Self-dispersing type polyurethane pesticide slow-release microcapsule suspending agent and preparation method

Abstract

The present invention relates to the technical field of pesticides. Disclosed is a self-dispersing type polyurethane pesticide slow-release microcapsule suspending agent. A preparation method therefor comprises: (1) mixing a pesticide and an organic solvent with a neutralized polyurethane prepolymer to obtain an oil phase; (2) mixing the oil phase with a colloid stabilizer aqueous solution, and then emulsifying same to obtain an emulsion; and (3) mixing a chain extender and a curing agent with the emulsion to undergo a cross-linking reaction to finally obtain a self-dispersing type polyurethane pesticide slow-release microcapsule suspending agent. A preparation method for the neutralized polyurethane prepolymer comprises: performing a polymerization reaction on polymeric polyol, polyisocyanate, a hydrophilic chain extender and a catalyst to obtain a polyurethane prepolymer; and adding a neutralizer to obtain the neutralized polyurethane prepolymer. The present invention has a simple process, and does not need aids such as an additional emulsifier and dispersing agent. The microcapsule suspending agent dispersed in water has a self-dispersing function, and the suspending agent has good stability.

Description

Self-dispersing polyurethane pesticide sustained-release microcapsule suspension and preparation method thereof Technical Field

[0001] The invention belongs to the technical field of pesticides, and particularly relates to a pesticide microcapsule suspension and a preparation method thereof. Background Art

[0002] Pesticide microencapsulation is the process of coating solid or liquid pesticides. It can protect sensitive pesticide components, extend the effective period of pesticides, reduce pesticide toxicity, and increase the stability of pesticides to environmental factors such as light, heat, and pH. It improves the effective utilization rate of pesticides and can significantly reduce the amount of pesticides used. It has huge advantages compared to traditional pesticide formulations.

[0003] Existing pesticide microcapsules are typically made of hydrophobic polyurethane, which results in poor dispersibility in water and a low suspension efficiency. During dilution or storage, the pesticide microcapsules are prone to stratification and sedimentation, seriously affecting the pesticide's efficacy. Improving the suspension efficiency would allow the active ingredient particles to remain evenly suspended in the spray solution for a longer period of time, maintaining a consistent concentration of the sprayed solution before and after spraying, allowing for even deposition on the target and achieving better efficacy. Furthermore, current pesticide microcapsules are not self-dispersible.

[0004] The existing solution involves adding additives such as dispersants and wetting agents to the microcapsule system to improve the suspension and dispersion stability of the pesticide microcapsules in water. This also creates another problem: the added surfactants, dispersants, or wetting agents can remain in the soil and water, potentially harming crops and other organisms.

[0005] Therefore, it is necessary to improve the existing technology to obtain a pesticide microcapsule that can achieve self-dispersion, reduce the use of various adjuvants, and make the preparation more stable.

[0006] In the actual agricultural production process, disease control is most likely to lead to the development of drug resistance. Combining different fungicide ingredients is a common method for combating resistant diseases. In most cases, the effects of fungicide combinations are additive, with few combinations exhibiting true synergistic effects. Research has found that combining amine with triazole fungicides can produce a significant synergistic effect.

[0007] Yield-enhancing amine, chemically known as 2-(3,4-dichlorophenoxy)triethylamine, is a new bioregulator that can be used throughout the crop life cycle to improve plant photosynthesis efficiency and increase yields and incomes. Yield-enhancing amine is absorbed by plant stems and leaves and acts directly on the cell nucleus, enhancing enzyme activity, promoting cell division and growth. It can also improve the plant's absorption and utilization of carbon dioxide and increase the accumulation and storage of substances such as proteins and lipids. Its use results in noticeable greening, thickening, and enlargement of leaves.

[0008] There are many types of triazole fungicides, which are highly favored for their high efficiency, low toxicity and broad spectrum, and are widely used in disease prevention and control.

