Alkyl-modified polyacrylic acid loaded hydrophobic pesticide aqueous emulsion and preparation method thereof

Abstract

The present invention provides an alkyl-modified polyacrylic acid-loaded hydrophobic pesticide aqueous emulsion and a preparation method thereof, and belongs to the technical field of pesticide preparation. In the present invention, the raw materials for preparing the alkyl-modified polyacrylic acid-loaded hydrophobic pesticide aqueous emulsion include alkyl-modified polyacrylic acid, hydrophobic pesticide, organic solvent and water, and the mass content of the alkyl-modified polyacrylic acid in the alkyl-modified polyacrylic acid-loaded hydrophobic pesticide aqueous emulsion is 0.5-2%, and the mass content of the hydrophobic pesticide is 5-50%. In the alkyl-modified polyacrylic acid-loaded hydrophobic pesticide aqueous emulsion provided by the present invention, a higher drug loading can be achieved when the amount of alkyl-modified polyacrylic acid is small, the stability is good and the environment is friendly, and the pesticide preparation is highly efficient and low-toxic.

Description

Technical Field

[0001] The invention relates to the technical field of pesticide preparations, and in particular to an alkyl-modified polyacrylic acid-loaded hydrophobic pesticide aqueous emulsion and a preparation method thereof. Background Art

[0002] Pesticides are widely used to increase grain production as an effective means of preventing and controlling pests and diseases. Commercial pesticides such as pesticide microemulsions, emulsifiable concentrates, and water-based emulsions usually contain a large amount of surfactants. Non-biodegradable surfactants can cause serious damage to the environment and endanger health, such as dermatitis, respiratory diseases, eye irritation, etc. As people's awareness of environmental protection increases, many eco-friendly agricultural chemicals have received more and more attention. However, many pesticides have the disadvantages of poor photostability, low water solubility, and high toxicity to non-target organisms, resulting in low utilization rates of pesticides and great risks to the environment, which not only increases costs but also aggravates pollution. Therefore, it is of great significance to develop an efficient and low-toxic pesticide formulation with a small amount of surfactant, good stability, and environmental friendliness. Summary of the invention

[0003] The object of the present invention is to provide an alkyl-modified polyacrylic acid-loaded hydrophobic pesticide emulsion in water and a preparation method thereof. The alkyl-modified polyacrylic acid-loaded hydrophobic pesticide emulsion in water provided by the present invention can achieve a higher drug loading amount when the amount of alkyl-modified polyacrylic acid is relatively small, has good stability and is environmentally friendly, and is a highly efficient and low-toxic pesticide preparation.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The invention provides an alkyl-modified polyacrylic acid loaded hydrophobic pesticide aqueous emulsion. The preparation raw materials include alkyl-modified polyacrylic acid, hydrophobic pesticide, organic solvent and water. In the alkyl-modified polyacrylic acid loaded hydrophobic pesticide aqueous emulsion, the mass content of the alkyl-modified polyacrylic acid is 0.5-2%, and the mass content of the hydrophobic pesticide is 5-50%.

[0006] Preferably, the raw materials for preparing the alkyl-modified polyacrylic acid include polyacrylic acid, alkylamine, N,N'-dicyclohexylcarbodiimide and N-methylpyrrolidone; the molar ratio of the polyacrylic acid to the alkylamine is 100:1-15.

[0007] Preferably, the number average molecular weight of the polyacrylic acid is 50,000 to 700,000; and the alkylamine includes one or more of dodecylamine, pentadecylamine, hexadecylamine and octadecylamine.

[0008] Preferably, the preparation method of the alkyl-modified polyacrylic acid comprises the following steps:

[0009] The raw materials for preparing the alkyl-modified polyacrylic acid are mixed and subjected to an amidation reaction to obtain the alkyl-modified polyacrylic acid.

[0010] Preferably, the amidation reaction is carried out at a temperature of 50-70° C. and for a time of 12-24 hours.

[0011] Preferably, the hydrophobic pesticide comprises one or more of pyraclostrobin, lambda-cyhalothrin, azoxystrobin and avermectin.

[0012] Preferably, the organic solvent comprises one or more of methyl benzoate, cyclohexanone and dimethyl sulfoxide.

[0013] Preferably, the particle size of the droplets in the alkyl-modified polyacrylic acid-loaded hydrophobic pesticide aqueous emulsion is 1-10 μm.

[0014] The present invention provides a method for preparing the alkyl-modified polyacrylic acid-loaded hydrophobic pesticide aqueous emulsion described in the above technical solution, comprising the following steps:

[0015] mixing a hydrophobic pesticide with an organic solvent to obtain an oil phase;

[0016] mixing the alkyl-modified polyacrylic acid with water to obtain an aqueous phase;

[0017] The oil phase is mixed with the water phase, and an emulsification loading treatment is performed under shearing conditions to obtain the alkyl-modified polyacrylic acid loaded hydrophobic pesticide aqueous emulsion.

[0018] Preferably, the shearing speed is 1000-7000 rpm; and the emulsification loading treatment time is 2-30 min.

