A microcapsule suspension-suspension containing thiazol phosphate and fluazamide and a preparation method thereof

Abstract

The application relates to the field of pesticide compounding, and specifically discloses a microcapsule suspension-suspension agent containing thiazol phosphorus and fluazacylamide and a preparation method thereof. The preparation method of the microcapsule suspension-suspension agent containing thiazol phosphorus and fluazacylamide comprises the following steps: S1. thiazol phosphorus microcapsule suspension agent preparation; S2. fluazacylamide suspension agent preparation; and S3. compounding: in the finally obtained microcapsule suspension-suspension agent, the thiazol phosphorus content is 6-7 wt%, and the fluazacylamide content is 12-18 wt%. The preparation method breaks through the technical bottleneck that the two components have poor compatibility, the microcapsule is easy to break, and the suspension phase is easy to stratify in the preparation of the existing CS-SC dosage form. Compared with common microcapsule suspensions and suspensions, the method has obvious advantages, the preparation process is simple and controllable, raw materials are easy to obtain, special high-end equipment is not needed, the preparation has a long effective period, the prevention and control effect is excellent, agricultural production efficiency is significantly improved, and planting cost is reduced.

Description

Technical Field

[0001] This application relates to the technical field of pesticide compound formulation, and in particular to a microcapsule suspension-suspension agent containing thiamethoxam and fluopyram and its preparation method. Background Technology

[0002] In modern agricultural production, the synergistic damage caused by root-knot nematode disease and soil-borne fungal diseases has become a core bottleneck restricting high-quality and high-yield crops. When the two occur together, it can lead to root rot, weakened growth, sharp reduction in yield, or even crop failure.

[0003] Thiazophos, as a highly effective organophosphate nematicide, has strong systemic activity and a broad nematicidal spectrum, rapidly killing root-knot nematodes in the soil. However, this agent is highly volatile and easily degraded by microorganisms in the soil, resulting in a short residual effect. This not only reduces the utilization rate of the pesticide but also easily causes soil and water pollution. Long-term use alone can easily induce nematodes to develop resistance. Fluopyram, a pyrazole amide fungicide, has a unique fungicidal mechanism and excellent control effect on soil-borne fungi such as Fusarium and Pythium, with both protective and curative effects. However, it has poor water solubility and weak mobility in the soil, making it difficult to reach the deep roots of crops to exert its efficacy. Furthermore, its thermal stability is generally poor. When mixed with thiazophos, the two have significant differences in polarity and poor compatibility, easily leading to problems such as stratification, precipitation, and degradation of the active ingredient.

[0004] Microencapsulated suspension-suspension formulation (CS-SC) is a novel composite dosage form that combines the advantages of sustained release, controlled release, and reduced volatility of microencapsulated suspensions (CS) with the uniform dispersion and rapid onset of action of suspensions (SC). By microencapsulating one active ingredient and suspending the other, the two components complement each other. Microencapsulation controls the release rate of volatile components and prolongs the duration of action, while suspension allows the other component to disperse and take effect quickly. This perfectly matches the physicochemical properties and synergistic control requirements of thiamethoxam and fluopyram. However, existing compound formulations of thiamethoxam and fluopyram are mostly single microencapsulated suspensions or suspensions, failing to fully utilize the advantages of the CS-SC formulation and thus unable to achieve the dual goals of "rapid onset of action" and "long-lasting control."

[0005] Although some technicians have tried to prepare CS-SC formulations of thiamethoxam and fluopyram, there are still some technical defects. In particular, the capsule wall material used for microencapsulation has low strength and poor sealing performance, and is easily damaged by the adjuvants in the suspension phase, resulting in the volatilization and leakage of thiamethoxam. The dispersant used in the suspension phase cannot meet the dispersion requirements of fluopyram, resulting in its easy crystallization and precipitation. Summary of the Invention

[0006] To address the aforementioned technical problems, this application provides a microcapsule suspension-suspension agent containing thiamethoxam and fluopyram, and a method for preparing the same.

[0007] In a first aspect, this application provides a method for preparing a microcapsule suspension-suspension agent containing thiamethoxam and fluopyram, comprising the following steps: S1. Preparation of thiazophos microcapsule suspension: Thiazolephos is dispersed in an organic solvent, followed by the addition of isocyanate and urea-formaldehyde resin prepolymer, and stirred to form an oil phase; emulsifier, polyamine and water are mixed and homogenized to obtain an aqueous phase; the oil phase and aqueous phase are mixed and cured at pH=2-6 and temperature of 45-65℃ to obtain thiazophos microcapsule suspension, wherein the weight ratio of thiazophos, isocyanate, urea-formaldehyde resin prepolymer and polyamine is 30:(6-9):(8-12):(13-18); S2. Preparation of fluopyram suspension: Fluopyram, polycarboxylate dispersant, wetting agent and water are mixed and milled until the average particle size is ≤3μm. Then, nano-silica is added and mixed evenly to obtain fluopyram suspension. The ratio of fluopyram, polycarboxylate dispersant, wetting agent and nano-silica is 20:(2-4):(1.5-2.5):(0.3-1.0). S3. Compounding: The thiamethoxam microcapsule suspension obtained in S1 and the fluopyram suspension obtained in S2 are mixed together, and then a suspending agent is added. The pH is adjusted to 6-6.5, and the mixture is stirred and homogenized. After adding a stabilizer, a microcapsule suspension-suspension is obtained. The ratio of the thiamethoxam microcapsule suspension to the fluopyram suspension is adjusted. In the final microcapsule suspension-suspension, the thiamethoxam content is 6-7 wt% and the fluopyram content is 12-18 wt%.

