OA11046A - Dispersion of microcapsules of endosulfan - Google Patents

Abstract

PURPOSE: An endosulfan microcapsule dispersion is provided which has excellent stability and biological starting activity and decreased toxicity. CONSTITUTION: In aqueous endosulfan microcapsule dispersions, the dispersed microcapsules contain endosulfan, an organic solvent or solvent mixture, and an isocyanate-prepolymer based capsule-forming material. The aqueous phase which constitutes the dispersion agent contains surface-active substances, a water-soluble inorganic salt and possibly further auxiliary formulation agents containing a relatively low proportion of capsule-forming material.

Description

1 011046

Microencapsulation of activespesticide substances is already described in many patent applications. Such formulations may, for example, liberate the encapsulated active substance in a slow manner and by this means a favorable influence can be exerted on various undesirable properties of the active substance, such as. toxicity to the user, or depletion by washing in groundwater.

For example, EP-A-134 674 discloses penetration toxicity; difonate skin is reduced for rabbits, by the patent document EP-A-183 999 the toxicity of permethrin is reduced for fish, by the patent document EP-A-368 576 the toxicity of chlorpyrifos is reduced for carp, by the fasciculede patent JP-A-6-256116 the penetrational toxicity of fenobucarb is reduced and by the patent specification WO-A-95/23506 the toxicity is reduced for fish and by the gastrointestinal tract in mice.

Among the different microcapsule variants, capsule dispersions have proved particularly suitable. They are obtained, for example, by coating water-insoluble active substances with a polymer skin in an aqueous medium, optionally by stabilizing the dispersion obtained with the aid of dispersion aids and in this way a dilutable concentrate is obtained directly with water. For these formulations, as for all multiphase formulations, care should be taken to ensure that no thickening, decoagulation or sedimentation occurs during storage: at the very least, the user must be able to reasonable expenses, to reverse these phenomena to the quality. It is in the nature of things that for this reason the active substances having a high volume volume are the most difficult to transform into microcapsule dispersions. The requirements for physical stability must be met by an appropriate composition of the aqueous phase.

Two other basic requirements for capsules containing pesticides have their origin in the opposite direction. On the one hand, it must be ensured by a sufficiently stable coating that the desired purpose of encapsulation is achieved, namely the bonding of the active substance to the inner face of the capsule. This means, for example, in the case of toxic insecticides for warm-blooded animals, that the activated active substance is released only after the formulation has been diluted and after which the user has applied it and the layer applied by spraying on the target area has dried. On the other hand, the above-mentioned coating should in no case be so solid that the release of the active substance is too slow after its application.

The lower limit of the release rate is then determined by many factors, such as, for example, physicochemical conditions, the biological mode of action, the type of the pest to be destroyed, and the tolerance of the residues in the cultures to be treated.

The insecticidal active substance endosulfan is, by reason of its toxicity, substances which must be labeled according to the regulation of poisonous substances. But endosulfan has a range of advantages, so that it is widely recognized as a standard insecticide for different crops. There has long been a need for a commercial form of endosulfan in the form of a dispersion of microcapsules which satisfies the above requirements.

The most usable way to build the paroide the capsule above around the active substance to 011046 wrap consists of a polymerization at the interfacedans oil-in-water emulsions, theorganic phasecontaining the side of the active substance anosoluble prepolymer with groups isocyanato free.

US-A-3,577,515 discloses that after the addition of water-soluble polyamines, the surface of the drops in such emulsions hardens upon the addition of prepolymers containing isocyanato groups. In doing so, an outer envelope of polyurea is formed.

US Pat. No. 1,140,516 discloses that microcapsules can also be obtained with an outer skin of the polyurea type without the addition of external water-soluble amines, by carrying out in the emulsion a partial hydrolysis of the prepolymers bearing the isocyanato functional groups. In doing so, some of the amino groups are reconstituted from the isocyanato groups by internal polyaddition followed by hardening, it also forms the desired capsule shell. Described is the use of toluene diisocyanate, hexamethylene diisocyanate, methylene diphenyldiisocyanate and their higher homologous counterparts. In the case where the curing with an external polyamine has to be carried out, it comes for the most part from the group comprising ethylene diamine, propylene diamine, hexa-methylene diamine, diethylene triamine and latetraethylene pentamine. Formulations with encapsulated endosulfan have already been described by various publications of the patent literature.

