Slow-release mixed preparation based on difenoconazole and preparation method thereof

Abstract

The invention relates to the technical field of pesticides, in particular to a slow-release mixed preparation based on difenoconazole and a preparation method thereof. The preparation method of the mixed preparation comprises the following steps: preparing a modified lignin coating solvent; preparing a humic acid light stabilizer; and mixing and compounding the sustained-release preparation. According to the invention, ester functional monomer molecules are introduced into a basic structure of lignin, and after pesticide active molecules are subsequently encapsulated, oxidation resistance and photolysis resistance of lignin can be provided for a slow-release mixed preparation based on difenoconazole; and the slow hydrolysis performance of ester functional monomer molecules in the environment can be matched with lignin to slowly release the pesticide, so that the pesticide active molecules are prevented from being damaged due to large-area exposure in the environment, the pesticide active molecules can act on crops for a long time, and the long-acting and stable sterilization capability is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of pesticides, and in particular to a difenoconazole-based sustained-release mixed preparation and a preparation method thereof. Background Art

[0002] Flusilazole is a fungicide widely used in agriculture, especially for preventing and controlling fungal diseases of crops. It has strong antibacterial effect and high selectivity, and can effectively reduce the occurrence of crop diseases. However, there are some limitations in the application of flusilazole, especially its poor environmental stability and susceptibility to degradation due to factors such as light and temperature, which leads to its rapid ineffectiveness in soil and water environments. This not only reduces its fungicidal effect, but also may cause environmental pollution.

[0003] In order to overcome this problem, researchers have proposed to extend the shelf life and stability of fenpropimorph through sustained-release preparations. Sustained-release preparations use special carriers and controlled release mechanisms to enable the drug to be continuously released over a long period of time, thereby improving the utilization rate of the drug and reducing environmental pollution. Existing sustained-release preparations mostly use synthetic polymer materials or natural polymer substances as coating carriers. Synthetic polymer materials have the problem of rapid degradation and poor environmental friendliness. Although natural polymer materials, such as lignin, have good biodegradability and environmental adaptability, due to their complex structure, the effect and stability of encapsulation of active pesticide molecules still need to be improved. Moreover, the above-mentioned coating carriers can only protect the active pesticide molecules during coating. Once the active pesticide molecules are released from the carrier, they are still prone to photodegradation under sunlight. Summary of the invention

[0004] In order to solve the above technical defects, the present invention has developed a method for preparing a difenoconazole-based sustained-release mixed preparation which combines sodium lignin sulfonate and ester functional monomer molecules as pesticide active molecule coating wall materials, and simultaneously prepares a humic acid light stabilizer and a pesticide active molecule composite. The prepared difenoconazole-based sustained-release mixed preparation has excellent sustained-release stability and anti-photolysis ability.

[0005] A method for preparing a sustained-release mixed preparation based on difenoconazole comprises the following steps: S1: Preparation of modified lignin coating solvent Prepare N,N-dimethylformamide solution, add sodium lignin sulfonate and stir to obtain sodium lignin sulfonate solution, dissolve 2-hydroxyethyl acrylic acid in N,N-dimethylformamide and then drip into the sodium lignin sulfonate solution, then add pyridine and stir to stand, extract the supernatant with isopropanol, then centrifuge and filter to obtain solid precipitate I, dry to obtain esterified sodium lignin sulfonate, ultrasonically disperse the esterified sodium lignin sulfonate in ethanol aqueous solution, add acrylic acid, 3-mercaptopropionic acid, hydrogen peroxide and ascorbic acid in sequence and stir to obtain a uniform mixture, add sodium dodecyl sulfate after heating and heat preservation to obtain a modified lignin coating solvent; S2: Preparation of Humic Acid Light Stabilizer Sodium humate, Zn(NO 3 ) 2 6H 2 O and terephthalic acid are dispersed in acetonitrile / N, N-dimethylformamide solution respectively to obtain terephthalic acid solution, sodium humate dispersion and zinc nitrate solution, which are then added into a tubular container in sequence to form a three-layer solution, and after heating treatment, centrifugal filtration is performed to obtain solid precipitate II, which is then washed and dried to obtain esterified sodium lignin sulfonate; S3: Compounding of sustained-release preparations Humic acid light stabilizer and difenoconazole are added to dichloromethane and magnetic stirring is performed to obtain a difenoconazole organic solution, which is then dropped into a modified lignin coating solvent, epichlorohydrin is added for homogenization, and then intermittent ultrasonic treatment is performed. After heating and stirring, a dispersant is added and stirred to obtain a difenoconazole-based sustained-release mixed preparation.