[0019] The present invention provides an alkyl-modified polyacrylic acid-loaded hydrophobic pesticide aqueous emulsion, and the raw materials for preparation include alkyl-modified polyacrylic acid, hydrophobic pesticide, organic solvent and water, and the mass content of alkyl-modified polyacrylic acid in the alkyl-modified polyacrylic acid-loaded hydrophobic pesticide aqueous emulsion is 0.5~2%, and the mass content of hydrophobic pesticide is 5~50%. The present invention uses alkyl-modified polyacrylic acid as a hydrophobic pesticide carrier, and its high viscosity can provide excellent stability for the system, and the strong emulsification effect can achieve a higher pesticide loading under the condition of less dosage, and it has good biocompatibility and can reduce environmental pressure. Moreover, the alkyl-modified polyacrylic acid of the present invention realizes the encapsulation of hydrophobic drugs through intermolecular non-covalent forces, such as hydrogen bonds and hydrophobic interactions, which can improve the photostability of hydrophobic pesticides and delay the release of hydrophobic pesticides in the environment, thereby reducing the acute toxicity of pesticides to non-target organisms and the photolysis rate in the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 P(AA / C 18), FTIR spectra of PAA and octadecylamine;

[0021] Figure 2 This is the surface tension test result diagram of different surfactant dilutions;

[0022] Figure 3 P(AA / C 18 ) and xanthan gum viscosity test results;

[0023] Figure 4 It is a schematic diagram of the preparation process of pyraclostrobin emulsion in water and a comparison diagram of the droplet size in pyraclostrobin emulsion in water prepared by different surfactants;

[0024] Figure 5 This is a photo of the pyraclostrobin emulsion in water prepared in Example 2 after centrifugation;

[0025] Figure 6 This is a physical picture of the pyraclostrobin emulsion in water prepared in Comparative Example 1 after centrifugation;

[0026] Figure 7 This is a photo of the pyraclostrobin emulsion in water prepared in Comparative Example 2 after centrifugation;

[0027] Figure 8 This is a photo of the pyraclostrobin emulsion in water prepared in Comparative Example 3 after centrifugation;

[0028] Fig. 9 This is a photo of the pyraclostrobin emulsion in water prepared in Comparative Example 4 after centrifugation;

[0029] Fig.10 This is a graph showing the droplet size test results of the pyraclostrobin aqueous emulsion prepared in Example 2 when placed for different time periods;

[0030] Fig.11 The microscope picture and the real picture of the pyraclostrobin emulsion in water prepared in Example 2;

[0031] Fig.12 The BS (%) of the pyraclostrobin aqueous emulsion prepared in Example 2 changes with time and sample height;

[0032] Fig.13 This is a graph showing the change of the TSI value of the pyraclostrobin emulsion in water prepared in Example 2 over time;

[0033] Fig.14 The potential test diagram of the newly prepared pyraclostrobin emulsion in water of Example 2 and Comparative Examples 1 to 4;

[0034] Fig.15 The pyraclostrobin aqueous emulsion prepared in Example 2 was mixed with the same concentration of P(AA / C 18 ) Viscosity comparison chart of pure water dilution;

[0035] Fig.16 : is a viscosity comparison chart of the pyraclostrobin aqueous emulsions prepared in Comparative Examples 1 to 4;

[0036] Fig.17 The appearance of pyraclostrobin emulsions in water with different drug loadings before and after centrifugation;

[0037] Fig.18 BS, TSI and particle size D of pyraclostrobin emulsions in water with different drug loadings 50 Test result graph;

[0038] Fig.19 The graph is a viscosity test result of pyraclostrobin emulsions in water with different drug loading amounts;

[0039] Fig. 20 The actual pictures and microscope pictures of pyraclostrobin emulsions in water with different drug loading amounts;

[0040] Fig.21 The photodegradation curves of the pyraclostrobin aqueous emulsion with a drug loading of 5 wt% prepared in Example 2 and Comparative Examples 1 to 4 after dilution;

[0041] Fig. 22 The figure is a graph showing the acute toxicity test results of the pyraclostrobin emulsion in water prepared in Example 2 and Comparative Examples 1 to 4 on zebrafish at pyraclostrobin concentrations of 0.1 mg / L and 0.08 mg / L, respectively. DETAILED DESCRIPTION

[0042] The invention provides an alkyl-modified polyacrylic acid loaded hydrophobic pesticide aqueous emulsion. The preparation raw materials include alkyl-modified polyacrylic acid, hydrophobic pesticide, organic solvent and water. In the alkyl-modified polyacrylic acid loaded hydrophobic pesticide aqueous emulsion, the mass content of the alkyl-modified polyacrylic acid is 0.5-2%, and the mass content of the hydrophobic pesticide is 5-50%.

[0043] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known to those skilled in the art or are prepared by methods well known to those skilled in the art.

[0044] The raw materials for preparing the alkyl-modified polyacrylic acid loaded hydrophobic pesticide aqueous emulsion of the present invention include alkyl-modified polyacrylic acid, hydrophobic pesticide, organic solvent and water; the mass content of alkyl-modified polyacrylic acid in the alkyl-modified polyacrylic acid loaded hydrophobic pesticide aqueous emulsion is 0.5-2%, specifically 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8% or 2%; the mass content of hydrophobic pesticide is 5-50%, specifically 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% or 50%. As an embodiment of the present invention, the mass ratio of the organic solvent to the hydrophobic pesticide can be 0.5-1.5:1, specifically 1:1.