Patent specification DE-A-2,757,017 deals with internally structuring microcapsules, the wall material of which consists of a mixed-type polymer which is crosslinked by urea and urethane units. The active substance dissolved in an organic solvent is found in the capsule. In order to build the wall of the capsule, in this case typically 10% of the prepolymer is used in relation to the totality of the formulation. There is no indication of the reduction of acute oral toxicity of this type of formulation. The same prepolymer is used in the patent specification WO-A-96/09760 also for the encapsulation of endosulfan. Indeed, a satisfactory insecticide efficacy is described, but no advantage with respect to undesirable toxicity. Patent specification WO-A-95/23506 relates to endosulfan-loaded polyurea microcapsules in which the active substance is present as a cooled melt. As a prepolymer, a mixture of methylene diphenyldiisocyanate and its higher homologs is undressed; the amount employed of the polymer is greater than 6% with respect to the total formulation. Curing is carried out using a mixture of polyamines. In addition to the indications of greatly reduced toxicity, this type of formulation does not provide any indication of the benefits in the field of biological efficacy and residues.

As before, there is therefore a need for insecticide formulation with encapsulated endosulfan, which fulfills the following conditions: - simple preparation mode, without risk, good storage stability, reduced toxicity for the user and the organisms useful, good initial biological effect, absence of the risk of multiplication of non-released residues of the active substance for the parts of the plant treated.

It has now surprisingly been found that a dispersion of microcapsules prepared by the known interface depolymerization process having an endosulfan content of up to 30% by weight and more, preferably from 300 to 330 g. endosulfan / 1, satisfies the above requirements when a relatively small amount of isocyanato-containing anepolymer (about 1% by weight) is used in the preparation, in addition to the water-soluble diamine which may be required. . Namely, thanks to the very small amount of prepolymer forming the wall of the capsule, the beginning of the insecticidal action is not slowed under the practical conditions. By adding a sufficiently large amount of a water-soluble organic salt, such as calcium chloride, to the aqueous phase and following an increase in the volume-mass related to this addition, the sedimentation of the microcapsules can be prevented after a certain time and possibly, the formation of a background deposit relatively difficult to disperse.

Such microcapsule dispersions make it possible, because of their favorable acute toxicity to warm-blooded organisms, to classify them as toxicologically "toxic" and show - in the case where they contain calcium chloride as a mass-increasing agent However, in comparison with the above-mentioned methods, there is a relatively lower toxicity to fish than such microdispersions which do not contain calcium chloride. It is known that commercially available emulsifiable concentrates have a high toxicity to fish. The invention relates to aqueous dispersions of endosulfan microcapsules in which the dispersed microcapsules contain endosulfan, an organic solvent or a mixture of solvents and a capsule-forming material based on an isocyanate-type prepolymer and the aqueous phase, which represents the dispersing agent contains surface-active agents and optionally other formulation adjuvants, and which, relative to the total dispersion, contain from 20 to 40% by weight of endosulfan, from 10 to 35% by weight. mass of organic solvent or solvent mixture, the material constituting the capsule based on 0.5 to 5% by weight of isocyanate-based prepolymer, 0.2 to 5% by weight of one or more agents of surface of the group comprising emulsifiers and dispersing agents and a water-soluble inorganic salt, the salt content being chosen such that the density of the aqueous phase is between e 1.05 and 1.45 kg / l.

In the microcapsule dispersions according to the invention, it is possible to use organic solvents or their mixtures chosen from N-fatty acid alkylamides, N-alkyl lactams, fatty acid esters and aromatic hydrocarbons, and alkyl-substituted naphthalene derivatives. lower ones being particularly appropriate.

