JPH0692282B2 - Organophosphorus insecticidal composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention provides an organophosphorus insecticide having an average particle size of 80 μm or less, a film thickness of 0.1 μm to 1 μm, and The invention relates to a microencapsulated insecticidal composition capable of exerting an excellent residual effect, which is contained in a polyurethane coating having a film thickness of 20 to 400.

<Prior Art> In general, organophosphorus insecticides are excellent in efficacy immediately after spraying, but many of them decompose and disappear quickly when sprayed in the environment, and in cases where residual efficacy is required. May interfere with use. For example, in the field of controlling termites, organophosphorus insecticides are rarely used at present except for a part thereof, and organochlorine compounds such as chlordane, lindane and daeldrin have been widely used. However, although these organochlorine compounds are effective against termites for a long period of time, they have a problem in terms of residual toxicity, and their use is gradually regulated, and it is desired to develop a substitute for them. It is necessary to develop an insecticidal composition having an excellent residual effect using an insecticide that rapidly decomposes and disappears in such an environment.

In addition, for example, several kinds of organophosphorus insecticides are currently used in the field of controlling cockroaches, but they require reprocessing in a short period of time, and it is desirable to develop a dosage form that has long-lasting efficacy once sprayed. ing.

<Problems to be Solved by the Invention> The main advantage of encapsulating an insecticide is as follows.
This means that the microcapsules improve the residual effect. For example, the invention described in JP-A-58-144304 relates to an organophosphorus insecticidal composition obtained by microencapsulating an organophosphorus insecticide using a polyurethane coating, and It is described that the microcapsule has a clearly superior residual effect.

Thus, in many cases, when the compatibility between the encapsulating insecticide and the membrane substance is good, the residual effect tends to be improved by microencapsulating the insecticide. However, when the same insecticide is encapsulated with the same membrane substance, the residual effect is extended in many cases as compared with the case where it is not microencapsulated, and in some cases, the residual effect may differ between the microcapsules. This is because even microcapsules have specific optimum formulation factors depending on the field of use. That is, the present inventors have found that in order to obtain an excellent microencapsulated insecticide, it is an important point that various factors constituting the microcapsule, particularly, the particle size and the film thickness are appropriate. , Researched the optimum range.

<Means for Solving Problems> The present inventors diligently studied conditions under which the residual effect is particularly excellent when the organic phosphorus insecticide is microencapsulated with a polyurethane coating. As a result, when the organic phosphorus insecticide is microencapsulated with the polyurethane coating, the average particle size of the microcapsules is controlled to 80 μm or less,
On top of that, if the film thickness is set to 0.1 μm to 1 μm and (average particle size / film thickness) is controlled to 20 to 400,
It has been found that the residual effect is particularly good.

Among them, as an organic phosphorus insecticide, 0,0-dimethyl-0-
It was confirmed that when (3-methyl-4-nitrophenyl) phosphorothioate was used, the microcapsules were excellent in residual effect particularly on cockroaches and termites.

The method of microencapsulation is, for example, after suspending a hydrophobic solution containing a polyfunctional isocyanate and an organophosphorus insecticide in an aqueous solution containing a water-soluble polymer as a suspension dispersant in the form of microdroplets. , Causes a polymerization reaction with a polyhydric alcohol having two or more hydroxyl groups. After the encapsulation reaction, the obtained capsule dispersion is diluted as it is with pure water so as to have a predetermined drug substance concentration, and if necessary, a dispersion stabilizer is added to obtain a stable slurry type preparation.

As a polyhydric alcohol having two or more OH groups,
Ethylene glycol, propylene glycol, butyr
Glycol, hexanediol, heptanediol,
Dipropylene glycol, triethylene glycol,
Lyserine, resorcin, hydroquinone, etc.
It As the polyfunctional isocyanate, for example, toluene
Diisocyanate, hexamethylene diisocyanate
Toluene diisocyanate and trimethylolpropan
With hexamethylene diisocyanate
Condensate, and Sumidule L (Sumitomo Bayer Ureta
Made by Sumin Co., Ltd., Sumidule N (Sumitomo Bayer Ure
Tan Co., Ltd.) and the like.

