Water emulsion preparation with high stability as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of pesticide preparations, and particularly relates to a water emulsion preparation with high stability and a preparation method and application thereof. The specific oil-phase material stabilizer PCL with a binding effect is introduced into the water emulsion preparation, so that the physical stability and the foliar application performance of the water emulsion preparation are remarkably improved. According to the method, the stability of an oil-water interface is further enhanced by optimizing the binding performance of a material to an oil phase, the risk of emulsion layering and flocculation is reduced by combining a proper amount of a thickening agent and an emulsifying agent, meanwhile, the leaf surface steady-state retention performance of an aqueous emulsion preparation is improved, and the leaf surface adsorption efficiency and the pesticide effect durability of a pesticide are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of pesticide formulations, and particularly relates to a water emulsion formulation with high stability, a preparation method thereof, and an application thereof. Background Art

[0002] Pesticides play a crucial role in modern agricultural production and have an important position in preventing and controlling diseases, insects, and weeds, ensuring the normal growth of crops, improving yield and quality, and promoting the sustainable development of agriculture. The water emulsion formulation is one of the green and environmentally friendly water-based formulations strongly advocated by the state, and has advantages such as low toxicity, safe transportation and storage, good compatibility, and simple preparation process during agricultural production. However, it has problems such as poor stability and poor foliar steady retention ability.

[0003] Currently, the research on the stability of water emulsion formulations mainly focuses on the changes at the oil-water two-phase interface, including emulsifiers (the oil-water two-phase interface layer), the viscosity and density of the organic phase, polymers (steric hindrance), and thickeners, which have important effects on the stability of water emulsions. The stability maintenance of the oil-water two-phase interface needs to consider the cost issue to a great extent. Foliar steady retention mainly focuses on the design of the drug-loading system, and uses functionalized drug-loading materials to regulate its foliar affinity adhesion and steady retention performance. The water emulsion formulation is a non-loaded system, and there are few reports on the steady retention performance of water emulsion formulations. Therefore, regulating the stability of water emulsions and improving the foliar application performance are urgent problems to be solved for water emulsion formulations. Summary of the Invention

[0004] In view of the problems of poor stability and poor foliar application performance of water emulsion formulations, the present invention provides a preparation method of a water emulsion formulation with high stability. The present invention improves the water emulsion formulation through the oil-phase binding principle, improving the stability of the formulation and endowing the water emulsion formulation with foliar steady retention ability at the same time.

[0005] The present invention is realized through the following technical solutions: A preparation method of a water emulsion formulation with high stability, comprising the following steps: (1) Preparation of the oil phase: Weigh the original pyraclostrobin drug, add solvent oil and the dissolution auxiliary agent cyclohexanone and stir to dissolve, then add the emulsifier 602 and a stabilizer, and mix well to form the oil phase; (2) Preparation of the water phase: Weigh sodium lignosulfonate as a dispersant, add deionized water to make up, and stir evenly to form the water phase; (3) Preparation of the water emulsion: Add the prepared oil phase to the water phase, start high-speed homogenization to obtain a water emulsion system; in the homogenized water emulsion system, add the thickener xanthan gum and add ethylene glycol, and continue to stir and mix well to obtain a stable pyraclostrobin water emulsion.

[0006] Further, the addition amount of pyraclostrobin is 9.75% - 25% of the total mass.

[0007] Further, the addition amount of solvent oil is 12% - 30% of the total mass.

[0008] Further, the addition amount of emulsifier is 0.5% - 1.5% of the total mass.

[0009] Further, the addition amount of cyclohexanone is 3% - 9% of the total mass.

[0010] Further, the addition amount of sodium lignosulfonate is 1% - 5% of the total mass.

[0011] Further, the addition amount of xanthan gum is 0.1% - 0.3% of the total mass.

[0012] Further, the addition amount of ethylene glycol is 1% - 3% of the total mass.

[0013] Further, the stabilizer is one of PCL2404 or PCL6500.

[0014] Further, when the stabilizer is PCL2404, the addition amount is 0.8% - 3.2% of the total mass; when the stabilizer is PCL6500, the addition amount is 0.8% - 1.6% of the total mass.

