CN114736070B - Coated controlled release fertilizer and preparation method thereof - Google Patents

Coated controlled release fertilizer and preparation method thereof Download PDF

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Publication number
CN114736070B
CN114736070B CN202210440866.9A CN202210440866A CN114736070B CN 114736070 B CN114736070 B CN 114736070B CN 202210440866 A CN202210440866 A CN 202210440866A CN 114736070 B CN114736070 B CN 114736070B
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fertilizer
calcium carbonate
nano calcium
water
controlled release
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CN114736070A (en
Inventor
周子军
曾祥忠
郭松
陈琨
喻华
秦鱼生
何明江
上官宇先
代雨柔
袁婉珍
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Institute Of Agricultural Resources And Environment Sichuan Academy Of Agricultural Sciences
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Institute Of Agricultural Resources And Environment Sichuan Academy Of Agricultural Sciences
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    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05C—NITROGENOUS FERTILISERS
    • C05C9/00—Fertilisers containing urea or urea compounds
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05B—PHOSPHATIC FERTILISERS
    • C05B7/00—Fertilisers based essentially on alkali or ammonium orthophosphates
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05C—NITROGENOUS FERTILISERS
    • C05C9/00—Fertilisers containing urea or urea compounds
    • C05C9/005—Post-treatment
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05D—INORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C; FERTILISERS PRODUCING CARBON DIOXIDE
    • C05D3/00—Calcareous fertilisers
    • C05D3/02—Calcareous fertilisers from limestone, calcium carbonate, calcium hydrate, slaked lime, calcium oxide, waste calcium products
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
    • C05G3/00—Mixtures of one or more fertilisers with additives not having a specially fertilising activity
    • C05G3/40—Mixtures of one or more fertilisers with additives not having a specially fertilising activity for affecting fertiliser dosage or release rate; for affecting solubility
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
    • C05G3/00—Mixtures of one or more fertilisers with additives not having a specially fertilising activity
    • C05G3/90—Mixtures of one or more fertilisers with additives not having a specially fertilising activity for affecting the nitrification of ammonium compounds or urea in the soil
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
    • C05G5/00—Fertilisers characterised by their form
    • C05G5/30—Layered or coated, e.g. dust-preventing coatings
    • C05G5/37—Layered or coated, e.g. dust-preventing coatings layered or coated with a polymer
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P60/00—Technologies relating to agriculture, livestock or agroalimentary industries
    • Y02P60/20—Reduction of greenhouse gas [GHG] emissions in agriculture, e.g. CO2
    • Y02P60/21—Dinitrogen oxide [N2O], e.g. using aquaponics, hydroponics or efficiency measures

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Pest Control & Pesticides (AREA)
  • Soil Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Fertilizers (AREA)

Abstract

The invention discloses a coated controlled release fertilizer, which comprises an inner layer fertilizer core particle and an outer layer polymer coating material, wherein the polymer coating material is a nano calcium carbonate modified water-based polyacrylate emulsion solid. The controlled release performance of the fertilizer is obviously improved by taking the nano calcium carbonate modified water-based polyacrylate emulsion as a polymer coating main body. Compared with unmodified water-based polyacrylate, the nano calcium carbonate modified water-based polyacrylate has lower synchronous fertilizer accumulation release rate of the slow release fertilizer after the coating material is improved, the release speed of the fertilizer is more gentle and uniform, the release period can be prolonged to about 1.9 times, and the nutrient requirement of the whole growing season of crops with longer growing season can be met under the conditions that the coating material and the fertilizer core particles are the same in dosage and the preparation process are the same.

Description

Coated controlled release fertilizer and preparation method thereof
Technical Field
The invention belongs to the field of fertilizers, and relates to a controlled release fertilizer and a preparation method thereof.
