Pesticide component-encapsulated gel and method for manufacturing pesticide component-encapsulated gel

Abstract

To provide a pesticide component-encapsulated gel that can be immobilized on a plant and can release a pesticide component at a desired timing, and a method for manufacturing the pesticide component-encapsulated gel.SOLUTION: A pesticide component-encapsulated gel contains a photoisomerizable compound having a photoisomerizable group and two or more electron-withdrawing groups, a halogenated alkyl quaternary ammonium, a pesticide component, and water. The pesticide component-encapsulated gel is in a gel form in which the photoisomerizable compound and the halogenated alkyl quaternary ammonium are bound by electrostatic interaction, and water and the pesticide component are encapsulated, and is solated by light irradiation to release the pesticide component.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gel containing an agrochemical ingredient and a method for producing the gel containing an agrochemical ingredient. [Background technology]

[0002] In agriculture, spraying pesticides is widely used to protect crop growth and increase yields. However, the problem with spraying pesticides is that they are easily dispersed by wind and rain. Excessive spraying of pesticides can also cause environmental pollution. Furthermore, it can encourage the increase of resistant pests, which reduces the effectiveness of conventional pesticides.

[0003] Spreaders are sometimes used to improve the adhesion and penetration of pesticides onto crops and stabilize their effectiveness. When using a spreader, the pesticide must be sprayed on the crops after the wetting agent has been applied, which requires time and effort.

[0004] There is also a demand for the effects of pesticides to act in a timely manner. As a method for controlling the release of pesticides, a method using a porous membrane material having photoisomerizable groups in the pores has been proposed (Patent Document 1). Patent Document 1 utilizes the fact that the action of the photoisomerizable groups in the porous membrane material causes the liquid to become vapor and pass through the pores, and it is envisioned that the pesticide, which is a liquid component, can be released to the other side of the porous membrane material by irradiating it with light. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-186794 Summary of the Invention [Problem to be solved by the invention]

[0006] Patent Document 1 does not disclose a specific method for immobilizing the pesticide and the porous membrane material on the crop.

[0007] The present invention has been made in consideration of the above matters, and its object is to provide a gel containing an agrochemical component that can be fixed to a plant and that can release the agrochemical component at a desired timing, and a method for producing the gel containing an agrochemical component. [Means for solving the problem]

[0008] The pesticide component-encapsulating gel according to the first aspect of the present invention comprises: a photoisomerizable compound having a photoisomerizable group and two or more electron-withdrawing groups; an alkyl quaternary ammonium halide; Pesticide ingredients and water, the photoisomerizable compound and the alkyl quaternary ammonium halide are bonded to each other through electrostatic interaction, and the gel-like substance encapsulates the water and the pesticide component, and the gel-like substance is converted into a sol by light irradiation to release the pesticide component; It is characterized by:

[0009] The photoisomerizable compound is preferably an azobenzene derivative.

[0010] The azobenzene derivative is preferably azobenzenedicarboxylic acid, azobenzenetetracarboxylic acid, azobenzenedisulfonic acid, or azobenzenetetrasulfonic acid.

[0011] The alkyl quaternary ammonium halide is preferably represented by formula 1. [CH3(CH2) n N(CH3)3]X …(Formula 1) (In formula 1, n represents an integer of 6 to 20, and X represents a halogen.)

[0012] Furthermore, the molar number of the electron-withdrawing group in the photoisomerizable compound / the molar number of the alkyl halide quaternary ammonium is preferably 0.5 to 1.5.

[0013] In addition, the total content of the photoisomerizable compound and the alkyl quaternary ammonium halide in the pesticide component-encapsulating gel is preferably 1% by weight or more.

[0014] A method for producing a pesticide component-encapsulating gel according to a second aspect of the present invention comprises: a photoisomerizable compound having a photoisomerizable group and an electron-withdrawing group, an alkyl quaternary ammonium halide, an agricultural chemical ingredient, and water are mixed and heated, and then cooled to form a gel; It is characterized by: [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a gel containing an agrochemical component that can be fixed to a plant and that can release the agrochemical component at a desired timing, and a method for producing the gel containing an agrochemical component. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a conceptual diagram illustrating the formation of a gel by binding of ADA and CTAB. [Figure 2] 1 is a graph showing the results of UV-Vis measurement of TMX-encapsulating gel. [Figure 3] 1 is a graph showing the results of rheology measurement of TMX gel-free. [Figure 4] 1 is a graph showing the contact angle of a TMX-encapsulating gel dropped onto a plant before and after light irradiation. [Figure 5] 1 is a graph showing cell death in Arabidopsis thaliana. [Figure 6] Figure 6(A) is a graph showing the insect mortality rate without UV irradiation (conditions (a), (c), and (d)), and Figure 6(B) is a graph showing the insect mortality rate with UV irradiation (conditions (b) and (e)). DETAILED DESCRIPTION OF THE INVENTION

[0017] <Gel containing pesticide ingredients> The pesticide component-encapsulating gel contains a photoisomerizable compound, an alkyl halide quaternary ammonium, a pesticide component, and water.