[0009] It has been reported that when the mass ratio of amine to tebuconazole is 1:80-80:1, it exhibits a synergistic effect against cucumber powdery mildew, with synergistic ratios (SR) exceeding 1.5. When the ratio is 1:20-20:1, the synergistic effect is even more pronounced, with SRs exceeding 2.35. Furthermore, when the weight ratio of amine to tebuconazole is 1:1, the synergistic ratio is the highest, and the synergistic effect is most pronounced.

[0010] Therefore, the self-dispersing polyurethane microcapsule suspension prepared by combining yield-increasing amine with triazole fungicide has good application prospects.

[0011] Summary of the Invention

[0012] In order to solve the problems existing in the prior art, the present invention provides a self-dispersing polyurethane microcapsule suspension and a preparation method thereof.

[0013] A self-dispersing polyurethane pesticide sustained-release microcapsule suspension. The self-dispersing polyurethane pesticide microcapsules contained in the suspension include a capsule core and a capsule wall. The capsule core contains one or more pesticides, and the capsule wall is polyurethane, which is formed by the polymerization reaction of polymerized polyol, isocyanate and a hydrophilic chain extender and then neutralized.

[0014] The self-dispersing polyurethane pesticide sustained-release microcapsule suspension has excellent self-dispersibility and high drug loading and encapsulation efficiency. It has a self-dispersibility of 95%-97%, a suspension rate of 90%-95%, a drug loading of 85%-95%, and an encapsulation efficiency of over 90%, and can reach 90%-95%.

[0015] Preferably, the pesticide is a mixture of a triazole fungicide and a yield-increasing amine.

[0016] The self-dispersible polyurethane pesticide slow-release microcapsule suspension containing a yield-increasing amine and a triazole fungicide has a good synergistic effect. The mass ratio of the yield-increasing amine to the triazole fungicide is 1:80-80:1, more preferably 1:20-20:1.

[0017] The preparation method of the self-dispersing polyurethane pesticide sustained-release microcapsule suspension comprises the following steps:

[0018] (1) dissolving the pesticide in an organic solvent and mixing it with a neutralized polyurethane prepolymer to obtain an oil phase;

[0019] The preparation method of the neutralized polyurethane prepolymer is as follows:

[0020] (a) polymerizing a polyol, a polyisocyanate, a hydrophilic chain extender, and a catalyst to perform a polymerization reaction to obtain a polyurethane prepolymer, wherein the hydrophilic chain extender is a chain extender having a carboxyl group or a sulfonic acid group;

[0021] (b) adding a neutralizing agent to obtain a neutralized polyurethane prepolymer;

[0022] (2) mixing the oil phase and the aqueous phase and emulsifying them to obtain an emulsion; the aqueous phase is a colloid stabilizer solution;

[0023] (3) Mixing the chain extender and curing agent with the emulsion to carry out a cross-linking reaction.

[0024] In step (a), the molar ratio of the polymerized polyol, polyisocyanate, and hydrophilic chain extender is 1:1-5:0.1-1, preferably 1:2-4:0.5-1. Preferably, the mass ratio of the total amount of the polymerized polyol and polyisocyanate to the catalyst is 1:0.001-0.05, more preferably 1:0.001-0.03. The polymerization reaction temperature is 30-90°C, and the reaction time is 2-6 hours.

[0025] The hydrophilic chain extender is one of dimethylol propionic acid, dimethylol butyric acid, dihydroxy half ester, diaminobenzoic acid, amino acid, N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid, ethylenediaminoethanesulfonic acid, 3-bis(hydroxyethyl)aminopropanesulfonic acid or any mixture thereof.

[0026] In step (b), the molar ratio of the neutralizing agent to the hydrophilic chain extender is 1:0.8-1, preferably 1:1. The neutralizing agent is an organic base or an inorganic base.

[0027] In step (b), the polyurethane prepolymer is cooled to 20-50°C, an organic solvent is added to reduce viscosity, a neutralizing agent is added, and stirring is performed for 5-45 minutes. The mass ratio of the polyurethane prepolymer to the organic solvent is 0.5-10:1, based on the total mass of the polymerized polyol and the polyisocyanate.

