WO2019153776A1 - 一种多层包膜结构缓控释肥料及其制备方法 - Google Patents

一种多层包膜结构缓控释肥料及其制备方法 Download PDF

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Publication number
WO2019153776A1
WO2019153776A1 PCT/CN2018/109655 CN2018109655W WO2019153776A1 WO 2019153776 A1 WO2019153776 A1 WO 2019153776A1 CN 2018109655 W CN2018109655 W CN 2018109655W WO 2019153776 A1 WO2019153776 A1 WO 2019153776A1
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Prior art keywords
fertilizer
layer
coating
envelope structure
controlled release
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PCT/CN2018/109655
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English (en)
French (fr)
Inventor
胡建民
刘小勇
胡锦哲
万培坤
白云涛
胡书民
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郑州高富肥料有限公司
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Application filed by 郑州高富肥料有限公司 filed Critical 郑州高富肥料有限公司
Priority to EP18904981.0A priority Critical patent/EP3715336A4/en
Priority to US16/331,496 priority patent/US20210380502A1/en
Publication of WO2019153776A1 publication Critical patent/WO2019153776A1/zh

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    • 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
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05B—PHOSPHATIC FERTILISERS
    • C05B19/00—Granulation or pelletisation of phosphatic fertilisers, other than slag
    • 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
    • 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
    • C05G5/10—Solid or semi-solid fertilisers, e.g. powders
    • C05G5/12—Granules or flakes
    • 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

Definitions

  • the invention relates to the field of fertilizers, and in particular to a multi-layered envelope structure controlled release fertilizer and a preparation method thereof.
  • the growth of crops begins from seed to maturity, and undergoes processes such as emergence, tillering, jointing, booting, flowering, and seeding, including two stages of nutrient growth and reproductive growth, each of which requires different amounts of nutrients.
  • the original nutrients in the soil generally do not meet the nutritional needs of the crop, and a certain proportion of fertilizer is required.
  • urea is nitrogen fertilizer
  • calcium phosphate and calcium are calcium phosphate
  • potassium phosphate is phosphorus and potassium, etc.
  • Compound fertilizers can only meet the needs of certain aspects of a certain stage of the crop, and can not meet the reasonable needs of nutrients in the whole growth cycle of the crop.
  • the object of the present invention is to provide a multi-layered envelope structure controlled release fertilizer which can release the nutrient elements in the fertilizer in time to meet the different nutrient requirements of different crops at different growth stages, and achieve the purpose of one fertilization without top dressing.
  • Another object of the present invention is to provide a method for preparing a multi-layered envelope structure controlled release fertilizer which is simple and easy to manufacture and can be applied to large-scale agriculture.
  • the invention provides a multi-layered envelope structure controlled release fertilizer, comprising a layer of coated fertilizer layer and a coating layer, the fertilizer layer and the coating layer are spaced apart, the fertilizer layer is provided with at least two layers, and the coating layer is provided with at least one Layer, and one layer of the fertilizer layer is used as a fertilizer core; the fertilizer layer contains at least one of nitrogen fertilizer, phosphate fertilizer and potassium fertilizer, the coating layer is polyurea formaldehyde, the raw materials of polyurea formaldehyde are urea and formaldehyde, urea and the formaldehyde The molar ratio is 1-2.5:1, and the polyurea formaldehyde contains at least polyurea formaldehyde having 2 to 5 carbon atoms.
  • the invention provides a preparation method of a multi-layered envelope structure controlled release fertilizer, comprising the following steps:
  • the fertilizer layer and the fertilizer corresponding to the coating layer are applied to the periphery of the fertilizer core in a predetermined order to form layer-covered fertilizer particles.
  • the multi-layered envelope structure controlled release fertilizer consists of a fertilizer layer and a coating layer, and the fertilizer layer and the coating layer are arranged at intervals, and the layers are coated to form a global shape.
