A hexaconazole polyurea microcapsule with a controllable sustained release rate prepared based on a chain structure design, its preparation method and application

Abstract

The present invention provides a hexaconazole polyurea microcapsule with a controllable sustained-release rate designed and prepared based on a chain structure, and its preparation method and application, belonging to the technical field of pesticide microcapsules. In the present invention, different types of polyamines are polymerized with diisocyanates to prepare microcapsule shells with different degrees of crosslinking and chain flexibility. During use, the sustained-release rate of hexaconazole is controlled according to the different chain segment movement abilities and swellabilities. The present invention controls the degree of crosslinking and chain flexibility of the polyurea microcapsule carrier by regulating the polymerization monomers, further regulates the release rate of hexaconazole, and greatly improves the selectivity of the application scenarios of hexaconazole. Further, the preparation method provided by the present invention has a high yield of polyurea microcapsules, is simple to operate, has low environmental pollution, strong adaptability of production equipment, low production cost, and is suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of pesticide microcapsules, and particularly relates to a hexaconazole polyurea microcapsule with a controllable slow-release rate prepared based on chain structure design, and a preparation method and application thereof. Background Art

[0002] Pesticides, as the main means of chemical control, have been widely used. Hexaconazole is a triazole fungicide developed by Syngenta in 1980. It is a sterol demethylation inhibitor and is used to control diseases such as grape powdery mildew, black rot, apple scab and powdery mildew. It has a broad-spectrum protective and eradicative effect on diseases caused by fungi. However, due to various environmental factors such as microbial degradation, light and leaching, a large amount of pesticides are lost. In order to achieve the purpose of sterilization, farmers have to increase the dosage and application frequency, resulting in problems such as the generation of resistance in target organisms, environmental pollution and harm to non-target organisms.

[0003] Traditional pesticide formulations mainly include suspension concentrates, emulsifiable concentrates, water-dispersible granules, wettable powders and microemulsions. During the application process, the original drug is directly exposed to the environment, resulting in problems such as short effective period, low utilization rate and large residues. Therefore, the development of pesticide slow-release dosage forms has become particularly important.

[0004] As a type of slow-release preparation, microcapsules can encapsulate active ingredients, reduce the influence of the environment on active ingredients, reduce the acute contact toxicity to non-target organisms, and at the same time enable the active ingredients to be slowly released. However, the slow-release rate of existing pesticide microcapsules is uncontrollable, and the selectivity of their application scenarios is poor, which limits their wide use in agriculture. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a hexaconazole polyurea microcapsule with a controllable slow-release rate prepared based on chain structure design, and a preparation method and application thereof. The method provided by the present invention can regulate the crosslinking degree of the polyurea microcapsule carrier, further regulate the release rate of hexaconazole, and greatly improve the selectivity of the application scenarios of hexaconazole.

[0006] In order to achieve the above invention purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a hexaconazole polyurea microcapsule with a controllable slow-release rate based on chain structure design, comprising the following steps:

[0008] Mix hexaconazole, core solvent and polyisocyanate to obtain an oil phase;

[0009] Mix an emulsifier and water to obtain an aqueous phase;

[0010] Add the oil phase to the aqueous phase, and shear and mix to obtain an emulsion;

[0011] Mix the polyamine with the emulsion and carry out an interfacial polymerization reaction to obtain hexaconazole polyurea microcapsules;

[0012] The polyamine includes one or more of diamine, triamine, tetraamine, and pentamine.

[0013] Preferably, based on mass percentage, the raw materials used in the method include:

[0014]

[0015] Preferably, the diamine includes one or more of ethylenediamine, butanediamine, hexanediamine, piperazine, and lysine;

[0016] The triamine includes diethylenetriamine;

[0017] The tetraamine includes triethylenetetramine;

[0018] The pentamine includes tetraethylenepentamine.

[0019] Preferably, the polyisocyanate includes one or more of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate, and lysine diisocyanate;

[0020] The core solvent is one or more of ketone solvents, alcohol solvents, solvent oils, ester solvents, substituted alkane solvents, and alkane solvents;

[0021] The emulsifier includes one or more of agricultural emulsion series emulsifiers, NP series emulsifiers, AEO series emulsifiers, Tween series emulsifiers, and EL series emulsifiers.

[0022] Preferably, after the interfacial polymerization reaction, a dispersant and / or a stabilizer is further added to the obtained interfacial polymerization reaction solution to obtain hexaconazole polyurea microcapsules;

[0023] The dispersant includes one or more of sodium polycarboxylate, sodium dodecylbenzenesulfonate, and polyphosphates;

[0024] The stabilizer is one or more of polyoxyethylene ether, sodium alkylbenzenesulfonate, calcium carbonate, and ethylene glycol.

