JP7546278B2 - Herbicidal Composition - Google Patents

Description

The present invention relates to a herbicide composition, and in particular to a technical field that contains pelargonic acid. More specifically, the present invention relates to a herbicide composition that has excellent long-term stability and rapid action by forming a mixed vesicle of the herbicidally active ingredient pelargonic acid and one or more cationic surfactants.

Fatty acids with 6 to 12 carbon atoms, particularly pelargonic acid (common name: pelargonic acid, IUPAC name: nonanoic acid), which has 9 carbon atoms, are safe and fast-acting herbicidal compounds that are widely used around the world (see, for example, Patent Document 1).

Pelargonic acid is also used as a food additive and is attracting attention as a herbicidal active ingredient with a safe image, so there is a growing demand for herbicides that use pelargonic acid.

Pelargonic acid is a hydrophobic substance with a solubility in water of 32 ppm (30°C), and the development of a herbicide using pelargonic acid requires technology to solubilize or emulsify pelargonic acid.

For example, Patent Document 1 discloses a formulation technology in which pelargonic acid is stably present in water as an acid by using water as the main solvent and combining an anionic surfactant and a nonionic surfactant.

Patent Document 2 also discloses a technique for emulsifying pelargonic acid using a quaternary ammonium salt as a surfactant.

On the other hand, Patent Documents 3 and 4 disclose preparations in which the water solubility of pelargonic acid is improved by neutralizing it with an organic base.

JP 2016-190832 A Special Publication No. 5-502216 JP 2013-216643 A JP 2014-91739 A

As described above, the prior art includes preparations in which pelargonic acid exists in the form of an acid in water and is emulsified or solubilized with a surfactant (Patent Documents 1 and 2), and preparations in which pelargonic acid is neutralized with a basic substance to improve its water solubility (Patent Documents 3 and 4). The former, in which pelargonic acid exists as an acid, is known to exhibit a more rapid herbicidal effect than the latter, and is more desirable in that the herbicidal effect is more easily felt by consumers.

Incidentally, commercially available general-purpose herbicides are often sold in spray containers. In ordinary households, such herbicides are often left in their containers outdoors or in warehouses, making them highly susceptible to exposure to low and high temperature conditions. In such harsh storage environments, pelargonic acid in conventional pelargonic acid herbicides that are emulsified and solubilized by surfactants can separate.

Therefore, there is a demand for a pelargonic acid herbicide composition that can stably maintain a uniformly dissolved and dispersed state even under such harsh storage conditions. Although it is possible to increase the amount of surfactant to improve storage stability, this is not realistic because the increased amount of surfactant increases the price and also increases the viscosity of the product, resulting in problems such as reduced spray efficiency and uneven spraying. Thus, conventional pelargonic acid herbicides produced by conventional emulsification and solubilization methods still lack stability and have room for improvement.

The present invention was made in consideration of these points, and its purpose is to provide a herbicide composition that has excellent long-term stability and high rapid action.

To achieve the above object, the inventors of the present application have found a concentration range in which pelargonic acid having a carbonyl group and a cationic surfactant having a specific quaternary amine group can interact in water to form mixed vesicles of self-aggregation. They have also found that the formation of mixed vesicles in this way enables pelargonic acid to be uniformly dissolved and dispersed in water and stabilized for a long period of time, thus completing the present invention.

In other words, mixed vesicles are self-associations in which amphiphilic molecules that have both hydrophobic and hydrophilic properties are arranged without gaps to form spheres, rods, layers, etc. in water, and because the self-associations form multiple layers, pelargonic acid is uniformly contained, making it possible to stabilize high concentrations of pelargonic acid in water for a long period of time.

The herbicidal composition according to the present disclosure contains pelargonic acid as a herbicidal active ingredient, one or more cationic surfactants selected from monoalkyl cationic surfactants and dialkyl cationic surfactants, and water. The pelargonic acid and the cationic surfactant interact with each other in water to form mixed vesicles, and the pelargonic acid is characterized by being uniformly dissolved and dispersed in water.

It is believed that a sufficient herbicidal effect cannot be obtained if the pelargonic acid does not adhere to the surface of weeds when sprayed with a herbicide containing pelargonic acid as a herbicidal active ingredient. In contrast, the mixed vesicle-formed pelargonic acid of the present invention is contained within a self-association body by interacting with a cationic surfactant, and no study has been conducted to date as to whether the pelargonic acid can adhere to the surface of weeds when sprayed with this. Through studies by the present inventors, it has been confirmed for the first time that a mixed vesicle-formed pelargonic acid herbicide composition has a high herbicidal effect.

