PH-responsive controlled-release fludioxonil microcapsule pesticide with high slow release performance and preparation method of pH-responsive controlled-release fludioxonil microcapsule pesticide

Abstract

The invention discloses a pH response controlled release type fludioxonil microcapsule pesticide with high slow release performance and a preparation method of the pH response controlled release type fludioxonil microcapsule pesticide. The fludioxonil microcapsule pesticide is prepared from the following raw materials in parts by weight: 0.1-0.3 part of fludioxonil; 0.2 to 0.3 part of ethyl cellulose; 5-10 parts of an organic solvent; 0.05 to 0.1 part of an emulsifier; 1.0 to 2.0 parts of a dispersant; 0.02 to 0.03 part of dopamine hydrochloride; and 20 to 50 parts of deionized water. The invention also specifically discloses a preparation method of the fludioxonil microcapsule pesticide. The invention effectively solves the problem that most of microcapsule pesticides in the prior art only have a slow release effect and cannot realize effective controlled release of pesticides, and the prepared microcapsule pesticide can reduce the use of organic solvents, reduce the production cost and achieve better environmental and ecological benefits.

Description

Technical Field

[0001] This invention belongs to the field of microencapsulated pesticide technology, specifically relating to a pH-responsive controlled-release fludioxonil microencapsulated pesticide with high sustained-release performance and its preparation method. Background Technology

[0002] Microencapsulated pesticides are a new type of pesticide formulation that controls the slow release of the active ingredient. They are typically made of pesticide technical, adjuvants, and a capsule wall. After application, the pesticide is gradually released from the capsule wall to achieve its control effect. Microencapsulated pesticides effectively overcome the shortcomings of traditional pesticide formulations, such as inefficiency, pollution, and uncontrolled release, reducing the number of pesticide applications and thus weakening the toxicity of pesticides to non-target organisms.

[0003] However, in the field of microencapsulated pesticide formulations, most microencapsulated pesticides only have a sustained-release effect and cannot achieve effective controlled-release of pesticides. Furthermore, the synthesis of microencapsulated pesticides requires the use of a large amount of organic solvents, such as toluene and xylene, which easily causes environmental pollution. Therefore, this invention provides a pH-responsive controlled-release microencapsulated pesticide. Its preparation process can reduce the use of organic solvents while endowing the microcapsules with controlled-release properties based on changes in the pH of the environment, making it more environmentally friendly.

[0004] Patent document CN202310059142.4 discloses a pH-responsive pesticide slow-release hydrogel sphere and its preparation method. It utilizes carboxylated nanocellulose crystals modified with polyethyleneimine as raw materials, which are self-assembled with modified montmorillonite through electrostatic bonding. Pesticides are then loaded in an organic solvent, and sodium alginate is used as a coating material, with anhydrous calcium chloride as a crosslinking agent. The pH-responsive pesticide slow-release hydrogel spheres, composed of nanocellulose crystals and montmorillonite, are prepared by dropwise addition and are used for the slow release of pesticides in the soil environment. The pesticide release rate increases with increasing pH until the hydrogel skeleton completely ruptures. The pesticide release rate can be adjusted by regulating the pH.

[0005] Patent document CN202210329429.X discloses a slow-release pesticide, its preparation method, and its application. The slow-release pesticide comprises a carrier with a porous structure and a mixture loaded within the carrier. The mixture includes a phase change material (PCM) and a pesticide, with the pesticide dispersed in the PCM. The mixture of PCM and pesticide is loaded within the carrier. Utilizing the high-temperature melting and low-temperature solidification properties of the PCM, problems such as leakage, strong odor, and high toxicity that occur when the carrier only carries pesticide are effectively avoided, thus achieving slow pesticide release. The prepared slow-release pesticide exhibits pH and temperature-responsive release characteristics. The release rate of the slow-release pesticide can be controlled by adjusting the pH and temperature of the application environment to meet the needs of different applications. The preparation method is simple, low-cost, and easily scalable for industrial production. Summary of the Invention

[0006] The technical problem solved by this invention is to provide a pH-responsive controlled-release fludioxonil microcapsule pesticide with high sustained-release performance and its preparation method. This effectively solves the problem that most microcapsule pesticides in the prior art only have a sustained-release effect and cannot achieve effective controlled release of pesticides. At the same time, the prepared microcapsule pesticide can reduce the use of organic solvents, reduce production costs, and achieve better environmental and ecological benefits.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a pH-responsive controlled-release fludioxonil microcapsule pesticide with high sustained-release performance, characterized in that it is prepared from the following raw materials in parts by weight: Fludioxonil 0.1~0.3 parts; Ethyl cellulose 0.2~0.3 parts; 5-10 parts organic solvent; Emulsifier 0.05~0.1 parts; Dispersant 1.0~2.0 parts; Dopamine hydrochloride 0.02~0.03 parts; 20-50 parts deionized water; The dispersant is one or more of PVA1788, PVA1799, polyethylene glycol, or sodium lignosulfonate.

