Fluopyram microcapsule suspending agent and preparation method thereof

Abstract

The invention relates to the field of pesticide insecticides, in particular to a fluopyram microcapsule suspending agent and a preparation method thereof.The fluopyram microcapsule suspending agent is prepared from, by mass, 8-12 parts of fluopyram, 18-22 parts of 150 # solvent oil, 1-3 parts of polyisocyanate, 0.2-0.4 part of modified polyamine, 10-12 parts of auxiliaries and 40-50 parts of deionized water. A microcapsule system which is high in environmental adaptability and long-acting and stable is constructed by introducing a special release mechanism and combining a curing process and a green material, and compared with the prior art, the technology can accurately match disease high-incidence environmental conditions, prolong the pesticide lasting period and improve the pesticide effect. Meanwhile, according to the scheme, the release controllability, the structural stability and the environmental protection property are remarkably improved, the method is suitable for various crop disease prevention and control scenes, reliable technical support is provided for precision agriculture and green plant protection, and the wide market application prospect is achieved.

Description

Technical Field

[0001] The present invention relates to the field of pesticide insecticides, and particularly relates to a fluopyram microcapsule suspension and a preparation method thereof. Background Art

[0002] Fluopyram is a chemically synthesized succinate dehydrogenase inhibitor fungicide, which has broad-spectrum high efficiency and systemic conductivity; a suspension is a pesticide or chemical preparation, which is a colloidal dispersion system formed by uniformly and stably suspending insoluble solid active ingredients in water or an organic liquid medium through techniques such as grinding and dispersion, and the fluopyram suspension is widely used in agricultural production to control various crop diseases.

[0003] In the prior art, the fluopyram suspension has certain limitations. Its physical stability is poor and it is easily affected by changes in environmental temperature and humidity, resulting in degradation of the active ingredient or physical stratification during storage, reducing the drug efficacy. Moreover, after the traditional preparation is applied in the field, the active ingredient is quickly lost due to factors such as rain washing and ultraviolet decomposition, and the effective period is short, requiring frequent application of pesticides, which not only increases the cost, but also exacerbates the pesticide residue and environmental risks.

[0004] Therefore, according to the above related technologies, it is urgent to develop a fluopyram microcapsule suspension and a preparation method thereof. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a fluopyram microcapsule suspension and a preparation method thereof to solve the problems of poor physical stability and rapid loss of the active ingredient due to external factors in the prior art.

[0006] Based on the above purpose, the present invention provides a fluopyram microcapsule suspension and a preparation method thereof.

[0007] A fluopyram microcapsule suspension, comprising the following components in parts by mass: 8-12 parts of fluopyram, 18-22 parts of 150# solvent oil, 1-3 parts of polyisocyanate, 0.2-0.4 parts of modified polyamine, 10-12 parts of auxiliary agent, and 40-50 parts of deionized water; The auxiliary agent includes an emulsifier, a dispersant, a thickener, a preservative, an antifoaming agent, an antifreezing agent, and a pH regulator.

[0008] A preparation method of a fluopyram microcapsule suspension, and the preparation method is as follows: Step S1: Add fluopyram into 150# solvent oil, heat up to 40-60°C, add polyisocyanate, and stir for 40-60 min at a rotation speed of 400-600 rpm to obtain oil phase A; Step S2: Add emulsifier Tween 80 and dispersant naphthalene sulfonate formaldehyde condensate sulfonate into deionized water, heat up to 20 - 30 °C, stir for 20 - 30 min at a rotation speed of 300 - 500 rpm to obtain aqueous phase B; Step S3: Pour oil phase A into aqueous phase B, stir and shear at a rotation speed of 8000 - 12000 rpm for 10 - 15 min to form a stable O / W emulsion. Control the average particle size D90 to be 5 μm - 8 μm, heat up to 35 - 45 °C, stir at a rotation speed of 200 - 300 rpm, add modified polyamine, react for 1 - 3 h, then heat up to 45 - 50 °C, react for 50 - 70 min, and then cool down to 30 - 40 °C, react for 50 - 70 min to obtain the microcapsule emulsion; Step S4: Add the microcapsule emulsion into the mixed aqueous solution of antifreeze glycerol and thickener xanthan gum, stir for 5 - 10 min, then add the pH regulator citric acid monohydrate aqueous solution to adjust the pH to 5.4, add preservative isothiazolinone and defoamer silicone, stir for 20 - 40 minutes to obtain the fluxapyroxad microcapsule suspension; The modified polyamine is thiourea - modified polyamine; The average particle size D90 being 5 μm - 8 μm means that the average particle size corresponding to 90% is 5 μm - 8 μm.

[0009] Preferably, in step S1, the mass ratio of fluxapyroxad, 150# solvent oil and polyisocyanate is 8 - 12:18 - 22:1 - 3; In step S2, the mass ratio of the emulsifier, dispersant and deionized water is 0.1 - 0.2:0.1 - 0.2:40 - 50; In step S3, the mass ratio of oil phase A, aqueous phase B and modified polyamine is 1:1.8 - 2.2:0.008 - 0.01; In step S4, the mass ratio of the microcapsule emulsion, antifreeze, thickener, preservative and defoamer is 40 - 50:2 - 4:0.1 - 0.2:0.01 - 0.02:0.01 - 0.02.

