JPH04211415A - Composition comprising aqueous suspension of microcapsule containing water-immiscible substance - Google Patents

Abstract

PURPOSE: To provide a new and improved encapsulating compsn. rapidly and effectively obtainable and excluding the necessity for separating an encapsulating substance from a continuous phase liquid.

CONSTITUTION: The compsn. is produced by a method wherein an aq. phase containing an emulsifier selected from a group consisting of sodium, potassium, magnesium, calcium and ammonium lignin sulfonates in specific concn. is prepared (a) and a water immisible phase substantially composed of a specific concn. of polymethylene polyphenylisocyanate dissolved in a water immiscible substance with specific concn. of a specific substance is dispersed in the above mentioned aq. phase to form a dispersion of water immiscible phase small droplets over the whole of the aq. phase (b) and polyfunctional amine is added to the dispersion in specific concn. under stirring to react the above mentioned amine with polymethylene polyphenylisocyanate (C) to form a shell wall of polyurea around the above mentioned water immiscible substance.

COPYRIGHT: (C)1992,JPO

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention is characterized in that water-immiscible substances present in high concentrations per composition are essentially more stable than suspensions of microcapsules in water, which are contained within the encapsulating wall of polyurea. A composition comprising:

The composition of the present invention involves dissolving polymethylene polyphenylisocyanate in a water-immiscible material to be encapsulated, and adding an emulsifier selected from the group consisting of salts of lignin sulfonates to the resulting mixture. containing an aqueous phase and then adding a polyfunctional amine and reacting the amine with the polymethylene polyphenylisocyanate to form an oil/
It can be made by a method of making small or microcapsules containing water-immiscible materials, which involves producing an oil-insoluble polyurea microcapsule wall at the water interface. The capsules can be manufactured to any desired size, for example from 1 micron to 100 microns or more. Preferably, the size of the microcapsules is from about 1 to about 50 mm in diameter.
It is in the range of μ.

Such capsules, containing for example dyes, inks, chemical reagents, pharmaceuticals, fragrances, pesticides, herbicides, and the like, have a variety of uses. Any liquid, oil, which can dissolve the polymethylene polyphenylisocyanate and is non-reactive with said isocyanate.
Meltable solids or solvent soluble substances can be encapsulated. Once encapsulated, the liquid or other form may be released until it is released by some or mechanical means such as breaking, crushing, melting, dissolving or otherwise removing the capsule skin. or stored until release by diffusion occurs under suitable conditions. The compositions of the invention are particularly suitable for the production of herbicides containing microcapsules of very small particle size suspended in an aqueous solution.

0004

BACKGROUND OF THE INVENTION Aqueous dispersions of pesticide and herbicide microcapsules are particularly useful in controlled release pesticide and herbicide formulations. This is because they can be diluted with water or liquid fertilizer and sprayed with conventional equipment, thereby forming a uniform field coverage of the pesticide or herbicide. Additives such as film formers can be added directly to this final formulation to improve the adhesion of the microcapsules to the leaf surface. In some cases, reduced toxicity and extended activity of encapsulated herbicides and pesticides has been observed.

Various packaging techniques have been used or proposed. In one such method, known as "simple coacervation," the polymer is dissolved by the action of a precipitating agent (e.g., a salt or a nonsolvent for the polymer) that reduces the solubility of the polymer in the solvent. Separate the polymer from the solvent solution. Patent documents describing such methods and their shell wall materials include U.S. Pat. No. 2,800,458 (Hydrophilic Colloids); U.S. Pat.
No. 116,216 (polymer zein), No. 3,137,
No. 631 (denatured protein), and No. 3,418,250
No. (Hydrophobic Thermoplastic Resin) Specifications and others.

Other methods include the formation of microcapsules based on in situ interfacial condensation polymerization. British Patent No. 1,
No. 371,179 discloses a process comprising dispersing an organic pesticide phase containing polymethylene polyphenylisocyanate or toluene diisocyanate monomers in an aqueous phase. This wall-forming reaction continues in this batch up to a high temperature point where the isocyanate monomers are hydrolyzed at the interface to form amines, which then react with the non-hydrolyzed isocyanate monomers to form the polyurea microcapsule walls. It is started by heating.

One difficulty with this method is the possibility of continued reaction of the monomers after packaging. If all monomers do not react during manufacture, hydrolysis of isocyanate monomers continues to generate CO2. This results in the development of pressure when the formulation is packaged.

Various methods of encapsulation by interfacial condensation between directly acting complementary reaction components are known. Among these methods are reactions that produce various types of polymers as capsule walls. Many such reactions for the production of coating materials involve the use of an amine, which must be of at least difunctional character, and a second reaction, which for the production of polyurea, is a di- or polyfunctional isocyanate. It is carried out between components and intermediates. The amines primarily used or proposed for these methods are typically exemplified by ethylenediamine having at least two primary amino groups. U.S. Patent Nos. 3,429,827 and 3,577;
The specifications of No. 515 are examples of encapsulation by interfacial condensation.

For example, US Pat. No. 3,577,515 requires a first reactant and a second reactant complementary to the first reactant and each reactant in a separate phase. and in which the first and second reactants react at the interface between the droplets to form encapsulated droplets. This method is applicable to many types of polycondensation reactions, ie, to many different combinations of reaction components that can interfacially condense from their respective phase liquids to produce a solid film at the liquid interface. The resulting capsule skin is made of polyamide, polysulfonamide, polyester, polycarbonate, polyurethane,
It is produced as a mixture of the reactants in one or both phases to produce the polyurea or corresponding condensation copolymer. This reference describes the presence of diamines or polyamines (e.g. ethylene diamine, phenylene diamine, toluene diamine, hexamethylene diamine, etc.) in the aqueous phase and diisocyanates (e.g. toluene diisocyanate, hexamethylene diisocyanate and polymethylene polyisocyanate) in the organic The formation of polyurea skins when present in an oil phase is described. In the practice of US Pat. No. 3,577,515, the primary liquid is a continuous phase liquid. That is, when forming oil-containing microcapsules, an aqueous liquid is predominant, and when water-encapsulated microcapsules are formed, an oil phase is predominant.

