JPH0625043B2 - Stable O / W type insecticidal emulsion formulation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Object of the present invention The present invention provides an O / W emulsion formulation having stability during storage, that is, an insecticide in the form of a hydrophobic liquid substance emulsified in water using an emulsifier. The present invention relates to an improved technique for emulsion formulations.

2. Description of the Related Art So far, suspension agents have been developed in which hydrophobic concentrated drug active ingredients are suspended and dispersed using water as a dispersion medium. The hydrophobic active ingredient here is almost solid. However, although various studies have been carried out on the formulation of emulsion-dispersed liquid concentrated active ingredients using water as a dispersion medium, both formulations have stability during storage, suspension stability in water, and dispersion at the time of application. It is still not sufficient from various points of view such as the degree of expression of the effect of the active ingredient and the chemical damage to crops. Therefore, none of the suspension agents containing water as a dispersion medium and containing a liquid concentrated active ingredient have been practically used. One of the results of the research so far is water-based, which is the same concentrated active ingredient as in the present invention. MEP and BPM
Studies have been conducted on a preparation in which a liquid mixture with C is emulsified and dispersed with polyvinyl alcohol (JP-A-60-1).
85705). According to this method, the content of the active ingredient in the preparation must be 50% by weight or less in order to obtain good emulsified dispersion. Therefore, in the present situation where a small amount of high concentration preparation is sprayed for labor-saving pest control, it is still unsatisfactory in terms of content in the preparation.

Problems to be Solved by the Invention Aerial spraying using a helicopter is widely used in order to perform wide-area pest control labor-savingly and economically.

As a requirement desired as a formulation for aerial spraying used here, a concentrated drug active ingredient can be contained in the formulation at a high concentration of 50% or more, and the formulation may be used as it is or as a conventional spraying agent. Such a formulation should be uniformly suspended in water when diluted to about 10 times, which is much lower than the dilution of 200 to 5000 times with water, and can be easily sprayed in the air from the nozzle of the sprayer. Are listed. However, in the case of the MEP / BPMC mixed preparation, which is currently being investigated for use as an aerial spray, no preparation that can satisfy such requirements has been found. Therefore, it is desired to develop a new suspension formulation suitable for aerial spraying, which is a mixed formulation of MEP and BPMC.

It is an object of the present invention to develop and provide a new formulation that meets such a demand.

(B) Structure of the Invention Means for Solving the Problems The inventors of the present invention have earnestly studied to develop a new type of emulsion preparation that meets the above-mentioned object. as a result,
We have come up with a new emulsion formulation that meets that purpose.

That is, in the present invention, O, O-dimethyl O- (3-methyl-4-nitrophenyl) phosphorothioate (hereinafter referred to as “MEP”) and 2-sec-butylphenyl N are used as a pesticide active ingredient using water as a dispersion medium. In an emulsion preparation containing two components of methyl carbamate (hereinafter referred to as “BPMC”), a liquid mixture of the two components is contained in an amount of 50 to 70% by weight based on the total amount of the preparation, and a mixing ratio (weight ratio). 5) 15% by weight of a mixture of a nonionic surfactant having a ratio of 1:01 to 1:06 and calcium dodecylbenzene sulfonate (hereinafter referred to as “DBS”), and a thickener of 0.1 to 10% by weight. Is added, and the remaining amount of water is added to make 100% by weight, and the electrical conductivity at 25 ° C. is adjusted to 0.1 mS or more.
We have found an O / W insecticidal emulsion formulation.
Such an emulsion preparation of the present invention is excellent in stability during storage, and even when this preparation is diluted to a low magnification of about 10 times, there is no problem in terms of emulsifiability in water and conditions of air spraying. It was found that the insecticidal effect was as good as that of the commercially available MEP / BPMC mixed emulsion. The present invention has been made based on such findings.

Action In the present invention, MEP and BPMC are both known and used as insecticidal active ingredients. The nonionic surfactant and DBS are the active ingredients MEP and BPMC.
Is effectively used for stable emulsification in a small amount of water used as a dispersion medium for the preparation. In addition, the thickener maintains the viscosity of the emulsion formulation moderately, stabilizes the concentrated active ingredient in the formulation, and stabilizes and thickens the emulsion when a spray solution is prepared by diluting this in water. It is useful for improving adhesion to crops. In addition, it is essential that all of them contain a specific range of amount in a specific ratio in the preparation, and at the time of adjusting the conductivity of the preparation, at least 0.1 mS or more is required for the first time. The effect of can be brought.