  • the ratio of nitrogen, phosphorus, potassium and medium and trace elements in the fertilizer layer can be designed.
  • the coating layer of polyurea formaldehyde according to the growth needs of different crops, the coated fertilizer can be slowly and timely released according to the fertilizer requirement of the crop. Part of the water-soluble nutrient element in the coated fertilizer layer can be released by the pore formed by the water-soluble portion of the coating layer to be absorbed by the crop.
  • the water-insoluble portion of the coating layer slowly decomposes under the action of microorganisms in the soil, releasing the remaining undissolved fertilizer in the fertilizer layer for absorption by the crop.
  • the layers of the envelope layer decompose, the layer of coated fertilizer is released until the entire fertilizer granules are completely dispersed in the soil. Since the coating layer itself is also a fertilizer, the fertilizer does not produce any residue while satisfying the growth of the crop.
  • FIG. 1 is a cross-sectional view showing a first multi-layered envelope structure controlled release fertilizer according to an embodiment of the present invention
  • FIG. 2 is a cross-sectional view showing a second multi-layered envelope structure controlled release fertilizer according to an embodiment of the present invention
  • Figure 3 is a schematic view showing the production process flow of Embodiment 2 of the present invention.
  • Icon 100-fertilizer core; 110-fertilizer layer; 120-envelope layer; 310-powder powder tank; 311-dusting machine; 320-first sizing tank; 330-second sizing tank; 340-first reactor 350-second reactor; 360-liquid slurry pump; 370-drum granulator; 380-dryer; 390-sieving machine.
  • the present invention provides a controlled release fertilizer (or a multi-layered envelope structure controlled release fertilizer) comprising: a layer of coated fertilizer layer 110 and a coating layer 120, the fertilizer layer 110 being spaced from the coating layer 120
  • the fertilizer layer 110 is provided with at least two layers, the coating layer 120 is provided with at least one layer, and one layer of the fertilizer layer 110 is used as the fertilizer core 100;
  • the fertilizer layer 110 contains at least one of nitrogen fertilizer, phosphate fertilizer and potassium fertilizer, and the coating layer 120 is polyurea formaldehyde, the raw material of polyurea formaldehyde is urea and formaldehyde, the molar ratio of urea to formaldehyde is 1-2.5:1, and the polyurea formaldehyde contains at least polyurea formaldehyde having 2 to 5 carbon atoms.
  • the polyurea formaldehyde may have a carbon number of 2 to 3, including dimethylol urea and monomethicone which are soluble in cold water, or 2 to 5, including polyurea formaldehyde which can be dissolved in cold water.
  • the polyurea formaldehyde comprises at least a polyurea formaldehyde having from 2 to 5 carbon atoms.
  • the fertilizer layer 110 contains a fertilizer such as nitrogen fertilizer, phosphate fertilizer or potassium fertilizer
  • the single component may be a fertilizer layer 110.
  • the fertilizer layer 110 contains two of nitrogen fertilizer, phosphate fertilizer and potassium fertilizer
  • the mixture of the two components is a fertilizer layer 110; or the two components are a single layer, and the two layers together form a fertilizer layer 110.
  • the mixture of the three components is a fertilizer layer 110; or the mixture of the two components is one layer, and the other component is one layer, the two layers Together, a layer of fertilizer layer 110 is formed; or the three components are a single layer, and the three layers collectively form a layer of fertilizer 110.
  • the NPK fertilizer may be quick-acting urea, ammonium sulfate, ammonium hydrogen phosphate, potassium sulfate, or a mixture of sustained-release urea formaldehyde, isobutylidene diurea, oxalic acid amide, and the like. It should be noted that the NPK fertilizer itself may contain other medium and trace elements, and may also be some specially added medium and trace elements.
  • the multi-layer envelope structure slow-release fertilizer is coated by the fertilizer layer 110 and the coating layer 120 to form a global shape, and the fertilizer layer 110 and the coating layer 120 are spaced apart according to different soil structures, different climatic conditions, and different crops.
