Self-dispersing pesticide microcapsule and preparation method

Abstract

The present invention belongs to the technical field of pesticide microcapsules, and provides a self-dispersing pesticide microcapsule and a preparation method. The self-dispersing pesticide microcapsule has a core material mainly obtained by mixing and curing polymerization of a polyurethane prepolymer and a pesticide, a capsule material mainly formed by interfacial polymerization of a hydrophilic group-containing polyurethane prepolymer, the drug loading capacity ranging from 80% to 99%, and a particle size ranging from 1 μm to 20 μm. The preparation method comprises: adding a hydrophobic polyurethane prepolymer coated with a pesticide and a hydrophilic polyurethane prepolymer into water separately, emulsifying to obtain an emulsion having the hydrophobic polyurethane prepolymer coated with the pesticide as a core and the hydrophilic group-containing hydrophilic polyurethane prepolymer as a shell, adding a curing agent into the emulsion, and carrying out interfacial polymerization to obtain a pesticide microcapsule. The obtained pesticide microcapsule is dissolved in a solvent and has the characteristics of easy dispersion, thin hydration layer, low viscosity and good stability.

Description

Self-dispersing pesticide microcapsule and preparation method Technical Field

[0001] The present invention relates to the technical field of pesticides, in particular to pesticide microcapsules and a preparation method thereof. Background Art

[0002] With increasing awareness of environmental protection and safety, pesticide microcapsules have become a hot topic in pesticide formulation research and development due to their potential to reduce pesticide toxicity, pesticide damage, and environmental pollution, extend their effectiveness, and increase their utilization rate. Microencapsulation technology uses natural or synthetic polymer film-forming materials to encapsulate dispersed solids, liquids, or gases into tiny particles. This technology isolates the target substance from the surrounding environment through a sealed or semipermeable membrane.

[0003] Polyurethane is a synthetic polymer material with excellent properties that can be used to synthesize microcapsules. Polyurethane is composed of soft and hard segments, a block copolymer with a urethane structure in the backbone, formed by the reaction of isocyanate and hydroxyl groups. These alternating segments, due to their varying polarity, tend to aggregate and separate, resulting in phase separation. Depending on the chemical composition, materials with unique properties can be produced. Waterborne polyurethane is a novel polyurethane system that uses water as the dispersion medium, replacing organic solvents. Using water as the solvent, it offers advantages such as being pollution-free, safe and reliable, possessing excellent mechanical properties, good compatibility, and ease of modification. It is also non-flammable, has low odor, is environmentally friendly, energy-efficient, and easy to process. It also possesses strong adhesion, wear resistance, and corrosion resistance, resulting in an increasingly broad range of applications. Waterborne polyurethane is gradually replacing solvent-based polyurethane for the preparation of pesticide microcapsules.

[0004] However, waterborne polyurethanes have several drawbacks, such as low solids content, long drying times, and insufficient initial tack. Increasing the solids content of waterborne polyurethane emulsions is one approach to overcoming these issues. Waterborne polyurethane particles typically consist of a hydrophobic core, a hydration layer, and an electrical double layer. The presence of the hydration layer makes the synthesis of high-solids waterborne polyurethanes extremely difficult, and a large amount of water is absorbed by the hydration layer of the polyurethane particles. When using waterborne polyurethane to prepare pesticide microcapsules, the pesticide is encapsulated as the core material. However, the presence of the hydration layer results in low drug loading in the pesticide microcapsule formulation.

[0005] Existing pesticide microcapsules have a low suspension efficiency. During dilution or storage, the particles can stratify and precipitate, seriously affecting the efficacy of the pesticide. Improving the suspension efficiency would allow the active ingredient particles to remain evenly suspended in the spray solution for a longer period of time. This would ensure consistent spray concentrations throughout the spraying process, allowing for even deposition on the target and better efficacy.

[0006] The current solution is to add additives such as dispersants and wetting agents to the microcapsule system to improve the suspension and dispersion stability of the pesticide microcapsules in water. However, these added surfactants, dispersants, or wetting agents can remain in the environment, causing environmental pollution.

[0007] Therefore, it is necessary to improve the existing technology to obtain pesticide microcapsules that can self-disperse in water and have high dispersion stability.

[0008] Summary of the Invention

[0009] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a self-dispersing pesticide microcapsule that can self-disperse in water to obtain a uniform pesticide microcapsule suspension with a high drug loading capacity.

[0010] A self-dispersing pesticide microcapsule comprises a capsule core and a capsule wall, wherein the capsule core encapsulates the pesticide; the inner wall of the capsule wall is hydrophobic polyurethane, and the outer wall is hydrophilic polyurethane.

[0011] Preferably, the drug loading is 80-99%. More preferably, the average particle size is 1-5 μm, and the particle size distribution is 1-20 μm.

