A complex herbicide suspending agent and a preparation method thereof

Abstract

The application discloses a kind of complex herbicide suspending agent and preparation method thereof, and it relates to the technical field of pesticide production.The suspending agent includes pendimethalin, flumetralin and propachlor, and a compatible mother liquor is introduced to realize in-situ synchronous surface passivation treatment;By using the mother liquor of the complex of polyethylene glycol block polyether and modified lignin sulfonate in the same system, the particles of three raw drugs with large difference in melting point are synchronously adsorbed on the same interface material, the surface properties tend to be consistent, the Ostwald ripening of the low-melting-point component is effectively inhibited, and the heterogeneous nucleation on the surface of the high-melting-point component is inhibited, solving the physical stability problem of conventional suspending agent, such as easy delamination, creaming and crystallization. At the same time, the interface repulsion and secondary crystallization caused by mixing the components after modification in the prior art are avoided, and the preparation process is simplified. Field tests show that the suspending agent has excellent control effect on annual weeds and is safe to crops, and has good industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of pesticide production technology, specifically to a compound herbicide suspension and its preparation method. Background Technology

[0002] Aqueous suspensions of pendimethalin (melting point 54-58℃), propyzamide (melting point 202-204℃), and promethazine (melting point 118-120℃) exhibit a broad spectrum of herbicidal activity and significant synergistic effects. Relevant literature reports that the combined action of these three herbicides shows additive or synergistic effects against weeds such as barnyard grass, velvetleaf, and lambsquarters, with significant control efficacy against weeds within the year of application. Therefore, developing this ternary compound system into a suspension formulation is of significant value.

[0003] However, processing the three active ingredients together into a stable aqueous suspension presents a more severe challenge than conventional binary formulations.

[0004] The problems of crystal growth and Ostwald ripening faced by conventional suspending agents are presented in a coupled and amplified form in this ternary system. Dimethyl pendimethalin has a melting point of only 54-58℃, making it extremely prone to softening and agglomeration during grinding and heat storage, resulting in Ostwald ripening. Low-melting-point crystals undergo crystal transformation or molecular rearrangement with temperature fluctuations, leading to the continuous dissolution of small particles and the sustained growth of large particles, precipitating a large amount of coarse crystals, resulting in paste formation and a sharp drop in suspension rate.

[0005] Due to their high melting points and numerous active sites on their crystalline surfaces, propyzamide and atrazine, after grinding, readily induce heterogeneous nucleation of dimethyl pendimethalin dissolved molecules on their surfaces, forming a complex agglomeration structure where large particles regrow crystals. This process rapidly broadens the particle size distribution, exacerbates sedimentation differences, and ultimately leads to irreversible stratification, paste formation, and even solidification. Conventional single dispersant systems struggle to simultaneously inhibit both of these processes.

[0006] Currently, to address the crystal growth problem of low-melting-point pesticides, there are numerous reports on microencapsulation of single components. For example, microencapsulated suspensions of pendimethalin using polyurea or polyurethane as wall materials can effectively inhibit crystal growth. However, these methods only focus on isolating single components and do not consider the interfacial disturbances and heterogeneous nucleation problems caused by the vastly different surface properties of high-melting-point active ingredients when they coexist.

[0007] For surface passivation treatment of high-melting-point active pharmaceutical ingredients, pre-adsorption and blocking of active sites using polycarboxylate or phosphate ester auxiliaries represents another independent technical route. Combining microencapsulation of low-melting-point active pharmaceutical ingredients with surface passivation treatment of high-melting-point active pharmaceutical ingredients, modifying each component separately before mixing, is a potential approach.

[0008] However, this combined approach suffers from interfacial incompatibility issues in practical systems: the two modified materials employ different interfacial systems with significantly different surface properties, leading to interfacial repulsion between different particles after mixing, which weakens the modification effects and may even introduce new disordered regions, inducing secondary crystallization. Furthermore, this approach requires separate design of processing routes; microencapsulation necessitates interfacial polymerization equipment, and surface passivation requires pre-grinding and adsorption processes, resulting in complex processes with poor universality.

