Microemulsion containing cyhalofop-butyl and metamifop and preparation method thereof

Abstract

The invention provides a microemulsion containing cyhalofop-butyl and metamifop, which comprises the following components in percentage by mass: 10 to 25 percent of active component, 10 to 20 percent of solvent, 20 to 25 percent of emulsifier, 5 to 10 percent of cosurfactant, 2 to 5 percent of stabilizer, 0.5 to 2.5 percent of antifreezing agent, 1 to 3 percent of anti-evaporation agent and the balance of water, the active ingredients are cyhalofop butyl and metamifop; the emulsifier comprises a molecular weight of 1t; a low molecular weight emulsifier of 500 g / mol and a molecular weight gt; and a high molecular weight emulsifier of 1500 g / mol. The particle size of the microemulsion reaches the nanoscale, and the microemulsion is suitable for being used under the high-temperature condition, high in stability and good in weeding effect.

Description

Technical Field

[0001] The invention belongs to the field of pesticides, and particularly relates to a microemulsion containing cyhalofop-butyl and metamifop-butyl and a preparation method thereof. Background Art

[0002] Cyhalofop-butyl is a systemic herbicide of the oxyphenoxypropionic acid class developed by Dow AgroSciences, which is highly safe for rice. It can be absorbed through the leaves and sheaths of plants, inhibiting acetyl-CoA carboxylase (ACCase), thereby affecting the normal growth and division of cells, and ultimately leading to plant death. The agent is mainly used to control grass weeds such as barnyard grass, lycopodii, crabgrass, and goosegrass.

[0003] Metamifop is an aryloxyphenoxypropionate herbicide developed by the Korea Institute of Chemical Technology. It is another ACCase inhibitor that can effectively inhibit the synthesis of plant fatty acids, leading to the death of weeds. Metamifop is mainly used to control annual grass weeds such as barnyard grass, lycopodii and goosegrass.

[0004] Rice is the main food crop in my country. With the expansion of direct-seeding rice planting area, the drug resistance of grass weeds has increased dramatically. Although both oxadiazine and cyfluthrin are ACCase inhibitors, they have different action sites. Market feedback shows that these two agents have significant synergistic effects in weed control applications. However, under high temperature conditions in summer, factors such as closure of weed stomata, thickening of the cuticle, and accelerated evaporation rate of pesticide droplets can lead to a significant decrease in drug efficacy.

[0005] Therefore, it is of great research significance to provide a herbicidal composition that can maintain or further improve the efficacy of the combination of metamifop-cyfluthrin and cyhalofop-butyl in a high temperature environment. Summary of the invention

[0006] In order to overcome the deficiencies of the prior art, the present invention provides a microemulsion containing cyhalofop-butyl and metamifop-butyl, which has good stability and efficacy under high temperature conditions and expands the applicable scenarios.

[0007] A microemulsion containing cyhalofop-butyl and metamifop-butyl, which comprises, by mass percentage, 10% to 25% of active ingredient, 10% to 20% of solvent, 20% to 25% of emulsifier, 5% to 10% of cosurfactant, 2% to 5% of stabilizer, 0.5% to 2.5% of antifreeze agent, 1% to 3% of antievaporation agent, and the balance is water;

[0008] The active ingredients are cyhalofop-butyl and metamifop-butyl;

[0009] The emulsifier comprises a low molecular weight emulsifier with a molecular weight of <500 g / mol and a high molecular weight emulsifier with a molecular weight of >1500 g / mol.

[0010] As an example, in the emulsifier, the mass ratio of the low molecular weight emulsifier to the high molecular weight emulsifier is 1:(1.5-7.5).

[0011] As an example, the low molecular weight emulsifier is selected from one or a combination of sodium dodecylbenzene sulfonate, isomeric tridecanol polyoxyethylene ether, sodium dioctyl sulfonate succinate, fatty alcohol polyoxyethylene ether and alkyl glycoside;

[0012] The HLB of the high molecular weight emulsifier is greater than 11, and is preferably one or more combinations of castor oil polyoxyethylene ether, propylene glycol block polyether, and tristyrylphenol polyoxyethylene ether.