[0010] Preferably, for the polyisocyanate, its preparation method is as follows: Step A1: Add iminoaldehyde, 5 - hydroxybenzotriazole and catalyst p - toluenesulfonic acid into toluene solvent, heat up to 110 - 120 °C, react for 35 - 40 h. After the reaction is completed, cool down to 20 - 30 °C, wash, dry, and perform vacuum distillation to obtain tetra - hydroxybenzotriazole condensed amine; Step A2: Add tetra - hydroxybenzotriazole condensed amine and 1,5 - pentane diisocyanate into ethyl acetate solvent, stir evenly, add catalyst dibutyltin dilaurate, heat up to 100 - 120 °C, react for 5 - 7 h, and perform vacuum distillation to obtain polyisocyanate; Step A3: Add the modified lignocellulose solution, the catalyst 30% HCl solution, and the polyisocyanate into the adipic acid solvent, heat up to 70 - 80 °C, react for 2 - 3 h, cool down to 20 - 30 °C, and after the reaction is completed, obtain the polyisocyanate; Construct a dynamic capsule wall using thiourea-modified polyamine and polyisocyanate. Combining with the moisture absorption characteristics of modified lignocellulose, environmental-responsive release can be achieved. It can accelerate the release of fluxapyroxad under high temperature and high humidity (conditions with high incidence of diseases), and at the same time, it can maintain the slow-release mode in the non-active environment, extend the effective period, and reduce the frequency of pesticide application.

[0011] Preferably, in step A1, the mass ratio of the imino aldehyde, 5-hydroxybenzotriazole, and the catalyst p-toluenesulfonic acid is 1:7.3 - 7.5:0.09 - 0.11; In step A2, the mass ratio of the tetra-hydroxybenzotriazole amine, 1,5-pentane diisocyanate, and dibutyltin dilaurate is 1:1 - 1.2:0.04 - 0.06; In step A3, the mass ratio of the modified lignocellulose solution, the catalyst, and the polyisocyanate is 1:0.11 - 0.13:2 - 4; Introduce benzotriazole groups in the synthesis of polyisocyanate. This group has a rigid aromatic ring structure and multiple hydrogen bond sites. During the cross-linking process of the microcapsule wall material, the triazole groups form a dense network through π-π stacking and hydrogen bond interactions, significantly enhancing the hydrolysis resistance and anti-solvent penetration ability of the capsule wall; In addition, the benzotriazole groups of the polyisocyanate can absorb ultraviolet light, thereby reducing the photo-oxidative degradation rate of the polymer material of the capsule wall, maintaining the integrity and slow-release function of the microcapsule. At the same time, due to its low mobility and high light stability, the benzotriazole groups can reduce the impact of fluxapyroxad on non-target organisms, meeting the development requirements of green pesticide formulations.

[0012] Preferably, for the modified lignocellulose solution, its preparation method is as follows: Step B1: Under a nitrogen atmosphere, add lignocellulose into the N, N-dimethylformamide solution, heat up to 140 - 160 °C, add iodocyclohexane, react for 10 - 14 h, after the reaction is completed, extract, filter, wash and dry to obtain the modified lignocellulose; Step B2: Add the modified lignocellulose and adipic acid into the 30% HCl solution, heat up to 70 - 80 °C, stir for 2 - 3 h, cool down to 20 - 30 °C, filter, and perform vacuum distillation to obtain the modified lignocellulose solution; Lignocellulose has degradability. When there is a high concentration of microbial communities in the soil, the enzymes secreted by bacteria can erode the microcapsule wall material to achieve the targeted slow release of fluxapyroxad, which not only avoids the premature release of the drug but also ensures an efficient response during the outbreak of pests and diseases.

[0013] Preferably, the mass ratio of the lignocellulose to iodocyclohexane in step B1 is 1:8 - 9; The mass ratio of the modified lignocellulose to adipic acid in step B2 is 1:2.8 - 3.2.

[0014] Preferably, for the modified polyamine, its preparation method is as follows: Under a nitrogen atmosphere, add 2,2'-dithiobis(ethylamine) to thiourea, stir and mix, heat up to 120 - 140 °C, react for 2 - 4 h, cool down to 40 - 50 °C, react for 50 - 70 min, and then cool down to 20 - 30 °C to obtain the modified polyamine; Through chemical modification of the polyamine with thiourea, a dynamic disulfide group (-S-S-) is introduced. This group can react efficiently with the isocyanate group (-NCO) in the polyisocyanate during the microcapsule formation process to form a thiocarbamate cross - linked network. Compared with traditional amine curing agents, the fracture and recombination characteristics of the dynamic disulfide bond endow the microcapsule with appropriate flexibility, effectively relieve the internal stress concentration, reduce the risk of capsule wall cracking, and the strong coordination ability of thiourea can accelerate the interfacial polymerization reaction, shorten the capsule - forming time, and improve the process efficiency.

[0015] Preferably, the mass ratio of 2,2'-dithiobis(ethylamine) to thiourea is 2.8 - 3.2:1.

