High-efficiency cyfluthrin microcapsule suspending agent and preparation method thereof

Abstract

The present application relates to the technical field of pesticide production, in particular to a high-efficiency lambda-cyhalothrin microcapsule suspending agent and a preparation method thereof, aiming at solving the problems of low encapsulation rate, poor dispersibility, insufficient stability and high skin irritation in the prior art. The microcapsule suspending agent is made of high-efficiency lambda-cyhalothrin, 150# aromatic hydrocarbon solvent, polyisocyanate, polyamine, lecithin and other components, and through specific preparation steps, a crosslinked network structure is formed to effectively coat the high-efficiency lambda-cyhalothrin and improve the encapsulation rate. The microcapsule suspending agent has high encapsulation rate, good dispersibility, excellent stability and low skin irritation, and can significantly improve the use effect and safety of pesticides. Through experimental verification, the microcapsule suspending agent performs well in terms of photolysis resistance, wet sieve test, persistent foaming property, low-temperature stability and heat storage stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pesticide production, and in particular to a high-efficiency lambda-cyhalothrin microcapsule suspension agent. BACKGROUND

[0002] Microcapsule technology started early in the medical field, and drugs were often wrapped in enteric materials to avoid the reduction of drug efficacy caused by gastric acid. Later, it was gradually extended to the fields of pesticides, veterinary drugs, and cosmetics. In the United States

[0003] In the 1970s, microencapsulation of methyl isothiocyanate was realized, which reduced the toxicity of short-acting pesticides and opened a new era of pesticide microencapsulation technology.

[0004] In recent years, microcapsule suspensions have developed rapidly. Herbicides include propachlor, pendimethalin, and isoxaben; insecticides include chlorpyrifos, imidacloprid, and high-efficiency lambda-cyhalothrin; and fungicides include triazophos, pyraclostrobin, and pyraclostrobin. The market-leading pesticide products have basically achieved microencapsulation. However, due to the lack of product standards, the quality standards for the performance of preparations such as embedding rate and suspension rate are different among manufacturers, but the general encapsulation rate is 80%-90%, which leads to waste of pesticides. In addition, the stability of microcapsule suspensions is easily affected by external factors such as storage time, light, and environmental temperature. For example, during storage, the active ingredients are degraded, the dispersibility of the microcapsule suspension is poor, and even the microcapsule suspension is stratified. The microcapsule suspension is easily affected by sunlight during field application, which leads to degradation of the active ingredients, reduces the utilization rate of the active ingredients, and requires frequent application of pesticides, which not only increases the cost but also affects the environment. Secondly, pesticides have certain toxicity. Although the active ingredients of pesticides are coated in the wall material, reducing direct contact with the outside world, they still have skin irritation, which poses potential hazards to operators and the environment

[0005] Therefore, according to the related technology in the above, it is urgent to develop a high-efficiency lambda-cyhalothrin microcapsule suspension agent. SUMMARY

[0006] Therefore, according to the related technology in the above, it is urgent to develop a high-efficiency lambda-cyhalothrin microcapsule suspension agent.

[0007] To achieve the above purpose, the present application adopts the following technical solutions:

[0008] A high-efficiency lambda-cyhalothrin microcapsule suspension agent comprises the following preparation steps:

[0009] S1: Heat soybean oil to 68-72 DEG C, add peroxyformic acid to the soybean oil, and react for 3-5 h. Separate the water phase, wash until the pH is 6.8-7.2, and distill under reduced pressure to obtain epoxy soybean oil;

[0010] S2: Add epoxy soybean oil into isopropyl alcohol, add isopropylamine and tetrafluoroboric acid, stir and react, control the temperature at 65-75℃, react for 15-18h, wash with saturated sodium sulfate solution, distill under reduced pressure to obtain soybean polyol;

[0011] S3: Under nitrogen protection, warm 4,4'-diphenyl methane diisocyanate to 57-65℃, after 4,4'-diphenyl methane diisocyanate is dissolved, add ethyl acetate and 2,4,6-tris(dimethylaminomethyl) phenol, control the reaction temperature to keep at 57-65℃, when the reaction solution is milky white and the viscosity increases, determine the isocyanate group (-NCO) content by using di-n-butylamine method, calculate the -NCO content to be 7.8%-8.1%, add benzoyl chloride and stir for 20-30min, wash and dry to obtain isocyanate trimer;

[0012] S4: Mix isocyanate trimer, polytetrahydrofuran diol, polyethylene glycol monomethyl ether, dibutyl tin dilaurate and acetone uniformly, heat to 85-95℃, add soybean polyol, react for 3-4h to obtain polyisocyanate;

[0013] S5: Dissolve lambda-cyhalothrin in 150# aromatic hydrocarbon solvent oil, add polyisocyanate and lecithin, stir uniformly to obtain uniform oil phase;

[0014] S6: Mix emulsifier, dispersant, glycyrrhizic acid dipotassium and water, stir uniformly to obtain water phase;

[0015] S7: Slowly pour the oil phase into the water phase, stir at high speed to form O / W emulsion, warm to 45℃, drop polyamine, constant temperature reaction for 3-4h, cool to 30℃, add water thickening agent, preservative, defoaming agent, antifreeze, adjust pH to 5.5-5.8 with citric acid, stir uniformly to obtain lambda-cyhalothrin microcapsule suspension.

