KR20000053236A - Endosulfan microcapsule dispersion - 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

Endosulfan Microcapsule dispersion

Many patent applications have already described microencapsulation of pesticide active ingredients. Formulations of this type can, for example, release the encapsulated active ingredient in an extended manner and can effectively solve many undesirable properties of the active ingredient (such as toxicity to the user or reaching groundwater). have.

For example, European Patent Application No. 134 674 describes the reduction of the skin toxicity of diponate in rabbits, and European Patent Application No. 183,999 discloses the reduction of toxicity of permethrin to fish, European Patent US Pat. No. 368,576 describes a reduction in the toxicity of clopilipose in carp, and Japanese Patent Application No. 6 256116 describes a reduction in skin toxicity of phenobucab. Describes the reduction in toxicity to fish and food toxicity in rats.

Among the various modified microcapsules, capsule dispersions have been found to be particularly useful. Capsule dispersions, for example, use a polymer shell to wrap the water-insoluble active ingredient in an aqueous environment, to stabilize the resulting dispersion (if necessary, dispersants are used), and concentrates water-dilutable by this method. This is just made. As with all multiphase formulations, care should be taken to ensure that no densification, coagulation or sedimentation formation occurs during the storage process in these formulations and that the user should be able to suppress such changes that degrade the quality of the active ingredient at least with reasonable effort. It is therefore natural that treating high density active ingredients to form microcapsule dispersions is very difficult. Requirements for physical stability should also be met with suitable compositions on aqueous carriers.

Insecticide-containing capsules must additionally meet two opposing requirements. One of them should form a film that is sufficiently stable to meet the encapsulation purposes required. In other words, the active ingredient must be bound inside the capsule. This means, for example, that if the insecticide is toxic to a warm-blooded animal, the user typically dilutes and applies the formulation and the active ingredient is sealed and not leaked until the sprayed coating is dried on the desired surface.

On the other hand, the coating should not be too strong so that the active ingredient does not come out too slowly after application. The lower limit of release rate is predetermined by a number of factors, for example, physicochemical conditions, mode of biological action, type of pest organism to be rescued, and tolerance of plant protection residuals in the treated crop.

According to German legislation on dangerous substances, in view of the toxicity of endosulfan, the active pesticide endosulfan is also included among the substances requiring proper labeling. However, endosulfan has a number of advantages and is widely recognized as a standard insecticide in many crops. Therefore, there has been a long demand for endosulfane to be commercially available in the form of microcapsule dispersions meeting the above requirements.

The most common method of forming the capsule wall surrounding the active ingredient is interfacial polymerization of an oil-in-water emulsion, wherein the organic phase comprises an oil-soluble prepolymer having free isocyanate groups with the active ingredient. .

U.S. Patent No. 3 577 515 describes how after the addition of a water soluble polyamine, the surface of the droplets in this emulsion cures as the prepolymer containing isocyanate groups is added. This forms the polyurea outer wall.

U.S. Patent Application No. 4 140 516 discloses that microcapsules having an outer wall of polyurea type, in the absence of external water soluble amines, can be prepared by partial hydrolysis in an emulsion of a prepolymer containing an isocyanate functional group. Doing. In this case, some amino groups are reformed from the isocyanate groups and the desired capsule wall is formed by internal multiple additions and subsequent curing. The use of tolylene diisocyanates, hexamethylene diisocyanates, methylenebis (phenylisocyanates) and analogs with high molecular weights thereof is also described. When curing proceeds with an external polyamine, this polyamine is generally derived from the group consisting of ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine and tetraethylene pentaamine.

Formulations containing microencapsulated endosulfans have already been described in a number of patent documents.

German Patent Application No. 2 757 017 relates to internally structured microcapsules in which the material of the wall has the properties of a mixed polymer crosslinked by urea and urethane residues. The active ingredient is located inside the capsule that is dissolved in the organic solvent. Typically 10% by weight of prepolymer, based on the weight of the entire formulation, is required to form the capsule wall. However, there is no information on the reduction of acute oral toxicity by this type of formulation.