[0013] As an example, the low molecular weight emulsifier is selected from one or a combination of sodium dodecylbenzene sulfonate, isomeric tridecanol polyoxyethylene ether and sodium dioctyl sulfonate succinate, and contains at least one anionic emulsifier;

[0014] The high molecular weight emulsifier is selected from one or a combination of tristyrylphenol polyoxyethylene ether, propylene glycol block polyether, and castor oil polyoxyethylene ether.

[0015] As an example, the co-surfactant is selected from one or more combinations of ethanol, isobutanol, isopentanol, isooctyl alcohol, dimethyl sulfoxide, dimethylacetamide, and N-methylpyrrolidone.

[0016] As an example, the stabilizer includes tristyrylphenol polyethylene glycol phosphate and one or more combinations selected from sodium ethoxylated alkyl sulfate, sodium lauroyl sarcosinate or sodium fatty alcohol polyoxyethylene ether sulfate.

[0017] As an example, the antifreeze agent is selected from one or more combinations of glycerol, propylene glycol, and ethylene glycol.

[0018] As an example, the anti-evaporation agent is selected from polyethylene glycol, glycerol, Atplus TM UEP-100, Hydravance TM 200. Synergen TM One or more combinations of OS.

[0019] As an example, the solvent is one or more selected from naphtha, cyclohexanone, xylene, isooctyl acetate, and ethylene glycol mono-n-butyl ether acetate.

[0020] The present invention also provides a method for preparing a microemulsion containing cyhalofop-butyl and metamifop-butyl as described in any one of the above contents, which comprises adding active ingredients, solvents and co-surfactants into a stirring kettle according to a formula, heating to 30-40° C., stirring until the active ingredients are completely dissolved, and then sequentially adding an emulsifier, a stabilizer, an antifreeze agent and an anti-evaporation agent, stirring, and finally adding the remaining amount of water and continuing to stir to obtain the microemulsion.

[0021] The present invention has the following advantages:

[0022] (1) The present invention successfully prepares a microemulsion containing cyhalofop-butyl and metamifop-butyl through the synergistic coordination of the components and the precise proportion of the components. The particle size of the prepared microemulsion reaches the nanometer level, enriching the product types of rice herbicides and being suitable for use under high temperature conditions.

[0023] (2) The present invention uses a combination of a low molecular weight emulsifier (Mw<500 g / mol) and a high molecular weight emulsifier (Mw>1500 g / mol). The low molecular weight emulsifier promotes the formation of nano-scale oil droplets, while the high molecular weight emulsifier helps to delay the agglomeration of oil droplets after dilution. The two act synergistically and optimize the formation and stability of oil droplets. The prepared nano-microemulsion can maintain a particle size of less than 100 nm for at least 5 hours after being diluted 50 times, and is particularly suitable for the preparation and application of flying control agents.

[0024] (3) The present invention successfully solves the problem that oxadiazine is prone to hydrolysis in microemulsion formulations by adding a specific stabilizer, and the prepared nano-microemulsion has satisfactory emulsion stability, thermal storage stability, and low-temperature stability.

[0025] (4) The present invention significantly improves the deposition amount after application and reduces the evaporation rate under high temperature conditions by improving the surface tension, contact angle and evaporation rate of the microemulsion containing cyhalofop-butyl and metamifop-butyl. Under the condition of temperature above 30°C, a synergistic effect of more than 30% can be achieved. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Anti-evaporation agent is selected from polyethylene glycol, glycerol, Atplus TM UEP-100 (Hero), Hydravance TM 200 (Grada), Synergen TM OS (Clariant).

[0028] The ratio of emulsifier to solvent is at least 1:1.