[0018] The photoisomerizable compound has a photoisomerizable group and an electron-withdrawing group. Because the photoisomerizable compound has the photoisomerizable group, the three-dimensional structure of the photoisomerizable compound changes when irradiated with light.

[0019] The photoisomerizable compound has two or more electron-withdrawing groups, which bond to the alkyl quaternary ammonium halide through electrostatic interaction. The electron-withdrawing groups may be any functional group that releases a proton in an aqueous solution, such as a carboxyl group or a sulfonic acid group.

[0020] Examples of photoisomerizable compounds include azobenzene derivatives. Specific examples of azobenzene derivatives include azobenzene-2,2'-dicarboxylic acid, azobenzene-3,3'-dicarboxylic acid, azobenzene-4,4'-dicarboxylic acid, azobenzene-3,3',5,5'-tetracarboxylic acid, azobenzene-2,2',4,4',6,6'-hexacarboxylic acid, azobenzene-2,2'-disulfonic acid, azobenzene-3,3'-disulfonic acid, 4,4'-azobenzenedisulfonic acid, azobenzene-3,3',5,5'-tetrasulfonic acid, and azobenzene-2,2',4,4',6,6'-hexasulfonic acid.

[0021] The alkyl quaternary ammonium halide is bonded to an electron-withdrawing group of the photoisomerizable compound. Specifically, the alkyl quaternary ammonium halide is represented by formula 1. In formula 1, n is an integer of 6 to 20, and X represents a halogen atom such as chlorine or bromine. [CH3(CH2) n N(CH3)3]X …(Formula 1)

[0022] Specific examples of the alkyl quaternary ammonium halide represented by Formula 1 include, for example, butyltrimethylammonium bromide, hexyltrimethylammonium bromide, octyltrimethylammonium bromide, decyltrimethylammonium bromide, dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, heptadecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, butyltrimethylammonium chloride, hexyltrimethylammonium chloride, octyltrimethylammonium chloride, decyltrimethylammonium chloride, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, heptadecyltrimethylammonium chloride, and octadecyltrimethylammonium chloride.

[0023] The pesticide component has an insecticidal effect. There are no limitations on the pesticide component contained, and it may be appropriately selected depending on the target insect to be killed, etc. Examples of pesticide components include organophosphates such as acephate, dimethoate, diazinon, malathion, methidathion, fenitrothion, and fenon; carbamate components such as alanycarb, oxamyl, carbosulfan, thiodicarb, benfuracarb, methomyl, N-methylcarbamate-2-(1-methylpropyl)phenyl, and carbaryl; and pyrethroids such as etofenprox, cyhalothrin, cyfluthrin, cypermethrin, silafluofen, bifenthrin, pyrethrins, fenvalerate, fenpropathrin, flucythrinate, and fluvathrin. These include linate, permethrin, nereistoxin-based cartap, thiocyclam, bensultap, neonicotinoid-based acetamiprid, imidacloprid, clothianidin, dinotefuran, thiacloprid, thiamethoxam, nitenpyram, sulfoximine-based sulfoxaflor, butenolide-based flupyradifurone, mesoionic-based triflumezopyrim, macrolide-based abamectin, emamectin benzoate, lepimectin, milbemectin, spinetoram, spinosad, phenylpyrazole-based fipronil, ethiprole, etc.

[0024] The compounding ratio of the photoisomerizable compound to the alkyl quaternary ammonium halide is preferably such that [the number of moles of electron-withdrawing groups in the photoisomerizable compound] / [the number of moles of alkyl quaternary ammonium halide] is 0.5 to 1.5, and more preferably an equal amount of 1. If the ratio is outside this range, it is difficult for the pesticide ingredient-encapsulating gel to gel sufficiently.

