Low-volatility herbicide and production process thereof

Abstract

The invention discloses a low-volatility herbicide and a production process thereof, and belongs to the technical field of herbicide preparations. Firstly, composite modified starch containing carboxyl and epoxy groups is prepared through esterification of fumaric acid and graft copolymerization of styrene, butyl acrylate and glycidyl methacrylate; the low-volatility herbicide is prepared by compounding the composite modified starch with a polyether chain segment, synthesizing a fluorosilicone epoxy emulsifier containing a perfluorinated chain, an epoxy group and a polyether chain segment through hydrosilylation, and finally compounding the composite modified starch and the fluorosilicone epoxy emulsifier with an active compound, a solvent and other assistants. By constructing a multi-synergistic system with nonionic emulsification stability, composite starch interface adhesion and fluorosilicone chain hydrophobic protection as the core, the adhesiveness and rain wash resistance of the liquid medicine on leaf surfaces are enhanced, photolysis and volatilization of clomazone are effectively inhibited, the storage stability and application effect of the herbicide are improved, the lasting period of the herbicide is prolonged, and the herbicide has good application prospects. A new scheme is provided for solving the problems of poor stability, unstable pesticide effect and the like of a traditional herbicide.

Description

Technical Field

[0001] This invention belongs to the field of herbicide formulation technology, specifically a low-volatility herbicide and its production process. Background Technology

[0002] Isoxaflutole is an organic heterocyclic pre-emergence herbicide suitable for fields of crops such as soybeans and corn. It can control annual grasses and some broadleaf weeds, but its efficacy against broadleaf weeds is limited when used alone, and its long residual period can endanger subsequent crops. S-metolachlor is an amide herbicide that achieves soil sealing by inhibiting fatty acid synthesis, but it is ineffective against emerging weeds. Although the combination of the two can complement each other's mechanisms of action and broaden the spectrum of efficacy, the active ingredients have problems with poor compatibility and insufficient stability when formulated, which restricts their practical application.

[0003] Emulsifiable concentrate formulations are an important and widely used type of traditional pesticide formulation. Their core advantage lies in their simple processing technology. Through the synergistic effect of solvents and emulsifiers, hydrophobic isoxaflutole and metolachlor can be evenly dispersed in water to form a stable emulsion. After spraying, it can quickly adhere to the surface of weeds and penetrate and be absorbed, effectively solving the problems of poor dispersibility and uneven efficacy when the two active ingredients are combined. At the same time, it can further enhance the synergistic weeding effect of the two and improve the control efficiency against a variety of weeds. However, isoxaflutole itself has a certain degree of photolysis and volatility. After application in the field, its active ingredients are easily decomposed by light and become ineffective, or they may be lost into the atmosphere through volatilization. This not only reduces the weeding retention period, but may also cause unstable efficacy and bring environmental drift risks.

[0004] Chinese patent application CN114651820A discloses a sulfadiazine emulsifiable concentrate herbicide and its production process. By introducing an adhesion stabilizer composed of xanthan gum, alkyl glycosides, modified starch, and deacetylated chitosan, and by using citric acid and salicylic acid to modify the starch in two steps, the aim is to utilize the film-forming adhesion properties of modified starch to more firmly adhere the active ingredient of the herbicide to the surface of weeds or soil, thereby slowing down the photodegradation and volatilization of isoxaflutole to a certain extent, and achieving stable and sustained efficacy.

[0005] However, the acidic groups in the modified starch will react with the emulsifier calcium dodecylbenzenesulfonate, which will not only consume the effective emulsifying components, but may also lead to the destruction of the emulsion system, resulting in precipitation, stratification and other phenomena, which will seriously affect the storage stability and application effect of the herbicide emulsion. Summary of the Invention

[0006] The purpose of this invention is to provide a low-volatility herbicide and its production process. By constructing a multi-synergistic system with non-ionic emulsion stabilization, composite starch interface adhesion, and fluorosilicone chain hydrophobic protection as the core, the adhesion of the herbicide to the leaf surface and its resistance to rain washout are enhanced. This effectively inhibits the photolysis and volatilization of isoxaflutole, improves the storage stability, application effect, and duration of action of the herbicide, and provides a new solution to the problems of poor stability and unstable efficacy of traditional herbicides.

