A wettable powder for preventing caking of diuron and its preparation method

Abstract

This invention discloses an anti-caking diuron wettable powder and its preparation method, belonging to the field of pesticide formulation technology. By weight, it comprises: 20-40 parts diuron technical grade, 40-70 parts modified nano-hydrotalcite, 1-3 parts wetting agent, 3-8 parts dispersant, 0.5-2 parts anti-caking agent, and 0.5-2 parts stabilizer. The modified nano-hydrotalcite is synergistically modified by an aminosilane coupling agent and a polyacrylate compound. The preparation method includes: pre-mixing the components, treating with low-temperature plasma, mixing with deionized water to form a slurry, grinding to D90 ≤ 5 μm using a high-pressure homogenizer, and finally granulating by centrifugal spray drying. This invention achieves excellent dispersibility and storage stability through the synergistic effect of plasma treatment enhancing hydrophilicity, high-pressure homogenization achieving submicron-level pulverization and core-shell structure coating, and spray drying forming porous spherical particles.

Description

Technical Field

[0001] This invention belongs to the field of pesticide formulation technology, specifically relating to an anti-caking diuron wettable powder and its preparation method. Background Technology

[0002] Diuron is a highly effective, broad-spectrum substituted urea herbicide that exerts its herbicidal activity primarily by inhibiting the Hill reaction in weed photosynthesis. It is widely used in non-arable land such as cotton, corn, sugarcane, and orchards, as well as in various crop fields, to control annual grasses and broadleaf weeds. Wettable powder formulations are one of the most common formulations of diuron due to their low production cost, convenient storage and transportation, crop safety, and environmental friendliness.

[0003] However, existing diuron wettable powders generally suffer from low suspension rates and poor physical stability in practical applications. During field spraying, solid particles in the pesticide solution easily settle rapidly in the spray can, resulting in lower concentrations of the first sprayed solution and higher concentrations of the later sprayed solution, causing uneven efficacy in the field and even localized crop damage. Furthermore, the product is prone to clumping and decomposition of active ingredients during heat storage, further reducing its dispersibility and suspension properties in water. These technical bottlenecks severely impact the field application efficacy and market competitiveness of diuron wettable powders.

[0004] To address the aforementioned issues, patent application CN112205413A discloses a method for preparing a wettable powder of atrazine composition. This method improves powder uniformity by optimizing the formulation and employing a multi-spiral composite mixer. However, its core filler, bentonite, lacks functional modification, resulting in limited improvement in suspension stability and anti-caking properties. Therefore, there is an urgent need to develop a novel diuron wettable powder and its preparation method that can enhance suspension stability and anti-caking performance while maintaining high efficiency and controllability. Summary of the Invention

[0005] One of the objectives of this invention is to provide an anti-caking diuron wettable powder to solve the problems of low suspension rate and easy agglomeration of existing diuron wettable powders.

[0006] The second objective of this invention is to provide a method for preparing an anti-caking diuron wettable powder, which is used to prepare the aforementioned anti-caking diuron wettable powder.

[0007] The objective of this invention can be achieved through the following technical solutions: In a first aspect, an anti-caking diuron wettable powder, comprising, by weight: 20-40 parts of diuron technical grade, 40-70 parts of modified nano-hydrotalcite, 1-3 parts of wetting agent, 3-8 parts of dispersant, 0.5-2 parts of anti-caking agent, and 0.5-2 parts of stabilizer; wherein the modified nano-hydrotalcite is nano-hydrotalcite synergistically modified with an aminosilane coupling agent and a polyacrylate compound.

[0008] The core of this invention lies in introducing nano-layered double hydroxides (LDHs) synergistically modified with aminosilane coupling agents and polyacrylate compounds as functional fillers. Nano-layered double hydroxides (LDHs) possess a unique layered structure, high specific surface area, and a permanent positive charge. Through the bridging effect of the aminosilane coupling agent, amino groups are introduced onto the LDH surface, and then negatively charged polyacrylate long chains are adsorbed onto the positively charged LDH surface via electrostatic self-assembly. When this modified LDH coexists with diuron technical grade pesticide, its large specific surface area and abundant functional groups strongly adsorb the pesticide particles, thereby solving the problems of low suspension rate and easy agglomeration.