[0016] Advantages of the present invention: The present invention provides a fluxapyroxad microcapsule suspension and its preparation method. By introducing a special release mechanism, combining the curing process with green materials, the present invention constructs a microcapsule system with strong environmental adaptability, long - term stability. Compared with the prior art, this technology can accurately match the environmental conditions with high disease incidence, extend the effective period of the medicament, and at the same time, this solution has achieved significant improvements in release controllability, structural stability and environmental protection, and is applicable to various crop disease prevention and control scenarios, providing reliable technical support for precision agriculture and green plant protection, and having broad market application prospects. Brief Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following - described drawings are only those of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 It is the electron microscope image of the microcapsule in Example 10 of the present invention. Detailed Embodiments

[0019] To make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below in conjunction with specific embodiments.

[0020] Example 1: Preparation method of modified lignocellulose solution: S1: Under a nitrogen atmosphere, add 100 g of lignocellulose to 1000 mL of N, N-dimethylformamide solution, heat up to 140 °C, add 800 g of iodocyclohexane, react for 14 h, after the reaction is completed, extract, filter, wash and dry to obtain modified lignocellulose; S2: Add 100 g of modified lignocellulose and 280 g of adipic acid to 500 mL of 30% HCl solution, heat up to 70 °C, stir for 3 h, cool down to 20 °C, filter, and perform vacuum distillation to obtain a modified lignocellulose solution.

[0021] Example 2: Preparation method of modified lignocellulose solution: S1: Under a nitrogen atmosphere, add 100 g of lignocellulose to 1000 mL of N, N-dimethylformamide solution, heat up to 150 °C, add 850 g of iodocyclohexane, react for 12 h, after the reaction is completed, extract, filter, wash and dry to obtain modified lignocellulose; S2: Add 100 g of modified lignocellulose and 300 g of adipic acid to 500 mL of 30% HCl solution, heat up to 75 °C, stir for 2.5 h, cool down to 25 °C, filter, and perform vacuum distillation to obtain a modified lignocellulose solution.

[0022] Example 3: Preparation method of modified lignocellulose solution: S1: Under a nitrogen atmosphere, add 100 g of lignocellulose to 1000 mL of N, N-dimethylformamide solution, heat up to 160 °C, add 900 g of iodocyclohexane, react for 10 h, after the reaction is completed, extract, filter, wash and dry to obtain modified lignocellulose; S2: Add 100 g of modified lignocellulose and 320 g of adipic acid to 500 mL of 30% HCl solution, heat up to 80 °C, stir for 2 h, cool down to 30 °C, filter, and perform vacuum distillation to obtain a modified lignocellulose solution.

[0023] Example 4: Preparation method of polyisocyanate: S1: Add 100 g of iminoaldehyde, 730 g of 5-hydroxybenzotriazole and 9 g of the catalyst p-toluenesulfonic acid to toluene solvent, heat up to 110 °C, react for 40 h, after the reaction is completed, cool down to 20 °C, wash, dry, and perform vacuum distillation to obtain tetra-hydroxybenzotriazole condensed amine; S2: Add 100 g of tetra-hydroxybenzotriazole amine and 100 g of 1,5-pentane diisocyanate into 200 mL of ethyl acetate solvent, stir evenly, add 4 g of dibutyltin dilaurate as catalyst, heat up to 100 °C, react for 7 h, and then conduct vacuum distillation to obtain polyisocyanate; S3: Add 100 g of modified lignocellulose solution, 11 g of 30% HCl solution as catalyst and 200 g of polyisocyanate into 500 mL of adipic acid solvent, heat up to 70 °C, react for 3 h, cool down to 20 °C, and the reaction is completed to obtain polyisocyanate.

[0024] Example 5: Preparation method of polyisocyanate: S1: Add 100 g of imino aldehyde, 740 g of 5-hydroxybenzotriazole and 10 g of p-toluenesulfonic acid as catalyst into 1000 mL of toluene solvent, heat up to 115 °C, react for 37 h, after the reaction is completed, cool down to 25 °C, wash, dry, and conduct vacuum distillation to obtain tetra-hydroxybenzotriazole amine; S2: Add 100 g of tetra-hydroxybenzotriazole amine and 110 g of 1,5-pentane diisocyanate into 300 mL of ethyl acetate solvent, stir evenly, add 5 g of dibutyltin dilaurate as catalyst, heat up to 110 °C, react for 6 h, and then conduct vacuum distillation to obtain polyisocyanate; S3: Add 100 g of modified lignocellulose solution, 12 g of 30% HCl solution as catalyst and 300 g of polyisocyanate into 500 mL of adipic acid solvent, heat up to 75 °C, react for 2.5 h, cool down to 25 °C, and the reaction is completed to obtain polyisocyanate.

[0025] Example 6: Preparation method of polyisocyanate: S1: Add 100 g of imino aldehyde, 750 g of 5-hydroxybenzotriazole and 11 g of p-toluenesulfonic acid as catalyst into 1000 mL of toluene solvent, heat up to 120 °C, react for 35 h, after the reaction is completed, cool down to 30 °C, wash, dry, and conduct vacuum distillation to obtain tetra-hydroxybenzotriazole amine; S2: Add 100 g of tetra-hydroxybenzotriazole amine and 120 g of 1,5-pentane diisocyanate into 300 mL of ethyl acetate solvent, stir evenly, add 6 g of dibutyltin dilaurate as catalyst, heat up to 120 °C, react for 5 h, and then conduct vacuum distillation to obtain polyisocyanate; S3: Add 100 g of modified lignocellulose solution, 13 g of 30% HCl solution as catalyst and 400 g of polyisocyanate into 600 mL of adipic acid solvent, heat up to 80 °C, react for 2 h, cool down to 30 °C, and the reaction is completed to obtain polyisocyanate.

