Slow-release nano suspending agent as well as preparation method and application thereof

Abstract

The invention provides a sustained-release nano suspending agent as well as a preparation method and application thereof, and belongs to the technical field of pesticide preparations. The slow-release nano suspending agent is prepared from the following raw materials in percentage by weight: 1 to 20 percent of pyrethroid active compound, 3 to 8 percent of wetting agent, 2 to 7 percent of dispersing agent, 4 to 6 percent of antifreezing agent, 0.05 to 1 percent of defoaming agent, 0.01 to 1 percent of preservative, 0.01 to 0.4 percent of pH (Potential of Hydrogen) regulator and the balance of water, the wetting agent is polyvinyl alcohol and sodium lignin sulfonate, and the mass ratio of the polyvinyl alcohol to the sodium lignin sulfonate is (1-3): 3. The wetting agent can reduce the decomposition of the raw pesticide, and hydrogen bonds are slowly damaged and gradually released to prolong the pesticide effect. Heat storage, cold storage and long-term storage stability tests show that compared with a traditional suspending agent, the slow-release nano-suspending agent is stable in performance and obvious in control effect, and the lasting period is prolonged by 1-2 times compared with the traditional suspending agent.

Description

Technical Field

[0001] The invention belongs to the technical field of agricultural preparations, and in particular relates to a sustained-release nano suspension and a preparation method and application thereof. Background Art

[0002] Pyrethroid insecticides are biomimetic synthetic insecticides, which are synthetic esters derived by changing the chemical structure of natural pyrethroids. They have stronger insecticidal toxicity than many other pyrethroid insecticides. When they enter the body of insects, they can quickly interfere with the function of neurons, and can effectively protect cotton, fruit trees and other crops from being eaten by piercing-sucking mouthparts pests and mites. Due to their broad spectrum, high efficiency, easy degradation and low toxicity, they are widely used in the cultivation of field crops and vegetables. Pyrethroid insecticides obtained by traditional preparation methods are prone to agglomeration and coagulation, which makes them difficult to store and have poor effects on preventing and controlling crop pests. It is difficult to meet the preparation needs of pesticides for preventing and controlling crop pests. Moreover, they are easily ineffective under the influence of the external environment, such as sunlight, soil pH, etc., and have a short duration, which reduces the prevention effect of pesticides. Summary of the invention

[0003] In view of this, the object of the present invention is to provide a sustained-release nanosuspension and a preparation method and application thereof, wherein the sustained-release nanosuspension prolongs the effective period of pest control and significantly improves the efficiency of pest control.

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

[0005] The present invention provides a sustained-release nano suspension, which comprises the following raw materials in percentage by weight: 1% to 20% of pyrethroid original drug, 3% to 8% of wetting agent, 2% to 7% of dispersant, 4% to 6% of antifreeze agent, 0.05% to 1% of defoaming agent, 0.01% to 1% of preservative, 0.01% to 0.4% of pH regulator, and water is added to 100%;

[0006] The wetting agents are polyvinyl alcohol and sodium lignin sulfonate, and the mass ratio of the polyvinyl alcohol to the sodium lignin sulfonate is 1 to 3:3.

[0007] Preferably, the particle size of the sustained-release nanosuspension is 200-500 nm.

[0008] Preferably, the pyrethroid original drug includes one or more of high-efficiency cyhalothrin, ethomethrin, permethrin, deltamethrin, cypermethrin, high-efficiency cypermethrin, cis-cypermethrin, cypermethrin, cypermethrin, cypermethrin, cypermethrin, cypermethrin, cypermethrin, cypermethrin, fluvalerate, flucythrin, flumethrin, cypermethrin, valerate, cypermethrin, cyfluthrin and bifenthrin.

[0009] Preferably, the dispersant comprises one or both of phosphate ester and block polyether.

[0010] Preferably, the phosphate ester includes one of 33SC, 500LQ, 2210 and 1020; and the block polyether includes one of 5500 and 5050PB.

