Method for improving uniformity of carbendazim suspending agent

Abstract

The invention relates to the technical field of pesticide preparations, in particular to a method for improving uniformity of a carbendazim suspending agent. The method comprises the following steps: mixing a carbendazim active compound, a modified dispersant, a wetting agent and part of deionized water, and carrying out shearing pre-dispersion and sanding grinding to prepare superfine slurry; adding the antifreeze agent, the thickening agent and the defoaming agent, uniformly stirring, adding the balance of water to adjust the solid content and the pH value, filtering out impurities, and intermittently stirring and curing to obtain a final suspending agent product. The modified dispersant is prepared by esterifying allyl polyoxyethylene ether and succinic anhydride, then copolymerizing with 2-ethylhexyl acrylate and acrylamide, grafting chitosan quaternary ammonium salt and inclusion cyclodextrin, and the steric hindrance and anchoring stability are remarkably enhanced; the thickening agent is a compound system of xanthan gum and magnesium aluminum silicate. According to the method, the uniformity and redispersibility of the preparation are effectively improved, Ostwald ripening and crystal growth are inhibited, and the physical stability and efficacy consistency of the product in the long-term storage and use process are guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of pesticide formulations, more particularly, it relates to a method for improving the uniformity of carbendazim suspension concentrate. BACKGROUND

[0002] Carbendazim, as a broad-spectrum systemic benzimidazole fungicide, is widely used in the prevention and control of various crop diseases in agricultural production. It is used to prevent and control various fungal diseases through foliar spraying, seed and soil treatment, etc. in agricultural production. Its efficacy relies on the uniform distribution and physical stability of the active ingredient in the formulation. As an important part of pesticide formulations, suspension concentrate has become the focus of modern pesticide formulation research and development due to its environmental protection, high efficiency, and convenience of use. The physical stability and uniformity of carbendazim suspension concentrate are directly related to its storage period, use effect and safety, and are key indicators for measuring the quality of the formulation.

[0003] However, during actual production and storage, carbendazim suspension concentrate still faces many technical challenges. Due to the high particle density and strong hydrophobicity of the raw material, it is prone to sedimentation, caking, austenitic ripening and phase separation, etc., which leads to a decrease in the uniformity of the formulation, seriously affecting its redispersibility and bioavailability. Conventional dispersants and stabilizing systems often fail to maintain the suspended state of the particles for a long time, resulting in large differences in stability between batches, shortening of the shelf life, and restricting its large-scale application. At present, the technical means to improve the stability of suspension concentrate mainly focus on optimizing the grinding process or compounding traditional surfactants, but the in-depth research on particle surface modification and space stabilization mechanism is still insufficient. The adsorption capacity of existing dispersants is limited, and it is easy to desorb under long-term static or temperature change conditions, which is difficult to effectively inhibit crystal growth and particle aggregation. Therefore, developing a new type of dispersion and stabilization system that can strengthen the anchoring effect and provide persistent steric hindrance, and matching the corresponding formulation processing technology, has become the key direction to improve the performance of carbendazim suspension concentrate. SUMMARY

[0004] In order to solve the above problems, the present application provides a method for improving the uniformity of carbendazim suspension concentrate, which effectively improves the uniformity and redispersibility of the formulation, inhibits austenitic ripening and crystal growth, and ensures the physical stability and efficacy consistency of the product during long-term storage and use.

[0005] To achieve the above purpose, the present application provides the following technical solutions:

[0006] A method for improving the uniformity of carbendazim suspension concentrate, comprising the following steps:

[0007] (1)Carbendazim, modified dispersant, wetting agent are added into deionized water, and stirred at 800-1000 rpm for 15-30 min at 23-27℃ to form a premix, then transferred to a sand mill, and zirconium oxide beads are added as grinding medium, the grinding temperature is controlled at 25-35℃, and the grinding is continued at a speed of 2800-3200 rpm for 2-4 h until the particle size reaches D90 of no more than 3.5 μm;

[0008] (2) The slurry obtained in step (1) is transferred to a stirred tank, and antifreeze, thickening agent and defoaming agent are added in sequence, and stirred at 1200-1500 rpm for 10-20 min at 20-30℃ to make the auxiliaries uniformly dispersed;

[0009] (3) The remaining deionized water is added to the mixture obtained in step (2) to adjust the solid content to 40-50%, and then the pH value is adjusted to 6.6-7.5, and stirred at 800-1000 rpm for 5-10 min at 30-40℃, and then filtered through a 100-200 mesh filter cloth to remove mechanical impurities, and the filtrate is transferred to an aging tank and aged at 25-30℃ for 13-17 h, during which it is stirred at 200-300 rpm for 5 min every 4 h, and then the carbendazim suspension is obtained.

