Method for preparing hectorite-based chlorantraniliprole nano suspending agent based on high-pressure microjet homogenization technology

Abstract

The invention discloses a method for preparing a hectorite-based chlorantraniliprole nano suspending agent based on a high-pressure micro-jet homogenization technology, which comprises the following steps: dispersing hectorite in water to obtain a colloidal suspension, then dispersing chlorantraniliprole powder in a reaction liquid, stirring at a high speed to form a uniform suspension, and then adding the uniform suspension into the colloidal suspension to prepare the hectorite-based chlorantraniliprole nano suspending agent. Treating the suspension through a high-pressure micro-jet homogenizer, and then encapsulating by adopting natural polymer to obtain the nano pesticide suspending agent. The colloidal property, adsorbability and carrier function of hectorite and the encapsulation treatment of natural polymer are utilized, and the key sticking point problems of poor water dispersibility, large average particle size, poor storage stability and the like of the pesticide are effectively solved through a high-pressure microjet homogenization technology.

Description

Technical Field

[0001] This invention relates to a nanopesticide suspension, specifically to a method for preparing lithium saponite-based chlorantraniliprole nanoparticle suspension based on high-pressure microfluidic homogenization technology, belonging to the field of nanopesticide application technology. Background Technology

[0002] Currently, the commonly used preparation processes for pesticide nano-suspensions mainly include two types: bottom-up and top-down methods. The bottom-up method is a preparation technique that constructs nanoparticles through molecular or atomic assembly. This process is relatively complex, has low yield, high cost, and most research remains in the laboratory, making large-scale production difficult. The top-down method involves applying high-intensity mechanical force to gradually refine large pesticide particles, ultimately obtaining nanoscale pesticide particles with uniform particle size distribution. This mainly includes media grinding methods (…). Chemical Engineering Journal,2025,503:158168 ), high-pressure homogenization method ( Pesticide Science Journal, 2014, 16(6): 635-643 ), microfluidic method ( 20241031305.X (etc.) Among these, the grinding method for preparing nano-suspensions requires a long time, and the large amount of heat generated during prolonged grinding can easily cause thermal aggregation between particles, thus affecting the stability of the nano-suspension, and the production energy consumption is high. High-pressure homogenization technology uses mechanical shearing and impact under high pressure to crush and disperse samples, which has advantages such as simple operation and narrow particle size distribution, but the equipment is prone to wear and has limited capacity to handle high-concentration, high-viscosity materials. Modern Pesticides, 2025, 24(3):1~8 High-pressure microjets homogenize the sample by ejecting it with high-pressure gas, accelerating and dispersing it at room temperature within a micrometer-scale jet, resulting in nanometer-sized particles. Compared to high-pressure homogenization, high-pressure microjets utilize the shear and impact forces generated by the high-speed gas flow to disperse the sample, resulting in a narrower particle size distribution and better dispersion.

[0003] Therefore, considering the advantages and disadvantages of the above-mentioned preparation technologies, based on the invention patent 202411424056.X, this invention proposes to use high-pressure microfluidic homogenization technology to peel off the sheet aggregates of lithium saponite to make them nano-sized, and then combine it with natural polymer encapsulation technology to prepare a nano-pesticide suspension that is long-lasting and stable in water. Summary of the Invention

[0004] This invention aims to overcome the shortcomings of existing chlorantraniliprole nano-suspension preparation technologies, such as complex processes, reliance on multiple chemical auxiliaries, incomplete carrier nano-suspension, and insufficient long-term physical stability of the formulation. It provides a chlorantraniliprole nano-suspension with a simple process, green and environmentally friendly technology, which can simultaneously achieve efficient carrier nano-suspension and high formulation stability, as well as its preparation method.

[0005] To achieve the above objectives, the first aspect of this invention provides a method for preparing lithium saponite-based chlorantraniliprole nano-suspensions based on high-pressure microfluidic homogenization technology. This method creatively combines the carrier function of synthetic lithium saponite, the deep exfoliation and nano-sizing capabilities of high-pressure microfluidic homogenization, and the environmentally friendly encapsulation and stabilizing effect of natural polymers, all simultaneously in a continuous and efficient process system.

[0006] The method specifically includes the following steps: (1) Preparation of lithium saponite colloidal suspension: Synthetic lithium saponite with a mass percentage concentration of 0.5%~5.0% is dispersed in water to initially form a colloidal suspension. In this step, lithium saponite begins to hydrate and expand, but its lamellae are still in an aggregated state.