The same prepolymer is used in WO 96/09760 to encapsulate endosulfan. Good pesticidal activity is described, but no advantage for unwanted toxic effects is also described.

WO 95/23506 relates to endosulfan-filled polyurea microcapsules in which the active ingredient is in the form of a cooled melt. As prepolymers, mixtures of methylenebis (phenyl isocyanate) and higher molecular weight analogs are described, the amount of prepolymer being used is at least 6% by weight based on the weight of the total formulation. Curing is carried out using a mixture of polyamines. Except for the results of this type of formulation being very reduced in toxicity, it did not appear to provide any benefit for biological activity or otherwise.

Thus, while containing microencapsulated endosulfan, simple non-toxic recipes, excellent stability on storage, reduced toxicity to users and useful organisms, good biological initiation activity, increased residual amounts of unreleased active ingredients on treated crop parts, There is a continuing need to prepare pesticide formulations that meet such requirements as non-hazards.

Surprisingly, the microcapsule dispersion prepared by an interfacial polymerization method known in the art and comprising at least 30% by weight of endosulfane, preferably about 300 to 330 g of endosulfane per liter, may contain any water-soluble diamine required for the preparation. In addition, it has been found that relatively small amounts of isocyanate-containing prepolymers (in amounts of about 1% by weight) are used to meet the above requirements. "Very small amount of prepolymer forming the capsule wall" means that the onset of pesticide activity is not delayed under actual conditions. Adding a sufficiently large amount of water soluble inorganic salt (eg sodium chloride) to the water phase increases the density, which can prevent the microcapsules from settling after a certain time to form a bottom precipitate that is difficult to redisperse.

This type of microcapsule dispersion was "dangerous" in the toxicological class because of its acute toxicity to warm-blooded animals, and when it contains calcium chloride as a density increasing agent, it contains a microcapsule dispersion that does not contain calcium chloride. It showed significantly lower fish toxicity. Commercially emulsifiable concentrates are known to still have high fish toxicity.

The present invention provides that the dispersed microcapsules comprise an encapsulant, an organic solvent or solvent mixture, and a capsule forming material based on an isocyanate prepolymer, and the aqueous phase, which means a dispersion medium, comprises a surfactant with or without other formulation aids. Aqueous microcapsule dispersions, wherein, based on the weight of the total dispersion, the microcapsule dispersion comprises 20-40% by weight endosulfan, 10-35% by weight organic solvent or solvent mixture, and 0.5-5% by weight isocyanate prepolymer. 0.2 to 5% by weight of at least one surfactant selected from the group consisting of forming materials, emulsifiers and dispersants, and water-soluble inorganic salts selected to have a density of 1.05 to 1.45 kg / l.

In the microcapsules according to the present invention, organic solvents selected from the group consisting of N-alkylamides of N fatty acids, N-alkylrantams, esters of fatty acids and aromatic hydrocarbons or mixtures thereof can be used, and lower-alkyl substituted naphthalene derivatives are Especially suitable.

Suitable commercially available solvents according to the invention are, for example, Solvesso® 200 (1), butyl diglycol acetate, Shellsol® RA (2), Acetrel® ) 400 (3), Agsolex (registered trademark) 8 (4), Agsolex 12 (5), Nopal (Norpar, registered trademark) 13 (6), nopal 15 (7), isopal V (8 ), Exsol® D 100 (9), Shelsol K (10) and Shelsol R (11), which are (1) a mixture of alkylated naphthalenes (boiling point: 219-282 ° C., manufactured by Exxon), ( 2) a mixture of alkylated benzenes (boiling point: 183-312 ° C., prepared in shell), (3) a high boiling mixture of aromatics (boiling point: 332-355 ° C .; manufactured by exon), (4) N-octylpyrrolidone ( Boiling point (0.3 mmHg): 100 ° C., manufactured at GAF), (5) N-dodecylpyrrolidone (boiling point (0.3 mmHg: 145 ° C., manufactured by GAF)), (6) aliphatic hydrocarbon (boiling point: 228-243 ° C.) ; Manufactured from exon), (7) aliphatic hydrocarbons (boiling point: 252-272 ° C., manufactured from exon), (8) aliphatic Hydrogen (boiling point: 278-305 ° C., manufactured by exon), (9) aliphatic hydrocarbon (boiling point: 233-263 ° C., manufactured by exon), (10) aliphatic hydrocarbon (boiling point: 192-254 ° C., manufactured by shell), and (11) A composition of aliphatic hydrocarbon (boiling point: 203-267 ° C., manufactured by the shell) is included.