[0015] Further, the conditions for shear homogenization are 12000 r / min for 5 min, and after adding the thickener xanthan gum and ethylene glycol, the stirring rate is adjusted to 600 r / min.

[0016] The present invention also provides an aqueous emulsion preparation with high stability prepared by the above preparation method.

[0017] The present invention also provides the application of the aqueous emulsion preparation with high stability prepared by the above preparation method in controlling Bipolaris maydis.

[0018] The beneficial technical effects of the present invention: The present invention provides a preparation method of an aqueous emulsion preparation with high stability. By introducing a specific oil-phase material stabilizer PCL with a binding effect into the aqueous emulsion preparation, the physical stability and foliar application performance of the aqueous emulsion preparation are significantly improved. This method further enhances the stability of the oil-water interface by optimizing the binding performance of the material to the oil phase, combines appropriate thickeners and emulsifiers to reduce the risk of emulsion stratification and flocculation, and at the same time improves the foliar steady retention performance of the aqueous emulsion preparation, increases the foliar adsorption efficiency of pesticides and the persistence of drug efficacy. This method has a simple process and moderate cost, can be widely used in the development of green and environment-friendly pesticide preparations, and has important popularization value. Brief Description of the Drawings

[0019] Figure 1 Optical imaging microscope topography diagrams of the preparations obtained in Example 1, Examples 16 - 18 and Comparative Example 16; Figure 2 Scanning electron microscope diagrams of the preparations obtained in Example 1, Examples 16 - 18 and Comparative Example 16; Figure 3 Particle size distribution, average particle sizes D50 and D90 diagrams of the preparations obtained in Example 1, Examples 16 - 18 and Comparative Example 16 at different time periods; Figure 4 Cold storage (4°C) stability analysis result diagrams of the preparations obtained in Example 1, Examples 16 - 18 and Comparative Example 16; Figure 5 Heat storage (54°C) stability analysis result diagrams of the preparations obtained in Example 1, Examples 16 - 18 and Comparative Example 16; Figure 6 Room temperature (25°C) stability analysis result diagrams of the preparations obtained in Example 1, Examples 16 - 18 and Comparative Example 16; Figure 7 Organic phase binding effect diagrams of the preparations obtained in Example 1, Examples 16 - 18 and Comparative Example 16; Figure 8 Physical diagrams of the interfacial oil phase migration staining experiments of Example 1, Examples 16 - 18 and Comparative Example 16; Figure 9 Absorbance result diagrams obtained from the interfacial oil phase migration staining experiments of Example 1, Examples 16 - 18 and Comparative Example 16; Figure 10 Photodegradation resistance performance result diagrams of the preparations obtained in Example 1, Examples 16 - 18 and Comparative Example 16; Figure 11 Anti - erosion performance measurement result diagrams of the preparations obtained in Example 1, Examples 16 - 18 and Comparative Example 16. Detailed implementation manners

[0020] In the following examples, the raw material sources are as follows: Table 1. Details of material sources

[0021] Example 1 Preparation of 25% pyraclostrobin aqueous emulsion: (1) Accurately weigh 12.82 g of pyraclostrobin technical, dissolve it by stirring with 11.8 g of solvent oil 150 and 3.2 g of cyclohexanone, add 0.5 g of emulsifier 602 and 0.4 g of PCL2404 to form the oil phase. (2) Accurately weigh 1.3 g of dispersant sodium lignosulfonate, add the remaining deionized water (make up to 50 g) to form the water phase. (3) Add the prepared oil phase to the water phase, start high-speed homogenization at 12000 r / min for 5 min. After shearing, add 0.075 g of xanthan gum and 1 g of ethylene glycol, and adjust the stirring rate to 600 r / min to thicken the aqueous emulsion system.

[0022] Example 2 The difference between Example 2 and Example 1 is that the addition amount of pyraclostrobin is 10 g, and other conditions are exactly the same.

[0023] Example 3 The difference between Example 3 and Example 1 is that the addition amount of pyraclostrobin is 5 g, and other conditions are exactly the same.

[0024] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the addition amount of pyraclostrobin is 20 g, and other conditions are exactly the same.

[0025] The addition amount of pyraclostrobin is limited to 9.75% - 25%. This range can not only ensure dissolution stability but also meet the requirements of formulation processing and preparation. While ensuring the stability of the formulation, the maximum loading of the active ingredient is achieved.

