Sustained-release composite material, method for preparing the same, and use thereof

Abstract

The slow-release composite material is composed of a first inorganic layer and a second inorganic layer which are compounded by an organic substance as a binder. The slow-release composite material provided by the present application uses green and environment-friendly materials as raw materials, has no obvious residue in soil, and realizes the environmental friendliness. As a packaging material, the composite material can coat the inhibitor in the composite material, inhibit the loss of the effective component (such as chloronicotinyl) with high volatility, and improve the storage stability.

Description

Technical Field

[0001] This invention relates to a composite material, and more particularly to a material composed of inorganic compounds, which has a slow-release effect. When used as a capsule material to encapsulate active substances, it can significantly delay the release of active substances and is suitable for improving the fertilizer efficiency of chemical fertilizers. Background Technology

[0002] Sustained release refers to the use of technology to prolong the rate of dissolution (or volatilization) of a substance. Commonly used in pharmaceutical formulations, it involves encapsulating a compound in a biodegradable material. As the material hydrolyzes or undergoes enzymatic hydrolysis, the compound is gradually released, thus slowing the drug release rate, reducing the rate of absorption into the body, extending the dosing time, improving patient compliance, maintaining appropriate blood drug concentrations within the therapeutic window, reducing drug toxicity and side effects, and ultimately achieving better therapeutic effects. Materials suitable for achieving sustained release are typically organic polymers, such as liposomes, PLGA, and chitosan.

[0003] Currently, agricultural production relies heavily on chemical fertilizers, with the overall utilization rate of nitrogen fertilizer being only 30%. 35% is lost through leaching, volatilization, and surface runoff, while approximately 30% is decomposed and consumed by microorganisms. For example, after urea is applied to the soil, it is quickly converted into ammonium nitrogen by urease in the soil. In high-pH soils, ammonium nitrogen is converted into ammonia gas and volatilized. Certain bacteria in the soil can cause ammonium nitrogen to undergo nitrification / denitrification, converting it into nitrate or nitrite nitrogen. Nitrate nitrogen is easily leached from the soil, while nitrite nitrogen is lost in the form of nitrogen oxides, resulting in a large loss of nitrogen fertilizer, reducing the utilization rate of fertilizer nitrogen, causing a huge waste of resources, and also leading to groundwater and soil non-point source pollution, contributing to the greenhouse gas effect and eutrophication of water bodies.

[0004] CN101434502B discloses a synergistic slow-release nitrogen fertilizer and its preparation method, describing a technique for obtaining a compound nitrogen fertilizer by adding biochemical inhibitors (urease inhibitors and nitrification inhibitors) and synergists (polyaspartic acid) to urea nitrogen fertilizer. Specifically, the synergistic nitrogen fertilizer is obtained by directly mixing the above-mentioned additive mixture with molten urea nitrogen fertilizer using mechanical or manual mixing methods. The content of the biochemical inhibitors varies from 0.5% to 10%. This process is complex and requires precise control of the mixing process. Furthermore, the biochemical additives are easily lost due to high temperature volatilization, and there is a lack of a slow-release protection mechanism for the biochemical additives, making their effective components easily lost during storage.

[0005] CN101891543A discloses a method for preparing granular compound fertilizer, describing the use of attapulgite clay, urea, and potassium dihydrogen phosphate as the fertilizer core, cross-linked sodium alginate (with CaCl2 as the cross-linking agent) as the fertilizer core film, and water-absorbing resin as the fertilizer outer coating. While this process achieves some degree of slow-release of fertilizer, it cannot effectively mitigate the volatilization of ammonium nitrogen or the nitrification-denitrification leaching loss of ammonium nitrogen in the soil, thus failing to improve nitrogen utilization. Furthermore, the use of high-cost materials such as sodium alginate results in a high product price.

