JPS62215504A - Agricultural, insecticidal and acaricidal composition - Google Patents

Abstract

PURPOSE:An agricultural, insecticidal and acaricidal composition, obtained by encapsulating a pyrethroid based insecticide and acaricide in polyurea based films to form microcapsules, capable of exhibiting improved residual efficacy and having reduced toxicity to fishes. CONSTITUTION:Microcapsules, obtained by suspending a hydrophobic solution containing a polyfunctional isocyanate, e.g. toluene diisocyanate, and pyrethroid based insecticide and acaricide, e.g. fenvalerate, etc., in an aqueous solution containing a water-soluble high polymer, e.g. polyvinyl alcohol, etc., as a suspending and dispersing agent in a state of driplets, directly heating the suspension to carry out reaction with water, etc., initiating polymerization reaction, carrying out encapsulating reaction, directly diluting the resultant encapsulated dispersion with pure water to give a given parent chemical concentration, as necessary, adding a dispersion stabilizer and having <=80Xm average particle size, <=0.3mum film thickness and >=250 ratio of the average particle diameter of the film thickness.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention provides a microcapsule containing a pyrethroid insecticide and acaricide, which is made of a polyurea film, the average particle size of which is 80 μm or less, and the film thickness is A microencapsulated agricultural insecticide and acaricide that can exhibit excellent residual efficacy and is contained in a polyurea coating having a particle diameter of 0.8 μm or less and a (average particle size/film thickness) of 250 or more. Related to compositions 0 <Prior art> Pyrethroid insecticides and acaricides generally have fast-acting and high insecticidal and acaricidal efficacy, and can be used in emulsions, oils, wettable powders,
It has been formulated as a powder and has been put into practical use as an agricultural insecticide and acaricide, but in some cases it has low residual efficacy and is expensive, so it is necessary to find a more economical way to use it. is expected.

In addition, pyrethroid insecticides and acaricides are relatively highly toxic to fish and contain mold, and it is difficult to reduce this fish toxicity when formulated into formulations such as emulsions, oils, wettable powders, and powders. Therefore, the development of a preparation that reduces fish toxicity is also desired.

Generally, when an insecticide or acaricide is microencapsulated, the active ingredient is encapsulated as the core material of the microcapsule and is isolated from the environment outside the membrane, so it is not easily decomposed by microorganisms, moisture, light, etc. Furthermore, since the release of the active ingredient outside the membrane is controlled by the presence of the membrane, sustained release is achieved.

Microencapsulated insecticide for the above two reasons.
Acaricides often have superior residual efficacy compared to those that are not encapsulated.
The invention described in Publication No. 8285 relates to a pyrethroid insecticidal composition obtained by microencapsulating a pyrethroid insecticide using a polyurethane coating. It is stated that it has excellent residual effect.

As described above, in many cases, microencapsulation of insecticides and acaricides tends to improve their residual effectiveness.

<Problems to be solved by the invention> However, even if the same insecticide or acaricide is encapsulated with the same membrane material, a certain level of residual efficacy cannot always be expected; the degree of residual efficacy depends on the distance between microcapsules. There were times when there was a difference.

Additionally, microencapsulation generally tends to reduce the fish toxicity of insecticides and acaricides;
There were some differences between microcapsules.

As a result of extensive studies, the present inventors have discovered that various factors constituting microcapsules, particularly particle size and film thickness, have a significant effect on residual efficacy and reduction of fish toxicity, and have completed the present invention. .

Means for Solving the Problems> The present inventors have intensively studied the conditions under which pyrethroid insecticides and acaricides for agricultural use can be microencapsulated with a polyurea film to achieve particularly excellent residual efficacy. As a result, when agricultural pyrethroid insecticides and acaricides are microencapsulated with a polyurea film, the average particle diameter of the microcapsules is 80 μm or less t'4J, and the upper film thickness is 0.
8 μm or less, and (average particle size/film thickness) is 250
If the above is achieved, the residual effect will be particularly good,
Moreover, it has been found that the formulation has reduced fish toxicity.

The microencapsulation method involves, for example, suspending a hydrophobic liquid containing a polyfunctional isocyanate and an organophosphorus insecticide in the form of microdroplets in an aqueous solution containing a water-soluble polymer as a suspending and dispersing agent. The polymerization reaction is caused by heating the mixture as it is to react with water, or by adding and heating a polyvalent amine having two or more amino groups. After the encapsulation reaction, the obtained capsule dispersion is directly diluted with pure water to a predetermined drug substance concentration, and if necessary, a dispersion stabilizer is added to form a stable slurry-type preparation. If an excess of amine is used during polymerization, it may be neutralized with, for example, HCl after the reaction.

