Compound fertilizer anti-caking agent, preparation method and application thereof

Abstract

The application relates to the technical field of fertilizer additives, and particularly discloses a compound fertilizer anti-caking agent as well as a preparation method and application thereof. The compound fertilizer anti-caking agent comprises the following components in parts by weight: 70-85 parts of an acrylic acid polymer, 8-15 parts of sodium polyacrylate, 5-15 parts of a penetrating agent, 10-20 parts of a reinforcing agent and 5-15 parts of a waterproof agent. The acrylic acid polymer has a polymerization degree of 70-110, and the sodium polyacrylate has a weight-average molecular weight of 100000-500000. The formula provided by the application has high anti-caking efficiency, is especially suitable for fertilizer storage under high and low temperature environments, has high production efficiency, a simple application process and can be directly added in a fertilizer granulation process.

Description

Technical Field

[0001] This application relates to the field of fertilizer additive technology, and more specifically, it relates to a compound fertilizer anti-caking agent, its preparation method, and its application. Background Technology

[0002] Currently, the main raw materials for compound (mixed) fertilizer production are urea, ammonium chloride, ammonium nitrate, ammonium sulfate, monoammonium phosphate, diammonium phosphate, superphosphate, calcium carbonate, potassium chloride, and potassium sulfate. These fertilizers have high solubility and low hygroscopic points, and the hygroscopic points of compound (mixed) fertilizers made from them are even lower than those of single fertilizers. This makes compound (mixed) fertilizers made from these fertilizers more prone to caking during storage and transportation. Caking fertilizers need to be broken up during use and testing, which not only increases labor but also poses potential safety hazards, causing inconvenience and affecting the uniformity and representativeness of commodity inspection sampling. Therefore, extensive research has been conducted on the fertilizer caking problem, which can be broadly summarized into two approaches: one is to reduce fertilizer caking by optimizing production processes, such as adopting modern production processes, introducing new granulation equipment and drying processes, improving storage conditions, improving packaging conditions and methods, and using moisture-proof packaging materials; the other approach is to use fertilizer anti-caking agents to reduce the product's moisture content and improve its strength, uniformity, and looseness.

[0003] Anti-caking agents, also known as anti-caking agents or loosening agents, are additives used to promote good flowability of fertilizers during loading and unloading. To prevent fertilizer caking, fertilizer manufacturers primarily use anti-caking agents to coat fertilizers while improving process conditions and controlling granule characteristics. The use of anti-caking agents can maximally suppress fertilizer caking, moisture absorption, and pulverization, increasing granule flowability and facilitating fertilizer storage, transportation, and use. Therefore, as a low-cost, high-return anti-caking measure, anti-caking agents are now widely accepted and used by compound fertilizer manufacturers worldwide.

[0004] Currently, there are many types of compound fertilizer anti-caking agents on the Chinese market, mainly in powder and oil forms depending on the base material:

[0005] Powdered anti-caking agents are made from inert powders such as diatomaceous earth, kaolin, and talc, which are modified and ground into ultrafine powders. These powders adhere to the surface of fertilizer granules, providing mechanical isolation and inhibiting fertilizer caking. Powdered anti-caking agents are widely used due to their versatility, low cost, and minimal environmental impact. However, because of the limited adhesion of the powder, the dosage is small, resulting in generally limited effectiveness.

[0006] Oil-based anti-caking agents typically work by coating fertilizer surfaces to form a hydrophobic protective film, reducing particle interaction. Traditional oil-based anti-caking agents are usually petroleum-based products such as mineral oils and alkylamines. Mineral oils, due to their stability and good hydrophobicity, are currently the most widely used anti-caking agents. Currently, most oil-based anti-caking agents on the market are mixtures of paraffin wax, primary amines, and dissolved oils. Paraffin wax is brittle and has poor adhesion. During fertilizer storage, slight deformation due to compression can cause cracks in the paraffin wax coating, significantly reducing its anti-caking effect. Using machine oil as a raw material is problematic because machine oil is expensive and often contains saturated alkanes that are difficult to degrade. Using acidified oil as a raw material is also problematic because acidified oil contains a large number of unsaturated carbon chains, which are easily oxidized and prone to generating bubbles when heated. When atomized and sprayed onto the fertilizer surface, these bubbles burst, resulting in discontinuous coating and significantly reducing the anti-caking effect.