Suitable commercially available solvents according to the invention are, for example, Solvesso 200 (1), butyl diglycol acetate, ShellholRA (2), Acetel 400 (3), Aggsolex 8 (4), Aggsolex. 12 (5), ®Norpar 13 (6), ®Norpar 15 (7), ®Isopar V (8), ®Exsol D 100 (9), ®Shellsol K (10) and © Shellsol R (11), whose The composition is as follows: (1) mixed alkali metal naphthalenes, boiling range 219 to 282 ° C, manufacturer: Exxon, (2) alkylated benzene mixtures, boiling range 183 to 312 ° C, manufacturer: Shell, (3) high boiling aromatic mixture, boiling range 332 to 355 ° C, manufacturer: Exxon, (4) N-octylpyrrolidone, boiling point 100 ° C (0.3mm Hg), manufacturer: GAF,

(5) N-dodecylpyrrolidone, boiling point 145 ° C 7 011046 (0.3 mm Hg), manufacturer: GAF, (6) aliphatic hydrocarbons, boiling range 228 to 243 ° C, manufacturer: Exxon, ( 7) aliphatic hydrocarbons, boiling range 252 to 272 ° C, manufacturer: Exxon, (8) aliphatic hydrocarbons, boiling range 278 to -305 ° C, manufacturer: Exxon-, (9) aliphatic hydrocarbons, range boiling point 233 to 263 ° C, manufacturer: Exxon, (10) aliphatic hydrocarbons, boiling range 192 to 254 ° C, manufacturer: Shell, (11) aliphatic hydrocarbons, boiling range 203 to 267 ° C C, manufacturer: Shell.

Mixtures of these solvents with each other are also suitable. Butyl diglycol acetate, Accelel 400, Aggsolex 8 and Aggsolex 12, Solvesso 200 can be particularly suitably used.

In this solvent, the active substance endosulfan is dissolved beforehand, and this in such quantities that the concentration of active substance in relation to the totality of the formulation is between 20 and 40% by weight, preferably between 20 and 35% by weight. About 300 to 330 g of endosulfan / l of the total formulation are particularly preferred.

The capsule-forming material, by which the microcapsule casings are made, is preferably obtained from anisocyanate-containing prepolymers containing a group of mixed industrial products, each consisting of polyisocyanates based on condensation products. Aniline and duformaldehyde. Mixed industrial products differ from each other by their degree of condensation and possibly by their chemical modifications. Important characteristics for the user are the viscosity and the content of free isocyanato groups. Typical marketed products are the brands ®Desmodur (Bayer AG) and the brands ®Voranate (Dow Chemicals). It is essential for the invention that the amount of isocyanato group-containing prepolymer used is 5% by weight based on the totality of the formulation; preferably from 0.5 to 5% by weight, in particular from 1 to 2% by weight, is used.

The capsule-forming material is obtained by hardening the isocyanato-containing prepolymer either in the presence of water at a temperature of from 0 to 95 ° C, preferably from 20 to 65 ° C, or preferably with the necessary amount of a diamine.

In the case where the microcapsules are formed with the aid of diamines, there may be used, for example, alkylene diamines, dialkylene triamines and trialkylene tetramines, the hydrocarbon chain units of which contain a number of carbon atoms of between 2 and 8. Hexamethylenediamine is used. For this purpose, it is possible either to use amounts which are in a ratio of the employed amount of isocyanate prepolymer or, preferably, in excess of up to three times, but preferably twice as much.

The aqueous phase of the formulations according to the invention contains surfactant formulation adjuvants taken from emulsifiers and dispersants. They come from a group comprising, for example, materials of the family of polyvinyl alcohols, poly (oxyalkylenes), products of the condensation of formaldehyde with naphthalenesulphonic acids and / or phenols, polyacrylates, and the descopolymers of maleic anhydride with alkylalkyl ethers, lignosulfonates and polyvinylpyrrolidones. These materials are used in an amount of from 0.2 to 5% by weight, preferably from 0.5 to 2% by weight, based on each time in relation to the totality of the dispersion.