A mixture of another solvent with this solvent is also suitable. In particular, butyl diglycol acetate, Acetrel 400, Agsolex 8 and Agsolex 12 are also useful. Solveso 200 is particularly preferred.

The active ingredient endosulfan is present in solution in such a solvent, more preferably 20 to 40% by weight, preferably 20 to 35% by weight, of the concentrate of the active ingredient, based on the weight of the total formulation. Especially preferably, it comprises about 300 to 330 g of endosulfane per liter of the total formulation.

The encapsulating material which forms the walls of the microcapsules is preferably a material prepared from oil-soluble prepolymers containing isocyanate groups, each consisting of a series of respective polyisocyanates based on condensates of aniline and formaldehyde Of industrially mixed products. These industrially mixed products differ from each other in degree of condensation and possibly in chemical modification, respectively. Important properties for the user are the viscosity and the content of free isocyanate groups. Typical products on the market are Desmodur brands (Bayer AG) and Boranate brands (Dow Chemical). In the present invention, the amount of prepolymer containing isocyanate groups used is 5% by weight or less, preferably 0.5 to 5% by weight, in particular 1 to 2% by weight, based on the weight of the total formulation.

The capsule forming material is formed by curing the isocyanate prepolymer in the presence of water at 0-95 ° C., preferably 30-65 ° C. or preferably with the required amount of diamine.

When the microcapsules are formed in the presence of diamines, suitable diamines include, for example, alkylenediamines, dialkylenetriamines and trialkylenetetraamines and their carbon backbone units contain from 2 to 8 carbon atoms. do. Preferably, hexamethylenediamine is mentioned. In this case, their amount can be used in stoichiometric ratios relative to the amount of isocyanate prepolymers used, or is preferably used in excess of 3 times excess, in particular in 2 times excess.

The aqueous phase of the formulation according to the invention comprises an interfacial-active formulation aid selected from the group consisting of emulsifiers and dispersions. These are, for example, poly (vinyl alcohol) s, poly (alkylene oxides), naphthalenesulfonic acids and / or condensation products of phenols and formaldehyde, copolymers of polyacrylates, alkylene alkyl ethers and maleic anhydride , Ligninsulfonate and polyvinylpyrrolidone. Such materials are used at 0.2 to 5% by weight, preferably 0.5 to 2% by weight, respectively, based on the weight of the total dispersion.

Preferred poly (alkylene oxides) are block copolymers whose molecular centers are formed of poly (propyleneoxide) blocks, while the perimeter of the molecule is formed of poly (ethylene oxide) blocks in contrast. In particular, preferably, in this case, the molar mass of a polypropylene block is 2000-3000, and the material in which a poly (ethylene oxide) block forms 60-80% of the total molar mass is mentioned. Materials of this type include, for example, those commercially available from BASF Wyandotte under the trade name Pluronic F87.

Other suitable dispersants include calcium ligninsulfonate, highly refined sodium ligninsulfonate (e.g. Varanisperse CB available from Borregard), dispersant SI and dispersant SS (Hoechst AG), Naphthalenesulfonic acid / formaldehyde condensation products, sodium salts (e.g., Morwet® D 425 available from DeSoto or Tamol® NN 8906 available from BASF), sodium poly Carboxylates (Sopropon® T 36 available from Rhone Poulenc).