[0007] For example, US Patent 4220463A discloses a surface coating C 12 -C 18 Alkylamine fertilizer granules are first coated with a uniform and continuous layer of molten C on the surface of the fertilizer granules. 12 -C 18 An alkylamine layer is applied, and after the coating cools, a thin layer of mineral oil is applied to the main body to prevent ammonium nitrate from absorbing moisture and clumping together. This patent application uses C... 12 -C 18 The coating of ammonium nitrate particles with alkylamine and mineral oil has high viscosity and low interoperability, resulting in a loose distribution on the surface of ammonium nitrate. This leads to a short anti-caking cycle. Furthermore, the process of first granulating ammonium nitrate and then coating it with alkylamine and mineral oil is complicated and inconvenient for production and use.

[0008] Therefore, a new solution is needed to address this problem. Summary of the Invention

[0009] To address the aforementioned technical problems, this application provides a compound fertilizer anti-caking agent, its preparation method, and its application. The formulation provided in this application has high anti-caking efficiency, is particularly suitable for fertilizer storage under high and low temperature environments, and has high production efficiency and simple application process, allowing it to be directly added during the fertilizer granulation process.

[0010] In a first aspect, this application provides a compound fertilizer anti-caking agent, which adopts the following technical solution:

[0011] A compound fertilizer anti-caking agent comprises the following components in parts by weight: 70-85 parts acrylic polymer, 8-15 parts sodium polyacrylate, 5-15 parts penetrant, 10-20 parts reinforcing agent, and 5-15 parts waterproofing agent; wherein the degree of polymerization of the acrylic polymer is 70-110, and the weight average molecular weight of the sodium polyacrylate is 100,000-500,000.

[0012] The penetrant is an anionic surfactant containing polar groups such as -SO4H, -SO3H, and -PO4H, which mainly plays a role in crystal form control, obtaining a good stable crystal form and maintaining looseness. It includes, but is not limited to, one or more combinations of sodium dioctyl maleate sulfonate, sodium butyl sulfonate, sodium dibutyl sulfonate, alkyl phosphate, sodium succinate sulfate, etc.

[0013] The reinforcing agent is a high-melting-point, insoluble silica-based material to increase the strength of compound fertilizer particles, including but not limited to one or more combinations of silicates, talc, diatomaceous earth, montmorillonite, bentonite, vermiculite, kaolin, perlite, sepiolite, and aerosol silica.

[0014] Preferably, the reinforcing agent is nano-silica with a D50 particle size of 15-50 μm.

[0015] Furthermore, the nano-silica is obtained by surface treatment with a silane coupling agent.

[0016] Preferably, the silane coupling agent is selected from one of aminosilane coupling agents, epoxysilane coupling agents, vinylsilane coupling agents, and mercaptosilane coupling agents.

[0017] More preferably, the silane coupling agent is an epoxy-based silane coupling agent.

[0018] Furthermore, the fertilizer anti-caking agent also contains 1-5 parts by weight of an epoxy silane coupling agent.

[0019] The granulation temperature of compound fertilizer is relatively low, generally 60-80℃. At this temperature, the epoxy groups are more likely to react with amines in the compound fertilizer, and are more likely to solidify into a film, which improves the bonding force between the anti-caking agent and the compound fertilizer particles, and the particles can maintain a high crystal stability.

[0020] Furthermore, the specific steps for treating nano-silica with the silane coupling agent are as follows: a nano-silica suspension is prepared using isopropanol as a solvent, a silane coupling agent is added, and the mixture is stirred and reacted at a certain temperature for a period of time. After purification, the final product is obtained.

[0021] Preferably, the amount of the silane coupling agent is 1-1.5 wt% of nano-silica.

[0022] Specifically, the heating temperature is 80-95℃, and the heating reaction time is 4-8 hours.

[0023] Specifically, the purification steps are as follows: collect the solid and wash it 3-4 times with anhydrous ethanol, then dry it at 100℃ for 2 hours to obtain the final product.

[0024] Waterproofing agents use substances with low melting points and easy film-forming properties to prevent the intrusion of environmental moisture and improve the appearance, molding quality, and brittleness of fertilizer granules. These include, but are not limited to, one or more combinations of long-chain fatty acids, waxes, polyesters, and base oils.

[0025] Preferably, the waterproofing agent is a mixture of polyalphaolefin and polyethylene wax. More preferably, the polyalphaolefin has a kinematic viscosity of 1.67-2.0 mm at 100°C. 2 / s, specifically, the polyalphaolefin is PAO2.