[0007] The objective of this invention can be achieved through the following technical solutions: A low-volatile herbicide is composed of a mixture of compound modified starch, fluorosilicone epoxy emulsifier, isoxaflutole technical grade, metolachlor technical grade, methyl oleate, dimethyl sulfoxide, and epoxidized soybean oil in a mass ratio of 28-32:85-95:95-105:75-85:400-420:190-210:12-18.

[0008] This invention also provides a production process for a low-volatility herbicide, comprising the following steps: Step 1: Using esterification and graft copolymerization, corn starch, fumaric acid, styrene, butyl acrylate and glycidyl methacrylate were used as raw materials to prepare composite modified starch with both carboxyl and epoxy groups.

[0009] Step 2: Using the hydrosilylation method, a fluorosilicone epoxy emulsifier is synthesized from polymethylhydrosiloxane, perfluorooctyl ethylene, allyl glycidyl ether and allyl polyoxyethylene polyoxypropylene ether.

[0010] Step 3: Mix the composite modified starch, fluorosilicone epoxy emulsifier, isoxaflutole, metolachlor technical, methyl oleate, dimethyl sulfoxide, and epoxidized soybean oil to obtain a low-volatile herbicide.

[0011] Furthermore, the specific preparation steps of the fluorosilicone epoxy emulsifier are as follows: Polymethylhydrosiloxane, perfluorooctylethylene, allyl glycidyl ether, allyl polyoxyethylene polyoxypropylene ether, and toluene were added to a reactor, followed by the addition of Karstedt catalyst at a mass concentration of 1.6 g / L. The reaction was carried out at 80-90 °C and 180-220 r / min for 5-6 h. After the reaction was completed, the fluorosilicone epoxy emulsifier was obtained by rotary evaporation and vacuum drying.

[0012] Furthermore, the ratio of polymethylhydrosiloxane, perfluorooctylethylene, allyl glycidyl ether, allyl polyoxyethylene polyoxypropylene ether, toluene, and Karstedt catalyst is 28-32g: 9.5-11g: 3.5-4g: 62-68g: 110-130mL: 0.32-0.4g.

[0013] Furthermore, the specific steps for compound modified starch are as follows: Fumarate-modified starch and N,N-dimethylformamide were added to a reaction vessel and stirred at 68-72℃ and 200-350 r / min for 0.8-1.2 h. Then, an azobisisobutyronitrile initiator solution dissolved in acetone was added dropwise over 45-60 min. The mixture was kept warm and stirred for another 25-35 min. Then, a mixed monomer solution consisting of styrene, butyl acrylate and glycidyl methacrylate was added dropwise over 60-90 min. The reaction was continued under the same conditions for 2.5-5 h. After the reaction was completed, the mixture was cooled to room temperature, and the product was precipitated with ice-cold methanol. The product was filtered, washed thoroughly with methanol, and dried under vacuum at 60℃. Finally, the product was purified using a Soxhlet extractor with acetone as the solvent for 24 h. After vacuum drying, the composite modified starch was obtained.

[0014] Furthermore, the ratio of fumarate-esterified starch, N,N-dimethylformamide, acetone, azobisisobutyronitrile, styrene, butyl acrylate, and glycidyl methacrylate is 32-38g: 140-150mL: 30-35mL: 0.8-1.2g: 30-35g: 6-7g: 3-3.5g.

[0015] Furthermore, the specific preparation steps of fumarate-treated starch are as follows: Fumaric acid was dissolved in acetone to obtain a fumaric acid solution. Corn starch and 4-dimethylaminopyridine were added sequentially to a reaction vessel and stirred for 3-8 min at 75-85℃ and 150-250 r / min. Then, the entire fumaric acid solution was added dropwise over 30-60 min. After the addition was complete, the reaction continued for 2.5-3.5 h. After the reaction was completed, the mixture was cooled to room temperature. The product was washed with anhydrous ethanol until no special odor was detected, and then dried under vacuum at 60℃ to obtain esterified starch.

[0016] Furthermore, the ratio of fumaric acid, acetone, corn starch and 4-dimethylaminopyridine is 15-20g: 600-800mL: 40-48g: 1.5-2g.