[0011] Preferably, the defoaming agent includes ester-ether type compounds, C8-C 10 One or more of fatty alcohol, organic silicone and silicone oil; the preservative includes one or more of formaldehyde, sodium benzoate and potassium sorbate; the pH adjuster includes one or more of phosphoric acid, lactic acid and citric acid; the pH value of the sustained-release nanosuspension is 5.0-7.0; the antifreeze agent is ethylene glycol.

[0012] The present invention provides a method for preparing the above-mentioned sustained-release nanosuspension, comprising the following steps:

[0013] (1) mixing the pyrethroid technical, a dispersant, a wetting agent, an antifreeze agent, a preservative and water to obtain a mixed slurry;

[0014] (2) sand-grinding the mixed slurry, adding the defoaming agent during the grinding process to obtain a sand-grinded slurry;

[0015] (3) The sand-milled slurry is mixed with the pH regulator to obtain a sustained-release nanosuspension.

[0016] Preferably, the sand grinding temperature is 20-30°C, and the sand grinding is performed to a particle size of 200-500 nm.

[0017] The present invention provides an application of the above-mentioned sustained-release nano suspension or the preparation method in controlling pests or preparing pesticides.

[0018] Preferably, the pests include one or more of aphids, cotton bollworms, beet armyworms, tea green leafhoppers and black cutworms.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention provides a sustained-release nano suspension and a preparation method and application thereof. The present invention adopts polyvinyl alcohol and sodium lignin sulfonate as wetting agents. During the sand grinding process, the hydrophilic end of the sodium lignin sulfonate can form 3D hydrogen bonds with water and polyvinyl alcohol to wrap the original drug particles and self-assemble to form nano original drug particles. At the same time, the hydrophobic end of the wetting agent can combine with the wax layer of the insect epidermis to quickly enter the insect body, and also form a water-locking film on the surface of the leaves to reduce the decomposition of the original drug, and gradually release it through the slow destruction of hydrogen bonds to achieve the purpose of prolonging the efficacy. The sustained-release nano suspension is subjected to hot storage, cold storage and long-term storage stability tests, indicating that the sustained-release nano suspension is more stable than the traditional suspension, has obvious prevention effect, and the lasting effect is 1 to 2 times longer than the traditional suspension. DETAILED DESCRIPTION

[0021] The present invention provides a sustained-release nano suspension, which comprises the following raw materials in percentage by weight: 1% to 20% of pyrethroid original drug, 3% to 8% of wetting agent, 2% to 7% of dispersant, 4% to 6% of antifreeze agent, 0.05% to 1% of defoaming agent, 0.01% to 1% of preservative, 0.01% to 0.4% of pH regulator, and water is added to 100%;

[0022] The wetting agents are polyvinyl alcohol and sodium lignin sulfonate, and the mass ratio of the polyvinyl alcohol to the sodium lignin sulfonate is 1 to 3:3.

[0023] The sustained-release nano suspension is preferably composed of the following raw materials in percentage by weight: 2% to 15% of pyrethroid original drug, 4% to 6% of wetting agent, 3% to 6% of dispersant, 4% to 6% of antifreeze agent, 0.2% to 0.6% of defoaming agent, 0.03% to 0.5% of preservative, 0.1% to 0.3% of pH regulator, and water is added to 100%;

[0024] The wetting agents are polyvinyl alcohol and sodium lignin sulfonate, and the mass ratio of the polyvinyl alcohol to the sodium lignin sulfonate is 1 to 3:3.

