Multi-layer coated medical fertilizer and preparation method thereof

Abstract

The invention belongs to the technical field of agricultural chemical products, and particularly relates to a multi-layer coated pesticide fertilizer and a preparation method thereof.The multi-layer coated pesticide fertilizer sequentially comprises a core layer, a first coating layer, a first functional layer, a second coating layer, a second functional layer, a third coating layer and a shell layer from inside to outside, the first functional layer comprises a balance fertilizer and a bactericide, the second functional layer comprises a nitrogen fertilizer and a second insecticide, and the shell layer comprises a biostimulant; the degradation rate of the third coating layer is greater than that of the second coating layer, and the degradation rate of the second coating layer is greater than that of the first coating layer; according to the multi-layer coated medical fertilizer disclosed by the invention, through a layer-by-layer degradation mechanism, the release of the fertilizer and the pesticide is matched with three key growth periods of crops, the growth period of the crops can be covered by applying the multi-layer coated medical fertilizer once, and the input amount and the loss amount of the fertilizer and the pesticide are reduced.

Description

Technical Field

[0001] This invention belongs to the field of agricultural chemical products technology, specifically a multi-layer coated fertilizer and its preparation method. Background Technology

[0002] Existing rice pesticide-fertilizer mixtures are mostly simple physical mixtures or single-coating types. They mainly have the following problems: (1) Asynchronous release: The release curves of fertilizers and pesticides do not match the specific fertilizer requirements of rice and the occurrence cycle of pests and diseases, and cannot provide effective protection during the critical window period.

[0003] (2) Single function: Ordinary controlled-release fertilizer can only control the release of nutrients and cannot integrate pesticide functions; while ordinary pesticide fertilizer lacks control over the release of pesticides, resulting in a short effective period or premature release.

[0004] (3) Environmental risks: Uncontrolled release of pesticides can easily lead to loss and environmental pollution.

[0005] Rice has different peak demand for nutrients (nitrogen, phosphorus, and potassium) at different growth stages (such as tillering, heading, and grain-filling). At the same time, the occurrence of major pests and diseases (such as rice stem borer, rice planthopper, and rice blast) also follows specific patterns. Current technology cannot achieve precise matching of "supplying fertilizer as needed and preventing pests as soon as they occur". Summary of the Invention

[0006] To solve the above-mentioned technical problems, the present invention provides a multi-layer coated fertilizer, which comprises, from the inside out: a core layer, a first coating layer, a first functional layer, a second coating layer, a second functional layer, a third coating layer, and an outer shell layer. The first coating layer covers the core layer, the first functional layer is disposed outside the first coating layer, the second coating layer covers the first functional layer, the second functional layer is disposed outside the second coating layer, the third coating layer covers the second functional layer, and the outer shell layer covers the third coating layer. The core layer includes potassium fertilizer and a first insecticide; the first functional layer includes balanced fertilizer and a fungicide; the second functional layer includes nitrogen fertilizer and a second insecticide; and the outer shell layer includes a biostimulant. The degradation rate of the third coating layer is greater than that of the second coating layer, and the degradation rate of the second coating layer is greater than that of the first coating layer.

[0007] The mass ratio of the core layer, the first functional layer, and the second functional layer is (0.5~1.5):(0.5~1.5):(0.5~1.5).

[0008] In the core layer, the mass fraction of the potassium fertilizer is 97wt%~99.5wt%, the mass fraction of the first insecticide is 0.4wt%~2.9wt%, and the remainder is adhesive. In the first functional layer, the mass fraction of the balanced fertilizer is 98wt%~99.8wt%, the mass fraction of the fungicide is 0.1wt%~1.9wt%, and the remainder is adhesive; In the second functional layer, the nitrogen fertilizer has a mass fraction of 98.5wt% to 99.8wt%, the second insecticide has a mass fraction of 0.4wt% to 1.9wt%, and the remainder is an adhesive.

[0009] The potassium fertilizer in the core layer has a nutrient content of 45% or more, the balanced fertilizer in the first functional layer has a nutrient content of 40% or more, and the nitrogen fertilizer in the second functional layer has a nutrient content of 35% or more.