[0016] Preferably, the lambda-cyhalothrin microcapsule suspension is made of the following components by weight percentage: lambda-cyhalothrin 18%-22%, 150# aromatic hydrocarbon solvent 15%-25%, polyisocyanate 1.5%-2.5%, polyamine 0.4%-0.7%, lecithin 1%-3%, glycyrrhizic acid dipotassium 0.3%-0.5%, emulsifier 4%-6%, dispersant 1.5%-3%, water thickening agent 0.2%-0.3%, preservative 0.1%-0.3%, defoaming agent 0.1%-0.3%, antifreeze 3%-4%, pH regulator 0.1%-0.3%, and water to 100%.

[0017] Preferably, the emulsifier is any one of fatty alcohol polyoxyethylene ether, lauryl alcohol polyoxyethylene ether, sorbitan monooleate and polyoxyethylene sorbitan monooleate.

[0018] Preferably, the polyamine is at least one of ethylenediamine, diethylenetriamine and triethylenetetramine.

[0019] Preferably, the dispersing agent is at least one of sodium lignosulfonate, alkylphenol polyoxyethylene ether phosphate, triphenyl styryl phenol polyoxyethylene ether phosphate ammonium salt and naphthalene sulfonate formaldehyde condensate sulfonate.

[0020] Preferably, the water thickening agent is compounded by magnesium aluminum silicate and xanthan gum, and the mass ratio of magnesium aluminum silicate and xanthan gum is 1:2-3.

[0021] Preferably, the defoaming agent is a silicone defoaming agent.

[0022] Preferably, the preservative is isothiazolinone.

[0023] Preferably, the antifreeze agent is propylene glycol.

[0024] Preferably, the pH regulator is citric acid monohydrate.

[0025] Preferably, the isopropanolamine is isopropanolamine or triisopropanolamine.

[0026] Preferably, in the preparation process of S1, the mass ratio of the soybean oil and the peroxyformic acid is 1:1.5-2.

[0027] Preferably, in the preparation process of S2, the mass ratio of the epoxy soybean oil, isopropanol, isopropanolamine, tetrafluoroboric acid is 1:2-2.5:1.5-1.9:0.03-0.005.

[0028] Preferably, in the preparation process of S3, the mass ratio of 4,4'-diphenyl methane diisocyanate, 2,4,6-tris(dimethylaminomethyl) phenol, ethyl acetate is 50:0.1-0.2:20-30.

[0029] Preferably, in the preparation process of S4, the mass ratio of isocyanate trimer, polytetrahydrofuran diol, polyethylene glycol monomethyl ether, dibutyl tin dilaurate, acetone and soybean polyol is 13.5:14-18:6-8:0.1-0.2:4-6:5-7.

[0030] The beneficial effects of the present application are as follows:

[0031] 1. The high-efficiency fluoro-cypermethrin micro-capsule suspension prepared by the present application can effectively coat high-efficiency fluoro-cypermethrin by introducing polyisocyanate to form a cross-linked network structure, thereby significantly improving the encapsulation rate.

[0032] 2、The microcapsule suspension agent prepared by the application has good dispersibility and stability, can be uniformly dispersed in the aqueous phase, and can maintain good stability under different environmental conditions, such as low temperature and high temperature.

[0033] 3、The microcapsule suspension agent has good photolysis resistance and rainwater scouring resistance, can maintain high stability under light conditions, reduces the problem of pesticide failure due to photolysis, can effectively reduce the loss of pesticides under natural conditions such as rainwater scouring, maintains the persistence of drug efficacy, thereby reducing the pollution caused by the loss of pesticides to the environment, and also reduces the increased cost due to frequent pesticide application. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the application more clear and explicit, the application is further described in detail below with specific examples.

[0035] Example 1

[0036] A high-efficiency lambda cyhalothrin microcapsule suspension agent comprises the following preparation steps:

[0037] S1: Soybean oil 6 g is heated to 70℃, peroxide formic acid 12 g is added, and reaction is maintained for 4 h, the aqueous phase is separated, washed with pure water until the pH is 7.0, and then reduced pressure distillation is performed to obtain epoxy soybean oil;

[0038] S2: The obtained epoxy soybean oil 5 g is added into isopropyl alcohol 12.5 g, isopropyl alcohol amine 9.5 g and tetrafluoroboric acid 1.2 g are added, stirring reaction is performed for 16 h with the temperature controlled at 70℃, saturated sodium sulfate solution is used for washing, and then reduced pressure distillation is performed to obtain soybean polyol;

