DMPP nano-material coated granule as well as preparation method and application thereof

Abstract

The invention relates to the technical field of fertilizers, in particular to a DMPP nano material coated granule as well as a preparation method and application thereof. The invention provides a DMPP nano material coated granule, which is prepared from the following raw materials in parts by weight: 50 to 65 parts of 3, 4-dimethyl pyrazole phosphate, 15 to 20 parts of stabilizing agents, 5 to 10 parts of buffering agents and 15 to 20 parts of nano coating agents. The stabilizer comprises biogenic functional polysaccharide, organic acid, cyclodextrin and a phosphorus-activated milk mixture. The stability of the DMPP is improved by combining the DMPP with the stabilizer, and then a high-temperature-resistant (the temperature can be increased to 180 DEG C or above) and salt-resistant net-shaped film layer is formed outside the DMPP by utilizing the nano coating agent, so that the high-temperature resistance and salt resistance of the DMPP are further improved, and the problems that the DMPP original medicine is not high-temperature-resistant and not saline-alkaline-resistant are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of fertilizer technology, specifically to a DMPP nanomaterial-coated granule agent, its preparation method, and its application. Background Technology

[0002] Among numerous nitrification inhibitors, 3,4-dimethylpyrazole phosphate (DMPP) has attracted widespread attention due to its high efficiency. However, existing DMPP technical grade exhibits significant performance defects during application, primarily poor chemical stability and sensitivity to high temperatures and saline-alkali environments. Thermal decomposition occurs during high-temperature processes (typically exceeding 80°C) necessary for industrial fertilizer production, such as granulation and drying, resulting in initial loss of the active ingredient. Simultaneously, its molecular structure is easily damaged and degraded in high-ion-concentration compound fertilizer formulations or alkaline soil environments. This inherent stability defect leads to a high loss rate of DMPP throughout the entire chain from factory production to field application, significantly weakening its expected effect as a nitrification inhibitor and resulting in low cost-effectiveness for farmers, severely hindering the large-scale promotion of this highly efficient technology in agriculture. Furthermore, in existing granule preparation processes, some coating materials (such as polyethylene) are difficult to degrade. Long-term, large-scale use can easily cause soil compaction and may release organic pollutants during degradation, posing a potential environmental risk.

[0003] Traditional coating technologies have limited ability to process small-particle or powdered active ingredients, making it difficult to achieve uniform and firm coating. The resulting granules tend to be too large, failing to meet the application requirements of precision agriculture scenarios such as greenhouse seedling cultivation and potted plants. From a technical efficiency perspective, these traditional methods struggle to form a complete, dense, and robust coating layer on the surface of micron-sized DMPP technical particles. The coating layer contains microscopic defects, failing to effectively block the penetration of water and oxygen, as well as contact with salt ions in the soil, thus limiting its protective effect on the active ingredients. This results in compromised long-term storage performance of DMPP and, moreover, causes coated DMPP to still be released and decompose too quickly in the soil, failing to achieve the "slow-release" function of delaying nitrification inhibition and ultimately failing to significantly reduce field loss of active ingredients.

[0004] In summary, the inadequacies of existing DMPP technical grade pesticides in terms of stability, and the limitations of traditional coating technologies in terms of material environmental friendliness and process applicability, jointly restrict the further application of this type of nitrification inhibitor in efficient and green agriculture. Therefore, there is an urgent need to develop a DMPP nanomaterial-coated granule formulation with high temperature and salt-alkali resistance and long-term storage capability to improve its applicability and durability in complex agricultural environments. Summary of the Invention

[0005] This invention provides a DMPP nanomaterial-coated particulate agent, its preparation method, and its application to solve the above-mentioned problems.

[0006] In a first aspect, the present invention provides a DMPP nanomaterial coating particle agent, comprising the following raw materials in parts by weight: 50-65 parts of 3,4-dimethylpyrazole phosphate, 15-20 parts of stabilizer, 5-10 parts of buffer, and 15-20 parts of nano-coating agent. The stabilizers include bio-derived functional polysaccharides, organic acids, cyclodextrins, and phosphorus-activated emulsifiers.

[0007] In one optional embodiment, the mass ratio of bio-derived functional polysaccharide, organic acid, cyclodextrin and phosphorus-activated emulsifier in the stabilizer is (2-7):(1-4):(1-5):(3-7); In one optional embodiment, the bio-derived functional polysaccharide includes at least one of chitosan oligosaccharide, β-glucan, and seaweed extract; Optionally, the seaweed extract includes at least one of fucoidan and sodium alginate; In one alternative embodiment, the organic acid includes at least one of phytic acid, citric acid, and fulvic acid; In one alternative embodiment, the cyclodextrin includes at least one of β-cyclodextrin, hydroxypropyl-β-cyclodextrin, and methyl-β-cyclodextrin.

[0008] In one optional embodiment, the total content of the active ingredient in the phosphorus-activated emulsion is 19%-21%.