[0029] Example 1

[0030] Microemulsion containing cyhalofop-butyl and metamifop-butyl, comprising, by mass percentage:

[0031] Cyhalofop-butyl 5%, oxadiazine 5%, cyclohexanone 10% (solvent), naphtha 5% (solvent), isooctyl alcohol 10% (co-surfactant), dioctyl sodium sulfosuccinate 3.2% (low molecular weight emulsifier), sodium dodecylbenzene sulfonate 5.6% (low molecular weight emulsifier), tristyrylphenol polyoxyethylene ether 13.2% (high molecular weight emulsifier), tristyrylphenol polyethylene glycol phosphate 1% (stabilizer), fatty alcohol polyoxyethylene ether sodium sulfate 2.5% (stabilizer), ethylene glycol 1.5% (antifreeze agent), Atplus TM UEP-100 2% (anti-evaporation agent), the balance is tap water.

[0032] The preparation method is as follows:

[0033] The solvent, the co-surfactant, the cyhalofop-butyl technical drug and the metamifop-butyl technical drug are added into a stirring kettle in proportion, the temperature is raised to 30-40° C., and the active ingredients (cyhalofop-butyl technical drug and metamifop-butyl technical drug) are stirred until they are completely dissolved. Then, the emulsifier, the stabilizer, the antifreeze agent and the anti-evaporation agent are added in sequence, and the mixture is stirred for 30 minutes. Then, the remaining water is added, and the stirring is continued for 30 minutes to obtain a microemulsion containing cyhalofop-butyl and metamifop-butyl.

[0034] Examples 2 to 4, and Comparative Examples 1 to 4 were prepared according to the method steps of Example 1.

[0035] Example 2

[0036] Microemulsion containing cyhalofop-butyl and metamifop-butyl, comprising, by mass percentage:

[0037] Cyanosulfuron 10%, oxadiazon 10%, isooctyl acetate 10% (solvent), xylene 5% (solvent), ethylene glycol monobutyl ether acetate 5% (solvent), butanol 8% (co-surfactant), sodium dodecylbenzene sulfonate 2.2% (low molecular weight emulsifier), isomeric tridecyl alcohol polyoxyethylene ether 4% (low molecular weight emulsifier), tristyrylphenol polyoxyethylene ether 15.8% (high molecular weight emulsifier), tristyrylphenol polyethylene glycol phosphate 1.5% (stabilizer), sodium polyoxyethylene fatty alcohol ether sulfate 3% (stabilizer), propylene glycol 2.5% (antifreeze), glycerol 3% (anti-evaporation agent), and the balance is tap water.

[0038] Example 3

[0039] Microemulsion containing cyhalofop-butyl and metamifop-butyl, comprising, by mass percentage:

[0040] Cyanosulfuron 15%, oxadiazine 10%, cyclohexanone 10% (solvent), xylene 10% (solvent), ethanol 5% (co-surfactant), isooctyl alcohol 5% (co-surfactant), dioctyl sodium sulfosuccinate 7.5% (low molecular weight emulsifier), tristyrylphenol polyoxyethylene ether 8.75% (high molecular weight emulsifier), castor oil polyoxyethylene ether 8.75% (high molecular weight emulsifier), tristyrylphenol polyethylene glycol phosphate 1% (stabilizer), fatty alcohol polyoxyethylene ether sodium sulfate 2% (stabilizer), ethylene glycol 1.5% (antifreeze), polyethylene glycol (PEG-200) 2.5% (anti-evaporation agent), and the balance is tap water.

