Efficient lambda-cyhalothrin microcapsule suspending agent, preparation method and application thereof

Abstract

This invention relates to a high-efficiency cyhalothrin microcapsule suspension, its preparation method, and its application. The high-efficiency cyhalothrin microcapsule suspension comprises the following components by mass percentage: 2.5-10% high-efficiency cyhalothrin, 5-20% modified solubilizing oily capsule shell component, 2.5-10% aqueous capsule shell component, and 60-90% water. The high-efficiency cyhalothrin microcapsule suspension provided by this invention involves first heating the high-efficiency cyhalothrin to a molten state, then using the modified solubilizing oily capsule shell component to solubilize the high-efficiency cyhalothrin to form an oily liquid, which is then mixed with water to obtain an oil-in-water emulsion. Finally, the aqueous capsule shell component is used for solidification and encapsulation to form the microcapsule suspension. This microcapsule suspension requires no solvent to dissolve the high-efficiency cyhalothrin throughout the entire process, making it green, safe, and environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of pesticide technology, and in particular to a highly efficient cyhalothrin microcapsule suspension, its preparation method, and its application. Background Technology

[0002] High-efficiency cyhalothrin, also known as lambda-cyhalothrin, chemically named 3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethylcyclopropanecarboxylic acid-α-cyano-3-phenoxybenzyl ester, is a pyrethroid insecticide characterized by high insecticidal efficiency, broad spectrum, and wide applicability. Its insecticidal mechanism involves specifically interfering with the sodium ion channel function of the insect's nervous system, blocking the normal transmission of nerve signals, ultimately leading to over-excitation, spasms, paralysis, and death in insects. It appears as a colorless and odorless crystalline solid and is typically processed into emulsifiable concentrates (EC), microemulsions (ME), and suspension concentrates (SC) for use.

[0003] When lambda-cyhalothrin is processed into formulations, it can cause itching upon contact with the human body. This is mainly because, as a fat-soluble chemical, it can irritate the skin barrier, activate nerve endings, or trigger local allergic reactions upon skin contact. Therefore, lambda-cyhalothrin is mostly processed into microcapsule suspensions to encapsulate the active ingredient and prevent it from coming into contact with human skin.

[0004] Currently, the main methods for preparing pesticide microcapsule suspensions are complex coagulation, in-situ polymerization, and interfacial polymerization. Existing technologies, such as complex coagulation and in-situ polymerization, require toxic solvents like aldehydes (formaldehyde), posing significant hazards to the environment and workers. For example, application number CN202110086801.4 provides a method for preparing a high-efficiency cyhalothrin microcapsule suspension, which uses solvents such as cyclohexanone and formaldehyde. Current interfacial polymerization methods typically use a small amount of solvent to dissolve the high-efficiency cyhalothrin technical material into an oil phase before encapsulation; for instance, applications CN202110607232.3 and CN201410215993.4 use 150# solvent oil or methylated vegetable oil.

[0005] Therefore, providing a highly efficient cyhalothrin microcapsule suspension that does not require solvent dissolution has good application prospects. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a highly efficient cyhalothrin microcapsule suspension, its preparation method, and its application.

[0007] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a high-efficiency cyhalothrin microcapsule suspension, wherein the high-efficiency cyhalothrin microcapsule suspension comprises the following components by mass percentage: 2.5-10% high-efficiency cyhalothrin (e.g., 2.5%, 4%, 6%, 8%, 10%, etc.), 5-20% modified solubilizing oily capsule shell component (e.g., 5%, 8%, 10%, 15%, 18%, 20%, etc.), 2.5-10% aqueous capsule shell component (e.g., 2.5%, 4%, 6%, 8%, 10%, etc.), and 60-90% water (e.g., 60%, 70%, 80%, 90%, etc.).