[0025] In the present invention, the mass ratio of the polyvinyl alcohol and sodium lignin sulfonate is preferably 1.5 to 2.5:3, and more preferably 2:3. The wetting agent of the present invention is a hydrogel, which is a very hydrophilic three-dimensional network structure gel, which can be used as a carrier of medicine. During the sand milling process, polyvinyl alcohol and sodium lignin sulfonate are added to the pesticide preparation as wetting agents, and the amphiphilic functional groups rich in sodium lignin sulfonate can be self-assembled into micro-nano particles in an aqueous solution, and the hydrophilic functional groups such as sulfonic acid groups, carboxyl groups, and hydroxyl groups exposed on the outer surface can form rich hydrogen bonds with the polyvinyl alcohol matrix and water, and construct a 3D hydrogen bond network to wrap the original drug to form original drug nanoparticles. After the agent acts on the surface of the pest, the hydrophobic end of the polyvinyl alcohol-modified sodium lignin sulfonate will combine with the wax layer on the surface of the pest to form a thin film to promote drug absorption. The agent sprayed on the plant leaf surface achieves the purpose of sustained release through the slow destruction of hydrogen bonds and prolongs the drug effect, improves the drug lasting period, reduces the number of medications, and improves the control effect.

[0026] In the present invention, for the pesticide active ingredient in the present invention, the smaller the particle size in the preparation, the more the number of pesticide active ingredient particles dispersed per unit area of ​​the target, the larger the specific surface area, the larger the contact area with the target organism, and the better the efficacy. The nano-scale sustained-release nano suspension of the present invention has higher prevention effect and less application amount than the traditional suspension micron-level (1-5μm) particles, which conforms to the national policy of reducing application and increasing efficiency, and is of great significance to food safety. The particle size of the sustained-release nano suspension is preferably 200-500nm.

[0027] In the present invention, the pyrethroid original drug includes one or more of high-efficiency cyhalothrin, ether cypermethrin, permethrin, deltamethrin, cypermethrin, high-efficiency cypermethrin, cis-cypermethrin, cypermethrin, cypermethrin, cypermethrin, valerate, flucythrin, flumethrin, fluvalerate cyanamide, valerate, cypermethrin, cyhalothrin and bifenthrin. The dispersant includes one or both of phosphate and block polyether. More preferably, the phosphate includes one of 33SC, 500LQ, 2210 and 1020; the block polyether includes one of 5500 and 5050PB. The defoamer includes ester-ether type compounds, C8-C 10 One or more of fatty alcohol, organic silicone and silicone oil; the preservative includes one or more of formaldehyde, sodium benzoate and potassium sorbate; the pH adjuster includes one or more of phosphoric acid, lactic acid and citric acid; the pH value of the sustained-release nanosuspension is 5.0-7.0.

[0028] The present invention provides a method for preparing the above-mentioned sustained-release nanosuspension, comprising the following steps:

[0029] (1) mixing the pyrethroid technical, a dispersant, a wetting agent, an antifreeze agent, a preservative and water to obtain a mixed slurry;

[0030] (2) sand-grinding the mixed slurry, adding the defoaming agent during the grinding process to obtain a sand-grinded slurry;

[0031] (3) The sand-milled slurry is mixed with the pH regulator to obtain a sustained-release nanosuspension.

[0032] In the present invention, the pyrethroid original drug, dispersant, wetting agent, antifreeze agent, preservative and water are mixed to obtain a mixed slurry, and the mixing can be selected as shear mixing to ensure uniform mixing. After obtaining the mixed slurry, the mixed slurry is sand-milled, and the defoamer is added during the grinding process to obtain a sand-milled slurry. The sand-milling temperature is preferably 20 to 30°C, and more preferably 22 to 28°C. The sand-milling to a particle size is preferably 200 to 500 nm. After obtaining the sand-milled slurry, the sand-milled slurry is mixed with the pH regulator to obtain a sustained-release nanosuspension, and the pH value of the sustained-release nanosuspension is 5.0 to 7.0.

[0033] The present invention provides an application of the above-mentioned sustained-release nano suspension or the preparation method in controlling pests or preparing pesticides.

[0034] In the present invention, the sustained-release nanosuspension or the preparation method can be used to increase the duration of pest control and also to improve the efficiency of killing pests, thereby reducing the amount of pesticides applied. The pests preferably include one or more of aphids, cotton bollworms, beet armyworms, tea leafhoppers and cutworms.

[0035] Compared with the traditional suspension, the sustained-release nano suspension of the present invention has uniform appearance, no crystal precipitation at temperature change, good pourability and good cold and hot storage stability even without adding a thickener, according to stability tests.

