A kind of pesticide slow-release granule and its preparation method and application

Abstract

The invention discloses a pesticide slow-release granule suitable for co-seeding of pesticides and plant seeds. The pesticide slow-release granule of the invention has a double coating layer, wherein the first coating layer has a pesticide active ingredient A as a core and a nano-calcium carbonate carrier material as a shell, and the fungicide active ingredient is first coated with nano-calcium carbonate by a physical adsorption method; the second coating layer is a mixture of the first coating layer and the pesticide active ingredient B as a core, and a material such as attapulgite as a shell. The slow-release granule of the invention has good slow-release performance, can stably release the active ingredient over a long period of time, prolong the efficacy period, reduce the operation of frequent application of pesticides, and thus improve the utilization rate of pesticides.

Description

Technical Field

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

[0002] There are many problems with traditional pesticide application methods, such as short duration of efficacy, low drug utilization, and greater negative impact on the environment. In order to solve these problems, sustained-release formulation technology has gradually gained attention. By encapsulating the active ingredients in appropriate carrier materials, the drug can be slowly released, thereby extending the duration of efficacy, reducing the frequency of application, and improving drug utilization.

[0003] As an inorganic material, nano calcium carbonate has the advantages of good biocompatibility, controllable release characteristics and low cost. In the field of pesticide loading, nano calcium carbonate as a carrier has received widespread attention. The calcium ion in it is an important element for plant growth and can promote crop growth. However, the nano calcium carbonate-pesticide delivery system is usually in the form of a water-insoluble powder, which brings many inconveniences in practical applications. Problems such as uneven distribution of pesticide active ingredient dosage, poor stability, and low pesticide utilization may occur. At the same time, although the nano calcium carbonate-pesticide delivery system can achieve slow release of active ingredients in the field, its initial release rate is unstable, which does not meet the actual needs of pest control, resulting in poor control effects. . Summary of the invention

[0004] In the prior art, the nano-calcium carbonate-pesticide delivery system is usually in the form of a water-insoluble powder, which may lead to uneven distribution of the dosage of the pesticide active ingredient, poor stability, low pesticide utilization rate, and slow release of the active ingredient during field application of the nano-calcium carbonate-pesticide delivery system, especially unstable initial release rate, and general control effect in actual application.

[0005] The applicant of the present invention first proposed a pesticide slow-release granule with a double-layer coating structure. The pesticide slow-release granule of the present invention can effectively prolong the efficacy period, improve the control effect of pesticides, and reduce environmental pollution.

[0006] Specifically, the pesticide slow-release granules of the present invention adopt the following technical scheme:

[0007] A pesticide slow-release granule, which has a double-coating core-shell structure, wherein the double coating is a first coating and a second coating, the first coating has a pesticide active ingredient A as a core and comprises nano-calcium carbonate as a carrier material to form a shell; the second coating is a mixture of the first coating and the pesticide active ingredient B as a core and comprises attapulgite as a carrier material to form a shell.

[0008] The present invention also provides a method for preparing the pesticide slow-release granules of the present invention, which comprises the following steps:

[0009] Step 1), dissolving the active ingredient A of the pesticide in an organic solvent to obtain a solution of the active ingredient A for later use;

[0010] Step 2), under stirring, adding the solution of the pesticide active ingredient A prepared in step 1) and the aqueous solution of the regulator to the calcium chloride aqueous solution, adding the sodium carbonate aqueous solution after the addition, stirring and reacting, and obtaining the first coating layer containing the active ingredient A as the core and the nano calcium carbonate carrier material as the shell after post-treatment;

[0011] Step 3), dissolve the binder and thickener in water for later use;

[0012] Step 4), add the first coating layer and the pesticide active ingredient B prepared in step 2) to the solution in step 3), stir evenly, then add the attapulgite, adsorb evenly and dry.

[0013] The present invention also provides application of the pesticide slow-release granules of the present invention in preventing and controlling crop diseases and insect pests.

[0014] The present invention also provides application of the pesticide slow-release granules obtained according to the preparation method of the present invention in preventing and controlling crop diseases and insect pests.