[0006] Furthermore, the preparation of the modified lignin coating solvent in step S1 comprises the following steps: S1.1: 1-1.5 parts by weight of N, N-dimethylformamide and 15-20 parts by weight of deionized water are mixed in a container and stirred for 8-10 minutes to obtain an N, N-dimethylformamide solution. 2-3 parts by weight of sodium lignin sulfonate are added to the N, N-dimethylformamide solution, and then the temperature is raised to 85-90°C and stirred until the sodium lignin sulfonate is completely dissolved. After naturally cooling to room temperature, nitrogen is introduced for protection to obtain a sodium lignin sulfonate solution. 1-1.2 parts by weight of 2-hydroxyethyl acrylic acid is dissolved in 4-5 parts by weight of N, N-dimethylformamide to obtain a 2-hydroxyethyl acrylic acid solution. The 2-hydroxyethyl olefine ester solution is added to the sodium lignin sulfonate solution, and then 1.5-2 parts by weight of pyridine is added, and the mixture is stirred at a temperature of 50-60° C. for 6-8 hours and at a stirring speed of 6000-7500 rpm for 4-6 minutes. After standing for stratification, the supernatant is filtered to obtain a supernatant, and the supernatant is mixed with isopropanol at a volume ratio of 1:(20-25) and then placed in a centrifuge for centrifugation at a centrifugal speed of 8000-10000 rpm for 5-6 minutes, and solid precipitate I is filtered to obtain a solid precipitate, which is rinsed with isopropanol 2-3 times and placed in a vacuum drying oven for drying at 40-45° C. to obtain esterified sodium lignin sulfonate; S1.2: The esterified sodium lignin sulfonate prepared in step S1.1 and an ethanol aqueous solution with a concentration of 30-35% are mixed in a mass ratio of 1: (8-10) and placed in an ultrasonic disperser, and ultrasonic treatment is performed at an ultrasonic frequency of 20-25 kHz for 15-20 minutes to obtain an esterified sodium lignin sulfonate solution, and acrylic acid is added to the esterified sodium lignin sulfonate solution at a molar mass ratio of 1: (0.28-0.32) to the esterified sodium lignin sulfonate, and then 3-mercaptopropionic acid, hydrogen peroxide and ascorbic acid are added. After stirring evenly, the temperature is raised to 40-45°C, and after keeping warm for 4-5 hours, 2-3wt% of sodium dodecyl sulfate is added, and the modified lignin coating solvent is obtained after high-speed stirring.

[0007] Furthermore, the preparation of the humic acid light stabilizer in step S2 comprises the following steps: S2.1: 0.6-0.8 parts by weight of sodium humate and 10-12 parts by weight of acetonitrile / N,N-dimethylformamide solution are placed in an ultrasonic disperser and ultrasonically dispersed at an ultrasonic frequency of 25-30 kHz for 10-15 minutes to obtain a sodium humate dispersion. 2.5-3 parts by weight of Zn(NO 3 ) 2 6H 2 O and 15-18 parts by weight of acetonitrile / N,N-dimethylformamide solution were mixed in a container and stirred until Zn(NO 3 ) 2 6H 2O is completely dissolved to obtain a zinc nitrate solution, and 5-6 parts by weight of terephthalic acid is dissociated into 15-18 parts by weight of acetonitrile / N,N-dimethylformamide solution to obtain a terephthalic acid solution; S2.2: The terephthalic acid solution obtained in step S2.1 is first placed at the bottom of a tubular container, and then the sodium humate dispersion obtained in step S2.1 is slowly added along the inner wall of the container, and finally the zinc nitrate solution obtained in step S2.1 is slowly added along the inner wall of the container to form a three-layer solution. The tubular container is placed in an oven and allowed to stand at 40-45°C for 45-48 hours, and then placed in a centrifuge for centrifugation and suction filtration to obtain solid precipitate II, which is washed 3-4 times with N,N-dimethylformamide and then dried at 80-85°C to obtain a humic acid light stabilizer.

[0008] Furthermore, step S3 of compounding the sustained-release preparation comprises the following steps: S3.1: 10-15 parts by weight of dichloromethane is placed in a container, 3-4 parts by weight of a humic acid light stabilizer and 2-3 parts by weight of difenoconazole are added, and magnetic stirring is performed at a stirring speed of 400-500 rpm until the difenoconazole is completely dissolved to obtain a difenoconazole organic solution; S3.2: Under stirring at 1000-1200rpm, 4-5 parts by weight of the difenoconazole organic solution are dropped into 15-20 parts by weight of the modified lignin coating solvent, and then 0.5-0.6 parts by weight of epichlorohydrin are added, and homogenized at a speed of 18000-20000rpm for 1.5-2 minutes using a homogenizer, and then placed in an ultrasonic cell crusher for intermittent ultrasonic treatment at a power of 200-220W for 2-2.5 minutes to obtain an ultrasonic emulsion, and the ultrasonic emulsion is placed in an environment of 50-55°C and stirred at a speed of 450-500rpm for 2-3 hours, and then 1-2wt% of styrylphenol polyoxyethylene ether dispersant is added, and stirred at room temperature for 1-1.5 hours to obtain a sustained-release mixed preparation based on difenoconazole.

[0009] Furthermore, the 3-mercaptopropionic acid, hydrogen peroxide and ascorbic acid added in step S1.2 account for 0.6-0.8%, 0.4-0.5% and 0.7-0.9% of the mass fraction of the esterified sodium lignin sulfonate, respectively.

[0010] Furthermore, the acetonitrile / N,N-dimethylformamide solution in step S2.1 is prepared by mixing acetonitrile and N,N-dimethylformamide solution in a volume ratio of 1:(1-1.5).