[0009] In one alternative embodiment, the stabilizer further includes a natural polymer derivative; Optionally, the natural polymer derivative includes at least one of starch derivatives and cellulose derivatives; optionally, it is at least one of cross-linked starch and hydroxypropyl methylcellulose. It should be noted that the starch derivatives or cellulose derivatives include those obtained by chemically modifying natural starch or cellulose (introducing polybasic acids or crosslinking agents, carboxymethyl and other functional groups) to solve the defects of poor water solubility, insufficient stability and single function of natural starch or cellulose, while retaining the core characteristics of polysaccharides such as thickening, stabilization, film formation and degradability. In one optional embodiment, the mass ratio of the bio-derived functional polysaccharide to the natural polymer derivative in the stabilizer is (2-7):(0-5).

[0010] In one alternative embodiment, the buffer comprises diatomaceous earth and bentonite.

[0011] In one optional embodiment, the nanocoating agent comprises at least one of polysaccharides and their derivatives, biopolyesters, and natural minerals; Optionally, the polysaccharide and its derivatives include at least one of polymerized chitosan nanoparticles, chitin nanofibers, starch and starch derivatives, and brown seaweed cellulose nanofibers. Further optionally, the starch and starch derivatives include at least one of sodium carboxymethyl starch, hydroxypropyl starch phosphate, starch-g-polyacrylic acid graft copolymer, and phosphate starch; Optionally, the biopolyester includes at least one of polyhydroxyalkanoate nanoscale aqueous suspension and polylactic acid nanofibers; Further optionally, the mass concentration of the polyhydroxyalkanoate nanoscale aqueous suspension is 9%-12%; Optionally, the natural mineral includes at least one of nano-kaolin, nano-montmorillonite, and nano-zeolite.

[0012] In one optional embodiment, the nanocoating agent further includes an acidic solvent and an ionic crosslinking agent; Optionally, the acidic solvent includes at least one of glacial acetic acid solution, aqueous citric acid solution, and aqueous lactic acid solution; Optionally, the ionic crosslinking agent includes at least one of sodium tripolyphosphate, sodium pyrophosphate, and sodium hexametaphosphate.

[0013] Secondly, the present invention provides a method for preparing the above-mentioned DMPP nanomaterial coated particles, comprising the following steps: S1, after mixing the stabilizer and 3,4-dimethylpyrazole phosphate, a crosslinking agent is added to carry out a crosslinking reaction, followed by heat treatment to obtain core particles; S2, the buffer and core particles are mixed and coated to obtain buffer-coated particles; S3, mix the nano-coating agent and the buffer layer coating particles for coating treatment, and then heat-cur to obtain the DMPP nanomaterial coated particles.

[0014] In one optional embodiment, the crosslinking reaction takes 10-15 minutes; In one optional embodiment, the crosslinking agent solution accounts for 0.5-1.0% of the total mass of the stabilizer and 3,4-dimethylpyrazole phosphate mixture. In one optional embodiment, the crosslinking agent solution includes at least one of calcium chloride solution, calcium nitrate solution, and polyethylene glycol solution; Optionally, the mass concentration of the calcium chloride solution is 1.5%-3.0%; Optionally, the mass concentration of the calcium nitrate solution is 0.8% to 1.2%. Optionally, the mass concentration of the polyethylene glycol solution is 9.8%-10.2%.

[0015] In one optional embodiment, the heat treatment is performed at a temperature of 40-45°C for a time of 1-1.5 hours.

[0016] In one optional embodiment, the coating treatment is performed at a temperature of 35-40°C for 15-20 minutes.

[0017] In one optional embodiment, the coating treatment is performed at a temperature of 40-50°C for a time when the buffer layer particles are completely coated by the mesh nanofilm. In one optional embodiment, the thermosetting temperature is 80-85°C and the time is 25-35 minutes.

[0018] It should be noted that step S1 also includes adding a stabilizer and stirring in a mixer at 30-60℃ and a stirring rate of 45-55 r / min; then slowly adding the DMPP technical material to form a stable DMPP mixture. The organic acids in the stabilizer that have the characteristics of "weak acidity and strong chelating ability" (such as citric acid, tartaric acid, and fulvic acid) can adjust the pH to the stable range of DMPP, inhibit chemical hydrolysis, chelate free metal ions in the soil, and block catalytic degradation, thereby making DMPP more stable. Cyclodextrins can coat part of the DMPP. Because DMPP is a small molecule organic compound, its molecular diameter is highly matched with the hydrophobic cavity size of specific cyclodextrins (such as β-CD), which satisfies the spatial conditions for "molecules to enter the cavity". Bio-derived functional polysaccharides can promote colloidal adhesion and achieve material aggregation. They possess high viscosity and adhesiveness, binding loose material particles together to form preliminary, shaped "soft granules" under the stirring and extrusion of a granulator. Subsequent cationic cross-linking solidifies the granules, firmly locking them within a network framework, significantly improving their mechanical strength, breakage resistance, and stability, ultimately forming compliant "hard granules." Continuous stirring for 30-80 minutes forms a homogeneous DMPP mixture. The mixture is then heated to 40-45℃ and stirred for 1 hour. Through hydrogen bonding or coordination reactions between the stabilizer and DMPP molecules, a stable DMPP mixture is formed. Sampling and testing of the DMPP's thermal stability ensure the compounding effect.