[0010] Preferably, the preparation step of the modified dispersant in step (1) is:

[0011] S1, succinic anhydride is dissolved in N,N-dimethylformamide, and allyl polyoxyethylene ether is added at a rate of 1-4 ml / min at 45-55℃ and 300-400 rpm, then p-toluenesulfonic acid is added, the temperature is raised to 65-75℃ and kept constant, and the reaction is carried out for 3-3.5 h, then the reaction solution is poured into an ice water mixture, stirred at 200-300 rpm to precipitate a white precipitate, and the filter cake is washed with cold water until the filtrate is neutral, and the wet product is vacuum dried at 50-60℃ for 5-8 h to obtain intermediate I;

[0012] S2, intermediate I, isooctyl acrylate and acrylamide are dissolved in a mixed solvent composed of deionized water and isopropyl alcohol, and the temperature is raised to 62-68℃ under nitrogen protection and stirring at 400-500 rpm, and potassium persulfate is dissolved in deionized water, and added to the reaction system at a uniform rate within 30-40 min, and then the reaction is carried out at 62-68℃ for 4-6 h after cooling to room temperature, and then precipitated, filtered, washed and vacuum dried to obtain a dispersant prepolymer;

[0013] S3, the dispersant prepolymer is weighed and dispersed in deionized water, stirred at 500-600 rpm and heated to 40-45 DEG C, dissolved for 30-40 min, the chitosan quaternary ammonium salt is added, heated to 52-58 DEG C, stirred at 300-350 rpm for 35-45 min, then the hydroxypropyl-beta-cyclodextrin is added, stirred at 52-58 DEG C for 3-5 h, then the reaction solution is transferred to a tray for freeze drying, and the modified dispersant with a particle size D90 of less than 10 microns is obtained after crushing.

[0014] Preferably, in step (1), 23-27 parts by weight of the carbendazim technical material, 7-9 parts by weight of the modified dispersant, 2-4 parts by weight of the wetting agent and 30-40 parts by weight of deionized water are used.

[0015] Preferably, in step (2), 4-6 parts by weight of the antifreeze agent, 0.1-0.3 parts by weight of the thickening agent and 0.3-0.6 parts by weight of the defoaming agent are used.

[0016] Preferably, in step S1, 10-15 parts by weight of succinic anhydride, 30-40 parts by weight of N,N-dimethylformamide, 30-40 parts by weight of allyl polyoxyethylene ether, 0.2-0.4 parts by weight of p-toluenesulfonic acid and 95-100 parts by weight of ice water mixture are used.

[0017] Preferably, in step S2, 18-22 parts by weight of the intermediate I, 6-9 parts by weight of isooctyl acrylate, 4-7 parts by weight of acrylamide, 45-58 parts by weight of deionized water, 15-20 parts by weight of isopropyl alcohol and 0.4-0.7 parts by weight of potassium persulfate are used.

[0018] Preferably, in step S3, 22-26 parts by weight of the dispersant prepolymer, 80-100 parts by weight of deionized water, 3-6 parts by weight of the chitosan quaternary ammonium salt and 2-6 parts by weight of the hydroxypropyl-beta-cyclodextrin are used.

[0019] Preferably, in step (1), the wetting agent is at least one of isodecyl alcohol polyoxyethylene ether, sodium dodecylbenzenesulfonate and Span 20.

[0020] Preferably, in step (2), the thickening agent is composed of xanthan gum and magnesium aluminum silicate in a mass ratio of (1-3):1.

[0021] Preferably, in step (2), the antifreeze agent is at least one of ethylene glycol, glycerol and propylene glycol, and the defoaming agent is an organic silicon additive.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] 1.The carbendazim suspension concentrate is prepared by premixing of carbendazim raw material with modified dispersant and wetting agent, ultrafine grinding, subsequent compounding of anti-freezing agent, thickening agent and defoaming agent, and final maturation process with precise control. The method, through precise design of each process step and synergistic effect of the additive system, not only significantly improves the initial dispersity and suspension stability of the preparation, but more importantly, greatly improves the long-term physical stability of the product, effectively overcomes the industry common problems such as particle sedimentation, Ostwald ripening and crystal growth during storage, and ensures the consistency of the performance and the reliability of the application of the product during the entire shelf life.