Suitable poly (vinyl alcohol) is prepared by partially saponifying poly (vinyl acetate). Their degree of hydrolysis is 72 to 99 mol% and the viscosity is 2 to 18 cP (measured in an aqueous solution at 4% concentration at 20 ° C. according to DIN 53 015). Preferably, partially saponified poly (vinyl alcohol) having a degree of hydrolysis of 83 to 88 mol% and a low viscosity, especially 3 to 5 cP, is preferred.

The aqueous phase of the formulations according to the invention, if appropriate, comprises one or more additional formulation aids selected from the group consisting of humectants, antifreezes, tackifiers, preservatives and ingredients that increase density.

Suitable wetting agents include, for example, alkylated naphthalenesulfonic acids, N-fatty acid acyl N-alkyltaudes, fatty acid acylamidoalkylbetaines, alkyl polyglycosides, alpha-olefinsulfonates, alkylbenzenesulfonates, sulfosuccinic acids. Substances such as esters and fatty acid alkyl sulfates (unmodified or modified by alkyleneoxa groups). Their content herein includes 0 to 5% by weight, preferably 0 to 2% by weight, based on the weight of the total formulation.

Suitable commercially available products include, for example, Darvan (registered trademark) No 3, Vanisper (registered trademark) CB, Luviskol (registered trademark) K 30, Reserve (registered trademark) C, Forlanit® P, Sokalan® CP 10, Maranil® A, Genapol® PF 40, Genapol LRO, Tributylphenol Poly Glycol ethers (e.g., Sapogenat® T trade name (Cheist)), nonylphenol polyglycol ethers (e.g. Arkopal N trade name (Cheist)) or tristyrylphenol polyglycol ether derivatives. have.

Examples of preservatives include formaldehyde or hexahydrotriazine derivatives (e.g., Mergal® KM 200 from Riedel de Haen or Cobate® C from Ron Flan, Iso). Thiazolinone derivatives (e.g. Mergal K9N of Riedel de Haen or Kathon CG of Rhom & Hass), 1,2-benzisothiazolin-2-one (e.g. Nipa Labortoriz) Nipacide® BIT 20 from Nipa Laboratories GmbH or Mergal K 10 of Liedel de Jaen) or 5-bromo-5-nitro-1,3-dioxane (e.g. Henkel Bronidox L) may be added to the aqueous formulation. The content of such preservatives is 2% by weight or less based on the total weight.

Suitable antifreezes are, for example, monohydric or polyhydric alcohols, glycol ethers or ureas, in particular calcium chloride, glycerol, isopropanol, propylene glycol monomethyl ether, di- or tripropylene glycol monomethyl ether or cyclohexanol have. The content of such antifreeze is 20% or less based on the weight of the total formulation.

The adhesive may be inorganic or organic, and they may be mixed. Suitable tackifiers include, for example, aluminum silicates, xanthans, methylcelluloses, polysaccharides, alkaline earth metal silicates, gelatin and poly (vinyl alcohol), for example Benton® EW, Veegum®. ), Rodopol (registered trademark) 23 or Kelzan (registered trademark) S. Their content is from 0 to 0.5% by weight, based on the weight of the total formulation.

Examples of the component capable of increasing the density of the aqueous phase include water-soluble salts and ammonium salts of alkali metals and alkaline earth metals or mixtures thereof, and preferably potassium chloride. The amount of salt depends on the specific gravity of the aqueous phase when contained and is such that the density is 1.05 to 1.45 kg / l, preferably 1.10 to 1.40 kg / l, most preferably 1.15 to 1.35 kg / l. Most preferred is an amount such that upon addition, the density of the aqueous phase can be made approximately equal to the density of the organic phase.

The invention also relates to a process for the preparation of the microcapsule dispersion according to the invention, which first prepares a crude preemulsion of an organic phase and an aqueous phase (without diamine), and then preferably this is a continuous mixer (e.g. rectification). A mixer, a colloid mill with which it is engaged, etc.) to apply shear force. The fine emulsified oil droplets required for subsequent microcapsule formation are not formed until this stage. Finally, curing can be carried out by adding diamine, if appropriate, and then carrying out the polymerization reaction with the entire volume of material.