[0019] It should be noted that the coating process in step S2 includes first mixing the buffer (dry diatomaceous earth and bentonite powder) evenly, then setting the inlet air temperature of the fluidized bed coating machine to 35-40℃ and the fluidization air velocity to 2-3m / s. Under the condition of equipment operation, the buffer powder is evenly sprinkled in through the feeding port, and the buffer layer powder is adsorbed by the surface adhesion of the core particles. The coating time is 15-20 minutes to ensure that the particle surface is completely covered by the buffer layer.

[0020] It should be noted that, in step S3, the preparation method of the nano-coating agent includes the following steps: (1) Prepare solvent: Prepare a 1-2% (v / v) aqueous solution of glacial acetic acid and adjust the pH to 4.0-4.5 using a pH meter.

[0021] (2) Phase separation and dispersion: ①Preparation of Phase A (Organic Phase - Film-forming Phase): Place 78-82% acidic solvent into a high-speed shear press, add biopolyester, set the shear rate to 9000-11000 r / min, and disperse for 8-12 minutes; Then add polysaccharides and their derivatives, adjust the stirring speed to 480-520 r / min, and stir for 18-22 min until completely dissolved or uniformly dispersed to form phase A (organic phase).

[0022] ②Preparation of phase B (aqueous phase-crosslinked phase): Take 18-22% acidic solvent, add natural minerals, and disperse for 13-17 minutes at a shear rate of 10000-14000 r / min. Add sodium tripolyphosphate at a mass concentration of 1-3%, and stir for 8-12 minutes until completely dissolved to form phase B (aqueous phase).

[0023] ③ Composite crosslinking: Under high-speed shearing conditions, phase B is slowly added dropwise to phase A at a rate of 0.8-1.2 mL / min, and shearing continues for 3-7 min after the addition is complete. During this process, positively charged polysaccharides and their derivatives undergo ionic cross-linking with negatively charged sodium tripolyphosphate to form a nanogel, which simultaneously encapsulates and fixes the biopolyester and natural mineral layers, ultimately yielding a homogeneous, stable, slightly viscous, milky-white suspension, namely the nanocoating agent.

[0024] It should be noted that in step S3, after the coating process is completed, the fluidized bed temperature is raised to 80-85℃ and kept at that temperature for 28-32 minutes to promote the cross-linking reaction between the nanomaterials and the composite emulsion, forming a dense network protective layer. By observing the membrane structure, it is ensured that there are no pores or cracks, achieving high temperature resistance (above 180℃) and salt resistance. Then, the nanofilm is continuously fluidized and dried at 38-42℃ for 10-15 minutes to completely solidify and shape it. The particles are cooled to room temperature and sieved again to remove any possible fragments or adhering particles. Finally, the particles are sealed and packaged with materials with good barrier properties, such as aluminum foil bags, to prevent moisture absorption.

[0025] Thirdly, the present invention provides an application of the above-mentioned DMPP nanomaterial coated granules or the DMPP nanomaterial coated granules prepared by the above-mentioned preparation method in fertilizers.

[0026] The technical solution of this invention has the following advantages: 1. The present invention provides a DMPP nanomaterial coated particle agent, comprising the following raw materials in parts by weight: 50-65 parts of 3,4-dimethylpyrazole phosphate (DMPP), 15-20 parts of stabilizer, 5-10 parts of buffer, and 15-20 parts of nano-coating agent; wherein the stabilizer comprises bio-derived functional polysaccharides, organic acids, and cyclodextrin. This invention improves the stability of DMPP by combining it with a stabilizer. Then, a nano-coating agent is used to form a high-temperature resistant (temperature resistance increased to over 180℃) and salt-resistant mesh layer on the outside of the DMPP, further enhancing its high-temperature and salt resistance. This effectively solves the problem of DMPP technical material's inability to withstand high temperatures and saline-alkali conditions. The formed nano-coating structure enables the slow release of DMPP, extending its shelf life. This reduces the high-temperature decomposition rate of DMPP in fertilizers containing this granule to 5%-9%, extending the shelf life to over 2 years and the half-life to a maximum of 3 years. This solves the problem of easy decomposition of DMPP and greatly improves the fertilizer's utilization efficiency and storage performance. The buffer in this invention reduces the damage to the core components caused by mechanical shock during processing and storage, and allows for the slow release of the core raw materials after application. The DMPP nanomaterial-coated granules provided by this invention can be widely used in ammonium nitrogen fertilizers and amide nitrogen fertilizers, requiring only a small amount and showing significant effects, demonstrating promising application prospects.

[0027] 2. The preparation method of DMPP nanomaterial coated particles provided by this invention is simple, easy to control, and suitable for industrial production. In step S1, a stabilizer composed of bio-derived functional polysaccharides, organic acids, and cyclodextrin is mixed with DMPP raw material, and cross-linked with calcium chloride and heat-treated to form core particles with high mechanical strength. At the same time, the molecular structure of DMPP is locked through hydrogen bonds and coordination bonds to reduce its free activity and avoid hydrolysis and oxidation. In step S2, a mixed powder of diatomaceous earth and bentonite is used to coat the core particles in a fluidized bed to form a buffer layer. This layer not only physically blocks mechanical collisions and water and oxygen, but also uses the functional groups on the surface of the buffer layer to regulate the interfacial properties of the particles, laying a solid foundation for subsequent nano-coating. In step S3, coating treatment and thermal curing are carried out to promote the cross-linking reaction between the coated buffer layer particles and the nano-coating agent, forming a dense network protective layer. Subsequent drying can completely solidify and shape the nanofilm, and sieving can remove any fragments or adhering particles that may be generated.