[0024] 2.The modified dispersant is prepared by esterification of allyl polyoxyethylene ether, copolymerization with acrylic ester monomer, and grafting modification of chitosan quaternary ammonium salt and cyclodextrin. The dispersant molecule, through careful structural design, simultaneously realizes multiple functions of steric hindrance, anchoring enhancement, electrical effect and crystal inhibition. The hydrophobic segment can strongly embed into the surface of carbendazim particles, providing persistent anchoring; the polyether long chain is fully hydrated to form a three-dimensional barrier, effectively preventing particle aggregation; the quaternary ammonium salt group enhances the adsorption strength and coverage of the particles through the cationic property; and the chemically bonded cyclodextrin precisely inhibits the dissolution-recrystallization process of the drug molecules through the inclusion effect, fundamentally delaying the Ostwald ripening. The synergistic effect of such multifunctional groups solves the technical bottleneck of the single function of traditional dispersants in complex environments and the easy desorption failure, thereby providing long-term stability protection for the suspension concentrate. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0026] In the following examples, the experimental methods are conventional methods unless otherwise specified, and the test materials used are commercially available from conventional biochemical reagent stores unless otherwise specified. In the quantitative tests in the following examples, three repeated experiments are set, and the data are the average value or average value ± standard deviation of the three repeated experiments.

[0027] Allyl polyoxyethylene ether, purchased from Hubei Rishengchang New Material Technology Co., Ltd., CAS No. 67874-71-9;

[0028] Hydroxypropyl-β-cyclodextrin, purchased from Shanghai Yuanye Biological Technology Co., Ltd., product No. S11012;

[0029] Isodecanol polyoxyethylene ether, purchased from Sichuan Poly West East New Material Co., Ltd., CAS No. 61827-42-7;

[0030] Span 20, Shanghai Yuan Ye Biotechnology Co., Ltd., Catalog No. S15049;

[0031] Xanthan gum, purchased from Jiangsu Yuanzhiyuan Biotechnology Co., Ltd., CAS No. 11138-66-2;

[0032] Silicone adjuvant, purchased from Shanghai Xiaoya Biotechnology Co., Ltd., Catalog No. XY15031.

[0033] Example 1

[0034] The present embodiment provides a method for improving the uniformity of carbendazim suspension concentrate, comprising the following steps:

[0035] (1) 23 parts of carbendazim technical material, 7 parts of modified dispersant, and 2 parts of isodecanol polyoxyethylene ether were added into 30 parts of deionized water, stirred at 800 rpm at 23°C for 30 min to form a premix, and then the premix was transferred to a sand mill, zirconium oxide beads were added as grinding medium, the grinding temperature was controlled at 25°C, and the grinding was continued at a speed of 2800 rpm for 4 h until the particle size D90 was 3.4 μm;

[0036] (2) The slurry obtained in step (1) was transferred to a stirred tank, 4 parts of ethylene glycol, 0.1 parts of thickening agent composed of xanthan gum and magnesium aluminum silicate in a mass ratio of 1:1, and 0.3 parts of silicone defoamer were added in turn, and stirred at 1200 rpm at 20°C for 20 min to make the adjuvants uniformly dispersed;

[0037] (3) The remaining deionized water was added to the mixed system obtained in step (2) to adjust the solid content to 40%, citric acid was used to adjust the pH value to 6.6, and after stirring at 800 rpm at 30°C for 10 min, the mechanical impurities were removed by filtering through a 100 mesh filter cloth, and the filtrate was transferred to an aging tank, and aged at 25°C for 17 h, during which it was stirred at 200 rpm for 5 min every 4 h, and after aging, carbendazim suspension concentrate was obtained.