[0008] Further specifying, the organic solvent is one of dichloromethane, ethyl acetate, acetone, or ethanol.

[0009] Further specifying, the emulsifier is one of span80, OP-10, Tween60, Tween80 or vinylphenol polyoxyethylene ether.

[0010] The preparation method of the pH-responsive controlled-release fludioxonil microcapsule pesticide with high sustained-release performance described in this invention is characterized by the following specific steps: Step S1, Preparation of single-shell fludioxonil microcapsules: Fludioxonil technical, emulsifier and ethyl cellulose are dissolved in an organic solvent to obtain an oil phase; a dispersant is dissolved in deionized water to obtain an aqueous phase; the oil phase is added to the aqueous phase and sheared and emulsified to obtain an O / W type emulsion; the O / W type emulsion is then stirred and evaporated to obtain single-shell fludioxonil microcapsules encapsulated with ethyl cellulose. Step S2, Preparation of double-shell fludioxonil microcapsules: The single-shell fludioxonil microcapsules obtained in step S1 are separated by centrifugation. The precipitate obtained after centrifugation is added to water and the pH of the mixture is adjusted to alkaline. After stirring and mixing evenly, an aqueous solution of dopamine hydrochloride is added and the mixture is stirred and mixed evenly to obtain double-shell fludioxonil microcapsules.

[0011] Further specifying, the emulsification conditions in step S1 are a shear rate of 8000~10000 rpm and an emulsification time of 10~15 min.

[0012] Further specifying, the volatilization conditions in step S1 are a mechanical stirring speed of 200~500 rpm and a volatilization time of 12~24 h.

[0013] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The present invention uses raw materials such as ethyl cellulose and polyvinyl alcohol, which have the advantages of being biodegradable and having low preparation cost.

[0014] 2. By adding dopamine hydrochloride as the outer shell material, this invention can achieve the goal of improving the water solubility and sustained-release performance of single-shell microcapsules.

[0015] 3. The pH-responsive controlled-release fludioxonil microcapsules prepared by this invention have uniform particle size, high drug loading, good sustained-release performance, and good pH-controlled release performance.

[0016] 4. The pH-controlled release fludioxonil microcapsule pesticide prepared by this invention can control the release of fludioxonil from the microcapsules by changing the pH value of the environment during disease outbreaks in agricultural production. This can improve the utilization rate of fludioxonil, reduce the amount used, and has good economic and environmental benefits. Attached Figure Description

[0017] Figure 1 Electron microscope images of different samples; (a) is fludioxonil technical, (b) is a single-shell fludioxonil microcapsule, and (c) is a double-shell fludioxonil microcapsule.

[0018] Figure 2 Infrared spectra of fludioxonil technical grade and double-shelled fludioxonil microcapsules in different organic solvents.

[0019] Figure 3 This is a comparison chart of the sustained-release properties of fludioxonil technical, single-shell fludioxonil microcapsules, and double-shell fludioxonil microcapsules.

[0020] Figure 4 This is a comparison of the sustained-release properties of double-shell fludioxonil microcapsules at different pH values. Detailed Implementation

[0021] The following examples further illustrate the above-described content of the present invention, but it should not be construed as limiting the scope of the subject matter of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Example 1

[0022] The preparation of fludioxonil microcapsule pesticides includes the following raw materials: 0.12g fludioxonil, 0.24g ethyl cellulose, 10.0g ethyl acetate, 0.08g vinylphenol polyoxyethylene ether, 1g PVA1788, 50.0g deionized water, and 0.02g dopamine hydrochloride.

[0023] Step S1, Preparation of single-shell fludioxonil microcapsules: 0.12g fludioxonil technical, 0.08g vinylphenol polyoxyethylene ether and 0.24g ethyl cellulose were dissolved in 10.0g ethyl acetate to obtain an oil phase; 1g PVA1788 was dissolved in 50.0g deionized water to obtain an aqueous phase; the obtained oil phase was added to the obtained aqueous phase and shear emulsified to obtain an O / W type emulsion; the O / W type emulsion was then stirred and evaporated to obtain single-shell fludioxonil microcapsules encapsulated with ethyl cellulose. The emulsification conditions were a shear rate of 10000rpm and an emulsification time of 10min; the evaporation conditions were a mechanical stirring speed of 500rpm and an evaporation time of 20h.