[0025] Furthermore, the total content of the photoisomerizable compound and alkyl halide quaternary ammonium in the pesticide ingredient-encapsulating gel is preferably 1% by weight or more, and more preferably 1 to 4% by weight. If the total content of the photoisomerizable compound and alkyl halide quaternary ammonium is low, it is difficult to achieve sufficient gelation.

[0026] The content of the pesticide component in the pesticide component-encapsulating gel may be appropriately set within a range that does not inhibit the gelation of the pesticide component-encapsulating gel.

[0027] The formation of a gel containing pesticide ingredients by combining a photoisomerizable compound with alkyl quaternary ammonium halide is explained using azobenzene-4,4'-dicarboxylic acid (ADA) and hexadecyltrimethylammonium bromide (CTAB) as an example.

[0028] ADA has two carboxyl groups, which are electron-withdrawing groups, per molecule. By placing ADA under alkaline conditions, specifically by placing it in an alkaline aqueous solution, the -COOH groups are deprotonated, and -COO - The electrostatic interaction between the positively charged portion of CTAB (quaternary ammonium) and the negatively charged portion of ADA (carboxyl group) promotes the binding of CTAB and ADA, as shown in Figure 1. Furthermore, the hydrophobic interaction between the alkyl chains in the hydrophobic portion of CTAB and the π-π interaction between the aromatic groups of ADA cause the formation of a gel that encapsulates water and the pesticide ingredients.

[0029] The pesticide-encapsulating gel is in gel form at room temperature, but transitions to a sol form when exposed to UV light. UV irradiation changes the structure of the photoisomerizable compound from trans to cis isomers, weakening the hydrophobic and π-π interactions described above, which is thought to be why the gel transitions to a sol form and releases the encapsulated pesticide ingredients.

[0030] <Method of manufacturing the gel containing pesticide ingredients> The pesticide component-encapsulating gel can be produced as follows. A mixed solution is prepared by mixing a photoisomerizable compound, alkyl quaternary ammonium halide, pesticide component, and water, and the mixture is heated to allow for a sufficient reaction. After the reaction, the gel can be obtained by cooling to room temperature. To facilitate deprotonation of the electron-withdrawing group of the photoisomerizable compound, the water used should be an alkaline aqueous solution, for example, water adjusted to a pH of approximately 8 to 12 by adding a pH adjuster such as sodium hydroxide. The heating temperature should be such that each component dissolves in water, for example, approximately 50 to 70°C. The mixing ratio of each component may be as described above. Alternatively, a mixed solution may be prepared by dissolving the photoisomerizable compound, alkyl quaternary ammonium halide, and pesticide component in water, respectively, and then forming the mixed solution.

[0031] <How to use the gel containing pesticide ingredients> The pesticide component-encapsulating gel is used by adhering it to the leaves of crops, etc. Adhesion to crops can be performed by any desired method, for example, using a spraying device, etc. If it is difficult to spray the pesticide component-encapsulating gel as is, it can be heated to about 50 to 70°C to form a sol, and then sprayed in the sol state. Thereafter, it becomes gel-like by natural cooling. And, since the pesticide component-encapsulating gel attached to the crop is in gel form, it has excellent fixing power to the crop.

[0032] Then, when the effect of the pesticide on the crops is desired, the attached pesticide component-encapsulating gel is irradiated with light to release the pesticide from the pesticide component-encapsulating gel. The light to be irradiated depends on the physical properties of the photoisomerizable compound contained in the pesticide component-encapsulating gel, but is, for example, ultraviolet light with a wavelength of 300 to 400 nm. [Example]

[0033] <Preparation of Gel Containing Pesticide Ingredient> Hexadecyltrimethylammonium bromide (hereinafter referred to as CTAB) and azobenzene-4,4'-dicarboxylic acid (hereinafter referred to as ADA) were dissolved in water and stirred well at 60 °C to prepare a CTAB / ADA mixed solution. The pH of water was adjusted to 12 by adding NaOH and then used. Thiamethoxam (hereinafter referred to as TMX) was dissolved in water to prepare a TMX solution (18 mg / mL). 50 μL of the TMX solution was added to 500 μL of the CTAB / ADA mixed solution, stirred well at 60 °C, and then cooled at room temperature for 5 minutes to prepare a TMX-encapsulated gel. The ratio of CTAB, ADA, and TMX was 2:1:0.28 in molar ratio. In addition, gels encapsulating various TMX and water (hereinafter referred to as TMX-encapsulated gels) were prepared in the range of 0.1 - 4 wt% of the total content of CTAB and ADA with respect to the total content of CTAB, ADA, and water. Hereinafter, each prepared TMX-encapsulated gel is denoted as an Xwt% TMX-encapsulated gel, and "X" represents the total content (wt%) of CTAB and ADA.