[0045] As an embodiment of the present invention, the raw materials for preparing the alkyl-modified polyacrylic acid may include polyacrylic acid, alkylamine, N,N'-dicyclohexylcarbodiimide (DCC) and N-methylpyrrolidone (NMP); the molar ratio of the polyacrylic acid to the alkylamine may be 100:1-15, specifically 100:1, 100:2, 100:3, 100:4, 100:5, 100:6, 100:7, 100:8, 100:9, 100:10, 100:11, 100:12, 100:13, 100:14 or 100:15. As an embodiment of the present invention, the number average molecular weight of the polyacrylic acid can be 50,000 to 700,000, specifically 50,000, 100,000, 150,000, 200,000, 250,000, 300,000, 350,000, 400,000, 450,000, 500,000, 550,000, 600,000, 650,000 or 700,000; the alkylamine can include one or more of dodecylamine, pentadecylamine, hexadecylamine and octadecylamine, specifically dodecylamine, pentadecylamine, hexadecylamine or octadecylamine. As an embodiment of the present invention, the amount ratio of the alkylamine, N,N'-dicyclohexylcarbodiimide and N-methylpyrrolidone can be 2.1mmol:2~2.5mmol:150~200mL, specifically 2.1mmol:2.3mmol:170mL.

[0046] As an embodiment of the present invention, the preparation method of the alkyl-modified polyacrylic acid may include the following steps: mixing the raw materials for preparing the alkyl-modified polyacrylic acid, performing an amidation reaction, and obtaining the alkyl-modified polyacrylic acid. As an embodiment of the present invention, specifically, freeze-drying a commercially available polyacrylic acid solution for 3 to 5 hours to obtain a polyacrylic acid solid; adding the polyacrylic acid solid to N-methylpyrrolidone at 50 to 70°C (for example, 55 to 60°C) and stirring for 12 to 24 hours (for example, 20 to 24 hours) to obtain a polyacrylic acid solution; dissolving an alkylamine and N,N'-dicyclohexylcarbodiimide in N-methylpyrrolidone respectively to obtain an alkylamine solution and an N,N'-dicyclohexylcarbodiimide solution, and sequentially adding the alkylamine solution and the N,N'-dicyclohexylcarbodiimide solution to the polyacrylic acid solution to perform an amidation reaction. As an embodiment of the present invention, the temperature of the amidation reaction can be 50-70°C, specifically 55-60°C; the time can be 12-24h, specifically 20-24h. As an embodiment of the present invention, the amidation reaction can also include: cooling the obtained feed liquid after the amidation reaction to room temperature and filtering, collecting the filtrate and mixing it with a 40wt% NaOH aqueous solution for precipitation, then filtering, collecting the filter cake and washing it with N-methylpyrrolidone (the temperature can be 60°C) and methanol (the temperature can be room temperature) for 3 times respectively, and finally drying it in a 50°C oven for 12h to obtain the alkyl-modified polyacrylic acid. In the embodiment of the present invention, a high molecular weight polyacrylic acid and an alkylamine are used as the basic materials, and an amphiphilic high molecular weight polymer, namely, an alkyl-modified polyacrylic acid, is synthesized by an amidation reaction, and it is used as a hydrophobic pesticide carrier to prepare an aqueous emulsion, and its high viscosity can provide excellent stability for the system, and the strong emulsification effect can achieve a higher pesticide loading under the condition of less dosage, and it has good biocompatibility and can reduce environmental pressure. Moreover, the alkyl-modified polyacrylic acid of the present invention can encapsulate the hydrophobic drug through intermolecular non-covalent forces, such as hydrogen bonds and hydrophobic interactions, thereby improving the photostability of the hydrophobic pesticide and delaying the release of the hydrophobic pesticide in the environment, that is, having a certain sustained-release effect, thereby reducing the acute toxicity of the pesticide to non-target organisms and the photolysis rate in the environment.

[0047] As an embodiment of the present invention, the hydrophobic pesticide may include one or more of pyraclostrobin, high-efficiency cyhalothrin, azoxystrobin and avermectin, specifically pyraclostrobin, high-efficiency cyhalothrin, azoxystrobin or avermectin.

[0048] As an embodiment of the present invention, the organic solvent may include one or more of methyl benzoate, cyclohexanone and dimethyl sulfoxide, specifically methyl benzoate, cyclohexanone or dimethyl sulfoxide.

[0049] As an embodiment of the present invention, the particle size of the droplets in the alkyl-modified polyacrylic acid-loaded hydrophobic pesticide aqueous emulsion may be 1 to 10 μm, for example, 1 to 6 μm.

[0050] The present invention provides a method for preparing the alkyl-modified polyacrylic acid-loaded hydrophobic pesticide aqueous emulsion described in the above technical solution, comprising the following steps:

[0051] mixing a hydrophobic pesticide with an organic solvent to obtain an oil phase;

[0052] mixing the alkyl-modified polyacrylic acid with water to obtain an aqueous phase;

[0053] The oil phase is mixed with the water phase, and an emulsification loading treatment is performed under shearing conditions to obtain the alkyl-modified polyacrylic acid loaded hydrophobic pesticide aqueous emulsion.

[0054] The present invention mixes a hydrophobic pesticide with an organic solvent to obtain an oil phase. As an embodiment of the present invention, the temperature at which the hydrophobic pesticide and the organic solvent are mixed can be 15-40°C, specifically 25-30°C; in the embodiment of the present invention, the hydrophobic pesticide and the organic solvent are mixed at room temperature.

[0055] In the present invention, the alkyl-modified polyacrylic acid is mixed with water to obtain an aqueous phase. The present invention has no particular limitation on the manner of mixing the alkyl-modified polyacrylic acid with water, and any manner well known to those skilled in the art may be used.

[0056] After obtaining the oil phase and the water phase, the present invention mixes the oil phase with the water phase, performs emulsification loading treatment under shearing conditions, and obtains the alkyl-modified polyacrylic acid loaded hydrophobic pesticide aqueous emulsion. As an embodiment of the present invention, the shearing speed can be 1000-7000rpm, and further can be 3000-5000rpm; the emulsification loading treatment time can be 2-30min, and further can be 5-15min. In an embodiment of the present invention, the emulsification loading treatment is specifically carried out in a high-speed shearing machine.

