JPWO2004049801A1 - Agricultural chemical microcapsule preparation by drying method in Oil / Oil liquid and method for producing the same - Google Patents

Abstract

A microcapsule production method comprising the following steps and a microcapsule preparation obtained by the method. (1) A step of dissolving one or more pesticidal active ingredients and a film-forming polymer mixture in a non-aqueous solvent A that can dissolve them. (2) A step of emulsifying and dispersing the solvent A solution in a non-aqueous solvent B that is incompatible with the solvent A. (3) A step of crystallizing the agrochemical active ingredient and the polymer by evaporating the solvent A in the emulsified and dispersed solution by heating and / or reducing pressure. (4) A step of obtaining a composite microcapsule preparation solidified by decantation and / or centrifugation. By the above production method, it is possible to provide an agrochemical microcapsule preparation method and a microcapsule preparation which can be easily produced and have a high recovery rate and microencapsulation rate.

Description

  The present invention relates to a method for producing an agrochemical microcapsule formulation that can be easily produced and has a high recovery rate and microencapsulation rate, and a microcapsule formulation obtained by the method.

Agrochemical microcapsule preparations have been conventionally produced by methods such as spray drying, interfacial polymerization, and in-liquid drying. (For example, see Non-Patent Document 1, Patent Document 1, and Patent Document 2)
Microencapsulation by the in-liquid drying method involves dispersing a film-forming polymer solution in which a core material is emulsified or dispersed in a water or oil medium, and dissolving the film-forming polymer by heating or reducing pressure while stirring. The solvent is distilled off to form a capsule film, and as a medium, water is generally used as a medium. (See Non-Patent Document 1 and Patent Document 4)
The spray drying method, which is known as the most common method for producing microcapsules of agricultural chemicals, has the disadvantage of poor productivity and high manufacturing costs. In the interfacial polymerization method, the content of agricultural chemical active ingredients in the microcapsule formulation is low. High formulation is difficult to obtain, and the spraying efficiency is poor. (See Patent Document 2 and Patent Document 3)
Regarding a microcapsule formulation of neonicotinoid insecticide similar to the present invention, Patent Document 3 manufactures a microcapsule containing 1% of acetamiprid by an interfacial polymerization method. Patent Document 4 describes a method of microencapsulating an O / W emulsion by a submerged drying method. The uptake rate into a microcapsule measured by washing treatment is 36.3%. And low.
Also known is a method for producing microcapsules by a method for drying a water-soluble substance in a liquid. (See Patent Document 5)
Non-Patent Document 1: “Basic Granulation and Engineering of Granulation”, “Granulation Handbook” (1991), edited by Japan Powder Industrial Technology Association, Ohm Co., Ltd., pages 60-64 Patent Document 1: Patent Japanese Patent No. 2848173 Patent Document 2: Japanese Translation of PCT International Publication No. 2002-523338 Patent Document 3: Japanese Patent Laid-Open No. 2000-95621 Patent Document 4: Japanese Patent Laid-Open No. 6-316504 Patent Document 5: Japanese Patent Laid-Open No. 6-65064

The object of the present invention is to produce a microcapsule formulation for agricultural chemicals and a microcapsule formulation which can be easily produced, have a high recovery rate and a high microencapsulation rate, and in particular, Neonicochi, which is highly water-soluble and difficult to encapsulate. It is to provide a microencapsulation method and a microcapsule preparation of a noidic insecticide.
A first aspect of the present invention is a method for producing a microcapsule comprising the following steps.
(1) A step of dissolving one or more pesticidal active ingredients and a film-forming polymer mixture in a non-aqueous solvent A that can dissolve them.
(2) A step of emulsifying and dispersing the solvent A solution in a non-aqueous solvent B that is incompatible with the solvent A.
(3) A step of crystallizing the agrochemical active ingredient and the polymer by evaporating the solvent A in the emulsified and dispersed solution by heating and / or reducing pressure.
(4) A step of obtaining a composite microcapsule preparation solidified by decantation and / or centrifugation.
The second is a microcapsule preparation obtained by the above production method.
In a preferred embodiment of the production method of the present invention, the film-forming polymer is one or more polymers selected from styrene-divinylbenzene copolymer, polyepsilon caprolactam, polylactic acid, and a copolymer of polylactic acid and glycolic acid. A manufacturing method, and
The non-aqueous solvent A has a boiling point that is at least 10 ° C. lower than the boiling point of the non-aqueous solvent B.

