Preparation process of pyrazosulfuron-ethyl water suspending agent

Abstract

The invention discloses a preparation process of a pyrazosulfuron-ethyl water suspending agent. The preparation process of the pyrazosulfuron-ethyl water suspending agent comprises the following steps: stirring and mixing the phenethyl phenol polyoxyethylene ether, the block polyether, the polyacrylate copolymer, the xanthan gum, the magnesium aluminum silicate, the preservative, the composite slow-release particles and the water for 30 minutes under the condition that the rotating speed is 2000rpm; adding a defoaming agent, carrying out primary sanding until the particle size D90 of the material is less than 5 microns, and carrying out secondary sanding until the particle size D98 of the material is less than 0.7 microns; and filling to obtain the pyrazosulfuron-ethyl water suspending agent. Compared with the prior art, by adopting a method of compounding the sustained-release particles and matching with the auxiliaries, main medicinal components can be protected from being influenced by the outside, on the other hand, the sustained-release particles and the plant rhizomes have a good combination effect, and the administration effect and the durability of the medicinal effect are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of suspending agents, and particularly to a preparation process of pyrazosulfuron-ethyl aqueous suspension concentrate. Background Art

[0002] An aqueous suspension concentrate is a pesticide preparation mainly composed of a water-insoluble solid active ingredient and related auxiliaries, and these components form a highly dispersed viscous suspension in water. The solid pesticide technical material is evenly dispersed in water in the form of particles below 4 microns, having advantages such as high suspension rate, good dispersibility, good spreading property, high biological activity, good drug efficacy, safe and convenient use and storage and transportation, and low cost. Compared with oil-based suspension concentrates, aqueous suspension concentrates have the superiority of not using any organic solvents, generating no dust, and being safe for operators, users and the environment. However, the physical stability of suspension concentrates is relatively poor, especially prone to stratification and precipitation during storage, and some even agglomerate, affecting the use.

[0003] According to the Chinese pesticide toxicity classification standard, pyrazosulfuron-ethyl is a low-toxicity, selective systemic herbicide, which is mainly absorbed through the roots, rapidly transferred in the weed plant body, inhibits growth, and the weeds gradually die. Pyrazosulfuron-ethyl can also be rapidly absorbed by the young buds, roots and stems and leaves of weeds and rapidly conduct in the plant body. It mainly inhibits the activity of acetolactate synthase in plant cells, hinders the synthesis of essential amino acids, so that the buds and roots of weeds quickly stop growing and developing, and the whole plant withers. Rice can decompose this agent and has almost no impact on rice growth. The drug efficacy is stable, the safety is high, and the effective period is 25-35 days. The applicable scope includes rice seedling fields, direct seeding fields, transplanted fields, etc. It can control annual and perennial broad-leaved weeds and Cyperaceae weeds, such as Cyperus difformis, Cyperus serotinus, Scirpus juncoides, Monochoria vaginalis, Oenanthe javanica, Rotala indica, Sagittaria trifolia, Potamogeton distinctus, Lemna minor, Eclipta prostrata.

[0004] CN102077834A discloses a microcapsule aqueous suspension concentrate for controlling paddy weeds and a preparation method thereof. By adding microcapsules of a combination of pyrazosulfuron-ethyl and pretilachlor, the action time is extended, and the closed weeding time is more than 1 time longer than that of the conventional dosage form, reaching about 75 days. However, the adhesion effect of the microcapsule aqueous suspension concentrate provided by this invention to plant roots and rhizomes is poor and it is easily washed away by rain, which is not conducive to its weeding effect.

[0005] CN114747589A discloses a dispersible oil suspension concentrate containing nicosulfuron and atrazine and a preparation method thereof. The oil suspension prepared from nicosulfuron, atrazine, calcium dodecylbenzenesulfonate, triphenylvinylphenol polyoxyethylene ether, alkylphenol polyoxyethylene ether, thickener, methyl oleate, adsorbent has a more persistent drug efficacy. However, the oil suspension concentrate provided by this invention has the problem of a relatively short storage duration, which will have an adverse impact on the weeding effect. Summary of the Invention

[0006] In view of the above defects of the prior art, the object of the present invention is to provide a preparation process of pyrazosulfuron-ethyl aqueous suspension concentrate. The aqueous suspension concentrate prepared by this process has good stability, is not easily washed by rain to the deep layer of the soil, improves the persistence of the drug effect, and has the characteristics of thorough weeding, less dosage, and the use of green and environmentally friendly solvents, and can prevent and control annual and perennial broad-leaved weeds and Cyperaceae weeds at one time.