Although a number of methods are available in the art for producing microencapsulated pesticide and herbicide formulations, various disadvantages exist with respect to prior art methods. Encapsulation materials produced by the in situ interfacial polymerization method of GB 1,371,179 require post-treatment to prevent continued carbon dioxide evolution and excessive caking, thereby Increases the cost of the product. In many encapsulation methods, it is often necessary to separate the encapsulated material from the molding medium. During this separation process the capsule wall is subjected to large stresses and strains, which can result in premature rupture of the capsule and concomitant loss of encapsulating material. They also lack practical value in various other respects. Various experiments have demonstrated the difficulty of establishing the desired capsules in a free-standing manner and of avoiding the partially formed capsules from agglomerating into a heterogeneous mass of material lacking clear capsule formation. There is. Very low concentrations of the intended product are often obtained relative to the total mixture.

[0011]

SUMMARY OF THE INVENTION The present invention provides a new and improved encapsulation composition that is rapid, effective, and eliminates the need to separate the encapsulation material from the continuous phase liquid. The present invention also eliminates the need to use strong solvents in the organic phase, resulting in savings in energy and packaging and equipment consumption. Furthermore, direct combination of water-based herbicide and pesticide formulations with other water-based pesticides is possible.

0012

A critical feature of the present invention is the use of lignin sulfonate emulsifiers, especially lignin sulfonate salts, for the realization of emulsions in which concentrated amounts of water-immiscible substances are present in the water-immiscible phase. For example, sodium, potassium,
It consists in using magnesium, calcium or ammonium salts. Generally 480 per liter of total composition
g or more of a water-immiscible substance is present. Through the use of certain emulsifiers described herein, it is possible to retain the final microcapsules in the initial aqueous solution, thus eliminating the additional step of separating the microcapsules from the initial aqueous environment. It is. The final microcapsules do not agglomerate and the aqueous capsule body does not solidify upon further long-term storage or short-term exposure to elevated temperatures.

The invention is particularly advantageous when used in the encapsulation of herbicides, especially acetanilide and thiocarbamate herbicides such as alachlor, butachlor, propachlor, trialate, dialate, and the like. Experiments have shown that conventional oil/water herbicide emulsions are sufficient to achieve microencapsulation of concentrated amounts of herbicide material when amines are added and sufficient to exclude solidification of the oil/water mass. It can be seen that it is not possible to produce a stable emulsion. Additionally, concentrated amounts of acetanilide and thiocarbamate, e.g. Attempts to encapsulate system herbicides have resulted in unsatisfactory formulations due to problems with excessive herbicide crystal growth as well as problems with agglomeration or solidification of the final suspension. It was believed that herbicide crystal growth resulted from incomplete encapsulation of the herbicide material or from passage of small amounts of herbicide through the polymer shell wall. This problem is particularly acute with respect to acetanilide herbicides.

Crystal growth is highly undesirable. The reason is that once it occurs, the final formulation cannot be used directly. Rather, the microcapsules must be separated from the aqueous solution and resuspended in water, after which it can be sprayed in conventional agricultural herbicide and fertilizer spray equipment.

Therefore, more than 480 g of acetanilide herbicides, such as alachlor, propachlor, butachlor, etc., and thiocarbamate herbicides, such as trialate, dialate, etc., are encapsulated in the polyurea shell wall in an amount of 480 g per liter of the total composition, with the final It is a particular object of the invention to provide a composition in which the microcapsules are suspended in an initial aqueous solution. Suspended microcapsules can be stored for long periods of time without causing agglomeration or solidification of the aqueous capsule formulation or excessive herbicide crystal growth, and can be exposed to elevated temperatures for short periods of time.

The method for preparing the composition of the present invention encapsulating a water-immiscible substance in a polyurea shell wall first comprises a lignin sulfonate salt selected from the group consisting of sodium, potassium, magnesium, calcium or ammonium salts. and providing an aqueous solution containing an emulsifier. Particularly effective for use herein are the sodium salts of lignin sulfonates. Water immiscible substances (
A water-immiscible (organic) phase consisting of the substance to be encapsulated) and polymethylene polyphenylisocyanate is added to this aqueous phase with stirring to form a dispersion of water-immiscible phase droplets in the aqueous phase. . A polyfunctional amine, preferably 1,6-hexamethylene diamine, is then added to the organic/aqueous dispersion with continuous stirring. This polyfunctional amine reacts with the polymethylene polyphenylisocyanate to form an encapsulated polyurea shell around the water immiscible material.