[0024] Step S2, Preparation of double-shell fludioxonil microcapsules: The single-shell fludioxonil microcapsules obtained in step S1 are separated by centrifugation. The precipitate obtained after centrifugation is added to water and the pH of the mixture is adjusted to alkaline. After stirring and mixing evenly, an aqueous solution containing 0.02g of dopamine hydrochloride is added and the mixture is stirred and mixed evenly to obtain double-shell fludioxonil microcapsules A1.

[0025] Comparative Example 1 The preparation of fludioxonil microcapsule pesticide includes the following raw materials: 0.12g fludioxonil, 0.24g ethyl cellulose, 10.0g ethyl acetate, 0.08g vinylphenol polyoxyethylene ether, 1g PVA1788 and 50.0g deionized water.

[0026] Preparation of single-shell fludioxonil microcapsules: 0.12 g fludioxonil technical, 0.08 g vinylphenol polyoxyethylene ether and 0.24 g ethyl cellulose were dissolved in 10.0 g ethyl acetate to obtain an oil phase; 1 g PVA1788 was dissolved in 50.0 g deionized water to obtain an aqueous phase; the obtained oil phase was added to the obtained aqueous phase and sheared emulsified to obtain an O / W type emulsion; the O / W type emulsion was then stirred and evaporated to obtain ethyl cellulose-encapsulated single-shell fludioxonil microcapsules A2. The emulsification conditions were a shear rate of 10000 rpm and an emulsification time of 10 min; the evaporation conditions were a mechanical stirring speed of 500 rpm and an evaporation time of 20 h. Example 2

[0027] The preparation of fludioxonil microcapsule pesticide includes the following raw materials: fludioxonil 0.24g, ethyl cellulose 0.24g, ethyl acetate 10.0g, vinylphenol polyoxyethylene ether 0.08g, PVA1788 1g, deionized water 50.0g and dopamine hydrochloride 0.02g.

[0028] Step S1, Preparation of single-shell fludioxonil microcapsules: 0.24g fludioxonil technical, 0.08g vinylphenol polyoxyethylene ether and 0.24g ethyl cellulose were dissolved in 10.0g ethyl acetate to obtain an oil phase; 1g PVA1788 was dissolved in 50.0g deionized water to obtain an aqueous phase; the obtained oil phase was added to the obtained aqueous phase and shear emulsified to obtain an O / W type emulsion; the O / W type emulsion was then stirred and evaporated to obtain single-shell fludioxonil microcapsules encapsulated with ethyl cellulose. The emulsification conditions were a shear rate of 10000rpm and an emulsification time of 10min; the evaporation conditions were a mechanical stirring speed of 500rpm and an evaporation time of 20h.

[0029] Step S2, Preparation of double-shell fludioxonil microcapsules: The single-shell fludioxonil microcapsules obtained in step S1 are separated by centrifugation. The precipitate obtained after centrifugation is added to water and the pH of the mixture is adjusted to alkaline. After stirring and mixing evenly, an aqueous solution containing 0.02g of dopamine hydrochloride is added and the mixture is stirred and mixed evenly to obtain double-shell fludioxonil microcapsules A3. Example 3

[0030] The preparation of fludioxonil microcapsule pesticides includes the following raw materials: 0.12g fludioxonil, 0.24g ethyl cellulose, 10.0g dichloromethane, 0.08g vinylphenol polyoxyethylene ether, 1g PVA1788, 50.0g deionized water, and 0.02g dopamine hydrochloride.

[0031] Step S1, Preparation of single-shell fludioxonil microcapsules: 0.12g fludioxonil technical, 0.08g vinylphenol polyoxyethylene ether and 0.24g ethyl cellulose were dissolved in 10.0g dichloromethane to obtain an oil phase; 1g PVA1788 was dissolved in 50.0g deionized water to obtain an aqueous phase; the obtained oil phase was added to the obtained aqueous phase and shear emulsified to obtain an O / W type emulsion; the O / W type emulsion was then stirred and evaporated to obtain single-shell fludioxonil microcapsules encapsulated with ethyl cellulose. The emulsification conditions were a shear rate of 10000rpm and an emulsification time of 10min; the evaporation conditions were a mechanical stirring speed of 500rpm and an evaporation time of 20h.