  FIG. 1 is a graph showing the results of Test Example 5.

The agrochemical active ingredient used in the present invention is a solid agrochemical having high solubility in the solvent A or a pesticide that is liquid at room temperature, and is particularly limited if it is poorly soluble in the solvent B and preferably has a solubility in the solvent B of 10,000 ppm or less. No, two or more types can be used in combination. For example, neonicotinoid compounds such as acetamiprid, pyrimidinyloxy compounds such as fluacrylpyrim, cyclohexanedione compounds such as cetoxidim, pyrethroid compounds such as aresulin, carbamate compounds such as benfuracarb, organophosphorus compounds such as fenitrothion, diflubenzuron There can be used urea-based compounds such as these, and these can be used alone or in combination. The method of the present invention is particularly suitable for microencapsulation of neonicotinoid insecticides, which are highly water soluble and difficult to encapsulate.
Solvent A used in the present invention has a low boiling point with respect to solvent B and is not particularly limited as long as it is not compatible with solvent B. Methanol, ethanol, acetonitrile, acetone, ethyl ether, isopropyl alcohol, methyl ethyl ketone, methylene chloride, There are benzene, hexane, chloroform, dichloromethane, dichloroethane, ethyl acetate, xylene, toluene, dimethyl sulfoxide, dimethylformamide, tetrahydrofuran, and the like. These can be used alone or in combination.
The solvent B used in the present invention has a high boiling point with respect to the solvent A and is not particularly limited as long as it is not compatible with the solvent A. Heavy naphtha, methyl isobutyl ketone, dichloropentagen, silicon oil, mineral spirit, petroleum Aromatic hydrocarbons, cyclohexanone, isophorone, cellosolve, butylcellosolve, ethylcarbylol, butylcarbitol, cellosolve acetate, butylcellosolve acetate, arbitol acetate, tetradecenyl acetate, kerosene, heavy oil, light oil, octane, There are isooctane, nonane, etc., and one or more of these may be used in combination.
In order to efficiently dry in the liquid, it is preferable that the boiling points of the solvent A and the solvent B are at least 10 ° C. apart.
The polymer used in the present invention is a substance that envelops an agrochemical active ingredient, and is limited in terms of molecular weight, structure, etc. if it is a styrene-divinylbenzene copolymer, polyepsilon caprolactam, polylactic acid, or a copolymer of polylactic acid and glycolic acid There is no particular limitation, and one or more of these may be used in combination.
In the method of the present invention, by dissolving the water-soluble polymer compound in the solvent A and using it, the elution of the agrochemical active ingredient can be controlled. The water-soluble polymer compound is not particularly limited as long as it is a water-soluble polymer compound that is soluble in the solvent A, and examples thereof include polyethylene glycol, diglycolic acid added with polyoxyethylene, and dipropylamine added with polyoxyethylene. 1 type or 2 or more types can be mixed and used.
In the method of the present invention, an emulsifying / dispersing agent can be added to the solvent A and / or the solvent B in order to assist emulsification / dispersion of the solvent A in which the pesticidal active ingredient and the polymer are dissolved in the solvent B. Examples of the emulsifier / dispersant include tri- or distyryl phenyl ether added with polyoxyethylene, alcohol ether added with polyoxyethylene, tween surfactant such as sorbitan oleate added with polyoxyethylene, and sorbitan oleate. Spun surfactants such as ate, sodium alkylnaphthalene sulfonate, sodium lauryl sulfate, sodium dodecyl sulfate, sodium lignin sulfonate, formaldehyde condensate of sodium alkyl naphthalene sulfonate, formaldehyde condensate of sodium phenol sulfonate, isobutylene-anhydrous malein Polyglycenol such as acid copolymer, sodium polycarboxylate, sodium alkylnaphthalene sulfonate and sodium alkylbenzene sulfonate Examples include synthetic ricinoleate, decaglyceryl monolaurate, gelatin, gum arabic, casein, dextrin, pectin, sodium alginate, methylcellulose, ethylcellulose, polyvinyl alcohol, polyvinylpyrrolidone, etc. Can do.
The amount of each component used in the production of the microcapsule preparation of the present invention varies depending on the type of the pesticidal active ingredient, but usually, the pesticidal active ingredient is 0.01 to 60% by weight, preferably 0 as a ratio to the whole. 0.01 to 40% by weight, the polymer for wrapping the pesticidal active ingredient is 0.005 to 80% by weight, preferably 0.005 to 50% by weight, and the solvent A for dissolving the pesticidal active ingredient and the polymer is 0.1 to 60% by weight. %, Preferably 0.1 to 50% by weight, solvent B 30 to 99% by weight, preferably 50 to 99% by weight, water-soluble polymer compound 1 to 50% by weight, preferably 5 to 50% by weight, emulsified -The surfactant for dispersion is 0 to 30% by weight, preferably 0 to 20% by weight.
In practicing the present invention, one or two or more of agrochemical active ingredients and one or two selected from a styrene-divinylbenzene copolymer, polyepsilon caprolactam, polylactic acid, and a copolymer of polylactic acid and glycolic acid. A polymer mixture of seeds or more is dissolved in a solvent A that can dissolve them, and added to a solvent B that is incompatible with the solvent A and emulsified and dispersed. At this time, a water-soluble polymer compound may be added to the solvent A in order to control the dissolution property of the pesticidal active ingredient, and an emulsifying / dispersing agent may be added to the solvent A or B. Next, the solvent A in the emulsified and dispersed solution is evaporated by heating and decompression to crystallize the pesticidal active ingredient and the polymer. Next, by removing the solvent B from the suspension by decantation, centrifugation, or the like, a microcapsule preparation having a high concentration of the pesticidal active ingredient in the microcapsules can be obtained with low production cost and high production efficiency. In addition, fine structure control is possible in the process of evaporating the solvent A by heating / depressurization, and the fine structure of the capsule material can be freely controlled in the range of 0.05 nm to 10 μm. By changing the size, the size of the capsule can be freely controlled to 10 nm to 1000 μm.

  EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these.

1 g of acetamiprid and 2 g of polylactic acid are dissolved in 20 g of acetonitrile, added to 200 g of silicon oil, and emulsified with a mixer for 1 hour (liquid temperature 25 ° C., mixer rotation speed 500 rpm). Next, the temperature of the mixer is kept at 500 rpm, the liquid temperature is raised to 75 ° C., and dried under reduced pressure at 700 mmHg for 3 hours to completely evaporate acetonitrile and encapsulate acetamiprid with polylactic acid. Only the solid component was removed from the suspension by decantation to produce a microcapsule preparation having an acetamiprid content of about 30%.
The composition of this microcapsule formulation is 1 g of acetamiprid and 2 g of polylactic acid, and the acetamiprid content is about 30%.

また、試験例５の結果を図１に示す。図１から本発明のマイクロカプセルはアセタミプリドの溶出率を制御していることが分かる。1 g of acetamiprid and 2 g of polyepsilon caprolactam are dissolved in 50 g of ethyl acetate, added to 200 g of silicon oil, and emulsified with a mixer for 1 hour (liquid temperature 25 ° C., mixer rotation speed 500 rpm). The temperature of the mixer is kept at 500 rpm, the liquid temperature is raised to 75 ° C., and dried under reduced pressure at 700 mmHg for 2 hours to completely evaporate ethyl acetate and encapsulate acetamiprid with polyepsilon caprolactam. Only the solid component was removed from the suspension by decantation to produce a microcapsule preparation having an acetamiprid content of about 30%.
The composition of this microcapsule formulation is 1 g of acetamiprid and 2 g of polyepsilon caprolactam, and the acetamiprid content is about 30%.
Comparative Example 1
An organic phase is produced by dissolving in 1 g of acetamiprid, 2 g of polylactic acid, 1 g of POE tristyryl phenyl ether and 50 g of dichloroethane. Next, 4 g of polyvinyl alcohol and 1 g of decaglyceryl monolaurate are dissolved in 500 g of water to produce an aqueous phase. The organic phase is added to the aqueous phase and emulsified with a mixer for 5 minutes (liquid temperature 40 ° C., mixer rotation speed 500 rpm), and the dichloroethane is completely evaporated by drying under reduced pressure at 40 ° C. and 700 mmHg for 3 hours at a mixer rotation speed of 5000 rpm. Acetamiprid is encapsulated with polylactic acid. Only the solid component was taken out from this suspension by decantation to produce a microcapsule preparation.
Comparative Example 2
An organic phase is produced by dissolving in 1 g of acetamiprid, 2 g of polylactic acid, 1 g of POE tristyryl phenyl ether and 50 g of dichloroethane. Next, 4 g of polyvinyl alcohol and 1 g of decaglyceryl monolaurate are dissolved in 500 g of water to produce an aqueous phase. The organic phase is added to the aqueous phase and emulsified with a homogenizer for 5 minutes (liquid temperature: 40 ° C., homogenizer rotation speed: 500 rpm), and the resulting suspension is sprayed using a spray dryer device (L-8 type, manufactured by Okawara Chemical Co., Ltd.). It was spray-dried at a drying temperature of 100 ° C. to produce a solid preparation in which acetamiprid was encapsulated with polylactic acid.
Comparative Example 3
1 g of acetamiprid and 0.5 g of protective colloid agent styrene maleic anhydride copolymer Na salt are heated and dissolved in 8 g of solvent SAS-296 and added to 86.5 g of water in which 2.5 g of urea is dissolved (2.5 g of urea + 84 g of water). After adjusting the pH to 3 with 10% aqueous citric acid, the mixture is emulsified with a homogenizer at 5000 rpm for 10 minutes. To this emulsion, 6.8 g of 37% formalin water (2.5 g of formalin) is added, the liquid temperature is raised to 70 to 75 ° C., and a urea-formalin resin is produced on the surface of the emulsified particles at a homogenizer of 10,000 rpm for 2 hours. After the reaction, the liquid temperature is lowered to 40 ° C. and adjusted to pH 7.5 with 28% aqueous ammonia. From this suspension, only the solid component was removed by decantation to produce an acetamiprid microcapsule preparation.
