Preparation process of double-membrane microcapsule suspending agent

Abstract

The invention discloses a preparation process of a double-membrane microcapsule suspending agent. The preparation process comprises the following steps: preparing an oil phase; preparing a water phase; forming an emulsion; forming a first layer of film; forming a double-membrane microcapsule; blending a final product; the bifenthrin and the thiacloprid are wrapped in a unique double-membrane structure, so that the pesticide can be slowly released, the lasting period is long, and the pesticide application frequency is reduced; the pesticide composition has the advantages of increasing the attachment and deposition of the pesticide, improving the transmission performance of the pesticide to a target, reducing the droplet bounce, improving the utilization rate of the pesticide, reducing the influence on the environment and having important significance on the reduction and synergism of the pesticide, and can improve the control effect and effectively help the forestry to reduce unnecessary extra disasters for the prevention and treatment of forestry insect pests; according to the insecticidal composition, the quality of the whole forestry is improved while the forestry treatment cost is saved, two pesticides with different action mechanisms are compounded, the defects of a single pesticide are overcome, the drug resistance of pests is reduced, the insecticidal range is expanded, and the insecticidal activity is higher.

Description

Technical Field

[0001] The present invention relates to the technical field of pesticide preparation processes, and specifically to a preparation process for a double-membrane microcapsule suspension concentrate. Background Art

[0002] Forests play a dominant role in the terrestrial ecosystem, undertaking important functions such as purifying the air, removing dust and preventing pollution, conserving water sources, maintaining biodiversity, and regulating the climate, and are the guarantee for human survival. With the emergence of problems such as global warming, declining biodiversity, and frequent occurrence of forest pests and diseases, people have gradually started to pay attention to the protection of forest resources. China has rich forest resources, with a large total area, but uneven distribution among regions and a small per capita possession. The results of the eighth national forest resources survey show that China's forest area is 208 million hectares, ranking fifth in the world, with a forest coverage rate of 21.63%, and the area of artificial afforestation is 69 million hectares, ranking first in the world. China has to meet the living needs of about 22% of the world's population with about 3.9% of the world's forest resources, and also meet the needs of China's social and economic development, as well as maintain the ecological environment needs of about 7.2% of the world's land. Therefore, it is necessary to establish a scientific forest management concept, improve the quality and efficiency of forests, ensure the sustainable development of forests, and safeguard ecological security.

[0003] Forest fires, illegal logging, and pests and diseases are the three major disasters affecting forestry development and threatening forestry security. Forestry pests and diseases are known as the "smokeless fire", showing the severity of their harm. According to statistics, due to the frequent occurrence of various pests and diseases in forestry resources, the average annual loss exceeds 110 billion yuan. Pests in the forestry field are characterized by great difficulty in prevention and control, a large number of species, and strong drug resistance. Common pests in forestry include longhorn beetles, pine caterpillars, and tent caterpillars. The main prevention and control methods include plant quarantine, biological control, and chemical control. Plant quarantine belongs to a legislative means. Due to the limitations of biological control methods such as slow effectiveness, strong specificity, and instability, it is difficult to popularize. Therefore, the chemical control method is currently the most effective measure for preventing and controlling forestry pests.

[0004] Traditional insecticidal agents are usually highly toxic and have a short effective period. They need to be sprayed frequently and in large doses, with low pesticide utilization rate. Such chemical agents will have serious negative impacts on forestry, mainly including: First, it causes the death of a large number of harmless insects, destroying the balance of the regional ecosystem; Second, the high-frequency spraying of traditional pesticide preparations will also cause some types of pests to develop strong drug resistance, accelerating the reproduction speed and evolution speed of pests, forming a vicious cycle and increasing the difficulty of pest control; Third, the unused pesticides enter the soil, leading to the accumulation of harmful substances in the soil and a decline in soil quality, posing a great threat to the forestry ecological environment and being unfavorable to the sustainable development of forestry; Fourth, the high-frequency spraying of pesticides increases labor costs, resulting in high forestry production costs and resource waste.