[0012] The method for preparing the self-dispersing pesticide microcapsules comprises the following steps:

[0013] (1) A pesticide technical dissolved in an organic solvent is mixed with an isocyanate, a small molecule chain extender A, a catalyst, and a vegetable oil to form a hydrophobic polyurethane prepolymer B;

[0014] A hydrophilic monomer, a polyol monomer, a small molecule chain extender B, an isocyanate, a catalyst, a neutralizer and an organic solvent are mixed and reacted, and water or a surfactant aqueous solution is added to form a hydrophilic polyurethane prepolymer A;

[0015] (2) mixing and emulsifying the hydrophilic polyurethane prepolymer A and the hydrophobic polyurethane prepolymer B to form an emulsion;

[0016] (3) Add a curing agent to the emulsion to carry out interfacial polymerization reaction.

[0017] In step (1), the mass ratio of the neutralizing agent to the hydrophilic monomer is 1:1-3.

[0018] The mass ratio of the hydrophobic polyurethane prepolymer B to the hydrophilic prepolymer A is 1:0.6-5, preferably 1:0.8-2, and more preferably 1:0.8-1.5.

[0019] The hydrophilic polyurethane prepolymer A is calculated based on the total amount of polyol monomer and isocyanate, and the hydrophobic polyurethane prepolymer B is calculated based on the total amount of vegetable oil and isocyanate. The mass ratio of the hydrophilic polyurethane prepolymer A to the hydrophobic polyurethane prepolymer B is 1-5:1, preferably 1-3:1.

[0020] In the raw materials of hydrophobic polyurethane prepolymer B, the mass ratio of the total amount of isocyanate and vegetable oil to the pesticide technical is 1:1.5-6; the mass ratio of isocyanate, vegetable oil, catalyst, and small molecule chain extender B is 1:1-3:0-0.06:0.1-0.7. The mass ratio of pesticide to organic solvent is 4-8:1, preferably 5-7:1.

[0021] The raw materials of the hydrophilic polyurethane prepolymer A include isocyanates, polyol monomers, curing agents, hydrophilic monomers, and catalysts in a mass ratio of 1:1.5-3:0.03-0.1:0.1-0.2:0-0.06. The mass ratio of the total amount of isocyanates and polyol monomers to the organic solvent is 2.5-6:1.

[0022] The content of the surfactant in the emulsion is 0.1wt%-1wt%.

[0023] In step (1), the small molecule chain extender A and the small molecule chain extender B are one or more of polyamines and polyols; preferably polyols.

[0024] The polyamine is one or more of polyethylene glycol diamine, triethylenetetramine, meglumine, tetraethylenepentamine, diethylenetriamine and isophoronediamine; the polyol is one or more of 3,3'-dithiobis-1,2-propylene glycol, 1,2,6-hexanetriol, pentaerythritol, N,N'-bis(3-aminopropyl)-1,3-propylenediamine, glycerol, trimethylolpropane, trimethylolethane, ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol and dipropylene glycol.

[0025] Furthermore, in step (2), the emulsification rate is 300-12000 r / min, and the emulsification time is 5-60 min.

[0026] The temperature of the interfacial polymerization reaction in step (3) is 50-80° C. and the time is 2-5 hours.

[0027] In step (3), the ratio of the emulsion to the curing agent is 1:0.005-0.015 by mass, preferably 1:0.01-0.1 by mass.

[0028] In the present invention, the vegetable oil can be one or more of castor oil, soybean oil, rapeseed oil, cottonseed oil, rice bran oil, corn oil, and sunflower oil.

[0029] The hydrophilic monomer is an alcoholamine, or a chain extender with a carboxyl group or a sulfonic acid group. Preferably, the alcoholamine chain extender is a tertiary amino alcohol. Specifically, the hydrophilic monomer is one or more of 1,2-propylene glycol-3-sulfonate, 1,4-butanediol-2-sulfonate, hydroxymethylpropionic acid, dimethylolbutyric acid, 1,4-butanediol-2-sulfonate, sodium N,N-(2-hydroxyethyl)-2-aminoethanesulfonate, N,N-dimethylformamide, sodium ethylenediamineethanesulfonate, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, N-propyldiethanolamine, N-butyldiethanolamine, dimethylethanolamine, 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt, bis(2-hydroxyethyl)aniline and bis(2-hydroxypropyl)aniline. When the hydrophilic monomer is an alcoholamine chain extender, it is neutralized with an acid, and the acid is preferably a carboxylic acid or a sulfonic acid; when the hydrophilic monomer is a chain extender having a carboxyl group or a sulfonic acid group, it is neutralized with a base, and the base is an organic base or an inorganic base, and the organic base is preferably triethylamine, trimethylamine, diethylenetriamine, tetramethylethylenediamine, etc., and the inorganic base is sodium hydroxide, potassium hydroxide, ammonia water, a soluble carbonate or bicarbonate.

[0030] Preferably, the isocyanate monomer is one or more of 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, hydrogenated phenylmethane diisocyanate, xylylene diisocyanate, isophorone diisocyanate, tetramethylxylene diisocyanate, 4,4'-dibenzyl diisocyanate, isophorone diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, toluene diisocyanate isomers, 1-methyl-2,4-diisocyanatocyclohexane, 1,6-diisocyanato-2,2,4-trimethylhexane, 1,6-diisocyanato-2,4,4-trimethylhexane, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and lysine diisocyanate.