[0009] Furthermore, the preparation method of the modified nano-hydrotalcite includes: (1) Disperse nano-hydrotalcite in an aqueous ethanol solution, add an aminosilane coupling agent, and react at 50-70℃ for 2-4 hours to obtain amino-modified nano-hydrotalcite; (2) Disperse the aminated nano-hydrotalcite in water, add polyacrylate compounds, stir and react at room temperature for 1-2 hours, and use electrostatic interaction to make PAAS self-assemble on the surface of the nano-hydrotalcite. Filter, wash and dry to obtain modified nano-hydrotalcite.

[0010] The first step involves introducing amino groups into the LDH surface through a condensation reaction between an aminosilane coupling agent (such as KH550) and the hydroxyl groups on the LDH surface, achieving organic functionalization modification. The second step utilizes the fact that the LDH layers carry a permanent positive charge, while sodium polyacrylate (PAAS) becomes negatively charged after dissociation in water. Electrostatic attraction causes the long PAAS chains to self-assemble onto the LDH surface. This ensures uniform and robust grafting of PAAS onto the LDH surface, providing a structural basis for subsequent steric stabilization.

[0011] Furthermore, the mass ratio of the nano-hydrotalcite, aminosilane coupling agent and polyacrylate compound is 100:(1-3):(2-5).

[0012] If the amount of aminosilane coupling agent is too low, there will be insufficient amino groups grafted onto the LDH surface, resulting in limited electrostatic adsorption of PAAS. If the amount is too high, self-polymerization of the coupling agent may occur, which will reduce the modification effect. If the amount of PAAS is too low, the steric hindrance effect will be insufficient. If the amount is too high, an excessively thick polymer layer may form on the particle surface, leading to flocculation between particles.

[0013] Furthermore, the silane coupling agent is γ-aminopropyltriethoxysilane; the polyacrylate compound is sodium polyacrylate with a molecular weight of 3000-5000.

[0014] In the molecular structure of γ-aminopropyltriethoxysilane (KH550), the ethoxy group can condense with the hydroxyl group on the LDH surface to form a covalent bond, while the terminal amino group can provide a positively charged site to form an electrostatic adsorption with the negatively charged PAAS.

[0015] Furthermore, the wetting agent is one or more of sodium dodecyl sulfate, BX dispersant, and alkyl naphthalene sulfonate; the dispersant is one or more of sodium lignosulfonate, polycarboxylate, and naphthalene sulfonate formaldehyde condensate; the anti-caking agent is one or more of precipitated silica, modified starch, and microcrystalline cellulose; and the stabilizer is one or more of epoxidized soybean oil, citric acid, and butylated hydroxyanisole.

[0016] The wetting agent is an anionic surfactant that effectively reduces the surface tension of water, allowing the powder to be quickly wetted. It also exhibits good compatibility with the PAAS chains on the modified LDH surface. The dispersant further provides additional electrostatic repulsion and steric hindrance, enhancing the stability of the suspension system. The anti-caking agents are mostly water-insoluble powders that form physical barriers between particles, preventing moisture absorption and clumping. Among the stabilizers, epoxidized soybean oil inhibits the photolysis of diuron, citric acid chelates metal ions to prevent catalytic decomposition, and butylated hydroxyanisole (BHA) acts as an antioxidant to prevent the oxidative degradation of the active ingredients.

[0017] Secondly, a method for preparing an anti-caking diuron wettable powder includes the following steps: S1. Add the prescribed amounts of diuron technical, modified nano-hydrotalcite, wetting agent, dispersant, anti-caking agent, and stabilizer to a double-helix conical mixer and premix until homogeneous to obtain a mixture. S2. Place the mixture obtained in S1 in a low-temperature plasma treatment device and treat it for 5-15 minutes in an oxygen or nitrogen atmosphere to obtain plasma-treated material. S3. Mix the plasma-treated material obtained in S2 with deionized water at a mass ratio of 1:(0.8-1.2) to form a slurry. Then, perform circulating grinding through a high-pressure homogenizer to control the average particle size D90 of the ground material to ≤5μm, and obtain the grinding slurry. S4. The grinding slurry obtained in S3 is granulated and dried by a centrifugal spray dryer. The inlet air temperature is controlled at 100-120℃ and the outlet air temperature is controlled at 50-60℃ to obtain dry wettable powder granules. S5. After drying, the granules are passed through an 80-mesh sieve and packaged after passing inspection to obtain anti-caking diuron wettable powder.