[0036] In the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art.

[0037] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0038] In the following examples, the phosphate ester (33SC) was purchased from Xingfei Chemical (Shanghai) Co., Ltd.; the phosphate ester (500LQ) was purchased from Nanjing Jierun Technology Co., Ltd.; the phosphate ester (2210) was purchased from Indorama Corporation of Indonesia; the phosphate ester (1020) was purchased from Wuxi Yijingfeng Technology Co., Ltd.; the block polyether (5500) was purchased from Indorama Corporation of Indonesia; the block polyether (5050PB) was purchased from Jieshi Chemical (Shanghai) Co., Ltd.; the sodium lignin sulfonate was purchased from Shenzhen Zhongshenghe Biotechnology Co., Ltd. Among them, 33SC is the product number of the phosphate ester purchased from Xingfei Chemical (Shanghai) Co., Ltd.; 500LQ is the product number of the phosphate ester purchased from Nanjing Jierun Technology Co., Ltd.; 2210 is the product number of the phosphate ester purchased from Indorama Corporation, an Indonesian group; 1020 is the product number of the phosphate ester purchased from Wuxi Yijingfeng Technology Co., Ltd.; 5500 is the product number of the block polyether purchased from Indorama Corporation, an Indonesian group; 5050PB is the product number of the block polyether purchased from Jieshi Chemical (Shanghai) Co., Ltd.

[0039] Example 1

[0040] A sustained-release nano suspension comprises the following components by weight based on 100 parts by weight of raw materials for its preparation: 2.5% of high-efficiency chlorflucythrinate, 2% of polyvinyl alcohol, 3% of sodium lignin sulfonate, 3% of phosphate ester (33SC), 4% of ethylene glycol, 0.4% of organic silicone, 0.1% of formaldehyde and 0.2% of phosphoric acid, which are supplemented to 100% with water.

[0041] The specific steps of the preparation method of the sustained-release nanosuspension are as follows:

[0042] a. Weigh the above-mentioned weight contents of cyhalothrin, phosphate (33SC), polyvinyl alcohol, sodium lignin sulfonate, ethylene glycol, formaldehyde and water respectively and put them into a stirring tank for shear mixing to obtain a mixed slurry;

[0043] b. At 20 to 30° C., the slurry mixed in step a is passed through a pin-type sand mill for sand grinding, and the organic silicone in the above weight content is added while grinding, and the slurry is sand ground to a particle size of 200 to 500 nm to obtain a sand-milled slurry;

[0044] c. Add the above-mentioned phosphoric acid in a weight content to the sand-milled slurry obtained in step b to adjust the pH value to 5.0-7.0, thereby obtaining a 2.5% cyhalothrin nano suspension.

[0045] Example 2

[0046] A sustained-release nano suspension comprises the following components by weight based on 100 parts by weight of the raw materials for its preparation: 5% of high-efficiency chlorpyrifos, 2% of polyvinyl alcohol, 3% of sodium lignin sulfonate, 2% of phosphate (2210), 1% of block polyether (5500), 4% of ethylene glycol, 0.4% of organic silicone, 0.1% of formaldehyde and 0.2% of phosphoric acid, which are supplemented with water to 100%.

[0047] The specific steps of the preparation method of the sustained-release nanosuspension are as follows:

[0048] a. Weigh the above-mentioned weight contents of cyhalothrin, phosphate (2210), block polyether (5500), polyvinyl alcohol, sodium lignin sulfonate, ethylene glycol, formaldehyde and water respectively and put them into a stirring tank for shear mixing to obtain a mixed slurry;

[0049] b. At 20 to 30° C., the slurry mixed in step a is passed through a pin-type sand mill for sand grinding, and the organic silicone in the above weight content is added while grinding, and the slurry is sand ground to a particle size of 200 to 500 nm to obtain a sand-milled slurry;

[0050] c. Add the above-mentioned phosphoric acid in a weight content to the sand-milled slurry obtained in step b to adjust the pH value to 5.0-7.0, thereby obtaining a 5% cyhalothrin nanosuspension.