[0007] To achieve the above object, the present invention provides a preparation process of pyrazosulfuron-ethyl aqueous suspension concentrate, including the following steps:

[0008] Stir and mix pyrazosulfuron-ethyl, phenethylphenol polyoxyethylene ether, block polyether, polyacrylate copolymer, xanthan gum, magnesium aluminum silicate, preservative and water at a rotation speed of 1000 - 3000 rpm for 20 - 40 min; after adding an antifoaming agent, perform primary sanding until the particle size D90 of the material is < 5 μm, and perform secondary sanding until the particle size D98 of the material is < 0.7 μm; fill into containers to obtain the pyrazosulfuron-ethyl aqueous suspension concentrate;

[0009] Or, stir and mix phenethylphenol polyoxyethylene ether, block polyether, polyacrylate copolymer, xanthan gum, magnesium aluminum silicate, preservative, composite slow-release granules and water at a rotation speed of 1000 - 3000 rpm for 20 - 40 min; after adding an antifoaming agent, perform primary sanding until the particle size D90 of the material is < 5 μm, and perform secondary sanding until the particle size D98 of the material is < 0.7 μm; fill into containers to obtain the pyrazosulfuron-ethyl aqueous suspension concentrate;

[0010] Preferably, by weight percentage, each raw material component includes:

[0011] 20 - 30% of pyrazosulfuron-ethyl, 2 - 4% of phenethylphenol polyoxyethylene ether, 1 - 2% of block polyether, 1 - 3% of polyacrylate copolymer, 0.1 - 0.3% of xanthan gum, 0.5 - 1% of magnesium aluminum silicate, 0.1 - 0.5% of preservative, 0.1 - 0.5% of antifoaming agent, and the balance is water;

[0012] Or, 20 - 30% of composite slow-release granules, 2 - 4% of phenethylphenol polyoxyethylene ether, 1 - 2% of block polyether, 1 - 3% of polyacrylate copolymer, 0.1 - 0.3% of xanthan gum, 0.5 - 1% of magnesium aluminum silicate, 0.1 - 0.5% of preservative, 0.1 - 0.5% of antifoaming agent, and the balance is water.

[0013] Preferably, the preservative is selected from at least one of sodium benzoate, 1,2-benzisothiazolin-3-one, benzoic acid, p-hydroxybenzaldehyde, and isothiazolinone.

[0014] Preferably, the antifoaming agent is selected from at least one of silicone antifoaming agents, mineral oil antifoaming agents, and higher alcohol antifoaming agents.

[0015] The phenethylphenol polyoxyethylene ether is a non-ionic surfactant that can reduce the surface tension of water, help the active ingredients to be better distributed on the crop leaves, and improve the efficacy of the pesticide.

[0016] The block polyether can, due to its surfactant properties, help maintain the uniform suspension state of the pesticide in the liquid in the pesticide suspension concentrate.

[0017] The polyacrylate copolymer is usually used as a thickener, which can increase the viscosity of the formulation, make it easier to adhere to the plant surface, and extend the action time of the active ingredient.

[0018] The xanthan gum is a natural high-molecular polysaccharide used as a thickener, which can improve the fluidity and stability of the formulation and at the same time provide good suspension performance.

[0019] The magnesium aluminum silicate, as an adjuvant, can improve the suspension stability of the formulation, reduce precipitation, and help maintain the uniformity of the product.

[0020] Preferably, the preparation method of the composite slow-release granules comprises the following steps, by weight:

[0021] S1. Place 1-3 parts of carbon material at 700-900 °C for pyrolysis for 1-3 h. After cooling, wash it with 0.1 mol / L HCl solution until neutral, and then soak it in 1-5 parts of 1-3 mol / L NaOH aqueous solution, and oscillate at a constant temperature of 60-80 °C for 3-6 h, filter and wash with water until the filtrate is neutral; place the filter cake in an oven at 80-100 °C for drying for 4-6 h to obtain modified activated carbon.

[0022] S2. Mix 5-15 parts of pyrazosulfuron-ethyl with 1-10 parts of acetone, then add 1-5 parts of the modified activated carbon obtained in the above step S1, stir at 40-60 °C for 2-4 h, and dry at 60-80 °C for 2-4 h to obtain the pyrazosulfuron-ethyl complex.

[0023] S3. At 40-70 °C, disperse 1-5 parts of chitosan in 10-50 parts of 1-3 mol / L NaOH aqueous solution, and mix and stir for 1-3 h; then add 10-15 parts of the modifier, heat to 60-80 °C, mix and stir for 6-8 h to obtain the mixed solution B, adjust the mixed solution B to neutral with 0.1 mol / L HCl solution, centrifuge at 4000-6000 rpm for 10-20 min, collect the precipitate, then wash it with water 3-5 times, and dry at 40-60 °C for 2-4 h to obtain the modified chitosan.