[0007] (2) Preparation of drug premix suspension: The chlorantraniliprole technical powder that has been pulverized and passed through a 200-mesh sieve is added to the suspension obtained in step (1) to make its mass percentage concentration in the final system reach 15%~40%. Then, the mixture is stirred for 10 minutes under high-speed shear at 4000~10000 rpm to initially disperse the drug and attach it to the surface and interlayer of the lithium saponite aggregate using intense turbulence.

[0008] (3) High-pressure microjets homogenizing nano-sizing treatment: The suspension obtained in step (2) is introduced into a high-pressure microjets homogenizing device and treated under ultra-high pressure of 10~150 MPa. This step is the key to the technological breakthrough of this invention: the extreme shear force, cavitation effect and shock wave generated by the high-pressure microjets can directly act on the interlayer bonding surface of lithium saponite, effectively weakening and peeling off its face-to-face stacked sheet structure, and dissociating the micron-sized aggregates into single-layer or few-layer nanosheets with a thickness of only a few nanometers. At the same time, this powerful mechanical force field also forces the chlorantraniliprole particles to be further refined and more firmly and uniformly loaded or embedded on the surface of the newly exposed huge nanosheets.

[0009] (4) In-situ encapsulation and stabilization with natural polymers: 0.1% to 2.0% by mass of natural polymers are directly added to the nanodispersion obtained after homogenization in step (3). The natural polymers are selected from at least one of chitosan or its alkylated, hydroxylated, or carboxylated derivatives. The reaction is carried out for 1 to 4 hours under gentle stirring at 1000 to 3000 rpm. During this process, the natural polymer chains form a flexible coating film on the surface of the drug-loaded lithium saponite nanosheets through mechanisms such as hydrogen bonding and electrostatic interactions. This encapsulation layer can not only effectively prevent the re-aggregation of nanoparticles through steric hindrance, but also further improve the colloidal stability of the system during long-term storage.

[0010] The second aspect of this invention provides a lithium saponite-based chlorantraniliprole nano-suspending agent prepared by the above method. This suspending agent has the following characteristics: the average particle size of the active particles in the system is less than 100 nm, and they are uniformly distributed; under harsh stability test conditions (sealed storage at 54±2°C for 14 days and sealed storage at 0±2°C for 7 days), there is no water separation, stratification, or visible precipitation, demonstrating excellent physical stability.

[0011] The principle of this invention is as follows: based on the silicic magnesium hydroxyl groups and structural negative charge on the surface of lithium saponite, chlorantraniliprole is uniformly loaded onto lithium saponite sheets by high-speed stirring; high-pressure microfluidic homogenization treatment is performed to achieve effective exfoliation of lithium saponite sheets, further reduce their particle size, and achieve efficient loading of chlorantraniliprole; chitosan and its derivatives contain amino and hydroxyl groups and have good film-forming properties. After coating the loaded chlorantraniliprole / lithium saponite nanoparticles, the efficient preparation of aqueous nano-pesticide suspension is achieved.

[0012] Compared with the prior art, the present invention has the following significant advantages: (1) High process integration and simple process: Through the core process of high pressure micro-jet homogenization, the deep nano-sizing of the carrier, the ultra-fine processing of the drug and the combination of the two are completed simultaneously, replacing the multi-step operation of "pretreatment + ball milling" in the traditional process, shortening the process flow and improving production efficiency.

[0013] (2) Green and environmentally friendly: Water is used as the medium throughout the process, completely avoiding the use of organic solvents; natural biodegradable polymers such as chitosan are used as the main stabilizers, reducing or avoiding dependence on synthetic surfactants and chemical modifiers, and significantly improving the environmental friendliness of the product.

[0014] (3) Excellent product performance: The prepared nano-suspension has a small particle size (<100 nm) and narrow distribution, which greatly improves the specific surface area and potential biological activity of pesticides. More importantly, thanks to the synergistic stabilizing effect of lithium saponite nanosheets and natural polymers, the formulation exhibits outstanding long-term storage stability, solving the industry problems of easy agglomeration of nanoparticles and easy stratification of formulations.

[0015] (4) Raw materials are readily available and suitable for scale-up: The main raw material used, lithium saponite, is an industrially synthesized product with stable quality; the high-pressure micro-jet homogenizer is a mature industrial equipment with easy-to-control process parameters, and the entire technical solution has good prospects for large-scale production. Attached Figure Description

[0016] Figure 1 TEM images of (a) lithium saponite, (b) homogenized lithium saponite, and (c) the suspension obtained in Example 2.

[0017] Figure 2(a) chlorantraniliprole, (b) N - Infrared spectra of succinyl chitosan, (c) lithium saponite and (d) the suspension obtained in Example 2.