[0041] Example 4

[0042] Microemulsion containing cyhalofop-butyl and metamifop-butyl, comprising, by mass percentage:

[0043] Cyhalofop-butyl 10%, oxadiazine 15%, cyclohexanone 10% (solvent), ethylene glycol monobutyl ether acetate 10% (solvent), ethanol 5% (co-surfactant), dimethyl sulfoxide 5% (co-surfactant), sodium dodecylbenzene sulfonate 5% (low molecular weight emulsifier), propylene glycol block polyether L64 (high molecular weight emulsifier) ​​2.5%, tristyrylphenol polyoxyethylene ether 15% (high molecular weight emulsifier), tristyrylphenol polyethylene glycol phosphate 1.5% (stabilizer), fatty alcohol polyoxyethylene ether sodium sulfate 3% (stabilizer), ethylene glycol 1.5% (antifreeze), Hydravance TM 200 (anti-evaporation agent) 2%, the balance is tap water.

[0044] Comparative Example 1

[0045] Microemulsion containing cyhalofop-butyl and metamifop-butyl, comprising, by mass percentage:

[0046] Cyhalofop-butyl 5%, oxadiazine 5%, cyclohexanone 10% (solvent), naphtha 5% (solvent), isooctyl alcohol 10% (co-surfactant), propylene glycol block polyether L64 11% (high molecular weight emulsifier), tristyrylphenol polyoxyethylene ether 11% (high molecular weight emulsifier), tristyrylphenol polyethylene glycol phosphate 1% (stabilizer), fatty alcohol polyoxyethylene ether sodium sulfate 2.5% (stabilizer), ethylene glycol 1.5% (antifreeze agent), Atplus TM UEP-100 2% (anti-evaporation agent), the balance is tap water.

[0047] Comparative Example 1 lacks a low molecular weight emulsifier.

[0048] Comparative Example 2

[0049] Microemulsion containing cyhalofop-butyl and metamifop-butyl, comprising, by mass percentage:

[0050] Cyhalofop-butyl 5%, oxadiazine 5%, cyclohexanone 10% (solvent), naphtha 5% (solvent), isooctyl alcohol 10% (co-surfactant), sodium dodecylbenzene sulfonate 4.4% (low molecular weight emulsifier), sodium dioctyl sulfonate succinate 4.4% (low molecular weight emulsifier), alkyl glycoside 13.2% (low molecular weight emulsifier), tristyrylphenol polyethylene glycol phosphate 1% (stabilizer), sodium polyoxyethylene fatty alcohol ether sulfate 2.5% (stabilizer), ethylene glycol 1.5% (antifreeze), Atplus TM UEP-100 2% (anti-evaporation agent), the balance is tap water.

[0051] Comparative Example 2 lacks a high molecular weight emulsifier.

[0052] Comparative Example 3

[0053] Cyhalofop-butyl 5%, oxadiazine 5%, cyclohexanone 10% (solvent), naphtha 5% (solvent), isooctyl alcohol 10% (co-surfactant), sodium dioctyl sulfosuccinate 1.65% (low molecular weight emulsifier), sodium dodecylbenzene sulfonate 3.45% (low molecular weight emulsifier), tristyrylphenol polyoxyethylene ether 9.9% (high molecular weight emulsifier), tristyrylphenol polyethylene glycol phosphate 1% (stabilizer), sodium fatty alcohol polyoxyethylene ether sulfate 2.5% (stabilizer), ethylene glycol 1.5% (antifreeze agent), Atplus TM UEP-100 2% (anti-evaporation agent), the balance is tap water.

[0054] The content of the emulsifier in Comparative Example 3 is not within the range of 20% to 25% of the present invention.

[0055] Comparative Example 4

[0056] Microemulsion containing cyhalofop-butyl and metamifop-butyl, comprising, by mass percentage:

[0057] Cyhalofop-butyl 5%, oxadiazine 5%, cyclohexanone 10% (solvent), naphtha 5% (solvent), isooctyl alcohol 10% (co-surfactant), dioctyl sodium sulfosuccinate 2.2% (low molecular weight emulsifier), sodium dodecylbenzene sulfonate 4.6% (low molecular weight emulsifier), tristyrylphenol polyoxyethylene ether 13.2% (high molecular weight emulsifier), tristyrylphenol polyethylene glycol phosphate 0.5% (stabilizer), sodium polyoxyethylene fatty alcohol ether sulfate 0.5% (stabilizer), ethylene glycol 1.5% (antifreeze agent), Atplus TM UEP-100 2% (anti-evaporation agent), the balance is tap water.