[0028] 3. The DMPP nanomaterial-coated granules provided by this invention effectively control nitrate nitrogen formation when applied to nitrogen fertilizers, directly reducing the risk of nitrate pollution to groundwater and rivers. Furthermore, by inhibiting nitrification, it indirectly and significantly reduces the emission of potent greenhouse gases (such as nitrous oxide) generated during denitrification. Detailed Implementation

[0029] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0030] Unless otherwise defined, 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 belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having” and any variations thereof in the text of this application are intended to cover non-exclusive inclusion.

[0031] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers from a to b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein, and "0-5" is merely a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that the parameter can be, for example, integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0032] In the description of the embodiments of this application, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0033] In the description of the embodiments of this application, the term "at least one" refers to one or more (including two).

[0034] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0035] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0036] The DMPP used is a commercially available product; The phosphorus-activated emulsifier used was purchased from TIMA emulsifier of Henan Fulian Biotechnology Co., Ltd., with an effective ingredient content of 20%.

[0037] Example 1 This embodiment provides a DMPP nanomaterial-coated particulate agent. The specific steps and parameter settings are as follows (by weight): S1. Mix 55 parts of DMPP and 20 parts of stabilizer (β-glucan, methyl-β-cyclodextrin, hydroxypropyl starch, citric acid, and phosphorus-activated emulsifier (TIMA emulsifier with 20% effective ingredient content) in a mass ratio of 3:4:4:3:6). Add 0.8% of the mass of the mixture to a crosslinking agent solution (calcium chloride solution with a mass concentration of 2%), stir for 12 min to carry out the crosslinking reaction, and then heat to 42℃ and stir for 1 h to obtain the core particles. S2, put the core particles into the fluidized bed coating machine, set the inlet air temperature to 38℃ and the fluidization air velocity to 2m / s. Under the running state of the equipment, 6 parts of buffer agent (mass ratio of diatomaceous earth to bentonite = 2:4) are evenly sprinkled in through the feeding port and coated for 18 minutes to obtain buffer layer coated particles. S3, the buffer layer coated particles are placed again in the fluidized bed coating machine, and 19 parts of nano-coating agent (mass ratio of polymeric chitosan nanoparticles, polylactic acid nanofibers, and nano-montmorillonite = 8:5:3) are atomized through a spray gun and uniformly sprayed onto the surface of the fluidized particles under the condition of an inlet air temperature of 45°C for coating treatment. Then, the fluidized bed temperature is raised to 83°C and kept at that temperature for 30 minutes for thermosetting. Then, it is continuously fluidized and dried at 40°C for 15 minutes, cooled to room temperature, and sieved to obtain the DMPP nanomaterial coated particles.

[0038] Example 2 This embodiment provides a DMPP nanomaterial-coated particulate agent. The specific steps and parameter settings are as follows (by weight): S1. Mix 60 parts of DMPP and 16 parts of stabilizer (hydroxypropyl-β-cyclodextrin, chitosan oligosaccharide, sodium alginate, phytic acid, citric acid, and phosphorus-activated emulsifier (TIMA emulsifier with 20% effective ingredient content) in a mass ratio of 3:3:3:2:1:4), then add 0.8% of the mass of the mixture to a crosslinking agent solution (calcium chloride solution with a mass concentration of 2%), stir for 12 min to carry out the crosslinking reaction, then heat to 42℃, keep warm and stir for 1 h to obtain the core particles; S2, put the core particles into the fluidized bed coating machine, set the inlet air temperature to 38℃ and the fluidization air velocity to 2m / s. Under the running state of the equipment, 8 parts of buffer agent (mass ratio of diatomaceous earth to bentonite = 4:4) are evenly sprinkled in through the feeding port and coated for 18 minutes to obtain buffer layer coated particles. S3, the buffer layer coated particles are placed again in the fluidized bed coating machine, and 16 parts of nano-coating agent (mass ratio of polymeric chitosan nanoparticles, polylactic acid nanofibers, and nano-montmorillonite = 8:5:3) are atomized through a spray gun and uniformly sprayed onto the surface of the fluidized particles under the condition of an inlet air temperature of 45°C for coating treatment. Then, the fluidized bed temperature is raised to 83°C and kept at that temperature for 30 minutes for thermosetting. Then, the particles are continuously fluidized and dried at 40°C for 15 minutes. After cooling to room temperature, they are sieved to obtain the DMPP nanomaterial coated particles.