[0032] Step S2, Preparation of double-shell fludioxonil microcapsules: The single-shell fludioxonil microcapsules obtained in step S1 are separated by centrifugation. The precipitate obtained after centrifugation is added to water and the pH of the mixture is adjusted to alkaline. After stirring and mixing evenly, an aqueous solution containing 0.02g of dopamine hydrochloride is added and the mixture is stirred and mixed evenly to obtain double-shell fludioxonil microcapsules A4. Example 4

[0033] The preparation of fludioxonil microcapsule pesticides includes the following raw materials: 0.12g fludioxonil, 0.24g ethyl cellulose, 10.0g acetone, 0.08g vinylphenol polyoxyethylene ether, 1g PVA1788, 50.0g deionized water, and 0.02g dopamine hydrochloride.

[0034] Step S1, Preparation of single-shell fludioxonil microcapsules: 0.12g fludioxonil technical, 0.08g vinylphenol polyoxyethylene ether and 0.24g ethyl cellulose were dissolved in 10.0g acetone to obtain an oil phase; 1g PVA1788 was dissolved in 50.0g deionized water to obtain an aqueous phase; the obtained oil phase was added to the obtained aqueous phase and shear emulsified to obtain an O / W type emulsion; the O / W type emulsion was then stirred and evaporated to obtain single-shell fludioxonil microcapsules encapsulated with ethyl cellulose. The emulsification conditions were a shear rate of 10000rpm and an emulsification time of 10min; the evaporation conditions were a mechanical stirring speed of 500rpm and an evaporation time of 20h.

[0035] Step S2, Preparation of double-shell fludioxonil microcapsules: The single-shell fludioxonil microcapsules obtained in step S1 are separated by centrifugation. The precipitate obtained after centrifugation is added to water and the pH of the mixture is adjusted to alkaline. After stirring and mixing evenly, an aqueous solution containing 0.02g of dopamine hydrochloride is added and the mixture is stirred and mixed evenly to obtain double-shell fludioxonil microcapsules A5. Example 5

[0036] The preparation of fludioxonil microcapsule pesticides includes the following raw materials: fludioxonil 0.12g, ethyl cellulose 0.24g, ethanol 10.0g, vinyl phenol polyoxyethylene ether 0.08g, PVA1788 1g, deionized water 50.0g and dopamine hydrochloride 0.02g.

[0037] Step S1, Preparation of single-shell fludioxonil microcapsules: 0.12g fludioxonil technical, 0.08g vinylphenol polyoxyethylene ether and 0.24g ethyl cellulose were dissolved in 10.0g ethanol to obtain an oil phase; 1g PVA1788 was dissolved in 50.0g deionized water to obtain an aqueous phase; the obtained oil phase was added to the obtained aqueous phase and shear emulsified to obtain an O / W type emulsion; the O / W type emulsion was then stirred and evaporated to obtain single-shell fludioxonil microcapsules encapsulated with ethyl cellulose. The emulsification conditions were a shear rate of 10000rpm and an emulsification time of 10min; the evaporation conditions were a mechanical stirring speed of 500rpm and an evaporation time of 20h.

[0038] Step S2, Preparation of double-shell fludioxonil microcapsules: The single-shell fludioxonil microcapsules obtained in step S1 are separated by centrifugation. The precipitate obtained after centrifugation is added to water and the pH of the mixture is adjusted to alkaline. After stirring and mixing evenly, an aqueous solution containing 0.02g of dopamine hydrochloride is added and the mixture is stirred and mixed evenly to obtain double-shell fludioxonil microcapsules A6.

[0039] The morphology of the fludioxonil microcapsules prepared in Example 1 was observed by electron microscopy; the composition and structure of the microcapsules prepared in Example 1 were characterized by infrared spectroscopy; a standard curve was obtained by ultraviolet spectrophotometry at 263 nm to determine the sustained-release performance and pH response of the fludioxonil microcapsules prepared in the example.

[0040] Figure 1 In Figure 1, (A), (B), and (C) represent fludioxonil technical, single-shell fludioxonil microcapsules, and double-shell fludioxonil microcapsules, respectively. As shown in the figure, the double-shell fludioxonil microcapsules prepared in Example 1 are spherical, with a smooth surface, no aggregation, and an average particle size of approximately 1.0 μm.

