Chlorofenapyr microcapsule, its preparation method and application

Abstract

The application belongs to the technical field of microcapsules of chlorofenapyr, and discloses a kind of microcapsules of chlorofenapyr, a preparation method and application thereof.The microcapsules of chlorofenapyr, structure includes capsule material and capsule core, capsule core contains chlorofenapyr, the capsule material is composed of resin capsule wall inner layer close to capsule core, calcium alginate gel intermediate layer and polydopamine biomimetic adhesion outer layer, and contains nano ultraviolet shielding agent in each layer of capsule material.The microcapsules of chlorofenapyr disclosed by the application can effectively prevent and control field pests with uniform active ingredient release, excellent stability, rainwater erosion resistance and excellent target adhesion performance.

Description

Technical Field

[0001] This invention relates to the field of chlorpyrifos microcapsule technology, and more specifically, to a chlorpyrifos microcapsule, its preparation method, and its application. Background Technology

[0002] Chlorpyrifos is a highly effective, low-toxicity pyrethroid insecticide. Current technology typically uses chlorpyrifos as the core, isopropyl diisocyanate as the wall material, and incorporates a nanocrystalline composition, employing interfacial polymerization and emulsion template methods to prepare a water-based suspension of chlorpyrifos. This suspension, with its microcapsule structure of chlorpyrifos encapsulated in a polyurethane resin wall, is effective in killing indoor pests such as mosquitoes, flies, and cockroaches, but it cannot be used for field pest control for the following reasons: (1) Uneven release of active ingredients.

[0003] Relying solely on a single layer of polyurethane resin for coating, the release rate is primarily controlled by the resin wall material, which suffers from permeability defects. When chlorpyrifos suspension comes into contact with field moisture, the concentration difference causes it to rapidly penetrate these defects and enter the water initially, resulting in a sudden release. Consequently, the release rate decreases significantly later, leading to insufficient efficacy and a pattern of "sudden release in the early stages, followed by weakness in the later stages," making long-term control of field pests impossible.

[0004] (2) Poor resistance to rain washout. Conventional water-based suspensions have weak adhesion to crop leaves after spraying and are easily washed away by rain or dew, resulting in loss of effective ingredients and environmental pollution. Summary of the Invention

[0005] This invention provides a chlorpyrifos microcapsule, whose active ingredient release is uniform, stable, and has better resistance to rain erosion and target adhesion than existing technologies.

[0006] Another object of the present invention is to provide a method for preparing the chlorpyrifos microcapsules.

[0007] Another object of the present invention is to provide the application of the chlorpyrifos microcapsules in the field control of pests.

[0008] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows: A chlorpyrifos microcapsule comprises a capsule material and a capsule core, the capsule core containing chlorpyrifos, and the capsule material consisting of a resin inner layer tightly adhering to the capsule core, a calcium alginate gel intermediate layer, and a polydopamine biomimetic adhesive outer layer.

[0009] The chlorpyrifos microcapsules of this invention, wherein the capsule material consists of an inner resin capsule wall layer, a calcium alginate gel intermediate layer, and a polydopamine biomimetic adhesive outer layer, can effectively control field pests. The specific principle is as follows: (1) Uniform release of active ingredients. The microcapsule material of this invention has a three-layer gradient structure of "dense resin inner layer - porous gel middle layer - biomimetic outer layer". Among them, the resin inner layer does not directly contact the field water and slowly releases chlorpyrifos, the calcium alginate middle layer can controllably swell and release slowly when it comes into contact with the field water, and the outer layer slowly degrades dopamine. This gradient structure requires chlorpyrifos to pass through three barriers with different properties, resulting in a smooth and long-lasting release curve, without "sudden release in the early stage and weak effect in the later stage", which can achieve long-term control of field pests.

[0010] (2) Excellent resistance to rain erosion. The outermost layer of the capsule material, polydopamine, has extremely strong biomimetic adhesion. It can form strong bonds with hydroxyl, amino and other groups on the surface of crop leaves, and can be firmly attached to the leaf surface. It is not easily washed off by rain or dew, and will not cause loss of effective ingredients or environmental pollution.

[0011] Preferably, each layer of the capsule material contains a nano-ultraviolet shielding agent.

[0012] Each layer of the encapsulation material contains a nano-UV shielding agent, resulting in chlorpyrifos microcapsules with excellent stability. The nano-UV shielding agent is uniformly dispersed in the three layers of the encapsulation wall, providing long-lasting UV protection and preventing the photodecomposition of chlorpyrifos.

[0013] The dense resin layer has excellent high-temperature resistance and forms a high-density hydrophobic barrier to prevent pyrethroid leakage.

[0014] Preferably, the core also contains a plant oil penetration enhancer.

[0015] More preferably, the plant oil penetration aid is one or two of rosin-based plant oil and methylated plant oil.

[0016] Plant oil penetration enhancers, in combination with chlorpyrifos, have a high insecticidal efficiency, specifically: Plant oil penetration aids can efficiently dissolve the waxy layer of insect epidermis and assist chlorpyrifos in quickly penetrating the cuticle, thereby significantly improving knockdown speed and stomach poison effect. It is especially advantageous for fruit flies that are highly migratory and require rapid suppression. Plant oil penetration aids dissolve the waxy coating on the surface of fruits and vegetables, helping chlorpyrifos to penetrate into the shallow layer of the fruit peel, killing eggs and newly hatched larvae in the egg-laying marks of fruit flies, achieving full-stage control of adults and larvae. The plant oil penetration aid balances the excessively high vapor pressure of chlorpyrifos, preventing rapid volatilization and loss in open fields, and extending the retention time of the pesticide film on the fruit surface.