Test Example 1: Measurement of yield of microencapsulated preparation The yield was calculated from the charged amount (A) when 100% was recovered in the production of microcapsule preparation and the amount (B) recovered in actual production.
Yield (%) = B / A × 100
Test Example 2: Measurement of Agrochemical Active Ingredient Content in Microcapsule 10 g of the prepared microencapsulated solid preparation was immersed in 100 ml of methanol, and acetamiprid was extracted from the microcapsule with ultrasound for 30 minutes. The extracted acetamiprid was analyzed by HPLC, and the acetamiprid content in the microcapsules was calculated.
Test Example 3: Measurement of microencapsulation rate 10 g of the prepared microencapsulated solid preparation is immersed in 100 ml of hexane and gently stirred with a spatula for about 30 seconds. After stirring, the mixture was allowed to stand for 5 minutes, and after confirming that the microcapsule had settled, the supernatant was analyzed by HPLC, the amount of the active ingredient dissolved in hexane was measured, and the microencapsulation rate was calculated.
Microencapsulation rate (%) = (Amount of drug substance in microcapsule preparation−Amount of drug substance dissolved in hexane) / Amount of drug substance in microcapsule preparation × 100
Test Example 4: Measurement of formulation dilution properties 10 g of lignin sulfonic acid Na, 5 g of formaldehyde condensate of alkyl naphthalene sulfonic acid Na salt, a mixture of 2 g of alkyl naphthalene sulfonic acid Na and clay 73 g and a wet milling powder having a powder size of about 7 microns by jet milling. Manufacture base. 10 g of the microencapsulated solid preparation produced in Examples and Comparative Examples and 90 g of a wettable powder base are mixed in a mortar to produce a wettable powder. This wettable powder was diluted 1000 times with tap water and measured for dilution properties (measurement items; self-dispersibility, initial dispersibility, suspension stability, foamability).
<Evaluation methods>
Self-dispersibility: Dispersed state of drug when 0.25 g of wettable powder was dropped into 200 ml of tap water (250 ml graduated cylinder). Dispersed in a cloud shape ◎>○>△> × Not dispersible at all / Initial dispersibility: The number of inversions required to completely disperse the drug by inverting the graduated cylinder 30 seconds after dropping the drug.
Suspension stability: Amount of sediment over time after inverting the graduated cylinder 30 times (ml).
-Foaming property: Foam height (ml) after 30 minutes of inversion of graduated cylinder.
Test Example 5: Measurement of dissolution rate 0.1 g of acetamiprid-encapsulated microcapsules prepared in Example 1 was added to 500 ml of distilled water (dispersing agent polyoxyethylene (20) sorbitan monostearate was added to improve microcapsule dispersibility). .1 wt% addition), and this was shaken at 60 rpm in a thermostatic bath at 30 ° C. This was collected at regular intervals, filtered through a membrane filter (pore size 0.2 μm), and then the concentration of acetamiprid released slowly was measured with a UV / VIS spectrophotometer. The measurement wavelength was 244.6 nm, and measurement was performed using the multi-inspection quantity curve method. The sustained release rate was calculated by the following formula. Controlled release rate (%) = {(concentration of acetamiprid released from microcapsule) / (concentration of acetamiprid contained in microcapsule)} × 100
The results of Test Examples 1 to 4 are shown in Table 1 below.
Test results