[0058] The content of the stabilizer in Comparative Example 4 is not within the range of 2% to 5% of the present invention.

[0059] Comparative Example 1

[0060] Commercially available 10% cyfluthrin EC product (5% cyfluthrin and 5% cyfluthrin) ， Non-nano particle size.

[0061] Comparative Example 2

[0062] Commercially available 20% cyfluthrin EC product (10% cyfluthrin and 10% cyfluthrin) ， Non-nano particle size.

[0063] Comparative Example 3

[0064] Commercially available 25% cyfluthrin EC product (15% cyhalofop-butyl and 10% cyfluthrin), non-nanoparticle size.

[0065] Test Example 1 Physicochemical Properties and Stability Study

[0066] Particle size test: Dynamic light scattering method is used for testing. After diluting the sample, let it stand at room temperature for 5 hours (50 times dilution for air defense spray and 200 times dilution for conventional spray). Then take 1μL of sample and slowly add it to the sample pool to avoid bubbles. Each sample is measured 5 times, and the particle size (Z-average particle size) is the average of the five measurements.

[0067] Low temperature stability test: Take 20 mL of the sample and place it in an ampoule, and store it at 0±2℃ for 7 days. Take out the sample and return it to room temperature, and observe its state changes.

[0068] Thermal storage stability test: 20 mL of the sample was placed in an ampoule and stored at 54±2°C for 14 days. The sample was taken out and returned to room temperature, its state was observed, and the degradation rate of metamifop was detected by high performance liquid chromatography.

[0069] Evaporation test: The temperature of the constant temperature and humidity chamber was adjusted to 35°C and the humidity was set to 60% to simulate the summer environment. 10 mL of the sample was taken and dripped onto the leaf surface of the goosegrass with a pipette, and the initial weight was recorded. The leaves were placed in the constant temperature and humidity chamber for 30 minutes and the final weight was recorded. The evaporation rate (%) was calculated as (initial weight - final weight) / initial weight.

[0070] The microemulsions of Examples 1-4, Comparative Examples 1-4 and Control Examples 1-3 are all light yellow transparent liquids, which can be quickly dispersed in water to form transparent and uniform O / W emulsions after dilution. In addition, the particle size, low temperature stability and heat storage stability of these microemulsions were investigated, and the results are shown in Table 1.

[0071] Table 1

[0072]

[0073]

[0074] As can be seen from Table 1, the nano-microemulsions provided by Examples 1-4 of the present invention can remain in the nano-particle size range for a long time after dilution at the conventional pesticide application and aerial spraying concentration, which is significantly better than the commercially available emulsifiable concentrate products (Comparative Examples 1 to 3).

[0075] Comparative Example 1 (lacking a low molecular weight emulsifier) ​​is milky white after dilution, indicating that relying solely on a slower moving high molecular weight emulsifier cannot quickly reach the oil-water interface, resulting in an inability to effectively form small-sized oil droplets.

[0076] Comparative Example 2 (lacking a high molecular weight emulsifier) ​​was transparent and bluish after dilution, but soon turned milky white, indicating that only a low molecular weight emulsifier could not maintain the stability of the oil droplet interface for a long time, resulting in the agglomeration of oil droplets and an increase in particle size.

[0077] Comparative Example 3 (emulsifier content is not within the range of 20% to 25%) is transparent with a bluish glow after dilution, but gradually becomes translucent during standing, indicating that the combination of high molecular weight emulsifier and low molecular weight emulsifier cannot maintain interface stability for a long time when the content is insufficient, resulting in agglomeration of oil droplets.