[0008] The high-efficiency cyhalothrin microcapsule suspension provided by this invention is made by first heating high-efficiency cyhalothrin to a molten state, then using a modified solubilizing oily capsule shell component to solubilize the high-efficiency cyhalothrin to form an oily liquid, then mixing it with water to obtain an oil-in-water emulsion, and finally using an aqueous capsule shell component to solidify and encapsulate it to form a microcapsule suspension.

[0009] The high-efficiency cyhalothrin microcapsule suspension provided by this invention requires no solvent to dissolve the high-efficiency cyhalothrin throughout the entire process, making it green, safe, and environmentally friendly.

[0010] Preferably, the modified solubilizing oily capsule shell component has the following structural formula: R1-R4 are each independently selected from straight-chain or branched alkyl groups of C1-C6 (e.g., C1, C2, C3, C4, C5, C6).

[0011] Preferably, R1-R4 are each independently selected from methyl, ethyl, n-propyl or n-butyl, and more preferably ethyl.

[0012] Preferably, the structural formula of the aqueous capsule component is selected from... or Any one or a combination of two of them.

[0013] R4-R6 are each independently selected from alkylene groups of C1-C10 (e.g., C1, C2, C4, C6, C8, C10, etc.), and n is selected from integers of 5-20 (e.g., 5, 8, 10, 12, 15, 18, 20, etc.).

[0014] Preferably, R4-R6 are each independently selected from C4 alkylene, C5 alkylene, C6 alkylene, C7 alkylene or C8 alkylene, and n is selected from an integer from 10 to 18.

[0015] Secondly, the present invention provides a method for preparing the high-efficiency cyhalothrin microcapsule suspension according to the first aspect, the preparation method comprising the following steps: (1) Heat the high-efficiency cyhalothrin to a molten state, and then mix and stir it with the modified solubilized oil phase capsule shell component to obtain an oily liquid; (2) Mix and stir the oily liquid from step (1) with water to obtain an oil-in-water emulsion; (3) The water-in-oil emulsion and aqueous capsule components from step (2) are mixed and stirred, and then solidified and encapsulated to obtain the high-efficiency cyhalothrin microcapsule suspension.

[0016] Preferably, the heating temperature in step (1) is 60-70℃ (e.g., 60℃, 62℃, 65℃, 68℃, 70℃, etc.).

[0017] Preferably, the stirring temperature in step (2) is 20-40℃ (e.g., 20℃, 25℃, 30℃, 35℃, 40℃, etc.), and the time is 20-60min (e.g., 20min, 30min, 40min, 50min, 60min, etc.).

[0018] Preferably, the stirring temperature in step (3) is 20-40℃ (e.g., 20℃, 25℃, 30℃, 35℃, 40℃, etc.), and the time is 40-90min (e.g., 40min, 50min, 60min, 70min, 80min, 90min, etc.).

[0019] Thirdly, the present invention provides an application of the highly efficient cyhalothrin microcapsule suspension according to the first aspect in insecticidal applications.

[0020] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The high-efficiency cyhalothrin microcapsule suspension provided by the present invention contains no solvent, is green and safe, and is environmentally friendly.

[0021] (2) The preparation method of the high-efficiency cyhalothrin microcapsule suspension provided by the present invention requires relatively simple production equipment and processes. It does not require the use of high-speed homogenizers or other equipment to shear the high-efficiency cyhalothrin technical material into an oil-in-water emulsion at high speed, resulting in low production costs. In the preferred embodiment, heating is required only when solubilizing the cyhalothrin technical material, while no heating is required throughout the encapsulation and solidification process; at the same time, encapsulation can be completed in just 1 hour, resulting in very low energy consumption for production. Attached Figure Description

[0022] Figure 1 This is an overall morphology diagram of the high-efficiency cyhalothrin microcapsule suspension prepared in Example 3.