[0017] The beneficial effects of this invention are: 1. This invention prepares a highly stable and long-lasting low-volatility herbicide by constructing a multi-synergistic system with nonionic emulsification stabilization, composite starch interfacial adhesion, and hydrophobic protection of fluorosilicone chains as the core. This solution fundamentally solves the technical problems in the prior art, such as the destruction of the emulsion system and poor storage stability caused by the acid-base reaction between acid-modified starch and anionic emulsifier. At the same time, through the ingenious design of each component, this invention can significantly inhibit the photolysis and volatilization of active ingredients such as isoxaflutole after application, enhance the adhesion of the herbicide to the leaf surface and its resistance to rain washout, thereby achieving stable and long-lasting weed control and meeting the needs of use in complex field environments.

[0018] 2. The composite modified starch prepared in this invention functions as a core adhesion and reaction platform in the system. It introduces carboxyl groups into the starch skeleton through fumarate esterification, providing strong ionic and hydrogen bond adhesion. Furthermore, the styrene segments introduced through graft copolymerization enhance rigidity, the butyl acrylate segments impart flexibility, and the glycidyl methacrylate introduces highly reactive epoxy groups. This design not only gives it excellent film-forming adhesion, but more importantly, its epoxy groups can undergo a slow cross-linking reaction with the epoxy groups in the emulsifier molecules at the interface, synergistically constructing a dynamically enhanced interfacial film, which greatly improves the retention of the drug solution.

[0019] 3. The fluorosilicone epoxy emulsifier prepared in this invention plays a key role in efficient emulsification and multifunctional synergy in the system. This emulsifier uses polymethylhydrosiloxane as the backbone, and provides superhydrophobicity and impermeability through hydrosilylation grafting of perfluorooctyl ethylene, epoxy reactive sites through grafting of allyl glycidyl ether, and excellent hydrophilic emulsification ability through grafting of allyl polyoxyethylene polyoxypropylene ether. Its nonionic properties ensure compatibility with acid-modified starch, and fundamentally guarantee the long-term stability of the emulsion system. Among them, the perfluorinated segments can promote the spread of the drug solution on the waxy leaf surface, while the epoxy groups form a synergy with the epoxy groups of the composite modified starch, providing a basis for constructing an integrated "emulsification-adhesion" network.

[0020] 4. This invention achieves a significant synergistic effect by scientifically compounding modified starch, fluorosilicone epoxy emulsifier, herbicide technical material, and cosolvent. The modified starch and emulsifier form a dense and robust composite film at the droplet interface through potential cross-linking of epoxy groups, achieving an "anchoring-slow release" effect. The synergy between fluorosilicone segments and polymer branches endows the film with excellent weather resistance and toughness. This composite system not only effectively inhibits the volatilization and photolysis of isoxaflutole, but also enhances the interfacial adhesion, giving the herbicide excellent resistance to rain washout, thereby significantly improving the bioavailability and duration of action of the herbicide, demonstrating superior comprehensive performance compared to simple physical mixing adjuvants. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1: A low-volatility herbicide, produced by the following process: S1: Dissolve 18g of fumaric acid in 720mL of acetone to obtain a fumaric acid solution; add 44g of corn starch and 1.8g of 4-dimethylaminopyridine (DMAP) to the reaction vessel in sequence, stir for 6min at 80℃ and 200r / min, then add all the fumaric acid solution dropwise over 40min, and continue the reaction for 3h under the same conditions. After the reaction is completed, cool to room temperature, wash the product with anhydrous ethanol until there is no special odor, and then dry it under vacuum at 60℃ to obtain esterified starch.

[0023] This step employs a nucleophilic catalytic esterification method. Fumaric acid is first dissolved in acetone to form a homogeneous solution, which serves as the acylation reagent. Under heating and the action of the nucleophilic catalyst 4-dimethylaminopyridine, the hydroxyl groups on the corn starch molecular chain undergo an esterification reaction with the carboxyl groups in the fumaric acid molecules. A fumaryl group containing a double bond is introduced into the starch backbone through a covalent bond. After the reaction is complete, unreacted fumaric acid, catalyst, and byproducts can be removed by washing with ethanol. After drying, fumarate-esterified starch with a surface rich in carboxyl groups and higher hydrophilicity and reactivity is obtained.

