Anti-caking graphene chemical fertilizer film and preparation method thereof
By preparing anti-caking graphene fertilizer films, using materials such as graphene oxide and sodium alginate to construct nanoscale spacer networks, and combining calcium chloride to regulate the degree of crosslinking, the problem of fertilizer caking was solved, achieving long-term anti-caking effect and rapid nutrient delivery of fertilizers, while also being environmentally friendly.
Patent Information
- Application Number
- CN202511778047.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-28
- Publication Date
- 2026-02-06
AI Technical Summary
Existing fertilizers are prone to clumping during storage and transportation, requiring them to be broken up before application, which affects fertilization efficiency and may cause uneven nutrient distribution. Furthermore, existing waterproofing materials cannot simultaneously achieve long-lasting anti-caking properties, rapid nutrient delivery, and environmental friendliness.
Anti-caking graphene fertilizer films are prepared using materials such as graphene oxide, sodium alginate, and konjac glucomannan. By constructing a nanoscale spacer network to block water migration and adding calcium chloride to regulate the degree of cross-linking, the film can be rapidly disintegrated in soil water, ensuring rapid release of fertilizer.
It achieves long-lasting anti-caking properties for fertilizers, rapidly releases nutrients, reduces caking during transportation, and quickly disintegrates in the soil without leaving harmful substances, making it environmentally friendly.
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Figure SMS_1
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of thin film materials, in particular to an anti-caking graphene fertilizer thin film and a preparation method thereof. BACKGROUND
[0002] Highly hygroscopic fertilizers (such as ammonium chloride and ammonium sulfate) and bulk urea are prone to form hard clumps during storage and transportation due to particle moisture absorption and extrusion, which leads to the need for crushing during application, thereby reducing the efficiency of fertilization and easily causing uneven nutrient distribution.
[0003] In order to solve the problem of fertilizer caking, the existing technology usually wraps a waterproof layer on the surface of the fertilizer. The existing waterproof layer materials mainly include inert powder, paraffin coating, and high molecular coating. Among them, the inert powder (talcum powder, diatomite) is easy to fall off, and the anti-caking effective period is less than 3 months; the paraffin coating is excessively hydrophobic (contact angle > 110°), which delays the release of nutrients for 2-3 days, affecting the growth of crops in the seedling stage; the high molecular coating is mostly non-degradable material (such as PP, PE), which causes soil residue during long-term use.
[0004] Therefore, in the existing technology, it is difficult to simultaneously achieve long-term anti-caking, nutrient availability, and environmental friendliness for ammonium chloride and other highly hygroscopic fertilizers, and there is still room for improvement. SUMMARY
[0005] In order to better achieve long-term anti-caking, nutrient availability, and environmental friendliness, the present application provides an anti-caking graphene fertilizer thin film and a preparation method thereof.
[0006] In a first aspect, the present application provides a preparation method of an anti-caking graphene fertilizer thin film, which adopts the following technical scheme: A preparation method of an anti-caking graphene fertilizer thin film, comprising the following steps: Step 1), mixing graphene oxide, xanthan gum, and a solvent, and ultrasonic crushing to obtain a dispersion liquid; Step 2), mixing sodium alginate, konjac glucomannan, glycerol, and a solvent, stirring at 50-55°C for 40-45 min, cooling to 20-25°C, adding nano-silicon dioxide, and stirring uniformly to obtain a base film liquid; Step 3), mixing the dispersion liquid with the base film liquid, then adding calcium chloride and mixing uniformly to obtain a coating liquid; Step 4), atomizing and spraying the coating liquid on the surface of the substrate particles to form pre-coated particles; Step 5), solidifying and drying the pre-coated particles to form an anti-caking graphene fertilizer thin film on the surface of the substrate particles; In step 1), the mass ratio of graphene oxide, xanthan gum, and solvent is 0.25-0.35:0.15-0.25:100. In the step 2), the mass ratio of sodium alginate, konjac glucomannan, glycerol, solvent, and nano-silicon dioxide is 14-16:0.9-1.1:0.4-0.6:200:1.4-1.6; In the step 3), the mass ratio of the dispersion liquid, the base film liquid, and calcium chloride is 10:90:0.8.
