)-3--~2-fluorophenyl)-1-methyl urea, 2-chloro-4,6-bis(isopropylamino3-s-triazine (commonly known as propazine); herbicides of the type a-chloro-N-(ethoxymethyl)-N-[2-methyl-6-(trifluoro-methyl)phenyl]acetamide and a-chIoro-N-(ethoxymethyl)-N-[2-ethyl-6-(trifluoromethyl)phenyl~acetamide; herbicidal safeners (antidotes~, e.g.; ethyl 2-chloro-4-(trifluoromethyl)-5-thiazolecarboxylate; benzyl 2-chloro-4-(trifluoromethyl)-5-thiazolecarboxylate are specifically contemplated herein.
gi In the practice o the pre~erred embodiment of the present lnvention~ -the ma-tèrial -to be encapsulated is a herbicide.
The material to be encapsulated utilizing the process of the present invention need not consist of only ane type, but may be a combination of two or more various types of water-immiscible materials. For example, employing an appropriate water-immiscible material, such a combination is an active herbicide with another active herbicide or an active herbicide and an active insecticide. Other water-immiscible materials which may be used in combination with those llsted above include ~-chloro-2',6'-diethyl-N-methoxy-methyl acetanilide (commonly known as alachlor), N-butox~methyl-~-chloro-2',6'-diethylacetanilide (commonly known as butachlor), ~-chloro N-isopropyl acetanilide ~commonly known as propach:Lor), 2'-methyl-6'-ethyl-N-(l-methoxyprop-~ yl)-2~chIoroacetanilide (commonly known as metolachlor~, S-2,3,3-trichloroallyl-diisopropyl thiocarbamate (commonly known as triallate), S-2,3,-dichloroallyl-dii~opropylthiocarbamate (commonly known as diallate), ~,a,~-trifluoro-2,6-dinitro-N,N-dlpropyl-p-toluidine (commonly known as trifluralin~, 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine (commonly known as atrazine), 2-chloro-4,6-bis-(ethylamino~-s-triazine ~commonly known as simazine), 4-amino-6-ll,l-dimethylethyl]-3-(methylthio) 1,2,4-triazin-5(4H) one ~commonly known as metribuzin), N'-(3,4-dichlorophenyl)-N-methoxy-~-methylurea (commonly known as linuron); insecticides, e.g., methyl and ethyl parathion, pyrethrin and pyrethroids (e.g., permethrin and fenvalerate~; and organic solvents, e~g., xylene and monochlorobenzene.
- ~a -Also contemplated is a water-immiscible material to be encapsulated which comprises an active ingredient, such as a herbicide, and in inactive ingredient, such as a solverit or adjuvant.
The water immiscible material containing the dissolved polymethylene polyphenylisocyanate comprises the water-immiscible or organic phase. The water-immiscible material acts as the solvent for polymethylene polyphenyl-isocyanate 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 and polymethylene polyphenyl-isocyanate are added simultaneously to the aqueous phase in a pre-mixed state. That is, the water-in~iscible material and polymethylene polyphenylisocyanate are pre-rnixed to obtain a homogeneous water-immiscible phase before addition to and emulsification in the a~ueous phase.
The concentration of water-irnrniscible material initially present in the water-immiscible phase should be sufficient to provide at least 480 yrams 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-irnmiscible material will result in very thick suspensions of micr0capsules. In general, the concentration of water-immiscible material will range from about 4~0 grams to about 700 gxams per liter of total composition. The preferred range is from about 480 grams 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 cornmercially available polymethylene polyphenylisocyanates: PAPI ~ and PAPI-135 ~ (registered trademarks of the Upjohn Co.) and Mondur-MR ~ (registered trademark of the Mobay Chemical Company).
The poly~unctional amines suitable for use in the present invention are those amines which are capable of reacting with polymethylene polyphenylisocyanate to ~orm a polyurea shell wall. The poly~unctional amlnes 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 ~o]lowing~ ethylenediamine, propylenediamine, isopropylenediamine, hexamethylenediamine, toluenediamine, ethenediamine, triethylenetetraamine, tetraethylenepentamine, pentaethylenehexamine, diethylenetriamine, bis-hexamethylènetriamine and the like. The amines may be used alone or in combination with each o~her, preferably in combination with 1,6-hexamethylenediarnine (HMDA)~
g5~
1, 6-hexamethylenediamine is preferred for use in the process of the present invention.
Polymethylene polyphenylisocyanate and the polyfunctional amine form the shell wall which ultimately encapsulates the water-imrniscible 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, there 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 water-immiscible material.
Preferably, there will be from about 5.6 to about 13.9 percent polymethylene polyphenylisocyanate and from about 2.4 to about 6.1 percent amine and more particularly, 7.0 percent polymethylene polyphenylisocyanate and 3.0 percent amine relative to the weight of the water-immiscible material, present in the reaction. Although an e*cess amount of polyfunctional amine relative to the amount of polymethylene polyphenylisocyanate has been used herein, it should be recognized that a stoichiometric amount of polyfunctional amine may be used without depar~ing 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 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 ~ ~jr~ 7~
present invention, the sodium salt of lignin sulfonace is the preferred emulsifier. Any commercially available emulsifier of the type previously described which does not contain added surfactant, may be conveniently employed and 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 may be mentioned are: Treax ~ , LTS, LTK and LTM, respectively, the potassium, magnesium and sodium salts of lignosulfonate (50% aqueous solutions), Scott Paper Co., Forest Chemical Products; Marasperse CR
and Marasperse CBOS-3 ~, sodium lignosulfonate, American Can Co.; Polyfon O ~, Polyfon~-T ~I Reax 88B ~, Reax 85B ~, sodium salts of lignin sulfonate and Reax C-21 ~ calcium salt of lignin sulfonate, Westvaco Polychemicals.
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 we:ight of the water-immiscible material~ Soaium lignosulfonate 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 dispersability.
The microcapsules of the present invenkion require no additional treatment such as separation from the aqueous li~uid, but may be directly utilized or combined with, e.g., liquid fertilizers, insecticides or the like to form aqueous solutions which may be conveniently applied in agricultural uses. Most often it is most convenient to bottle or can the aqueous suspension containing the encapsulated water-immiscible material, in which case, it may be desirable to add formulation additives to the finished -lZ-aqueous sc)lution of microcapsules. Formulation adclitlves such as thickeners, density balancing agents, ~iocides, surfactants, dispersants, ~yes, salts, anti-freeze agents, anti-corrosion agents and the like can be added to improve stability and ease of application.
Those skilled in the art o~ formulations will recog-nize that the preceding examples of formulation additives are only illustrative and other additives may be advantageously employed in the compositions described herein.
The process of the present invention is capable of satisfactory performance 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 formulations, as, for example, when the aqueous solution o~ fil?ished microcapsule is combined with other herbicldes, pesticides, etc., conven-tional cooperating reagents or additions for adjustment of acidity or alk~linity, or like characteristics, may be used, e.g., such substances as hydrochloric acid, sodium hydroxide, sodium carbonate, sodium bicarbonate and the like.
In the practice of the process of the invention, the tempera~ure should be maintained above the melt~n~ point of the water-immiscible material but below the temperature wherein the polymeric shell wall will begin to h~drolyze excessively. For example, where it is desired to encapsulate a liquid organic solvent the temperature o~ 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 sta-teO In general, the -tempera-ture of the reaction shollld not exceed above about 80C., since the polymeric isocyanate monomer will begin to rapidl~
hydrolyze above this temperature, with resulting loss of ~ormation of shell wall material.
