Bio-based anti-blocking agent as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of anti-blocking, and particularly relates to a bio-based anti-blocking agent as well as a preparation method and application thereof. The preparation method comprises the following specific steps: S1, chitosan modification: weighing chitosan, dissolving the chitosan in an acetic acid solution with the concentration of 1%, adding acetic anhydride, continuously reacting in a constant-temperature water bath environment of 50 DEG C for 4 hours, and sequentially performing dialysis treatment and freeze drying to obtain modified chitosan; s2, preparation of a composite emulsion: adding the modified chitosan and mixed wax into a reaction container according to a mass ratio of 1: (2-3), heating at 70 DEG C to obtain a mixture, adding 5wt% of an emulsifier, homogenizing, emulsifying, and cooling to 40 DEG C to obtain the composite emulsion. The caking agent provided by the invention has the characteristics of degradability and excellent adhesion performance.

Description

Technical Field

[0001] This invention belongs to the field of anti-caking agent technology, and particularly relates to a bio-based anti-caking agent, its preparation method and application. Background Technology

[0002] When compound fertilizers are used, the temperature difference with humid air and the hydrophilic nature of the fertilizer cause the granules to stick together, leading to clumping. To solve this problem, anti-caking agents are usually added to the compound fertilizer. Traditional anti-caking agents, such as paraffin wax and diatomaceous earth, are highly dependent on petroleum-based materials. Their degradation rate in the natural environment is extremely slow, and they can cause long-term and continuous environmental pollution problems.

[0003] Regarding diatomaceous earth as an anti-caking agent, the coating layer it forms on the surface of granular products has poor stability and is prone to detachment. This directly results in the anti-caking agent's effect being difficult to maintain for a long time, seriously affecting the product's performance during storage and use. Furthermore, anti-caking agents like fatty amines are often used as materials for hydrophobic coatings, posing a risk of soil pollution in practical applications and potentially harming the ecological environment.

[0004] Therefore, there is an urgent need for a bio-based anti-caking agent, its preparation method, and its application to solve the above problems. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention provides a bio-based anti-caking agent, its preparation method, and its application. The anti-caking agent of this invention possesses biodegradable properties and excellent adhesion performance, while its mechanical stability is enhanced through a nano-hybrid structure, thus meeting the dual demands of environmental protection and improved product performance.

[0006] To achieve one of the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing a bio-based anti-caking agent, the specific steps of which are as follows:

[0008] S1. Chitosan modification: Weigh 2-3g of chitosan and dissolve it in a 1% acetic acid solution, add acetic anhydride, and react continuously in a constant temperature water bath at 50℃ for 4 hours. Then, perform dialysis and freeze-drying in sequence to obtain modified chitosan.

[0009] S2. Preparation of composite emulsion: Modified chitosan and mixed wax are added to a reaction vessel at a mass ratio of 1:(2-3), and heated at 70°C to promote full melting and uniform mixing. The molten mixture is then added with 5wt% emulsifier for homogenization and emulsification. The mixture is then cooled to 40°C to obtain a bio-based anti-caking agent.

[0010] Preferably, the mass ratio of chitosan to acetic anhydride is 1:0.5.

[0011] Preferably, the dialysis process involves placing the reaction product into a dialysis bag and dialyzing it in deionized water to thoroughly remove unreacted substances and impurities.

[0012] Preferably, the mixed wax is a mixture of palm wax and microcrystalline wax, with a mass ratio of palm wax to microcrystalline wax of 1:(0.5-1.5).

[0013] Preferably, the emulsifier is Tween 80.

[0014] To achieve the second objective mentioned above, the present invention provides a method for preparing a bio-based anti-caking agent. The bio-based anti-caking agent is prepared by forming a nanoscale structure from modified chitosan and mixed wax in a mass ratio of 1:(2-3).

[0015] To achieve the third objective mentioned above, this invention provides an application of a bio-based anti-caking agent. The specific steps are as follows: in a fluidized bed device, the compound fertilizer granules are preheated to 50°C, and the bio-based anti-caking agent is uniformly sprayed onto the surface of the compound fertilizer granules using a spray gun. Then, a drying process is performed to construct a uniform anti-caking coating on the surface of the compound fertilizer granules.

[0016] Preferably, the inlet air temperature of the fluidized bed is 50-55℃.

