CN117378605A

CN117378605A - Pyrethroid pesticide microcapsule suspending agent and preparation method thereof

Info

Publication number: CN117378605A
Application number: CN202311694316.0A
Authority: CN
Inventors: 曾章华; 陈龙; 崔博; 高飞; 崔海信
Original assignee: Institute of Environment and Sustainable Development in Agriculturem of CAAS
Current assignee: Institute of Environment and Sustainable Development in Agriculturem of CAAS
Priority date: 2023-12-12
Filing date: 2023-12-12
Publication date: 2024-01-12
Anticipated expiration: 2043-12-12
Also published as: CN117378605B

Abstract

The invention discloses a pyrethroid pesticide microcapsule suspending agent and a preparation method thereof. The preparation method comprises the following steps: (1) Melting pyrethrin pesticide, adding isophorone diisocyanate and dibutyl tin dilaurate, and stirring and mixing to obtain oil phase; (2) Diluting the sulfonated cellulose nanocrystalline with water to obtain a water phase; (3) Adding the oil phase into the water phase, shearing, homogenizing, solidifying and cooling to obtain pyrethroid pesticide microcapsule. The pesticide prepared by the invention has the advantages of low cost, environmental protection, low residual quantity, high safety and high application efficacy. The invention provides a new research and development idea and a new technical basis for the development of novel pesticides.

Description

Pyrethroid pesticide microcapsule suspending agent and preparation method thereof

Technical Field

The invention belongs to the technical field of pesticide preparations, and particularly relates to a pyrethroid pesticide microcapsule suspending agent and a preparation method thereof.

Background

Effective pest and disease management is critical to the protection of crop yields, for which millions of tons of pesticides are applied annually worldwide. Traditional pesticide formulations, such as emulsifiable concentrates, suspending agents and powders, are susceptible to environmental hazards due to inefficiency. In recent years, new technologies are continuously emerging, including development of novel pesticide adjuvants, novel pesticide adjuvants and intelligent delivery systems. These innovations aim to minimize pesticide drift, runoff and degradation while achieving precise delivery of the pesticide. Encapsulation of pesticidal active ingredients plays a key role in achieving these objectives.

Pesticide encapsulation has a number of advantages, including reduced toxic odors, reduced risk of acute poisoning, and increased light and heat stability. In a typical encapsulation process, a water-insoluble pesticide is first dissolved in an organic solvent and then immobilized by electrostatic, hydrophobic, or complexation forces, etc. The prior encapsulation technology is mainly divided into two main categories (1) the pore canal of mesoporous silicon, metal organic framework, clay mineral and other materials is utilized to adsorb pesticide active ingredients. (2) The active ingredients are fixed in the polymer or the amphipathic molecule by using the anti-solvent method or the emulsifying solvent evaporation method and other technologies to form micro/nanospheres, micro/nanocapsules, micelles and other similar structures.

Interfacial polymerization is the most commonly used technology for preparing pesticide microcapsules. This process typically dissolves both monomers in the oil and water phases. When the emulsion is formed, these monomers crosslink and cure at the oil-water interface, forming a polymer shell. For example: the patent with publication number of CN114208831A discloses a pesticide microcapsule suspending agent, which comprises the following raw materials in parts by weight: 1-40% of pesticide active ingredient, 10-30% of oil phase solvent, 1-10% of capsule wall material, 1-5% of magnesium aluminum silicate, 40-80% of water and other auxiliary agents acceptable by pesticide microcapsule suspending agent. The patent with publication number of CN113016792A discloses a polyurethane pesticide microcapsule suspending agent which is prepared from the following raw materials in parts by weight: 1-5 parts of isophorone diisocyanate; 1-25 parts of pesticide raw materials; 5-15 parts of an organic solvent; 20-50 parts of deionized water; 1-10 parts of an emulsifier; 1.5-20 parts of polyether polyol; 0.1-0.5 parts of dibutyl tin dilaurate; 1-10 parts of chain extender.

However, the preparation of the existing pesticide microcapsules has the following defects:

1. recovery of the organic solvent used to dissolve the active ingredient requires expensive environmental protection equipment.

2. The size of the microcapsules is generally determined by the size of the emulsion droplets. In order to improve the permeability and the adhesiveness of the blades, various surfactants are often added into the water phase in the emulsification process to generate smaller microcapsules, which is easy to cause adverse effects on the environment.