[0018] S1 premixing ensures initial uniform dispersion of all components; S2 low-temperature plasma treatment introduces polar functional groups such as hydroxyl and carboxyl groups onto the material surface, significantly enhancing the hydrophilicity of the powder; S3 mixes the plasma-treated material with water to form a slurry, which is then circulated and ground using a high-pressure homogenizer. The cavitation effect, shear force, and impact force generated by the high pressure efficiently break the material to the submicron level, while simultaneously allowing the polyacrylate long chains on the surface of the modified nano-hydrotalcite to uniformly coat the surface of the diuron particles under shear force; S4 centrifugal spray drying rapidly evaporates moisture, giving the product excellent flowability and self-dispersibility; S5 sieving and inspection ensure uniform particle size and quality compliance of the product.

[0019] Furthermore, in S2, the power of the low-temperature plasma treatment is 200-500W, the treatment atmosphere is oxygen, and the pressure is 30-60Pa.

[0020] The plasma treatment power directly affects the degree of surface modification. Too low a power results in insufficient active particles and insignificant surface modification; too high a power may cause excessive etching or thermal damage to the material surface. An oxygen atmosphere is chosen because the hydroxyl and carboxyl groups introduced by oxygen plasma are highly hydrophilic, thus having the most significant promoting effect on subsequent aqueous phase grinding.

[0021] Furthermore, in S3, the grinding pressure of the high-pressure homogenizer is 80-120 MPa, and the number of cyclic grinding cycles is 3-5.

[0022] High-pressure homogenizers utilize high pressure to force slurry through narrow gaps, efficiently crushing materials to submicron levels. Particle sizes with D90 ≤ 5 μm are ideal; excessively coarse particles result in low suspension rates and rapid sedimentation, while excessively fine particles lead to excessively high surface energy and secondary agglomeration. During this process, the PAAS chains on the modified LDH surface uniformly coat the surface of diuron particles under shear force, achieving a tight composite of the active ingredient and functional filler.

[0023] Furthermore, in step S3, before high-pressure homogenization grinding, a defoamer accounting for 0.1%-0.3% of the total mass of the slurry is added.

[0024] During high-pressure homogenization, a large number of microbubbles are generated in the slurry due to strong cavitation and shearing effects. These bubbles not only reduce homogenization efficiency but also lead to uneven droplet distribution during subsequent spray drying. Adding a trace amount of defoamer can quickly break these bubbles, ensuring the stable progress of the homogenization process.

[0025] Furthermore, in S4, the rotation speed of the atomizing disc in the centrifugal spray dryer is 15,000-20,000 rpm.

[0026] A rotation speed range of 15,000-20,000 rpm can produce droplets with a D50 of 20-50 μm, which, after drying, form spherical particles with uniform particle size and good flowability. At the same time, the centrifugal force generated by high-speed rotation ensures that the droplets are evenly distributed in the drying chamber, avoiding local overheating or sticking to the walls.

[0027] The beneficial effects of this invention are: (1) The present invention provides an anti-caking diuron wettable powder, comprising, by weight: 20-40 parts of diuron technical grade, 40-70 parts of modified nanofiller, 1-3 parts of wetting agent, 3-8 parts of dispersant, 0.5-2 parts of anti-caking agent, and 0.5-2 parts of stabilizer; wherein the modified nanofiller is nano-hydrotalcite synergistically modified with silane coupling agent and polyacrylate compound. This technical solution is not a simple superposition of the functions of each component, but rather a multi-dimensional stable system constructed through multiple synergistic effects between the components.