[0041] Figure 2 The image shows a comparison of the infrared spectra of the double-shelled fludioxonil microcapsules prepared in Example 1 with fludioxonil technical, ethyl cellulose wall material, and different comparative proportions.

[0042] Figure 3 This figure compares the release performance of the double-shelled fludioxonil microcapsules prepared in Example 1 with that of fludioxonil technical and the single-shelled fludioxonil microcapsules prepared in Comparative Example 1. The figure shows that the prepared double-shelled fludioxonil microcapsules exhibit enhanced sustained-release performance, which can prevent premature release of fludioxonil to some extent.

[0043] Figure 4The graph shows the release capacity of the double-shelled fludioxonil microcapsules prepared in Example 1 at different pH values. These microcapsules exhibit good pH sensitivity, especially under acidic conditions, which increases the solubility of the wall material, thereby promoting the release of pesticides from the microcapsules. The results show that the release rate of this microcapsule pesticide increases by 13.22% at pH=5. It ensures rapid release of the pesticide when diseases occur, demonstrating excellent release stability and pH responsiveness.

[0044] The fludioxonil microcapsule pesticide prepared by this invention can control the release of fludioxonil within the microcapsules by varying the pH of the environment in agricultural production. This can effectively improve the utilization rate of fludioxonil, reduce pesticide usage, and provide significant economic and environmental benefits. Results show that these microcapsules exhibit excellent sustained-release performance (e.g., 18.36% release after 300 hours at pH 7.0) and intelligent response capability (31.58% release after 300 hours in an acidic environment). The pH-controlled-release fludioxonil microcapsule pesticide prepared by this invention can control the release of fludioxonil within the microcapsules by monitoring soil changes during disease outbreaks. It is suitable for application in the field of sustained-release pesticides. The development of this technology has positive implications for promoting the application and development of environmentally friendly materials.

[0045] The above embodiments describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from the scope of the principles of the present invention, and all such changes and modifications fall within the protection scope of the present invention.

Claims

1. A pH-responsive controlled-release fludioxonil microcapsule pesticide with high sustained-release properties, characterized in that... It is prepared from the following raw materials in parts by weight: Fludioxonil 0.1~0.3 parts; Ethyl cellulose 0.2~0.3 parts; 5-10 parts organic solvent; Emulsifier 0.05~0.1 parts; Dispersant 1.0~2.0 parts; Dopamine hydrochloride 0.02~0.03 parts; 20-50 parts deionized water; The dispersant is one or more of PVA1788, PVA1799, polyethylene glycol, or sodium lignosulfonate.

2. The pH-responsive controlled-release fludioxonil microcapsule pesticide with high sustained-release performance according to claim 1, characterized in that: The organic solvent is one of dichloromethane, ethyl acetate, acetone or ethanol.

3. The pH-responsive controlled-release fludioxonil microcapsule pesticide with high sustained-release performance according to claim 1, characterized in that: The emulsifier is one of span80, OP-10, Tween60, Tween80 or vinylphenol polyoxyethylene ether.

4. A method for preparing a pH-responsive controlled-release fludioxonil microcapsule pesticide according to any one of claims 1 to 3, characterized in that... The specific steps are as follows: Step S1, Preparation of single-shell fludioxonil microcapsules: Fludioxonil technical, emulsifier and ethyl cellulose are dissolved in an organic solvent to obtain an oil phase; a dispersant is dissolved in deionized water to obtain an aqueous phase; the oil phase is added to the aqueous phase and sheared and emulsified to obtain an O / W type emulsion; the O / W type emulsion is then stirred and evaporated to obtain single-shell fludioxonil microcapsules encapsulated with ethyl cellulose. Step S2, Preparation of double-shell fludioxonil microcapsules: The single-shell fludioxonil microcapsules obtained in step S1 are separated by centrifugation. The precipitate obtained after centrifugation is added to water and the pH of the mixture is adjusted to alkaline. After stirring and mixing evenly, an aqueous solution of dopamine hydrochloride is added and the mixture is stirred and mixed evenly to obtain double-shell fludioxonil microcapsules.

5. The method for preparing pH-responsive controlled-release fludioxonil microcapsule pesticide according to claim 4, characterized in that: In step S1, the emulsification conditions are a shear rate of 8000~10000 rpm and an emulsification time of 10~15 min.

6. The method for preparing pH-responsive controlled-release fludioxonil microcapsule pesticide according to claim 4, characterized in that: The volatilization conditions in step S1 are a mechanical stirring speed of 200~500 rpm and a volatilization time of 12~24 h.

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