3. At present, the preparation of pesticide microcapsules mainly takes non-biodegradable total-synthesis polymer materials as microcapsule materials, such as polyurea, urea-formaldehyde resin, melamine, formaldehyde resin and the like. The capsule wall material is difficult to degrade, and pesticide cannot be completely released, so that the pesticide effect is low and the pesticide residue is large.

Disclosure of Invention

In order to solve the technical problems, the application efficiency of pesticides is improved, the pesticide residue and the production cost are reduced, and the environmental pollution is reduced. The invention is realized by the following technical scheme.

In a first aspect, the invention provides a pyrethroid pesticide microcapsule suspending agent, which is prepared from the following raw materials in parts by weight: pyrethroid pesticide, isophorone diisocyanate, dibutyl tin dilaurate, sulfonated cellulose nanocrystals, water=100:3-30:0.15-1.5:1-10:800-1200.

Preferably, the pyrethroid pesticide microcapsule suspending agent is prepared from the following raw materials in parts by weight: pyrethroid pesticide, isophorone diisocyanate, dibutyl tin dilaurate, sulfonated cellulose nanocrystals, water=100:5-20:0.25-1.0:2-8:900-1100.

Preferably, the thickness of the pyrethroid pesticide microcapsule is 10-100 nm, more preferably 20-80 nm, for example: 10 nm, 14 nm, 17 nm, 20nm, 24 nm, 27 nm, 30 nm, 34 nm, 37 nm, 40nm, 44 nm, 47 nm, 50 nm, 54 nm, 57 nm, 60nm, 64 nm, 67 nm, 70 nm, 74 nm, 76 nm, 80nm, 84 nm, 87 nm, 90 nm, 94 nm, 97 nm, 100nm.

In a second aspect, the invention provides a method for preparing the pyrethroid pesticide microcapsule suspending agent. The method takes the directly melted low-melting-point pyrethroid pesticide as a hydrophobic oil phase, so that the pyrethroid pesticide has the function of a solvent. In addition, the method replaces the traditional surfactant with solid particles with nanometer or micrometer size, thereby avoiding the influence of the surfactant on the environment. The inventor skillfully combines the technologies of heating and melting, nano material assisted emulsification and interfacial polymerization, and designs and develops a low-cost and environment-friendly preparation method aiming at low-melting-point pesticide microcapsules, wherein the preparation method comprises the following steps:

(1) Melting pyrethrin pesticide, adding isophorone diisocyanate and dibutyl tin dilaurate, and stirring and mixing to obtain oil phase;

(2) Diluting the sulfonated cellulose nanocrystalline with water to obtain a water phase;

(3) And adding the oil phase into the water phase, and shearing, homogenizing, solidifying and cooling to obtain the pyrethroid pesticide microcapsule.

Preferably, both steps (1) and (3) are carried out at a temperature above the melting point of the pyrethroid pesticide.

Further preferably, the difference between the temperature and the melting point of the pyrethroid pesticide is 0-15 ℃, and more preferably 5-15 ℃. For example: 0 ℃, 1 ℃, 2 ℃,3 ℃, 4 ℃, 5 ℃, 6 ℃, 7 ℃, 8 ℃,9 ℃, 10 ℃, 11 ℃, 12 ℃, 13 ℃, 14 ℃, 15 ℃.

Preferably, the pyrethroid pesticide comprises permethrin, tetramethrin, cypermethrin, cyhalothrin, fenvalerate, tefluthrin, bifenthrin, beta-cyhalothrin, etc.

Preferably, the pyrethroid pesticide is any one or a combination of more of permethrin, tetramethrin, cypermethrin, cyhalothrin, ethofenprox, tefluthrin, bifenthrin or lambda-cyhalothrin. Further preferred are ethofenprox, bifenthrin or lambda-cyhalothrin.

Preferably, in the oil phase, the mass ratio of isophorone diisocyanate to the pyrethroid pesticide is 3-30:100, and more preferably 5-25:100. For example: 3:100, 5:100, 8:100, 10:100, 15:100, 20:100, 25:100, 30:100.

