Thermostable insecticide microcapsule as well as preparation method and application thereof
By preparing heat-stable insecticide microcapsules, the problem of low thermal stability in existing insecticide microcapsules in high temperature environments is solved, and long-term termite protection and maintenance costs are achieved.
Patent Information
- Application Number
- CN202510320859.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-18
- Publication Date
- 2025-06-06
AI Technical Summary
The existing insecticide microcapsules have low thermal stability in high temperature environments, resulting in inactivation of insecticides, reducing the anti-antit effect and increasing maintenance costs.
Using a preparation method, by dissolving the emulsifier in water, prepoly isocyanate and polytetrahydrofuran, mixing insecticides and polylactic acid, an oil-in-water emulsion is formed, and the organic solvent is volatile by heating, and the small molecule prepolymer is polymerized to form a heat-stable insecticide microcapsule.
Improves the thermal stability of insecticide microcapsules, extends their service life, provides long-term termite protection, and reduces maintenance costs.
Smart Images
Figure CN120092775A_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the technical field of pesticides, and in particular relates to a heat-stable pesticide microcapsule and a preparation method and application thereof. Background Art
[0002] The traditional methods of using pesticides such as imidacloprid, clothianidin and acetamiprid are spraying, dusting and irrigation, but these methods of using pesticides can easily lead to excessive use of pesticides. More seriously, they may flow into the surface through surface water, runoff and wetlands, causing water environment pollution. Therefore, a new technology with a slow-release effect is needed to overcome the problems caused by traditional methods of using pesticides.
[0003] At present, microencapsulation technology mainly adopts interfacial polymerization, condensed phase separation, in situ polymerization or solvent volatilization to completely encapsulate a certain target object (core or inner phase) with a continuous film (wall or outer phase) of various natural or synthetic polymer compounds, and maintain the original chemical properties of the target object. Then, through certain external stimulation or sustained release, the function of the target object is gradually presented externally again, or the shielding effect of the capsule wall is relied on to protect the core material. Insecticide microcapsules prepared with insecticides such as imidacloprid, clothianidin and acetamiprid as the core material of microcapsules can reduce some problems caused by excessive use of insecticides by utilizing the sustained release effect of microcapsules.
[0004] There are many ways to lay cables, including overhead laying, wall laying, tunnel laying, pipeline laying, direct burial laying, etc. Except for overhead cables, cables laid in other ways will be attacked by pests such as termites, especially direct burial. Laying cables underground is prone to termite erosion. Burying insecticide microcapsules around directly buried cables can reduce termite erosion. However, when the voltage and current carried by the cable are high, a large amount of heat is generated during the operation of the cable, resulting in a continuous heating state. At present, the operating temperature of cross-linked polyethylene cables can usually reach 90°C. In addition, when the cable is overloaded or short-circuited, the temperature may even exceed 200°C. High temperature will affect the stability of the insecticide microcapsules and reduce the anti-termite effect of the insecticide microcapsules. In order to maintain the anti-termite effect, the insecticide microcapsules need to be re-buried, which leads to increased costs. The above situation can be avoided by improving the thermal stability of the insecticide microcapsules. Summary of the invention
[0005] In view of this, the present application provides a thermally stable insecticide microcapsule and a preparation method and application thereof, which are used to solve the technical problem that the existing insecticide microcapsules have low thermal stability.
[0006] The first aspect of the present application is a method for preparing a heat-stable insecticide microcapsule, the preparation method comprising the following steps:
[0007] The step of preparing the aqueous phase is to dissolve the emulsifier in water to obtain the aqueous phase;
[0008] The step of preparing the oil phase is to prepolymerize isocyanate, polytetrahydrofuran and a catalyst to obtain a small molecule prepolymer;
[0009] Dissolving the pesticide and polylactic acid in an organic solvent to obtain a polylactic acid / pesticide solution;
[0010] mixing the small molecule prepolymer and the polylactic acid / insecticide solution to obtain an oil phase;
[0011] The step of preparing the oil-in-water emulsion is to add the oil phase into the water phase for emulsification to obtain the oil-in-water emulsion;
[0012] The steps of preparing microcapsules are as follows: heating to decompose the organic solvent in the water-in-oil emulsion, polymerizing the small molecule prepolymer, and obtaining the heat-stable insecticide microcapsules.