[0038] The preparation steps of the modified dispersant are as follows:

[0039] S1, 10 parts of succinic anhydride were dissolved in 30 parts of N,N-dimethylformamide, 30 parts of allyl polyoxyethylene ether were added dropwise at 1 ml / min under the condition of 45°C and 300 rpm stirring, 0.2 parts of p-toluenesulfonic acid were added after the dropwise addition was completed, the temperature was raised to 65°C and kept constant for 3.5 h, after the reaction was completed, the reaction liquid was poured into a mixture of 95 parts of ice water, stirred at 200 rpm to precipitate white precipitate, the filter cake was washed with cold water until the filtrate was neutral, and the wet product was vacuum dried at 50°C for 8 h to obtain intermediate I;

[0040] S2, 18 parts of intermediate I, 6 parts of isooctyl acrylate, 4 parts of acrylamide were dissolved in a mixed solvent composed of 45 parts of deionized water and 15 parts of isopropyl alcohol, and the temperature was raised to 62°C under nitrogen protection and 400 rpm stirring. 0.4 parts of potassium persulfate was dissolved in 5 parts of deionized water, and was added to the reaction system at a constant speed within 30 min. After dropping, it was kept at 62°C for 6 h. After the reaction was completed, it was cooled to room temperature, precipitated by ethanol, suction filtered, washed, and vacuum dried at 60°C for 12 h to obtain a dispersant prepolymer;

[0041] S3, 22 parts of the dispersant prepolymer was dispersed in 80 parts of deionized water, stirred at 500 rpm and heated to 40°C. After 40 min of dissolution, 3 parts of chitosan quaternary ammonium salt was added, heated to 52°C, stirred at 300 rpm for 45 min, and then 2 parts of hydroxypropyl-β-cyclodextrin was added. Stirring was carried out at 52°C for 5 h. Then the reaction liquid was transferred to a tray for freeze-drying, and the modified dispersant with a particle size D90 of 9.8 μm was obtained after crushing.

[0042] Example 2

[0043] The present embodiment provides a method for improving the uniformity of carbendazim suspension concentrate, comprising the following steps:

[0044] (1) 25 parts of carbendazim, 8 parts of modified dispersant, and 3 parts of sodium dodecyl benzene sulfonate were added to 35 parts of deionized water, and stirred at 900 rpm at 25°C for 22 min to form a premix. Then the premix was transferred to a sand mill, zirconium oxide beads were added as grinding medium, the grinding temperature was controlled at 30°C, and the grinding was continued at a speed of 3000 rpm for 3 h until the particle size D90 was 3.2 μm;

[0045] (2) The slurry obtained in step (1) was transferred to a stirred tank, 5 parts of glycerol, 0.2 parts of thickening agent composed of xanthan gum and magnesium aluminum silicate with a mass ratio of 2:1, and 0.45 parts of silicone defoamer were added in sequence, and stirred at 1350 rpm at 25°C for 15 min to uniformly disperse the additives;

[0046] (3) The remaining deionized water was added to the mixed system obtained in step (2) to adjust the solid content to 45%, and sodium acetate was used to adjust the pH value to 7.0. After stirring at 900 rpm at 35°C for 7 min, the mechanical impurities were removed by filtering through a 150 mesh filter cloth, and the filtrate was transferred to an aging tank and aged at 27°C for 15 h. During the aging process, the slurry was stirred at 250 rpm for 5 min every 4 h. After the aging was completed, the carbendazim suspension concentrate was obtained.

[0047] The preparation steps of the modified dispersant are as follows:

[0048] S1, 12 parts of succinic anhydride was dissolved in 35 parts of N, N- dimethylformamide, 35 parts of allyl polyoxyethylene ether was added dropwise at 2.5 ml / min under the condition of 50℃ and 350 rpm stirring, after the dropwise addition was completed, 0.3 parts of p-toluenesulfonic acid was added, the temperature was raised to 70℃ and kept constant for 3.2 h, after the reaction was completed, the reaction liquid was poured into 97 parts of ice water mixture, white precipitate was separated by stirring at 250 rpm, the filter cake was washed with cold water until the filtrate was neutral, and the wet product was dried at 55℃ under vacuum for 6.5 h to obtain intermediate I;

[0049] S2, 20 parts of intermediate I, 7.5 parts of isooctyl acrylate, and 5.5 parts of acrylamide were dissolved in a mixed solvent composed of 52 parts of deionized water and 17 parts of isopropanol, under the protection of nitrogen and 450 rpm stirring, the temperature was raised to 65℃, 0.55 parts of potassium persulfate was dissolved in 8 parts of deionized water, and was added uniformly to the reaction system within 35 min, after the dropwise addition was completed, the temperature was kept at 65℃ for 5 h, after the reaction was completed, the temperature was cooled to room temperature, and the product was precipitated by ethanol, filtered, washed, and dried at 62℃ under vacuum for 10 h to obtain a dispersant prepolymer;