[0024] S2: 36g of fumarate-treated starch and 146mL of N,N-dimethylformamide (DMF) were added to a reaction vessel and stirred for 1 hour at 70℃ and 250r / min. Then, 1g of azobisisobutyronitrile (AIBN) initiator solution dissolved in 33mL of acetone was added dropwise over 50 minutes. The mixture was kept warm and stirred for another 30 minutes. Then, a mixed monomer solution (composed of 32.5g styrene, 6.5g butyl acrylate and 3.25g glycidyl methacrylate) was added dropwise over 70 minutes. The reaction was continued for another 3 hours under the same conditions. After the reaction was completed, the mixture was cooled to room temperature. The product was precipitated in ice-cold methanol, filtered, washed thoroughly with methanol, and dried under vacuum at 60℃. Finally, the product was purified using a Soxhlet extractor with acetone as the solvent for 24 hours. After vacuum drying, the composite modified starch was obtained.

[0025] The process involves free radical graft copolymerization. First, starch is swelled and esterified with DMF to extend its molecular chains and expose active sites. Then, under the initiation of azobisisobutyronitrile (AIBN), the generated free radicals attack the starch chains to form macromolecular free radicals. These macromolecular free radicals then sequentially polymerize with styrene (providing hydrophobic rigidity), butyl acrylate (imparting flexibility), and glycidyl methacrylate (introducing epoxy groups), grafting polymer side chains onto the starch backbone via covalent bonds. Finally, the modified starch is obtained through precipitation and Soxhlet extraction purification. S3: 30g of polymethylhydrosiloxane (PMHS, hydrogen content 0.16-0.18), 10.3g of perfluorooctylethylene (PFOE), 3.8g of allyl glycidyl ether (AGE), 65.2g of allyl polyoxyethylene polyoxypropylene ether (F6-PO) and 120mL of toluene were added to a reactor, followed by the addition of 0.36g of Karstedt catalyst with a mass concentration of 1.6g / L. The reaction was carried out at a temperature of 80-90℃ and a stirring speed of 200r / min for 5.5h. After the reaction was completed, toluene was removed by rotary evaporation, and then the mixture was vacuum dried at 50℃ for 4h to further remove residual solvent and unreacted volatile components, thus obtaining a fluorosilicone epoxy emulsifier.

[0026] Using a combination of hydrosilylation and functional group grafting, the Si-H bonds of low-hydrogen-content polymethylhydrosiloxane (PMHS) undergo addition reactions with the carbon-carbon double bonds of perfluorooctyl ethylene (PFOE), allyl glycidyl ether (AGE), and allyl polyoxyethylene polyoxypropylene ether (F6-PO) under the action of a Karstedt catalyst. The perfluorooctyl segment provides hydrophobic weather resistance, allyl glycidyl ether introduces epoxy active sites, and allyl polyoxyethylene polyoxypropylene ether provides hydrophilic segments.

[0027] S4: Add 410g of solvent methyl oleate to a mixing tank, then add 200g of cosolvent dimethyl sulfoxide, 90g of fluorosilicone epoxy emulsifier, 30g of composite modified starch, 100g of isoxaflutole technical grade, 80g of S-metolachlor technical grade, and 15g of epoxidized soybean oil in sequence. Stir and mix for 40min at a speed of 200r / min. After filtration through a 1μm filter membrane, a low-volatility herbicide is obtained.

[0028] Example 2: A low-volatility herbicide, produced by the following process: S1: Dissolve 15g of fumaric acid in 600mL of acetone to obtain a fumaric acid solution; add 40g of corn starch and 1.5g of 4-dimethylaminopyridine (DMAP) to the reaction vessel in sequence, stir for 3min at 75℃ and 150r / min, then add all the fumaric acid solution dropwise over 30min, and continue the reaction for 2.5h under the same conditions. After the reaction is completed, cool to room temperature, wash the product with anhydrous ethanol until there is no special odor, and then dry it under vacuum at 60℃ to obtain esterified starch.