[0024] S4. Disperse 1 - 10 parts of bentonite sufficiently in 50 - 100 parts of water, add 5 - 15 parts of the modified chitosan obtained in the above step S3, and mix and stir at a constant temperature of 60 - 80 °C for 4 - 8 h; then add 1 - 5 parts of the pyrazosulfuron - ethyl complex obtained in the above step S2, mix and stir for 1 - 2 h, then centrifuge at 4000 - 6000 rpm for 10 - 20 min. After centrifugation, collect the precipitate and dry it at 40 - 60 °C to obtain the composite slow - release granules.

[0025] Preferably, the steps of step S1 can also be: Mix 0.5 - 1 part of FeCl3·6H2O, 0.3 - 0.8 part of FeCl2·4H2O with 5 - 10 parts of water to obtain a mixed solution A; Add 1 - 3 parts of carbon material to 3 - 8 parts of the above - mentioned mixed solution A, soak at 70 - 90 °C for 1 - 3 h; Then add 0.5 - 2 parts of NaOH solid and continue to stir at 70 - 90 °C for 2 - 4 h, filter, and wash the solid with water 3 - 5 times, and dry at 70 - 90 °C for 6 - 8 h to obtain the modified carbon material; Mix 1 - 3 parts of the modified carbon material and 1 - 10 parts of 40 - 60 wt% zinc chloride aqueous solution at room temperature and stir for 12 - 16 h, then dry at 70 - 90 °C for 6 - 8 h; Then place it in a pyrolysis furnace at 700 - 900 °C for 1 - 3 h, cool, wash it with 0.1 mol / L HCl solution until neutral, then soak it with 1 - 5 parts of 1 - 3 mol / L NaOH aqueous solution, oscillate at a constant temperature of 60 - 80 °C for 3 - 6 h, filter and wash it with water until the filtrate is neutral; Place the filter cake in an oven and dry it at 80 - 100 °C for 4 - 6 h to obtain the modified activated carbon.

[0026] Preferably, the carbon material in step S1 is selected from at least one of bamboo, corn straw, sorghum straw, wheat straw, rice straw, soybean straw, cotton straw, and sugarcane bagasse.

[0027] Preferably, the modifier in step S3 is selected from one of 3 - chloro - 2 - hydroxypropyl trimethyl ammonium chloride, methacryloyloxyethyl trimethyl ammonium chloride, and dioctyldimethyl ammonium chloride.

[0028] The present invention also provides a pyrazosulfuron - ethyl aqueous suspension agent prepared by the above process.

[0029] In the process of preparing the composite slow - release granules of the present invention, modified activated carbon is introduced. By magnetizing the carbon material and then carbonizing the magnetized carbon material, modified activated carbon is obtained. Magnetizing the carbon material of the modified activated carbon before carbonization and then carbonizing it can increase the specific surface area of the activated carbon and enhance its adsorption performance; Using 0.1 mol / L HCl solution can remove heavy metal ions; Soaking with NaOH aqueous solution can perform hydrophobic modification on the activated carbon and improve its suspension effect in water.

[0030] The inventor of the present invention has found that the solubility of pyrazosulfuron in water is poor, and its chemical structure may be affected in water when it is prepared into a water suspension in the presence of other compounds. Modified activated carbon has strong selective adsorption for it, can adsorb and protect it, and can increase its structural stability through the action of hydrogen bonds or electron bonds. This is because hydrogen bonds may form between the protonated amino group of pyrazosulfuron and the oxygen-containing functional groups on the surface of modified activated carbon. In addition, pyrazosulfuron contains benzene and aromatic heterocyclic groups, has strong electron absorption ability and specific π-electron acceptor properties, and may also bind to modified activated carbon through π-π electron donor-acceptor interactions.

[0031] Advantages of the present invention:

[0032] Compared with the prior art, the present invention introduces composite slow-release particles, which can effectively improve the herbicidal effect of the pyrazosulfuron aqueous suspension. The main body of the composite slow-release particles is a modified chitosan-bentonite complex. Modified chitosan can bind to the negatively charged sites on the surface of bentonite lamellae through ion exchange reactions, which not only enhances the hydrophobicity of the bentonite surface but also can form hydrogen bonds, van der Waals forces, and possibly a small number of covalent bonds with plant roots and rhizomes to enhance its binding ability to the plant surface, and has a good slow-release effect. Loading the pyrazosulfuron complex can further improve the persistence of the drug effect.

[0033] Compared with the prior art, the method of the present invention using composite slow-release particles combined with additives can protect the main active ingredient of the drug from external influences. On the other hand, the slow-release particles and plant roots and rhizomes have a good binding effect, improving the drug delivery effect and the persistence of the drug effect. Specific embodiments

[0034] The parameters and sources of some raw materials in the embodiments of the present invention are as follows:

[0035] Phenethylphenol polyoxyethylene ether, CAS No.: 99734-09-5.

[0036] Block polyether, model Ethylan NS-500LQ, brand: Nouryon; a non-ionic hydroxy poly(ethylene oxide) block copolymer with an EO / PO ratio of 1:1.71 and a pH value of 6.5 - 7.5.