[0028] In step (1), based on the total mass of the polymerized polyol and the polyisocyanate, the mass ratio of the neutralized polyurethane prepolymer to the pesticide is 1:0.5-5, preferably 1:1-4; the mass ratio of the pesticide to the organic solvent is 3-10:1, preferably 5-10:1.

[0029] In the oil phase, the mass ratio of pesticide to organic solvent is 2-8:1, preferably 3-6:1.

[0030] In step (2), the mass ratio of the oil phase to the water phase is 1:0.5-3, preferably 1:0.5-1.5, and more preferably 1:0.5-1.

[0031] The amount of the colloid stabilizer used is 0.5 wt% to 3 wt% based on the total amount of the emulsion.

[0032] The emulsification conditions are: shear rate 3000-12000 r / min, shear time 2-30 min.

[0033] In step (3), the mass ratio of the emulsion, the chain extender and the curing agent is 1:0.005-0.1:0.005-0.1; preferably 1:0.005-0.05:0.005-0.05.

[0034] The cross-linking reaction temperature is 50°C-90°C, and the time is 1h-5h, preferably 2-3h.

[0035] In step (1), the polyisocyanate includes 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.

[0036] The polymeric polyol is one or more of polyether polyol, polyester polyol, polycaprolactone, polycarbonate polyol, and polyacrylate polyol, and preferably one or more of polypropylene adipate, polybutylene adipate, polyhexane adipate, polyoxypropylene glycol, polyethylene glycol, polytetrahydrofuran diol, copolyether glycol, polyethylene adipate glycol, polyethylene glycol ether, polyneopentyl adipate, etc. The molecular weight of polyethylene glycol, polyethylene glycol monoacetal, and polyneopentyl adipate is 200 to 4000, the molecular weight of polyoxypropylene glycol is 200 to 4000, and the molecular weight of polytetrahydrofuran diol is 250 to 2000.

[0037] Preferably, the catalyst is an organotin catalyst selected from the group consisting of dibutyltin dilaurate, dimethyltin dilaurate, dioctyltin dilaurate, stannous octoate, dimethyltin diacetate, dibutyltin diacetate, dimethyltin dibutyrate, dibutyltin dibutyrate, dioctyltin dibutyrate, dimethyltin dioleate, dibutyltin dioleate, dioctyltin dioleate, dimethyltin isooctyl dithioacetate, dibutyltin isooctyl dithioacetate, dioctyltin isooctyl dithioacetate, dimethyltin dioctyldecanoate, dibutyltin dioctyldecanoate, and dioctyltin dioctyldecanoate.

[0038] The organic solvent is one or more of dimethylacetamide, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, amyl acetate, sec-butyl acetate, isoamyl citrate, xylene, cyclohexane, acetone, methyl butyl ketone, methyl isobutyl ketone, acetone, butanone, trimethylbenzene, cyclohexanone, 100# solvent oil, 150# solvent oil and 200# solvent oil.

[0039] The neutralizing agent is an organic base or an inorganic base. The inorganic base is one or more of ammonia water, potassium hydroxide, sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate; the organic base is one or more of trimethylamine, triethylamine, tributylamine, diethylenetriamine and tetramethylethylenediamine.

[0040] The pesticide is preferably a mixture of an increasing yield amine and a triazole fungicide, wherein the mass ratio of the increasing yield amine to the triazole fungicide is 1:80-80:1, more preferably 1:20-20:1.

[0041] Further, the triazole fungicide is any one or more of fluopicolide, hexaconazole, difenoconazole, tebuconazole, cyproconazole, penconazole, flusilazole, prothioconazole, propiconazole, cyproconazole, myclobutanil, mandipropamid, fluopicolide, blastamide, thiofuran, boscalid, fluopyram, thiamidine, fluopyram, cyclamates, cyclamates, cyclamates, kresoxim-methyl, azoxystrobin, fluoxastrobin, pyraclostrobin, trifloxystrobin, fenocitar-methyl, kresoxim-methyl, trifloxystrobin, picoxystrobin, fenocitar-methyl, pyraclostrobin, myclobutanil, diniconazole, triadimenol and bitertaconazole.