Background
The chemical fertilizer is used as grain and makes important contribution to guaranteeing global grain safety. The cultivated land of 9% of the world consumes 1/3 of the fertilizer in the world, and the fertilizer application amount per unit area is 3 times of the average fertilizer application amount in the world. The fertilizer has low utilization rate, especially nitrogen fertilizer, and brings environmental, economic and energy pressure. The slow/controlled release fertilizer has the advantages of effectively improving the nutrient utilization rate, reducing the harm of nutrient loss to the environment, reducing the fertilization cost and the like, and is concerned about the world, wherein the polymer coated fertilizer becomes one of the most developed controlled release fertilizers at present due to the better controlled release effect.
The polymer coated fertilizer is a controlled release fertilizer which is prepared by coating the surface of traditional instant fertilizer particles with high molecular organic polymer to form a film with a certain thickness and realizing the purpose of slowing down or controlling nutrient release through the permeation of the film. However, most of the polymer coated fertilizers commercialized at present need to use organic solvents in the synthetic processing process, which easily causes secondary pollution and causes safety problems.
In recent years, the development of the water-based polyacrylate coated controlled release fertilizer rapidly becomes a great research hotspot of the polymer coated controlled release fertilizer at present. The water-based polyacrylate takes water as a solvent, does not need an organic solvent in the synthesis and fertilizer production processes, has the advantages of odorless finished products, easy degradation, relatively low price, easy synthesis, good film forming property, proper viscosity, no fire hazard in manufacturing, storage and transportation, and the like, and is regarded as an ideal environment-friendly type coated controlled release material.
The inventors have found, in carrying out the present invention, that water-based polyacrylate materials have at least one of the following technical problems:
the water-based polyacrylate coating material has insufficient strength and poor water resistance, so that the coated fertilizer prepared by using the water-based polyacrylate coating material has fast nutrient release and low strength, and the coating is easily disturbed to break in the later release period, so that the nutrient requirement of crops with longer growing seasons in the whole growing season can not be met.
In order to slow down the nutrient release rate of the water-based polyacrylate coated fertilizer and improve the mechanical strength of the coated material, the inventors tried various physical/chemical modifications of the coated material, such as modification with bentonite, modification with nano calcium carbonate, and the like.
The nano calcium carbonate is mainly used for supplying calcein (Chinese patent application No. 201410803048.6 and 201110332329.4) and fertilizer synergist (Chinese patent application No. 201210267581.6 and 201210267685.7) in fertilizers at present.
Because the specific surface area of the nano calcium carbonate is high, the surface of the nano calcium carbonate is hydrophilic and oleophobic, agglomeration and flocculation are easy to occur in aqueous solution, and the dispersion is uneven, so that the modification of the water-based polyacrylate by the nano calcium carbonate in the related prior art scheme of the disclosed coated controlled release fertilizer is not yet considered.
The inventor has not found that the research and report on the use of nano calcium carbonate for modifying water-based polyacrylate emulsion in the prior art, and the patent and literature data of the coated fertilizer prepared from the water-based polyacrylate modified by nano calcium carbonate have not been reported.
Disclosure of Invention
In view of the above, one of the purposes of the invention is to provide a coated controlled release fertilizer with slow nutrient release and high strength of coating materials.
The second purpose of the invention is to provide a preparation method of the coated controlled release fertilizer with slow nutrient release and high strength of the coated material.
The inventor continuously reforms and innovates through long-term exploration and trial and repeated experiments and efforts, and the technical scheme provided by the invention is that the coated controlled-release fertilizer comprises inner-layer fertilizer core particles and outer-layer polymer coating materials, wherein the polymer coating materials are nano calcium carbonate modified water-based polyacrylate emulsion solids.
According to one embodiment of the coated controlled release fertilizer of the present invention, the nano calcium carbonate modified water-based polyacrylate emulsion is prepared by the following steps:
slowly adding the nano calcium carbonate aqueous solution dispersion system into the water-based polyacrylate emulsion, fully stirring, and sieving.