[0005] Therefore, the development of new green, efficient and environmentally friendly pesticides is of great significance for the prevention and control of forest pests, the maintenance of forest ecological environment and the sustainable development of forestry. Bifenthrin belongs to pyrethroid insecticides, which has the characteristics of broad spectrum, high efficiency, rapidity and long residual effect. It mainly has contact and stomach toxicity effects and no systemic effect. It can control various forest pests such as longhorn beetles, pine caterpillars and aphids. Thiacloprid is a new type of chloronicotinyl insecticide that acts on the post-synaptic membrane of insect nerves. By binding to the nicotinic acetylcholine receptor, it interferes with the normal conduction of the insect nervous system, causes the obstruction of nerve channels, resulting in a large accumulation of acetylcholine, thus making the insects extremely excited, with systemic convulsions and paralysis and death; Thiacloprid has strong systemic, contact and stomach toxicity effects and is one of the highly effective agents for controlling piercing and chewing mouthpart pests. However, in actual application, when bifenthrin is applied alone, it is easy for pests to develop drug resistance, which is a common problem of pyrethroid pesticides. When compounded with thiacloprid, two agents with completely different action mechanisms are mixed, which can make up for the deficiencies of each single agent, reduce the drug resistance of pests, expand the insecticidal range and have higher insecticidal activity. At present, the reported products of the two compounded are mainly suspension concentrates. In terms of application, there are some defects such as drug irritation, too large overall usage amount, low utilization rate of active ingredients, not long enough effective period and too many application times. Summary of the Invention

[0006] The purpose of the present invention is to provide a preparation process of a double-membrane microcapsule suspension concentrate to solve the existing problems.

[0007] To achieve the above purpose, the present invention provides the following technical solutions: A preparation process of a double-membrane microcapsule suspension concentrate, including the following steps:

[0008] S1: Preparation of the oil phase: First, dissolve two original drugs, bifenthrin and thiacloprid, with a safe and environmentally friendly solvent, and at the same time dissolve the oily monomer therein to prepare an oil phase. The original drugs are dissolved by the solvent so that they can be evenly dispersed, laying a foundation for the subsequent formation of a stable emulsion and microcapsules. After the original drugs are dissolved, they can be better encapsulated in the microcapsules, and the oily monomer participates in subsequent film-forming and other reaction processes;

[0009] S2: Preparation of the water phase: Mix an emulsifier, a protective colloid and water to form a water phase. The role of the emulsifier is to reduce the surface tension between the oil phase and the water phase, so that the oil phase can be evenly dispersed in the water phase in the form of tiny droplets; The protective colloid can increase the stability of the system, prevent the oil droplets from aggregating and merging, and contribute to the formation of a stable emulsion;

[0010] S3: Emulsion formation: The prepared oil phase is added to the water phase, and under high-speed shearing conditions, an oil-in-water emulsion is formed. The high-speed shearing provides powerful energy, causing the oil phase to be dispersed into tiny droplets and evenly distributed in the water phase, forming a stable oil-in-water emulsion. This emulsion is the basis for the subsequent formation of microcapsules, and its stability directly affects the quality of the microcapsules;

[0011] S4: First-layer film formation: A water-soluble polymer monomer is added to the emulsion. Under certain temperature conditions, a film-forming polymerization reaction occurs at the oil-water interface of the emulsion particles. The polymer capsule shell isolates the pesticide component from the water, forming the first layer of film. The water-soluble polymer monomer undergoes a polymerization reaction at the oil-water interface to form a polymer film. Due to the presence of the film, the pesticide component is wrapped inside and separated from the external water, improving the stability and controlled-release performance of the pesticide;

[0012] S5: Double-film microcapsule formation: A high-concentration curing agent and wall material solution are added. Under certain temperature conditions, high-speed stirring is carried out to form stable double-film microcapsules. The curing agent can make the already formed first layer of film more solid, and the wall material solution is evenly wrapped outside the first layer of film under high-speed stirring to form the second layer of film, further enhancing the stability of the microcapsules and the protective effect on the pesticide;

[0013] S6: Final product preparation: An appropriate amount of additives is added to prepare the final double-film microcapsule suspension concentrate product. The additives can improve the physical and chemical properties of the product, such as enhancing the dispersibility, stability, and fluidity of the product, making the product easier to store and use.

[0014] As a further aspect of the present invention: The safe and environmentally friendly solvent can be selected from one or more of vegetable oils such as soybean oil and rapeseed oil, fatty acid methyl ester, dimethyl carbonate, diacid ester, ethyl acetate, and butyl acetate.

[0015] As a further aspect of the present invention: The protective colloid can be selected from any one of gelatin, gum arabic, sodium carboxymethyl cellulose, and polyvinyl alcohol.