[0009] There is no existing technology that provides technical inspiration for using the same interface material in the same system to perform integrated and simultaneous surface treatment on three active ingredients with significantly different melting points, nor is there any report on the synergistic effect of interface chemical regulation and physical particle size structure design.

[0010] Therefore, there is an urgent need to develop a ternary suspension preparation strategy that can coordinate the interfacial behavior of the three active ingredients as a whole and regulate it uniformly from the source, so as to fundamentally solve the problem of physical stability of this ternary system, while simplifying the preparation process and lowering the threshold for industrialization.

[0011] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0012] To address the aforementioned technical problems, embodiments of the present invention provide a compound herbicide suspension and its preparation method, thereby resolving the issues raised in the background section.

[0013] A compound herbicide suspension comprises the following parts by weight of active ingredient and adjuvant: Active ingredients: Pendimethalin 23.4 parts, propyzamide 0.6 parts, and propyzamide 13 parts; Ambisexual stock solution: 3.0-5.0 parts; Dispersant: 1.0-3.0 parts; Wetting agent: 0.3-1.0 parts; Thickener: 0.2-0.6 parts; Antifreeze: 4.0-6.0 parts; Defoamer: 0.1-0.2 parts; Deionized water: Add to a total mass of 100 parts; The amphiphilic mother liquor comprises polyethylene glycol block polyether and modified lignin sulfonate in a mass ratio of 40-60:30-50; the solid content of the amphiphilic mother liquor is 70%-90%. Dimethoate, propyzamide, and propyzamide were subjected to in-situ synchronous surface passivation treatment in amphoteric mother liquor.

[0014] Preferably, the polyethylene glycol block polyether is an EO / PO block polyether with an HLB value of 12-15, a number-average molecular weight of 6000-8000, and an EO content of 40%-60%.

[0015] Preferably, the modified lignin sulfonate is a product of lignin sulfonate modified by oxidation, sulfonation and polycondensation reactions, with a weight-average molecular weight of 8000-15000 and a degree of sulfonation ≥0.8.

[0016] Preferably, the dispersant is sodium lignosulfonate; the wetting agent is alkyl naphthalene sulfonate; the thickener is a compound of xanthan gum and magnesium aluminum silicate, with a mass ratio of 1:2 to 1:3; the antifreeze is propylene glycol or ethylene glycol; and the defoamer is an organosilicon defoamer.

[0017] Preferably, the in-situ synchronous surface passivation treatment is achieved by adding dimethoate, propyzamide, and pyrazosulfuron into an amphoteric mother liquor and then subjecting it to high-speed shearing; the high-speed shearing speed is 2000-4000 r / min, and the shearing time is 15-30 min.

[0018] A method for preparing a compound herbicide suspension according to the above-described method includes the following steps: (1) Polyethylene glycol block polyether and modified lignin sulfonate were added to deionized water and stirred and dissolved at 40-50℃ to prepare an amphoteric mother liquor; (2) Add 23.4 parts of pendimethalin, 0.6 parts of propyzamide and 13 parts of pyrazosulfuron into the amphoteric mother liquor of step (1) and perform high-speed shear dispersion so that the amphoteric interface material is simultaneously adsorbed on the surface of the three active ingredients. (3) Grind the slurry obtained in step (2) to make the particle size of solid particles D90≤3μm; (4) Add 1.0-3.0 parts of dispersant, 0.3-1.0 parts of wetting agent, 0.2-0.6 parts of thickener, 4.0-6.0 parts of antifreeze, 0.1-0.2 parts of defoamer, and the remaining deionized water to make up to a total mass of 100 parts. Stir evenly to obtain the compound herbicide suspension product.