[0039] Example 3 This embodiment provides a DMPP nanomaterial-coated particulate agent. The specific steps and parameter settings are as follows (by weight): S1. Mix 65 parts of DMPP and 15 parts of stabilizer (phosphorus activated emulsifier (TIMA emulsifier with 20% effective ingredient content), fucoidan oligosaccharide, β-cyclodextrin, fulvic acid, and sodium carboxymethyl cellulose in a mass ratio of 5:4:2:2:2), add 0.8% of the mass of the mixture of crosslinking agent solution (calcium chloride solution with a mass concentration of 2%), stir for 12 min to carry out crosslinking reaction, then heat to 42℃, keep warm and stir for 1 h to carry out heat treatment to obtain core particles; S2, put the core particles into the fluidized bed coating machine, set the inlet air temperature to 38℃ and the fluidization air velocity to 2m / s. Under the running state of the equipment, 5 parts of buffer agent (mass ratio of diatomaceous earth to bentonite = 2:3) are evenly sprinkled in through the feeding port and coated for 18 minutes to obtain buffer layer coated particles. S3. Place the buffer layer coated particles back into the fluidized bed coating machine. Atomize 15 parts of nano-coating agent (brown seaweed cellulose nanofiber, polylactic acid nanofiber, and nano zeolite in a mass ratio of 8:4:3) through a spray gun. Under the condition of an inlet air temperature of 45°C, spray the agent evenly onto the surface of the fluidized particles for coating treatment. Then, raise the fluidized bed temperature to 83°C and keep it at that temperature for 30 minutes for thermosetting. Then, continue fluidizing and drying at 40°C for 15 minutes. After cooling to room temperature, sieve to obtain the DMPP nanomaterial coated particles.

[0040] Example 4 This embodiment provides a DMPP nanomaterial-coated particulate agent. The specific steps and parameter settings are as follows (by weight): S1, 55 parts of DMPP and 15 parts of stabilizer (chitosan oligosaccharide, methyl-β-cyclodextrin, citric acid, hydroxypropyl starch, phosphorus-activated emulsifier (TIMA emulsifier with 20% effective ingredient content), sodium carboxymethyl cellulose in a mass ratio of 3:2:2:2:4:1) were mixed, and then 0.8% of the mass of the mixture was added to a crosslinking agent solution (calcium chloride solution with a mass concentration of 2%). The mixture was stirred for 12 min to carry out the crosslinking reaction, and then the temperature was raised to 42℃ and kept at the temperature and stirred for 1 h to carry out heat treatment to obtain core particles; S2, put the core particles into the fluidized bed coating machine, set the inlet air temperature to 38℃ and the fluidization air velocity to 2m / s. Under the running state of the equipment, 10 parts of buffer agent (mass ratio of diatomaceous earth to bentonite = 4:6) are evenly sprinkled in through the feeding port and coated for 18 minutes to obtain buffer layer coated particles. S3. The buffer layer coated particles are placed again in a fluidized bed coating machine. 20 parts of nano-coating agent (starch and starch derivatives (sodium carboxymethyl starch, hydroxypropyl starch phosphate, starch-g-polyacrylic acid graft copolymer, phosphate starch mass ratio = 3:2:1:1), 12% polyhydroxy fatty acid ester nano-aqueous suspension, nano-montmorillonite mass ratio = 7:7:6) are atomized through a spray gun and uniformly sprayed onto the surface of the fluidized particles under an inlet air temperature of 45°C for coating treatment. Then, the fluidized bed temperature is raised to 83°C and kept at that temperature for 30 minutes for thermosetting. Then, the particles are continuously fluidized and dried at 40°C for 15 minutes. After cooling to room temperature, the particles are sieved to obtain the DMPP nanomaterial coated particles.

[0041] Example 5 This embodiment provides a DMPP nanomaterial-coated particulate agent. The specific steps and parameter settings are as follows (by weight): S1. Mix 60 parts of DMPP and 15 parts of stabilizer (β-glucan, methyl-β-cyclodextrin, hydroxypropyl starch, citric acid, and phosphorus-activated emulsifier (TIMA emulsifier with 20% effective ingredient content) in a mass ratio of 3:4:1:2:5). Add 0.8% of the mass of the mixture to a crosslinking agent solution (calcium chloride solution with a mass concentration of 2%), stir for 12 min to carry out the crosslinking reaction, and then heat to 42℃ and keep stirring for 1 h to obtain the core particles. S2, put the core particles into the fluidized bed coating machine, set the inlet air temperature to 38℃ and the fluidization air velocity to 2m / s. Under the running state of the equipment, 6 parts of buffer agent (mass ratio of diatomaceous earth to bentonite = 2:4) are evenly sprinkled in through the feeding port and coated for 18 minutes to obtain buffer layer coated particles. S3, the buffer layer coated particles are placed again in a fluidized bed coating machine. 19 parts of nano-coating agent (chitin nanofibers, 9% polyhydroxy fatty acid ester nano-aqueous suspension, and nano-kaolin in a mass ratio of 10:5:4) are atomized through a spray gun and uniformly sprayed onto the surface of the fluidized particles under an inlet air temperature of 45°C for coating treatment. Then, the fluidized bed temperature is raised to 83°C and kept at that temperature for 30 minutes for thermosetting. Then, the particles are continuously fluidized and dried at 40°C for 15 minutes. After cooling to room temperature, they are sieved to obtain the DMPP nanomaterial coated particles.

