Emamectin benzoate polyurethane / polyurea microcapsule suspending agent as well as preparation method and application thereof

Abstract

The invention provides an emamectin benzoate polyurethane / polyurea microcapsule suspending agent as well as a preparation method and application thereof, and belongs to the technical field of pesticide preparations. The emamectin benzoate polyurethane / polyurea microcapsule suspending agent is prepared by adopting an interfacial polymerization method, the stability and uniformity of shear emulsified liquid drops are ensured through the synergistic use of the oil-soluble emulsifier and the water-soluble emulsifier, and the interfacial polymerization reaction is promoted to be uniformly and compactly carried out on the surfaces of the oil drops through the addition of the protective colloid in the water phase. The capsule wall of the emamectin benzoate polyurethane / polyurea microcapsule has high compactness, emamectin benzoate can be effectively isolated from external light, heat and air, the decomposition rate of emamectin benzoate is remarkably slowed down, and the quality guarantee period of the product is prolonged. Besides, the compact microcapsule structure can enable the emamectin benzoate to be slowly released on target crops, prolong the lasting period of the pesticide effect, reduce the number of times of pesticide application and the pesticide dosage, remarkably reduce the acute toxicity of the effective component emamectin benzoate to non-target organisms, and improve the biological safety and environmental friendliness of the preparation.

Description

Technical Field

[0001] This invention relates to the field of pesticide formulation technology, specifically to an abamectin polyurethane / polyurea microcapsule suspension, its preparation method, and its application. Background Technology

[0002] Emamectin benzoate (emamectin benzoate for short) is a highly effective, broad-spectrum, low-toxicity, and low-residue semi-synthetic antibiotic insecticide with extremely high activity against lepidopteran pests. However, emamectin benzoate technical grade is sensitive to light, heat, and air, and is prone to decomposition during storage and use, leading to a decrease in the persistence of its efficacy. Furthermore, emamectin benzoate poses a high toxicity risk to non-target organisms such as aquatic organisms (e.g., fish) and beneficial insects (e.g., bees).

[0003] To overcome the aforementioned drawbacks, microencapsulation of abamectin is an effective technical approach. Microencapsulation technology encapsulates the active pesticide ingredient using a polymer wall material, forming a micron-sized core-shell structure. This structure effectively protects the active ingredient, slows its degradation rate in the environment, and achieves slow and sustained release of the pesticide, thereby extending its duration of action. Simultaneously, microencapsulation can reduce pesticide drift, lowering the toxicity risk during application and minimizing impacts on non-target organisms. Polyurethane, due to its excellent film-forming properties, good biodegradability, and controllable wall material density, is considered one of the ideal wall materials for preparing pesticide microcapsules. Interfacial polymerization is currently the mainstream technology for preparing polyurethane microcapsules.

[0004] Currently, existing technologies for preparing abamectin polyurethane microcapsules still have shortcomings, one of the core challenges being poor capsule wall density. This is typically due to: 1) the instability of the oil-water two-phase emulsion system, leading to uneven droplet size or aggregation during polymerization; 2) the difficulty in precisely controlling the interfacial polymerization rate, with isocyanate monomers potentially undergoing side reactions such as hydrolysis at the interface instead of efficient polymerization with polyols / amines; and 3) improper ratios or poor selection of wall material monomers (polyisocyanates and polyols / amines), resulting in defects or pores in the formed polymer network structure. These factors collectively lead to poor capsule wall density, making abamectin prone to premature leakage or degradation, and its stability and controlled-release effect do not reach ideal levels. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide an abamectin polyurethane / polyurea microcapsule suspension, its preparation method, and its application. The abamectin polyurethane / polyurea microcapsule suspension obtained by this invention has good capsule wall density and sustained-release effect, as well as good biocompatibility.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing an abamectin-based polyurethane / polyurea microcapsule suspension, comprising the following steps: The technical grade abamectin, polyisocyanate, oil-soluble emulsifier, and organic solvent are mixed to obtain the oil phase; A water-soluble emulsifier, dispersant, protective colloid, monomer, and water are mixed to obtain an aqueous phase, wherein the monomer includes polyols or polyamines; The oil phase is added to the aqueous phase and shear emulsification is performed to obtain an O / W type emulsion. The O / W type emulsion was subjected to interfacial polymerization, and after cooling, a pH adjuster, antifreeze, thickener and defoamer were added to obtain an abamectin polyurethane / polyurea microcapsule suspension.