[0017] The nano-ultraviolet shielding agent described in this invention is specifically surface-inert modified nano-TiO2 or nano-ZnO.

[0018] The resin described in this invention is selected from urea-formaldehyde resin or melamine resin.

[0019] The specific preparation method of the surface-inert modified nano-TiO2 of the present invention is as follows: 1. Reagent ratio (parts by mass) 100 parts of nano-TiO2 powder, 400–600 parts of anhydrous ethanol (dispersion medium), 3–8 parts of hexadecyltrimethoxysilane HDTMS (modifier), and 0.3 times the mass of deionized water (silane hydrolysis) for HDTMS; glacial acetic acid is used as a hydrolysis catalyst.

[0020] 2. Specific operating steps: 1) Powder pre-dispersion: Mix nano-TiO2 with ethanol, and ultrasonically disperse for 30–40 min at an ultrasonic power of 300–500 W and a temperature of 40–50 ℃ to break up hard agglomerates and obtain a uniform suspension. 2) Preparation of silane hydrolysis solution: HDTMS, deionized water, and glacial acetic acid are mixed and stirred at 40 °C for 20–30 min to hydrolyze the silane completely to generate silanol; 3) The hydrolyzed silane solution was added dropwise to the TiO2 ethanol suspension at a uniform rate for 30 min; the temperature was raised to 60–70 ℃ and stirred for 2.5–4 h; the silanol and the hydroxyl groups on the TiO2 surface underwent dehydration condensation, and a layer of long alkylsilane inert film was bonded on the particle surface, which passivated the surface active sites and eliminated hydrophilic groups. 4) Cool the reaction solution to room temperature, centrifuge at 3000 r / min for 10 min, and wash the precipitate 2–3 times with anhydrous ethanol to remove ungrafted free silane; 5) Vacuum dry at 45–55 ℃ for 8–12 h, then pass through a 300-mesh sieve to obtain surface inert hydrophobic modified nano-TiO2.

[0021] The specific preparation method of the surface-inert modified nano-ZnO described in this invention is as follows: 1. Reagent ratio (parts by mass) 100 parts of nano ZnO powder, 500–700 parts of anhydrous ethanol, 4–9 parts of HDTMS silane, and 0.3 times the mass of deionized water as silane; glacial acetic acid is used as a hydrolysis catalyst.

[0022] 2. Specific operating steps: 1) Pre-dispersion: ZnO + ethanol, sonicated at 40–50 ℃ for 40–50 min, power 300–500 W; 2) Silane hydrolysis: Same as TiO2 process, hydrolyze at 40 ℃ for 20–30 min; 3) Coating reaction: Hydrolyzed silane was added dropwise for 30 min, and stirred at a constant temperature of 65–75 ℃ for 3–4.5 h; 4) The centrifugal washing, vacuum drying, and sieving parameters are completely consistent with those of modified TiO2.

[0023] More preferably, the plant oil penetration aid is one or two of rosin-based plant oil and methylated plant oil.

[0024] This invention also provides a method for preparing the chlorpyrifos microcapsules described in any one of the above claims, comprising the following steps: S1.O / W emulsion emulsification: First, dissolve chlorpyrifos, then add a penetration enhancer and mix thoroughly to obtain capsules. The core oil phase is prepared; then, sodium alginate is dissolved to obtain an aqueous sodium alginate phase; finally, the core oil phase is added to the aqueous sodium alginate phase for high-speed shear emulsification to form a stable oil-in-water O / W emulsion. S2. In-situ polymerization to coat the inner layer of resin: The resin prepolymer is dripped into the O / W emulsion obtained in S1 at a uniform rate and prepolymerized at a constant temperature to form a resin inner layer that is closely attached to the core. S3. Construction of the calcium alginate gel intermediate layer by calcium ion crosslinking: Calcium chloride aqueous solution was slowly and uniformly added to... After the inner layer of resin has been polymerized, a calcium alginate gel intermediate layer is formed in situ on the outer layer of resin through heat preservation and curing in the emulsion. S4. In-situ polymerization of polydopamine biomimetic adhesive outer layer: This is achieved after the formation of the calcium alginate gel intermediate layer. Tris buffer salt was added to the emulsion, followed by dopamine hydrochloride and continuous stirring. A polydopamine film was uniformly deposited on the outer surface of the calcium alginate gel intermediate layer to form a polydopamine biomimetic adhesive outer layer, thus obtaining chlorpyrifos microcapsules.

[0025] Preferably, the components added are as follows by weight: 5-20 parts of chlorpyrifos; 10-25 parts of penetration aid; 3-8 parts of resin; 0.5-3 parts of nano-UV shielding agent; 0.5-2 parts of sodium alginate; 0.3-1.5 parts of calcium chloride; and 0.1-0.5 parts of polydopamine.

[0026] The pH of the aqueous phase of sodium alginate in this invention is 4.0~5.0.

[0027] Preferably, the prepolymerization temperature of S2 is 55~65℃ and the prepolymerization time is 2.5~3.5h.

[0028] Preferably, in step S4, after adding Tris buffer salt, the pH is adjusted to 8.0~8.5, and dopamine hydrochloride is added and stirred continuously for 6~10 h.

[0029] Preferably, after forming the polydopamine biomimetic adhesive outer layer in step S4, the product is then subjected to solid-liquid separation and low-temperature drying to obtain chlorpyrifos microcapsules.

