A network interpenetrating modified bio-based coated controlled-release fertilizer and a preparation method thereof

Abstract

The application discloses a kind of network interpenetrating modification based on biological base film coated controlled-release fertilizer and preparation method thereof, belong to controlled-release fertilizer production technical field.The network interpenetrating modification based on biological base film material of the application is prepared by substrate A, substrate B and nutrient release adjusting material according to mass ratio (4-30) :(4-30) :(1-3);The substrate A is biological base epoxy resin;The substrate B is polyethylene imine;The nutrient release adjusting material is at least two kinds of mixture consisting of epoxidized lignin, modified aminocellulose and modified starch.The application improves the controlled-release performance of biological base film material by network interpenetrating modification treatment, and coating reaction can be carried out at normal temperature, which greatly reduces energy consumption and cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of slow / controlled release fertilizer production, in particular to a bio-based coated controlled release fertilizer based on network interpenetration modification and a preparation method thereof. BACKGROUND

[0002] At present, the use amount of chemical fertilizer is huge, and over-fertilization is common. The utilization rate of fertilizer is generally between 30%-60%, and the waste and pollution are quite serious. Slow / controlled release fertilizer can significantly improve the utilization rate of fertilizer, but the coating materials of the currently marketed controlled release fertilizer are mostly derived from petroleum chemical products, which are high in cost and non-renewable, and are not conducive to the sustainable development of the industry.

[0003] In recent years, bio-based materials have attracted widespread attention due to their low cost, renewability and degradability, and have been developed and applied to controlled release fertilizer coating. Bio-based coated fertilizers prepared by using bio-based materials are low in price, renewable in resources, efficient and environmentally friendly, and have important social and economic benefits. However, the bio-based coated fertilizers synthesized by using bio-based coating materials have many pores or a large number of hydrophilic groups, which accelerate the entry of water into the coating material, cause the coating material to swell and absorb water, and increase the permeability, thereby accelerating the release of nutrients and greatly shortening the controlled release period of nutrients, affecting the controlled release quality. Therefore, modification of bio-based coating materials is the only way to promote the development and progress of the industry.

[0004] Interpenetrating polymer network (IPN) is a unique type of polymer composed of two or more interpenetrating polymers. IPN has good thermal stability and mechanical properties, and its structure and properties can be customized through interpenetrating network technology. At present, IPN is widely used in hydrogels, rubbers, polyelectrolyte films and coatings, etc. However, there are few reports on the modification of bio-based coating materials for controlled release. SUMMARY

[0005] In view of the problems existing in the prior art, the purpose of the present application is to provide a bio-based coated controlled release fertilizer based on network interpenetration modification and a preparation method thereof.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] In a first aspect of the present application, a bio-based coating material based on network interpenetration modification is provided, which is prepared from a base material A, a base material B and a nutrient release regulating material in a mass ratio of (4-30):(4-30):(1-3).

[0008] The base material A is a bio-based epoxy resin; the base material B is polyethyleneimine; and the nutrient release regulating material is a mixture of at least two of epoxy lignin, modified amino cellulose and modified starch.

[0009] Preferably, the bio-based epoxy resin is prepared by the following method:

[0010] After dissolving the vegetable oil in acetone, it is placed in a reaction kettle, concentrated sulfuric acid and formic acid are added, the temperature is set to 50-60 DEG C, and 40% concentration hydrogen peroxide is slowly dropped, the reaction is stopped after 6h, and the lower layer wastewater is removed after layering.

[0011] More preferably, the vegetable oil is one or more of palm oil, soybean oil, castor oil.

[0012] More preferably, the mass ratio of vegetable oil, acetone, concentrated sulfuric acid, formic acid is 15: (10-20): (0.5-1): (1-3).

[0013] Preferably, the epoxidized lignin is prepared by the following method:

[0014] After dissolving the lignin in sodium hydroxide solution, heating to 65-75 DEG C, adding epichlorohydrin, constant temperature reaction for 2.5-3.5h, adjusting the pH to neutral, and drying by suction filtration, the epoxidized lignin is prepared.

[0015] The modified aminated cellulose is prepared by the following method:

[0016] After crushing the waste paper shell, it is placed in an ethylene glycol solution, concentrated sulfuric acid is used as a catalyst, and ethylenediamine is used as an amination reagent, and the mixture is stirred at 140-160 DEG C for 2-4h.