[0007] Preferably, the amount of raw materials used in the preparation process, by mass percentage, is: 1-10% of abamectin technical grade; Organic solvents 5-20%; Polyisocyanates 1-8%; Polyols or polyamines 0.5-5%; Oil-soluble emulsifier 1-5%; Water-soluble emulsifier 1-5%; Dispersant 1~5%; Protective colloid 0.1~2%; pH adjuster 0.05~0.5%; Antifreeze 1-8%; Thickener 0.1~1.5%; Defoamer 0.05~0.5%; Deionized water balance.

[0008] Preferably, the polyisocyanate is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, isophorone diisocyanate and hexamethylene diisocyanate; The polyols include one or more of ethylene glycol, propylene glycol, and butanediol; The polyamines include one or more of ethylenediamine, hexamethylenediamine, diethylenetriamine, and triethanolamine.

[0009] Preferably, the oil-soluble emulsifier includes one or more of sorbitan monooleate and castor oil polyoxyethylene ether; The water-soluble emulsifier includes one or more of sodium dodecyl sulfate, lignin sulfonate, and alkylphenol polyoxyethylene ether.

[0010] Preferably, the dispersant comprises one or more of polycarboxylate, naphthalene sulfonate formaldehyde condensate, and lignin sulfonate; The protective colloid includes one or more of gelatin, gum arabic, polyvinyl alcohol, guar gum, hydroxypropyl guar gum, sodium carboxymethyl cellulose, sodium alginate, and polyvinylpyrrolidone.

[0011] Preferably, the pH adjuster includes one or more of citric acid, sodium citrate, sodium bicarbonate, sodium carbonate, disodium hydrogen phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, acetic acid, sodium acetate, lactic acid, triethanolamine, and isopropanolamine. The antifreeze includes ethylene glycol and / or propylene glycol; The thickener includes one or more of xanthan gum, magnesium aluminum silicate, and hydroxyethyl cellulose; The defoamer is an organosilicone defoamer.

[0012] Preferably, the shear emulsification rate is 5000~15000 rpm and the time is 10~30 min; The interfacial polymerization reaction is carried out at a temperature of 40~80℃ for 2~5 hours.

[0013] The present invention provides an abamectin polyurethane / polyurea microcapsule suspension prepared by the above preparation method, comprising a capsule wall and a capsule core, wherein the capsule wall is composed of polyurethane and / or polyurea, and the capsule core comprises abamectin.

[0014] Preferably, the particle size of the emamectin benzoate polyurethane / polyurea microcapsules is 2~10μm.

[0015] This invention provides the application of the above-mentioned abamectin polyurethane / polyurea microcapsule suspension in insecticides.

[0016] This invention provides a method for preparing an abamectin polyurethane / polyurea microcapsule suspension, comprising the following steps: mixing abamectin technical, polyisocyanate, an oil-soluble emulsifier, and an organic solvent to obtain an oil phase; mixing a water-soluble emulsifier, a dispersant, a protective colloid, a monomer, and water to obtain an aqueous phase, wherein the monomer includes a polyol or a polyamine; adding the oil phase to the aqueous phase and performing shear emulsification to obtain an O / W emulsion; subjecting the O / W emulsion to interfacial polymerization, and after cooling, adding a pH adjuster, an antifreeze, a thickener, and an antifoaming agent to obtain the abamectin polyurethane / polyurea microcapsule suspension. This invention, through the synergistic use of oil-soluble and water-soluble emulsifiers, ensures the stability and uniformity of the shear emulsion droplets, avoiding uneven droplet size or agglomeration during polymerization. Furthermore, the addition of a protective colloid in the aqueous phase promotes uniform and dense interfacial polymerization on the oil droplet surface, preventing the hydrolysis side reaction of the polyisocyanate. Specifically, emulsifiers, at the initial stage of emulsion formation, help form a stable initial emulsion by reducing interfacial tension and rapidly adsorbing onto the interface to form the first barrier (electrostatic repulsion or steric hindrance). Their molecular size is relatively small, and their action is rapid and effective. Protective colloids, on the other hand, have larger molecular sizes and thicker adsorption films. Through strong steric hindrance effects and / or increased viscosity of the continuous phase, they provide long-term physical stability, effectively preventing long-term droplet flocculation, aggregation, and gravitational separation, and avoiding the side reactions of polyisocyanate hydrolysis.