[0029] S2: 32g of fumarate-treated starch and 140mL of N,N-dimethylformamide (DMF) were added to a reaction vessel and stirred and swollen for 0.8h at 68℃ and 200r / min. Then, 0.8g of azobisisobutyronitrile (AIBN) initiator solution dissolved in 30mL of acetone was added dropwise over 45min. The mixture was kept warm and stirred for another 25min. Then, a mixed monomer solution (composed of 30g styrene, 6g butyl acrylate and 3g glycidyl methacrylate) was added dropwise over 60min. The reaction was continued for another 2.5h under the same conditions. After the reaction was completed, the mixture was cooled to room temperature, and the product was precipitated in ice-cold methanol. The product was filtered, washed thoroughly with methanol, and dried under vacuum at 60℃. Finally, the product was purified using a Soxhlet extractor with acetone as solvent for 24h. After vacuum drying, the composite modified starch was obtained.

[0030] S3: 28g of polymethylhydrosiloxane (PMHS, hydrogen content 0.16-0.18), 9.5g of perfluorooctylethylene (PFOE), 3.5g of allyl glycidyl ether (AGE), 62g of allyl polyoxyethylene polyoxypropylene ether (F6-PO) and 110mL of toluene were added to a reactor, followed by the addition of 0.32g of Karstedt catalyst with a mass concentration of 1.6g / L. The reaction was carried out at 80℃ and with stirring at 180r / min for 5h. After the reaction was completed, toluene was removed by rotary evaporation, and then the mixture was dried under vacuum at 50℃ to further remove residual solvent and unreacted volatile components, yielding a fluorosilicone epoxy emulsifier.

[0031] S4: Add 400g of solvent methyl oleate to a mixing tank, then add 190g of cosolvent dimethyl sulfoxide, 85g of fluorosilicone epoxy emulsifier, 28g of composite modified starch, 95g of isoxaflutole technical grade, 75g of S-metolachlor technical grade, and 12g of epoxidized soybean oil in sequence. Stir and mix for 35 minutes at a speed of 180r / min. After filtration through a 1μm filter membrane, a low-volatility herbicide is obtained.

[0032] Example 3: A low-volatility herbicide, produced by the following process: S1: Dissolve 20g of fumaric acid in 800mL of acetone to obtain a fumaric acid solution; add 48g of corn starch and 2g of 4-dimethylaminopyridine (DMAP) to the reaction vessel in sequence, stir for 8min at 85℃ and 250r / min, then add all the fumaric acid solution dropwise over 60min, and continue the reaction for 3.5h under the same conditions. After the reaction is completed, cool to room temperature, wash the product with anhydrous ethanol until there is no special odor, and then dry it under vacuum at 60℃ to obtain esterified starch.

[0033] S2: 38g of fumarate-modified starch and 150mL of N,N-dimethylformamide (DMF) were added to a reaction vessel and stirred for 1.2h at 72℃ and 350r / min. Then, 1.2g of azobisisobutyronitrile (AIBN) initiator solution dissolved in 35mL of acetone was added dropwise over 60min. The mixture was kept warm and stirred for another 35min. Then, a mixed monomer solution (composed of 35g of styrene, 7g of butyl acrylate and 3.5g of glycidyl methacrylate) was added dropwise over 90min. The reaction was continued for another 5h under the same conditions. After the reaction was completed, the mixture was cooled to room temperature. The product was precipitated in ice-cold methanol, filtered, washed thoroughly with methanol, and dried under vacuum at 60℃. Finally, the product was purified using a Soxhlet extractor with acetone as solvent for 24h. After vacuum drying, the composite modified starch was obtained.

[0034] S3: 32g of polymethylhydrosiloxane (PMHS, hydrogen content 0.16-0.18), 11g of perfluorooctylethylene (PFOE), 4g of allyl glycidyl ether (AGE), 68g of allyl polyoxyethylene polyoxypropylene ether (F6-PO) and 130mL of toluene were added to a reactor, followed by the addition of 0.4g of Karstedt catalyst with a mass concentration of 1.6g / L. The reaction was carried out at 90℃ and 220r / min for 6h. After the reaction was completed, toluene was removed by rotary evaporation, and then vacuum dried at 50℃ to further remove residual solvent and unreacted volatile components, thus obtaining a fluorosilicone epoxy emulsifier.

[0035] S4: Add 420g of solvent methyl oleate to a mixing tank, then add 210g of cosolvent dimethyl sulfoxide, 95g of fluorosilicone epoxy emulsifier, 32g of composite modified starch, 105g of isoxaflutole technical grade, 85g of S-metolachlor technical grade, and 18g of epoxidized soybean oil in sequence. Stir and mix at 220r / min for 45min. After filtration through a 1μm filter membrane, a low-volatility herbicide is obtained.