In other words, by containing one or more cationic surfactants selected from a group consisting of multiple surfactants that are monoalkyl cationic surfactants and multiple surfactants that are dialkyl cationic surfactants, pelargonic acid is uniformly dispersed and dissolved in water as a self-association of mixed vesicles, and when sprayed, the pelargonic acid that constituted the mixed vesicles adheres to the surface of weeds. This provides excellent stability over time and a high herbicidal effect even when left under low or high temperature conditions.

The concentration range of the pelargonic acid can be 1.5% by mass or more and 7.0% by mass or less. The concentration range of the pelargonic acid can also be 2.0% by mass or more and 6.0% by mass or less.

The concentration range of the cationic surfactant can be 1.8% by mass or more and 18.0% by mass or less. The concentration range of the cationic surfactant can also be 2.5% by mass or more and 16.0% by mass or less.

The concentration ratio of the cationic surfactant to the pelargonic acid can be 0.83 or more and 6.00 or less. The concentration ratio of the cationic surfactant to the pelargonic acid can also be 1.00 or more.

The herbicide composition may contain a monohydric or polyhydric alcohol. This configuration facilitates the formation of mixed vesicles. The alcohol may have a carbon number of 2 to 6 and a hydroxyl group number of 1 to 6. The alcohol concentration may be in the range of 2.0% by mass to 6.0% by mass. The alcohol concentration may be in the range of 2.5% by mass to 5.0% by mass.

The pH of the herbicide composition can be 2.5 or more and 5.0 or less. The herbicide composition can be a translucent liquid having mixed vesicles.

According to the present invention, a specific cationic surfactant and pelargonic acid form mixed vesicles in water, and high-concentration pelargonic acid is uniformly dispersed and dissolved in water, resulting in a herbicide with excellent long-term stability and rapid action.

The following describes in detail the preferred embodiments of the present invention. Note that the following description of the preferred embodiments is merely illustrative in nature and is not intended to limit the present invention, its applications, or its uses.

The herbicide composition according to the embodiment of the present invention is a liquid herbicide containing pelargonic acid as a herbicidally active ingredient, a specific cationic surfactant, water, and a specific alcohol. The herbicide can be stored, for example, in various containers. By storing the herbicide in a container, a product used for weed control is formed. The herbicide can be used by directly spraying it on weeds from the container in which it is stored, or it can be transferred to a container other than the container in which it is stored and sprayed on weeds. The container that stores the herbicide may be provided with a shower nozzle with multiple openings. The container that stores the herbicide may also be provided with a sprayer equipped with a pump mechanism. The container that stores the herbicide may also be an aerosol container equipped with a valve and a nozzle, and in this case, the herbicide composition according to the present invention is filled into the aerosol container together with a propellant.

(Pelargonic acid, the herbicidal active ingredient)
The herbicidally active ingredient pelargonic acid of the present invention may be used alone or as a major component (e.g., 90% or more) of a mixture containing other fatty acids. When other fatty acids are contained, the herbicidally active ingredient may be one or a mixture of carboxyl fatty acids having a hydrocarbon chain of 8 to 12 carbon atoms, including pelargonic acid.

Pelargonic acid exists in water by forming mixed vesicles through interaction with cationic surfactants. In other words, mixed vesicles are self-assemblies in which amphiphilic molecules that are both hydrophobic and hydrophilic are arranged without gaps to form a spherical shell or bag shape in water, and since the layers of the self-assembly form multiple phases, pelargonic acid is uniformly contained, which allows pelargonic acid to be stabilized in water for a long period of time.

The lower limit of the concentration range of pelargonic acid in the herbicide composition is 1.5 mass% or more, and more preferably 2.0 mass% or more. The upper limit of the concentration range of pelargonic acid is 7.0 mass% or less, and more preferably 6.0 mass% or less. If the concentration range of pelargonic acid exceeds the above upper limit, mixed vesicles are difficult to form, and the formed mixed vesicles are easily broken. In addition, if the concentration range of pelargonic acid is below the above lower limit, the herbicidal effect becomes insufficient.

(Cationic Surfactant)
In order to form the mixed vesicle in water, the specific cationic surfactant is required. The specific cationic surfactant is any one or any two or more cationic surfactants selected from a group of surfactants consisting of a plurality of surfactants classified as monoalkyl cationic surfactants and a plurality of surfactants classified as dialkyl cationic surfactants. The specific cationic surfactant may be only a monoalkyl cationic surfactant or only a dialkyl cationic surfactant. The specific cationic surfactant may contain a monoalkyl cationic surfactant and a dialkyl cationic surfactant. In this case, it may contain one monoalkyl cationic surfactant and two or more dialkyl cationic surfactants, or it may contain two or more monoalkyl cationic surfactants and one dialkyl cationic surfactant.