[0026] Example 4 The difference between Example 4 and Example 1 is that the addition amount of solvent oil is 6 g, and other conditions are exactly the same.

[0027] Example 5 The difference between Example 5 and Example 1 is that the addition amount of solvent oil is 15 g, and other conditions are exactly the same.

[0028] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the addition amount of solvent oil is 3 g, and other conditions are exactly the same.

[0029] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the addition amount of solvent oil is 20 g, and other conditions are exactly the same.

[0030] Examples 1, 4, 5 and Comparative Examples 2 - 3 explored the influence of solvent naphtha. The stability analysis is shown in Table 2. The dosage of solvent naphtha was limited to 12% - 30%. If the addition amount could not be lower than 12%, only when it was greater than 12% could it ensure that the technical material was dissolved into a uniform and transparent oily liquid in the solvent system. If it was higher than 30%, it could prevent the emulsification efficiency from being insufficient due to the excessive volume of the oil phase and cause demulsification. This range balanced the dissolution ability of the solvent for the active ingredient and the process feasibility.

[0031] Table 2. Comparative analysis of the stability of Examples 1, 4, 5 and Comparative Examples 2 - 3

[0032] Example 6 The difference between Example 6 and Example 1 was that the addition amount of emulsifier 602 was 0.25 g, and other conditions were exactly the same.

[0033] Example 7 The difference between Example 7 and Example 1 was that the addition amount of emulsifier 602 was 0.75 g, and other conditions were exactly the same.

[0034] Comparative Example 4 The difference between Comparative Example 4 and Example 1 was that the addition amount of emulsifier 602 was 1 g, and other conditions were exactly the same.

[0035] Comparative Example 5 The difference between Comparative Example 5 and Example 1 was that the addition amount of emulsifier 602 was 0 g, and other conditions were exactly the same.

[0036] Examples 1, 6, 7 and Comparative Examples 4 - 5 explored the influence of the emulsifier. The stability analysis is shown in Table 3. The dosage of emulsifier 602 was limited to 0.5% - 1.5%. The lower limit of 0.5% could meet the basic requirements for the stability of the oil - water interface and prevent flocculation caused by insufficient emulsification. The upper limit of 1.5% avoided over - emulsification from destroying the balance of the oil - water interface film and causing demulsification. This range screened the dosage of the emulsifier by judging the emulsion stability and the cold - hot storage stability to achieve the high - efficiency stability of the water - in - oil emulsion preparation. When exceeding this range, the system would become unstable due to flocculation (low dosage) or oil - water interface separation (high dosage).

[0037] Table 3. Comparative analysis of the stability of Examples 1, 6, 7 and Comparative Examples 4 - 5

[0038] Example 8 The difference between Example 8 and Example 1 was that the addition amount of cyclohexanone was 1.5 g, and other conditions were exactly the same.

[0039] Example 9 Example 9 is different from Example 1 in that the addition amount of cyclohexanone is 4.5 g, and other conditions are exactly the same.

[0040] Comparative Example 6 Comparative Example 6 is different from Example 1 in that the addition amount of cyclohexanone is 1 g, and other conditions are exactly the same.

[0041] Comparative Example 7 Comparative Example 7 is different from Example 1 in that the addition amount of cyclohexanone is 5 g, and other conditions are exactly the same.

[0042] Example 1, 8, 9 and Comparative Examples 6 - 7 were used to explore the effect of cyclohexanone. The stability analysis is shown in Table 4. The dosage of cyclohexanone is limited to 3% - 9%. Within this range, the thermal storage stability of the water emulsion preparation is qualified and there is no delamination phenomenon. This range realizes the efficient and stable production of the preparation by balancing the cold and heat storage stability and industrial compliance of the water emulsion preparation.

[0043] Table 4. Comparative analysis of the stability of Example 1, 8, 9 and Comparative Examples 6 - 7

[0044] Example 10 Example 10 is different from Example 1 in that the addition amount of sodium lignosulfonate is 0.5 g, and other conditions are exactly the same.

[0045] Example 11 Example 11 is different from Example 1 in that the addition amount of sodium lignosulfonate is 2.5 g, and other conditions are exactly the same.