[0026] Example 7: Preparation method of modified polyamine: Under a nitrogen atmosphere, 280 g of 2,2'-dithiobis(diethylamine) was added to 100 g of thiourea, stirred and mixed, heated to 120 °C, reacted for 4 h, cooled to 40 °C, reacted for 70 min, and then cooled to 20 °C to obtain a modified polyamine.

[0027] Example 8: Preparation method of modified polyamine: Under a nitrogen atmosphere, 300 g of 2,2'-dithiobis(diethylamine) was added to 100 g of thiourea, stirred and mixed, heated to 130 °C, reacted for 3 h, cooled to 45 °C, reacted for 60 min, and then cooled to 25 °C to obtain a modified polyamine.

[0028] Example 9: Preparation method of modified polyamine: Under a nitrogen atmosphere, 320 g of 2,2'-dithiobis(diethylamine) was added to 100 g of thiourea, stirred and mixed, heated to 140 °C, reacted for 2 h, cooled to 50 °C, reacted for 50 min, and then cooled to 30 °C to obtain a modified polyamine.

[0029] Example 10: Preparation method of a fluxapyroxad microcapsule suspension: S1: 80 g of fluxapyroxad was added to 180 g of 150# solvent oil, heated to 40 °C, 10 g of polyisocyanate was added, and stirred for 60 min at a rotation speed of 400 rpm to obtain oil phase A; S2: 1 g of emulsifier Tween 80 and 1 g of dispersant naphthalene sulfonate formaldehyde condensate sulfonate were added to 400 g of deionized water, heated to 20 °C, and stirred for 30 min at a rotation speed of 300 rpm to obtain water phase B; S3: 100 g of oil phase A was poured into 180 g of water phase B, stirred and sheared at a rotation speed of 8000 rpm for 15 min to form a stable O / W emulsion, controlling the average particle size D90 to be 5 μm - 8 μm, heated to 35 °C, at a rotation speed of 300 rpm, 0.8 g of modified polyamine was added, reacted for 1 h, then heated to 50 °C, reacted for 50 min, and then cooled to 40 °C, reacted for 50 min to obtain a microcapsule emulsion; S4: 100 g of the microcapsule emulsion was added to an aqueous solution mixture of 5 g of antifreeze glycerol and 1 g of thickener xanthan gum, stirred for 5 min, then an aqueous solution of pH regulator citric acid monohydrate was added to adjust the pH to 5.4, 0.1 g of preservative isothiazolinone and 0.1 g of defoamer silicone were added, and stirred for 40 minutes to obtain a fluxapyroxad microcapsule suspension.

[0030] Example 11: Preparation method of a fluxapyroxad microcapsule suspension: S1: Add 100 g of fluxapyroxad to 200 g of 150# solvent oil, heat up to 50 °C, add 20 g of polyisocyanate, and stir for 50 min at a rotation speed of 500 rpm to obtain oil phase A; S2: Add 1.5 g of emulsifier Tween 80 and 1.5 g of dispersant naphthalene sulfonate formaldehyde condensate sulfonate to 450 g of deionized water, heat up to 25 °C, stir for 25 min at a rotation speed of 400 rpm to obtain water phase B; S3: Pour 100 g of oil phase A into 200 g of water phase B, stir and shear at a rotation speed of 10000 rpm for 12 min to form a stable O / W emulsion, control the average particle size D90 to be 5 μm - 8 μm, heat up to 40 °C, rotate at 250 rpm, add 0.9 g of modified polyamine, react for 2 h, then heat up to 47 °C and react for 60 min, then cool down to 35 °C and react for 60 min to obtain a microcapsule emulsion; S4: Add 100 g of the microcapsule emulsion to an aqueous solution mixture of 6.7 g of antifreeze glycerol and 0.34 g of thickener xanthan gum, stir for 8 min, then add an aqueous solution of pH regulator citric acid monohydrate to adjust the pH to 5.4, add 0.034 g of preservative isothiazolinone and 0.034 g of defoamer silicone, and stir for 30 minutes to obtain a fluxapyroxad microcapsule suspension.

