A microcapsule suspension of deltamethrin containing a release accelerator, its preparation method and application

Abstract

The application provides a microcapsule suspension of deltamethrin containing a release accelerator, a preparation method and application thereof. The microcapsule suspension takes polyurea as a capsule wall material, deltamethrin is wrapped in the microcapsule through an interfacial polymerization method, and trans-anethole is added as a release accelerator. The trans-anethole is a natural terpene compound, which can increase the porosity of the capsule wall to a certain extent, thereby significantly improving the release rate of deltamethrin from the microcapsule. The preparation has excellent cold storage stability and hot storage stability, low decomposition rate of the effective component, and no delamination and caking phenomenon in appearance. Field tests show that the preparation has excellent quick-acting property and persistence on peach small fruit borers, and the initial control effect is significantly better than that of traditional preparations. The application is suitable for pest control of crops such as fruit trees and vegetables.

Description

Technical Field

[0001] This invention relates to the field of pesticide formulation technology, specifically to a deltamethrin microcapsule suspension containing a release promoter, its preparation method, and its application. Background Technology

[0002] Deltamethrin, CAS Registry No. 52918-63-5, chemically named (S)-α-cyano-3-phenoxybenzyl(1R,3R)-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylic acid ester, is a representative product of the second-generation pyrethroid insecticide class. Deltamethrin is a neurotoxin that prolongs the opening time of sodium ion channels on the nerve cell membranes of pests, leading to over-excitation, paralysis, and death. This ingredient is characterized by high efficiency, broad spectrum, and strong contact and stomach poison effects, exhibiting excellent control efficacy against various agricultural pests such as Lepidoptera (e.g., cabbage caterpillars, diamondback moths, cotton bollworms, peach fruit moths), Coleoptera, and Hemiptera, as well as sanitary pests such as mosquitoes, flies, and cockroaches.

[0003] However, deltamethrin has the following inherent defects: (1) high lipophilicity (octanol / water partition coefficient lgKow=5.43) and low water solubility, which makes its dispersibility and stability in traditional water-based formulations poor; (2) insufficient photostability, which makes it prone to photolysis under ultraviolet irradiation and has a short duration of effect; (3) traditional emulsifiable concentrate formulations use a large amount of organic solvents (such as toluene and xylene), which pose safety and environmental problems; (4) high toxicity to non-target organisms such as fish, bees, and silkworms, which poses a high risk of use.

[0004] Trans-anethole, CAS Registry No. 4180-23-8, chemically known as trans-1-methoxy-4-(1-propenyl)benzene, is a naturally occurring aromatic compound widely found in the essential oils of plants such as star anise and fennel seeds. At room temperature, trans-anethole is a colorless to pale yellow liquid with a distinctive anise aroma and can be used as an edible flavoring and pharmaceutical excipient. Studies have shown that trans-anethole has good lipid solubility and permeability, low skin irritation, and good safety.

[0005] Microencapsulated suspensions (CS) are pesticide formulations in which the active ingredients of solid or liquid pesticides are encapsulated in a polymeric capsule wall and dispersed in an aqueous phase. Compared with traditional emulsifiable concentrates (EC) and suspension concentrates (SC), microencapsulated suspensions have the following significant advantages: (1) They improve the persistence of the pesticide through the controlled release effect of the capsule wall, reducing the number of applications; (2) They reduce the photolysis and oxidative degradation rate of the active ingredients, improving stability; (3) They reduce the direct contact between the active ingredients and human skin, reducing the risk of toxicity; (4) They use water as the dispersion medium, replacing organic solvents, making them environmentally friendly; and (5) They can achieve timed and quantitative release of the drug by controlling the composition and structure of the capsule wall material. Polyurea-type capsule walls are generated by the interfacial polymerization reaction of polyisocyanates and polyamines. They have advantages such as high mechanical strength, good chemical stability, and wide compatibility with various active ingredients, and are one of the mainstream technical routes for pesticide microencapsulation formulations.