[0034] In addition, a gel not encapsulating TMX (hereinafter referred to as a TMX-free gel) was prepared in the same manner except for not adding TMX. This is denoted as an Xwt% TMX-free gel, and "X" has the same meaning as above.

[0035] <UV-Vis (Ultraviolet Visible Absorption Spectroscopy) Measurement> For the prepared 0.1 wt% TMX-encapsulated gel, UV-Vis measurement was performed using an ultraviolet-visible spectrophotometer (V-550, JASCO Corporation). The cis-trans isomerization peak of the 0.1 wt% TMX-encapsulated gel was measured in the range of 200–700 nm. The hydrogel was irradiated with 365 nm light using a handy UV lamp (As One Corporation). Absorbance measurements of the trans-ADA peak (330 nm) and cis-ADA peak (260 nm) were performed at 5-minute intervals up to 60 minutes.

[0036] The results are shown in Figure 2. As the UV irradiation time increased, the trans-ADA peak at 330 nm decreased significantly within 15 minutes, while the cis-ADA peak at 260 nm increased. Finally, the cis-trans isomerization reached equilibrium within 60 minutes.

[0037] <Rheology measurement> The storage modulus (G') and loss modulus (G") of gel-free TMX were measured using a dynamic shear rheometer (MCR102: Anton Paar GmbH, Graz, Austria) equipped with a stainless steel cone and plate, in dynamic oscillation mode, at 6.283 rad / s (1 Hz) with an oscillation amplitude of 1% from 20 to 60 °C. Furthermore, the storage modulus and loss modulus were measured in the same manner after irradiating TMX gel-free with ultraviolet light (wavelength: 365 nm).

[0038] The results are shown in Figure 3. Before UV irradiation, the storage modulus and loss modulus of the TMX-free gel increased as the total content of CTAB and ADA increased. Since there was no significant change when the total content of CTAB and ADA was 1 wt% or higher, it can be said that a gel that maintains mechanical strength can be obtained by increasing the total content of CTAB and ADA to 1 wt% or higher.

[0039] Furthermore, after UV irradiation, the storage modulus and loss modulus decreased significantly, and this was particularly noticeable when the total content of CTAB and ADA was 1 wt% or more. It is thought that UV irradiation caused the TMX gel to maintain its fluidity, i.e., to transition to a sol, resulting in a decrease in mechanical strength.

[0040] <Contact angle measurement> 1 wt% TMX gel (3 μL) was heated to 60°C to form a sol and then dropped onto each of the samples (cabbage, Chinese cabbage, lettuce, and a metal plate). After the TMX-encapsulated gel gelled as the temperature decreased, the contact angle of the TMX-encapsulated gel was measured using a contact angle meter (DMs-401 (Kyowa Interface Science CO., Ltd.)). Furthermore, the TMX-encapsulated gel was irradiated with ultraviolet light (365 nm wavelength) for 1 hour, and the contact angle of the TMX-encapsulated gel was measured in the same manner.

[0041] The results are shown in Figure 4. The contact angle of the TMX-encapsulated gel varies depending on the hydrophilicity of the surface of the object onto which it is dropped, but in all cases, the contact angle decreased significantly after UV irradiation. It is thought that UV irradiation causes a gel-sol transition due to trans-cis isomerization of ADA, resulting in a decrease in mechanical strength.

[0042] The results of the above UV-vis, rheology, and contact angle measurements confirmed that the gel encapsulating the pesticide ingredient transitioned from a gel to a sol upon exposure to ultraviolet light.

[0043] <Cytotoxicity test> Arabidopsis cotyledons were placed on TMX gel after 3 weeks of germination. After 24 hours, they were immersed in a staining solution (Evans blue) for 30 minutes, washed twice with water, and then immersed in methanol. The absorbance (623 nm) of the solution was measured using UV-vis to calculate cell viability.

[0044] The results are shown in Figure 5. The cell viability of Arabidopsis thaliana was 98% or higher in all cases. Therefore, it can be said that the gel itself, which does not encapsulate TMX, has extremely low toxicity to plants.