[0042] In step (2), the colloidal stabilizer is a water-soluble polymer compound. Preferably, it is one or more of polyvinyl alcohol, hydroxyethyl cellulose, polyvinyl pyrrolidone, sodium poly(meth)acrylate, sodium alginate, xanthan gum, and gum arabic; more preferably, the polyvinyl alcohol is of the type 1799, 1788, and 0588; the viscosity-average relative molecular weight of hydroxyethyl cellulose is 15,000-30,000, and the polyvinyl pyrrolidone is of the type PVP-K30.

[0043] In step (3), the chain extender is a polyol, preferably one or more of diethylene glycol, ethylene glycol, butanediol, hexanediol, glycerol, trimethylolpropane, methylpropylene glycol, trishydroxymethylaminomethane, and pentaerythritol.

[0044] The curing agent is a polyamine, preferably one or more of ethylenediamine, hexamethylenediamine, isophoronediamine, meglumine, 1,2-propylenediamine, butanediamine, diethylenetriamine, triethylenetetramine and tetraethylenepentamine.

[0045] The present invention introduces a hydrophilic chain extender during the preparation of the polyurethane capsule wall prepolymer. The carboxyl or sulfonic acid groups on the hydrophilic chain extender are neutralized to form a carboxylate or sulfonate, which enhances the hydrophilicity of the neutralized polyurethane prepolymer, improving its dispersibility in the emulsion and making the resulting emulsion more stable. Furthermore, the addition of an aqueous phase containing a colloidal stabilizer stabilizes the dispersion of the neutralized polyurethane prepolymer particles in the emulsion, thereby reducing the amount of organic solvent and aqueous phase used. The resulting polyurethane pesticide microcapsule suspension not only exhibits excellent self-dispersion properties, but also reduces the amount of surfactants, dispersants, or emulsifiers used. Furthermore, the system exhibits good stability and a high drug loading capacity.

[0046] The beneficial effects of the present invention are:

[0047] (1) The polyurethane pesticide microcapsules have carboxylates or sulfonates on their walls, making them hydrophilic. Therefore, no additional additives are needed or only a small amount of additives are needed to improve the suspension stability of the microcapsules, and the suspension rate can reach more than 90%. Therefore, the microcapsules can be evenly and stably suspended in water for a long time and are not prone to precipitation. During the spraying process, the concentration of the sprayed liquid is relatively consistent, which facilitates long-term operation of the spraying. The liquid is evenly deposited on the target, which can better exert the efficacy of the drug.

[0048] (2) The pesticide microcapsules of the present invention have excellent self-dispersibility, with a spontaneous dispersibility of more than 95%. When diluted for use, no external stirring or emulsifier is required. By simple dropwise addition or mixing, they can be directly and quickly dispersed in water to obtain a uniform pesticide microcapsule suspension, thereby ensuring the effectiveness of the pesticide microcapsules.

[0049] (3) The preparation process is simple, which can reduce the amount of organic solvents and water used. The resulting product has a high drug loading capacity. The pesticide component loading in the microcapsules is more than 85%, the encapsulation efficiency is more than 90%, and the active ingredient contained in the suspension is higher.

[0050] (4) The microcapsules of the present invention have a good sustained-release effect, which enables the production-increasing amine and triazole fungicides to have a good synergistic effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] FIG1 is a scanning electron microscope image of the 25% self-dispersible yield-increasing amine·tebuconazole microcapsules prepared in Example 1.