Examples of monoalkyl cationic surfactants include lauryl trimethyl ammonium chloride, myristyl trimethyl ammonium chloride, cetyl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride, behenyl trimethyl ammonium chloride, alkyl (C12-C16) trimethyl ammonium chloride, alkyl (C16-C18) trimethyl ammonium chloride, etc.

Examples of dialkyl cationic surfactants include dioctyl dimethyl ammonium chloride, didecyl dimethyl ammonium chloride, dilauryl dimethyl ammonium chloride, dialkyl (C12-C18) dimethyl ammonium chloride, didecyl dimethyl ammonium chloride, dialkyl dimethyl ammonium chloride, dialkyl (C16-18) dimethyl ammonium chloride, etc.

The lower limit of the concentration range of the specific cationic surfactant is 1.8% by mass or more, and more preferably 2.5% by mass or more. The upper limit of the concentration range of the cationic surfactant is 18.0% by mass or less, and more preferably 16.0% by mass or less. If the concentration range of the specific cationic surfactant is outside the above range, it becomes difficult to form mixed vesicles.

(Monohydric or polyhydric alcohol)
In order to ensure the formation of the mixed vesicles, it is preferable that the herbicide composition contains a specific alcohol. The specific alcohol is a monohydric or polyhydric alcohol, and is preferably an alcohol having 2 to 6 carbon atoms and 1 to 6 hydroxyl groups. Examples of such alcohols include ethyl alcohol, propyl alcohol, isopropyl alcohol, 1,3 butylene glycol, propylene glycol, dipropylene glycol, glycerin, and sorbitol.

By using the above alcohol, the formation of mixed vesicles becomes more certain. The lower limit of the alcohol concentration range is 0.01 mass% or more, preferably 2.0 mass% or more, and more preferably 2.5 mass% or more. The upper limit of the alcohol concentration range is 6.0 mass% or less, and more preferably 5.0 mass% or less. If the alcohol concentration range is outside the above range, mixed vesicles are difficult to form, or the formed mixed vesicles are easily broken.

(Concentration ratio of pelargonic acid to cationic surfactant R=b/a)
In addition, when the concentration of pelargonic acid is a and the concentration of the specific cationic surfactant is b, the concentration ratio R of the specific cationic surfactant to pelargonic acid can be expressed by the following formula 1.

R=b/a Formula 1

The lower limit of R is 0.83 or more, and more preferably 1.00 or more. The upper limit of R is 6.00 or less, and more preferably 5.00 or less. If the value of R is outside the above range, it becomes difficult to form mixed vesicles.

(Other ingredients)
The water may be purified water or ion-exchanged water. The herbicide may contain a preservative. Examples of the preservative include, but are not limited to, isothiazolinone derivatives.

The herbicide may also contain a pest control component. Examples of the pest control component include, but are not limited to, pyrethroid insecticides, neonicotinoid insecticides, and diamide insecticides. Examples of pyrethroid insecticides include transfluthrin, pyrethrin, allethrin, phthalthrin, tetramethrin, prallethrin, fenothrin, tralomethrin, cyfluthrin, resmethrin, permethrin, empenthrin, cyphenothrin, imiprothrin, fenpropathrin, fenvalerate, etofenprox, and silafluofen. Examples of neonicotinoid insecticides include imidacloprid, nitenpyram, acetamiprid, thiamethoxam, clothianidin, and dinotefuran. Examples of diamide insecticides include flubendiamide, chlorantraniliprole, and cyantraniliprole. Of these, one or more can be used in combination.

(Method for producing herbicidal composition)
An example of a method for producing a herbicide composition will be described. First, purified water heated to 70°C is prepared. The specific cationic surfactant, pelargonic acid, and alcohol are dissolved in this purified water. If a pest control component is contained, the pest control component is also dissolved. Then, the mixture is cooled to room temperature, and a preservative is added.

The following describes examples of the present invention, but the present invention should not be interpreted as being limited to these examples.

Table 1 shows the composition of the herbicides according to Examples 1 to 16 of the present invention. The concentration of pelargonic acid in Examples 1 to 16 is 1.50% by mass or more and 7.00% by mass or less. The concentration of the monoalkyl cationic surfactant is 0.90% by mass or more and 9.00% by mass or less. The concentration of the dialkyl cationic surfactant is 0.90% by mass or more and 15.00% by mass or less. The concentration of the alcohol is 3.00% by mass. The concentration of the preservative is 0.02% by mass. The balance is purified water.