[0015] Beneficial effects of the present invention

[0016] 1. The pesticide sustained-release granules of the present invention combine nano-calcium carbonate with attapulgite carriers to prepare an attapulgite-nano-calcium carbonate-pesticide controlled-release system, which achieves the slow release of pesticides and improves the operability of pesticide application. The preparation process is simple, efficient, easy to industrialize, and has low material cost, and has good market promotion prospects.

[0017] 2. The pesticide slow-release granules of the present invention improve the stability and uniformity of the pesticide, reduce the breakage and pulverization of the granules during storage and transportation, effectively prolong the efficacy period, improve the control effect of the pesticide, and reduce environmental pollution.

[0018] 3. The pesticide slow-release granules of the present invention are suitable for the application method of pesticides and plant seeds at the same time, avoiding multiple sowing, application and other operations, and can effectively replace traditional seed dressing agents and soil treatment agents, reduce labor costs, and achieve the effect of disease prevention and control with one application of pesticides. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Photo of 0.15% attapulgite-nano calcium carbonate-pesticide slow-release granules sown with wheat seeds

[0020] Figure 2 Schematic diagram of the structure of attapulgite-nano calcium carbonate-pesticide slow-release granules

[0021] Figure 3 Photo of 0.1% attapulgite-nano calcium carbonate-pesticide slow-release granules sown with soybean seeds

[0022] Figure 4 Photos of the effects of binders and thickeners on the loading uniformity of granules: (a) 0.5% PVA-1788 + 0.02% xanthan gum; (b) 0.3% PEG + 0.025% guar gum; (c) 0.3% PEG + 0.05% gelatin; (d) 0.3% PVP + 0.05% gelatin; (e) 0.3% PVP + 0.05% guar gum.

[0023] Figure 5 Fludioxonil release profile

[0024] Figure 6 Metalaxyl release curve

[0025] Figure 7 Photo of the effect of material ratio on load uniformity

[0026] Figure 8 Photos of different granules mixed with soybean seeds: (a) active ingredient content 0.001%; ​​(b) active ingredient content 0.01%; (c) active ingredient content 0.1%; (d) active ingredient content 1%. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "including" will be understood to include the stated components or steps, without excluding other material components or steps.

[0028] In addition, in order to better illustrate the present invention, numerous specific details are given in the following detailed description.

[0029] Those skilled in the art will appreciate that the present invention can be implemented without certain specific details. In some embodiments, raw materials, methods, means, etc. that are well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present invention.

[0030] In the present invention, the percentage content refers to the mass percentage content unless otherwise specified.

[0031] In the present invention, "the nano-calcium carbonate carrier material is the first coating layer of the shell" is also called "nano-calcium carbonate-pesticide drug delivery system"

[0032] The present invention first provides a pesticide slow-release granule, which has a double-coating core-shell structure, wherein the double coating is a first coating and a second coating, wherein the first coating is a shell formed by using the pesticide active ingredient A as the core and nano calcium carbonate as the carrier material; and the second coating is a shell formed by mixing the first coating with the pesticide active ingredient B as the core and using attapulgite as the main material. Preferably, the shell material of the first coating also includes a regulator, and the regulator is preferably sodium dodecyl sulfate; the shell material of the second coating also includes a binder and a thickener, and a dye can be further added to distinguish the agents, wherein the binder is preferably PVA-1788; and the thickener is preferably xanthan gum.

[0033] Preferably, the pesticide active ingredient A in the above-mentioned pesticide slow-release granules is one or more of fludioxonil, tebuconazole, azoxystrobin, and fluazifop-butyl; the pesticide active ingredient B is one or more of metalaxyl-M, difenoconazole, fludioxonil, tebuconazole, azoxystrobin, and fluazifop-butyl.