[0017] The polyurethane / polyurea microcapsules containing abamectin obtained in this invention have highly dense capsule walls, effectively isolating abamectin from external light, heat, and air, significantly slowing its decomposition rate and extending the product's shelf life. Furthermore, the dense microcapsule structure allows for the slow release of abamectin onto the target crop, prolonging the duration of efficacy, reducing the frequency and dosage of application, and significantly reducing the acute toxicity of the active ingredient abamectin to non-target organisms (such as aquatic organisms), thus improving the formulation's biosafety and environmental friendliness.

[0018] This invention uses interfacial polymerization to prepare abamectin polyurethane / polyurea microcapsule suspensions. The operation is simple, the process is mature, the process parameters (such as shear rate and reaction temperature) are easy to control, the repeatability is good, and it is suitable for industrial production. The resulting microcapsule suspensions have a uniform particle size distribution (average particle size 2~10μm), good storage stability (heat resistant storage, not easy to settle or clump), and good suspension rate and dispersibility. Attached Figure Description

[0019] Figure 1 This is a SEM image of the 5% abamectin polyurea microcapsule suspension obtained in Example 1. Detailed Implementation

[0020] This invention provides a method for preparing an abamectin-based polyurethane / polyurea microcapsule suspension, comprising the following steps: The technical grade abamectin, polyisocyanate, oil-soluble emulsifier, and organic solvent are mixed to obtain the oil phase; A water-soluble emulsifier, dispersant, protective colloid, monomer, and water are mixed to obtain an aqueous phase, wherein the monomer includes polyols or polyamines; The oil phase is added to the aqueous phase and shear emulsification is performed to obtain an O / W type emulsion. The O / W type emulsion was subjected to interfacial polymerization, and after cooling, a pH adjuster, antifreeze, thickener and defoamer were added to obtain an abamectin polyurethane / polyurea microcapsule suspension.

[0021] Unless otherwise specified, all raw materials used in this invention are commercially available.

[0022] The preferred amount of raw materials used in the preparation process, based on mass percentage, is: The technical grade of abamectin is 1-10%, more preferably 2-8%, and even more preferably 5%; The organic solvent is 5-20%, more preferably 8-18%, and even more preferably 10-15%; The polyisocyanate content is 1-8%, more preferably 2-6%, and even more preferably 3-5%; The polyol or polyamine is 0.5-5%, more preferably 1-4%, and even more preferably 2-3%; The oil-soluble emulsifier is 1-5%, more preferably 1-4%, and even more preferably 2-3%; The water-soluble emulsifier is 1-5%, more preferably 1-4%, and even more preferably 2-3%; The dispersant is 1-5%, more preferably 2-4%, and even more preferably 3%; The protective colloid content is 0.1-2%, more preferably 0.5-1.5%, and even more preferably 1%. The pH adjuster is 0.05-0.5%, more preferably 0.1-0.4%, and even more preferably 0.2-0.3%; The antifreeze is 1-8%, more preferably 3-7%, and even more preferably 4-6%; The thickener is 0.1-1.5%, more preferably 0.2-1.2%, and even more preferably 0.5-1%. The defoamer is used at a concentration of 0.05-0.5%, more preferably 0.1-0.4%, and even more preferably 0.2-0.3%. Deionized water balance.

[0023] This invention, by controlling the amount of the above raw materials, enables the prepared abamectin polyurethane / polyurea microcapsules to have highly dense capsule walls, effectively isolating abamectin from external light, heat, and air, significantly slowing its decomposition rate and extending the product's shelf life. Furthermore, the dense microcapsule structure allows for the slow release of abamectin onto the target crop, prolonging the duration of efficacy, reducing the frequency and dosage of application, and significantly reducing the acute toxicity of the active ingredient abamectin to non-target organisms (such as aquatic organisms), thus improving the biosafety and environmental friendliness of the formulation.

[0024] This invention involves mixing abamectin technical, a polyisocyanate, an oil-soluble emulsifier, and an organic solvent to obtain an oil phase. Preferably, the purity of the abamectin technical is ≥95%. Preferably, the polyisocyanate is selected from one or more of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymethylene polyphenyl polyisocyanate (PAPI), isophorone diisocyanate (IPDI), and hexamethylene diisocyanate (HDI).

[0025] In this invention, the oil-soluble emulsifier preferably includes one or more of sorbitan monooleate and castor oil polyoxyethylene ether. In this invention, the sorbitan monooleate is preferably a Span series emulsifier, more preferably Span-80; the castor oil polyoxyethylene ether is preferably an EL series emulsifier.