[0031] Preferably, the curing agent is one or more of a polyamine and a polyol. The polyamine is one or more of polyethylene glycol diamine, triethylenetetramine, meglumine, tetraethylenepentamine, diethylenetriamine, and isophoronediamine; the polyol is one or more of 3,3'-dithiobis-1,2-propylene glycol, 1,2,6-hexanetriol, pentaerythritol, N,N'-bis(3-aminopropyl)-1,3-propylenediamine, glycerol, trimethylolpropane, trimethylolethane, ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, and dipropylene glycol.

[0032] Preferably, the pesticide technical is one or more of cyhalothrin, chlorpyrifos, pendimethalin, trifloxystrobin, trifluralin, trifloxystrobin, cyhalofop-butyl, bifenthrin, blastifungin, pyraclostrobin, oxyfluorfen, cyflumetofen, cyprodinil, hexaconazole, avermectin, carbendazim, emamectin benzoate, thiophanate-methyl, tebuconazole, metalaxyl-M, clodinafop-propargyl, butachlor, difenoconazole, propiconazole, mexamethylenetetracycline, flutriafol, diniconazole, myclobutanil, oxadiazol, triadimefon, cyprodinil, azoxystrobin, trifloxystrobin, epoxiconazole, clethodim, imazalil, triadimenol, bitertaconazole and cyproconazole.

[0033] Preferably, the catalyst is one of dibutyltin oxide, dibutyltin dibutyrate, dimethyltin dibutyrate, dioctyltin dibutyrate, dibutyltin diacetate, dimethyltin diacetate, dibutyltin dilaurate, dimethyltin dilaurate, dioctyltin dilaurate, dibutyltin dioleate, dimethyltin dioleate, dioctyltin dioleate, dibutyltin isooctyl dithioacetate, dimethyltin isooctyl dithioacetate, dioctyltin isooctyl dithioacetate, dibutyltin dioctyldecanoate, dimethyltin dioctyldecanoate, dioctyltin dioctyldecanoate, dibutyltin diacetate, and dimethyltin diacetate.

[0034] Preferably, the polyol monomer is one or more of polyester polyols and polyether polyols, such as one or more of polypropylene adipate, polybutylene adipate, polyhexanediol adipate, polyoxypropylene glycol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, trimethylolpropane, polyethylene oxide glycol, polytetramethylene glycol, copolyether glycol, polyethylene adipate glycol, polydiethylene adipate, polyneopentyl adipate, and the like.

[0035] Preferably, the organic solvent is one or more of cyclohexane, toluene, cyclohexanone, ethyl acetate, dimethylacetamide, butyl acetate, amyl acetate, sec-butyl acetate, isoamyl citrate, butanone, methyl acetate, propyl acetate, acetone, methyl butyl ketone, methyl isobutyl ketone and cyclohexanone.

[0036] Preferably, the surfactant is one or more of the Tween series (Tween-80, Tween-85, Tween-20, Tween-60, Tween-40), Span series (Span-40, Span-20, Span-60), castor oil polyoxyethylene ether series (EL-40, EL-60, EL-80, EL-90), sodium lauryl sulfate, sodium dodecylbenzene sulfonate and polyvinyl alcohol.

[0037] The present invention first synthesizes two polyurethane prepolymers with different hydrophobic properties; one is a hydrophobic polyurethane prepolymer and the other is a hydrophilic polyurethane prepolymer; then the two prepolymers are mixed in a certain proportion and emulsified by high-speed shearing to obtain a core-shell polyurethane emulsion; due to the difference in hydrophilicity and hydrophobicity between the hydrophobic polyurethane prepolymer and the hydrophilic prepolymer, the hydrophobic polyurethane prepolymer wraps the pesticide, which is further wrapped by the hydrophilic polyurethane prepolymer, and further solidified to obtain self-dispersed polyurethane pesticide microcapsules; since the inner side of the capsule wall is hydrophobic, the pesticide can be wrapped; and the outer side is hydrophilic, the formed polyurethane pesticide microcapsules can be stably self-dispersed in water.

[0038] The preparation method of the present invention can reduce the thickness of the hydration layer, so that the prepared pesticide microcapsules have the advantages of a thin hydration layer, low viscosity, high content and good suspension stability; by increasing the mass ratio of hydrophobic polyurethane prepolymer to hydrophilic polyurethane prepolymer, pesticide microcapsules with high content and high drug loading can be prepared.

[0039] The present invention also uses vegetable oil containing hydroxyl groups to replace part of the polyester / polyether polyol to prepare the prepolymer. On the one hand, the vegetable oil can be used as a solvent to dissolve part of the pesticide technical, reducing the amount of organic solvent used in the preparation of pesticide microcapsules; it can also react with isocyanate.

[0040] The pesticide microcapsules obtained by the present invention have a high suspension rate, and the active ingredient particles can be evenly suspended in water for a long time, so that the concentration of the sprayed liquid remains consistent during the spraying process, and the liquid is evenly deposited on the target, thereby better exerting the efficacy.