[0034] Preferably, the content of the pesticide active ingredient A in the above-mentioned pesticide slow-release granules is 0.001-5%, and the content of the pesticide active ingredient B is 0.001-5%. Preferably, the content of the pesticide active ingredient A is 0.01-0.1%, and the content of the pesticide active ingredient B is 0.01-0.1%. It is particularly preferred that the total mass of the pesticide active ingredients A and B is 0.01-0.1% of the pesticide slow-release granules. In the optimal technical solution, the pesticide slow-release granules of the present invention can be in a moderate volume ratio with soybean seeds, the agent and the seeds can be mixed evenly, and the uniformity of the application is good. The present invention also provides a method for preparing the above-mentioned pesticide slow-release granules of the present invention, which comprises the following steps:

[0035] Step 1), dissolving the active ingredient A of the pesticide in an organic solvent to obtain a solution of the active ingredient A for later use;

[0036] Step 2), under stirring, adding the solution of the pesticide active ingredient A prepared in step 1) and the aqueous solution of the regulator to the calcium chloride solution, adding the sodium carbonate aqueous solution after the addition and stirring the reaction sufficiently, and obtaining a first coating layer containing the active ingredient A as the core and the nano calcium carbonate carrier material as the shell after post-treatment; the regulator is selected from one or more of sodium dodecyl sulfate, soy protein, starch and polyethylene glycol;

[0037] Step 3), dissolving a binder and a thickener in water for later use; the binder is selected from one or more of PVA-1788, PEG and PVP; the thickener is selected from one or more of xanthan gum, guar gum and gelatin;

[0038] Step 4), the first coating layer prepared in step 2) and the pesticide active ingredient B are mixed and added to the solution in step 3), stirred evenly, and then the attapulgite is added, and the mixture is dried after being adsorbed evenly.

[0039] Preferably, the pesticide active ingredient A in the above-mentioned method for preparing the pesticide sustained-release granules is one or more of fludioxonil, tebuconazole, azoxystrobin, and fluzoxacillin, with fludioxonil being particularly preferred; the pesticide active ingredient B is one or more of metalaxyl-M, difenoconazole, fludioxonil, tebuconazole, azoxystrobin, and fluzoxacillin, with metalaxyl-M being particularly preferred.

[0040] Preferably, in the above-mentioned method for preparing the pesticide slow-release granules, the content of the pesticide active ingredient A is 0.001-5%, and the content of the pesticide active ingredient B is 0.001-5%. Preferably, the content of the pesticide active ingredient A is 0.01-0.1%, and the content of the pesticide active ingredient B is 0.01-0.1%, and it is particularly preferred that the total mass of the pesticide active ingredients A and B is 0.01-0.1% of the pesticide slow-release granules. Preferably, the effective content of the pesticide ingredients can have a relatively excellent effect of exerting the efficacy.

[0041] Preferably, the organic solvent in step 1) of the above preparation method is selected from one or more of methanol, ethanol, acetonitrile, dichloromethane, acetone and propylene glycol; preferably methanol, ethanol and acetonitrile. Methanol is particularly preferred. The preferred solvent in the present invention can improve the drug loading rate and encapsulation rate of the pesticide.

[0042] Preferably, in the above preparation method, the regulator is selected from sodium dodecyl sulfate; the binder is selected from PVA-1788; and the thickener is selected from xanthan gum. Preferably, the binder is selected from PVA-1788, and the concentration is 0.1-5%, particularly preferably 1.75%, 1.6% and 0.5%; the thickener is selected from xanthan gum, and the concentration is 0.01-2%, particularly preferably 0.06% and 0.02%. The preferred combination of the binder and the thickener can effectively improve the loading effect of the first coating layer on the attapulgite.

[0043] Preferably, the volume ratio of the pesticide active ingredient A solution, calcium chloride aqueous solution, sodium dodecyl sulfonate aqueous solution and sodium carbonate aqueous solution in step 2) of the above preparation method is (0.05-0.15):1:(1-2):(1-2); the pesticide active ingredient A is preferably fludioxonil.

[0044] Preferably, the molar concentration of calcium chloride and sodium carbonate in step 2) of the above preparation method is 10mmol / L-1000mmol / L, preferably, 20mmol / L-200mmol / L, particularly preferably 50mmol / L-100mmol / L. Under particularly preferred conditions, the drug loading rate and encapsulation rate are relatively excellent.

[0045] Preferably, after the addition of the carbonate solution in step 2) of the above preparation method, the reaction time after sufficient stirring is 5-60 minutes, particularly preferably 10 minutes.