[0019] It should be noted that in steps (2) and (3), the slurry temperature is controlled to not exceed 30°C throughout the process. Specific measures include: setting up a jacketed cooling water circulation system on the high-speed shear dispersion and grinding equipment, or using an ice-water bath for cooling.

[0020] Preferably, the stirring speed in step (1) is 300-500 r / min and the stirring time is 30-60 min.

[0021] Preferably, in step (2), the high-speed shearing speed is 2000-4000 r / min and the shearing time is 15-30 min.

[0022] Preferably, in step (3), a horizontal sand mill is used for grinding, the grinding speed is 3000-5000 r / min, the grinding medium is zirconia beads, the grinding medium particle size is 0.4-0.6 mm, and the grinding is repeated 2-3 times.

[0023] The compound herbicide suspension and its preparation method provided in this invention have the following beneficial effects: (1) This invention significantly improves the physical stability of ternary compound suspensions. This invention uses an amphoteric mother liquor to perform in-situ synchronous surface passivation treatment on pendimethalin, propyzamide, and propargite, enabling the three active ingredients with vastly different melting points to simultaneously adsorb the same interface material within the same system, resulting in more uniform surface properties. Example data shows that this invention fundamentally inhibits the Ostwald ripening of low-melting-point pendimethalin and heterogeneous nucleation on the surface of high-melting-point active ingredients, achieving long-term uniform and stable dispersion of the three active ingredients.

[0024] (2) This invention effectively overcomes the interfacial incompatibility problem caused by discrete modification. In the prior art, the microencapsulation of low-melting-point active ingredients and the surface passivation of high-melting-point active ingredients are treated separately and then mixed. The surface properties of the two interfacial materials are significantly different, and interfacial repulsion occurs after mixing, weakening the modification effect and even inducing secondary crystallization. This invention uses the same amphiphilic mother liquor to complete the integrated surface treatment of the three active ingredients in the same system, avoiding the conflict between different interfacial materials, simplifying the processing route, eliminating the need for interfacial polymerization equipment required for microencapsulation, and achieving the process only through high-speed shearing and conventional grinding. The process is simple, universal, and suitable for industrial-scale production.

[0025] (3) This invention ensures that the herbicidal biological activity is not affected. Field efficacy trials show that the suspension prepared by the method of this invention has significantly better control efficacy against the total number of annual weeds and fresh weight of tiger pea fields than the control group, and is safe for crops without phytotoxicity. This indicates that the in-situ synchronous surface passivation treatment of this invention does not reduce the herbicidal activity of the active ingredients. On the contrary, due to the significant improvement in the dispersibility and physical stability of the suspension, the active ingredients are evenly and stably distributed in the solution, thereby promoting the full exertion of the efficacy and achieving a balance between stabilization and high efficiency. Attached Figure Description

[0026] Figure 1 This is a microscopic morphology diagram of sample D1 in Comparative Example 1. Figure 2 This is a microscopic morphology diagram of sample S1 from Example 1. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] To address the aforementioned technical problems, embodiments of the present invention provide a compound herbicide suspension and its preparation method, thereby resolving the issues raised in the background section.

[0029] I. Preparation of Experimental Materials 1. Active ingredient raw material Pendimethalin technical grade: purity ≥97%; Propylene flumetsulam technical grade: purity ≥98%; Atrazine technical grade: purity ≥ 97%.

[0030] 2. Amphoteric Mother Liquor Raw Material Polyethylene glycol block polyether: EO / PO block polyether, HLB value 12-15, number average molecular weight 6000-8000, EO content 40%-60%; The specific preparation method of modified lignin sulfonate is as follows: 1000 parts of lignin sulfonate raw powder are added to water to prepare a 40% solution, the pH is adjusted to 8.0-10.0 with sodium hydroxide, 30 parts of 30% hydrogen peroxide and 3 parts of ferrous sulfate are added, and the temperature is raised to 80-100℃ for oxidation reaction for 0.5-2 hours to introduce oxygen-containing functional groups.