[0046] Comparative Example 8 Comparative Example 8 is different from Example 1 in that the addition amount of sodium lignosulfonate is 0 g, and other conditions are exactly the same.

[0047] Comparative Example 9 Comparative Example 9 is different from Example 1 in that the addition amount of cyclohexanone is 3 g, and other conditions are exactly the same.

[0048] Example 1, 10, 11 and Comparative Examples 8 - 9 were used to explore the effect of sodium lignosulfonate. The stability analysis is shown in Table 5. The dosage of sodium lignosulfonate is limited to 1% - 5%. When it is less than 1%, the particles cannot be separated and agglomeration and sedimentation occur. If it is excessive, it will destroy the charge balance or steric hindrance effect on the particle surface, resulting in an increase in the attraction between particles and causing flocculation or aggregation. This range realizes the efficient dispersion and long-term stability of the preparation by balancing the dosage of the dispersant.

[0049] Table 5. Comparative analysis of the stability of Example 1, 10, 11 and Comparative Examples 8 - 9

[0050] Example 12 The difference between Example 12 and Example 1 is that the addition amount of xanthan gum is 0.05 g, and other conditions are exactly the same.

[0051] Example 13 The difference between Example 13 and Example 1 is that the addition amount of xanthan gum is 0.15 g, and other conditions are exactly the same.

[0052] Comparative Example 10 The difference between Comparative Example 10 and Example 1 is that the addition amount of xanthan gum is 0 g, and other conditions are exactly the same.

[0053] Comparative Example 11 The difference between Comparative Example 11 and Example 1 is that the addition amount of xanthan gum is 0.2 g, and other conditions are exactly the same.

[0054] Table 6. Comparative analysis of the stability of Example 1, 12, 13 and Comparative Example 10 - 11

[0055] Example 1, 12, 13 and Comparative Example 10 - 11 explore the influence of xanthan gum. The comparative analysis of stability is shown in Table 6. The dosage of xanthan gum is limited to 0.1% - 0.3%. If it is lower than 0.1%, rapid sedimentation will occur. If it is higher than 0.3%, excessive thickening will lead to difficulties in pouring and dilution during the use of the preparation. This range achieves the best balance between the storage stability and use performance of the preparation by regulating the dosage of the anti - sediment agent.

[0056] Example 14 The difference between Example 14 and Example 1 is that the addition amount of ethylene glycol is 0.5 g, and other conditions are exactly the same.

[0057] Example 15 The difference between Example 15 and Example 1 is that the addition amount of ethylene glycol is 1.5 g, and other conditions are exactly the same.

[0058] Comparative Example 12 The difference between Comparative Example 12 and Example 1 is that the addition amount of ethylene glycol is g, and other conditions are exactly the same.

[0059] Comparative Example 13 The difference between Comparative Example 13 and Example 1 is that the addition amount of ethylene glycol is 2 g, and other conditions are exactly the same.

[0060] Example 1, 14, 15 and Comparative Example 12 - 13 explore the influence of ethylene glycol. The comparative analysis of stability is shown in Table 7. The dosage of ethylene glycol is limited to 1% - 3%. Within this range, better cold storage stability is provided. A suitable dosage range of the antifreeze agent is screened by comparing a series of performance changes such as the cold and hot storage stability of the emulsion in water.

[0061] Table 7. Comparative Analysis of the Stability of Examples 1, 14, 15 and Comparative Examples 12 - 13

[0062] Example 16 Preparation of 25% pyraclostrobin aqueous emulsion: (1) Accurately weigh 12.82 g of pyraclostrobin technical, stir and dissolve it with 11.8 g of solvent oil and 3.2 g of cyclohexanone, add 0.5 g of emulsifier 602 and 1.6 g of PCL2404 to form the oil phase. (2) Accurately weigh 1.3 g of dispersant sodium lignosulfonate, add the remaining deionized water (make up to 50 g) to form the water phase. (3) Add the prepared oil phase to the water phase, start high-speed homogenization at 12000 r / min for 5 min. After shearing, add 0.075 g of xanthan gum and 1 g of ethylene glycol, adjust the stirring rate to 600 r / min, and thicken the aqueous emulsion system.