[0026] In this invention, the organic solvent preferably includes one or more of aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, vegetable oils, and methylated vegetable oils. The aromatic hydrocarbon solvent preferably includes solvent oils S-150 and / or S-180. The aliphatic hydrocarbon solvent is preferably mineral oil, white oil, isoparaffinic solvents, or dearomatized solvent oils. The vegetable oil preferably includes soybean oil and / or corn oil. This invention does not impose special requirements on the mixing method; any mixing method well-known in the art can be used, such as stirring.

[0027] This invention mixes a water-soluble emulsifier, a dispersant, a protective colloid, a monomer, and water to obtain an aqueous phase. In this invention, the water-soluble emulsifier preferably includes one or more of sodium dodecyl sulfate, lignin sulfonate, and alkylphenol polyoxyethylene ether, and the alkylphenol polyoxyethylene ether includes OP series emulsifiers and / or TX series emulsifiers. In this invention, the monomer includes a polyol or a polyamine, the polyol preferably including one or more of ethylene glycol, propylene glycol, and butanediol; the polyamine includes one or more of ethylenediamine, hexamethylenediamine, diethylenetriamine, and triethanolamine. In this invention, the water is preferably deionized water; the amount of water used is preferably 40-70% of the total water volume, more preferably 50-60%.

[0028] In this invention, the dispersant preferably comprises one or more of polycarboxylate, naphthalene sulfonate formaldehyde condensate, and lignin sulfonate; the protective colloid comprises one or more of gelatin, gum arabic, polyvinyl alcohol, guar gum, hydroxypropyl guar gum, sodium carboxymethyl cellulose, sodium alginate, and polyvinylpyrrolidone. Preferably, the water-soluble emulsifier, dispersant, and protective colloid are first dissolved in water, and then a polyol or polyamine is added.

[0029] The present invention does not have any special requirements on the preparation order of the oil phase and the aqueous phase.

[0030] In this invention, the oil phase is added to the aqueous phase and shear emulsified to obtain an O / W type emulsion. In this invention, the shear emulsification rate is preferably 5000~15000 rpm, more preferably 8000~12000 rpm, even more preferably 12000 rpm, and the time is preferably 10~30 min, more preferably 20 min.

[0031] After obtaining the O / W emulsion, the present invention subjectes the O / W emulsion to interfacial polymerization. After cooling, a pH adjuster, antifreeze, thickener, and defoamer are added to obtain an abamectin polyurethane / polyurea microcapsule suspension. In the present invention, the interfacial polymerization reaction is preferably carried out in a reactor, the temperature of the interfacial polymerization reaction is preferably 40~80℃, more preferably 50~60℃, and the time is preferably 2~5h, more preferably 3~4h. In the present invention, the interfacial polymerization reaction is preferably carried out under stirring conditions, the stirring rate is preferably 200~1000rpm, more preferably 300~500rpm.

[0032] In this invention, the pH adjuster preferably includes one or more of citric acid, sodium citrate, sodium bicarbonate, sodium carbonate, disodium hydrogen phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, acetic acid, sodium acetate, lactic acid, triethanolamine, and isopropanolamine. Preferably, the pH adjuster is used to adjust the pH of the system to 6.5-7.0. In this invention, the antifreeze preferably includes ethylene glycol and / or propylene glycol; the thickener preferably includes one or more of xanthan gum, magnesium aluminum silicate, and hydroxyethyl cellulose; and the defoamer is an organosilicone defoamer.

[0033] After adding the pH adjuster, antifreeze, thickener and defoamer, the present invention preferably makes the water content 100%.

[0034] This invention provides an abamectin-polyurethane / polyurea microcapsule suspension prepared by the above-described method, comprising a capsule wall and a core, wherein the capsule wall is composed of polyurethane and / or polyurea, and the core comprises abamectin. In this invention, the particle size of the abamectin-polyurethane / polyurea microcapsules is preferably 2-10 μm, more preferably 4-8 μm.

[0035] This invention provides the application of the above-mentioned abamectin polyurethane / polyurea microcapsule suspension in insecticides. In this invention, the insecticide is preferably an insecticide for lepidopteran pests.