The agitation employed to establish the dispersion of water-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 te.g., blender) can be usefully employed to provide the desired agitation.
The desired condensation reaction at the interface between the water-immiscible phase droplets and the aqueous phase occurs very rapidly and within minutes, the condensation reaction is complete. That is, the ~ormation of the polyurea capsule wall has been completed, thereby encapsulating the water-immiscible material within a skin of polyurea and there exists a useable encapsulated product suspended in an aqueous liquid.
The particle size of the microcapsules will range from about 1 micron up to about 100 microns in diameter. In general, the smaller the particle size the better. From about 1 to about 10 microns is an optimum range. From about 5 to about 50 microns is satisfactory for formulating.
Particle size is controlled by the emulsifier used and the degree of agitation employed. One convenient manner of controlling the size of the microcapsules is by adjusting the speed of agitation employed, which is suppled 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 of agitation is well 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 -:L~I--s~a-ted, no change in particle size of the finished micro-capsules in the aqueous suspending medium was observed with passage of time.
Example 1 Ingreaients Percent Grams 2'-t-Bu-tyl-2-chloro-N-methoxymethyl-6'-methyl-acetanilide (93%) 45.75 304.00 ,' PAPI-135~ 3.20 21.22 HMDA (43.26%) 3.20 21.22 Reax 88B~ .98 6.50 Water 38.77 257.66 NaCl '8.1'1' 53.32 Total 100.00 664.52 In this example, the temperature of -the reaction was 15 maintained at 50C. 304.0 g of the acetanilide herbicide (93% technical material) containing 21.22 g of PAPI-135~ was emulsified in-to 257.66 g o water containing 6.50 g of Reax 8-8B~, sodium lignosulfonate, using a Waring blender operat:iny at medium shear and a ~rinkman Polytron PT-10-20-3500 operatiny 20 at maxlmum speed. Twenty seconds after the emulsion was formed 21.22 g of HMDA was added concurrently with elimina-tion 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 25 formulation was stable with time.
Ex'arnple 2 . .
Ingredi'ents 'P cent Grams 2-Chloro-N-(ethoxymethyl~-6'-ethyl--o-acetotoluidide 30 (95.3%~ - 44.~8 303.00 PAPI-135~ 3~14 21.15 HMDA ~43.26%) 3.14 21.15 Reax 88B~ 0.96 6.48 ~15-Water 39.89 268.71 NaCl 7,88 5~.12_ Total 100.00 673.61 All reaction conditions were in accordance with Example 1 except that all reactants were at room temperature. The majority of uniformly spherical microcapsules were 4-10 microns in diameter. The formulation was stable with time.
Ex'amp'l'e 3 -Ingredients - Percent Grams l-(l-Cyclohexen-l-yl~-3-(2-fluorophenyl)-1-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 1. The majority oE the microcapsules we,re 4-15 microns in diame-ter.
The formulation was stable with time.
F,xample' 4 Ingredients Percent Gr'ams 5-Thiazolecarboxylic acid, 2-chloro-4-(trifluoro- -methyl)-, (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 1'4 10'2.20 Total 100.00 777.91 Reac-tion conditions were in accordarlce with Exarnple 1, except that the starting materials were at 60C. The majority of spherical microcapsules were 4-10 microns in diameter. The formulation was stable with -time.
Exampl'e 5 Ingredients Percent Grams a-Chloro-N-(2-methoxy-6-methylphenyl~-N-(l-methyl-ethoxymethyl)acetamiae ~93%~ 51.53 2063.0 PAPI-135~ 3.58 143.4 HMDA (,40.0%~ 3.89 155.8 Reax 88B~ 1.03 41.3 Water 39.00 1561.2 NaCl ' 0.'96' ' 3~8.5 Total100.00 4003.2 Reaction conditions were in accordance with Example 1, escept that a Premier dispersator and a square stainless steel container were used with the polytron. Spherical - microcapsules were 1-10 microns in size. The formulation was stable with time.
E'_a' p~'e' 6 - Ing'redients Percenk Grams ~-Chloro-N-(ethox~methyl)-N~-[2-methyl-6~(trifluoromethyl) phenyl]-acetamide ~92.4%) 42,58 266.66 PAPI-135~ 2u97 18.61 HMDA C43.26%~ 2.97 1~.61 Reax 88B~ 0.85 5.33 Water 37.97 237.73 3Q NaCl 12.-65 79.24 TotallOO.OQ626.18 -~7-Reaction conditions were in accordance with Example 1.
Spherical microcapsules were 4-10 microns in diarneter, The formulation was stable with time.
Example' 7 Ingredients Percent Grams -~-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 Total100~00 475.10 Reaction conditions were in accordance with Example 1, except that, all reactants were at room temperature. The majority of spherical microcapsules were 4-10 microns in diameter.
The formulation was stable wit'h time.
._ ' Ex'amp'l'e 8 Ingred'ients e cent rams U-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' ' ''4'4.12 To~al100.00 510.09 All process conditions were in accordance with Example 1. The majority of spherical microcapsules were 4-10 microns in diameter. The formulation was stable wi-th time.
S~3~
~ 1 8 -E m~ ~_~, Inyredient_ Percent Grams N-(2-butoxy-6-methylphenyl)-~-chloro-N-methyl aceta-mide (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 Process conditlons were in accordance with Example 1, except that all components were at room temperature. The majority of spherical microcapsules were 4-10 microns in diameter.
The formulation was stable with time.
Exa'mpl'e '10 Ingredients Percent Grams Isobutyl ester of t2,4-di-chlorophenoxy)-acetic acid (76.4% acid) 50.96 200.00 PAPI~ 3.56 13.96 HMDA (,43.26%~ 3.56 13.96 Reax 88B~ 1.09 4~28 Wa-ter 29.04 113.96 NaCl 10.72 42.0~
CaC12 1.07 - 4.21 Total100.00 392.43 This is an example of microencapsulation of an organic acid (2,4-D~ which can be rendered ei,ther water soluble by reaction with amines or mineral cations, or water insoluble by rèaction with organic esters. The formulation was stable with time.
-l9-In addition to the previously described advantages of the present invention, microencapsulation of herb;cides or pesticides may, in general, offer several advantages over conventional herbicide or pesticide formulations. Thus, for example, microencapsulated herbicide formulations may reduce mammalian toxicity and extend the ~ctivit~ of tne herbicide. Where volatility of the herbicide is a prohlem, microencapsulation can reduce evaporative losses and thus prevent reduction in herbicide ac~ivity associated with such losses. Microencapsulated herbicide formulations may, in some cases, be less phytotoxic to certain crop plants, therèby enhancing the crop safety of the herbicide. Microencapsulation of herbicides may also protect the herbicides from environ-mental degradation, reduce leaching of the herbicide into the soil and prolong or increase the soil life oE the herbicide. It can be appreciated that microencapsula-ted herbicide formulations have several advantages which ma]ce such microencapsulated herbicide formulations a desirable and beneficial alternative to 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 wall of polyurea.
Herbicides of -the type previously described are expressly contemplated for use in such compositions. The concentration of herbicide present in such compositions will be about 480 grams per liter of total composition or greater, preferably from about 480 grams to about 700 grams per liter of total composition and more preferably, from about 480 grams to about 600 grams per liter of total composition.
J
~20 ~ he encapsulating wall of polyurea is the react:ion product of polymethylene p~lypherlylisocyanate and a polyfunctional amine o-f the type previously descrihed. The concentration of polymethylene polyphenylisocyanate will range from about 3.5 percent to about 21~0 percent reLative to the weight of herbicide present in the composition and the concentxation o polyfunctional amine will range from about 1.5 percent to about 9.0 percent relative to the weight of the herbicide present in the composition.
