Microcapsule pesticide composition

Abstract

To provide a microcapsule agrochemical composition, which secures safety of a worker who sprays the agrochemical and stability of the formulation, where an initial effect by disintegration or elution for achieving a sufficient effect against pest insects and sufficient strength and stability of microcapsules are maintained.SOLUTION: Microcapsules having a volume median diameter of 1 to 50 μm and a film thickness of 5 to 50 nm are prepared through an O / W emulsion dispersing step using a specific dispersant. Thereby, a high rate of inclusion in capsules, rapid releasability, and strength and stability of capsules are achieved.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to the field of pesticide formulations for controlling pests, and more particularly to the field of microcapsule pesticide formulations.

Background Art

[0002] Currently, various pesticides are being used worldwide for the purpose of controlling pests that damage crops. Pesticides are essential products in modern times because they enhance the value of crops and enable the sustainable provision of safe crops to consumers. In recent years, exposure of workers during pesticide spraying has become a problem, and the Ministry of Agriculture, Forestry and Fisheries has implemented guidelines regarding worker exposure as law. As a result, new standards have been established for worker exposure during pesticide spraying, and in the case of highly toxic pesticides, there is a possibility that the usage amount will be reduced or they will become unusable. For this reason, farmers are concerned that the pesticides available for use on crops are decreasing, and there is a risk that they will not be able to maintain the quality and value of their crops.

[0003] The use of microcapsule formulations can be considered as a countermeasure against worker exposure to pesticides. Since the active ingredient of the pesticide in the microcapsule formulation is encapsulated in a membrane, even if a worker is exposed during spraying, direct contact can be avoided, and it can be expected to have low toxicity and high safety. In addition, since the disappearance and decomposition of the active ingredient after spraying are delayed and the residual effect is extended, long-term control efficacy can be expected, which leads to labor savings for farmers, making it a very useful pesticide formulation. However, in order to exhibit stable control efficacy, a detailed design for controlling the encapsulation and release of the active ingredient of the pesticide in the microcapsule formulation is required.

[0004] In Patent Document 1, a microcapsule agent with excellent initial insecticidal activity and long-term residual efficacy has been proposed by mixing two types of microcapsules with different film thicknesses. However, the microcapsule agent is manufactured by the In-Situ method rather than the interfacial polymerization method, and the film is composed of a very hard melamine resin. In addition, the microcapsule agent with a thin film thickness in the literature is excellent in initial residual efficacy, but more than 30% of the residual efficacy is confirmed even 14 days after spraying, and there are concerns about residues depending on the active ingredient. Moreover, the pesticide active ingredient is limited to pyrethroids only, and it is not effective for all active ingredients. In Patent Documents 2 to 4, a method has been proposed to control the elution of the pesticide active ingredient encapsulated in the microcapsule by adding a surfactant or the like to the diluent without changing the composition of the microcapsule. However, 0.1% of the surfactant is added to 1 L of the 1000-fold diluted solution of the formulation, and since the amount of the formulation and the surfactant is the same, the amount is too large to be added as a surfactant in the formulation. In addition, when spraying pesticides, mixing of pesticide formulations and the use of a spreading agent, which is a formulation mainly composed of a surfactant, are generally carried out. Therefore, the elution control when pesticides are used in combination becomes unclear and is not useful. Moreover, the pesticide active ingredient is limited to pyriproxyfen, and it is not effective for all pesticide active ingredients.

[0005] Patent Document 5 reports that even when the microcapsules are physically impacted, such as when transferring a microcapsule aqueous suspension composition composed of the volume particle diameter of a specific particle size range containing a pesticide active ingredient by a pump or spraying using a chemical liquid sprayer, the microcapsules are difficult to be destroyed. However, the strength of the microcapsules is greatly affected by the film thickness and the formulation of the composition, and it is expected that the impact will also vary depending on the nozzle diameter and spraying method of the pump or chemical liquid sprayer used.

[0006] Microcapsule formulations are pesticide formulations that exhibit the desired control effect by sensitizing target pests to the pesticide components encapsulated in the film through rupture by external factors or self-elution of the active ingredient from within. In order to achieve a rapid initial effect with microcapsule formulations, a thin film thickness is required to facilitate rupture of the capsule film. However, there are concerns that a sufficient encapsulation rate of the pesticide component may not be obtained, or that the capsule film may rupture during the spraying operation. On the other hand, to provide residual efficacy, it is necessary to increase the film thickness of the capsule film. However, depending on the crop, pesticide residues can become a problem. Therefore, in the formulation design of microcapsule formulations for foliar spraying, it is important to design the elution mechanism of the encapsulated pesticide, control the elution rate of the encapsulated pesticide, and appropriately select the encapsulated pesticide, etc. In particular, foliar sprays often require an initial effect, but due to the reasons mentioned above, microcapsule formulations cannot achieve a rapid initial effect, resulting in insufficient efficacy or residual active ingredient.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0008] Exposure of workers to pesticides during spraying has become a problem, and there is a demand for pest control pesticides that can be safely sprayed by pesticide applicators. In addition, a pest control pesticide formulation that exhibits sufficient initial control efficacy in the early stage of pesticide spraying is required. For this reason, as a microcapsule formulation that can reduce the problem of spraying exposure of workers, a microcapsule formulation that can withstand the pesticide spraying pressure and has a high encapsulation rate of the active ingredient, while quickly releasing the active ingredient after spraying to exhibit the initial control efficacy is necessary. The present invention aims to solve the above problems. That is, the present invention uses microcapsule formulation technology, and in a microcapsule pesticide composition that ensures the safety and formulation stability of pesticide applicators, the initial effect by disintegration or elution to achieve a sufficient effect on pests and the strength and stability of the microcapsules The problem is to provide a microcapsule pesticide composition by sufficiently maintaining the above.

Means for Solving the Problems

[0009] As a result of intensive research to solve the above problems, the present inventors prepared microcapsules having a volume median diameter of 1 to 50 μm and a film thickness of 5 to 50 nm through an O / W emulsion dispersion step using a specific dispersant, and found that they have a high encapsulation rate in the capsules, rapid release properties, and can achieve the desired effects, thus completing the present invention. That is, the gist of the present invention is as follows [1] to

[11] .

[0010] [1] A microcapsule pesticide composition comprising a microcapsule containing a pesticide active ingredient having a water solubility of 1000 ppm or less at 20°C and an aqueous phase, The volume median diameter of the microcapsule is 1 to 50 μm, the film thickness of the microcapsule defined by the following formula (I) is 5 to 50 nm, The microcapsule is a microcapsule whose film is composed of a polyurea film and / or a polyurethane film having an aromatic ring structure, An aqueous phase contains an aromatic polymer salt and / or an inorganic salt selected from the group consisting of sodium chloride, potassium chloride, disodium hydrogen phosphate, sodium dihydrogen phosphate, dipotassium hydrogen phosphate, and potassium dihydrogen phosphate as a dispersant. A microcapsule pesticide composition. Equation (I): Film thickness (nm) = (weight of film material / weight of core material) × (density of core material / density of film material) × (volume median diameter / 6) × 1000 [2] The microcapsule pesticide composition according to [1] above, wherein the ratio of the volume median diameter to the film thickness of the microcapsules (volume median diameter / film thickness) is 100 to 2000. [3] The microcapsule pesticide composition according to [1] or [2] above, wherein the aromatic polymer salt is at least one selected from the group consisting of lignin sulfonate, alkyl naphthalene sulfonate, and styrene maleate. [4] The microcapsule pesticide composition according to any one of [1] to [3] above, wherein the content of the dispersant in the microcapsule pesticide composition is 0.01 to 5% by mass. [5] The microcapsule pesticide composition according to any one of [1] to [4] above, wherein the pesticide active ingredient is an organophosphorus insecticide or a carbamate insecticide. [6] The microcapsule pesticide composition according to any one of [1] to [5] above, wherein the pesticide active ingredient is O,O-diethyl-O-2-isopropyl-6-methylpyrimidin-4-yl-phosphorothioate (common name: diazinon), (RS)-O-2,4-dichlorophenyl = O-ethyl = S-propyl = phosphorodithioate (common name: prothiofos), S-α-ethoxycarbonylbenzyl = O,O-dimethyl = phosphorodithioate (common name: PAP, phenthoate), or 2-sec-butylphenylmethylcarbamate (common name: BPMC, phenobucarb).

[0011] [7] A method for producing a microcapsule pesticide composition, comprising: (1)(a) An oil phase containing a pesticidal active ingredient and a polyisocyanate having an aromatic ring structure, wherein the content of the polyisocyanate having the aromatic ring structure is 3% by mass or less, and (b) An aqueous phase containing an aromatic polymer salt and / or an inorganic salt selected from the group consisting of sodium chloride, potassium chloride, disodium hydrogen phosphate, sodium dihydrogen phosphate, dipotassium hydrogen phosphate, and potassium dihydrogen phosphate as a dispersant, and mixing the two phases; (2) A step of dispersing the mixture to prepare an O / W emulsion; (3) A step of adding a polyamine and / or a polyol to prepare microcapsules. A method for producing a microcapsule pesticide composition according to the above steps. [8] The method for producing a microcapsule pesticide composition according to [7] above, wherein the volume median diameter of the microcapsules is 1 to 50 μm and the film thickness of the microcapsules defined by the following formula (I) is 5 to 50 nm. Formula (I) Film thickness (nm) = (film substance weight / core substance weight) × (core substance density / film substance density) × (volume median diameter / 6) × 1000 [9] The method for producing a microcapsule pesticide composition according to [7] or [8] above, wherein the ratio of the volume median diameter to the film thickness of the microcapsules (volume median diameter / film thickness) is 100 to 2000.

[10] The method for producing a microcapsule pesticide composition according to any one of [7] to [9] above, wherein the aromatic polymer salt is at least one selected from the group consisting of lignin sulfonate, alkyl naphthalene sulfonate, and styrene maleate.

[11] The method for producing a microcapsule pesticide composition according to any one of [7] to

[10] above, wherein the content of the dispersant in the microcapsule pesticide composition is 0.01 to 5% by mass. [Advantages of the Invention]