[0030] The preparation method of the chlorpyrifos microcapsules of the present invention specifically includes the following steps: S1.O / W emulsion emulsification, as detailed below: S11. Preparation of core oil phase: Add metered chlorpyrifos to a stirring container at room temperature, heat to 40~50℃ and stir at low speed until completely dissolved; add vegetable oil penetration aid, stir at constant temperature for 15~25 min, and mix evenly; then surface inert treatment of nano UV shielding agent, high-speed dispersion and homogenization for 30 min at a speed of 8000~10000 r / min to ensure that the nano powder does not agglomerate and is evenly dispersed in the pyrethrin oil phase to obtain a uniform core oil phase, and keep it at 40℃ for later use. S12. Aqueous phase preparation and O / W emulsion emulsification: In a separate reaction vessel, add a measured amount of deionized water, add the emulsifier, stir to dissolve, slowly add sodium alginate powder, stir in a water bath at 40~50℃ for 1.5~2 h until completely dissolved and free of gel lumps, adjust the pH of the aqueous phase to 4.0~5.0 with dilute hydrochloric acid to prepare the sodium alginate aqueous phase; the emulsifier is selected from fatty alcohol ethers or alkylphenol polyoxyethylene ethers; The oil phase of the capsule core, kept at 40℃, was slowly added dropwise to the aqueous phase of sodium alginate. High-speed shear emulsification was carried out at a speed of 6000 r / min for 20-30 min to form a stable oil-in-water (O / W) emulsion. The droplet size of the emulsion was controlled at 2-15 μm. The resulting emulsion was kept at a constant temperature of 40℃ and stirred at a low speed (300 r / min) to prevent stratification.

[0031] S2. In-situ polymerization to coat the inner layer of resin, specifically urea-formaldehyde resin or melamine resin, wherein: The preparation steps for the urea-formaldehyde resin inner layer specifically include the following steps: (1) Preparation of urea-formaldehyde prepolymer: The molar ratio of urea to formaldehyde is 1:(1~2), the pH is adjusted to 8.0~8.5 with triethanolamine, and the reaction is carried out at 65~75℃ for 40 min to obtain low molecular weight UF prepolymer, which is then cooled for later use; (2) Slowly add the metered UF prepolymer dropwise into the above O / W emulsion over a period of 30 min; after the addition is complete, slowly adjust the pH of the system to 3.0-3.8 with dilute hydrochloric acid. (3) Heat to 55~60℃, keep warm and stir at low speed for 2.5~3.5 h, the urea-formaldehyde prepolymer undergoes in-situ condensation at the oil droplet interface, forming a dense urea-formaldehyde resin inner wall outside the core.

[0032] The preparation steps of the melamine resin inner layer specifically include the following steps: (1) Mix melamine, formaldehyde, and deionized water, adjust the pH to 8.3~8.8 with triethanolamine, and prepolymerize at 70~80℃ for 30 min to prepare MF prepolymer solution; (2) The prepolymer solution was added dropwise to the emulsion at a uniform rate, and the addition was completed in 30 minutes. The pH of the system was then adjusted to 3.2-4.0. (3) Polymerize at a constant temperature of 60~65℃ for 3 h to form a melamine resin inner layer on the surface of the core.

[0033] S3. Calcium ion crosslinking constructs the calcium alginate gel intermediate layer, as detailed below: After the inner layer of resin has polymerized, the temperature is lowered to 35~40℃; Prepare an 8-12 wt% calcium chloride aqueous solution and add it dropwise to the reaction system at a uniform rate over a period of 40-60 minutes, with the stirring speed at 200 r / min throughout the process. After the addition is complete, keep warm and mature for 1 hour. Free alginate and Ca²⁺ in the emulsion will react. + Ionic cross-linking occurs, forming calcium alginate hydrogel in situ on the outer layer of the resin.

[0034] S4. In-situ polymerized polydopamine biomimetic adhesive outer layer, as detailed below: (1) Add Tris buffer salt to the system and adjust the pH of the system to 8.0~8.5; (2) Add dopamine hydrochloride and stir continuously at room temperature for 6-10 h; oxygen in the air acts as an oxidant, and dopamine undergoes self-oxidative polymerization, uniformly depositing a polydopamine film on the outer surface of calcium alginate gel to form a third biomimetic adhesion outer layer; determination of polymerization endpoint: the system is light brown, there is no free dopamine monomer, and the microcapsule suspension shows no obvious demulsification or stratification when left to stand. (3) After forming the polydopamine biomimetic adhesive outer layer, solid-liquid separation and low-temperature drying are performed to obtain chlorpyrifos microcapsules, as follows: Solid-liquid separation: Collect microcapsule solids by vacuum filtration or centrifugation (3000 r / min, 10 min); Washing and purification: Wash 2-3 times each with deionized water and anhydrous ethanol to remove unreacted resin. Free calcium salts, unpolymerized dopamine, and excess emulsifier impurities; Low-temperature drying: Vacuum drying at 40~45℃ for 8~12 h to avoid decomposition of chlorpyrifos due to high temperature.

[0035] The present invention also provides the application of the chlorpyrifos microcapsules described in any of the above-mentioned claims in the field control of pests. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to specific embodiments.

[0037] The nano-UV shielding agent used in the various embodiments and comparative examples of this invention is specifically surface-inert modified nano-TiO2, and the preparation method of surface-inert modified nano-TiO2 is as follows: 1. Reagent ratio (parts by mass) 100 parts of nano-TiO2 powder, 500 parts of anhydrous ethanol (dispersion medium), 5 parts of hexadecyltrimethoxysilane HDTMS (modifier), and 0.3 times the mass of deionized water (silane hydrolysis) for HDTMS; glacial acetic acid is used as a hydrolysis catalyst.