[0013] Preferably, in the step of preparing the aqueous phase, the emulsifier is selected from at least one of sodium oleate, sodium stearate, polyoxyethylene fatty acid ester and polysorbate.
[0014] Preferably, in the step of preparing the aqueous phase, the mass ratio of the water to the pesticide is 25-100:1.
[0015] The values include the minimum and maximum values of the range, and every value between the minimum and maximum values, specifically including but not limited to the following point values: 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 55:1, 60:1, 65:1, 70:1, 75:1, 80:1, 85:1, 90:1, 95:1, 100:1.
[0016] Preferably, in the step of preparing the oil phase, the average molecular weight of the polytetrahydrofuran is 600-3000.
[0017] For example, the average molecular weight of polytetrahydrofuran can be 600, 800, 1000, 1500, 2000, 2500, or 3000.
[0019] Preferably, in the step of preparing the oil phase, the isocyanate is selected from at least one of naphthalene diisocyanate, dicyclohexylmethane diisocyanate, norbornane diisocyanate and hexamethylene diisocyanate;
[0020] The catalyst is selected from at least one of dibutyltin dilaurate, stannous octoate, and triethylenediamine;
[0021] The insecticide is selected from at least one of imidacloprid, clothianidin and acetamiprid;
[0022] The organic solvent is selected from dichloromethane.
[0023] Preferably, in the step of preparing the oil phase, the molar ratio of the isocyanate to the polytetrahydrofuran is 1 to 6:1;
[0024] The mass ratio of the insecticide to the polylactic acid is 5-20:1.
[0025] The values include the minimum and maximum values of the range, and every value between the minimum and maximum values, specifically including but not limited to the following point values: 1:1, 1.25:1, 1.3:1, 1.35:1, 2:1, 2.45:1, 2.5:1, 2.55:1, 3.6:1, 3.65:1, 4.7:1, 4.75:1, 4.:1, 5:1, 6:1.
[0026] Preferably, in the step of preparing the oil-in-water emulsion, the mass ratio of the emulsifier, the isocyanate and the pesticide is 0.2~0.3:2~3:1.
[0027] The values include the minimum and maximum values of the range, and every value between the minimum and maximum values, including but not limited to the following point values: 0.2:2:1, 0.2:2.1:1, 0.2:2.2:1, 0.2:2.3:1, 0.2:2.4:1, 0.2:2.5:1, 0.2:2.6:1, 0.2:2.7:1, 0.2:2.8:1, 0.2:2.9:1, 0.2:3:1, 0.25:2:1, 0.25:2.1:1, 0.25:2.2:1, 0. : 1, 0.25:2.3:1, 0.25:2.4:1, 0.25:2.5:1, 0.25:2.6:1, 0.25:2.7:1, 0.25:2.8:1, 0.25:2.9:1, 0.25:3:1, 0.3:2:1, 0.3:2.1:1, 0.3:2.2:1, 0.3:2.3:1, 0.3:2.4:1, 0.3:2.5:1, 0.3:2.6:1, 0.3:2.7:1, 0.3:2.8:1, 0.3:2.9:1, 0.3:3:1.
[0028] Preferably, in the step of preparing the oil-in-water emulsion, the stirring speed is 800 rpm to 3000 rpm, and the stirring time is 10 min to 20 min.
[0029] The values include the minimum and maximum values of the range, and every value between the minimum and maximum values. The speed values specifically include but are not limited to the following point values: 800rpm, 900rpm, 1000rpm, 1100rpm, 1200rpm, 1300rpm, 1400rpm, 1500rpm, 1600rpm, 1700rpm, 1800rpm, 1900rpm, 2000rpm, 2100rpm, 2200rpm, 2300rpm, 2400rpm, 2500rpm, 2600rpm, 2700rpm, 2800rpm, 2900rpm, 3000rpm; the time values specifically include but are not limited to the following point values: 10min, 11min, 12min, 13min, 14min, 15min, 16min, 17min, 18min, 19min, 20min.