[0028] (2) The modified nano-hydrotalcite used in this invention introduces amino groups onto the LDH surface through an aminosilane coupling agent, and then adsorbs negatively charged PAAS long chains onto the positively charged LDH surface through electrostatic self-assembly, realizing a synergistic stabilization mechanism of "steric hindrance-electrostatic repulsion-interlayer isolation". The flexible long chains of PAAS provide steric hindrance, preventing particles from approaching; the positive charge of LDH and the negative charge after PAAS ionization form an electric double layer, providing electrostatic repulsion; the two-dimensional layered structure of LDH acts as a physical isolation layer after drying, preventing direct contact and sintering between the original drug particles, thus improving the suspension stability and anti-caking performance of diuron wettable powder.

[0029] (3) The preparation method used in this invention integrates low-temperature plasma treatment, high-pressure homogenizing milling, and spray drying technologies. Plasma treatment introduces polar groups on the surface of the material, enhancing its hydrophilicity; high-pressure homogenizing milling achieves submicron-level pulverization, promoting uniform coating of diuron by modified LDH; spray drying forms spherical particles with smooth surfaces and porous interiors, improving flowability and self-dispersibility. The synergistic effect of each step enhances the product performance. Detailed Implementation

[0030] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0031] Preparation Example 1: Preparation of Modified Nano-hydrotalcite Take 100g of nano-hydrotalcite (chemical composition Mg6Al2(OH)). 16CO3·4H2O (particle size 50-100 nm) was dispersed in 1000 mL of ethanol / water (volume ratio 1:1) solution and ultrasonically dispersed for 30 minutes. 2 g of KH550 was added, and the mixture was stirred in a 60℃ water bath for 3 hours. After the reaction was complete, the mixture was centrifuged and washed three times with anhydrous ethanol to obtain aminated nano-hydrotalcite. Aminated nano-hydrotalcite was redispersed in 1000 mL of deionized water, and 3 g of sodium polyacrylate (PAAS, molecular weight 3000) was added. The mixture was stirred and reacted at room temperature for 1.5 hours. After the reaction was completed, the mixture was centrifuged, washed three times with deionized water, vacuum dried at 80 °C for 12 hours, and ground through a 200-mesh sieve to obtain modified nano-hydrotalcite.

[0032] Preparation Example 2: Preparation of Modified Nano-Layer Hydrotalcite The difference from Preparation Example 1 is that the amount of KH550 added is 3g and the amount of PAAS added is 5g.

[0033] Preparation Example 3: Preparation of Modified Nano-Layer Hydrotalcite The difference from Preparation Example 1 is that the amount of KH550 added is 1.5g and the amount of PAAS added is 2.5g.

[0034] Example 1 This embodiment provides an anti-caking diuron wettable powder, which is prepared through the following steps: S1. Add 30 parts of diuron technical grade, 61 parts of modified nano-hydrotalcite (preparation example 1), 2 parts of wetting agent sodium dodecyl sulfate, 5 parts of dispersant sodium lignosulfonate, 1 part of anti-caking agent precipitated silica, and 1 part of stabilizer epoxidized soybean oil to a double helix conical mixer and premix for 30 minutes to obtain a mixture. S2. Spread the mixture obtained in S1 evenly on the tray of the low-temperature plasma treatment equipment, evacuate to 40Pa, introduce oxygen to a pressure of 50Pa, and treat at 300W power for 10 minutes to obtain plasma-treated material. S3. Mix the plasma-treated material obtained in S2 with deionized water at a mass ratio of 1:1, add 0.2% (accounting for the total mass of the slurry) of defoamer, stir evenly to make a slurry, and then circulate and grind it 4 times under a pressure of 100MPa using a high-pressure homogenizer to obtain a ground slurry with a D90 of 3.9μm. S4. The grinding slurry obtained in S3 is dried by a centrifugal spray dryer with an inlet air temperature of 110℃, an outlet air temperature of 55℃, and an atomizing disc speed of 18000rpm. The dried powder is then collected. S5. Pass the dried powder through an 80-mesh sieve to obtain anti-caking diuron wettable powder.