[0023] Figure 2 This is an electron microscope image of the encapsulation of the high-efficiency cyhalothrin microcapsule suspension prepared in Example 3. Detailed Implementation

[0024] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0025] The reagents used in the following examples are described below: LR-1420, N,N'-(methylenedi-4,1-cyclohexanediyl)diaspartic acid tetraethyl ester, structural formula is The CAS number is 136210-30-5, and it was purchased from Shenzhen Ruqinba Chemical Materials Co., Ltd. RQB-1220, a polyether-modified hexamethylene diisocyanate trimer, has the following structural formula: Purchased from Shenzhen Ruqinba Chemical Materials Co., Ltd. RQB-1221, an anionic modified hexamethylene diisocyanate trimer, has the following structural formula: R4-R6 are all C6 alkylene groups, n=15, purchased from Shenzhen Ruqinba Chemical Materials Co., Ltd.

[0026] Example 1 A high-efficiency cyhalothrin microcapsule suspension with a content of 2.5% comprises the following components: The preparation method of the high-efficiency cyhalothrin microcapsule suspension includes the following steps: (1) Heat the high-efficiency cyhalothrin to 65°C until it melts, add LR-1420, and stir until it becomes a clear, transparent oily liquid; (2) Add all the water to the oily liquid in step (1) and stir at room temperature (25℃) for 30 minutes to obtain an oil-in-water emulsion; (3) Add RQB-1220 to the oil-in-water emulsion in step (2), stir at room temperature (25°C) for 1 hour, and then solidify and encapsulate to obtain the high-efficiency cyhalothrin microcapsule suspension.

[0027] Example 2 A high-efficiency cyhalothrin microcapsule suspension with a content of 5% comprises the following components: The preparation method of the high-efficiency cyhalothrin microcapsule suspension is as described in Example 1.

[0028] Example 3 A highly efficient cyhalothrin microcapsule suspension with a content of 10% comprises the following components: The preparation method of the high-efficiency cyhalothrin microcapsule suspension is as described in Example 1.

[0029] The overall morphology of the high-efficiency cyhalothrin microcapsule suspension prepared in Example 3 is as follows: Figure 1 As shown, the images of cysts observed under an electron microscope are as follows: Figure 2 As shown.

[0030] Comparative Example 1 A high-efficiency cyhalothrin microcapsule suspension (complex coagulation method) with a content of 2.5% comprises the following components: The high-efficiency cyhalothrin microcapsule suspension was prepared by a complex coagulation method, specifically including the following steps: (1) Add high-efficiency cyhalothrin, 150# solvent oil and castor oil polyoxyethylene ether to the reaction vessel and stir until dissolved and transparent as the oil phase; (2) Prepare aqueous solutions of gelatin and gum arabic separately, and mix them at 50°C as the aqueous phase; (3) At a constant temperature of 50℃, slowly add the oil phase to the aqueous phase while stirring. Add 10% acetic acid aqueous solution dropwise to the mixture and adjust the pH to 4.0. (4) After naturally cooling to 25°C, add 37% formaldehyde solution, stir for 20 min, then adjust the pH to 6 with 20% NaOH solution, continue stirring for 40 min, observe until precipitation, and let stand to allow the microcapsules to settle; (5) After sedimentation, the supernatant is discarded, the obtained microcapsules are dispersed in water, and xanthan gum, sodium benzoate and sodium lignosulfonate are added and stirred thoroughly to obtain a high-efficiency cyhalothrin microcapsule suspension.

[0031] Comparative Example 2 A 5% high-efficiency cyhalothrin microcapsule suspension (in-situ polymerization method) comprises the following components: The high-efficiency cyhalothrin microcapsule suspension was prepared by in-situ polymerization, specifically including the following steps: (1) Add high-efficiency cyhalothrin, 150# solvent oil and castor oil polyoxyethylene ether to the reaction vessel and stir until dissolved and transparent as the oil phase; (2) Prepare an aqueous solution of the colloidal protective agent, polyethylene maleic anhydride, as the aqueous phase; (3) Slowly add the oil phase to the aqueous phase and perform high-speed shearing at a speed of 10000r / min for 10min, controlling the particle size D90 to be 5-8μm; (4) Add melamine-formaldehyde prepolymer, heat to 80°C, and stir at a low speed of 500r / min for 2 hours to encapsulate and solidify; (5) Finally, adjust the pH to 6 with 20% NaOH solution, then add xanthan gum, sodium benzoate and sodium lignosulfonate and stir evenly to obtain high-efficiency cyhalothrin microcapsule suspension.