For the polyoxyalkylenes, sequenced polymers are preferred, the molecular center of which is formed by a block of polyoxypropylene, whereas, the periphery of the molecule consists of polyoxyethylene blocks. To do this, it is particularly preferred. materials in which the polyoxypropylene block has a molar mass of 2000 to 3000 and the polyoxypropylene blocks are present in a proportion of 60 to 80% of the total molar mass.Such a material is marketed for example by the company BASF Wyandotte under the trademark ®Pluronic F87 . Other suitable dispersing agents are calcium lignosulfonate, sodium lignosulfonate with a high degree of purity (for example, ®VanisperseCB from the company Borregaard), SI dispersants and SS dispersing agents from Hoechst AG, the sodium salt of condensation product of acidenaphthalene sulfonic-formaldehyde (for example ®MorwetD 425 from DeSoto or ®Tamol NN 8906 from BASF), sodium polycarboxylate (for example ®Sopropon T 36from the company Rhône Poulenc).

Suitable polyvinyl alcohols are prepared by partial saponification of polyvinyl acetate. They have a degree of hydrolysis of 72 to 99 mol% and a viscosity of 2 to 18 cP (measured on a 4% strength aqueous solution). 20 ° C, according to DIN53 015). Preferably, partially saponified poly (alcohols) are used with a degree of hydrolysis of 83 to 88 mol% and a low viscosity, in particular of 3 to 5 cP.

Optionally, the aqueous phase of the formulationsconformed in the invention contains at least one other formulation adjuvant of the family of wetting agents, antifreezes, thickeners, preservatives and constituents increasing volumic volume ·. 011046

As wetting agents come into account, for example, representatives of the decomposed groups of alkylated naphthalene sulfonic acids, N-fatty alkyl N-alkyltaurides, fatty acyl alkylamidobetaines, alkylpolyglycosides, alpha-olefin sulphonates, alkylbenzenesulfonates, desesters of sulfosuccinic acid and alkylsulfatesgras (optionally modified with alkoxyalkylene groups). Their level is between 0 and 5% by weight, preferably between 0 and 2% by weight relative to the totality of the formulation.

Suitable products available in the trade are, for example, ®Darvan No. 3, ®Vanisperse CB, Luviskol K 30, Reserve C, Fluorit P, Sokalan CP 10, Maranil A, Genapol PF40, Genapol LRO, ethers. detributylphenol and polyglycol such as the brands ®Sapogenate T (Hoechst), nonylphenol ethers and depolyglycol such as the trademarks © Arcopal N (Hoechst) or derivatives of tristyrylphenol ethers and polyglycol.

As preserving agent, it is possible to add to the aqueous formulations the following agents: formaldehyde or hexahydrotriazine derivatives, such as for example Mergal KM 200 from the company Riedel de Haenou®Cobate C from the company Rhône Poulenc, derivatives of isothiazolinone, for example from Mergal K9N of the company Riedel de Haen or ®Kathon CG of the Rohmund Haas Company, 1,2-benzisothiazolin-2-ones, such as for example ®Nipacid BIT 20 'from the company Nipa LaboratorienGmbH or © Mergal K10 from the company Riedel de Haen or 5-bromo-5-nitro-1,3-dioxane (Bronidox L from Henkel). The proportion of these preservatives is at most 2% by weight relative to the totality of the formulation.

Suitable anti-freezing agents are, for example, mono- or multifunctional alcohols, glycol ethers or urea, in particular calcium chloride, glycerin, isopropanol, propylene glycol monomethyl ether, monomethyl ether of di- or propylene glycol or cyclohexanol. The proportion of these antifreezes is at most 20% by weight relative to the totality of the formulation. Organic or inorganic thickeners may be employed; we can also use their combinations. Suitable agents are, for example, those based on aluminum silicate, dexanthan, methylcellulose, polysaccharides, alkaline-earth metal silicates, gelatin and polyvinyl alcohol, such as, for example, ®Bentone EW, ®Veegum , ®Rodopol 23 or ®Kelzan S. They can be present in a proportion of 0 to 0.5% by weight relative to the totality of the formulation. As the component for increasing the density of the aqueous phase, water-soluble salts of alkali and alkaline earth metals, as well as ammonium salts or mixtures thereof, can be used. The amount of salt depends on the specific weight which the aqueous phase must exhibit at each time, namely mass masses of between 1.05 and 1.45 kg / l, preferably between 1.10 and 1.40 kg / l and particularly preferably between 1.15 and 1.35 kg / l. Amounts are preferred whose addition brings the volumetric mass of the aqueous phase closer to the density of the organic phase. The invention also relates to a process for the preparation of the microcapsule dispersions according to the invention, characterized in that a coarse pre-emulsion is first prepared from the organic phase and the aqueous phase (without the diamine). and then it is then exposed to shear forces by passing it preferably through a continuously operating mixing device, for example a static mixer, a toothed or analogous colloid mill. By this operation, firstly the fine division is formed necessary for the formation of microcapsules of emulsified oil droplets. At the end, optionally after the addition of a diamine, the entire volume of the materials is corrugated by a polycreaction.