On the other hand, as the composition of the hydrophobic liquid, when the polyfunctional isocyanate and the organophosphorus insecticide are soluble in each other, a mixture of these two can be directly used, but when they are not soluble in each other, they are dissolved in water. It is possible to use a homogeneous mixture of the three (polyfunctional isocyanate, organophosphorus insecticide, solvent) by selecting one that can dissolve the polyfunctional isocyanate and the organophosphorus insecticide in an immiscible organic solvent. desirable.
Examples of the organic solvent used for this purpose include hydrocarbons such as xylene, toluene, alkylbenzene, hexane, and heptane, chlorinated hydrocarbons such as chloroform, ketones such as methyl ethyl ketone and cyclohexanone, and phthalic acid in common organic solvents. It can be selected from esters such as diethyl and n-butyl acetate. As a dispersant for suspending and dispersing a hydrophobic solution containing an organophosphorus insecticide and a polyfunctional isocyanate, natural polysaccharides such as gum arabic, carboxymethyl cellulose, semisynthetic polysaccharides such as methyl cellulose, polyvinyl alcohol, etc. Synthetic polymer, mineral fine powder such as magnesium / aluminum silicate, etc. may be used alone or in admixture of two or more. When the suspension dispersibility is weak, the suspension dispersibility can be improved by adding a known surfactant described in “Synthetic Surfactant” by Hiroshi Horiguchi. As the dispersion stabilizer of the capsule slurry, the water-soluble polymers listed as the above-mentioned dispersants may be used as they are, but if necessary, natural polysaccharides such as xanthan gum and locust bean gum, carboxymethyl cellulose and the like. The semi-synthetic polysaccharide, the synthetic polymer such as polyacrylic acid sodium salt, and the fine mineral powder such as magnesium / aluminum silicate may be used alone or in combination of two or more as a thickener.

As an organic phosphorus insecticide, 0,0-dimethyl-0- (3
-Methyl-4-nitrophenyl) phosphorothioate (hereinafter referred to as fenitrothion), 0,0-dimethyl-0- (4-cyanophenyl) phosphorothioate (hereinafter referred to as cyanophos), 2-methoxy- 4H-
Examples include 1,3,2-benzodioxaphosphorine-2-sulfide (hereinafter referred to as salicione) and the like, but it is also possible to use a mixture with another insecticide.

Further, if necessary, a stabilizer such as BHT (2,6-di-tert-butyl-4-methylphenol) can be added.

The average particle size of the microcapsules is determined by the type and concentration of the dispersant used for suspension dispersion, and the strength of mechanical stirring during suspension dispersion. For the measurement of the average particle diameter, for example, Coulter Counter Model TA-II type (manufactured by Nikkaki Co., Ltd.) can be used.

The film thickness of the microcapsules varies depending on the ratio of the volume of the core substance to the volume of the film substance, but can be obtained by the following approximate expression. That is, if the weight of the core substance of the microcapsule is Wc, the weight of the membrane substance is Ww, the density of the membrane substance is ρw, the density of the core substance is ρc, and the average particle diameter of the core substance is d. Becomes

The film thickness referred to in the present invention is calculated using this equation.

<Example> Next, the present invention will be described in more detail with reference to Examples, Comparative Examples and Test Examples.

Example 1 Sumidule L 12g (same as above) fenitrothio
To 200 g and stir until it becomes a uniform solution.
Amount of 350% aqueous solution containing gum arabic as an emulsifying dispersant
In addition to T.K.
Sir (trade name of Tokushu Kika Kogyo Co., Ltd.) for several minutes
I stirred. The rotation speed was 1800 rpm. Then ethylene
After dropping 6g of recall into the reaction system,
If the reaction is carried out with gentle stirring for an hour, the microcapsule
A dispersion of the chloride was formed. Add pure water to this and add
Adjust the amount to 1000g, 20% by weight active ingredient concentration
A fenitrothion capsule slurry of
1).

The average particle size of the obtained microcapsules is 80 μm, and the film thickness is
It was 0.67 μm and (average particle size / film thickness) was 119.

Example 2 Sumidule L (Same as above) to 9g, T.K.
Set the rotation speed of Toho homomixer (same as above) to 3200 rpm
The same operation as in Example 1 was carried out except that
20 wt% fenitrothion capsule slurry was obtained
(This composition 2).

The average particle size of the obtained microcapsules is 50 μm, and the film thickness is
0.32 μm, (average particle size / film thickness) was 156.

Example 3 Sumidule L (Same as above) to 4g, T.K.
Set the rotation speed of Toho homomixer (same as above) to 3400 rpm
The same operation as in Example 1 was carried out except that
20 wt% fenitrothion capsule slurry was obtained
(This composition 3).

The average particle size of the obtained microcapsules is 45 μm, and the film thickness is
0.13 μm, (average particle size / film thickness) was 346.

Example 4 Sumidule L (Same as above) to 10g, T.K.
Rotating speed of auto homomixer (same as above) to 5600 rpm
The same operation as in Example 1 was performed except that the active ingredient concentration was increased.
20% by weight fenitrothion capsule slurry was obtained
(This composition 4).

The average particle size of the obtained microcapsules is 20 μm, and the film thickness is
0.14 μm, (average particle size / film thickness) was 143.