[0025] Preferably, the mass ratio of the dispersant to hexaconazole is 0.5 - 4:1 - 35;

[0026] The mass ratio of the stabilizer to hexaconazole is 0.5 - 3:1 - 35.

[0027] Preferably, the rate of shear mixing is 10,000 - 15,000 r / min, and the time is 10 - 15 min.

[0028] Preferably, the temperature of the interfacial polymerization reaction is 30 - 60 °C, and the time is 0.5 - 2 h.

[0029] The present invention provides the hexaconazole polyurea microcapsules prepared by the above method, including a hexaconazole core and a polyurea shell.

[0030] The present invention provides the application of the above hexaconazole polyurea microcapsules in the preparation of drugs for preventing grape powdery mildew, black rot, apple scab, powdery mildew, and wheat sheath blight.

[0031] The present invention provides a method for preparing hexaconazole polyurea microcapsules with a controllable sustained-release rate based on chain structure design, including the following steps: mixing hexaconazole, a core solvent, and a polyisocyanate to obtain an oil phase; mixing an emulsifier and water to obtain an aqueous phase; adding the oil phase to the aqueous phase and performing shear mixing to obtain an emulsion; mixing a polyamine with the emulsion and performing an interfacial polymerization reaction to obtain hexaconazole polyurea microcapsules; the polyamine includes one or several of diamine, triamine, tetraamine, and pentamine; when the polyamine includes triamine, tetraamine, or pentamine, high-crosslinking-degree hexaconazole polyurea microcapsules are obtained; when the polyamine is diamine, low-crosslinking-degree hexaconazole polyurea microcapsules are obtained. In the present invention, the release of hexaconazole needs to penetrate through the polymer film formed by polyurea, greatly improving the utilization rate of hexaconazole and the product safety. The present invention prepares microcapsule shells with different crosslinking degrees and chain flexibility by polymerizing diisocyanate with different types of polyamines, and controls the sustained-release rate of hexaconazole according to the different chain segment movement abilities and swellabilities during use. Specifically, polymerizing with polyamines having a long alkyl chain length results in a low-crosslinking-degree microcapsule shell, and polymerizing with polyamines having a short alkyl chain length results in a high-crosslinking-degree microcapsule shell; polymerizing with polyamines having a long alkyl chain length and no rigid chain segments can obtain a shell with good flexibility, and polymerizing with polyamines having rigid chain segments can obtain a shell with poor flexibility. A low crosslinking degree, good chain segment flexibility, and the presence of side groups in the chain segment result in a fast sustained-release rate of the microcapsules. A high crosslinking degree and strong chain segment rigidity result in poor swellability of the obtained polyurea shell, making the sustained-release rate of the capsule slow. The present invention controls the crosslinking degree and chain flexibility of the polyurea microcapsule carrier by regulating the polymerization monomers, further regulating the release rate of hexaconazole, and greatly improving the selectivity of the application scenarios of hexaconazole.

[0032] Furthermore, the preparation method provided by the present invention has a high yield of polyurea microcapsules, is easy to operate, has low environmental pollution, strong adaptability of production equipment, low production cost, and is suitable for industrial production. Description of the Drawings

[0033] Figure 1SEM image of the hexaconazole polyurea microcapsules obtained in Example 1;

[0034] Figure 2 SEM image of the hexaconazole polyurea microcapsules obtained in Example 2;

[0035] Figure 3 SEM image of the hexaconazole polyurea microcapsules obtained in Example 3;

[0036] Figure 4 SEM image of the hexaconazole polyurea microcapsules obtained in Example 4;

[0037] Figure 5 SEM image of the hexaconazole polyurea microcapsules obtained in Example 5;

[0038] Figure 6 SEM image of the hexaconazole polyurea microcapsules obtained in Example 6;

[0039] Figure 7 SEM image of the hexaconazole polyurea microcapsules obtained in Example 7;

[0040] Figure 8 SEM image of the hexaconazole polyurea microcapsules obtained in Example 8;

[0041] Figure 9 SEM image of the hexaconazole polyurea microcapsules obtained in Example 9;

[0042] Figure 10 SEM image of the hexaconazole polyurea microcapsules obtained in Example 10;

[0043] Figure 11 SEM image of the hexaconazole polyurea microcapsules obtained in Example 11;

[0044] Figure 12 SEM image of the hexaconazole polyurea microcapsules obtained in Example 12;

[0045] Figure 13 Sustained-release performance graph of the hexaconazole polyurea microcapsules prepared in Examples 1-4;

[0046] Figure 14 Sustained-release performance graph of the hexaconazole polyurea microcapsules prepared in Examples 5-8;