[0063] Comparative Example 14 The difference between Comparative Example 14 and Example 1 is that the addition amount of PCL2404 is 3 g, and the other conditions are exactly the same.

[0064] Examples 1, 16 and Comparative Example 14 were used to explore the effect of PCL2404. The comparative analysis of stability is shown in Table 8. The dosage of PCL2404 is limited to 0.8% - 3.2%. Within this range, PCL2404 can be used to bind the organic phase to maintain the stability of the preparation. If it is too low, the ability to maintain stability is insufficient; if it is too high, flocculation and precipitation will occur.

[0065] Table 8. Comparative Analysis of the Stability of Examples 1, 16 and Comparative Example 14 Example 17 Preparation of 25% pyraclostrobin aqueous emulsion: (1) Accurately weigh 12.82 g of pyraclostrobin technical, stir and dissolve it with 11.8 g of solvent oil and 3.2 g of cyclohexanone, add 0.5 g of emulsifier 602 and 0.4 g of PCL6500 to form the oil phase. (2) Accurately weigh 1.3 g of dispersant sodium lignosulfonate, add the remaining deionized water (make up to 50 g) to form the water phase. (3) Add the prepared oil phase to the water phase, start high-speed homogenization at 12000 r / min for 5 min. After shearing, add 0.075 g of xanthan gum and 1 g of ethylene glycol, adjust the stirring rate to 600 r / min, and thicken the aqueous emulsion system.

[0066] Example 18 Preparation of 25% pyraclostrobin aqueous emulsion: (1) Accurately weigh 12.82 g of pyraclostrobin technical, dissolve it by stirring with 11.8 g of solvent oil and 3.2 g of cyclohexanone, add 0.5 g of emulsifier 602 and 0.8 g of PCL6500 to form the oil phase. Accurately weigh 1.3 g of dispersant sodium lignosulfonate, add the remaining deionized water (to make up 50 g) to form the water phase. (3) Add the prepared oil phase to the water phase, start high-speed homogenization at 12000 r / min for 5 min. After shearing, add 0.075 g of xanthan gum and 1 g of ethylene glycol, adjust the stirring rate to 600 r / min, and thicken the aqueous emulsion system.

[0067] Comparative Example 15 The difference between Comparative Example 15 and Example 1 is that the addition amount of PCL2404 is 1.6 g, and the other conditions are exactly the same.

[0068] Examples 17, 18 and Comparative Example 15 were used to explore the influence of PCL6500. The comparative analysis of stability is shown in Table 9. The dosage of PCL6500 is limited to 0.8% - 1.6%. Within this range, PCL6500 can be used to bind the organic phase to maintain the stability of the preparation. If it is too low, the ability to maintain stability is insufficient; if it is too high, flocculation and precipitation will occur.

[0069] Table 9. Comparative analysis of the stability of Examples 17, 18 and Comparative Example 15

[0070] Comparative Example 16 Preparation of 25% pyraclostrobin aqueous emulsion: (1) Accurately weigh 12.82 g of pyraclostrobin technical, dissolve it by stirring with 11.8 g of solvent oil and 3.2 g of cyclohexanone, add 0.5 g of emulsifier 602 to form the oil phase. Accurately weigh 1.3 g of dispersant sodium lignosulfonate, add the remaining deionized water (to make up 50 g) to form the water phase. (3) Add the prepared oil phase to the water phase, start high-speed homogenization at 12000 r / min for 5 min. After shearing, add 0.075 g of xanthan gum and 1 g of ethylene glycol, adjust the stirring rate to 600 r / min, and thicken the aqueous emulsion system.

[0071] Characterize the preparations obtained from Examples 1, 16 - 18 and Comparative Example 16 1. Morphology characterization of different pesticide preparations Optical imaging microscope pretreatment: Dilute each sample with deionized water, add 100 μL of the diluted solution to a 50 mL centrifuge tube and add 10 mL of deionized water, vortex and let stand for 30 min. After standing, suck the suspension from the upper middle part of the centrifuge tube and titrate it onto a glass slide. Adjust the optical microscope to the appropriate brightness, and observe and photograph the morphological characteristics.