The results of Test Example 5 are shown in FIG. 1 that the microcapsules of the present invention control the dissolution rate of acetamiprid.

  According to the present invention, a microencapsulated preparation of an agrochemical active ingredient with good dilution properties can be efficiently produced by a simple method.

Claims (7)

The manufacturing method of the microcapsule characterized by including the following processes.
(1) A step of dissolving one or more pesticidal active ingredients and a film-forming polymer mixture in a non-aqueous solvent A that can dissolve them.
(2) A step of emulsifying and dispersing the solvent A solution in a non-aqueous solvent B that is incompatible with the solvent A.
(3) A step of crystallizing the agrochemical active ingredient and the polymer by evaporating the solvent A in the emulsified and dispersed solution by heating and / or reducing pressure.
(4) A step of obtaining a composite microcapsule preparation solidified by decantation and / or centrifugation. 2. The production method according to 1, wherein the film-forming polymer is one or two or more polymers selected from a styrene-divinylbenzene copolymer, polyepsilon caprolactam, polylactic acid, and a copolymer of polylactic acid and glycolic acid. 3. The production method according to 1 or 2, wherein the non-aqueous solvent A has a boiling point that is at least 10 ° C. lower than the boiling point of the non-aqueous solvent B. Manufacture by dissolving a water-soluble polymer compound selected from polyethylene glycol, diglycolic acid added with polyoxyethylene, and dipropylamine added with polyoxyethylene in solvent A to control the dissolution of agrochemical active ingredients. 2. The composite microcapsule preparation according to 1, and a production method thereof. 5. The production method according to any one of 1 to 4, wherein the pesticidal active ingredient is a neonicotinoid insecticide. 6. The production method according to 5, wherein the neonicotinoid insecticide is acetamiprid. A microcapsule preparation produced by any one of the production methods 1 to 6 above.

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