[0012] The microcapsule pesticide composition of the present invention has a high encapsulation rate of the pesticide active ingredient, and can ensure the strength of the film from the microcapsules, so that the pesticide active ingredient is not directly exposed to the spray applicator, and thus the safety is also ensured. In addition, the release of the pesticide active ingredient after spraying is rapid, and both the initial effect and crop residue, which have been problems of microcapsule formulations, can be satisfied. That is, it is possible to provide a microcapsule pesticide formulation that can achieve both high capsule encapsulation property at the time of spraying and immediate release property after spraying for the pesticide active ingredient.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0014] The microcapsule pesticide composition according to the present invention will be described below. In the present invention, there is no particular limitation as long as it is a compound for pest control having a water solubility of 1000 ppm or less at 20°C as an agrochemical active ingredient, and it can be applied. It is preferable to apply a compound used as an active ingredient of an insecticide. Specific examples of applicable insecticides include diazinon, prothiofos, cyanophos, fenitrothion, fenthion, pirimiphos-methyl, isoxathion, chlorpyrifos, chlorpyrifos-methyl, malathion, phenthoate, dimethoate, hosalon, methidathion, acephate, trichlorfon, EPN, ethylthiometon, profenofos, dichlorvos, propetamphos, fosthiazate, imicyafos, kazusaphos and other organophosphorus insecticides, carbaryl, BPMC, MIPC,Carbamate insecticides such as carbosulfan, benfuracarb, methomyl, oxamyl, thiodicarb, and alanicarb; pyrethroid insecticides such as pyrethrin, allethrin, permethrin, cypermethrin, cyhalothrin, lambda-cyhalothrin, tralomethrin, fenpropathrin, bifenthrin, fenvalerate, flucythrinate, flubalinate, acrinathrin, cycloprothrin, tefluthrin, etofenprox, silafluofen, cyphenothrin, phenothrin, propargite, resmethrin, alpha-cypermethrin, flucythrinate, silafluofen, cyhalothrin, flumethrin, fenclothrin, silafluofen; neonicotinoid insecticides such as imidacloprid, clothianidin, thiamethoxam, acetamiprid, thiacloprid, nitenpyram; and other chromafenozide, spinosad, spinetoram, diflubenzuron, teflubenzuron, lufenuron, flufenoxuron, chlorfluazuron, novaluron, tebufenozide, methoxyfenozide, silafluofen, pyriproxyfen, buprofezin, pymetrozine, pyrifluquinazon, flonicamid, pyridalyl, chlorfenapyr, tolfenpyrad, diafenthiuron, metaflumizone, indoxacarb, metaldehyde, tetradifon, propargite, amitraz, phenothiocarb, hexaflumuron, dienochlor, fenpyroximate, tebufenpyrad, pyridaben, pyrimidifen, chlorphentermine, etoxazole, bufencarb, acequinocyl, cyenopyrafen, piflubumide, flupyradifurone, spirodiclofen, spirotetramat, spirotetramat, spirotetramat, spirotetramat, spirotetramat, D-D, DCIP, methyl isothiocyanate, sodium carbamate, emamectin, BT, flometokine, hexaflumuron, hydramethylnon, sulfluramid, flupyradifurone, emamectin, lepimectin, abamectin, milbemectin, etc. If there are no problems with the mixing stability, two or more of these can be used., Among them, considering the significance of formulating as a microcapsule formulation for a spray agent, an organophosphorus insecticide is preferable, and diazinon (chemical name: O,O-diethyl-O-2-isopropyl-6-methylpyrimidin-4-yl-phosphorothioate), prothiofos ((RS)-O-2,4-dichlorophenyl = O-ethyl = S-propyl = phosphorodithioate), fenthoate, PAP (S-α-ethoxycarbonylbenzyl = O,O-dimethyl = phosphorodithioate), or BPMC (phenobucarb chemical name: 2-sec-butylphenylmethylcarbamate) is particularly preferable. As the content of the pesticidal active ingredient, 0.1 to 50 parts by mass is desirable, and particularly preferably 1 to 50 parts by mass with respect to 100 parts by mass of the pesticide composition.

[0015] In the present invention, the microcapsules encapsulating the pesticidal active ingredient are not particularly limited, and microcapsules prepared by known techniques can be used. A preferable method for preparing microcapsules is a chemical preparation method. Particularly preferably, since the production is easy, encapsulation can be performed in a short time, and the particle size can be easily controlled, microcapsules prepared by an interfacial polymerization method can be mentioned.

[0016] The interfacial polymerization method is, for example, a method of polymerizing a polyisocyanate and a polyol at the two-phase interface of an oil phase - water phase to form a film made of polyurethane, a method of interfacial polymerization of a polyisocyanate and a polyamine to form a film made of polyurea, etc. are used. In the present invention, the method for preparing microcapsules can be appropriately selected depending on the type of the active ingredient, the purpose of use or the application, etc., but the interfacial polymerization method is particularly preferably used. In the present invention, microcapsules composed of a polyurea film and / or a polyurethane film and prepared by the interfacial polymerization method are preferable. Hereinafter, the microcapsule pesticide composition according to the present application will be described in more detail based on the production method of the microcapsules prepared by the interfacial polymerization method.

[0017] In the interfacial polymerization method, first, an oil phase containing a pesticidal active ingredient and an oil-soluble film-forming component is prepared. In the present application, examples of the oil-soluble film-forming component include polyisocyanates, and in the present invention, polyisocyanates having an aromatic ring structure in the molecule are used. Examples of the polyisocyanate having an aromatic ring structure include aromatic polyisocyanates such as diphenylmethane diisocyanate and toluene diisocyanate, and aromatic aliphatic polyisocyanates such as polymethylene polyphenyl isocyanate, xylylene diisocyanate, and tetramethylxylylene diisocyanate. Further, derivatives of these polyisocyanates, such as dimers, trimers, biurets, allophanates, carbodiimides, uretdiones, oxadiazinetriones, etc., and modified products of these polyisocyanates, such as polyol-modified polyisocyanates obtained by previously reacting with low molecular weight polyols such as trimethylolpropane or high molecular weight polyols such as polyether polyols, are also included. These oil-soluble film-forming components may be used alone or in combination of two or more. Optionally, an aliphatic polyisocyanate such as hexamethylene diisocyanate, an alicyclic polyisocyanate such as isophorone diisocyanate, a hydrogenated xylylene diisocyanate, or a hydrogenated diphenylmethane diisocyanate may be used in combination.

[0018] When the polyisocyanate is a liquid at room temperature and the pesticidal active ingredient can be dissolved or dispersed therein, or when the pesticidal active ingredient is a liquid at room temperature and the polyisocyanate can be dissolved or dispersed therein, the oil phase can be prepared by blending these. Alternatively, for example, the oil phase can be prepared by dissolving or dispersing the pesticidal active ingredient and the polyisocyanate, if necessary, using an organic solvent. The organic solvent is not particularly limited as long as it can dissolve or disperse the pesticidal active ingredient and the polyisocyanate, and can be appropriately selected according to the type of the active ingredient. It is preferable to use an aromatic organic solvent. Examples thereof include alkylbenzenes, alkylnaphthalenes, alkylphenols, phenylxylylethane, and the like. More specifically, various commercially available organic solvents obtained from petroleum fractions, such as Solvesso 100 (manufactured by ExxonMobil Corporation), Solvesso 150 (manufactured by ExxonMobil Corporation), Solvesso 200 (manufactured by ExxonMobil Corporation), Solvesso 150ND (manufactured by ExxonMobil Corporation), Solvesso 200ND (manufactured by ExxonMobil Corporation), Swasol 1000 (manufactured by Maruzen Oil Co., Ltd.), Swasol 1500 (manufactured by Maruzen Oil Co., Ltd.), Swasol 1800 (manufactured by Maruzen Oil Co., Ltd.), and the like can be mentioned, and Solvesso 150ND is particularly preferable. These organic solvents may be used alone or in combination of two or more.

[0019] The blending ratio of the pesticidal active ingredient and the organic solvent is, for example, 25 to 100 parts by mass, preferably 50 to 95 parts by mass of the pesticidal active ingredient and 0 to 75 parts by mass, preferably 5 to 50 parts by mass of the organic solvent with respect to a total of 100 parts by mass of the oil phase.

[0020] In addition, the blending ratio of the polyisocyanate having an aromatic ring structure can be in the range of 0.01 to 3 parts by mass with respect to 100 parts by mass of the oil phase, but it is preferably in the range of 0.02 to 2 parts by mass. When the blending ratio of the polyisocyanate increases, the film of the obtained microcapsules may become too thick. On the other hand, when the blending ratio of the polyisocyanate decreases, the film of the microcapsules may not be formed.

[0021] In addition, as components that can be added to the oil phase, stabilizers, surfactants, plasticizers, gelling agents, etc., which are non-reactive with the polyisocyanate in the oil phase and do not inhibit the interfacial polymerization reaction, can be used. Examples of stabilizers include quenchers, radical scavengers, ultraviolet absorbers, antioxidants, etc. Examples of quenchers include K-800 (trade name, made by Takemoto Yushi Co., Ltd.), epoxidized soybean oil, epoxidized linseed oil, octyl epoxidized fatty acid, butyl epoxidized fatty acid, methyl epoxidized nuca fatty acid, epoxidized rapeseed oil, etc., and K-800 is particularly preferred. Examples of radical scavengers include vitamin E, vitamin C, ubiquinol, uric acid, flavonoid, tannin, sesaminol, curcumin, etc. Examples of ultraviolet absorbers include benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, etc. Examples of antioxidants include phenolic antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, etc. Also, two or more of these stabilizers may be mixed and used at any ratio. The proportion of the stabilizer is preferably in the range of 0 to 10 parts by mass, and more preferably in the range of 0.1 to 5 parts by mass, based on 100 parts by mass of the oil phase.

[0022] Examples of surfactants include nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl aryl ether, polyoxyethylene alkyl phenol formalin condensate, polyoxyethylene castor oil derivative, polyoxyethylene fatty acid ester, higher fatty acid glycerin ester, polyoxyethylene fatty acid amide, alkylol amide, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyoxyethylene polyoxypropylene block polymer, sucrose fatty acid ester, polyglycerin fatty acid ester, etc. Also, two or more of these surfactants may be mixed and used at any ratio. The proportion of the surfactant is preferably in the range of 0 to 10 parts by mass, based on 100 parts by mass of the oil phase.

[0023] Examples of plasticizers include phthalic acid esters, adipic acid esters, polyesters, phosphoric acid esters, citric acid esters, sebacic acid esters, maleic acid esters, etc. Also, two or more of these plasticizers may be mixed and used at any ratio. The proportion of the plasticizer is preferably in the range of 0 to 10 parts by mass with respect to 100 parts by mass of the oil phase. Examples of the gelling agent include waxes and resins, and various waxes such as hydrogenated castor oil, 12-hydroxystearic acid, sorbitan fatty acid ester, polyglycerin fatty acid ester, stearic acid, stearyl alcohol, isopropyl myristate, glycol fatty acid ester, montan wax, paraffin wax, candelilla wax, carnauba wax, rice wax, hydrogenated beef tallow, extremely hydrogenated beef tallow, hydrogenated soybean oil, beeswax, lanolin, spermaceti, ceresin, shellac, etc. Further, these gelling agents may be used by mixing two or more kinds thereof at an arbitrary ratio. The proportion of the gelling agent is preferably in the range of 0 to 10 parts by mass with respect to 100 parts by mass of the oil phase.

[0024] The preparation of microcapsules by the interfacial polymerization method can be carried out by mixing the oil phase prepared by mixing the above oil phase components with the aqueous phase component, stirring to disperse fine oil droplets in the aqueous phase to prepare an oil-in-water (O / W) emulsion, and then carrying out an interfacial polymerization step. The aqueous phase is prepared mainly using a medium immiscible with the above oil phase. Water is used as the medium, and it can be prepared by adding a dispersant to this aqueous medium. The dispersant also has a function of stabilizing the dispersion system so that there is no sedimentation and aggregation in the microcapsule dispersion liquid after the microcapsules are produced. In the present invention, by using an aqueous phase containing an aromatic polymer salt or a specific inorganic salt as a dispersant to prepare microcapsules, it is possible to prepare a microcapsule dispersant that has a high encapsulation rate of the pesticidal active ingredient and excellent storage stability while being a thin-film microcapsule. Further, in addition to the aromatic polymer salt or the specific inorganic salt, an aqueous phase containing a water-soluble polymer dispersant may be used. In the microcapsule pesticide composition of the present invention, those applied as a dispersant are aromatic polymer salts and / or one or more inorganic salts selected from the group consisting of sodium chloride, potassium chloride, disodium hydrogen phosphate, dipotassium hydrogen phosphate, sodium dihydrogen phosphate, and potassium dihydrogen phosphate. The aromatic polymer salt and the inorganic salt may be used alone or in combination.

[0025] The aromatic polymer salt is a salt of a polyanionic polymer having an aromatic ring structure in the molecule. For example, lignin sulfonate, alkyl naphthalene sulfonate, and styrene maleate can be mentioned. Alkali metal salts, alkaline earth metal salts, or ammonium salts of these polyanionic polymers are used. The aromatic polymer salt may be used alone as a dispersant or in combination with a water-soluble polymer dispersant described later. The blending ratio of the aromatic polymer salt is preferably 0.1 part by mass or more and 10 parts by mass or less, more preferably 0.5 part by mass or more and 5 parts by mass or less, based on 100 parts by mass of the aqueous phase. The larger the concentration of the dispersant, the finer the volume median diameter can be obtained. Also, it is preferably used in an amount of 0.01 part by mass or more and 10 parts by mass or less, more preferably 0.01 part by mass or more and 5 parts by mass or less, based on 100 parts by mass of the microcapsule pesticide composition according to the present application.

