Preparation process and application of tebuconazole suspending agent

Abstract

The invention provides a preparation process and application of a tebuconazole suspending agent. The tebuconazole-containing suspending agent is prepared from the following components: tebuconazole, a defoaming agent, a wetting dispersant, a thickening agent, a stabilizer, an anti-freezing agent and water. Methyl methacrylate is compounded with methacrylic acid to react with 2-acrylamide-2-methylpropanesulfonic acid and 2, 2-dimethylolbutyric acid, reflux concentration is performed to prepare a concentrated solution, the concentrated solution further reacts with mercaptoacetic acid through a water free radical polymerization method, and the wetting dispersant is prepared after pH is adjusted. And compounding with tebuconazole to prepare the suspending agent containing tebuconazole. Compared with the prior art, the suspending agent containing tebuconazole prepared by the invention has better dispersing performance, and can improve the utilization rate of the pesticide, reduce the loss of the pesticide and prolong the shelf life of the pesticide.

Description

Technical Field

[0001] The invention relates to the technical field of insecticides, and in particular to a preparation process of a tebuconazole suspension and application thereof. Background Art

[0002] Tebuconazole suspension concentrate is a commonly used pesticide formulation, mainly used to prevent and control crop diseases, especially fungal diseases. Tebuconazole is a broad-spectrum fungicide with good control effects on a variety of pathogens. Suspension concentrate is a suspension containing active ingredients. Through the use of suspension concentrate, tebuconazole can be evenly dispersed in water, which is convenient for spraying and application.

[0003] Tebuconazole suspension can be used in the agricultural field to prevent and control apple leaf spot disease, bitter melon powdery mildew and honeysuckle powdery mildew. Apple leaf spot disease is a disease caused by fungi that causes spots on apple tree leaves and gradually turns yellow, withers and falls off. Tebuconazole suspension can be used to spray apple tree leaves to reduce the extent of the disease by inhibiting the growth and reproduction of pathogenic fungi. Bitter melon powdery mildew is a disease caused by powdery mildew, which manifests as a white powdery mold covering on the leaves and stems of bitter melon. Tebuconazole suspension can be used to spray the leaves and stems of the plant to inhibit the growth and spread of powdery mildew, helping to reduce the impact of the disease. Honeysuckle powdery mildew is also a disease caused by powdery mildew, which causes the surface of honeysuckle leaves and flowers to be covered with white powdery mold. Tebuconazole suspension can be used to spray honeysuckle plants to reduce the growth and spread of pathogenic fungi, thereby controlling the occurrence and spread of powdery mildew.

[0004] How to improve the dispersibility and drug utilization of tebuconazole suspension is a breakthrough direction of the research.

[0005] China's invention patent CN108464306B discloses a sustained-release thiophanate-methyl and tebuconazole suspension and a preparation method thereof, which belongs to the technical field of pesticide preparations. The active ingredients of the suspension are thiophanate-methyl and tebuconazole. The sustained-release thiophanate-methyl and tebuconazole suspension of the invention does not use organic solvents, is green and environmentally friendly, has a long lasting effect, a long-lasting drug effect, a high suspension rate, and stable product performance. The suspension of the invention is used for wheat, rice, fruit trees, vegetables and other crops and flowers to prevent fungal diseases of plants. However, the suspension prepared by the invention has the disadvantages of poor dispersibility, low drug utilization rate, and difficulty in storage. Summary of the invention

[0006] In view of the shortcomings of the prior art tebuconazole suspension, such as poor dispersibility, low drug utilization rate and difficulty in storage, the technical problem to be solved by the present invention is to provide a preparation process and application of a tebuconazole suspension which has good dispersibility, is easy to store and can significantly kill pests and diseases.

[0007] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions: A tebuconazole suspension comprises the following components: tebuconazole, a defoamer, a wetting and dispersing agent, a thickener, a stabilizer, an antifreeze agent and water.

[0008] Preferably, the tebuconazole suspension comprises the following components in weight percentage: 40-45% tebuconazole, 0.1-0.5% defoamer, 2-10% wetting and dispersing agent, 0.1-2% thickener, 0.1-5% stabilizer, 1-5% antifreeze agent, and the balance is water.

[0009] Preferably, the defoaming agent is at least one of sodium methylene dinaphthalene sulfonate, tributyl phosphate, polyoxyethylene sorbitan fatty acid ester, sodium methylene disulfonate, sodium lignin sulfonate or methylphenyl vinyl silicone oil.