[0007] By adopting the above technical scheme, the particles are wrapped by a continuous film formed by sodium alginate, and the graphene oxide sheet layers are staggered in the film to construct a "nanoscale interval net", which not only blocks the water migration and crystallization bridge formation between the particles, but also reduces water adsorption through moderate hydrophobicity (contact angle 82-88°), and the anti-caking efficiency is improved by 50% compared with pure sodium alginate, solving the problem of "easy falling off" of traditional powder.
[0008] By adding calcium chloride, the cross-linking degree of sodium alginate can be adjusted, so that the film starts to disintegrate in soil water in 3-5 minutes and completely dissolves in 15 minutes, avoiding caking during storage period and not delaying the fertilizer effect, solving the defect of "slow release of fertilizer".
[0009] The polysaccharide chains of sodium alginate and konjac glucomannan are combined by hydrogen bonds, enhancing the film elasticity (elongation at break ≥150%), which can withstand 0.5MPa pressure without deformation, reducing the adhesion of particles caused by extrusion.
[0010] Through the cooperation of the above raw materials, the anti-caking graphene fertilizer film prepared can well realize the technical effects of anti-caking, long-term effectiveness, nutrient availability, and environmental friendliness.
[0011] Preferably, in the step 1), the ultrasonic power is 500-550W during ultrasonic crushing, and the ultrasonic crushing time is 35-40min.
[0012] By adopting the above technical scheme, the ultrasonic crushing effect is better, which can effectively reduce the particle size of the aggregate, so that the quality of the dispersion liquid is better, and the anti-caking graphene fertilizer film prepared by cooperating with the base film liquid is better.
[0013] Preferably, in the step 2), the stirring speed is 300-350r / min at 50-55℃ for 40-45min.
[0014] By adopting the above technical scheme, the stirring is more sufficient, the quality of the base film liquid prepared is better, the cooperation effect with the dispersion liquid is good, and the quality of the anti-caking graphene fertilizer film prepared is more stable.
[0015] Preferably, in the step 3), after mixing the dispersion liquid and the base film liquid, the stirring speed is 450-500r / min for 50-60min before adding calcium chloride.
[0016] By adopting the technical scheme, the graphene oxide in the dispersion liquid can be uniformly dispersed in the sodium alginate by fully mixing the dispersion liquid and the base film liquid and then adding calcium chloride, the sodium alginate is prevented from being crosslinked too early to affect the dispersion effect of the graphene, and the quality of the fertilizer film is better.
[0017] Preferably, in the step 3), after adding the calcium chloride, the pH is adjusted to 6.5-7.0 to obtain a coating liquid.
[0018] By adopting the technical scheme, the subsequent crosslinking effect is better by adjusting the pH value, and the performance of the fertilizer film is better.
[0019] Preferably, in the step 4), the substrate particles are sent into a fluidized bed coating machine, the coating liquid is sprayed into the fluidized bed coating machine through a double-fluid nozzle, the single coating thickness is 1-1.5 microns, and the pre-coated particles are formed by repeating the coating twice.
[0020] By adopting the technical scheme, the substrate particles can be uniformly coated by twice coating, the anti-caking graphene fertilizer film can better protect the substrate particles, and a better anti-caking effect is achieved.
[0021] Preferably, in the step 5), the pre-coated particles are placed at 30-35 DEG C and 40-45% relative humidity for 20-25 min to complete the curing, and the water content after drying is less than or equal to 0.5%.
[0022] By adopting the technical scheme, the curing effect is better, the performance of the anti-caking graphene fertilizer film is more stable, and the anti-caking effect is better.
[0023] In a second aspect, the application provides an anti-caking graphene fertilizer film, which adopts the following technical scheme: An anti-caking graphene fertilizer film is prepared by the preparation method of the anti-caking graphene fertilizer film.