[0016] As a further aspect of the present invention: The additives are dispersant, thickener, antifreeze, preservative, and defoamer.

[0017] As a further aspect of the present invention: The curing agent can be selected from one or more of ethylenediamine, propylenediamine, triethylenediamine, diethylenetriamine, triethylenetetramine, and isophorone diamine, and the wall material solution can be selected from any one of isophorone diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, toluene diisocyanate, and lysine diisocyanate.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] In the present invention, by adopting a unique double-film structure to encapsulate bifenthrin and thiacloprid, the drug can be slowly released with a long-lasting effect, reducing the number of pesticide applications; increasing the adhesion and deposition of the drug, improving the transfer performance of the drug to the target, reducing droplet bounce, improving the utilization rate of the drug, reducing the impact on the environment, which is of great significance for reducing the amount of pesticides and increasing their efficiency. For the prevention and control of forestry pests, it can improve the control effect, effectively help the forestry reduce unnecessary additional disasters, save the forestry management cost, and improve the quality of the entire forestry. The compounding of two pesticides with different action mechanisms makes up for the deficiencies of single agents, reduces the drug resistance of pests, expands the insecticidal range, and has higher insecticidal activity;

[0020] In the present invention, by using an environmentally friendly solvent, it is environmentally friendly and does not use a large amount of organic solvents like traditional emulsifiable concentrate products, causing additional impact or damage to the environment, nor does it generate a large amount of dust during the manufacturing and use processes like dry powder seed coating agents, which is easy to pollute the environment and endanger the health and safety of producers and users. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a flow chart of the preparation process of a double-film microcapsule suspension agent described in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0023] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", "connected", "set" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. The following will describe the embodiments according to the overall structure of the present invention.

[0024] Referring to Figure 1 , in the embodiments of the present invention: A preparation process of a double-film microcapsule suspending agent includes the following steps:

[0025] S1: Preparation of the oil phase: First, dissolve two active ingredients, bifenthrin and thiamethoxam, in a safe and environmentally friendly solvent, and at the same time dissolve the oily monomer therein to prepare an oil phase (core material ratio 10:1). The solvent is used to dissolve the active ingredients and the oily monomer, so that they can be evenly dispersed, laying a foundation for the subsequent formation of a stable emulsion and microcapsules. After the active ingredients are dissolved, they can be better encapsulated in the microcapsules, and the oily monomer participates in subsequent film-forming and other reaction processes;

[0026] S2: Preparation of the water phase: Mix the emulsifier, protective colloid and water to form a water phase. The role of the emulsifier is to reduce the surface tension between the oil phase and the water phase, so that the oil phase can be evenly dispersed in the water phase in the form of tiny droplets; the protective colloid can increase the stability of the system, prevent oil droplets from aggregating and merging, and contribute to the formation of a stable emulsion;

[0027] S3: Formation of the emulsion: Start shearing at a rotation speed of 2000 r / min, and slowly add the prepared oil phase to the water phase to form an oil-in-water emulsion. High-speed shearing provides powerful energy, dispersing the oil phase into tiny droplets and evenly distributing them in the water phase to form a stable oil-in-water emulsion. This emulsion is the basis for the subsequent formation of microcapsules, and its stability directly affects the quality of the microcapsules;

[0028] S4: Formation of the first layer of film: The stirring speed is reduced to 500 - 800 r / min, the water bath heating is turned on, and the above emulsion is slowly heated to 50 °C. A water-soluble polymer monomer and a small amount of curing agent are slowly added (the ratio of wall material to curing agent is 10:0.2). The initial polymerization reaction for film formation occurs at the oil-water interface of the emulsion particles, and the polymer capsule shell isolates the pesticide component from water. It is cured for 1 h at a constant temperature to form the first layer of film.

[0029] S5: Formation of double-layer microcapsules: The stirring speed is reduced to 300 r / min, and a high-concentration wall material solution is added. After 2 - 3 minutes, the stirring speed is increased to 1000 r / min, and a sufficient amount of curing agent is added (wall material: curing agent = 10:1). The temperature is raised to 60 °C. The curing agent and the high-concentration wall material solution form a polymer at the phase interface and uniformly wrap around the outside of the first layer of film to form the second layer of film. It is cured for 3 h at a constant temperature to form stable double-layer microcapsules.

[0030] S6: Preparation of the final product: An appropriate amount of additives is added to prepare the final double-layer microcapsule suspension product. The additives can improve the physical and chemical properties of the product, such as enhancing the dispersibility, stability, and fluidity of the product, making the product easier to store and use.