[0017] The modified starch is prepared by the following method:

[0018] After mixing the starch and water uniformly to prepare a starch slurry, sodium sulfite is added to the starch slurry and stirred for 20-40min, and then hydrochloric acid is added for acid hydrolysis reaction for 2-3h; the solution after acid hydrolysis is adjusted to neutral, urea and ammonium persulfate are added, and the mixture is reacted at 55-65 DEG C for 3-5h, cooled to room temperature, precipitated with ethanol, suction filtered, washed, and dried.

[0019] Preferably, the nutrient release regulating material is a mixture of epoxidized lignin and amide-modified starch in a mass ratio of 2:1.

[0020] In a second aspect of the present application, the bio-based coating material is used in the preparation of controlled-release fertilizers.

[0021] In a third aspect of the present application, a bio-based coated controlled-release fertilizer is provided, comprising: a fertilizer core and a bio-based coating material wrapped on the surface of the fertilizer core.

[0022] Preferably, the amount of bio-based coating material added is 1-10% of the weight of the fertilizer core.

[0023] A fourth aspect of the present invention provides a method for preparing the above-mentioned bio-based coated controlled-release fertilizer, comprising the following steps:

[0024] The fertilizer core is added into a coating machine. Under rotating conditions, substrate A and substrate B of the bio-based coating material are added first, and the pre-reaction is carried out at room temperature for 3-5 minutes. Then, the nutrient release regulating material of the bio-based coating material is added, and the reaction is continued for 10-20 minutes. The film is solidified on the surface of the fertilizer core to prepare a bio-based coated controlled-release fertilizer.

[0025] The mechanism of action of the bio-based coated controlled-release fertilizer of the present invention is as follows:

[0026] Substrate A and Substrate B are constructed simultaneously to form an interpenetrating network framework, which serves as the main material for the coated fertilizer. Its dense coating can prevent water from entering. The nutrient release regulating material functions as a switch to regulate water channels. It is inserted into the network of the substrate to further construct the interpenetrating network structure, adjust the network pore size, and act as a water conduit to regulate the rate of water entering the membrane and nutrient release. This process is a stepwise method for constructing the interpenetrating network structure.

[0027] Substrate A is a bio-based epoxy resin purified from one or more mixtures of palm oil, soybean oil, and castor oil; another substrate B, which can interpenetrate with it in a network, is polyethyleneimine. Under room temperature conditions, a nucleophilic ring-opening reaction occurs between the epoxy groups of the epoxy resin and the amino groups of polyethyleneimine.

[0028] The specific process is as follows: The nitrogen atom in the amino group of polyethyleneimine has a lone pair of electrons, exhibiting nucleophilicity. It attacks the carbon atom in the epoxy group of the epoxy resin, causing the three-membered ring structure of the epoxy group to open. Therefore, the epoxy resin molecular chain and the open-ring polyethyleneimine molecular chain can be connected by covalent bonds. Their molecular chains interweave and entangle in space, ultimately forming a network-interpenetrating framework structure. This process can be carried out at room temperature. This material has advantages such as low cost, good controlled-release effect, environmental friendliness, low energy consumption, simple preparation process, and short preparation time, making it an ideal controlled-release membrane material.

[0029] The added nutrient release regulator material is a mixture of two or more of epoxidized lignin, modified amino cellulose, and modified starch. Because these materials have different charged groups on their molecular chains, when mixed with the substrate at room temperature, the molecular chains tend to arrange themselves perpendicular to the network structure of the substrate under electrostatic effects. This vertical arrangement allows for the efficient use of space between the molecular chains, forming a channel structure, similar to a "wick," thus creating nanoscale or microscale pores for water entry and exit, thereby controlling the rate of water entry and nutrient dissolution. By selecting different materials and varying the proportions, the nutrient release regulator material can form different numbers and sizes of micro / nanoscale pores on the substrate, thereby regulating the rate at which water enters the membrane and nutrients dissolve, ultimately achieving the goal of controlling nutrient release.

[0030] The beneficial effects of this invention are:

[0031] (1) The coating process is simple, the reaction can be carried out at room temperature, the curing time is fast, which greatly reduces energy consumption and costs, and is suitable for large-scale production.

[0032] (2) The residual film of the coated controlled-release fertilizer produced by the present invention can be degraded and contains certain organic nutrients, which can provide nutrition to crops after decomposition.