[0047] Figure 15 Sustained-release performance graph of the hexaconazole polyurea microcapsules prepared in Examples 9-12. Detailed implementation manners

[0048] The present invention provides a method for preparing hexaconazole polyurea microcapsules with a controllable sustained-release rate based on chain structure design, comprising the following steps:

[0049] Mix hexaconazole, core solvent and polyisocyanate to obtain an oil phase;

[0050] Mix an emulsifier and water to obtain an aqueous phase;

[0051] Add the oil phase to the aqueous phase and shear-mix to obtain an emulsion;

[0052] Mix a polyamine with the emulsion and carry out an interfacial polymerization reaction to obtain hexaconazole polyurea microcapsules;

[0053] The polyamine includes one or more of diamine, triamine, tetraamine and pentamine.

[0054] Unless otherwise specified, the raw materials used in the present invention are all commercially available.

[0055] In the present invention, by mass percentage, the preparation raw materials used in the method preferably include:

[0056] Hexaconazole 1-35%, more preferably 5-30%, further preferably 10-20%;

[0057] Core solvent 1-30%, more preferably 5-25%, further preferably 10-20%;

[0058] Polyisocyanate 1-15%, more preferably 5-10%;

[0059] Polyamine 1-13%, more preferably 3-10%;

[0060] Emulsifier 1-5%, more preferably 2-4%;

[0061] Water as the balance.

[0062] In the present invention, hexaconazole, core solvent and polyisocyanate are mixed to obtain an oil phase. In the present invention, the core solvent is preferably one or more of ketone solvents, alcohol solvents, solvent oils, ester solvents, substituted alkane solvents and alkane solvents; the ketone solvents are preferably one or more of acetone, cyclohexanone and methyl isobutyl ketone; the alcohol solvents are preferably one or more of ethanol, butanol and octanol; the alkane solvents are preferably one or more of rosin spirit, n-hexane and cyclohexane.

[0063] In the present invention, the polyisocyanate preferably includes one or more of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate and lysine diisocyanate.

[0064] The present invention has no special requirements on the mixing method, and the mixing methods well-known to those skilled in the art can be used, such as stirring and mixing specifically.

[0065] In the present invention, an emulsifier and water are mixed to obtain an aqueous phase. In the present invention, the emulsifier preferably includes one or more of agricultural emulsifier series, NP series emulsifier, AEO series emulsifier, Tween series emulsifier, and EL series emulsifier. In the present invention, the agricultural emulsifier series preferably includes one or more of agricultural emulsifier 300#, agricultural emulsifier 500#, and agricultural emulsifier 600#; the NP series emulsifier preferably includes NP-7 and / or NP-10; the AEO series emulsifier preferably includes one or more of AEO-3, AEO-7, and AEO-9; the Tween series emulsifier preferably includes one or more of Tween 20, Tween 60, and Tween 80; the EL series emulsifier preferably includes one or more of EL-10, EL-40, and EL-60.

[0066] The present invention has no special requirements for the mixing method, and a mixing method well-known to those skilled in the art can be used, such as stirring and mixing.

[0067] After obtaining the oil phase and the aqueous phase, in the present invention, the oil phase is added to the aqueous phase and shear-mixed to obtain an emulsion. In the present invention, the rate of the shear mixing is preferably 10000 r / min, and the time is preferably 10 min.

[0068] After obtaining the emulsion, in the present invention, a polyamine is mixed with the emulsion to carry out an interfacial polymerization reaction to obtain hexaconazole polyurea microcapsules. In the present invention, the diamine preferably includes one or more of ethylenediamine, butanediamine, hexanediamine, piperazine, and lysine; the triamine preferably includes diethylenetriamine; the tetraamine preferably includes triethylenetetramine; the pentamine preferably includes tetraethylenepentamine.

[0069] In the present invention, when the polyamine is a mixture of multiple components, the polyamine is preferably a combination of triethylenetetramine and ethylenediamine, a combination of triethylenetetramine and lysine, a combination of triethylenetetramine and piperazine, a combination of tetraethylenepentamine and ethylenediamine, a combination of tetraethylenepentamine and butanediamine, a combination of triethylenetetramine and butanediamine, a combination of triethylenetetramine and hexanediamine, or a combination of diethylenetriamine and hexanediamine.

[0070] In the present invention, when the polyamine is a triamine, tetraamine, or pentamine, high-crosslinking-degree hexaconazole polyurea microcapsules are obtained; when the polyamine is a diamine, low-crosslinking-degree hexaconazole polyurea microcapsules are obtained.