[0030] Preferably, in the step of preparing the microcapsules, the heating temperature is 60° C. to 80° C. and the heating time is 2 h to 8 h.
[0031] Among them, the values include the minimum and maximum values of the range, and every value between the minimum and maximum values. The temperature values specifically include but are not limited to: 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃, 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃, 80℃. The time values specifically include but are not limited to: 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h.
[0032] Preferably, in the step of preparing microcapsules, after heating to release the organic solvent in the oil-in-water emulsion and polymerize the small molecule prepolymer, the steps of washing with deionized water for 3 to 5 times, filtering, drying, etc. are also included to obtain heat-stable insecticide microcapsules.
[0033] The second aspect of the present application provides a heat-stable insecticide microcapsule, which is prepared by the preparation method described in the first aspect.
[0034] The third aspect of the present application provides the application of the heat-stable insecticide microcapsules described in the second aspect of the present application in the field of cable ant prevention.
[0035] Compared with the prior art, the heat-stable insecticide microcapsule provided in the present application has at least the following beneficial effects.
[0036] 1. The outer layer of the heat-stable insecticide microcapsule provided in the present application is a polyurea shell layer, and the inner layer is polylactic acid.
[0037] It has better stability when facing harsh environment such as temperature, and the coated insecticides such as imidacloprid are not easily degraded and inactivated, which can provide long-term protection against termites.
[0038] 2. The outer layer of the heat-stable insecticide microcapsule provided in the present application is a polyurea shell layer, and the inner layer is polylactic acid.
[0039] It can provide good coating effect, and has a high coating rate for insecticides such as imidacloprid.
[0040] 3. The heat-stable insecticide microcapsules provided in this application are widely used. In addition to being used in the field of cable ant prevention, they can also be used in special high-temperature environments such as greenhouses, chemical plants and steel plants to provide long-term protection. BRIEF DESCRIPTION OF THE DRAWINGS
[0041] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0042] Figure 1 This is a scanning electron microscope observation image of the insecticide microcapsule provided in Example 1 of the present application;
[0043] Figure 2 This is a scanning electron microscope observation image of the insecticide microcapsule provided in Example 2 of the present application;
[0044] Figure 3 This is a scanning electron microscope observation image of the insecticide microcapsule provided in Example 3 of the present application;
[0045] Figure 4 This is a scanning electron microscope observation image of the insecticide microcapsule provided in Comparative Example 1 of the present application;
[0046] Figure 5 A scanning electron microscope observation image of the insecticide microcapsule provided in Comparative Example 2 of the present application;
[0047] Figure 6 Infrared test images of the insecticide microcapsules provided in Examples 1-3 and Comparative Examples 1-2 of the present application;
[0048] Figure 7 This is a thermogravimetric test diagram of the insecticide microcapsules provided in Examples 1-3 and Comparative Examples 1-2 of the present application. DETAILED DESCRIPTION
[0049] The present application provides a thermally stable insecticide microcapsule and a preparation method and application thereof, which are used to solve the technical problem that the thermal stability of existing insecticide microcapsules is not high.
[0050] The technical solution of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.
[0051] Example 1
[0052] Example 1 of the present application provides a method for preparing heat-stable pesticide microcapsules, which includes the steps of preparing an aqueous phase, preparing an oil phase, preparing an oil-in-water emulsion, and preparing microcapsules.
[0053] The steps of preparing the water phase include: taking 5 g of emulsifier polysorbate, dissolving it in 250 mL of deionized water, and preparing a water phase component.
[0054] The steps of preparing the oil phase include:
[0055] 16.80 g of hexamethylene diisocyanate and 12.0 g of polytetrahydrofuran (molar ratio of about 5:1) were reacted at 60°C for 2 hours under the catalysis of 2.3 g of dibutyltin dilaurate to generate a small molecule prepolymer;
[0056] 10.0 g of the insecticide imidacloprid and 0.5 g of polylactic acid were dissolved in 20 mL of organic solvent dichloromethane and stirred until completely dissolved to obtain a polylactic acid / insecticide solution. Subsequently, the small molecule prepolymer was mixed with the polylactic acid / insecticide solution and homogenized for 10 minutes to obtain an oil phase component.