Preparation Method In order to prepare the stable O / W type insecticidal emulsion preparation of the present invention, the following method may be followed. First, the mixing ratio of MEP and BPMC, which are the active ingredients of the present invention, is
There is no particular restriction on the formulation, and it can be appropriately changed depending on the target pest and the insecticidal efficacy. And it can be contained in the range of 50 to 70% by weight with respect to the total amount of the preparation of the mixture.

According to the present invention, if the content of the mixture of MEP and BPMC in the preparation is 50% by weight or less, it is not desirable in terms of work efficiency in aerial application, insecticidal effect and economy. Also M
If the content of EP and BPMC exceeds 70% by weight, the stability during storage and the physical properties when diluted with water are poor, and it becomes difficult to spray, which is not preferable from all points.

The surfactant used in the present invention must be a combination of two kinds of surfactants having different properties, and in this case, the nonionic surfactant and DBS are mixed in a mixing ratio of 1: 0. It is necessary to use them together in the range of 1 to 1: 0.6. If it is used outside the range of this blending ratio, the emulsion stability during storage of the formulation will deteriorate, and when diluted with water, the emulsified state will be very poor, and uniform mixing will not be possible. Will end up. The amount of the surfactant added to the preparation is 5 to 1 in total of the two kinds of surfactants.
It is necessary to be in the range of 5% by weight. If an amount out of this range is added, the emulsion stability of the preparation becomes poor and the liquid mixture of MEP and BPMC separates into an oil in the preparation. Therefore, in the present invention, it is essential to mix the specific two kinds of surfactants in a specific ratio as described above and to add them in the formulation in an amount within a specific range.

Examples of the nonionic surfactant effectively used in the present invention include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene octylphenol ether, polyoxyethylene nonylphenol ether, polyoxyethylene styrenated phenol ether. , Polyoxyethylene distyrenated phenol ether, polyoxyethylene styrenated paraphenylphenol ether, polyoxyethylene cyclohexylphenol ether, polyoxyethylene benzil phenol ether, polyoxyethylene sorbitan fatty acid esters, oxyethyleneoxypropylene Block polymer etc. are mentioned.

As the thickener used in the present invention, for example, xanthan gum, tragacanth gum, guar gum, sodium alginate, sodium carboxymethyl cellulose,
Examples thereof include sodium carboxymethyl starch, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polyactylic acid and its derivatives, and magnesium aluminum silicate. The amount of these thickeners added may be in the range of 0.1 to 10% by weight.

Further, the conductivity of the emulsion preparation according to the present invention varies depending on the preparation composition and the stirring conditions at the time of preparation of the emulsion preparation, but in the present invention, a good emulsion preparation can be prepared by adjusting it to 0.1 mS or more. Can be prepared. That is, even in the case of a preparation having the same composition, the electric conductivity of an emulsion preparation needs to be 0.1 mS or higher, although the electric conductivity varies depending on the preparation method. When the conductivity is adjusted to be 0.1 mS or less, the emulsion stability of the formulation is deteriorated, and when stored for a long period of time, emulsion separation occurs, and when diluted with water, The emulsifier becomes so bad that it cannot withstand spraying.

Thus, in the present invention, it is essential to adjust the conductivity of the preparation to 0.1 mS or more in order to obtain stabilization of the preparation, but in order to control the conductivity of the preparation to 0.1 mS or more, The following method may be used.

That is, pesticide active ingredient (mixture of MEP and BPMC)
And 2 kinds of surfactants are mixed and heated to about 40 to 60 ° C., and the mixed liquid is stirred with a three-one motor (manufactured by HEIDON) at a rotation speed of about 300 to 600 rpm while water as a dispersion medium. And a small amount of thickener are added, the liquid temperature is lowered from room temperature to about 30 ° C., and stirring is continued for further 60 minutes or more. In this case, the conductivity of the preparation varies depending on the content of the active ingredient, the kind of the surfactant, the addition amount, etc., but the stirring may be stopped when it becomes approximately 0.1 mS to 0.4 mS.

The measurement of electric conductivity is not limited to a specific model, but for example, CM manufactured by Toa Denpa Kogyo Co., Ltd.
A -20E type may be used.

Next, examples of the present invention will be described.

Examples 1 to 8 Examples 1 to 8 having the compositions shown in Table 1 and the following preparation methods
The emulsion formulation of was prepared.

[Preparation method]

Mix the liquid mixture of MEP and BPMC and the mixture of nonionic surfactant and DBS and warm to 50 ° C. Using a three-one motor (manufactured by HEIDON), this mixed solution was added with water and a thickener while stirring at a rotation speed of 400 rpm, the liquid temperature was adjusted to 25 ° C., and the mixture was further stirred for 120 minutes to obtain the emulsion preparation of the present invention. And For the conductivity at this time, a CM-20E model conductivity meter manufactured by Toa Denpa Kogyo Co., Ltd. was used. The results are shown in Table 1.