[0008] Preferably, in step S3, the ratio of the amount of thiazophos microcapsule suspension and fluopyram suspension is adjusted so that the final microcapsule suspension contains 6.5 wt% thiazophos and 15 wt% fluopyram.

[0009] By adopting the above technical solution, this application first prepares thiamethoxam microcapsule suspension, and uses isocyanate and urea-formaldehyde resin prepolymer as wall material, which has good mechanical strength and the microcapsules are not easy to break. The substances in the suspension have almost no effect on the capsule wall. Therefore, the capsule wall of this application can play a good role in protecting and slowing down the release of thiamethoxam, thereby giving full play to the advantages of thiamethoxam's strong systemic conductivity, broad nematicidal spectrum, and ability to quickly kill root-knot nematodes in the soil.

[0010] Subsequently, this application mixes fluopyram with a polycarboxylate dispersant, a wetting agent, and water, then mills the mixture to a certain particle size, and adds nano-silica to obtain a fluopyram suspension with extremely high dispersion uniformity. Finally, the thiamethoxam microcapsule suspension is compounded with the fluopyram suspension, and the ratio of the thiamethoxam microcapsule suspension to the fluopyram suspension is adjusted to obtain a microcapsule suspension-suspension with a thiamethoxam content of 6-7 wt% and a fluopyram content of 12-18 wt%. The capsule wall material has high strength and good sealing performance, and is almost not damaged by the additives in the suspension phase. Therefore, thiamethoxam will hardly volatilize or leak. The polycarboxylate dispersant used in the suspension phase can meet the dispersion requirements of fluopyram, and crystallization and precipitation will hardly occur.

[0011] Preferably, in S1, the urea-formaldehyde resin prepolymer is prepared by the following method: Urea and formaldehyde are mixed in a molar ratio of 1:(1.6-2.0) and reacted at a temperature of 40-85℃ and a pH of 7-9 until the solution is clear and transparent. After cooling to room temperature, a colorless or light yellow transparent liquid is obtained, which is the urea-formaldehyde resin prepolymer solution.

[0012] Preferably, when preparing the urea-formaldehyde resin prepolymer in S1, the molar ratio of urea to formaldehyde is 1:1.8.

[0013] By adopting the above technical solution, this application controls the molar ratio of urea to formaldehyde to be 1:1.8 when preparing the urea-formaldehyde resin prepolymer in S1. At this time, the capsule wall is dense, the encapsulation rate reaches 98.89%, the particle size distribution is concentrated, the free formaldehyde content is low, and by-products are not easily generated, resulting in good emulsion stability.

[0014] Preferably, in step S1, curing is performed at pH=3 and temperature of 55°C.

[0015] By adopting the above technical solution, this application controls the pH and temperature of curing, so that the polycondensation rate is moderate, forming a wall material with high cross-linking degree and low porosity, with higher encapsulation rate and the ability to form a very stable shell; and at this temperature, the optimal polymerization kinetics can be achieved, resulting in a dense shell with high mechanical strength and improved thermal stability.

[0016] Preferably, in S1, the weight ratio of isocyanate to urea-formaldehyde resin prepolymer is 8:10.

[0017] By adopting the above technical solution, this application controls the weight ratio of isocyanate and urea-formaldehyde resin prepolymer to 8:10 in S1, which can maximize the mechanical strength of the wall material and ensure better uniformity of the thickness of the capsule wall.

[0018] Preferably, in S1, the total amount of isocyanate and urea-formaldehyde resin prepolymer is 120 wt% of the amount of polyamine.

[0019] By adopting the above technical solution, this application controls the total amount of isocyanate and urea-formaldehyde resin prepolymer to 120wt% of the amount of polyamine, which can effectively balance the reactivity and free formaldehyde, ensuring that even if 60% of NCO is lost, there is still a sufficient amount of reactants to completely combine with the polyamine. The wall material is denser, the mechanical strength is increased by 30-50%, the wall material is non-porous and has good continuity, and the barrier properties are significantly enhanced, which can offset the interference of uneven emulsification, stirring shear, temperature fluctuation, etc. The compressive strength, thermal stability and long-term storage performance of the microcapsules are all optimal.

[0020] Preferably, in step S2, the ratio of fluopyram, polycarboxylate dispersant, wetting agent and nano silica is 20:3:2:0.5.