[0057] The steps of preparing the oil-in-water emulsion include: adding the oil phase component to the water phase component, stirring at a high speed of 1000 rpm again, and ultrasonic emulsification to ensure that the inner layer material is not prematurely wrapped or agglomerated by the outer layer, so as to obtain a uniform oil-in-water emulsion.
[0058] The steps of preparing microcapsules include: transferring the oil-in-water emulsion into a three-necked flask, stirring at 800 rpm for 3 hours at 70°C to volatilize the organic solvent dichloromethane (polylactic acid forms an inner layer), and polymerizing the small prepolymer with water to form a polyurea outer layer, thereby obtaining a suspension containing heat-stable insecticide microcapsules; then filtering, washing and drying to obtain the heat-stable insecticide microcapsules.
[0059] Example 2
[0060] Example 2 of the present application provides a method for preparing heat-stable pesticide microcapsules. The difference between the preparation method and Example 1 is that the amount of raw materials added is adjusted; the preparation method includes the steps of preparing an aqueous phase, preparing an oil phase, preparing an oil-in-water emulsion, and preparing microcapsules.
[0061] The step of preparing the water phase includes: taking 10 g of emulsifier polysorbate, dissolving it in 1000 mL of deionized water, and preparing a water phase component.
[0062] The steps of preparing the oil phase include:
[0063] 16.80 g of hexamethylene diisocyanate and 12.0 g of polytetrahydrofuran (molar ratio of about 5:1) were reacted at 60°C for 2 hours under the catalysis of 2.3 g of dibutyltin dilaurate to generate a small molecule prepolymer;
[0064] 10.0 g of the insecticide imidacloprid and 0.5 g of polylactic acid were dissolved in 20 mL of organic solvent dichloromethane and stirred until completely dissolved to obtain a polylactic acid / insecticide solution. Subsequently, the small molecule prepolymer was mixed with the polylactic acid / insecticide solution and homogenized for 10 minutes to obtain an oil phase component.
[0065] The steps of preparing the oil-in-water emulsion include: adding the oil phase component to the water phase component, stirring at a high speed of 1000 rpm again, and ultrasonic emulsification to ensure that the inner layer material is not prematurely wrapped or agglomerated by the outer layer, so as to obtain a uniform oil-in-water emulsion.
[0066] The steps of preparing microcapsules include: transferring the oil-in-water emulsion into a three-necked flask, stirring at 800 rpm for 3 hours at 70°C to volatilize the organic solvent dichloromethane (polylactic acid forms an inner layer), and polymerizing the small prepolymer with water to form a polyurea outer layer, thereby obtaining a suspension containing heat-stable insecticide microcapsules; then filtering, washing and drying to obtain the heat-stable insecticide microcapsules.
[0067] Example 3
[0068] Example 3 of the present application provides a method for preparing heat-stable pesticide microcapsules. The difference between the preparation method and Example 1 is that the amount of raw materials added and the process conditions are adjusted; the method includes the steps of preparing an aqueous phase, preparing an oil phase, preparing an oil-in-water emulsion, and preparing microcapsules.
[0069] The step of preparing the water phase includes: taking 10 g of emulsifier polysorbate, dissolving it in 1000 mL of deionized water, and preparing a water phase component.
[0070] The steps of preparing the oil phase include:
[0071] 16.80 g of hexamethylene diisocyanate and 12.0 g of polytetrahydrofuran (molar ratio of about 5:1) were reacted at 60°C for 2 hours under the catalysis of 2.3 g of dibutyltin dilaurate to generate a small molecule prepolymer;
[0072] 10.0 g of the insecticide imidacloprid and 1.5 g of polylactic acid were dissolved in 20 mL of organic solvent dichloromethane and stirred until completely dissolved to obtain a polylactic acid / insecticide solution. Subsequently, the small molecule prepolymer was mixed with the polylactic acid / insecticide solution and homogenized for 10 minutes to obtain an oil phase component.