[0041] The beneficial effects of the present invention are:

[0042] (1) The thickness of the hydration layer of the prepared emulsion can be reduced, so that the prepared emulsion has the characteristics of low viscosity, high solid content and good stability; the obtained pesticide microcapsules have the advantages of thin hydration layer, low viscosity, high drug content and good stability; by increasing the mass ratio of hydrophobic polyurethane prepolymer to hydrophilic polyurethane prepolymer, pesticide microcapsules with high drug content and high drug loading can be prepared;

[0043] (2) Because the outer wall of the pesticide microcapsule contains a large number of hydrophilic groups, the microcapsule suspension stability can be high without adding or with minimal addition of additional additives. Moreover, when diluted for use, no external stirring is required, and the microcapsules can be directly and quickly dispersed in water to obtain a uniform pesticide microcapsule suspension, thereby ensuring the effectiveness of the pesticide microcapsules. Therefore, the prepared microcapsules do not require the addition of additives such as wetting agents and dispersants; they have strong self-dispersibility, with an automatic dispersibility of 95% or more;

[0044] (3) The pesticide microcapsules of the present invention have a high suspension rate of over 90%, allowing the particles of the active ingredient to be evenly suspended in the liquid medicine for a long time. The concentration of the liquid medicine sprayed before and after the spraying process remains consistent, and the liquid medicine is evenly deposited on the target, thereby better exerting the efficacy of the medicine.

[0045] (4) The present invention uses hydroxyl-containing vegetable oil to replace part of the polyester / polyether polyol in the preparation of the prepolymer. On the one hand, the vegetable oil can replace the organic solvent to dissolve part of the pesticide technical, thereby reducing the amount of organic solvent used in the preparation of the pesticide microcapsules; on the other hand, it can participate in the reaction of isocyanate, thereby reducing the amount of organic reactants used, which is environmentally friendly.

[0046] (5) The pesticide microcapsule suspension of the present invention is used for spraying crops, and the pesticide microcapsules are deposited better and more evenly on the leaf surface; no external stirring is required when diluting and using, and it is easy to use and operate;

[0047] (6) The preparation method provided by the present invention has high polyurethane microcapsule yield and drug loading, simple process flow, does not require harsh operating conditions and expensive production equipment, has low cost, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] FIG1 is a self-dispersion diagram of 25% pyraclostrobin microcapsules prepared in Example 1; FIGA and FIGB are initial diagrams of dropwise addition of microcapsules, and FIGC is a dispersion diagram 15 seconds after dropwise addition.

[0049] FIG2 is a scanning electron micrograph of 25% pyraclostrobin microcapsules prepared in Example 1;

[0050] FIG3 is a sustained-release curve of the release rate of 25% pyraclostrobin microcapsules prepared in Example 1 over time.

[0051] Figure 4 is a scanning electron micrograph of 30% blastolin microcapsules;

[0052] FIG5 is a scanning electron micrograph of 30% blastifungin-prochloraz microcapsules;

[0053] Figure 6 is a scanning electron micrograph of 25% difenoconazole microcapsules;

[0054] FIG7 is a scanning electron micrograph of 25% rice blast-in pesticide microcapsules;

[0055] FIG8 is a scanning electron micrograph of 25% pyraclostrobin·blastifungin;

[0056] Figure 9 is a scanning electron micrograph of 25% pyraclostrobin·difenoconazole;

[0057] Figure 10 is a scanning electron micrograph of 21% tebuconazole. DETAILED DESCRIPTION

[0058] Example 1 Preparation of 25% Pyraclostrobin Microcapsule Suspension

[0059] 51 g of pyraclostrobin (98%) was dissolved in 10 g of isoamyl citrate, 0.3 g of dioctyltin dilaurate, 0.9 g of 1,4-butanediol, 6.66 g of toluene diisocyanate, and 18.66 g of castor oil were added to the above system, and the mixture was stirred and reacted at 60° C. for 1 h to obtain a hydrophobic polyurethane prepolymer B;

[0060] 1.15 g of sodium 1,4-butanediol-2-sulfonate, 0.3 g of dibutyltin dilaurate, 0.9 g of 1,4-butanediol, 20 g of polypropylene glycol, 13.3 g of hexamethylene diisocyanate, and 10 g of isoamyl citrate were directly mixed, 0.52 g of triethylamine was added dropwise for neutralization, and the mixture was heated and stirred at 60° C. for 2 h. The mixture was then added to a 2 wt % sodium dodecylbenzenesulfonate solution and the mass was supplemented to 1.2 times that of the hydrophobic polyurethane prepolymer B to obtain a hydrophilic prepolymer A.

[0061] The hydrophilic polyurethane prepolymer A and the hydrophobic polyurethane prepolymer B are mixed and emulsified at a shear rate of 12000 r / min and an emulsification time of 10 min to obtain an emulsion;

[0062] The emulsion was mixed with triethylenetetramine at a mass ratio of 100:1 and subjected to interfacial polymerization at 60°C for 3 hours to obtain a 25% pyraclostrobin microcapsule suspension. The following performance analysis was performed on the obtained microcapsule suspension. 1.1 Self-dispersion test

[0063] Detection method: Use standard hard water to prepare the test sample into a suspension of appropriate concentration.