[0035] Example 2 The difference between this embodiment and Example 1 is that 35 parts of diuron technical grade, 54 parts of modified nano-hydrotalcite (Preparation Example 2), 2.5 parts of wetting agent BX, 6 parts of dispersant polycarboxylate, 1.5 parts of anti-caking agent microcrystalline cellulose, and 1 part of stabilizer citric acid.

[0036] In S2, the plasma processing power is 400W and the processing time is 8 minutes; in S3, the grinding pressure is 120MPa, the grinding is repeated 3 times, and the D90 is 3.5μm; in S4, the inlet air temperature is 105℃, the outlet air temperature is 60℃, and the atomizing disc speed is 20000rpm.

[0037] The remaining raw materials and preparation process are the same as in Example 1.

[0038] Example 3 The difference between this embodiment and Example 1 is that the amount of diuron technical material is 25 parts, modified nano-hydrotalcite (preparation example 3) is 68.2 parts, wetting agent is alkyl naphthalene sulfonate 1.5 parts, dispersant is naphthalene sulfonate formaldehyde condensate 4 parts, anti-caking agent is precipitated silica 0.8 parts, and stabilizer is butylated hydroxyanisole 0.5 parts.

[0039] In S2, the plasma treatment atmosphere is nitrogen, the power is 250W, and the treatment time is 12 minutes; in S3, the grinding pressure is 90MPa, the grinding is repeated 5 times, and the D90 is 4.2μm; in S4, the inlet air temperature is 115℃, the outlet air temperature is 50℃, and the atomizing disc speed is 16000rpm.

[0040] The remaining raw materials and preparation process are the same as in Example 1.

[0041] Example 4 The difference between this embodiment and Example 1 is that 30 parts of diuron technical grade, 61 parts of modified nano-hydrotalcite (Preparation Example 1), 2 parts of sodium dodecyl sulfate wetting agent, 5 parts of sodium lignosulfonate dispersant, 1 part of precipitated silica anti-caking agent, and 1 part of epoxidized soybean oil stabilizer.

[0042] In S2, the plasma treatment time is extended to 15 minutes, and the power is 200W.

[0043] The remaining raw materials and preparation process are the same as in Example 1.

[0044] Example 5 The difference between this embodiment and Example 1 is that 30 parts of diuron technical grade, 61 parts of modified nano-hydrotalcite (Preparation Example 1), 2 parts of sodium dodecyl sulfate wetting agent, 5 parts of sodium lignosulfonate dispersant, 1 part of precipitated silica anti-caking agent, and 1 part of epoxidized soybean oil stabilizer.

[0045] The high-pressure homogenizing milling pressure in S3 was reduced to 80 MPa, and after 5 cycles of milling, the D90 was 4.1 μm.

[0046] The remaining raw materials and preparation process are the same as in Example 1.

[0047] Example 6 The difference between this embodiment and Example 1 is that 20 parts of diuron technical grade, 75 parts of modified nano-hydrotalcite (Preparation Example 3), 1 part of sodium dodecyl sulfate wetting agent, 3 parts of sodium lignosulfonate dispersant, 0.5 parts of precipitated silica anti-caking agent, and 0.5 parts of epoxidized soybean oil stabilizer.

[0048] The remaining raw materials and preparation process are the same as in Example 1.

[0049] Example 7 Compared with Example 1, the difference in this embodiment is that 40 parts of diuron technical grade, 45 parts of modified nano-hydrotalcite (Preparation Example 2), 3 parts of wetting agent BX, 8 parts of dispersant polycarboxylate, 2 parts of anti-caking agent microcrystalline cellulose, and 2 parts of stabilizer citric acid.

[0050] The remaining raw materials and preparation process are the same as in Example 1.

[0051] Comparative Example 1 The difference between this comparative example and Example 1 is that the modified nano-hydrotalcite was replaced with an equal amount (61 parts) of ordinary bentonite.

[0052] The remaining raw materials and preparation process are the same as in Example 1.

[0053] Comparative Example 2 The difference between this comparative example and Example 1 is that the modified nano-hydrotalcite was replaced with an equal amount (61 parts) of unmodified nano-hydrotalcite.