[0010] Wherein, the dry film mass of the first coating layer is 1% to 5% of the mass of the core layer, the dry film mass of the second coating layer is 1% to 5% of the total mass of the core layer and the first functional layer, and the dry film mass of the third coating layer is 1% to 5% of the total mass of the multi-layer coated fertilizer.

[0011] The first coating layer is polycaprolactone, the second coating layer is polylactic acid, and the third coating layer is polyvinyl alcohol or sodium alginate.

[0012] The biostimulant is composed of polyglutamic acid and γ-aminobutyric acid in a mass ratio of (2~10):1, and the biostimulant accounts for 0.01%~0.2% of the total mass of the multi-layer coated fertilizer.

[0013] Wherein, the first insecticide and the second insecticide are any one of thiamethoxam, thiamethoxam, dinotefuran, and chlorantraniliprole; the fungicide is any one of azoxystrobin, oxamoxin, metalaxyl, tebuconazole, and thifluzamide; and the adhesive is at least one of bentonite, starch, and sodium carboxymethyl cellulose.

[0014] To address the aforementioned technical problems, the present invention also provides a method for preparing a multi-layer coated pesticide fertilizer, the method comprising the following steps: S1. Prepare the core layer; S2. Prepare a first coating layer outside the core layer; S3. Prepare a first functional layer outside the first coating layer; S4. Prepare a second coating layer outside the first functional layer; S5. Prepare a second functional layer outside the second coating layer; S6. Prepare a third coating layer outside the second functional layer, and prepare an outer shell layer outside the third coating layer to obtain the multi-layer coated fertilizer.

[0015] Specifically, step S1 involves crushing potassium fertilizer to 80-120 mesh and mixing it evenly with a first insecticide and binder to obtain a first mixture. Then, 5%-8% of deionized water is added to the first mixture and stirred to obtain a first moist material. The first moist material is then granulated, dried until its moisture content is less than or equal to 3%, cooled, and sieved to obtain core layer particles with a particle size of 1-4 mm. Specifically, step S2 involves dissolving polycaprolactone in ethyl acetate to obtain a first coating solution, wherein the mass ratio of polycaprolactone to ethyl acetate is 1:(7~9), spraying the first coating solution onto the core layer particles, drying and cooling to room temperature, and forming a first coating layer on the core layer particles to obtain a first masterbatch. Specifically, step S3 involves crushing the balanced fertilizer to 100-120 mesh and mixing it evenly with a bactericide and a binder to obtain a second mixture. Then, 6%-9% of deionized water by mass of the second mixture is added to the second mixture and stirred to obtain a second moist material. The first masterbatch and the second moist material are granulated, dried until their moisture content is less than or equal to 3%, cooled, and sieved to form a first functional layer on the outside of the first masterbatch to obtain the first functional layer particles. Specifically, step S4 involves dissolving polylactic acid in a mixed solvent of dichloromethane and ethanol in a volume ratio of 1:1 to form a second coating solution containing 8wt%~12wt% polylactic acid, spraying the second coating solution onto the first functional layer particles, drying and cooling to room temperature, and forming a second coating layer on the first functional layer particles to obtain the second masterbatch. Specifically, step S5 involves crushing nitrogen fertilizer to 100-200 mesh and uniformly mixing it with the second insecticide and binder to obtain a third mixture. Then, 7%-10% of deionized water by mass of the third mixture is added to the third mixture and stirred to obtain a third moist material. The second masterbatch and the third moist material are granulated, dried until their moisture content is less than or equal to 3%, cooled, and sieved to form a second functional layer on the outside of the second masterbatch to obtain the second functional layer particles. Specifically, step S6 involves dissolving polyvinyl alcohol in deionized water at 80-90°C to form a third coating solution containing 8wt%-10wt% polyvinyl alcohol, spraying the third coating solution onto the second functional layer particles, drying and cooling to room temperature, and forming a third coating layer on the second functional layer particles to obtain the third masterbatch. Specifically, step S7 involves mixing polyglutamic acid and γ-aminobutyric acid in a mass ratio of (2~10):1 and dissolving them in deionized water to obtain a biostimulant solution. The biostimulant solution is then sprayed onto the third masterbatch to form an outer shell layer, thus obtaining the multi-layer coated fertilizer.