[0036] The following detailed description, in conjunction with embodiments, illustrates the abamectin polyurethane / polyurea microcapsule suspension, its preparation method, and its applications provided by the present invention. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0037] Example 1: Preparation of 5% Abamectin-Polyurea Microcapsule Suspension (1) Preparation of oil phase: Weigh 5.3g of abamectin technical material (content 95%, 5g pure), add it to a composite solvent composed of 15g solvent oil S-150 and 5g soybean oil, stir to dissolve it completely, then add 4g polymethylene polyphenyl polyisocyanate (PAPI) and 2g sorbitan monooleate (Span-80), stir evenly to obtain oil phase.

[0038] (2) Preparation of aqueous phase: Add 3g alkylphenol polyoxyethylene ether (TX-10) (as a water-soluble emulsifier), 2g polycarboxylate dispersant and 0.5g gelatin (as a protective colloid) to 60g deionized water and stir to dissolve. Then add 2g ethylenediamine and stir evenly to obtain the aqueous phase.

[0039] (3) Pre-emulsification: Under a high-speed shearing machine at 10,000 rpm, the oil phase obtained in step (1) is slowly added dropwise to the aqueous phase obtained in step (2), and shearing is continued for 15 minutes to form a uniform oil-in-water emulsion.

[0040] (4) Interfacial polymerization: The above emulsion was transferred to a reactor, heated to 60°C, and stirred at 300 rpm for 3 hours. After the reaction was completed, it was allowed to cool naturally to room temperature. 0.1 g citric acid was added to adjust the pH to 6.5, 5 g ethylene glycol (as an antifreeze), 0.3 g xanthan gum (as a thickener), and 0.1 g silicone defoamer were added sequentially. The remaining deionized water was added to bring the total volume to 100 g. The mixture was stirred evenly to obtain a 5% emamectin benzoate polyurea microcapsule suspension.

[0041] The SEM image of the obtained 5% abamectin polyurea microcapsule suspension is shown below. Figure 1 As shown. By Figure 1 It can be seen that the obtained 5% emamectin benzoate polyurea microcapsule suspension has a dense capsule wall and a particle size of about 3~5 μm.

[0042] Example 2: Preparation of 2% Emamectin benzoate polyurea microcapsule suspension (1) Preparation of oil phase: Weigh 2.1g of abamectin technical grade (content 95%, 2g pure) and dissolve it in 10g of solvent oil S-180. Add 2g of toluene diisocyanate (TDI) and 1.5g of castor oil polyoxyethylene ether (EL-40), stir evenly to obtain the oil phase.

[0043] (2) Preparation of aqueous phase: Add 2.5g sodium dodecyl sulfate, 1.5g naphthalene sulfonate formaldehyde condensate and 0.2g polyvinyl alcohol to 70g deionized water, then add 1g hexamethylenediamine and stir evenly to obtain aqueous phase.

[0044] (3) Pre-emulsification: Under high-speed shearing at 8000 rpm, the oil phase is added to the water phase and sheared continuously for 20 minutes.

[0045] (4) Interfacial polymerization: The emulsion was stirred at 300 rpm for 4 hours at 55°C. After the reaction was completed, it was cooled to room temperature. The pH was adjusted to 7.0 with 0.1g sodium bicarbonate. 3g propylene glycol, 0.2g magnesium aluminum silicate, and 0.1g defoamer were added. The remaining water was added to 100g and stirred evenly to obtain 2% emamectin benzoate polyurea microcapsule suspension.

[0046] Example 3: Preparation of 10% Emamectin benzoate polyurea microcapsule suspension (1) Oil phase preparation: Weigh 10.5g of abamectin technical material (content 95%, 10g pure), dissolve it in 20g of methylated soybean oil, add 8g of diphenylmethane diisocyanate (MDI) and 4g of Span-80.

[0047] (2) Aqueous phase preparation: Add 5g TX-10, 3g lignin sulfonate and 1g gum arabic to 40g deionized water, and then add 4g diethylenetriamine.

[0048] (3) Pre-emulsification: Under high-speed shearing conditions of 12,000 rpm, the oil phase is added to the water phase and sheared continuously for 10 minutes.

[0049] (4) Interfacial polymerization: The emulsion was stirred at 300 rpm for 2.5 h at 65 °C. After the reaction was completed, it was cooled to room temperature. The pH was adjusted to 6.8 with 0.2 g disodium hydrogen phosphate. 8 g ethylene glycol, 0.8 g xanthan gum, and 0.2 g defoamer were added. The remaining water was added to 100 g and stirred evenly to obtain the 10% emamectin benzoate polyurea microcapsule suspension.