The water-immiscible material referred to herein is the material to be encapsulated, which is suitably capable of dissolving the polymethylene polyphenylisocyanate and yet being non-reactive with it. All liquids, oils, meltable solids or solvent-soluble substances. Such water-immiscible substances include, for example, herbicides such as α-chloro-2',6'-diethyl-N-methoxymethylacetanilide (commonly known as alachlor), N-(butoxymethyl)-2- Chloro
2',6'-diethylacetanilide (commonly known as butachlor), α-chloro-N-isopropylacetanilide (commonly known as propachlor), 2'-methyl-6'-ethyl-N-(1 -methoxyprop-2-yl)-2-chloroacetanilide (
commonly known as metolachlor), 2'-tertiary
butyl-2-chloro-N-(methoxymethyl-6'-
Methylacetanilide, α-chloro-2'-ethyl-6
'-Methyl-N-(1-methyl-2-methoxyethyl)
Acetanilide, α-chloro-N-(2-methoxy-6
-methylphenyl)-N-(1-methylethoxymethyl)acetamide, α-chloro-N-methyl-N-[2-
Methyl-6-(3-methylbutoxy)phenyl]acetamide, α-chloro-N-[2-methyl-6-(2-methylpropoxy)phenyl]-N-(propoxymethyl)acetamide, N-[(acetylamino ) methyl] −
α-chloro-N-(2,6-diethylphenyl)acetamide, α-chloro-N-methyl-N-(2-methyl-
6-propoxyphenyl)acetamide, N-(2-butoxy-6-methylphenyl)-α-chloro-N-methylacetamide, (2,4-dichlorophenoxy)acetic acid isobutyl ester, 2-chloro-N-(ethoxymethyl) )-6'-ethyl-o-acetatoluidide (commonly known as acetochlor), 1-(1-cyclohexen-1-yl)-3-(2-fluorophenyl)-
1-methylurea, S-2,3,3-trichloroallyl-
Diisopropylthiocarbamate (commonly known as trialate), S-2,3-dichloroallyl-
Diisopropylthiocarbamate (commonly known as dialate), α,α,α-trifluoro-2,
6-dinitro-N,N-dipropyl-p-toluidine (
(commonly known as trifulurin), 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),
2-chloro-4,6-bis(isopropylamino)-S
- triazine (commonly known as propazine)
, 4-amino-6-(1,1-dimethylethyl)-3-
(Methylthio)-1,2,4-triazine-5(4H)
on (commonly known as metribuzin), N'
-(3,4-dichlorophenyl)-N-methoxy-N-
Methylurea (commonly known as linuron), alpha
-chloro-N-(ethoxymethyl)-N-[2-methyl-6-(trifluoromethyl)phenyl]acetamide, and α-chloro-N-(ethoxymethyl)-N-[
2-Ethyl-6-(trifluoromethyl)phenyl]acetamide, insecticides such as methyl and ethyl parathion, pyrethrins and pyrethroids (e.g. permethrin and fenvalerate), herbicide safety agents (antidotes)
For example, ethyl 2-chloro-4-(trifluoromethyl)
-5-triazole carboxylate, benzyl 2-chloro-4-(trifluoromethyl)-5-thiazole carboxylate, and organic solvents such as xylene and are specifically contemplated herein.

In the practice of a preferred embodiment of the invention, the substance to be encapsulated is a herbicide, particularly an acetanilide or thiocarbamate herbicide, and more particularly alachlor, butachlor, propachlor, trialate and dialate herbicides. It is a drug.

[0019] In the present invention, the substance to be encapsulated need not consist of only one type. This can be a combination of two or more different types of water-immiscible substances. Such combinations, for example when using suitable water-immiscible substances, include active herbicides and other active herbicides,
or active herbicides and active insecticides. Also contemplated are water-immiscible materials to be encapsulated, including active ingredients such as herbicides and inert ingredients such as solvents or additives.

The water-immiscible material containing dissolved polymethylene polyphenylisocyanate constitutes the water-immiscible or organic phase. The water-immiscible material acts as a solvent for the polymethylene polyphenylisocyanate, i.e. excluding the use of other water-immiscible organic solvents and providing a concentrated amount of water-immiscible material in the final encapsulation product. Make it possible. The water-immiscible substance and the polymethylene polyphenylisocyanate are simultaneously added in premixed form to the aqueous phase. That is, the water-immiscible material and the polymethylene polyphenylisocyanate are premixed to form a homogeneous water-immiscible phase before being added to the aqueous phase and emulsified.

The concentration of the water-immiscible substance initially present in the water-immiscible phase is at least 480% per liter of aqueous solution.
It should be sufficient to provide g of water immiscible material. However, this is in no way limiting and larger amounts can be used. In practical operation, as will be recognized by those skilled in the art, the use of very high concentrations of water-immiscible materials will result in very thick microcapsule suspensions. Generally, the concentration of water-immiscible substances is from about 480 g per liter of total composition.
It is in the range of about 700g. A preferred range is about 480 grams to about 500 grams per liter of total composition.

The polyisocyanate useful in this invention is polymethylene polyphenylisocyanate. Suitable for use herein are commercially available polymethylene polyphenylisocyanates, including PAPI® and PAPI-135® (Upjohn products) and Mondur MR® (Mobay).・Chemical company products).

Polyfunctional amines suitable for use in the present invention are amines that can react with polymethylene polyphenylisocyanate to form a polyurea shell wall. The polyfunctional amine should itself be water-soluble or in the form of a water-soluble salt. Polyfunctional amines that can be used can be selected from a wide variety of such materials. Suitable examples of polyfunctional amines that can be used in the present invention include, but are by no means limited to, the following: Ethylenediamine, propylenediamine, isopropylenediamine, hexamethylenediamine, toluenediamine, ethenediamine, triethylenetetraamine, tetraethylenepentamine, pentaethylenehexamine, diethylenetriamine, bishexamethylenetriamine, and others. The amines can be used alone or in combination with each other, preferably with 1,6-hexamethylene diamine (HMDA). 1,6-hexamethylene diamine is preferred for use in the method of the invention.

The polymethylene polyphenylisocyanate and the polyfunctional amine ultimately form a shell wall that encapsulates the water-immiscible material. The shell wall content of the capsules produced by this method is from about 5 to about 30% water-immiscible material.
% by weight, preferably 8-20% by weight, and more particularly 10% by weight.