[0026] The water-soluble polymer dispersant that may be contained in the aqueous phase is used as a dispersion aid and is used to maintain the stability of the O / W dispersion system. Examples of the water-soluble polymer dispersant include polyvinyl alcohol, polyvinyl pyrrolidone, vinyl pyrrolidone-vinyl acetate copolymer, methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, polyacrylic acid, polyacrylic acid metal salts, etc., and polyvinyl alcohol is more preferred. The blending ratio of the water-soluble polymer dispersant is preferably from 0.1 part by mass to 20 parts by mass, more preferably from 0.5 part by mass to 10 parts by mass, and still more preferably 1 part by mass or less, based on 100 parts by mass of the aqueous phase. Further, the use amount is preferably from 0.1 part by mass to 15 parts by mass, more preferably from 0.5 part by mass to 10 parts by mass, based on 100 parts by mass of the microcapsule pesticide composition according to the present application.

[0027] The inorganic salt is used in combination with the water-soluble polymer dispersant. The inorganic salt has a function of stabilizing the function of the water-soluble polymer dispersant and preventing the components of the oil phase from dissolving into the aqueous phase. Examples of the inorganic salt used in the present application include sodium chloride, potassium chloride, disodium hydrogen phosphate, dipotassium hydrogen phosphate, sodium dihydrogen phosphate, and potassium dihydrogen phosphate. These inorganic salts may be used alone or in combination of two or more. As a method of use, a predetermined amount of the inorganic salt is dissolved in the aqueous phase together with the water-soluble polymer dispersant and used. Incidentally, these dispersants also have a function of stabilizing the dispersion system so that sedimentation and aggregation do not occur in the microcapsule dispersion liquid after the microcapsules are produced. The blending ratio of the inorganic salt is preferably from 0.01 part by mass to 20 parts by mass, more preferably from 0.5 part by mass to 10 parts by mass, based on 100 parts by mass of the aqueous phase. Further, the use amount is preferably from 0.01 part by mass to 15 parts by mass, more preferably from 0.01 part by mass to 10 parts by mass, and still more preferably from 0.01 part by mass to 5 parts by mass, based on 100 parts by mass of the microcapsule pesticide composition according to the present application.

[0028] Examples of other optional components to be added to the aqueous phase include an antifoaming agent, a pH adjuster, a surfactant, etc., which are added to efficiently disperse the oil phase and the aqueous phase. As the antifoaming agent, a silicone emulsion is generally used, and particularly ((trade name), Antifoam E-20, manufactured by Kao Corporation) is preferable. The blending ratio of the antifoaming agent is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the aqueous phase. As the pH adjuster, inorganic salts such as sodium hydroxide, potassium hydroxide, disodium hydrogen phosphate, sodium dihydrogen phosphate, dipotassium hydrogen phosphate, and potassium dihydrogen phosphate, and inorganic acids or organic acids such as hydrochloric acid, sulfuric acid, acetic acid, formic acid, citric acid, and phosphoric acid can be used. The blending ratio of the pH adjuster is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the aqueous phase. As the surfactant, nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl aryl ether, polyoxyethylene alkylphenol formalin condensate, polyoxyethylene castor oil derivative, polyoxyethylene fatty acid ester, higher fatty acid glycerin ester, polyoxyethylene fatty acid amide, alkylol amide, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyoxyethylene polyoxypropylene block polymer, sucrose fatty acid ester, and polyglycerin fatty acid ester, anionic surfactants such as polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl ether phosphate, polyoxyethylene alkyl aryl ether sulfate, polyoxyethylene alkyl aryl ether phosphate, and alkyl sulfosuccinate, and amphoteric surfactants such as betaine-type surfactants can be mentioned. Further, two or more of these surfactants may be mixed and used at an arbitrary ratio.

[0029] To blend the oil phase component into the aqueous phase component, a method can be adopted in which the oil phase component is added to the aqueous phase component and stirred and dispersed by a disperser such as a high-shear mixer, a homomixer, a desolver, a colloid mill, a homogenizer, or an ultrasonic stirrer until the oil phase becomes fine droplets under a constant temperature. At this time, for the management of preparing the particle size, there are the type of the disperser, the stirring speed, the stirring time, the temperature of the aqueous phase and the oil phase, and the pH of the aqueous phase. The optimum pH and temperature differ depending on the active ingredient to be dispersed. Specifically, under a constant temperature, the oil phase is added while stirring the aqueous phase with a disperser, and the stirring speed and the stirring time are controlled until the target volume median diameter is reached. The volume median diameter when the oil phase is dispersed in the aqueous phase becomes a value close to the volume median diameter after the final interfacial polymerization reaction. Examples of the stirrer include Hiscotron (manufactured by Microtech Nition Co., Ltd.) and T.K. Homomixer (manufactured by Primix Corporation). The stirring speed is preferably in the range of 100 to 10,000 rpm, more preferably 1,000 to 8,000 rpm. The stirring time is preferably in the range of 0.1 to 30 minutes, more preferably 0.5 to 15 minutes. By increasing the stirring speed, microcapsules with a small volume median diameter can be prepared. Also, by lengthening the stirring time, microcapsules with a small volume median diameter can be prepared. The optimal temperature of the aqueous phase and the oil phase varies depending on the physical properties of the active ingredient to be dispersed. Generally, a range of 0.1 to 50°C is preferred, and a range of 1 to 30°C is more preferred. The optimal pH of the aqueous phase varies depending on the physical properties of the active ingredient to be dispersed. Generally, a pH that contributes to the stability of the active ingredient is preferred.

[0030] A method for preparing the microcapsules according to the present application by the interfacial polymerization method includes a method in which an oil phase containing a pesticide active ingredient and a polyisocyanate having an aromatic ring structure is dispersed in an aqueous phase containing a dispersant, and then a curing agent, which is a water-soluble film-forming component, is added dropwise and mixed. The curing agent as the water-soluble film-forming component is a polyamine and / or polyol that reacts with the polyisocyanate having an aromatic ring structure to cause interfacial polymerization. That is, when polyamine is used as the curing agent, microcapsules with a polyurea film are prepared. On the other hand, when polyol is used, microcapsules with a polyurethane film are prepared. When both agents are used in combination, microcapsules with a film material in which polyurea and polyurethane coexist are prepared.

[0031] Examples of the polyamine used as the curing agent include ethylenediamine, propylenediamine, hexamethylenediamine, diaminotoluene, phenylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, piperazine, etc., and they may be used alone or as a mixture of two or more of them. Ethylenediamine and diethylenetriamine are particularly preferred.

[0032] Examples of the polyol used as the curing agent include ethylene glycol, propanediol, 1,4 - butanediol, 1,6 - hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, dipropylene glycol, cyclohexanedimethanol, glycerin, trimethylolpropane, polyethylene glycol, polypropylene glycol, etc., and they may be used alone or as a mixture of two or more of them. Diethylene glycol or propylene glycol is particularly preferred.

[0033] The curing agent is used as it is or as its aqueous solution. When making the curing agent into an aqueous solution, it is preferably used at a concentration of 50% by weight or less of the curing agent. The curing agent is dropped until the reactive groups of the film - forming component are approximately equal in equivalent amount to the reactive groups of the polyisocyanate (for example, when polyisocyanate and polyamine are used, the equivalent ratio of isocyanate groups / amino groups is approximately 1), and then subjected to the interfacial polymerization. By dropping the curing agent into an O / W emulsion in which fine oil droplets of an oil phase containing a pesticidal active ingredient and a polyisocyanate having an aromatic ring structure are dispersed in the aqueous phase component, the curing agent and the polyisocyanate react at the interface between the fine oil droplets of the oil phase component and the aqueous phase component, and a microcapsule membrane is formed by the interfacial polymerization reaction, and microcapsules encapsulating the active ingredient can be obtained as a dispersion in the aqueous phase. To promote this interfacial polymerization reaction, it is preferable to stir and react at a reaction temperature of 25 - 85°C, preferably 40 - 80°C, and a reaction time of 30 minutes - 24 hours, preferably 1 - 12 hours. Examples of the stirrer used for the mixing used to promote the interfacial polymerization reaction include a chemical mixer, a three-one motor, etc.

[0034] To the microcapsule dispersion obtained in this way, known additives such as a thickener, an antifreeze, a preservative, a specific gravity regulator, an osmotic pressure regulator, a pH adjuster, a stabilizer, a colorant, a fragrance, a surfactant, etc. may be appropriately blended as necessary. Examples of the thickener include natural polysaccharides such as xanthan gum, locust bean gum, xanthan gum, minerals such as magnesium aluminum silicate, bentonite, etc., semi-synthetic polysaccharides such as sodium carboxymethyl cellulose salt, and synthetic water-soluble polymers such as polyacrylate salts. Examples of the antifreeze include urea, or glycols such as propylene glycol, ethylene glycol, diethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, etc. Examples of the preservative include Proxel GXL(S) ((trade name) 1,2-benzisothiazolin-3-one, manufactured by Lonza Japan Co., Ltd.), 2-methyl-isothiazolin-3-one, formalin, etc., and Proxel GXL(S) is particularly preferred. Examples of the specific gravity regulator include water-soluble salts such as sodium sulfate. Examples of the osmotic pressure regulator include saccharides such as mannitol, glucose, sorbitol, etc., and inorganic substances such as sodium chloride, potassium chloride, etc. Examples of the pH adjuster include acids such as phosphoric acid, acetic acid, hydrochloric acid, citric acid, etc., and bases such as sodium hydroxide, potassium hydroxide, ammonia, etc. Examples of the stabilizer include BHT, copper oxide, etc. Examples of the colorant include tar dyes such as rhodamine B, yellow No. 4, blue No. 1, red No. 2, etc., and various dyes. Examples of the fragrance include esters such as ethyl acetoacetate, methyl anthranilate, and ethyl cinnamate; organic acids such as caproic acid and cinnamic acid; alcohols such as geraniol, cinnamic alcohol, citral, and decyl alcohol; aldehydes such as vanillin, piperonal, perilla aldehyde, and cinnamaldehyde; ketones such as maltitol and methyl β-naphthyl ketone; and menthols. As the surfactant, various dispersants for the purpose of dispersion stabilization can be used. These can be used alone or in combination of two or more, but those that do not affect the microcapsule composition are preferred, and thickeners, preservatives, and glycols are particularly preferred. These additives can be used in the range of 0 to 30% by mass.

[0035] The volume median diameter of the microcapsules applied in the microcapsule preparation according to the present invention greatly affects the exertion of the pest control efficacy. The volume median diameter here represents the average particle diameter based on volume, and when the cumulative curve is obtained with the total volume of the population as 100%, it refers to the particle diameter at the point where the cumulative curve reaches 50%. In the microcapsule pesticide composition of the present invention, the volume median diameter at the time of dispersion and of the microcapsules can be determined by measuring the size and its distribution state of the volume median diameter using, for example, a commercially available laser diffraction particle size distribution measuring device, specifically, SALD2200 (manufactured by Shimadzu Corporation). The microcapsule pesticide composition of the present invention has a volume median diameter of 1 to 50 μm. Since the nozzle diameter used at the time of spraying is fine for the pesticide preparation used as a spraying agent, it is desirable that the microcapsules have a small volume median diameter accordingly. More preferably, the volume median diameter is 4 to 45 μm, and still more preferably, it is 10 to 30 μm.