Present in the water, in addition to the micro-capsules, is a lignin sulfonate emulsifier of the type previously described and optionally, formulation ingredients such as anti-freeze agents, dispersing agents, salts, biocides and the like. The concentration of lignin sulfonate emul-sifier may range from about 1/2 percent to about 15.0 percent relative to -the weight of herbicide present in the composi-tion.
It is to be understood that the present invention is not limited to the speciEic embodiments shown and des-cribed herein, but may be carried out in other ways withoutdeparture from its spirit or scope.
such reactions to produce the coating substance occur between an amine, which must be of at least difunctional character and a second reactant intermediate, which 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. Fatent No. 3,429,827 and U.SO Patent No.
3,577,515 are illustrative of encapsulation by interfacial condensation.
For example, U.S. Patent No. 3,577,515 describes a con inuous or batch method which requires a first reactant and a second reactant complimentary to the first reactant, with each reactant in separate phases, such that the Eirst and second reactants react at the interface between the droplets to form encapsulated droplets. The process is applicable to a large variety of polycondensation reactions, i.e., to many different pairs of reactants capable of interfacial 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 condensation copolymers. The re~erence describes the ~ormation of a polyurea skin when aiamines 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 diisocyanate, hexamethylene diisocyanate and polymethylene polyphenylisocyanate) are present in the organic/oil phase.
In the practice of U.S. Patent 3,577,515l the liquid w~ich preponderates becomes the continuous phase liquid. That is, in forming oil containing microcapsules, the aqueous liquid would preponderate; when water encapsulated microcapsules are formed, the oil phase would preponderate.
Although a number of methods are available in the art for producing micxoencapsulated pesticide and herbicide formulations there are vaxious disadvantages associated with the prior art methods. The encapsulated materials formed by the in situ interfacial polymerization process of sritish Patent 1,371,179, require post-treatment to prevent continued carbon dio~ide evolution and excessive caking, thereby increasing th~ costs of the finished product. For 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 subjected to great stresses and s-trains which can result in premature rupture of the capsules with concomitant loss of 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 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 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, 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 par-ticular, -the salts oE 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 immiscible 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 adaitional step of separation of the microcapsules from 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 e~posed for short-terms to elevated temperatures.
The present invention is particularly advantageous when employed to encapsulate herbicides. Experiments indicate that conventional oil/water herbicide emulsifiers fail -to produce sufficiently stable emulsions to attain micro-encapsulation of concentrated amounts of herbicide ma-terial and avoiding solidification of -the oil/water mass when amlne is added. Additionally, attempts to encapsulate concentrated amounts of herbicides, for example, four to five pounds per gallon (480 grams to 700 grams per liter~ using traditional interfacial polymerization techni~ues, as for example that disclosed in U.S. Patent No. 3,577,515, have resulted in unsatlsfactory formulatlons because of the problem of excessive herbiclde crystal growth, as well as agglomeration or solidification of the finished suspensions. It is thought that her~icide crystal growth results from either incomplete encapsulation of the herbicidal material or from the passage of small amounts of herblclde through the polymeric shell wall.
The problem is particularly acu-te wi-th the acetanllide herbicides.
Crystal growth is very undesirab]e because once it occurs, the final formulations cannot be used directl~;
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 appara-tus.
It is accordingly a particular object of this invention to provide a process whereby greater than 480 grams of herbicide per liter of total composition is encapsulated in a polyurea shell wall with the 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 tem-peratures without the occurrence of agglomera-tion or solidi-fication of the aqueous capsule Eormulation or excessive herbicide crystal forma-tion.
The lnvention relates to a process of encapsulting a water~immiscible material within a shell wal] of polyurea.
The procedure of the invention involves irst pro~l~ing an aqueous solution containing an emulsifier selected from the group consisting of the salts of lignin sulfonate, for examp~e, the sodlum, potassium, magnesium, calcium or ammonium salts. Particularly effective for use herein, is the sodium salt of lignin sulfona-te. A water-immiscible ~organic) phase, which consists of a water-immiscible material (the material to be encapsulated~ and polymethylene polyphenyl-isocyanate, 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-hexamethylene diamine, is added, with continued a~itation, to the organic/aqueous dispersion. The polyfunctional amine reacts witll polymethylene polyphenyl-isocyana-te to form a capsular polyurea shell about the water-immiscible material.
The water immiscible material referred to herein, 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 herbicidesr e.g., a-chloro-2'-ethyl-6'-methyl-N-(l-methy]~
2-methoxyethyl~acetanilide, 2'-t-butyl-2-chloro-N-methoxy-methyl-6'-methylacetanilide, a-chloro-N-(2-methoxy-6-methyl-phenyl)-N-(l-methylethoxymethyl)acetamide, a-chloro-N-methyl-N-~2-methyl-6-(3-methylbutoxy)phenyl~acetamide, a-chloro-N-[2-methyl-6-(2-methylpropoxy)phenyl~-~J~propoxymethyl)acetamide, N-[(acetylamino~methyl]-a-chloro-N-(2,6-diethylphenyl)acetamide, ~-chloro-N-methyl-N-(2-rnethyl-6-propoxyphenyl)ace-tamide, N-(Z
butoxy-6-methylphenyl)-a-chloro--N-methyl ace-tamide, :isobutyl ester of 2,4-(dichlorophenoxy)acetic acid, 2-chloro~N-(ethoxymethyl)-6'-ethyl-o-acetatoluidide ~commonly known as acetochlor), l~(l-cyclohexen-1-yl)-3--~2-fluorophenyl)-1-methyl urea, 2-chloro-4,6-bis(isopropylamino3-s-triazine (commonly known as propazine); herbicides of the type a-chloro-N-(ethoxymethyl)-N-[2-methyl-6-(trifluoro-methyl)phenyl]acetamide and a-chIoro-N-(ethoxymethyl)-N-[2-ethyl-6-(trifluoromethyl)phenyl~acetamide; herbicidal safeners (antidotes~, e.g.; ethyl 2-chloro-4-(trifluoromethyl)-5-thiazolecarboxylate; benzyl 2-chloro-4-(trifluoromethyl)-5-thiazolecarboxylate are specifically contemplated herein.
gi In the practice o the pre~erred embodiment of the present lnvention~ -the ma-tèrial -to be encapsulated is a herbicide.
The material to be encapsulated utilizing the process of the present invention need not consist of only ane type, but may be a combination of two or more various types of water-immiscible materials. For example, employing an appropriate water-immiscible material, such a combination is an active herbicide with another active herbicide or an active herbicide and an active insecticide. Other water-immiscible materials which may be used in combination with those llsted above include ~-chloro-2',6'-diethyl-N-methoxy-methyl acetanilide (commonly known as alachlor), N-butox~methyl-~-chloro-2',6'-diethylacetanilide (commonly known as butachlor), ~-chloro N-isopropyl acetanilide ~commonly known as propach:Lor), 2'-methyl-6'-ethyl-N-(l-methoxyprop-~ yl)-2~chIoroacetanilide (commonly known as metolachlor~, S-2,3,3-trichloroallyl-diisopropyl thiocarbamate (commonly known as triallate), S-2,3,-dichloroallyl-dii~opropylthiocarbamate (commonly known as diallate), ~,a,~-trifluoro-2,6-dinitro-N,N-dlpropyl-p-toluidine (commonly known as trifluralin~, 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine (commonly known as atrazine), 2-chloro-4,6-bis-(ethylamino~-s-triazine ~commonly known as simazine), 4-amino-6-ll,l-dimethylethyl]-3-(methylthio) 1,2,4-triazin-5(4H) one ~commonly known as metribuzin), N'-(3,4-dichlorophenyl)-N-methoxy-~-methylurea (commonly known as linuron); insecticides, e.g., methyl and ethyl parathion, pyrethrin and pyrethroids (e.g., permethrin and fenvalerate~; and organic solvents, e~g., xylene and monochlorobenzene.