[0024] By adopting the technical scheme, after the anti-caking graphene fertilizer film wraps the moisture-absorbing fertilizer, the anti-caking graphene fertilizer film can well block the invasion of water, so that the fertilizer can be kept dry for a long time and is not easy to be caked and hardened, and after fertilization, the anti-caking graphene fertilizer film can be quickly disintegrated under the action of soil water, so that the fertilizer ingredients can be quickly released, the influence on the time effectiveness of fertilization is reduced, harmful substances are not easy to be left in the soil, the environment is more friendly, and the fertilizer is more stable.
[0025] In summary, the application has the following beneficial effects: 1. Since the present application forms a continuous film by sodium alginate to wrap the particles, the graphene oxide layers are staggered in the film, constructing a "nanoscale interval net", which not only blocks the water migration and crystallization bridge formation between particles, but also reduces water adsorption through moderate hydrophobicity (contact angle 82-88°), improving the anti-caking efficiency by 50% compared with pure sodium alginate, solving the problem of "easy falling off" of traditional powder.
[0026] 2. In the present application, calcium chloride is preferably added to adjust the cross-linking degree of sodium alginate, so that the film begins to disintegrate in soil water in 3-5 min and completely dissolves in 15 min, avoiding caking during storage period and not delaying fertilizer efficiency, solving the defect of "slow release of fertilizer".
[0027] 3. In the present application, sodium alginate and konjac glucomannan are preferably combined, and the polysaccharide chains of sodium alginate and konjac glucomannan are combined by hydrogen bonds, enhancing the film elasticity (elongation at break ≥150%), which can withstand 0.5 MPa pressure without deformation, reducing particle adhesion caused by extrusion. DETAILED DESCRIPTION
[0028] The present application is further described below in conjunction with examples. Example 1
[0029] A kind of anti-caking fertilizer coated with anti-caking graphene fertilizer film, the preparation method comprises the following steps: Step 1), 0.25 g of graphene oxide, 0.15 g of xanthan gum, 100 g of solvent are put into a container, 500 W ultrasonic crushing is carried out for 35 min, and a dispersion liquid is obtained.
[0030] Step 2), 14 g of sodium alginate, 0.9 g of konjac glucomannan, 0.4 g of glycerol, 200 g of solvent are put into a stirring kettle, heated to 50 DEG C, the stirring speed is 300 r / min, stirring for 40 min, then the temperature is lowered to 20 DEG C, 1.4 g of nano silicon dioxide is added, the stirring speed is 300 r / min, stirring for 10 min, and a base film liquid is obtained.
[0031] Step 3), 10 g of the dispersion liquid and 90 g of the base film liquid are put into a stirring kettle, the stirring speed is 450 r / min, stirring for 50 min, then 0.8 g of calcium chloride is added, the pH is adjusted to 6.5 by adding citric acid, the stirring speed is 450 r / min, stirring for 3 min, and a coating liquid with a viscosity of 150-200 MPa·s is obtained.
[0032] Step 4), 1000 g of ammonium chloride particles are sent into a fluidized bed coating machine, the bed temperature is 40 DEG C, the wind speed is 1.8 m / s, the coating liquid is sprayed by a double-fluid nozzle, the spraying pressure is 0.35 MPa, the single coating thickness is 1 μm, and the pre-coated particles are formed by repeating twice.
[0033] Step 5), the pre-coated particles are transferred into a low-temperature curing chamber, and are left to stand at 30°C and 40% relative humidity for 20 min to complete curing, and then vacuum degassing drying is performed to make the water content ≤0.5%, so that the anti-caking graphene fertilizer film is formed on the surface of the ammonium chloride particles, thereby obtaining the anti-caking fertilizer coated with the anti-caking graphene fertilizer film.
[0034] The graphene oxide is commercially available, has a purity ≥92%, a sheet size of 3-8 μm, and a carboxyl content ≥15%.
[0035] The xanthan gum is commercially available.
[0036] The solvent is deionized water.