[0010] Preferably, the thickener is at least one of carboxymethyl cellulose, soluble starch, gum arabic, xanthan gum, magnesium aluminum silicate, polyethylene glycol 6000 distearate or polyacrylamide.

[0011] Preferably, the stabilizer is at least one of 2,6-di-tert-butyl-4-methylphenol, glycerol, methanol, ethanol, butanol, epoxidized soybean oil, epoxidized linseed oil, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, aluminum monostearate, aluminum distearate, distearin, sorbitan monooleate, soybean lecithin, egg yolk lecithin or polyethylene glycol-12-hydroxystearate.

[0012] Preferably, the antifreeze agent is at least one of ethylene glycol, propylene glycol, glycerol or urea.

[0013] The preparation method of the tebuconazole suspension is as follows: weighing various raw materials according to weight percentage, first adding a wetting dispersant, a thickener, and 1 / 2 to 1 / 4 of water into a reactor with high shear stirring, heating to 60 to 70° C., and stirring to dissolve; then continuing to add tebuconazole, an antifreeze agent, a defoamer, a stabilizer, and the remaining water into the reactor, mixing, and continuing to stir until the mixture becomes a uniform viscous liquid, and then stopping stirring; then adding the uniform viscous liquid into a sand mill for sand grinding for 2 hours to 5 hours to prepare the tebuconazole suspension.

[0014] Preferably, the wetting and dispersing agent is prepared by the following method, in parts by weight: S1, add 0.5-1.5 parts of 5-10mmol / L methyl methacrylate aqueous solution, 2-5 parts of 40-60mmol / L methacrylic acid aqueous solution, 5-15 parts of 40-60mmol / L 2-acrylamide-2-methylpropanesulfonic acid aqueous solution, 1-1.5 parts of 5-15mmol / L 2,2-dihydroxymethylbutyric acid aqueous solution to 20-30 parts of water to prepare a mixed solution, adjust the temperature of the mixed solution to 60-80°C under a nitrogen environment, react for 20-50min, and then reflux and concentrate, the solvent used for the reflux is toluene, the reflux reaction temperature is 70-90°C, the reflux reaction time is 2-8h, and the concentration is to concentrate the mixed solution at a temperature of 60-80°C into a concentrated solution with a relative density of 1.1-1.5g / cm³, and collect the concentrated solution for standby use; S2, respectively dropping 0.5-1 part of 5-10 mmol / L thioglycolic acid aqueous solution and 0.5-1 part of 3-5 mmol / L ammonium persulfate aqueous solution into the concentrated solution prepared in step S1, with a dropping speed of 10-30 mL / min. After the dropping is completed, the reaction temperature is maintained at 80-90° C. and the reaction is carried out for 1-3 hours to obtain a reaction solution; S3. Add 30-60 wt % of NaOH aqueous solution to the reaction solution prepared in step S2, adjust the pH value to 7-8, and obtain a wetting dispersant.

[0015] The tebuconazole suspension is used in preventing and controlling apple leaf spot disease, bitter melon and honeysuckle powdery mildew.

[0016] The present invention uses methyl methacrylate to compound methacrylic acid with 2-acrylamide-2-methylpropanesulfonic acid and 2,2-dihydroxymethylbutyric acid, refluxes and concentrates to prepare a concentrated solution, and then further reacts with thioglycolic acid through a water free radical polymerization method, and adjusts the pH to prepare a wetting dispersant. The wetting dispersant contains functional groups such as hydroxyl groups; sulfonic acid groups, carboxylic acid groups and amide groups, and has good adsorption and dispersion properties, thereby improving the grinding performance during processing. The chemical chain of the wetting dispersant can provide strong steric hindrance energy between particles, and has electrostatic repulsion and wettability. In addition, the wetting dispersant can also reduce the viscosity of the suspension, so that the suspension has good grinding performance. In the presence of the wetting dispersant, the zeta potential of the particle surface is increased, and the electrostatic repulsion between the particles is enhanced, thereby improving the dispersion and grinding performance of the particles. The field efficacy is improved.