The process according to the invention can be carried out on the technical scale and the production scale in semi-continuous mode.

The following examples serve to provide more detailed explanations of the invention without being limited to these examples. A. EXAMPLES OF FORMULATION Example 1 to 5 (technical tests) Each time, a solution of 27 kg of technical endosulfan and 23 parts of stirring vessel equipped with an anchor stirring vessel is prepared in a stirred tank of 200 liters. kg of ®Solvesso 200 and the tank is evacuated.

Subsequently, an aqueous phase is prepared in the same stirred vessel (the composition of the various examples is given in Table 1 below), first introducing the water and then, stirring, the various adjuvants. We continue to stir until complete dissolution. Thereafter, the stirring rate is increased to 70 rpm and the freshly prepared organic phase mixture as described above is rapidly introduced with 1 kg of VoranateM220. '

After stirring for a short time, the stirrer is stopped and the crude, yellowish emulsion is allowed to flow into a reservoir through a toothed colloid mill, forming a thin, clear emulsion whose droplets have a diameter of 2. at 15 pm depending on the setting of the colloid mill 35 toothed. This fine emulsion is returned to the cuveagitée and the stirring mobile is started again with a speed of 70 rpm. 2.5 kg of 40% aqueous hexamethylene solution was added and stirred for a further 4 hours at 30 rpm. TABLE 1

Example (quantitative data in kg) 1,2 3,4 5 ®Mowiol 3/83 2,00 2,00 1,00 ®Pluronic F87 1,80 1,80 1,80 ®Morwet D425 0,50 ®Galoryl DTI20 0 , 50 ®Sopropfor FL 2.00 ®Rhodopol 23 0.10 0.10 0.10 ®Mergal K9N 0.10 0.10 0.10 ®Antimussol UP 0.10 0.10 0.10 CaC12 anhydrous 12.20 11 , 00 Glycerin techn. 4.00 4.00 Water 25.70 26.90 41.40 The microcapsules contained in the dispersion 10 have a mean diameter which depends, in addition to the composition composition, also on the peripheral speed of the rotor of the mill and the setting of the resistance between the rotor and the stator ("Reibspalte"). Table 2 contains more detailed information. The indicated viscosity data was measured using a rotary viscometer. 15 14 011046

Example Peripheral speed tpm TABLE 2 Diameter of the capsule pm Distance between the starter and the starter ("Reibspalt") Viscosity mPas at 144 s-1 1 3000 3 840 2.8 2 1500 3 1100 5.1 3 1500 1 500 9.0 4 1500 1,510 8.7 5 3000 3 140 2.5

Example 6

A microcapsule dispersion is prepared as in Examples 1 to 5, but with the difference that no continuous mixing step is provided. The composition of the phase is as follows: 2.1 kg of ®Mowiol 3/83, 1.8 kg of ®Pluronic F 87, 0.5 kg of ®Morwet D425, 4 kg of technical glycerin (86.5%) as well as each time 100 g of ®Rhodopol 23 and ®Mergal K9N in 36.8 kg of water. This phasicose is placed in a stirred tank equipped with an anchor stirring device and the organic phase composed of 27 kg of technical endosulfan, 24 kg of Solvesso 200 and 1 kg of prepolymer®Voranate M220 is poured in with stirring. a tilting pourer. After stirring for 30 minutes, 2.5 kg of aqueous solution of hexamethylene / diamine are added and the mixture is stirred for a further 4 hours.

In this way, microcapsules with an average diameter of 14.9 μm are obtained.