According to one embodiment of the coated controlled release fertilizer, the solute in the nano calcium carbonate aqueous solution dispersion system comprises nano calcium carbonate, sodium hexametaphosphate and/or polyethylene glycol, and the solvent is deionized water.
According to one embodiment of the coated controlled release fertilizer, the nano calcium carbonate aqueous solution dispersion system comprises the following components in parts by weight: 0.005-2.5 parts of nano calcium carbonate, 0.01-1 part of sodium hexametaphosphate, 0.01-0.3 part of polyethylene glycol and 100 parts of deionized water.
According to one embodiment of the coated controlled release fertilizer, the solute addition amount in the nano calcium carbonate aqueous solution dispersion system accounts for 0.01% -5% of the dry matter of the water-based polyacrylate.
According to one embodiment of the coated controlled release fertilizer, the nano calcium carbonate aqueous solution dispersion system is prepared by the following steps:
adding nano calcium carbonate into deionized water, then adding sodium hexametaphosphate or/and polyethylene glycol, and fully stirring and mixing to obtain a nano calcium carbonate aqueous solution dispersion system.
According to one embodiment of the coated controlled release fertilizer, the stirring is performed by a magnetic stirrer for 15min, and the mixing is performed by ultrasonic treatment for 30min.
According to one embodiment of the coated controlled release fertilizer, the mass of the dry matter of the modified polymer coating material accounts for 2.5% -15% of the coated controlled release fertilizer.
According to one embodiment of the coated controlled release fertilizer of the present invention, the water-based polyacrylate emulsion solid is obtained by treating for 8 hours in an oven at 60 ℃.
The invention also provides a preparation method of the coated controlled release fertilizer, which comprises the following steps:
s1, preparation of nano calcium carbonate aqueous solution dispersion system
Adding nano calcium carbonate into deionized water, then adding sodium hexametaphosphate or/and polyethylene glycol, stirring for 15min, and performing ultrasonic treatment for 30min to obtain a nano calcium carbonate aqueous solution dispersion system;
s2, preparation of modified water-based polyacrylate emulsion
Slowly adding the nano calcium carbonate aqueous solution dispersion system prepared in the step S1 into the water-based polyacrylate emulsion, stirring for 15min by using a magnetic stirrer, and sieving with a 200-mesh screen for later use;
s3, coating treatment
And (2) taking the fertilizer core fertilizer and the nano calcium carbonate modified water-based polyacrylate emulsion prepared in the step (S2), preparing coated fertilizer by using a coating machine, and placing the prepared coated fertilizer in an oven for treatment at 60 ℃ for 8 hours.
Compared with the prior art, one of the technical schemes has the following advantages:
a) The controlled release performance of the fertilizer is obviously improved by taking the nano calcium carbonate modified water-based polyacrylate emulsion as a polymer coating main body.
b) The inventor finds that the dispersion effect of the solid nano calcium carbonate in the aqueous solution can be improved by selecting proper dispersing agents and dispersing methods, the mechanical properties of the modified water-based polyacrylate coating material are greatly improved, and the coating quality and effect are improved.
c) The method has simple production process and environmental protection, and has important popularization value.
d) Compared with unmodified water-based polyacrylate, the nano calcium carbonate modified water-based polyacrylate has lower synchronous fertilizer accumulation release rate of the slow release fertilizer after the coating material is improved, the release speed of the fertilizer is more gentle and uniform, the release period can be prolonged to about 1.9 times, and the nutrient requirement of the whole growing season of crops with longer growing season can be met under the conditions that the coating material and the fertilizer core particles are the same in dosage and the preparation process are the same.