[0050] Example 4 Variations in the composition of individual wall materials: The basic formulation is the same as in Example 1, except that the polyisocyanate is replaced with a mixture of 2g PAPI and 2g TDI, and the polyamine is replaced with a mixture of 1g ethylenediamine and 1g triethanolamine. The remaining steps remain unchanged.

[0051] Example 5 Changes in the solvent system: The basic formula is the same as in Example 2, except that the organic solvent is replaced with 10g of corn oil, and the other steps remain unchanged.

[0052] Example 6 Changes in the emulsifier system: The basic formulation is the same as in Example 3, except that the oil-soluble emulsifier is replaced with 4g of EL-20, and the water-soluble emulsifier is replaced with a mixture of 2.5g of lignin sulfonate and 2.5g of OP-10. The remaining steps remain unchanged.

[0053] Example 7 Changes in protective colloids: The basic formula is the same as in Example 1, except that the protective colloid of 0.5g gelatin is replaced with 0.5g xanthan gum. The remaining steps remain unchanged.

[0054] Example 8 Changes in reaction temperature: The basic formulation is the same as in Example 2, except that the interfacial polymerization reaction temperature is changed from 55°C to 70°C. The remaining steps remain unchanged.

[0055] Example 9 Changes in reaction time: The basic formulation is the same as in Example 3, except that the interfacial polymerization reaction time is extended from 2.5 h to 5 h. The remaining steps remain unchanged.

[0056] Example 10 Changes in the thickener system: The basic formula is the same as in Example 1, except that the thickener 0.3g xanthan gum is replaced with a complex of 0.2g xanthan gum and 0.15g magnesium aluminum silicate. The remaining steps remain unchanged.

[0057] Example 11 Examples using polyol monomers: This embodiment uses polyol monomers for preparation, and the specific steps are as follows: (1) Preparation of oil phase: Weigh 5g of abamectin technical grade (content 95%, purity 4.75g), add 20g of solvent oil S-150, and stir until completely dissolved. Then add 3g of isophorone diisocyanate (IPDI) and 2g of castor oil polyoxyethylene ether (EL-40), stir evenly to obtain the oil phase.

[0058] (2) Preparation of aqueous phase: Add 2g sodium dodecyl sulfate (SDS), 2g polycarboxylate dispersant and 0.5g gelatin (as a protective colloid) to 50g deionized water and stir to dissolve. Then add 3g propylene glycol and stir evenly to obtain the aqueous phase.

[0059] (3) Pre-emulsification: Under a high-speed shearing machine at 10,000 rpm, the oil phase obtained in step 1 is slowly added dropwise to the aqueous phase obtained in step 2, and shearing is continued for 20 minutes to form a uniform oil-in-water emulsion.

[0060] (4) Interfacial polymerization: The emulsion was transferred to a reactor, heated to 55°C, and stirred at 300 rpm for 4 hours. After the reaction was completed, it was allowed to cool naturally to room temperature. 0.1 g of citric acid was added to adjust the pH to 6.5, 5 g of propylene glycol was added as an antifreeze, and deionized water was added to bring the total volume to 100 g. The mixture was stirred evenly to obtain a 5% abamectin polyurethane microcapsule suspension.

[0061] Comparative Example 1 The compound emulsifier used in Example 1 was replaced with a single emulsifier, specifically: Oil phase preparation: Change to oil phase without using emulsifier.

[0062] Aqueous phase preparation: 3g of water-soluble emulsifier alkylphenol polyoxyethylene ether (TX-10).

[0063] Effect Analysis: The difference in effect between using a single emulsifier and a compound emulsifier is mainly reflected in the following aspects: Poor emulsion stability: Compound emulsifiers provide stronger stability during emulsification through synergistic effects, preventing droplet aggregation and uneven distribution. Single emulsifiers are relatively weaker and more prone to causing uneven droplet distribution or agglomeration.

[0064] Uneven particle size distribution: Compound emulsifiers help form a more uniform emulsion with a narrower particle size distribution and better particle size consistency. A single emulsifier may lead to larger differences in particle size distribution, affecting the quality of microcapsules.

[0065] Comparative Example 2 The 0.5g of gelatin used in Example 1 (as a protective colloid) is omitted. The remaining steps remain unchanged.