[0071] In the present invention, the mixing method is preferably to drop the polyamine into the emulsion, and the dropping rate is preferably 10 - 30 drops / min, more preferably 20 drops / min.

[0072] In the present invention, the temperature of the interfacial polymerization reaction is preferably 50 °C, and the time is preferably 1 h.

[0073] In the present invention, after the interfacial polymerization reaction, it is further preferred to include adding a dispersant and / or a stabilizer to the obtained interfacial polymerization reaction solution to obtain hexaconazole polyurea microcapsules.

[0074] In the invention, the dispersant is preferably one or more of sodium polycarboxylate, sodium dodecylbenzenesulfonate, and polyphosphate; the mass ratio of the dispersant to hexaconazole is preferably 0.5 - 4:1 - 35, more preferably 1 - 3:1 - 35;

[0075] In the present invention, the stabilizer is preferably one or more of polyoxyethylene ether, sodium alkylbenzenesulfonate, calcium carbonate, and ethylene glycol; the mass ratio of the stabilizer to hexaconazole is preferably 0.5 - 3:1 - 35, more preferably 1 - 2:1 - 35.

[0076] In the present invention, after the interfacial polymerization reaction, a hexaconazole polyurea microcapsule suspension is obtained. The present invention preferably performs solid-liquid separation on the obtained hexaconazole polyurea microcapsule suspension, and washes and dries the obtained solid to obtain hexaconazole polyurea microcapsules.

[0077] In the present invention, the method of solid-liquid separation is preferably centrifugation; the washing is preferably ethanol washing and water washing, and the number of times of ethanol washing and water washing is 2 times respectively. In the present invention, the drying temperature is preferably 40 °C, and the time is preferably 24 h.

[0078] The present invention provides the hexaconazole polyurea microcapsules prepared by the above method, including a hexaconazole core and a polyurea shell. In the present invention, the particle size of the hexaconazole polyurea microcapsules is preferably 1 - 3 microns, more preferably 2 microns.

[0079] The present invention provides the application of the above hexaconazole polyurea microcapsules in the preparation of drugs for treating grape powdery mildew, black rot, apple scab, powdery mildew, and wheat sheath blight.

[0080] The following combines examples to elaborate in detail on the hexaconazole polyurea microcapsules with a controllable release rate prepared based on chain structure design provided by the present invention, its preparation method and application, but they cannot be understood as limiting the protection scope of the present invention.

[0081] Example 1

[0082] By mass percentage, the raw materials for preparing hexaconazole polyurea microcapsule suspensions with different release rates through chain structure design in this example are shown in Table 1, and the preparation method includes the following steps:

[0083] Dissolve hexaconazole in 200# solvent naphtha, add isophorone diisocyanate, and stir and mix evenly to obtain an oil phase;

[0084] Add Tween 80 to water, stir and mix evenly to obtain an aqueous phase;

[0085] Mix the oil phase and the aqueous phase, perform high-speed shear emulsification at 10000 r / min for 10 min to obtain a uniform and stable emulsion. Drop the triethylenetetramine aqueous solution into the reaction kettle at a rate of 20 drops / min, and react at 500 r / min and 50 °C for 1 h; add sodium polycarboxylate to the obtained system and stir evenly for 30 min to obtain a hexaconazole polyurea microcapsule suspension designed by chain structure.

[0086] Centrifuge the hexaconazole polyurea microcapsule suspension designed by chain structure, wash the substrate twice with ethanol and water respectively, and dry at 40 °C for 24 h to obtain hexaconazole polyurea microcapsules designed by chain structure.

[0087] Example 2

[0088] By mass percentage, the raw materials for preparing hexaconazole polyurea microcapsule suspensions with different slow-release rates by chain structure design in this example are shown in Table 1. The preparation method includes the following steps:

[0089] Dissolve hexaconazole in ethyl acetate, add isophorone diisocyanate, and stir and mix evenly to obtain an oil phase;

[0090] Add polyvinyl alcohol to water, stir and mix evenly to obtain an aqueous phase;

[0091] Mix the oil phase and the aqueous phase, perform high-speed shear emulsification at 10000 r / min for 10 min to obtain a uniform and stable emulsion. Drop the tetraethylenepentamine aqueous solution into the reaction kettle at a rate of 20 drops / min, and react at 500 r / min and 50 °C for 1 h; add sodium dodecylbenzenesulfonate to the obtained system and stir evenly for 30 min to obtain a hexaconazole polyurea microcapsule suspension designed by chain structure.

[0092] Centrifuge the hexaconazole polyurea microcapsule suspension designed by chain structure, wash the substrate twice with ethanol and water respectively, and dry at 40 °C for 24 h to obtain hexaconazole polyurea microcapsules designed by chain structure.