[0051] Example 3

[0052] A sustained-release nano suspension comprises the following components by weight based on 100 parts by weight of raw materials for its preparation: 10% of deltamethrin, 2% of polyvinyl alcohol, 3% of sodium lignin sulfonate, 3% of phosphate (2210), 4% of ethylene glycol, 0.4% of organic silicone, 0.1% of formaldehyde and 0.3% of phosphoric acid, which are supplemented with water to 100%.

[0053] The specific steps of the preparation method of the sustained-release nanosuspension are as follows:

[0054] a. Weigh the above-mentioned deltamethrin, phosphate (2210), polyvinyl alcohol, sodium lignin sulfonate, ethylene glycol, formaldehyde and water respectively and put them into a stirring tank for shear mixing to obtain a mixed slurry;

[0055] b. At 20 to 30° C., the slurry mixed in step a is passed through a pin-type sand mill for sand grinding, and the organic silicone in the above weight content is added while grinding, and the slurry is sand ground to a particle size of 200 to 500 nm to obtain a sand-milled slurry;

[0056] c. Add the above-mentioned phosphoric acid in a weight content to the sand-milled slurry obtained in step b to adjust the pH value to 5.0-7.0, thereby preparing a 10% deltamethrin nano suspension.

[0057] Example 4

[0058] A sustained-release nano suspension comprises the following components by weight based on 100 parts by weight of raw materials for its preparation: 20% of bifenthrin, 2% of polyvinyl alcohol, 3% of sodium lignin sulfonate, 2% of block polyether (5050PB), 4% of ethylene glycol, 0.4% of organic silicone, 0.1% of formaldehyde, and 0.25% of phosphoric acid, which are supplemented with water to 100%.

[0059] The specific steps of the preparation method of the sustained-release nanosuspension are as follows:

[0060] a. Weigh the above-mentioned weight contents of bifenthrin, block polyether (5050PB), polyvinyl alcohol, sodium lignin sulfonate, ethylene glycol, formaldehyde and water respectively and put them into a stirring tank for shear mixing to obtain a mixed slurry;

[0061] b. At 20 to 30° C., the slurry mixed in step a is passed through a pin-type sand mill for sand grinding, and the organic silicone in the above weight content is added while grinding, and the slurry is sand ground to a particle size of 200 to 500 nm to obtain a sand-milled slurry;

[0062] c. Add the above-mentioned phosphoric acid in a weight content to the sand-milled slurry obtained in step b to adjust the pH value to a range of 5.0 to 7.0, thereby obtaining a 20% bifenthrin nanosuspension.

[0063] Comparative Example 1

[0064] The present embodiment provides a highly effective cyhalothrin suspension, which comprises the following components by weight percentage: 2.5% of highly effective cyhalothrin, 3% of sodium dodecylbenzene sulfonate (wetting agent), 3% of phosphate ester (33SC) (dispersant), 0.1% of formaldehyde (preservative), 0.1% of phosphoric acid (pH regulator), 4% of ethylene glycol (antifreeze agent), 0.5% of xanthan gum (thickener), 0.4% of organic silicone (defoaming agent), and the content is made up to 100% with water.

[0065] The specific steps of the method for preparing the highly effective cyhalothrin suspension are as follows:

[0066] a. Weigh the above-mentioned weight contents of highly effective chlorfenapyr, phosphate (33SC), sodium dodecylbenzene sulfonate, ethylene glycol, formaldehyde and water respectively and put them into a stirring tank for shear mixing to obtain a mixed material;

[0067] b. At 20-30° C., the mixed material in step a is passed through a sand mill for sand grinding, while adding the above-mentioned weight content of organic silicone, and sand grinding to a particle size of 1-5 μm to obtain a sand-milled material;

[0068] c. Add the above-mentioned weight content of xanthan gum to the sand-milled material obtained in step b, shear and stir evenly again, add the above-mentioned weight content of phosphoric acid to adjust the pH value to 5.0-7.0, and obtain a 2.5% efficient chlorfenapyr suspension.