[0033] (3) Coated controlled-release fertilizers have a good controlled-release effect and can meet the fertilizer requirements of different crops as needed. Attached Figure Description

[0034] Figure 1 : Schematic diagram of the formation process of the interpenetrating network structure; In the figure, 1. Substrate A; 2. Substrate B; 3. Construction of the interpenetrating network framework; 4. Addition of nutrient release regulating material; 5. Synthesis of bio-based coating material modified based on interpenetrating network technology.

[0035] Figure 2 : A schematic diagram of the controlled-release principle of the bio-based coated controlled-release fertilizer of the present invention; in the figure, 1, fertilizer granules; 2, interpenetrating membrane material; 3, water channels formed by the regulation of modified materials; 4, nutrient release regulator material; 5, water channels.

[0036] Figure 3 Cross-sectional views of the bio-based membrane shells prepared in Example 1 and Comparative Example 1 of this invention. In the figure, A is a cross-sectional view of the membrane shell of Comparative Example 1, and B is a cross-sectional view of the membrane shell of Example 1. Detailed Implementation

[0037] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0038] Terminology Explanation:

[0039] In this article, "normal temperature" refers to a temperature range of 15-25℃.

[0040] As mentioned earlier, interpenetrating polymer networks (IPNs) are a unique type of polymer composed of two or more cross-linked polymers, and can be used in fields such as hydrogels, rubber, polyelectrolyte films, and coatings. However, since the raw materials for forming IPNs are mostly homogeneous polymers, they cannot form nanoscale channels through electrostatic or hydrogen bonding self-assembly. Directly using IPNs as bio-based coating materials results in a single-diffusion sustained-release curve, which is prone to explosive release in the later stages; moreover, the film is brittle and easily cracks and detaches. Therefore, research on the controlled-release modification of bio-based coating materials using IPNs is still relatively rare.

[0041] In view of this, this invention has conducted an in-depth study on the application of interpenetrating polymer networks in bio-based coating materials. The synthesis process of the bio-based coating material modified by the network interpenetration technology of this invention is as follows: Figure 1 As shown, this invention selects bio-based epoxy resin as substrate A, polyethyleneimine as substrate B, and a mixture of at least two of epoxidized lignin, modified amino cellulose, and modified starch as nutrient release regulating material. Substrate A and substrate B are constructed simultaneously to form an interpenetrating network framework, which serves as the main material of the coated fertilizer. The function of the nutrient release regulating material is to act as a switch to regulate water channels. It is inserted into the network of the substrate to further construct the interpenetrating network structure, adjust the network pore size, and act as a water conduit to regulate the rate of water entering the membrane and nutrient release. This process is a stepwise method for constructing the interpenetrating network structure.

[0042] The controlled release principle of the bio-based coating material of the present invention is as follows: Figure 2 As shown, nutrient release regulator materials are used to form a "wick"-like structure, thereby creating nanoscale or microscale channels for water entry and exit, thus controlling the rate of water entry and nutrient dissolution. By selecting different materials and varying the proportions, nutrient release regulator materials can form different numbers and sizes of micro- and nanoscale channels on the substrate, thereby regulating the rate at which water enters the membrane and nutrients dissolve, ultimately achieving the goal of controlling nutrient release.

[0043] To enable those skilled in the art to better understand the technical solution of this application, the technical solution of this application will be described in detail below with reference to specific embodiments.

[0044] The test materials used in the embodiments and comparative examples of this invention are all conventional test materials in the art and can be purchased through commercial channels. Experimental methods without specified detailed conditions were performed according to conventional test methods or the supplier's recommended operating instructions. Wherein:

[0045] CAS number for polyethyleneimine: 9002-98-6.

[0046] The preparation method of bio-based epoxy resin is as follows:

[0047] Dissolve 15g of palm oil in 20g of acetone and place it in a reaction vessel. Add 0.5g of concentrated sulfuric acid and 2g of formic acid. Set the temperature to 55℃ and slowly add 3g of hydrogen peroxide with a mass concentration of 40%. Stop the reaction after 6 hours, let it stand to separate into layers, and remove the lower layer of wastewater.

[0048] The preparation method of epoxidized lignin is as follows:

[0049] Dissolve 10g of lignin in 100mL of 1mol / L sodium hydroxide solution, add the solution to a three-necked flask equipped with a stirrer, heat in a water bath to 70℃, add 30mL of epichlorohydrin, reflux at a constant temperature for 3h, adjust the pH to neutral, filter and dry to obtain epoxidized lignin.