[0046] Preferably, after the addition of the carbonate solution in step 2) of the above preparation method, the temperature for fully stirring the reaction is 20-50°C, particularly preferably 30-40°C.

[0047] Preferably, in step 4) of the above preparation method, the mass ratio of attapulgite, water and load is 100: (4-14): (0.1-4). Preferably 100: 4: 0.3. Under the preferred conditions, the pesticide sustained-release granules obtained by the present invention have excellent uniformity. Among them, the load is the first coating layer of the shell of the nano calcium carbonate carrier material (nano calcium carbonate-pesticide drug-carrying system) and the active ingredient B original drug, and the water is the water used to dissolve the binder and thickener in step 3).

[0048] The present invention also provides the use of the above-mentioned pesticide slow-release granules in the prevention and treatment of crop diseases and insect pests.

[0049] The present invention also provides application of the pesticide slow-release granules obtained according to the preparation method of the present invention in preventing and controlling crop diseases and insect pests.

[0050] The present invention is further described below in conjunction with embodiments and drawings, but the protection scope of the present invention is not limited thereto.

[0051] Among them, the raw materials and reagents involved include:

[0052] CaCl 2 : Analytical grade, Sinopharm Chemical Reagent Co., Ltd., batch number: 20240103

[0053] Na 2 CO 3 : Analytical grade, Sinopharm Chemical Reagent Co., Ltd., batch number: 20230911

[0054] Sodium dodecyl sulfate: Beijing Solaibao Technology Co., Ltd. Lot.No.34230821002

[0055] Fludioxonil: content 95%, Yongnong Bioscience Co., Ltd.

[0056] Attapulgite: Hebei Jiashili Chemical Co., Ltd.

[0057] Coloring agent: Sijia brand water-based color paste, Hebei Jiashili Chemical Co., Ltd.

[0058] Xanthan gum: Shanghai Aladdin Biochemical Technology Co., Ltd., Lot: #E2428468

[0059] Methanol: Tianjin Concord Pharmaceutical Chemical Co., Ltd., LOT240619

[0060] The raw materials, reagents, etc. used in the examples that are not described in detail are all commercially available.

[0061] Example 1: Preparation of 0.15% attapulgite-nano calcium carbonate-pesticide sustained-release granules

[0062] Take 0.125 g of fludioxonil and dissolve it in 5 mL of methanol for later use. Take 50 mL of 100 mmol / L calcium chloride solution in a beaker, pour the fludioxonil solution and 100 mL of 100 mmol / L sodium dodecyl sulfonate solution into the beaker in sequence at 30°C and 500 r / min stirring conditions, continue stirring for 10 min, then add 100 mL of 100 mmol / L sodium carbonate solution dropwise to make it fully react, and obtain a nano-calcium carbonate fludioxonil sustained-release suspension, continue stirring for 10 min, let it stand, wash with water and centrifuge for a total of 3 times, and place the centrifuged product at 65°C to dry for 6 h to obtain a nano-calcium carbonate fludioxonil sustained-release system with a drug loading rate of 19%.

[0063] Take 4 ml of water, add PVA-1788 binder and xanthan gum to make their mass concentrations 1.75% and 0.06%, respectively, stir until dissolved, then add 0.3 g of nano calcium carbonate fludioxonil sustained-release system and 0.09 g of metalaxyl technical, stir evenly, add 0.1% dye, pour in 100 g of attapulgite particles (diameter 3-5 mm) and shake quickly to ensure sufficient adsorption, finally, the attapulgite-nano calcium carbonate-fludioxonil-metalaxyl sustained-release particles are dried at 60°C to obtain attapulgite-nano calcium carbonate-pesticide sustained-release granules, which can be applied simultaneously with wheat seed sowing in actual application, as shown in the photo. Figure 1 As shown, the structure of the sustained-release agent is as follows Figure 2 The total content of active ingredients of pesticides is 0.15% (0.06% of fludioxonil and 0.09% of metalaxyl-M).