Example 7

A microcapsule dispersion was prepared as in Example 6 but with the difference that a paddle stirrer was used instead of an anchor stirrer. Under identical conditions, microcapsules having an average diameter of 4.1 μm are obtained.

Example 8 (Comparative Example)

For this microcapsule experiment, a material obtained by conversion of 8 moles of toluene diisocyanate with hexane-1,2,6-triol: butane-1,3-diol: propylene glycol 1000 in a molar ratio of 3: 1 was used as the polymer. 1 and, for further use, 1: 1 n-butyl acetate-xylene is dissolved in a mixture, which contains a solution of the 50% prepolymer (described in DE-A 2,757,017). ).

A microcapsule dispersion as described in Example 1 was prepared, but with the difference that 36.4 parts of water and 3 parts of the prepolymer solution indicated above were used, giving up the diamine for curing. To do this, it is stirred for 15 hours at room temperature.

The microcapsules of the dispersion obtained have an average diameter of 17 μηη and the viscosity measured on a rotary viscometer is 350 mPas for a shear rate of 144 s -1.

EXAMPLES 9, 10 AND 11 On the laboratory scale, microdispersions are prepared by means of the formulations of Examples 1, 3 and 5 by first placing 46.5 parts of the aqueous phase described above. and introducing into the aqueous phase, with stirring at 300 rpm, 51 parts of the complete organic phase. Then, the stirrer is set at 200 rpm and stirred for 30 seconds at 2000 rpm. Then the number of revolutions is reduced to 300 rpm, 2.5 parts of a 40% aqueous solution of hexamethylenediamine are added and the mixture is stirred for a further minute. Finally, the number of revolutions is reduced to 50 rpm and the stirring is continued for another 4 hours. 011046 - 16 -

The results are summarized in Table 3. TABLE 3

Example Formulation as in Example Viscosity mPas at 144 s-1 Decapsule diameter (μm) 9 1,870 8,1 10 3,560 7.8 11 5 150 8.4

B. BIOLOGICAL EXAMPLES

Example 12: Initial and long-lasting effect on Aphis fabae

Beans are sprayed on the beans until a dilution of the indicated formulation is achieved, and the plants are infested by bean aphids immediately, respectively 3 days after drying.

Control: mortality (%) 7 days after infestation (see Table 4) TABLE 4

Formulation g of active substance / hl Infestation 0 days after 3 days endosulfan 30 99 EC35 (commercial product) 10 90 15 3 • o-0 Example of formulation 10 30 100 95 10 98 60 3 93 0

Example 13: Initial and lasting effect onHeliothis virescens

The cotton plants are sprayed with an amount of an aqueous dilution of the indicated formulations corresponding to an application amount of 200 liters of boiled water per hectare. After drying, larvae of Heliothis virescens ("Baumwollkapselbohrer") were infested immediately, respectively 4 and 7 days later. (Results see Table 5). (Control: Mortality (%) 4 days after infestation). TABLE 5

Formulation g of active substance / hl Infestation after 0 days 4 days 7 days endosulfan 300 100 100 50 EC35 (commercial product) 100 100 70 20 30 80 30 40 10 10 0 10 Example of formulation 10 300 100 100 100 100 90 100 100 30 10 80 100 10 20 30 90

Greenhouse experiments confirm that a formulation of microcapsules according to the invention is at least equivalent to a commercial EC formulation which concerns its initial and long-lasting effect.

C. TOXICOLOGICAL TRIALS

Example 14

Microcapsules having an average diameter of 14.9 μm capsules, prepared as described in Example 6: LD50 for female rats: 530 mg / kg body weight

Example 16

Microcapsules having a mean capsule diameter of 7.8 μm, prepared as described in Example 10: LD50 for female rats: greater than 200 mg / kg body weight 18 011046

Example 17

Microcapsules with an average diameter of 17 μιη capsules, prepared as described in Example 8: LD50 for female rats: 173 mg / kg of body weight

The toxicological tests confirm a favorable oral toxicity of the formulations according to the invention for warm-blooded animals over a wide range of diameters.