[0036] The raw materials used in Examples 1-3 of this application are all commercially available. Fumaric acid (99%) was purchased from Shandong Mopai Biotechnology Co., Ltd.; 4-dimethylaminopyridine (≥99%), N,N-dimethylformamide (AR, ≥99.5%), azobisisobutyronitrile (≥98%), styrene (≥99%), and butyl acrylate (≥99%) were purchased from Shanghai Aladdin Biochemical Co., Ltd.; glycidyl methacrylate (97%), allyl glycidyl ether (99.9%), corn starch (reagent grade), and methyl oleate (… 99% epoxidized soybean oil (reagent grade) and dimethyl sulfoxide (≥99.7%) were purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; perfluorooctyl ethylene (≥99%) was purchased from Wuhan Kanos Technology Co., Ltd.; allyl polyoxyethylene polyoxypropylene ether (99.9%) was purchased from Zhejiang Lvkean Chemical Co., Ltd.; polymethylhydrosiloxane (hydrogen content 0.16-0.18, viscosity 20-30) was purchased from Nanjing Bermuda Biotechnology Co., Ltd.; isoxaflutole was purchased from Jiangsu Bailing Agricultural Chemical Co., Ltd.; and metolachlor was purchased from Shanghai Jiegu Biotechnology Co., Ltd.

[0037] Application Example: In the process of weed control in crop fields, the low-volatile herbicide of this invention is diluted with water at a mass ratio of 1:(200-300) to prepare a uniform emulsion. This emulsion is then applied to the soil using a sprayer before crop sowing or before weed emergence, with a spraying rate of 150-200 mL / acre. After spraying, the herbicide, with the help of the hydrophobic spreadability of the fluorosilicone segments and the interfacial adhesion of the modified starch, quickly forms a dense protective film on the soil surface and weed seedlings. This film resists rainwater erosion and inhibits the photodegradation and volatilization of isoxaflutole. Throughout the crop's growth period, the herbicide slowly releases its active ingredients, continuously exerting the synergistic weeding effect of isoxaflutole and metolachlor. This improves the control rate of annual grasses and some broadleaf weeds, prolongs the effective period, and does not affect the growth of subsequent crops, achieving a highly efficient, stable, and long-lasting weed control effect.

[0038] Comparative Example 1: Based on Example 1, steps S2 and S3 were omitted, i.e., the composite modified starch and fluorosilicone epoxy emulsifier were not prepared. In step S4, 410g of methyl oleate was added to a mixing tank, followed by 200g of dimethyl sulfoxide, 100g of isoxaflutole technical grade, 80g of S-metolachlor technical grade, and 10g of epoxidized soybean oil. The mixture was stirred and filtered under the same conditions to obtain the herbicide.

[0039] Comparative Example 2: Based on Example 1, step S2 was omitted, i.e., the composite modified starch was not prepared. In step S4, 410g of methyl oleate was added to a mixing tank, followed by 200g of dimethyl sulfoxide, 90g of fluorosilicone epoxy emulsifier, 100g of isoxaflutole technical grade, 80g of S-metolachlor technical grade, and 10g of epoxidized soybean oil. The mixture was stirred and filtered under the same conditions to obtain the herbicide.

[0040] Comparative Example 3: Based on Example 1, the fluorosilicone epoxy emulsifier prepared in step S3 was replaced with an equal mass of the traditional anionic emulsifier calcium dodecylbenzenesulfonate, while all other steps and parameters remained unchanged, and a herbicide was prepared.

[0041] The herbicide samples prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests. The stability was determined in accordance with the GB / T 1603-2001 standard. The presence of floating oil (paste), settling oil, and precipitation was observed. If none of these occurred, the system was considered qualified; if they did, it was considered unqualified. This indicator directly reflects the dispersion uniformity and system stability of the herbicide after dilution with water, which is a basic condition for ensuring uniform spraying in the field.