Detailed Description
The following description is made with reference to specific embodiments. Example 1 was compared with the base, unmodified water-based polyacrylate was used as the coating material, nano-calcium carbonate modified water-based polyacrylate was used as the coating material in example 2, sodium hexametaphosphate dispersed 1% nano-calcium carbonate modified water-based polyacrylate was used as the coating material in example 3, polyethylene glycol dispersed 1% nano-calcium carbonate modified water-based polyacrylate was used as the coating material in example 4, sodium hexametaphosphate and polyethylene glycol coupled 1% nano-calcium carbonate modified water-based polyacrylate was used as the coating material in example 5, and sodium hexametaphosphate and polyethylene glycol coupled 3% nano-calcium carbonate modified water-based polyacrylate was used as the coating material in example 6. Examples 1 to 6 each include a slow release fertilizer and a method for preparing a slow release fertilizer.
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described in the following in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, based on the embodiments of the invention, which are apparent to those of ordinary skill in the art without inventive faculty, are intended to be within the scope of the invention. Thus, the following detailed description of the embodiments of the invention is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention.
In examples 1 to 6, the method for measuring the cumulative nutrient release rate was as follows:
the coated fertilizer with complete particles is randomly selected from the coated fertilizers stored in a sealing way, each treatment is carried out for 3 times, each repetition is 5g, each repeated coated fertilizer is accurately weighed (two positions after decimal point is accurate), and then the coated fertilizer is placed into a wide-mouth bottle (rubber plug seal) containing 100ml of deionized water, and is placed into a incubator at 25 ℃ for sampling every certain time. After each sampling, all the leachate in the jar was poured out, and 100ml deionized water was added again for further culture at 25 ℃. Urea is measured on a flow analyzer by adopting a p-dimethylaminobenzaldehyde colorimetric method, so that a nutrient accumulation and release curve is obtained.
The results of the measurement of the cumulative nutrient release rate in each example are shown in Table 1.
Figure GDA0004087380730000041
As can be seen from Table 1, the release rates of the six slow release fertilizers show the characteristic of first being fast and then being slow, on one hand, because the coating quality of part of fertilizer core particles is not high, for example, the coating is incomplete, the fertilizer can be released at a higher speed, on the other hand, the total nutrients of the fertilizer in the later-period fertilizer particles are less and less, and the corresponding release rate per day can be reduced. Obviously, after modification treatment, the tensile strength of the model membrane has obvious effect, and is also beneficial to improving the coating quality and reducing the release speed of the initial fertilizer of the slow-release fertilizer.
In examples 1 to 6, the method for measuring the mechanical property data of the coating material:
according to the national standard GB/T528-2009, the prepared model membrane is cut into dumbbell shapes by a cutter. The size of the cutter is 50 multiplied by 4mm, the cutter is measured by an Instron3366 type universal material tester, the automatic sample injection is carried out, the stretching speed is 10mm/min, the camera tracking is carried out, and the temperature is 23 ℃ and the humidity is 50% during the test operation. The tensile strength of the film material was measured. The preparation method of the water-based polyacrylate emulsion model membrane comprises the following steps: and (3) placing the smooth and flat polytetrafluoroethylene plate in a blast drying box, adjusting the level to be horizontal by using a level bar and an aluminum flake, and slowly pouring the uniformly stirred coating liquid onto the polytetrafluoroethylene plate to be freely stretched to form a film. Firstly, placing the film in a drying oven with the temperature of 40 ℃ for 10 hours, then adjusting the temperature to 80 ℃ and continuously baking the film for 24 hours to obtain the model film.
The measurement results of the mechanical property data of the coating materials in each example are shown in Table 2.
Figure GDA0004087380730000051
The coated controlled release fertilizer comprises an inner layer fertilizer core particle and an outer layer polymer coating material, wherein the fertilizer core particle can be a granular simple substance fertilizer such as a nitrogenous fertilizer, a phosphate fertilizer, a potash fertilizer and the like, and can also be a compound fertilizer containing multiple nutrients. In examples 1 to 6, the fertilizer core particles were urea.
Example 1
This example is a comparative example and illustrates a process for the preparation of coated urea using unmodified water-based polyacrylate, and coated controlled release urea prepared by this process. The preparation method of the coated controlled release urea in the embodiment specifically comprises the following steps:
step a, selecting coating mother liquor:
100g of water-based polymer polyacrylate emulsion with solid content of (49+/-1)% is prepared in a laboratory by using a water-based process.