[0031] Example 12: A preparation method of a fluxapyroxad microcapsule suspension: S1: Add 120 g of fluxapyroxad to 220 g of 150# solvent oil, heat up to 60 °C, add 30 g of polyisocyanate, and stir for 40 min at a rotation speed of 600 rpm to obtain oil phase A; S2: Add 2 g of emulsifier Tween 80 and 2 g of dispersant naphthalene sulfonate formaldehyde condensate sulfonate to 500 g of deionized water, heat up to 30 °C, stir for 20 min at a rotation speed of 500 rpm to obtain water phase B; S3: Pour 100 g of oil phase A into 220 g of water phase B, stir and shear at a rotation speed of 12000 rpm for 10 min to form a stable O / W emulsion, control the average particle size D90 to be 5 μm - 8 μm, heat up to 45 °C, rotate at 200 rpm, add 1 g of modified polyamine, react for 3 h, then heat up to 45 °C and react for 70 min, then cool down to 30 °C and react for 70 min to obtain a microcapsule emulsion; S4: Add 100 g of the microcapsule emulsion to an aqueous solution mixture of 8 g of antifreeze glycerol and 0.4 g of thickener xanthan gum, stir for 10 min, then add an aqueous solution of pH regulator citric acid monohydrate to adjust the pH to 5.4, add 0.04 g of preservative isothiazolinone and 0.04 g of defoamer silicone, and stir for 20 minutes to obtain a fluxapyroxad microcapsule suspension.

[0032] Comparative Example 1: Compared with Example 10, polyisocyanate was not added during the preparation of the fluxapyroxad microcapsule suspension in this comparative example, and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally the fluxapyroxad microcapsule suspension was obtained.

[0033] Comparative Example 2: Compared with Example 10, only "thiourea-modified polyamine" was replaced with "ethylenediamine" in this comparative example, and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally the fluxapyroxad microcapsule suspension was obtained.

[0034] Comparative Example 3: Compared with Example 10, the preparation time of polyisocyanate was shortened from 40 h to 20 h in this comparative example, and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally the fluxapyroxad microcapsule suspension was obtained.

[0035] Comparative Example 4: Compared with Example 10, only "modified lignocellulose" was replaced with "lignocellulose" in this comparative example, and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally the fluxapyroxad microcapsule suspension was obtained.

[0036] Comparative Example 5: Compared with Example 10, only "p-toluenesulfonic acid" was replaced with "sulfuric acid" in this comparative example, and the remaining steps and parameters were the same. This comparative example will not be repeated here, and finally the fluxapyroxad microcapsule suspension was obtained.

[0037] Performance test: Determination of microcapsule particle size and distribution: Referring to the test standard of "ISO 13320 (Determination of particle size by laser diffraction method)", a CSL-101BI laser particle size distribution analyzer was used; 1. Respectively take 0.1 g of the microcapsule suspensions prepared in Examples 10 - 12 and Comparative Examples 1 - 5, add 100 mL of deionized water, and ultrasonically disperse for 5 minutes 2. The average particle size D of the microcapsules was measured by a laser particle size distribution analyzer av and the particle size dispersion coefficient δ. The smaller the δ value, the narrower the particle size distribution and the better the monodispersity of the microcapsules. The calculation formula for the particle size dispersion coefficient δ is: In the formula: D 10 、D 50 and D90 are the average particle sizes of the microcapsules corresponding to 10%, 50% and 90% respectively; Determination of encapsulation efficiency Refer to the ISO / TS 21387:2020 test standard, and use an HPLC high-performance liquid chromatograph. Chromatographic conditions: Mobile phase: acetonitrile - water (70:30, containing 0.1% phosphoric acid), flow rate: 1.0 mL / min, detection wavelength: 254 nm, column temperature: 30 °C, injection volume: 20 μL; 1. Determination of total drug content: Prepare the microcapsule suspension agents in Examples 10 - 12 and Comparative Examples 1 - 5 respectively, each 0.1 g. Add 10 mL of methanol, ultrasonically crush for 30 min with a power of 200 W, centrifuge for 10 min at a rotation speed of 15000 rpm. Take the supernatant and filter it through a 0.22 μm filter membrane, and detect the fluxapyroxad concentration by HPLC (denoted as C 总 ); 2. Determination of free drug: Prepare the microcapsule suspension agents in Examples 10 - 12 and Comparative Examples 1 - 5 respectively, each 0.1 g. Centrifuge at 15000 rpm for 30 minutes, separate the upper clear liquid, and the lower precipitate is the encapsulated microcapsule. Take the upper clear liquid and filter it through a 0.22 μm filter membrane, and detect the free fluxapyroxad concentration by HPLC (denoted as C 游离 );

[0038] 3. Calculation formula for encapsulation efficiency: Suspension rate of the preparation: 1. Prepare the microcapsule suspension agents in Examples 10 - 12 and Comparative Examples 1 - 5 respectively, each 2.0000 g. Place them in a 200 mL beaker containing 50 mL of standard hard water at 30 ± 1 °C, and oscillate in a circular motion by hand about 120 times per minute to completely dissolve the sample; 2. Pour it into a 250 mL graduated cylinder, rinse with standard hard water at 30 ± 1 °C, and dilute to the scale for volume fixation; 3. Use a pipette to remove 9 / 10 of the suspension in the graduated cylinder within 15 s, and measure the content in the bottom 1 / 10 (25 mL) of the suspension.

[0039] 4. Shake the 25 mL suspension at the bottom of the graduated cylinder well, filter it through a 0.22 μm filter paper. Place the residual capsule and the filter membrane together in a 50 mL beaker, add 10 mL of dimethylformamide for dilution, break the capsule with an ultrasonic cell disruptor, transfer it to a 50 mL volumetric flask, dilute to the scale with methanol, shake well. Use a pipette to transfer 5 mL of this solution to another 50 mL volumetric flask, dilute to the scale with methanol and shake well, then filter through a 0.45 μm filter paper, and the filtrate is for testing.