[0072] The test results are as follows Figure 1 As shown, by observing the change in the particle size of the emulsion in water under storage conditions at different temperatures through an optical imaging microscope, after 14 days of storage, the particle size of the emulsion preparation in the comparative example showed a significant increase, while the particle sizes of the emulsion preparations in Examples 1, 16 - 18 showed no significant change.

[0073] Scanning electron microscope pretreatment: First, the emulsion in water was diluted, centrifuged, redissolved, etc. The redissolved solution was allowed to stand for 30 minutes, 1 mL of the upper-middle solution was taken, diluted to an appropriate concentration, spotted on a silicon wafer, and naturally air-dried. The morphology characteristics of the emulsion in water were photographed through a scanning electron microscope.

[0074] The test results are as follows Figure 2 As shown, by observing the morphological differences of the emulsion particles in the preparation through a scanning electron microscope, the morphology of the emulsion preparation in the comparative example showed a more spreading tendency compared to the morphologies of the emulsion preparations in the 4 examples. The emulsion preparations in the examples could maintain a good morphology of the emulsion preparation.

[0075] 2. Determination of particle size distribution The prepared preparations were stored according to cold storage (4°C), heat storage (54°C), and normal temperature (25°C). At different time points, the preparations were taken out and diluted with deionized water. At room temperature, the particle size distribution, average particle sizes D50 and D90 were measured respectively through a micron-level laser particle size analyzer to evaluate the size parameters. The results are shown in Figure 3 , by measuring the change in the particle size of the emulsion particles in the preparation under storage conditions at different temperatures through a micron-level laser particle size analyzer, after 14 days of storage, the particle size of the emulsion preparation in the comparative example showed a significant increase, and the particle sizes of the emulsion preparations in the 4 examples showed stability over time.

[0076] 3. Determination by a stability analyzer The prepared preparations were placed in a stability analyzer according to cold storage (4°C), heat storage (54°C), and normal temperature (25°C), and the temperature parameters were set. The test results are as follows Figures 4 - 6 As shown, by simulating the stability of the preparation under long-term storage conditions through a stability analyzer, under different temperature conditions of cold, heat, and normal temperature, the comparative example emulsion preparation showed a larger SI (stability index), while the SI (stability index) of the 4 example emulsion preparations was relatively small. The larger the SI index, the more unstable it is, indicating that the emulsion preparations in Examples 1, 16 - 18 have better preparation stability, and the stability of the emulsion preparation in Comparative Example 16 is relatively poor, especially during the heat storage stability process, the emulsion preparation in the comparative example tends to be more unstable.

[0077] 4. Determination of the oil phase binding ability Accurately weigh 0.1 g of drug-loaded material and place it in a 50 mL centrifuge tube, add 20 mL of pure water, let it stand for 5 min, stir the supernatant, take 1 ml of the supernatant, dilute it 50 times with acetonitrile, filter out impurities with a 0.22 μL organic filter membrane, and then perform high-performance liquid chromatography analysis to obtain the free pyraclostrobin concentration C1 not loaded by the material. Drain the water, add 20 ml of acetonitrile, ultrasonicate for 30 min and shake and extract for 5 min, take 1 ml of the supernatant, dilute it 50 times with acetonitrile, filter out impurities with a 0.22 μL organic filter membrane, and then perform high-performance liquid chromatography analysis to obtain the pyraclostrobin concentration C0 loaded by the material. Calculate the pesticide loading efficiency of the drug-loaded material according to the following formula: LE (%) = C1 / (C0+C1)×100% The test results are as follows Figure 7 As shown, Examples 1-4 exhibited relatively good oil phase binding capacity, and the 14-day binding efficiency was above 94%. The difference in binding capacity between Examples 1 and 16-18 was mainly reflected in the difference in the amount of material added and the difference between different materials. The binding capacity of Comparative Example 16 was poorer than that of Examples 1 and 16-18. The results showed that the introduction of the material increased the binding capacity of the oil phase itself and enhanced the stability of the oil phase.