[0026] Secondly, this application provides a method for preparing a compound fertilizer anti-caking agent, which adopts the following technical solution:

[0027] A method for preparing a compound fertilizer anti-caking agent includes the following steps: mixing and stirring an acrylic polymer, sodium polyacrylate, and a waterproofing agent to obtain a mixture; adding a penetrant and a reinforcing agent to the mixture after mixing and stirring; and mixing to obtain the finished product.

[0028] Thirdly, this application provides the application of the aforementioned anti-caking agent. Specifically, it provides the application of the aforementioned anti-caking agent in preventing compound fertilizer from caking.

[0029] Based on this application, this application provides a method for preventing compound fertilizer from caking, the method comprising the step of applying the above-mentioned anti-caking agent to the compound fertilizer.

[0030] Specifically, the step is as follows: In the compound fertilizer granulation process, the anti-caking agent prepared according to the above method is added to the granulation device by spraying and granulated together with the compound fertilizer to obtain compound fertilizer granules with anti-caking effect.

[0031] Preferably, the amount of the anti-caking agent is 0.15-0.4 wt% based on the dry weight of the compound fertilizer.

[0032] In summary, this application has the following beneficial effects:

[0033] (1) This application uses acrylic polymer with a polymer of 70-110 and sodium polyacrylate with a weight average molecular weight of 10w-50w as film-forming agents, which can form a thin film on the surface of fertilizer crystals to prevent moisture and moisture, so that the crystal particles are isolated from each other and do not stick together. The formulation of this application does not add alkylamines, so it will not cause corrosion to the fertilizer surface, and the dosage is low, with the addition amount being only 0.15-0.4wt% of the fertilizer.

[0034] (2) By adding nano-silica that has been surface-treated with silane coupling agent, the strength of fertilizer particles can be increased. The oleophilic nano-silica can further improve the bonding force with the particle surface. In addition, a certain amount of epoxy silane coupling agent is directly added to the anti-caking agent formulation to improve the bonding force of the anti-caking agent on the fertilizer particle surface and improve the anti-caking effect on fertilizer.

[0035] (3) The waterproofing agent of this application uses a combination of PAO2 and polyethylene wax, which can improve the moisture-proof and damp-proof effect of fertilizer particles. The addition of polyalphaolefin PAO2 can improve the anti-caking effect of fertilizer particles in low temperature environment and inhibit salt dissolution-recrystallization between fertilizer particles. Detailed Implementation

[0036] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0037] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0038] Unless otherwise specified, the experimental conditions used in the examples are generally in accordance with conventional conditions in the art or the conditions recommended by the reagent company. Unless otherwise specified, the materials and reagents used in the examples can be purchased commercially.

[0039]

[0040] The D50 particle size of the nano-silica used in this application is 25 μm.

[0041] The polyethylene wax was purchased from Shandong Baolilai Plastic Additives Co., Ltd., with a molecular weight of 1500-5000.

[0042] The fertilizer used is 15-15-15 (N-P2O5-K2O) granular compound fertilizer (particle size 3-5mm).

[0043] The mineral oil used is 60# mineral oil.

[0044] Detection method:

[0045] 1. Relative Agglomeration Rate: Under certain temperature and humidity conditions, the surface of fertilizer crystals will dissolve and recrystallize, forming crystal bridges at the contact points between crystal grains, causing the grains to stick together and agglomerate. High temperature promotes dissolution, while low temperature promotes crystallization. To accurately evaluate crystallinity, the performance testing method provided in this application adds a step of high-temperature moisture absorption, drying, and then low-temperature refrigeration. The total time is short, enabling rapid evaluation of the anti-caking agent's performance. The specific testing and evaluation methods are as follows:

[0046] Granular fertilizer treated with anti-caking agent and granular fertilizer not treated with anti-caking agent were placed in constant temperature and humidity chamber (60℃, 70%RH) for moisture absorption treatment. The moisture absorption time was T and the moisture absorption rate was 4%. Then, a pressure of 40 kPa was applied to the moisture-absorbing granular fertilizer and dried in a 50℃ oven for 12 hours. Then, it was refrigerated in a -4℃ refrigerator for 8 hours. The granular fertilizer after the above steps was gently placed in a shaker and shaken at a frequency of 200 r / min for 10 minutes.

[0047] Agglomerated granular fertilizers were selected from both the granular fertilizer treated with anti-caking agent and the untreated granular fertilizer, and weighed as M1 and M2, respectively.