[0039] S3: Under the protection of nitrogen, 4,4'-diphenyl methane diisocyanate 50 g is warmed to 60℃, 2,4,6-tris(dimethylaminomethyl) phenol 1.5 g and ethyl acetate 25 g are added, the reaction temperature is controlled to be maintained at 60℃, when the solution is milky white and the viscosity increases, the -NCO content is determined to be 8.0% by using di-n-butylamine method, benzoyl chloride 35 g is added and stirred for 25 min, and then washing and drying are performed to obtain isocyanate trimer;

[0040] S4: The obtained isocyanate trimer 40 g, polytetrahydrofuran diol 45 g, polyethylene glycol monomethyl ether 7 g, dibutyl tin dilaurate 0.015 g and acetone 5 g are uniformly mixed, heated to 90℃, the soybean polyol 6 g of S2 is added, and reaction is performed for 3.6 h to obtain polyisocyanate;

[0041] S5: dissolve 400 g of lambda-cyhalothrin in 380 g of 150# aromatic hydrocarbon solvent oil, add 40 g of polyisocyanate prepared in S4 and 18 g of lecithin, stir uniformly to obtain a uniform oil phase;

[0042] S6: mix 100 g of fatty alcohol polyoxyethylene ether, 50 g of naphthalene sulfonate formaldehyde condensate sulfonate, 8 g of glycyrrhizic acid dipotassium and 908 g of water, stir uniformly to obtain an aqueous phase;

[0043] S7: slowly pour the oil phase into the aqueous phase, stir at high speed to form an O / W emulsion, heat to 45℃, add 10 g of ethylenediamine, constant temperature reaction for 3.5h, cool to 30℃, add 6 g of xanthan gum, 2 g of magnesium aluminum silicate, 3 g of isothiazolinone, 3 g of silicone defoaming agent and 70 g of propylene glycol, adjust the pH to 5.6 with 3 g of citric acid, to obtain lambda-cyhalothrin microcapsule suspension concentrate.

[0044] Example 2:

[0045] A lambda-cyhalothrin microcapsule suspension concentrate, comprising the following preparation steps:

[0046] S1: heat 6 g of soybean oil to 68℃, add 9 g of peroxyformic acid, keep the temperature constant for 3h, separate the aqueous phase, wash with pure water until the pH is 6.9, and distill under reduced pressure to obtain epoxy soybean oil;

[0047] S2: add 5 g of the obtained epoxy soybean oil to 10 g of isopropyl alcohol, add 9 g of isopropyl alcohol amine and 1.5 g of tetrafluoroboric acid, stir for 15h, control the temperature at 65℃, wash with saturated sodium sulfate solution, and distill under reduced pressure to obtain soybean polyol;

[0048] S3: under nitrogen protection, heat 50 g of 4,4'-diphenyl methane diisocyanate to 60℃, add 1.5 g of 2,4,6-tris(dimethylaminomethyl)phenol and 25 g of ethyl acetate, control the reaction temperature to keep at 60℃, react until the solution is milky white and the viscosity increases, determine the -NCO content by di-n-butylamine method to be 8.0%, add 35 g of benzoyl chloride, stir for 25 min, wash and dry to obtain isocyanate trimer;

[0049] S4: uniformly mix 40 g of the obtained isocyanate trimer, 45 g of polytetrahydrofuran diol, 7 g of polyethylene glycol monomethyl ether, 0.015 g of dibutyl tin dilaurate and 5 g of acetone, heat to 90℃, add 6 g of soybean polyol prepared in S2, react for 3.6h to obtain polyisocyanate;

[0050] S5: Dissolve 400 g of lambda-cyhalothrin in 380 g of 150# aromatic hydrocarbon solvent oil, add 40 g of polyisocyanate prepared in S4 and 18 g of lecithin, stir uniformly to obtain a uniform oil phase.

[0051] S6: Mix 100 g of fatty alcohol polyoxyethylene ether, 50 g of naphthalene sulfonate formaldehyde condensate sulfonate, 8 g of potassium glycyrrhizinate and 908 g of water, stir uniformly to obtain an aqueous phase.

[0052] S7: Slowly pour the oil phase into the aqueous phase, high-speed stirring, forming an O / W emulsion, warming to 45℃, dropwise addition of 10 g of ethylenediamine, constant temperature reaction for 3.5h, cooling to 30℃, adding 6 g of xanthan gum, 2 g of magnesium aluminum silicate, 3 g of isothiazolinone, 3 g of silicone antifoaming agent and 70 g of propylene glycol, adjusting the pH to 5.6 with 3 g of citric acid, to obtain lambda-cyhalothrin microcapsule suspension concentrate.