[0078] After 14 days of hot storage, the color of Comparative Example 4 (the stabilizer content is not in the range of 2% to 5%) changed from light yellow to dark red. The test results showed that the decomposition rate of oxadiazine seriously exceeded the standard, indicating that when the amount of stabilizer added is insufficient, it is impossible to effectively prevent the hydrolysis reaction of oxadiazine at the oil-water interface and it cannot be used.

[0079] Test Example 2: Prevention Test

[0080] Examples 1-4, comparative examples 1-3 and control examples 1-3 were selected to conduct field control efficacy tests on weeds in rice fields.

[0081] The temperature during the test was 28-37°C, and the dosage of each sample was set as follows according to the total active ingredient (g / mu): the dosage of Examples 1-4 was 30g / mu and 40g / mu, and the dosage of Comparative Examples 1-3 was 40g / mu. The control group was set as the commercially available product oxazolidinone cyanamide EC, and the dosage of Comparative Examples 1-3 was 40g / mu.

[0082] The experiment set up 11 treatment groups, 3 control groups and 1 blank control group, each group was repeated 3 times, a total of 45 plots, arranged in random blocks. Leptochloa chinensis, Digitaria tangutica and Echinochloa chinensis were used as the test weeds, and the control effect was recorded 14 days and 28 days after application. The experimental results are shown in Table 2 (the control effect of the preparation with cyhalofop-butyl and metamifop-butyl as the active ingredients on weeds 14 days later) and Table 3 (the control effect of the preparation with cyhalofop-butyl and metamifop-butyl as the active ingredients on weeds 28 days later).

[0083] Plant control effect = (number of weeds in the blank control area - number of weeds in the treatment area) / number of weeds in the blank control area * 100%

[0084] Table 2

[0085]

[0086] Table 3

[0087]

[0088]

[0089] According to the results in Table 2 and Table 3:

[0090] The microemulsions provided by the present invention (Examples 1 to 4) show significantly superior control effects on weeds such as Leptochloa chinensis, Digitaria tangutica, and Echinochloa chinensis in a high temperature environment in summer within 14 days and 28 days after application. Even at a dosage of 30 g / mu of total active ingredients, the control effect of the microemulsion is still better than the control effect of commercially available emulsifiable concentrate products (Comparative Examples 1 to 3) at a dosage of 40 g / mu of total active ingredients, indicating that the nanoparticle size and the reduction in evaporation rate jointly improve the drug effect. Among them, Example 1 shows the best control effect at a dosage of 40 g / mu of total active ingredients. 14 days after application, the control effect on Leptochloa chinensis, Digitaria tangutica, Echinochloa chinensis and annual grass weeds reached 89.63%, 90.12%, 83.32% and 87.69% respectively; 28 days after application, the control effect was further improved to 92.33%, 95.8%, 89.49% and 92.54%. In contrast, the control effect of Comparative Example 1 (lacking low molecular weight emulsifier), Comparative Example 2 (lacking high molecular weight emulsifier) ​​and Comparative Example 3 (emulsifier content is not within the scope of the present invention) at a dosage of 40 g / mu of total active ingredients was significantly lower than that of Examples 1 to 4 (total active ingredients 40 g / mu), but was similar to the control effect of Examples 1 to 4 at a dosage of 30 g / mu. In addition, the particle size of Comparative Example 2 is similar to that of Control Example 1, and the evaporation rate is slower than that of Control Example 1. At a dosage of 40 g / mu of total active ingredient, its efficacy is significantly better than that of Control Example 1, which once again proves the joint influence of particle size and evaporation rate on the final control effect.

[0091] In summary, the microemulsion provided by the present invention has good dispersibility, small particle size, excellent storage stability and anti-evaporation, has excellent control effect on weeds such as Leptochloa chinensis, Digitaria tangutica, Echinochloa chinensis, etc., takes effect quickly, and is suitable for weed control in rice fields under high temperature conditions in summer.