[0038] 2. Specific operating steps: 1) Powder pre-dispersion: Mix nano-TiO2 with ethanol, and ultrasonically disperse for 30–40 min at an ultrasonic power of 300–500 W and a temperature of 45 ℃ to break up hard agglomerates and obtain a uniform suspension. 2) Preparation of silane hydrolysis solution: HDTMS, deionized water, and glacial acetic acid are mixed and stirred at 40 °C for 20–30 min to hydrolyze the silane completely to generate silanol; 3) The hydrolyzed silane solution was added dropwise to the TiO2 ethanol suspension at a uniform rate for 30 min; the temperature was raised to 65 ℃ and stirred for 3.5 h; the silanol and the hydroxyl groups on the TiO2 surface underwent dehydration condensation, and a layer of long alkylsilane inert film was bonded on the particle surface, which passivated the surface active sites and eliminated hydrophilic groups; 4) Cool the reaction solution to room temperature, centrifuge at 3000 r / min for 10 min, and wash the precipitate 2–3 times with anhydrous ethanol to remove ungrafted free silane; 5) Vacuum dry at 50 ℃ for 10 h, and pass through a 300-mesh sieve to obtain surface inert hydrophobic modified nano-TiO2.

[0039] The nano-UV shielding agent used in the various embodiments and comparative examples of this invention is specifically surface-inert modified nano-TiO2, and the preparation method of surface-inert modified nano-ZnO is as follows: 1. Reagent ratio (parts by mass) 100 parts of nano ZnO powder, 600 parts of anhydrous ethanol, 6 parts of HDTMS silane, and 0.3 times the mass of deionized water as silane; glacial acetic acid was used as a hydrolysis catalyst.

[0040] 3. Specific operating steps: 5) Pre-dispersion: ZnO + ethanol, sonicated at 45 ℃ for 40–50 min, power 300–500 W; 6) Silane hydrolysis: Same as TiO2 process, hydrolyze at 40 ℃ for 20–30 min; 7) Coating reaction: Hydrolyzed silane was added dropwise for 30 min, and the mixture was stirred at a constant temperature of 70℃ for 4 h; 8) The centrifugal washing, vacuum drying, and sieving parameters are completely consistent with those of modified TiO2.

[0041] Example 1 A chlorpyrifos microcapsule comprises a capsule material and a core, the core containing chlorpyrifos and a plant oil penetration enhancer; the capsule material consists of a resin inner layer tightly adhering to the core, a calcium alginate gel intermediate layer, and a polydopamine biomimetic adhesion outer layer, each layer of the capsule material containing a nano-UV shielding agent, specifically a surface-inert modified nano-TiO2; the plant oil penetration enhancer is specifically a rosin-based plant oil; and the resin is specifically urea-formaldehyde resin.

[0042] In the preparation method of chlorpyrifos microcapsules, the amounts of each component added are as follows: 15 parts chlorpyrifos, 20 parts plant oil permeability enhancer, 5 parts resin, 2 parts nano UV shielding agent, 1 part sodium alginate, 1 part calcium chloride, 0.3 parts polydopamine, and 3 parts emulsifier; the preparation method of the chlorpyrifos microcapsules specifically includes the following steps: S1.O / W emulsion emulsification, as detailed below: S11. Preparation of core oil phase: Add metered chlorpyrifos to a stirring container at room temperature, heat to 45℃ and stir at low speed until completely dissolved; add vegetable oil penetration aid, stir at constant temperature for 20 min and mix evenly; then surface inert treatment of nano UV shielding agent, high-speed dispersion and homogenization for 30 min at 9000 r / min to ensure that the nano powder does not agglomerate and is evenly dispersed in the pyrethrin oil phase to obtain a uniform core oil phase, and keep warm at 40℃ for later use. S12. Aqueous phase preparation and O / W emulsion emulsification: In a separate reaction vessel, add a measured amount of deionized water, add the emulsifier, stir to dissolve, slowly add sodium alginate powder, stir in a 45°C water bath for 1.8 h until completely dissolved and free of gel lumps, adjust the pH of the aqueous phase to 4.5 with dilute hydrochloric acid to prepare the sodium alginate aqueous phase; the emulsifier is selected from fatty alcohol ethers; The oil phase of the capsule core, kept at 40℃, was slowly added dropwise to the aqueous phase of sodium alginate. High-speed shear emulsification was carried out at a speed of 6000 r / min for 25 min to form a stable oil-in-water (O / W) emulsion. The droplet size of the emulsion was controlled at 2~15 μm. The resulting emulsion was kept at a constant temperature of 40℃ and stirred at a low speed (300 r / min) to prevent stratification.

[0043] S2. In-situ polymerization to coat the inner layer of resin, specifically urea-formaldehyde resin, wherein: The preparation steps for the urea-formaldehyde resin inner layer specifically include the following steps: (1) Preparation of urea-formaldehyde prepolymer: The molar ratio of urea to formaldehyde is 1:1.5, the pH is adjusted to 8.2 with triethanolamine, and the reaction is carried out at 70℃ for 40 min to obtain low molecular weight UF prepolymer, which is then cooled for later use; (2) Slowly add the metered UF prepolymer dropwise into the above O / W emulsion over a period of 30 min; after the addition is complete, slowly adjust the pH of the system to 3.5 with dilute hydrochloric acid. (3) Heat to 55~60℃, keep warm and stir at low speed for 3.0 h. The urea-formaldehyde prepolymer undergoes in-situ condensation at the oil droplet interface, forming a dense urea-formaldehyde resin inner wall outside the core.