[0042] Example 6 This embodiment provides a DMPP nanomaterial-coated particulate agent. The specific steps and parameter settings are as follows (by weight): S1. Mix 60 parts of DMPP and 15 parts of stabilizer (phosphorus-activated emulsifier (TIMA emulsifier with 20% effective ingredient content), chitosan oligosaccharide, methyl-β-cyclodextrin, citric acid, hydroxypropyl starch, and sodium carboxymethyl cellulose in a mass ratio of 5:3:3:2:1:1), add 0.8% of the mass of the mixture to a crosslinking agent solution (calcium chloride solution with a mass concentration of 1.8%), stir for 12 min to carry out the crosslinking reaction, then heat to 42℃, keep warm and stir for 1 h to obtain the core particles; S2, put the core particles into the fluidized bed coating machine, set the inlet air temperature to 38℃ and the fluidization air velocity to 2m / s. Under the running state of the equipment, 10 parts of buffer agent (mass ratio of diatomaceous earth to bentonite = 4:6) are evenly sprinkled in through the feeding port and coated for 18 minutes to obtain buffer layer coated particles. S3, the buffer layer coated particles are placed again in a fluidized bed coating machine. 15 parts of nano-coating agent (starch and starch derivatives (sodium carboxymethyl starch, hydroxypropyl starch phosphate, starch-g-polyacrylic acid graft copolymer, phosphate starch mass ratio = 3:2:1:1), 10% polyhydroxy fatty acid ester nano-aqueous suspension, nano-montmorillonite mass ratio = 7:5:3) are atomized through a spray gun and uniformly sprayed onto the surface of the fluidized particles under an inlet air temperature of 45℃ for coating treatment. Then, the fluidized bed temperature is raised to 83℃ and kept at that temperature for 30 minutes for thermosetting. Then, it is continuously fluidized and dried at 40℃ for 15 minutes, cooled to room temperature, and sieved to obtain the DMPP nanomaterial coated particles.

[0043] Example 7 This embodiment provides a DMPP nanomaterial-coated particulate agent. The specific steps and parameter settings are as follows (by weight): S1. Mix 50 parts of DMPP and 20 parts of stabilizer (β-glucan, methyl-β-cyclodextrin, hydroxypropyl starch, citric acid, and phosphorus-activated emulsifier (TIMA emulsifier with 20% effective ingredient content) in a mass ratio of 2:5:0:4:3). Add 1% of the mass of the mixture to a crosslinking agent solution (0.8% calcium nitrate solution). Stir for 10 minutes to carry out the crosslinking reaction. Then heat the mixture to 45°C and keep it at that temperature for 1 hour to carry out heat treatment to obtain the core particles. S2, put the core particles into the fluidized bed coating machine, set the inlet air temperature to 40℃ and the fluidization air velocity to 2m / s. Under the running state of the equipment, 5 parts of buffer agent (mass ratio of diatomaceous earth to bentonite = 2:4) are evenly sprinkled in through the feeding port and coated for 15 minutes to obtain buffer layer coated particles. S3, the buffer layer coated particles are placed again in the fluidized bed coating machine, and 20 parts of nano-coating agent (mass ratio of polymeric chitosan nanoparticles, polylactic acid nanofibers, and nano-montmorillonite = 8:5:3) are atomized through a spray gun and uniformly sprayed onto the surface of the fluidized particles under the condition of an air inlet temperature of 50°C for coating treatment. Then, the fluidized bed temperature is raised to 80°C and kept at that temperature for 35 minutes for thermosetting. Then, the particles are continuously fluidized and dried at 40°C for 15 minutes. After cooling to room temperature, they are sieved to obtain the DMPP nanomaterial coated particles.

[0044] Example 8 This embodiment provides a DMPP nanomaterial-coated particulate agent. The specific steps and parameter settings are as follows (by weight): S1. Mix 65 parts of DMPP and 15 parts of stabilizer (β-glucan, methyl-β-cyclodextrin, hydroxypropyl starch, citric acid, and phosphorus-activated emulsifier (TIMA emulsifier with 20% active ingredient content) in a mass ratio of 7:1:5:1:7). Add 0.5% of the mass of the mixture to a crosslinking agent solution (polyethylene glycol solution with a mass concentration of 10.2%), stir for 15 min to carry out the crosslinking reaction, and then heat to 40℃ and keep stirring for 1.5 h to obtain the core particles. S2, put the core particles into the fluidized bed coating machine, set the inlet air temperature to 35℃ and the fluidization air velocity to 2m / s. Under the running state of the equipment, 10 parts of buffer agent (mass ratio of diatomaceous earth to bentonite = 2:4) are evenly sprinkled in through the feeding port and coated for 20 minutes to obtain buffer layer coated particles. S3, the buffer layer coated particles are placed again in the fluidized bed coating machine, and 15 parts of nano-coating agent (mass ratio of polymeric chitosan nanoparticles, polylactic acid nanofibers, and nano-montmorillonite = 8:5:3) are atomized through a spray gun and uniformly sprayed onto the surface of the fluidized particles under the condition of an air inlet temperature of 40°C for coating treatment. Then, the fluidized bed temperature is raised to 85°C and kept at that temperature for 25 minutes for thermosetting. Then, the particles are continuously fluidized and dried at 40°C for 15 minutes, cooled to room temperature, and sieved to obtain the DMPP nanomaterial coated particles.