[0053] Example 3:

[0054] A lambda-cyhalothrin microcapsule suspension concentrate, comprising the following preparation steps:

[0055] S1: Heat 6 g of soybean oil to 72℃, add 15 g of peroxyformic acid, keep the temperature constant for 5h, separate the aqueous phase, wash with pure water until the pH is 7.0, and distill under reduced pressure to obtain epoxy soybean oil;

[0056] S2: Add 5 g of the obtained epoxy soybean oil to 15 g of isopropyl alcohol, add 10 g of isopropyl alcohol amine and 2 g of tetrafluoroboric acid, stir for 18h, control the temperature at 75℃, wash with saturated sodium sulfate solution, and distill under reduced pressure to obtain soybean polyol;

[0057] S3: Under nitrogen protection, warm 50 g of 4,4'-diphenyl methane diisocyanate to 60℃, add 1.5 g of 2,4,6-tris(dimethylaminomethyl)phenol and 25 g of ethyl acetate, control the reaction temperature to keep at 60℃, react until the solution is milky white and the viscosity increases, determine the -NCO content by di-n-butylamine method to be 8.0%, add 35 g of benzoyl chloride, stir for 25 min, wash and dry to obtain isocyanate trimer;

[0058] S4: Mix 40 g of the obtained isocyanate trimer, 45 g of polytetrahydrofuran diol, 7 g of polyethylene glycol monomethyl ether, 0.25 g of dibutyl tin dilaurate and 5 g of acetone uniformly, heat to 90℃, add 6 g of soybean polyol prepared in S3, react for 3.6h to obtain polyisocyanate;

[0059] S5: 400 g of lambda-cyhalothrin was dissolved in 380 g of 150# aromatic hydrocarbon solvent oil, 40 g of polyisocyanate prepared in S4 and 18 g of lecithin were added, and stirring was performed to obtain a uniform oil phase.

[0060] S6: 100 g of fatty alcohol polyoxyethylene ether, 50 g of naphthalene sulfonate formaldehyde condensate sulfonate, 8 g of potassium glycyrrhizinate and 908 g of water were mixed, and stirring was performed to obtain an aqueous phase.

[0061] S7: The oil phase was slowly poured into the aqueous phase, high-speed stirring was performed to form an O / W emulsion, the temperature was increased to 45℃, 10 g of ethylenediamine was added dropwise, constant temperature reaction was performed for 3.5 h, the temperature was decreased to 30℃, 6 g of xanthan gum, 2 g of magnesium aluminum silicate, 3 g of isothiazolinone, 3 g of silicone antifoaming agent and 70 g of propylene glycol were added, 3 g of citric acid was added, and the pH was adjusted to 5.6 to obtain lambda-cyhalothrin microcapsule suspension.

[0062] Example 4:

[0063] A lambda-cyhalothrin microcapsule suspension includes the following preparation steps:

[0064] S1: 6 g of soybean oil was heated to 68℃, 9 g of peroxyformic acid was added, and constant temperature reaction was performed for 3 h, the aqueous phase was separated, and washing was performed with pure water until the pH was 6.9, and distillation was performed under reduced pressure to obtain epoxy soybean oil;

[0065] S2: 5 g of the obtained epoxy soybean oil was added to 10 g of isopropyl alcohol, 9 g of isopropyl alcohol amine and 1.5 g of tetrafluoroboric acid were added, stirring reaction was performed for 15 h, the temperature was controlled at 65℃, washing was performed with saturated sodium sulfate solution, and distillation was performed under reduced pressure to obtain a soybean polyol;

[0066] S3: Under the protection of nitrogen, 50 g of 4,4'-diphenyl methane diisocyanate was heated to 57℃, 1 g of 2,4,6-tris(dimethylaminomethyl)phenol and 20 g of ethyl acetate were added, the reaction temperature was controlled to be maintained at 57℃, and when the solution was milky white and the viscosity increased, the -NCO content was determined to be 7.9% by using di-n-butylamine method, 3 g of benzoyl chloride was added and stirred for 20 min, and after washing and drying, an isocyanate trimer was obtained;

[0067] S4: 40 g of the obtained isocyanate trimer, 42 g of polytetrahydrofuran diol, 24 g of polyethylene glycol monomethyl ether, 0.2 g of dibutyl tin dilaurate and 4 g of acetone were uniformly mixed, heated to 85℃, 50 g of the soybean polyol prepared in S2 was added, and reaction was performed for 3 h to obtain a polyisocyanate;

[0068] S5: 360 g of lambda-cyhalothrin was dissolved in 300 g of 150# aromatic hydrocarbon solvent oil, 30 g of polyisocyanate prepared in S4 and 20 g of lecithin were added, and stirring was performed to obtain a uniform oil phase.

[0069] S6: 40 g of fatty alcohol polyoxyethylene ether, 30 g of naphthalene sulfonate formaldehyde condensate sulfonate, 10 g of glycyrrhizic acid dipotassium and 1130 g of water were mixed, and stirring was performed to obtain an aqueous phase.