Step b, preparing coating liquid:
distilled water with the same amount as the coating mother solution is slowly dripped into the stirred coating mother solution, and stirring is continued for 15min after all dripping. The coating liquid prepared by uniformly mixing is prepared and used immediately, and the storage temperature is 5-25 ℃ and the storage time is not longer than 4 hours.
Step c, coating:
and (3) using a bottom jet fluidized bed coating machine, such as LDP-3 fluidized bed coating equipment produced by Jiangsu Changzhou drying equipment factory, putting 500g urea into a coating cavity, pumping coating liquid into the coating cavity through a peristaltic pump when the fluidization of the fertilizer is good, atomizing and adhering the coating liquid onto the surfaces of fertilizer particles, and gradually forming a layer of uniform film on the surfaces of the fertilizer particles through up-and-down circulating movement in the coating cavity, thus obtaining the coated fertilizer. In the fluidized bed coating process, the pumping speed, the air inlet temperature, the air outlet temperature, the atomization pressure and other coating parameters of the coating liquid are properly adjusted according to the properties of the coating liquid, so that the water volatilization speed in the coating process is consistent with the film forming reaction, and the film forming is not influenced to cause the coating failure. The coating process is completed in this apparatus every 0.5 kg of fertilizer for about 1.5 to 2 hours.
The tensile strength of the model film prepared in the embodiment is 13.21MPa; the coated urea prepared in the embodiment has a cumulative release rate of about 23.51% after being released in distilled water at 25 ℃ for 1 day, and a cumulative release rate of 62.18% at 28 days.
The coated urea obtained in this example has acceptable controlled release effects, but has the necessity and possibility of modification.
According to table 1, the cumulative release rate of fertilizer 10 days ago for this example satisfies the following curve:
y＝2.4266x+20.856 (R 2 ＝0.9982)。
the cumulative release rate of fertilizer after 10 days in this example satisfies the following curve:
y＝0.9225x+36.063 (R 2 ＝0.9971)。
where y is the cumulative release rate and x is the number of days released.
According to the prediction of the mathematical model, the estimated period of complete release of the slow release fertilizer in the embodiment is 69 days.
Example 2
This example describes a method for preparing coated urea based on 1% nano calcium carbonate modified water-based polyacrylate emulsion and coated controlled release fertilizer prepared by the method. The preparation method of the coated controlled release fertilizer in the embodiment comprises the following specific steps:
step a, selecting coating mother liquor:
100g of water-based polymer polyacrylate emulsion with solid content of (49+/-1)% is prepared in a laboratory by using a water-based process.
Step b, preparing coating liquid:
100g of distilled water is added into 0.5g of nano calcium carbonate, the mixture is stirred for 15min, then ultrasonic treatment is carried out for 30min, the mixture is slowly dripped into the stirred coating mother liquor, and stirring is continued for 15min after all dripping. The coating liquid prepared by uniformly mixing is prepared and used immediately, and the storage temperature is 5-25 ℃ and the storage time is not longer than 4 hours.
Step c, coating:
this step is the same as in example 1.
The tensile strength of the model film prepared in this example was 13.65MPa; the coated urea prepared in the embodiment has a cumulative release rate of about 21.23% after being released in distilled water at 25 ℃ for 1 day, and a cumulative release rate of 57.72% at 28 days. After nano calcium carbonate is added, the tensile strength of the water-based polymer material is increased to a certain extent, the nutrient release rate is reduced to a certain extent, and the nutrient controlled release performance of the fertilizer is improved to a certain extent.
According to table 1, the cumulative release rate of fertilizer 10 days ago for this example satisfies the following curve:
y＝2.3445x+18.789 (R 2 ＝0.9973)。
the cumulative release rate of fertilizer after 10 days in this example satisfies the following curve:
y＝0.8579x+33.515 (R 2 ＝0.996)。
where y is the cumulative release rate and x is the number of days released.
