Pesticide sustained-release microcapsule as well as preparation method and application thereof

Abstract

The invention relates to the technical field of microcapsules, in particular to a pesticide sustained-release microcapsule as well as a preparation method and application thereof. The shell material of the pesticide sustained-release microcapsule provided by the invention is organic silicon modified polyurethane, and the core material of the pesticide sustained-release microcapsule is an original pesticide; wherein the organic silicon modified polyurethane is obtained by reacting isocyanate, organic silicon dihydric alcohol and degradable dihydric alcohol. The low-polarity and low-surface-energy organic silicon is introduced into the shell material of the pesticide sustained-release microcapsule, so that the contact angle of the microcapsule emulsion is reduced, and the microcapsule emulsion is easier to wet and spread on crops; the degradable dihydric alcohol is introduced, so that the microcapsule is degraded and broken for a long time, the internally wrapped pesticide is fully released, and the release rate and the utilization rate of the pesticide are improved.

Description

Technical Field

[0001] The present application relates to the technical field of microcapsules, and in particular to a pesticide sustained-release microcapsule and a preparation method and application thereof. Background Art

[0002] Pesticide sustained-release formulation is a kind of preparation that can continuously release the active ingredients of pesticides over a certain period of time. It can prolong the action time of pesticides, improve the efficiency of pesticide use, reduce the amount of pesticides used and residues, and reduce the impact on the environment and human health.

[0003] Microencapsulation technology can be used to encapsulate solid or liquid pesticides to prepare pesticide formulations with sustained release function. This technology forms a layer of tiny capsules on the surface of the pesticide, encapsulating the pesticide in it, thereby achieving slow release of the pesticide.

[0004] Common methods for preparing pesticide microcapsules are mainly divided into physical methods and chemical methods. Among them, the physical method is mainly the solvent evaporation method, which requires the use of more organic solvents and has a short time limit. The chemical method can be divided into in-situ polymerization and interfacial polymerization. These two methods prepare high molecular polymers as shell materials to wrap the internal pesticide raw materials. For example, patent CN113040160B discloses a pesticide microcapsule suspension and its preparation method, which uses polyisocyanate prepolymer as a component of the oil phase, emulsifies with the water phase, and then crosslinks and solidifies to form polyurethane microcapsules.

[0005] However, the sustained-release rate of existing pesticide microcapsules is difficult to control, the outer shell materials are mostly non-degradable high-molecular polymers such as polyurethane and melamine resin, the internal core material is difficult to release completely, and it causes plastic pollution to the environment, limiting its application in agriculture. Summary of the invention

[0006] The embodiment of the present application provides a pesticide sustained-release microcapsule to solve the problem in the related art that the outer shell material of the existing pesticide microcapsule is non-degradable and causes environmental pollution.

[0007] In a first aspect, an embodiment of the present application provides a pesticide sustained-release microcapsule, wherein the shell material of the microcapsule is silicone-modified polyurethane, and the core material is the pesticide technical; wherein the silicone-modified polyurethane is obtained by reacting isocyanate, silicone diol and degradable diol.

[0008] In some embodiments, the pesticide sustained-release microcapsules include the following raw materials, measured by mass: 10-50 parts of isocyanate, 1-10 parts of silicone diol, 1-10 parts of degradable diol, 0.05-2 parts of catalyst, 10-100 parts of pesticide technical, 0-50 parts of organic additives, 0.5-5 parts of surfactants, 1-5 parts of diamines, and 1-20 parts of triamines.

[0009] In some embodiments, the isocyanate is one or a mixture of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), and lysine diisocyanate (LDI).

[0010] In some embodiments, the organosilicon diol is hydroxyl-terminated polydimethylsiloxane with a molecular weight of 1000-4000.

[0011] In some embodiments, the degradable diol is one or a mixture of polybutylene succinate diol (PBSD), polycaprolactone diol (PCL), polyester carbonate diol, and the molecular weight of the degradable diol is 1000-4000.

[0012] In some embodiments, the catalyst is one or a mixture of organic bismuth, organic zinc, zirconium isooctanoate, and organic tin.

[0013] In some embodiments, the pesticide technical is one or a mixture of acetochlor, butachlor, avermectin, and emamectin benzoate.

[0014] In some embodiments, the organic auxiliary agent is one or a mixture of ethyl acetate, butyl acetate, toluene, xylene, chloroform, and dichloromethane; the surfactant is one or a mixture of two of sodium dodecylbenzene sulfonate and sodium dodecyl sulfate.

[0015] In some embodiments, the diamine is one or a mixture of ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine; and the triamine is diethylenetriamine.