[0036] In the microcapsule pesticide composition of the present invention, the film thickness of the microcapsules is 5 to 50 nm. The film thickness of the microcapsules is the film thickness calculated by the following formula (I) described on page 66 of the Pesticide Formulation Guide (published by the Japan Plant Protection Association in 1997). Film thickness (nm) of formula (I) = (weight of film material / weight of core material) × (density of core material / density of film material) × (volume median diameter / 6) × 1000 In formula (I), the film material is a component used in the reaction of the interfacial polymerization method, and is a polyisocyanate such as aromatic isocyanate and aliphatic isocyanate, and a curing agent such as polyamine and polyol. The core material is a component other than the polyisocyanate contained in the oil phase, and specifically is a solvent such as a pesticide active ingredient and an aromatic organic solvent. These weights are the total weights of the respective components, and these densities use the density obtained by weight-averaging the densities of the respective components. Thereby, the film thickness of the microcapsules according to the present invention is defined. In the present invention, the film thickness is preferably 1 to 50 nm, more preferably 5 to 40 nm, and still more preferably 10 to 30 nm.

[0037] In addition, the microcapsule pesticide composition of the present invention preferably has a thin film thickness in order to aim at a rapid release of the active ingredient, and is preferably 100 to 2000 in terms of the index represented by (volume median diameter / film thickness). This index represents the relationship between the volume median diameter and the film thickness of the microcapsules that can withstand the pressure during spraying, exhibit the most effective insecticidal efficacy, and disappear from the environment quickly. In the present invention, (volume median diameter / film thickness) is preferably 200 to 1500, and more preferably 400 to 1000.

[0038] The microcapsule pesticide composition of the present invention is usually diluted 10 to 10,000 times with respect to the total weight of the active ingredient of the composition, and is directly treated by foliar spraying, soil mixing, soil perfusion treatment, etc. It is preferable to use water as the diluent. Alternatively, without performing the dilution operation, it is also possible to directly perform soil treatment as a microcapsule slurry without removing the dispersion medium which is the aqueous phase component used for microcapsule preparation. Alternatively, the dispersion medium can be removed and the microcapsules alone can be used for soil treatment. Further, for example, it may be formulated into a known dosage form such as a powder or a granule as appropriate.

[0039] The microcapsule pesticide composition of the present invention is mainly used as a pesticide for controlling pests occurring in fruit trees, tea trees, vegetables, and flowers. Examples of pests to be controlled include Momosina quinquemaculata, Nasihime shinku, Rhynchites heros, Monochamus alternatus, Rhynchites foveipennis, Rhynchites bacchus, larvae of Anomala cuprea, scale insects, aphids, larvae of Oulema oryzae, Psylla pyrisuga, Empoasca onukii, leafhoppers, Sitophilus spp., Umesirokaigarimushi, Empoasca vitis, Empoasca flavescens, Plutella xylostella, Aphis gossypii, Aphis craccivora, Thrips spp., Liriomyza huidobrensis, Liriomyza sativae, Tetranychus spp., Coccinella septempunctata larvae, Chrysomela populi, larvae of Phyllotreta striolata, Parasaissetia nigra, Blattella germanica, Blatta orientalis, nematodes, etc. The microcapsule pesticide composition of the present invention can achieve both the initial efficacy immediately after pesticide spraying and the appropriate residual efficacy thereafter.

[0040] As the mechanism by which the microcapsule formulation exerts a control effect on pests, there are a first mechanism in which the leakage of the pesticide active ingredient due to the physical destruction of the microcapsule causes contact with and absorption by the target pests, or a second mechanism in which the elution of the pesticide active ingredient from the microcapsule causes contact with and absorption by the target pests. Regarding pest control, when the size of the pest itself is large, the microcapsule can be destroyed by the movement and feeding of the target pest, and the effect is expressed by the first mechanism of action. On the other hand, when the size of the pest itself is small, the active ingredient eluted from the microcapsule contacts the minute pests and the effect is expressed. From the viewpoints of ensuring the stability of the active ingredient and the safety of the operator during spraying, a formulation in which the elution of the active ingredient from the microcapsule membrane is suppressed is desirable. Therefore, it is efficient to use a microcapsule containing a pest control active ingredient as a microcapsule formulation with an appropriate volume median diameter so as to suppress the elution of the drug immediately after spraying and to make it easy for the microcapsule to disintegrate and elute due to light or drying and be taken into the body of the target pest or adhere to the body surface. It is preferable to design such a microcapsule formulation. Generally, in order to extend the residual efficacy of microcapsule formulations, the film thickness of the microcapsules is increased to adjust the residual efficacy. However, when the residual efficacy is extended, the elution property of the active ingredient decreases, resulting in a decrease in the initial effect. On the other hand, when the film thickness is decreased, the elution property of the pesticidal active ingredient increases, the content of the free component of the active ingredient increases, and although the initial effect is ensured, the strength of the microcapsules becomes weak, the stability decreases, and problems such as an increase in the amount of the active ingredient outside the capsules in the formulation or breakage of the microcapsules due to the pressure during spraying occur. Therefore, it is necessary to design a microcapsule formulation that enhances the stability of the microcapsules while setting the film thickness of the microcapsules to be thin, and increases the contact amount between the active ingredient eluted from the microcapsules and the pests, thereby enhancing the insecticidal effect. The microcapsule pesticide composition according to the present invention adds an aromatic polymer salt and / or a specific inorganic salt as a dispersant during the microcapsule manufacturing process, so that even when the film thickness of the microcapsules is thin, the encapsulation rate of the active ingredient in the capsules is 95% or more. In addition, it is a formulation with excellent storage stability. Therefore, the initial effect on pests is surely ensured, and it is possible to solve the problem of chemical exposure of the spraying workers.

Examples

[0041] Hereinafter, the present invention will be described in more detail by way of examples. Diazinon manufactured by Nippon Kayaku Co., Ltd. (purity 95.3%) was used. Prothiofos was purchased as a commercially available Tokuthion wettable powder (manufactured by Alice Life Science Co., Ltd.), extracted with ethyl acetate, concentrated, and then purified (purity 94.4%) was used. The original form of fenthoate was purchased as a commercially available Elsan wettable powder (manufactured by Nissan Chemical Industries, Ltd.), extracted with hexane, concentrated, and then purified (purity 91.7%) was used. For BPMC, an article of unknown purity that had been stored was used.

[0042] The prepared microcapsules were measured for volume median diameter under the following analytical instruments and analytical conditions Analytical instrument: Laser diffraction particle size distribution measuring device SALD-2200, manufactured by Shimadzu Corporation Measurement method: Laser diffraction and laser scattering method Measurement range: 0.03~1000μm Light source: Semiconductor laser (wavelength 680nm, output 3mW) Cell: Flow cell method Cell material: Made of quartz glass Software: WingSALD-2200 Analysis sample: Prepared by adding water to the prepared microcapsules so that the concentration of the active ingredient is 0.1~5 wt%, and dispersing them.

[0043] The film thickness of the prepared microcapsules was calculated by the calculation method according to the following approximate formula (I). Formula (I) Film thickness = (film material weight / core material weight) × (core material density / film material density) × (volume median diameter / 6) Here, the following numerical values were used for each weight and density. Film material weight = polyisocyanate weight + curing agent weight Core material weight = oil phase weight - polyisocyanate weight Core material density = weighted average density of the oil phase components excluding polyisocyanate Film material density = weighted average density of polyisocyanate and curing agent The following density (specific gravity) values were used for the film thickness calculation in the examples. Diazinon: 1.117 Prothiofos: 1.310 Fenthionate: 1.226 BPMC: 1.10 MR-400: 1.240 MR-100: 1.231 TMDI: 1.020 Solvesso150ND: 0.886 Solvesso150: 0.895 JX normal paraffin: 0.750 Diethylenetriamine: 0.955 Ethylenediamine: 0.960 Diethylene glycol: 1.118 Propylene glycol: 1.038

[0044] The encapsulation rate of the active ingredient in the prepared microcapsules was calculated by measuring the content of the active ingredient in the preparation and the amount of the free component of the active ingredient outside the capsules by the following analysis method, subtracting the amount of the free component of the active ingredient outside the capsules from the total amount of the active ingredient to calculate the amount of the active ingredient inside the capsules, and expressing this as the ratio of the amount of the active ingredient inside the capsules to the total amount of the active ingredient in the preparation. As an analysis method for the content of the active ingredient in the preparation, about 1 g of the microcapsule composition was weighed, an internal standard substance and 100 mL of acetonitrile were added, and the mixture was shaken at a speed of 300 revolutions per minute for 20 minutes. Then, 1 mL of the supernatant was filtered through a 0.45 μm syringe filter to obtain a sample solution for content analysis. The sample solution was analyzed by high performance liquid chromatography, and the content of the active ingredient was determined by the internal standard method. As an analysis method for the amount of the free component of the active ingredient outside the capsules, about 1 g of the microcapsule composition was weighed, an internal standard substance and 50 mL of toluene or hexane were added, and the mixture was shaken at a speed of 300 revolutions per minute for 5 minutes. Then, 1 mL of the supernatant was mixed with 9 mL of acetonitrile to obtain a sample solution for analyzing the amount of the free component. The sample solution was analyzed by high performance liquid chromatography, and the amount of the free component of the active ingredient was determined by the internal standard method. Then, the encapsulation rate of the active ingredient was calculated from the following formula (II). Formula (II) Encapsulation rate (%) = ((((amount of microcapsule composition) × (content of active ingredient)) - (amount of free component)) / ((amount of microcapsule composition) × (content of active ingredient))) × 100

[0045] Example 1 To 35.9 parts by mass of (2-isopropyl-4-methylpyrimidyl-6)-diethylthiophosphate (generic name: diazinon, purity 95.6%), 0.12 part by mass of MR-400 ((trade name), polymethylene polyphenyl polyisocyanate, manufactured by Tosoh Corporation), 0.12 part by mass of TMDI ((trade name), trimethylhexamethylene diisocyanate, manufactured by Evonik Japan Co., Ltd.), and 2.5 parts by mass of K-800 ((trade name), epoxidized soybean oil, manufactured by Takemoto Yushi Co., Ltd.) were added and uniformly mixed to prepare an oil phase component. In another container, 6.0 parts by mass of a 5% by weight aqueous solution of PVA-217 (trade name, polyvinyl alcohol, manufactured by Kuraray Co., Ltd.), 0.5 part by mass of Sun Extract P-252 (trade name, lignin sulfonate, manufactured by Nippon Paper Industries Co., Ltd.), and 34.88 parts by mass of tap water were put to prepare an aqueous phase component. The oil phase component and the aqueous phase component were put into a 300 mL separable flask, and using a Hiscotron (manufactured by Microtech Nition Co., Ltd.), after stirring at a rotational speed of 2500 rpm for 2 minutes, stirring was carried out at 7000 rpm for 3 minutes to disperse the oil phase component, and an O / W type emulsion was prepared. To this, a mixed solution of 0.08 part by mass of diethylenetriamine ((reagent), manufactured by Huntsman Japan K.K.) and 0.6 part by mass of tap water as a water-soluble film-forming component was added, and the reaction was carried out at 60 °C for 3 hours under stirring to prepare a microcapsule-containing liquid. To this, 10 parts by mass of propylene glycol ((trade name), manufactured by ADEKA Corporation) as an anti-settling agent, 0.1 part by mass of Rhodopole 23 ((trade name), xanthan gum, manufactured by Solvay & DuPont K.K.), 0.25 part by mass of CMC RC591 ((trade name), carboxymethyl cellulose, manufactured by Asahi Kasei Corporation), 0.2 part by mass of Proxel GXL(S) ((trade name), fungicide, manufactured by Lonza Japan K.K.), and 8.75 parts by mass of tap water were added and uniformly mixed to obtain a dispersion containing microcapsules for pest control with a diazinon content of 34% by weight. The measured value of the volume median diameter of the obtained microcapsules was 16.4 μm. Also, the calculated value of the film thickness of the microcapsules was 23 nm. The encapsulation rate was 96.4%.