[0032] Comparative Example 3 A 10% high-efficiency cyhalothrin microcapsule suspension (interfacial polymerization method) comprises the following components: The high-efficiency cyhalothrin microcapsule suspension was prepared by interfacial polymerization, specifically including the following steps: (1) Add high-efficiency cyhalothrin, 150# solvent oil and toluene diisocyanate to the reaction vessel and stir until dissolved and transparent as the oil phase; (2) Add all the water, castor oil polyoxyethylene ether, xanthan gum and sodium benzoate to another reactor and stir until homogeneous as the aqueous phase; (3) Slowly add the oil phase to the aqueous phase and perform high-speed shearing at a speed of 10000r / min for 10min, controlling the particle size D90 to be 5-8μm; (4) Add polyethylene glycol, keep stirring at a low speed of 500 r / min, and slowly heat to 60℃ to cure for 4 hours; (5) Finally, add 5% sodium lignosulfonate and continue stirring for 1 hour to obtain high-efficiency cyhalothrin microcapsule suspension.

[0033] Test Example 1 Performance index testing The high-efficiency cyhalothrin microcapsule suspensions prepared in the embodiments and comparative examples of the present invention were tested for the following performance indicators, and the results are summarized in Table 1.

[0034] (1) D90 particle size: detected using a laser particle size analyzer; (2) Suspension rate: Tested according to the method of national standard GB / T 14825-2023; (3) Coating rate: Coating rate (%) = (Total content of raw material - Free content) / Total content of raw material × 100%; (4) Sustained-release rate: Detected according to the industry standard NY / T 4001-2021 method; (5) Stability of cold and hot storage: Tested according to the method of GB / T 19136-2021.

[0035] Table 1. Results of main technical indicators of microcapsule suspensions As shown in Table 1, the high-efficiency cyhalothrin microcapsule suspension D90 provided by this invention has a small particle size, high suspension rate, high encapsulation rate, and high sustained-release rate, and meets the requirements for cold and hot storage stability. In preferred embodiments 1-3, the D90 particle size is 5.221-5.676 μm, the suspension rate is 99.24-99.63%, the encapsulation rate is 98.2-98.7%, and the sustained-release rate is 97.6-98.1%.

[0036] A comparison of Examples 1-3 with Comparative Examples 1-3 shows that the encapsulation rate and sustained release rate of Examples 1, 2 and 3 are higher than those of Comparative Examples 1, 2 and 3, indicating that the solvent-free high-efficiency cyhalothrin microcapsule suspension of the present invention has advantages in encapsulation and sustained release.

[0037] Test Example 2 Field efficacy verification The high-efficiency cyhalothrin microcapsule suspension prepared in the embodiments and comparative examples of the present invention was tested in the field. The test was designed and implemented in accordance with GB / T 17980.13-2023 Field Efficacy Test Guidelines for Pesticides Part 13: Insecticides for the Control of Diamondback Moth in Cruciferous Vegetables.

[0038] Experimental crop: Cruciferous vegetable, cabbage, plant height 25-30cm, vigorous growth, no history of disease or pest occurrence, and uniform growth in the field.

[0039] Target pest: Diamondback moth (Plutella xylostella), naturally occurring population, mainly consisting of 1st-3rd instar larvae. Pre-application survey showed a uniform pest population, with an average of 2.1 pests per plant, which met the experimental requirements.