[0006] CN101434504B discloses an enhanced slow-release nitrogen fertilizer and its preparation method, describing a technique for adding two biochemical inhibitors (urease inhibitor and nitrification inhibitor), an enhancer (polyaspartic acid), and additives (humic acid, diatomaceous earth, etc.) to urea nitrogen fertilizer. One method involves using a fluidized bed process to prepare a suspension of the aforementioned additives and organic solvents, which is then sprayed onto the surface of urea fertilizer granules. The other method involves mixing the mixture of the aforementioned additives with molten urea nitrogen fertilizer using mechanical or manual mixing methods to obtain the enhanced nitrogen fertilizer. The content of the biochemical inhibitors varies from 0.1% to 10%. Both processes are complex, and the biochemical additives are easily lost during high-temperature processing. Furthermore, there is a lack of suitable slow-release protection mechanisms, and the effective components are easily lost during storage.

[0007] CN102557814 and CN102557838A both disclose a multifunctional slow-release urea fertilizer and its preparation method. They describe a process where an synergist (polyaspartic acid), a slow-release agent (urease inhibitor and nitrification inhibitor), and some crop growth trace elements are mechanically mixed into a suspension, which is then directly added to an existing high-tower granulation process for large-particle urea, and mixed with molten urea slurry for granulation. The content of biochemical inhibitors varies from 0.1% to 10%. This process is complex, and biochemical additives are easily lost due to high temperatures during processing. Furthermore, it lacks a suitable slow-release protection mechanism, and its effective components are easily lost during storage.

[0008] CN102584480B and CN102617254A disclose a specific formulation and process for preparing a latex suspension containing 2-chloro-6-trichloromethylpyridine (nitration inhibitor) for enhancing the efficiency of nitrogen fertilizer. This latex suspension can be sprayed onto the surface of nitrogen fertilizer granules to obtain a compound fertilizer containing a solid urea / amino nitrogen fertilizer with a nitration inhibitor. However, products prepared by this granule surface spraying method lack a suitable slow-release protection mechanism for the nitration inhibitor, and their active ingredients are easily lost during storage.

[0009] CN103772074A discloses a fluidized bed coating process that involves spraying one or two nitrification inhibitors, namely dicyandiamide and 2-chloro-6-trichloromethylpyridine, onto the core surface of a nitrogen-phosphorus-potassium compound fertilizer using a polyethylene wax-based coating material at 70-100°C. Finally, a sodium polyacrylate water-retaining agent is coated onto the core using a rolling adhesion method, resulting in a long-lasting sweet potato fertilizer with a three-layer core-shell structure. However, in this patented technology, the nitrification inhibitors are prone to loss during high-temperature production, and the water-retaining agent coating can easily cause problems with storage stability.

[0010] CN103524272A discloses a technique for using a spray bed coating machine to coat solid 2-chloro-6-trichloromethylpyridine (nitrification inhibitor) and a coating agent onto the surface of a nitrogen-phosphorus-potassium compound granular fertilizer at 80°C, and adding talc as an anti-sticking agent to obtain a compound fertilizer containing 0.2%~0.4% 2-chloro-6-trichloromethylpyridine. However, talc cannot form a dense slow-release film and cannot prevent the volatilization of chloropyridine. Summary of the Invention

[0011] One object of the present invention is to provide a slow-release composite material composed of two layers of inorganic materials, which enables the substances encapsulated in the material to be released in a slow-release manner.

[0012] Another objective of this invention is to provide a slow-release composite material as a packaging material for coating fertilizers, which can effectively improve the fertilizer efficiency.

[0013] Another object of the present invention is to provide a slow-release composite material as a packaging material for coating regulators, thereby improving the storage stability of the regulators.

[0014] Another objective of this invention is to provide a slow-release composite material as a packaging material for coating nitrogen fertilizer, thereby comprehensively reducing ammonia volatilization, increasing rice yield, and improving the nitrogen fertilizer effect on the aboveground parts.

[0015] Another object of the present invention is to provide a method for preparing a sustained-release composite material.

[0016] The present invention provides a slow-release composite material, which is composed of an organic compound that combines a first inorganic layer and a second inorganic layer.