[0046] Example 2 The same operations were carried out except that the Sun Extract P-252 in the aqueous phase in Example 1 was changed to 0.02 part by mass and the tap water was changed to 35.36 parts by mass, to obtain a dispersion containing microcapsules for pest control with a diazinon content of 34% by weight. The measured value of the volume median diameter of the obtained microcapsules was 21.6 μm. Also, the calculated value of the film thickness of the microcapsules was 31 nm. The encapsulation rate was 97.1%.

[0047] Example 3 The same procedure was carried out except that 1.0 part by mass of Sun Extract P-252 in the aqueous phase in Example 1 was changed to 34.38 parts by mass of tap water, to obtain a dispersion containing microcapsules for pest control with a diazinon content of 34% by weight. The measured value of the volume median diameter of the obtained microcapsules was 24.5 μm. Also, the calculated value of the film thickness of the microcapsules was 35 nm. The encapsulation rate was 97.7%.

[0048] Example 4 The same procedure was carried out except that 2.0 parts by mass of Sun Extract P-252 in the aqueous phase in Example 1 was changed to 33.38 parts by mass of tap water, to obtain a dispersion containing microcapsules for pest control with a diazinon content of 34% by weight. The measured value of the volume median diameter of the obtained microcapsules was 17.4 μm. Also, the calculated value of the film thickness of the microcapsules was 25 nm. The encapsulation rate was 96.8%.

[0049] Example 5 The same procedure was carried out except that 0.5 part by mass of Sun Extract P-252 in the aqueous phase in Example 1 was changed to 0.5 part by mass of Morwet D-425 POWDER (trade name, alkylnaphthalenesulfonate, manufactured by Lion Specialty Chemicals Co., Ltd.), 10.0 parts by mass of the anti-settling agent propylene glycol was changed to 5.0, and 8.75 parts by mass of tap water was changed to 13.75 parts by mass, to obtain a dispersion containing microcapsules for pest control with a diazinon content of 34% by weight. The measured value of the volume median diameter of the obtained microcapsules was 26.2 μm. Also, the calculated value of the film thickness of the microcapsules was 37 nm. The encapsulation rate was 96.7%.

[0050] Example 6 The same procedure was carried out except that 0.02 part by mass of Sun Extract P-252 in the aqueous phase in Example 2 was changed to 0.02 part by mass of Morwet D-425 POWDER, to obtain a dispersion containing microcapsules for pest control with a diazinon content of 34% by weight. The measured volume median diameter of the obtained microcapsules was 22.4 μm. Also, the calculated film thickness of the microcapsules was 32 nm. The capsule encapsulation rate was 97.5%.

[0051] Example 7 In Example 1, 34.88 parts by mass of tap water in the aqueous phase was changed to 33.38 parts by mass, 2.0 parts by mass of sodium chloride was added to the aqueous phase, and while 0.5 part by mass of Sunex P-252 was changed to 0 part by mass, all other operations were carried out in the same manner to obtain a dispersion containing microcapsules for pest control with a diazinon content of 34% by weight. The measured volume median diameter of the obtained microcapsules was 20.3 μm. Also, the calculated film thickness of the microcapsules was 29 nm. The capsule encapsulation rate was 97.8%.

[0052] Example 8 In Example 7, all operations were carried out in the same manner except that 2.0 parts by mass of sodium chloride in the aqueous phase was changed to 2.0 parts by mass of potassium chloride to obtain a dispersion containing microcapsules for pest control with a diazinon content of 34% by weight. The measured volume median diameter of the obtained microcapsules was 23.4 μm. Also, the calculated film thickness of the microcapsules was 33 nm. The capsule encapsulation rate was 97.7%.

[0053] Example 9 In Example 3, all operations were carried out in the same manner except that 1.0 part by mass of Sunex P-252 in the aqueous phase was changed to 1.0 part by mass of Demol MS ((trade name), alkylnaphthalenesulfonate, manufactured by Kao Corporation) to obtain a dispersion containing microcapsules for pest control with a diazinon content of 34% by weight. The measured volume median diameter of the obtained microcapsules was 19.6 μm. Also, the calculated film thickness of the microcapsules was 28 nm. The capsule encapsulation rate was 96.7%.

[0054] Example 10 The same operations were carried out as in Example 3, except that 1.0 part by mass of Sun Ekisu P-252 in the aqueous phase was changed to 1.0 part by mass of Srz-402K ((trade name), alkyl styrene maleate, manufactured by Tago Chemical Co., Ltd.), and a dispersion containing microcapsules for pest control with a diazinon content of 34% by weight was obtained. The measured value of the volume median diameter of the obtained microcapsules was 21.7 μm. Also, the calculated value of the film thickness of the microcapsules was 31 nm. The encapsulation rate of the capsules was 95.5%.

[0055] Example 11 The same operations were carried out as in Example 3, except that 1.0 part by mass of Sun Ekisu P-252 in the aqueous phase was changed to 1.0 part by mass of Vanilex N ((trade name), lignin sulfonate, manufactured by Nippon Paper Industries Co., Ltd.), and a dispersion containing microcapsules for pest control with a diazinon content of 34% by weight was obtained. The measured value of the volume median diameter of the obtained microcapsules was 20.7 μm. Also, the calculated value of the film thickness of the microcapsules was 29 nm. The encapsulation rate of the capsules was 98.3%.

[0056] Example 12 The same operations were carried out as in Example 11, except that 1.0 part by mass of Vanilex N in the aqueous phase was changed to 0.5 part by mass and 34.38 parts by mass of tap water was changed to 34.88 parts by mass, and a dispersion containing microcapsules for pest control with a diazinon content of 34% by weight was obtained. The measured value of the volume median diameter of the obtained microcapsules was 21.7 μm. Also, the calculated value of the film thickness of the microcapsules was 31 nm. The encapsulation rate of the capsules was 98.2%.

[0057] Example 13 The same operations were carried out as in Example 11, except that 1.0 part by mass of Vanilex N in the aqueous phase was changed to 3.0 parts by mass and 34.38 parts by mass of tap water was changed to 32.38 parts by mass, and a dispersion containing microcapsules for pest control with a diazinon content of 34% by weight was obtained. The measured value of the volume median diameter of the obtained microcapsules was 20.0 μm. Also, the calculated value of the film thickness of the microcapsules was 28 nm. The capsule encapsulation rate was 96.5%.

[0058] Example 14 In Example 3, the same operations were performed except that 34.38 parts by mass of tap water in the aqueous phase was changed to 32.38 parts by mass, and 2.0 parts by mass of sodium chloride was added to the aqueous phase, to obtain a dispersion containing microcapsules for pest control with a diazinon content of 34% by weight. The measured value of the volume median diameter of the obtained microcapsules was 22.9 μm. Also, the calculated value of the film thickness of the microcapsules was 32 nm. The capsule encapsulation rate was 98.8%.

[0059] Example 15 In Example 14, the same operations were performed except that 0.12 part by mass of MR-400 in the oil phase was changed to 0.06 part by mass, 0.12 part by mass of TMDI was changed to 0.06 part by mass, 32.38 parts by mass of tap water in the aqueous phase was changed to 32.54 parts by mass, and 0.08 part by mass of diethylenetriamine as the curing agent was changed to 0.04 part by mass, to obtain a dispersion containing microcapsules for pest control with a diazinon content of 34% by weight. The measured value of the volume median diameter of the obtained macro-capsules was 22.6 μm. Also, the calculated value of the film thickness of the microcapsules was 16 nm. The capsule encapsulation rate was 97.2%.

[0060] Example 16 In Example 15, the same operations were performed except that 32.54 parts by mass of tap water in the aqueous phase was changed to 30.54 parts by mass, and 2.0 parts by mass of sodium chloride was changed to 4.0 parts by mass, to obtain a dispersion containing microcapsules for pest control with a diazinon content of 34% by weight. The measured value of the volume median diameter of the obtained microcapsules was 22.8 μm. Also, the calculated value of the film thickness of the microcapsules was 16 nm. The capsule encapsulation rate was 95.5%.

[0061] Example 17 The same operations were carried out as in Example 11, except that 34.38 parts by mass of tap water in the aqueous phase was changed to 31.38 parts by mass, and 3.0 parts by mass of sodium chloride was additionally added, to obtain a dispersion containing microcapsules for pest control with a diazinon content of 34% by weight. The measured value of the volume median diameter of the obtained microcapsules was 23.5 μm. Also, the calculated value of the film thickness of the microcapsules was 33 nm. The encapsulation rate was 98.6%.

[0062] Example 18 To 31.59 parts by mass of (2-isopropyl-4-methylpyrimidyl-6)-diethylthiophosphate (common name: diazinon, purity 95.6%), 0.12 part by mass of MR-400 (trade name, polymethylene polyphenyl polyisocyanate, manufactured by Tosoh Corporation) as an oil-soluble film-forming component, 0.12 part by mass of TMDI (trade name, trimethylhexamethylene diisocyanate, manufactured by Evonik Japan Co., Ltd.), 1.0 part by mass of K-800 (trade name, epoxidized soybean oil, manufactured by Takemoto Yushi Co., Ltd.), and 10.0 parts of Solvesso 150 (trade name, manufactured by ExxonMobil Corporation) were added and uniformly mixed to prepare an oil-phase component. In another container, 6.0 parts by mass of a 5% by weight aqueous solution of PVA-217 (trade name, polyvinyl alcohol, manufactured by Kuraray Co., Ltd.), 1.0 part by mass of Sunex P-252 (trade name, ligninsulfonate, manufactured by Nippon Paper Industries Co., Ltd.), 2.5 parts by mass of sodium chloride, and 33.44 parts by mass of tap water were put to prepare an aqueous-phase component. The oil-phase component and the aqueous-phase component were put into a 300 mL separable flask, and using a Hiscotron (manufactured by Microtech Nition Co., Ltd.), they were stirred at a rotational speed of 2500 rpm for 3 minutes and then at a rotational speed of 5000 rpm for 4 minutes to disperse the oil-phase component, and an O / W type emulsion was prepared. To this, a mixed solution of 0.08 part by mass of diethylenetriamine and 0.6 part by mass of tap water as a water-soluble film-forming component was added, and the reaction was carried out at 60 °C for 3 hours with stirring to prepare a microcapsule-containing liquid. To this, 5 parts by mass of propylene glycol ((trade name), manufactured by ADEKA Corporation) as an anti-settling agent, 0.1 part by mass of Rhodopole 23 ((trade name), xanthan gum, manufactured by Solvay & Asahi Kasei Co., Ltd.), 0.25 part by mass of Seolaus RC591 ((trade name), carboxymethyl cellulose, manufactured by Asahi Kasei Corporation), 0.2 part by mass of Proxel GXL(S) ((trade name), fungicide, manufactured by Lonza Japan Co., Ltd.), and 8 parts by mass of tap water were added and mixed uniformly to obtain a dispersion containing microcapsules for pest control with a diazinon content of 30% by weight. The measured value of the volume median diameter of the obtained microcapsules was 19.9 μm. Also, the calculated value of the film thickness of the microcapsules was 24 nm. The capsule encapsulation rate was 98.6%.

[0063] Example 19 The same operations were carried out except that 0.12 part by mass of MR-400 in the oil phase component in Example 18 was changed to 0.09 part by mass, 0.12 part by mass of TMDI was changed to 0.09 part by mass, 33.44 parts by mass of tap water in the aqueous phase was changed to 33.52 parts by mass, and 0.08 part by mass of diethylenetriamine as a curing agent was changed to 0.06 part by mass, to obtain a dispersion containing microcapsules for pest control with a diazinon content of 30% by weight. The measured value of the volume median diameter of the obtained microcapsules was 17.2 μm. Also, the calculated value of the film thickness of the microcapsules was 16 nm. The capsule encapsulation rate was 96.9%.

[0064] Example 20 The same operations were carried out except that 2.5 parts by mass of sodium chloride in the aqueous phase in Example 19 was changed to 2.5 parts by mass of disodium hydrogen phosphate, to obtain a dispersion containing microcapsules for pest control with a diazinon content of 30% by weight. The measured value of the volume median diameter of the obtained microcapsules was 20.1 μm. Also, the calculated value of the film thickness of the microcapsules was 18 nm. The capsule encapsulation rate was 98.0%.