[0093] Example 3

[0094] By mass percentage, the raw materials for preparing hexaconazole polyurea microcapsule suspensions with different slow-release rates by chain structure design in this example are shown in Table 1. The preparation method includes the following steps:

[0095] Dissolve hexaconazole in butyl acetate, add toluene diisocyanate, and stir and mix evenly to obtain an oil phase;

[0096] Add EL-40 to water, stir and mix evenly to obtain an aqueous phase;

[0097] Mix the oil phase and the aqueous phase, perform high-speed shear emulsification at 10000 r / min for 10 min to obtain a uniform and stable emulsion. Drop the mixed aqueous solution of triethylenetetramine and ethylenediamine into the reaction kettle at a rate of 20 drops / min, and react at 500 r / min and 50 °C for 1 h; add sodium polycarboxylate to the obtained system and stir evenly for 30 min to obtain a hexaconazole polyurea microcapsule suspension designed by chain structure.

[0098] Centrifuge the hexaconazole polyurea microcapsule suspension designed by chain structure, wash the substrate twice with ethanol and water respectively, and dry at 40 °C for 24 h to obtain hexaconazole polyurea microcapsules designed by chain structure.

[0099] Example 4

[0100] By mass percentage, the raw materials for preparing hexaconazole polyurea microcapsule suspensions with different slow-release rates designed by chain structure in this example are shown in Table 1. The preparation method includes the following steps:

[0101] Dissolve hexaconazole in cyclohexanone, add toluene diisocyanate, and stir and mix evenly to obtain an oil phase;

[0102] Add polyvinyl alcohol to water, stir and mix evenly to obtain an aqueous phase;

[0103] Mix the oil phase and the aqueous phase, perform high-speed shear emulsification at 10000 r / min for 10 min to obtain a uniform and stable emulsion. Drop the mixed aqueous solution of triethylenetetramine and lysine into the reaction kettle at a rate of 20 drops / min, and react at 500 r / min and 50 °C for 1 h; add sodium dodecylbenzenesulfonate to the obtained system and stir evenly for 30 min to obtain a hexaconazole polyurea microcapsule suspension designed by chain structure.

[0104] Centrifuge the hexaconazole polyurea microcapsule suspension designed by chain structure, wash the substrate twice with ethanol and water respectively, and dry at 40 °C for 24 h to obtain hexaconazole polyurea microcapsules designed by chain structure.

[0105] Example 5

[0106] By mass percentage, the raw materials for preparing hexaconazole polyurea microcapsule suspensions with different slow-release rates designed by chain structure in this example are shown in Table 2. The preparation method includes the following steps:

[0107] Dissolve hexaconazole in 200# solvent naphtha, add hexamethylene diisocyanate, and stir and mix evenly to obtain an oil phase;

[0108] Add NP-10 to water, stir and mix evenly to obtain an aqueous phase;

[0109] Mix the said oil phase and aqueous phase, carry out high-speed shear emulsification at 10000 r / min for 10 min to obtain a uniform and stable emulsion, dropwise add the mixed aqueous solution of triethylenetetramine and piperazine into the reaction kettle at a rate of 20 drops / min, and react at 500 r / min and 50 °C for 1 h; add sodium dodecylbenzenesulfonate to the obtained system, stir evenly for 30 min to obtain a hexaconazole polyurea microcapsule suspension designed by chain structure.

[0110] Centrifuge the hexaconazole polyurea microcapsule suspension designed by chain structure, wash the substrate twice with ethanol and water respectively, and dry at 40 °C for 24 h to obtain hexaconazole polyurea microcapsules designed by chain structure.

[0111] Example 6

[0112] By mass percentage, the preparation raw materials for preparing hexaconazole polyurea microcapsule suspensions with different slow-release rates by chain structure design in this example are shown in Table 2, and the preparation method includes the following steps:

[0113] Dissolve hexaconazole in butyl acetate, add hexamethylene diisocyanate, and stir and mix evenly to obtain an oil phase;

[0114] Add EL-40 to water, stir and mix evenly to obtain an aqueous phase;

[0115] Mix the said oil phase and aqueous phase, carry out high-speed shear emulsification at 10000 r / min for 10 min to obtain a uniform and stable emulsion, dropwise add the mixed aqueous solution of tetraethylenepentamine and ethylenediamine into the reaction kettle at a rate of 20 drops / min, and react at 500 r / min and 50 °C for 1 h; add sodium polycarboxylate to the obtained system, stir evenly for 30 min to obtain a hexaconazole polyurea microcapsule suspension designed by chain structure.