[0037] The sodium alginate is commercially available, has a molecular weight of 100000-150000, a viscosity of 200-300 mPa·s, and a solubility ≥90% at 25°C. The konjac glucomannan is commercially available.
[0038] The glycerol is commercially available.
[0039] The nano-silicon dioxide is commercially available, has a particle size of 10-20 nm.
[0040] The calcium chloride is commercially available.
[0041] The ammonium chloride is commercially available, has a particle size of 2-4 mm. Example 2
[0042] An anti-caking fertilizer coated with an anti-caking graphene fertilizer film, and a preparation method thereof, includes the following steps: Step 1), 0.3 g of graphene oxide, 0.2 g of xanthan gum, and 100 g of solvent are put into a container, and are subjected to ultrasonic crushing at 550 W for 40 min to obtain a dispersion liquid.
[0043] Step 2), 15 g of sodium alginate, 1 g of konjac glucomannan, 0.5 g of glycerol, and 200 g of solvent are put into a stirring kettle, and are heated to 55°C, and are stirred at a speed of 350 r / min for 45 min, and then are cooled to 25°C, 1.5 g of nano-silicon dioxide is added, and is stirred at a speed of 350 r / min for 15 min to obtain a base film liquid.
[0044] Step 3), 10 g of the dispersion liquid and 90 g of the base film liquid are put into a stirring kettle, and are stirred at a speed of 500 r / min for 60 min, and then 0.8 g of calcium chloride is added, and the pH is adjusted to 6.8 by adding citric acid, and is stirred at a speed of 500 r / min for 5 min to obtain a coating liquid with a viscosity of 150-200 MPa·s.
[0045] Step 4), 1000 g of ammonium chloride particles were sent into a fluidized bed coating machine, the bed temperature was 40℃, the wind speed was 1.8 m / s, the coating liquid was sprayed by a double-fluid nozzle, the spraying pressure was 0.35 MPa, the single coating thickness was 1.2 μm, and the pre-coated particles were formed by repeating twice.
[0046] Step 5), the pre-coated particles were transferred into a low-temperature curing chamber, and were placed at 35℃ and 45% relative humidity for 25 min to complete curing, and then vacuum degassing drying was performed to make the water content ≤0.5%, so that an anti-caking graphene fertilizer film was formed on the surface of the ammonium chloride particles, thereby obtaining an anti-caking fertilizer coated with an anti-caking graphene fertilizer film.
[0047] The graphene oxide was commercially available, the purity was ≥92%, the sheet size was 3-8 μm, and the carboxyl content was ≥15%.
[0048] The xanthan gum was commercially available.
[0049] The solvent was deionized water.
[0050] The sodium alginate was commercially available, the molecular weight was 100000-150000, the viscosity was 200-300 mPa・s, and the solubility at 25℃ was ≥90%. The konjac glucomannan was commercially available.
[0051] The glycerol was commercially available.
[0052] The nano-silicon dioxide was commercially available, the particle size was 10-20 nm.
[0053] The calcium chloride was commercially available.
[0054] The ammonium chloride was commercially available, the particle size was 2-4 mm. Example 3
[0055] An anti-caking fertilizer coated with an anti-caking graphene fertilizer film, the preparation method comprising the following steps: Step 1), 0.35 g of graphene oxide, 0.25 g of xanthan gum, and 100 g of solvent were put into a container, and were ultrasonically broken for 40 min at 550 W to obtain a dispersion liquid.
[0056] Step 2), 16 g of sodium alginate, 1.1 g of konjac glucomannan, 0.6 g of glycerol, and 200 g of solvent were put into a stirring kettle, heated to 55℃, stirred at a speed of 350 r / min for 45 min, then cooled to 25℃, 1.6 g of nano-silicon dioxide was added, and stirred at a speed of 350 r / min for 15 min to obtain a base film liquid.