[0044] S3. Calcium ion crosslinking constructs the calcium alginate gel intermediate layer, as detailed below: After the inner layer of resin has polymerized, the temperature is lowered to 35~40℃; Prepare a 10 wt% calcium chloride aqueous solution and add it dropwise to the reaction system at a uniform rate over a period of 40-60 minutes, with the stirring speed at 200 r / min throughout the process. After the addition is complete, keep warm and mature for 1 hour. Free alginate and Ca²⁺ in the emulsion will react. + Ionic cross-linking occurs, forming calcium alginate hydrogel in situ on the outer layer of the resin.

[0045] S4. In-situ polymerized polydopamine biomimetic adhesive outer layer, as detailed below: (1) Add Tris buffer salt to the system and adjust the pH of the system to 8.2; (2) Add dopamine hydrochloride and stir continuously at room temperature for 8 h; oxygen in the air acts as an oxidant, and dopamine undergoes self-oxidative polymerization, uniformly depositing a polydopamine film on the outer surface of calcium alginate gel to form a third biomimetic adhesion outer layer; determination of polymerization endpoint: the system is light brown, there is no free dopamine monomer, and the microcapsule suspension does not show obvious demulsification or stratification when left to stand. (3) After forming a polydopamine biomimetic adhesive outer layer, solid-liquid separation and low-temperature drying are performed to obtain chlorpyrifos microcapsules, as follows: Solid-liquid separation: Collect microcapsule solids by vacuum filtration or centrifugation (3000 r / min, 10 min); Washing and purification: Wash 2-3 times each with deionized water and anhydrous ethanol to remove unreacted resin. Free calcium salts, unpolymerized dopamine, and excess emulsifier impurities; Low-temperature drying: vacuum drying at 42℃ for 10 h.

[0046] Example 2 The method is basically the same as in Example 1, except that in the preparation method of chlorpyrifos microcapsules, the amount of each component added is as follows: 5 parts chlorpyrifos, 10 parts plant oil permeability agent, 3 parts resin, 0.5 parts nano UV shielding agent (specifically ZnO), 0.5 parts sodium alginate, 0.3 parts calcium chloride, 0.1 parts polydopamine, and 2 parts emulsifier (specifically alkylphenol polyoxyethylene ether).

[0047] Example 3 The method is basically the same as in Example 1, except that in the preparation method of chlorpyrifos microcapsules, the amount of each component added is as follows: 20 parts of chlorpyrifos, 25 parts of plant oil permeability agent, 8 parts of resin, 3 parts of nano UV shielding agent (specifically ZnO), 2 parts of sodium alginate, 1.5 parts of calcium chloride, 0.5 parts of polydopamine, and 4 parts of emulsifier (specifically alkylphenol polyoxyethylene ether).

[0048] Example 4 The method is basically the same as in Example 1, except that in the preparation method of chlorpyrifos microcapsules, the pH of the aqueous phase of sodium alginate (S12) is 4.0.

[0049] Example 5 It is basically the same as Example 1, except that the pH of the aqueous phase of sodium alginate in S12 is 5.0.

[0050] Example 6 The method is basically the same as in Example 1, except that the resin in the chlorpyrifos microcapsule component is specifically melamine resin. In the preparation method of chlorpyrifos microcapsules, S2. in-situ polymerization to coat the inner layer of resin is specifically as follows: (1) Mix melamine, formaldehyde, and deionized water, adjust the pH to 8.5 with triethanolamine, and prepolymerize at 75℃ for 30 min to prepare MF prepolymer solution; (2) The prepolymer solution was added dropwise to the emulsion at a uniform rate, and the addition was completed in 30 minutes. The pH of the system was then adjusted to 3.6. (3) Polymerize at a constant temperature of 60~65℃ for 3 h to form a melamine resin inner layer on the surface of the core.

[0051] Example 7 The method is basically the same as in Example 1, except that in the preparation method of chlorpyrifos microcapsules, S4. in-situ polymerization of polydopamine biomimetic adhesion outer layer, as follows: Add Tris buffer salt to the system and adjust the pH to 8.0; Add dopamine hydrochloride and stir continuously at room temperature for 6 hours.

[0052] Example 8 The method is basically the same as in Example 1, except that in the preparation method of chlorpyrifos microcapsules, S4. in-situ polymerization of polydopamine biomimetic adhesion outer layer, as follows: Add Tris buffer salt to the system and adjust the pH to 8.5; Add dopamine hydrochloride and stir continuously at room temperature for 10 h.

[0053] Example 9 The method is basically the same as in Example 1, except that the core of the chlorpyrifos microcapsules does not contain... Plant oil penetration aid.

[0054] Comparative Example 1 Similar to Example 1, except that the layers of the chlorpyrifos microcapsules do not contain nano-UV shielding agents.

[0055] Comparative Example 2 The method is basically the same as in Example 1, except that the wall material of the chlorpyrifos microcapsules only has a resin inner layer, without a calcium alginate gel intermediate layer and a polydopamine biomimetic adhesion outer layer; and steps S3 and S4 are not performed in the preparation method of chlorpyrifos microcapsules.

[0056] Comparative Example 3 The method is basically the same as in Example 1, except that the wall material of the chlorpyrifos microcapsules only has a calcium alginate gel intermediate layer, without a resin inner layer and without a polydopamine biomimetic adhesion outer layer; in the preparation method of chlorpyrifos microcapsules, step S3 is directly performed after step S1, without step S2 and step S4.

[0057] Comparative Example 4 The method is basically the same as in Example 1, except that the wall material of the chlorpyrifos microcapsules only has a polydopamine biomimetic adhesion outer layer, without a calcium alginate gel intermediate layer or a resin inner layer; in the preparation method of chlorpyrifos microcapsules, step S4 is directly performed after step S1, without step S2 and step S3.