Two or more NH! Examples of the polyvalent amine having groups include ethylenediamine, hexamethylenediamine, phenylenediamine, toluenediamine, diethylenetriamine, and the like.

Examples of polyfunctional isocyanates include toluene diisocyanate, hexamethylene diisocyanate, adducts of toluene diisocyanate and trimethylolpropane, self-condensates of hexamethylene diisocyanate, Sumidur LO (manufactured by Sumitomo Bayer Urethane Co., Ltd.), and Sumidur N. Examples include @ (manufactured by Sumitomo Bayer Urethane Co., Ltd.).

On the other hand, as for the composition of the hydrophobic liquid, if a polyfunctional isocyanate and a pyrethroid insecticide or acaricide dissolve in each other, a mixture of these kings can be used directly.
If they are not soluble in each other, select an organic solvent that is difficult to miscible with water and that can dissolve the polyfunctional isocyanate and the pyrethroid insecticide or acaricide. acaricides, solvents)
It is desirable to use a homogeneous mixture of Examples of organic solvents used for this purpose include hydrocarbons such as xylene, toluene, alkylbenzene, phenylxylylethane, hexane, and heptane, chlorinated hydrocarbons such as chloroform, methyl ethyl ketone, and cyclohexanone. Ketones, diethyl phthalate,
It can be selected from esters such as n-butyl acetate. Dispersants for suspending and dispersing hydrophobic solutions containing pyrethroid insecticides, acaricides, and polyfunctional isocyanates include natural polysaccharides such as gum arabic, semisynthetic polysaccharides such as carboxymethyl cellulose, and methyl cellulose; Synthetic polymers such as polyvinyl alcohol, fine mineral powders such as magnesium/aluminum silicate, etc. are used alone or in combination of two or more. If the suspension-dispersibility is weak, the suspension-dispersibility can be improved by adding a known surfactant described in "Synthetic Surfactants" by Hiroshi Horiguchi. As a dispersion stabilizer for the capsule slurry, it is possible to use the water-soluble polymers listed above as dispersants as they are, but if necessary, natural polysaccharides such as xanthan gum and locust bean gum,
Semi-synthetic polysaccharides such as carboxymethylcellulose, synthetic polymers such as sodium polyacrylate, fine mineral powders such as magnesium aluminum silicate, etc. may be used alone or in combination of two or more as the thickener.

Pyrethroid insecticides and acaricides include fenvalerate (α-cyano-8-phenoxybenzyl α-isopropyl-41-chlorophenylacetate), fenpropathrin (α-cyano-8-phenoxybenzyl
2.2.8.8-tetramethelcyclopropanecarboxylate), permethrin (8-phenoxybenzyl 2
．． 2-dimethyl-8-(2,2-dichlorononvinyl)cyclopropene-1-carboxylate), dibermethrin (α-cyano-8-phenoxybenzyl
8-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate), tetramethrin (8
, 4,5゜6-titrahydrophtalielectrotomethyl chrysanthemate), allethrin (8-allyl-2-methylcyclopent-2-en-4-one-1-yl cis, trans-chrysanthemate), phenothrin (8-phenoxybenzyl cis, trans-chrysanthemate)
, deltamethrin (α-cyano-8-phenoxybenzyl 8(212-dibromovinyl) 2*2-dimethylcyclopropanecarboxylate), cyhalothrin (a-cyano-8-phenoxybenzyl 2,2-dimethyl-8-(8, 8,8-trifluoro-2-chloro-
(propenyl)-cyclopropanecarboxylate) and isomers thereof, natural pyrethrins, etc., but are not limited to these. In addition, it is also possible to use mixtures of these different pyrethroid insecticides and acaricides, as well as mixtures of pyrethroid insecticides, acaricides and pyrethroid insecticides, insecticides other than acaricides, and acaricides. . In addition, military agents such as piperonyl butoxide and the commonly used BHT (2°6
Stabilizers such as -di-t-butyl-4-methylphenol and the like can also be blended.