[0016] In a second aspect, the present application also provides a method for preparing the above-mentioned pesticide sustained-release microcapsules, comprising the following steps:

[0017] Step S101, isocyanate, organosilicon diol, degradable diol and catalyst are uniformly mixed, heated to 60-70° C., and stirred to obtain a prepolymer;

[0018] Step S102, the pesticide technical, organic additives and prepolymer are mixed to form an oil phase, and a surfactant is added to water, and the mixture is mixed evenly to form a water phase;

[0019] Step S103, adding the oil phase to the water phase, and emulsifying at room temperature for 10-20 minutes to obtain an oil-in-water emulsion;

[0020] Step S104, adding the aqueous solution of diamine and triamine dropwise into the oil-in-water emulsion, and heating to 70-90° C. after the addition is complete to perform interfacial polymerization reaction, so as to obtain a pesticide sustained-release microcapsule suspension.

[0021] The pesticide microcapsules prepared in the present application have good pesticide sustained-release performance, and the shell material is prepared by degradable diols, and the internal core material can be completely released through the slow decomposition and rupture of the shell material, which is more environmentally friendly and economical and efficient.

[0022] The beneficial effects of the technical solution provided by this application include:

[0023] 1. The pesticide sustained-release microcapsules of the present application introduce long-chain silicone into the shell material, so that the polymer network in the microcapsule shell material has larger pores, and the internal pesticide core material can be slowly released through the pores; in addition, due to the addition of emulsifiers, the contact angle of the microcapsule emulsion is reduced to 60°-80°, making it easier to wet and spread on crops;

[0024] 2. The pesticide sustained-release microcapsules of the present application introduce degradable diols into the shell material so that the microcapsule shell material can be slowly degraded and broken in a natural environment for several months, fully releasing the pesticides encapsulated inside, thereby improving the release rate and utilization rate of the pesticides;

[0025] 3. The preparation method of the present application has a simple process and mild conditions, and the pesticide microcapsules prepared by this method also have a good sustained-release effect, which to a certain extent prolongs the duration of the pesticide effect and reduces the amount of pesticide application, effectively solving the problems of high toxicity of traditional pesticide preparations, low pesticide utilization rate and easy loss to the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 This is a scanning electron microscope (SEM) image of the pesticide sustained-release microcapsule prepared in Example 1;

[0028] Figure 2 This is a graph showing the release rate of the pesticide sustained-release microcapsules prepared in Example 1 in a methanol-water solution;

[0029] Figure 3 The contact angles of the pesticide sustained-release microcapsule emulsion and the aqueous dispersion of the pesticide original drug prepared in Example 1 on the crops, respectively. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0031] The embodiment of the present application provides a pesticide sustained-release microcapsule, which can solve the problem in the prior art that the outer shell material of the pesticide microcapsule is non-degradable and causes environmental pollution.

[0032] The present invention provides a method for preparing a pesticide sustained-release microcapsule, comprising the following steps:

[0033] Step S101, by weight, 10-50 parts of isocyanate, 1-10 parts of organosilicon diol, 1-10 parts of degradable diol and 0.05-2 parts of catalyst are mixed uniformly, heated to 60-70° C., and stirred to obtain a prepolymer;

[0034] Step S102, by weight, 10-100 parts of pesticide technical, 0-50 parts of organic additives, and prepolymer are mixed as the oil phase, and 0.5-5 parts of surfactant are added to water, and the mixture is mixed evenly as the water phase;

[0035] Step S103, adding the oil phase to the water phase by weight, and emulsifying at room temperature for 10-20 minutes to obtain an oil-in-water emulsion;

[0036] Step S104, adding 1-5 parts of diamine and 1-20 parts of triamine aqueous solution dropwise into the oil-in-water emulsion by mass, heating to 70-90° C. after complete addition to perform interfacial polymerization reaction, and obtaining a pesticide sustained-release microcapsule suspension.

[0037] Embodiment 1:

[0038] (1) 20 g of isophorone diisocyanate, 1.0 g of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 2000, 1.0 g of polycaprolactone diol with a molecular weight of 1000, and 0.2 g of an organic tin catalyst were mixed uniformly, heated to 60° C., and stirred for reaction for 4 h to obtain a prepolymer;

[0039] (2) 10 g of avermectin, 1 g of butyl acetate, and 2 g of prepolymer were mixed as the oil phase, and then 1 g of sodium dodecylbenzene sulfonate was added to 50 g of water and mixed well as the water phase;

[0040] (3) adding the oil phase to the water phase, and emulsifying at room temperature at 4000 rpm in a disperser for 10 min to obtain an oil-in-water emulsion;

[0041] (4) 50 g of an aqueous solution containing 2 g of ethylenediamine and 10 g of diethylenetriamine was added dropwise to the oil-in-water emulsion. After the addition was complete, the mixture was heated to 90° C. for interfacial polymerization to obtain a pesticide sustained-release microcapsule suspension.