- ~a -Also contemplated is a water-immiscible material to be encapsulated which comprises an active ingredient, such as a herbicide, and in inactive ingredient, such as a solverit or adjuvant.
The water immiscible material containing the dissolved polymethylene polyphenylisocyanate comprises the water-immiscible or organic phase. The water-immiscible material acts as the solvent for polymethylene polyphenyl-isocyanate 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 and polymethylene polyphenyl-isocyanate are added simultaneously to the aqueous phase in a pre-mixed state. That is, the water-in~iscible material and polymethylene polyphenylisocyanate are pre-rnixed to obtain a homogeneous water-immiscible phase before addition to and emulsification in the a~ueous phase.
The concentration of water-irnrniscible material initially present in the water-immiscible phase should be sufficient to provide at least 480 yrams 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-irnmiscible material will result in very thick suspensions of micr0capsules. In general, the concentration of water-immiscible material will range from about 4~0 grams to about 700 gxams per liter of total composition. The preferred range is from about 480 grams 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 cornmercially available polymethylene polyphenylisocyanates: PAPI ~ and PAPI-135 ~ (registered trademarks of the Upjohn Co.) and Mondur-MR ~ (registered trademark of the Mobay Chemical Company).
The poly~unctional amines suitable for use in the present invention are those amines which are capable of reacting with polymethylene polyphenylisocyanate to ~orm a polyurea shell wall. The poly~unctional amlnes 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 ~o]lowing~ ethylenediamine, propylenediamine, isopropylenediamine, hexamethylenediamine, toluenediamine, ethenediamine, triethylenetetraamine, tetraethylenepentamine, pentaethylenehexamine, diethylenetriamine, bis-hexamethylènetriamine and the like. The amines may be used alone or in combination with each o~her, preferably in combination with 1,6-hexamethylenediarnine (HMDA)~
g5~
1, 6-hexamethylenediamine is preferred for use in the process of the present invention.
Polymethylene polyphenylisocyanate and the polyfunctional amine form the shell wall which ultimately encapsulates the water-imrniscible 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, there 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 water-immiscible material.
Preferably, there will be from about 5.6 to about 13.9 percent polymethylene polyphenylisocyanate and from about 2.4 to about 6.1 percent amine and more particularly, 7.0 percent polymethylene polyphenylisocyanate and 3.0 percent amine relative to the weight of the water-immiscible material, present in the reaction. Although an e*cess amount of polyfunctional amine relative to the amount of polymethylene polyphenylisocyanate has been used herein, it should be recognized that a stoichiometric amount of polyfunctional amine may be used without depar~ing 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 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 ~ ~jr~ 7~
present invention, the sodium salt of lignin sulfonace is the preferred emulsifier. Any commercially available emulsifier of the type previously described which does not contain added surfactant, may be conveniently employed and 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 may be mentioned are: Treax ~ , LTS, LTK and LTM, respectively, the potassium, magnesium and sodium salts of lignosulfonate (50% aqueous solutions), Scott Paper Co., Forest Chemical Products; Marasperse CR
and Marasperse CBOS-3 ~, sodium lignosulfonate, American Can Co.; Polyfon O ~, Polyfon~-T ~I Reax 88B ~, Reax 85B ~, sodium salts of lignin sulfonate and Reax C-21 ~ calcium salt of lignin sulfonate, Westvaco Polychemicals.
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 we:ight of the water-immiscible material~ Soaium lignosulfonate 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 dispersability.
The microcapsules of the present invenkion require no additional treatment such as separation from the aqueous li~uid, but may be directly utilized or combined with, e.g., liquid fertilizers, insecticides or the like to form aqueous solutions which may be conveniently applied in agricultural uses. Most often it is most convenient to bottle or can the aqueous suspension containing the encapsulated water-immiscible material, in which case, it may be desirable to add formulation additives to the finished -lZ-aqueous sc)lution of microcapsules. Formulation adclitlves such as thickeners, density balancing agents, ~iocides, surfactants, dispersants, ~yes, salts, anti-freeze agents, anti-corrosion agents and the like can be added to improve stability and ease of application.
Those skilled in the art o~ formulations will recog-nize that the preceding examples of formulation additives are only illustrative and other additives may be advantageously employed in the compositions described herein.
The process of the present invention is capable of satisfactory performance 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 formulations, as, for example, when the aqueous solution o~ fil?ished microcapsule is combined with other herbicldes, pesticides, etc., conven-tional cooperating reagents or additions for adjustment of acidity or alk~linity, or like characteristics, may be used, e.g., such substances as hydrochloric acid, sodium hydroxide, sodium carbonate, sodium bicarbonate and the like.
In the practice of the process of the invention, the tempera~ure should be maintained above the melt~n~ point of the water-immiscible material but below the temperature wherein the polymeric shell wall will begin to h~drolyze excessively. For example, where it is desired to encapsulate a liquid organic solvent the temperature o~ 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 sta-teO In general, the -tempera-ture of the reaction shollld not exceed above about 80C., since the polymeric isocyanate monomer will begin to rapidl~
hydrolyze above this temperature, with resulting loss of ~ormation of shell wall material.
The agitation employed to establish the dispersion of water-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 te.g., blender) can be usefully employed to provide the desired agitation.
The desired condensation reaction at the interface between the water-immiscible phase droplets and the aqueous phase occurs very rapidly and within minutes, the condensation reaction is complete. That is, the ~ormation of the polyurea capsule wall has been completed, thereby encapsulating the water-immiscible material within a skin of polyurea and there exists a useable encapsulated product suspended in an aqueous liquid.
The particle size of the microcapsules will range from about 1 micron up to about 100 microns in diameter. In general, the smaller the particle size the better. From about 1 to about 10 microns is an optimum range. From about 5 to about 50 microns is satisfactory for formulating.
Particle size is controlled by the emulsifier used and the degree of agitation employed. One convenient manner of controlling the size of the microcapsules is by adjusting the speed of agitation employed, which is suppled 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 of agitation is well 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 -:L~I--s~a-ted, no change in particle size of the finished micro-capsules in the aqueous suspending medium was observed with passage of time.
Example 1 Ingreaients Percent Grams 2'-t-Bu-tyl-2-chloro-N-methoxymethyl-6'-methyl-acetanilide (93%) 45.75 304.00 ,' PAPI-135~ 3.20 21.22 HMDA (43.26%) 3.20 21.22 Reax 88B~ .98 6.50 Water 38.77 257.66 NaCl '8.1'1' 53.32 Total 100.00 664.52 In this example, the temperature of -the reaction was 15 maintained at 50C. 304.0 g of the acetanilide herbicide (93% technical material) containing 21.22 g of PAPI-135~ was emulsified in-to 257.66 g o water containing 6.50 g of Reax 8-8B~, sodium lignosulfonate, using a Waring blender operat:iny at medium shear and a ~rinkman Polytron PT-10-20-3500 operatiny 20 at maxlmum speed. Twenty seconds after the emulsion was formed 21.22 g of HMDA was added concurrently with elimina-tion 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 25 formulation was stable with time.