[0011] Furthermore, the intermittent ultrasonic treatment in step S3.2 is performed by ultrasonicating for 2-3 seconds and pausing for 2-3 seconds.

[0012] A difenoconazole-based sustained-release mixed preparation is prepared by the above-mentioned method for preparing a difenoconazole-based sustained-release mixed preparation.

[0013] The beneficial effects are as follows: 1. The present invention mixes a 2-hydroxyethyl acrylic acid ester solution with a sodium lignin sulfonate solution, adds pyridine and stirs at a temperature of 50-60°C to combine 2-hydroxyethyl acrylic acid and sodium lignin sulfonate to generate esterified sodium lignin sulfonate, places the prepared esterified sodium lignin sulfonate and acrylic acid in a reduction system of hydrogen peroxide and ascorbic acid, adds 3-mercaptopropionic acid as a chain transfer agent, and causes the esterified sodium lignin sulfonate and acrylic acid to undergo a free radical polymerization reaction, and on the basis of lignin The introduction of ester functional monomer molecules into the structure, after the subsequent encapsulation of the active pesticide molecules, can not only provide the anti-oxidation and anti-photolysis capabilities of lignin for the sustained-release mixed formulation based on difenoconazole, but the slow hydrolysis performance of the ester functional monomer molecules in the environment can cooperate with lignin to slow-release the pesticide, thereby enhancing the sustained-release effect of the sustained-release mixed formulation based on difenoconazole, avoiding the destruction of the active pesticide molecules due to large-scale exposure to the environment, and allowing the active pesticide molecules to act on crops for a long time, thereby having a long-lasting and stable bactericidal ability.

[0014] 2. The present invention combines sodium humate, Zn(NO 3 ) 2 6H 2 O and terephthalic acid are dispersed in acetonitrile / N,N-dimethylformamide solution respectively to obtain terephthalic acid solution, sodium humate dispersion and zinc nitrate solution, which are then added into a tubular container in sequence to obtain a three-layer solution with terephthalic acid solution at the bottom, sodium humate dispersion in the middle and zinc nitrate solution at the top. At this time, the temperature is increased to obtain Zn(NO 3 ) 2 6H 2 O and terephthalic acid diffuse into the sodium humate dispersion in the middle to react. Humic acid is introduced while generating the zinc-based organic metal framework, which can provide a large number of oxygen-containing functional groups and adsorption sites for the zinc-based organic metal framework, and can not only effectively adsorb the subsequent fenpropimorph active molecules, but also humic acid can cooperate with zinc metal to absorb light in a wider wavelength range. Humic acid can also serve as an effective free radical quencher or inhibit the photochemical reaction process through the light shielding effect, and can be released from the wall material together with the fenpropimorph active molecules, thereby inhibiting the photodegradation behavior of the fenpropimorph active molecules, so that the fenpropimorph active molecules can continuously and effectively kill harmful bacteria, thereby improving the use effect of the sustained-release mixed preparation based on fenpropimorph.

[0015] 3. The present invention drips the prepared difenoconazole organic solution into the modified lignin coating solvent, then adds the cross-linking agent epichlorohydrin, and performs intermittent ultrasonic treatment after homogenization by a homogenizer. The intermittent ultrasonic treatment can not only reduce the impact on the coating material and avoid structural damage, but also avoid uneven coating of the material due to continuous mechanical force, thereby enhancing the sustained release effect of the difenoconazole-based sustained-release mixed preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The present invention is a flow chart of a method for preparing a sustained-release mixed preparation based on difenoconazole used in an embodiment of the present invention. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0018] Example 1 A method for preparing a sustained-release mixed preparation based on difenoconazole, such as Figure 1 As shown, the following steps are included: S1: Preparation of modified lignin coating solvent S1.1: 1 part by weight of N,N-dimethylformamide and 15 parts by weight of deionized water are mixed in a container and stirred for 8 minutes to obtain an N,N-dimethylformamide solution. 2 parts by weight of sodium lignin sulfonate are added to the N,N-dimethylformamide solution, and then the temperature is raised to 85°C and stirred until the sodium lignin sulfonate is completely dissolved. After naturally cooling to room temperature, nitrogen is introduced for protection to obtain a sodium lignin sulfonate solution. 1 part by weight of 2-hydroxyethyl acrylic acid is dissolved in 4 parts by weight of N,N-dimethylformamide to obtain 2-hydroxyethyl acrylic acid. solution, adding the acrylic acid-2-hydroxyethyl ester solution to the sodium lignin sulfonate solution, and then adding 1.5 parts by weight of pyridine, stirring at a temperature of 50°C for 6 hours and then stirring at a stirring speed of 6000 rpm for 4 minutes, standing for stratification and then filtering to obtain a supernatant, mixing the supernatant with isopropanol at a volume ratio of 1:20, and then centrifuging in a centrifuge at a centrifugal speed of 8000 rpm for 5 minutes, filtering to obtain a solid precipitate I, washing it twice with isopropanol, and then placing it in a vacuum drying oven, and drying it at 40°C to obtain esterified sodium lignin sulfonate; S1.2: The esterified sodium lignin sulfonate prepared in step S1.1 and a 30% ethanol aqueous solution are mixed in a mass ratio of 1:8 and placed in an ultrasonic disperser. Ultrasonic treatment is performed at an ultrasonic frequency of 20 kHz for 15 minutes to obtain an esterified sodium lignin sulfonate solution. Acrylic acid is added to the esterified sodium lignin sulfonate solution in a molar mass ratio of 1:0.28 to the esterified sodium lignin sulfonate, and then 3-mercaptopropionic acid, hydrogen peroxide and ascorbic acid are added, wherein 3-mercaptopropionic acid, hydrogen peroxide and ascorbic acid account for 0.6%, 0.4% and 0.7% of the mass fraction of the esterified sodium lignin sulfonate, respectively. After stirring evenly, the temperature is raised to 40°C. After keeping warm for 4 hours, 2wt% of sodium dodecyl sulfate is added, and the modified lignin coating solvent is obtained after high-speed stirring.