[0042] The scanning electron microscope image of the pesticide sustained-release microcapsules prepared in Example 1 is shown in Figure 1 , Figure 1 It can be seen that the particle size distribution of the prepared pesticide sustained-release microcapsules is about 2-10 μm, the particle size is small, and has good dispersion stability.

[0043] The release rate of the pesticide sustained-release microcapsules prepared in Example 1 in methanol-water solution is shown in FIG. Figure 2 ,from Figure 2 It can be seen that the original avermectin drug as the control group is completely released in a very short time (<20h), while the prepared pesticide sustained-release microcapsules can be slowly released within about 125h, proving that the prepared pesticide sustained-release microcapsules have obvious sustained-release properties.

[0044] The contact angles of the pesticide sustained-release microcapsule emulsion and the aqueous dispersion of the pesticide original drug prepared in Example 1 on the crops are shown in FIG. Figure 3 ,from Figure 3 It can be seen that the contact angle of the pesticide sustained-release microcapsule emulsion shown in the upper row is 80-60°, which is significantly smaller than the water dispersion of the original drug and has better spreading and wetting properties.

[0045] Comparative Example 1:

[0046] The difference between Comparative Example 1 and Example 1 is that polycaprolactone diol is not added during the preparation of the prepolymer; the rest is the same as Example 1.

[0047] The pesticide in the core material of the microcapsule obtained in Comparative Example 1 cannot be completely released.

[0048] Embodiment 2:

[0049] (1) 30 g of hexamethylene diisocyanate, 1.5 g of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 3000, 3.0 g of polyester carbonate diol with a molecular weight of 2000, and 0.5 g of an organic zinc catalyst were mixed uniformly, heated to 65° C., and stirred for reaction for 4 h to obtain a prepolymer;

[0050] (2) 20 g of butachlor, 3 g of chloroform, and 3.5 g of prepolymer were mixed as the oil phase, and then 1.5 g of sodium dodecyl sulfate was added to 50 g of water and mixed well as the water phase;

[0051] (3) adding the oil phase to the water phase, and emulsifying at room temperature at 4000 rpm in a disperser for 20 min to obtain an oil-in-water emulsion;

[0052] (4) 50 g of an aqueous solution containing 3 g of butanediamine and 15 g of diethylenetriamine was added dropwise to the oil-in-water emulsion. After the addition was complete, the mixture was heated to 80° C. for interfacial polymerization to obtain a pesticide sustained-release microcapsule suspension.

[0053] Embodiment 3:

[0054] (1) 30 g of diphenylmethane diisocyanate, 2.0 g of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 2000, 4.0 g of polybutylene succinate diol with a molecular weight of 3000, and 0.3 g of an organic tin catalyst were mixed uniformly, heated to 70° C., and stirred for reaction for 4 h to obtain a prepolymer;

[0055] (2) 25 g of emamectin benzoate, 3 g of dichloromethane, and 4 g of prepolymer were mixed as the oil phase, and then 2.5 g of sodium dodecylbenzene sulfonate was added to 70 g of water and mixed well as the water phase;

[0056] (3) adding the oil phase to the water phase, and emulsifying at room temperature at 4000 rpm in a disperser for 10 min to obtain an oil-in-water emulsion;

[0057] (4) 80 g of an aqueous solution containing 4 g of propylenediamine and 5 g of diethylenetriamine was added dropwise to the oil-in-water emulsion. After the addition was complete, the mixture was heated to 90° C. for interfacial polymerization to obtain a pesticide sustained-release microcapsule suspension.

[0058] Embodiment 4:

[0059] (1) 35 g of toluene diisocyanate, 3.0 g of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 4000, 5.0 g of polybutylene succinate diol with a molecular weight of 2000, and 0.8 g of zirconium isooctanoate were mixed uniformly, heated to 70° C., and stirred for reaction for 4 h to obtain a prepolymer;

[0060] (2) 25 g of acetochlor, 5 g of ethyl acetate, and 6 g of prepolymer were mixed as the oil phase, and then 2 g of sodium dodecylbenzene sulfonate was added to 60 g of water and mixed well as the water phase;

[0061] (3) adding the oil phase to the water phase, and emulsifying at room temperature at 4000 rpm in a disperser for 20 min to obtain an oil-in-water emulsion;

[0062] (4) 100 g of an aqueous solution containing 3 g of butanediamine and 15 g of diethylenetriamine was added dropwise to the oil-in-water emulsion. After the addition was complete, the mixture was heated to 85° C. for interfacial polymerization to obtain a pesticide sustained-release microcapsule suspension.