[0016] The multi-layer coated fertilizer of this invention achieves the release of fertilizer and pesticides in accordance with the three key growth stages of crops through a layer-by-layer degradation mechanism. A single application can cover the entire growth cycle of crops, reducing the input and loss of fertilizers and pesticides, and is environmentally friendly. By coating the outermost layer with biostimulants, the utilization rate of fertilizers and pesticides is significantly improved. Detailed Implementation

[0017] The technical solutions described below in conjunction with the embodiments will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] This invention provides a multi-layer coated fertilizer, which comprises, from the inside out: a core layer, a first coating layer, a first functional layer, a second coating layer, a second functional layer, a third coating layer, and an outer shell layer. The first coating layer covers the core layer, the first functional layer is disposed outside the first coating layer, the second coating layer covers the first functional layer, the second functional layer is disposed outside the second coating layer, the third coating layer covers the second functional layer, and the outer shell layer covers the third coating layer. The core layer includes potassium fertilizer and a first insecticide; the first functional layer includes balanced fertilizer and a fungicide; the second functional layer includes nitrogen fertilizer and a second insecticide; and the outer shell layer includes a biostimulant. The degradation rate of the third coating layer is greater than that of the second coating layer, and the degradation rate of the second coating layer is greater than that of the first coating layer.

[0019] This invention precisely designs the functions of each layer of a multi-layered coated fertilizer: the outer shell layer is a biostimulant, serving as a fast-acting absorption promoter and water-retaining layer; the second functional layer corresponds to the tillering stage of the plant, containing high-nitrogen compound fertilizer and systemic insecticides (such as thiamethoxam), coated with a rapidly degradable material (polyvinyl alcohol, PVA); the first functional layer corresponds to the heading stage of the plant, containing balanced fertilizer and broad-spectrum fungicides (such as pyraclostrobin), coated with a material with a medium degradation rate (polylactic acid, PLA); the core layer corresponds to the grain-filling stage of the plant, containing high-potassium compound fertilizer and sustained-release insecticides (such as pymetrozine), coated with a slowly degradable material (polycaprolactone, PCL), ensuring that the core layer is released last. Through the simplification and efficient combination of pesticide types, only two pesticides (systemic insecticide and broad-spectrum fungicide) are used to cover the main pests and diseases throughout the entire growth period of rice, reducing resistance risks and environmental burden; a single basal application can meet the fertilizer and pesticide needs of the main growth stages of rice, greatly saving labor costs. The release of fertilizers and pesticides is highly synchronized with the needs of rice during its growth stage, improving their utilization rate. By increasing utilization and precise application, the total amount of chemical fertilizers and pesticides used is reduced, lowering the risk of non-point source pollution, while ensuring healthy rice growth and increasing yield. The outer layer of biostimulants enhances the root system's efficiency in nutrient absorption, creating a synergistic effect with controlled-release technology.

[0020] Example 1 Weigh 980g of 10-10-25 high-potassium compound fertilizer, 15g of chlorantraniliprole, and 5g of bentonite. Crush the high-potassium compound fertilizer to 100 mesh and mix it evenly with chlorantraniliprole and bentonite in a mixer to obtain the first mixture. Spray 60g of deionized water into the first mixture and stir until the material is evenly moistened to obtain the first moist material. Put it into a rotary drum granulator and dry it at 80℃ until the moisture content is ≤3%. After cooling, sieve out spherical particles of 1~4mm to obtain the core layer particles.

[0021] 30g of polycaprolactone and ethyl acetate were dissolved in ethyl acetate at a mass ratio of 1:9 and stirred thoroughly to prepare the first coating solution. 1000g of core layer particles were placed in a fluidized bed coating machine and preheated to 40℃. The first coating solution was evenly sprayed onto the particle surface and dried with hot air (50℃) to evaporate the solvent. After the coating solution was completely sprayed and dried, it was cooled to room temperature to obtain the first masterbatch.