[0050] S3, 24 parts of the dispersant prepolymer was dispersed in 90 parts of deionized water, stirred at 550 rpm and heated to 42℃, dissolved for 35 min, 4.5 parts of chitosan quaternary ammonium salt was added, heated to 55℃, stirred at 325 rpm for 40 min, then 3 parts of hydroxypropyl-β-cyclodextrin was added, and stirred at 55℃ for 4 h, then the reaction liquid was transferred to a tray for freeze-drying, and the modified dispersant with a particle size D90 of 8.5 μm was obtained after crushing.

[0051] Example 3

[0052] The present embodiment provides a method for improving the uniformity of carbendazim suspension agent, comprising the following steps:

[0053] (1) 27 parts of carbendazim, 9 parts of modified dispersant, and 4 parts of Span 20 were added to 40 parts of deionized water, stirred at 1000 rpm at 27℃ for 15 min to form a premix, then the premix was transferred to a sand mill, zirconium oxide beads were added as grinding medium, the grinding temperature was controlled at 35℃, and the grinding was continued at a speed of 3200 rpm for 2 h, until the particle size D90 was 2.9 μm;

[0054] (2) The slurry obtained in step (1) was transferred to a stirred tank, 6 parts of propylene glycol, 0.3 parts of thickening agent composed of xanthan gum and magnesium aluminum silicate with a mass ratio of 3:1, and 0.6 parts of silicone defoaming agent were added, and stirred at 1500 rpm at 30℃ for 10 min to uniformly disperse the additives;

[0055] (3) adding the rest of deionized water to the mixed system obtained in step (2) to adjust the solid content to 50%, adjusting the pH value to 7.5 with potassium dihydrogen phosphate, stirring at 1000 rpm for 5 min at 40℃, removing mechanical impurities by filtering through a 200-mesh filter cloth, and transferring the filtrate to an aging tank to stand and mature at 30℃ for 13 h, during which the solution is stirred at 300 rpm for 5 min every 4 h, to obtain carbendazim suspension concentrate.

[0056] The preparation steps of the modified dispersant are as follows:

[0057] S1, 15 parts of succinic anhydride were dissolved in 40 parts of N,N-dimethylformamide, 40 parts of allyl polyoxyethylene ether was added dropwise at 4 ml / min under the condition of stirring at 55℃ and 400 rpm, 0.4 parts of p-toluenesulfonic acid was added after the dropwise addition was completed, the temperature was raised to 75℃ and kept constant for 3 h, after the reaction was completed, the reaction solution was poured into a mixture of 100 parts of ice water, and white precipitate was separated by stirring at 300 rpm, the filter cake was washed with cold water until the filtrate was neutral, and the wet product was dried at 60℃ under vacuum for 5 h to obtain intermediate I;

[0058] S2, 22 parts of intermediate I, 9 parts of isooctyl acrylate, and 7 parts of acrylamide were dissolved in a mixed solvent composed of 58 parts of deionized water and 20 parts of isopropanol, and the temperature was raised to 68℃ under nitrogen protection and stirring at 500 rpm, 0.7 parts of potassium persulfate was dissolved in 10 parts of deionized water, and was added dropwise to the reaction system at a uniform speed within 40 min, after the dropwise addition was completed, the reaction was kept at 68℃ for 4 h, after the reaction was completed, the temperature was cooled to room temperature, and the product was precipitated by ethanol, filtered, washed, and dried at 65℃ under vacuum for 8 h to obtain a dispersant prepolymer;

[0059] S3, 26 parts of the dispersant prepolymer was weighed and dispersed in 100 parts of deionized water, stirred at 600 rpm and heated to 45℃, dissolved for 30 min, 6 parts of chitosan quaternary ammonium salt was added, heated to 58℃, stirred at 350 rpm for 35 min, then 6 parts of hydroxypropyl-β-cyclodextrin was added, and the reaction was kept at 58℃ for 3 h, then the reaction solution was transferred to a tray for freeze-drying, and the modified dispersant with a particle size D90 of 7.2 μm was obtained after crushing.