[0048] .

[0049] 2. Storage caking rate: Granular fertilizer treated with anti-caking agent is packaged into 40kg bags, air is removed and the bags are compacted. The bags are then stored at 60℃ and 70%RH. After three months, the bags are vertically lifted to a height of 1.5m above the ground and dropped freely twenty times. The caking fertilizer inside the bags is removed and weighed (M3). The storage caking rate is then calculated. .

[0050] Example 1: Preparation of the reinforcing agent:

[0051] Example 1-1 Preparation of reinforcing agent: Nano-silica and isopropanol were mixed at a ratio of 20g:100mL to obtain a suspension. Epoxy silane coupling agent KH-560, water, and anhydrous ethanol were mixed at a volume ratio of 1:2:20 to prepare a mixture. The suspension and mixture were then mixed, with KH-560 accounting for 1wt% of the weight of the nano-silica. The mixture was then reacted at 90℃ for 5h. The solid was collected and washed three times with anhydrous ethanol, and then dried at 100℃ for 2h to obtain the final product.

[0052] Example 1-2 Preparation of reinforcing agent: The aminosilane coupling agent KH-550 was used to replace the epoxysilane coupling agent KH-560 in Example 1-1, and the rest was the same as in Example 1-1.

[0053] Example 1-3 Preparation of reinforcing agent: Vinyl silane coupling agent A-171 was used to replace epoxy silane coupling agent KH-560 in Example 1-1, and the rest was the same as in Example 1-1.

[0054] Examples 1-4 Preparation of reinforcing agents: The epoxy silane coupling agent KH-560 in Example 1-1 was replaced by mercaptosilane coupling agent A-189, and the rest was the same as in Example 1-1.

[0055] Example 2: Preparation of anti-caking agent

[0056] Example 2-1 Preparation of anti-caking agent: 80 parts of acrylic polymer, 10 parts of sodium polyacrylate and 10 parts of waterproofing agent were mixed and stirred evenly to obtain a mixture. 10 parts of penetrant and 15 parts of reinforcing agent were mixed and stirred evenly and then added to the mixture. The mixture was stirred and stirred to obtain the finished product.

[0057] The degree of polymerization of the acrylic polymer is 70-110, and the weight-average molecular weight of sodium polyacrylate is 100,000-500,000.

[0058] The waterproofing agent is a mixture of polyalphaolefin (PAO2) and polyethylene wax in a weight ratio of 2:1.

[0059] The penetrant used is sodium dioctyl maleate sulfonate.

[0060] The reinforcing agent was prepared according to Example 1-1.

[0061] Example 2-2 Preparation of anti-caking agent: The reinforcing agent was prepared in Example 1-2, and the rest was the same as in Example 2-1.

[0062] Example 2-3 Preparation of anti-caking agent: The reinforcing agent was prepared in Example 1-3, and the rest was the same as in Example 2-1.

[0063] Examples 2-4 Preparation of anti-caking agent: The reinforcing agent was prepared in Examples 1-4, and the rest was the same as in Example 2-1.

[0064] Example 2-5 Preparation of anti-caking agent: When the penetrant and reinforcing agent are mixed, 3 parts of epoxy silane coupling agent KH-560 are also added, and the rest is the same as in Example 2-1.

[0065] The anti-caking agents prepared in Examples 2-1 to 2-5 were added directly to the granulator by spraying at 0.2 wt% of the fertilizer weight, and granulated together with the compound fertilizer. The granulation temperature was 60-80℃ to obtain granular fertilizer with anti-caking effect. The relative caking rate X and the storage caking rate Y were measured, and the test results are recorded in Table 1 below.

[0066]

[0067] Referring to the test results in Table 1, a comparison of the results of Examples 2-1 to 2-4 shows that Example 2-1 had the lowest relative agglomeration rate X and the lowest agglomeration rate Y after three months of storage, indicating that the anti-caking agent prepared in Example 2-1 had the best anti-caking effect. This demonstrates that nano-silica modified with different silane coupling agents exhibits different reinforcing effects when applied to anti-caking agents. Nano-silica modified with epoxy-based silane coupling agents showed the best anti-caking effect after application. This is because epoxy-based silane coupling agents can react with substances such as amines in compound fertilizers, improving the binding force between the reinforcing agent and the granular fertilizer and maintaining its high crystal stability. Compared to Example 2-1, the direct addition of epoxy-based silane coupling agents in the formulation of Example 2-5 significantly improved the anti-caking effect of the anti-caking agent. This is because when the granulation temperature is controlled at 60-80℃, the epoxy groups readily react with amines in the compound fertilizer, making it easier to solidify into a film, improving the binding force between the anti-caking agent and the compound fertilizer granules, and allowing the granules to maintain high crystal stability.