[0065] Example 21 In Example 18, 0.12 parts by mass of MR-400 in the oil phase component was changed to 0.30 parts by mass of MR-100 (trade name, polymethylene polyphenyl polyisocyanate, manufactured by Tosoh Corporation), 0.12 parts by mass of TMDI was changed to 0 parts by mass, 10 parts by mass of Solvesso 150 was changed to 8 parts by mass of Solvesso 150ND, 33.44 parts by mass of tap water in the aqueous phase was changed to 35.86 parts by mass, 2.5 parts by mass of sodium chloride was changed to 2.0 parts by mass, 0.08 parts by mass of diethylenetriamine as the curing agent was changed to 0.05 parts by mass, and the same operations were performed except that 0.05 parts by mass of propylene glycol was added to the curing agent, to obtain a dispersion containing microcapsules for pest control with a diazinon content of 30% by weight. The measured value of the volume median diameter of the obtained microcapsules was 21.8 μm. Also, the calculated value of the film thickness of the microcapsules was 33 nm. The encapsulation rate of the capsules was 98.8%.

[0066] Example 22 In Example 18, 0.12 parts by mass of MR-400 in the oil phase component was changed to 0.36 parts by mass, 0.12 parts by mass of TMDI was changed to 0.36 parts by mass, 10 parts by mass of Solvesso 150 was changed to 10 parts by mass of Solvesso 150ND, 6 g of a 5% PVA aqueous solution in the aqueous phase was changed to 12 g, 33.44 parts by mass of tap water was changed to 26.8 parts by mass, and 0.08 parts by mass of diethylenetriamine as the curing agent was changed to 0.24 parts by mass. The same operations were performed, to obtain a dispersion containing microcapsules for pest control with a diazinon content of 30% by weight. The measured value of the volume median diameter of the obtained microcapsules was 9.2 μm. Also, the calculated value of the film thickness of the microcapsules was 34 nm. The encapsulation rate of the capsules was 99.0%.

[0067] Example 23 In Example 18, except that 0.12 parts by mass of MR-400 in the oil phase component was changed to 0.18 parts by mass, 0.12 parts by mass of TMDI was changed to 0.18 parts by mass, 10 parts by mass of Solvesso 150 was changed to 10 parts by mass of Solvesso 150ND, 33.44 parts by mass of tap water in the aqueous phase was changed to 33.28 parts by mass, and 0.08 parts by mass of diethylenetriamine as the curing agent was changed to 0.12 parts by mass, the same operations were carried out to obtain a dispersion containing microcapsules for pest control with a diazinon content of 30% by weight. The measured value of the volume median diameter of the obtained microcapsules was 19.4 μm. Also, the calculated value of the film thickness of the microcapsules was 36 nm. The capsule encapsulation rate was 99.1%.

[0068] Example 24 In Example 18, except that 0.12 parts by mass of MR-400 in the oil phase component was changed to 0.09 parts by mass, 0.12 parts by mass of TMDI was changed to 0.09 parts by mass, 10 parts by mass of Solvesso 150 was changed to 10 parts by mass of Solvesso 150ND, 33.4 parts by mass of tap water in the aqueous phase was changed to 33.52 parts by mass, and 0.08 parts by mass of diethylenetriamine as the curing agent was changed to 0.06 parts by mass, the same operations were carried out to obtain a dispersion containing microcapsules for pest control with a diazinon content of 30% by weight. The measured value of the volume median diameter of the obtained microcapsules was 40.7 μm. Also, the calculated value of the film thickness of the microcapsules was 37 nm. The capsule encapsulation rate was 99.3%.

[0069] Example 25 In Example 18, except that 0.12 parts by mass of MR-400 in the oil phase component was changed to 0.72 parts by mass, 0.12 parts by mass of TMDI was changed to 0.72 parts by mass, 10 parts by mass of Solvesso 150 was changed to 10 parts by mass of Solvesso 150ND, 1.0 part by mass of Sun extract P-252 in the aqueous phase was changed to 2.0 parts by mass, 6 g of 5% PVA aqueous solution in the aqueous phase was changed to 12 g, 33.44 parts by mass of tap water was changed to 27.7 parts by mass, 0.08 parts by mass of diethylenetriamine as the curing agent was changed to 0.48 parts by mass, and 8.0 parts by mass of tap water as the anti-settling agent was changed to 3.0 parts by mass, the same operations were carried out to obtain a dispersion containing microcapsules for pest control with a diazinon content of 30% by weight. The measured value of the volume median diameter of the obtained microcapsules was 4.5 μm. Also, the calculated value of the film thickness of the microcapsules was 33 nm. The capsule encapsulation rate was 98.2%.

[0070] Example 26 The same operations were carried out except that 0.3 parts by mass of MR-100 in the oil phase component in Example 21 was changed to 0.3 parts by mass of MR-400, 0.05 parts by weight of diethylenetriamine as the curing agent was changed to 0 parts by mass, and 0.05 parts by mass of propylene glycol was changed to 0.1 parts by mass, to obtain a dispersion containing microcapsules for pest control with a diazinon content of 30% by weight. The measured value of the volume median diameter of the obtained microcapsules was 19.6 μm. Also, the calculated value of the film thickness of the microcapsules was 29 nm. The capsule encapsulation rate was 96.8%.

[0071] Example 27 To 21.45 parts by mass of (RS)-O-2,4-dichlorophenyl = O-ethyl = S-propyl = phosphorodithioate (common name: prothiofos), 0.13 parts by mass of MR-400 ((trade name), polymethylene polyphenyl polyisocyanate, manufactured by Tosoh Corporation) was added as an oil-soluble film-forming component and mixed uniformly to prepare an oil phase component. In another container, 1.8 parts by mass of an 8.3% by weight aqueous solution of PVA-217 ((trade name), polyvinyl alcohol, manufactured by Kuraray Co., Ltd.), 1.0 part by mass of Morwet D-425 Powder ((trade name), alkylnaphthalenesulfonate, manufactured by Lion Specialty Chemicals Co., Ltd.), and 19.63 parts by mass of tap water were put to prepare an aqueous phase component. The oil phase component and the aqueous phase component were put into a 300 mL separable flask, and using a high-shearing mixer (manufactured by Microtech Nition Co., Ltd.), it was stirred at a rotational speed of 2000 rpm for 2 minutes and then at 7500 rpm for 2 minutes to disperse the oil phase component and prepare an O / W type emulsion. To this, a mixed solution of 0.04 parts by mass of ethylenediamine ((reagent), manufactured by Wako Pure Chemical Industries, Ltd.) and 0.3 parts by mass of tap water as a water-soluble film-forming component was added, and the reaction was carried out at 60 °C for 3 hours under stirring to prepare a microcapsule-containing liquid. To this, 5 parts by mass of propylene glycol ((trade name), manufactured by ADEKA Corporation) as an anti-settling agent, 0.1 part by mass of Rhodopole 23 ((trade name), xanthan gum, manufactured by Solvay & Asahi Kasei Co., Ltd.), 0.2 part by mass of Kunipia F ((trade name), bentonite, manufactured by Kunimine Industries Co., Ltd.), and 0.15 part by mass of Proxel GXL(S) ((trade name), fungicide, manufactured by Lonza Japan Co., Ltd.) were added and uniformly mixed to obtain a dispersion containing microcapsules for pest control with a profenofos content of 40% by weight. The measured value of the volume median diameter of the obtained microcapsules was 10.5 μm. Also, the calculated value of the film thickness of the microcapsules was 15 nm. The encapsulation rate was 99.5%.

[0072] Example 28 To 21.81 parts by mass of S-α-ethoxycarbonylbenzyl O,O-dimethyl phosphorodithioate (common name: PAP, phenthoate), 0.075 part by mass of MR-400 ((trade name), polymethylene polyphenyl polyisocyanate, manufactured by Tosoh Corporation) as an oil-soluble film-forming component was added and uniformly mixed to prepare an oil-phase component. In another container, 3.0 parts by mass of a 5% aqueous solution of PVA-217 ((trade name), polyvinyl alcohol, manufactured by Kuraray Co., Ltd.), 0.5 part by mass of Sunex P-252 ((trade name), lignin sulfonate, manufactured by Nippon Paper Industries Co., Ltd.), 1.25 parts by mass of sodium chloride, 15.715 parts by mass of tap water, and 0.05 part by mass of Antifoam E-20 ((trade name), silicone emulsion) were put to prepare an aqueous-phase component. The oil-phase component and the aqueous-phase component were put into a 300 mL separable flask, and using a Hiscotron (manufactured by Microtech Nition Co., Ltd.), they were stirred at a rotation speed of 2500 rpm for 2 minutes and then at a rotation speed of 6000 rpm for 2 minutes to disperse the oil-phase component and prepare an O / W type emulsion. To this, a mixed solution of 0.025 part by mass of diethylenetriamine and 0.3 part by mass of tap water as a water-soluble film-forming component was added, and the reaction was carried out at 60 °C for 3 hours with stirring to prepare a microcapsule-containing liquid. To this, 3.5 parts by mass of propylene glycol ((trade name), manufactured by ADEKA CORPORATION) as an anti-settling agent, 0.05 parts by mass of Rhodopole 23 ((trade name), xanthan gum, manufactured by Solvay & Asahi Kasei Co., Ltd.), 0.125 parts by mass of CMC RC591 ((trade name), carboxymethyl cellulose, manufactured by Asahi Kasei Corporation), 0.1 parts by mass of Proxel GXL (S) ((trade name), fungicide, manufactured by Lonza Japan Ltd.), and 3.5 parts by mass of tap water were added and uniformly mixed to obtain a dispersion containing microcapsules for pest control with a fenothiocarb content of 40% by weight. The measured value of the volume median diameter of the obtained microcapsules was 26.5 μm. Also, the calculated value of the film thickness of the microcapsules was 21 nm. The encapsulation rate was 98.5%.

[0073] Example 29 To 15.5 parts by mass of 2-sec-butylphenyl-N-methylcarbamate (generic name: BPMC, phenothiocarb), 0.18 parts by mass of MR-400 ((trade name), polymethylene polyphenyl polyisocyanate, manufactured by Tosoh Corporation) and 5.0 parts of Solvesso 150 ((trade name), manufactured by ExxonMobil Corporation) were added as oil-soluble film-forming components and uniformly mixed to prepare an oil-phase component. In another container, 3.6 parts by mass of a 5 wt% aqueous solution of PVA-217 ((trade name), polyvinyl alcohol, manufactured by Kuraray Co., Ltd.), 0.6 parts by mass of Sunex P-252 ((trade name), lignin sulfonate, manufactured by Nippon Paper Industries Co., Ltd.), 1.5 parts by mass of sodium chloride, and 15.46 parts by mass of tap water were placed to prepare an aqueous-phase component. The oil-phase component and the aqueous-phase component were placed in a 300 mL separable flask, and using a Hiscotron (manufactured by Microtech Nition Co., Ltd.), they were stirred at a rotation speed of 2500 rpm for 2 minutes, and then at a rotation speed of 4000 to 8000 rpm for 3 minutes to disperse the oil-phase component and prepare an O / W type emulsion. To this, a mixed solution of 0.06 parts by mass of diethylenetriamine and 0.3 parts by mass of tap water as a water-soluble film-forming component was added, and the reaction was carried out at 60 °C for 3 hours under stirring to prepare a microcapsule-containing liquid. To this, 2.5 parts by mass of propylene glycol ((trade name), manufactured by ADEKA Corporation) as an anti-settling agent, 0.1 part by mass of Rhodopole 23 ((trade name), xanthan gum, manufactured by Solvay & Asahi Kasei Co., Ltd.), 0.1 part by mass of Ceolus RC591 ((trade name), carboxymethyl cellulose, manufactured by Asahi Kasei Corporation), 0.1 part by mass of Proxel GXL(S) ((trade name), fungicide, manufactured by Lonza Japan Co., Ltd.), and 5 parts by mass of tap water were added and uniformly mixed to obtain a dispersion containing microcapsules for pest control with a BPMC content of 30% by weight. The measured value of the volume median diameter of the obtained microcapsules was 29.0 μm. Also, the calculated value of the film thickness of the microcapsules was 51 nm. The encapsulation efficiency was 95.3%.