[0060] Example 4

[0061] The present embodiment provides a method for improving the uniformity of carbendazim suspension concentrate, comprising the following steps:

[0062] (1) 26 parts of carbendazim technical material, 8.5 parts of modified dispersing agent, 3.5 parts of isodecanol polyoxyethylene ether and sodium dodecyl benzene sulfonate complex wetting agent were added into 38 parts of deionized water, and stirred at 950 rpm for 18 min at 26°C to form a premix, then the premix was transferred to a sand mill, zirconium oxide beads were added as grinding medium, the grinding temperature was controlled at 32°C, and the grinding was continued at a speed of 3100 rpm for 2.5 h until the particle size D90 was 2.5 μm;

[0063] (2) The slurry obtained in step (1) was transferred to a stirred tank, 5.5 parts of glycerol, 0.25 parts of thickening agent composed of xanthan gum and magnesium aluminum silicate in a mass ratio of 2.5:1, and 0.5 parts of silicone defoamer were added in sequence, and stirred at 1450 rpm for 12 min at 28°C to make the auxiliaries uniformly dispersed;

[0064] (3) The remaining deionized water was added to the mixed system obtained in step (2) to adjust the solid content to 48%, and succinic acid was used to adjust the pH value to 7.2, and stirred at 950 rpm for 6 min at 38°C, then filtered through a 180 mesh filter cloth to remove mechanical impurities, and the filtrate was transferred to an aging tank, and aged at 28°C for 14 h, during which it was stirred at 280 rpm for 5 min every 4 h, and then high-performance carbendazim suspension concentrate was obtained after aging.

[0065] The preparation steps of the modified dispersing agent are as follows:

[0066] S1, 14 parts of succinic anhydride were dissolved in 38 parts of N,N-dimethylformamide, and 38 parts of allyl polyoxyethylene ether was added dropwise at a rate of 3 ml / min under stirring at 52°C and 380 rpm, then 0.35 parts of p-toluenesulfonic acid was added, the temperature was raised to 72°C and kept constant for 3.3 h, then the reaction liquid was poured into a mixture of 98 parts of ice water, and stirred at 280 rpm to precipitate white solid, which was filtered and washed with cold water until the filtrate was neutral, and then the wet product was vacuum dried at 58°C for 6 h to obtain intermediate I;

[0067] S2, 21 parts of intermediate I, 8 parts of isooctyl acrylate and 6 parts of acrylamide were dissolved in a mixed solvent composed of 55 parts of deionized water and 18 parts of isopropyl alcohol, and the temperature was raised to 66°C under nitrogen protection and stirring at 480 rpm, then 0.65 parts of potassium persulfate was dissolved in 9 parts of deionized water, and added dropwise into the reaction system at a uniform rate within 38 min, then the reaction was kept at 66°C for 4.5 h after dropping, and then cooled to room temperature, precipitated with ethanol, filtered, washed and vacuum dried at 63°C for 9 h to obtain a dispersing agent prepolymer;

[0068] S3, 25 parts of the dispersant prepolymer was weighed into 95 parts of deionized water, stirred at 580 rpm and heated to 44℃, dissolved for 32 min, 5 parts of chitosan quaternary ammonium salt was added, heated to 56℃, stirred at 340 rpm for 38 min, then 5 parts of hydroxypropyl-β-cyclodextrin was added, stirred at 56℃ for 3.5 h, then the reaction solution was transferred to a tray for freeze-drying, and after crushing treatment, a modified dispersant with a particle size D90 of 5 μm was obtained.

[0069] Comparative Example 1

[0070] A method for improving the uniformity of carbendazim suspension concentrate, which is different from Example 4 in that the modified dispersant is omitted and replaced with an equal amount of conventional dispersant. Specifically, in step (1), 26 parts of carbendazim technical material, 8.5 parts of naphthalenesulfonic acid sodium formaldehyde condensate, and 3.5 parts of compound wetting agent were added to 38 parts of deionized water, and the pre-dispersion and sanding process parameters were completely consistent with Example 4.

[0071] Comparative Example 2

[0072] A method for improving the uniformity of carbendazim suspension concentrate, which is different from Example 4 in that the dispersant only undergoes S1 step synthesis. Specifically, in the preparation of the modified dispersant, only the S1 esterification reaction step is retained, and the S2 copolymerization and S3 graft modification procedures are omitted, and the intermediate I obtained in S1 is directly used as the dispersant, and the suspension concentrate preparation process is completely the same as Example 4.