[0017] Preferably, the amount of bio-based anti-caking agent used is 1% of the mass of the compound fertilizer.

[0018] Preferably, the spraying rate of the spray gun is 0.5-1.0 mL / min.

[0019] The advantages of this invention are:

[0020] (1) The present invention is a bio-based anti-caking agent with degradable properties and excellent adhesion performance. At the same time, it enhances its mechanical stability by means of nano-hybrid structure, so as to meet the dual requirements of environmental protection and product performance improvement.

[0021] (2) The agglomeration rate of the product treated with the anti-caking agent of the present invention is ≤3%, while the agglomeration rate of the product with paraffin coating in the control group is ≥15%; the biodegradation rate is ≥90% within 6 months, and the experimental data is detailed and reliable; the friction test confirms that the coating has strong adhesion and the peeling rate after the friction test is <5%, which comprehensively improves the overall performance of the product.

[0022] (3) This invention modifies chitosan by introducing hydrophobic acetyl groups into the chitosan molecular structure using acetic anhydride, clearly defining the specific reaction conditions for chitosan modification, and innovatively adopting a low-temperature emulsification spraying process to ensure that the wax droplet particle size is less than 1μm, effectively avoiding the risk of high temperature damaging fertilizer nutrients; fully considering the melting temperature of the wax phase (the melting point of palm wax is about 40-45℃) to prevent the film layer from becoming uneven due to excessive temperature; and dynamically adjusting in real time according to the fluidization state of the particles to ensure that the film layer achieves uniform coverage. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0024] Example 1

[0025] S1. Chitosan Modification: Accurately weigh 2g of chitosan and dissolve it completely in a 1% acetic acid solution. Slowly add acetic anhydride at a ratio of chitosan to acetic anhydride of 1:0.5 (mass ratio) to avoid excessively vigorous reactions and side effects, ensuring the smooth progress of the main reaction. Continue the reaction in a constant temperature water bath at 50℃ for 4 hours. After the reaction, carefully place the product into a dialysis bag and dialyze it in deionized water to thoroughly remove unreacted substances and impurities. Finally, freeze-dry the dialyzed product to obtain modified chitosan.

[0026] S2. Preparation of the composite emulsion: The modified chitosan obtained above and the mixed wax (carnauba wax: microcrystalline wax = 1:0.5) were added to a reaction vessel at a mass ratio of 1:2. The mixture was heated at 70°C to ensure complete melting and homogenization. Next, 5% (by mass) of Tween 80 was added as an emulsifier for emulsification. The mixture was then homogenized using a homogenizer and finally cooled to 40°C, successfully obtaining a stable composite emulsion, thus producing the bio-based anti-caking agent.

[0027] S3. Fertilizer Coating: In a fluidized bed apparatus, the compound fertilizer granules are preheated to 50°C. The prepared composite emulsion is then uniformly sprayed onto the surface of the compound fertilizer granules using a spray gun. The amount of emulsion used is precisely controlled to be 1% of the fertilizer mass. After the spraying operation is completed, a drying process is carried out to successfully construct a uniform coating on the surface of the compound fertilizer granules.

[0028] Example 2

[0029] S1. Chitosan Modification: Accurately weigh 3g of chitosan and dissolve it thoroughly in a 1% acetic acid solution. Add acetic anhydride slowly at a ratio of chitosan to acetic anhydride of 1:0.5 (mass ratio) to avoid excessively vigorous reactions and side effects, ensuring the smooth progress of the main reaction. Continue the reaction in a constant temperature water bath at 50℃ for 4 hours. After the reaction, carefully place the product into a dialysis bag and dialyze it in deionized water to thoroughly remove unreacted substances and impurities. Finally, freeze-dry the dialyzed product to obtain modified chitosan.

[0030] S2. Preparation of the composite emulsion: The modified chitosan obtained above and the mixed wax (carnauba wax: microcrystalline wax = 1:1.5) were added to a reaction vessel at a mass ratio of 1:2. The mixture was heated at 70°C to ensure complete melting and homogenization. Next, 5% (by mass) of Tween 80 was added as an emulsifier for emulsification. The mixture was then homogenized using a homogenizer and finally cooled to 40°C, successfully obtaining a stable composite emulsion, thus producing the bio-based anti-caking agent.