[0017] From a kinetic point of view, the pesticide water suspension is an unstable system. Since the dispersant molecules wrapped on the surface of the original drug particles repel each other, there is no continuous network structure in the system to support it, which will cause the particles therein to settle over time. The wetting dispersant added in the present invention can reduce the viscosity of the grinding liquid. The carbon chain of the wetting dispersant is adsorbed on the surface of the particles, which reduces the surface energy of the particles, makes the particles have lower viscosity and higher fluidity, and optimizes the grinding performance. The rheological behavior of the suspension containing tebuconazole can be regarded as a shear deformation type non-Newtonian fluid. In the presence of a wetting dispersant, due to the steric hindrance that reduces the contact probability between particles, the inter-particle electrostatic and steric hindrance electrostatic repulsion can improve the dispersion and grinding performance of the particles. There are three types of particle crushing mechanisms, namely wear, compression and impact crushing. In wear crushing, the tangential force peeling of the particle surface can produce sub-particles with similar particle sizes to the parent particles and fine sub-particles. In impact crushing, particles are broken under high-density extrusion stress, and the volume of the obtained sub-particles is generally 20~70% of the parent particles. Therefore, the smaller the particle size of the prepared particles, the fewer defects, the larger the specific surface area, the higher the strength, and the more stable the structure.

[0018] The theory of viscosity change is that the electrostatic repulsion between dispersed particles increases, resulting in less entanglement of the dispersant wrapped on the surface of the particles, and the hydrodynamic volume of the entire system decreases, so the viscosity decreases, and the system becomes more stably dispersed. If the wetting dispersant is continued to be added, the viscosity of the suspension increases. This is because after adsorption saturation, the excess dispersant will squeeze the double layer, the system will have vacancy flocculation, the friction in the dispersed phase will increase, the dispersant molecules will be more entangled, and the hydrodynamic volume of the system will increase, resulting in increased viscosity. When the amount of wetting dispersant added is small, it is not enough to cover the surface of the suspension particles, resulting in poor wettability of the particle surface. When the amount of wetting dispersant added is large, the particle size distribution of the suspension particles is significantly wider and the median of the particle size is larger. This may be because the carbon chain of the wetting dispersant is excessively adsorbed on the surface of the particles, causing them to be entangled, hindering the dispersion and ultrafine grinding of the particles. The amount of the wetting dispersant added in the present invention is verified by experiments, and the adsorption saturation amount is determined to be the best. The adsorption of the wetting dispersant on the particle surface depends on hydrogen bonds, and the hydroxyl groups in the wetting dispersant can form hydrogen bonds on the particle surface. In addition, the ester group in the wetting and dispersing agent reduces the contact probability between particles due to steric hindrance, enhancing the steric hindrance and electrostatic repulsion effects. Therefore, the wetting and dispersing agent has a better dispersing and grinding effect on the suspension.

[0019] The present invention has found through experimental research that when the pH value is 3.0, the surface of the suspension agent particles is positively charged, and when the pH value is greater than 3, the surface of the suspension agent particles is negatively charged. The reason for this phenomenon may be that the hydrogen ions added to the suspension neutralize the hydroxide ions in the suspension. When the pH value is 7.0-8.0, the zeta potential on the particle surface reaches a maximum value. The zeta potential may be reduced as the pH value continues to increase. The possible reason is that a larger pH value will compress the double layer on the surface of the particle, thereby reducing the thickness and electromotive force of the double layer, thereby reducing the electrostatic repulsion between the particles and weakening the dispersion and grinding performance of the particles. Therefore, in the preparation process of the wetting dispersant, the present invention finally adjusts the pH value to between 7.0-8.0 to control the wetting dispersant to produce the maximum steric hindrance and electrostatic repulsion.

[0020] Compared with the prior art, the present invention has the following beneficial effects: 1) The present invention uses methyl methacrylate to compound methacrylic acid with 2-acrylamide-2-methylpropanesulfonic acid and 2,2-dihydroxymethylbutyric acid to react, reflux and concentrate to prepare a concentrated solution, and then further react with thioglycolic acid through a water free radical polymerization method, and adjust the pH to prepare a wetting dispersant. The wetting dispersant has good adsorption and dispersion properties and improves the grinding performance during the processing.

[0021] 2) During the medicinal process, the prepared tebuconazole suspension has a good dispersion effect, which can improve the utilization rate of the drug, reduce the loss of pesticides and extend the shelf life of pesticides. DETAILED DESCRIPTION

[0022] The present invention is further explained below in conjunction with specific implementation modes.

[0023] To avoid redundancy, the items used in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods unless otherwise specified.