[0057] Step 3), 10 g of the dispersion liquid and 90 g of the base film liquid were put into a stirred tank, stirred at a speed of 500 r / min for 60 min, then 0.8 g of calcium chloride was added, the pH was adjusted to 7.0 by adding citric acid, and stirred at a speed of 500 r / min for 5 min to obtain a coating liquid with a viscosity of 150-200 MPa·s.
[0058] Step 4), 1000 g of ammonium chloride particles were sent into a fluidized bed coating machine, the bed temperature was 40℃, the wind speed was 1.8 m / s, the coating liquid was sprayed by a double-fluid nozzle, the spraying pressure was 0.35 MPa, the single coating thickness was 1.5 μm, and the pre-coated particles were formed by repeating twice.
[0059] Step 5), the pre-coated particles were transferred into a low-temperature curing chamber, and the curing was completed by standing at 35℃ and 45% relative humidity for 25 min, then vacuum degassing drying was performed to make the water content ≤0.5%, so that an anti-caking graphene fertilizer film was formed on the surface of the ammonium chloride particles, thereby obtaining an anti-caking fertilizer coated with an anti-caking graphene fertilizer film.
[0060] The graphene oxide was commercially available, with a purity of ≥92%, a sheet size of 3-8 μm, and a carboxyl content of ≥15%.
[0061] The xanthan gum was commercially available.
[0062] The solvent was deionized water.
[0063] The sodium alginate was commercially available, with a molecular weight of 100000-150000, a viscosity of 200-300 mPa·s, and a solubility of ≥90% at 25℃. The konjac glucomannan was commercially available.
[0064] The glycerol was commercially available.
[0065] The nano-silicon dioxide was commercially available, with a particle size of 10-20 nm.
[0066] The calcium chloride was commercially available.
[0067] The ammonium chloride was commercially available, with a particle size of 2-4 mm.
[0068] Comparative Example 1 An anti-caking fertilizer coated with an anti-caking graphene fertilizer film, compared with Example 2, only differed in that: The diatomite was used to replace the graphene oxide in an equal amount.
[0069] The diatomite was commercially available, with a mesh size of 325.
[0070] Comparative Example 2 An anti-caking fertilizer coated with an anti-caking graphene fertilizer film, compared with Example 2, only differed in that: Talcum powder is used to replace graphene oxide in equal amount.
[0071] Talcum powder is commercially available, 325 mesh.
[0072] Comparative Example 3 A caking prevention fertilizer coated with a caking prevention graphene fertilizer film, compared with Example 2, is only different in that: Inulin is used to replace konjac glucomannan in equal amount.
[0073] Inulin is commercially available, 90% content, water-soluble dietary fiber.
[0074] Comparative Example 4 A caking prevention fertilizer coated with a caking prevention graphene fertilizer film, compared with Example 2, is only different in that: Kappa carrageenan is used to replace konjac glucomannan in equal amount.
[0075] Kappa carrageenan is commercially available.
[0076] Experiment 1 The caking prevention fertilizer coated with a caking prevention graphene fertilizer film of each example and comparative example is stored at 85% relative humidity for 6 months, 1000 kg of the caking prevention fertilizer coated with a caking prevention graphene fertilizer film is used as a test sample, after 6 months of storage, the caked fertilizer is screened, the mass of the caked fertilizer is weighed, recorded as the mass of the caked fertilizer after storage (kg), and the caking rate (%) of the caking prevention fertilizer coated with a caking prevention graphene fertilizer film is calculated by the following formula.
[0077] Caking rate (%) = (mass of caked fertilizer after storage ÷ 1000) × 100% Experiment 2 The caking prevention fertilizer coated with a caking prevention graphene fertilizer film of each example and comparative example is put into soil water, and the time required for the caking prevention fertilizer to completely melt is observed, and the completely melted criterion is that it is difficult to observe the existence of the caking prevention fertilizer coated with a caking prevention graphene fertilizer film in the soil water.
[0078] Experiment 3 The coating liquid obtained in step 3) of the examples and comparative examples is injected into a mold, and the solidification is completed by standing at 30°C and 40% relative humidity for 60 min, thereby preparing a test sample.