[0031] After oxidation, the pH is adjusted to 9.0-11.0 with sodium hydroxide, and 50 parts of sodium sulfite are added. The mixture is then subjected to sulfonation methylation at 90-100℃ for 2-4 hours to increase sulfonic acid groups and improve water solubility and dispersibility. Subsequently, the pH is adjusted to 4.0-6.0 with dilute sulfuric acid, and 40 parts of formaldehyde are added. The mixture is then subjected to condensation polymerization at 90-100℃ for 1-3 hours to moderately crosslink through methylene bridges, increasing the molecular weight.

[0032] After the reaction is complete, the material is cooled and discharged, then spray-dried to obtain modified lignin sulfonate powder. The weight-average molecular weight of the product is controlled between 8000-15000, and the degree of sulfonation is ≥0.8. If the molecular weight or degree of sulfonation does not meet the standard, the polycondensation time can be extended or the amount of sulfonating agent can be increased, and adjustments can be made through routine experiments.

[0033] The weight-average molecular weight of the product was determined to be 9230 by gel permeation chromatography, and the degree of sulfonation was determined to be 0.89 by ion exchange-conductivity titration. Infrared spectroscopy was performed at 1045 cm⁻¹. -1 The presence of a characteristic absorption peak for sulfonic acid groups confirms successful modification.

[0034] 3. Other additives Dispersant: Sodium lignosulfonate; Wetting agent: alkyl naphthalene sulfonate; Thickeners: xanthan gum, magnesium aluminum silicate; Antifreeze: Propylene glycol; Defoamer: Polydimethylsiloxane emulsion; Deionized water: homemade in the laboratory.

[0035] II. Preparation of Amphoteric Stock Solution According to the proportions in Table 1, polyethylene glycol block polyether and modified lignin sulfonate were added to deionized water and stirred at 400 r / min for 45 min at 45℃ to dissolve and compound, thus preparing an amphoteric mother liquor.

[0036] Table 1. Mixing ratio of amphiphilic mother liquor

[0037] III. Example 1 3.1 Formulation Composition Active ingredients: Pendimethalin 23.4 parts, propyzamide 0.6 parts, and propyzamide 13 parts; Ambisexual stock solution: 4.0 parts; Dispersant: 2.0 parts; Wetting agent: 0.5 parts; Thickener (xanthan gum: magnesium aluminum silicate = 1:2): 0.3 parts; Antifreeze: 5.0 parts; Defoamer: 0.15 parts; Deionized water: Add to a total of 100 parts by weight.

[0038] 3.2 Preparation method (1) Preparation of amphoteric mother liquor: According to the ratio of Example 1 in Table 1, 50 parts of polyethylene glycol block polyether and 40 parts of modified lignin sulfonate were added to 10 parts of deionized water and stirred at 400 r / min for 45 min at 45°C to dissolve and compound, thus preparing amphoteric mother liquor.

[0039] (2) In-situ synchronous surface passivation treatment: 23.4 parts of pendimethalin, 0.6 parts of propyzamide and 13 parts of pyrazosulfuron are put into the amphoteric compatible mother liquor of step (1) and dispersed at high speed at 3000 r / min for 20 min. The temperature of the slurry is controlled not to exceed 30℃ by cooling water circulation in the jacket, so that the surface of the three active ingredients can be simultaneously adsorbed with amphoteric interface materials.

[0040] (3) Grinding: The in-situ synchronous surface passivation slurry obtained in step (2) was transferred into a horizontal sand mill and ground at a grinding speed of 4000 r / min, a grinding media (zirconia beads) particle size of 0.5 mm, and circulated grinding for 3 times. During the grinding process, the jacket cooling water was kept circulating, and the slurry temperature was controlled not to exceed 30℃, so that the solid particle size D90 ≤ 3 μm. The particle size was detected by a laser particle size analyzer (Mastersizer 3000), and the particle D90 after grinding was 2.8 μm.