[0045] Comparative Example 1 This comparative example provides a DMPP nanomaterial-coated granule, which differs from Example 4 only in that, by weight, the DMPP nanomaterial-coated granule consists of 55 parts DMPP, 15 parts stabilizer (borate ratio of boric acid to lignin sulfonate = 12:8), 10 parts buffer, and 20 parts nano-coating agent.

[0046] Comparative Example 2 This comparative example provides a DMPP nanomaterial-coated particulate agent, which differs from Example 4 only in that the stabilizer is replaced with an equal mass of DMPP.

[0047] Comparative Example 3 This comparative example provides a DMPP nanomaterial-coated particle agent, which differs from Example 4 only in that the raw materials do not include a nano-coating agent and step S3 is not performed.

[0048] Comparative Example 4 This comparative example provides a DMPP nanomaterial-coated particulate agent, which differs from Example 4 only in that the raw materials do not include a buffer and step S2 is not performed.

[0049] Comparative Example 5 This comparative example provides a DMPP nanomaterial-coated granule agent, which differs from Example 2 only in that the stabilizer does not include organic acids, and the mass ratio of hydroxypropyl-β-cyclodextrin, chitosan oligosaccharide, sodium alginate, and phosphorus-activated emulsifier (TIMA emulsifier with an effective ingredient content of 20%) is 3:3:3:4.

[0050] Comparative Example 6 This comparative example provides a DMPP nanomaterial-coated granule agent, which differs from Example 2 only in that the stabilizer does not include cyclodextrin, and the mass ratio of chitosan oligosaccharide, sodium alginate, phytic acid, citric acid, and phosphorus-activated emulsifier (TIMA emulsifier with an effective ingredient content of 20%) is 3:3:2:1:4.

[0051] Comparative Example 7 This comparative example provides a DMPP nanomaterial-coated granule agent, which differs from Example 2 only in that the stabilizer does not include bio-derived functional polysaccharides, and the mass ratio of hydroxypropyl-β-cyclodextrin, sodium alginate, phytic acid, citric acid, and phosphorus-activated emulsifier (TIMA emulsifier with an effective ingredient content of 20%) is 3:3:2:1:4.

[0052] Comparative Example 8 This comparative example provides a DMPP nanomaterial-coated particulate agent, which differs from Example 4 only in that the phosphorus-activated emulsifier is replaced with an equal mass of chitosan oligosaccharide.

[0053] Comparative Example 9 This comparative example provides a DMPP nanomaterial-coated granule, which differs from Example 2 only in that, by weight, the DMPP nanomaterial-coated granule consists of 60 parts DMPP, 16 parts stabilizer (hydroxypropyl-β-cyclodextrin, chitosan oligosaccharide, sodium alginate, phytic acid, citric acid, and phosphorus-activated emulsifier in a mass ratio of 3:3:3:2:1:4), 8 parts buffer, and 23 parts nano-coating agent (polymerized chitosan nanoparticles, brown seaweed cellulose nanofibers, polylactic acid nanofibers, and nano-montmorillonite in a mass ratio of 9:6:5:3).

[0054] Comparative Example 10 This comparative example provides a DMPP nanomaterial-coated granule, which differs from Example 2 only in that, by weight, the DMPP nanomaterial-coated granule consists of 60 parts DMPP, 16 parts stabilizer, 15 parts buffer, and 16 parts nano-coating agent.

[0055] Comparative Example 11 This comparative example provides a DMPP nanomaterial-coated granule, which differs from Example 2 only in that, by weight, the DMPP nanomaterial-coated granule consists of 60 parts DMPP, 25 parts stabilizer (hydroxypropyl-β-cyclodextrin, chitosan oligosaccharide, sodium alginate, phytic acid, citric acid, and phosphorus-activated emulsifier in a mass ratio of 7:5:4:2:1:6), 8 parts buffer, and 16 parts nano-coating agent.

[0056] Experimental Example 1 The performance of the DMPP nanoparticles obtained in each embodiment and comparative example was tested, and the test indicators included: (1) High-temperature decomposition rate The following formula is used to calculate the proportion of DMPP lost due to thermal decomposition under simulated extreme high-temperature conditions (200℃, held for 2 hours): High-temperature decomposition rate (%) = [(initial DMPP content - residual DMPP after high temperature) / initial DMPP content] × 100%.

[0057] The high-temperature resistance test aimed to withstand temperatures ≥180℃. 2.0~4.0mm particles (10.0g / sample, 3 parallel samples) from the examples / comparative examples and an uncoated DMPP blank control were heated in a muffle furnace at 180℃ / 200℃ / 220℃ for 2 hours and then naturally cooled. The particle integrity rate (mass on a 2.0mm sieve / initial mass × 100%) and DMPP content retention rate were then measured (using high-performance liquid chromatography according to GB / T35104-2017).

[0058] (2) Shelf life By using short-term accelerated storage (a constant temperature and humidity chamber at 70°C and 75% relative humidity), the residual amount of DMPP is measured periodically. The time when the residual amount drops to 80% of the initial content is the shelf life. Accelerated storage requires conversion to room temperature shelf life using the "Arrhenius equation".