The amounts of polymethylene polyphenylisocyanate and polyfunctional amine used in the present invention are determined by the percent shell wall content produced. Generally, the reaction involves from about 3.5 to about 21.5% by weight relative to the weight of the water-immiscible material.
0% polymethylene polyphenylisocyanate and about 1.5% to about 9.0% amine are present. Preferably from about 5.6 to about 13% relative to the weight of the water immiscible material
．． 9% polymethylene polyphenylisocyanate and about 2.4 to about 6.1% amine, and more specifically 7.0% polymethylene polyphenylisocyanate and 3.0% amine. Although excess amounts of polyfunctional amines relative to the amount of polymethylene polyphenylisocyanate are used herein, stoichiometric amounts of polyfunctional amines may be used without departing from the spirit of the invention. It should be recognized that it can be used.

Emulsifying agents (generally referred to herein as emulsifiers) which are critical for use in the practice of this invention are salts of lignin sulfonates such as the sodium, potassium, magnesium, calcium or ammonium salts. be. In the practice of this invention, the sodium salt of lignin sulfonate is the preferred emulsifier. Commercially available emulsifiers of any of the above types that do not contain added surfactants can be conveniently used, and many are available from McCutcheon's
Detergents and Emulsif
ier's'' (North American version 1978) (MC Publ.
Published by Ishing Co., Ltd.). Examples of commercially available emulsifiers are "Treax®" LT which are potassium, magnesium and sodium salts (50% aqueous solution) of lignosulfonates, respectively.
S, LTK and LTM (Scott Paper products)
, "Marasperse CR registered trademark" and "Marasperse CBOS-3 registered trademark" (sodium lignosulfonate, American Cannon Company product), "Polyfon O registered trademark",
"Polyphone T registered trademark", "Reax 8"
8B registered trademark", "Reax 85B registered trademark" lignin sulfonate sodium salt, and "Reax C-21 registered trademark" lignin sulfonate calcium salt (product of Westvaco Polychemicals).

The emulsifier concentration range found to be best accepted in the system is about 1% by weight of the water-immiscible material.
/2 to about 15%, and preferably from about 2 to about 6%. Sodium lignosulfonate emulsifier is preferentially used at a concentration of 2% relative to the weight of the water-immiscible substance. Higher emulsifier concentrations can be used but do not provide greater ease of dispersion.

The microcapsules of the invention require no further processing, eg separation from the aqueous liquid. This can be used directly or combined with, for example, liquid fertilizers, pesticides, etc. to produce aqueous solutions that can be conveniently applied for agricultural use. Most often, it is most convenient to package the aqueous suspension containing the encapsulated water-immiscible material in a bottle or can. In that case, it may be desirable to add formulation additives to the final aqueous solution of the microcapsules. Adding formulation additives such as thickeners, density modifiers, biocides, surfactants, dispersants, dyes, salts, antifreezes, corrosion inhibitors, etc. to improve stability and ease of application. I can do it.

[0029] The formulator will recognize that the foregoing formulation additives are exemplary only and that other additives may be advantageously used in the compositions described herein.

The present invention makes it possible to provide satisfactory performance and production of encapsulation materials without adjustment to a specific pH. That is, there is no need to adjust the pH of the system during the encapsulation process. If it is desired to adjust the pH of the final microcapsule formulation, such as when combining the final microcapsule aqueous solution with other herbicides, pesticides, etc., acidity or alkalinity or other Customary cooperative reagents or additives for adjusting the properties can be used, such as substances such as hydrochloric acid, sodium hydroxide, sodium carbonate, sodium bicarbonate, and the like.

In preparing the compositions of this invention, the temperature should be maintained above the melting point of the water-immiscible material, but below the temperature at which the polymer shell begins to over-hydrolyze. For example, if it is desired to encapsulate a liquid organic solvent, the temperature of the process can be maintained at room temperature. If encapsulation of a solid herbicide is desired, it is necessary to heat the herbicide to its molten state. For example, alachlor herbicide melts at 39.5-41.5°C. Therefore, the process temperature should be maintained above about 41.5°C. Generally the reaction temperature should not exceed about 80°C. This is because above this temperature the polymeric isocyanate monomer begins to rapidly hydrolyze resulting in loss of shell wall material.

The agitation used to establish the dispersion of the water-immiscible phase droplets in the aqueous phase can be provided by any means capable of imparting suitably high shear. Thus, any variable shear mixing device (eg, a blender) can be advantageously used to provide the desired agitation.

The desired condensation reaction at the interface of the water-immiscible phase droplets and the aqueous phase occurs very quickly and is complete within a few minutes. That is, the formation of the polyurea capsule wall is complete, thereby completing the encapsulation of the water-immiscible material within the polyurea skin, and there is a usable encapsulated product suspended in an aqueous liquid.

[0034] The particle size of microcapsules is approximately 1 μm in diameter.
~100μ. Generally the smaller the particle size the better. About 1 to about 10 microns is an optimal range. About 5 to about 50 microns is satisfactory for formulation.

Particle size is controlled by the emulsifier used and the degree of agitation used. One convenient method of controlling the size of the microcapsules is to adjust the stirring speed used to form a dispersion of water-immiscible phase droplets in the aqueous phase. The higher the stirring speed at this stage, the smaller the capsules obtained. Control of capsule size by adjusting the stirring speed is within the skill of those skilled in the art.

The invention is further illustrated by the following examples, which are intended to be illustrative and not of a limiting nature, and unless otherwise stated, the final microcapsules in an aqueous suspension medium. No particle size change was observed over time.