[0024] Sodium methylene dinaphthalene sulfonate, Anyang Longquan Chemical Co., Ltd., Molecular formula: C 21 H 14 O6S2Na2, diffusion rate: ≥95%, PH value: 7~9.

[0025] 2-Acrylamide-2-methylpropanesulfonic acid, Shandong Guangshen Electronic Technology Co., Ltd., CAS: 15214-89-8, Grade: superior.

[0026] Example 1 A tebuconazole suspension is prepared by the following method: first, 6 kg of a wetting dispersant, 1 kg of xanthan gum and 25.9 kg of water are added into a reaction kettle with high shear stirring, heated to 65°C, and stirred to dissolve; then, 43 kg of tebuconazole, 3 kg of ethylene glycol, 0.3 kg of sodium methylene dinaphthalene sulfonate, 2 kg of 2,6-di-tert-butyl-4-methylphenol and 51.8 kg of water are added into the reaction kettle for mixing, and stirring is continued until the mixture becomes a uniform viscous liquid, and stirring is stopped; then, the uniform viscous liquid is added into a sand mill for sand grinding for 3 hours to prepare the tebuconazole suspension.

[0027] The wetting and dispersing agent is prepared by the following method: S1, 0.9kg 9mmol / L methyl methacrylate aqueous solution, 4kg 50mmol / L methacrylic acid aqueous solution, 9kg 50mmol / L 2-acrylamide-2-methylpropanesulfonic acid aqueous solution, 1.2kg 9mmol / L 2,2-dihydroxymethylbutyric acid aqueous solution were added to 28kg water to form a mixed solution, and the temperature of the mixed solution was adjusted to 70°C under a nitrogen environment, and the mixture was reacted for 30min, and then refluxed and concentrated, wherein the solvent used for the reflux was toluene, the reflux reaction temperature was 80°C, and the reflux reaction time was 5h, and the concentration was concentrated at a temperature of 70°C to concentrate the mixed solution into a concentrated solution with a relative density of 1.4g / cm³, and the concentrated solution was collected for standby use; S2, 0.8 kg 8 mmol / L thioglycolic acid aqueous solution and 0.7 kg 3.4 mmol / L ammonium persulfate aqueous solution were respectively added dropwise into the concentrated solution prepared in step S1, the dropping speed was 20 mL / min, after the dropwise addition was completed, the reaction temperature was maintained at 85 ° C, the reaction was carried out for 2 hours, and a reaction solution was obtained; S3. Add 50 wt % NaOH aqueous solution to the reaction solution prepared in step S2, adjust the pH value to 7.5, and obtain a wetting dispersant.

[0028] Example 2 The preparation method of a tebuconazole suspension concentrate is substantially the same as that of Example 1, with the only difference being that the preparation method of the wetting and dispersing agent is different.

[0029] The preparation steps of the wetting and dispersing agent are as follows: S1. Add 0.9kg 9mmol / L methyl methacrylate aqueous solution, 4kg 50mmol / L methacrylic acid aqueous solution, and 1.2kg 9mmol / L 2,2-dihydroxymethylbutyric acid aqueous solution to 28kg water to form a mixed solution. Under a nitrogen environment, adjust the temperature of the mixed solution to 70°C, react for 30 minutes, and then reflux and concentrate. The solvent used for the reflux is toluene, the reflux reaction temperature is 80°C, and the reflux reaction time is 5h. The concentration is to concentrate the mixed solution at a temperature of 70°C into a concentrated solution with a relative density of 1.4g / cm³, and collect the concentrated solution for standby use; S2, 0.8 kg 8 mmol / L thioglycolic acid aqueous solution and 0.7 kg 3.4 mmol / L ammonium persulfate aqueous solution were respectively added dropwise into the concentrated solution prepared in step S1, the dropping speed was 20 mL / min, after the dropwise addition was completed, the reaction temperature was maintained at 85 ° C, the reaction was carried out for 2 hours, and a reaction solution was obtained; S3. Add 50 wt % NaOH aqueous solution to the reaction solution prepared in step S2, adjust the pH value to 7.5, and obtain a wetting dispersant.

[0030] Example 3 The preparation method of a tebuconazole suspension concentrate is substantially the same as that of Example 1, with the only difference being that the preparation method of the wetting and dispersing agent is different.