[0045] <Insecticidal activity test> Randomly selected insects (Helicoverpa armigera larvae (n=10)) were distributed to each plastic case and reared under the following conditions (a) to (e). Condition (a): Raised in a plastic container with filter paper and water. Condition (b): Water was added to a plastic case with filter paper placed on it, and the fish were reared under ultraviolet light. Condition (c): The mice were reared in a plastic container with filter paper and water containing TMX. Condition (d): TMX-encapsulated gel was added to a plastic case containing filter paper. Condition (e): TMX-encapsulated gel was placed in a plastic case with filter paper placed on it, and the cells were reared under UV light.

[0046] The amount of water added under conditions (a) and (b) was 3 mL. Under condition (c), 3 mL of TMX-containing water was added, with a TMX concentration of 0.9 mg / mL. Under conditions (d) and (e), 3 mL of TMX-encapsulated gel was added, with a TMX concentration of 0.9 mg / mL. Under conditions (b) and (e), UV irradiation was performed using a handheld UV lamp with a wavelength of 365 nm, starting 2 hours after incubation.

[0047] The number of dead insects in each plastic container was recorded every hour. The criterion for determining the state of death was when the insect's body was touched and it was determined to be dead if it was not breathing or moving.

[0048] Figure 6(A) shows the change in insect mortality over time without UV irradiation (conditions (a), (c), and (d)). Figure 6(B) shows the change in insect mortality over time with UV irradiation (conditions (b) and (e)).

[0049] The results of conditions (a) and (b) show that water and ultraviolet light have no effect on the survival of insects. Under condition (c), when TMX-containing water is used, the mortality rate of insects reached 100% within 3 hours.

[0050] When the TMX-encapsulated gel was present under condition (d), the release of TMX from the TMX-encapsulated gel was suppressed, resulting in a decrease in the mortality rate of the insects, which was 10%.

[0051] When UV light was applied with the TMX-encapsulated gel in place (condition (e)), the mortality rate of insects was 0% before UV light irradiation. However, once UV light irradiation began, the mortality rate began to increase, reaching 100% 8 hours after the start of measurement.

[0052] In this way, when a TMX-encapsulated gel is used, the release of TMX is suppressed until UV light is irradiated, and TMX is released upon UV light irradiation. In other words, after the pesticide-encapsulated gel is sprayed on crops and immobilized, UV light can be irradiated at the desired time to release the pesticide ingredients, thereby exerting its pesticidal effect on the crops. [Industrial Applicability]

[0053] The gel containing the pesticide ingredient can be used in the agricultural field to protect the growth of crops and increase the yield.

Claims

1. a photoisomerizable compound having a photoisomerizable group and two or more electron-withdrawing groups; an alkyl quaternary ammonium halide; Pesticide ingredients and water, the photoisomerizable compound and the alkyl halide quaternary ammonium are bonded to each other through electrostatic interaction, and the gel-like substance encapsulates the water and the pesticide component, and the gel-like substance is converted into a sol by light irradiation to release the pesticide component; A gel containing a pesticide ingredient.

2. the photoisomerizable compound is an azobenzene derivative; 2. The pesticide ingredient-encapsulating gel according to claim 1.

3. the azobenzene derivative is azobenzenedicarboxylic acid, azobenzenetetracarboxylic acid, azobenzenedisulfonic acid, or azobenzenetetrasulfonic acid; 3. The pesticide ingredient-encapsulating gel according to claim 2.

4. The alkyl halide quaternary ammonium is represented by Formula 1: [CH ３ (CH ２ ) ｎ N(CH ３ ) ３ X … (Formula 1) (In formula 1, n is an integer of 6 to 20, and X represents a halogen.) 2. The pesticide ingredient-encapsulating gel according to claim 1.

5. the molar number of the electron-withdrawing group in the photoisomerizable compound / the molar number of the alkyl halide quaternary ammonium is 0.5 to 1.5; 2. The pesticide ingredient-encapsulating gel according to claim 1.

6. the total content of the photoisomerizable compound and the alkyl halide quaternary ammonium in the pesticide ingredient-encapsulating gel is 1% by weight or more; 2. The pesticide ingredient-encapsulating gel according to claim 1.

7. a photoisomerizable compound having a photoisomerizable group and an electron-withdrawing group, an alkyl halide quaternary ammonium, an agricultural chemical ingredient, and water are mixed and heated, and then cooled to form a gel; A method for producing a gel containing an agricultural chemical ingredient, comprising:

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