[0017] Organic materials, such as, but not limited to, one or more of sucrose, agar, urea, chitosan, modified cellulose ether, starch, guar gum, polyvinyl alcohol (PVA), acrylic emulsion (solid content e.g., 40%~50%), and waterborne polyurethane, are used as binders to bond the first and second inorganic layers. Due to the different organic materials used or the surface condition of the inorganic layers, there may not be clear boundaries between the organic material and the first inorganic layer, or between the organic material and the second inorganic layer, making it easy to distinguish between them.

[0018] The materials used in the first inorganic layer include, but are not limited to, one or two of the following: silica, kaolin, talc, attapulgite, diatomaceous earth, clay, sulfur powder, and calcium magnesium phosphate fertilizer.

[0019] The materials used in the second inorganic layer include, but are not limited to, one or two of the following: silica, kaolin, talc, attapulgite, diatomaceous earth, clay, sulfur powder, and calcium magnesium phosphate fertilizer.

[0020] The first inorganic layer uses the same materials as the second inorganic layer.

[0021] The slow-release composite material provided by this invention is used as a packaging material in the manufacture of slow-release fertilizers. The slow-release composite material encapsulates fertilizers and regulators, achieving slow release of substances, improving fertilizer efficiency, and enhancing the storage stability of regulators.

[0022] A specific embodiment of manufacturing a slow-release fertilizer using the slow-release composite material provided by the present invention as packaging material, the slow-release fertilizer includes a slow-release composite material, a fertilizer and a regulator, the slow-release composite material is made into a capsule shape, including a capsule cavity, the fertilizer and the regulator are placed in the capsule cavity, the fertilizer is in the form of particles with a diameter of 0.1 mm to 10 mm, and the regulator is covered on the outside of the fertilizer.

[0023] Fertilizer granules are made from one or more of the following: nitrogen fertilizer (such as, but not limited to, urea, ammonium nitrate and ammonium sulfate), phosphate fertilizer (such as, but not limited to, ammonium phosphate, superphosphate, monoammonium phosphate and diammonium phosphate), potassium fertilizer (potassium sulfate and potassium chloride) and agricultural additives.

[0024] Agricultural additives, such as, but not limited to, calcium carbonate, clay, and compound micronutrient fertilizers (such as zinc sulfate, manganese sulfate, and ferrous sulfate). These additives are used alone or in combination in this invention.

[0025] By using the slow-release composite material provided by this invention as packaging material to encapsulate nitrogen fertilizer, the fertilizer effect period of urea (amide) nitrogen fertilizer is effectively extended, increasing the fertilizer effect period from 30 days to 60 days, and the total effective period of fertilizer reaches about 120 days.

[0026] Urease inhibitors are substances that inhibit urease activity in soil. They can prevent or inhibit the conversion of amide nitrogen in urea into ammonium hydroxide and ammonia for a certain period of time. They reduce ammonia volatilization and further nitrification by slowing down the hydrolysis rate of urea in the soil. N-(n-butyl)thiophosphrictriamide (nBPT) is one of the most effective soil urease inhibitors currently available. Studies have found that in well-aerated, non-acidic soils, nBPT can effectively reduce the volatilization of gaseous ammonia and also weaken the formation of nitrate nitrogen, thereby improving nitrogen use efficiency.

[0027] Nitrification inhibitors effectively suppress the activity of nitrifying / denitrifying bacteria in the soil, reducing the conversion of ammonium nitrogen to nitrite and nitrate nitrogen, and prolonging the retention time of ammonium nitrogen in the soil, thereby increasing the effective period of nitrogen fertilizer. Among all nitrification inhibitors, 2-chloro-6-trichloromethylpyridine (Nitrapyrin) has undergone rigorous laboratory toxicology tests, continuous field trials, and half-life testing, which have shown that it has a highly effective nitrification / denitrification inhibition effect while having no adverse effects on the soil environment. It is a safe and reliable nitrification inhibitor approved by the US EPA and is widely used in maize field production in North America. However, nitrapyrin has a high vapor pressure and is prone to sublimation above 70°C.