[0069] Comparative Example 2

[0070] A highly effective cypermethrin suspension comprises the following components by weight percentage: 5% of highly effective cypermethrin technical, 3% of sodium dodecylbenzene sulfonate (wetting agent), 2% of phosphate ester (2210) (dispersant), 1% of block polyether (5500) (dispersant), 0.1% of formaldehyde (preservative), 0.1% of phosphoric acid (pH regulator), 4% of ethylene glycol (antifreeze agent), 0.5% of xanthan gum (thickener), 0.4% of organic silicone (defoaming agent), and the content is made up to 100% with water.

[0071] The specific steps of the method for preparing the highly effective cyhalothrin suspension are as follows:

[0072] a. Weigh the above-mentioned weight contents of cyhalothrin, phosphates (2210), block polyethers (5500), sodium dodecylbenzene sulfonate, ethylene glycol, formaldehyde and water respectively and put them into a stirring tank for shear mixing to obtain a mixed material;

[0073] b. At 20-30° C., the mixed material in step a is passed through a sand mill for sand grinding, while adding the above-mentioned weight content of organic silicone, and sand grinding to a particle size of 1-5 μm to obtain a sand-milled material;

[0074] c. Add the above-mentioned weight content of xanthan gum to the sand-milled material obtained in step b, shear and stir evenly again, add the above-mentioned weight content of phosphoric acid to adjust the pH value to 5.0-7.0, and obtain a 2.5% efficient chlorfenapyr suspension.

[0075] Comparative Example 3

[0076] A cypermethrin suspension comprises the following components by weight percentage: 10% of cypermethrin, 3% of sodium dodecylbenzene sulfonate (wetting agent), 3% of phosphate ester (2210) (dispersant), 0.1% of formaldehyde (preservative), 0.1% of phosphoric acid (pH regulator), 4% of ethylene glycol (antifreeze agent), 0.5% of xanthan gum (thickener), 0.4% of organic silicone (defoaming agent), and the content is made up to 100% with water.

[0077] The specific steps of the preparation method of the deltamethrin suspension are as follows:

[0078] a. Weigh the above-mentioned deltamethrin, phosphate (2210), sodium dodecylbenzene sulfonate, ethylene glycol, formaldehyde and water respectively and put them into a stirring tank for shear mixing to obtain a mixed material;

[0079] b. At 20-30° C., the mixed material in step a is passed through a sand mill for sand grinding, while adding the above-mentioned weight content of organic silicone, and sand grinding to a particle size of 1-5 μm to obtain a sand-milled material;

[0080] c. Add the above-mentioned xanthan gum by weight to the sand-milled material obtained in step b, shear and stir evenly again, add the above-mentioned phosphoric acid by weight to adjust the pH value to 5.0-7.0, and obtain the cypermethrin suspension concentrate.

[0081] Comparative Example 4

[0082] A bifenthrin suspension comprises the following components by weight percentage: 20% of bifenthrin, 3% of sodium dodecylbenzene sulfonate (wetting agent), 3% of block polyether (5050PB) (dispersant), 0.1% of formaldehyde (preservative), 0.1% of phosphoric acid (pH regulator), 4% of ethylene glycol (antifreeze agent), 0.5% of xanthan gum (thickener), 0.4% of organic silicone (defoaming agent), and the content is made up to 100% with water.

[0083] The specific steps of the preparation method of the bifenthrin suspension are as follows:

[0084] a. Weigh the above-mentioned weight contents of bifenthrin, block polyether (5050PB), sodium dodecylbenzene sulfonate, ethylene glycol, formaldehyde and water respectively and put them into a stirring tank for shear mixing to obtain a mixed material;

[0085] b. At 20-30° C., the mixed material in step a is passed through a sand mill for sand grinding, while adding the above-mentioned weight content of organic silicone, and sand grinding to a particle size of 1-5 μm to obtain a sand-milled material;

[0086] c. Add the above-mentioned weight content of xanthan gum to the sand-milled material obtained in step b, shear and stir evenly again, add the above-mentioned weight content of phosphoric acid to adjust the pH value to 5.0-7.0, and obtain the bifenthrin suspension concentrate.