[0073] The steps of preparing the oil-in-water emulsion include: adding the oil phase component to the water phase component, stirring at a high speed of 1000 rpm again, and ultrasonic emulsification to ensure that the inner layer material is not prematurely wrapped or agglomerated by the outer layer, so as to obtain a uniform oil-in-water emulsion.
[0074] The steps of preparing microcapsules include: transferring the oil-in-water emulsion into a three-necked flask, stirring at 300 rpm for 3 hours at 70°C to volatilize the organic solvent dichloromethane (polylactic acid forms an inner layer), and polymerizing the small prepolymer with water to form a polyurea outer layer, thereby obtaining a suspension containing heat-stable insecticide microcapsules; then filtering, washing and drying to obtain the heat-stable insecticide microcapsules.
[0075] Comparative Example 1
[0076] Comparative Example 1 of the present application provides a method for preparing insecticide microcapsules, including the steps of preparing an aqueous phase, preparing an oil phase, preparing an oil-in-water emulsion, and preparing microcapsules.
[0077] The steps of preparing the water phase include: taking 5 g of emulsifier polyvinyl alcohol, dissolving it in 250 mL of deionized water, and preparing a water phase component.
[0078] The step of preparing the oil phase includes: 10.0g of the insecticide imidacloprid, 22.2g of isophorone diisocyanate, 10.0g of diethylenetriamine, and 2.3g of dibutyltin dilaurate are subjected to high-speed mechanical stirring and shearing emulsification reaction at a speed of 1000rpm for one hour to obtain the oil phase component.
[0079] The steps of preparing the oil-in-water emulsion include: adding the oil phase component to the water phase component, and again performing high-speed mechanical stirring and shearing emulsification at a rotation speed of 1000 rpm to obtain a uniform oil-in-water emulsion.
[0080] The steps of preparing microcapsules include: transferring the oil-in-water emulsion into a three-necked flask, stirring at 800 rpm for 3 hours at 70°C to obtain a suspension containing insecticide microcapsules; then filtering, washing and drying to obtain insecticide microcapsules.
[0081] Comparative Example 2
[0082] Comparative Example 2 of the present application provides a method for preparing insecticide microcapsules, including the steps of preparing an aqueous phase, preparing an oil phase, preparing an oil-in-water emulsion, and preparing microcapsules.
[0083] The steps of preparing the water phase include: taking 5 g of emulsifier polysorbate, dissolving it in 250 mL of deionized water, and preparing a water phase component.
[0084] The steps of preparing the oil phase include: mixing 10.0g of the insecticide imidacloprid, 0.5g of polylactic acid, 16.80g of hexamethylene diisocyanate, 12.0g of polytetrahydrofuran (molar ratio of about 5:1) and 2.3g of dibutyltin dilaurate, stirring at a high speed of 1000rpm for emulsification reaction for 1 hour to obtain an oil phase component of a mixture of an oil phase small molecule prepolymer and imidacloprid.
[0085] The steps of preparing the oil-in-water emulsion include: adding the oil phase component to the water phase component, stirring at a high speed of 1000 rpm again, and ultrasonic emulsification to obtain a uniform oil-in-water emulsion.
[0086] The steps of preparing microcapsules include: transferring the oil-in-water emulsion into a three-necked flask, stirring at 800 rpm for 3 hours at 70°C to obtain a suspension containing insecticide microcapsules; then filtering, washing and drying to obtain insecticide microcapsules.
[0087] Comparative Example 3
[0088] Comparative Example 3 of the present application provides a method for preparing insecticide microcapsules, including the steps of preparing an aqueous phase, preparing an oil phase, preparing an oil-in-water emulsion, and preparing microcapsules.
[0089] The steps of preparing the water phase include: taking 5 g of emulsifier polyvinyl alcohol, dissolving it in 250 mL of deionized water, and preparing a water phase component.