[0031] S3. Fertilizer Coating: In a fluidized bed apparatus, the compound fertilizer granules are preheated to 50°C. The prepared composite emulsion is then uniformly sprayed onto the surface of the compound fertilizer granules using a spray gun. The amount of emulsion used is precisely controlled to be 1% of the fertilizer mass. After the spraying operation is completed, a drying process is carried out to successfully construct a uniform coating on the surface of the compound fertilizer granules.

[0032] Comparative Example 1

[0033] Paraffin wax was used as an anti-caking agent in compound fertilizer granules.

[0034] The compound fertilizer granules of Example 1 and Comparative Example 1 after applying the anti-caking agent were subjected to performance tests. After a long-term storage of 6 months, the agglomeration rate of the product with paraffin coating in Example 1 was ≥15%, while the contact angle test result of Example 1 showed 112°, which fully demonstrates its excellent hydrophobicity; the agglomeration rate was 2.8%, which was much lower than that of Comparative Example 1, and the anti-caking effect was extremely significant.

[0035] This invention employs a low-temperature emulsification spraying process, with the preheating temperature precisely controlled at 40–50°C throughout the process. This ensures that the composite emulsion adheres evenly to the particle surface during spraying, improving the coating effect. The shear rate is stably maintained at 8000–10000 rpm, and laser particle size analyzer measurements ensure that the wax droplet size is less than 1 μm, thereby obtaining a stable composite emulsion and effectively avoiding the risk of high-temperature damage to fertilizer nutrients.

[0036] Air inlet temperature: strictly controlled at 50-55℃, taking into full account the melting temperature of the wax phase (the melting point of palm wax is about 40-45℃) to prevent the film layer from becoming uneven due to excessive temperature.

[0037] Spraying rate: can be flexibly set between 0.5-1.0 mL / min and dynamically adjusted in real time according to the fluidization state of the particles to ensure uniform coverage of the film layer.

[0038] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a bio-based anti-caking agent, characterized in that, The specific steps are as follows: S1. Chitosan modification: Weigh 2-3g of chitosan and dissolve it in a 1% acetic acid solution, add acetic anhydride, and react continuously in a constant temperature water bath at 50℃ for 4 hours. Then, perform dialysis and freeze-drying in sequence to obtain modified chitosan. S2. Preparation of composite emulsion: Modified chitosan and mixed wax are added to a reaction vessel at a mass ratio of 1:(2-3). The mixture is heated at 70°C to obtain a molten mixture. Then, 5wt% emulsifier is added for homogenization and cooled to 40°C to obtain a bio-based anti-caking agent.

2. The method for preparing a bio-based anti-caking agent according to claim 1, characterized in that: The mass ratio of chitosan to acetic anhydride is 1:0.

5.

3. The method for preparing a bio-based anti-caking agent according to claim 1, characterized in that: The dialysis process involves placing the reaction product into a dialysis bag and dialyzing it in deionized water.

4. The method for preparing a bio-based anti-caking agent according to claim 1, characterized in that: The mixed wax is a mixture of palm wax and microcrystalline wax, with a mass ratio of palm wax to microcrystalline wax of 1:(0.5-1.5).

5. The method for preparing a bio-based anti-caking agent according to claim 1, characterized in that: The emulsifier is Tween 80.

6. A bio-based anti-caking agent prepared by the method for preparing the bio-based anti-caking agent according to any one of claims 1-5, characterized in that: This bio-based anti-caking agent is formed by modifying chitosan and mixed waxes in a mass ratio of 1:(2-3) to create a nanoscale structure.

7. The application of a bio-based anti-caking agent as described in claim 6, characterized in that, The specific steps are as follows: In the fluidized bed equipment, the compound fertilizer granules are preheated to 50°C, and the bio-based anti-caking agent is evenly sprayed onto the surface of the compound fertilizer granules using a spray gun. Then, a drying process is carried out to build a uniform anti-caking coating on the surface of the compound fertilizer granules.

8. The application of the bio-based anti-caking agent according to claim 1, characterized in that: The inlet air temperature of the fluidized bed is 50-55℃.

9. The application of the bio-based anti-caking agent according to claim 1, characterized in that: The amount of the bio-based anti-caking agent is 1% of the mass of the compound fertilizer.

10. The application of the bio-based anti-caking agent according to claim 1, characterized in that: The spraying rate of the spray gun is 0.5-1.0 mL / min.