[0070] S7: The oil phase was slowly poured into the aqueous phase, high-speed stirring was performed to form an O / W emulsion, the temperature was raised to 45°C, 8 g of diethylenetriamine was added dropwise, constant temperature reaction was performed for 3 h, the temperature was lowered to 30°C, 3 g of xanthan gum, 1 g of magnesium aluminum silicate, 2 g of isothiazolinone, 4 g of silicone antifoaming agent, 60 g of propylene glycol and 2 g of citric acid were added, the pH was adjusted to 5.5 with water, stirring was performed to obtain lambda-cyhalothrin microcapsule suspension.

[0071] Example 5:

[0072] A lambda-cyhalothrin microcapsule suspension includes the following preparation steps:

[0073] S1: 6 g of soybean oil was heated to 72°C, 15 g of peroxyformic acid was added, and constant temperature reaction was performed for 5 h, the aqueous phase was separated, and washing was performed with pure water until the pH was 7.0, and distillation was performed under reduced pressure to obtain epoxy soybean oil.

[0074] S2: 5 g of the obtained epoxy soybean oil was added to 15 g of isopropyl alcohol, 10 g of isopropyl alcohol amine and 2 g of tetrafluoroboric acid were added, stirring was performed for 18 h, the temperature was controlled at 75°C, washing was performed with saturated sodium sulfate solution, and distillation was performed under reduced pressure to obtain a soybean polyol.

[0075] S3: Under the protection of nitrogen, 50 g of 4,4'-diphenyl methane diisocyanate was heated to 60°C, 1.5 g of 2,4,6-tris(dimethylaminomethyl)phenol and 25 g of ethyl acetate were added, the reaction temperature was controlled to be maintained at 60°C, and when the solution was milky white and the viscosity increased, the -NCO content was determined to be 8.0% by using di-n-butylamine method, 35 g of benzoyl chloride was added, stirring was performed for 25 min, and after washing and drying, an isocyanate trimer was obtained.

[0076] S4: 40 g of the obtained isocyanate trimer, 45 g of polytetrahydrofuran diol, 7 g of polyethylene glycol monomethyl ether, 0.25 g of dibutyl tin dilaurate and 5 g of acetone were uniformly mixed, heating was performed to 90°C, 6 g of the soybean polyol prepared in S2 was added, and reaction was performed for 3.6 h to obtain a polyisocyanate.

[0077] S5: 440 g of lambda-cyhalothrin was dissolved in 500 g of 150# aromatic hydrocarbon solvent oil, 50 g of polyisocyanate prepared in S4 and 30 g of lecithin were added, and stirred uniformly to obtain a uniform oil phase.

[0078] S6: 120 g of fatty alcohol polyoxyethylene ether, 60 g of naphthalene sulfonate formaldehyde condensate sulfonate, 6 g of glycyrrhizic acid dipotassium and 678 g of water were mixed and stirred uniformly to obtain an aqueous phase.

[0079] S7: The oil phase was slowly poured into the aqueous phase, high-speed stirring was performed to form an O / W emulsion, the temperature was raised to 45°C, 14 g of triethylenetetramine was added dropwise, constant temperature reaction was performed for 3 h, the temperature was lowered to 30°C, 4 g of xanthan gum and 2 g of magnesium aluminum silicate, 6 g of isothiazolinone, 6 g of silicone antifoaming agent, 80 g of propylene glycol, 4 g of citric acid were added, the pH was adjusted to 5.5 with citric acid, and stirring was performed uniformly to obtain lambda-cyhalothrin microcapsule suspension.

[0080] Comparative Example 1:

[0081] In this comparative example, compared with Example 1, the step S3 was omitted, and “isocyanate trimer 40 g” was replaced by “4,4'-diphenylmethane diisocyanate 40 g”, and the remaining steps and parameters were the same. The final lambda-cyhalothrin microcapsule suspension was obtained.

[0082] Comparative Example 2:

[0083] In this comparative example, compared with Example 1, polytetrahydrofuran diol was not added in the preparation process of S4, and the remaining steps and parameters were the same. The final lambda-cyhalothrin microcapsule suspension was obtained.

[0084] Comparative Example 3:

[0085] In this comparative example, compared with Example 1, soybean polyol was not added in the preparation process of S4, and the remaining steps and parameters were the same. The final lambda-cyhalothrin microcapsule suspension was obtained.

[0086] Comparative Example 4:

[0087] In this comparative example, compared with Example 1, lecithin was not added in the preparation process of S5 of Example 1, and the remaining steps and parameters were the same. The final lambda-cyhalothrin microcapsule suspension was obtained.

[0088] Comparative Example 5:

[0089] In this comparative example, compared with Example 1, magnesium aluminum silicate was not added in the preparation process of S7 of Example 1, and the remaining steps and parameters were the same. The final lambda-cyhalothrin microcapsule suspension was obtained.

[0090] Performance test:

[0091] Determination of hydroxyl value: The hydroxyl value of the soybean polyol prepared in Examples 1-3 was determined by the method of phthalic anhydride-pyridine, and the detailed results are shown in Table 1.