[0031] The preparation steps of the wetting and dispersing agent are as follows: S1, 0.9kg 9mmol / L methyl methacrylate aqueous solution, 4kg 50mmol / L methacrylic acid aqueous solution, 9kg 50mmol / L 2-acrylamide-2-methylpropanesulfonic acid aqueous solution were added to 28kg water to form a mixed solution, and the temperature of the mixed solution was adjusted to 70°C under a nitrogen environment, and the mixture was reacted for 30min, and then refluxed and concentrated, wherein the solvent used for the reflux was toluene, the reflux reaction temperature was 80°C, and the reflux reaction time was 5h, and the concentration was concentrated at a temperature of 70°C to concentrate the mixed solution into a concentrated solution with a relative density of 1.4g / cm³, and the concentrated solution was collected for standby use; S2, 0.8 kg 8 mmol / L thioglycolic acid aqueous solution and 0.7 kg 3.4 mmol / L ammonium persulfate aqueous solution were respectively added dropwise into the concentrated solution prepared in step S1, the dropping speed was 20 mL / min, after the dropwise addition was completed, the reaction temperature was maintained at 85 ° C, the reaction was carried out for 2 hours, and a reaction solution was obtained; S3. Add 50 wt % NaOH aqueous solution to the reaction solution prepared in step S2, adjust the pH value to 7.5, and obtain a wetting dispersant.

[0032] Example 4 The preparation method of a tebuconazole suspension concentrate is substantially the same as that of Example 1, with the only difference being that the preparation method of the wetting and dispersing agent is different.

[0033] The preparation steps of the wetting and dispersing agent are as follows: S1, 0.9kg 9mmol / L methyl methacrylate aqueous solution, 4kg 50mmol / L methacrylic acid aqueous solution, 9kg 50mmol / L 2-acrylamide-2-methylpropanesulfonic acid aqueous solution, 1.2kg 9mmol / L 2,2-dihydroxymethylbutyric acid aqueous solution were added to 28kg water to form a mixed solution, and the temperature of the mixed solution was adjusted to 70°C under a nitrogen environment, and the mixture was reacted for 30min, and then refluxed and concentrated, wherein the solvent used for the reflux was toluene, the reflux reaction temperature was 80°C, and the reflux reaction time was 5h, and the concentration was concentrated at a temperature of 70°C to concentrate the mixed solution into a concentrated solution with a relative density of 1.4g / cm³, and the concentrated solution was collected for standby use; S2, 0.7 kg 3.4 mmol / L ammonium persulfate aqueous solution was added dropwise to the concentrated solution prepared in step S1, the dropping speed was 20 mL / min, after the dropwise addition was completed, the reaction temperature was maintained at 85 ° C, the reaction was carried out for 2 hours, and a reaction solution was obtained; S3. Add 50 wt % NaOH aqueous solution to the reaction solution prepared in step S2, adjust the pH value to 7.5, and obtain a wetting dispersant.

[0034] Comparative Example 1 The preparation method of a tebuconazole suspension concentrate is substantially the same as that of Example 1, with the only difference being that the preparation method of the wetting and dispersing agent is different.

[0035] The preparation steps of the wetting and dispersing agent are as follows: S1. Add 0.9kg 9mmol / L methyl methacrylate aqueous solution and 4kg 50mmol / L methacrylic acid aqueous solution to 28kg water to form a mixed solution. Under a nitrogen environment, adjust the temperature of the mixed solution to 70°C, react for 30min, and then reflux and concentrate. The solvent used for the reflux is toluene, the reflux reaction temperature is 80°C, and the reflux reaction time is 5h. The concentration is to concentrate the mixed solution at a temperature of 70°C into a concentrated solution with a relative density of 1.4g / cm³, and collect the concentrated solution for standby use. S2, 0.7 kg 3.4 mmol / L ammonium persulfate aqueous solution was added dropwise to the concentrated solution prepared in step S1, the dropping speed was 20 mL / min, after the dropwise addition was completed, the reaction temperature was maintained at 85 ° C, the reaction was carried out for 2 hours, and a reaction solution was obtained; S3. Add 50 wt % NaOH aqueous solution to the reaction solution prepared in step S2, adjust the pH value to 7.5, and obtain a wetting dispersant.

[0036] Comparative Example 2 The preparation method of a tebuconazole suspension concentrate is substantially the same as that of Example 1, with the only difference being that no wetting and dispersing agent is added in the preparation method of a tebuconazole suspension concentrate.