[0064] Under specified conditions, let the suspension stand in the measuring cylinder for a certain period of time, measure the mass of the active ingredient in the bottom one-tenth of the suspension, and calculate its spontaneous dispersion.

[0065] The spontaneous dispersion measured according to the above method reached 97%.

[0066] The resulting pesticide microcapsules have low viscosity, forming a uniformly dispersed suspension and exhibiting rapid self-dispersion. As shown in Figure 1, A and B show the initial stages of microcapsule addition, respectively, while C shows the self-dispersion effect 15 seconds after addition. This demonstrates the low viscosity and excellent self-dispersion properties of the pesticide microcapsules, enabling them to quickly form a uniform, diluted dispersion.

[0067] 1.2 Suspension rate detection

[0068] Test method: Weigh 1.0g of sample and perform the test according to GB / T 14825-2006. Transfer the remaining 1 / 10 suspension and sediment at the bottom of the graduated cylinder to a 100mL volumetric flask. Add 10mL of N,N-dimethylformamide. Wash the bottom of the graduated cylinder with 40mL of methanol three times. Combine the washings with the volumetric flask. Ultrasonicate for 10 minutes to dissolve the sample. Cool to room temperature, dilute to the mark with methanol, shake well, and filter.

[0069] The mass was measured and the suspension rate was calculated to be 91% according to the method (the sample was dissolved in a mobile phase, acetonitrile + water + acetic acid was used as the mobile phase, a stainless steel column filled with C18 and an ultraviolet detector was used, the pesticides in the sample were separated by reverse-phase high performance liquid chromatography at 290 nm, and quantified by the external standard method).

[0070] 1.3 Wet screening test

[0071] Wet sieving test was carried out according to GB / T 16150-1995, and ≥98% passed 80-mesh test sieve.

[0072] 1.4 Encapsulation efficiency and drug loading detection

[0073] The encapsulation efficiency and drug loading of pyraclostrobin were determined by destroying the microcapsules.

[0074] 0.01 g of the dried microcapsule sample was weighed and added to 10 mL of methanol, the volume was adjusted to 100 mL, and then ultrasonicated for 30 min to completely release the pyraclostrobin.

[0075] The absorbance was measured at 274 nm using an ultraviolet spectrophotometer, and the amount of pyraclostrobin in the microcapsules was calculated based on the standard curve.

[0076] The formulas for calculating the encapsulation efficiency and drug loading of microcapsules are as follows:

[0077] Encapsulation efficiency (%) = weight of original drug in microcapsules / total weight of original drug × 100

[0078] Drug loading (%) = weight of original drug in microcapsules / total weight of microcapsules × 100

[0079] The encapsulation efficiency measured by the above method was 90% and the drug loading was 89%.

[0080] The scanning electron micrograph of the microcapsules is shown in FIG2 , and the average particle size is about 2 μm. The release rate curve of the microcapsules is shown in FIG3 , and the cumulative release rate reaches more than 80% after 70 h.

[0081] Example 2 Preparation of 30% Pablolin Microcapsule Suspension

[0082] 61.8 g of blastifungin (97%) was dissolved in 10 g of amyl acetate, and 1.35 g of 1,4-butanediol, 5.55 g of hexamethylene diisocyanate, 0.3 g of dibutyltin dioctanoate and 16 g of cottonseed oil were mixed with the above system. The mixture was stirred and reacted at 65° C. for 1 h to obtain a hydrophobic polyurethane prepolymer B.

[0083] 1.0 g of dimethylolpropionic acid, 0.3 g of dioctyltin dioctanoate, 0.9 g of 1,4-butanediol, 20 g of polypropylene glycol, 13.3 g of hexamethylene diisocyanate, and 10 g of amyl acetate were mixed, neutralized with 0.5 g of triethylamine, and heated with stirring at 70° C. for 1 h. 1.7 g of Tween-80 was added to the reaction system, and finally deionized water was added to 1.2 times the mass of the hydrophobic polyurethane prepolymer B to obtain a hydrophilic prepolymer A.

[0084] The hydrophilic polyurethane prepolymer A and the hydrophobic polyurethane prepolymer B are mixed and emulsified to obtain an emulsion; the emulsification parameters are: shear rate 10000 r / min, emulsification time 6 min;

[0085] The emulsion and diethylenetriamine were mixed in a mass ratio of 100:1, and interfacial polymerization reaction was carried out at 50° C. for 4 h to obtain a 30% rice blasticide microcapsule suspension.

[0086] The spontaneous dispersibility of the microcapsule suspension was measured to be 96%, and the suspension rate was 93%. According to the wet sieving test of GB / T 16150-1995, ≥98% of the microcapsules passed through an 80-mesh test sieve. The encapsulation efficiency was measured to be 89%, and the drug loading was 82%.

[0087] FIG4 is a scanning electron micrograph of 30% rice blasting agent microcapsules.