[0092]

[0093] Performance test experiments were carried out on the lambda-cyhalothrin microcapsule suspensions prepared in Examples 1-5 and Comparative Examples 1-5, and the detection methods of each experimental item are as follows:

[0094] Determination of coating rate: The content of free lambda-cyhalothrin in the lambda-cyhalothrin microcapsule suspensions prepared in Examples 1-5 and Comparative Examples 1-5 was determined by high performance liquid chromatography, and the coating rate was calculated.

[0095] Determination of total pesticide content: 1.0 g of the lambda-cyhalothrin microcapsule suspensions prepared in Examples 1-5 and Comparative Examples 1-5 was precisely weighed, 10 mL of methanol was added, and then it was put into an ultrasonic cell crusher, the capsule was broken by ultrasonic, the ultrasonic time was 30 s, the interval time was 20 s, the working times was 10, and the ultrasonic power was 200. After the capsule was broken by ultrasonic, it was transferred to a 50 mL volumetric flask, diluted with ethanol to the mark and shaken well, filtered, the filtrate was filtered with a 0.45 um filter membrane to obtain a sample, and the pesticide concentration of the sample was detected by HPLC.

[0096] Determination of free pesticide content: 1.0 g of the lambda-cyhalothrin microcapsule suspensions prepared in Examples 1-5 and Comparative Examples 1-5 was precisely weighed, dissolved in 25 mL of ethanol solution, shaken well, then transferred to a 50 mL volumetric flask, diluted with ethanol to the mark and shaken well, filtered, the filtrate was filtered with a 0.45 um filter membrane to obtain a sample, and the pesticide concentration of the sample was detected by HPLC.

[0097] Encapsulation efficiency calculation formula: .

[0098] Determination of suspension rate: The suspension rate of the lambda-cyhalothrin microcapsule suspensions prepared in Examples 1-5 and Comparative Examples 1-5 was determined according to the national standard GB / T14825-2006.

[0099] Determination of microcapsule particle size and distribution:

[0100] The particle size of the microcapsules in the lambda-cyhalothrin microcapsule suspensions prepared in Examples 1-5 and Comparative Examples 1-5 was determined by a laser particle size analyzer, and the D 10 , D 50 and D 90 of the microcapsules were measured, and the dispersion index (Span) was calculated, and the calculation formula of the dispersion index (Span) was:

[0101]

[0102] D90: cumulative distribution of 90%, indicating that 90% of the particle size is less than or equal to this value. 10 D90: cumulative distribution of 90%, indicating that 90% of the particle size is less than or equal to this value. 50 D90: cumulative distribution of 90%, indicating that 90% of the particle size is less than or equal to this value. 90 D90: cumulative distribution of 90%, indicating that 90% of the particle size is less than or equal to this value.

[0103] Formula meaning: numerator D90-D10: indicates the range of particle distribution (span of particle size from 10% to 90%), denominator D50: indicates the median particle size, used to normalize the distribution range, Span measures the relative width of the distribution range relative to the median, the smaller the value, the more concentrated the particle distribution, the higher the uniformity.

[0104] Wet sieve test: according to GB / T1601, take 20g on 200 mesh (75μm) screen, promote its passing through the screen with water flow, then place in oven for drying, weigh the mass that does not pass through the screen, calculate the wet sieve passing percentage.

[0105] Persistent foaming property: test according to GB / T28137, take 1g into a specified cylinder, and make up to 80% of the volume, in 1min, uniformly upside down for 30 times, open the ground glass stopper and stand for 1min, count the foam height.

[0106] Low temperature stability: according to national standard GB / T19136-2003, measure the suspension rate of high-efficiency fluoro-cyphenothrin microcapsule suspending agent prepared in examples 1-5 and comparative examples 1-5.

[0107] Thermal storage stability: according to national standard GB / T19136-2003, measure the suspension rate of high-efficiency fluoro-cyphenothrin microcapsule suspending agent prepared in examples 1-5 and comparative examples 1-5.

[0108] The detection results of high-efficiency fluoro-cyphenothrin microcapsule suspending agent are shown in Table 2.

[0109] Table 2

[0110]

[0111] Stability test:

[0112] Anti-photolysis experiment: 10 mL of high-efficiency lambda-cyhalothrin microcapsule suspensions prepared in Example 1 and Comparative Examples 1-5 were uniformly coated on a glass plate, and after drying, a drug film was formed with a thickness of about 0.1 mm. A UV lamp with a wavelength of 365 nm and a power of 30 W was used to vertically irradiate the sample at a distance of 20 cm for 24 h, 48 h, and 72 h, respectively.

[0113] After each irradiation, the drug film was scraped and dissolved in methanol for ultrasonic extraction for 30 min. After filtration, the residual amount of high-efficiency lambda-cyhalothrin was determined by high-performance liquid chromatography (HPLC), and the degradation rate was calculated. The formula for calculating the degradation rate is: wherein C0is the initial concentration, C t is the concentration after irradiation. The degradation rates after 24 h, 48 h, and 72 h of irradiation were determined, respectively.