[0087] Example 5

[0088] Storage stability test

[0089] The sustained-release nanosuspensions of Examples 1 to 4 were subjected to storage stability tests, including hot storage tests and cold storage tests, respectively, at 54±2°C for 2 weeks and at 0±2°C for 1 week. After storage, it was found that the sustained-release nanosuspensions of Examples 1 to 4 of the present invention had uniform appearance, no crystals precipitated at different temperatures, and good pourability. 90 The particle size of the microparticles is between 200 and 300 nm, and the suspension rate is above 99% (see Table 1).

[0090] Table 1 Physical stability test results of sustained-release nanosuspension of the present invention

[0091]

[0092] Example 6

[0093] Field application

[0094] Test crop: Tobacco, variety Yunyan 87

[0095] Target: Aphids

[0096] Test agents: The treatment agent is the 2.5% high-efficiency cyhalothrin nanosuspension of Example 1, the control agent is the 2.5% high-efficiency cyhalothrin suspension of Comparative Example 1, and the blank control is an equal amount of clean water.

[0097] Test method: The test was conducted at Hongyan Tobacco Station in Huaning County, Yuxi City, Yunnan Province from July to August 2023. When the density of tobacco aphids exceeded the control index, a backpack electric sprayer was used to spray the rice plants with each of the above-mentioned test agents once. The amount of the liquid was 750 liters / hectare. Each agent treatment was repeated 4 times, and the plot area was 40m 2 The insect population base was investigated before the application of pesticides. At 1, 3, 7, and 14 days after the application of pesticides, five points were sampled using the five-point sampling method, with five plants at each point, to investigate the number of live insects. Finally, the statistical test results were analyzed and the difference significance was analyzed.

[0098] Insect population reduction rate (%) = [(number of insects before application - number of insects after application) ÷ number of insects before application] × 100% Formula 1.

[0099] Control effect (%) = [(insect population reduction rate in treatment area - insect population reduction rate in blank control area) ÷ (100 - insect population reduction rate in blank control area)] × 100% Formula 2.

[0100] Table 2 The results of the efficacy test of the sustained-release nanosuspension of the present invention against tobacco aphids

[0101]

[0102] Note: Different lowercase letters after the data in the same column represent the significance of the difference when P≤0.05 under Duncan's new multiple range test.

[0103] As can be seen from the data in Table 2, the sustained-release nanosuspension of Example 1 exhibits a good control effect on tobacco aphids, and the control effect is greatly improved compared with that of Comparative Example 1. Moreover, compared with the comparative example, the sustained-release nanosuspension of Example 1 has a prolonged effect duration, and the control effect can still reach 89.6% 14 days after application, which is much higher than 73.4% of the control.

[0104] Example 7

[0105] Field application

[0106] Test crop: Cabbage, variety Zhonggan No. 11

[0107] Target of control: Beet armyworm

[0108] Test agents: 5% efficient cyhalothrin nanosuspension of Example 2, 10% deltamethrin nanosuspension of Example 3, 20% bifenthrin nanosuspension of Example 4; 2.5% efficient cyhalothrin suspension of Comparative Example 2, deltamethrin suspension of Comparative Example 3, bifenthrin suspension of Comparative Example 4; blank control was an equal amount of clean water.

[0109] Test method: The test was conducted in the experimental field of Northwest Agriculture and Forestry University in Yangling District, Xianyang City, Shaanxi Province from August to September 2022. During the peak period of beet armyworm, a backpack electric sprayer was used to spray the cabbage plants with each of the above-mentioned test agents once. The amount of the liquid was 900 liters / hectare. Each agent treatment was repeated 4 times, and the plot area was 30m 2 . At 3, 7 and 14 days after application, a five-point sampling method was used, and 8 plants were sampled at each point to investigate the number of all insects at different ages of the whole plant. The base number of beet armyworm larvae was investigated before application, and the insect population reduction rate and control effect were calculated. Finally, the statistical test results were analyzed and the difference significance analysis was performed. Among them, the calculation method of the insect population reduction rate and control effect can be found in Formula 1 and Formula 2.