[0050] The preparation method of modified amino-modified cellulose is as follows:

[0051] Waste paperboard was crushed and 10g was placed in 100ml of 80% ethylene glycol solution. 0.8ml of concentrated sulfuric acid was used as a catalyst, and 10ml of ethylenediamine was used as an amination reagent. The reaction was carried out at 150℃ with continuous stirring for 3 hours. After the reaction was completed, the mixture was cooled to room temperature, the pH was adjusted to neutral, and the mixture was filtered, washed, and dried.

[0052] The modified starch is prepared as follows:

[0053] Mix 10g of starch with 90ml of water to prepare a 10% starch slurry. Add 0.5g of sodium sulfite to the starch slurry and stir for 30 minutes. Then add 5ml of hydrochloric acid and allow the reaction to proceed for 2.5 hours. Adjust the solution to neutral, add 5g of urea and 0.05g of ammonium persulfate, react at 60℃ for 4 hours, cool to room temperature, precipitate with 95% (v / v) ethanol, filter, wash, and dry to obtain the modified starch.

[0054] The above-mentioned modification treatments of lignin, cellulose, and starch can, on the one hand, introduce ionic groups so that they can be inserted into the interpenetrating network structure; on the other hand, introduce functional groups to enhance the reactivity and compatibility of natural polymers.

[0055] Example 1: Preparation of Bio-based Coated Controlled-Release Fertilizer Based on Network Interpenetrating Modification

[0056] 1. Raw material composition:

[0057] Large-particle urea and bio-based coating materials;

[0058] in:

[0059] The bio-based coating material consists of substrate A (bio-based epoxy resin), substrate B (polyethyleneimine), and nutrient release regulator (a mixture of epoxidized lignin and modified starch in a mass ratio of 2:1).

[0060] 2. Preparation method:

[0061] Substrate A and Substrate B were mixed at a mass ratio of 1:1 to obtain a substrate mixture. 10 kg of large-particle urea (3-5 mm in diameter) was added to the coating machine pot, and the machine was started to rotate (30 rpm). Then, 80 g of the substrate mixture was added to the coating machine, and after a pre-reaction at room temperature for 3 minutes, 20 g of nutrient release regulator was added. The reaction was continued at room temperature, and after 20 minutes, a film was formed on the surface of the fertilizer particles. This process was repeated three times. Finally, the rotation was stopped, the fertilizer was removed, packaged, and stored, thus preparing a bio-based coated controlled-release fertilizer based on network interpenetrating modification. In this embodiment, the bio-based coating material accounts for 3% of the weight of urea in the prepared bio-based coated controlled-release fertilizer.

[0062] Example 2: Preparation of Bio-based Coated Controlled-Release Fertilizer Based on Network Interpenetrating Modification

[0063] 1. Raw material composition:

[0064] Particulate diammonium phosphate and bio-based coating materials;

[0065] in:

[0066] The bio-based coating material consists of substrate A (bio-based epoxy resin), substrate B (polyethyleneimine), and nutrient release regulating material (a mixture of epoxidized lignin, modified starch, and modified amino cellulose in a mass ratio of 6:3:1).

[0067] 2. Preparation method:

[0068] Substrate A and Substrate B were mixed at a mass ratio of 1:1 to obtain a substrate mixture. 10 kg of granular diammonium phosphate was added to the coating machine pot, and the machine was started to rotate (35 r / min). 80 g of the substrate mixture was added to the coating machine, and after a pre-reaction at room temperature for 5 minutes, 20 g of nutrient release regulator was added. The reaction was continued at room temperature, and after 20 minutes, a film was formed on the surface of the fertilizer granules. This process was repeated 5 times. Finally, the rotation was stopped, the fertilizer was removed, packaged, and stored, thus preparing a bio-based coated controlled-release fertilizer based on network interpenetrating modification. In this embodiment, the bio-based coating material accounts for 5% of the weight of urea in the prepared bio-based coated controlled-release fertilizer.

[0069] Example 3: Preparation of Bio-based Coated Controlled-Release Fertilizer Based on Network Interpenetrating Modification

[0070] 1. Raw material composition:

[0071] Granular potassium sulfate fertilizer and bio-based coating materials;

[0072] in:

[0073] The bio-based coating material consists of substrate A (bio-based epoxy resin), substrate B (polyethyleneimine), and nutrient release regulating material (a mixture of epoxidized lignin and modified amino cellulose in a 1:1 mass ratio).