The concentration ratio R of the cationic surfactant concentration b to the herbicide active ingredient concentration a is set to a range of 0.83 to 6.00.

(Appearance Evaluation)
After preparing the herbicidal composition samples of the Examples, they were placed in 100 ml glass bottles and visually evaluated for appearance at room temperature (RT). The same evaluation was also carried out for the Comparative Examples described below.

Transparent gel: transparent liquid or gel Translucent: translucent liquid Cloudy: cloudy liquid

(Confirmation and evaluation of mixed vesicles)
After preparing the herbicide composition sample of the embodiment, it was placed in a 100 ml glass bottle, and placed in a box with orthogonal polarizing plates (crossed Nicols) at room temperature (RT). The presence or absence of mixed vesicle formation was evaluated by shining light on the sample bottle from outside the polarizing plate box and visually observing the state of the light passing through the sample bottle through the polarizing plate. The same evaluation was also performed for the comparative examples described later.

○: Mixed vesicles present ×: No mixed vesicles present

As shown in Table 1, mixed vesicles were formed in all of Examples 1 to 16.

(Stability evaluation)
Next, the results of the stability test will be described. In the stability test, the herbicide composition samples of the examples were placed in 100 ml glass bottles and stored for one month in thermostatic chambers at room temperature (RT), 5°C, and 50°C. The condition (appearance) of the herbicide composition after one month of storage was visually evaluated, and the stability was evaluated according to the following criteria. The comparative examples described below were also evaluated in the same manner.

◯: No separation (single homogeneous phase).
△: Partial separation between upper and lower layers.
×: Completely separated into two phases.

As shown in Table 1, Examples 1 to 16 were rated "○" at all temperatures: "RT," "5°C," and "50°C." In other words, the mixed vesicles continued to exist without being destroyed, and it can be seen that separation and changes in properties are unlikely to occur even when stored in the extremely wide temperature range of 5°C to 50°C and for the extremely long period of one month. The same results would be obtained even if no preservatives were included.

Next, we will explain Comparative Examples 1 to 5.

Comparative Example 1 is an example that does not contain alcohol. In this Comparative Example 1, the "appearance (immediately after production)" was cloudy, and mixed vesicles were not formed immediately after production. In other words, mixed vesicles were not formed immediately after production, and the composition was rated "X" at all temperatures of "RT," "5°C," and "50°C," i.e., it was an unstable composition.

Comparative Example 2 is an example in which the concentration ratio R of the cationic surfactant concentration b to the herbicide active ingredient concentration a is 0.33. In this Comparative Example 2, the product was cloudy in the "Appearance (immediately after production)" category, and mixed vesicles were not formed immediately after production. In addition, the product was stable at "RT" and "5°C", but separation occurred at "50°C". In other words, the product was stable in a relatively low temperature environment, but unstable in a high temperature environment.

In Comparative Example 3, a transparent gel was formed in the "Appearance (immediately after production)" category, and mixed vesicles were not formed immediately after production. In addition, the product was stable at "RT" and "5°C", but separation occurred at "50°C". In other words, the product was stable in a relatively low temperature environment, but unstable in a high temperature environment.

Comparative Example 4 was cloudy in the "Appearance (immediately after production)" category, and mixed vesicles were not formed immediately after production. It was stable at "5°C", but unstable at "RT" and "50°C".

In Comparative Example 5, a transparent gel was formed in the "Appearance (immediately after production)" category, and mixed vesicles were not formed immediately after production. Also, the product was stable at "RT" and "5°C", but unstable at "50°C".

Next, we will explain Examples 17 to 25.

In Examples 17 to 25, the concentration of pelargonic acid is 3.00% by mass or more and 6.00% by mass or less. The concentration of the monoalkyl cationic surfactant is 1.50% by mass or more and 3.00% by mass or less. The concentration of the dialkyl cationic surfactant is 1.50% by mass or more and 3.00% by mass or less. The concentration of the alcohol is 3.00% by mass or more and 5.00% by mass or less. The concentration of the preservative is 0.02% by mass. The range of the concentration ratio R of the concentration b of the cationic surfactant to the concentration a of the herbicide active ingredient is set to 1.00.

In addition, Examples 17 to 25 contain a pest control component (insecticide component). The concentration of transfluthrin or tralomethrin is 0.01% by mass or more and 0.10% by mass or less.