[0042] Field weed control efficiency: 20 seeds each of common target weeds (barnyardgrass, sedge, flat-stemmed sedge, duckweed, and Echinochloa crus-galli) were selected and tested under two treatments: Soil sealing treatment: The experimental soil was prepared and weed seeds were sown. Before weed germination, the diluted herbicide was sprayed evenly onto the soil surface using a manual sprayer at a dosage of 150-200 mL / mu and a water dosage of 45 kg / mu. A blank control group (sprayed with the same amount of water) was set up. The number of germinating weeds after 7 days and the number of surviving weeds after 21 days were recorded. The weed control rate was calculated. The formula is: Weed control rate = (Total number of sown plants - Number of surviving plants) / Total number of sown plants × 100%; Foliar treatment: Sow weed seeds, and when the weeds grow to the 3-4 leaf stage, spray the diluted herbicide at a rate of 30 kg / mu with water; Set up a blank control group, and record the number of weeds that did not die after 3 days and the number of remaining weeds after 21 days (including weeds that regenerated after dying). The weed control rate is calculated as above. A weed control rate ≥ 90% indicates excellent killing effect on the target weeds. No regenerated weeds after 21 days indicates that the herbicide's residual effect meets the actual needs of long-term control in the field.

[0043] Rain erosion resistance: The herbicide sample was sprayed according to the above foliar treatment method. 20 minutes after spraying, a simulated rainfall device (rainfall intensity 10 mm / h, lasting 30 min) was used to simulate erosion of the weeds. A control group under the same conditions without rainfall was set up. After 3 days, the number of weeds that did not die was recorded, and the weed control rate after rain erosion was calculated. The control rate retention rate was further calculated: Control rate retention rate = (control rate after erosion / control rate) × 100%. The control rate retention rate ≥ 85% indicates that the active ingredient of the herbicide sample has excellent adhesion to the weed surface after spraying and can resist the loss of herbicide caused by natural rainfall in the field.

[0044] Table 1 Performance test results of various herbicides As can be seen from the performance test results, the low-volatility herbicides prepared in Examples 1-3 of this invention achieve a triple synergistic effect of fluorosilicone hydrophobic spreading, carboxyl electrostatic adhesion, and polymer chain hydrogen bond anchoring by constructing a multi-synergistic system with nonionic emulsion stabilization, composite starch interface adhesion, and hydrophobic protection of fluorosilicone chains as the core. Examples 1-3 show outstanding performance in terms of emulsion stability, weed control efficiency, duration of action, and resistance to rain washout. They fundamentally solve the core defects of traditional herbicides caused by the reaction between acid-modified starch and anionic emulsifiers, such as system instability and easy efficacy decay. They significantly improve the product's storage stability, field application consistency, and adaptability to complex environments.

[0045] Comparative Example 1 lacked the composite modified starch and fluorosilicone epoxy emulsifier components, and its overall performance was significantly inferior to that of the Example. This may be because the two components play a key role as an integrated "emulsification-adhesion-protection synergistic unit." The composite modified starch provides interfacial adhesion, and the fluorosilicone epoxy emulsifier ensures system stability and imparts hydrophobic protection. Without both, the herbicide solution may have difficulty forming a stable emulsion and may not adhere firmly to the weed surface, leading to easy loss of active ingredients and photodegradation, thus significantly affecting the weeding effect.

[0046] Comparative Example 2 lacked the composite modified starch component, and its performance was weaker than that of the Example. This may be because the composite modified starch plays a core role as an "interfacial adhesion and membrane structure enhancement unit." This component may help the herbicide adhere more tightly to the weed surface and form a protective film through carboxyl electrostatic adhesion and polymer chain hydrogen bond anchoring. Without it, the herbicide's resistance to rain washout may decrease, and the herbicide film structure may become loose, making it difficult to maintain a long-lasting weed control effect.

[0047] Comparative Example 3 replaced the fluorosilicone epoxy emulsifier with the traditional anionic emulsifier calcium dodecylbenzenesulfonate. Its performance was between that of the examples and Comparative Examples 1-2. This may be because the nonionic nature of the fluorosilicone epoxy emulsifier is an important prerequisite for ensuring its compatibility with acidic composite modified starch. Traditional anionic emulsifiers may interact with the acidic groups in the composite modified starch, affecting the stability of the emulsion system and causing uneven dispersion of the active ingredients. This may reduce the weeding efficiency and make it difficult to synergistically construct a stable interfacial protective film, thus failing to achieve the best synergistic effect of each component.