[0074] 2. Preparation method:

[0075] Substrate A and Substrate B were mixed at a mass ratio of 2:1 to obtain a substrate mixture. 10 kg of granular potassium sulfate fertilizer was added to the coating machine pot, and the machine was started and rotated (40 rpm). Then, 85 g of the substrate mixture was added to the coating machine. After 5 minutes, 15 g of nutrient release regulator was added, and the reaction proceeded. After 20 minutes, a film was formed on the surface of the fertilizer granules. This process was repeated 5 times. Finally, the rotation was stopped, the fertilizer was removed, packaged, and stored. A bio-based coated controlled-release fertilizer based on network interpenetrating modification was prepared. In this embodiment, the bio-based coating material accounts for 5% of the weight of urea in the bio-based coated controlled-release fertilizer.

[0076] Comparative Example 1:

[0077] 1. Raw material composition:

[0078] Large-particle urea and bio-based coating materials;

[0079] in:

[0080] The bio-based coating material consists of substrate A (bio-based epoxy resin) and substrate B (polyethyleneimine).

[0081] 2. Preparation method:

[0082] Substrate A and Substrate B were mixed at a mass ratio of 1:1 to obtain a bio-based coating material. 10 kg of large-particle urea (particle size 3-5 mm) was added to the coating machine pot, and the machine was turned on and rotated (30 r / min). Then, 100 g of the bio-based coating material was added to the coating machine, and the reaction was carried out at room temperature. After 20 minutes, a film was formed on the surface of the fertilizer particles. This process was repeated 3 times. Finally, the rotation was stopped, the fertilizer was removed, packaged, and stored to prepare a bio-based coated controlled-release fertilizer with simple network interpenetration modification.

[0083] Comparative Example 2:

[0084] 1. Raw material composition:

[0085] Particulate diammonium phosphate and bio-based coating materials;

[0086] in:

[0087] The bio-based coating material consists of substrate A (bio-based epoxy resin) and substrate B (polyethyleneimine).

[0088] 2. Preparation method:

[0089] Substrate A and Substrate B were mixed at a mass ratio of 1:1 to obtain a bio-based coating material. 10 kg of granular diammonium phosphate was added to the coating machine pot, and the machine was turned on and rotated (35 r / min). 100 g of the bio-based coating material was added to the coating machine, and the reaction was carried out at room temperature. After 20 minutes, a film was formed on the surface of the fertilizer granules. This process was repeated 5 times. Finally, the rotation was stopped, the fertilizer was removed, packaged, and stored to prepare a bio-based coated controlled-release fertilizer with simple network interpenetration modification.

[0090] Comparative Example 3:

[0091] 1. Raw material composition:

[0092] Granular potassium sulfate fertilizer and bio-based coating materials;

[0093] in:

[0094] The bio-based coating material consists of substrate A (bio-based epoxy resin) and substrate B (polyethyleneimine).

[0095] 2. Preparation method:

[0096] Substrate A and Substrate B were mixed at a mass ratio of 1:1 to obtain a bio-based coating material. 10 kg of granular potassium sulfate fertilizer was added to the coating machine pot, and the machine was started to rotate (40 r / min). Then, 100 g of the bio-based coating material was added to the coating machine, and the reaction was carried out at room temperature. After 20 minutes, a film was formed on the surface of the fertilizer granules. This process was repeated 5 times. Finally, the rotation was stopped, the fertilizer was removed, packaged, and stored, thus preparing a bio-based coated controlled-release fertilizer with simple network interpenetration modification.

[0097] Experimental Example 1:

[0098] Electron microscopy was performed on cross-sections of the bio-based membrane shells of the bio-based coated controlled-release fertilizers prepared in Example 1 and Comparative Example 1. The results are as follows: Figure 3 As shown, the bio-based membrane shell of Comparative Example 1 was not modified with nutrient release regulating material, and its membrane shell was loose and porous; while the bio-based membrane shell of Example 1 was modified with nutrient release regulating material, and its structure was more compact.

[0099] Experimental Example 2:

[0100] The nutrient release time of the bio-based coated controlled-release fertilizers prepared in Examples 1-3 and Comparative Examples 1-3 was measured.