[0114] Anti-rainwater erosion experiment: To evaluate the stability and loss of high-efficiency lambda-cyhalothrin microcapsule suspensions under rainwater erosion conditions, the high-efficiency lambda-cyhalothrin microcapsule suspensions prepared in Example 1 and Comparative Examples 1-8 were diluted 100 times and sprayed on the center area of the rice leaf surface to ensure that a uniform drug film was formed on the center area of the leaf surface with a thickness of about 0.1 mm. Note that the leaf edge was not sprayed to avoid loss of the drug solution. The initial concentration of high-efficiency lambda-cyhalothrin in the suspension before spraying was calculated and recorded as C0, and the actual spraying volume was recorded as V0. The total amount of pesticide sprayed was calculated (C0× V0). After the drug film was naturally dried, a simulated rainfall device (nozzle aperture 0.5 mm, water pressure 0.3 MPa) was used to continuously erode the leaf surface for 30 min at a rainfall intensity of 10 mm / h. After the erosion was completed, the residual drug film on the leaf surface was scraped, dissolved in methanol, and ultrasonically extracted to obtain a leaf washing solution. The volume of the washing solution was recorded as V 残留 . The residual concentration of high-efficiency lambda-cyhalothrin in the leaf washing solution was determined by HPLC and recorded as C 残留 . The residual amount on the leaf surface was calculated (C 残留 × V 残留 ). According to the formula for calculating the erosion loss rate, the erosion loss rates of the suspensions in each group were calculated to evaluate their loss under rainwater erosion conditions. The formula for calculating the erosion loss rate is: .

[0115] The degradation rates after 24 h, 48 h, and 72 h of irradiation in the anti-photolysis experiment and the erosion loss rates in the anti-rainwater erosion experiment were recorded, and the detailed results are shown in Table 3.

[0116] Table 3

[0117]

[0118] Skin irritation test: 30 healthy adult white rabbits were selected and randomly divided into 6 groups,

[0119] Before the test, the hair on both sides of the rabbit's back spine was shaved, with a range of 2 cm x 3 cm on both sides, ensuring that the skin was not damaged, and the high-efficiency fluoro-cyphenothrin micro-capsule suspending agent prepared in Example 1 and Comparative Examples 1-5 was evenly applied to the shaved area, with a dose of 0.5 mL per rabbit. After application, the gauze was covered and fixed, and the other side of the rabbit's skin was used as a control. After 3 hours of pesticide contact with the skin, the dressing was removed and the skin was gently washed with warm water.

[0120] After removing the test substance from the surface of the rabbit's skin, the erythema and edema reactions of the rabbit's skin were observed and scored, and the observation time was 1 h, 12 h and 24 h after treatment. The scoring standard is shown in Table 4, and the skin irritation test score is shown in Table 5.

[0121] Table 4

[0122]

[0123] Table 5

[0124]

[0125] Data analysis:

[0126] As can be seen from Tables 1-5, the high-efficiency fluoro-cyphenothrin micro-capsule suspending agent prepared by the present application has high encapsulation rate, suspension rate, stability and anti-irritation.

[0127] The high-efficiency fluoro chlorocyan pyrethroid is a core insecticidal active ingredient, but has the disadvantages of photolysis sensitivity and skin irritation, and the application is coated by a crosslinking network of polyisocyanate to reduce photolysis and direct contact with the skin. The MDI trimer prepared in the application is formed by 3 MDI molecules through an addition reaction, contains multiple -NCO groups, and each molecule contains three -NCO groups, which can react with multiple active hydrogen compounds (such as hydroxyl and amine groups) at the same time to form a highly crosslinked network structure. Compared with synthetic polyols, the crosslinking reaction rate of soybean polyol is slower, and generally requires higher temperature or longer reaction time. The MDI trimer prepared in the application solves the problem of slow crosslinking reaction rate of soybean polyol. Soybean polyol is derived from renewable soybean oil and is a green and sustainable raw material. Soybean polyol is rich in hydroxyl groups. The higher the content of hydroxyl groups, the higher the degree of crosslinking reaction, and the more compact the network structure formed, which can effectively coat the high-efficiency fluoro chlorocyan pyrethroid and improve the encapsulation rate. Secondly, the ether bond and hydroxyl group formed after the ring opening of the epoxy group of the soybean polyol have high chemical stability and can maintain structural stability under high temperature and ultraviolet radiation. Secondly, the epoxy soybean contains a large number of hydrophobic long carbon chains, which can effectively block the penetration of water and oxygen, thereby improving the protection of the active ingredient in the microcapsule. However, these hydrophobic long carbon chains also reduce the hydrophilicity. Polyol tetrahydrofuran diol is a flexible segment, and the introduction of polytetrahydrofuran diol increases the crosslinking point, adjusts the flexibility of the crosslinking network, and improves the flexibility and strength of the microcapsule. Polyethylene glycol monomethyl ether is a hydrophilic ether alcohol compound, and the introduction of polyethylene glycol monomethyl ether adjusts the hydrophilicity of the crosslinking network and improves the dispersibility of the microcapsule in the aqueous phase. Magnesium aluminum silicate has a unique layered structure and good rheological properties. At low concentrations, magnesium aluminum silicate can stabilize the oil-in-water emulsion, and has the effects of thickening, suspension stabilization and thixotropic adjustment.