[0078] 5. Interfacial oil phase migration staining determination Accurately weigh 10 g of the oil phase and place it in a 30 ml glass bottle. Add 0.001 g of boron reagent to evenly dye the oil phase. Then slowly add 10 g of pure water along the wall of the cup. After standing for 10 min, take 3 ml of the upper aqueous phase and measure its absorbance with a UV spectrophotometer. The actual measurement is shown in the figure below. Figure 8 The results of the measurement are shown in Figure 9 It can be seen from the figure that the amount of migration of the oil phase to the water phase in Examples 1 and 16-18 is small, and the difference in the absorbance of the water layer is mainly reflected in the difference in the amount of material added and the difference between different materials. The oil phase migration efficiency of Example 16 is higher than that of Examples 1 and 16-18. The results show that the introduction of the material increases the binding capacity of the oil phase itself and reduces the migration efficiency of the free oil phase, thereby maintaining the stability of the oil phase.

[0079] 6. Determination of photolysis resistance of different preparations Dilute the drug-loaded preparation to 1000 mg / L with deionized water, add 0.01% silicone as a wetting agent. Take 100 μL of the sample diluent and evenly apply it on a glass slide. After natural drying, place the glass slide under ultraviolet light with an average radiation intensity of 200 μW / cm2 to simulate the photolysis behavior of the carrier by ultraviolet rays. Finally, take out the glass slide and place it in a 50 mL centrifuge tube after photolysis for 0 min, 10 min, 30 min, 60 min, and 120 min respectively. Add 10 mL of acetonitrile to the centrifuge tube, ultrasonically treat for 30 min and then oscillate and extract for 30 min. Then take 1 mL of the supernatant and filter impurities using an organic filter membrane with a specification of 0.22 μm. Use a high-performance liquid chromatograph to measure the residual content (M t ) of the active ingredient on the glass slide at different photolysis times. Take the content of the active ingredient remaining on the glass slide before photolysis as the total content (M0), calculate the ultraviolet residual rate of the active ingredient, and draw the retention curve of the active ingredient of the foliar pesticide after photolysis. Calculate the pesticide residue rate of different drug-loaded preparations after photolysis according to the following formula: Pesticide residue rate (%) = M t / M0×100% The test results are as Figure 10 shown. It can be seen from Figure 10 that in Examples 1, 16 - 18, the photolysis rate is significantly slower than that in Comparative Example 16. The emulsion in water can better resist the degradation by ultraviolet rays during the retention on the leaf surface, reduce the loss of the active ingredient, and reduce the number of pesticide applications. This not only reduces the input cost of pesticide chemicals but also enhances the disease control effect.

[0080] 7. Determination of the anti-scouring performance of different preparations Dilute the drug-loaded preparation to 1000 mg / L with deionized water, add 0.01% silicone as a wetting agent. Take 100 μL of the sample diluent and evenly apply it on a glass slide. After natural drying, place the glass slide at a position on a platform with an angle of 30° to the horizontal plane and 10 cm away from the burette. Finally, take out the glass slide and place it in a 50 mL centrifuge tube after scouring for 0 min, 1 min, 3 min, 5 min, and 10 min respectively. Add 10 mL of acetonitrile to the centrifuge tube, ultrasonically treat for 30 min and then oscillate and extract for 30 min. Then take 1 mL of the supernatant and filter impurities using an organic filter membrane with a specification of 0.22 μm. Use a high-performance liquid chromatograph to measure the residual content (Mt) of the active ingredient on the glass slide at different scouring times. Take the content of the active ingredient remaining on the glass slide before scouring as the total content (M0), calculate the ultraviolet residual rate of the active ingredient, and simulate the retention curve of the active ingredient of the foliar pesticide after rain scouring. Calculate the pesticide residue rate of different drug-loaded preparations after photolysis according to the following formula: Pesticide residue rate (%) = Mt / M0×100% The test results are asFigure 11 As shown, there is no significant difference in the erosion resistance effect of Examples 1, 16 - 18, but they are all significantly better than the comparative example. In the scenario of long - term erosion (erosion for 6 - 10 min), Examples 1, 16 - 18 still exhibit good erosion resistance performance, and compared with Comparative Example 16, the loss of active ingredients can be reduced by 20%. The good rain erosion resistance performance of the aqueous emulsion preparation of the example means that less drug dosage is lost, which is environmentally friendly and more in line with the concept of green sustainable development.