[0021] By adopting the above technical solution, this application controls the dosage ratio of fluopyram, polycarboxylate dispersant, wetting agent and nano silica in S2 to be 20:3:2:0.5, ensuring the content of effective ingredients and avoiding viscosity runaway. The synergistic weight ratio of wetting agent and polycarboxylate dispersant can balance emulsification stability and wetting efficiency, avoiding sedimentation or splashing. Nano silica can significantly improve the thermal storage stability and mechanical strength of the suspending agent. Excessive amount can easily cause agglomeration.

[0022] Preferably, the stirring and homogenization in S3 specifically involves: first mixing and homogenizing at a speed of 500 rpm for 8-10 minutes, and then continuing to homogenize at a speed of 1500 rpm for 10 minutes.

[0023] By adopting the above technical solution, this application first performs low-speed stirring, which can gently disperse dry powder or agglomerated materials, prevent splashing or clumping at high speeds, promote the initial wetting and distribution of each component, create a uniform foundation for subsequent high shear, and reduce the introduction of air bubbles. Then, the rotation speed is increased, which generates strong hydraulic shear and turbulence at high speeds, significantly reducing the droplet or particle size (down to the micron level), improving the dispersion uniformity, preventing sedimentation or stratification, and more importantly, enhancing the interfacial encapsulation effect, which can greatly improve the stability and dispersion uniformity of microcapsule suspensions-suspension agents.

[0024] Secondly, this application also provides a microcapsule suspension prepared by the above-mentioned method for preparing microcapsule suspensions containing thiamethoxam and fluopyram.

[0025] By adopting the above technical solution, the microcapsule suspension prepared by the method of this application has a thiazophos content of 6-7 wt% and a fluopyram content of 12-18 wt%. The capsule wall material has high strength and good sealing performance, and is almost not destroyed by the additives in the suspension phase. Therefore, thiazophos will hardly volatilize and leak. The polycarboxylate dispersant selected for the suspension phase can adapt to the dispersion requirements of fluopyram, and there will be almost no crystallization or precipitation.

[0026] In summary, this application has the following beneficial technical effects: 1. The preparation method of this application breaks through the technical bottlenecks of poor compatibility between the two components, easy microcapsule rupture, and easy stratification of the suspension phase in the preparation of existing CS-SC formulations. Compared with ordinary microcapsule suspensions and suspensions, it has significant advantages. The preparation process is simple and controllable, the raw materials are readily available, no special high-end equipment is required, the cost of composite capsule wall materials and adjuvants is low, the production cost is reduced compared with similar imported composite formulations, and the formulation has a long duration of action and excellent control effect. It can reduce the number of subsequent applications and labor costs, significantly improve agricultural production efficiency, reduce planting costs, and solve the problem of environmental pollution caused by traditional formulations. It has economic, environmental and social benefits and has good prospects for promotion. 2. The microcapsule suspension-suspension agent of this application has a thiazophos content of 6-7 wt% and a fluopyram content of 12-18 wt%. The capsule wall material has high strength and good sealing performance, and is almost not destroyed by the additives in the suspension phase. Therefore, thiazophos will hardly volatilize and leak. The polycarboxylate dispersant selected for the suspension phase can meet the dispersion requirements of fluopyram, and crystallization and precipitation will hardly occur. Detailed Implementation

[0027] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0028] A method for preparing a microcapsule suspension-suspension agent containing thiamethoxam and fluopyram includes the following steps: S1. Preparation of thiazophos microcapsule suspension: Thiazolephos is dispersed in an organic solvent, followed by the addition of isocyanate and urea-formaldehyde resin prepolymer, and stirred to form an oil phase; emulsifier, polyamine and water are mixed and homogenized to obtain an aqueous phase; the oil phase and aqueous phase are mixed and cured at pH=2-6 and temperature of 45-65℃ to obtain thiazophos microcapsule suspension, wherein the weight ratio of thiazophos, isocyanate, urea-formaldehyde resin prepolymer and polyamine is 30:(6-9):(8-12):(13-18); S2. Preparation of fluopyram suspension: Fluopyram, polycarboxylate dispersant, wetting agent and water are mixed and milled until the average particle size is ≤3μm. Then, nano-silica is added and mixed evenly to obtain fluopyram suspension. The ratio of fluopyram, polycarboxylate dispersant, wetting agent and nano-silica is 20:(2-4):(1.5-2.5):(0.3-1.0). S3. Compounding: The thiamethoxam microcapsule suspension obtained in S1 and the fluopyram suspension obtained in S2 are mixed together, and then a suspending agent is added. The pH is adjusted to 6-6.5, and the mixture is stirred and homogenized. After adding a stabilizer, a microcapsule suspension-suspension is obtained. The ratio of the thiamethoxam microcapsule suspension to the fluopyram suspension is adjusted. In the final microcapsule suspension-suspension, the thiamethoxam content is 6-7 wt% and the fluopyram content is 12-18 wt%.