[0090] The step of preparing the oil phase includes: 50.0g of the insecticide imidacloprid, 22.2g of isophorone diisocyanate, 10.0g of diethylenetriamine, and 2.3g of dibutyltin dilaurate are subjected to high-speed mechanical stirring and shearing emulsification reaction at a speed of 1000rpm for one hour to obtain the oil phase component.
[0091] The steps of preparing the oil-in-water emulsion include: adding the oil phase component to the water phase component, and again performing high-speed mechanical stirring and shearing emulsification at a rotation speed of 1000 rpm to obtain a uniform oil-in-water emulsion.
[0092] The steps of preparing microcapsules include: transferring the oil-in-water emulsion into a three-necked flask, stirring at 800 rpm for 3 hours at 70°C to obtain a suspension containing insecticide microcapsules; then filtering, washing and drying to obtain insecticide microcapsules.
[0093] Experimental Example 1
[0094] Experimental Example 1 of the present application analyzes the structure and performance of the insecticide microcapsules provided in Examples 1-3 and Comparative Example 1.
[0095] The electron microscope structure analysis results of the insecticide microcapsules provided in Examples 1-3 and Comparative Examples 1-2 are shown in FIG. Figure 1-5 shown; from Figure 1-3 It can be seen that the insecticide microcapsules provided in Examples 1-3 of the present application use an emulsifier and deionized water as the aqueous phase, pesticides, polylactic acid and prepolymer as the oil phase, the prepolymer is obtained by reacting hexamethylene diisocyanate with polytetrahydrofuran, and the oil phase and the aqueous phase are mixed and emulsified to obtain an oil-in-water emulsion, wherein the prepolymer reacts with water at the oil-water interface to generate urea groups (-NH-CO-NH-), which promote the chain growth of polyurea and make the microcapsule shell more stable. In the process of preparing the oil-in-water emulsion, the emulsifier, isocyanate, and insecticide are also controlled. and polytetrahydrofuran, so that the components are coordinated, the dense structure of the insecticide microcapsule wall is improved, and the coverage rate is relatively high; at the same time, since the outer layer of the insecticide microcapsule provided by Examples 1-3 of the present application is a polyurea shell layer, and the inner layer is polylactic acid, polylactic acid is a biodegradable material, it can not only provide a good coating effect, but also enhance the biocompatibility of the insecticide microcapsule, and protect insecticides such as imidacloprid from external environmental factors (such as light, humidity, temperature, etc.), prolong the action time of insecticides such as imidacloprid, and reduce the abuse of insecticides such as imidacloprid.
[0096] The infrared spectra of the insecticide microcapsules and imidacloprid provided in Examples 1-3 and Comparative Examples 1-2 tested using a Thermal Scientific Fourier transform infrared spectrometer are shown in FIG. Figure 6 As shown, from Figure 6 It can be seen that the C=O vibration absorption peak of polyurea appears at 1650cm -1 The stretching vibration absorption peak of CO bond appears at 1302 cm -1 , 1230cm -1 The infrared characteristic peak of COC appeared at 3350cm, proving that isocyanate, diol and water polymerized to form polyurea, confirming the structural characteristics of the microcapsule. -1 The NH bond stretching vibration of polyurea is at 3650-3250cm -1There is a relatively broad absorption peak at the position, which indicates that the synthetic insecticide microcapsules of Examples 1-3 and Comparative Examples 1-2 are coated with the insecticide imidacloprid.