[0052] FIG2 is a release rate curve of the 25% self-dispersible yield-increasing amine·tebuconazole microcapsules prepared in Example 1. The cumulative release rate reaches more than 50% after 70 hours. DETAILED DESCRIPTION

[0053] Example 1

[0054] (1) 20 g of polycaprolactone (number average molecular weight 1000), 10 g of 4,4'-diphenylmethane diisocyanate, 2.25 g of dimethylolpropionic acid, and 0.3 g of dibutyltin dilaurate were mixed and polymerized at 65°C for 2 h to obtain a polyurethane prepolymer;

[0055] The polyurethane prepolymer was cooled to 30°C, and 8g of ethyl acetate was added and mixed to reduce the viscosity; 1.16g of 25wt% ammonia water was slowly added dropwise to the above mixture for neutralization, and then stirred for 15 minutes to obtain a neutralized polyurethane prepolymer;

[0056] 35.5 g of tebuconazole, 2.7 g of yield-enhancing amine, 4 g of ethyl acetate and a neutralized polyurethane prepolymer were shear-mixed at 550 r / min for 15 min to obtain an oil phase;

[0057] (2) A 4 wt% sodium alginate aqueous solution was used as the aqueous phase; the oil phase and the aqueous phase were mixed in a mass ratio of 1:0.8, and shear emulsified at 12000 r / min for 10 min to prepare an emulsion.

[0058] (3) 1.2 g of glycerol and 0.6 g of ethylenediamine were added to the emulsion; and the mixture was cured at 70° C. for 3 h to obtain 25% self-dispersible yield-enhancing amine-tebuconazole microcapsules.

[0059] The obtained microcapsule suspension was characterized and the performance was analyzed, and the results are as follows.

[0060] 1. Self-dispersion detection

[0061] Detection method: Use standard hard water to prepare the test sample into a suspension of appropriate concentration.

[0062] 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.

[0063] According to the above method, the spontaneous dispersion was measured to be 97%.

[0064] 2. Suspension rate detection

[0065] 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.

[0066] According to the method (the sample is dissolved in a mobile phase, acetonitrile + water + acetic acid is used as the mobile phase, a stainless steel column filled with C18 is used and an ultraviolet detector is used, the pesticides in the sample are separated by reverse phase high performance liquid chromatography at 290 nm, and the external standard method is used for quantification. Gas chromatography can also be used to determine the mass fraction of the pesticide) the mass is measured and the suspension rate is calculated to be 90%.

[0067] 3. Wet screening test

[0068] Wet sieving test was carried out according to GB / T 16150-1995, and ≥98% passed 80-mesh test sieve.

[0069] 4. Encapsulation efficiency and drug loading detection

[0070] The encapsulation efficiency and drug loading of pyraclostrobin were determined by destroying the microcapsules.

[0071] 0.01 g of 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 release all the pesticides therein.

[0072] The absorbance was measured at 274 nm using an ultraviolet spectrophotometer, and the amount of pesticide technical in the microcapsules was calculated based on the standard curve.

[0073] The formulas for calculating the encapsulation efficiency and drug loading of microcapsules are as follows:

[0074] Encapsulation efficiency (%) = weight of original drug in microcapsules / total weight of original drug × 100

[0075] Drug loading (%) = weight of original drug in microcapsules / total weight of microcapsules × 100

[0076] The encapsulation efficiency measured by the above method was 92% and the drug loading was 90%.

[0077] The electron micrograph of the obtained 25% self-dispersible yield-increasing amine·tebuconazole polyurethane sustained-release microcapsules is shown in Figure 1. The release rate curve is shown in Figure 2. After 70-80 hours, the cumulative release rate reaches more than 50%.

[0078] Example 2

[0079] (1) 8 g of polyethylene glycol-400, 13.3 g of lysine diisocyanate, 1.48 g of dimethylolbutyric acid, and 0.2 g of stannous octoate were mixed and polymerized at 60° C. for 2 h to obtain a polyurethane prepolymer;

[0080] The polyurethane prepolymer was cooled to 25°C, and 8g of butyl acetate was added and mixed to reduce the viscosity; 1mL of 10M sodium hydroxide solution was slowly added dropwise to the above mixture for neutralization, and then stirred for 15 minutes to obtain a neutralized polyurethane prepolymer;

[0081] 35 g of epoxiconazole, 10.9 g of yield-enhancing amine, 6 g of butyl acetate and neutralized polyurethane prepolymer were shear-mixed at 600 r / min for 15 min to obtain an oil phase;

[0082] (2) A 3 wt% hydroxyethyl cellulose (viscosity average molecular weight 15000) aqueous solution was used as the aqueous phase; the oil phase and the aqueous phase were mixed in a mass ratio of 1:0.8, and shear emulsified at 12000 r / min for 12 minutes to prepare an emulsion.