[0029] In a preferred embodiment of this application, in step S3, the ratio of the amount of thiazophos microcapsule suspension and fluopyram suspension is adjusted so that the final microcapsule suspension contains 6.5 wt% thiazophos and 15 wt% fluopyram.

[0030] In a preferred embodiment of this application, in S1, the urea-formaldehyde resin prepolymer is prepared by the following method: urea and formaldehyde are mixed in a molar ratio of 1:(1.6-2.0) and reacted at a temperature of 40-85℃ and a pH of 7-9 until the solution is clear and transparent. After cooling to room temperature, a colorless or light yellow transparent liquid is obtained, which is the urea-formaldehyde resin prepolymer solution.

[0031] In a preferred embodiment of this application, when preparing the urea-formaldehyde resin prepolymer in S1, the molar ratio of urea to formaldehyde is 1:1.8.

[0032] In a preferred embodiment of this application, in step S1, curing is performed at pH=3 and a temperature of 55°C.

[0033] In a preferred embodiment of this application, in S1, the weight ratio of isocyanate to urea-formaldehyde resin prepolymer is 8:10.

[0034] In a preferred embodiment of this application, in S1, the total amount of isocyanate and urea-formaldehyde resin prepolymer is 120 wt% of the amount of polyamine.

[0035] In a preferred embodiment of this application, in step S2, the ratio of fluopyram, polycarboxylate dispersant, wetting agent and nano silica is 20:3:2:0.5.

[0036] In a preferred embodiment of this application, the stirring and homogenization in S3 specifically involves: first, mixing and homogenizing at a speed of 500 rpm for 8-10 minutes, and then continuing to homogenize at a speed of 1500 rpm for 10 minutes.

[0037] <Example 1> A method for preparing a microcapsule suspension-suspension agent containing thiamethoxam and fluopyram includes the following steps: S0. Preparation of urea-formaldehyde resin prepolymer: Disperse 2 mol of formaldehyde in water until the formaldehyde concentration is 37%. Then heat the formaldehyde aqueous solution to 50°C, slowly add 1 mol of urea, stir until completely dissolved, add ammonia to adjust the pH to 7.5-8.5, raise the temperature to 85°C and keep it at that temperature for 30-60 minutes until the solution is clear and transparent. Cool to room temperature to obtain a colorless or light yellow transparent liquid, which is the urea-formaldehyde resin prepolymer solution containing 102g of urea-formaldehyde resin prepolymer. Preparation of S1. Thiazole phosphorus microcapsule suspension: 382.5g of thiazophos was dispersed in 500mL of xylene, followed by the addition of 114.75g of isocyanate and all of the urea-formaldehyde resin prepolymer solution obtained from S0, and stirred to form an oil phase; 55.25g of emulsifier alkylphenol polyoxyethylene ether, 165.75g of ethylenediamine and 200mL of water were mixed and homogenized at 12000rpm for 5min to obtain an aqueous phase; all of the oil phase and all of the aqueous phase were mixed and cured at pH=2 and 45℃ for 2h to obtain the thiazophos microcapsule suspension; S2. Preparation of fluopyram suspension: 2 kg fluopyram, 200 g polycarboxylate dispersant, 250 g alkyl naphthalene sulfonate wetting agent and 10 L water are mixed and milled until the average particle size is ≤3 μm. Then 30 g nano silica is added and mixed evenly to obtain fluopyram suspension. S3. Compounding: The thiamethoxam microcapsule suspension obtained in S1 and the fluopyram suspension obtained in S2 are mixed together. The ratio of the thiamethoxam microcapsule suspension to the fluopyram suspension is adjusted. Then, 12g of xanthan gum suspension is added, and the pH is adjusted to 6-6.5. The mixture is stirred and homogenized at 1000rpm for 20min. After adding 25g of polyvinyl alcohol stabilizer, a microcapsule suspension-suspension is obtained, in which the thiamethoxam content is 7wt% and the fluopyram content is 12wt%.