[0054] The remaining raw materials and preparation process are the same as in Example 1.

[0055] Comparative Example 3 The difference between this comparative example and Example 1 is that the modified nano-hydrotalcite was replaced with an equal amount (61 parts) of nano-hydrotalcite modified only with KH550.

[0056] The remaining raw materials and preparation process are the same as in Example 1.

[0057] Comparative Example 4 The difference between this comparative example and Example 1 is that the low-temperature plasma treatment in step S2 is omitted.

[0058] The remaining raw materials and preparation process are the same as in Example 1.

[0059] Comparative Example 5 The difference between this comparative example and Example 1 is that the high-pressure homogenizing grinding in step S3 is replaced with conventional airflow milling (milling pressure 0.8 MPa, milling to 800 mesh).

[0060] The remaining raw materials and preparation process are the same as in Example 1.

[0061] Performance testing The performance of the anti-caking diuron wettable powder prepared in Examples 1-7 and Comparative Examples 1-5 was tested according to national standards.

[0062] 1. Suspension rate determination: Refer to GB / T 14825-2023 "Method for Determination of Suspension Rate of Pesticides". The specific steps are as follows: Weigh an appropriate amount of sample (accurate to 0.0002g), place it in a graduated cylinder containing standard hard water, disperse and settle it according to the prescribed method, determine the content of active ingredients in the bottom one-tenth of the suspension, and calculate the suspension rate.

[0063] 2. Determination of thermal storage stability: Refer to GB / T 19136-2021 "Determination of thermal storage stability of pesticides". The specific steps are as follows: seal the sample in an ampoule and store it in a constant temperature chamber at (54±2)℃ for 14 days. After taking it out, cool it to room temperature and determine the decomposition rate of the active ingredient and the suspension rate after thermal storage.

[0064] 3. Disintegration time determination: Add 100 mL of standard hard water to a 250 mL graduated cylinder, weigh 0.5 g of sample, drop it freely from the top of the graduated cylinder, and record the time required for the sample to completely sink into the water and disperse evenly (without visible solid particles).

[0065] The test results are shown in Table 1: Table 1

[0066] As shown in Table 1, the suspension rates of the diuron wettable powder prepared in Examples 1-7 all exceeded 93%, reaching a maximum of 95.5%, which is higher than all comparative examples. This indicates that the modified nano-hydrotalcite and its specific proportions used in this invention, combined with the preparation method of this invention, can achieve a high suspension rate for diuron wettable powder. The thermal decomposition rates of Examples 1-7 were all below 0.32%, far lower than those of Comparative Examples 1-5, indicating that the multi-stabilized system is effective not only at room temperature but also under high-temperature accelerated conditions, effectively protecting the active ingredients and preventing their decomposition. Furthermore, the suspension rate remained above 91% after thermal storage, demonstrating the long-term stability of the system.

[0067] Comparing Example 1 with Comparative Examples 1 and 2, it can be seen that the suspension rate and thermal storage stability of samples using ordinary bentonite or unmodified nano-hydrotalcite are significantly lower than those of Example 1, confirming the crucial role of modified nano-hydrotalcite as a core filler. Comparing Example 1 with Comparative Example 3, it can be seen that the sample modified with KH550 without PAAS electrostatic self-assembly, while superior to Comparative Example 2, still significantly inferior to Example 1, demonstrating that the steric hindrance provided by PAAS is crucial for improving suspension stability and anti-caking performance. Comparing Example 1 with Comparative Example 4, it can be seen that omitting low-temperature plasma treatment reduces both the suspension rate and the suspension rate after thermal storage, indicating that plasma treatment promotes grinding and dispersion by enhancing the hydrophilicity of the material. Comparing Example 1 with Comparative Example 5, it can be seen that replacing high-pressure homogenizing milling with traditional airflow milling significantly reduces the suspension rate and significantly increases the particle size, demonstrating the unique advantages of high-pressure homogenizing milling in achieving submicron-level pulverization and promoting uniform coating of the active ingredient by modified fillers.