Preferably, in the oil phase, the mass ratio of the dibutyl tin dilaurate to the pyrethroid pesticide is 0.15-1.5:100, and more preferably 0.2-1.0:100. For example: 0.15:100, 0.2:100, 0.25:100, 0.3:100, 0.4:100, 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100, 1.0:100, 1.1:100, 1.2:100, 1.3:100, 1.4:100, 1.5:100.

Preferably, in the oil phase, the mass ratio of the sulfonated cellulose nanocrystalline to the pyrethroid pesticide is 1-10:100, and more preferably 2-8:100. For example: 1:100, 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, 10:100.

Preferably, in the aqueous phase, the mass percentage of the sulfonated cellulose nanocrystalline is 0.1-1%. For example: 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%.

Preferably, the water is selected from one or more of distilled water, pure water, deionized water.

Preferably, in the step (3), the rotation speed of the shearing is 10000-15000 rpm, for example: 10000 rpm, 11000 rpm, 12000 rpm, 13000 rpm, 14000 rpm, 15000 rpm.

Preferably, the shearing time is 1-3 min, for example: 1 min, 1.5 min, 2 min, 2.5 min, 3 min.

Preferably, in the step (3), the homogenizing pressure is 400 to 600 bar, for example: 400 bar, 450 bar, 500 bar, 550 bar, 600 bar.

Preferably, the homogenized flow rate is 30-60 mL/min, for example: 30 mL/min, 35 mL/min, 40 mL/min, 45 mL/min, 50mL/min, 55 mL/min, 60 mL/min.

Preferably, the homogenizing time is 5-15 min, for example: 5 min, 7 min, 10 min, 13 min, and 15 min.

Preferably, in the step (3), the stirring speed of the solidification is 150-450 rpm, for example: 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450rpm.

Preferably, the curing time is 8-15 hours, for example: 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h, 15 h.

In the step (3), the factors such as the shearing rotation speed, the shearing time, the average pressure, the homogenizing flow rate, the homogenizing time, the curing rotation speed and the curing time are not particularly limited, so long as the oil phase and the water phase can be uniformly dispersed, and the thickness of the pesticide microcapsule is controlled to be 10-100 nm.

In a third aspect, the invention provides the use of a pyrethroid pesticide microcapsule suspension in controlling agricultural pests.

Preferably, the pest is cabbage caterpillar, plutella xylostella, cotton bollworm, etc., and more preferably plutella xylostella.

In a fourth aspect, the present invention provides the use of the above-described preparation method for the development of novel pesticide formulations.

The invention has the beneficial effects that:

1. the invention takes low-melting-point pyrethroid pesticide and nano solid particles as main raw materials, combines the heating and melting, nano material auxiliary emulsification and interfacial polymerization technology, and prepares the pesticide microcapsule suspending agent with low cost and environmental protection.

2. The invention fully utilizes the characteristics of low-melting-point pyrethrin pesticides, utilizes the heating to melt the pyrethrin pesticides, adds isophorone diisocyanate and dibutyltin dilaurate as oil phases, and avoids the influence of adding organic solvents on the environment and the increase of preparation cost in the preparation of the existing pesticide microcapsules.

3. In the preparation process of the invention, no surfactant is added, so that the preparation cost is reduced, and the potential influence of the surfactant on non-target organisms is avoided.

4. The pyrethroid microcapsule suspending agent prepared by the invention can be degraded under natural conditions, and has low residual quantity, high safety and high application efficacy. The invention provides a new research and development idea and a new technical basis for the development of novel pesticides.

Drawings

FIG. 1 shows scanning electron microscope images of microcapsule samples 1-3, in which a represents sample 1, b represents sample 2, and c represents sample 3;

FIG. 2 shows transmission electron microscope images of microcapsule samples 1-3, in which a represents sample 1, b represents sample 2, and c represents sample 3;

FIG. 3 shows the release profile of beta-cyhalothrin in microcapsules;

FIG. 4 shows a scanning electron microscope image of microcapsules after storage at 4℃and 54℃for 7 days, 14 days;

FIG. 5 shows a scanning electron microscope image of microcapsules after 30 days of storage at room temperature;

FIG. 6 shows a scanning electron microscope image of a microcapsule after 14 days of outdoor placement;

FIG. 7 shows a scanning electron microscope image of a microcapsule after being left outdoors for 21 days;

FIG. 8 shows the number of rounds of scratching after application of the drug solution to the skin surface of the mice.