[0068] Example 3 Preparation of anti-caking agent

[0069] Example 3-1 Preparation of anti-caking agent: The waterproofing agent is a mixture of polyalphaolefin PAO6 and polyethylene wax in a weight ratio of 2:1, and the rest is the same as in Example 2-1.

[0070] Example 3-2 Preparation of anti-caking agent: The waterproofing agent is a mixture of polyalphaolefin PAO10 and polyethylene wax in a weight ratio of 2:1, and the rest is the same as in Example 2-1.

[0071] Example 3-3 Preparation of anti-caking agent: The waterproofing agent is a mixture of polyalphaolefin PAO40 and polyethylene wax in a weight ratio of 2:1, and the rest is the same as in Example 2-1.

[0072] Preparation of comparative anti-caking agents

[0073] Comparative Example 1: Preparation of anti-caking agent: The waterproofing agent is a mixture of 60# mineral oil and polyethylene wax in a weight ratio of 2:1, and the rest is the same as in Example 2-1.

[0074] Based on 0.2 wt% of the fertilizer weight, the anti-caking agent prepared in Examples 3-1 to 3-3 and Comparative Example 1 was directly added to the granulator by spraying and granulated together with the compound fertilizer. The granulation temperature was 60-80℃ to obtain granular fertilizer with anti-caking effect. The relative caking rate X and storage caking rate Y were measured, and the test results are recorded in Table 2 below.

[0075]

[0076] Referring to the test results in Table 2, it can be seen that the anti-caking effect of the anti-caking agent varies significantly depending on the combination of waterproofing agents, especially the change in relative agglomeration rate. This is because the present application uses a mixture of polyalphaolefin and polyethylene wax, which has a better high and low temperature waterproofing and isolation effect. In contrast, Comparative Example 1 uses a combination of 60# mineral oil and polyethylene wax, which has poor low temperature performance and is difficult to prevent the salt dissolution and recrystallization of granular fertilizer, resulting in easy adhesion and agglomeration between granular crystals.

[0077] The above description is merely a preferred embodiment of this application. The scope of protection of this application is not limited to the above embodiments. All technical solutions falling within the scope of this application's concept are within the scope of protection of this application. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of this application should also be considered within the scope of protection of this application.

Claims

1. A compound fertilizer anti-caking agent, characterized in that, The product comprises the following components in parts by weight: 70-85 parts acrylic polymer, 8-15 parts sodium polyacrylate, 5-15 parts penetrant, 10-20 parts reinforcing agent, 5-15 parts waterproofing agent, and 1-5 parts epoxy silane coupling agent; wherein the degree of polymerization of the acrylic polymer is 70-110, the weight average molecular weight of the sodium polyacrylate is 100,000-500,000, the reinforcing agent is nano-silica modified with epoxy silane coupling agent, and the waterproofing agent is a mixture of polyalphaolefin (PAO2) and polyethylene wax.

2. The compound fertilizer anti-caking agent according to claim 1, characterized in that, The penetrant includes at least one of sodium dioctyl maleate sulfonate, sodium butyl sulfonate, sodium dibutyl sulfonate, alkyl phosphate, and sodium succinate sulfate.

3. The compound fertilizer anti-caking agent according to claim 1, characterized in that, The modification steps of the nano-silica are as follows: using isopropanol as solvent, a nano-silica suspension is prepared, an epoxy silane coupling agent is added, and the mixture is stirred and reacted at a certain temperature for a period of time. After purification, the nano-silica is obtained.

4. A method for preparing the compound fertilizer anti-caking agent according to any one of claims 1-3, characterized in that, The process includes the following steps: mixing and stirring acrylic polymer, sodium polyacrylate, and waterproofing agent to obtain a mixture; adding penetrant and reinforcing agent after mixing and stirring to the mixture; and stirring to obtain the finished product.

5. The application of the anti-caking agent according to any one of claims 1-3 in compound fertilizer, characterized in that, The amount of the anti-caking agent is 0.15-0.4 wt% based on the dry weight of the compound fertilizer.

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