[0059] (3) DMPP half-life The coated particles were placed in a simulated accelerated degradation environment (e.g., high temperature and high humidity, i.e., temperature 60℃ and relative humidity 90%), and the DMPP residue was determined using high performance liquid chromatography according to GB / T35104-2017. The degradation curve was fitted by a first-order kinetic equation, and the half-life was calculated. First-order dynamic equation: ; half life: ; Where C represents the amount of DMPP remaining during the experimental sampling; C0 represents the initial content of DMPP; k is the degradation rate constant; t represents time.

[0060] Salt tolerance tests simulated a saline-alkali soil environment. 2.0–4.0 mm particles (5.0 g / sample, 4 parallel samples) from the examples / comparative examples and an uncoated DMPP blank control were soaked in 200 mL of 0.5% / 1.0% / 2.0% NaCl at 5°C with shaking for 7 days (deionized water was used as a control). The coating integrity rate (mass of intact coated particles after drying / initial mass × 100%) and DMPP dissolution rate (HPLC supernatant dissolution amount / total content × 100%) were then measured. Specific test results are shown in the table below. Table 1 Performance Test Data

[0061] This invention optimizes the component ratio and process parameters of "DMPP-stabilizer-buffer layer-nano-coating" to construct a multi-layer coating system that combines high temperature resistance, salt resistance, and long-lasting sustained release, thus solving the technical pain points of poor thermal stability, short shelf life, and weak applicability to saline-alkali environments of DMPP technical material. The comprehensive performance of the embodiment (high temperature decomposition rate, shelf life, half-life, high temperature resistance, and salt resistance dissolution rate) is significantly better than that of the comparative example, providing technical support for the application of DMPP in extreme environments (high temperature storage, saline-alkali environments).

[0062] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A DMPP nanomaterial-coated granule agent, characterized in that, The raw materials include the following parts by weight: 50-65 parts of 3,4-dimethylpyrazole phosphate, 15-20 parts of stabilizer, 5-10 parts of buffer, and 15-20 parts of nano-coating agent; The stabilizers include bio-derived functional polysaccharides, organic acids, cyclodextrins, and phosphorus-activated emulsifiers.

2. The DMPP nanomaterial-coated particulate agent according to claim 1, characterized in that, The mass ratio of bio-derived functional polysaccharides, organic acids, cyclodextrins, and phosphorus-activated emulsifiers in the stabilizer is (2-7):(1-4):(1-5):(3-7); And / or, the bio-derived functional polysaccharide includes at least one of chitosan oligosaccharide, β-glucan, and seaweed extract; And / or, the organic acid includes at least one of phytic acid, citric acid, and fulvic acid; And / or, the cyclodextrin includes at least one of β-cyclodextrin, hydroxypropyl-β-cyclodextrin, and methyl-β-cyclodextrin.

3. The DMPP nanomaterial-coated particulate agent according to claim 1 or 2, characterized in that, The stabilizer also includes natural polymer derivatives; Optionally, the natural polymer derivative includes at least one of starch derivatives and cellulose derivatives; And / or, the mass ratio of the bio-derived functional polysaccharide to the natural polymer derivative in the stabilizer is (2-7):(0-5).

4. The DMPP nanomaterial-coated particulate agent according to any one of claims 1-3, characterized in that, The buffering agent includes diatomaceous earth and bentonite.

5. The DMPP nanomaterial-coated particulate agent according to any one of claims 1-4, characterized in that, The nano-coating agent includes at least one of polysaccharides and their derivatives, biopolyesters, and natural minerals. And / or, the nanocoating agent further includes an acidic solvent and an ionic crosslinking agent.

6. A method for preparing a DMPP nanomaterial-coated particulate agent according to any one of claims 1-5, characterized in that, Includes the following steps: S1, after mixing the stabilizer and 3,4-dimethylpyrazole phosphate, a crosslinking agent solution is added to carry out a crosslinking reaction, followed by heat treatment to obtain core particles; S2, the buffer and core particles are mixed and coated to obtain buffer-coated particles; S3, mix the nano-coating agent and the buffer layer coating particles for coating treatment, and then heat-cur to obtain the DMPP nanomaterial coated particles.

7. The preparation method according to claim 6, characterized in that, The crosslinking reaction takes 10-15 minutes; And / or, the mass of the crosslinking agent solution accounts for 0.5-1.0% of the total mass of the stabilizer and 3,4-dimethylpyrazole phosphate mixture; And / or, the crosslinking agent solution includes at least one of calcium chloride solution, calcium nitrate solution, and polyethylene glycol solution; Optionally, the mass concentration of the calcium chloride solution is 1.5%-3.0%; Optionally, the mass concentration of the calcium nitrate solution is 0.8% to 1.2%. Optionally, the mass concentration of the polyethylene glycol solution is 9.8%-10.2%; And / or, the heat treatment temperature is 40-45℃ and the time is 1-1.5h.

8. The preparation method according to claim 6 or 7, characterized in that, The coating process is carried out at a temperature of 35-40℃ for 15-20 minutes.

9. The preparation method according to any one of claims 6-8, characterized in that, The coating treatment temperature is 40-50℃; And / or, the thermosetting temperature is 80-85℃ and the time is 25-35min.

10. The application of a DMPP nanomaterial-coated granule according to any one of claims 1-5 or a DMPP nanomaterial-coated granule prepared by the preparation method according to any one of claims 6-9 in fertilizer.

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