[0088] Example 3 Preparation of 30% Paclobutrazol-Prochloraz Microcapsule Suspension

[0089] 35 g of 97% pyraclostrobin and 26.8 g of prochloraz (97%) were dissolved in 10 g of sec-butyl acetate, 2.25 g of 1,4-butanediol, 7.77 g of dicyclohexylmethane diisocyanate, 0.3 g of dibutyltin dilaurate, 10 g of castor oil, and 1.6 g of Span-60 were added to the above system, and the mixture was heated at 50° C. for 1 h to obtain a hydrophobic polyurethane prepolymer B;

[0090] 1.3 g of a hydrophilic monomer, DMBA, 2.7 g of 1,4-butanediol, 25 g of polypropylene glycol, 16.6 g of dicyclohexylmethane diisocyanate, 0.3 g of dibutyltin dilaurate, and 8 g of sec-butyl acetate were mixed, 0.89 g of triethylamine was added dropwise for neutralization, and the mixture was heated at 60°C for 2 h. 1 g of Tween-60 was added to the reaction mixture, and deionized water was added to the mixture to a mass of 1.2 times that of the hydrophobic polyurethane prepolymer B, and the mixture was mixed to obtain a hydrophilic polyurethane prepolymer A.

[0091] The hydrophilic polyurethane prepolymer A and the hydrophobic polyurethane prepolymer B are mixed and emulsified to obtain an emulsion. The emulsification parameters are: shear rate 11000 r / min, emulsification time 10 min;

[0092] The emulsion and diethylenetriamine were mixed at a mass ratio of 100:1, and interfacial polymerization was carried out at 60° C. for 4 hours to obtain a 30% blastifungin-prochloraz microcapsule suspension.

[0093] The spontaneous dispersibility was measured to be 98%, the suspension rate was 92%, and according to the GB / T 16150-1995 wet sieving test, ≥98% passed the 80-mesh test sieve. The encapsulation efficiency was measured to be 90%, and the drug loading was 86%.

[0094] FIG5 is a scanning electron micrograph of 30% blastifungin-prochloraz microcapsules.

[0095] Example 4 Preparation of 25% Difenoconazole Microcapsule Suspension

[0096] 51.5 g of difenoconazole (97%) was dissolved in 8 g of methyl acetate, 1.8 g of 1,4-butanediol, 0.3 g of dibutyltin dilaurate, 8.25 g of lysine diisocyanate and 14.5 g of castor oil were added to the above system, and the mixture was heated and stirred at 65° C. for 1 h to obtain a hydrophobic polyurethane prepolymer B;

[0097] 2.6 g of sodium 1,2-propylene glycol-3-sulfonate, 1.8 g of 1,4-butanediol, 10 g of polyethylene glycol, 17 g of lysine diisocyanate, 0.3 g of dibutyltin dilaurate, and 10 g of methyl acetate were mixed, 0.8 g of triethylamine was added dropwise for neutralization, and the mixture was heated and stirred at 60°C for 2 h. 1.5 g of EL-40 was added to the reaction mixture, and deionized water was added to the above mixture to a concentration of 1.2 times the mass of the hydrophobic polyurethane prepolymer B to obtain a hydrophilic polyurethane prepolymer A.

[0098] The hydrophilic polyurethane prepolymer A and the hydrophobic polyurethane prepolymer B are mixed and emulsified to obtain an emulsion. The emulsification parameters are: shear rate 12000 r / min, emulsification time 5 min;

[0099] The emulsion and the pentaerythritol aqueous solution were mixed in a mass ratio of 12:1, and subjected to interfacial polymerization reaction at 70° C. for 3 hours to obtain a 25% difenoconazole pesticide microcapsule suspension.

[0100] The spontaneous dispersibility of the pesticide microcapsule suspension was measured to be 98%, and the suspension rate was 93%. A wet sieving test according to GB / T16150-1995 showed that ≥98% of the particles passed an 80-mesh test sieve. The encapsulation efficiency was measured to be 87%, and the drug loading was 82%.

[0101] FIG6 is a scanning electron micrograph of 25% difenoconazole microcapsules.

[0102] Example 5 Preparation of 25% Paddyblastin Microcapsule Suspension

[0103] 51.5 g of blastifungin (97%) was dissolved in 8.5 g of cyclohexanone, and the dissolved blastifungin was mixed with 1.5 g of 1,2-propylene glycol, 0.3 g of dibutyltin dilaurate, 6.7 g of hexamethylene diisocyanate, and 6.76 g of soybean oil. The mixture was heated and stirred at 65° C. for 1 h to obtain a hydrophobic polyurethane prepolymer B.

[0104] 0.98 g of N-propyldiethanolamine, 1.1 g of 1,2-propylene glycol, 26 g of polytetramethylene glycol, 13.4 g of hexamethylene diisocyanate, and 10 g of cyclohexanone were mixed, 1.1 g of acetic acid was added for neutralization, and the mixture was heated and stirred at 65°C for 1.5 h. 1.6 g of EL-80 was added to the reaction mixture, and the mass was adjusted to 1.5 times that of the hydrophobic polyurethane prepolymer B with deionized water to obtain a hydrophilic prepolymer A.