[0041] (4) Subsequent formulation processing: Add 2.0 parts of dispersant, 0.5 parts of wetting agent, 0.3 parts of thickener, 5.0 parts of antifreeze, 0.15 parts of defoamer to the slurry obtained in step (3), and make up the remaining amount of deionized water to a total mass of 100 parts. Stir evenly to obtain the compound herbicide suspension product. Sample number S1.

[0042] IV. Example 2 4.1 Formulation Composition Active ingredients: Pendimethalin 23.4 parts, propyzamide 0.6 parts, and propyzamide 13 parts; Ambisexual stock solution: 5.0 parts; Dispersant: 1.0 part; Wetting agent: 1.0 part; Thickener (xanthan gum: magnesium aluminum silicate = 1:2): 0.6 parts; Antifreeze (propylene glycol): 4.0 parts; Defoamer (SAG 630): 0.20 parts; Deionized water: Add to a total of 100 parts by weight.

[0043] 4.2 Preparation method The amphoteric mother liquor (60 parts polyethylene glycol block polyether, 30 parts modified lignin sulfonate, and 10 parts deionized water) was prepared according to the proportions in Example 2 of Table 1. The remaining steps were the same as in Example 1, except that the high-speed shearing speed was adjusted to 2500 r / min and the time to 30 min, and the grinding cycle was repeated twice. The resulting sample was numbered S2.

[0044] V. Example 3 5.1 Formulation Composition Active ingredients: Pendimethalin 23.4 parts, propyzamide 0.6 parts, and propyzamide 13 parts; Ambisexual stock solution: 3.0 parts; Dispersant: 3.0 parts; Wetting agent: 0.3 parts; Thickener (xanthan gum: magnesium aluminum silicate = 1:2): 0.2 parts; 6.0 parts antifreeze; Defoamer: 0.10 parts; Deionized water: Add to a total of 100 parts by weight.

[0045] 5.2 Preparation method The amphoteric mother liquor (40 parts polyethylene glycol block polyether, 50 parts modified lignin sulfonate, and 10 parts deionized water) was prepared according to the proportions in Example 3 of Table 1, and the remaining steps were the same as in Example 1. The resulting sample was numbered S3.

[0046] VI. Comparative Example 1 6.1 Pretreatment of pendimethalin microencapsulation Take 23.4 parts of pendimethalin, add 2.5 parts of toluene diisocyanate and 1.5 parts of ethylenediamine, react at 60℃ for 3 hours, filter and dry to obtain microencapsulated pendimethalin powder.

[0047] 6.2 Surface passivation pretreatment of propyzamide and propyzamide Take 0.6 parts of propyzamide and 13 parts of pyrazosulfuron, add 0.5 parts of polycarboxylate dispersant and 20 parts of deionized water, and pre-grind in a sand mill for 30 minutes to allow the passivating agent to be adsorbed onto the particle surface.

[0048] 6.3 Mixing and Formulation Processing The microencapsulated pendimethalin powder was mixed with the passivated propyne fluroxypyr and promethazine slurries, and 1.5 parts dispersant, 0.5 parts wetting agent, 0.3 parts thickener, 5.0 parts antifreeze, 0.15 parts defoamer, and deionized water were added and stirred until homogeneous. The resulting sample was designated D1.

[0049] VII. Performance Testing 7.1 Test Method (1) Visual observation: Observe the state of the sample after storage at room temperature and after heat storage with the naked eye, including phenomena such as layering, precipitation, crystallization, and paste formation.

[0050] (2) Particle size determination: The particle size distribution of the sample was determined using a laser particle size analyzer (Mastersizer 3000), and the D90 value was recorded.

[0051] (3) Suspension rate determination: Refer to GB / T 14825-2006 Pesticide suspension rate determination method, dilute the sample with standard hard water, let it stand in a graduated cylinder for 30 minutes, determine the content of effective ingredients in the bottom tenth of the suspension, and calculate the suspension rate.