[0083] (3) Add 2 g of tris(hydroxymethyl)aminomethane and 2.2 g of triethylenetetramine to the emulsion; perform a curing reaction at 70° C. for 3 h to obtain a 30% self-dispersible yield-enhancing amine-tebuconazole polyurethane sustained-release microcapsule suspension.

[0084] The pesticide slow-release microcapsule suspension concentrate showed a spontaneous dispersibility of 96% and a suspension rate of 92%. According to the GB / T 16150-1995 wet sieving test, ≥98% of the suspension passed an 80-mesh test sieve. The encapsulation efficiency was 94% and the drug loading was 93%.

[0085] Example 3

[0086] (1) 12 g of polyvinyl alcohol-600 (number average molecular weight 600), 10.4 g of toluene diisocyanate, 1.68 g of ethylenediaminoethanesulfonic acid, and 0.3 g of dibutyltin diacetate were mixed and polymerized at 65° C. for 2 h to obtain a polyurethane prepolymer;

[0087] The polyurethane prepolymer was cooled to 30°C, 5g of butanone was added and mixed to reduce the viscosity; 1g of triethylamine was slowly added dropwise to the above mixture for neutralization, and then stirred for 15 minutes to obtain a neutralized polyurethane prepolymer;

[0088] 47 g of cyproconazole, 23 g of yield-enhancing amine, 8 g of butanone and the neutralized polyurethane prepolymer were shear-mixed at 600 r / min for 15 min to obtain an oil phase;

[0089] (2) A 3 wt% gum arabic aqueous solution was used as the aqueous phase; the oil phase and the aqueous phase were mixed in a mass ratio of 1:0.6, and shear emulsified at 12000 r / min for 15 min to prepare an emulsion.

[0090] (3) 1.35 g of methyl propylene glycol and 1.74 g of hexamethylenediamine were added to the emulsion; the mixture was cured at 75° C. for 3 h to obtain a 40% self-dispersible yield-increasing amine-tebuconazole polyurethane sustained-release microcapsule suspension.

[0091] The pesticide slow-release microcapsule suspension concentrate has a spontaneous dispersibility of 95% and a suspension rate of 91%. According to the GB / T 16150-1995 wet sieving test, ≥98% of the contents passed an 80-mesh test sieve. The encapsulation efficiency was 95% and the drug loading was 92%.

[0092] Example 4

[0093] (1) 20 g of polytetramethylene glycol PTMG-1000 (number average molecular weight 1000), 13.1 g of dicyclohexylmethane diisocyanate, 2.1 g of N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid, and 0.3 g of dimethyltin dioleate were mixed and polymerized at 55° C. for 2.5 h to obtain a polyurethane prepolymer;

[0094] The polyurethane prepolymer was cooled to 35°C, and 5g of trimethylbenzene was added and mixed to reduce the viscosity; 1.8g of tributylamine was added to the above mixture for neutralization, and then stirred for 15 minutes to obtain a neutralized polyurethane prepolymer;

[0095] 32g of propiconazole, 24g of yield-enhancing amine, 7g of trimethylbenzene and neutralized polyurethane prepolymer were shear-mixed at 550r / min for 15min to obtain an oil phase;

[0096] (2) A 4 wt% polyvinylpyrrolidone PVP-K30 aqueous solution was used as the aqueous phase; the oil phase and the aqueous phase were mixed in a mass ratio of 1:0.5, and shear emulsified at 12000 r / min for 20 minutes to prepare an emulsion.

[0097] (3) 1.81 g of tris(hydroxymethyl)aminomethane) and 1.32 g of diaminobutane were added to the emulsion; the mixture was cured at 75° C. for 3 h to obtain a 35% self-dispersible yield-enhancing amine-tebuconazole polyurethane sustained-release microcapsule suspension.