[0116] Centrifuge the hexaconazole polyurea microcapsule suspension designed by chain structure, wash the substrate twice with ethanol and water respectively, and dry at 40 °C for 24 h to obtain hexaconazole polyurea microcapsules designed by chain structure.

[0117] Example 7

[0118] By mass percentage, the preparation raw materials for preparing hexaconazole polyurea microcapsule suspensions with different slow-release rates by chain structure design in this example are shown in Table 2, and the preparation method includes the following steps:

[0119] Dissolve hexaconazole in ethyl acetate, add lysine diisocyanate, and stir to mix evenly to obtain an oil phase;

[0120] Add Tween 80 to water, and stir to mix evenly to obtain an aqueous phase;

[0121] Mix the oil phase and the aqueous phase, and perform high-speed shear emulsification at 10000 r / min for 10 min to obtain a uniform and stable emulsion. Drop the mixed aqueous solution of triethylenetetramine and lysine into the reaction kettle at a rate of 20 drops / min, and react at 500 r / min and 50 °C for 1 h; add sodium dodecylbenzenesulfonate to the obtained system and stir evenly for 30 min to obtain a hexaconazole polyurea microcapsule suspension designed by chain structure.

[0122] Centrifuge the hexaconazole polyurea microcapsule suspension designed by chain structure, wash the substrate twice with ethanol and water respectively, and dry at 40 °C for 24 h to obtain hexaconazole polyurea microcapsules designed by chain structure.

[0123] Example 8

[0124] By mass percentage, the raw materials for preparing hexaconazole polyurea microcapsule suspensions with different slow-release rates designed by chain structure in this example are shown in Table 2. The preparation method includes the following steps:

[0125] Dissolve hexaconazole in butyl acetate, add lysine diisocyanate, and stir to mix evenly to obtain an oil phase;

[0126] Add polyvinyl alcohol to water, and stir to mix evenly to obtain an aqueous phase;

[0127] Mix the oil phase and the aqueous phase, and perform high-speed shear emulsification at 10000 r / min for 10 min to obtain a uniform and stable emulsion. Drop the aqueous solution of triethylenetetramine into the reaction kettle at a rate of 20 drops / min, and react at 500 r / min and 50 °C for 1 h; add sodium polycarboxylate to the obtained system and stir evenly for 30 min to obtain a hexaconazole polyurea microcapsule suspension designed by chain structure.

[0128] Centrifuge the hexaconazole polyurea microcapsule suspension designed by chain structure, wash the substrate twice with ethanol and water respectively, and dry at 40 °C for 24 h to obtain hexaconazole polyurea microcapsules designed by chain structure.

[0129] Example 9

[0130] By mass percentage, the raw materials for preparing hexaconazole polyurea microcapsule suspensions with different slow-release rates designed by chain structure in this example are shown in Table 3. The preparation method includes the following steps:

[0131] Dissolve hexaconazole in 200# solvent naphtha, add diphenylmethane diisocyanate, and stir and mix evenly to obtain an oil phase;

[0132] Add EL-40 to water, and stir and mix evenly to obtain an aqueous phase;

[0133] Mix the oil phase and the aqueous phase, and perform high-speed shear emulsification at 10000 r / min for 10 min to obtain a uniform and stable emulsion. Drop tetraethylenepentamine and aqueous butanediamine solution into the reaction kettle at a rate of 20 drops / min, and react at 500 r / min and 50 °C for 1 h; Add sodium dodecylbenzenesulfonate to the obtained system, and stir evenly for 30 min to obtain a hexaconazole polyurea microcapsule suspension designed by chain structure.

[0134] Centrifuge the hexaconazole polyurea microcapsule suspension designed by chain structure, wash the substrate twice with ethanol and water respectively, and dry at 40 °C for 24 h to obtain hexaconazole polyurea microcapsules designed by chain structure.

[0135] Example 10

[0136] By mass percentage, the preparation raw materials for preparing hexaconazole polyurea microcapsule suspensions with different slow-release rates by chain structure design in this example are shown in Table 3. The preparation method includes the following steps:

[0137] Dissolve hexaconazole in ethyl acetate, add diphenylmethane diisocyanate, and stir and mix evenly to obtain an oil phase;

[0138] Add polyvinyl alcohol to water, and stir and mix evenly to obtain an aqueous phase;

[0139] Mix the oil phase and the aqueous phase, and perform high-speed shear emulsification at 10000 r / min for 10 min to obtain a uniform and stable emulsion. Drop triethylenetetramine and aqueous butanediamine solution into the reaction kettle at a rate of 20 drops / min, and react at 500 r / min and 50 °C for 1 h; Add sodium polycarboxylate to the obtained system, and stir evenly for 30 min to obtain a hexaconazole polyurea microcapsule suspension designed by chain structure.