[0064] Example 2: Preparation of 0.05% attapulgite-nano calcium carbonate-pesticide sustained-release granules

[0065] Take 8 ml of water, add PVA-1788 binder and xanthan gum to make the mass concentrations 0.5% and 0.02% respectively, stir until dissolved, then add 0.26 g of nano calcium carbonate pesticide delivery system (see Example 1) and 75 mg of metalaxyl-M active ingredient, pour in 250 g of attapulgite particles (about 6-7 mm in diameter) and shake quickly to ensure full adsorption, and dry naturally after the water is completely adsorbed. The attapulgite-nano calcium carbonate-fludioxonil-metalaxyl-M sustained-release particles are obtained, in which the metalaxyl-M content is 0.03% and the fludioxonil content is 0.02%. In actual application, the pesticide can be applied simultaneously with soybean seed sowing, as shown in the photo. Figure 3 shown.

[0066] Example 3: Effect of reactant concentration on drug loading rate during the preparation of nano-calcium carbonate-pesticide sustained-release system.

[0067] In the preparation process of nano-calcium carbonate-pesticide slow-release system, the appropriate concentration of reactants has an important influence on the encapsulation rate and drug loading rate of the nano-calcium carbonate-pesticide slow-release system. 2 and Na 2 CO 3 The concentration of CaCl 2 and Na 2 CO 3 When the concentration of CaCl was 100 mmol / L, the drug loading rate and encapsulation efficiency of the microspheres reached the best state. A moderate concentration of reactants is conducive to the formation of calcium carbonate microspheres with stable structure and good drug loading effect. In contrast, a higher concentration (200 mmol / L) of reactants led to a decrease in drug loading rate and encapsulation efficiency, which may be due to the excessively high ionic strength interfering with the structural stability of the microspheres and the encapsulation efficiency of the drugs. Therefore, in the preparation process of nano-calcium carbonate-pesticide sustained-release system, CaCl 2 and Na 2 CO 3 The optimal condition was 100 mmol / L.

[0068] Table 1 CaCl 2 and Na 2 CO 3 Effect of concentration on the sustained release system of nano-calcium carbonate-pesticide

[0069]

[0070] Example 4: Effect of solvent type on drug loading rate and encapsulation efficiency during the preparation of nano-calcium carbonate-pesticide sustained-release system.

[0071] In the preparation process of the nano-calcium carbonate-pesticide sustained-release system, the choice of solvent type has an important influence on the encapsulation rate and drug loading rate of the nano-calcium carbonate-pesticide sustained-release system. By changing the type of solvent for dissolving the active ingredient of the pesticide in Example 1, nano-calcium carbonate-pesticide sustained-release systems with different drug loading rates and encapsulation rates can be obtained, as shown in Table 2. The results show that the choice of solvent has an important influence on the drug loading effect of the microspheres. When methanol is used as a solvent, the nano-calcium carbonate-pesticide sustained-release system shows the highest drug loading rate and encapsulation rate (19.46% and 94.85%). When acetonitrile and ethanol are used as solvents, the drug loading rate and encapsulation rate are slightly lower than methanol, but still show a good encapsulation effect. Therefore, choosing methanol, acetonitrile, and ethanol as solvents can achieve a good loading effect, and methanol has the best effect.

[0072] Table 2 Effect of solvent type on nano-calcium carbonate-pesticide sustained-release system

[0073]

[0074] Example 5: Effect of stirring time on drug loading rate and encapsulation efficiency during the preparation of nano-calcium carbonate-pesticide sustained-release system.

[0075] In the preparation process of nano calcium carbonate-pesticide slow-release system, stirring time has an important influence on the encapsulation rate and drug loading rate of nano calcium carbonate-pesticide slow-release system, and affects the production efficiency. By changing the stirring time after the addition of sodium carbonate in Example 1, nano calcium carbonate-pesticide slow-release systems with different drug loading rates and encapsulation rates can be obtained, as shown in Table 3. The results show that stirring time also has a significant effect on the drug loading and encapsulation properties of microspheres. Experimental data show that under a stirring time of 10 min, the drug loading rate and encapsulation rate reach 19.46% and 94.85%, respectively, which is the best performance. Shorter (5 min) or longer (30 min and 60 min) stirring time leads to a decrease in drug loading rate and encapsulation rate, especially when the stirring time is too long (such as 60 min), the encapsulation rate drops to 30.28%. This may be due to the instability of the microsphere structure or the release of the drug caused by excessive stirring time, thereby reducing the encapsulation efficiency. Therefore, considering factors such as drug loading rate, encapsulation rate and production time cost, stirring for 10 min is the optimal reaction condition.