[0040] 5. Determine the fluxapyroxad content according to the encapsulation efficiency. The suspension rate expressed as a mass percentage is calculated by the following formula: Where: M --- the mass of fluxapyroxad in the sample weighed for preparing the suspension, g; M1 ---- The mass of acetochlor remaining in the bottom tenth of the suspension in the graduated cylinder, g.

[0041] Table 1 Detection data of Examples 10 - 12 and Comparative Examples 1 - 5 Physical stability test: Referring to the test standard of "CIPAC MT180 (Storage Stability Test of Pesticide Suspension Concentrates)". Thermal storage stability determination: The microcapsule suspension concentrates prepared in Examples 10 - 12 and Comparative Examples 1 - 5 were respectively filled into ampoules, sealed and placed in a constant temperature oven at 54 ± 2 °C. After standing for 14 d, they were taken out, and the microcapsule encapsulation rate, formulation suspension rate, water separation rate and the content of the active ingredient in the formulation were determined. Low temperature stability determination: The microcapsule suspension concentrates prepared in Examples 10 - 12 and Comparative Examples 1 - 5 were respectively filled into ampoules, sealed and stored at - 25 °C for 24 h. Then they were taken out and placed at room temperature to stand and melt, and the microcapsule encapsulation rate, formulation suspension rate, water separation rate and the content of the active ingredient in the formulation were determined. Table 2 Stability detection data of Examples 10 - 12 and Comparative Examples 1 - 5 Active ingredient sustained release performance test: Respectively take the microcapsule suspension concentrates prepared in Examples 10 - 12 and Comparative Examples 1 - 5, each 10 g, add 900 mL of pH 6.8 phosphate buffer solution, rotate at 50 rpm, and take samples regularly (0.5, 1, 2, 4, 8, 24, 48 h), and detect the release amount by HPLC. Anti - ultraviolet decomposition performance test: Referring to the ISO4892 - 3 test standard, using an ultraviolet aging chamber, respectively take the microcapsule suspension concentrates prepared in Examples 10 - 12 and Comparative Examples 1 - 5, each 0.5 g, coat the suspension concentrate on a glass plate to form a uniform film, dry it, put it into the ultraviolet aging chamber, irradiate it with light of a fixed intensity for 8 h at a temperature of 60 °C, take it out, condense it for 4 h at a temperature of 50 °C, continue for 72 h, and use HPLC to determine the residue amount of fluxapyroxad. The decomposition rate (R) calculation formula: In the formula: m1 is the mass of fluxapyroxad in the sample before irradiation treatment, g; m2 is the mass of the remaining fluxapyroxad in the sample after irradiation treatment, g.

[0042] Table 3 Detection data of Examples 10 - 12 and Comparative Examples 1 - 5 Environment - responsive release Refer to the test standard of GB / T31270-2014: Use a constant temperature incubator and HPLC; 1. Microbial response test: a. Collect the surface soil of the farmland at 0-20 cm, pass through a 2 mm sieve, measure the microbial activity, and the total number of bacteria ≥ 10 7 CFU / g; b. Sterilize the same soil with high-pressure steam at 121 °C for 30 min, repeat 3 times, and verify sterility after cooling; c. Respectively take the microcapsule suspension agents prepared in Examples 10-12 and Comparative Examples 1-5, each 1 g, weigh 10 g of highly active soil and 10 g of sterile soil, respectively put them into 50 mL glass culture bottles, stir evenly, adjust the soil humidity to 60% of the field water holding capacity, place the culture bottles in a constant temperature incubator at 25 °C, cultivate in the dark, ventilate for 10 minutes every day to maintain microbial activity, and conduct the experiment for 14 d; d. Respectively take 1 g of soil samples, add 10 mL of methanol-water (8:2) solution, ultrasonically extract for 30 min, with a power of 200 W, centrifuge for 10 min at 10000 rpm, take the supernatant and filter it through a 0.22 μm filter membrane, and detect the concentration of fluxapyroxad by HPLC.

[0043] 2. Humidity response test a. Respectively take the microcapsule suspension agents prepared in Examples 10-12 and Comparative Examples 1-5, each 1 g, evenly coat them on a glass weighing dish to form a film with a thickness of about 0.5 mm, and dry at 25 °C for 3 h; b. Respectively place the samples in a desiccator containing saturated KNO3 solution and a desiccator containing saturated LiCl solution, set 3 parallel samples in each group, and continue for 24 h, c. Dissolve the fluxapyroxad released in the film with 10 mL of methanol, ultrasonically assist extraction for 15 min, take the supernatant after centrifugation and filter it through a membrane, and detect the concentration by HPLC.