[0048] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0049] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A production process for a low-volatile herbicide, characterized in that, Prepared by the following steps: Step 1: Using esterification and graft copolymerization, corn starch, fumaric acid, styrene, butyl acrylate and glycidyl methacrylate as raw materials, a composite modified starch with both carboxyl and epoxy groups is prepared. Step 2: Mix the composite modified starch, fluorosilicone epoxy emulsifier, isoxaflutole, S-metolachlor technical, methyl oleate, dimethyl sulfoxide, and epoxidized soybean oil to obtain a low-volatile herbicide.

2. The production process of a low-volatility herbicide according to claim 1, characterized in that, The mass ratio of the composite modified starch, fluorosilicone epoxy emulsifier, isoxaflutole technical grade, metolachlor technical grade, methyl oleate, dimethyl sulfoxide, and epoxidized soybean oil is 28-32:85-95:95-105:75-85:400-420:190-210:12-18.

3. The production process of a low-volatility herbicide according to claim 1, characterized in that, The fluorosilicone epoxy emulsifier is synthesized from polymethylhydrosiloxane, perfluorooctylethylene, allyl glycidyl ether and allyl polyoxyethylene polyoxypropylene ether by hydrosilylation.

4. The production process of a low-volatility herbicide according to claim 3, characterized in that, The specific preparation steps of the fluorosilicone epoxy emulsifier are as follows: Polymethylhydrosiloxane, perfluorooctylethylene, allyl glycidyl ether, allyl polyoxyethylene polyoxypropylene ether, and toluene were added to a reactor, followed by the addition of Karstedt catalyst at a mass concentration of 1.6 g / L. The reaction was carried out at 80-90 °C and 180-220 r / min for 5-6 h. After the reaction was completed, the fluorosilicone epoxy emulsifier was obtained by rotary evaporation and vacuum drying.

5. The production process of a low-volatility herbicide according to claim 4, characterized in that, The ratio of polymethylhydrosiloxane, perfluorooctylethylene, allyl glycidyl ether, allyl polyoxyethylene polyoxypropylene ether, toluene, and Karstedt catalyst is 28-32g: 9.5-11g: 3.5-4g: 62-68g: 110-130mL: 0.32-0.4g.

6. The production process of a low-volatility herbicide according to claim 1, characterized in that, The specific steps for the compound modified starch are as follows: Fumarate-modified starch and N,N-dimethylformamide were added to a reaction vessel and stirred at 68-72℃ and 200-350 r / min for 0.8-1.2 h. Then, an azobisisobutyronitrile initiator solution dissolved in acetone was added dropwise over 45-60 min. After the addition was completed, the mixture was stirred at the same temperature for 25-35 min. Then, a mixed monomer solution consisting of styrene, butyl acrylate and glycidyl methacrylate was added dropwise over 60-90 min. The reaction was continued for 2.5-5 h. The mixture was cooled, and the product was precipitated with ice-cold methanol. The product was filtered, washed, and dried. Finally, it was purified with acetone as solvent using a Soxhlet extractor for 24 h and dried to obtain the composite modified starch.

7. The production process of a low-volatility herbicide according to claim 6, characterized in that, The ratio of fumarate-esterified starch, N,N-dimethylformamide, acetone, azobisisobutyronitrile, styrene, butyl acrylate and glycidyl methacrylate is 32-38g: 140-150mL: 30-35mL: 0.8-1.2g: 30-35g: 6-7g: 3-3.5g.

8. The production process of a low-volatility herbicide according to claim 6, characterized in that, The specific preparation steps for the fumarate-esterified starch are as follows: Fumaric acid was dissolved in acetone to obtain a fumaric acid solution. Corn starch and 4-dimethylaminopyridine were added sequentially to a reaction vessel and stirred for 3-8 min at 75-85℃ and 150-250 r / min. Then, the entire fumaric acid solution was added dropwise over 30-60 min. After the addition was complete, the reaction continued for 2.5-3.5 h. After the reaction was completed, the mixture was cooled to room temperature, and the product was washed and dried to obtain esterified starch.

9. The production process of a low-volatility herbicide according to claim 8, characterized in that, The ratio of fumaric acid, acetone, corn starch and 4-dimethylaminopyridine is 15-20g: 600-800mL: 40-48g: 1.5-2g.

10. A low-volatility herbicide, characterized in that, It is produced by the production process described in any one of claims 1-9.

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