[0028] The slow-release composite material provided by this invention is used as packaging material to encapsulate regulators such as urease inhibitors and nitration inhibitors. After a 2-week accelerated heat storage test, the regulator content is still more than 80%, and the storage stability of the nitration inhibitor can reach two years, effectively improving the storage stability of the regulator.

[0029] Urease inhibitors include, but are not limited to, n-butylthiophosphoric triamine (nBPT), phenylphosphoric diamine, hydroquinone, quinone hydroquinone, and urea analogs (such as thiourea, phenylurea, etc.). These substances are used alone or in combination in this invention.

[0030] Nitrification inhibitors include, but are not limited to, 2-chloro-6-(trichlorotoluene)pyridine, amidothiourea, dicyandiamide, 2-methyl-4,6-bis(trichlorotoluene)triazine, 2-sulfathiazole, 3,4-dimethylpyrazole phosphate, 3,5-dimethylpyrazole, 3,5-dimethylpyrazole phosphate, 1-methylamino-3-methylpyrazole, 1-methylpyrazole-1-carboxamide, 3-methylpyrazole, 2-chloro-6-(trichloromethyl)pyridine, and 4-chloro-3-methylpyrazole. These substances are used alone or in combination in this invention.

[0031] A method for preparing the sustained-release composite material of the present invention includes the following steps:

[0032] The first inorganic material is applied to the carrier and dried to form the first inorganic layer;

[0033] Then, at 0℃~80℃, an organic material is applied to the surface of the first inorganic layer, followed by the application of a second inorganic material and drying, so that the first inorganic layer and the second inorganic layer are combined to form a slow-release composite material.

[0034] Another method for preparing the sustained-release composite material of the present invention includes the following steps:

[0035] The first inorganic material is applied to a granular carrier, rolled, and dried to form the first inorganic layer.

[0036] Subsequently, at 0℃~80℃ and 10rpm~800rpm, an organic material was applied to the surface of the first inorganic layer, followed by the application of a second inorganic material. The mixture was then rolled and dried to combine the first and second inorganic layers, forming a particulate slow-release composite material.

[0037] The beneficial effects of the technical solution of this invention are as follows:

[0038] The slow-release composite material provided by this invention uses green and environmentally friendly raw materials, leaving no obvious residue in the soil, thus achieving environmental friendliness.

[0039] The slow-release composite material provided by this invention has low production cost, simple preparation process, low equipment investment, small footprint, and can be industrialized. It is suitable for manufacturing most granular fertilizers and improving fertilizer efficiency.

[0040] The sustained-release composite material provided by this invention serves as packaging material, encapsulating the inhibitor within the composite material, thereby suppressing the loss of highly volatile active ingredients (such as chloridine) and improving storage stability.

[0041] The slow-release composite material provided by this invention serves as packaging material, encapsulating fertilizer within the composite material and significantly extending the fertilizer's effective period.

[0042] The slow-release composite material provided by this invention serves as a packaging material to encapsulate nitrogen fertilizer within the composite material, effectively extending the fertilizer effect period of urea (amide) nitrogen fertilizer. When mixed with urea granular fertilizer to form a base fertilizer, a single application of base fertilizer can meet the nitrogen needs of crops throughout the entire growing season. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of an embodiment of a slow-release fertilizer manufactured using the slow-release composite material of the present invention as packaging material. Detailed Implementation

[0044] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings. The embodiments of the present invention are only used to illustrate the technical solution of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of the invention without departing from the spirit and scope of the technical solution of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention.

[0045] Example 1: Preparation of slow-release urea granular fertilizer containing chloridine nitrification inhibitor

[0046] (1) Using urea fertilizer as the core, weigh 2 kg of urea with a particle diameter of 3 mm and add it into a disc-drum coating machine with a diameter of 40 cm to 50 cm. Rotate the machine at a constant speed of 30 rpm to 500 rpm. Apply 200 g of 35 wt% ethyl chloride solution evenly to the surface of the particles and continue rotating to prevent clumping.

[0047] (2) Add 90g of 50-mesh diatomaceous earth that has been dried at 120℃ to the drum in step (1) and stir it thoroughly at 300rpm for 5 minutes to complete the inner layer coating (so that fertilizers and inhibitors are coated in the first inorganic layer).