[0073] Comparative Example 3

[0074] A method for improving the uniformity of carbendazim suspension concentrate, which is different from Example 4 in that the S2 copolymerization step is omitted in the preparation of the dispersant. Specifically, in the preparation of the modified dispersant, after performing S1 esterification, the copolymerization step with isooctyl acrylate and acrylamide in S2 is skipped, and intermediate I is directly subjected to S3 chitosan quaternary ammonium salt grafting and cyclodextrin inclusion, and the suspension concentrate preparation process is completely the same as Example 4.

[0075] Comparative Example 4

[0076] A method for improving the uniformity of carbendazim suspension concentrate, which is different from Example 4 in that the S3 grafting step is omitted in the preparation of the dispersant. Specifically, in the preparation of the modified dispersant, after performing S1 esterification and S2 copolymerization, the S3 chitosan quaternary ammonium salt grafting and cyclodextrin inclusion procedure is skipped, and the dispersant prepolymer obtained in S2 is directly used as the dispersant, and the suspension concentrate preparation process is completely the same as Example 4.

[0077] Comparative Example 5

[0078] A method for improving the uniformity of carbendazim suspension concentrate, which is different from example 4 in that the chitosan quaternary ammonium salt in the S3 step of the dispersant preparation is omitted, and the hydroxypropyl-β-cyclodextrin is replaced with an equal amount of ordinary β-cyclodextrin. Specifically: in the S3 step, 25 parts of the dispersant prepolymer is weighed and dispersed in 95 parts of deionized water, stirred at 580 rpm and heated to 44°C, after 32 minutes of dissolution, 3.5 parts of β-cyclodextrin is directly added to replace the original hydroxypropyl-β-cyclodextrin, and the reaction is stirred at 56°C for 3.5 hours, and the subsequent freeze-drying and crushing process is the same as example 4, and the preparation process of the suspension concentrate is exactly the same as example 4.

[0079] Performance test

[0080] The performance of the carbendazim suspension concentrates of examples 1-4 and comparative examples 1-5 was detected, and the results are shown in Table 1 below; wherein the suspension rate was detected according to GB / T14825-2006 Pesticide Suspension Rate Determination Method, and the pouring property was detected according to GB / T31737-2015 Pesticide Pouring Property Determination Method.

[0081] Table 1

[0082] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Suspendability 96.85 98.21 99.08 99.32 80.41 83.55 86.64 88.27 90.71 Hot reserve suspendability 95.21 96.85 97.33 98.12 78.52 82.34 86.73 89.22 92.49 14-day control efficiency 90.13 92.34 94.55 95.77 75.83 79.14 83.54 87.83 90.30 Pourable residue 1.85 1.42 1.15 1.03 5.81 4.56 3.20 2.36 1.78

[0083] From the performance test results, the carbendazim suspension concentrates prepared in examples 1-4 all showed excellent and increasing comprehensive performance in suspension rate, thermal storage stability, prevention effect and pouring property, among which the optimal process ratio represented by example 4 showed the best effect, indicating that its physical stability and biological activity retention ability were the most outstanding. This series of excellent performance is due to the effective synergy of multiple functional groups in the modified dispersant, including the common action of strong hydrophobic anchor segment, hydrated polyether side chain, cationic quaternary ammonium group and cyclodextrin inclusion structure, supplemented by the space network formed by the complex thickening system, which together ensures the long-term dispersion stability of the particles and effectively inhibits the austenite ripening.

[0084] In comparison, the performances of the comparative examples showed different degrees of decline due to the lack of structural integrity or component function of the dispersant. Comparative example 1 uses a conventional dispersant, which lacks multiple stabilization mechanisms and has overall deteriorated performance; comparative examples 2-5, although partially retaining the modified structure, lack the polymeric anchor enhancement, grafting group or cyclodextrin type replacement, resulting in insufficient adsorption stability, steric hindrance or austenite ripening inhibition ability, which is reflected in the decrease of thermal storage suspension rate, the decrease of prevention effect and the increase of pouring residue.

[0085] The above content is only an example and description of the present application, and those skilled in the art can make various modifications or supplements or use similar ways to replace the described specific examples, as long as they do not deviate from the scope of the invention or exceed the scope defined by the present claims, which shall belong to the protection scope of the present application.