The average particle size of the microcapsules is determined by the type and concentration of the dispersant used during suspension and dispersion, and the intensity of mechanical stirring during suspension and dispersion. To measure the average particle size, for example, Coulter counter model TA-1 (
◎ The thickness of the microcapsule film varies depending on the ratio of the volume of the core material to the film material, but it can be determined using the following approximate formula: In other words, the weight of the core material of the microcapsule is We, the weight of the membrane material is Ww%, the density of the membrane material is -W, the density of the core material is -c1, the average particle diameter of the core material is d. Then, the film thickness referred to in the present invention was calculated using Shobu. <Example> Next, the present invention will be explained in further detail by giving Examples, Comparative Examples, and Test Examples. Example 1 A solution of Sumigel L (same as above) 4F and phenylxylylethane (product name Hysol 8AI9296, manufactured by Sumikichi Tai 1 Petrochemical Co., Ltd.) and 10G is stirred until it becomes a mixture, and this is mixed with polyvinyl alcohol (product name Gosenol GL- 050; manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd.) in a 10% aqueous solution 4002 at room temperature for several minutes using a T, K, autohomogen mixer (trade name of Tokushu Kika Kogyo Co., Ltd.) until it becomes minute l^. Stirred. Number of revolutions was 125.
It was 0 rpm.

Then, the mixture was allowed to react in a constant temperature bath at 60° C. for 24 hours with slight stirring to form a dispersion of microcapsules.

Pure water was added to the mixture to give a total weight of 1000 f to obtain a fenvalerate capsule slurry with an active ingredient concentration of 10% by weight (Present Composition 1).

The average particle size of the submerged microcapsules was 60 μm, the film thickness was 0.109 μm, and (average particle size/film thickness) was 459.

Example 2 The same operation as in Example 1 was performed except that the rotational speed of the T, K, autohomogen mixer (same as above) was changed to 650 Orpmlζ to obtain a fenvalerate capsule slurry with an active ingredient concentration of 10j51% (this composition Thing 2).

The average particle diameter of the obtained microcapsules was 5 μm%, and the film thickness was 0.011 μm (C average particle diameter/film thickness) was 455.

Example 8 The amount of Sumidur Le (same as above) was set to 0.82, and T
, set the rotation speed of the autohomogen mixer (same as above) to 6.
The same operation as in Example 1 was performed except that the speed was changed to 500 rpm to obtain a fenvalerate capsule slurry with an active ingredient concentration of 1011% (Present Composition 8).

The obtained microcapsules had an average particle size of 5 μm, a film thickness of 0.002 um, and a ratio of (average particle size/film thickness) of 2500, which was small.

Example 4 The amount of Sumidur L0 (same as above) was set to 0.22, and T
, The same operation as in Example 1 was performed except that the rotation speed of the autohomogen mixer (same as 1ζ described above) was changed to 2800 rpm, to obtain a fenvalerate capsule slurry with an active ingredient concentration of 10% by weight (Present Composition 4). .

The average particle size of the obtained microcapsules was 20 μm, the film thickness was 0.002 μm, and (average particle size/film thickness) was too
It was o.

Example 5 The amount of Sumidur Lo (same as above) was set to 4y, fenpropathrin was used instead of quenvalerate, and the rotation speed of the autohomogen mixer (same as above) was set to 650.
The same operation as in Example 1 was performed except that Orpm was used to obtain a fenpropathrin capsule slurry with an active ingredient concentration of 10% by weight (Present Composition 5).

The obtained microcapsules had an average particle diameter of 5 μm and a film thickness of 0.011 μm (average particle diameter/film thickness) of 455.

Example 6 1.5 g of Sumidur Le (same as above) was added to fenvalerate zooy, heated, stirred until a homogeneous solution was formed, and this was added to 850 g of an aqueous solution containing 51% gum arabic as an emulsifying dispersant. In addition, the mixture was stirred for several minutes under heating using a T, K, autohomogen mixer (same as above) until it became fine droplets. The rotation speed was 8500 rpm. Then, the mixture was reacted in a constant temperature bath at 80° C. for 20 hours with slight stirring to form a dispersion of microcapsules. Add pure water to this to make the total Mlk too
Transfer fenvalerate capsule slurry with an active ingredient concentration of 20% by weight so that it becomes OP (this composition 6).
).

The obtained microcapsules had an average particle diameter of 15 μm and a film thickness of 0.018 μm (average particle diameter/film thickness) of 1154.

Example 7 The same operation as in Example 7 was carried out except that the amount of Sumidur Le (same as above) was changed and the rotation speed of IP- (same as above) was changed to 550 Orpm. Propathrin capsule slurry was obtained (this composition 7
).

The average particle size of the obtained microcapsules was 50 μm, the film thickness was 0.08 μm, and (average particle size/film thickness) was 1667.