[0006] Chinese patent application CN110731349A discloses a microcapsule suspension containing tetrazolium acetamiprid and deltamethrin. However, this application focuses on the synergistic effect of the two active ingredients combined. For the microcapsule suspension, it only provides a simple formulation composition, but does not provide relevant quality indicators of the formulation or field application effect data. It is unclear whether the formulation can be actually prepared, nor is it clear about the rapid effect and duration of the formulation. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a deltamethrin microcapsule suspension containing a release promoter, its preparation method, and its application, thereby solving the technical issues of insufficient rapid-acting and poor sustained-action effects of existing deltamethrin formulations. This invention is the first to introduce the release promoter trans-anisole into the deltamethrin microcapsule suspension system. Utilizing the plasticizing and pore-forming effects of trans-anisole on the polyurea capsule wall, rapid release of deltamethrin is achieved while maintaining the sustained-action advantage of microcapsule formulations.

[0008] The present invention is implemented through the following technical solutions.

[0009] This invention provides a deltamethrin microcapsule suspension containing a release promoter, comprising the following components by weight (100%): deltamethrin 1.0%~30.0%; trans-anetinoside 5.0%~20.0%; organic solvent 5.0%~20.0%; polyurea capsule wall material 1.5%~5.0%; surfactant 3.0%~10.0%; thickener 0.1%~0.3%; defoamer 0.05%~0.5%; antifreeze 2.0%~5.0%; preservative 0.05%~0.2%; and deionized water to 100%.

[0010] The organic solvent is selected from at least one of solvent oil 150#, solvent oil 180#, methyl oleate, soybean oil methyl ester, xylene, cyclohexanone, and N-methylpyrrolidone.

[0011] Preferably, the mass ratio of trans-anetinoside to organic solvent is 1:0.5 to 1:2.

[0012] The polyurea capsule wall material is formed by interfacial polymerization of polyisocyanate and polyamine. The polyisocyanate is selected from at least one of toluene diisocyanate, diphenylmethane diisocyanate or polyphenylmethylene polyisocyanate, and the polyamine is selected from at least one of ethylenediamine, diethylenetriamine, triethylenetetramine or hexamethylenediamine.

[0013] The surfactant is selected from at least one of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, naphthalene sulfonate formaldehyde condensate, phenethylphenol polyoxyethylene ether, polyoxyethylene ether phosphate, EO-PO block copolymer, carboxylate dispersant, polyoxyethylene sorbitan monostearate, and lignin sulfonate.

[0014] The thickener is selected from at least one of xanthan gum, gum arabic, or bentonite.

[0015] The defoamer is an organosilicone defoamer.

[0016] The antifreeze is selected from at least one of ethylene glycol, propylene glycol, or glycerol.

[0017] The preservative is selected from at least one of isothiazolinone preservatives, parabens, sodium benzoate, or potassium sorbate.

[0018] The present invention also provides a method for preparing the deltamethrin microcapsule suspension containing the release promoter, comprising the following steps: (1) Preparation of oil phase: Mix deltamethrin technical material, trans-anetinoside, and organic solvent, stir to dissolve, then add polyisocyanate, stir to mix evenly, and obtain oil phase; (2) Preparation of aqueous phase: Mix a portion of surfactant, a small amount of defoamer and deionized water evenly to obtain an aqueous phase; (3) Preparation of mixed emulsion: Add the oil phase to the aqueous phase and emulsify under shear stirring for 15-30 min, then slowly add polyamine to form mixed emulsion; (4) Encapsulation reaction: The temperature of the mixed emulsion is slowly raised to 45-60℃ and stirred for 3-4 hours to allow the polyisocyanate and polyamine to polymerize at the oil-water interface to form deltamethrin microcapsules. (5) Microcapsule suspension: After cooling to room temperature, continue to add the remaining surfactants, thickeners, antifreeze, preservatives and remaining defoamers, stir and mix evenly to obtain deltamethrin microcapsule suspension. After passing the test, it is packaged to obtain the finished product.