[0058] Comparative Example 5 Similar to Example 1, except that the wall material of the chlorpyrifos microcapsules consists only of an inner resin layer and a calcium alginate gel intermediate layer, without a polydopamine biomimetic adhesion outer layer; and step S4 is not performed in the preparation method of the chlorpyrifos microcapsules.

[0059] Comparative Example 6 The method is basically the same as in Example 1, except that the wall material of the chlorpyrifos microcapsules only has a resin inner layer and a polydopamine biomimetic adhesion outer layer, without a calcium alginate gel intermediate layer; in the preparation method of chlorpyrifos microcapsules, step S4 is directly performed after step S2, and step S3 is not performed.

[0060] Comparative Example 7 The method is basically the same as in Example 1, except that the wall material of the chlorpyrifos microcapsules only has a calcium alginate gel intermediate layer and a polydopamine biomimetic adhesion outer layer, without a resin inner layer; in the preparation method of chlorpyrifos microcapsules, steps S3 and S4 are performed directly after step S1, and step S2 is not performed.

[0061] Performance testing: The particle size detection method for the chlorpyrifos microcapsules obtained in the examples is as follows: Sampling: Take 0.1–0.2 g of the dried finished microcapsules; Dispersion medium: deionized water (the system is hydrophilic, preventing organic solvents from dissolving the capsule wall); Dispersion: Add a small amount of dispersant (dilute sodium dodecyl sulfate solution), stir at low speed for 3 minutes, and then gently ultrasonically disperse for 1-2 minutes (low ultrasonic power to prevent capsule rupture and core leakage). Opacity adjustment: Dilute the suspension to a 10%–20% occupancy rate on the laser particle size analyzer and remove air bubbles; The particle size D50 of the chlorpyrifos microcapsules obtained in the examples is 5~18 μm.

[0062] I. Uniformity of Active Ingredient Release from Chlorpheniramine Microcapsules 1. Testing Principle Simulating field rainwater / soil water environment, a static slow-release extraction method was used to periodically measure the chlorpyrifos content in the slow-release medium. The release uniformity was evaluated by three indicators: burst release rate, slow-release period, and coefficient of variation of release uniformity.

[0063] (1) 72h burst release rate: 72h cumulative release amount / total effective ingredients of microcapsules × 100%. The lower the value, the lighter the initial burst release. (2) 25-day cumulative release rate: characterizing long-acting sustained-release capability; (3) Coefficient of variation of release uniformity: The standard deviation of the daily release rate from 1 to 25 days is calculated as the average release rate. The smaller the CV, the more stable and uniform the release.

[0064] 2. Experimental instruments and reagents Instruments: High performance liquid chromatograph (HPLC), constant temperature water bath shaker, centrifuge tubes, 0.22μm organic filter membrane, electronic balance, vacuum drying oven; Reagents: Acetonitrile (chromatographic grade), deionized water, standard chlorpyrifos, and microcapsule samples from each example / comparative example; Slow-release medium: pH 6.8 phosphate buffer (simulating the field leaf surface moisture environment).

[0065] 3. Sample pretreatment Take 0.5000g of dried finished microcapsules from each of Examples 1-9 and Comparative Examples 1-7, and accurately weigh them into three parallel portions for each group; Determination of total effective ingredient content (benchmark value) Weigh 0.5g of microcapsules, add 20mL of acetonitrile, sonicate for 30min, centrifuge and collect the supernatant, and determine the total content M0 (mg) of chlorpyrifos by HPLC, which is taken as the theoretical maximum release amount of the sample.

[0066] 4. Procedural steps for sustained-release testing (1) Preparation of sustained-release system: Add 400mL of pH6.8 phosphate buffer to a 500mL stoppered conical flask and place it in a 25℃ constant temperature water bath shaker at a speed of 120r / min; (2) Sample loading: Add 0.5g of the microcapsule to be tested into the buffer solution and start timing; (3) Timed sampling: Samples were taken at 6h, 24h, 2d, 3d, 4d, 5d, 6d, 7d, 14d, and 25d respectively; 5mL of sustained-release solution was taken each time, and 5mL of fresh buffer solution was added at the same time to maintain the volume unchanged; (4) Sample detection: The sustained-release solution was filtered through a 0.22 μm filter membrane, and the mass M of chlorpyrifos in the filtrate was determined by HPLC. t ; (5) Calculation of indicators: Instantaneous release rate Rt = (Mt / M0) × 100%; 72h burst release = R 24h ; Total cumulative release rate over 25 days = ; Daily release rate ν d : Percentage of release on day d; Release uniformity coefficient of variation CV= ×100%, SD is the standard deviation of daily release rate; ν is the 7-day average daily release rate.

[0067] The results of the uniformity of release of active ingredients from the chlorpyrifos microcapsules obtained in Examples 1-9 and Comparative Examples 1-7 are shown in Table 1.

[0068] Table 1. Sustained-release effects of chlorpyrifos microcapsules obtained in Examples 1-9 and Comparative Examples 1-7

[0069] II. Stability test of chlorpyrifos microcapsules General experimental instruments and reagents Instruments: High performance liquid chromatography (HPLC), ultraviolet aging test chamber, constant temperature forced air drying oven, simulated rain erosion test device, high speed centrifuge, vacuum filtration device, 0.22μm organic filter membrane, electronic analytical balance, ultraviolet spectrophotometer; Standard: Chlorpheniramine standard sample; Reagents: Chromatographic grade acetonitrile, deionized water, anhydrous ethanol, pH 6.8 phosphate buffer; Samples to be tested: Dry microcapsule powders from Examples 1-9 and Comparative Examples 1-7.