[0066] Effect Analysis Protective colloids play an important role in microcapsule preparation, mainly in the following aspects: Poor emulsion stability: Protective colloids effectively increase the viscosity of the continuous phase, preventing droplet aggregation and sedimentation, thus ensuring emulsion stability. Without them, droplets are more prone to aggregation, leading to emulsion instability.

[0067] Microcapsule performance is poor: Protective colloids also provide physical protection, helping to form denser capsule walls and preventing the loss of active ingredients. Without protective colloids, the resulting microcapsule walls are poorly dense, making abamectin prone to leakage, and thus reducing efficacy.

[0068] Performance testing (1) Particle size analysis The particle size of the microcapsules obtained in Examples 1-11 and Comparative Examples 1-2 was determined using a laser particle size analyzer (such as Bettersize2600), and the results are shown in Table 1.

[0069] (2) Suspension rate test The suspension rates of the microcapsules obtained in Examples 1-11 and Comparative Examples 1-2 were determined according to GB / T 14825-2006 "Determination of Pesticide Suspension Concentrates". The results are shown in Table 1.

[0070] (3) Thermal storage stability test The microcapsules obtained in Examples 1-11 and Comparative Examples 1-2 were stored in an oven at 54±2℃ for 14 days. After being removed and brought to room temperature, the suspension rate was determined according to GB / T 14825-2006 "Determination Method of Pesticide Suspension Concentrates". The suspension rate of the microcapsules after heat storage is shown in Table 1.

[0071] The content of abamectin in the samples before and after heat storage was determined by high performance liquid chromatography (HPLC), and the thermal decomposition rate was calculated. The results are shown in Table 1.

[0072] Table 1 Performance test results of the examples and comparative examples

[0073] Particle size analysis results showed that the particle sizes of the products obtained in Examples 1-11 of this invention were all within the range of 3.6-6.2 μm, and the particle size distribution (Span value) was all less than 1.5, exhibiting a unimodal distribution, indicating uniform particle size. The suspension rates of the products obtained in the examples before and after heat storage were all ≥90%, and the samples from each example showed uniform appearance after heat storage, without clumping or stratification. This demonstrates that the microcapsules obtained by this invention have good suspension rate, dispersibility, and heat storage stability.

[0074] The thermal decomposition results show that the dense polyurethane / polyurea capsule wall formed by the present invention has an excellent protective effect on emamectin benzoate and significantly improves its thermal stability.

[0075] (4) Controlled release performance test A precise amount (equivalent to 5 mg of abamectin) of microcapsule suspension sample was weighed and placed in an Erlenmeyer flask containing 100 mL of deionized water (pH 7.0). Release was initiated under constant temperature shaking at 25 °C and 100 rpm. Samples were taken at set time points (e.g., 1 h, 6 h, 12 h, 24 h, 48 h, and 72 h), filtered through a 0.22 μm filter membrane, and the concentration of abamectin in the filtrate was determined by HPLC. The cumulative release rate was calculated.

[0076] Tests showed that the products of Examples 1-3 all exhibited significant sustained-release characteristics. The cumulative release rate of Example 1 was approximately 38.5% after 24 hours and approximately 86.2% after 72 hours, confirming the controlled-release effect of the microcapsules. The cumulative release rates of Example 1 at different temperatures and times are shown in Table 2.

[0077] Table 2. Cumulative release rate (%) of Example 1 at different temperatures and times

[0078] As shown in Table 2, at the same time point, the cumulative release rate of abamectin increases with increasing temperature: for example, at 72 h, the cumulative release rates at 15℃, 25℃, and 35℃ are approximately 78.0%, 86.2%, and 93.4%, respectively. This indicates that the microcapsule system of the present invention has typical temperature-sensitive diffusion-controlled release characteristics. With increasing temperature, the movement of polyurethane / polyurea network segments in the capsule wall intensifies, increasing the effective diffusion coefficient of the microporous channels, thereby accelerating the migration rate of abamectin to the external aqueous phase. In Example 1, the cumulative release rate-time curves at different temperatures show a generally slow upward trend, with the highest cumulative release rate still below 100% within 72 h, indicating that the microcapsules of the present invention have significant sustained-release behavior, capable of continuously releasing abamectin over a longer period, which is beneficial for prolonging the duration of efficacy and reducing the number of administrations.

[0079] (5) Biosafety testing Referring to the OECD 203 guidelines for acute toxicity testing of fish, zebrafish were used as the test organism to determine the 96-h median lethal concentration (LC50) of Example 1 (5% abamectin microcapsule suspension) and an equivalent concentration of abamectin technical material (prepared as an emulsifiable concentrate). 50 ).