This method can be performed semi-automatically on a laboratory scale and on a manufacturing scale.

The following examples are intended to illustrate the invention rather than to limit the invention.

A. Formulation Example

Examples 1-5 (Experimental Scale Experiment)

A solution containing 27 kg of industrial endosulfane and 23 kg of Solveso 200 was prepared in a 200-l stirred tank equipped with a fixed shaker, which was transferred to a storage container. Each aqueous phase (see Table 1 for the compositions of the individual examples) was prepared by filling the same stirring tank with water and adding each adjuvant with stirring. The mixture was kept stirring until the mixture was completely dissolved. The speed of the shaker was then increased to 70 rpm and 1 kg of borate M 200 and the freshly prepared mixture of organic phase prepared as described above were quickly added.

After further stirring for a while, the shaker was stopped and the resulting yellow crude emulsion was transferred to a storage vessel through a colloid mill with which it was engaged, formed in a light fine emulsion, the diameter of their droplets being 2-15 μm, This diameter then depends on the setting of the colloid mill with which it is engaged. This fine emulsion was transferred back to the stirring tank and the shaker started again at 70 rpm. 2.5 kg of aqueous hexamethylene solution at 40% concentration were added and the mixture was stirred for an additional 4 hours at 30 rpm.

The average diameter of the microcapsules obtained in the dispersion depends not only on the composition of the formulation but also on the setting of the rotational speed of the rotator in the mill and the setting of the spacing (ie "grinding space") between the rotator and the stator. This is described in more detail in Table 2 below. The reported viscosity was measured using a rotary viscometer.

Example 6

Microcapsule dispersions were prepared in the same manner as in Examples 1 to 5, except that a continuous mixing step was not provided. The water phase is 2.1 kg of mowiol 3/83 in 36.8 g of water, 1.8 kg of Pluronic F 87, 0.5 kg of Mowet D425, 4 kg of industrial glycerol (86.5% purity) and 100 g of Rhodopol 23 and mergal K 9 N 100 g was included. The water phase was poured into a stirring tank equipped with a fixed shaker and the organic phase of 27 kg of industrial endosulfane, 24 kg of Solvesso 200 and 1 kg of prepolymer borate M220 was poured through a drum-type slope while stirring at room temperature. After stirring for 30 minutes, 2.5 kg of aqueous 40% aqueous hexamethylenediamine solution was added and stirred for an additional 4 hours.

Microcapsules having an average diameter of 14.9 μm were prepared in this manner.

Example 7

A microcapsule dispersion was prepared as prepared in Example 6 except that a propeller shaker was used instead of the fixed shaker. Under the same conditions, microcapsules having a diameter of 4.1 mu m were prepared.

Example 8 (comparative example)

For these microcapsule experiments, the prepolymers used were 8 moles of tolylene diisocyanate in a 3: 1: 1 molar ratio of hexane-1,2,6-triol: butane-1,3-diol: poly (propylene glycol ) Prepared by reacting with 1000 and dissolved in a 1: 1 mixture of n-butyl acetate and xylene for future use, wherein the prepolymer is present at a concentration of 50% (as described in DE A 2 757 017). do.

Microcapsule dispersions were prepared as prepared in Example 1, except that 36.4 parts of water and 3 parts of the prepolymer solution described above were used and no diamine was used to cure. In addition, the mixture was stirred for an additional 15 hours at room temperature. The average diameter of the microcapsules of the resulting dispersion was 17 μm and the viscosity in a rotary viscometer was 350 mPa at a shear rate of 144 / sec.

Examples 9, 10 and 11

Each microcapsule dispersion was prepared on a laboratory scale using the formulations of Examples 1, 3, and 5 by filling with 46.5 parts of the aqueous phase described above and introducing 51 parts of the complete organic phase into the aqueous phase while stirring at 300 rpm. The shaker was then set at 2000 rpm and stirring continued at 2000 rpm for 30 seconds.