[0057] The preparation method of the alkyl-modified polyacrylic acid-loaded hydrophobic pesticide aqueous emulsion provided by the invention is simple to operate and suitable for industrial batch production.

[0058] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0059] The experimental materials used in the following experiments are shown in Table 1, and the experimental instruments are shown in Table 2.

[0060] Table 1 Experimental materials

[0061]

[0062] Table 2 Experimental instruments

[0063]

[0064] Example 1

[0065] Preparation of octadecylamine-modified polyacrylic acid, the steps are as follows:

[0066] The polyacrylic acid (PAA) raw material liquid was freeze-dried for 5 hours to obtain PAA solid; 5g (0.0694mol) PAA solid was added to 150mL N-methylpyrrolidone (NMP) at 60°C and stirred for 24 hours to obtain a PAA solution; 0.565g octadecylamine and 0.474g N,N'-dicyclohexylcarbodiimide (DCC) were dissolved in 10mL NMP to obtain an octadecylamine solution and a DCC solution; the octadecylamine solution and the DCC solution were added to the PAA solution in sequence and reacted at 60°C for 24 hours; after the reaction was completed, the obtained product liquid was cooled to room temperature and filtered, the filtrate was collected and mixed with a 40wt% NaOH aqueous solution for precipitation, and then filtered, the collected filter cake was washed 3 times with N-methylpyrrolidone at a temperature of 60°C and methanol at a temperature of room temperature, respectively, and finally dried in an oven at 50°C for 12 hours to obtain octadecylamine-modified polyacrylic acid (denoted as P(AA / C 18 )).

[0067] Test Example 1

[0068] 1. Take PAA, octadecylamine, P(AA / C 18 ) samples were analyzed by FTIR spectroscopy at 4000 cm -1 Up to 650cm -1 Infrared detection is performed in a wide wavenumber range to determine the composition and structure of the sample by analyzing changes in functional groups.

[0069] Figure 1 P(AA / C 18 ), FTIR spectra of PAA and octadecylamine, by Figure 1 It can be seen that octadecylamine is at 3331 cm -1 There is an absorption peak at 1700cm -1 There is a strong absorption peak near the carbonyl stretching vibration. 18 ) spectrum at 3330cm -1 and 1560cm -1There are two absorption peaks near 3330cm -1 The broad peak at 1560 cm -1 The absorption band near 100 nm confirmed the formation of an amide bond between PAA and octadecylamine. The above results indicate that P(AA / C 18 ).

[0070] 2. Use DCAT 21 surface tension meter to test different surfactants (P(AA / C 18 The surface tension of the dilutions of 1, 2, 4, 5-nitropropene (Tween-80, SDBS, 602, EL-40, and AEO-9) was measured. The DCAT 21 surface tension meter was calibrated with deionized water (72.0 ± 0.2 mN / m) (WANG et al., 2014). Before the measurement, the samples were balanced until the surface tension value remained constant. Three replicates were measured for each sample.

[0071] The surface activity of a surfactant refers to its ability to significantly reduce the surface tension of a solvent after dissolving in it, and is usually measured by the magnitude of the surface tension. As the concentration of surfactant in the solvent increases, the surfactant molecules will gradually aggregate to form micelles, and the minimum concentration corresponding to the formation of micelles is the critical micelle concentration (CMC). Figure 2 The surface tension test results of different surfactant dilutions are shown in the figure. The results show that all six surfactants have good surface activity. As the concentration of surfactant increases, the surface tension of their aqueous solutions decreases rapidly. When the surfactant concentration reaches a certain value, the surface tension no longer decreases. The corresponding concentration at this time is CMC, and the corresponding surface tension value is the critical surface tension value (γ cmc ) Unlike other surfactants, in P(AA / C 18 ) After reaching the CMC value, the surface tension is diluted by 10 5 ~10 3 The surface tension value increases again when the concentration continues to increase, which may be due to the fact that P(AA / C 18 ) concentration increases, the distance between molecules decreases, P(AA / C 18 ) The hydrogen bonding between molecules is enhanced, thus increasing the surface tension. When the dilution factor is 100, the surface tension value reaches the highest point and then decreases again. It may be that the viscosity changes by an order of magnitude at this stage, which leads to a downward trend in the surface tension value again.

[0072] 3. At 25°C, use the No. 1 rotor of the rotational viscometer NDJ-5S to measure the viscosity of the sample, and perform three repeated measurements for each sample.

[0073] Figure 3 P(AA / C18 ) and xanthan gum viscosity test results. The results show that compared with xanthan gum, a common thickener in the formulation system, P(AA / C 18 ) has excellent viscosity performance in addition to its surface activity as a surfactant. 18 ) exhibits hydrogel properties and can be used as a thickener to increase the viscosity of the aqueous emulsion and thus maintain the stability of the system.

[0074] Example 2

[0075] Take 5.1g of pyraclostrobin (purity 98wt%) and dissolve it in 5.1g of methyl benzoate as the oil phase. Then add 0.5g, 1g and 2g of P(AA / C 18 ) was added into ultrapure water as the aqueous phase (total 100 g), and then the aqueous phase was mixed with the oil phase and sheared at 5000 rpm for 5 min, 10 min, and 15 min, respectively, to obtain pyraclostrobin aqueous emulsions with a drug loading of 5 wt%, respectively, denoted as P(AA / C 18 )@Pyr(where P(AA / C 18 ) mass contents are 0.5%, 1% and 2% respectively).