[0101] The method for determining the controlled release time of nutrients is as follows: 10g of the prepared fertilizer is placed in a mesh bag and then placed in 200ml of deionized water at 25℃. Every 7 days, 1ml is taken to measure the nutrient release concentration, and the water is replaced with a fresh 200ml of deionized water until the nutrients are completely released. The nutrient release concentration is determined using the conventional methods for nitrogen, phosphorus, and potassium. The cumulative release rate is obtained by summing the measured nutrient release concentrations.

[0102] The results showed that the nutrient release time of the bio-based coated controlled-release fertilizer prepared in Example 1 was about 90 days, which was 3 times longer than that of the bio-based coated controlled-release fertilizer prepared in Comparative Example 1.

[0103] The nutrient release time of the bio-based coated controlled-release fertilizer prepared in Example 2 is about 120 days, which is 4 times longer than that of the bio-based coated controlled-release fertilizer prepared in Comparative Example 2.

[0104] The nutrient release time of the bio-based coated controlled-release fertilizer prepared in Example 2 is about 150 days, which is 5 times longer than that of the bio-based coated controlled-release fertilizer prepared in Comparative Example 3.

[0105] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A bio-based coating material based on network interpenetration modification, characterized in that, It is prepared from substrate A, substrate B and nutrient release regulating material in a mass ratio of (4-30):(4-30):(1-3); The substrate A is a bio-based epoxy resin; the substrate B is polyethyleneimine; the nutrient release regulating material is a mixture of at least two of epoxidized lignin, modified amino cellulose, and modified starch; The bio-based epoxy resin is prepared by the following method: Vegetable oil was dissolved in acetone and placed in a reaction vessel. Concentrated sulfuric acid and formic acid were added. The temperature was set to 50-60℃. Hydrogen peroxide was slowly added dropwise. The reaction was stopped after 6 hours. The mixture was allowed to stand and separate into layers. The lower layer of wastewater was removed. The epoxidized lignin is prepared by the following method: Lignin was dissolved in sodium hydroxide solution, heated to 65-75℃, and epichlorohydrin was added. The mixture was reacted at a constant temperature for 2.5-3.5 hours. The pH was adjusted to neutral, and the mixture was then filtered and dried to prepare epoxidized lignin. The modified aminoated cellulose is prepared by the following method: The waste paperboard was crushed and placed in an ethylene glycol solution. Concentrated sulfuric acid was used as a catalyst and ethylenediamine was used as an amination reagent. The mixture was stirred at 140-160℃ for 2-4 hours. The modified starch is prepared by the following method: Mix starch and water evenly to make a starch slurry. Add sodium sulfite to the starch slurry and stir for 20-40 minutes. Then add hydrochloric acid and react for 2-3 hours. Adjust the solution after the acid reaction to neutral, add urea and ammonium persulfate, and react at 55-65℃ for 3-5 hours. Cool to room temperature, precipitate with ethanol, filter, wash and dry.

2. The bio-based coating material according to claim 1, characterized in that, The vegetable oil is one or more of palm oil, soybean oil, and castor oil.

3. The bio-based coating material according to claim 1, characterized in that, The mass ratio of vegetable oil, acetone, concentrated sulfuric acid, and formic acid is 15:(10-20):(0.5-1):(1-3).

4. The bio-based coating material according to claim 1, characterized in that, The nutrient release regulating material is a mixture of epoxidized lignin and modified starch in a mass ratio of 2:

1.

5. The application of the bio-based coating material according to any one of claims 1-4 in the preparation of controlled-release fertilizers.

6. A bio-based coated controlled-release fertilizer, characterized in that, include: The fertilizer core and the bio-based coating material as described in any one of claims 1-4, which is wrapped around the surface of the fertilizer core.

7. The bio-based coated controlled-release fertilizer according to claim 6, characterized in that, The amount of bio-based coating material added is 1-10% of the weight of the fertilizer core.

8. The method for preparing the bio-based coated controlled-release fertilizer according to claim 6 or 7, characterized in that, Includes the following steps: The fertilizer core is added into a coating machine. Under rotating conditions, substrate A and substrate B of the bio-based coating material are added first, and the pre-reaction is carried out at room temperature for 3-5 minutes. Then, the nutrient release regulating material of the bio-based coating material is added, and the reaction is continued for 10-20 minutes. The film is solidified on the surface of the fertilizer core to prepare a bio-based coated controlled-release fertilizer.

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