[0052] (4) Thermal storage stability: The sample was placed in a sealed container and stored in a constant temperature oven at 54℃ for 14 days. After being taken out and cooled to room temperature, the suspension rate and particle size changes were measured and the appearance was observed.

[0053] (5) Cyclic stability: The sample was stored in a 0℃ refrigerator for 24 hours, then transferred to a 54℃ oven for 24 hours. This cycle was repeated 3 times, and the sample status was observed.

[0054] (6) Microscopic morphology observation: Use an optical microscope (400x magnification) to observe the particle dispersion state after the sample is diluted, and take pictures to record.

[0055] 7.2 Test Results Table 2 Performance test results of each sample

[0056] 7.3 Microscopic Morphological Observation Take the comparative example 1 sample (D1, Figure 1 ), and the sample of Example 1 (S1, Figure 2 After being diluted with deionized water, the particle dispersion was observed under a 400x optical microscope, and photographs were taken and recorded.

[0057] Microscopic morphology description of the unmodified sample (D1): The particle size distribution in the field of view is extremely uneven, with a large number of coarse particles in addition to a small number of fine particles. The presence of large particles causes sedimentation during storage, affecting the uniformity of the active ingredient and the final efficacy. The particle morphology is mainly long rod-shaped or irregular polyhedral, but the edges are blurred, and fine particles adhere to the surface, indicating that the crystal structure was damaged during the crushing or dispersion process.

[0058] Microscopic morphology description of the improved sample (S1): Microscopic observation shows that the improved sample exhibits a well-dispersed microstructure with regular particle morphology. Numerous fine solid particles are visible suspended in the medium, with particle shapes primarily being elongated elliptical, rod-shaped, and irregular polyhedral. The vast majority of particles are small in size and relatively uniformly distributed. The particles are evenly distributed in the field of view, without obvious sedimentation or large-area aggregation, and the particles exhibit good independence, indicating good physical stability of the system. Some particles have clear edges and distinct outlines, showing the integrity of the crystal structure. This indicates that the present invention effectively suppresses particle flocculation and crystal growth through in-situ synchronous surface passivation treatment.

[0059] 7.4 Results Analysis The results in Table 2 show that: Examples 1-3 (S1-S3) employed the in-situ synchronous surface passivation treatment and amphoteric mother liquor of the present invention. After heat storage, the suspension rate exceeded 90%, with no visible crystallization or stratification, and the cyclic stability test also showed good results. This indicates that the present invention successfully achieved uniform and stable dispersion of the three components by synchronously treating the interfaces within the same system.

[0060] Comparative Example 1 (D1) involved encapsulating pendimethalin in microcapsules, passivating the surfaces of propyzamide and propargite, and then mixing the three together. The result was a suspension rate of only 71.3% after heat storage, with obvious stratification and crystal precipitation. This confirms the problem described in the background section: the materials used in the two treatment methods are incompatible, with significantly different surface properties. When mixed, they repel each other, not only failing to enhance the effect but also canceling each other out, and even inducing new crystallization.

[0061] The above results fully demonstrate that the present invention, through in-situ synchronous surface passivation treatment, simultaneously treats three active pharmaceutical ingredients in the same amphiphilic mother liquor, effectively avoiding the interface incompatibility problem caused by discrete modification, and significantly improving the physical stability and thermal storage stability of the suspension.

[0062] IX. Field efficacy verification The field efficacy trial method involved applying the product of Example 1 (S1) and Comparative Example 1 (D1) to tiger pea fields, with an additional Comparative Example 2 (D2). The application rate was 1800 g / hm². 2 Table 3 shows the control efficacy against annual weeds (mainly barnyard grass, velvetleaf, and lambsquarters) 40 days after application (based on total effective ingredient content).

[0063] Comparative Example 2 used a conventional suspension preparation process, without adding amphoteric mother liquor or performing in-situ synchronous surface passivation treatment, and served as a conventional control. Its formulation was the same as that of Example 2, except that the amphoteric mother liquor was removed, while the types and amounts of other additives remained the same, and it was made up to a total mass of 100 parts with deionized water.