[0076] Comparative Examples 1 to 5

[0077] The method of Example 2 is followed, except that P(AA / C 18 ) were replaced by AEO-9, Tween-80, EL-40, 602, and SDBS, respectively, and finally the pyraclostrobin emulsions in water with a drug loading of 5 wt% were obtained, which were recorded as AEO-9@Pyr, Tween-80@Pyr, EL-40@Pyr, 602@Pyr, and SDBS@Pyr, respectively.

[0078] Test Example 2

[0079] 1. The particle sizes of the droplets in the newly prepared pyraclostrobin aqueous emulsions in Example 2 and Comparative Examples 1 to 5 were measured by a laser particle size analyzer.

[0080] Figure 4 Schematic diagram of the preparation process of pyraclostrobin emulsion in water and a comparison of droplet size in pyraclostrobin emulsion in water prepared with different surfactants. Figure 4 A in the figure is a schematic diagram of the preparation process of pyraclostrobin emulsion in water, wherein P(AA / C 18 ) is not only a gel material, but also can be used as a surfactant to load hydrophobic pesticides due to its amphiphilic structure, and aqueous emulsions with different fluidities can be prepared by high-speed shear method. Figure 4B and C in the figure are photos of pyraclostrobin emulsions prepared by using different surfactants under different shearing time conditions. Among them, the pyraclostrobin emulsions prepared by using SDBS under shearing time of 5min, 10min, and 15min all showed obvious stratification (such as Figure 4 B in the figure), the pyraclostrobin emulsions prepared with other surfactants at shear times of 5 min, 10 min, and 15 min all showed a milky white uniform state (e.g. Figure 4 C in. Figure 4 D, E, F, G and H in the figure are respectively P(AA / C 18 ), EL-40, AEO-9, 602 and Tween-80 prepared pyraclostrobin emulsions in water with shear times of 5min, 10min and 15min. The results show that with the increase of surfactant content, the particle size decreases. This may be because with the increase of surfactant content, the number of surfactant molecules increases, the emulsification performance is enhanced, and more emulsion droplets can be formed, thereby reducing the particle size. In addition, with the increase of shear time, the particle size decreases. This may be because the longer the shear time, the more energy is provided to the system, which can break up the larger emulsion droplets to form smaller droplets and improve the stability of the system.

[0081] 2. The newly prepared pyraclostrobin emulsions in water of Example 2 and Comparative Examples 1 to 4 were centrifuged (centrifuged at 3800 rpm for 10 min) to test their stability.

[0082] Figure 5 The pyraclostrobin aqueous emulsion prepared in Example 2 (surfactant is P(AA / C 18 )) Actual picture after centrifugation, Figure 6 This is a photo of the pyraclostrobin emulsion in water (surfactant is AEO-9) prepared in Comparative Example 1 after centrifugation. Figure 7 This is a photo of the pyraclostrobin aqueous emulsion (surfactant is Tween-80) prepared in Comparative Example 2 after centrifugation. Figure 8 This is a photo of the pyraclostrobin aqueous emulsion (surfactant is EL-40) prepared in Comparative Example 3 after centrifugation. Fig. 9 The actual picture of the pyraclostrobin aqueous emulsion (surfactant is 602) prepared in comparative example 4 after centrifugation; the results show that except for the use of 1% and 2% P(AA / C 18 ) prepared by the aqueous emulsion system remained uniform and stable, while the others showed stratification instability, indicating that only 1% of P(AA / C 18 ) can keep the water emulsion stable and not stratified under room temperature conditions.

[0083] 3. The different contents of P(AA / C) in Example 2 were used.18 ) The pyraclostrobin emulsion in water prepared under a shear time of 15 min was placed for different times (freshly prepared, 3d, 5d, 7d, 10d, 14d, 40d), and the droplet size was tested by a laser particle size analyzer.

[0084] Fig.10 The pyraclostrobin aqueous emulsion (P(AA / C 18 ) content, shear time is 15min) droplet size test results at different time, the results show that (P(AA / C 18 ) content was 0.5%, the droplet size increased significantly several times, and after 40 days, the particle size D 50 When the growth exceeds 8 μm, the appearance also shows obvious stratification; while (P(AA / C 18 ) content was 1% and 2%, the droplet size increased significantly only in the first 3 days of preparation, and the particle size remained stable without significant growth in the later period. 50 It remains at around 6μm, and the system remains uniform and stable without any stratification.

[0085] 4. Using a research-level biological microscope, the samples of Example 2 with different contents of P(AA / C 18 ) The morphology of the pyraclostrobin emulsions prepared under different shear time conditions was observed. Specifically, a drop of the pyraclostrobin emulsion was dropped on a glass slide and then covered with a cover glass. A drop of camphor oil was dropped on the cover glass, and then observation was performed using a 100X oil objective.

[0086] Fig.11 The pyraclostrobin aqueous emulsion (P(AA / C 18 ) content, different shearing time) microscope pictures and physical pictures, where A is a microscope picture and B is a physical picture; the results show that the pyraclostrobin emulsion in water is spherical, indicating that P(AA / C 18 ) is used to load the oil phase and emulsify it. The change in the size of the spherical emulsion is similar to the change in particle size, that is, as the shear time increases, the particle size of the emulsion becomes smaller and more uniform. However, when the content of P(AA / C 18 ) found that the droplets aggregated significantly, which may be due to P(AA / C 18 ) content increases, resulting in a higher viscosity and enhanced interaction between droplets, leading to an aggregation state.