According to the prediction of the mathematical model, the estimated period of complete release of the slow release fertilizer in the embodiment is 77 days, which is prolonged by 8 days compared with the embodiment 1.
Example 3
This example describes a method for preparing coated urea based on sodium hexametaphosphate dispersed 1% nano calcium carbonate modified water-based polyacrylate emulsion, and coated controlled release fertilizer prepared by the method. The preparation method of the coated controlled release fertilizer in the embodiment comprises the following specific steps:
step a, selecting coating mother liquor:
100g of water-based polymer polyacrylate emulsion with solid content of (49+/-1)% is prepared in a laboratory by using a water-based process.
Step b, preparing coating liquid:
100g of distilled water and 0.5g of sodium hexametaphosphate are added into 0.5g of nano calcium carbonate, then the mixture is stirred for 15min, then the mixture is subjected to ultrasonic treatment for 30min, and the mixture is slowly dripped into the stirred coating mother liquor after ultrasonic treatment, and stirring is continued for 15min after all dripping. The coating liquid prepared by uniformly mixing is prepared and used immediately, and the storage temperature is 5-25 ℃ and the storage time is not longer than 4 hours.
Step c, coating:
this step is the same as in example 1.
The tensile strength of the model film prepared in this example was 16.18MPa; the coated urea prepared in the embodiment has a cumulative release rate of about 9.21% after being released in distilled water at 25 ℃ for 1 day, and a cumulative release rate of up to 37.14% at 28 days. The effect of modifying the water-based polyacrylate by using the nano calcium carbonate dispersed by hexa-metaphosphorylation is better than that of adding only nano calcium carbonate, and the tensile strength and the nutrient controlled release performance are greatly improved compared with the latter.
According to table 1, the cumulative release rate of fertilizer 10 days ago for this example satisfies the following curve:
y＝1.516x+8.1547 (R 2 ＝0.9907)。
the cumulative release rate of fertilizer after 10 days in this example satisfies the following curve:
y＝0.7692x+15.805 (R 2 ＝0.991)。
where y is the cumulative release rate and x is the number of days released.
According to the prediction of the mathematical model, the estimated period of complete release of the slow-release fertilizer in the embodiment is 109 days, which is 40 days longer than that of the embodiment 1, and the slow-release fertilizer can meet the nutrient requirements of crops with longer growing seasons in the whole growing season.
Example 4
This example describes a method for preparing coated urea based on polyethylene glycol dispersed 1% nano calcium carbonate modified water-based polyacrylate emulsion, and coated controlled release fertilizer prepared by the method. The preparation method of the coated controlled release fertilizer in the embodiment comprises the following specific steps:
step a, selecting coating mother liquor:
100g of water-based polymer polyacrylate emulsion with solid content of (49+/-1)% is prepared in a laboratory by using a water-based process.
Step b, preparing coating liquid:
100g of distilled water and 0.08g of polyethylene glycol are added to 0.5g of nano calcium carbonate, then stirring is carried out for 15min, ultrasonic treatment is carried out for 30min, the nano calcium carbonate is slowly dripped into the stirred coating mother liquor after ultrasonic treatment, and stirring is continued for 15min after all dripping. The coating liquid prepared by uniformly mixing is prepared and used immediately, and the storage temperature is 5-25 ℃ and the storage time is not longer than 4 hours.
Step c, coating:
this step is the same as in example 1.
The tensile strength of the model film prepared in this example was 16.02MPa; the coated urea prepared in the embodiment has a cumulative release rate of about 10.24% after being released in distilled water at 25 ℃ for 1 day, and a cumulative release rate of nutrients of 40.21% at 28 days. The effect of modifying the water-based polyacrylate by using the nano calcium carbonate dispersed by polyethylene glycol is better than that of only adding the nano calcium carbonate, and the tensile strength and the nutrient controlled release performance are greatly improved compared with those of the sodium hexametaphosphate.