Detailed Description

The technical scheme of the present invention will be further described with reference to the following examples and the accompanying drawings, and advantages and features of the present invention will be more apparent with the description. It should be understood that the embodiments are illustrative only and should not be taken as limiting the scope of the invention.

The experimental methods used in the following examples are conventional in the art unless otherwise specified.

Example 1 preparation of sulfonated cellulose nanocrystals.

1.1 washing 15 g cotton with deionized water and drying in an oven at 60 ℃. Then 4 h was bleached in 500mL of 1% sodium hypochlorite solution. The cotton was rinsed with deionized water and dried again in an oven at 60 ℃ for 4 h.

1.2 10 g bleached cotton was weighed and hydrolyzed in 100mL of 30 strength sulfuric acid in water 4 h. The hydrolysis mixture was then diluted with 100ml of water and cooled rapidly in an ice bath, and the pH of the mixture was adjusted to 6-7 with sodium hydroxide.

1.3 sonicating the mixture for 30 min under the following ultrasound conditions: 2 seconds on, 1 second off, 30KHz. And filtering and separating the mixture, washing filter residues with deionized water and ethanol, and then drying in a vacuum oven at 60 ℃ to obtain the sulfonated cellulose nanocrystalline.

Example 2 preparation of beta-cyhalothrin microcapsule suspension sample 1.

2.1 weighing 20. 20 g high-efficiency cyhalothrin, melting at 60 ℃, adding 1.1 g isophorone diisocyanate and 0.05g dibutyltin dilaurate, and uniformly mixing to obtain an oil phase.

2.2 adding the 1 g sulfonated cellulose nanocrystalline into 199 g water, stirring for 30 min at 60 ℃, and uniformly dispersing to obtain a water phase.

2.3 adding the oil phase to the water phase at 60℃and shearing at 13000 rpm for 2 min to give a milky colostrum. The colostrum is then homogenized cyclically for 10 min at a pressure of 500 bar and a flow rate of 50 mL/min. And stirring and solidifying the re-emulsion solution at 60 ℃ and 300 rpm for 10 h, and cooling to room temperature to obtain the high-efficiency cyfluthrin microcapsule suspension sample 1.

Example 3 preparation of beta-cyhalothrin microcapsule suspension sample 2.

The specific preparation was the same as in example 2, except that isophorone diisocyanate was 2g and dibutyltin dilaurate was used in an amount of 0.1 g. And preparing the beta-cyhalothrin microcapsule suspension sample 2.

Example 4 preparation of beta-cyhalothrin microcapsule suspension sample 3.

The specific preparation was the same as in example 2, except that isophorone diisocyanate was 4 g and dibutyltin dilaurate was used in an amount of 0.2 g. And preparing the beta-cyhalothrin microcapsule suspension sample 3.

Example 5 preparation of bifenthrin microcapsule suspension samples.

5.1 weighing 20. 20 g bifenthrin, melting at 80 ℃, adding 4. 4 g isophorone diisocyanate and 0.2. 0.2 g dibutyltin dilaurate, and uniformly mixing to obtain an oil phase.

5.2 adding the 1 g sulfonated cellulose nanocrystalline into 199 g water, stirring for 30 min at 80 ℃, and uniformly dispersing to obtain a water phase.

5.3 adding the oil phase to the water phase at 80℃and shearing at 13000 rpm for 2 min to give a milky colostrum. The colostrum is then homogenized cyclically for 10 min at a pressure of 500 bar and a flow rate of 50 mL/min. And stirring and solidifying the re-emulsion solution at 80 ℃ and 300 rpm for 10 h, cooling to room temperature to obtain a bifenthrin microcapsule suspension sample, and observing the sample by a scanning electron microscope, wherein the shell thickness of the microcapsule is 80 nm.

Example 6 preparation of samples of ethofenprox microcapsule suspension.

6.1 weighing 20 g ethofenprox, melting at 45 ℃, adding 4 g isophorone diisocyanate and 0.2 g dibutyltin dilaurate, and mixing to obtain an oil phase.

6.2 adding the 1 g sulfonated cellulose nanocrystalline into 199 g water, stirring for 30 min at 45 ℃, and uniformly dispersing to obtain a water phase.