[0087] 5. The emulsion stabilizer was used to test the emulsions with different contents of P(AA / C 18) The stability of the pyraclostrobin emulsion in water prepared under a shear time of 15 min was evaluated. Specifically, the pyraclostrobin emulsion in water was placed in a sample bottle (sample height of about 50 mm), and each sample was scanned every 5 min at 25 ° C for a total of 6 hours. By measuring the change in backscattered light intensity (BS, %) under different sample height conditions over time, the changes in droplet diameter and phase separation in the pyraclostrobin emulsion in water can be monitored, and the TSI value can be calculated based on the BS to evaluate its stability.

[0088] Fig.12 The pyraclostrobin aqueous emulsion (P(AA / C 18 ) content, shear time is 15min) with time (0~6h) and sample height, Fig.13 The pyraclostrobin aqueous emulsion (P(AA / C 18 ) content, shear time is 15min) TSI value changes with time (0~6h); The results show that the use of 1% and 2% P(AA / C 18 The TSI value of the pyraclostrobin emulsion prepared by 0.5% P(AA / C 18 ) The TSI value of pyraclostrobin prepared by PCR quickly increased to above 15 within 6 h, and the BS changed significantly with time, indicating that its stability was poor.

[0089] 6. Using a nanoparticle size and Zate potential analyzer, the newly prepared pyraclostrobin aqueous emulsions (with different surfactant contents and a shear time of 15 min) in Example 2 and Comparative Examples 1 to 4 were diluted 200 times with ultrapure water, and each sample was measured three times using a capillary electrode.

[0090] Fig.14 The potential test diagram of the newly prepared pyraclostrobin aqueous emulsion in Example 2 and Comparative Examples 1 to 4 shows that the use of P(AA / C 18 ) has a lower potential, indicating that negative charges are formed on the surface of the pyraclostrobin emulsion droplets. The electrostatic repulsion effect may make the droplets less likely to aggregate and combine, making them more stable.

[0091] 7. The viscosity of the pyraclostrobin emulsions prepared in Example 2 and Comparative Examples 1 to 4 under different surfactant contents and different shear times was measured. Specifically, the viscosity value was measured at 25° C. using rotor No. 1 of a rotational viscometer NDJ-5S, and each sample was measured three times.

[0092] Fig.15 The pyraclostrobin aqueous emulsion (P(AA / C 18 ) content, different shearing time) and the same concentration P(AA / C 18 ) viscosity comparison of pure water dilutions. The results show that the use of P(AA / C 18 ) prepared has a higher viscosity, and using the same content of P(AA / C 18 The viscosity of the drug-carrying system (i.e., pyraclostrobin emulsion in water) prepared by 18 ) pure water dilution, it is possible that the addition of oil phase to the system makes the gel network structure more expanded, thus causing P(AA / C 18 ) The intermolecular forces are enhanced, so the viscosity value increases significantly. 18 ) content was 0.5%, although the viscosity of the pyraclostrobin emulsion was higher than that of its pure water dilution, its fluidity was still good; P(AA / C 18 ) content was 1%, the pyraclostrobin emulsion was relatively viscous and had average fluidity; P(AA / C 18 ) content is 2%, and the pyraclostrobin emulsion in water is the most viscous and has poor fluidity. This may be because the increase in viscosity causes the droplets to move slowly, reducing the probability of collision between droplets, and thus reducing the Oss ripening phenomenon between droplets. Therefore, compared with other systems with good fluidity, it can maintain a stable state for a long time.

[0093] Fig.16 This is a viscosity comparison chart of the pyraclostrobin emulsions in water (different surfactant contents and different shear times) prepared in Comparative Examples 1 to 4. The results show that the pyraclostrobin emulsions in water prepared with conventional surfactants such as AEO-3, EL-40, Tween-80, and 602 have lower viscosity values, all below 10.

[0094] From the above results, it can be seen that the use of P(AA / C 18 ) content, the longer the shearing time, the smaller the particle size D of the prepared hydrophobic drug aqueous emulsion 50 Through high-speed centrifugation, TSI, BS and other analysis, using 1% or 2% P(AA / C 18 ) prepared hydrophobic drug aqueous emulsion has good stability, and through the particle size test of samples after different storage time, it is found that the system is still uniform and stable after 40 days, and the particle size is below 6μm. The reason may be that P(AA / C 18 )The negative charge on the surface provides spatial electrostatic repulsion and its high viscosity maintains the stable state of the system, making the system have long-term stability.

[0095] Example 3

[0096] Take 10.2g of pyraclostrobin and dissolve it in 10.2g of methyl benzoate as the oil phase, and add 1g of P(AA / C 18 ) was added into ultrapure water as the aqueous phase (total 100 g), and then the aqueous phase was mixed with the oil phase and high-speed sheared at 5000 rpm for 15 min using a high-speed shearing machine to obtain a pyraclostrobin aqueous emulsion with a drug loading of 10 wt%.

[0097] Example 4

[0098] Take 20.4g of pyraclostrobin and dissolve it in 20.4g of methyl benzoate as the oil phase, and add 1g of P(AA / C 18 ) was added into ultrapure water as the aqueous phase (to a total of 100 g), and then the aqueous phase was mixed with the oil phase and high-speed sheared at 5000 rpm for 15 min using a high-speed shearing machine to obtain a pyraclostrobin aqueous emulsion with a drug loading of 20 wt%.