[0022] Weigh 990g of 15-15-15 balanced fertilizer, 8g of azoxystrobin, and 2g of sodium carboxymethyl cellulose. Crush the balanced fertilizer to 100 mesh and mix it with azoxystrobin and sodium carboxymethyl cellulose in a mixer to obtain a second mixture. Spray 80g of deionized water into the second mixture and stir until the material is evenly moistened to obtain a second moist material. Put 1000g of the first masterbatch into a rotary drum granulator. During the rolling process, the second moist material gradually and evenly coats the surface of the first masterbatch to form an outer layer. After granulation, dry it at 75℃ until the moisture content is ≤3%, cool and sieve to obtain the first functional layer granules. Dissolve 80g of polylactic acid in a mixed solvent of dichloromethane and ethanol in a volume ratio of 1:1 to prepare a 10wt% second coating solution. Place the first functional layer particles in a fluidized bed coating machine, preheat to 45°C, spray with the second coating solution, dry with hot air (55°C), and cool to room temperature to obtain the second masterbatch.

[0023] Weigh 985g of 30-5-5 high-nitrogen compound fertilizer, 12g of thiamethoxam, and 3g of starch. Crush the high-nitrogen compound fertilizer to 100 mesh and mix it with thiamethoxam and starch in a mixer to obtain a third mixture. Spray 85g of deionized water into the third mixture and stir until the material is evenly moistened to obtain a third moist material. Put the above second masterbatch into a rotary drum granulator and gradually and evenly coat the surface of the second masterbatch with the third moist material to form an outer layer. After drying (70℃), cooling, and sieving, the second functional layer granules are obtained. Add 60g of polyvinyl alcohol (PVA 1788) to 540g of hot deionized water at 90℃, stir vigorously until completely dissolved, cool to room temperature, and prepare a 10wt% third coating solution. Place the above second functional layer particles in a fluidized bed coating machine, preheat to 50℃, spray with the third coating solution, dry with hot air (60℃), and cool to room temperature to obtain the third masterbatch.

[0024] Weigh 2g of polyglutamic acid with a purity of 25% and 1g of γ-aminobutyric acid with a purity of 98%, dissolve them in deionized water, and prepare a 3wt% biostimulant solution. Place the above third masterbatch in a fluidized bed coating machine, and spray the biostimulant solution evenly onto the surface of the particles at a temperature of 40℃. After drying, a multi-layer coated fertilizer is obtained.

[0025] The mass ratio of the core layer, the first functional layer, and the second functional layer of the multi-layer coated fertilizer prepared in Example 1 is approximately 1:1:1.

[0026] Comparative Example 1 Comparative Example 1 is a conventional slow-release fertilizer, which is coated with a single layer of PVA and contains the same amount of total nutrients and pesticides as the multi-layer coated fertilizer of Example 1.

[0027] Comparative Example 2 Comparative Example 2 is a conventional fertilizer without coating, containing the same amount of total nutrients and pesticides as the multi-layer coated fertilizer of Example 1.

[0028] Comparative Example 3 Unlike Example 1, no first coating layer, no second coating layer, and no third coating layer were prepared.

[0029] Comparative Example 4 Unlike Example 1, no first coating layer was prepared, and no second coating layer was prepared.

[0030] Comparative Example 5 Unlike Example 1, no outer shell layer was prepared.

[0031] Experiment Example 2 The multi-layer coated fertilizer prepared in Example 1 and the fertilizer prepared in Comparative Examples 1-5 were used to treat hybrid rice "Yongyou 1540" (with a growth period of about 135 days). All treatments were applied as a single basal application of 50 kg / mu before transplanting. The results are shown in Table 1.

[0032] Table 1 Example 1 demonstrated stable late-stage fertilizer effect, with rice flag leaves remaining green for a longer period, resulting in fuller grains. At the same time, the incidence of diseases and pests throughout the heading stage was significantly lower than that of the control group.

[0033] Comparative examples 1-5: Nutrients are released in a concentrated manner in the early stage, and nutrient deficiency and premature aging occur in the later stage. In addition, the pesticide has a short duration of action and additional pesticides are required in the later stage.

[0034] Comparative Examples 2 and 3 demonstrate that coated controlled release is fundamental. Regardless of whether the structure is layered, nutrients and pesticides in the uncoated form will be rapidly lost in the early stages, leading to severe nutrient deficiency and uncontrolled pests and diseases in the later stages, resulting in the lowest yield.