[0070] 1. Ultraviolet light stability test 1.1 Test Principle Ultraviolet light was used to simulate the ultraviolet radiation of sunlight in the field. After long-term irradiation, the content of the remaining active ingredients in the microcapsules was measured, and the photostability was evaluated by the residual rate of the active ingredients. The higher the residual rate, the better the protective effect of the nano-ultraviolet shielding agent.

[0071] 1.2 Operating Procedures (1) Weigh 0.2000g of each microcapsule to be tested and spread it evenly on a quartz sample dish. The sample thickness should be ≤0.5mm. (2) UV aging chamber conditions: UV lamp 365nm, light intensity 0.85W / m², constant temperature 40℃, continuous light irradiation for 120h; (3) Blank standard: The same mass of unexposed microcapsules were extracted with acetonitrile by ultrasonic extraction for 30 min, and the initial content of chlorpyrifos C0 was determined by HPLC; (4) After the light exposure ends, take out all samples and extract and detect the remaining effective content C1 after light exposure using the same method; (5) Calculation formula: Light residue rate (%) = (C1 / C0) × 100% 2: High-temperature thermal stability test (evaluating the ability to inhibit high-temperature storage and high-temperature leakage in the field) 2.1 Test Principle Simulating high-temperature storage / field high-temperature environments in summer, the leakage of microcapsules was measured after high-temperature sealed placement. The high-temperature leakage rate was used to characterize the drug-locking ability of the capsule wall. The lower the leakage rate, the better the barrier effect of the inner resin layer.

[0072] 2.2 Operating Procedures (1) Accurately weigh 0.5000g of microcapsules and place them in a sealed, pressure-resistant glass bottle; (2) Set the oven to 54℃ (the standard temperature for conventional heat storage of pesticides) and store it in a sealed environment at a constant temperature for 14 days; (3) After the heat storage is completed, all samples are transferred to centrifuge tubes, 50 mL of n-hexane is added (only to dissolve the pyrethroids that have leaked out of the capsule, without penetrating the intact capsule wall), shake at low speed for 10 min, and centrifuge at 3000 r / min for 10 min. (4) Take the supernatant and determine the mass M of the leaked pyrethroid by HPLC. 漏 ; (5) Simultaneously determine the total effective content M of the same batch of microcapsules 总 ; (6) Calculation formula: High temperature leakage rate (%) = (M 漏 / M 总 ) × 100% 3: Rainwater erosion adhesion stability test (evaluating leaf adhesion and resistance to leaching) 3.1 Test Principle Fresh citrus leaves (the target crop for fruit flies) were coated with a microcapsule suspension and dried. Then, they were continuously sprayed with simulated moderate rain to measure the retention rate of the effective components remaining on the leaves after being washed away. The higher the retention rate, the stronger the biomimetic adhesion effect of polydopamine.

[0073] 3.2 Operating Procedures (1) Preparation of microcapsule suspension: 0.1g microcapsule + 10mL deionized water, stir well; (2) Select fresh citrus leaves of uniform size, wipe off the surface moisture, coat each leaf evenly with 0.5 mL of suspension, and air dry at room temperature in the dark for 2 hours; 5 leaves per group; (3) Simulated rainwater device parameters: spray flow rate 2L / h, spray distance 30cm, continuous spraying for 30min; (4) After spraying, collect the leaves, cut them into pieces, add 20 mL of acetonitrile and ultrasonically extract for 40 min, and determine the residual pyrethroid content W1 in the leaves after rinsing; (5) Blank control group: Leaves with the same coating and not washed by rain were extracted and the initial drug loading W0 was measured; (6) Calculation formula: Rainwater erosion retention rate (%) = (W1 / W0) × 100% The stability test results of the chlorpyrifos microcapsules obtained in Examples 1-9 and Comparative Examples 1-7 are shown in Table 2.

[0074] Table 2. Stability of the chlorpyrifos microcapsules obtained in Examples 1-9 and Comparative Examples 1-7

[0075] III. Effects of Chlorpheniramine maleate microcapsules on killing fruit flies in field applications. 1. Basic Information of the Experiment 1.1 Test Subjects Target pest: Citrus fruit fly (natural population in orchards and fields, adults + eggs laid + newly hatched larvae); Test crop: 3-year-old citrus trees with uniform tree vigor and consistent fruit load; Experimental environment: Open-air citrus orchard, conventional field water and fertilizer management, with no pesticide residues from previous treatments.

[0076] 1.2 Test Sample Examples 1-9 and Comparative Examples 1-7: Chlorpheniramine microcapsules; 1.3 Instruments and Consumables Backpack electric sprayer, temperature and humidity recorder, standard insect rearing cage, scalpel, magnifying glass, electronic balance, handheld pH meter; 1.4 Evaluation Indicators 24-hour knockdown rate of adults: The proportion of dead adults that fall to the ground in the field 24 hours after pesticide application, which reflects the rapid knockdown effect; 30-day adult control efficacy: the inhibition rate of surviving adults in the field 30 days after pesticide application; Fruit infestation rate: 20 days after pesticide application, randomly harvested fruits and count the percentage of fruits with insect eggs / larvae.

[0077] 2. Complete Field Efficacy Testing Procedures Step 1: Experimental Cell Division The orchard was divided into 16 independent plots (9 groups for the example + 7 groups for the comparative example, for a total of 16 groups), with 3 citrus trees in each group; A 2m isolation buffer zone is set between the small groups to prevent drug drift interference; each group is repeated 3 times. One day before application, baseline survey was conducted: the number of active adult insects on each tree and the existing insect population in the fruit were counted, and the insect population in each group was standardized.