D. TOXICITY ON FISH

The examples in Table 6 show that the fish toxicity of the microcapsule formulations according to the invention containing sodium chloride is considerably less than that of microcapsule dispersions without calcium chloride. TABLE 6 TOXICITY ON FISH TO PERCH ("BLAUER SONNENBARSCH")

Example 18: DISPERSION OF MICROCAPSULES WITHOUT CaCl2 (Formulation Example 5) Concentration mq 24 h animals /% Mortality 48 h animals /% a after 72 h animals /% 96 h animals /% Formulation / 1 Control 0/0 0/0 0 / 0 0/0 0.032 0/0 0/0 0/0 0/0 0.1 3/100 3/100 3/100 3/100 19 011046

EXAMPLE 19 DISPERSION OF MICROCAPSULES ACCORDING TO THE INVENTION (EXAMPLE OF FORMULATION 1)

Mortality after

Concentration 24 h 48 h 72 h 96 h met animals /% animals /% animals /% animals /% Formulation / 1 Control 0/0 0/0 0/0 0/0 0,032 0/0 0/0 0/0 0 / 0 0.1 0/0 0/0 0/0 0/0

Example 20

DISPERSION OF MICROCAPSULES ACCORDING TO THE INVENTION (FORMULATION EXAMPLE 3) Concentration mq 24 h animals /% Mortality 48 h animals /% a after 72 h mimaux /% 96 h animals /% Formulation / 1 Control 0/0 0/0 0 / 0/0/0 0.032 0/0 0/0/0/0/0 0.1 0/0 0/0 0/0/0/0 10

Claims (10)

- 011046 CLAIMS An aqueous dispersion of endosulfan microcapsules in which the dispersed endosulfan microcapsules contain an organic solvent or a mixture of solvents and an isocyanate-based prepolymer-forming material and the aqueous phase, which is the dispersion medium, contains surfactants and optionally other formulation adjuvants and which, based on the entire dispersion, contain from 20 to 40% by weight of endosulfan, from 10 to 35% by weight of organic solvent or solvent mixture, of the capsule material based on 0.5 to 5% by weight of isocyanate-based prepolymer, 0.2 to 5% by weight of one or more surfactants selected from the group consisting of emulsifiers and dispersants and a water-soluble inorganic salt, the salt content being selected so that the density of the aqueous phase is between 1.05 and 1.45 kg / l. 2. Microcapsule dispersion according to claim 1, wherein the isocyanate-based prepolymer is an oil-soluble technical mixed product from polyisocyanates based on aniline and formaldehyde condensation products. 3. Dispersion of microcapsules according to claim 1 or 2, wherein the material constituting the capsule is formed by curing the isocyanate-based prepolymer in the presence of water at a temperature of 0 to 95 ° C, preferably 20 to 65 ° C. orwith a necessary amount of a diamine. 4. Dispersion of microcapsules according to one of claims 1 to 3, which contains, in relation to the entire dispersion, 20 to 35% by weight of endosulfan, 15 to 30% by weight of organic solvent or a mixture of solvents, the material constituting the capsule based on 1 to 2% by weight of isocyanate-based prepolymer, 0.5 to 2% by weight of one or more surfactants taken from the group comprising of. emulsifiers and dispersing agents. The microcapsule dispersion according to any one of claims 1 to 4, wherein the capsule material is formed by curing the isocyanate-based prepolymer with up to three times a stoichiometric amount of a diamine. 6. Dispersion of microcapsules according to one of claims 1 to 5, wherein the aqueous phase has a density of 1.05 to 1.45 kg / 1. 7. Dispersion of microcapsules according to one of claims 6 therein, the aqueous phasepresents a density of 1.10 to 1.40 kg / 1. 8. Dispersion of microcapsules according to one of claim 7, the aqueous phasepresents a density of 1.15 to 1.35 kg / 1. Microcapsule dispersion according to one of claims 1 to 8, which contains calcium chloride as the water-soluble inorganic salt. 10. Process for the preparation of a dispersion of microcapsules according to one of Claims 1 to 9, characterized in that a coarse pre-emulsion is prepared from the organic phase and the aqueous phase, and then exposed This is achieved by shearing forces and curing the resulting divided emulsion, optionally after the addition of a diamine, to the entire volume of the material.