Example 1

[Table 1]

4.0 g of 200 g of industrial chemical grade trialate containing 13.9 g of PAPI-135 registered trademark
was emulsified in 141.3 g of water containing Reax 88B® sodium lignosulfonate. Industrial chemical grade trialate and PAPI-135 registered trademark at 50°C
was held in. The aqueous solution containing the sodium lignosulfonate emulsifier was at 50°C. The emulsion was made using a Waring blender operated at high shear. 15.1 g of 40% HMDA was added to this emulsion to simultaneously reduce 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 contained 500 g of encapsulated technical grade trialate per liter of aqueous solution.

Example 2

[Table 2]

200 g of technical grade alachlor, held at 50° C., containing 15.0 g of PAPI® was poured into 168.0 g of water containing 3.8 g of Reax 88B® sodium lignosulfonate emulsifier. The emulsion was prepared using a Brinkmann polytron (Brink) at high shear.
(man Polytron) homogenizer in a rectangular beaker (temperature in the beaker increased to 60°C as a result of the shear rate). 20.0 g of 35% HMDA was added to the emulsion while the shear was reduced to low speed. The resulting formulation contained 527 g of encapsulated technical grade alachlor per liter of aqueous solution. The resulting microcapsules had a particle size of 1-10 microns in diameter. Approximately 20% of the liquid phase formed over time but was resuspended by gentle shaking.

Example 3

[Table 3]

200.0 g of technical grade alachlor containing 15.0 g of PAPI® was emulsified in 155.9 g of water containing 3.8 g of Reax 88B® sodium lignosulfonate. Technical alachlor and PAPI® were held at 50°C. The aqueous solution containing the sodium lignosulfonate emulsifier was at room temperature. The emulsions were made using a work ring blender operated at high shear. This emulsion contains 16
．． 5g of 40% HMDA was added and the shear was lowered at the same time. After 20 minutes, the ethylene glycol was added and the formulation was bottled. Sedimentation occurred over time, but upon gentle shaking the settled layer was completely resuspended. When this formulation was passed through a 325 mesh screen (45μ aperture), only trace amounts of material larger than 45μ were observed.

The procedure of Example 3 was repeated using various lignin sulfonate emulsifiers in place of Reax 88®. These lignin sulfonate emulsifiers are Reax 85A®, Reax C-21®, Malasperse CB®, Polyphone H®, Polyphone O®, Polyphone T®, Reax 84A and Malasperse CBOS-3®.

Example 4

[Table 4]

All starting materials and Waring blender cups were held at 70°C. 7.5g PAPI
100.0 g of industrial grade propachlor (96.6%) containing a registered trademark was mixed with 2.0 g of water containing 96.6% of Reax 88B registered trademark sodium lignosulfonate.
Emulsification was performed using a Waring blender operated at high shear during g. This emulsion contains 9.3 g of 35.8% HM.
DA was added and the shear was lowered at the same time. Diameter 1~
Capsules in the 60μ range and mostly 1-20μ were produced.

Example 5

[Table 5]

1 containing 7.5g of PAPI registered trademark
00.0 g technical grade butachlor (90%) (both at room temperature) 152.4 g H2O containing 2.0 g Reax 88B® sodium lignosulfonate
During emulsification using high shear. 9.3g in this emulsion
of 35.8% HMDA was added and the shear was lowered at the same time. Spherical and irregularly shaped particles were observed in the size range 1-30μ in diameter and mostly 1-20μ.

Example 6

[Table 6]

This example uses a Ross model 100L homogenizer and is similar to Example 2 except that the beaker is placed in an ice bath to prevent its temperature from rising above 50°C.
Manufactured as in. High shear continued throughout. Shearing was continued for 20 minutes and then 17.1 g of ethylene glycol was added just before bottling. Almost all particles produced were less than 45μ in diameter. Only trace amounts of material did not pass through the 325 mesh screen (45μ maximum aperture).

Example 7

[Table 7]

4.0 g of industrial grade alachlor containing 13.9 g of PAPI-135 registered trademark
g of Reax 88B® sodium lignosulfonate was emulsified in 166.1 g of water. All components were held at 50°C. The emulsion was made using a Waring blender operated at high shear. 15.1 g of 70% BHMTA was added to the emulsion and simultaneously lowered the shear. After 20 minutes, sodium chloride was added and the formulation was bottled. The resulting microcapsules were primarily spherical particles with some irregularly shaped particles and ranged in size from 1 to 15 microns in diameter. The majority of particles were 1-10 microns in diameter.

Example 8

[Table 8]

200.0 g of industrial grade alachlor (containing 13.0 g of Mondoul MR registered trademark) at 50°C.
90%) and 165.4 g water containing 3.8 g Reax 88B® sodium lignosulfonate (
Both were emulsified in room temperature). The emulsion was made using a Waring blender operated at high shear. 16.7 g of HMDA (40%) was added to the emulsion and the shear was simultaneously reduced to provide gentle agitation. Ethylene glycol was added after 20 minutes. Irregularly shaped particles have a diameter of 1
~20μ, and the majority were 1-10μ in diameter.

Example 9

[Table 9]

Add 100 pounds of technical grade alachlor (90%) to a 55 gallon drum at 60° C. and dissolve 7.5 pounds of PAPI® in the alachlor using a Ross model ME-105 homogenizer. I let it happen. 75.5 pounds of water containing 1.9 pounds of Reax 88B® was added to the drum without shear. An emulsion was then produced using a loss homogenizer to impart shear. This emulsion contains 40% of 9.0 lbs.
HMDA was added. After 20 minutes, 8.6 pounds of ethylene glycol was added and the formulation was filled into gallon containers. Predominantly spherical particles were formed with some irregular shape. These were 1-60μ in diameter and the majority were 1-20μ in diameter.