Example 5 Sumidule L (Same as above) to 15g, T.K.
Rotation speed of auto homomixer (same as above) to 7200 rpm
The same operation as in Example 1 was performed except that the active ingredient concentration was increased.
20% fenitrothion capsule slurry was obtained (book
Composition 5).

The average particle size of the obtained microcapsules is 12 μm, and the film thickness is
0.13 μm, (average particle size / film thickness) was 92.

Example 6 Sumidule L (Same as above) to 8g, T.K.
Set the rotation speed of Toho homomixer (same as above) to 5600 rpm
The same operation as in Example 1 was carried out except that
20 wt% fenitrothion capsule slurry was obtained
(This composition 6).

The average particle size of the obtained microcapsules is 20 μm, and the film thickness is
0.11 μm, (average particle size / film thickness) was 182.

Example 7 Sumidule L (Same as above) to 15g, T.K.
Rotating speed of auto homomixer (same as above) to 5600 rpm
The same operation as in Example 1 was performed except that the active ingredient concentration was increased.
20% by weight fenitrothion capsule slurry was obtained
(This composition 7).

The average particle size of the obtained microcapsules is 20 μm, and the film thickness is
0.21 μm, (average particle size / film thickness) was 95.

Example 8 Sumidule L (Same as above) to 60g, T.K.
Rotation speed of the homotomixer (same as above) is 6000 rpm
Example except that the amount of ethylene glycol was changed to 10 g
Perform the same operation as in step 1, and perform a test with a concentration of 20% by weight of the active ingredient.
A nitrothion capsule slurry was obtained (present composition 8).

The average particle size of the obtained microcapsules is 20 μm, and the film thickness is
0.79 μm, (average particle size / film thickness) was 25.

Example 9 Sumidule L (Same as above) Change to single
L 8g (same as above) and toluene diisocyanate
Red (Sumijour F80 , Sumitomo Bayer Urethane Co., Ltd.
(Manufactured by the company) using 1 g of T.K. auto homomixer (same as above)
The rotation speed of 4) to 4500 rpm and the amount of ethylene glycol to 8
Example except that the stirring time in the constant temperature bath was 20 hours in g
Perform the same operation as in step 1, and perform a test with a concentration of 20% by weight of the active ingredient.
A nitrothion capsule slurry was obtained.

The average particle size of the obtained microcapsules is 30 μm, and the film thickness is
0.20 μm, (average particle size / film thickness) was 150.

Example 10 Sumidule L Fenitrothion 9g (same as above)
Add to 200g and stir until it becomes a uniform solution.
% Aqueous solution containing polyvinyl alcohol as an emulsifying dispersant
In addition to 400 g, T.K.
Stir with a momixer (same as above) for a few minutes. At that time
The rotation speed was 1200 rpm. Then ethylene glycol 7
After dropping g into the reaction system, slowly in a constant temperature bath at 60 ° C for 24 hours.
When the reaction is performed while stirring,
A dispersion formed. Add pure water to this and add 1000 to the total weight.
After adjusting to g, 0.3 weight of zanthan gum
%, Magnesium-aluminum silicate 0.6% by weight
Dilute twice with thickening agent solution containing 10% by weight of active ingredient
A fenitrothion capsule slurry was obtained.

The average particle size of the obtained microcapsules is 50 μm, and the film thickness is
0.32 μm, (average particle size / film thickness) was 156.

Example 11 Sumidur N 10g (same as above) fenitrothio
To 200 g and stir until it becomes a uniform solution.
Amount of 350% aqueous solution containing gum arabic as an emulsifying dispersant
In addition to T.K.
Stir with a sir (same as above) for a few minutes. Number of rotations at that time
Was 5600 rpm. Then 6 g of propylene glycol
After dropping into the reaction system, gently in a constant temperature bath at 70 ° C for 36 hours
When the reaction is carried out while stirring,
Sprinkling occurred. Pure water is added to this, and the total weight is 1000 g.
To 4% by weight carboxymethylce
Lulose (Serogen 3H , Daiichi Kogyo Seiyaku Co., Ltd.) water
Fenitro with an active ingredient concentration of 10% by weight
A thione capsule slurry was obtained.

The average particle size of the obtained microcapsules is 20 μm, and the film thickness is
0.15 μm, (average particle size / film thickness) was 133.

Example 12 Sumidule L Use the same amount as above (9g)
The phosphorus phosphorus insecticide is used in Siaphos and T.K.
-(Same as above) except for 3200 rpm
The same operation as in Example 1 was performed, and the active ingredient concentration of 20% by weight was
Ianox capsule slurry was obtained.