Example 8 Sumidur Le (same as above) 4F and Heizol 5AS-296” 1002 (same as above) were added to 100 t of permethrin, stirred until a homogeneous solution was obtained, and 6% by weight of gum arabic was emulsified and dispersed. Aqueous solution included as agent 8
Add to 50P and T, K at room temperature until it becomes micro droplets.

The mixture was stirred for several minutes using an autohomogen mixer (same as above).

The rotation speed at that time was 8000 rpm. Then 6
When the reaction was carried out in a constant temperature bath at 5° C. for 80 hours with slight stirring, a dispersion of microcapsules was produced. After adding pure water to this to adjust the total weight to ZooO+, it was further diluted to 2 times with a thickener solution containing xanthan gum O, Aiiit%, and magnesium aluminum silicate 0.6% by weight, and the active ingredient A permethrin capsule slurry with a concentration of 6% by weight was obtained (Present Composition 8).

The average particle size of the obtained microcapsules was 20 μm, the film thickness was 0.044 μm, and the ratio (average particle size/film thickness) was 466.

f to gibermethrin 1oof! This was added to 850f of an aqueous solution containing 5% by weight of gum arabic as an emulsifying and dispersing agent, and heated until it became fine droplets.

The mixture was stirred for several minutes using an autohomogen mixer (same as above). The rotation speed at that time was 5500 rpm. Then, after dropping ethylenediamine 6F into the reaction system,
When the reaction was carried out in a constant temperature water bath of C for 24 hours with constant stirring, a dispersion of microcapsules was formed.

After adjusting the pH of the system using 1N aqueous hydrochloric acid solution, pure water was added to adjust the total weight to 10,001.
Active ingredient concentration 10! % dibermethrin capsule slurry was obtained (Present Composition 9).

The average particle size of the obtained microcapsules was 60 μm, the film thickness was 0.065 μm, and the C average particle size/film thickness was 769.

Example 10 Sumidur N0 (same as above) 2g instead of Sumidur Lelf (same as described above) 22! , dibermethrin 100
The same operation as in Example 9 was carried out except that tetramethrine 100 f was used instead of f, phenylenediamine 6f was used instead of ethylenediamine 6F, and the rotation speed of the autohomogen mixer was set to 800 rpm.
A tetramethrin capsule slurry with a concentration of 0% was obtained (Present Composition 10).

The average particle size of the obtained microcapsules was 20 μm%, the film thickness was 0.027 μm, and (average particle size/film thickness) was 741.

Example 11 Sumidur Shi@ (same as above) IP and xylene 50f were added to allethrin 150f and stirred until a homogeneous solution was obtained, and this was added to an aqueous solution 5soy containing 5% by weight gum arabic as an emulsifying dispersant. The mixture was stirred for several minutes at room temperature using a T, K, autohomogen mixer (same as above) until it became fine droplets. The rotation speed was 8000 rpm. Next, a dispersion of microcapsules was produced by reacting in a 6G"O constant temperature bath with constant stirring for 24 hours. Pure water was added to this to adjust the total weight to 1000p. The mixture was further diluted twice with a 4% by weight carboxymethyl cellulose (Celogen 8I (e, manufactured by Dai-Kogyo Seiyaku Co., Ltd.) aqueous solution to obtain an allethrin capsule slurry with an active ingredient concentration of 7.6% by weight (Present Composition 11).

The average particle size of the obtained microcapsules was 20 μm, the film thickness was 0.01 μm, and the ratio (average particle size/film thickness) was 2000.

Example 12 Instead of Sumidur Le (same as above) alone, Sumidur Le (same as above) 0.8F and toluene diisocyanate (Sumidur T80°1 Sumitomo Bayer Urethane Co., Ltd.) 0.12 were used and replaced with fenvalerate. The same operation as in Example 6 was carried out, except that the rotation speed of the autohomomixer (same as described above) was set to sooorpm, and the active ingredient concentration was 20.
! A 1% i phenothrin capsule slurry was obtained (Present Composition 12).

The average particle size of the obtained microcapsules was 20 μm, the film thickness was 0.01 μm, and (average particle size/film thickness) was 2000.

Example 18 Sumidur L6 (same as above) 1y and fenitrothion (0,0-dimethyl-〇-(8-methyl-4-
Nitrophenyl) phosphorothioate) 160p was added to Fenvalerate 40F and stirred until a homogeneous solution was obtained.
The mixture was added to 0P and stirred for several minutes at room temperature using a T, K, autohomogen mixer (same as above) until it became fine droplets. The rotation speed was 7100 rpm. Then 60°C
When the reaction was carried out in a constant temperature bath with constant stirring for 24 hours, a dispersion of the microcapsules was produced. Add pure water to this to make the total weight 100 OP,
A capsule slurry with a fenitrothion concentration of 16% and a fenvalerate concentration of 41% was obtained (this composition 18%).
).