[0044] d. Calculate the humidity response coefficient (R): Table 4 Environmental response release detection data of Examples 10-12 and Comparative Examples 1-5 Data analysis: As can be seen from Tables 1-4, the fluxapyroxad microcapsule suspension agent prepared by the present invention has higher stability, slow release performance and environmental responsiveness; In Comparative Example 1, since polyisocyanate was not added, the encapsulation rate and suspension rate were significantly lower than those in Example 10, and the water separation rate after heat storage was relatively high. The reason is that polyisocyanate is a key component for constructing the dynamic microcapsule wall. Without it, a dense cross-linked network cannot be formed, resulting in a loose wall structure, easy leakage of the drug, and poor physical stability. In addition, the ultraviolet decomposition rate is much higher than that in the example, indicating that without the benzotriazole group in polyisocyanate, the capsule wall cannot effectively absorb ultraviolet light, accelerating the photooxidative degradation of fluxapyroxad; In Comparative Example 2, since thiourea-modified polyamine was replaced by ethylenediamine, the encapsulation rate and suspension rate were low. The reason is that ethylenediamine lacks dynamic disulfide bonds (-S-S-). The bond energy of dynamic disulfide bonds is relatively low. Under temperature changes and chemical environments, reverse cleavage and recombination can occur, thereby endowing the capsule wall with flexibility, relieving internal stress concentration, reducing the risk of capsule wall cracking, and enhancing the physical stability of microcapsules. At the same time, the microbial response release amount is relatively low. The reason is that bacteria in the soil secrete reducing enzymes or thiol substances, reducing the dynamic disulfide bonds to thiols, resulting in the fracture of the cross-linked network, accelerating the degradation of the capsule wall, and releasing fluxapyroxad. In Comparative Example 2, the capsule wall does not contain dynamic disulfide bonds, weakening the sensitivity to microbial enzymatic hydrolysis and reducing the targeted release efficiency; In Comparative Example 3, due to the shortening of the preparation time of polyisocyanate, the encapsulation rate and suspension rate were slightly lower than those in the example. The reason is that insufficient reaction time led to a decrease in the condensation degree of tetrahydroxybenzotriazole condensing amine, a decrease in the compactness of the cross-linked network, and a weakening of the anti-solvent penetration ability of the capsule wall. At the same time, the humidity response coefficient was relatively low. The possible reason is that the unreacted benzotriazole group has a certain hydrophobicity, thus weakening the water absorption and swelling efficiency of the capsule wall, resulting in a slow change in pore size, thereby delaying the drug release rate in a high-humidity environment; In Comparative Example 4, due to the use of unmodified wood cellulose, its encapsulation rate and suspension rate were significantly lower than those in the example. The reason is that unmodified wood cellulose lacks the chemical bonding ability with polyisocyanate, resulting in a loose capsule wall structure and insufficient hygroscopicity, further leading to a significant increase in the water separation rate in high-temperature and high-humidity tests. The reason is that unmodified wood cellulose cannot effectively regulate water penetration, resulting in premature drug release. In addition, the microbial response release amount is relatively low. The reason is that the surface of unmodified wood cellulose is smooth and lacks pores, making it difficult for enzymes to adsorb and catalyze hydrolysis reactions. Moreover, unmodified cellulose forms a dense molecular chain structure through hydrogen bonds. This rigid structure hinders the entry of enzyme molecules into the fiber interior, limiting the contact efficiency between enzymes and cellulose and weakening the targeted sustained-release function; In Comparative Example 5, since p-toluenesulfonic acid as the catalyst was replaced by sulfuric acid, the by-products of the condensation reaction increased during the preparation of polyisocyanate. The difference in acidic conditions might destroy the condensation selectivity between iminoaldehyde and 5-hydroxybenzotriazole, reducing the purity of tetra-hydroxybenzotriazole condensate. The rigid structure of the benzotriazole group was not fully formed due to the interference of impurities, further deteriorating the hydrolysis resistance of the capsule wall, and both the suspension rate and the sustained-release performance were significantly reduced. In addition, its environmental responsiveness decreased because the hygroscopicity of modified lignocellulose and the function of targeted release by microbial enzymatic hydrolysis relied on its compatibility with polyisocyanate. However, the cross-linked network of the capsule wall in Comparative Example 5 was incomplete, which might affect the distribution of modified lignocellulose in the wall material, resulting in its inability to effectively respond to the enzymatic hydrolysis of soil microorganisms.

[0045] Those of ordinary skill in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the present invention is limited to these examples. Under the concept of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order. There are many other variations in different aspects of the present invention as described above, and they are not provided in detail for the sake of brevity.

[0046] The present invention aims to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omission, modification, equivalent substitution, improvement, etc., made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A fluopyram microcapsule suspension, characterized in that, It comprises the following components in parts by mass: 8 - 12 parts of fluxapyroxad, 18 - 22 parts of 150# solvent oil, 1 - 3 parts of polyisocyanate, 0.2 - 0.4 parts of modified polyamine, 10 - 12 parts of auxiliary agent, and 40 - 50 parts of deionized water; The auxiliary agent includes emulsifier, dispersant, thickener, preservative, defoamer, antifreeze, and pH regulator.