[0031] The safe and environmentally friendly solvent can be selected from one or more of vegetable oils such as soybean oil and rapeseed oil, fatty acid methyl ester, dimethyl carbonate, dibasic acid ester, ethyl acetate, and butyl acetate.

[0032] The emulsifier can be selected from one of block polyethers, alcohol polyoxyethylene ethers, OP-10, and AEO-9.

[0033] The protective colloid can be selected from any one of gelatin, gum arabic, sodium carboxymethyl cellulose, and polyvinyl alcohol.

[0034] The additives are dispersants, thickeners, antifreeze agents, preservatives, and defoamers. Among them, the dispersant can be selected from one or more of polycarboxylate dispersants, polysulfonate dispersants, and mixed phosphate dispersants; the thickener is one of xanthan gum, magnesium aluminum silicate, and hydroxypropyl methylcellulose; the antifreeze agent is one of ethylene glycol, propylene glycol, glycerol, and urea; the preservative is Kathon (isothiazolinone) or sodium benzoate; the defoamer is silicone-based.

[0035] The curing agent can be selected from one or more of ethylenediamine, propylenediamine, triethylenediamine, diethylenetriamine, triethylenetetramine, and isophorone diamine; the wall material solution can be selected from any one of isophorone diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, toluene diisocyanate, and lysine diisocyanate.

[0036] The raw material ratios are as follows in the table:

[0037]

[0038]

[0039]

[0040] The functions of the raw materials in the formulation

[0041] Technical material

[0042] Bifenthrin: The proportion is 2 - 8%. Bifenthrin is a highly effective pyrethroid insecticide with contact and stomach poisoning effects. It has good control effects on various pests such as aphids, whiteflies, spider mites, etc. It can act on the nervous system of pests, causing the pests to become paralyzed and die, and is widely used in pest control of crops such as vegetables, fruits, and cotton in agricultural production.

[0043] Thiacloprid: The proportion is 2 - 8%. Thiacloprid is a new type of chloronicotinyl insecticide with systemic and contact effects. It can be quickly absorbed by plants and conducted to various parts. It has good control effects on piercing-sucking mouthpart pests such as aphids, leafhoppers, thrips, etc. and Coleoptera pests. Its action mechanism is to act on the acetylcholine receptors of pests, interfering with the normal functions of the nervous system of pests.

[0044] Solvent

[0045] One or more of vegetable oils such as soybean oil and rapeseed oil, fatty acid methyl ester, dimethyl carbonate, dibasic acid ester, ethyl acetate, and butyl acetate: The proportion is 5 - 10%. The main functions of these solvents are to dissolve the technical materials of bifenthrin and thiacloprid and the oily monomers, enabling them to be evenly dispersed in the system, laying a foundation for the subsequent formation of a stable emulsion and microcapsules. At the same time, the selected solvents have the characteristics of safety and environmental protection, reducing environmental pollution.

[0046] Emulsifier

[0047] One of block polyethers, alcohol polyoxyethylene ethers, OP-10, and AEO-9: The proportion is 1 - 5%. The function of the emulsifier is to reduce the surface tension between the oil phase and the water phase, enabling the oil phase to be evenly dispersed in the water phase in the form of tiny droplets, forming a stable oil-in-water emulsion. This can ensure the uniform distribution of the technical material in the system, improving the stability and efficacy of the preparation.

[0048] Wall material

[0049] Any one of isophorone diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, toluene diisocyanate and lysine diisocyanate: the proportion is 2 - 12%. The wall material plays a key role in the preparation of double - film microcapsules. It participates in the film - forming reaction, forms a polymer film at the oil - water interface of emulsion particles, wraps the pesticide components inside, isolates them from the external water, and improves the stability and controlled - release performance of the pesticide.

[0050] Curing agent

[0051] One or more of ethylenediamine, propylenediamine, triethylenediamine, diethylenetriamine, triethylenetetramine and isophoronediamine: the proportion is 1 - 5%. The role of the curing agent is to make the already formed first - layer film more solid, enhance the stability of the microcapsules and the protective effect on pesticides. It can react with the wall material to further cross - link and cure the film structure.