[0097] At the same time, since the thermal stability of the insecticide microcapsules has a great influence on the insecticide microcapsules, the present application also conducts thermal stability analysis on the insecticide microcapsules provided in Examples 1-3 and Comparative Examples 1-2 and imidacloprid. The analysis results are as follows: Figure 7 As shown in Table 1, Figure 7 Table 1 is the results of the thermal aging test at 200℃ / 90℃ / 60℃ for different time periods. Figure 7 As can be seen from Table 1, the insecticide imidacloprid without microcapsule coating has poor thermal stability and is degraded and inactivated by about 40% at 200°C / 48h or 90°C / 28d, while the insecticide microcapsules provided by Examples 1-3 and Comparative Examples 1-2 have improved thermal stability and are not easily degraded and inactivated; further comparison shows that the early thermal weight loss is caused by water loss. Compared with the insecticide microcapsules provided by Comparative Documents 1-2, the degradation rate of the insecticide microcapsules provided by Examples 1-3 is much slower than that of the Comparative Example and imidacloprid, and the thermal stability is better, which shows that Examples 1-3 The provided insecticide microcapsules have a polyurea shell layer as an outer layer and a polylactic acid as an inner layer, so that when the temperature and other environmental conditions become harsh, the insecticide microcapsules can better alleviate the impact of external conditions on the internal insecticides, thereby extending their service life. When used for cable anti-termite, when the cable is working in a heating state, the insecticide microcapsules provided in Examples 1-3 have good thermal stability and can provide a long-term anti-termite erosion effect; and due to good high temperature resistance, in addition to being used for cable anti-termite, they have broad application prospects in special high temperature environments such as greenhouses, chemical plants and steel plants.
[0098] Table 1: Thermal aging test results
[0099]
[0100] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.
Claims
1. A method for preparing heat-stable insecticide microcapsules, characterized in that: The following steps are involved: The step of preparing the aqueous phase is to dissolve the emulsifier in water to obtain the aqueous phase; The step of preparing the oil phase is to prepolymerize isocyanate, polytetrahydrofuran and a catalyst to obtain a small molecule prepolymer; Dissolving the pesticide and polylactic acid in an organic solvent to obtain a polylactic acid / pesticide solution; mixing the small molecule prepolymer and the polylactic acid / insecticide solution to obtain an oil phase; The step of preparing the oil-in-water emulsion is to add the oil phase into the water phase for emulsification to obtain the oil-in-water emulsion; The steps of preparing microcapsules are as follows: heating to decompose the organic solvent in the water-in-oil emulsion, polymerizing the small molecule prepolymer, and obtaining the heat-stable insecticide microcapsules.
2. The method for preparing a heat-stable insecticide microcapsule according to claim 1, characterized in that: In the step of preparing the aqueous phase, the emulsifier is selected from at least one of sodium oleate, sodium stearate, polyoxyethylene fatty acid ester and polysorbate.
3. The method for preparing a heat-stable insecticide microcapsule according to claim 1, characterized in that: In the step of preparing the aqueous phase, the mass ratio of the water to the pesticide is 25-100:
1.
4. The method for preparing a heat-stable insecticide microcapsule according to claim 1, characterized in that: In the step of preparing the oil phase, the average molecular weight of the polytetrahydrofuran is 600-3000.
5. The method for preparing a heat-stable insecticide microcapsule according to claim 1, characterized in that: In the step of preparing the oil phase, the isocyanate is selected from at least one of naphthalene diisocyanate, dicyclohexylmethane diisocyanate, norbornane diisocyanate and hexamethylene diisocyanate; The catalyst is selected from at least one of dibutyltin dilaurate, stannous octoate, and triethylenediamine; The insecticide is selected from at least one of imidacloprid, clothianidin and acetamiprid; The organic solvent is selected from dichloromethane.
6. The method for preparing a heat-stable insecticide microcapsule according to claim 1, characterized in that: In the step of preparing the oil phase, the molar ratio of the isocyanate to the polytetrahydrofuran is 1 to 6:1; The mass ratio of the insecticide to the polylactic acid is 5-20:
1.
7. The method for preparing a heat-stable insecticide microcapsule according to claim 1, characterized in that: In the step of preparing the oil-in-water emulsion, the mass ratio of the emulsifier, the isocyanate and the pesticide is 0.2-0.3:2-3:
1.
8. The method for preparing a heat-stable insecticide microcapsule according to claim 1, characterized in that: In the step of preparing microcapsules, the heating temperature is 60°C to 80°C and the heating time is 2h to 8h.
9. A heat-stable insecticide microcapsule, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 8.
10. Use of the heat-stable insecticide microcapsule according to claim 9 in the field of cable anti-ant.