[0037] Polyacrylate copolymer, CAS No.: 25035-69-2.

[0038] 1,2-Benzisothiazolin-3-one, CAS No.: 2634-33-5.

[0039] Organosilicon defoamer: model SAG1572, brand: Momentive.

[0040] Chitosan, medium viscosity, 200 - 400 mPa.s, sourced from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0041] Bentonite, 200 mesh.

[0042] Example 1

[0043] A preparation process of pyrazosulfuron - ethyl aqueous suspension concentrate, comprising the following steps:

[0044] Mix 30 g of pyrazosulfuron - ethyl, 3 g of phenethylphenol polyoxyethylene ether, 1 g of block polyether, 2 g of polyacrylate copolymer, 0.2 g of xanthan gum, 0.7 g of magnesium aluminum silicate, 0.3 g of 1,2 - benzisothiazolin - 3 - one and 62.5 g of water under stirring at 2000 rpm for 30 min; after adding 0.3 g of silicone defoamer, perform primary sanding until the particle size D90 of the material < 5 μm, and perform secondary sanding until the particle size D98 of the material < 0.7 μm; fill into containers to obtain the pyrazosulfuron - ethyl aqueous suspension concentrate.

[0045] Example 2

[0046] A preparation process of pyrazosulfuron - ethyl aqueous suspension concentrate, comprising the following steps:

[0047] Mix 3 g of phenethylphenol polyoxyethylene ether, 1 g of block polyether, 2 g of polyacrylate copolymer, 0.2 g of xanthan gum, 0.7 g of magnesium aluminum silicate, 0.3 g of 1,2 - benzisothiazolin - 3 - one, 30 g of composite slow - release granules and 62.5 g of water under stirring at 2000 rpm for 30 min; after adding 0.3 g of silicone defoamer, perform primary sanding until the particle size D90 of the material < 5 μm, and perform secondary sanding until the particle size D98 of the material < 0.7 μm; fill into containers to obtain the pyrazosulfuron - ethyl aqueous suspension concentrate.

[0048] The preparation method of the composite slow - release granules is as follows:

[0049] S1. Dissolve 8 g of FeCl3·6H2O and 4 g of FeCl2·4H2O in 60 g of water to prepare solution A; add 20 g of corn straw to 50 g of the above - mentioned solution A and soak at 80 °C for 3 h; add 10 g of solid NaOH and continue stirring at 80 °C for 3 h, wash with water 3 times, and dry at 80 °C for 8 h to obtain modified carbon material; stir - mix 20 g of modified carbon material and 30 g of 50 wt% zinc chloride aqueous solution at room temperature for 16 h, dry at 80 °C for 8 h, then pyrolyze at 800 °C for 2 h, cool, wash with 0.1 mol / L HCl solution until neutral, then soak with 30 g of 2 mol / L NaOH aqueous solution, perform constant - temperature oscillation at 60 °C for 3 h, filter, and wash with water until the filtrate is neutral; place the filter cake in an oven and dry at 80 °C for 6 h to obtain modified activated carbon;

[0050] S2, dissolving 100 g of pyrazosulfuron-methyl in 50 g of acetone, then adding 10 g of the modified activated carbon obtained in step S1 above, stirring at 50° C. for 4 h, and drying at 70° C. for 3 h to obtain a pyrazosulfuron-methyl complex;

[0051] S3. Disperse 20 g of chitosan in 200 g of 1 mol / L NaOH aqueous solution at 60°C, mix and stir for 2 h; then add 200 g of 3-chloro-2-hydroxypropyltrimethylammonium chloride, heat to 70°C, stir for 7 h to obtain mixed solution B, adjust mixed solution B to neutrality with 0.1 mol / L HCl solution, centrifuge at 6000 rpm for 20 min, collect precipitates, wash with water 3 times, and dry at 60°C for 4 h to obtain modified chitosan;

[0052] S4, 50g of bentonite was fully dispersed in 500g of water, 100g of modified chitosan was added, and the mixture was stirred and reacted at a constant temperature of 70°C for 5h, and then 30g of the pyrazosulfuron-methyl complex obtained in the above step S2 was added, and the mixture was stirred and reacted for 2h, and then centrifuged at 6000rpm for 20min. The precipitate after centrifugation was dried at 60°C to obtain composite sustained-release particles.