[0038] <Example 2> A method for preparing a microcapsule suspension-suspension agent containing thiamethoxam and fluopyram includes the following steps: S0. Preparation of urea-formaldehyde resin prepolymer: Disperse 1.6 mol of formaldehyde in water until the formaldehyde concentration is 37%. Then heat the formaldehyde aqueous solution to 50°C, slowly add 1 mol of urea, stir until completely dissolved, add ammonia to adjust the pH to 7.5-8.5, raise the temperature to 85°C and keep it at that temperature for 30-60 minutes until the solution is clear and transparent. Cool to room temperature to obtain a colorless or light yellow transparent liquid, which is the urea-formaldehyde resin prepolymer solution containing 96g of urea-formaldehyde resin prepolymer. Preparation of S1. Thiazole phosphorus microcapsule suspension: 240g of thiazophos was dispersed in 400mL of xylene, followed by the addition of 48g of isocyanate and all of the urea-formaldehyde resin prepolymer solution obtained from S0, and stirred to form an oil phase; 34.5g of emulsifier alkylphenol polyoxyethylene ether, 104g of ethylenediamine and 120mL of water were mixed and homogenized at 12000rpm for 5min to obtain an aqueous phase; all of the oil phase and all of the aqueous phase were mixed and cured at pH=6 and 65℃ for 2h to obtain the thiazophos microcapsule suspension; S2. Preparation of fluopyram suspension: 2 kg fluopyram, 400 g polycarboxylate dispersant, 150 g alkyl naphthalene sulfonate wetting agent and 10 L water are mixed and milled until the average particle size is ≤3 μm. Then 100 g nano silica is added and mixed evenly to obtain fluopyram suspension. S3. Compounding: The thiamethoxam microcapsule suspension obtained in S1 and the fluopyram suspension obtained in S2 are mixed together. The ratio of the thiamethoxam microcapsule suspension to the fluopyram suspension is adjusted. Then, 12g of xanthan gum suspension is added, and the pH is adjusted to 6-6.5. The mixture is stirred and homogenized at 1000rpm for 20min. After adding 25g of polyvinyl alcohol stabilizer, a microcapsule suspension-suspension is obtained, in which the thiamethoxam content is 6wt% and the fluopyram content is 18wt%.

[0039] <Example 3> A method for preparing a microcapsule suspension-suspension agent containing thiamethoxam and fluopyram includes the following steps: S0. Preparation of urea-formaldehyde resin prepolymer: Disperse 2 mol of formaldehyde in water until the formaldehyde concentration is 37%. Then heat the formaldehyde aqueous solution to 50°C, slowly add 1 mol of urea, stir until completely dissolved, add ammonia to adjust the pH to 7.5-8.5, raise the temperature to 85°C and keep it at that temperature for 30-60 minutes until the solution is clear and transparent. Cool to room temperature to obtain a colorless or light yellow transparent liquid, which is the urea-formaldehyde resin prepolymer solution containing 102g of urea-formaldehyde resin prepolymer. Preparation of S1. Thiazole phosphorus microcapsule suspension: 382.5g of thiazophos was dispersed in 500mL of xylene, followed by the addition of 114.75g of isocyanate and all of the urea-formaldehyde resin prepolymer solution obtained from S0, and stirred to form an oil phase; 55.25g of emulsifier alkylphenol polyoxyethylene ether, 165.75g of ethylenediamine and 200mL of water were mixed and homogenized at 12000rpm for 5min to obtain an aqueous phase; all of the oil phase and all of the aqueous phase were mixed and cured at pH=2 and 45℃ for 2h to obtain the thiazophos microcapsule suspension; S2. Preparation of fluopyram suspension: 2 kg fluopyram, 200 g polycarboxylate dispersant, 250 g alkyl naphthalene sulfonate wetting agent and 10 L water are mixed and milled until the average particle size is ≤3 μm. Then 30 g nano silica is added and mixed evenly to obtain fluopyram suspension. S3. Compounding: The thiamethoxam microcapsule suspension obtained in S1 and the fluopyram suspension obtained in S2 are mixed together. The ratio of the thiamethoxam microcapsule suspension to the fluopyram suspension is adjusted. Then, 12g of xanthan gum suspension is added, and the pH is adjusted to 6-6.5. The mixture is stirred and homogenized at 1000rpm for 20min. After adding 25g of polyvinyl alcohol stabilizer, a microcapsule suspension-suspension is obtained, in which the thiamethoxam content is 6.5wt% and the fluopyram content is 15wt%.

[0040] <Example 4> A method for preparing a microcapsule suspension containing thiazophos and fluopyram differs from Example 3 in that, in S0, the amount of formaldehyde is adjusted to 1.8 mol, and the resulting urea-formaldehyde resin prepolymer solution contains 99.6 g of urea-formaldehyde resin prepolymer; in S1, 373.5 g of thiazophos is dispersed in 500 mL of xylene, followed by the addition of 112.05 g of isocyanate and all the urea-formaldehyde resin prepolymer solution obtained in S0, and stirred to form an oil phase; 54 g of emulsifier alkylphenol polyoxyethylene ether, 161.85 g of ethylenediamine and 200 mL of water are mixed and homogenized at 12000 rpm for 5 min to obtain an aqueous phase; all the oil phase and all the aqueous phase are mixed and cured at pH=2 and 45℃ for 2 h to obtain the thiazophos microcapsule suspension; the rest is the same as in Example 3.

[0041] <Example 5> A method for preparing a microcapsule suspension containing thiazophos and fluopyram is different from that in Example 4, in S1, the microcapsule suspension is cured for 2 hours at pH=3 and temperature of 55°C to obtain the thiazophos microcapsule suspension. The rest is the same as in Example 4.

[0042] <Example 6> A method for preparing a microcapsule suspension containing thiazophos and fluopyram is different from that in Example 4, in S1, the microcapsule suspension is cured for 2 hours at pH 5 and temperature 62°C to obtain the thiazophos microcapsule suspension. The rest is the same as in Example 4.