[0080] Tests showed that emamectin benzoate technical grade (emulsifiable concentrate) had a 96-h-LC50 effect on zebrafish. 50 The value was 0.05 mg / L. The 96h-LC-L of the microcapsule suspension in Example 1 for zebrafish... 50 The value was 1.5 mg / L. The results showed that the LC50 of the microcapsule formulation was... 50 The value was significantly higher than that of the technical grade abamectin, indicating that microencapsulation significantly reduced the acute toxicity of abamectin to aquatic organisms.

[0081] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A process for the preparation of emamectin benzoate polyurethane / polyurea microcapsule suspension formulation, characterized by, The preparation process comprises the following steps: Mixing emamectin benzoate, polyisocyanate, oil-soluble emulsifier and organic solvent to obtain oil phase; Mixing water-soluble emulsifier, dispersant, protective colloid, monomer and water to obtain water phase, wherein the monomer comprises polyol or polyamine; Adding the oil phase into the water phase and performing shear emulsification to obtain O / W emulsion; Performing interfacial polymerization on the O / W emulsion, and adding pH regulator, antifreezing agent, thickening agent and defoaming agent after cooling to obtain emamectin benzoate polyurethane / polyurea microcapsule suspension.

2. The production method according to claim 1, characterized by, The amounts of raw materials used in the preparation process are as follows in terms of mass percentage: Emamectin benzoate 1-10%; Organic solvent 5-20%; Polyisocyanate 1-8%; Polyol or polyamine 0.5-5%; Oil-soluble emulsifier 1-5%; Water-soluble emulsifier 1-5%; Dispersant 1-5%; Protective colloid 0.1-2%; pH regulator 0.05-0.5%; Antifreezing agent 1-8%; Thickening agent 0.1-1.5%; Defoaming agent 0.05-0.5%; Deionized water balance.

3. The production method according to claim 1 or 2, characterized by, The polyisocyanate is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, isophorone diisocyanate and hexamethylene diisocyanate; The polyol comprises one or more of ethylene glycol, propylene glycol and butylene glycol; The polyamine comprises one or more of ethylenediamine, hexamethylenediamine, diethylenetriamine and triethanolamine.

4. The production method according to claim 1 or 2, characterized by, The oil-soluble emulsifier comprises one or more of sorbitan monooleate and castor oil polyoxyethylene ether; The water-soluble emulsifier comprises one or more of sodium dodecyl sulfate, lignosulfonate and alkylphenol polyoxyethylene ether.

5. The production method according to claim 1 or 2, characterized by, The dispersant comprises one or more of polycarboxylate, naphthalenesulfonate formaldehyde condensate and lignosulfonate; The protective colloid comprises one or more of gelatin, gum arabic, polyvinyl alcohol, guar gum, hydroxypropyl guar gum, sodium carboxymethyl cellulose, sodium alginate and polyvinylpyrrolidone.

6. The production method according to claim 1 or 2, characterized by, The pH regulator comprises one or more of citric acid, sodium citrate, sodium bicarbonate, sodium carbonate, disodium hydrogen phosphate, potassium dihydrogen phosphate, potassium hydrogen phosphate, acetic acid, sodium acetate, lactic acid, triethanolamine and isopropyl alcoholamine; The antifreezing agent comprises ethylene glycol and / or propylene glycol; The thickening agent comprises one or more of xanthan gum, magnesium aluminum silicate and hydroxyethyl cellulose; The defoaming agent is silicone defoaming agent.

7. The preparation method according to claim 1, characterized in that, The shear emulsification is performed at a rate of 5000-15000 rpm for 10-30 min; The interfacial polymerization is performed at a temperature of 40-80℃ for 2-5 h.

8. The emsulphocid polyurethane / polyurea microcapsule SC prepared by the method of any one of claims 1 to 7, characterized in that, The microcapsule comprises capsule wall and capsule core, wherein the capsule wall comprises polyurethane and / or polyurea, and the capsule core comprises emamectin benzoate.

9. The emamectin benzoate polyurethane / polyurea microcapsule suspension according to claim 8, characterized in that, The particle size of the emamectin benzoate polyurethane / polyurea microcapsule is 2-10 μm.

10. Application of the emamectin benzoate polyurethane / polyurea microcapsule suspension of claim 8 or 9 in insecticide.

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