[0140] Centrifuge the hexaconazole polyurea microcapsule suspension designed by chain structure, wash the substrate twice with ethanol and water respectively, and dry at 40 °C for 24 h to obtain hexaconazole polyurea microcapsules designed by chain structure.

[0141] Example 11

[0142] By mass percentage, the preparation raw materials for preparing hexaconazole polyurea microcapsule suspensions with different slow-release rates by chain structure design in this example are shown in Table 3. The preparation method includes the following steps:

[0143] Dissolve hexaconazole in butyl acetate, add dicyclohexylmethane diisocyanate, and stir and mix evenly to obtain an oil phase;

[0144] Add Tween 80 to water, stir and mix evenly to obtain an aqueous phase;

[0145] Mix the said oil phase and aqueous phase, perform high-speed shear emulsification at 10000 r / min for 10 min to obtain a uniform and stable emulsion. Drop triethylenetetramine and hexamethylenediamine aqueous solution into the reaction kettle at a rate of 20 drops / min, and react at 500 r / min and 50 °C for 1 h; add sodium dodecylbenzenesulfonate to the obtained system, stir evenly for 30 min to obtain a hexaconazole polyurea microcapsule suspension designed by chain structure.

[0146] Centrifuge the hexaconazole polyurea microcapsule suspension designed by chain structure, wash the substrate twice with ethanol and water respectively, and dry at 40 °C for 24 h to obtain hexaconazole polyurea microcapsules designed by chain structure.

[0147] Example 12

[0148] By mass percentage, the preparation raw materials for preparing hexaconazole polyurea microcapsule suspensions with different slow-release rates by chain structure design in this example are shown in Table 3. The preparation method includes the following steps:

[0149] Dissolve hexaconazole in 200# solvent oil, add dicyclohexylmethane diisocyanate, and stir and mix evenly to obtain an oil phase;

[0150] Add polyvinyl alcohol to water, stir and mix evenly to obtain an aqueous phase;

[0151] Mix the said oil phase and aqueous phase, perform high-speed shear emulsification at 10000 r / min for 10 min to obtain a uniform and stable emulsion. Drop diethylenetriamine and hexamethylenediamine aqueous solution into the reaction kettle at a rate of 20 drops / min, and react at 500 r / min and 50 °C for 1 h; add sodium polycarboxylate to the obtained system, stir evenly for 30 min to obtain a hexaconazole polyurea microcapsule suspension designed by chain structure.

[0152] Centrifuge the hexaconazole polyurea microcapsule suspension designed by chain structure, wash the substrate twice with ethanol and water respectively, and dry at 40 °C for 24 h to obtain hexaconazole polyurea microcapsules designed by chain structure.

[0153] Table 1 Preparation raw materials and mass percentages in Examples 1-4

[0154]

[0155]

[0156] Table 2 Preparation raw materials and mass percentages in Examples 5 - 8

[0157]

[0158] Table 3 Preparation raw materials and mass percentages in Examples 9 - 12

[0159]

[0160]

[0161] The hexaconazole polyurea microcapsules prepared by chain structure design in Examples 1 - 12 were characterized as follows:

[0162] 1. Figures 1 to 12 SEM images of the hexaconazole polyurea microcapsules prepared by chain structure design in Examples 1 - 12 respectively. As can be seen from Figures 1 to 12 it, the morphology of the hexaconazole polyurea microcapsules prepared by chain structure design is approximately spherical with uniform particle size. The polyurea microcapsules formed by the polymerization of different monomers have different surface morphologies. The higher the cross - linking degree of the polyurea microcapsules, the denser and smoother the surface morphology of the microcapsules. The growth of the alkyl chain, the increase of side groups, and the decrease of cross - linking degree in the polyurea microcapsules will all lead to the rough and wrinkled surface morphology of the microcapsules.

[0163] 2. Figures 13 to 15 The sustained - release performance diagrams of the hexaconazole polyurea microcapsules prepared in Examples 1 - 12. Figure 13 In it, a - d are respectively toluene diisocyanate with triethylenetetramine and lysine (Example 4), toluene diisocyanate with triethylenetetramine and ethylenediamine (Example 3), isophorone diisocyanate with triethylenetetramine (Example 1), isophorone diisocyanate with tetraethylenepentamine (Example 2). Figure 14 In it, e - h are respectively hexamethylene diisocyanate with triethylenetetramine and piperazine (Example 5), hexamethylene diisocyanate with tetraethylenepentamine and ethylenediamine (Example 6), lysine diisocyanate with triethylenetetramine and lysine (Example 7), lysine diisocyanate with triethylenetetramine (Example 8). Figure 15 In it, i - l are respectively diphenylmethane diisocyanate with tetraethylenepentamine and butanediamine (Example 9), diphenylmethane diisocyanate with triethylenetetramine and butanediamine (Example 10), dicyclohexylmethane diisocyanate with triethylenetetramine and hexanediamine (Example 11), dicyclohexylmethane diisocyanate with diethylenetriamine and hexanediamine (Example 12).