[0035] Comparative Examples 1 and 4 demonstrate that the outermost slow-release membrane alone cannot achieve the timing control of nutrients in the inner layers. The lack of the first and second coating layers causes high-nitrogen compound fertilizers and balanced fertilizers to be released too early, resulting in a flattened release curve, which prevents the formation of the peak nutrient supply during the booting stage (reducing the number of grains per ear), and shortens the pesticide's residual effect (exacerbating pests and diseases).

[0036] Although the yields of Comparative Example 5 and Example 1 were not significantly different, the thousand-grain weight and seed setting rate decreased slightly, indicating that the polyglutamic acid and γ-aminobutyric acid in the outer shell layer played a positive role in promoting root activity and nutrient transport during the grain-filling period.

[0037] This invention releases thiamethoxam (the second insecticide) and high-nitrogen compound fertilizer simultaneously during the tillering stage to effectively control planthoppers; releases chlorantraniliprole (the first insecticide) and high-potassium compound fertilizer during the grain-filling stage to control stem borers; and releases azoxystrobin (a fungicide) and balanced fertilizer during the booting stage to prevent diseases. This bundled, precise delivery of "pesticides + corresponding nutrients" is the fundamental reason for the lowest incidence of pests and diseases, an effect that none of the comparative methods can achieve.

[0038] The multi-layer coated fertilizer of this invention achieves the release of fertilizer and pesticides in accordance with the three key growth stages of crops through a layer-by-layer degradation mechanism. A single application can cover the entire growth cycle of crops, reducing the input and loss of fertilizers and pesticides, and is environmentally friendly. By coating the outermost layer with biostimulants, the utilization rate of fertilizers and pesticides is significantly improved.

[0039] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A multi-layer coated fertilizer, characterized in that, The multi-layer coated fertilizer comprises, from the inside out: a core layer, a first coating layer, a first functional layer, a second coating layer, a second functional layer, a third coating layer, and an outer shell layer. The first coating layer covers the core layer, the first functional layer is disposed outside the first coating layer, the second coating layer covers the first functional layer, the second functional layer is disposed outside the second coating layer, the third coating layer covers the second functional layer, and the outer shell layer covers the third coating layer. The core layer includes potassium fertilizer and a first insecticide; the first functional layer includes balanced fertilizer and a fungicide; the second functional layer includes nitrogen fertilizer and a second insecticide; and the outer shell layer includes a biostimulant. The degradation rate of the third coating layer is greater than that of the second coating layer, and the degradation rate of the second coating layer is greater than that of the first coating layer.

2. The multi-layer coated fertilizer according to claim 1, characterized in that, The mass ratio of the core layer, the first functional layer, and the second functional layer is (0.5~1.5):(0.5~1.5):(0.5~1.5).

3. The multi-layer coated fertilizer according to claim 1, characterized in that, In the core layer, the mass fraction of the potassium fertilizer is 97wt%~99.5wt%, the mass fraction of the first insecticide is 0.4wt%~2.9wt%, and the remainder is adhesive; In the first functional layer, the mass fraction of the balanced fertilizer is 98wt%~99.8wt%, the mass fraction of the fungicide is 0.1wt%~1.9wt%, and the remainder is adhesive; In the second functional layer, the nitrogen fertilizer has a mass fraction of 98.5wt% to 99.8wt%, the second insecticide has a mass fraction of 0.4wt% to 1.9wt%, and the remainder is an adhesive.

4. The multi-layer coated fertilizer according to claim 1, characterized in that, The potassium fertilizer in the core layer has a nutrient content of 45% or more, the balanced fertilizer in the first functional layer has a nutrient content of 40% or more, and the nitrogen fertilizer in the second functional layer has a nutrient content of 35% or more.

5. The multi-layer coated fertilizer according to claim 1, characterized in that, The dry film mass of the first coating layer is 1% to 5% of the mass of the core layer, the dry film mass of the second coating layer is 1% to 5% of the total mass of the core layer and the first functional layer, and the dry film mass of the third coating layer is 1% to 5% of the total mass of the multi-layer coated fertilizer.