Example 10

[Table 10]

In this example, sodium chloride and 40
All materials except %HMDA were at 50°C. 7.
200g industrial grade alachlor (90%) containing 0g PAPI-135® 3.8g Reax 8
8B® sodium lignosulfonate was emulsified in 169.0 g of water using a Waring blender operated at high shear. This emulsion contains 7.6 g of H
MDA (40%) was added and the shear was simultaneously reduced to provide gentle agitation. After 20 minutes, 39.7 g of sodium chloride was added to balance the density of the aqueous phase to that of the suspended microcapsules. Both spherical and irregularly shaped microcapsules ranging in size from 1 to 20 microns in diameter were produced. Some particles were 80μ in diameter.

Example 10 was repeated using diethylenetriamine, triethylenetetramine, tetraethylenepentamine and pentamethylenehexamine alone and in combination with 1,6-hexamethylenediamine. The combinations of amines and their respective concentrations are listed in Table 1 along with the amount of additional water if required.

[Table 11]

Example 11 The microcapsules of this example contain 6 to 60% of the herbicide encapsulated.
Example 1 except varying the amounts of PAPI® and 40% HMDA to produce a shell wall content of 30%
Manufactured by method 0.

[Table 12]

Example 12

[Table 13]

This example illustrates the encapsulation of organic solvents. The order of addition of ingredients was the same as described in Example 1. All steps in this example were performed at room temperature. A Waring blender was used to provide moderate shear, which was reduced to gentle agitation after diamine addition. The particle size of the microcapsules produced ranged from 1 to 15μ in diameter.

Example 13

[Table 14]

Water 1459 containing 35.8 g of Reax 88B® Sodium Lignosulfonate Emulsifier
．． In 6g, 1351.4g alachlor, 440.6
g of metributin and 124.6 g of PAPI-13
All 5 registered trademark solutions were emulsified at 50°C. Emulsions were produced using a Polytron PT1020 and Premier disperser in a square vessel. This emulsion contains 135.
3 g of 40% HMDA was added and the polytron shear was stopped immediately thereafter. After 10 minutes, 452.7g of NaC
1 was dissolved in this suspension, which was then placed in a bottle. The particle size of the obtained spherical microcapsules is 1 to 1 in diameter.
It was in the range of 0μ.

Example 14

[Table 15]

The manufacturing conditions were the same as in Example 12. The resulting microcapsules were spherical and ranged in diameter from 1 to 10 microns.

Example 15

[Table 16]

200.0 g of Parathion containing 13.9 g of PAPI-135® dissolved therein was emulsified in 187.0 g of water containing 8.6 g of Reax 88B® sodium lignosulfonate. All ingredients were at 50°C. Emulsions were produced in a Waring blender using a Polytron PT1020 providing shear. Add 15.1 g of 40% HMDA to this emulsion.
was added and the polytron shear was stopped. After 5 minutes, 91.1 g of NaNO3 was dissolved into this suspension using a blender with gentle shear. The resulting microcapsules were spherical and ranged in diameter from 1 to 10 microns.

Example 16

[Table 17]

In this example, the reaction temperature was maintained at 50°C. Acetanilide herbicide (93%, industrial grade) containing 21.22g PAPI-135® 30
Waring blender operating 4.0 g at moderate shear and Brinkmann Polytron PT operating at maximum speed.
-10-20-3500 was used to emulsify 6.50 g of Reax 88B® sodium lignosulfonate in 257.66 g of water. 20 days after emulsion formation
After 21.22 g of HMDA at the same time as shear removal
added. After 5 minutes, 53.92 g of NaCl was added and dissolved using Waring blender shear. Spherical particles ranging from 4 to 10 microns in diameter were produced. This formulation was stable over time.

Example 17

[Table 18]

Reaction conditions were as in Example 16 except that all reaction components were at room temperature. Most of the uniformly spherical microcapsules were 1-4μ in diameter. This formulation was stable over time.

Example 18

[Table 19]

The reaction conditions were as in Example 16. Most of the microcapsules were 4-15μ in diameter. This formulation was stable over time.

Example 19

[Table 20]

The reaction conditions were as in Example 16 except that the starting materials were at 60°C. Most of the spherical microcapsules were 4-10μ in diameter. This formulation was stable over time.

Example 20

[Table 21]

Reaction conditions were as in Example 16 except that a Premier disperser and a square stainless steel vessel were used with a Polytron. The size of the spherical microcapsules was 1-10μ. This formulation was stable over time.

Example 21

[Table 22]

The reaction conditions were as in Example 16. The spherical microcapsules were 4-10μ in diameter. This formulation was stable over time.

Example 22

[Table 23]

Reaction conditions were as in Example 16 except that all reaction components were at room temperature. Most of the spherical microcapsules were 4-10μ in diameter. The formulation was stable over time.

Example 23

[Table 24]

All process conditions were as per Example 16. Most of the spherical microcapsules were 4-10μ in diameter. This formulation was stable over time.

Example 24

[Table 25]

Process conditions were as in Example 16, but all ingredients were at room temperature. Most of the spherical microcapsules were 4-10μ in diameter. This formulation was stable over time.

Example 25

[Table 26]

This is an example of a microcapsule of an organic acid (2,4-D) that can be made water-soluble by reaction with an amine or mineral acid cation or water-insoluble by reaction with an organic ester. This formulation was stable over time.

Example 26

[Table 27]

The process conditions were the same as in Example 16 except that this emulsion was made using only a Waring blender operated at higher speed. After addition of the diamine, the shear reduced starting material was at 60°C. This formulation was stable over time.

Example 27

[Table 28]

All conditions were the same as in Example 25. This formulation was stable over time. No solvent odor was detectable.

Example 28

[Table 29]

All conditions were the same as in Example 16. This formulation was stable over time.