[0076] Table 3 Effect of stirring time on nano calcium carbonate-pesticide sustained release system

[0077]

[0078] Example 6: Effect of stirring temperature on drug loading rate and encapsulation efficiency during the preparation of nano-calcium carbonate-pesticide sustained-release system.

[0079] In the preparation process of the nano-calcium carbonate-pesticide slow-release system, the stirring temperature has an important influence on the encapsulation rate and drug loading rate of the nano-calcium carbonate-pesticide slow-release system, and also affects the production cost. By changing the stirring temperature in Example 1, nano-calcium carbonate-pesticide slow-release systems with different drug loading rates and encapsulation rates can be obtained, as shown in Table 4. The results show that there is no significant difference in the effect of temperature on the drug loading rate and encapsulation rate. At 30-40°C, the drug loading rate is 19.17%-19.46%, and the encapsulation rate is 89.05%-94.85%. Considering the energy consumption of temperature control, a stirring temperature of 30°C can save production costs and is the optimal stirring temperature.

[0080] Table 4 Effect of stirring temperature on nano-calcium carbonate-pesticide slow-release system

[0081]

[0082] Example 7: Effect of the type of regulator on drug loading rate and encapsulation efficiency during the preparation of nano-calcium carbonate-pesticide sustained-release system.

[0083] In the preparation process of nano calcium carbonate-pesticide sustained-release system, the type of regulator has an important influence on the encapsulation rate and drug loading rate of the nano calcium carbonate-pesticide sustained-release system. By changing the type of regulator in Example 1, nano calcium carbonate-pesticide sustained-release systems with different drug loading rates and encapsulation rates can be obtained, as shown in Table 5. The results show that different regulators have significant effects on crystal nucleation, stability of sustained-release system, and drug binding mode. Sodium dodecylbenzene sulfonate, as an anionic surfactant, promotes the stable growth of calcium carbonate nuclei by reducing the surface energy of the system, thereby achieving a higher drug loading rate and encapsulation rate. Protein molecules bind to drugs and crystal surfaces through multiple hydrogen bonds and electrostatic interactions, which significantly improves the encapsulation rate, but this high encapsulation rate may be accompanied by excessive concentration of drug molecules on the surface of crystals or carriers, resulting in a relatively low drug loading rate. Although polyethylene glycol can stabilize the system, its high viscosity and molecular chain length hinder drug embedding, resulting in low drug loading rate and encapsulation rate. The network structure formed by starch improves the encapsulation efficiency (97.18%), but its polarity and steric hindrance limit the drug loading, and the drug loading rate is only 12.03%. Therefore, sodium dodecylbenzene sulfonate is the best choice as a regulator.

[0084] Table 5 Effect of regulators on nano calcium carbonate-pesticide slow-release system

[0085]

[0086] Example 8: Effects of binder and thickener on the loading uniformity of attapulgite during the preparation of attapulgite-nano calcium carbonate-pesticide slow-release granules.

[0087] In the preparation process of attapulgite-nano calcium carbonate-pesticide slow-release granules, the selection of binders and thickeners has an important influence on the loading uniformity. By changing the type and amount of binders and thickeners in Example 2 as shown in Table 6, different attapulgite-nano calcium carbonate-pesticide slow-release granules can be obtained. Figure 4 As shown in the figure, when PVA-1788 and xanthan gum are used as binders and thickeners respectively, the loading of attapulgite on the calcium carbonate drug delivery system is uniform and stable, while when other combinations such as PGE+guar gum, PEG+gelatin, PVP+gelatin, and PVP+guar gum are used, although attapulgite can load the nano-calcium carbonate drug delivery system, the loading effect is uneven and the best effect cannot be achieved. Therefore, the combination of PVA-1788 and xanthan gum as binders and thickeners is the best choice.