[0053] Example 3

[0054] A preparation process of a pyrazosulfuron-methyl aqueous suspension, which is different from Example 2 in that the preparation method of the composite sustained-release granules comprises the following steps:

[0055] S1. Dissolve 8g FeCl3·6H2O and 4g FeCl2·4H2O in 60g water to prepare solution A; add 20g corn stalks to 50g of the above solution A and soak at 80℃ for 3h; add 10g NaOH solid and continue stirring at 80℃ for 3h, rinse with water 3 times, and dry at 80℃ for 8h to obtain modified carbon material; 20g modified carbon material and 30g 50wt% zinc chloride aqueous solution are stirred and mixed at room temperature for 16h, dried at 80℃ for 8h, and then pyrolyzed at 800℃ for 2h, washed with 0.1mol / L HCl solution until neutral after cooling, and then soaked with 30g 2mol / L NaOH aqueous solution, shaken at 60℃ for 3h, filtered and rinsed with water until the filtrate is neutral; the filter cake is dried in an oven at 80℃ for 6h to obtain modified activated carbon;

[0056] S2, dissolving 100 g of pyrazosulfuron-methyl in 50 g of acetone, then adding 10 g of the modified activated carbon obtained in step S1 above, stirring at 50° C. for 4 h, and drying at 70° C. for 3 h to obtain a pyrazosulfuron-methyl complex;

[0057] S3. At 60 °C, disperse 20 g of chitosan in 200 g of 1 mol / L aqueous NaOH solution, mix and stir for 2 h; then add 200 g of methacryloyloxyethyl trimethyl ammonium chloride, heat to 70 °C, stir for 7 h to obtain a mixed solution B, adjust the mixed solution B to neutral with 0.1 mol / L HCl solution, centrifuge at 6000 rpm for 20 min, collect the precipitate, then wash it with water three times, and dry it at 60 °C for 4 h to obtain modified chitosan;

[0058] S4. Disperse 50 g of bentonite thoroughly in 500 g of water, add 100 g of modified chitosan, stir and react at a constant temperature of 70 °C for 5 h, then add 30 g of the pyrazosulfuron-ethyl complex obtained in the above step S2, stir and react for 2 h, then centrifuge at 6000 rpm for 20 min, and dry the centrifuged precipitate at 60 °C to obtain the composite slow-release granules.

[0059] Example 4

[0060] A preparation process of a pyrazosulfuron-ethyl aqueous suspension agent, which is different from Example 2 in that the preparation method of the composite slow-release granules comprises the following steps:

[0061] S1. Dissolve 8 g of FeCl3·6H2O and 4 g of FeCl2·4H2O in 60 g of water to prepare solution A; add 20 g of corn straw to 50 g of the above solution A and soak it at 80 °C for 3 h; add 10 g of solid NaOH and continue to stir at 80 °C for 3 h, wash it with water three times, and dry it at 80 °C for 8 h to obtain modified carbon material; stir and mix 20 g of modified carbon material and 30 g of 50 wt% zinc chloride aqueous solution at room temperature for 16 h, dry it at 80 °C for 8 h, then pyrolyze it at 800 °C for 2 h, cool it, wash it to neutral with 0.1 mol / L HCl solution, then soak it with 30 g of 2 mol / L NaOH aqueous solution, oscillate at a constant temperature of 60 °C for 3 h, filter, and wash it with water until the filtrate is neutral; dry the filter cake in an oven at 80 °C for 6 h to obtain modified activated carbon;

[0062] S2. Dissolve 100 g of pyrazosulfuron-ethyl in 50 g of acetone, then add 10 g of the modified activated carbon obtained in the above step S1, stir at 50 °C for 4 h, and dry at 70 °C for 3 h to obtain the pyrazosulfuron-ethyl complex;

[0063] S3. At 60 °C, disperse 20 g of chitosan in 200 g of 1 mol / L aqueous NaOH solution, mix and stir for 2 h; then add 200 g of dioctyldimethylammonium chloride, heat to 70 °C, stir for 7 h to obtain a mixed solution B, adjust the mixed solution B to neutral with 0.1 mol / L HCl solution, centrifuge at 6000 rpm for 20 min, collect the precipitate, then wash it with water three times, and dry it at 60 °C for 4 h to obtain modified chitosan;

[0064] S4. Disperse 50 g of bentonite thoroughly in 500 g of water, add 100 g of modified chitosan, stir and react at a constant temperature of 70 °C for 5 h, then add 30 g of the pyrazosulfuron-ethyl complex obtained in the above step S2, stir and react for 2 h, then centrifuge at 6000 rpm for 20 min, and dry the precipitate after centrifugation at 60 °C to obtain the composite slow-release granules.

[0065] Example 5

[0066] A preparation process of a pyrazosulfuron-ethyl aqueous suspension agent, which is different from Example 2 in that the preparation method of the composite slow-release granules includes the following steps:

[0067] S1. Place 20 g of corn straw at 800 °C for pyrolysis for 2 h, cool it, wash it with 0.1 mol / L HCl solution until neutral, then soak it with 30 g of 2 mol / L NaOH aqueous solution, oscillate at a constant temperature of 60 °C for 3 h, filter and wash it with water until the filtrate is neutral; dry the filter cake in an oven at 80 °C for 6 h to obtain modified activated carbon.