  • the proportion of nutrients such as nitrogen, phosphorus and potassium and other medium and trace elements in the fertilizer layer 110 is designed.
  • the polyurea formaldehyde of the coating layer 120 the fertilizer in the coated fertilizer layer 110 can be slowly and timely released according to the fertilizer requirement of the crop according to the growth requirements of different crops.
  • Part of the water-soluble nutrient element in the coated fertilizer layer 110 can be released by the pores formed by the water-soluble portion of the coating layer 120 to be absorbed by the crop.
  • the water-insoluble portion of the coating layer 120 slowly decomposes under the action of microorganisms in the soil, releasing the remaining undissolved fertilizer in the fertilizer layer 110 for absorption by the crop. As the layers of the coating layer 120 decompose, the layer of the coated fertilizer layer 110 is released until the entire fertilizer particles are completely dispersed in the soil. Since the polyurea formaldehyde of the coating layer 120 itself is also a fertilizer, the fertilizer does not cause any residue while satisfying the growth of the crop.
  • the multi-layered envelope structure controlled release fertilizer of the embodiment of the invention can meet the needs of all nutrients in the whole growth cycle of the crop, and the nutrient release can be tailored according to the crop, so that the nutrient release time and intensity of the fertilizer are the same as the crops.
  • the laws are basically synchronized. When the crop needs a lot of nutrients, it can be supplied quickly and efficiently. When the amount is small, it can be provided slowly.
  • the medium and trace elements can also be designed and placed on different fertilizer layers 110. This slow release effect improves fertilizer utilization, reduces fertilizer loss and/or is fixed. Achieve a full base fertilizer without the need for top dressing.
  • composition and content of the fertilizer core 100, the fertilizer layer 110, and the carbon chain length and coating thickness of the coating layer 120 can be calculated and determined according to the fertilizer requirements of different crops under different soil and climatic conditions.
  • the fertilizer requirement law is determined according to the crop fertilizer efficiency test done by scientific research institutions in the country and around the world, or the soil test and fertilizer efficiency test done by the production unit.
  • the polyurea formaldehyde is mainly prepared by the following steps: mixing urea and formaldehyde in a molar ratio of 1-2.5:1, adjusting the pH of the reaction system to 7.5-11.5, the temperature of 50 ° C to 75 ° C, and then adjusting the pH.
  • the value is from 2.5 to 5.5.
  • the traditional polyurea formaldehyde is prepared by dissolving the granular urea in water first, then adding the formaldehyde solution, heating the mixed solution to a certain temperature, adjusting the pH value to cause methylolation. reaction. After the reaction is completed, the pH and temperature are adjusted to cause polymerization.
  • the polyurea formaldehyde prepared by the conventional method is a suspension, and the polymerization reaction completely occurs in water.
  • the preparation method has a water content of more than 70% after the completion of the polymerization reaction, and needs to be discharged, cooled, centrifuged or plated to filter out part of the water, and the filter cake also contains 35% to 45% of water, which is part of the water. It must be removed by high temperature heating of the dryer 380, and finally a polyurea formaldehyde mixed in a powder form and a block form is obtained. Since the polyurea formaldehyde prepared by the conventional method has a high water content, it cannot be sprayed into a film alone. Although it can be encapsulated into film after mixing with other binders, cross-linking and entanglement do not occur between molecules. The structure of the membrane is not dense enough, and it is easy to disperse and disintegrate in the soil. freed.
  • the urea does not need to be dissolved in water but dissolved and reacted in the formaldehyde solution, and the prepared mixed solution of methylol urea and urea has a low water content.
  • the polymerization does not occur in the aqueous phase, but is sprayed onto the fertilizer core 100 or the surface of the fertilizer layer 110, and the polymer is solidified into a film while the water evaporates, between the molecules.