[0063] Embodiment 5:

[0064] (1) 40 g of lysine diisocyanate, 5.0 g of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 3000, 3.0 g of polycaprolactone diol with a molecular weight of 3000, and 1 g of an organic bismuth catalyst were mixed uniformly, heated to 60° C., and stirred for reaction for 4 h to obtain a prepolymer;

[0065] (2) 25 g of acetochlor, 1.5 g of xylene, and 3 g of prepolymer were mixed as the oil phase, and then 3 g of sodium lauryl sulfate was added to 100 g of water and mixed well to form the water phase;

[0066] (3) adding the oil phase to the water phase, and emulsifying at room temperature at 4000 rpm in a disperser for 20 min to obtain an oil-in-water emulsion;

[0067] (4) 100 g of an aqueous solution containing 3.5 g of hexamethylenediamine and 12 g of diethylenetriamine was added dropwise to the oil-in-water emulsion. After the addition was complete, the mixture was heated to 90° C. for interfacial polymerization to obtain a pesticide sustained-release microcapsule suspension.

[0068] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments / methods or examples. In addition, those skilled in the art may combine and combine the different embodiments / methods or examples described in this specification and the features of the different embodiments / methods or examples, unless they are contradictory.

[0069] It should be noted that, in the present application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements defined by the sentence "comprise one..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements. In the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically stipulated.

[0070] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A pesticide sustained-release microcapsule, characterized in that: The shell material of the microcapsule is organosilicon-modified polyurethane, and the core material is pesticide technical; wherein the organosilicon-modified polyurethane is obtained by reacting isocyanate, organosilicon diol and degradable diol.

2. The pesticide sustained-release microcapsule according to claim 1, characterized in that: The raw materials are as follows, calculated by weight: 10-50 parts of isocyanate, 1-10 parts of organosilicon diol, 1-10 parts of degradable diol, 0.05-2 parts of catalyst, 10-100 parts of pesticide technical, 0-50 parts of organic additive, 0.5-5 parts of surfactant, 1-5 parts of diamine and 1-20 parts of triamine.

3. The pesticide sustained-release microcapsule according to claim 2, characterized in that: The isocyanate is one or a mixture of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate.

4. The pesticide sustained-release microcapsule according to claim 2, characterized in that: The organosilicon diol is hydroxyl-terminated polydimethylsiloxane.

5. The pesticide sustained-release microcapsule according to claim 2, characterized in that: The degradable diol is one of polybutylene succinate diol, polycaprolactone diol and polyester carbonate diol or a mixture of several of them.

6. The pesticide sustained-release microcapsule according to claim 2, characterized in that: The catalyst is one or a mixture of organic bismuth, organic zinc, zirconium isooctanoate and organic tin.

7. The pesticide sustained-release microcapsule according to claim 2, characterized in that: The pesticide technical is one of acetochlor, butachlor, avermectin and emamectin benzoate or a mixture of several of them.

8. The pesticide sustained-release microcapsule according to claim 2, characterized in that: The organic auxiliary agent is one of ethyl acetate, butyl acetate, toluene, xylene, chloroform and dichloromethane or a mixture of several of them; the surfactant is one of sodium dodecylbenzene sulfonate and sodium dodecyl sulfate or a mixture of two of them.

9. The pesticide sustained-release microcapsule according to claim 2, characterized in that: The diamine is one of ethylenediamine, propylenediamine, butylenediamine and hexamethylenediamine or a mixture of several thereof; the triamine is diethylenetriamine.

10. The method for preparing the pesticide sustained-release microcapsules according to claim 2, characterized in that: The following steps are involved: S101, isocyanate, silicone diol, biodegradable diol and catalyst are uniformly mixed, heated to 60-70° C., and stirred to obtain a prepolymer; S102, mixing the pesticide technical, organic additives and prepolymer as the oil phase, adding the surfactant into water, and mixing them evenly as the water phase; S103, adding the oil phase to the water phase and emulsifying at room temperature to obtain an oil-in-water emulsion; S104, adding aqueous solutions of diamine and triamine dropwise into the oil-in-water emulsion, and heating to 70-90° C. after complete addition to carry out interfacial polymerization reaction, thereby obtaining a pesticide sustained-release microcapsule suspension.

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