[0064] Formula composition: Active ingredients: Pendimethalin 23.4 parts, propyzamide 0.6 parts, and propyzamide 13 parts; Dispersant (sodium lignosulfonate): 1.0 part; Wetting agent (alkyl naphthalene sulfonate): 1.0 part; Thickener (xanthan gum: magnesium aluminum silicate = 1:2): 0.6 parts; Antifreeze (propylene glycol): 4.0 parts; Defoamer (polydimethylsiloxane emulsion): 0.20 parts; Deionized water: Add to a total of 100 parts by weight.

[0065] Preparation method: (1) Mix 23.4 parts of pendimethalin, 0.6 parts of propyzamide, 13 parts of pyrazosulfuron-methyl and 30 parts of deionized water, add 1.0 part of dispersant and 1.0 part of wetting agent, and stir into a uniform slurry; (2) Transfer the slurry obtained in step (1) into a horizontal sand mill and grind it at a grinding speed of 4000 r / min, a grinding media (zirconia beads) particle size of 0.5 mm, and circulate grinding 3 times to make the solid particle size D90≤3μm; (3) Add 0.6 parts thickener, 4.0 parts antifreeze, 0.20 parts defoamer to the ground slurry, and make up the remaining deionized water to a total mass of 100 parts. Stir evenly to obtain the compound herbicide suspension. The obtained sample is numbered D2 (conventional control).

[0066] Table 3 Comparison of field control efficacy

[0067] As shown in Table 3, the modified suspension concentrate product (S1) of this invention is superior to the control (D1) and the conventional suspension concentrate control (D2) in weed control efficacy, and also exhibits good crop safety. Better dispersibility and suspension rate promote the full realization of efficacy, while conventional suspension concentrates have the lowest efficacy due to poor physical stability and uneven distribution of active ingredients.

[0068] It should be noted that the design of the amphoteric mother liquor as a unified interface treatment medium is based on the following key ideas: First, polyethylene glycol block polyether was selected. This polyether has an amphiphilic structure composed of ethylene oxide and propylene oxide segments, and its hydrophilic and lipophilic properties can be optimized by adjusting the ratio of the two blocks. The hydrophobic segments of the polyether can effectively anchor to the surface of strongly hydrophobic active ingredients such as pendimethalin through hydrophobic interactions, while also exhibiting moderate adsorption strength on the surface of moderately polar active ingredients such as atrazine and propyzamide. After adsorption, the polyether molecules extend into the aqueous phase, forming a steric hindrance layer, thereby inhibiting close-range contact between particles and providing steric stabilization.

[0069] Second, modified lignin sulfonate was also selected. This dispersant underwent three consecutive modifications—oxidation, sulfonation, and polycondensation—to obtain a molecular structure with high charge density and suitable molecular size. Its negative charge enhances the dispersion stability between particles through electrostatic repulsion, preventing aggregation caused by double-layer compression or overlap. Furthermore, the inherent phenolic hydroxyl and carboxyl functional groups in the lignin molecule can form hydrogen bonds or coordinate adsorption with the surface of high-melting-point active ingredients, significantly improving the bonding strength and coverage density of lignin at the particle interface.

[0070] Third, the two media mentioned above are compounded. The polyether component dominates steric stabilization, while the lignin sulfonate component dominates electrostatic repulsion stabilization. Both exhibit synergistic adsorption behavior at the interface of the active pharmaceutical ingredient particles: on the one hand, they complement each other's insufficient adsorption on specific active pharmaceutical ingredient surfaces; on the other hand, they jointly construct a high-strength steric and electrostatic composite barrier. This synergistic effect allows the composite mother liquor to be compatible with different active pharmaceutical ingredient particles with significantly different surface chemical properties, achieving effective dispersion and stabilization of multi-component particles using a unified interface treatment medium.