The average particle size of the obtained microcapsules was 10 am, @f
'L is 0.0067! AIM (average particle size/film thickness) is 16
It was 67.

Comparative Example 1 The amount of Sumidur Le (same as above) was set to 151, T,
Then, set the rotation speed of the autohomogen mixer (same as above) to 65.
The same operation as in Example 1 was carried out except that the concentration of the active ingredient was 10! % of fenvalerate capsule slurry was obtained (comparative composition 1).

The obtained microcapsules had an average particle size of 5 μm and a film thickness of 0.04 μms (average particle size/film thickness) of 126.

Comparative Example 2 The amount of Sumidur L4' (same as above) was set to 151, and T
, set the rotation speed of the autohomogen mixer (same as above) to 2.
The same operation as in Example 5 was carried out except that the concentration was changed to 15 Orpm to obtain a fenpropathrin capsule slurry having an active ingredient concentration of io weight i% (comparative composition 2).

The average particle size of the obtained microcapsules was 26 μm, the film thickness was 0.888 μon, and the ratio (average particle size/film thickness) was 75.

Comparative Example 3 A fenvalerate emulsion having an active ingredient concentration of 10% by weight was produced in a conventional manner according to the following formulation (Comparative Composition 8).

Fenvalerate 101 parts Tsurupol 8005X" 10! parts (Toho Chemical registered trademark name; mixture of nonionic surfactant and anionic surfactant) A fenpropathrin emulsion with a concentration of 10% by weight was produced by a conventional method (comparative composition 4)
.

Fenpropathrin 10 parts Trupol 8005Xo (same as above) 10 parts xylene The remaining toox was diluted 1000 times with a chemical solution, which was sprayed on a turntable using a spray gun to spray 50 ml per 6 pots. At this time, 0.0002% by weight of special Rino 6 (manufactured by Nihon Nohyaku Co., Ltd.) was added as a spreading agent to the diluted chemical solution.

The treated pots containing Citrus orchid were left in a glass greenhouse, and the leaves were cut off on a predetermined day and placed in a cup with a diameter of 12 am along with 10 8th instar larvae of Spodoptera japonica, and the number of dead insects was counted after 48 hours. The test was conducted eight times, and the mortality rate was calculated using the following formula.

The results are shown in Table 1).

＼、Test Example 2 Two weeks after sowing, green beans planted in pots (two plants per pot) were inoculated with mites (approximately 80 mites per pot) to female adult senaden.
After a day, a 1000-fold diluted solution of the drug was sprayed at 5 oul per 6 pots using a spray gun on a turntable. At this time, the special Rino 0 (same as above) 0.
0002% by weight was added as a spreading agent.

The treated pots were left in a mite room, and the number of female adult mites was counted on a designated day.

The results are shown in Table 2.

Table 2 Residual effectiveness against false spider mites (number of female mites; total of 5 pots) Test Example 8 A solution prepared by diluting the sample fenvalerate microcapsule slurry or the sample fenvalerate emulsion (comparative composition 8) to a predetermined concentration was added to a glass of 21elIIX16tsX28am. Pour 5 liters into a container and add 1 medaka to it.
0 fish were released and observed for survival after 48 hours, and based on the results, the half-lethal concentration of fenvalerate was determined (
TLm4. (MC). ).

A similar operation was performed using fenvalerate bulk instead of fenvalerate microcapsule slurry, and the half-lethal concentration of fenvalerate was determined (T
Lm4. ('rG). ).

TLm4. (MC)/TLm4. (TG) was calculated and used as the fish toxicity reduction rate. The results are shown in Table 8.

Table 8 Reduction rate of fish poison against Japanese medaka (Effect of the invention) As explained above, the microencapsulated agricultural insecticidal and acaricidal composition of the present invention is obtained from the pyrethroid agricultural insecticide and acaricide 1ζ-J 4I of residual effect and fish toxicity of !
It is a useful thing that can reduce the amount of carbon dioxide.

Procedural amendment format) June 1986 field

Claims (1)

[Claims] A microcapsule made of a polyurea film,
The average particle size is 80 μm or less, and the film thickness is 0.8 μm.
In the polyurea coating which is below and has (average particle size/film thickness) of 250 or more, pyrethroid insecticide,
A microencapsulated agricultural insecticidal and acaricidal composition characterized by encapsulating an acaricide.