  • Cross-linking and entanglement occur, the structure of the membrane is dense, and it does not disintegrate in the soil, thereby achieving the purpose of controlling the slow release of various nutrients in the fertilizer core 100 and the fertilizer layer 110.
  • the molar ratio of urea to formaldehyde is from 1.2 to 2.2:1 or from 1.5 to 2:1 or from 1.6 to 1.8:1.
  • the thickness of each of the coating layers 120 in the multi-layered envelope structure controlled release fertilizer and its composition determine the release time of the coated fertilizer.
  • the multi-layered envelope structure controlled release fertilizer comprises at least two layers of coating layer 120, at least two of which have the same thickness. In some embodiments of the invention, at least two layers of coating layer 120 have different thicknesses.
  • the polyurea formaldehyde of at least two layers of coating layer 120 has the same carbon chain length component. In some embodiments, the polyurea formaldehyde of at least two layers of coating layer 120 has components of different carbon chain lengths.
  • polyurea formaldehyde is a sustained-release nitrogen fertilizer containing four forms of nitrogen in urea formaldehyde, including partially unreacted excess urea, monomethylolurea, dimethylolurea, and monomethicone which are soluble in cold water. Dimer triuret, trimethylidene tetraurea and hot water which are insoluble in cold water and soluble in hot water are also insoluble in urea having a carbon chain length exceeding four carbon atoms.
  • the main component of polyurea formaldehyde is a series of chain length urea and formaldehyde condensate such as dimethyl triuret and trimethylidene tetraurea.
  • the condensate is slightly soluble in water, can control the release of nitrogen and prevent nitrogen loss. It can be slowly decomposed by microorganisms in the soil.
  • the use of polyurea formaldehyde as the coating layer 120 can control the release amount of the coated fertilizer, so that it can be fully absorbed and utilized by the plant in time.
  • the polyurea formaldehyde is a slow release fertilizer containing the above four forms of nitrogen. In some embodiments, the polyurea formaldehyde is a slow release fertilizer containing the first three forms of nitrogen. In some embodiments, the polyurea formaldehyde is a slow release fertilizer containing the latter three forms of nitrogen. In some embodiments, the polyurea formaldehyde is nitrogen which is soluble in hot water and which is soluble in hot water, and nitrogen which is insoluble in hot water, a slow release fertilizer of two forms of nitrogen.
  • the term "fertilizer layer 110" contains at least one of nitrogen fertilizer, phosphate fertilizer and potassium fertilizer.
  • the fertilizer layer 110 comprises: (a) at least one macronutrient fertilizer selected from the group consisting of nitrogen fertilizers, phosphate fertilizers, or potash fertilizers; and optionally (b) at least one trace element fertilizer.
  • the fertilizer layer 110 comprises: (a) a plurality of elemental fertilizer nitrogen fertilizers, phosphate fertilizers, and potassium fertilizers; and optionally (b) at least one trace element fertilizer.
  • the trace element fertilizer is selected from the group consisting of boron fertilizer, zinc fertilizer, molybdenum fertilizer, iron fertilizer, manganese fertilizer, copper fertilizer, and the like, or a combination thereof.
  • the fertilizer layer 110 is a fertilizer other than the individual polyurea formaldehyde.
  • the polyurea formaldehyde itself as the coating layer 120 is itself a nitrogen fertilizer.
  • the nitrogen fertilizer in the coated fertilizer layer 110 may be slow-acting or quick-acting one or more of polyurea formaldehyde, urea, isobutylidene diamine, butylene diurea, oxalic acid amide, ammonium sulfate and ammonium nitrate. fertilizer.
  • coated fertilizer layer 110 polyurea formaldehyde and other nutrient elements such as Ca, Mg, and the like may be mixed.
  • other elements such as Ca and Mg may be mixed in the phosphate fertilizer and the potassium fertilizer, so that when the polyurea formaldehyde as the coating layer 120 is slowly decomposed, the crop is provided with other nutrients it needs.
  • the multilayer envelope structure slow release fertilizer comprises one or more layers of coating 120.