6. The multi-layer coated fertilizer according to claim 1, characterized in that, The first coating layer is polycaprolactone, the second coating layer is polylactic acid, and the third coating layer is polyvinyl alcohol or sodium alginate.

7. The multi-layer coated fertilizer according to claim 1, characterized in that, The biostimulant is composed of polyglutamic acid and γ-aminobutyric acid in a mass ratio of (2~10):1, and the biostimulant accounts for 0.01%~0.2% of the total mass of the multi-layer coated fertilizer.

8. The multi-layer coated fertilizer according to claim 1, characterized in that, The first insecticide and the second insecticide are any one of thiamethoxam, thiamethoxam, dinotefuran, and chlorantraniliprole; the fungicide is any one of azoxystrobin, oxamoxin, metalaxyl, tebuconazole, and thifluzamide; and the adhesive is at least one of bentonite, starch, and sodium carboxymethyl cellulose.

9. A method for preparing a multi-layer coated fertilizer according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Prepare the core layer; S2. Prepare a first coating layer outside the core layer; S3. Prepare a first functional layer outside the first coating layer; S4. Prepare a second coating layer outside the first functional layer; S5. Prepare a second functional layer outside the second coating layer; S6. Prepare a third coating layer outside the second functional layer, and prepare an outer shell layer outside the third coating layer to obtain the multi-layer coated fertilizer.

10. The method for preparing a multi-layer coated fertilizer according to claim 8, characterized in that, Specifically, step S1 involves crushing potassium fertilizer to 80-120 mesh and mixing it evenly with the first insecticide and binder to obtain a first mixture. Then, 5%-8% of deionized water (by mass of the first mixture) is added to the first mixture and stirred to obtain a first moist material. The first moist material is then granulated, dried until its moisture content is less than or equal to 3%, cooled, and sieved to obtain core layer particles with a particle size of 1-4 mm. Specifically, step S2 involves dissolving polycaprolactone in ethyl acetate to obtain a first coating solution, wherein the mass ratio of polycaprolactone to ethyl acetate is 1:(7~9), spraying the first coating solution onto the core layer particles, drying and cooling to room temperature, and forming a first coating layer on the core layer particles to obtain a first masterbatch. Specifically, step S3 involves crushing the balanced fertilizer to 100-120 mesh and mixing it evenly with a bactericide and a binder to obtain a second mixture. Then, 6%-9% of deionized water by mass of the second mixture is added to the second mixture and stirred to obtain a second moist material. The first masterbatch and the second moist material are granulated, dried until their moisture content is less than or equal to 3%, cooled, and sieved to form a first functional layer on the outside of the first masterbatch to obtain the first functional layer particles. Specifically, step S4 involves dissolving polylactic acid in a mixed solvent of dichloromethane and ethanol in a volume ratio of 1:1 to form a second coating solution containing 8wt%~12wt% polylactic acid, spraying the second coating solution onto the first functional layer particles, drying and cooling to room temperature, and forming a second coating layer on the first functional layer particles to obtain the second masterbatch. Specifically, step S5 involves crushing nitrogen fertilizer to 100-200 mesh and uniformly mixing it with the second insecticide and binder to obtain a third mixture. Then, 7%-10% of deionized water by mass of the third mixture is added to the third mixture and stirred to obtain a third moist material. The second masterbatch and the third moist material are granulated, dried until their moisture content is less than or equal to 3%, cooled, and sieved to form a second functional layer on the outside of the second masterbatch to obtain the second functional layer particles. Specifically, step S6 involves dissolving polyvinyl alcohol in deionized water at 80-90°C to form a third coating solution containing 8wt%-10wt% polyvinyl alcohol, spraying the third coating solution onto the second functional layer particles, drying and cooling to room temperature, and forming a third coating layer on the second functional layer particles to obtain the third masterbatch. Specifically, step S7 involves mixing polyglutamic acid and γ-aminobutyric acid in a mass ratio of (2~10):1 and dissolving them in deionized water to obtain a biostimulant solution. The biostimulant solution is then sprayed onto the third masterbatch to form an outer shell layer, thus obtaining the multi-layer coated fertilizer.

Images