[0043] <Example 7> A method for preparing a microcapsule suspension-suspension agent containing thiamethoxam and fluopyram includes the following steps: S0. Preparation of urea-formaldehyde resin prepolymer: Disperse 1.8 mol of formaldehyde in water until the formaldehyde concentration is 37%. Then heat the formaldehyde aqueous solution to 50°C, slowly add 1 mol of urea, stir until completely dissolved, add ammonia to adjust the pH to 7.5-8.5, raise the temperature to 85°C and keep the reaction at this temperature for 30-60 minutes until the solution is clear and transparent. Cool to room temperature to obtain a colorless or light yellow transparent liquid, which is the urea-formaldehyde resin prepolymer solution containing 99.6 g of urea-formaldehyde resin prepolymer. Preparation of S1. Thiazole phosphorus microcapsule suspension: 298.8 g of thiazophos was dispersed in 500 mL of xylene, followed by the addition of 79.68 g of isocyanate and all of the urea-formaldehyde resin prepolymer solution obtained from S0, and stirred to form an oil phase; 49.8 g of emulsifier alkylphenol polyoxyethylene ether, 149.4 g of ethylenediamine and 200 mL of water were mixed and homogenized at 12000 rpm for 5 min to obtain an aqueous phase; all of the oil phase and all of the aqueous phase were mixed and cured at pH=3 and 55℃ for 2 h to obtain the thiazophos microcapsule suspension; S2. Preparation of fluopyram suspension: 2 kg fluopyram, 200 g polycarboxylate dispersant, 250 g alkyl naphthalene sulfonate wetting agent and 10 L water are mixed and milled until the average particle size is ≤3 μm. Then 30 g nano silica is added and mixed evenly to obtain fluopyram suspension. S3. Compounding: The thiamethoxam microcapsule suspension obtained in S1 and the fluopyram suspension obtained in S2 are mixed together. The ratio of the thiamethoxam microcapsule suspension to the fluopyram suspension is adjusted. Then, 12g of xanthan gum suspension is added, and the pH is adjusted to 6-6.5. The mixture is stirred and homogenized at 1000rpm for 20min. After adding 25g of polyvinyl alcohol stabilizer, a microcapsule suspension-suspension is obtained, in which the thiamethoxam content is 6.5wt% and the fluopyram content is 15wt%.

[0044] <Example 8> A method for preparing a microcapsule suspension containing thiazophos and fluopyram differs from Example 3 in that, in step S2, 2 kg of fluopyram, 300 g of polycarboxylate dispersant, 200 g of alkyl naphthalene sulfonate wetting agent and 10 L of water are mixed, milled until the average particle size is ≤3 μm, and then 50 g of nano silica is added. After mixing evenly, the fluopyram suspension is obtained. The rest is the same as in Example 3.

[0045] <Example 9> A method for preparing a microcapsule suspension-suspension agent containing thiamethoxam and fluopyram, differing from Example 3 in that S3 specifically involves: The thiamethoxam microcapsule suspension obtained in S1 and the fluopyram suspension obtained in S2 were blended together. The ratio of the thiamethoxam microcapsule suspension to the fluopyram suspension was adjusted, and 12g of xanthan gum suspension was added. The pH was adjusted to 6-6.5. The mixture was first homogenized at 500 rpm for 10 min, and then homogenized again at 1500 rpm for 10 min. After adding 25g of polyvinyl alcohol stabilizer, the microcapsule suspension was obtained. The rest was the same as in Example 3.

[0046] <Example 10> A method for preparing a microcapsule suspension-suspension agent containing thiamethoxam and fluopyram, differing from Example 3 in that S3 specifically involves: The thiamethoxam microcapsule suspension obtained in S1 and the fluopyram suspension obtained in S2 were blended together. The ratio of the thiamethoxam microcapsule suspension to the fluopyram suspension was adjusted, and 12g of xanthan gum suspension was added. The pH was adjusted to 6-6.5. The mixture was first homogenized at 500 rpm for 8 min, and then homogenized again at 1500 rpm for 10 min. After adding 25g of polyvinyl alcohol stabilizer, the microcapsule suspension was obtained. The rest was the same as in Example 3.

[0047] <Comparative Example 1> The difference from Example 3 is that S0 is removed. Specifically, in S1, 382.5g of thiazophos is dispersed in 500mL of xylene, followed by the addition of 216.75g of isocyanate, and stirred to form an oil phase; 55.25g of emulsifier alkylphenol polyoxyethylene ether, 165.75g of ethylenediamine and 200mL of water are mixed and homogenized at 12000rpm for 5min to obtain an aqueous phase; all the oil phase and all the aqueous phase are mixed and cured at pH=2 and 45℃ for 2h to obtain thiazophos microcapsule suspension. The remaining steps S2 and S3 are the same as in Example 3.