[0105] The hydrophilic polyurethane prepolymer A and the hydrophobic polyurethane prepolymer B are mixed and emulsified, and the emulsification parameters are as follows: a shear rate of 8000 r / min and an emulsification time of 10 min to obtain an emulsion;

[0106] The emulsion was mixed with a meglumine aqueous solution at a mass ratio of 15:1, and subjected to interfacial polymerization reaction at 60° C. for 3 h to obtain a 25% blastifungin microcapsule suspension.

[0107] The spontaneous dispersibility of the pesticide microcapsule suspension was measured to be 97%, the suspension rate was 95%, and in a wet sieving test according to GB / T16150-1995, ≥98% of the particles passed an 80-mesh test sieve. The encapsulation efficiency was measured to be 89%, and the drug loading was 81%.

[0108] FIG7 is a scanning electron micrograph of 25% rice blasting agent microcapsules.

[0109] Example 6 Preparation of 25% Pyraclostrobin·Blastolin Microcapsule Suspension

[0110] 8.1 g of pyraclostrobin (97%) and 43.3 g of blastifungin (97%) were dissolved in 10 g of butanone, 2.36 g of 1,6-hexanediol, 8.8 g of isophorone diisocyanate, 9 g of corn oil, and 1.1 g of EL-40 were added to the above system, and the mixture was heated and stirred at 45°C for 1 h to obtain a hydrophobic polyurethane prepolymer B;

[0111] 1.96 g of dimethylethanolamine, 2.36 g of 1,6-hexanediol, 18 g of polyethylene glycol, 19.98 g of isophorone diisocyanate, and 10 g of butanone were mixed, and 3.36 g of 3,4-dihydroxyphenylacetic acid was added dropwise to neutralize the mixture. The mixture was heated and stirred at 70°C for 2 h. After the reaction, the mass of the system was supplemented with deionized water to 1.2 times that of the hydrophobic polyurethane prepolymer B to obtain a hydrophilic prepolymer A.

[0112] The hydrophilic polyurethane prepolymer A and the hydrophobic polyurethane prepolymer B were mixed and emulsified under the following emulsification parameters: shear rate of 11000 r / min, emulsification time of 8 min, to obtain an emulsion.

[0113] The emulsion was mixed with an aqueous solution of polyamine isophorone diamine at a mass ratio of 10.1:1, and subjected to interfacial polymerization reaction at 55° C. for 4 hours to obtain a 25% pyraclostrobin·blastifungin microcapsule suspension.

[0114] The spontaneous dispersibility of the pesticide microcapsule suspension was measured to be 96%, and the suspension rate was 91%. According to the wet sieving test of GB / T16150-1995, ≥98% of the particles passed through an 80-mesh test sieve. The encapsulation efficiency was measured to be 90%, and the drug loading was 88%.

[0115] FIG8 is a scanning electron micrograph of 25% pyraclostrobin·blastifungin microcapsules.

[0116] Example 7 Preparation of 25% Pyraclostrobin·Difenoconazole Microcapsule Suspension

[0117] 20 g of pyraclostrobin (98%) and 31 g of difenoconazole (97%) were dissolved in 8 g of methyl isobutyl ketone, and 4.2 g of neopentyl glycol, 7 g of toluene diisocyanate, 0.3 g of dibutyltin dilaurate, and 10 g of castor oil were added to the above system, and the mixture was heated and stirred at 60° C. for 2 h to obtain a hydrophobic polyurethane prepolymer B;

[0118] 1.48 g of bis(2-hydroxyethyl)aniline, 2.08 g of neopentyl glycol, 24 g of polyethylene glycol, 15.66 g of toluene diisocyanate, and 10 g of methyl isobutyl ketone were mixed, 1.54 g of 3,4-dihydroxybenzoic acid was added dropwise for neutralization, and the mixture was heated and stirred at 65°C for 2 h. 1.7 g of polyvinyl alcohol was added to the reaction system, and the mass was supplemented with deionized water to 1.2 times that of the hydrophobic polyurethane prepolymer B to obtain a hydrophilic prepolymer A;

[0119] The hydrophilic polyurethane prepolymer A and the hydrophobic polyurethane prepolymer B are mixed and emulsified to obtain an emulsion; the emulsification parameters are: a pick-up rate of 12000 r / min, and an emulsification time of 5 min;

[0120] The emulsion and glycerol were mixed at a mass ratio of 9:1, and interfacial polymerization reaction was carried out at 50° C. for 3.5 hours to obtain a 25% pyraclostrobin·difenoconazole microcapsule suspension.

[0121] The pesticide microcapsule suspension was tested to have a spontaneous dispersibility of 98% and a suspension rate of 93%. According to the GB / T16150-1995 wet sieving test, ≥98% of the particles passed an 80-mesh test sieve. The encapsulation efficiency was 90% and the drug loading was 89%.

[0122] FIG9 is a scanning electron micrograph of 25% pyraclostrobin·difenoconazole.