Claims

1. A microemulsion containing cyhalofop-butyl and metamifop-butyl, which comprises, by mass percentage, 10% to 25% of active ingredient, 10% to 20% of solvent, 20% to 25% of emulsifier, 5% to 10% of cosurfactant, 2% to 5% of stabilizer, 0.5% to 2.5% of antifreeze agent, 1% to 3% of antievaporation agent, and the balance is water; The active ingredients are cyhalofop-butyl and metamifop-butyl; The emulsifier comprises a low molecular weight emulsifier with a molecular weight of <500 g / mol and a high molecular weight emulsifier with a molecular weight of >1500 g / mol.

2. The microemulsion containing cyhalofop-butyl and metamifop-butyl according to claim 1, characterized in that: In the emulsifier, the mass ratio of the low molecular weight emulsifier to the high molecular weight emulsifier is 1:(1.5-7.5).

3. The microemulsion containing cyhalofop-butyl and metamifop-butyl according to claim 1, characterized in that: The low molecular weight emulsifier is selected from one or a combination of sodium dodecylbenzene sulfonate, isomeric tridecanol polyoxyethylene ether, sodium dioctyl sulfonate succinate, fatty alcohol polyoxyethylene ether and alkyl glycoside; The HLB of the high molecular weight emulsifier is greater than 11, and is preferably one or more combinations of castor oil polyoxyethylene ether, propylene glycol block polyether, and tristyrylphenol polyoxyethylene ether.

4. The microemulsion containing cyhalofop-butyl and metamifop-butyl according to claim 3, characterized in that: The low molecular weight emulsifier is selected from one or a combination of sodium dodecylbenzene sulfonate, isomeric tridecanol polyoxyethylene ether and sodium dioctyl sulfonate succinate, and contains at least one anionic emulsifier; The high molecular weight emulsifier is selected from one or a combination of tristyrylphenol polyoxyethylene ether, propylene glycol block polyether, and castor oil polyoxyethylene ether.

5. The microemulsion containing cyhalofop-butyl and metamifop-butyl according to claim 1, characterized in that: The co-surfactant is selected from one or more combinations of ethanol, isobutanol, isopentanol, isooctyl alcohol, dimethyl sulfoxide, dimethylacetamide, and N-methylpyrrolidone.

6. The microemulsion containing cyhalofop-butyl and metamifop-butyl according to claim 1, characterized in that: The stabilizer includes tristyrylphenol polyethylene glycol phosphate and one or more combinations selected from sodium ethoxylated alkyl sulfate, sodium lauroyl sarcosinate or sodium fatty alcohol polyoxyethylene ether sulfate.

7. The microemulsion containing cyhalofop-butyl and metamifop-butyl according to claim 1, characterized in that: The antifreeze agent is selected from one or more combinations of glycerol, propylene glycol and ethylene glycol.

8. The microemulsion containing cyhalofop-butyl and metamifop-butyl according to claim 1, characterized in that: The anti-evaporation agent is selected from polyethylene glycol, glycerol, Atplus TM UEP-100, Hydravance TM 200. Synergen TM One or more combinations of OS.

9. The microemulsion containing cyhalofop-butyl and metamifop-butyl according to claim 1, characterized in that: The solvent is one or more selected from naphtha, cyclohexanone, xylene, isooctyl acetate, and ethylene glycol mono-n-butyl ether acetate.

10. The method for preparing the microemulsion containing cyhalofop-butyl and metamifop-butyl as claimed in any one of claims 1 to 9, characterized in that: Add the active ingredient, solvent and co-surfactant into a stirring kettle according to the formula, raise the temperature to 30-40°C, stir until the active ingredient is completely dissolved, then add the emulsifier, stabilizer, antifreeze agent and anti-evaporation agent in sequence, stir, and finally add the remaining amount of water and continue stirring to obtain the product.

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