The rotational speed was reduced to 300 rpm and 2.5 parts of 40% hexamethylenediamine aqueous solution was added and the mixture was stirred for a further 1 minute. The rotation speed was finally reduced to an additional 50 rpm and stirring continued for 4 hours.

The results are shown in Table 3 below.

B. Biological Examples

Example 12 Initial Action and Duration of Action on Apis fabae

Each of the soybean crops was sprayed with an aqueous dilution of the specified formulation until flowing, allowing the aphids to transfer shortly or three days after drying.

Evaluation:% mortality at 7 days after invasion.

Example 13: Initial Action and Duration of Action on Heliothis virescens

Aqueous dilutions of each specified formulation were sprayed onto the cotton crop with a coating volume of 200 liters of spray per ha. After drying, either immediately or after 4 days and after 7 days invaded with larvae of gray tobacco moth (results are described in Table 5 below). (Evaluation:% mortality at 4 days after invasion)

Greenhouse experiments have demonstrated that the microcapsule formulations according to the invention are at least identical to commercially available EC formulations in terms of initial action and duration of action.

C. Toxicity Test

Example 14:

Microcapsules having an average capsule diameter of 14.9 μm were prepared as described in Example 6.

LD ₅₀ of female rats: 530 mg / kg body weight

Example 15

Microcapsules having an average capsule diameter of 4.1 μm were prepared as in Example 7.

LD ₅₀ of female rats: 315 mg / kg body weight

Example 19

Example 20

Claims (10)

The dispersed microcapsules include an endosulfane, an organic solvent or solvent mixture, and an encapsulating material based on an isocyanate prepolymer, the aqueous phase representing the medium of the dispersion comprises a surfactant with or without other formulation aids, At least 20 to 40% by weight of the endosulfane, 10 to 35% by weight of the organic solvent or solvent mixture, and 0.5 to 5% by weight of the isocyanate prepolymer, selected from the group consisting of emulsifiers and dispersants 0.2 to 5% by weight of one or more surfactants, and a water-soluble inorganic salt selected to have a density of 1.05 to 1.45 kg / L of the aqueous phase. Aqueous Endosulfane Microcapsule Dispersion. The method of claim 1, A microcapsule dispersion, which is an oil-soluble industrial mixture product of polyisocyanates based on condensates of aniline and formaldehyde that is not an isocyanate prepolymer. The method according to claim 1 or 2, Microcapsule dispersions which form capsule forming materials by curing the isocyanate prepolymers in the presence of water at 0-95 ° C., preferably 20-65 ° C., or with the required amount of diamine. The method according to any one of claims 1 to 3, 1 selected from the group consisting of encapsulants, emulsifiers and dispersants, 20 to 35% by weight endosulfan, 15 to 30% by weight organic solvent or solvent mixture, and 1 to 2% by weight isocyanate prepolymer, based on the weight of the total dispersion Microcapsule dispersions containing 0.5 to 2% by weight of at least one surfactant. The method according to any one of claims 1 to 4, A microcapsule dispersion in which a capsule forming material is formed by curing an isocyanate prepolymer with diamine no more than three times the stoichiometric amount of the isocyanate prepolymer. The method according to any one of claims 1 to 5, Microcapsule dispersion having a water phase density of 1.05 to 1.45 kg / L. The method according to any one of claims 1 to 6, Microcapsule dispersion having a water phase density of 1.10 to 1.40 kg / L. The method according to any one of claims 1 to 7, Microcapsule dispersion having a water phase density of 1.15 to 1.35 kg / L. The method according to any one of claims 1 to 8, Microcapsule dispersion comprising calcium chloride as a water-soluble inorganic salt. A crude pre-emulsion of an organic phase and an aqueous phase, which is then subjected to shear forces and to curing the fine emulsion obtained with the entire volume of material with or without diamine. A method for preparing a microcapsule dispersion according to claim 1.