[0019] Preferably, in step (1), the active ingredient is completely dissolved until the solution is clear and transparent before proceeding to the next step. If necessary, a heating device can be used to promote the dissolution of the active ingredient.

[0020] Preferably, in step (3), before adding the oil phase to the aqueous phase, the shearing machine in the mixing vessel is turned on, and the shearing time should not be too long to avoid demulsification.

[0021] Preferably, the stirring in step (4) does not use a shearing machine to avoid breaking the microcapsules.

[0022] Preferably, in step (5), the thickener is pre-dispersed in the antifreeze to avoid clumping and difficulty in dispersion.

[0023] The present invention unexpectedly discovered that trans-anisole, as a release promoter, can promote the initial release of active ingredients in microcapsules and improve the rapid effect of microcapsule suspensions.

[0024] The beneficial effects of this invention are: (1) The addition of trans-anisone significantly improved the release rate of deltamethrin, effectively solving the problem of poor rapid action of traditional microcapsule preparations; and trans-anisone replaced some organic solvents, reducing the use of toxic solvents such as toluene and xylene, making it safer. (2) The polyurea capsule wall material of the present invention is dense and has high mechanical strength, with an encapsulation rate of over 90% and a low decomposition rate of active ingredients; the formulation has excellent cold and hot storage stability and no layering or clumping in appearance. (3) The formulation of the present invention has excellent control effect on a variety of agricultural pests such as peach fruit moth, cabbage caterpillar, diamondback moth, and cotton bollworm, and is suitable for a variety of crops such as fruit trees and vegetables. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 The production process flow of deltamethrin microcapsule suspension in Example 1 is shown below. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1 Formula composition

[0029] Example 2 Formula composition

[0030] Example 3 Formula composition

[0031] Example 4 According to NY / T 2989-2016, NY / T 4001-2021, and Q / PMB 651-2024, the quality indicators of Examples 1-3 were tested, and the specific data are summarized in the table below:

[0032] Release rate refers to the amount of free deltamethrin determined after rupture with acetone, and the determination method is based on NY / T40012021.

[0033] Example 5: Trans-anetinoside-promoted deltamethrin release assay (1) Samples: Examples 1-3, with nominal effective ingredient contents of 5.0%, 8.0% and 3.0% respectively; Comparative samples 1-3 were prepared according to the formulations of Examples 1-3, except that trans-anetinoside was not added, and solvent oil 150#, methyl oleate and solvent oil 180# were used respectively.

[0034] (2) Release medium: standard hard water (simulating field water use).

[0035] (3) Main instruments: Constant temperature water bath shaker (temperature control 30±2°C); Erlenmeyer flask with stopper (250mL); 0.45μm microporous filter membrane and filtration device; Ultrasonic cleaner (for capsule rupture and extraction); High-performance liquid chromatography (HPLC) or other equipment for detecting active ingredients; Analytical balance (accuracy 0.0001g).

[0036] (4) Test operation procedure Accurately weigh approximately 1.0 g (to a depth of 0.0001 g) of each of the six samples and place them in 250 mL Erlenmeyer flasks with stoppers. Add 100.0 mL of standard hard water to each flask.

[0037] The Erlenmeyer flask was placed in a constant temperature water bath shaker and continuously shaken at 100 r / min at 30±2℃. Samples were taken and measured at preset time points (1 day, 3 days, and 30 days). a. When the time point is reached, remove the corresponding Erlenmeyer flask, quickly filter the suspension through a 0.45μm filter membrane, and collect all the filtrate.

[0038] b. Wash the residual solids (microcapsules) on the filter membrane three times with an appropriate amount of fresh medium, and combine the filtrate and washing solution.

[0039] c. The content of the active ingredient in the filtrate is determined by HPLC, which is the amount (Mt) released into the medium at that time point.

[0040] d. Transfer the residual solids (unreleased microcapsules) on the filter membrane to the original Erlenmeyer flask, add the encapsulation rupture agent and medium, sonicate for 30 min, and after making up to volume, determine the content of the remaining active ingredient (Rt). This is used to verify mass balance.