According to table 1, the cumulative release rate of fertilizer 10 days ago for this example satisfies the following curve:
y＝1.6816x+9.3159 (R 2 ＝0.985)。
the cumulative release rate of fertilizer after 10 days in this example satisfies the following curve:
y＝0.8037x+18.233 (R 2 ＝0.9886)。
where y is the cumulative release rate and x is the number of days released.
According to the prediction of the mathematical model, the prediction period of the complete release of the slow-release fertilizer in the embodiment is 101 days, which is prolonged by 32 days compared with the embodiment 1, and the nutrient requirements of crops with longer growing seasons in the whole growing season can be met.
Example 5
This example describes a method for preparing coated urea based on sodium hexametaphosphate and polyethylene glycol coupled with dispersed 1% nano calcium carbonate modified water-based polyacrylate emulsion, and coated controlled release fertilizer prepared by the method. The preparation method of the coated controlled release fertilizer in the embodiment comprises the following specific steps:
step a, selecting coating mother liquor:
100g of water-based polymer polyacrylate emulsion with solid content of (49+/-1)% is prepared in a laboratory by using a water-based process.
Step b, preparing coating liquid:
100g of distilled water, 0.03g of sodium hexametaphosphate and 0.03g of polyethylene glycol are added to 0.5g of nano calcium carbonate, then stirring is carried out for 15min, ultrasonic treatment is carried out for 30min, the nano calcium carbonate is slowly dripped into the stirred coating mother liquor after ultrasonic treatment, and stirring is continued for 15min after all dripping. The coating liquid prepared by uniformly mixing is prepared and used immediately, and the storage temperature is 5-25 ℃ and the storage time is not longer than 4 hours.
Step c, production of coated fertilizer:
this step is the same as in example 1.
The tensile strength of the model film prepared in this example was 16.92MPa; the coated urea prepared in the embodiment has a cumulative release rate of about 8.62% after being released in distilled water at 25 ℃ for 1 day, and a cumulative release rate of nutrients of 31.87% at 28 days. The effect of the nano calcium carbonate modified water-based polyacrylate by using two dispersing agents of sodium hexametaphosphate and polyethylene glycol is better than that of the two dispersing agents which are added independently, the addition amount is obviously reduced compared with that of the two dispersing agents which are added independently, and the tensile strength and nutrient controlled release performance of the material are greatly improved.
According to table 1, the cumulative release rate of fertilizer 10 days ago for this example satisfies the following curve:
y＝1.28x+7.5022 (R 2 ＝0.9932)。
the cumulative release rate of fertilizer after 10 days in this example satisfies the following curve:
y＝0.6366x+14.405 (R 2 ＝0.9857)。
where y is the cumulative release rate and x is the number of days released.
According to the prediction of the mathematical model, the estimated period of complete release of the slow-release fertilizer in the embodiment is 134 days, which is prolonged by 65 days compared with the embodiment 1, and the slow-release fertilizer can meet the nutrient requirements of crops with longer growing seasons in the whole growing season.
Example 6
This example describes a method for preparing coated urea based on a 3% nano calcium carbonate modified water-based polyacrylate emulsion dispersed in sodium hexametaphosphate and polyethylene glycol, and coated controlled release fertilizer prepared by the method. The preparation method of the coated controlled release fertilizer in the embodiment comprises the following specific steps:
step a, selecting coating mother liquor:
100g of water-based polymer polyacrylate emulsion with solid content of (49+/-1)% is prepared in a laboratory by using a water-based process.
Step b, preparing coating liquid:
100g of distilled water, 0.03g of sodium hexametaphosphate and 0.03g of polyethylene glycol are added to 1.5g of nano calcium carbonate, then stirring is carried out for 15min, ultrasonic treatment is carried out for 30min, the nano calcium carbonate is slowly dripped into the stirred coating mother liquor after ultrasonic treatment, and stirring is continued for 15min after all dripping. The coating liquid prepared by uniformly mixing is prepared and used immediately, and the storage temperature is 5-25 ℃ and the storage time is not longer than 4 hours.