Claims

1. A method for improving the uniformity of a carbendazim suspension concentrate, characterized in that, The method comprises the following steps: (1) mixing carbendazim, modified dispersant, wetting agent and part of deionized water, pre-dispersing by shearing to obtain a premix, then transferring the premix to a sand mill, adding zirconium oxide beads as grinding medium for grinding until the particle size reaches D90 of no more than 3.5 μm; (2) transferring the slurry obtained in step (1) to a stirred tank, adding antifreeze, thickening agent and defoaming agent in sequence, and stirring to uniformly disperse the additives; (3) adding the remaining deionized water to the mixture obtained in step (2) to adjust the solid content and pH value, filtering, and then standing and aging the filtrate, stirring at 200-300 rpm for 5 min every 4 h during the aging, and obtaining the carbendazim suspension after the aging is completed.

2. The method of improving the uniformity of carbendazim suspension concentrate according to claim 1, characterized in that, The preparation steps of the modified dispersant in step (1) are as follows: S1, dissolving succinic anhydride in N,N-dimethylformamide, adding allyl polyoxyethylene ether dropwise under stirring, adding p-toluenesulfonic acid after the dropwise addition is completed, warming and reacting, then pouring the reaction solution into an ice water mixture, stirring to precipitate a white solid, filtering, washing the filter cake with cold water until the filtrate is neutral, and vacuum drying the wet product to obtain intermediate I; S2, dissolving intermediate I, isooctyl acrylate and acrylamide in a mixed solvent composed of deionized water and isopropanol, warming under nitrogen protection and stirring, dissolving potassium persulfate in deionized water, adding it to the reaction system at a constant speed, keeping the reaction after the dropwise addition is completed, cooling to room temperature after the reaction is completed, precipitating, filtering, washing and vacuum drying to obtain a dispersant prepolymer; S3, weighing the dispersant prepolymer, dispersing it in deionized water, stirring and warming to dissolve, adding chitosan quaternary ammonium salt, then adding hydroxypropyl-β-cyclodextrin after warming and stirring, stirring at constant temperature to obtain a modified dispersant with a particle size D90 of less than 10 μm.

3. The method of improving the uniformity of carbendazim suspension concentrate according to claim 1, characterized in that, In step (1), the amounts of the components are 23-27 parts of carbendazim, 7-9 parts of modified dispersant, 2-4 parts of wetting agent and 30-40 parts of deionized water.

4. The method of improving the uniformity of carbendazim suspension concentrate according to claim 1, characterized in that, In step (2), the amounts of the components are 4-6 parts of antifreeze, 0.1-0.3 parts of thickening agent and 0.3-0.6 parts of defoaming agent.

5. The method of improving the uniformity of carbendazim suspension concentrate according to claim 1, characterized in that, In step S1, the amounts of the components are 10-15 parts of succinic anhydride, 30-40 parts of N,N-dimethylformamide, 30-40 parts of allyl polyoxyethylene ether, 0.2-0.4 parts of p-toluenesulfonic acid and 95-100 parts of ice water mixture.

6. The method of improving the uniformity of carbendazim suspension concentrate according to claim 1, characterized in that, In step S2, the amounts of the components are 18-22 parts of intermediate I, 6-9 parts of isooctyl acrylate, 4-7 parts of acrylamide, 45-58 parts of deionized water, 15-20 parts of isopropanol and 0.4-0.7 parts of potassium persulfate.

7. The method of improving the uniformity of carbendazim suspension concentrate according to claim 1, characterized in that, In step S3, the amounts of the components are 22-26 parts of dispersant prepolymer, 80-100 parts of deionized water, 3-6 parts of chitosan quaternary ammonium salt and 2-6 parts of hydroxypropyl-β-cyclodextrin.

8. The method of improving the uniformity of carbendazim suspension concentrate according to claim 1, characterized in that, In step (1), the wetting agent is at least one of isodecyl alcohol polyoxyethylene ether, sodium dodecylbenzenesulfonate and Span 20.

9. The method of improving the uniformity of carbendazim suspension concentrate according to claim 1, characterized in that, In step (2), the thickening agent is composed of xanthan gum and magnesium aluminum silicate in a mass ratio of 1-3:

1.

10. The method of improving the uniformity of carbendazim suspension concentrate according to claim 1, characterized in that, The antifreeze in the step (2) is at least one of ethylene glycol, glycerol and propylene glycol, and the defoaming agent is silicone assistant.