[0098] The pesticide slow-release microcapsule suspension concentrate has a spontaneous dispersibility of 95% and a suspension rate of 94%. According to the GB / T 16150-1995 wet sieving test, ≥98% of the contents passed an 80-mesh test sieve. The encapsulation efficiency was 91% and the drug loading was 90%.

[0099] The sustained-release microcapsule suspension prepared in Examples 2-4 has a sustained-release effect, and the cumulative release rate in 60-80 hours exceeds 50%.

Claims

1. A self-dispersible polyurethane pesticide sustained-release microcapsule suspension, wherein the self-dispersible polyurethane pesticide microcapsules contained in the suspension include a capsule core and a capsule wall, wherein the capsule core contains one or more pesticides, and the capsule wall is polyurethane, which is formed by polymerization reaction of a polymerized polyol, an isocyanate and a hydrophilic chain extender and then neutralized.

2. The self-dispersible polyurethane pesticide sustained-release microcapsule suspension according to claim 1, characterized in that: Its self-dispersibility is 95%-97% and its suspension rate is 90%-95%.

3. The self-dispersing polyurethane pesticide microcapsule according to claim 1, characterized in that: The pesticide is a mixture of triazole fungicides and yield-increasing amines.

4. The method for preparing the self-dispersible polyurethane pesticide sustained-release microcapsule suspension according to any one of claims 1 to 3, characterized in that the steps include: (1) dissolving the pesticide in an organic solvent and mixing it with a neutralized polyurethane prepolymer to obtain an oil phase; The preparation method of the neutralized polyurethane prepolymer is as follows: (a) polymerizing polyol, polyisocyanate, hydrophilic chain extender and catalyst to obtain polyurethane prepolymer; (b) adding a neutralizing agent to obtain a neutralized polyurethane prepolymer; (2) mixing the oil phase and the water phase and emulsifying them to obtain an emulsion; the water phase is a colloid stabilizer solution, and the colloid stabilizer is a water-soluble polymer compound; (3) Mixing the chain extender and curing agent with the emulsion to carry out a cross-linking reaction.

5. The method for preparing the self-dispersible polyurethane pesticide sustained-release microcapsule suspension according to claim 4, characterized in that: In step (a), the molar ratio of polymerized polyol, polyisocyanate and hydrophilic chain extender is 1:1-5:0.3-1; the mass ratio of the total amount of polymerized polyol and polyisocyanate to the catalyst is 1:0.001-0.

05.

6. The method for preparing the self-dispersible polyurethane pesticide sustained-release microcapsule suspension according to claim 4, characterized in that: In step (1), the mass ratio of the polyurethane prepolymer to the pesticide is 1:0.5-5, based on the total amount of the polymerized polyol and the polyisocyanate.

7. The method for preparing the self-dispersible polyurethane pesticide sustained-release microcapsule suspension according to claim 4, characterized in that: The hydrophilic chain extender is a chain extender with a carboxyl group or a sulfonic acid group; the neutralizer is an organic base or an inorganic base.

8. The method for preparing the self-dispersible polyurethane pesticide sustained-release microcapsule suspension according to claim 4, characterized in that: The colloidal stabilizer is selected from one or more of polyvinyl alcohol, hydroxyethyl cellulose, polyvinyl pyrrolidone, sodium polymethacrylate, sodium alginate, xanthan gum, and gum arabic.

9. The method for preparing the self-dispersible polyurethane pesticide sustained-release microcapsule suspension according to claim 4, characterized in that: The pesticide is a mixture of yield-increasing amine and triazole fungicide.

10. The method for preparing the self-dispersible polyurethane pesticide sustained-release microcapsule suspension according to claim 4, characterized in that: In step (3), the mass ratio of the emulsion, the chain extender and the curing agent is 1:0.005-0.1:0.005-0.1; and the cross-linking reaction conditions are: reacting at 50°C-90°C for 1h-5h.

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