6.3 adding the oil phase to the water phase at 45℃and shearing at 13000 rpm for 2 min to give a milky colostrum. The colostrum is then homogenized cyclically for 10 min at a pressure of 500 bar and a flow rate of 50 mL/min. And stirring and solidifying the re-emulsion solution at 80 ℃ and 300 rpm for 10 h, cooling to room temperature to obtain a ethofenprox microcapsule suspension sample, and observing the ethofenprox microcapsule suspension sample by a scanning electron microscope, wherein the shell thickness of the microcapsule is 64 nm.

Example 7 performance experiments of samples of beta-cyhalothrin microcapsule suspension.

7.1 morphology observations of microcapsule suspension

7.1.1 sucking 20 mu L of the microcapsule suspension prepared in examples 2-4 respectively, injecting into 4 mL deionized water, uniformly dispersing, sucking 4 mu L, and spotting on a copper wire. After natural drying, the morphological characteristics of the microcapsule suspending agent samples are observed by a transmission electron microscope, the results are shown in figure 1, the samples 1, 2 and 3 are all spherical, the diameter is mainly between 250 nm and 1000 nm, and the number of microcapsules with larger diameter is increased along with the reduction of isophorone diisocyanate content.

7.1.2 sucking 4 mu L of the diluted suspending agent, spotting on a silicon wafer, naturally airing, and observing the three-dimensional morphological characteristics of the microcapsule by using a scanning electron microscope, wherein the result is shown in figure 2. The shell thicknesses of sample 1, sample 2, and sample 3 were 24 nm, 34 nm, and 76 nm, respectively.

7.2 Microcapsule embedding rate and drug loading rate test

The microcapsule solution was centrifuged at 10,000 rpm for 10 min to remove the supernatant, 50% ethanol was added and dispersed by sonication. The process was repeated twice, and the unencapsulated lambda-cyhalothrin was washed off and freeze-dried. 10mg of dry powder was dispersed in 5 mL acetone, sonicated 2 h, and incubated overnight at room temperature. And then the content of the beta-cyhalothrin is measured by a High Performance Liquid Chromatography (HPLC). Encapsulation Efficiency (EE) is defined as the ratio of the amount of beta-cyhalothrin in the microcapsules after washing with ethanol to the amount of beta-cyhalothrin in the unwashed microcapsule powder, and drug loading is defined as the ratio of the mass of beta-cyhalothrin encapsulated in the microcapsules to the total mass of the microcapsules.

The results show that the encapsulation efficiency of the beta-cyhalothrin in the sample 1, the sample 2 and the sample 3 is 88 percent, 98 percent and 99 percent respectively, the drug loading rate is 80 percent, 86 percent and 79 percent respectively, the encapsulation efficiency is increased along with the increase of the carrier content, and the mass ratio of the drug loading to the components in the oil phase is the beta-cyhalothrin: isophorone diisocyanate: dibutyl tin dilaurate=100:10:0.5 to 86%.

7.3 Release Performance test of microcapsule suspension

5. Mu.L of cellulase (700U/mL, from Lishi xylanase, available from Aba Ding Shenghua technology Co., ltd.) was added to the microcapsule solution (beta-cyhalothrin content 4 mg/mL) to give microcapsule solution 5 mL having cellulase activity of 7U/mL. The solution was incubated at room temperature for 12. 12 h, then placed in a dialysis bag (MWCO: 3500 Da) immersed in 100mL of 40% acetonitrile in water. The solution was released by shaking 72. 72 h at 35℃and 1 mL of 40% acetonitrile in water was aspirated at 1 h, 3 h, 6h, 9 h, 12 h, 24 h, 36 h, 48 h, 72 h, 96h, respectively, and the dialysis system was rapidly supplemented with corresponding volumes of slow-release medium. The concentrations of lambda-cyhalothrin in the samples taken at each time point were determined by high performance liquid chromatography, while the microcapsule solution without cellulase added (lambda-cyhalothrin content 4 mg/mL) was used as a control. And calculating to obtain the accumulated release amount and the accumulated release curve. The results are shown in FIG. 3.