2. A preparation method of a fluxapyroxad microcapsule suspension, characterized in that, The preparation method thereof is as follows: Step S1: Add fluxapyroxad into 150# solvent oil, heat up to 40 - 60°C, add polyisocyanate, and stir for 40 - 60 min at a rotation speed of 400 - 600 rpm to obtain oil phase A; Step S2: Add emulsifier Tween 80 and dispersant naphthalene sulfonate formaldehyde condensate sulfonate into deionized water, heat up to 20 - 30°C, and stir for 20 - 30 min at a rotation speed of 300 - 500 rpm to obtain aqueous phase B; Step S3: Pour oil phase A into aqueous phase B, stir and shear at a rotation speed of 8000 - 12000 rpm for 10 - 15 min to form a stable O / W emulsion, control the average particle size D90 to be 5 μm - 8 μm, heat up to 35 - 45°C, stir at a rotation speed of 200 - 300 rpm, add modified polyamine, react for 1 - 3 h, then heat up to 45 - 50°C, react for 50 - 70 min, and then cool down to 30 - 40°C, react for 50 - 70 min to obtain a microcapsule emulsion; Step S4: Add the microcapsule emulsion into the mixed aqueous solution of antifreeze glycerol and thickener xanthan gum, stir for 5 - 10 min, then add pH regulator citric acid monohydrate aqueous solution to adjust the pH to 5.4, add preservative isothiazolinone and defoamer silicone, and stir for 20 - 40 minutes to obtain a fluxapyroxad microcapsule suspension; The modified polyamine is thiourea - modified polyamine.

3. The preparation method of the fluxapyroxad microcapsule suspension according to claim 2, characterized in that, In step S1, the mass ratio of fluxapyroxad, 150# solvent oil, and polyisocyanate is 8 - 12:18 - 22:1 - 3; In step S2, the mass ratio of emulsifier, dispersant, and deionized water is 0.1 - 0.2:0.1 - 0.2:40 - 50; In step S3, the mass ratio of oil phase A, aqueous phase B, and modified polyamine is 1:1.8 - 2.2:0.008 - 0.01; In step S4, the mass ratio of microcapsule emulsion, antifreeze, thickener, preservative, and defoamer is 40 - 50:2 - 4:0.1 - 0.2:0.01 - 0.02:0.01 - 0.

02.

4. The preparation method of the fluxapyroxad microcapsule suspension according to claim 2, characterized in that, The preparation method of the polyisocyanate is as follows: Step A1: Add iminoaldehyde, 5 - hydroxybenzotriazole, and catalyst p - toluenesulfonic acid into toluene solvent, heat up to 110 - 120°C, react for 35 - 40 h, after the reaction is completed, cool down to 20 - 30°C, wash, dry, and perform vacuum distillation to obtain tetra - hydroxybenzotriazole condensed amine; Step A2: Add tetra - hydroxybenzotriazole condensed amine and 1,5 - pentane diisocyanate into ethyl acetate solvent, stir evenly, add catalyst dibutyltin dilaurate, heat up to 100 - 120°C, react for 5 - 7 h, and perform vacuum distillation to obtain polyisocyanate; Step A3: Add the modified lignocellulose solution, the catalyst 30% HCl solution, and the polyisocyanate into the adipic acid solvent, heat up to 70 - 80 °C, react for 2 - 3 h, cool down to 20 - 30 °C, and after the reaction is completed, obtain the polyisocyanate.

5. The preparation method of the fluxapyroxad microcapsule suspension according to claim 4, wherein, In Step A1, the mass ratio of the iminoaldehyde, 5 - hydroxybenzotriazole, and the catalyst p - toluenesulfonic acid is 1:7.3 - 7.5:0.09 - 0.11; In Step A2, the mass ratio of the tetrahydroxybenzotriazole - amine, 1,5 - pentane diisocyanate, and dibutyltin dilaurate is 1:1 - 1.2:0.04 - 0.06; In Step A3, the mass ratio of the modified lignocellulose solution, the catalyst, and the polyisocyanate is 1:0.11 - 0.13:2 - 4.

6. The preparation method of the fluxapyroxad microcapsule suspension according to claim 4, characterized in that, The preparation method of the modified lignocellulose solution is as follows: Step B1: Under a nitrogen atmosphere, add lignocellulose into the N, N - dimethylformamide solution, heat up to 140 - 160 °C, add iodocyclohexane, react for 10 - 14 h, after the reaction is completed, perform extraction, filtration, washing, and drying to obtain the modified lignocellulose; Step B2: Add the modified lignocellulose and adipic acid into the 30% HCl solution, heat up to 70 - 80 °C, stir for 2 - 3 h, cool down to 20 - 30 °C, filter, and perform vacuum distillation to obtain the modified lignocellulose solution.

7. The preparation method of the fluxapyroxad microcapsule suspension according to claim 6, characterized in that, In Step B1, the mass ratio of the lignocellulose and iodocyclohexane is 1:8 - 9; In Step B2, the mass ratio of the modified lignocellulose and adipic acid is 1:2.8 - 3.

2.

8. The preparation method of the fluxapyroxad microcapsule suspension according to claim 2, wherein, The preparation method of the modified polyamine is as follows: Under a nitrogen atmosphere, add 2,2'-dithiobis(ethylamine) into thiourea, stir and mix, heat up to 120 - 140 °C, react for 2 - 4 h, cool down to 40 - 50 °C, react for 50 - 70 min, and then cool down to 20 - 30 °C to obtain the modified polyamine.

9. The preparation method of the fluxapyroxad microcapsule suspension according to claim 7, characterized in that, The mass ratio of 2,2'-dithiobis(ethylamine) and thiourea is 2.8 - 3.2:1.

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