[0088] Table 6 Effect of binder and thickener on loading uniformity of attapulgite

[0089]

[0090] Example 9: Sustained Release Effect

[0091] Prepare release medium solution, wherein ethanol, water volume ratio is 70: 30. Weigh the fludioxonil original medicine and 30mg metalaxyl original medicine of active ingredient 20mg respectively, and the nano calcium carbonate fludioxonil slow-release system and attapulgite-nano calcium carbonate-pesticide slow-release granules in Example 1, and place in a volume of 200mL release medium solution respectively, and release at 120rpm under 25 ± 1°C in a constant temperature shock reactor. Sample 1mL at regular intervals, and pass 0.22μm water filter membrane, and detect the content of imidacloprid with high performance liquid chromatograph. Add 1mL of release medium solution after each sampling, and calculate the cumulative release rate according to the following formula.

[0092]

[0093] Where:

[0094] Q——Cumulative release rate, expressed in %;

[0095] V0 – total volume of dissolution medium (200 mL);

[0096] CT – the mass concentration of the active ingredient in the dissolution medium measured at the release time point, in milligrams per milliliter (mg / mL);

[0097] V——volume of each sample (1 mL);

[0098] W——The total mass of active ingredients in the system.

[0099] Figure 5is the cumulative release rate of the active ingredient fludioxonil. Under the same release conditions, the fludioxonil original drug dissolves rapidly; the initial release of the fludioxonil active ingredient in the nano-calcium carbonate drug delivery system is slow, and the cumulative release rate reaches 90% in the first 6 hours; while the initial release of the attapulgite-nano-calcium carbonate drug delivery system is even slower, with a cumulative release rate of only 51.3% in the first 6 hours, and it can only reach more than 90% after 30 hours. The results show that the nano-calcium carbonate drug delivery system has a certain controlled release effect on the active ingredient fludioxonil, while the attapulgite-nano-calcium carbonate drug delivery system has a more stable release rate and a better controlled release effect. Therefore, the drug delivery system with double-layer coating of attapulgite and nano-calcium carbonate has a better controlled release effect than the single-layer coated drug delivery system.

[0100] Figure 6 is the cumulative release rate of the active ingredient metalaxyl-M. Under the same release conditions, the metalaxyl-M original drug dissolved rapidly; while the initial release of the attapulgite-nano calcium carbonate drug delivery system was very slow, reaching more than 80% after 35 hours and 100% release after 46 hours. The results show that the attapulgite-nano calcium carbonate drug delivery system has a good controlled release effect and a stable release rate for the active ingredient metalaxyl-M.

[0101] Example 10: Effects of the ratio of attapulgite, water, nano-calcium carbonate pesticide delivery system + metalaxyl-M technical and the concentration of binder and xanthan gum on particle loading uniformity

[0102] By changing the mass ratio of attapulgite, water, (nano-calcium carbonate pesticide loading system + metalaxyl-M technical), and the concentration of PVA-1788 binder and xanthan gum in Example 1, pesticide sustained-release granules were prepared respectively. The specific ratios and concentrations are shown in Table 2. The photos of granule loading uniformity are shown in FIG. Figure 7 The results show that when attapulgite with a particle size of 3-5 mm is selected as the carrier material, the mass ratio of attapulgite, water, and (nano-calcium carbonate pesticide loading system + metalaxyl-M) has a great influence on the uniformity of the sustained-release particle loading. At the same time, the concentrations of PVA-1788 binder and xanthan gum in the system also affect the loading uniformity. When the ratio of attapulgite: water: (nano-calcium carbonate pesticide loading system + metalaxyl-M) is 100: 4: 0.3, the concentration of xanthan gum is 0.06%, and the concentration of PVA-1788 binder is 1.6%, the uniformity of the sustained-release particles is the best.

[0103] Table 5 The mass ratio of different attapulgite, water, (nano-calcium carbonate pesticide delivery system + metalaxyl technical), and the concentration of PVA-1788 binder and xanthan gum

[0104]

[0105] Example 11: Field trial results

[0106] The one-time application method of "drug and seed co-sowing" was adopted to clarify the control effect of slow-release granules and traditional seed coating agents on soybean root rot. A soybean field trial was conducted in Xinxiang, Henan Province, with each treatment area of ​​300 m 2 , 4 kg of soybean seeds were used for each treatment. The results showed that compared with traditional seed coating agents, at the same dosage, the controlled-release system can effectively improve the emergence rate of soybean seeds; 60 days after application, at the same dosage, the controlled-release product can reduce the incidence of soybean root rot, and no soybean phytotoxicity was observed, proving that it is safer for crops.