As can be seen from fig. 3, the release rate of beta-cyhalothrin in the microcapsules gradually slows down over time, following a diffusion pattern. The cumulative release rate of the beta-cyhalothrin in the blank control is 30.33% in 72 h, and the cumulative release rate of the beta-cyhalothrin in the microcapsule treated by the cellulase is 36.98%. The difference between the two curves is counted by a non-model dependent method, and the difference factor f1 of the two curves is 16.32 and is larger than 15, so that obvious difference exists, and the release of the beta-cyhalothrin has responsiveness. The reason is that the sulfonated cellulose nanocrystals in the microcapsules are degraded by cellulase enzymes, resulting in disintegration of the microcapsule shells. The high-efficiency cyhalothrin microcapsule suspending agent prepared by the invention has good microbial degradation performance, and can be completely degraded by microorganisms producing cellulase under natural environment.

7.4 storage stability test of microcapsule suspension

7.4.1 samples 1-3 of the suspension of the beta-cyhalothrin microcapsules were stored at 4℃and 54℃for 7d and 14d, respectively, and the morphology and size were observed by a scanning electron microscope, and the results are shown in FIG. 4.

7.4.2 the sample 3 of the suspension of the beta-cyhalothrin microcapsule is placed at 25 ℃ and stored for 30d, and the appearance and the size of the sample are observed by a scanning electron microscope, and the result is shown in figure 5.

As can be seen from fig. 4, the shape and size of the microcapsules are not changed after the microcapsules are stored for 7d and 14d in a low-temperature and high-temperature environment, and the microcapsules have good stability. As can be seen from fig. 5, the microcapsules maintain their original morphology and size after 30d storage at room temperature (25 ℃). The high-efficiency cyhalothrin microcapsule suspending agent prepared by the invention has strong adaptability to the environment temperature, wide storage temperature range and high storage stability.

7.5 degradation of microcapsules

10% polyvinyl alcohol (PVA) solution was poured into a petri dish and dried to form a film with a smooth surface. The 100-fold microcapsule solution of the beta-cyhalothrin microcapsules was diluted with deionized water and carefully sprayed onto the film surface using a sprayer. The films were placed in a transparent petri dish and exposed to outdoor conditions for 3 weeks. Small portions of the film were cut off at 14d and 21d, respectively, and the morphology of the microcapsules was observed by scanning electron microscopy. The results are shown in FIGS. 6 and 7.

As can be seen from fig. 6 and 7. The microcapsules were degradable in an outdoor environment, and after 14 days of cumulative exposure, the larger diameter microcapsules ruptured and the remaining particles bound together. Spherical microcapsules were barely visible after 21 days of cumulative exposure. The high-efficiency cyhalothrin microcapsule prepared by the method can be naturally degraded in a short period under natural conditions, and has low residue and high environmental friendliness.

Example 8 insecticidal Activity and safety experiments on samples of beta-cyhalothrin microcapsule suspension.

8.1 Comparative analysis of biological toxicity in microcapsule suspending agent chamber

The insecticidal activity of samples 1-3 of the beta-cyhalothrin microcapsule suspension was evaluated using a spray method, and commercially available beta-cyhalothrin Suspensions (SC) and Emulsifiable Concentrates (EC) were used as control groups. The pesticides were formulated with deionized water to 6 concentration gradients, and then solutions of different concentrations (2 mL each) were sprayed into petri dishes containing 10 three-year-old plutella xylostella and their feeds using a baud spray tower. Three biological replicates were established and mortality of plutella xylostella was recorded after 48 hours of treatment, and the results are shown in table 1.

As can be seen from Table 1, the microcapsule suspending agent prepared by the method has no obvious difference between the relative toxicity of the plutella xylostella and the commercial preparation, and has high application efficacy.

8.2 Comparative analysis of behavior of pruritus of mice caused by microcapsule suspending agent

C57 male mice (body weight 20+ -2 g) were selected at 25℃,The mice were kept in a 12 hour light/dark environment and were free to obtain food and water. After 24 hours of acclimatization, the hair on one side of the mouse body (between the ear and the hind leg) was shaved off, exposing the surface skin (area about 6 cm ² ) Mice were acclimatized to the cage for 30 min. 200 mu L of the beta-cyhalothrin microcapsule solution with the concentration of 0.05% is taken and lightly smeared on the exposed skin of a mouse, and the beta-cyhalothrin emulsifiable concentrate with the concentration of 0.05% is used as a control treatment. After the mice are adapted for 2 min, the mice are placed in a container of a pruritus behavior recorder, the scratching times of the mice within 30 min are automatically counted through a visual scratch scratching behavior analysis system, and the result is shown in fig. 8.