[0110] Table 3 Field efficacy test results of the sustained-release nanosuspension of the present invention for controlling cabbage beet armyworm

[0111]

[0112] Note: Different lowercase letters after the data in the same column represent the significance of the difference when P≤0.05 under Duncan's new multiple range test.

[0113] It can be seen from the data in Table 3 that Examples 2 to 4 all showed good control effects on cabbage beet armyworm. Compared with the comparative examples, the sustained-release nanosuspensions of Examples 1 to 4 had significantly prolonged effective periods on beet armyworm, and the control effects were significantly improved. The examples showed significant differences compared with the comparative examples.

[0114] 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. A sustained-release nanosuspension, characterized in that: The raw materials are as follows: 1% to 20% of pyrethroid original drug, 3% to 8% of wetting agent, 2% to 7% of dispersant, 4% to 6% of antifreeze agent, 0.05% to 1% of defoaming agent, 0.01% to 1% of preservative, 0.01% to 0.4% of pH regulator, and water is added to 100%; The wetting agents are polyvinyl alcohol and sodium lignin sulfonate, and the mass ratio of the polyvinyl alcohol to the sodium lignin sulfonate is 1 to 3:

3.

2. The sustained-release nanosuspension according to claim 1, characterized in that: The particle size of the sustained-release nano suspension is 200-500 nm.

3. The sustained-release nanosuspension according to claim 1, characterized in that: The pyrethroid original drug includes one or more of highly effective cyhalothrin, cypermethrin, permethrin, deltamethrin, cypermethrin, highly effective cypermethrin, cis-cypermethrin, cypermethrin, cypermethrin, cypermethrin, cypermethrin, cypermethrin, cypermethrin, cypermethrin, cypermethrin, cypermethrin, cypermethrin, cypermethrin, cypermethrin, cypermethrin, cypermethrin, cypermethrin, cypermethrin, cypermethrin, cypermethrin and bifenthrin.

4. The sustained-release nanosuspension according to claim 1, characterized in that: The dispersant includes one or both of phosphate ester and block polyether.

5. The sustained-release nanosuspension according to claim 4, characterized in that: The phosphate ester includes one of 33SC, 500LQ, 2210 and 1020; the block polyether includes one of 5500 and 5050PB.

6. The sustained-release nanosuspension according to claim 1, characterized in that: The defoaming agent includes ester-ether type compounds, C8-C 10 One or more of fatty alcohol, organic silicone and silicone oil; the preservative includes one or more of formaldehyde, sodium benzoate and potassium sorbate; the pH adjuster includes one or more of phosphoric acid, lactic acid and citric acid; the pH value of the sustained-release nanosuspension is 5.0-7.0; the antifreeze agent is ethylene glycol.

7. A method for preparing the sustained-release nanosuspension according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) mixing the pyrethroid technical, a dispersant, a wetting agent, an antifreeze agent, a preservative and water to obtain a mixed slurry; (2) sand-grinding the mixed slurry, adding the defoaming agent during the grinding process to obtain a sand-grinded slurry; (3) The sand-milled slurry is mixed with the pH regulator to obtain a sustained-release nanosuspension.

8. The preparation method according to claim 7, characterized in that: The sand grinding temperature is 20-30°C, and the sand grinding is performed to a particle size of 200-500nm.

9. Use of the sustained-release nanosuspension according to any one of claims 1 to 6 or the preparation method according to claim 7 or 8 in controlling pests or preparing pesticides.

10. The use according to claim 9, characterized in that: The pests include one or more of aphids, cotton bollworms, beet armyworms, tea green leafhoppers and small cutworms.

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