[0041] (5) Calculate the release rate Release rate (%) = [Mt / (Mt+Rt)] × 100% Each sample was measured three times at each time point, and the average value was taken.

[0042] The released data is summarized in the table below.

[0043]

[0044] Experimental data show that the addition of trans-anetinoside significantly increased the release rate of deltamethrin. The sample from the example achieved a release rate of over 30% within one day, while the control samples did not exceed 20%. With prolonged exposure, the sample from the example achieved a release rate of approximately 90% or higher after 30 days, while the control samples still had over 15% of the active ingredient remaining unreleased.

[0045] Unbound by any theoretical constraints, the inventors believe that trans-anisone has a dual mechanism of action. On the one hand, trans-anisone participates in the oil phase formulation, increasing the solubility of deltamethrin in the oil phase; on the other hand, the benzene ring and olefin structure in the trans-anisone molecule can interact with the polyurea capsule wall, disrupting the dense crystalline structure of the capsule wall and increasing its free volume and porosity, thereby achieving rapid release of deltamethrin while maintaining the integrity of the microcapsules. Later, as trans-anisone is gradually released and consumed, its effect on promoting deltamethrin release disappears, and deltamethrin mainly diffuses slowly through the concentration difference between the inside and outside of the capsule wall.

[0046] Example 6 Field Trial To verify the control efficacy of the formulation of this invention against the peach fruit moth, a field plot trial was conducted in a peach orchard in Shandong Province from June to July 2025. The trial included eight treatments, each with four replicates, and five peach trees per replicate, arranged in a randomized block design. A commercially available 2.5% deltamethrin EC was used as a control, and a water-based blank control was also included. All samples from the examples and controls were diluted 1000-3000 times and sprayed (i.e., the dosage per acre was adjusted according to the tree canopy size, ensuring a consistent final concentration).

[0047] Experimental Methods: During the peak emergence period of the first generation of adult peach fruit moths (June 15th), a backpack sprayer was used to uniformly spray the pesticide at a rate of 1500 L / ha. The percentage of infested fruit was surveyed before application as a baseline. At 7, 15, and 30 days after application, the number of live insects and the percentage of infested fruit were surveyed for each treatment to calculate the insect population reduction rate and control effect. On each survey tree, two fruits (or fruiting branches) were randomly marked in each of the five directions (east, west, south, north, and center), for a total of 10 survey points per tree. The number of live insects (larvae) and the number of infested fruits with fresh frass or boreholes were counted at each marked point. Each survey was conducted by the same team to minimize human error.

[0048] Calculation formula: Insect population reduction rate (%) = [(Number of live insects in the treatment area before application - Number of live insects in the treatment area after application) / Number of live insects in the treatment area before application] × 100 Control efficacy (%) = [(Pest population reduction rate in the treated area - Pest population reduction rate in the blank control area) / (100 - Pest population reduction rate in the blank control area)] × 100 The final efficacy is expressed as the mean ± standard deviation of each replicate, and the results are shown in the table below.

[0049]

[0050] The above field trial data show that the sample of this invention rapidly releases the active ingredient in the initial stage, exhibiting a rapid control efficacy of over 90% within 7 days after application, and can immediately control the damage caused by the peach fruit moth. At 15 and 30 days after application, the control efficacy remains above 87% and 74% respectively, indicating that the product of this invention has both excellent rapid control efficacy and good residual effect.

[0051] The control sample showed only 25%-30% efficacy 7 days after application, indicating a significant window of opportunity for control. Although the efficacy gradually improved in the later stages, the initial lack of rapid effectiveness was the main problem in practical application, making it difficult to deal with sudden or explosive pest outbreaks.