[0018] Figure 3 The effect of microjet homogeneous pressure on the particle size of lithium saponite.

[0019] Figure 4 The particle size distribution of the suspending agents obtained in the comparative examples and the embodiment is shown.

[0020] Figure 5 The suspension stability of the suspending agents obtained from the comparative examples and the examples after being stored at high temperature (A) and low temperature (B) for 14 days and 7 days, respectively (a. comparative example, b. example 1, c. example 2, d. example 3, e. example 4 and f. example 5). Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below with reference to specific embodiments and comparative examples. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0022] Example 1 At 300 rpm, 5.0 g of lithium saponite was dispersed in 100 mL of water to form a uniform colloidal suspension. Then, 20.0 g of chlorantraniliprole was added and stirred evenly. The mixture was stirred at 4000 rpm for 10 min. The suspension was then transferred to a reactor through a high-pressure microjet homogenizer with a pressure of 10 MPa. 0.1 g of water-soluble chitosan was added and the mixture was stirred at 3000 rpm for 1 h. The average particle size of the suspension was 98.2 nm.

[0023] Example 2 At 300 rpm, 0.75 g of lithium saponite was dispersed in 100 mL of water to form a homogeneous colloidal suspension. Then, 40.0 g of chlorantraniliprole was added and stirred until homogeneous. The mixture was stirred at 7000 rpm for 10 min. The suspension was then transferred to a reactor through a high-pressure microfluidic homogenizer at 90 MPa, and 0.1 g of [unspecified substance] was added. N - Succinyl chitosan was stirred at 1000 rpm for 1 h, and the average particle size of the suspension was 81.6 nm.

[0024] Example 3 At 300 rpm, 0.5 g of lithium saponite was dispersed in 100 mL of water to form a uniform colloidal suspension. Then, 10.0 g of chlorantraniliprole was added and stirred evenly. The mixture was stirred at 4000 rpm for 10 min. The suspension was then transferred to a reactor through a high-pressure microfluidic homogenizer with a pressure of 100 MPa. 1.75 g of hydroxypropyl chitosan was added and the mixture was stirred at 2000 rpm for 2 h. The average particle size of the suspension was 34.2 nm.

[0025] Example 4 At 300 rpm, 1.0 g of lithium saponite was dispersed in 100 mL of water to form a uniform colloidal suspension. Then, 20.0 g of chlorantraniliprole was added and stirred evenly. The mixture was stirred at 6000 rpm for 10 min. The suspension was then transferred to a reactor through a high-pressure microfluidic homogenizer with a pressure of 120 MPa. 2.0 g of hydroxyethyl chitosan was added and the mixture was stirred at 3000 rpm for 3 h. The average particle size of the suspension was 29.9 nm.

[0026] Example 5 At 300 rpm, 0.5 g of lithium saponite was dispersed in 100 mL of water to form a uniform colloidal suspension. Then, 5.0 g of chlorantraniliprole was added and stirred evenly. The mixture was stirred at 10,000 rpm for 10 min. The suspension was then transferred to a reactor through a high-pressure microfluidic homogenizer with a pressure of 150 MPa. 0.1 g of carboxymethyl chitosan was added and the mixture was stirred at 3000 rpm for 4 h. The average particle size of the suspension was 25.5 nm.

[0027] Comparative Example At 300 rpm, 0.5 g of lithium saponite was dispersed in 100 mL of water to form a uniform colloidal suspension. Then, 20.0 g of chlorantraniliprole was added and stirred evenly. The mixture was stirred at 4000 rpm for 10 min, and then 2.0 g of water-soluble chitosan was added. The mixture was stirred at 1000 rpm for 1 h. The average particle size of the suspension was 263.0 nm.