[0081] 8. Indoor antibacterial activity test The mycelial growth rate method was used to determine the inhibitory effect of the aqueous emulsion preparation on Bipolaris maydis. A 5 - mm mycelial disc was taken from the edge of the tested Bipolaris maydis colony using a puncher and inoculated onto the center of the PDA plate containing the drug with the mycelial side facing down using an inoculation needle. The concentration gradients of the drug - containing plates were set as 0 μg / mL, 0.125 μg / mL, 0.25 μg / mL, 0.5 μg / mL, 1 μg / mL, and 2 μg / mL. After culturing in the dark at 27°C for 7 d, the diameter of the colony was measured using the cross - cross method (vertical cross method), and then the growth inhibition rate of the mycelium at different drug concentrations was calculated using the following formula. Each treatment was repeated 3 times.

[0082]

[0083] Note: Analyzed using DPS software, the ordinate (Y) represents the probit value of the inhibition rate, and the abscissa (X) represents the logarithm of the drug mass concentration. The virulence regression equation Y = bx + a and the correlation coefficient R are obtained, and the EC50 value and the 95% confidence interval are calculated. The EC50 value refers to the concentration of the drug that can cause a 50% inhibitory effect on the pathogen.

[0084] Table 10. Statistics of regression equation, EC50 value, and correlation coefficient

[0085] It can be seen from Table 9 that the aqueous emulsion preparations of Examples 1, 16 - 18 and Comparative Example 16 have good control effects on Bipolaris maydis, and can effectively inhibit the growth of Bipolaris maydis in the short term. The addition of the material does not affect the antibacterial effect of the aqueous emulsion preparation.

Claims

1. A preparation method of an emulsion preparation with high stability, characterized in that: It includes the following steps: (1) Preparation of the oil phase: Weigh the original pyraclostrobin drug, add solvent oil and cyclohexanone as a dissolution aid, stir and dissolve, then add emulsifier 602 and a stabilizer, and mix well to form the oil phase; (2) Preparation of the aqueous phase: Weigh sodium lignosulfonate as a dispersant, add deionized water to make up, and stir evenly to form the aqueous phase; (3) Preparation of the water emulsion: Add the prepared oil phase to the aqueous phase, start high-speed homogenization to obtain a water emulsion system; in the homogenized water emulsion system, add xanthan gum as a thickener and ethylene glycol, and continue to stir and mix well to obtain a stable pyraclostrobin water emulsion.

2. The preparation method of the water-in-oil emulsion preparation with high stability according to claim 1, wherein: The stabilizer is one of PCL2404 or PCL6500. When the stabilizer is PCL2404, the addition amount is 0.8 - 3.2% of the total mass; when the stabilizer is PCL6500, the addition amount is 0.8 - 1.6% of the total mass.

3. The preparation method of the aqueous emulsion preparation with high stability according to claim 1, characterized in that: The addition amount of pyraclostrobin is 9.75% - 25% of the total mass.

4. The preparation method of the water-in-oil emulsion preparation with high stability according to claim 1, characterized in that: The addition amount of solvent oil is 12% - 30% of the total mass, and the addition amount of emulsifier is 0.5% - 2% of the total mass.

5. The preparation method of the aqueous emulsion preparation with high stability according to claim 1, characterized in that: The addition amount of cyclohexanone is 3% - 9% of the total mass.

6. The preparation method of the water-in-oil emulsion preparation with high stability according to claim 1, characterized in that: The addition amount of sodium lignosulfonate is 1% - 5% of the total mass, and the addition amount of xanthan gum is 0.1 - 0.3% of the total mass.

7. The preparation method of the water-in-oil emulsion preparation with high stability according to claim 1, characterized in that: The addition amount of ethylene glycol is 1% - 3% of the total mass.

8. The preparation method of the water-in-oil emulsion preparation with high stability according to claim 1, characterized in that: The conditions for shear homogenization are 12000 r / min for 5 min. After adding xanthan gum and ethylene glycol, adjust the stirring rate to 600 r / min.

9. A water emulsion preparation with high stability prepared by the preparation method according to any one of claims 1 - 8.

10. Application of a water emulsion preparation with high stability prepared by the preparation method according to any one of claims 1 - 8 in preventing and controlling the pathogens of Bipolaris maydis.

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