[0068] S2. Dissolve 100 g of pyrazosulfuron-ethyl in 50 g of acetone, then add 10 g of the modified activated carbon obtained in the above step S1, stir at 50 °C for 4 h, and dry at 70 °C for 3 h to obtain the pyrazosulfuron-ethyl complex.

[0069] S3. At 60 °C, disperse 20 g of chitosan in 200 g of 1 mol / L NaOH aqueous solution, mix and stir for 2 h; then add 200 g of dioctyldimethylammonium chloride, heat to 70 °C, stir for 7 h to obtain mixture B, adjust mixture B to neutral with 0.1 mol / L HCl solution, centrifuge at 6000 rpm for 20 min, collect the precipitate, then wash it 3 times with water, and dry at 60 °C for 4 h to obtain modified chitosan.

[0070] S4. Disperse 50 g of bentonite thoroughly in 500 g of water, add 100 g of modified chitosan, stir and react at a constant temperature of 70 °C for 5 h, then add 30 g of the pyrazosulfuron-ethyl complex obtained in the above step S2, stir and react for 2 h, then centrifuge at 6000 rpm for 20 min, and dry the precipitate after centrifugation at 60 °C to obtain the composite slow-release granules.

[0071] Comparative Example 1

[0072] A preparation process of a pyrazosulfuron-ethyl oil suspension agent includes the following steps:

[0073] Mix 30 g of pyrazosulfuron-ethyl, 3 g of phenethylphenol polyoxyethylene ether, 1 g of block polyether, 2 g of polyacrylate copolymer, 0.2 g of xanthan gum, 0.7 g of magnesium aluminum silicate, 0.3 g of 1,2-benzisothiazolin-3-one and 62.5 g of methyl oleate under the condition of a stirring speed of 2000 rpm for 30 min; add 0.3 g of silicone defoamer and then grind it in a first stage until the particle size D90 of the material is <5 μm, and grind it in a second stage until the particle size D98 of the material is <0.7 μm; fill it into containers, and thus obtain the pyrazosulfuron-ethyl oil suspension concentrate.

[0074] Test Example 1

[0075] Test on the control effect of weeds

[0076] Adopt the method in "GB / T17980.127-2004 Pesticide field efficacy test guidelines (part 2) - Part 127: Herbicides - Spray between rows to control weeds in crop fields" to determine the control effects of the pyrazosulfuron-ethyl water suspension concentrates prepared in Examples 1-5 of the present invention and the pyrazosulfuron-ethyl oil suspension concentrate prepared in Comparative Example 1. Set two groups of experimental groups. One group is that Examples 1-5 and Comparative Example 1 do not have simulated rainfall; the other group is that Examples 1-5 and Comparative Example 1 have simulated rainfall 1 h after dosing. The uniformity of the simulated rainfall conforms to "GB / T50085-2007 Irrigation engineering technical code", and the rainfall is 30.0 mm.

[0077] Test method: Investigate the weed base number before applying the medicine; conduct the first investigation 10 days after applying the medicine; conduct the second investigation 20 days after applying the medicine; conduct the third investigation 50 days after applying the medicine; calculate the plant control effect according to the investigation results. The higher the value of the plant control effect, the better the effect; the calculation formula of the plant control effect is as follows:

[0078] E(%) = (C - T) / C × 100%

[0079] In the formula: E is the plant control effect; C is the number of weed plants in the control area; T is the number of weed plants in the treatment area;

[0080] The test results are shown in Table 1.

[0081] Table 1 Plant control effect

[0082]

[0083] It can be found by comparing Examples 1, 4, 5 and Comparative Example 1 that the plant control effect of Example 4 is the highest and the duration of the drug effect is long. The possible reason is that modified activated carbon is used in Example 4 to protect pyrazosulfuron-ethyl. The modified activated carbon has selective adsorption for pyrazosulfuron-ethyl and a high adsorption efficiency, and then a double slow-release structure is formed through the protection of the modified chitosan-bentonite structure, thereby improving the duration of the drug effect.

[0084] By comparing Examples 2 - 4, it can be found that the plant control efficacy of Example 4 is high both before and after rainfall, indicating that the influence of rainwater on it is small. The possible reason is that the special structure formed by chitosan - bentonite modified with dioctyldimethylammonium chloride in Example 4 interacts with the groups of plant roots and rhizomes through hydrogen bonds or ionic bonds, causing the slow - release granules to adhere to the roots and rhizomes of weeds.