Ex'arnple 2 . .
Ingredi'ents 'P cent Grams 2-Chloro-N-(ethoxymethyl~-6'-ethyl--o-acetotoluidide 30 (95.3%~ - 44.~8 303.00 PAPI-135~ 3~14 21.15 HMDA ~43.26%) 3.14 21.15 Reax 88B~ 0.96 6.48 ~15-Water 39.89 268.71 NaCl 7,88 5~.12_ Total 100.00 673.61 All reaction conditions were in accordance with Example 1 except that all reactants were at room temperature. The majority of uniformly spherical microcapsules were 4-10 microns in diameter. The formulation was stable with time.
Ex'amp'l'e 3 -Ingredients - Percent Grams l-(l-Cyclohexen-l-yl~-3-(2-fluorophenyl)-1-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 1. The majority oE the microcapsules we,re 4-15 microns in diame-ter.
The formulation was stable with time.
F,xample' 4 Ingredients Percent Gr'ams 5-Thiazolecarboxylic acid, 2-chloro-4-(trifluoro- -methyl)-, (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 1'4 10'2.20 Total 100.00 777.91 Reac-tion conditions were in accordarlce with Exarnple 1, except that the starting materials were at 60C. The majority of spherical microcapsules were 4-10 microns in diameter. The formulation was stable with -time.
Exampl'e 5 Ingredients Percent Grams a-Chloro-N-(2-methoxy-6-methylphenyl~-N-(l-methyl-ethoxymethyl)acetamiae ~93%~ 51.53 2063.0 PAPI-135~ 3.58 143.4 HMDA (,40.0%~ 3.89 155.8 Reax 88B~ 1.03 41.3 Water 39.00 1561.2 NaCl ' 0.'96' ' 3~8.5 Total100.00 4003.2 Reaction conditions were in accordance with Example 1, escept that a Premier dispersator and a square stainless steel container were used with the polytron. Spherical - microcapsules were 1-10 microns in size. The formulation was stable with time.
E'_a' p~'e' 6 - Ing'redients Percenk Grams ~-Chloro-N-(ethox~methyl)-N~-[2-methyl-6~(trifluoromethyl) phenyl]-acetamide ~92.4%) 42,58 266.66 PAPI-135~ 2u97 18.61 HMDA C43.26%~ 2.97 1~.61 Reax 88B~ 0.85 5.33 Water 37.97 237.73 3Q NaCl 12.-65 79.24 TotallOO.OQ626.18 -~7-Reaction conditions were in accordance with Example 1.
Spherical microcapsules were 4-10 microns in diarneter, The formulation was stable with time.
Example' 7 Ingredients Percent Grams -~-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 Total100~00 475.10 Reaction conditions were in accordance with Example 1, except that, all reactants were at room temperature. The majority of spherical microcapsules were 4-10 microns in diameter.
The formulation was stable wit'h time.
._ ' Ex'amp'l'e 8 Ingred'ients e cent rams U-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' ' ''4'4.12 To~al100.00 510.09 All process conditions were in accordance with Example 1. The majority of spherical microcapsules were 4-10 microns in diameter. The formulation was stable wi-th time.
S~3~
~ 1 8 -E m~ ~_~, Inyredient_ Percent Grams N-(2-butoxy-6-methylphenyl)-~-chloro-N-methyl aceta-mide (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 Process conditlons were in accordance with Example 1, except that all components were at room temperature. The majority of spherical microcapsules were 4-10 microns in diameter.
The formulation was stable with time.
Exa'mpl'e '10 Ingredients Percent Grams Isobutyl ester of t2,4-di-chlorophenoxy)-acetic acid (76.4% acid) 50.96 200.00 PAPI~ 3.56 13.96 HMDA (,43.26%~ 3.56 13.96 Reax 88B~ 1.09 4~28 Wa-ter 29.04 113.96 NaCl 10.72 42.0~
CaC12 1.07 - 4.21 Total100.00 392.43 This is an example of microencapsulation of an organic acid (2,4-D~ which can be rendered ei,ther water soluble by reaction with amines or mineral cations, or water insoluble by rèaction with organic esters. The formulation was stable with time.
-l9-In addition to the previously described advantages of the present invention, microencapsulation of herb;cides or pesticides may, in general, offer several advantages over conventional herbicide or pesticide formulations. Thus, for example, microencapsulated herbicide formulations may reduce mammalian toxicity and extend the ~ctivit~ of tne herbicide. Where volatility of the herbicide is a prohlem, microencapsulation can reduce evaporative losses and thus prevent reduction in herbicide ac~ivity associated with such losses. Microencapsulated herbicide formulations may, in some cases, be less phytotoxic to certain crop plants, therèby enhancing the crop safety of the herbicide. Microencapsulation of herbicides may also protect the herbicides from environ-mental degradation, reduce leaching of the herbicide into the soil and prolong or increase the soil life oE the herbicide. It can be appreciated that microencapsula-ted herbicide formulations have several advantages which ma]ce such microencapsulated herbicide formulations a desirable and beneficial alternative to 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 wall of polyurea.
Herbicides of -the type previously described are expressly contemplated for use in such compositions. The concentration of herbicide present in such compositions will be about 480 grams per liter of total composition or greater, preferably from about 480 grams to about 700 grams per liter of total composition and more preferably, from about 480 grams to about 600 grams per liter of total composition.
J
~20 ~ he encapsulating wall of polyurea is the react:ion product of polymethylene p~lypherlylisocyanate and a polyfunctional amine o-f the type previously descrihed. The concentration of polymethylene polyphenylisocyanate will range from about 3.5 percent to about 21~0 percent reLative to the weight of herbicide present in the composition and the concentxation o polyfunctional amine will range from about 1.5 percent to about 9.0 percent relative to the weight of the herbicide present in the composition.
Present in the water, in addition to the micro-capsules, is a lignin sulfonate emulsifier of the type previously described and optionally, formulation ingredients such as anti-freeze agents, dispersing agents, salts, biocides and the like. The concentration of lignin sulfonate emul-sifier may range from about 1/2 percent to about 15.0 percent relative to -the weight of herbicide present in the composi-tion.
It is to be understood that the present invention is not limited to the speciEic embodiments shown and des-cribed herein, but may be carried out in other ways withoutdeparture from its spirit or scope.
Claims (33)
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 or ammonium salts of lignin sulfonate;
(b) dispersing in said aqueous phase, a water-immiscible 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 poly-methylene polyphenylisocyanate to form a polyurea shell wall about said water-immiscible material;
wherein said water-immiscible material is selected from -the group consisting of .alpha.-chloro-2'-ethyl-6'-methyl-N-(l-methyl-2-methoxyethyl)acetanilide, 2'-t-butyl-2-chloro-N-methoxy-methyl-6'-methylacetanilide, .alpha.-chloro-N-(2-methoxy-6-methylphenyl)-N-(l-methylethoxymethyl)acetamide, .alpha.-chloro-N-methyl-N-[2-methyl-6-(3-methylbutoxy)phenyl]-acetamide, .alpha.-chloro-N-[2-methyl-6-(2-methylpropoxy)phenyl]-N-(propoxy-methyl)acetamide, N-[(acetylamino)methyl]-.alpha.-chloro-N-(2,6-diethylphenyl)acetamide, .alpha.-chloro-N-methyl-N-(2-methyl-6-propoxyphenyl)acetamide, N-(2-butoxy-6-methylphenyl)-.alpha.-chloro-N-methylacetamide, isobutyl ester of (2,4-dichloro-phenoxy)acetic acid, 2-chloro-N-(ethoxymethyl)-6'-ethyl-o-acetatoluidide, 1-(1-cyclohexen-l-yl)-3-(2-fluorophenyl)-1-methyl urea, 2-chloro-4,6-bis(isopropylamino)-1,3,5-triazine, .alpha.-chloro-N-(ethoxymethyl)-N-[2-ethyl-6-(trifluoromethyl)-phenyl]acetamide, .alpha.-chloro-N-(ethoxymethyl)-N-[2-methyl-6-(trifluoromethyl)-phenyl]acetamide, ethyl 2-chloro-4-(trifluoromethyl)-5-thiazolecarboxylate and benzyl 2-chloro-4-(trifluoromethyl)-5-thiazolecarboxylate;
and wherein the concentration of said water-immiscible material is from about 480 grams to about 700 grams per liter of composition.