[0048] <Comparative Example 2> Includes the following steps: S0. Preparation of urea-formaldehyde resin prepolymer: Disperse 4 mol of formaldehyde in water until the formaldehyde concentration is 37%. Then heat the formaldehyde aqueous solution to 50°C, slowly add 2 mol of urea, stir until completely dissolved, add ammonia to adjust the pH to 7.5-8.5, raise the temperature to 85°C and keep it at that temperature for 30-60 minutes until the solution is clear and transparent. Cool to room temperature to obtain a colorless or light yellow transparent liquid, which is the urea-formaldehyde resin prepolymer solution containing 205g of urea-formaldehyde resin prepolymer. Preparation of S1. Thiazole phosphorus microcapsule suspension: 382.5g of thiazophos was dispersed in 500mL of xylene, and then all the urea-formaldehyde resin prepolymer solution obtained from S0 was added and stirred to form an oil phase; 55.25g of emulsifier alkylphenol polyoxyethylene ether, 165.75g of ethylenediamine and 200mL of water were mixed and homogenized at 12000rpm for 5min to obtain an aqueous phase; all the oil phase and all the aqueous phase were mixed and cured at pH=2 and 45℃ for 2h to obtain thiazophos microcapsule suspension; S2. Preparation of fluopyram suspension: 2 kg fluopyram, 200 g polycarboxylate dispersant, 250 g alkyl naphthalene sulfonate wetting agent and 10 L water are mixed and milled until the average particle size is ≤3 μm. Then 30 g nano silica is added and mixed evenly to obtain fluopyram suspension. S3. Compounding: The thiamethoxam microcapsule suspension obtained in S1 and the fluopyram suspension obtained in S2 are mixed together. The ratio of the thiamethoxam microcapsule suspension to the fluopyram suspension is adjusted. Then, 12g of xanthan gum suspension is added, and the pH is adjusted to 6-6.5. The mixture is stirred and homogenized at 1000rpm for 20min. After adding 25g of polyvinyl alcohol stabilizer, a microcapsule suspension-suspension is obtained, in which the thiamethoxam content is 6.5wt% and the fluopyram content is 15wt%.

[0049] <Comparative Example 3> The difference from Example 3 is that in S2, the alkyl naphthalene sulfonate wetting agent is removed, while the rest is the same as in Example 3.

[0050] <Comparative Example 4> The difference from Example 3 is that in S3, the suspending agent xanthan gum is removed, while the rest is the same as in Example 3.

[0051] <Comparative Example 5> The difference from Example 3 is that in S3, the stabilizer polyvinyl alcohol is removed, while the rest is the same as in Example 3.

[0052] <Performance Detection> The microcapsule suspensions obtained in the embodiments and comparative examples of this application were used for wheat fungal control. Before the experiment, diseased wheat samples were collected from the field and identified as *Fusarium graminearum* after molecular identification. Each plot was randomly distributed in a block design, with a protective row of 20m around each plot. 2 The plots were randomly arranged (16 plots in total), and wheat grain nematodes were inoculated simultaneously, with 100 nematodes inoculated in each plot.

[0053] Apply the pesticide once during the wheat greening stage, and then apply it again after 7 days, for a total of 2 applications. Use conventional spraying method to evenly spray the pesticide on both sides of the leaves. The spraying equipment is a backpack electric sprayer, and the water consumption is 60L / mu. 1. Determination of fungicidal effect: The disease was investigated twice, once at the wheat jointing stage (35 days after application, visual observation) and once at the wheat heading stage. Five sampling points were fixed along the diagonal of each plot, and 60 plants / 100-200 ears were investigated at each point. The disease incidence and disease rate of wheat were recorded in detail. Grading method: Grade 0: No lesions on leaf sheaths or stems; Grade 1: Leaf sheath infection, but not invading the stem; Grade 2: Lesions invade less than 1 / 4 of the stem circumference; Grade 3: Lesions invade less than 1 / 4 to 1 / 2 of the stem circumference; Grade 4: Lesions invade less than 1 / 2 to 3 / 4 of the stem circumference; Level 5: Lesions invade less than 3 / 4 of the stem circumference, resulting in white ears or no ears due to disease; The disease index and prevention efficacy are calculated using the following formula:

[0054] 2. Insecticide efficacy determination: Insect control rate % = 100% × dead wheat grain nematodes / 100.