[0019] S2: Preparation of Humic Acid Light Stabilizer S2.1: 0.6 parts by weight of sodium humate and 10 parts by weight of acetonitrile / N,N-dimethylformamide solution were placed in an ultrasonic disperser and ultrasonically dispersed at an ultrasonic frequency of 25 kHz for 10 minutes to obtain a sodium humate dispersion. 2.5 parts by weight of Zn(NO 3 ) 2 6H 2 O and 15 parts by weight of acetonitrile / N,N-dimethylformamide solution were mixed in a container and stirred until Zn(NO 3 ) 2 6H 2 O is completely dissolved to obtain a zinc nitrate solution, 5 parts by weight of terephthalic acid is dissociated into 15 parts by weight of acetonitrile / N,N-dimethylformamide solution to obtain a terephthalic acid solution, wherein the acetonitrile / N,N-dimethylformamide solution is prepared by preparing acetonitrile and N,N-dimethylformamide solution in a volume ratio of 1:1; S2.2: The terephthalic acid solution obtained in step S2.1 is first placed at the bottom of a tubular container, and then the sodium humate dispersion obtained in step S2.1 is slowly added along the inner wall of the container, and finally the zinc nitrate solution obtained in step S2.1 is slowly added along the inner wall of the container to form a three-layer solution. The tubular container is placed in an oven and allowed to stand at 40°C for 45 hours, and then placed in a centrifuge for centrifugation and suction filtration to obtain solid precipitate II, which is washed three times with N,N-dimethylformamide and dried at 80°C to obtain a humic acid light stabilizer.

[0020] S3: Compounding of sustained-release preparations S3.1: 10 parts by weight of dichloromethane are placed in a container, 3 parts by weight of a humic acid light stabilizer and 2 parts by weight of difenoconazole are added, and magnetic stirring is performed at a stirring speed of 400 rpm until the difenoconazole is completely dissolved to obtain a difenoconazole organic solution; S3.2: Under stirring at 1000rpm, 4 parts by weight of the fenpropimorph organic solution are dropped into 15 parts by weight of the modified lignin coating solvent, and then 0.5 parts by weight of epichlorohydrin are added, and homogenized at a speed of 18000rpm for 1.5 minutes using a homogenizer, and then placed in an ultrasonic cell crusher for intermittent ultrasonic treatment at a power of 200W for 2 minutes. The intermittent ultrasonic treatment method is ultrasonic for 2S and pause for 2S to obtain an ultrasonic emulsion. The ultrasonic emulsion is placed in an environment of 50°C and stirred at a speed of 450rpm for 2 hours, and then 1wt% of styrylphenol polyoxyethylene ether dispersant is added and stirred at room temperature for 1 hour to obtain a sustained-release mixed preparation based on fenpropimorph.

[0021] Example 2 A method for preparing a sustained-release mixed preparation based on difenoconazole, such as Figure 1 As shown, the following steps are included: S1: Preparation of modified lignin coating solvent S1.1: 1.5 parts by weight of N, N-dimethylformamide and 20 parts by weight of deionized water are mixed in a container and stirred for 8 minutes to obtain an N, N-dimethylformamide solution. 3 parts by weight of sodium lignin sulfonate are added to the N, N-dimethylformamide solution, and then the temperature is raised to 85°C and stirred until the sodium lignin sulfonate is completely dissolved. After cooling naturally to room temperature, nitrogen is introduced for protection to obtain a sodium lignin sulfonate solution. 1.2 parts by weight of 2-hydroxyethyl acrylic acid is dissolved in 5 parts by weight of N, N-dimethylformamide to obtain 2-hydroxyethyl acrylic acid. ethyl ester solution, adding acrylic acid-2-hydroxyethyl ester solution to sodium lignin sulfonate solution, and then adding 2 parts by weight of pyridine, stirring at a temperature of 50°C for 6 hours and then stirring at a stirring speed of 6000 rpm for 4 minutes, standing for stratification and then filtering to obtain a supernatant, mixing the supernatant with isopropanol at a volume ratio of 1:20, and then centrifuging in a centrifuge at a centrifugal speed of 8000 rpm for 5 minutes, filtering to obtain a solid precipitate I, washing it twice with isopropanol, and then placing it in a vacuum drying oven, and drying it at 40°C to obtain esterified sodium lignin sulfonate; S1.2: The esterified sodium lignin sulfonate prepared in step S1.1 and a 30% ethanol aqueous solution are mixed in a mass ratio of 1:10 and placed in an ultrasonic disperser. Ultrasonic treatment is performed at an ultrasonic frequency of 20 kHz for 15 minutes to obtain an esterified sodium lignin sulfonate solution. Acrylic acid is added to the esterified sodium lignin sulfonate solution in a molar mass ratio of 1:0.32 to the esterified sodium lignin sulfonate, and then 3-mercaptopropionic acid, hydrogen peroxide and ascorbic acid are added, wherein 3-mercaptopropionic acid, hydrogen peroxide and ascorbic acid account for 0.8%, 0.5% and 0.9% of the mass fraction of the esterified sodium lignin sulfonate, respectively. After stirring evenly, the temperature is raised to 40°C. After keeping warm for 4 hours, 2wt% of sodium dodecyl sulfate is added, and the modified lignin coating solvent is obtained after high-speed stirring.