[0052] Protective colloid

[0053] Any one of gelatin, gum arabic, sodium carboxymethyl cellulose and polyvinyl alcohol: the proportion is 2 - 5%. The protective colloid can increase the stability of the system, prevent the aggregation and coalescence of oil droplets, and contribute to the formation of a stable emulsion. It can form a protective film on the surface of oil droplets, reduce the mutual attraction between oil droplets, and thus improve the stability of the emulsion.

[0054] Dispersant

[0055] One or more of polycarboxylate dispersants, polysulfonate dispersants, and mixed phosphate dispersants: the proportion is 1 - 5%. The role of the dispersant is to evenly disperse the microcapsules in the continuous phase, prevent the aggregation and precipitation of microcapsules, improve the dispersibility and stability of the product, and ensure the uniformity of the preparation during storage and use.

[0056] Thickening agent

[0057] One of xanthan gum, magnesium aluminum silicate, and hydroxypropyl methylcellulose: the proportion is 0.2 - 2%. The thickening agent can increase the viscosity of the preparation, prevent the sedimentation and stratification of microcapsules during storage, improve the stability and fluidity of the product, and make the product easier to store and use.

[0058] Defoaming agent

[0059] Organosilicon type: the proportion is 0.2%. During the preparation process, due to operations such as stirring, a large amount of foam will be generated. The defoaming agent can eliminate these foams, prevent the foam from affecting the preparation process and product quality, and ensure the smooth progress of production and the appearance quality of the product.

[0060] Preservative

[0061] Kathon (isothiazolinone) or sodium benzoate: The proportion is 0.1%. The role of the preservative is to prevent the preparation from being contaminated and damaged by microorganisms during storage, extend the shelf life of the product, and ensure the quality stability of the product within a certain period of time.

[0062] Antifreeze

[0063] One of ethylene glycol, propylene glycol, glycerol, and urea: The proportion is 3%. In a low-temperature environment, the antifreeze can lower the freezing point of the preparation, prevent the preparation from freezing, ensure the stability and fluidity of the product under low-temperature conditions, and enable it to be used normally in cold regions.

[0064] Continuous phase

[0065] Deionized water: Make up to 100%. As the continuous phase, deionized water provides a dispersion medium for the entire system, enabling other components to be evenly dispersed therein, forming a stable preparation system.

[0066] The above is only the preferred specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A preparation process of a double-membrane microcapsule suspending agent, characterized in that It includes the following steps: S1: Preparation of the oil phase: First, dissolve bifenthrin and thiamethoxam, two kinds of active ingredients, with a safe and environmentally friendly solvent, and at the same time dissolve the oily monomer therein to prepare the oil phase; S2: Preparation of the water phase: Mix the emulsifier, protective colloid and water to form the water phase; S3: Formation of the emulsion: Add the prepared oil phase to the water phase and form an oil-in-water emulsion under high-speed shearing conditions; S4: Formation of the first layer of film: Add a water-soluble polymer monomer to the emulsion. Under certain temperature conditions, a film-forming polymerization reaction occurs at the oil-water interface of the emulsion particles, and the polymer capsule shell isolates the pesticide component from the water to form the first layer of film; S5: Formation of the double-film microcapsule: Add a high-concentration curing agent and wall material solution, and under certain temperature conditions, stir at high speed to form a stable double-film microcapsule; S6: Preparation of the final product: Add an appropriate amount of auxiliary agent to prepare the final double-film microcapsule suspension product.

2. The preparation process of a double-film microcapsule suspending agent according to claim 1, characterized in that, The safe and environmentally friendly solvent can be selected from one or more of vegetable oils such as soybean oil and rapeseed oil, fatty acid methyl ester, dimethyl carbonate, dibasic acid ester, ethyl acetate and butyl acetate.

3. The preparation process of a double-film microcapsule suspending agent according to claim 1, characterized in that, The protective colloid can be selected from any one of gelatin, arabic gum, sodium carboxymethyl cellulose and polyvinyl alcohol.

4. The preparation process of a double-membrane microcapsule suspending agent according to claim 1, characterized in that, The auxiliary agent is a dispersant, thickener, antifreeze, preservative and defoamer.

5. The preparation process of a double-membrane microcapsule suspending agent according to claim 1, characterized in that, The curing agent can be selected from one or more of ethylenediamine, propylenediamine, triethylenediamine, diethylenetriamine, triethylenetetramine and isophorone diamine, and the wall material solution can be selected from any one of isophorone diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, toluene diisocyanate and lysine diisocyanate.

Images