(a) providing an aqueous phase containing an emulsifier selected from the group consisting of sodium, potassium, magnesium, calcium or ammonium salts of lignin sulfonate;
(b) dispersing in said aqueous phase, a water-immiscible 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 poly-methylene polyphenylisocyanate to form a polyurea shell wall about said water-immiscible material;
wherein said water-immiscible material is selected from -the group consisting of .alpha.-chloro-2'-ethyl-6'-methyl-N-(l-methyl-2-methoxyethyl)acetanilide, 2'-t-butyl-2-chloro-N-methoxy-methyl-6'-methylacetanilide, .alpha.-chloro-N-(2-methoxy-6-methylphenyl)-N-(l-methylethoxymethyl)acetamide, .alpha.-chloro-N-methyl-N-[2-methyl-6-(3-methylbutoxy)phenyl]-acetamide, .alpha.-chloro-N-[2-methyl-6-(2-methylpropoxy)phenyl]-N-(propoxy-methyl)acetamide, N-[(acetylamino)methyl]-.alpha.-chloro-N-(2,6-diethylphenyl)acetamide, .alpha.-chloro-N-methyl-N-(2-methyl-6-propoxyphenyl)acetamide, N-(2-butoxy-6-methylphenyl)-.alpha.-chloro-N-methylacetamide, isobutyl ester of (2,4-dichloro-phenoxy)acetic acid, 2-chloro-N-(ethoxymethyl)-6'-ethyl-o-acetatoluidide, 1-(1-cyclohexen-l-yl)-3-(2-fluorophenyl)-1-methyl urea, 2-chloro-4,6-bis(isopropylamino)-1,3,5-triazine, .alpha.-chloro-N-(ethoxymethyl)-N-[2-ethyl-6-(trifluoromethyl)-phenyl]acetamide, .alpha.-chloro-N-(ethoxymethyl)-N-[2-methyl-6-(trifluoromethyl)-phenyl]acetamide, ethyl 2-chloro-4-(trifluoromethyl)-5-thiazolecarboxylate and benzyl 2-chloro-4-(trifluoromethyl)-5-thiazolecarboxylate;
and wherein the concentration of said water-immiscible material is from about 480 grams to about 700 grams per liter of composition.
2. A process as described in claim 1 wherein the con-centration of polymethylene polyphenylisocyanate is from about 3.5% to about 21.0% by weight of said water-immiscible material, wherein the concentration of said polyfunctional amine is from about 1.5% to about 9% by weight of said water-immiscible material and wherein the concentration of said emulsifier is from about 1/2% to about 15% by weight of said water-immiscible material.
3. A process according to claim 1 wherein the concen-tration of said water-immiscible material is from about 480 grams to about 600 grams per liter of composition, wherein the concentration of polymethylene polyphenylisocyanate is from about 5.0% to about 15.0% by weight of said water-immiscible material, wherein the concentration of said poly-functional amine is from about 2.0% to about 7.5% by weight of said water-immiscible material, and wherein the concen-tration of said emulsifier is from about 2.0% to about 6.0%
by weight of said water-immiscible material.
by weight of said water-immiscible material.
4. A process as described in claim 3 wherein the concen-tration of polymethylene polyphenylisocyanate is about 7.0%
relative to the weight of said water-immiscible material, wherein the concentration of said polyfunctional amine is about 3.0% relative to the weight of said water-immiscible material and wherein the concentration of said emulsifier is about 2.0% relative to the weight of said water-immiscible material.
relative to the weight of said water-immiscible material, wherein the concentration of said polyfunctional amine is about 3.0% relative to the weight of said water-immiscible material and wherein the concentration of said emulsifier is about 2.0% relative to the weight of said water-immiscible material.
5. A process as described in claim 1, 2 or 3 wherein said emulsifier is the sodium salt of lignin sulfonate.
6. A process as described in claim 4 wherein said emulsifier is the sodium salt of lignin sulfonate.
7. A process as described in claim 1, 2 or 3 wherein said amine is 1,6-hexamethylene diamine and wherein said emulsifier is the sodium salt of lignin sulfonate.
8. A process as described in claim 4 wherein said amine is 1,6-hexamethylene diamine and wherein said emulsifier is the sodium salt of lignin sulfonate.
9. 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 about 80°C.
10. A process as described in claim 1 wherein the average particle size of the microcapsules is in the range of from about 1 micron to about 50 microns in diameter.
11. A process as described in claim 1, 2 or 3 wherein said amine is 1,6-hexamethylene diamine, said emulsifier is the sodium salt of lignin sulfonate and said water-immiscible material is .alpha.-chloro-2'-ethyl-6'-methyl-N-(l-methyl-2-methoxyethyl)acetanilide, .alpha.-chloro-N-(2-methoxy-6-methyl-phenyl)-N-(l-methylethoxymethyl)acetamide, .alpha.-chloro-N-(ethoxy-methyl)-N-[2-methyl-6-(trifluoromethyl)phenyl]acetamide, .alpha.-chloro-N-(ethoxymethyl)-N-[2-ethyl-6-(trifluoromethyl) phenyl]acetamide, and N-[(acetylamino)methyl]-.alpha.-chloro-N-(2,6-diethylphenyl)acetamide.
12. A process as described in claim 4 wherein said amine is 1,6-hexamethylene diamine, said emulsifier is the sodium salt of lignin sulfonate and said water-immiscible material is .alpha.-chloro-2'-ethyl-6'-methyl-N-(l-methyl-2-methoxethyl) acetanilide, .alpha.-chloro-N-(2-methoxy-6-methylphenyl)-N-(l-methylethoxymethyl)acetamide, .alpha.-chloro-N-(ethoxymethyl)-N-[2-methyl-6-(trifluoromethyl)phenyl]acetamide, .alpha.-chloro-N-(ethoxymethyl)-N-[2-ethyl-6-(trifluoromethyl)phenyl]acetamide, and N-[(acetylamino)methyl]-.alpha.-chloro-N-(2,6-diethylphenyl) acetamide.
13. A process as described in claim 1, 2 or 3 wherein said amine is 1,6-hexamethylene diamine, said emulsifier is the sodium salt of lignin sulfonate and said water-immiscible material is .alpha.-chloro-N-(ethoxymethyl)-N-[2-methyl-6-(tri-fluoromethyl)phenyl]acetamide.
14. A process as described in claim 4 wherein said amine is 1,6-hexamethylene diamine, said emulsifier is the sodium salt of lignin sulfonate and said water-immiscible material is .alpha.-chloro-N-(ethoxymethyl)-N-[2-methyl-6-(trifluoromethyl) phenyl]acetamide.