[0022] S2: Preparation of Humic Acid Light Stabilizer S2.1: 0.8 parts by weight of sodium humate and 12 parts by weight of acetonitrile / N,N-dimethylformamide solution were placed in an ultrasonic disperser and ultrasonically dispersed at an ultrasonic frequency of 25 kHz for 10 minutes to obtain a sodium humate dispersion. 3 parts by weight of Zn(NO 3 ) 2 6H 2 O and 18 parts by weight of acetonitrile / N,N-dimethylformamide solution were mixed in a container and stirred until Zn(NO 3 ) 2 6H 2 O is completely dissolved to obtain a zinc nitrate solution, 6 parts by weight of terephthalic acid is dissociated into 18 parts by weight of acetonitrile / N,N-dimethylformamide solution to obtain a terephthalic acid solution, wherein the acetonitrile / N,N-dimethylformamide solution is prepared by acetonitrile and N,N-dimethylformamide solution in a volume ratio of 1:1.5; S2.2: The terephthalic acid solution obtained in step S2.1 is first placed at the bottom of a tubular container, and then the sodium humate dispersion obtained in step S2.1 is slowly added along the inner wall of the container, and finally the zinc nitrate solution obtained in step S2.1 is slowly added along the inner wall of the container to form a three-layer solution. The tubular container is placed in an oven and allowed to stand at 40°C for 45 hours, and then placed in a centrifuge for centrifugation and suction filtration to obtain solid precipitate II, which is washed three times with N,N-dimethylformamide and dried at 80°C to obtain a humic acid light stabilizer.

[0023] S3: Compounding of sustained-release preparations S3.1: 15 parts by weight of dichloromethane are placed in a container, 4 parts by weight of a humic acid light stabilizer and 3 parts by weight of difenoconazole are added, and magnetic stirring is performed at a stirring speed of 400 rpm until the difenoconazole is completely dissolved to obtain a difenoconazole organic solution; S3.2: Under stirring at 1000rpm, 5 parts by weight of the fenpropimorph organic solution are dropped into 20 parts by weight of the modified lignin coating solvent, and then 0.6 parts by weight of epichlorohydrin are added, and homogenized at a speed of 18000rpm for 1.5 minutes using a homogenizer, and then placed in an ultrasonic cell crusher for intermittent ultrasonic treatment at a power of 200W for 2 minutes. The intermittent ultrasonic treatment is carried out in a manner of ultrasonicating for 2S and pausing for 2S to obtain an ultrasonic emulsion. The ultrasonic emulsion is placed in an environment of 50°C and stirred at a speed of 450rpm for 2 hours, and then 2wt% of styrylphenol polyoxyethylene ether dispersant is added and stirred at room temperature for 1 hour to obtain a sustained-release mixed preparation based on fenpropimorph.

[0024] Example 3 A method for preparing a sustained-release mixed preparation based on difenoconazole, such as Figure 1 As shown, the following steps are included: S1: Preparation of modified lignin coating solvent S1.1: 1 part by weight of N,N-dimethylformamide and 15 parts by weight of deionized water are mixed in a container and stirred for 8 minutes to obtain an N,N-dimethylformamide solution. 2 parts by weight of sodium lignin sulfonate are added to the N,N-dimethylformamide solution, and then the temperature is raised to 90°C and stirred until the sodium lignin sulfonate is completely dissolved. After naturally cooling to room temperature, nitrogen is introduced for protection to obtain a sodium lignin sulfonate solution. 1 part by weight of 2-hydroxyethyl acrylic acid is dissolved in 4 parts by weight of N,N-dimethylformamide to obtain 2-hydroxyethyl acrylic acid. solution, adding the acrylic acid-2-hydroxyethyl ester solution to the sodium lignin sulfonate solution, and then adding 1.5 parts by weight of pyridine, stirring at a temperature of 60°C for 8 hours and then stirring at a stirring speed of 7500 rpm for 6 minutes, standing for stratification and then filtering to obtain a supernatant, mixing the supernatant with isopropanol at a volume ratio of 1:25, and then centrifuging in a centrifuge at a centrifugal speed of 10000 rpm for 6 minutes, filtering to obtain a solid precipitate I, washing it with isopropanol 3 times, and then placing it in a vacuum drying oven, and drying it at 45°C to obtain esterified sodium lignin sulfonate; S1.2: The esterified sodium lignin sulfonate prepared in step S1.1 and a 35% ethanol aqueous solution are mixed in a mass ratio of 1:8 and placed in an ultrasonic disperser. Ultrasonic treatment is performed at an ultrasonic frequency of 25 kHz for 20 minutes to obtain an esterified sodium lignin sulfonate solution. Acrylic acid is added to the esterified sodium lignin sulfonate solution in a molar mass ratio of 1:0.28 to the esterified sodium lignin sulfonate, and then 3-mercaptopropionic acid, hydrogen peroxide and ascorbic acid are added, wherein 3-mercaptopropionic acid, hydrogen peroxide and ascorbic acid account for 0.6%, 0.4% and 0.7% of the mass fraction of the esterified sodium lignin sulfonate, respectively. After stirring evenly, the temperature is raised to 45°C. After keeping warm for 5 hours, 2wt% of sodium dodecyl sulfate is added, and the modified lignin coating solvent is obtained after high-speed stirring.