As shown in the "Appearance (immediately after production)" column in Table 3, mixed vesicles were formed in all of Examples 17 to 25.

Next, we will explain Comparative Examples 6 to 11.

In Comparative Examples 6 to 8, the cationic surfactant concentration was 1.00% by mass. In Comparative Examples 6 to 8, the "Appearance (immediately after production)" item showed turbidity, and mixed vesicles were not formed immediately after production. Separation also occurred at all of the temperatures of "RT," "5°C," and "50°C."

In Comparative Examples 9 to 11, the cationic surfactant concentration was 15.00% by mass. In Comparative Example 9, the "Appearance (immediately after production)" item showed turbidity, and mixed vesicles were not formed immediately after production. Separation occurred at all of "RT," "5°C," and "50°C." In Comparative Examples 10 and 11, the product was stable at "5°C," but separation occurred at "RT" and "50°C."

These results show that compositions that form mixed vesicles are stable from low to high temperatures, whereas compositions that do not form mixed vesicles are unstable in any temperature range.

(Weed control test)
Next, the herbicidal test will be described. Table 5 shows the formulation of Comparative Example 12.

Comparative Example 12 is an example containing pelargonic acid and triethanolamine.

The herbicide test method was as follows. First, wood sorrel, crabgrass, and green foxtail were prepared as test weeds. Each weed was transplanted into a pot, and the herbicides of the Examples and Comparative Examples were sprayed evenly over each weed using a hand sprayer with a discharge volume of 1 ml. The pots were then placed in an artificial weather chamber (temperature 25°C, humidity 60%), and the state of the weeds was recorded using the interval photography function of a camera. The results are shown in Table 6. The Example in Table 6 was the formulation of Example 18.

In Example 18, the time until wood sorrel, crabgrass, and green foxtail begin to wither is significantly shorter than in Comparative Example 12. The time until withering is also significantly shorter in Example 18. In particular, while Comparative Example 12 was unable to completely wither crabgrass, Example 18 was able to completely wither crabgrass. Note that the formulations of other Examples other than Example 18 can also provide similar herbicidal effects, although the time required may vary slightly.

(Effects of the embodiment)
As described above, the herbicide of this embodiment contains pelargonic acid and one or more cationic surfactants selected from monoalkyl cationic surfactants and dialkyl cationic surfactants, and since the pelargonic acid forms mixed vesicles and is present in water, it can be a herbicide with excellent long-term stability and high rapid action.

The above-described embodiments are merely illustrative in all respects and should not be interpreted as limiting. Furthermore, all modifications and variations within the scope of the claims are within the scope of the present invention.

As explained above, the herbicide of the present invention can be used against various weeds.

Claims (10)

Pelargonic acid, a herbicidal active ingredient;
one or more cationic surfactants selected from monoalkyl cationic surfactants and dialkyl cationic surfactants;
Water ,
Contains a monohydric or polyhydric alcohol ,
The concentration range of the pelargonic acid is 1.5% by mass or more and 6.0% by mass or less,
A herbicidal composition comprising mixed vesicles formed in the water by the pelargonic acid and the cationic surfactant. 2. The herbicidal composition according to claim 1 ,
A herbicidal composition, characterized in that the concentration of the cationic surfactant is in the range of 1.8 mass % or more and 18.0 mass % or less. The herbicidal composition according to claim 2 ,
A herbicidal composition, characterized in that the concentration of the cationic surfactant is in the range of 2.5 mass % or more and 16.0 mass % or less. In the herbicidal composition according to any one of claims 1 to 3 ,
A herbicidal composition characterized in that, when the concentration of the pelargonic acid is a and the concentration of the cationic surfactant is b, the concentration ratio R=b/a is 0.83 or more and 6.00 or less. The herbicidal composition according to claim 4 ,
A herbicide composition characterized in that the concentration ratio R = b/a is 1.00 or more. 2. The herbicidal composition according to claim 1 ,
A herbicidal composition, characterized in that the alcohol has 2 to 6 carbon atoms and 1 to 6 hydroxyl groups. 7. The herbicidal composition according to claim 6 ,
A herbicide composition, wherein the concentration of the alcohol is in the range of 2.0% by mass or more and 6.0% by mass or less. The herbicidal composition according to claim 7 ,
A herbicide composition, wherein the concentration of the alcohol is in the range of 2.5% by mass or more and 5.0% by mass or less. 9. The herbicidal composition according to claim 1,
A herbicide composition having a pH of 2.5 or more and 5.0 or less. 10. The herbicidal composition according to claim 1,
1. A herbicide composition which is a translucent liquid.