[0099] Test Example 3

[0100] Referring to the relevant test method in Test Example 2, the pyraclostrobin aqueous emulsion (P(AA / C 18 ) mass content is 1%, shear time is 15min), the pyraclostrobin emulsion in water with a drug loading of 10wt% prepared in Example 3 and the pyraclostrobin emulsion in water with a drug loading of 20wt% prepared in Example 4 were subjected to performance tests, as follows:

[0101] Fig.17 These are the appearance pictures of pyraclostrobin emulsions with different drug loadings before and after centrifugation (centrifugation at 3800 rpm for 10 min), with the left picture showing the appearance before centrifugation and the right picture showing the appearance after centrifugation. The results show that pyraclostrobin emulsions with different drug loadings remain milky and uniform after high-speed centrifugation, without any unstable phenomena such as stratification.

[0102] Fig.18 BS, TSI and particle size D of pyraclostrobin emulsions in water with different drug loadings 50 Test result diagram. Fig.18 A is the BS test result diagram, and B is the TSI test result diagram; the results show that the pyraclostrobin emulsions with different drug loadings are relatively stable, but with the increase of drug loading, the TSI value will show an increasing trend, which may be because the increase of oil phase makes P(AA / C 18 ) weakens its emulsifying ability. Fig.18 C is the particle size D 50The test results show that the particle size of the pyraclostrobin emulsion with a drug loading of 20% is the largest. However, compared with the pyraclostrobin emulsions with drug loadings of 5% and 10%, except for a significant increase in particle size in the first few days, the particle size did not increase significantly in the later period and tended to stabilize. After 40 days, the appearance of the three pyraclostrobin emulsions with different drug loadings remained uniform and stable.

[0103] Fig.19 The graph shows the viscosity test results of pyraclostrobin emulsions in water with different drug loadings. The results show that with the increase of drug loading, the viscosity of pyraclostrobin emulsions in water increases. Therefore, the increased viscosity plays an important role in maintaining high drug loading.

[0104] Fig. 20 The actual pictures and microscope images of pyraclostrobin emulsions in water with different drug loadings, with the actual picture on the left and the microscope image on the right. The results show that with the increase of drug loading, the droplets of pyraclostrobin emulsion in water become more aggregated and its fluidity becomes worse, thus maintaining the stability of the system.

[0105] The above results show that the present invention uses a lower content of P (AA / C 18 ) can be prepared into hydrophobic pesticide emulsions with different drug loading contents and can maintain the long-term stability of the system. Therefore, in the preparation of high-content drug loading systems, P(AA / C 18 ) has huge potential.

[0106] Test Example 4 Photodegradation Test

[0107] The pyraclostrobin aqueous emulsion with a drug loading of 5wt% prepared in Example 2 and Comparative Examples 1-4 (the surfactant mass content was 1% and the shearing time was 15min) was diluted 400 times with ultrapure water and placed in a stoppered quartz tube, a high-pressure mercury lamp was used as the light source, the quartz tube was 10cm away from the light source, the rotating motor was started and the dilution was stirred continuously to make the dilution evenly exposed to light, and the photolysis experiment was carried out after the photolysis instrument was stable. After different illumination times, 1mL of samples were taken, 3mL of methanol was added for dilution and dissolution, and the concentration (mg / L) of pyraclostrobin was detected by HPLC after passing through a 0.22μm filter membrane.

[0108] The photochemical degradation of pesticides in solution can be described by the first-order reaction kinetic equation. The photolysis kinetic equation and half-life calculation formula are shown in Formula I and Formula II:

[0109] C t =C0×e -kt Formula I;

[0110] T 1 / 2 =ln2 / k Formula II;

[0111] Among them Ct is the mass concentration of pyraclostrobin in the dilution at time t (mg / L), C0 is the initial mass concentration of pyraclostrobin (mg / L), k is the photolysis rate constant (min -1 ), T 1 / 2 is the photolysis half-life (min).

[0112] The first-order kinetic model was used to fit and analyze the photodegradation reaction of pyraclostrobin in pure water.

[0113] Fig.21 The photodegradation curves of the pyraclostrobin aqueous emulsion with a drug loading of 5 wt % prepared in Example 2 and Comparative Examples 1 to 4 after dilution are shown in Table 3.

[0114] Table 3 Photolysis kinetic equations of different samples under high pressure mercury lamp

[0115]

[0116] The results showed that the photodegradation reaction of pyraclostrobin conformed to the first-order reaction kinetic model (R 2 =0.987~0.998). Under high pressure mercury lamp irradiation, the ultraviolet photolysis half-life of pyraclostrobin aqueous emulsion prepared with Tween-80, AEO-9, 602, and EL-40 as surfactants were 0.138h, 0.121h, 0.136h, and 0.115h, respectively, while that with P(AA / C 18 The photolysis half-life of the pyraclostrobin emulsion prepared with P(AA / C) as the surfactant is 0.351 h, which is 2.54 to 3.05 times that of the pyraclostrobin emulsion prepared with the conventional surfactant. 18 ) as surfactant, can significantly reduce the photolysis rate of pyraclostrobin in water environment and improve its stability. Moreover, it can be known from the above results that the pyraclostrobin emulsions prepared using AEO-9, EL-40, 602, and Tween-80 as surfactants have no obvious difference in the decomposition rate of pyraclostrobin under ultraviolet light, proving that the above surfactants have no significant effect on the photodegradation rate when they are all emulsions, while the use of P(AA / C 18 The photolysis rate of pyraclostrobin emulsion prepared with ) as surfactant was significantly reduced under ultraviolet light irradiation, proving that it has the ability to resist ultraviolet light degradation.