As can be seen in FIG. 8, mice with skin surfaces coated with a commercial dilution of bifenthrin cream showed a pronounced itching response with intermittent scratching of the treated area with the hind paws. Whereas mice coated with the microcapsule formulations showed reduced itching response with significantly reduced scratch rounds. The high-efficiency cyhalothrin microcapsule prepared by the invention can reduce the irritation to skin, improve the safety and relieve the adverse effect of drifting pesticides on a user during application.

8.3 Toxicity comparison analysis of microcapsule suspending agent zebra fish

The toxicity of the beta-cyhalothrin microcapsule sample 3 to zebra fish was evaluated using a static method, while the commercially available beta-cyhalothrin Emulsifiable Concentrate (EC) was used as a control. 2 pesticide preparations are diluted into liquid medicines with different concentrations by using tap water after circulating filtration for 24 hours, 10 zebra fishes (with the length of 2-3 cm) are put in the liquid medicines, the tap water is used as a blank control, three biological replicates are arranged, and the mortality rate of the zebra fishes in the liquid medicines after 96 hours is recorded, and the results are shown in Table 2.

As can be seen from Table 2, the LC of the microcapsule suspension and the commercial emulsifiable concentrate was obtained 96 hours after zebra fish was exposed to the pesticide formulation ₅₀ The toxicity of the beta-cyhalothrin is obviously reduced after the beta-cyhalothrin is encapsulated by the microcapsules, which are respectively 0.39 mug/mL and 0.20 mug/mL. The high-efficiency fluorochlorocyanogen prepared by the inventionThe pyrethrin microcapsule suspending agent has low toxicity and high environmental friendliness.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the scope of the technical concept of the present invention, and all the simple modifications belong to the protection scope of the present invention.

Claims

1. A pyrethroid pesticide microcapsule suspending agent is characterized in that: the pyrethroid pesticide microcapsule suspending agent is prepared from the following raw materials in parts by weight: pyrethroid pesticide, isophorone diisocyanate, dibutyl tin dilaurate, sulfonated cellulose nanocrystals, water=100:3-30:0.15-1.5:1-10:800-1200.

2. The pyrethroid pesticide microcapsule suspension according to claim 1, wherein: the thickness of the pyrethroid pesticide microcapsule is 10-100 nm.

3. A preparation method of a pyrethroid pesticide microcapsule suspending agent is characterized by comprising the following steps: the preparation method comprises the following steps:

(1) Melting pyrethrin pesticide at the temperature of 0-15 ℃ higher than the melting point of Yu Ju ester pesticide, adding isophorone diisocyanate and dibutyltin dilaurate, and stirring and mixing to obtain an oil phase;

(2) Diluting the sulfonated cellulose nanocrystalline with water under the condition of 0-15 ℃ of high Yu Ju ester pesticide melting point to obtain a water phase;

4. A method for preparing pyrethroid pesticide microcapsule suspension according to claim 3, characterized in that: in the oil phase, the mass ratio of isophorone diisocyanate to the pyrethroid pesticide is 3-30:100, the mass ratio of dibutyltin dilaurate to the pyrethroid pesticide is 0.15-1.5:100, and the mass ratio of sulfonated cellulose nanocrystalline to the pyrethroid pesticide is 1-10:100.

5. A method for preparing pyrethroid pesticide microcapsule suspension according to claim 3, characterized in that: in the water phase, the mass percentage of the sulfonated cellulose nanocrystalline is 0.1-1%.

6. A method for preparing pyrethroid pesticide microcapsule suspension according to claim 3, characterized in that: the shearing speed is 10000-15000 rpm, and the shearing time is 1-3 min.

7. A method for preparing pyrethroid pesticide microcapsule suspension according to claim 3, characterized in that: the average pressure is 400-600 bar, the homogenizing flow rate is 30-60 mL/min, and the homogenizing time is 5-15 min.

8. A method for preparing pyrethroid pesticide microcapsule suspension according to claim 3, characterized in that: the stirring rotation speed of the solidification is 150-450 rpm, and the solidification time is 8-15 h.