[0055] Table 1 Data Records

[0056] Data Analysis: As shown in Table 1, the microcapsule suspension-suspension agent containing thiamethoxam and fluopyram of this application has a control effect of no less than 85% and an insect control rate of no less than 97.0%. This indicates that the microcapsule suspension-suspension agent of this application, with a thiamethoxam content of 6-7 wt% and a fluopyram content of 12-18 wt%, has a high-strength capsule wall material with good sealing properties, and is almost not damaged by the adjuvants in the suspension phase. Therefore, thiamethoxam almost never volatilizes and leaks. Furthermore, the polycarboxylate dispersant used in the suspension phase is suitable for the dispersion requirements of fluopyram, and almost no crystallization or precipitation occurs. This is due to the formulation of this application... This preparation method overcomes the technical bottlenecks in the preparation of existing CS-SC formulations, such as poor compatibility between the two components, easy microcapsule rupture, and easy stratification of the suspended phase. Compared with ordinary microcapsule suspensions and suspensions, it has significant advantages. The preparation process is simple and controllable, the raw materials are readily available, no special high-end equipment is required, and the cost of composite capsule wall materials and adjuvants is low. Compared with similar imported composite formulations, the production cost is reduced, and the formulation has a long-lasting effect and excellent control effect. It can reduce the number of subsequent applications and labor costs, significantly improve agricultural production efficiency, reduce planting costs, and solve the problem of environmental pollution caused by traditional formulations. It has economic, environmental and social benefits and has good prospects for promotion.

[0057] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for preparing a microcapsule suspension-suspension agent containing thiamethoxam and fluopyram, characterized in that, Includes the following steps: S1. Preparation of thiazophos microcapsule suspension: Thiazolephos is dispersed in an organic solvent, followed by the addition of isocyanate and urea-formaldehyde resin prepolymer, and stirred to form an oil phase; emulsifier, polyamine and water are mixed and homogenized to obtain an aqueous phase; the oil phase and aqueous phase are mixed and cured at pH=2-6 and temperature of 45-65℃ to obtain thiazophos microcapsule suspension, wherein the weight ratio of thiazophos, isocyanate, urea-formaldehyde resin prepolymer and polyamine is 30:(6-9):(8-12):(13-18); S2. Preparation of fluopyram suspension: Fluopyram, polycarboxylate dispersant, wetting agent and water are mixed and milled until the average particle size is ≤3μm. Then, nano-silica is added and mixed evenly to obtain fluopyram suspension. The ratio of fluopyram, polycarboxylate dispersant, wetting agent and nano-silica is 20:(2-4):(1.5-2.5):(0.3-1.0). S3. Compounding: The thiamethoxam microcapsule suspension obtained in S1 and the fluopyram suspension obtained in S2 are mixed together, and then a suspending agent is added. The pH is adjusted to 6-6.5, and the mixture is stirred and homogenized. After adding a stabilizer, a microcapsule suspension-suspension is obtained. The ratio of the thiamethoxam microcapsule suspension to the fluopyram suspension is adjusted. In the final microcapsule suspension-suspension, the thiamethoxam content is 6-7 wt% and the fluopyram content is 12-18 wt%.

2. The method for preparing a microcapsule suspension-suspension agent containing thiamethoxam and fluopyram according to claim 1, characterized in that, In step S3, the ratio of the amount of thiazophos microcapsule suspension to fluopyram suspension is adjusted so that the final microcapsule suspension contains 6.5 wt% thiazophos and 15 wt% fluopyram.

3. The method for preparing a microcapsule suspension-suspension agent containing thiamethoxam and fluopyram according to claim 1, characterized in that, In S1, the urea-formaldehyde resin prepolymer is prepared by the following method: Urea and formaldehyde are mixed in a molar ratio of 1:(1.6-2.0) and reacted at a temperature of 40-85℃ and a pH of 7-9 until the solution is clear and transparent. After cooling to room temperature, a colorless or light yellow transparent liquid is obtained, which is the urea-formaldehyde resin prepolymer solution.

4. The method for preparing a microcapsule suspension-suspension agent containing thiamethoxam and fluopyram according to claim 3, characterized in that, When preparing the urea-formaldehyde resin prepolymer in S1, the molar ratio of urea to formaldehyde is 1:1.

8.

5. The method for preparing a microcapsule suspension-suspension agent containing thiamethoxam and fluopyram according to claim 1, characterized in that, In the S1, curing is carried out under conditions of pH=3 and temperature of 55°C.

6. The method for preparing a microcapsule suspension-suspension agent containing thiamethoxam and fluopyram according to claim 1, characterized in that, In S1, the weight ratio of isocyanate to urea-formaldehyde resin prepolymer is 8:

10.

7. The method for preparing a microcapsule suspension-suspension agent containing thiamethoxam and fluopyram according to claim 1, characterized in that, In S1, the total amount of isocyanate and urea-formaldehyde resin prepolymer is 120 wt% of the amount of polyamine used.

8. The method for preparing a microcapsule suspension-suspension agent containing thiamethoxam and fluopyram according to claim 1, characterized in that, In S2, the ratio of fluopyram, polycarboxylate dispersant, wetting agent and nano silica is 20:3:2:0.

5.

9. The method for preparing a microcapsule suspension-suspension agent containing thiamethoxam and fluopyram according to claim 1, characterized in that, The stirring and homogenization in S3 specifically involves: First, mix and homogenize at 500 rpm for 8-10 minutes, then continue homogenizing at 1500 rpm for 10 minutes.

10. A microcapsule suspension prepared by the method of any one of claims 1-9 containing thiamethoxam and fluopyram.

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