[0074] Comparative Example 1 To 35.9 parts by mass of (2-isopropyl-4-methylpyrimidyl-6)-diethylthiophosphate (common name: diazinon), 0.12 part by mass of MR-400 ((trade name), polymethylene polyphenyl polyisocyanate, manufactured by Tosoh Corporation) as an oil-soluble film-forming component, 0.12 part by mass of TMDI ((trade name), trimethylhexamethylene diisocyanate, manufactured by Evonik Japan Co., Ltd.), and 2.5 parts by mass of K-800 ((trade name), epoxidized soybean oil, manufactured by Takemoto Yushi Co., Ltd.) were added and uniformly mixed to prepare an oil-phase component. In another container, 6.0 parts by mass of a 5% by weight aqueous solution of PVA-217 ((trade name), polyvinyl alcohol, manufactured by Kuraray Co., Ltd.) and 35.38 parts by mass of tap water were placed to prepare an aqueous-phase component. The oil-phase component and the aqueous-phase component were placed in a 300 mL separable flask, and using a Hiscotron (manufactured by Microtech Nition Co., Ltd.), they were stirred at a rotation speed of 2500 rpm for 2 minutes, and then stirred at a rotation speed of 5000 rpm for 2 minutes to disperse the oil-phase component, and an O / W type emulsion was prepared. To this, a mixed solution of 0.08 part by mass of diethylenetriamine ((trade name), manufactured by Huntsman Japan K.K.) as a water-soluble film-forming component and 0.6 part by mass of tap water was added, and the reaction was carried out at 60 °C for 3 hours under stirring to prepare a microcapsule-containing liquid. To this, 10 parts by mass of propylene glycol ((trade name), manufactured by ADEKA Corporation) as an anti-settling agent, 0.1 part by mass of Rhodopole 23 ((trade name), xanthan gum, manufactured by Solvay & Asahi Kasei Co., Ltd.), 0.25 part by mass of Avicel RC591 ((trade name), carboxymethyl cellulose, manufactured by Asahi Kasei Corporation), 0.2 part by mass of Proxel GXL(S) ((trade name), fungicide, manufactured by Lonza Japan Co., Ltd.), and 8.75 parts by mass of tap water were added and uniformly mixed to obtain a dispersion containing microcapsules for pest control with a diazinon content of 34% by weight. The measured value of the volume median diameter of the obtained microcapsules was 18.2 μm. Also, the calculated value of the film thickness of the microcapsules was 26 nm. The encapsulation rate was 89.7%.

[0075] Comparative Example 2 To the aqueous phase of Comparative Example 1, 2.0 parts by mass of New Calgen WG-5 ((trade name), sodium polycarboxylate, manufactured by Takemoto Yushi Co., Ltd.), 0.4 part by mass of Antifoam E-20, 32.98 parts by mass of tap water, and 0.08 part by mass of diethylenetriamine as a curing agent were changed to 0.08 part by mass of ethylenediamine, and the same operations were performed. However, solidification occurred during the reaction and no microcapsule dispersion was obtained.

[0076] Comparative Example 3 The same operations were performed except that 0.08 part by mass of diethylenetriamine in Comparative Example 1 was changed to 0.08 part by mass of diethylene glycol ((reagent), manufactured by Wako Pure Chemical Industries, Ltd.) to obtain a dispersion containing microcapsules for pest control with a diazinon content of 34% by weight. The measured value of the volume median diameter of the obtained microcapsules was 21.4 μm. Also, the calculated value of the film thickness of the microcapsules was 29 nm. The encapsulation rate was 88.0%.

[0077] Comparative Example 4 The same operations were performed except that 35.38 parts by mass of tap water in the aqueous phase of Comparative Example 1 was changed to 33.38 parts by mass and 2.0 parts by mass of calcium chloride ((reagent), manufactured by Wako Pure Chemical Industries, Ltd.) was added to the aqueous phase. However, solidification occurred during the reaction and no microcapsule dispersion was obtained.

[0078] Comparative Example 5 Except that 35.38 parts by mass of tap water in the aqueous phase of Comparative Example 1 was changed to 33.38 parts by mass and 2.0 parts by mass of ammonium chloride ((reagent), manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the aqueous phase, the same operations were performed. As a result, solidification occurred during the reaction and a microcapsule dispersion could not be obtained.

[0079] Comparative Example 6 Except that 35.38 parts by mass of tap water in the aqueous phase of Comparative Example 1 was changed to 33.38 parts by mass and 2.0 parts by mass of sodium acetate ((reagent), manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the aqueous phase, the same operations were performed. As a result, solidification occurred during the reaction and a microcapsule dispersion could not be obtained.

[0080] Comparative Example 7 In the oil phase of Comparative Example 1, 0.12 part by mass of MR-400 was changed to 0.23 part by mass, 0.12 part by mass of TMDI was changed to 0 part by mass, in the aqueous phase, 35.38 parts by mass of tap water was changed to 35.39 parts by mass, 5.0 parts by mass of propylene glycol as an anti-settling agent was changed to 10.0 parts by mass, and 8.75 parts by mass of tap water was changed to 13.75 parts by mass. The same operations were performed except for these changes, and a dispersion containing microcapsules for pest control with a diazinon content of 34% by weight was obtained. The measured value of the volume median diameter of the obtained microcapsules was 26.9 μm. The calculated value of the film thickness of the microcapsules was 34 nm. The encapsulation efficiency was 93.4%.

[0081] Comparative Example 8 In the oil phase of Comparative Example 1, 0.12 part by mass of MR-400 was changed to 0 part by mass, 0.12 part by mass of TMDI was changed to 0.46 part by mass, in the aqueous phase, 35.38 parts by mass of tap water was changed to 35.16 parts by mass, and 8.75 parts by mass of tap water as an anti-settling agent was changed to 13.75 parts by mass. The same operations were performed except for these changes. As a result, aggregation occurred during aging and a microcapsule dispersion could not be obtained.

[0082] Comparative Example 9 35.9 parts by mass of (2-isopropyl-4-methylpyrimidyl-6)-diethylthiophosphate (common name: diazinon) of Comparative Example 1 was changed to 27.1 parts by mass, 0.12 part by mass of MR-400 in the oil phase was changed to 1.0 part by mass, 0.12 part by mass of TMDI was changed to 1.0 part by mass, 2.5 parts by mass of K-800 was changed to 2.0 parts by mass, and 7.5 parts by mass of JX normal paraffin ((trade name), hydrocarbon solvent, manufactured by JXTG Energy Corporation) was added to the oil phase. 34.9 parts by mass of tap water in the aqueous phase, 0.08 part by mass of the curing agent diethylenetriamine was changed to 0.3 part by mass, 0.3 part by mass of ethylenediamine was added, and 8.75 parts by mass of tap water as an anti-settling agent was changed to 13.75 parts by mass. The operation was carried out in the same manner except for the above changes, and a dispersion containing microcapsules for pest control with a diazinon content of 25% by weight was obtained. The measured value of the volume median diameter of the obtained microcapsules was 40.0 μm. Also, the calculated value of the film thickness of the microcapsules was 450 nm. The encapsulation efficiency was 99.9%.

[0083] Comparative Example 10 (RS)-O-2,4-dichlorophenyl = O-ethyl = S-propyl = phosphorodithioate (common name: prothiofos) 21.45 parts by mass was added with 0.13 part by mass of MR-400 ((trade name), polymethylene polyphenyl polyisocyanate, manufactured by Tosoh Corporation) as an oil-soluble film-forming component and uniformly mixed to prepare an oil-phase component. In another container, 1.8 parts by mass of an 8.3 wt% aqueous solution of PVA-217 ((trade name), polyvinyl alcohol, manufactured by Kuraray Co., Ltd.), 20.49 parts by mass of tap water, and 0.2 part by mass of Antifoam E-20 ((trade name), silicone emulsion, manufactured by Kao Corporation) were added to prepare an aqueous-phase component. The oil-phase component and the aqueous-phase component were placed in a 300 mL separable flask, and using a histotron (manufactured by Microtech Nition Co., Ltd.), after stirring at a rotation speed of 2500 rpm for 2 minutes, the mixture was stirred at a rotation speed of 12500 rpm for 6 minutes to disperse the oil-phase component, and an O / W type emulsion was prepared. To this, a mixed solution of 0.04 part by mass of ethylenediamine and 0.3 part by mass of tap water as a water-soluble film-forming component was added, and the reaction was carried out at 60 °C for 3 hours with stirring to prepare a microcapsule-containing liquid. To this, 5 parts by mass of propylene glycol ((trade name), manufactured by ADEKA Corporation) as an anti-settling agent, 0.1 part by mass of Rhodopol 23 ((trade name), xanthan gum, manufactured by Solvay & DuPont K.K.), 0.2 part by mass of Kunipia F ((trade name), bentonite, manufactured by Kunimine Industries Co., Ltd.), and 0.15 part by mass of Proxel GXL(S) ((trade name), fungicide, manufactured by Lonza Japan Co., Ltd.) were added and uniformly mixed to obtain a dispersion containing microcapsules for pest control with a profenofos content of 40% by weight. The measured value of the volume median diameter of the obtained microcapsules was 17.0 μm. Also, the calculated value of the film thickness of the microcapsules was 25 nm. The encapsulation rate was 91.9%.

[0084] Comparative Example 11 To 21.68 parts by mass of S-α-ethoxycarbonylbenzyl O,O-dimethyl phosphorodithioate (common name: PAP, phenthoate), 0.075 part by mass of MR-400 ((trade name), polymethylene polyphenyl polyisocyanate, manufactured by Tosoh Corporation) as an oil-soluble film-forming component was added and uniformly mixed to prepare an oil-phase component. In another container, 3.0 parts by mass of a 5% aqueous solution of PVA-217 ((trade name), polyvinyl alcohol, manufactured by Kuraray Co., Ltd.) and 15.27 parts by mass of tap water were placed to prepare an aqueous-phase component. The oil-phase component and the aqueous-phase component were placed in a 300 mL separable flask, and using a Hiscotron (manufactured by Microtech Nition Co., Ltd.), they were stirred at a rotation speed of 2500 rpm for 2 minutes and then at a rotation speed of 5000 rpm for 2 minutes to disperse the oil-phase component and prepare an O / W type emulsion. To this, a mixed solution of 0.025 part by mass of diethylenetriamine and 0.3 part by mass of tap water as a water-soluble film-forming component was added, and the reaction was carried out at 60 °C for 3 hours with stirring to prepare a microcapsule-containing liquid. To this, 5 parts by mass of propylene glycol ((trade name), manufactured by ADEKA CORPORATION) as an anti-settling agent, 0.05 parts by mass of Rhodopole 23 ((trade name), xanthan gum, manufactured by Solvay & DuPont K.K.), 0.125 parts by mass of Seolaus RC591 ((trade name), carboxymethyl cellulose, manufactured by Asahi Kasei Corporation), 0.1 parts by mass of Proxel GXL(S) ((trade name), fungicide, manufactured by Lonza Japan K.K.), and 4.375 parts by mass of tap water were added and uniformly mixed to obtain a dispersion containing microcapsules for pest control with a fenothate content of 40% by weight. The measured value of the volume median diameter of the obtained microcapsules was 24.0 μm. Also, the calculated value of the film thickness of the microcapsules was 19 nm. The encapsulation rate was 94.2%.