[0079] The tensile strain at break (%) of the test sample is detected according to GB / T1040.3-2006 “Determination of the tensile properties of plastics-Part 3: test conditions for films and sheets”.
[0080] The test sample is prepared according to the Type 2 sample standard, and the tensile speed in the experiment is 50 mm / min.
[0081] The specific experimental data of experiment 1-3 are shown in Table 1.
[0082] Table 1
[0083] According to the data comparison of each example and the comparative example in Table 1, each example has a lower caking rate, a shorter fertilizer melting time, and a higher tensile fracture strain, which proves that the anti-caking graphene fertilizer film of each example can effectively protect the hygroscopic fertilizer particles, reduce the caking of the hygroscopic fertilizer particles, and has a relatively long-lasting effect. Moreover, it does not affect the release of the fertilizer after fertilization, so that the fertilization efficiency is relatively high. In addition, the anti-caking graphene fertilizer film is not easy to break during transportation, reduces the caking phenomenon caused by extrusion during transportation, and makes the anti-caking effect more significant during storage and transportation.
[0084] The specific embodiments are merely illustrative of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the present specification, as long as the modifications are within the scope of the claims of the present application.
Claims
1. A method for preparing an anti-caking graphene fertilizer film, characterized in that: Includes the following steps: Step 1), mix graphene oxide, xanthan gum, and solvent, and then sonicate to break down the mixture to obtain a dispersion; Step 2), mix sodium alginate, konjac glucomannan, glycerol and solvent, stir at 50-55℃ for 40-45 min, cool to 20-25℃, add nano silica, stir evenly to obtain base film solution; Step 3) Mix the dispersion with the base film solution, then add calcium chloride and mix thoroughly to obtain the coating solution; Step 4) Atomize the coating liquid and spray it onto the surface of the substrate particles to form pre-coated particles; Step 5) The pre-coated particles are cured and dried to form an anti-caking graphene fertilizer film on the surface of the substrate particles. In step 1), the mass ratio of graphene oxide, xanthan gum, and solvent is 0.25-0.35:0.15-0.25:
100. In step 2), the mass ratio of sodium alginate, konjac glucomannan, glycerol, solvent, and nano-silica is 14-16: 0.9-1.1：0.4-0.6：200：1.4-1.6； In step 3), the mass ratio of the dispersion, the base film solution, and the calcium chloride is 10: 90：0.8。 2. The method for preparing an anti-caking graphene fertilizer film according to claim 1, characterized in that: In step 1), the ultrasonic power is 500-550W and the ultrasonic breaking time is 35-40min.
3. The method for preparing an anti-caking graphene fertilizer film according to claim 1, characterized in that: In step 2), the stirring is carried out at 50-55℃ and 300-350 r / min for 40-45 min.
4. The method for preparing an anti-caking graphene fertilizer film according to claim 1, characterized in that: In step 3), after mixing the dispersion and the base film solution, stir at 450-500 r / min for 50-60 min and then add calcium chloride.
5. The method for preparing an anti-caking graphene fertilizer film according to claim 4, characterized in that: In step 3), after adding calcium chloride, the pH is adjusted to 6.5-7.0 to obtain the coating solution.
6. The method for preparing an anti-caking graphene fertilizer film according to claim 1, characterized in that: In step 4), the substrate particles are fed into a fluidized bed coating machine, and the coating liquid is sprayed in through a dual-fluid nozzle. The coating thickness is 1-1.5 μm in a single application, and the process is repeated twice to form pre-coated particles.
7. The method for preparing an anti-caking graphene fertilizer film according to claim 1, characterized in that: In step 5), the pre-coated particles are left to stand at 30-35℃ and 40-45% relative humidity for 20-25 minutes to complete the curing process, and the moisture content after drying is ≤0.5%.
8. A graphene fertilizer film for preventing agglomeration, characterized in that: It is prepared by the method for preparing anti-caking graphene fertilizer film according to any one of claims 1-7.