[0037] Test Example 1 Field efficacy testing Field efficacy test for the prevention and control of powdery mildew in bitter melon The field efficacy test was conducted in accordance with the provisions of the Institute for Drug Control of the Ministry of Agriculture and Rural Affairs, "GB / T17980.30-2000 Pesticide Field Efficacy Test Guidelines (I) - Fungicides for the Prevention and Control of Cucumber Powdery Mildew". The plots of the test agent, control agent and blank control were arranged in random blocks, with a plot area of ​​16m 2 , 4 times of repetition, this experiment applied the pesticide twice in total. The first application was at the early stage of the disease, and the second application was done one week later. The dosage of each application was 15 ml / mu. Four random sampling points were used in each experimental plot, and 2 plants were surveyed at each point. All leaves of each plant were surveyed and the disease grade was recorded.

[0038] The disease classification standards are as follows: Level 0: no lesions; Level 1: The lesion area accounts for less than 5% of the entire leaf area; Level 3: The lesion area accounts for 6% to 10% of the entire leaf area; Level 5: The lesion area accounts for 11% to 20% of the entire leaf area; Level 7: The lesion area accounts for 21% to 40% of the entire leaf area; Level 9: The area of ​​lesions accounts for more than 40% of the total leaf area.

[0039] The efficacy calculation method is as follows: Disease index = Σ[number of diseased leaves at each level × relative level value] × 100 / total number of surveys × 9 Control effect (%) = [1- (CK0 × PT1) / (CK1 × PT0)] × 100 Wherein: CK0 and CK1 are the disease indexes of the blank control area before and after application of the drug, respectively; PT0 and PT1 are the disease indexes of the drug-treated area before and after application of the drug, respectively.

[0040] The test results are shown in Table 1 Table 1: Field efficacy test results

[0041] As can be seen from the test results of Table 1, the field efficacy of the tebuconazole suspension prepared in Example 1 is the best. The possible reason is that the present invention uses methyl methacrylate to compound methacrylic acid with 2-acrylamide-2-methylpropanesulfonic acid and 2,2-dihydroxymethylbutyric acid, refluxes and concentrates to prepare a concentrated solution, and then further reacts with thioglycolic acid by water free radical polymerization, and adjusts pH to prepare a wetting dispersant. The wetting dispersant contains functional groups such as hydroxyl, sulfonic acid groups, carboxylic acid groups and amide groups, has good adsorption and dispersion performance, and improves the grinding performance during processing. The chemical chain of the wetting dispersant can provide strong steric hindrance between particles, and has electrostatic repulsion and wettability on the particle surface. In addition, the wetting dispersant can also reduce the viscosity of the suspension, so that the suspension has good grinding performance. In the presence of the wetting dispersant, the zeta potential of the particle surface is increased, and the electrostatic repulsion between the particles is enhanced, thereby improving the dispersion and grinding performance of the particles. Therefore, when acting on crops, the field efficacy of Example 1 is the best.

[0042] Test Example 2 Determination of storage stability The test of storage stability was carried out according to the test of (Shanghai Normal University, Effect of Polycarboxylate Dispersants on the Stability of Pesticide Aqueous Suspension Concentrates, Author: Gui Qifeng, 2017) and was carried out at 60±2.0°C. First, the specific method of the hot storage stability test was as follows: the tebuconazole suspension prepared in the embodiment and the comparative example was placed in a 10 mL ampoule at room temperature, which was sealed and stored continuously at 60±2.0°C for 14 days, and the technical indicators of appearance, particle size, and suspension rate were analyzed, detected, and recorded.

[0043] The difference in sample particle size before and after hot storage was tested with reference to the test (Shanghai Normal University, Effect of Polycarboxylate Dispersants on the Stability of Pesticide Aqueous Suspension Concentrates, Author: Gui Qifeng, 2017), and the long-term storage stability of the system was judged by the change in particle size.