[0025] S2: Preparation of Humic Acid Light Stabilizer S2.1: 0.6 parts by weight of sodium humate and 10 parts by weight of acetonitrile / N,N-dimethylformamide solution were placed in an ultrasonic disperser and ultrasonically dispersed at an ultrasonic frequency of 30 kHz for 15 minutes to obtain a sodium humate dispersion. 2.5 parts by weight of Zn(NO 3 ) 2 6H 2 O and 15 parts by weight of acetonitrile / N,N-dimethylformamide solution were mixed in a container and stirred until Zn(NO 3 ) 2 6H 2 O is completely dissolved to obtain a zinc nitrate solution, 5 parts by weight of terephthalic acid is dissociated into 15 parts by weight of acetonitrile / N,N-dimethylformamide solution to obtain a terephthalic acid solution, wherein the acetonitrile / N,N-dimethylformamide solution is prepared by preparing acetonitrile and N,N-dimethylformamide solution in a volume ratio of 1:1.5; S2.2: The terephthalic acid solution obtained in step S2.1 is first placed at the bottom of a tubular container, and then the sodium humate dispersion obtained in step S2.1 is slowly added along the inner wall of the container, and finally the zinc nitrate solution obtained in step S2.1 is slowly added along the inner wall of the container to form a three-layer solution. The tubular container is placed in an oven and allowed to stand at 45°C for 48 hours, and then placed in a centrifuge for centrifugation and suction filtration to obtain solid precipitate II, which is washed four times with N,N-dimethylformamide and dried at 85°C to obtain a humic acid light stabilizer.

[0026] S3: Compounding of sustained-release preparations S3.1: 10 parts by weight of dichloromethane are placed in a container, 3 parts by weight of a humic acid light stabilizer and 2 parts by weight of difenoconazole are added, and magnetic stirring is performed at a stirring speed of 500 rpm until the difenoconazole is completely dissolved to obtain a difenoconazole organic solution; S3.2: Under stirring at 1200rpm, 4 parts by weight of the fenpropimorph organic solution are dropped into 15 parts by weight of the modified lignin coating solvent, and then 0.5 parts by weight of epichlorohydrin are added, and homogenized at 20,000rpm for 2 minutes using a homogenizer, and then placed in an ultrasonic cell crusher for intermittent ultrasonic treatment at a power of 220W for 2.5 minutes. The intermittent ultrasonic treatment is performed in the form of ultrasonication for 3S and pause for 3S to obtain an ultrasonic emulsion. The ultrasonic emulsion is placed in an environment of 50°C and stirred at a speed of 500rpm for 3 hours, and then 1wt% of styrylphenol polyoxyethylene ether dispersant is added and stirred at room temperature for 1.5 hours to obtain a sustained-release mixed preparation based on fenpropimorph.

[0027] Comparative Example 1 Compared with Example 1, the difference of Comparative Example 1 is that Comparative Example 1 removes step S1, replaces the modified lignin coating solvent in step S3.2 with an aqueous solution of sodium lignin sulfonate with an equal mass concentration of 11%, and the remaining steps are the same as those in Example 1. The obtained sustained-release mixed preparation based on difenoconazole is recorded as Comparative Example 1.

[0028] Comparative Example 2 Compared with Example 1, the difference of Comparative Example 2 is that step S2 is removed in Comparative Example 2, and humic acid light stabilizer is not added in step S3.1. The remaining steps are the same as those in Example 1. The obtained sustained-release mixed preparation based on difenoconazole is recorded as Comparative Example 2.

[0029] Comparative Example 3 Compared with Example 1, the difference of Comparative Example 3 is that the intermittent ultrasonic treatment in step S3.2 is replaced by a continuous ultrasonic treatment, and the remaining steps are the same as those in Example 1. The obtained sustained-release mixed preparation based on difenoconazole is recorded as Comparative Example 3.