[0068] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A wettable powder for preventing caking, characterized in that, By weight, it includes: 20-40 parts of diuron technical grade, 40-70 parts of modified nano-hydrotalcite, 1-3 parts of wetting agent, 3-8 parts of dispersant, 0.5-2 parts of anti-caking agent, and 0.5-2 parts of stabilizer; wherein the modified nano-hydrotalcite is nano-hydrotalcite synergistically modified with aminosilane coupling agent and polyacrylate compound.

2. The anti-caking diuron wettable powder according to claim 1, characterized in that, The preparation method of the modified nano-hydrotalcite includes: (1) Disperse nano-hydrotalcite in an aqueous ethanol solution, add an aminosilane coupling agent, and react at 50-70℃ for 2-4 hours to obtain amino-modified nano-hydrotalcite; (2) Disperse the aminated nano-hydrotalcite in water, add polyacrylate compounds, stir and react at room temperature for 1-2 hours, and use electrostatic interaction to make PAAS self-assemble on the surface of the nano-hydrotalcite. Filter, wash and dry to obtain modified nano-hydrotalcite.

3. The anti-caking diuron wettable powder according to claim 1, characterized in that, The mass ratio of the nano-hydrotalcite, aminosilane coupling agent and polyacrylate compound is 100:(1-3):(2-5).

4. The anti-caking diuron wettable powder according to claim 1, characterized in that, The silane coupling agent is γ-aminopropyltriethoxysilane; the polyacrylate compound is sodium polyacrylate with a molecular weight of 3000-5000.

5. The anti-caking diuron wettable powder according to claim 1, characterized in that, The wetting agent is one or more of sodium dodecyl sulfate, BX dispersant, and alkyl naphthalene sulfonate; the dispersant is one or more of sodium lignosulfonate, polycarboxylate, and naphthalene sulfonate formaldehyde condensate; the anti-caking agent is one or more of precipitated silica, modified starch, and microcrystalline cellulose; and the stabilizer is one or more of epoxidized soybean oil, citric acid, and butylated hydroxyanisole.

6. A method for preparing an anti-caking diuron wettable powder, characterized in that, The preparation of the anti-caking diuron wettable powder according to any one of claims 1-5 includes the following steps: S1. Add the prescribed amounts of diuron technical, modified nano-hydrotalcite, wetting agent, dispersant, anti-caking agent, and stabilizer to a double-helix conical mixer and premix until homogeneous to obtain a mixture. S2. Place the mixture obtained in S1 in a low-temperature plasma treatment device and treat it for 5-15 minutes in an oxygen or nitrogen atmosphere to obtain plasma-treated material. S3. Mix the plasma-treated material obtained in S2 with deionized water at a mass ratio of 1:(0.8-1.2) to form a slurry. Then, perform circulating grinding through a high-pressure homogenizer to control the average particle size D90 of the ground material to ≤5μm, and obtain the grinding slurry. S4. The grinding slurry obtained in S3 is granulated and dried by a centrifugal spray dryer. The inlet air temperature is controlled at 100-120℃ and the outlet air temperature is controlled at 50-60℃ to obtain dry wettable powder granules. S5. After drying, the granules are passed through an 80-mesh sieve and packaged after passing inspection to obtain anti-caking diuron wettable powder.

7. The method for preparing an anti-caking diuron wettable powder according to claim 6, characterized in that, In S2, the power of the low-temperature plasma treatment is 200-500W, the treatment atmosphere is oxygen, and the pressure is 30-60Pa.

8. The method for preparing an anti-caking diuron wettable powder according to claim 6, characterized in that, In S3, the grinding pressure of the high-pressure homogenizer is 80-120MPa, and the number of cyclic grinding cycles is 3-5.

9. The method for preparing an anti-caking diuron wettable powder according to claim 6, characterized in that, In step S3, before high-pressure homogenization grinding, a defoamer accounting for 0.1%-0.3% of the total mass of the slurry is added.

10. The method for preparing an anti-caking diuron wettable powder according to claim 6, characterized in that, In step S4, the rotation speed of the atomizing disc in the centrifugal spray dryer is 15,000-20,000 rpm.

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