[0078] Step 2: Drug preparation and application Standardized dilution: All microcapsule samples were uniformly diluted to 100 mg / L of effective chlorpyrifos, and then the concentration was increased by adding water. Spraying procedure: Spray evenly over the entire plant, ensuring both sides of the leaves and the surface of the fruit are fully wetted until the solution is just about to drip; spray 2L per plant. Blank control supplement (auxiliary reference, not included in the table): Water spraying area; Application conditions: Sunny mornings from 9:00 to 11:00, temperature 24~30℃, no rain, light wind.

[0079] Step 3: Time-segmented sampling 24-hour knockdown survey: White sticky insect cloth is laid on the ground in each area, dead adult fruit flies are collected, the total number of active adult fruit flies in the area is counted, and the knockdown rate is calculated. 20-day adult survival survey: The survival rate of adult fruit flies was calculated using the trap counting method, based on the standard reference NYT1480.

[0080] 30-day survey of infested fruit: 20 fruits were randomly selected from each of the five directions (east, south, west, north, and center) of each plot. The fruits were dissected and examined for egg-laying marks and larvae. The number of infested fruits was counted and the infestation rate was calculated.

[0081] Step 4: Core Calculation Formula 24-hour knockdown rate (%) = (Number of dead insects on the ground in 24 hours / Total number of adult insects in the field before application) × 100% Insect-infested fruit rate (%) = (Number of infested fruits / Total number of fruits surveyed) × 100% Judgment criteria Excellent control efficacy: ≥85% knockdown rate in 24 hours, ≥90% adult control efficacy after 20 days, and ≤5% fruit infestation rate after 30 days; Moderate control efficacy: knockdown rate 60%~84%, adult control efficacy 70%~89%, and fruit infestation rate 5%~12%; Poor control efficacy: knockdown rate <60%, adult control efficacy <70%, and fruit infestation rate >12%.

[0082] The effects of the chlorpyrifos microcapsules obtained in Examples 1-9 and Comparative Examples 1-7 on killing fruit flies in the field are shown in Table 3.

[0083] Table 3 shows the application of chlorpyrifos microcapsules obtained in Examples 1-9 and Comparative Examples 1-7 in field pest control. Fruit fly effect

[0084] The above description is merely an embodiment of the present invention and does not limit the scope of patent protection. Any non-substantial changes or substitutions made by those skilled in the art based on the present invention will still fall within the scope of patent protection.

Claims

1. A microcapsule containing chlorpyrifos, comprising a capsule material and a core, wherein the core contains chlorpyrifos. Its features are, The capsule material consists of a resin inner layer that adheres closely to the capsule core, a calcium alginate gel intermediate layer, and a polydopamine biomimetic adhesive outer layer.

2. The chlorpyrifos microcapsules according to claim 1, characterized in that, In each layer of the capsule material It contains nano-UV shielding agents.

3. The chlorpyrifos microcapsules according to claim 1, characterized in that, The core also contains Plant oil penetration aid.

4. The chlorpyrifos microcapsules according to claim 2, characterized in that, The vegetable oil permeation The additives are one or both of rosin-based vegetable oil and methylated vegetable oil.

5. The method for preparing the chlorpyrifos microcapsules according to any one of claims 1 to 4, Its features are, Includes the following steps: S1.O / W emulsion emulsification: First, dissolve chlorpyrifos, then add a penetration enhancer and mix thoroughly to obtain capsules. The core oil phase is prepared; then, sodium alginate is dissolved to obtain an aqueous sodium alginate phase; finally, the core oil phase is added to the aqueous sodium alginate phase for high-speed shear emulsification to form a stable oil-in-water O / W emulsion. S2. In-situ polymerization to coat the inner resin layer: The resin prepolymer is dripped into the O / W emulsion obtained in S1 at a uniform rate and prepolymerized at a constant temperature to form a resin inner layer that is closely attached to the core. S3. Construction of the calcium alginate gel intermediate layer by calcium ion crosslinking: Calcium chloride aqueous solution was slowly and uniformly added to... After the inner layer of resin has been polymerized, a calcium alginate gel intermediate layer is formed in situ on the outer layer of resin in the emulsion after heat preservation and curing. S4. In-situ polymerization of polydopamine biomimetic adhesive outer layer: This is followed by the formation of the calcium alginate gel intermediate layer. Tris buffer salt was added to the emulsion, followed by dopamine hydrochloride and continuous stirring. A polydopamine film was uniformly deposited on the outer surface of the calcium alginate gel intermediate layer to form a polydopamine biomimetic adhesive outer layer, thus obtaining chlorpyrifos microcapsules.

6. The method for preparing chlorpyrifos microcapsules according to claim 5, characterized in that, The The specific weight percentages of each component are as follows: 5-20 parts of chlorpyrifos; 10-25 parts of penetration enhancer; 3-8 parts of resin; 0.5-3 parts of nano-UV shielding agent; 0.5-2 parts of sodium alginate; 0.3-1.5 parts of calcium chloride; and 0.1-0.5 parts of polydopamine.

7. The method for preparing chlorpyrifos microcapsules according to claim 5, characterized in that, The S2. The prepolymerization temperature is 55~65℃, and the prepolymerization time is 2.5~3.5h.

8. The method for preparing chlorpyrifos microcapsules according to claim 5, characterized in that, The S4. After adding Tris buffer salt, adjust the pH to 8.0~8.5, add dopamine hydrochloride and stir continuously for 6~10 h.

9. The method for preparing chlorpyrifos microcapsules according to claim 5, characterized in that, The S4. After forming a polydopamine biomimetic adhesive outer layer, solid-liquid separation and low-temperature drying are performed to obtain chlorpyrifos microcapsules.

10. The use of the chlorpyrifos microcapsules according to any one of claims 1 to 4 in the field control of pests.

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