[0128] As can be seen from Table 5, the total irritation score of Comparative Example 4 is significantly improved compared with Example 1 due to the absence of soft phospholipid. The soft phospholipid has amphoteric properties, the head of the soft phospholipid molecule contains phosphocholine groups, which have hydrophilicity and can interact with water molecules. The tail of the lecithin molecule is composed of two fatty acid chains, which have lipophilicity and can interact with the components in the oil phase, so that the soft phospholipid is distributed on the interface between the oil phase and the water phase. The lipophilic tail of lecithin will be embedded in the oil phase, while the hydrophilic head will stretch towards the water phase, so that lecithin can form a protective film to reduce the direct contact of the solvent in the oil phase with the skin, thereby reducing skin irritation.

[0129] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Within the scope of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

[0130] The present invention is intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An efficient lambda-cyhalothrin microcapsule suspension characterized in that, The high-efficiency lambda cyhalothrin microcapsule suspension agent is made of the following components by weight percentage: high-efficiency lambda cyhalothrin 18%-22%, 150# aromatic hydrocarbon solvent oil 15%-25%, polyisocyanate 1.5%-2.5%, polyamine 0.4%-0.7%, lecithin 1%-3%, glycyrrhizic acid dipotassium 0.3%-0.5%, emulsifier 4%-6%, dispersant 1.5%-3%, water thickening agent 0.2%-0.3%, preservative 0.1%-0.3%, defoaming agent 0.1%-0.3%, antifreeze 3%-4%, pH regulator 0.1%-0.3%, and water to 100%; The preparation method of the polyisocyanate is as follows: under nitrogen protection, 4,4'-diphenyl methane diisocyanate is warmed to 57-65 DEG C, 4,4'-diphenyl methane diisocyanate is dissolved, ethyl acetate and 2,4,6-tris (dimethyl aminomethyl) phenol are added, benzoyl chloride is added after the reaction is completed, and the isocyanate trimer is obtained after washing and drying; the isocyanate trimer, polytetrahydrofuran diol, polyethylene glycol monomethyl ether, dibutyl tin dilaurate and acetone are uniformly mixed, heated to 85-95 DEG C, soybean polyol is added, and the polyisocyanate is obtained after 3-4 h of reaction; The water thickening agent is obtained by compounding magnesium aluminum silicate and xanthan gum, and the mass ratio of magnesium aluminum silicate to xanthan gum is 1:2-3; The preparation method of the soybean polyol is as follows: soybean oil is heated to 68-72 DEG C, peroxoacetic acid is added to the soybean oil, the reaction is kept for 3-5 h, the water phase is separated, washing is performed until the pH is 6.8-7.2, and the epoxy soybean oil is obtained by distillation under reduced pressure; the epoxy soybean oil is added to isopropyl alcohol, isopropyl amine and tetrafluoroboric acid are added, the reaction is stirred, the temperature is controlled at 65-75 DEG C, the reaction is performed for 15-18 h, washing is performed with saturated sodium sulfate solution, and the soybean polyol is obtained by distillation under reduced pressure; The emulsifier is a fatty alcohol polyoxyethylene ether; The polyamine is at least one of ethylenediamine, diethylenetriamine and triethylenetetramine; The dispersant is naphthalene sulfonate formaldehyde condensate sulfonate; The defoaming agent is an organic silicon defoaming agent, the preservative is isothiazolinone, the antifreeze is propylene glycol, and the pH regulator is citric acid monohydrate.

2. A process for the preparation of the high efficiency lambda cyhalothrin microcapsule suspension as claimed in claim 1, characterized in that, The following preparation steps are included: Step S1: high-efficiency lambda cyhalothrin is dissolved in 150# aromatic hydrocarbon solvent oil, polyisocyanate and lecithin are added, and the oil phase is uniformly stirred; Step S2: the emulsifier, dispersant, glycyrrhizic acid dipotassium and water are mixed, and the water phase is uniformly stirred; Step S3: the oil phase is slowly poured into the water phase, high-speed stirring is performed, the O / W emulsion is formed, the temperature is increased to 45 DEG C, the polyamine is added dropwise, the constant temperature reaction is performed for 3-4 h, the temperature is decreased to 30 DEG C, the water thickening agent, preservative, defoaming agent and antifreeze are added, the pH is adjusted to 5.5-5.8 with citric acid monohydrate, and the high-efficiency lambda cyhalothrin microcapsule suspension agent is obtained after uniform stirring.

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