[0117] Test Example 5 Acute toxicity test

[0118] This test example studies the acute toxicity of pyraclostrobin aqueous emulsions with a drug loading of 5 wt% (surfactant mass content is 1% and shear time is 15 min) prepared in Example 2 and Comparative Examples 1 to 4 to non-target organism zebrafish, as follows:

[0119] 3-5 month old zebrafish were used. Feeding was stopped 24 hours before the experiment. Ten zebrafish were placed in a fish tank filled with 3L of aerated water for testing. No feeding was given during the test. The pyraclostrobin aqueous emulsions (surfactant mass content was 1% and shearing time was 15min) with a drug loading of 5wt% prepared in Example 2 and Comparative Examples 1-4 were respectively formulated into reagents with pyraclostrobin concentrations of 0.1mg / L and 0.08mg / L to test the acute toxicity to zebrafish. Under the same conditions, a blank control experiment was carried out with blank aerated water. The experiment was repeated three times, and the mortality rate and poisoning symptoms of zebrafish were observed and recorded at different times.

[0120] Fig. 22 The results of the acute toxicity test of the pyraclostrobin aqueous emulsion prepared in Example 2 and Comparative Examples 1 to 4 on zebrafish at 0.1 mg / L and 0.08 mg / L pyraclostrobin concentrations are shown in the figure, with the left side at 0.1 mg / L and the right side at 0.08 mg / L. The results show that when the pyraclostrobin concentration is 0.1 mg / L, the use of P(AA / C 18 ) had lower acute toxicity than other samples, with a mortality rate of less than 50% at 24 hours. As time went on, the use of P(AA / C 18 ) had no significant difference in toxicity from other samples, indicating that the preparations prepared with P(AA / C 18 ) has the potential to reduce the toxicity level of pyraclostrobin within a certain period of time, and is expected to be 18 ) was used to reduce the toxicity of pyraclostrobin to zebrafish from acute toxicity to high toxicity. When the concentration of pyraclostrobin was 0.08 mg / L, the use of P(AA / C 18 ) had lower acute toxicity than other samples. As time went on, the use of P(AA / C 18 ) had no significant difference in toxicity from other samples.

[0121] The above results prove that the present invention adopts P(AA / C 18 ) can prepare hydrophobic pesticide emulsions, which can realize the feasibility of hydrophobic pesticide delivery and delayed pesticide release as well as reduce the pressure on the environment. 18 )'s high viscosity, strong emulsification and charge effect make the loaded hydrophobic pesticide have high drug loading and excellent stability. Compared with the drug loading system prepared by conventional surfactants, the use of P(AA / C 18) can significantly improve the photostability of hydrophobic drugs and reduce their acute toxicity to non-target aquatic organisms such as zebrafish. 18 ) is expected to become an ideal carrier for pesticide sustained-release preparations and has broad application prospects in the field of pesticide loading and sustained-release.

[0122] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An alkyl-modified polyacrylic acid loaded hydrophobic pesticide aqueous emulsion, the raw materials for preparation are alkyl-modified polyacrylic acid, hydrophobic pesticide, organic solvent and water, the mass content of alkyl-modified polyacrylic acid in the alkyl-modified polyacrylic acid loaded hydrophobic pesticide aqueous emulsion is 0.5-2%, and the mass content of hydrophobic pesticide is 5-50%; the raw materials for preparation of the alkyl-modified polyacrylic acid include polyacrylic acid, alkylamine, N,N'-dicyclohexylcarbodiimide and N-methylpyrrolidone; the molar ratio of the polyacrylic acid to the alkylamine is 100:1-5; The number average molecular weight of the polyacrylic acid is 50,000 to 700,000; the alkylamine is one or more of dodecylamine, pentadecylamine, hexadecylamine and octadecylamine; The preparation method of the alkyl-modified polyacrylic acid comprises the following steps: The raw materials for preparing the alkyl-modified polyacrylic acid are mixed and subjected to an amidation reaction to obtain the alkyl-modified polyacrylic acid; The hydrophobic pesticide is pyraclostrobin.

2. The alkyl-modified polyacrylic acid-loaded hydrophobic pesticide aqueous emulsion according to claim 1, characterized in that: The temperature of the amidation reaction is 50-70° C. and the time is 12-24 hours.

3. The alkyl-modified polyacrylic acid-loaded hydrophobic pesticide aqueous emulsion according to claim 1, characterized in that: The organic solvent includes one or more of methyl benzoate, cyclohexanone and dimethyl sulfoxide.

4. The alkyl-modified polyacrylic acid-loaded hydrophobic pesticide aqueous emulsion according to claim 1, characterized in that: The particle size of the droplets in the alkyl-modified polyacrylic acid-loaded hydrophobic pesticide aqueous emulsion is 1-10 μm.

5. A method for preparing the alkyl-modified polyacrylic acid-loaded hydrophobic pesticide aqueous emulsion according to any one of claims 1 to 4, comprising the following steps: mixing a hydrophobic pesticide with an organic solvent to obtain an oil phase; mixing the alkyl-modified polyacrylic acid with water to obtain an aqueous phase; The oil phase is mixed with the water phase, and an emulsification loading treatment is performed under shearing conditions to obtain the alkyl-modified polyacrylic acid loaded hydrophobic pesticide aqueous emulsion.

6. The preparation method according to claim 5, characterized in that: The shearing speed is 1000-7000 rpm; the emulsification loading treatment time is 2-30 min.

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