[0085] Test Example 2

[0086] Test on the degradation rate of pyrazosulfuron - ethyl

[0087] The pyrazosulfuron - ethyl aqueous suspension prepared in Example 1, Example 4, and Example 5 and the pyrazosulfuron - ethyl oil suspension prepared in Comparative Example 1 were stored at 65 °C for 14 days respectively, and then the content of pyrazosulfuron - ethyl in each example and comparative example was tested by high - performance liquid chromatography (HPLC). Among them, the chromatographic conditions were as follows: the chromatographic column was Agilent Eclipse XDB - C18 (250 mm×4.6 mm, 5 μm); the mobile phase was acetonitrile (A) - 0.1% phosphoric acid aqueous solution (B); the detection wavelength was 254 nm, and the column temperature was 25 °C. Take 5 mL of the supernatant of the samples of Example 1, Example 4, Example 5, and Comparative Example 1 just prepared, dissolve it with the mobile phase, filter, and take the subsequent filtrate as the test solution to test the content of pyrazosulfuron - ethyl before heat storage of the above samples; take 5 mL of the supernatant of the samples of the above examples and comparative examples stored at 65 °C for 14 days, dissolve it with the mobile phase, filter, and take the subsequent filtrate as the test solution to test the content of pyrazosulfuron - ethyl after heat storage of the above samples. Calculate the degradation rate of pyrazosulfuron - ethyl according to the test results. The lower the degradation rate value, the better the effect. The formula for calculating the degradation rate is as follows:

[0088] S0(%)=(S1 - S2) / S1×100%

[0089] In the formula, S0 is the degradation rate of pyrazosulfuron - ethyl; S1 is the content of pyrazosulfuron - ethyl before heat storage; S2 is the content of pyrazosulfuron - ethyl after heat storage. The results are shown in Table 2.

[0090] Table 2 Degradation rate of pyrazosulfuron - ethyl

[0091] Number / Item Drop Rate (%) Example 1 22.27 Example 4 5.67 Example 5 12.93 Comparative Example 1 23.15

[0092] By comparing before and after heat storage of Example 1, Example 4, Example 5, and Comparative Example 1, it can be found that the change in content of Example 4 is the smallest, indicating that the slow - release granules have a better protective effect on pyrazosulfuron - ethyl. The possible reason is that the modified activated carbon can selectively adsorb pyrazosulfuron - ethyl to form a complex, and the modified chitosan - bentonite structure performs a secondary adsorption on the complex to form slow - release granules with a double - protection structure, thereby reducing the influence of the external environment on pyrazosulfuron - ethyl.

[0093] Test Example 3

[0094] Table 3 Quality Standards

[0095]

Claims

1. A preparation process of pyrazosulfuron-ethyl aqueous suspension concentrate, characterized in that: It includes the following steps: Mix pyrazosulfuron-ethyl, phenethylphenol polyoxyethylene ether, block polyether, polyacrylate copolymer, xanthan gum, magnesium aluminum silicate, preservative and water under the condition of a rotation speed of 1000 - 3000 rpm for 20 - 40 min; add an antifoaming agent and then perform primary sanding until the particle size D90 of the material is < 5 μm, and perform secondary sanding until the particle size D98 of the material is < 0.7 μm; fill into containers to obtain the pyrazosulfuron-ethyl aqueous suspension concentrate. Or, mix phenethylphenol polyoxyethylene ether, block polyether, polyacrylate copolymer, xanthan gum, magnesium aluminum silicate, preservative, composite sustained-release particles and water under the condition of a rotation speed of 1000 - 3000 rpm for 20 - 40 min; add an antifoaming agent and then perform primary sanding until the particle size D90 of the material is < 5 μm, and perform secondary sanding until the particle size D98 of the material is < 0.7 μm; fill into containers to obtain the pyrazosulfuron-ethyl aqueous suspension concentrate.

2. The preparation process of a pyrazosulfuron-ethyl aqueous suspension agent according to claim 1, characterized in that, By weight percentage, each raw material component includes: 20 - 30% of pyrazosulfuron-ethyl, 2 - 4% of phenethylphenol polyoxyethylene ether, 1 - 2% of block polyether, 1 - 3% of polyacrylate copolymer, 0.1 - 0.3% of xanthan gum, 0.5 - 1% of magnesium aluminum silicate, 0.1 - 0.5% of preservative, 0.1 - 0.5% of antifoaming agent, and the balance is water; Or, 20 - 30% of composite sustained-release particles, 2 - 4% of phenethylphenol polyoxyethylene ether, 1 - 2% of block polyether, 1 - 3% of polyacrylate copolymer, 0.1 - 0.3% of xanthan gum, 0.5 - 1% of magnesium aluminum silicate, 0.1 - 0.5% of preservative, 0.1 - 0.5% of antifoaming agent, and the balance is water.

3. The preparation process of a pyrazosulfuron-ethyl aqueous suspension concentrate as claimed in claim 1 or 2, characterized in that: The preservative is selected from at least one of sodium benzoate, 1,2-benzisothiazolin-3-one, benzoic acid, p-hydroxybenzaldehyde, and isothiazolinone.