[0123] Example 8 Preparation of 21% Padosamil-Tebuconazole Microcapsule Suspension

[0124] 30.9 g of 97% pyraclostrobin and 12.2 g of 98% tebuconazole were dissolved in 8 g of butanone, and 1.8 g of 1,4-butanediol, 13.3 g of isophorone diisocyanate, 15 g of rice bran oil and 0.9 g of Span-80 were mixed to obtain a hydrophobic polyurethane prepolymer B;

[0125] 3.8 g of sodium ethylenediamine sulfonate, 2.7 g of 1,4-butanediol, 15.4 g of poly(1,4-butylene adipate), 22 g of isophorone diisocyanate, and 10 g of butanone were mixed, and 1 g of triethylamine was added dropwise for neutralization. After the reaction, the system was supplemented with deionized water to a mass 1.4 times that of the hydrophobic polyurethane prepolymer B to obtain a hydrophilic prepolymer A;

[0126] The hydrophilic prepolymer A and the hydrophobic polyurethane prepolymer B are mixed and emulsified to obtain an emulsion; the emulsification parameters are: shear rate 9000 r / min, emulsification time 8 min;

[0127] The emulsion and trimethylolpropane were mixed at a mass ratio of 11:1, and interfacial polymerization reaction was carried out at 65° C. for 3 hours to obtain a 21% blastifungin-tebuconazole pesticide microcapsule suspension.

[0128] The spontaneous dispersibility of the pesticide microcapsule suspension was measured to be 97%, and the suspension rate was 91.5%. According to the wet sieving test of GB / T16150-1995, ≥98% of the particles passed through an 80-mesh test sieve. The encapsulation efficiency was measured to be 88%, and the drug loading was 84%.

[0129] FIG10 is a scanning electron micrograph of 21% tebuconazole.

[0130] The particle size distribution and cumulative release rate of the pesticide microcapsules of Examples 2-8 are similar to those of Example 1, and the viscosity is low, the pesticide solution is easy to absorb and drip, and has a rapid self-dispersion effect.

Claims

1. A self-dispersing pesticide microcapsule, characterized in that: It comprises a capsule core and a capsule wall, wherein the pesticide is encapsulated in the capsule core; the inner wall of the capsule wall is hydrophobic polyurethane, and the outer wall is hydrophilic polyurethane.

2. The self-dispersing pesticide microcapsule according to claim 1, characterized in that: The pesticide loading is 80%-99%.

3. The self-dispersing pesticide microcapsule according to claim 1, characterized in that: The particle size is 1-20μm.

4. The method for preparing the self-dispersible pesticide microcapsules according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) isocyanate monomer, small molecule chain extender A, catalyst and pesticide technical dissolved in organic solvent are uniformly mixed with vegetable oil to form a hydrophobic polyurethane prepolymer B; A hydrophilic monomer, a polyol monomer, a small molecule chain extender B, an isocyanate, a catalyst, a neutralizer and an organic solvent are mixed, and water or a surfactant and water are added to form a hydrophilic polyurethane prepolymer A; (2) mixing and emulsifying the hydrophilic polyurethane prepolymer A and the hydrophobic polyurethane prepolymer B to form an emulsion; (3) Add a curing agent to the emulsion to carry out an interfacial polymerization reaction.

5. The preparation method according to claim 4, characterized in that: The hydrophilic monomer is an alcohol amine, or a chain extender with a carboxyl group or a sulfonic acid group. The alcohol amine chain extender is neutralized with an acid, and the chain extender with a carboxyl group or a sulfonic acid group is neutralized with an alkali.

6. The preparation method according to claim 4, characterized in that: The hydrophilic polyurethane prepolymer A is calculated based on the total amount of polyol monomer and isocyanate, the hydrophobic polyurethane prepolymer B is calculated based on the total amount of vegetable oil and isocyanate, and the mass ratio of the hydrophilic polyurethane prepolymer A to the hydrophobic polyurethane prepolymer B is 1-5:

1.

7. The preparation method according to claim 4, characterized in that: In the raw materials of the hydrophobic polyurethane prepolymer B, the mass ratio of the total amount of isocyanate and vegetable oil to the pesticide original is 1:1.5-6; the mass ratio of isocyanate, vegetable oil, catalyst and curing agent is 1:0.8-2:0-0.05:0.02-0.

1.

8. The preparation method according to claim 4, characterized in that: In the raw materials of the hydrophilic polyurethane prepolymer A, the mass ratio of isocyanate to polyol monomer, small molecule chain extender and hydrophilic monomer is 1:0.8-3:0.03-0.15:0.05-0.

2.

9. The method for preparing self-dispersible pesticide microcapsules according to claim 2, characterized in that: The temperature of the interfacial polymerization reaction in step (3) is 40 to 80° C. and the time is 2 to 5 hours.

10. A method for preparing self-dispersible pesticide microcapsules according to any one of claims 1 to 9, characterized in that in step (3), the amount ratio of the emulsion to the curing agent is 1:0.005-0.15 by mass.

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