[0164] The specific test method is as follows:

[0165] The dialysis bag method was used to simulate the release process of hexaconazole from polyurea microcapsules. The slow release rate of hexaconazole polyurea microcapsules in water was observed. To study its release behavior, methanol was selected as the release medium. The specific method was as follows: 0.01 g of dry hexaconazole polyurea microcapsules were accurately weighed and dispersed in 3 mL of methanol. The above system was encapsulated in a dialysis bag with a molecular weight cut-off of 2000. Then the dialysis bag was suspended in a container containing 197 mL of the release medium. After sealing the container, it was placed in a constant temperature shaker at a temperature of 25 °C and a speed of 100 rpm. At fixed intervals, 3 mL of dialysis fluid was taken from the beaker and an equal volume of the release medium was replenished to keep the total volume of the system at 200 mL unchanged. The absorbance of the dialysis fluid was measured continuously three times at a wavelength of 230 nm using an ultraviolet spectrophotometer, and the average value was taken. The concentration of hexaconazole was calculated from the hexaconazole calibration curve, and the cumulative release amount of hexaconazole was calculated according to the formula. The cumulative release curve of hexaconazole was obtained by plotting the cumulative release amount against the release time.

[0166] It can be seen from Figures 13 to 15 that hexaconazole polyurea microcapsules with different chain structure designs have different slow release rates. The crosslinking degree, chain segment flexibility, and presence or absence of side chains in the polyurea microcapsules will all affect the slow release effect of hexaconazole. As the crosslinking degree increases, the swellability of the microcapsules decreases, resulting in a weakened penetration and diffusion ability of hexaconazole, and a decrease in the slow release rate and cumulative release amount. As the chain segment flexibility increases, the crosslinking degree decreases, and the side chain content increases, the movement ability of the polyurea chain segments is enhanced, the space between the chain segments and the swellability increase, resulting in an enhanced penetration and diffusion ability of hexaconazole, and an increase in the slow release rate and cumulative release amount.

[0167] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing hexaconazole polyurea microcapsules with a controllable slow-release rate based on chain structure design, comprising the following steps: Mix hexaconazole, core solvent and polyisocyanate to obtain an oil phase; Mix emulsifier and water to obtain an aqueous phase; Add the oil phase to the aqueous phase and shear-mix to obtain an emulsion; Mix polyamine with the emulsion and carry out an interfacial polymerization reaction to obtain hexaconazole polyurea microcapsules; By mass percentage, the preparation raw materials used in this method include: The polyamine is triethylenetetramine and lysine; the molar ratio of triethylenetetramine to lysine is 1:

1.

2. The method according to claim 1, wherein The polyisocyanate includes one or more of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate and lysine diisocyanate; The core solvent is one or more of ketone solvents, alcohol solvents, solvent oils, ester solvents, substituted alkane solvents and alkane solvents; The emulsifier includes one or more of agricultural emulsion series emulsifiers, NP series emulsifiers, AEO series emulsifiers, Tween series emulsifiers and EL series emulsifiers.

3. The method according to claim 1, wherein After the interfacial polymerization reaction, it further includes adding a dispersant and / or a stabilizer to the obtained interfacial polymerization reaction solution to obtain hexaconazole polyurea microcapsules; The dispersant includes one or more of sodium polycarboxylate, sodium dodecylbenzenesulfonate and polyphosphates; The stabilizer is one or more of polyethylene oxide ether, sodium alkylbenzenesulfonate, calcium carbonate and ethylene glycol.

4. The method according to claim 3, wherein The mass ratio of the dispersant to hexaconazole is 0.5-4:1-35; The mass ratio of the stabilizer to hexaconazole is 0.5-3:1-35.

5. The method according to claim 1, wherein The rate of the shear mixing is 10000-15000 r / min and the time is 10-15 min.

6. The method according to claim 1, characterized in that, The temperature of the interfacial polymerization reaction is 30-60 °C and the time is 0.5-2 h.

7. The hexaconazole polyurea microcapsules prepared by the method according to any one of claims 1-6, comprising a hexaconazole core and a polyurea shell.

8. Use of the hexaconazole polyurea microcapsules according to claim 7 in the preparation of drugs for preventing and treating grape powdery mildew, black rot, apple scab, powdery mildew, wheat sharp eyespot.

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