4. The preparation process of a pyrazosulfuron-ethyl aqueous suspension concentrate according to claim 1 or 2, characterized in that: The antifoaming agent is selected from at least one of silicone antifoaming agents, mineral oil antifoaming agents, and higher alcohol antifoaming agents.

5. The preparation process of a pyrazosulfuron-ethyl aqueous suspension concentrate according to claim 1 or 2, characterized in that, The preparation method of the said composite sustained-release particles includes the following steps, by weight parts: S1. Place 1 - 3 parts of carbon material at 700 - 900 °C for pyrolysis for 1 - 3 h, cool and wash with 0.1 mol / L HCl solution until neutral, then soak with 1 - 5 parts of 1 - 3 mol / L NaOH aqueous solution, keep it at 60 - 80 °C for constant-temperature oscillation for 3 - 6 h, filter and wash with water until the filtrate is neutral; place the filter cake in an oven at 80 - 100 °C for drying for 4 - 6 h to obtain modified activated carbon. S2. Mix 5 - 15 parts of pyrazosulfuron-ethyl with 1 - 10 parts of acetone, then add 1 - 5 parts of the modified activated carbon obtained in the above step S1, stir at 40 - 60 °C for 2 - 4 h, and dry at 60 - 80 °C for 2 - 4 h to obtain the pyrazosulfuron-ethyl complex. S3. At 40 - 70 °C, disperse 1 - 5 parts of chitosan in 10 - 50 parts of 1 - 3 mol / L aqueous NaOH solution, mix and stir for 1 - 3 h; then add 10 - 15 parts of the modifier, heat to 60 - 80 °C, mix and stir for 6 - 8 h to obtain mixture B. Adjust mixture B to neutral with 0.1 mol / L HCl solution, centrifuge at 4000 - 6000 rpm for 10 - 20 min, collect the precipitate, then wash it with water 3 - 5 times and dry it at 40 - 60 °C for 2 - 4 h to obtain modified chitosan; S4. Disperse 1 - 10 parts of bentonite fully in 50 - 100 parts of water, add 5 - 15 parts of the modified chitosan obtained in step S3 above, mix and stir at a constant temperature of 60 - 80 °C for 4 - 8 h; then add 1 - 5 parts of the pyrazosulfuron - ethyl complex obtained in step S2 above, mix and stir for 1 - 2 h, then centrifuge at 4000 - 6000 rpm for 10 - 20 min. After centrifugation, collect the precipitate and dry it at 40 - 60 °C to obtain the composite slow - release granules.

6. The preparation process of the pyrazosulfuron-ethyl aqueous suspension agent according to claim 5, characterized in that: The steps of step S1 can also be: Mix 0.5 - 1 part of FeCl₃·6H₂O, 0.3 - 0.8 part of FeCl₂·4H₂O with 5 - 10 parts of water to obtain mixed solution A; Add 1 - 3 parts of carbon material to 3 - 8 parts of the above - mentioned mixed solution A, soak at 70 - 90 °C for 1 - 3 h; then add 0.5 - 2 parts of NaOH solid and continue to stir at 70 - 90 °C for 2 - 4 h, filter, wash the solid with water 3 - 5 times, and dry at 70 - 90 °C for 6 - 8 h to obtain modified carbon material; Mix 1 - 3 parts of the modified carbon material and 1 - 10 parts of 40 - 60 wt% zinc chloride aqueous solution at room temperature and stir for 12 - 16 h, then dry at 70 - 90 °C for 6 - 8 h; then place it in a pyrolysis furnace at 700 - 900 °C for 1 - 3 h, cool it, wash it to neutral with 0.1 mol / L HCl solution, then soak it with 1 - 5 parts of 1 - 3 mol / L aqueous NaOH solution, oscillate at a constant temperature of 60 - 80 °C for 3 - 6 h, filter and wash it with water until the filtrate is neutral; Place the filter cake in an oven and dry it at 80 - 100 °C for 4 - 6 h to obtain modified activated carbon.

7. The preparation process of the pyrazosulfuron-ethyl aqueous suspension agent according to claim 5 or 6, characterized in that: In step S1, the carbon material is selected from at least one of bamboo, corn straw, sorghum straw, wheat straw, rice straw, soybean straw, cotton straw, and sugarcane bagasse.

8. The preparation process of the pyrazosulfuron-ethyl aqueous suspension agent according to claim 5, characterized in that: In step S3, the modifier is selected from one of 3 - chloro - 2 - hydroxypropyl trimethyl ammonium chloride, methacryloyloxyethyl trimethyl ammonium chloride, and dioctyldimethyl ammonium chloride.

9. A pyrazosulfuron-ethyl aqueous suspension concentrate, characterized in that: Prepared by the process according to any one of claims 1 - 8.

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