[0044] The suspension rate was determined as follows: about 100 mL of deionized water was added to a 250 mL measuring cylinder, the cylinder was peeled and zeroed on an electronic balance, and then 2.5 g of the tebuconazole suspension prepared in the embodiment and the comparative example was dripped into the measuring cylinder, and the actual dripping mass was recorded as Z. After the dripping was completed, standard hard water was slowly added to accurately adjust to the 250 mL scale and the measuring cylinder was tightly plugged with a stopper. The stoppered measuring cylinder was turned upside down 30 times, and after the shaking was completed, it was left to stand to ensure that there was no fluctuation interference around. After 0.5 hours, the 225 mL of liquid located on the upper layer was extracted with a micro-table vacuum pump. At this time, 25 mL of liquid was left at the bottom of the measuring cylinder, which was transferred to a culture dish with a mass of M1 after washing and drying. After rinsing the measuring cylinder three times with a small amount of distilled water, each washing liquid was transferred to the above-mentioned culture dish. Finally, the dish was placed in an oven and dried overnight at 75 ° C. After drying, the culture dish was weighed as a whole and recorded as M2. The mass of the dry solid in the culture dish is recorded as S, then S=M2-M1, and the suspension rate is calculated using the following formula: Suspension rate=10 / 9×100(aZ-S) / aZ×100%=111(aZ-S) / aZ×100% Where a is the content of the effective component in the sample; Z is the actual sampling mass, and S is the mass of the effective component in the remaining 25 mL of suspension.

[0045] Suspension rate difference = suspension rate 前 - Suspension rate 后 The suspension rate difference is the difference between the suspension rates before and after storage; 前 is the suspension rate before storage; 后 is the suspension rate after storage; Each sample was tested three times and the average value was taken. The test results are shown in Table 2.

[0046] Table 2: Storage stability test results

[0047] From a kinetic point of view, the pesticide suspension concentrate is an unstable system. Since the dispersant molecules wrapped around the surface of the original drug particles repel each other and there is no continuous network structure to support the system, the particles will settle over time.

[0048] As can be seen from the test results of Table 2, the storage stability of the tebuconazole suspension of Example 1 is the best, which may be due to the wetting and dispersing agent added by the present invention can reduce the viscosity of the grinding liquid, and the carbon chain of the wetting and dispersing agent is adsorbed on the particle surface, which reduces the particle surface energy, makes the particles have lower viscosity and higher fluidity, and optimizes the grinding performance. The rheological behavior of the tebuconazole suspension can be regarded as a shear deformation type non-Newtonian fluid. In the presence of the wetting and dispersing agent, the contact probability between particles is reduced due to steric hindrance, and the inter-particle static electricity and steric hindrance electrostatic repulsion can improve the dispersion and grinding performance of the particles. There are three types of particle crushing mechanisms, namely wear, compression and impact crushing. In wear and tear, the tangential force on the particle surface is peeled off, and sub-particles similar to the parent particle and fine sub-particle size can be produced. In impact crushing, the particles are crushed under the action of high-density extrusion stress, and the volume of the obtained sub-particles is generally 20-70% of the parent particle, so the smaller the particle size of the prepared particles, the fewer defects, the larger the specific surface area, the higher the strength, and the more stable the structure, so the storage stability of Example 1 is the best.

[0049] Test Example 3 Determination of viscosity The absolute viscosity of the system is determined by the rotational viscometer method, that is, at 25°C, the viscosity of the suspension system is determined by the NDJ-1 type rotational viscometer. A specified amount of tebuconazole suspension sample is placed in a cylindrical sampling tank, and a suitable rotor is selected so that the liquid level of the sample is submerged in the rotor. The reading is taken after the pointer is finally stable. As shown below, the absolute viscosity η of the test sample is the product of the pointer reading d on the scale dial and the coefficient k, and the unit is mPa•ּs.

[0050] η=kd formula (2-2) Where, η-absolute viscosity, mPa•s; k-rotor coefficient; d- The reading indicated by the pointer (a certain deflection angle is equal to one reading unit).

[0051] Each example and comparative example sample was tested three times and the average value was taken. The test results are shown in Table 3.

[0052] Table 3: Viscosity measurement results

[0053] The theory of viscosity change is that the electrostatic repulsion between dispersed particles increases, resulting in less entanglement of the dispersant wrapped on the surface of the particles, and the hydrodynamic volume of the entire system decreases, so the viscosity decreases and the system becomes more stably dispersed. If wetting dispersant is continued to be added, the viscosity of the suspension increases. This is because after adsorption saturation, the excess dispersant will squeeze the double layer, the system will have vacancy flocculation, the friction in the dispersed phase will increase, the dispersant molecules will become more entangled, and the hydrodynamic volume of the system will increase, resulting in an increase in viscosity.