[0040] Experimental design and arrangement: A total of 6 treatments were set up, with 4 replicates for each treatment, and one blank control was included; the experiment was conducted in a randomized block design, with each plot having an area of ​​20m². 2 (4m×5m), approximately 30 cabbage plants were planted in each plot, which was rectangular in shape with a 1m spacing between repeating plots to ensure consistent environmental conditions. Backpack-mounted electric sprayers (fan nozzles) were used, with a water consumption of 50L / acre, to spray the entire plant evenly.

[0041] The results of the field efficacy test are shown in Table 2.

[0042] Table 2. Field efficacy results of pesticides in controlling diamondback moth. As shown in Table 2, the high-efficiency cyhalothrin microcapsule suspension provided by this invention has excellent field efficacy in controlling diamondback moth. In preferred embodiments 1-3, the control efficacy reached 85.2-88.7% 21 days after application.

[0043] A comparison of Examples 1-3 with Comparative Examples 1-3 shows that the control efficacy of Examples 1, 2, and 3 of the present invention reached 90% at 14 days after application, and the difference in efficacy was not significant. However, at 21 days after application, the control efficacy of the examples of the present invention was much higher than that of the comparative examples, indicating that the solvent-free, high-efficiency cyhalothrin microcapsule suspension of the present invention has a greater advantage in terms of encapsulation and sustained release, thus giving it a superior sustained efficacy.

[0044] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A highly efficient cyhalothrin microcapsule suspension, characterized in that, The high-efficiency cyhalothrin microcapsule suspension comprises the following components by mass percentage: 2.5-10% high-efficiency cyhalothrin, 5-20% modified solubilized oily capsule shell component, 2.5-10% aqueous capsule shell component, and 60-90% water.

2. The high-efficiency cyhalothrin microcapsule suspension according to claim 1, characterized in that, The structural formula of the modified, solubilized, oily capsule shell component is as follows: R1-R4 are each independently selected from straight-chain or branched alkyl groups of C1-C6.

3. The high-efficiency cyhalothrin microcapsule suspension according to claim 2, characterized in that, R1-R4 are each independently selected from methyl, ethyl, n-propyl or n-butyl, preferably ethyl.

4. The high-efficiency cyhalothrin microcapsule suspension according to any one of claims 1-3, characterized in that, The structural formula of the aqueous capsule component is selected from... or Any one or a combination of two of them; R4-R6 are each independently selected from C1-C10 alkylene groups, and n is selected from integers from 5 to 20.

5. The high-efficiency cyhalothrin microcapsule suspension according to claim 4, characterized in that, R4-R6 are each independently selected from C4 alkylene, C5 alkylene, C6 alkylene, C7 alkylene or C8 alkylene, and n is selected from an integer from 10 to 18.

6. A method for preparing a high-efficiency cyhalothrin microcapsule suspension according to any one of claims 1-5, characterized in that, The preparation method includes the following steps: (1) Heat the high-efficiency cyhalothrin to a molten state, and then mix and stir it with the modified solubilized oil phase capsule shell component to obtain an oily liquid; (2) Mix and stir the oily liquid from step (1) with water to obtain an oil-in-water emulsion; (3) The water-in-oil emulsion and aqueous capsule components from step (2) are mixed and stirred, and then solidified and encapsulated to obtain the high-efficiency cyhalothrin microcapsule suspension.

7. The preparation method according to claim 6, characterized in that, The heating temperature in step (1) is 60-70℃.

8. The preparation method according to claim 6 or 7, characterized in that, The stirring temperature in step (2) is 20-40℃ and the stirring time is 20-60min.

9. The preparation method according to any one of claims 6-8, characterized in that, The stirring temperature in step (3) is 20-40℃ and the stirring time is 40-90min.

10. The application of the high-efficiency cyhalothrin microcapsule suspension according to any one of claims 1-5 in insecticidal applications.

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