[0107] Table 6 Field test results

[0108]

[0109] Example 12: Effect of active ingredient content of sustained-release granules on pesticide application

[0110] According to the recommendation of the Pesticide Information Network, the dosage of the mixture of metalaxyl-M and fludioxonil is 25g of active ingredient / 100kg of seeds. When the dosage is 25g of active ingredient / 100kg of seeds, the content of active ingredient in the slow-release granules is changed to 0.001%, 0.01%, 0.1%, and 1%, and the "drug and seed co-sowing" one-time application is carried out. The effect of the mixed drug and seed is shown in the photo. Figure 8 The results show that when the content of the active ingredient in the slow-release granules is too low (0.001%), the granules will be used in large quantities, resulting in waste of production materials; when the content of the active ingredient in the slow-release granules is too high (1%), the volume ratio of the granules to the soybean seeds will be too low, and the agent and the seeds cannot be mixed evenly, which is not conducive to the efficacy of the drug; when the content of the active ingredient in the slow-release granules is between 0.01% and 0.1%, the volume ratio of the granules to the soybean seeds is moderate, the agent and the seeds can be mixed evenly, and the uniformity of the application is good, which is the best choice.

[0111] The above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A pesticide slow-release granule, characterized in that: The pesticide slow-release granules have a double-coating core-shell structure, wherein the double coating is a first coating and a second coating, the first coating is a shell formed by using the pesticide active ingredient A as a core and nano-calcium carbonate as a carrier material; the second coating is a shell formed by using a mixture of the first coating and the pesticide active ingredient B as a core and attapulgite as a carrier material; the pesticide active ingredient A is fludioxonil; the pesticide active ingredient B is metalaxyl-M; The content of the active ingredient A of the pesticide is 0.001-5%, and the content of the active ingredient B of the pesticide is 0.001-5%; The shell material of the first coating layer also includes a regulator; the regulator is selected from sodium dodecyl sulfate; The shell material of the second coating layer also includes a binder and a thickener; The binder is selected from PVA-1788; The thickener is selected from xanthan gum.

2. The pesticide slow-release granules according to claim 1, characterized in that: The content of the pesticide active ingredient A is 0.01-0.1%, and the content of the pesticide active ingredient B is 0.01-0.1%.

3. A method for preparing the pesticide slow-release granules according to claim 1, characterized in that: The steps include: Step 1), dissolving the active ingredient A of the pesticide in an organic solvent to obtain a solution of the active ingredient A for later use; Step 2), under stirring, adding the solution of the pesticide active ingredient A prepared in step 1) and the aqueous solution of the regulator to the calcium chloride aqueous solution, adding the sodium carbonate aqueous solution after the addition and stirring the reaction sufficiently, and after treatment, obtaining a first coating layer containing the active ingredient A as the core and the nano calcium carbonate carrier material as the shell; the regulator is selected from sodium dodecyl sulfate; Step 3), dissolving the binder and thickener in water for later use; the binder is selected from PVA-1788; the thickener is selected from xanthan gum; Step 4), add the first coating layer and the pesticide active ingredient B prepared in step 2) to the solution in step 3), stir evenly, then add the attapulgite, adsorb evenly and dry.

4. The preparation method according to claim 3, characterized in that: The organic solvent is selected from methanol.

5. The preparation method according to claim 3, characterized in that: The volume ratio of the pesticide active ingredient A solution, the calcium chloride aqueous solution, the sodium dodecyl sulfonate aqueous solution, and the sodium carbonate aqueous solution is (0.05-0.15):1:(1-2):(1-2).

6. Use of the pesticide slow-release granules according to any one of claims 1 to 2 in preventing and controlling crop diseases and insect pests.

7. Use of the pesticide slow-release granules obtained according to any one of claims 3 to 5 in preventing and controlling crop diseases and insect pests.

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