[0048] (3) Apply the organic matter to the drum in step (2), mix thoroughly for 5 minutes, then add 100g of pre-dried 50-mesh diatomaceous earth, and continue to rotate for 5 minutes to obtain slow-release fertilizer.

[0049] The slow-release fertilizer in step (3) is dried at 70℃~100℃ for 1 hour to obtain the dried slow-release fertilizer.

[0050] Figure 1 This is a schematic diagram illustrating the structure of an embodiment of a slow-release fertilizer manufactured using the slow-release composite material of the present invention as a packaging material. Figure 1 As shown, the slow-release fertilizer includes a slow-release packaging material, fertilizer 1, and regulator 2. The slow-release packaging material is composed of organic matter 4, which is combined with a first inorganic layer 3 and a second inorganic layer 5, forming a capsule. The fertilizer and regulator are placed inside the capsule cavity. The fertilizer consists of granules with a diameter of 0.1 mm to 10 mm, and the regulator covers the outside of the fertilizer.

[0051] Various fertilizers were prepared using the above method, as detailed in Tables 1-9. The fertilizers shown in Tables 1 and 2 did not use the slow-release packaging material composed of a first and second inorganic layer; the slow-release fertilizers are detailed in Tables 3-9. Analysis and testing showed that the 2-chloro-6-(trichloromethyl)-pyridine content, acting as a nitrification inhibitor, was over 95% of its designed content, with minimal process loss. After a two-week accelerated heat storage test at 54℃, its nitrification inhibitor content remained above 80%.

[0052] Table 1

[0053]

[0054] Note: N / A in the table indicates that it is not provided.

[0055] Table 2

[0056]

[0057] Note: N / A in the table indicates that it is not provided.

[0058] Table 3

[0059]

[0060] Note: N / A in the table indicates that it is not provided.

[0061] Table 4

[0062]

[0063] Note: N / A in the table indicates that it is not provided.

[0064] Table 5

[0065]

[0066] Note: N / A in the table indicates that it is not provided.

[0067] Table 6

[0068]

[0069] Note: N / A in the table indicates that it is not provided.

[0070] Table 7

[0071]

[0072] Note: N / A in the table indicates that it is not provided.

[0073] Table 8

[0074]

[0075] Note: N / A in the table indicates that it is not provided.

[0076] Table 9

[0077]

[0078] Note: N / A in the table indicates that it is not provided.

[0079] In actual use, simply take 1 kg of the slow-release fertilizer, mix it with 15 kg to 20 kg of pure urea granular fertilizer, stir it simply, and then apply it as a traditional base fertilizer.

[0080] Example 2: Preparation of slow-release urea granular fertilizer containing nitrification inhibitor and urease inhibitor

[0081] (1) Weigh 2 kg of urea with a particle diameter of 3 mm and 4 g of nBPT and add them to a disc-drum coating machine with a diameter of 40 cm to 50 cm. Rotate the machine at a constant speed of 30 rpm to 70 rpm. Apply 200 g of 30 wt% chloridine acetone solution to the surface of the particles and continue rotating to prevent clumping.

[0082] (2) Add 90g of 50-mesh diatomaceous earth that has been dried at 120℃ to the drum in step (1) and stir it thoroughly at 70rpm for 5 minutes to complete the inner layer coating (so that fertilizers and inhibitors are coated in the first inorganic layer).

[0083] (3) Apply the organic matter to the drum in step (2), mix thoroughly for 5 minutes, then add 100g of pre-dried 50-mesh diatomaceous earth, and continue to rotate for 5 minutes to obtain slow-release fertilizer.

[0084] The slow-release fertilizer in step (3) is dried at 70℃~100℃ for 1 hour to obtain the dried slow-release fertilizer.