3) Effects of the Invention When the stable O / W type insecticidal emulsion preparation of the present invention is carried out, the following effects are brought about.

First of all, in the present invention, the emulsion preparation is stored even for a long period of time, and the emulsion is not separated, so that the stability of the preparation is maintained.

Secondly, this formulation can be mixed evenly even when diluted about 10 times with water to obtain an aerial spray liquid, and a stable suspension, that is, a stable aerial spray liquid can be obtained. .

Thirdly, the emulsion preparation of the present invention is sufficiently exerted without impairing the original insecticidal activity of MEP / BPMC, which is an insecticidal active ingredient, and the conventional MEP / BPM.
It is possible to exert an insecticidal effect which is not inferior to the insecticidal effect by using the C-containing emulsion.

Fourthly, when the emulsion preparation of the present invention is sprayed in the air, it does not give any phytotoxicity to crops.

Fifth, since it does not contain an organic solvent such as the conventional MEP / BPMC-containing emulsion, it is possible to eliminate the baldness of the car paint and the harm to humans and animals when sprayed in the air.

Sixth, in order to further improve the work efficiency of aerial spraying, it can be mixed with other aerial spraying agents that are commonly used, and has a wide range of application.

Next, a test example of stability and insecticidal efficacy of the stable O / W type insecticidal emulsion preparation of the present invention will be shown.

Test Example 1 The emulsion formulations prepared according to Examples 1 to 8 were subjected to the following tests.

(1) Stability test of formulation 20 m of the emulsion formulation was placed in a test tube and sealed, and this was left in a thermostat at 40 ° C. After 4 weeks of standing, the stability of the emulsion preparation was visually observed according to the following criteria.

(-) No abnormality such as oil separation was observed.

Separation of (+) oil is observed.

(2) Dilutability test with water The emulsion preparation was diluted 6 times with 3 ° hard water,
Put 0 m into a cylinder with a stopper. And this at 20 ℃
Leave it in the water bath. After 2 hours of standing, the emulsion stability of the diluted solution was visually observed according to the following criteria.

(-) Emulsified uniformly and no abnormalities such as oil separation were observed.

(+) Emulsified particles are coarse and oil separation is observed.

In addition, (a) the compounding ratio of the nonionic surfactant and DBS is out of the range of 1: 0.1 to 1: 0.6, (b) the added amount of the surfactant mixture is 5 to 15% by weight. Outside the range of
(C) Amount of MEP and BPMC exceeding 70% by weight,
(D) Emulsion preparations having the same composition as the present invention but having an electric conductivity of less than 0.1 mS were prepared according to the examples of the present invention and used as control examples.

Regarding (d), the same preparation method as in the example of the present invention was used, but a final emulsion time was shortened to prepare a control emulsion preparation.

If oil separation occurs in this test, uniform spraying becomes difficult, and even if sprayed, the active ingredient particles are large, resulting in insufficient insecticidal effect, which is not preferable. Further, even if separation of oil is observed when diluted with water, it is also not preferable. Therefore, it is necessary that there is no oil separation.

The results are shown in Table 2.

Test Example 2 Insecticidal effect test 6 to 6 planted in a pot having a size of 1 / 10,000 ares
An emulsion formulation prepared according to the example was diluted 6-fold with water to 7-leaf stage rice (variety Nihonbare), and MEP was 48 g and BPMC was 32 g as active ingredients per 10 ares.
It was sprinkled so that On the day of spraying and 5 days later, cover the rice with a cylinder made of vinyl chloride, and incubate the green leafhoppers 10
I released my head. Then, the number of live and dead insects was examined 24 hours and 48 hours after the release, and the mortality rate (%) was calculated.

In addition, this test was carried out in a 3-division system for each reagent. The results are shown in Table 3.

Claims (1)

[Claims] 1. Water as a dispersion medium, as an agricultural chemical active ingredient,
In an emulsion preparation containing two kinds of components of O, O-dimethyl O- (3-methyl-4-nitrophenyl) phosphorothioate and 2-sec-butylphenyl N-methylcarbamate, a liquid mixture of the two kinds of components is prepared in a total amount. 50 to 70% by weight, and a compounding ratio (weight ratio) of the mixture of nonionic surfactant and calcium dodecylbenzene sulfonate of 5 to 15 % By weight, 0.1-10% by weight thickener, and 100% by weight of the remaining water, and 25
A stable O / W type insecticidal emulsion preparation characterized by having an electric conductivity at 0 ° C. adjusted to 0.1 mS or more.