15. A process as described in claim 1, 2 or 3 wherein said amine is 1,6-hexamethylene diamine, said emulsifier is the sodium salt of lignin sulfonate and said water-immiscible material is .alpha.-chloro-2'-ethyl-6'-methyl-N-(1-methyl-2-methoxyethyl)acetanilide.
16. A process as described in claim 4 wherein said amine is 1,6-hexamethylene diamine, said emulsifier is the sodium salt of lignin sulfonate and said water-immiscible material is .alpha.-chloro-2'-ethyl-6'-methyl-N-(l-methyl-2-methoxyethyl) acetanilide.
17. A process as described in claim 1, 2 or 3 wherein said amine is 1,6-hexamethylene diamine, said emulsifier is the sodium salt of lignin sulfonate and said water-immiscible material is N-[(acetylamino)-methyl]-.alpha.-chloro-N-(2,6-diethylphenyl)acetamide.
18. A process as described in claim 4 wherein said amine is 1,6-hexamethylene diamine, said emulsifier is the sodium salt of lignin sulfonate and said water-immiscible material is N-[(acetylamino)-methyl]-.alpha.-chloro-N-(2,6-diethylphenyl) acetamide.
19. A process as described in claim 1, 2 or 3 wherein said amine is 1,6-hexamethylene diamine, said emulsifier is the sodium salt of lignin sulfonate and said water-immiscible material is a mixture of .alpha.-chloro-N-(ethoxymethyl)-N-[2-methyl-6-(trifluoromethyl)phenyl]acetamide and 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine.
20. A process as described in claim 4 wherein said amine is 1,6-hexamethylene diamine, said emulsifier is the sodium salt of lignin sulfonate and said water-immiscible material is a mixture of .alpha.-chloro-N-(ethoxymethyl)-N-[2-methyl-6-(trifluoromethyl)phenyl]acetamide and 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine.
21. A process as described in claim 1 wherein said water-immiscible material is a mixture of at least one material selected from the group defined in claim 1 and at least one material selected from the group consisting of .alpha.-chloro-2',6'-diethyl-N-methoxymethyl acetanilide ("alachlor"), N-butoxy-methyl-.alpha.-chloro-2',6'-diethylacetanilide ("butachlor),.alpha.-chloro-N-isopropyl acetanilide ("propachlor"), 2'-methyl-6'-ethyl-N-(1-methoxyprop-2-yl)-2-chloroacetanilide ("metolachlor"), S-2,3,3-trichloroallyl-diisopropyl thio-carbamate ("triallate"), S-2,3-dichloroallyl-diisopropyl-thiocarbamate ("diallate"), .alpha.,.alpha.,.alpha.-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine ("trifluralin"), 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine ("atrazine"), 2-chloro-4,6-bis(ethylamino)-s-triazine ("simazine"), 4-amino-6-(1,1-dimethylethyl)-3-(methylthiol-1,2,4-triazin-5(4H)one ("metribuzin"), N'-(3,4-dichlorophenyl)-N-methoxy-N-methyl-urea ("linuron"), methyl and ethyl parathion, pyrethrin, insecticides and organic solvents.
22. A composition consisting essentially of a suspension in water of microcapsules comprised of a water-immiscible material contained within an encapsulating wall of polyurea wherein:
(a) the concentration of said water-immiscible material is from about 480 grams to about 700 grams per liter of composition;
(b) wherein said encapsulating wall of polyurea is the reaction product of polymethylene polyphenylisocyanate and a polyfunctional amine wherein the concentration of poly-methylene polyphenylisocyanate is from about 3.5% to about 21.0% relative to the weight of said water-immiscible material and wherein the concentration or said polyfunctional amine is from about 1.5% to about 9.0% relative to the weight of said water-immiscible material;
(c) wherein said water contains from about 1/2%
to about 15% of an emulsifier relative to the weight of said water-immiscible material, said emulsifier being selected from the group consisting of the sodium, potassium, magnesium, calcium or ammonium salts of lignin sulfonate;
and wherein said water-immiscible material is selected from the group consisting of .alpha.-chloro-2'-ethyl-6'-methyl-N-(l-methyl-2-methoxyethyl)acetanilide, 2'-t-butyl-2-chloro-N-methoxymethyl-6'-methylacetanilide, .alpha.-chloro-N-(2-methoxy-6-methylphenyl)-N-(l-methylethoxymethyl)acetamide, .alpha.-chloro-N-methyl-N-[2-methyl-6-(3-methylbutoxy)phenyl]acetamide, .alpha.-chloro-N-[2-methyl-6-(2-methylpropoxy)phenyl]-N-(propoxy-methyl)acetamide, N-[(acetylamino)methyl]-.alpha.-chloro-N-(2,6-diethylphenyl)acetamide, .alpha.-chloro-N-methyl-N-(2-methyl-6-propoxyphenyl)acetamide, N-(2-butoxy-6-methylphenyl)-.alpha.-chloro-N-methylacetamide, isobutyl ester of (2,4 dichlorophenoxy)-acetic acid, 2-chloro-N-(ethoxymethyl)-6'-ethyl-o-acetatoluidide, 1-(l-cyclohexen-1-yl)-3-(2-fluorophenyl)-1-methyl urea, 2-chloro-4,6-bis(isopropylamino)-1,3,5-triazine, .alpha.-chloro-N-(ethoxymethyl)-N-[2-ethyl-6-(-trifluoromethyl)-phenyl]acetamide, .alpha.-chloro-N-(ethoxymethyl)-N-[2-methyl-6-(-trifluoromethyl)-phenyl]acetamide, ethyl 2-chloro-4-(trifluoromethyl)-5-thiazolecarboxylate and benzyl 2-chloro-4-(trifluoromethyl)-5-thiazolecarboxylate.
(a) the concentration of said water-immiscible material is from about 480 grams to about 700 grams per liter of composition;
(b) wherein said encapsulating wall of polyurea is the reaction product of polymethylene polyphenylisocyanate and a polyfunctional amine wherein the concentration of poly-methylene polyphenylisocyanate is from about 3.5% to about 21.0% relative to the weight of said water-immiscible material and wherein the concentration or said polyfunctional amine is from about 1.5% to about 9.0% relative to the weight of said water-immiscible material;
(c) wherein said water contains from about 1/2%
to about 15% of an emulsifier relative to the weight of said water-immiscible material, said emulsifier being selected from the group consisting of the sodium, potassium, magnesium, calcium or ammonium salts of lignin sulfonate;
and wherein said water-immiscible material is selected from the group consisting of .alpha.-chloro-2'-ethyl-6'-methyl-N-(l-methyl-2-methoxyethyl)acetanilide, 2'-t-butyl-2-chloro-N-methoxymethyl-6'-methylacetanilide, .alpha.-chloro-N-(2-methoxy-6-methylphenyl)-N-(l-methylethoxymethyl)acetamide, .alpha.-chloro-N-methyl-N-[2-methyl-6-(3-methylbutoxy)phenyl]acetamide, .alpha.-chloro-N-[2-methyl-6-(2-methylpropoxy)phenyl]-N-(propoxy-methyl)acetamide, N-[(acetylamino)methyl]-.alpha.-chloro-N-(2,6-diethylphenyl)acetamide, .alpha.-chloro-N-methyl-N-(2-methyl-6-propoxyphenyl)acetamide, N-(2-butoxy-6-methylphenyl)-.alpha.-chloro-N-methylacetamide, isobutyl ester of (2,4 dichlorophenoxy)-acetic acid, 2-chloro-N-(ethoxymethyl)-6'-ethyl-o-acetatoluidide, 1-(l-cyclohexen-1-yl)-3-(2-fluorophenyl)-1-methyl urea, 2-chloro-4,6-bis(isopropylamino)-1,3,5-triazine, .alpha.-chloro-N-(ethoxymethyl)-N-[2-ethyl-6-(-trifluoromethyl)-phenyl]acetamide, .alpha.-chloro-N-(ethoxymethyl)-N-[2-methyl-6-(-trifluoromethyl)-phenyl]acetamide, ethyl 2-chloro-4-(trifluoromethyl)-5-thiazolecarboxylate and benzyl 2-chloro-4-(trifluoromethyl)-5-thiazolecarboxylate.