[0028] Structural characterization and performance evaluation of the above embodiments and comparative products: 1. Morphological and structural characterization Figure 1 TEM images of the lithium saponite before and after homogenization, and the suspension obtained in Example 2, are presented. Figure 1 It is evident that the lamellae of the synthetic lithium saponite exhibit an aggregated state (see...). Figure 1 a) After high-pressure microfluidic homogenization, the thickness of the exfoliated sheet is approximately 2–5 nm (see [link]). Figure 1(b) After drug loading, chlorantraniliprole particles, approximately 10 nm in size, are attached to the lithium saponite plates. Figure 1 c). Figure 2 Chlorantraniliprole (a) is given. N Infrared spectra of succinyl chitosan (b), lithium saponite (c), and the suspension obtained in Example 2 (d). From Figure 2 d can be seen in the range of 3400~2800 cm -1 and 1700~450 cm -1 The characteristic infrared absorption peak of chlorantraniliprole was observed (see...) Figure 2 a), at 1640 cm -1 1005 cm -1 and 449 cm -1 The characteristic infrared absorption peak of lithium saponite appeared at (see) Figure 2 c). The infrared absorption peak of lithium saponite showed a slight shift, indicating that lithium saponite mainly complexed with chlorantraniliprole through weak interactions such as hydrogen bonds and van der Waals forces. However... Figure 2 Except for d, which is between 2900 and 2800 cm -1 and 1665 cm -1 The infrared absorption peak at that location is affected N -The effect of succinyl chitosan was enhanced at 1642~450 cm⁻¹ -1 Receive N The infrared spectrum of succinyl chitosan was not significantly affected, which is attributed to the fact that it falls within this range. N The overlap of infrared absorption peaks between succinyl chitosan and chlorantraniliprole is the cause. The appearance of these absorption peaks indicates... N - Succinyl chitosan successfully encapsulated chlorantraniliprole / lithium saponite nanoparticles.

[0029] 2. Key Process Impact Analysis Effect of homogenization pressure on carrier particle size: To clarify the key role of high-pressure microjet homogenization, pure lithium saponite aqueous dispersions of different concentrations were prepared and treated once under pressures of 0~100 MPa, and their particle size distribution was measured.

[0030] The results are as follows Figure 3 As shown, the average particle size of lithium saponite decreases as the homogenization pressure increases from 0 MPa to 100 MPa. This indicates that high-pressure microfluidic homogenization can effectively break the interlayer aggregation of lithium saponite, which is a crucial process step for achieving its nano-scale formation and lays the structural foundation for subsequent loading and stability.

[0031] Particle size distribution curves for all embodiments and comparative examples ( Figure 4The results show that the particle size distribution peaks in the various embodiments of the present invention are narrower and more concentrated. The average particle size of the comparative example is 263.0 nm, while the average particle size of all embodiments is significantly less than 100 nm, demonstrating the significant advantages of the method of the present invention in obtaining small-sized, uniform nanoparticles.

[0032] 3. Storage stability evaluation Accelerated storage stability tests were conducted in accordance with relevant standards for pesticide formulation stability. Each sample was sealed in an ampoule and stored in a constant temperature oven at (54±2)℃ for 14 days (heat storage test), and in a refrigerator at (1±0.5)℃ for 7 days (cold storage test). After the tests, the samples were brought back to room temperature, and the state of the samples, as well as phenomena such as water separation and stratification of the suspension, were visually observed.

[0033] The results are as follows Figure 5 As shown, the comparative samples exhibited significant water separation and stratification after both hot and cold storage. However, all samples from the embodiments of this invention remained in a uniform suspension state after high and low temperature storage, with no visible water separation, stratification, or sediment formation. This fully demonstrates the effectiveness of the coating stabilization mechanism constructed from lithium saponite nanosheets and a natural polymer encapsulation layer.

Claims

1. A method for preparing lithium saponite-based chlorantraniliprole nano-suspension based on high-pressure microfluidic homogenization technology, characterized in that, Includes the following steps: (1) Disperse lithium saponite with a mass percentage concentration of 0.5% to 5.0% in water to form a colloidal suspension; (2) Add the chlorantraniliprole powder that has passed through a 200-mesh sieve to the suspension obtained in step (1), and stir at 4000~10000 rpm for 10~15 min to form a homogeneous suspension; wherein the mass percentage concentration of chlorantraniliprole in the final system is 15%~40%; (3) The suspension obtained in step (2) is subjected to high-pressure micro-jet homogenization at a pressure of 10~150 MPa to peel off the lithium saponite sheet aggregates and achieve nanoscale dispersion. (4) Add 0.1% to 2.0% by mass of natural polymer to the homogenized system in step (3), and encapsulate the mixture by stirring at 1000 to 3000 rpm for 1 to 4 hours to obtain the nano-suspension agent; the natural polymer is at least one of chitosan or its alkylated, hydroxylated or carboxylated derivatives.

2. The method according to claim 1, characterized in that: The lithium saponite-based chlorantraniliprole nano-suspension prepared by the method has an average particle size of less than 100 nm.

3. A lithium saponite-based chlorantraniliprole nano-suspension prepared by the method according to any one of claims 1-2.

4. The nano-suspending agent according to claim 3, characterized in that: The suspending agent showed no water separation, stratification, or sedimentation after being sealed and stored at 54°C for 14 days and at 1°C for 7 days.

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