[0085] Comparative Example 12 To 15.5 parts by mass of 2-sec-butylphenyl-N-methylcarbamate (generic name: BPMC, phenobucarb), 0.15 parts by mass of MR-400 ((trade name), polymethylene polyphenyl polyisocyanate, manufactured by Tosoh Corporation) and 5.0 parts of Solvesso 150 ((trade name), manufactured by ExxonMobil Corporation) were added as an oil-soluble film-forming component and uniformly mixed to prepare an oil-phase component. In another container, 3 parts by mass of a 5 wt% aqueous solution of PVA-217 ((trade name), polyvinyl alcohol, manufactured by Kuraray Co., Ltd.) and 18.2 parts by mass of tap water were put to prepare an aqueous-phase component. The oil-phase component and the aqueous-phase component were put into a 300 mL separable flask, and using a Hiscotron (manufactured by Microtech Nition Co., Ltd.), they were stirred at a rotational speed of 2500 rpm for 2 minutes, and then at a rotational speed of 5000 - 6000 rpm for 2 minutes to disperse the oil-phase component and prepare an O / W type emulsion. To this, a mixed solution of 0.05 parts by mass of diethylenetriamine and 0.3 parts by mass of tap water as a water-soluble film-forming component was added, and the reaction was carried out at 60 °C for 3 hours under stirring to prepare a microcapsule-containing liquid. To this, 2.5 parts by mass of propylene glycol ((trade name), manufactured by ADEKA CORPORATION) as an anti-settling agent, 0.1 part by mass of Rhodopol 23 ((trade name), xanthan gum, manufactured by Solvay & Asahi Kasei Co., Ltd.), 0.1 part by mass of Seolaus RC591 ((trade name), carboxymethyl cellulose, manufactured by Asahi Kasei Corporation), 0.1 part by mass of Proxel GXL(S) ((trade name), fungicide, manufactured by Lonza Japan Ltd.), and 5 parts by mass of tap water were added and uniformly mixed to obtain a dispersion containing microcapsules for pest control with a BPMC content of 30% by weight. The measured value of the volume median diameter of the obtained microcapsules was 24.0 μm. Also, the calculated value of the film thickness of the microcapsules was 35 nm. The encapsulation rate was 88.5%.

[0086] For Examples 1 to 27 and Comparative Examples 1 to 10 (comparative examples where microencapsulation was possible), the volume median diameter, film thickness, and encapsulation rate of the microcapsules were summarized in Tables 1-1 and 1-2. For Example 28 and Comparative Example 11, they were summarized in Table 1-3. Also, for Example 29 and Comparative Example 12, they were summarized in Table 1-4.

[0087]

Table 1-1

[0088]

Table 1-2

[0089]

Table 1-3

[0090]

Table 1-4

[0091] All the formulations of the examples showed a high encapsulation rate of over 95% in the capsules. Since the inclusion of a dispersant maintained high dispersion stability during dispersion, it is considered that the encapsulation proceeded rapidly and stably, and the capsule film became strong. On the other hand, the capsule encapsulation rates of the comparative examples without a dispersant were all less than 95% except for Comparative Example 9 with a thick film, and it is considered that the film was weak and the capsules were easily broken.

[0092] Test Example 1 (Accelerated Stability Test) Regarding the formulations of the examples and comparative examples, they were taken out after being stored in a constant temperature bath at 54°C for 2 weeks, and the active ingredient content and capsule encapsulation rate were measured. The results are shown in Tables 2-1 and 2-2.

[0093]

Table 2-1

[0094]

Table 2-2

[0095]

Table 2-3

[0096] Regarding the active ingredient content, there was no significant difference between the formulations of the examples and comparative examples at the initial value and after 2 weeks at 54°C, and both were stable. For the capsule encapsulation rate, in the formulations of the examples, even after storage at 54°C for 2 weeks, the decomposition rate was 5% or less, and the overall decomposition rate was very low. On the other hand, in the formulations of the comparative examples, after storage at 54°C for 2 weeks, a high capsule decomposition rate or an apparent increase in the capsule encapsulation rate, presumably due to the decomposition of the free component of the active ingredient, was observed. Since the expiration date of agricultural formulations is usually more than 2 years, from the results of the accelerated test at 54°C for 2 weeks, which is equivalent to the storage conditions at room temperature for 2 years, the storage stability of the formulations of the examples is considered to be high.

[0097] Test Example 2 (Spraying Test) The dilution solution was prepared using the formulation of the example, the spraying pressure test was carried out using a power sprayer, the amount of the free component outside the microcapsules before and after spraying in the dilution solution was measured, and the encapsulation rate in the formulation was measured from the calculation. The results are shown in Table 3. The spraying pressure test was carried out in the following manner. After diluting 50 mL of the formulation in 50 L of tap water to prepare a dilution solution for spraying, it was sprayed onto a polyfilm at a spraying pressure of 1.5 to 4.0 MPa, and the sprayed solution was collected. (Equipment used) Power sprayer: BIG M GS205 Nozzle used: D8 fan nozzle (manufactured by Yamaho Co., Ltd.) (Formulation used) Example 21

[0098] Here, the content of the free component in the dilution solution is the amount of the free component outside the microcapsules in the dilution solution, from which the encapsulation rate was calculated based on the total amount of the active ingredient using the following formula. As the analysis method, approximately 100 parts by mass of a 1000-fold dilution solution of the microcapsule formulation was passed through a membrane filter with a pore size of 45 μm to filter the microcapsules, and a sample solution was obtained. Separately, an acetonitrile solution with an active ingredient of about 20 ppm was prepared as a standard solution. The standard solution and the sample solution were analyzed by high performance liquid chromatography, the concentration of the free component of the active ingredient was determined by the absolute calibration curve method, and then the encapsulation rate of the active ingredient was calculated by the following formula (III).

[0099] Formula (III) Amount of free component (mg) = Concentration of standard solution (ppm) × (Peak area of sample solution / Peak area of standard solution) × Volume of dilution solution (L)

[0100]

Table 3

[0101] The formulation of the example showed a high encapsulation rate regardless of the spraying pressure. Since in agricultural chemical spraying with a normal speed sprayer or the like, it is often sprayed at 1.5 MPa or less, it is considered that the capsules of the formulation of this example do not break even after spraying, and the safety for the operator is ensured.

[0102] Test Example 3 (Disappearance Test) 2 mL of a 200-fold dilution of the microcapsule pesticide composition formulations of Example 21 and Comparative Example 9 was added to a petri dish. After drying, it was left in a greenhouse, and the amount of active ingredient after 1, 3, and 7 days was analyzed, and the attenuation rate of the initial strength was calculated. The results are shown in Figure 1. Also, electron micrographs showing the microcapsule shapes after 1, 3, and 7 days of Example 21 are shown in Figures 2 to 4, and electron micrographs showing the microcapsule shapes after 1, 3, and 7 days of Comparative Example 9 are shown in Figures 5 to 7.

[0103] The formulation of the example disappeared rapidly, and then the attenuation progressed with time, and more than 90% had disappeared after 7 days, so the initial effect of the active ingredient can be expected. On the other hand, in the formulation of the comparative example, almost no active ingredient decayed even after 3 days, and only about 40% disappeared even after 7 days. Therefore, the initial effect cannot be expected, and there is concern about the residue of the active ingredient. From the above, the microcapsule pesticide composition of the present invention can achieve both a thin capsule film thickness and a high capsule encapsulation rate, which were impossible in the past. As a result, it can withstand a high spraying pressure during pesticide spraying, reducing the toxicity to workers, and can achieve the initial effect by rapidly releasing the active ingredient.

Claims

1. A microcapsule pesticide composition comprising a microcapsule containing a pesticidal active ingredient having a water solubility of 1000 ppm or less at 20°C and an aqueous phase, wherein the volume median diameter of the microcapsule is 1 to 50 μm, and the film thickness of the microcapsule defined by the following formula (I) is 5 to 50 nm, the microcapsule is a microcapsule in which the film of the microcapsule is composed of a polyurea film and / or a polyurethane film having an aromatic ring structure, the pesticidal active ingredient is O,O-diethyl-O-2-isopropyl-6-methylpyrimidin-4-yl-phosphorothioate (common name: diazinon), (RS)-O-2,4-dichlorophenyl = O-ethyl = S-propyl = phosphorodithioate (common name: prothiofos), S-α-ethoxycarbonylbenzyl = O,O-dimethyl = phosphorodithioate (common name: PAP, phenthoate), or 2-sec-butylphenylmethylcarbamate (common name: BPMC, phenobucarb), the aqueous phase contains one or more aromatic polymer salts selected from the group consisting of lignin sulfonates, alkylnaphthalene sulfonates, and styrene maleates as a dispersant, and one or more inorganic salts selected from the group consisting of sodium chloride, potassium chloride, disodium hydrogen phosphate, sodium dihydrogen phosphate, dipotassium hydrogen phosphate, and potassium dihydrogen phosphate, the aromatic polymer salt is 0.01 part by mass or more and 5 parts by mass or less based on 100 parts by mass of the microcapsule pesticide composition, the inorganic salt is 0.01 part by mass or more and 5 parts by mass or less based on 100 parts by mass of the microcapsule pesticide composition, a microcapsule pesticide composition. Formula (I) Film thickness (nm) = (film substance weight / core substance weight) × (core substance density / film substance density) × (volume median diameter / 6) × 1000

2. The microcapsule pesticide composition according to claim 1, wherein the ratio of the volume median diameter of the microcapsule to the film thickness of the microcapsule (volume median diameter / film thickness) is 100 to 2000.

3. The microcapsule pesticide composition according to claim 1 or 2, wherein the content of the dispersant in the microcapsule pesticide composition is 0.01 to 5% by mass.

4. A method for producing a microcapsule pesticide composition, (1) (a) An agrochemical active ingredient that is O,O - diethyl - O - 2 - isopropyl - 6 - methylpyrimidin - 4 - yl - phosphorothioate (common name: diazinon), (RS) - O - 2,4 - dichlorophenyl = O - ethyl = S - propyl - phosphorodithioate (common name: prothiofos), S - α - ethoxycarbonylbenzyl = O,O - dimethyl - phosphorodithioate (common name: PAP, phenthoate), or 2 - sec - butylphenylmethylcarbamate (common name: BPMC, phenobucarb), and a polyisocyanate having an aromatic ring structure, wherein the content of the polyisocyanate having an aromatic ring structure is 3% by mass or less, an oil phase, and (b) A step of mixing an aqueous phase containing an aromatic polymer salt selected from the group consisting of lignin sulfonate, alkylnaphthalene sulfonate, and styrene maleate as a dispersant, and an inorganic salt selected from the group consisting of sodium chloride, potassium chloride, disodium hydrogen phosphate, sodium dihydrogen phosphate, dipotassium hydrogen phosphate, and potassium dihydrogen phosphate. The content of the aromatic polymer salt is 0.01 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the microcapsule agrochemical composition. The content of the inorganic salt is 0.01 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the microcapsule agrochemical composition. (2) A step of dispersing the mixture to prepare an O / W emulsion. (3) A step of adding a polyamine and / or a polyol to prepare microcapsules. A method for producing a microcapsule agrochemical composition according to the above steps.

5. The method for producing a microcapsule agrochemical composition according to claim 4, wherein the volume median diameter of the microcapsules is 1 to 50 μm, and the film thickness of the microcapsules defined by the following formula (I) is 5 to 50 nm. Formula (I) Film thickness (nm) = (film substance weight / core substance weight) × (core substance density / film substance density) × (volume median diameter / 6) × 1000

6. The method for producing a microcapsule agrochemical composition according to claim 4 or 5, wherein the ratio of the volume median diameter of the microcapsules to the film thickness of the microcapsules (volume median diameter / film thickness) is 100 to 2000.

7. The method for producing a microcapsule agrochemical composition according to any one of claims 4 to 6, wherein the content rate of the dispersant in the microcapsule agrochemical composition is 0.01 to 5% by mass.

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