23. A composition as described in claim 22 wherein said polyfunctional amine is 1, 6-hexamethylene diamine.
24. A composition as described in claim 22 wherein said emulsifier is the sodium salt of lignin sulfonate.
25. A composition as described in claim 22 wherein the concentration of polymethylene polyphenylisocyanate is from about 5.6% to about 13.9% relative to the weight of said water-immiscible material, wherein the concentration of said polyfunctional amine is from about 2.4% to about 6.1% relative to the weight of said water-immiscible material, and wherein the concentration of said emulsifier is from about 2.0% to about 6.0% relative to the weight of said water-immiscible material.
26. A composition as described in claim 25 wherein the concentration of polymethylene polyphenylisocyanate is about 7.0% relative to the weight of said water-immiscible material, wherein the concentration of said polyfunctional amine is about 3.0% relative to the weight of said water-immiscible material and wherein the concentration of said emulsifier is about 2% relative to the weight of said water-immiscible material.
27. A composition as described in claim 22 wherein the average particle size of the microcapsules is in the range of from about 1 micron to about 50 microns in diameter.
28. A composition as described in claim 22 wherein the concentration of said water-immiscible material is from about 480 grams to about 600 grams per liter of composition.
29. A composition as described in claim 25 wherein said water-immiscible material is .alpha.-chloro-N-(ethoxymethyl)-N-[2-methyl-6-(trifluoromethyl)phenyl]acetamide.
30. A composition as described in claim 25 wherein said water-immiscible material is N-[(acetylamino)-methyl]-.alpha.-chloro-N-(2,6-diethylphenyl)acetamide.
31. A composition as described in claim 25 wherein said water-immiscible material is a mixture of .alpha.-chloro-N-(ethoxymethyl)-N-[2-methyl-6-(trifluoromethyl)-phenyl]acetamide and 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine.
32. A composition as described in claim 22 wherein said water-immiscible material is .alpha.-chloro-2'-ethyl-6'-methyl-N-(1-methyl-2-methoxyethyl)acetanilide
33. A composition as described in claim 22 wherein said water-immiscible material is a mixture of at least one material selected from the group defined in claim 22 and at least one material selected from the group consisting of .alpha.-chloro-2',6'-diethyl-N-methoxymethyl acetanilide ("alachlor"), N-butoxy-methyl-.alpha.-chloro-2',6'-diethylacetanilide ("butachlor"), .alpha.-chloro-N-isopropyl acetanilide ("propachlor"), 2'-methyl-6'-ethyl-N-(l-methoxyprop-2-yl)-2-chloroacetanilide ("metolachlor"), S-2,3,3-trichloroallyl-diisopropyl thio-carbamate ("triallate"), S-2,3-dichloroallyl-diisopropyl thiocarbamate ("diallate"), .alpha.,.alpha.,.alpha.-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine ("trifluralin"), 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine ("atrazine"), 2-chloro-4,6-bis(ethylamino)-s-triazine ("simazine"), 4-amino-6-(1,1-dimethylethyl)-3-(methyl-thio)-1,2,4-triazin-5(4H)one ("metribuzin"), N'-(3,4-dichlorophenyl)-N-methoxy-N-methyl-urea ("linuron"), methyl and ethyl parathion, pyrethrin, pyrethroids, permethrin, fenvalerate, and organic solvents.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US286,092 | 1981-07-20 | ||
| US06/286,092 US4417916A (en) | 1979-03-26 | 1981-07-22 | Encapsulation by interfacial polycondensation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1165636A true CA1165636A (en) | 1984-04-17 |
Family
ID=23097036
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000404365A Expired CA1165636A (en) | 1981-07-20 | 1982-06-03 | Encapsulation by interfacial polycondensation of polymethylene polyphenylisocyanate with a poly- functional amine in presence of a lignin sulfonate emulsifier |
Country Status (11)
| Country | Link |
|---|---|
| JP (2) | JPS5825319A (en) |
| AU (1) | AU548259B2 (en) |
| CA (1) | CA1165636A (en) |
| DD (1) | DD202393A5 (en) |
| ES (1) | ES514154A0 (en) |
| GR (1) | GR77554B (en) |
| PL (1) | PL237597A1 (en) |
| RO (1) | RO85310B1 (en) |
| YU (1) | YU160982A (en) |
| ZA (1) | ZA825221B (en) |
| ZW (1) | ZW15082A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ATE77916T1 (en) * | 1985-09-13 | 1992-07-15 | Ciba Geigy Ag | PROCESS FOR PRODUCTION OF MICROCAPSULES. |
| TR200100313T2 (en) * | 1998-07-30 | 2001-06-21 | Zeneca Limited | Microcapsules released by acid triggering. |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2413123A1 (en) * | 1977-12-30 | 1979-07-27 | Philagro Sa | INTERFACIAL POLYCONDENSATION ENCAPSULATION PROCESS |
-
1982
- 1982-06-03 CA CA000404365A patent/CA1165636A/en not_active Expired
- 1982-07-20 ES ES514154A patent/ES514154A0/en active Granted
- 1982-07-21 AU AU86248/82A patent/AU548259B2/en not_active Ceased
- 1982-07-21 JP JP57125957A patent/JPS5825319A/en active Granted
- 1982-07-21 RO RO108217A patent/RO85310B1/en unknown
- 1982-07-21 PL PL23759782A patent/PL237597A1/en unknown
- 1982-07-21 ZW ZW15082A patent/ZW15082A1/en unknown
- 1982-07-21 GR GR68818A patent/GR77554B/el unknown
- 1982-07-21 DD DD24183582A patent/DD202393A5/en not_active IP Right Cessation
- 1982-07-21 ZA ZA825221A patent/ZA825221B/en unknown
- 1982-07-22 YU YU160982A patent/YU160982A/en unknown
-
1991
- 1991-03-18 JP JP3052582A patent/JPH04211415A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0485B2 (en) | 1992-01-06 |
| ZA825221B (en) | 1983-07-27 |
| YU160982A (en) | 1985-04-30 |
| RO85310A7 (en) | 1984-09-29 |
| JPH0571608B2 (en) | 1993-10-07 |
| PL237597A1 (en) | 1983-03-14 |
| ES8400880A2 (en) | 1983-11-16 |
| AU548259B2 (en) | 1985-12-05 |
| GR77554B (en) | 1984-09-24 |
| JPS5825319A (en) | 1983-02-15 |
| ZW15082A1 (en) | 1982-10-13 |
| ES514154A0 (en) | 1983-11-16 |
| RO85310B1 (en) | 1984-10-30 |
| AU8624882A (en) | 1983-05-12 |
| JPH04211415A (en) | 1992-08-03 |
| DD202393A5 (en) | 1983-09-14 |
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