[0054] From the test results in Table 3, it can be seen that the viscosity of Example 1 is the smallest. The reason may be that the amount of the wetting and dispersing agent added in the present invention is the adsorption saturation amount, and the adsorption of the wetting and dispersing agent on the particle surface depends on hydrogen bonding. The hydroxyl groups in the wetting and dispersing agent can form hydrogen bonds on the particle surface. In addition, the ester group in the wetting and dispersing agent reduces the contact probability between particles due to steric hindrance. Enhance the steric hindrance effect and the electrostatic repulsion effect. Therefore, the wetting and dispersing agent has a good dispersing and grinding effect on the suspending agent. So the viscosity of Example 1 is the smallest.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A tebuconazole suspension, characterized in that, The invention comprises the following components in weight percentage: 40-45% tebuconazole, 0.1-0.5% defoaming agent, 2-10% wetting dispersant, 0.1-2% thickener, 0.1-5% stabilizer, 1-5% antifreeze agent, and the balance is water; The wetting and dispersing agent is prepared by the following method, calculated by weight: S1, add 0.5-1.5 parts of 5-10mmol / L methyl methacrylate aqueous solution, 2-5 parts of 40-60mmol / L methacrylic acid aqueous solution, 5-15 parts of 40-60mmol / L 2-acrylamide-2-methylpropanesulfonic acid aqueous solution, 1-1.5 parts of 5-15mmol / L 2,2-dihydroxymethylbutyric acid aqueous solution to 20-30 parts of water to prepare a mixed solution, under a nitrogen environment, adjust the temperature of the mixed solution to 60-80°C, react for 20-50min, and then reflux and concentrate, the solvent used for the reflux is toluene, the reflux reaction temperature is 70-90°C, the reflux reaction time is 2-8h, and the concentration is to concentrate the mixed solution at a temperature of 60-80°C into a concentrated solution with a relative density of 1.1-1.5g / cm³, and collect the concentrated solution for standby use; S2, respectively dropping 0.5-1 part of 5-10 mmol / L thioglycolic acid aqueous solution and 0.5-1 part of 3-5 mmol / L ammonium persulfate aqueous solution into the concentrated solution prepared in step S1, with a dropping speed of 10-30 mL / min. After the dropping is completed, the reaction temperature is maintained at 80-90° C. and the reaction is carried out for 1-3 hours to obtain a reaction solution; S3. Add 30-60 wt % of NaOH aqueous solution to the reaction solution prepared in step S2, adjust the pH value to 7-8, and obtain a wetting dispersant.

2. A tebuconazole suspension according to claim 1, characterized in that: The defoaming agent is at least one of sodium methylene dinaphthalene sulfonate, tributyl phosphate, polyoxyethylene sorbitan fatty acid ester, sodium methylene disulfonate, sodium lignin sulfonate or methylphenyl vinyl silicone oil.

3. A tebuconazole suspension according to claim 1, characterized in that: The thickener is at least one of carboxymethyl cellulose, soluble starch, gum arabic, xanthan gum, magnesium aluminum silicate, polyethylene glycol 6000 distearate or polyacrylamide.

4. A tebuconazole suspension according to claim 1, characterized in that: The stabilizer is at least one of 2,6-di-tert-butyl-4-methylphenol, glycerol, methanol, ethanol, butanol, epoxidized soybean oil, epoxidized linseed oil, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, aluminum monostearate, aluminum distearate, distearin, sorbitan monooleate, soybean lecithin, egg yolk lecithin or polyethylene glycol-12-hydroxystearate.

5. A tebuconazole suspension according to claim 1, characterized in that: The antifreeze agent is at least one of ethylene glycol, propylene glycol, glycerol or urea.

6. A method for preparing the tebuconazole suspension concentrate according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: weighing various raw materials according to weight percentage, firstly adding a wetting dispersant, a thickener and 1 / 2 to 1 / 4 of water into a reaction kettle with high shear stirring, heating to 60 to 70 DEG C, and stirring to dissolve; then continuously adding tebuconazole, an antifreeze agent, a defoaming agent, a stabilizer and the remaining water into the reaction kettle, mixing, and continuously stirring until the mixture becomes a uniform viscous liquid, and then stopping stirring; then adding the uniform viscous liquid into a sand mill for sand grinding for 2h to 5h, so as to prepare the tebuconazole suspension.

7. An application of the tebuconazole suspension concentrate according to any one of claims 1 to 6, characterized in that: Application in the prevention and control of apple leaf spot disease, bitter melon and honeysuckle powdery mildew.

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