[0030] Experiment 1: Take the difenoconazole-based sustained-release mixed preparations prepared in Examples 1-3, Comparative Example 1 and Comparative Example 3 of equal mass, take five portions respectively for drying to obtain microcapsule particle samples, then weigh and record as M0, and then wrap them in filter bags and place them in containers, and carry out natural sustained release at 25° C., rinse with distilled water for 6 minutes every 12 hours, and weigh the microcapsule particles after drying every other week, record as M1, and calculate the weight loss rate = (M0-M1) / M0×100%, and then calculate the average weight loss rate of the five microcapsule particle samples, continue to carry out the experiment for 7 weeks with the same experimental standard, record the data and make a table, as shown in Table 1; It can be seen from Table 1 that the weight loss rates of Examples 1-3 are all less than that of Comparative Example 1, which can prove that the introduction of ester functional monomer molecules into the basic structure of lignin can greatly enhance the sustained release effect of the sustained release mixed formulation based on difenoconazole. It can also be proved that intermittent ultrasonic treatment can avoid uneven material coating caused by continuous mechanical force, thereby enhancing the sustained release effect of the sustained release mixed formulation based on difenoconazole.

[0031] Table 1: Average weight loss rate of microcapsule granule samples over 7 weeks

[0032] Experiment 2: Take the same mass of the difenoconazole-based sustained-release mixed preparations prepared in Examples 1-3 and Comparative Example 2, place them in a well plate, cover them with a transparent film, and then irradiate them under a UV lamp (38W, wavelength 254nm), take samples after 12h, 24h, 36h, and 72h, analyze the content of difenoconazole by high pressure liquid chromatography, and calculate the photodecomposition rate of difenoconazole at 12h, 24h, 36h, and 72h, record the data and make a table, as shown in Table 2; It can be seen from Table 2 that under the light simulation environment, the decomposition rates of the difenoconazole-based sustained-release mixed preparations prepared in Examples 1-3 at 12 h, 24 h, 36 h, and 72 h are all lower than those in Comparative Example 2, which proves that the introduction of humic acid while generating a zinc-based organic metal framework can cooperate with zinc metal to absorb light in a wider wavelength range, thereby inhibiting the photodegradation behavior of the difenoconazole active molecules.

[0033] Table 2: Photodecomposition rate of difenoconazole

[0034] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for preparing a sustained-release mixed preparation based on difenoconazole, characterized in that: The following steps are involved: S1 Preparation of modified lignin coating solvent: Prepare N,N-dimethylformamide solution, add sodium lignin sulfonate and stir to obtain sodium lignin sulfonate solution, dissolve 2-hydroxyethyl acrylic acid in N,N-dimethylformamide and then drip into the sodium lignin sulfonate solution, then add pyridine and stir to stand, extract the supernatant with isopropanol, then centrifuge and filter to obtain solid precipitate I, dry to obtain esterified sodium lignin sulfonate, ultrasonically disperse the esterified sodium lignin sulfonate in ethanol aqueous solution, add acrylic acid, 3-mercaptopropionic acid, hydrogen peroxide and ascorbic acid in sequence and stir to obtain a modified lignin coating solvent; Preparation of S2 humic acid light stabilizer: Sodium humate, Zn(NO3)2·6H2O and terephthalic acid are dispersed in acetonitrile / N,N-dimethylformamide solution respectively to obtain terephthalic acid solution, sodium humate dispersion and zinc nitrate solution, which are then added into a tubular container in sequence to form a three-layer solution. After heating treatment, solid precipitate II is obtained by centrifugation and filtration, which is then washed and dried to obtain esterified sodium lignin sulfonate. S3 mixed compounding of sustained-release preparation: humic acid light stabilizer and difenoconazole are added to dichloromethane and magnetically stirred to obtain a difenoconazole organic solution, which is then dropped into a modified lignin coating solvent, epichlorohydrin is added for homogenization, and then intermittent ultrasonic treatment is performed. After heating and stirring, a dispersant is added and stirred to obtain a sustained-release mixed preparation based on difenoconazole.

2. The method for preparing a sustained-release mixed preparation based on difenoconazole according to claim 1, characterized in that: Step S1: Preparation of modified lignin coating solvent, comprising the following steps: S1.1: 1-1.5 parts by weight of N, N-dimethylformamide and 15-20 parts by weight of deionized water are mixed in a container and stirred for 8-10 minutes to obtain an N, N-dimethylformamide solution. 2-3 parts by weight of sodium lignin sulfonate are added to the N, N-dimethylformamide solution, and then the temperature is raised to 85-90°C and stirred until the sodium lignin sulfonate is completely dissolved. After naturally cooling to room temperature, nitrogen is introduced for protection to obtain a sodium lignin sulfonate solution. 1-1.2 parts by weight of 2-hydroxyethyl acrylic acid is dissolved in 4-5 parts by weight of N, N-dimethylformamide to obtain a 2-hydroxyethyl acrylic acid solution. The 2-hydroxyethyl olefine ester solution is added to the sodium lignin sulfonate solution, and then 1.5-2 parts by weight of pyridine is added, and the mixture is stirred at a temperature of 50-60° C. for 6-8 hours and at a stirring speed of 6000-7500 rpm for 4-6 minutes. After standing for stratification, the supernatant is filtered to obtain a supernatant, and the supernatant is mixed with isopropanol at a volume ratio of 1:(20-25) and then placed in a centrifuge for centrifugation at a centrifugal speed of 8000-10000 rpm for 5-6 minutes, and solid precipitate I is filtered to obtain a solid precipitate, which is rinsed with isopropanol 2-3 times and placed in a vacuum drying oven for drying at 40-45° C. to obtain esterified sodium lignin sulfonate; S1.2: The esterified sodium lignin sulfonate prepared in step S1.1 and an ethanol aqueous solution with a concentration of 30-35% are mixed in a mass ratio of 1: (8-10) and placed in an ultrasonic disperser, and ultrasonic treatment is performed at an ultrasonic frequency of 20-25 kHz for 15-20 minutes to obtain an esterified sodium lignin sulfonate solution, and acrylic acid is added to the esterified sodium lignin sulfonate solution at a molar mass ratio of 1: (0.28-0.32) to the esterified sodium lignin sulfonate, and then 3-mercaptopropionic acid, hydrogen peroxide and ascorbic acid are added. After stirring evenly, the temperature is raised to 40-45°C, and after keeping warm for 4-5 hours, 2-3wt% of sodium dodecyl sulfate is added, and the modified lignin coating solvent is obtained after high-speed stirring.