[0085] Various fertilizers were prepared using the above method, as detailed in Tables 1-9. The fertilizers shown in Tables 1 and 2 did not use the slow-release packaging material composed of a first and second inorganic layer; the slow-release fertilizers are detailed in Tables 3-9. Analysis and testing showed that the 2-chloro-6-(trichloromethyl)-pyridine content, acting as a nitrification inhibitor, was over 95% of its designed content, with minimal process loss. After a two-week accelerated heat storage test at 54℃, its nitrification inhibitor content remained above 80%.

[0086] Table 10

[0087]

[0088] Note: N / A in the table indicates that it is not provided.

[0089] Table 11

[0090]

[0091] Note: N / A in the table indicates that it is not provided.

[0092] Table 12

[0093]

[0094] Note: N / A in the table indicates that it is not provided.

[0095] Table 13

[0096]

[0097] Note: N / A in the table indicates that it is not provided.

[0098] Table 14

[0099]

[0100] Note: N / A in the table indicates that it is not provided.

[0101] Table 15

[0102]

[0103] Note: N / A in the table indicates that it is not provided.

[0104] In actual use, simply take 1 kg of the slow-release fertilizer, mix it with 10 kg to 20 kg of pure nitrogen-containing (such as urea) granular fertilizer, stir it simply, and then apply it as a traditional base fertilizer.

Claims

1. A slow-release composite material for extending the fertilizer effect period of urea-based nitrogen fertilizer, used to encapsulate fertilizer granules and regulators to manufacture slow-release fertilizer, characterized in that, The slow-release fertilizer includes a slow-release composite material, a fertilizer, and a regulator. The fertilizer is in the form of granules with a diameter of 0.1 mm to 10 mm. The regulator is coated on the outside of the fertilizer granules. The slow-release composite material is made by combining a first inorganic layer and a second inorganic layer with organic matter. The organic matter acts as a binder to bond the first inorganic layer and the second inorganic layer, forming a capsule shape, including a capsule cavity. The fertilizer granules and the regulator are placed inside the capsule cavity. The fertilizer granules are made from nitrogen fertilizer and agricultural additives; The regulators mentioned include nitration inhibitors; The nitrogen fertilizer mentioned is urea; The organic compound is Polyacrylic emulsion, and the solid content of Polyacrylic emulsion is 40%~50%. The first inorganic layer is selected from diatomaceous earth; The second inorganic layer is made of diatomaceous earth; The first inorganic layer and the second inorganic layer use the same material; The nitration inhibitor is 2-chloro-6-(trichloromethyl)-pyridine; In the preparation of the slow-release fertilizer, the following feed ratio is used: the content of urea is 90%, the content of the first inorganic layer is 3.5%, the content of the polyacrylic acid emulsion is 1.0%, the content of the second inorganic layer is 3.0%, the content of the nitrification inhibitor is 1.5%, and the diatomaceous earth is 50 mesh. A 35wt% ethyl 2-chloro-6-(trichloromethyl)-pyridine solution is uniformly applied to the surface of the fertilizer granules. The slow-release fertilizer is a dried slow-release fertilizer obtained by drying at 70~100℃ for 1 hour. The slow-release composite material encapsulates fertilizer and regulators, enabling the slow release of substances, improving fertilizer efficiency, extending the fertilizer's effective period from 30 days to 60 days, and achieving a total effective period of approximately 120 days. It also improves the storage stability of the regulators; after a two-week accelerated heat storage test, the nitrification inhibitor retained over 80% of its original value, and the nitrification inhibitor achieved two years of storage stability within the slow-release composite material.

2. The slow-release composite material for extending the fertilizer effect period of urea nitrogen fertilizer according to claim 1 is used to encapsulate fertilizer granules and regulators to manufacture slow-release fertilizer, characterized in that, The agricultural additives mentioned are selected from one or more of calcium carbonate, clay, zinc sulfate, manganese sulfate and ferrous sulfate.

3. The slow-release composite material for extending the fertilizer effect period of urea nitrogen fertilizer according to claim 1 is used to encapsulate fertilizer granules and regulators to manufacture slow-release fertilizer, characterized in that, After two weeks of accelerated heat storage test at 54℃, the modifier contained in the slow-release composite material remained above 80%.

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