The average particle size of the obtained microcapsules is 50 μm, and the film thickness is
The average particle size / film thickness was 0.34 μm, which was 147.

Comparative Example 1 Sumidule L (Same as above) to 2.2g, T.K.
Rotating speed of the auto homomixer (same as above) to 3400 rpm
The same operation as in Example 1 was performed except that the active ingredient concentration was increased.
20% by weight fenitrothion capsule slurry was obtained
(Comparative composition 1).

The average particle size of the obtained microcapsules is 45 μm, and the film thickness is
0.07 μm, (average particle size / film thickness) was 643.

Comparative Example 2 Sumidule L (Same as above) to 60g, T.K.
Rotational speed of the auto homomixer (same as above) is 3200 rpm
Example except that the amount of ethylene glycol was changed to 10 g
Perform the same operation as in step 1, and perform a test with a concentration of 20% by weight of the active ingredient.
Nitrothion capsule slurry was obtained (comparative composition
2).

The average particle size of the obtained microcapsules is 50 μm, and the film thickness is
1.98 μm, (average particle size / film thickness) was 25.

Comparative Example 3 Sumidur L (Same as above) to 2.4g, T.K.
Rotate homomixer (same as above) to 1200 rpm
The same operation as in Example 1 was performed except that the active ingredient concentration was increased.
20% by weight fenitrothion capsule slurry was obtained
(Comparative composition 3).

The average particle size of the obtained microcapsules was 100 μm, the film thickness was 0.17 μm, and (average particle size / film thickness) was 588.

Comparative Example 4 A fenitrothion emulsion having an active ingredient concentration of 20% by weight was produced by a conventional method according to the following formulation (Comparative Composition 4).

Fenitrothion 20 parts by weight Solpol SM-100P 10 parts by weight (Thoho Kagaku registered trademark; mixture of nonionic surfactant and anionic surfactant) Xylene 100 parts by weight Test Example 1 Compositions 1 to 4 and 8 And comparative compositions 1 and 2
20 times diluted with each water, and further comparative composition 4
A 10-fold dilution of (emulsion) with water was prepared and uniformly coated on a 15 cm x 15 cm veneer plate surface at a rate of 50 ml / m ² , air dried for 2 hours, and then a plastic ring (diameter 13 cm, height 5 cm) ( Inner butter coating for escape prevention) was placed, and the German cockroach adults were released as a group of 10 adults, and after forced contact for 2 hours,
All test insects were collected in a collection container, water and food were given, and the mortality rate after 3 days was calculated.

Also, using the same treated surface, the mortality rate was calculated after 2, 4 and 8 weeks from the treatment.

Test Example 2 On a 15 cm × 15 cm cina plywood plate, 5 ml of a water dilution of the reagent solution was sprayed from a distance of 60 cm with a spray gun. The discharge pressure of the spray gun was 0.6 μg / cm ² . 25 after air drying
On the treated surface at ℃ and 100% relative humidity
Heads were inoculated, and the mortality rate after 24 hours was calculated. After the test,
The treated veneer boards were placed in a thermostat at 40 ° C., and after 1, 3 and 6 months, the anticidal activity against the termites on the treated surface was similarly examined. The test was performed in 5 replicates.

<Effects of the Invention> As described above, the microencapsulated organophosphorus insecticidal composition of the present invention generally gives organophosphorus insecticides, which are often rapidly decomposed in the environment, with further persistence. It is a useful thing.

Among organic phosphorus insecticides, 0,0-dimethyl-0- (3-
When methyl-4-nitrophenyl) phosphorothioate is used, the effect is particularly strong in the efficacy against cockroaches and termites, resulting in an insecticidal composition having a long persistence.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takaaki Ito 4-2-1 Takashi, Takarazuka-shi, Hyogo Sumitomo Kagaku Kogyo Co., Ltd. (72) Inventor Hitoshi Kawada 4-2-1 Takashi, Takarazuka-shi, Hyogo Sumitomo Kagaku Kogyo Co., Ltd. (72) Inventor Goro Shinjo 4-2-1 Takashi Takarazuka-shi, Hyogo Sumitomo Kagaku Kogyo Co., Ltd. (72) Inventor Kozo Tsuji 3-chome Kasuga, Konohana-ku, Osaka, Osaka No. 1-98 Sumitomo Chemical Co., Ltd. (56) Reference JP-A-58-144304 (JP, A) JP-A-60-156546 (JP, A)

Claims (1)

[Claims] 1. An average particle size of 80 μm or less and a film thickness of 0.1
μm to 1 μm, and (average particle size / film thickness)
A microencapsulated organophosphorus insecticidal composition, characterized in that the organophosphorus insecticide is encapsulated in a polyurethane coating film of 20 to 400.