3. The method for preparing a sustained-release mixed preparation based on difenoconazole according to claim 1, characterized in that: Step S2: preparation of humic acid light stabilizer, comprising the following steps: S2.1: 0.6-0.8 parts by weight of sodium humate and 10-12 parts by weight of acetonitrile / N,N-dimethylformamide solution are placed in an ultrasonic disperser, and ultrasonically dispersed at an ultrasonic frequency of 25-30kHz for 10-15 minutes to obtain a sodium humate dispersion, 2.5-3 parts by weight of Zn(NO3)2·6H2O and 15-18 parts by weight of acetonitrile / N,N-dimethylformamide solution are mixed and placed in a container, and stirred until Zn(NO3)2·6H2O is completely dissolved to obtain a zinc nitrate solution, and 5-6 parts by weight of terephthalic acid are dissociated into 15-18 parts by weight of acetonitrile / N,N-dimethylformamide solution to obtain a terephthalic acid solution; S2.2: The terephthalic acid solution obtained in step S2.1 is first placed at the bottom of a tubular container, and then the sodium humate dispersion obtained in step S2.1 is slowly added along the inner wall of the container, and finally the zinc nitrate solution obtained in step S2.1 is slowly added along the inner wall of the container to form a three-layer solution. The tubular container is placed in an oven and allowed to stand at 40-45°C for 45-48 hours, and then placed in a centrifuge for centrifugation and suction filtration to obtain solid precipitate II, which is washed 3-4 times with N,N-dimethylformamide and then dried at 80-85°C to obtain a humic acid light stabilizer.

4. The method for preparing a sustained-release mixed preparation based on difenoconazole according to claim 1, characterized in that: Step S3: compounding the sustained-release preparation, comprising the following steps: S3.1: 10-15 parts by weight of dichloromethane is placed in a container, 3-4 parts by weight of a humic acid light stabilizer and 2-3 parts by weight of difenoconazole are added, and magnetic stirring is performed at a stirring speed of 400-500 rpm until the difenoconazole is completely dissolved to obtain a difenoconazole organic solution; S3.2: Under stirring at 1000-1200rpm, 4-5 parts by weight of the difenoconazole organic solution are dropped into 15-20 parts by weight of the modified lignin coating solvent, and then 0.5-0.6 parts by weight of epichlorohydrin are added, and homogenized at a speed of 18000-20000rpm for 1.5-2 minutes using a homogenizer, and then placed in an ultrasonic cell crusher for intermittent ultrasonic treatment at a power of 200-220W for 2-2.5 minutes to obtain an ultrasonic emulsion, and the ultrasonic emulsion is placed in an environment of 50-55°C and stirred at a speed of 450-500rpm for 2-3 hours, and then 1-2wt% of styrylphenol polyoxyethylene ether dispersant is added, and stirred at room temperature for 1-1.5 hours to obtain a sustained-release mixed preparation based on difenoconazole.

5. The method for preparing a sustained-release mixed preparation based on difenoconazole according to claim 2, characterized in that: The 3-mercaptopropionic acid, hydrogen peroxide and ascorbic acid added in step S1.2 account for 0.6-0.8%, 0.4-0.5% and 0.7-0.9% of the mass fraction of the esterified sodium lignin sulfonate, respectively.

6. The method for preparing a sustained-release mixed preparation based on difenoconazole according to claim 3, characterized in that: The acetonitrile / N,N-dimethylformamide solution in step S2.1 is prepared by mixing acetonitrile and N,N-dimethylformamide solution in a volume ratio of 1:(1-1.5).

7. The method for preparing a sustained-release mixed preparation based on difenoconazole according to claim 4, characterized in that: The intermittent ultrasonic treatment in step S3.2 is performed by ultrasonicating for 2-3 seconds and pausing for 2-3 seconds.

8. A sustained-release mixed preparation based on difenoconazole, characterized in that: The invention is prepared by the method for preparing a sustained-release mixed preparation based on difenoconazole according to any one of claims 1 to 7.

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