Example 29 Comparing the herbicidal activity of encapsulated alachlor of the present invention to unencapsulated alachlor, encapsulated alachlor generally exhibits comparable herbicidal activity against monocotyledonous and broadleaf weeds. The crop safety of encapsulated alachlor was similar to that of unencapsulated alachlor. Microencapsulated alachlor showed greater safety against radiation than non-encapsulated alachlor. Table 2 summarizes the results observed six weeks after application of encapsulated and unencapsulated alachlor in a trial conducted in Brazil with standard agricultural practices at three application rates.

[Table 30]

EXAMPLE 30 A 91/2" x 51/2" aluminum pan was planted with silver millet, blueberry, blackberry, blackberry, and foxtail. Alachlor and microencapsulated technical grade alachlor were applied to two pans each in various proportions. Encapsulated alachlor and unencapsulated alachlor are
Both were applied to the pan using a belt sprayer with water as the carrier. A visual estimation of % inhibition was performed and recorded two weeks after treatment (2WAT). The bread was dried and the surface vegetation removed. 1/2 surface from each bread
After removing the 2 inches of soil, the pans were replanted and covered with the first top 1/2 inch of soil. No further herbicide was applied. 2 of this second planting
A second reading was performed a week later. This re-implantation operation 1.
One additional cycle was run for the 1/2 and 1/4 pound/acre rates. For the third cycle, 10 ml of standard nutrient solution was added to each loaf to improve fertility. The final observation was made 48 days after the first treatment, or approximately 7 weeks after treatment. The results are summarized in Table 3. This indicates that microencapsulated alachlor has a longer pot life than non-encapsulated alachlor when given the same ratio. The alachlor used in this example was a commercially available emulsifying concentrate sold by Monsanto under the trade name "Lasso®".

[Table 31]

Example 31 The herbicide activity of microencapsulated trialate and non-encapsulated trialate was compared on wild oat and cane millet in wheat fields at three locations in Europe. Table I
The results summarized in Section V show that encapsulated trialate exhibits comparable herbicidal activity to unencapsulated trialate against wild oats and sycamore. Encapsulated trialate shows crop safety for wheat as good or even better than non-encapsulated trialate. In the results summarized in Table IV, aqueous suspensions of microencapsulated trialate and non-encapsulated trialate were applied by spraying by standard agricultural methods.

[Table 32]

In addition to the above-described advantages of the present invention, herbicide or pesticide microcapsules generally offer several advantages over conventional herbicide or pesticide formulations. Thus, for example, microencapsulated herbicide formulations can reduce mammalian toxicity and prolong herbicide activity. Where herbicide volatility is a concern, microencapsulation may reduce evaporative losses and thus prevent the reduction in herbicide activity associated with such losses. Microencapsulated herbicide formulations can in some cases be less phytotoxic to certain crop plants, thereby enhancing the crop stability of the herbicide. Microencapsulation of herbicides also protects herbicides from environmental degradation, reduces leaching of herbicides into the soil, and
And the in-plant life of the herbicide can be extended or increased. It is appreciated that microencapsulated herbicide formulations have several advantages that make such microencapsulated herbicide formulations a desirable and advantageous alternative to conventional herbicide formulations. I can do it.

Accordingly, one object of the present invention is to provide a herbicidal composition consisting essentially of a suspension in water of microcapsules containing herbicide contained within a polyurea encapsulation wall. Herbicides of the above type, preferably acetanilide and thiocarbamate herbicides, and especially alachlor, butachlor, propachlor and trialate, are particularly contemplated for use in such compositions. The concentration of herbicide present in such compositions is about 480 grams per liter of total composition or more, preferably from about 480 to about 700 grams per liter of total composition, and more preferably from about 480 to about 700 grams per liter of total composition. It is about 480 to about 600 g.

The polyurea encapsulation wall is the reaction product of polymethylene polyphenylisocyanate and a polyfunctional amine of the type described above. The concentration of polymethylene polyphenylisocyanate ranges from about 3.5% to about 21.0% relative to the weight of herbicide present in the composition, and the concentration of polyfunctional amine ranges from about 3.5% to about 21.0% relative to the weight of herbicide present in the composition. from about 1.5% to about 9.0% relative to the weight of the herbicide used.

In addition to the microcapsules, there are present in the water a lignin sulfonate emulsifier of the type mentioned above, and optionally formulation ingredients such as antifreeze agents, dispersants, salts, disinfectants and the like. The concentration of lignin sulfonate emulsifier is about 1/2 of the weight of the herbicide present in the composition.
2 to about 15.0%.

It is to be understood that this invention is not limited to the particular embodiments shown herein, and that it may be embodied in other ways without departing from its spirit.

Claims (16)