Step c, coating:
this step is the same as in example 1.
The tensile strength of the model film prepared in this example was 16.51MPa; the cumulative release rate of the fertilizer after being released in distilled water at 25 ℃ for 1 day is about 13.03%, and the cumulative release rate of nutrients at 28 days reaches 45.79%.
According to table 1, the cumulative release rate of fertilizer 10 days ago for this example satisfies the following curve:
y＝1.8906x+11.377 (R 2 ＝0.9991)。
the cumulative release rate of fertilizer after 10 days in this example satisfies the following curve:
y＝0.8711x+21.707 (R 2 ＝0.997)。
where y is the cumulative release rate and x is the number of days released.
According to the prediction of the mathematical model, the estimated period of complete release of the slow release fertilizer in the embodiment is 89 days, which is 20 days longer than that of the embodiment 1.
Experiments show that the modification effect of the nano calcium carbonate on the water-based polyacrylate is not as good as possible despite the effect of the dispersing agent, and when the addition amount is too high, a certain agglomeration phenomenon can occur, so that the dispersion effect of the nano calcium carbonate in the water-based polymer is reduced, and the modification effect of the nano calcium carbonate is further reduced. It can be seen that the amount of nano calcium carbonate used for modification and the pretreatment mode are key factors for success or failure of modification.
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that the above-mentioned preferred embodiment should not be construed as limiting the invention, and the scope of the invention should be defined by the appended claims. It will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the spirit and scope of the invention, and such modifications and adaptations are intended to be comprehended within the scope of the invention.

Claims (3)

1. The coated controlled release fertilizer comprises an inner layer fertilizer core particle and an outer layer polymer coating material, and is characterized in that the polymer coating material is a nano calcium carbonate modified water-based polyacrylate emulsion solid;
the nano calcium carbonate modified water-based polyacrylate emulsion is prepared by the following steps:
slowly adding the nano calcium carbonate aqueous solution dispersion system into the water-based polyacrylate emulsion, fully stirring, and sieving;
in the nano calcium carbonate aqueous solution dispersion system, the components in parts by weight are as follows: 0.005-2.5 parts of nano calcium carbonate, 0.01-1 part of sodium hexametaphosphate, 0.01-0.3 part of polyethylene glycol and 100 parts of deionized water;
the solute addition amount in the nano calcium carbonate aqueous solution dispersion system accounts for 0.01% -5% of the dry matter mass of the water-based polyacrylate;
the mass of the dry matter of the modified polymer coating material accounts for 2.5-15% of that of the coated controlled release fertilizer.
2. The coated controlled release fertilizer of claim 1, wherein the aqueous dispersion of nano calcium carbonate is prepared by the steps of:
adding nano calcium carbonate into deionized water, then adding sodium hexametaphosphate and polyethylene glycol, and fully stirring and mixing to obtain a nano calcium carbonate aqueous solution dispersion system.
3. The coated controlled release fertilizer of claim 2, wherein the stirring is magnetic stirrer stirring for 15min and the mixing is performed by ultrasonic treatment for 30min.
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CN1948241B (en) * 2005-10-13 2010-04-21 南京理工大学 Polymer composite coated slow release fertilizer
CN102924164B (en) * 2012-04-24 2014-07-09 中国科学院南京土壤研究所 Water-based polymer polyacrylate coated fertilizer modified based on biochar, and preparation method thereof
CN106927951B (en) * 2017-01-23 2020-06-16 中国科学院南京土壤研究所 Based on water dispersion nano SiO2Modified water-based polyacrylate coated controlled release fertilizer and preparation method thereof
CN108585474A (en) * 2018-06-06 2018-09-28 石家庄学院 A kind of preparation method of anti-bacteria ceramic glaze filling nano-calcium carbonate

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