[0052] Compared with commercially available 2.5% deltamethrin emulsifiable concentrate, the formulation of this invention has comparable rapid-acting properties and significantly better sustained-release properties, thanks to the sustained-release characteristics of the microencapsulation formulation.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A deltamethrin microcapsule suspension containing a release promoter, characterized in that, Based on a total weight of 100%, it includes the following components: deltamethrin 1.0%~30.0%; release promoter trans-anetinoside 5.0%~20.0%; organic solvent 5.0%~20.0%; polyurea capsule wall material 1.5%~5.0%; surfactant 3.0%~10.0%; thickener 0.1%~0.3%; defoamer 0.05%~0.5%; antifreeze 2.0%~5.0%; preservative 0.05%~0.2%; deionized water to 100%.

2. The deltamethrin microcapsule suspension containing a release promoter according to claim 1, characterized in that, The organic solvent is selected from at least one of solvent oil 150#, solvent oil 180#, methyl oleate, soybean oil methyl ester, xylene, cyclohexanone, and N-methylpyrrolidone.

3. The deltamethrin microcapsule suspension containing a release promoter according to claim 1, characterized in that, The mass ratio of trans-anetinoside to organic solvent is 1:0.5 to 1:

2.

4. The deltamethrin microcapsule suspension containing a release promoter according to claim 1, characterized in that, The polyurea capsule wall material is formed by interfacial polymerization of polyisocyanate and polyamine. The polyisocyanate is selected from at least one of toluene diisocyanate, diphenylmethane diisocyanate or polyphenylmethylene polyisocyanate, and the polyamine is selected from at least one of ethylenediamine, diethylenetriamine, triethylenetetramine or hexamethylenediamine.

5. The deltamethrin microcapsule suspension containing a release promoter according to claim 1, characterized in that, The surfactant is selected from at least one of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, naphthalene sulfonate formaldehyde condensate, phenethylphenol polyoxyethylene ether, polyoxyethylene ether phosphate, EO-PO block copolymer, carboxylate dispersant, polyoxyethylene sorbitan monostearate, and lignin sulfonate.

6. The deltamethrin microcapsule suspension containing a release promoter according to claim 1, characterized in that, The thickener is selected from at least one of xanthan gum, gum arabic, or bentonite; the defoamer is an organosilicon defoamer; the antifreeze is selected from at least one of ethylene glycol, propylene glycol, or glycerol; and the preservative is selected from at least one of isothiazolinone preservatives, parabens, sodium benzoate, or potassium sorbate.

7. A method for preparing a deltamethrin microcapsule suspension containing a release promoter according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Preparation of oil phase: Mix deltamethrin technical material, trans-anetinoside, and organic solvent, stir to dissolve, then add polyisocyanate, stir to mix evenly, and obtain oil phase; (2) Preparation of aqueous phase: Mix a portion of surfactant, a small amount of defoamer and deionized water evenly to obtain an aqueous phase; (3) Preparation of mixed emulsion: Add the oil phase to the aqueous phase and emulsify under shear stirring for 15-30 min, then slowly add polyamine to form mixed emulsion; (4) Encapsulation reaction: The temperature of the mixed emulsion is slowly raised to 45-60℃ and stirred for 3-4 hours to allow the polyisocyanate and polyamine to polymerize at the oil-water interface to form deltamethrin microcapsules. (5) Microcapsule suspension: After cooling to room temperature, continue to add the remaining surfactants, thickeners, antifreeze, preservatives and remaining defoamers, stir and mix evenly to obtain deltamethrin microcapsule suspension. After passing the test, it is packaged to obtain the finished product.

8. The method for preparing a deltamethrin microcapsule suspension containing a release promoter according to claim 7, characterized in that, In step (5), the thickener is pre-dispersed in the antifreeze to prevent clumping and difficulty in dispersion.

9. The use of a deltamethrin microcapsule suspension containing a release promoter according to any one of claims 1-6 for the control of crop pests.

10. The use of a deltamethrin microcapsule suspension containing a release promoter according to claim 9 for the control of crop pests, characterized in that, The crops include apples, citrus fruits, pears, peaches, and cabbages; the pests include peach fruit moth, cabbage caterpillar, diamondback moth, and bollworm.

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