[Claims] 1. The steps of: (a) providing an aqueous phase containing an emulsifier selected from the group consisting of ligninsulfonate sodium, potassium, magnesium, calcium or ammonium salts; (b) in a water-immiscible substance; dispersing in said aqueous phase a water-immiscible phase consisting essentially of polymethylene polyphenylisocyanate dissolved in said aqueous phase to produce a dispersion of water-immiscible phase droplets throughout the aqueous phase; c) adding a polyfunctional amine to the dispersion with stirring, thereby reacting the amine with the polymethylene polyphenylisocyanate to form a polyurea shell wall around the water-immiscible material; A composition consisting essentially of a mixture of water and microcapsules containing a water-immiscible substance prepared by a method comprising can be,
The concentration of polymethylene polyphenylisocyanate is 3.5 to 21.0% by weight of the water-immiscible material, and the concentration of the polyfunctional amine is 1.5% by weight of the water-immiscible material.
~9.0% by weight, and the concentration of the emulsifier is 1/2 to 15% by weight of the water-immiscible substance, and the water-immiscible substance is 2-chloro-2',6'- Diethyl-N-(methoxymethyl)acetanilide, N-(butoxymethyl)-2-chloro-2',6'-diethylacetanilide, 2-chloro-N-isopropylacetanilide, α-chloro-2'-ethyl-6' -Methyl-N-
(1-methyl-2-methoxyethyl)acetanilide,
α-chloro-N-(2-methoxy-6-methylphenyl)-N-(1-methylethoxymethyl)acetamide,
α-chloro-N-methyl-N-[2-methyl-6-(3
-methylbutoxy)phenyl]acetamide, α-chloro-N-[2-methyl-6-(2-methylpropoxy)
phenyl]-N-(propoxymethyl)acetamide,
N-[(acetylamino)methyl]-α-chloro-N-
(2,6-diethylphenyl)acetamide, α-chloro-N-methyl-N-(2-methyl-6-propoxyphenyl)acetamide, N-(2-butoxy-6-methylphenyl)-α-chloro-N - methylacetamide,
Isobutyl ester of (2,4-dichlorophenoxy)acetic acid, 2-chloro-N-(ethoxymethyl)-6'-ethyl-o-acetatoluidide, 1-(1-cyclohexen-1-yl)-3-(2- Fluorophenyl)-1-
Methylurea, S-2,3,3-trichloroallyl-diisopropylthiocarbamate, S-2,3-dichloroallyl-diisopropylthiocarbamate, α,α,α-
Trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine, 2-chloro-4-ethylamino-6
-isopropylamino-1,3,5-triazine, 2-
Chloro-4,6-bis(ethylamino)-1,3,5-
Triazone, 2-chloro-4,6-bis(isopropylamino)-1,3,5-triazine, 4-amino-6-
(1,1-dimethylethyl)-3-(methylthio)-1
, 2,4-triazin-5(4H)one, N'-(3,
4-dichlorophenyl)-N-methoxy-N-methylurea, 2-chloro-N-(ethoxymethyl)-N-[2-
Methyl-6-(trifluoromethyl)phenyl]acetamide, α-chloro-N-(ethoxymethyl)-N-[
2-ethyl-6-(trifluoromethyl)phenyl]acetamide, methyl and ethyl parathion, ethyl 2
-chloro-4-(trifluoromethyl)-5-thiazolecarboxylate and benzyl 2-chloro-4-(
The composition is selected from the group consisting of trifluoromethyl)-5-thiazolecarboxylate. 2. The composition of claim 1, wherein the polyfunctional amine is 1,6-hexamethylene diamine. 3. The composition of claim 1, wherein the emulsifier is a sodium salt of lignin sulfonate. 4. The concentration of polymethylene polyphenylisocyanate is 5.5% relative to the weight of the water-immiscible material.
6-13.9%, the concentration of the polyfunctional amine is 2.4-6.1% relative to the weight of the water-immiscible substance, and the concentration of the emulsifier is 2.4-6.1% relative to the weight of the water-immiscible substance. 2. A composition according to claim 1, wherein the composition is between 2.0 and 6.0% relative to the weight of the sexual substance. 5. The concentration of polymethylene polyphenylisocyanate is 7.5% relative to the weight of the water-immiscible material.
0%, the concentration of the polyfunctional amine is 3.0% relative to the weight of the water-immiscible material, and the concentration of the emulsifier is 2% relative to the weight of the water-immiscible material. The composition according to claim 4. 6. A composition according to claim 1, wherein the average particle size of the microcapsules ranges from 1μ to 50μ in diameter. 7. The water-immiscible substance is α-chloro-N
5. The composition of claim 4, which is -(ethoxymethyl)-N-[2-methyl-6-(trifluoromethyl)phenyl]acetamide. 8. The water-immiscible substance is 2'-methyl-
6'-ethyl-N-(1-methoxyprop-2-yl)
5. The composition according to claim 4, which is -2-chloroacetanilide. 9. The composition of claim 4, wherein the water-immiscible substance is N-[(acetylamino)methyl]-α-chloro-N-(2,6-diethylphenyl)acetamide. 10. The water-immiscible substance is S-2,3,
5. The composition of claim 4, which is a mixture of 3-trichloroallyl-diisopropylthiocarbamate and α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine. 11. The water-immiscible substance is α-chloro-
2',6'-diethyl-N-methoxymethylacetanilide and 4-amino-6-(1,1-dimethylethyl)-
3-(methylthio)-1,2,4-triazine-5(4
5. The composition of claim 4, wherein the composition is in a mixture with H)one. 12. The water-immiscible substance is α-chloro-
5. The composition of claim 4, which is a mixture of 2',6'-diethyl-N-methoxymethylacetanilide and N'-(3,4-dichlorophenyl)-N-methoxy-N-methylurea. 13. The water-immiscible substance is α-chloro-
a mixture of 2',6'-diethyl-N-methoxymethylacetanilide and 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine;
The composition according to claim 4. 14. The water-immiscible substance is α-chloro-
N-isopropylacetanilide and 2-chloro-4
-ethylamino-6-isopropylamino-1,3,5
- The composition according to claim 4, in a mixture with triazine. 15. The water-immiscible substance is α-chloro-
N-(ethoxymethyl)-N-[2-methyl-6-(trifluoromethyl)phenyl]acetamide and 2-chloro-4-ethylamino-6-isopropylamino-1,
5. A composition according to claim 4, which is a mixture with 3,5-triazine. 16. The water-immiscible substance is 2'-methyl-6'-ethyl-N-(1-methoxyprop-2-yl)-2-chloroacetanilide and 2-chloro-4-ethylamino-6- 5. A composition according to claim 4, which is a mixture with isopropylamino-1,3,5-triazine.