[0071] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications to the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the invention. All variations and improvements should fall within the protection scope defined by the claims of this invention.

Claims

1. A compound herbicide suspension, characterized in that, Includes the following parts by weight of active ingredients and excipients: Active ingredients: Pendimethalin 23.4 parts, propyzamide 0.6 parts, and propyzamide 13 parts; Ambisexual stock solution: 3.0-5.0 parts; Dispersant: 1.0-3.0 parts; Wetting agent: 0.3-1.0 parts; Thickener: 0.2-0.6 parts; Antifreeze: 4.0-6.0 parts; Defoamer: 0.1-0.2 parts; Deionized water: Add to a total mass of 100 parts; The amphiphilic mother liquor comprises polyethylene glycol block polyether and modified lignin sulfonate in a mass ratio of 40-60:30-50; the solid content of the amphiphilic mother liquor is 70%-90%. Dimethoate, propyzamide, and propyzamide were subjected to in-situ synchronous surface passivation treatment in amphoteric mother liquor.

2. The compound herbicide suspension according to claim 1, characterized in that, The polyethylene glycol block polyether is an EO / PO block polyether with an HLB value of 12-15, a number-average molecular weight of 6000-8000, and an EO content of 40%-60%.

3. The compound herbicide suspension according to claim 1, characterized in that, The modified lignin sulfonate is a product of lignin sulfonate modified by oxidation, sulfonation and polycondensation reactions, with a weight-average molecular weight of 8000-15000 and a degree of sulfonation ≥0.

8.

4. The compound herbicide suspension according to claim 1, characterized in that, The dispersant is sodium lignosulfonate; the wetting agent is alkyl naphthalene sulfonate; the thickener is a compound of xanthan gum and magnesium aluminum silicate, with a mass ratio of 1:2 to 1:3; the antifreeze is propylene glycol or ethylene glycol; and the defoamer is an organosilicon defoamer.

5. The compound herbicide suspension according to claim 1, characterized in that, The in-situ synchronous surface passivation treatment is achieved by adding dimethoate, propyzamide, and pyrazosulfuron into an amphoteric mother liquor and then subjecting it to high-speed shearing; the high-speed shearing speed is 2000-4000 r / min, and the shearing time is 15-30 min.

6. A method for preparing a compound herbicide suspension according to any one of claims 1-5, characterized in that, Includes the following steps: (1) Polyethylene glycol block polyether and modified lignin sulfonate were added to deionized water and stirred and dissolved at 40-50℃ to prepare an amphoteric mother liquor; (2) Add 23.4 parts of pendimethalin, 0.6 parts of propyzamide and 13 parts of pyrazosulfuron into the amphoteric mother liquor of step (1) and perform high-speed shear dispersion so that the amphoteric interface material is simultaneously adsorbed on the surface of the three active ingredients. (3) Grind the slurry obtained in step (2) to make the particle size of solid particles D90≤3μm; (4) Add 1.0-3.0 parts of dispersant, 0.3-1.0 parts of wetting agent, 0.2-0.6 parts of thickener, 4.0-6.0 parts of antifreeze, 0.1-0.2 parts of defoamer, and the remaining deionized water to make up to a total mass of 100 parts. Stir evenly to obtain the compound herbicide suspension product.

7. The method for preparing the compound herbicide suspension according to claim 6, characterized in that, In step (1), the stirring speed is 300-500 r / min and the stirring time is 30-60 min.

8. The method for preparing the compound herbicide suspension according to claim 6, characterized in that, In step (2), the high-speed shearing speed is 2000-4000 r / min, and the shearing time is 15-30 min.

9. The method for preparing the compound herbicide suspension according to claim 6, characterized in that, In step (3), a horizontal sand mill is used for grinding. The grinding speed is 3000-5000 r / min, the grinding medium is zirconia beads, the grinding medium particle size is 0.4-0.6 mm, and the grinding is repeated 2-3 times.

Images