  • the multi-layered envelope structure controlled release fertilizer comprises at least two layers of coating layer 120, or at least three layers of coating layer 120, or at least four layers of coating layer 120.
  • the outermost layer of the multi-layered envelope structure controlled release fertilizer is a polyurea formaldehyde envelope layer 120, please refer to FIG.
  • the outermost layer of the multi-layered envelope structure controlled release fertilizer is a polyurea formaldehyde containing fertilizer layer 110, see FIG.
  • the outermost layer of the multi-layered envelope structure controlled release fertilizer is a fertilizer layer 110 that does not contain polyurea formaldehyde.
  • the fertilizer core 100 may be a common chemical fertilizer purchased from the market, or may be a fertilizer component arranged in proportion, or may be a granular fertilizer containing polyurea formaldehyde.
  • the fertilizer component may include urea, monoamine phosphate, and diamine phosphate. At least one of potassium dihydrogen phosphate, potassium chloride, potassium sulfate, potassium nitrate, ammonium sulfate, and ammonium chloride.
  • the multi-layered envelope structure controlled release fertilizer is configured such that the release amount of each fertilizer element is substantially consistent with the fertilizer requirement of the corn crop (herein referred to as "corn special fertilizer").
  • corn-specific fertilizers include from the inside out:
  • Fertilizer core 100 including urea, monoammonium phosphate, potassium chloride, nitrogen accounts for about 20% of total nitrogen in the whole fertilizer granule, phosphorus accounts for 15% of total phosphorus, and potassium accounts for 5% of total potassium.
  • Fertilizer layer 110 including urea, monoammonium phosphate, potassium chloride. Nitrogen accounts for 50% of total nitrogen in the entire fertilizer granule, phosphorus accounts for 65% of total phosphorus, and potassium accounts for 80% of total potassium.
  • Fertilizer layer 110 including urea, monoammonium phosphate, potassium chloride, polyurea formaldehyde, zinc sulfate, and dolomite powder. Nitrogen accounts for 13% of total nitrogen in the entire fertilizer granule, phosphorus accounts for 20% of total phosphorus, and potassium accounts for 15% of total potassium.
  • the multi-layered envelope structure controlled release fertilizer is configured such that the release amount of each fertilizer element is substantially the same as the fertilizer requirement of the wheat crop (herein referred to as "wheat-specific fertilizer").
  • the wheat-specific fertilizer includes from the inside to the outside:
  • Fertilizer core 100 including urea, monoammonium phosphate, potassium chloride, nitrogen accounts for about 15% of total nitrogen in the whole fertilizer granule, phosphorus accounts for 20% of total phosphorus, and potassium accounts for 30% of total potassium.
  • Fertilizer layer 110 including urea, monoammonium phosphate, potassium chloride. Nitrogen accounts for 30% of total nitrogen in the entire fertilizer granule, phosphorus accounts for 40% of total phosphorus, and potassium accounts for 50% of total potassium.
  • Fertilizer layer 110 including urea, monoammonium phosphate, potassium chloride, zinc sulfate, borax, dolomite powder. Nitrogen accounts for 25% of total nitrogen in the entire fertilizer granule, phosphorus accounts for 40% of total phosphorus, and potassium accounts for 20% of total potassium.
  • the multi-layered envelope structure controlled release fertilizer is constructed such that the release amount of each fertilizer element is substantially the same as the fertilizer requirement of the rice crop (herein referred to as "rice-specific fertilizer").
  • the rice-specific fertilizer includes from the inside to the outside:
  • Fertilizer core 100 including urea, diammonium phosphate, potassium chloride, nitrogen accounts for about 10% of the total nitrogen of the entire fertilizer granule, phosphorus accounts for 5% of total phosphorus, and potassium accounts for 10% of total potassium.
  • Fertilizer layer 110 including urea, diammonium phosphate, potassium chloride. Nitrogen accounts for 10% of total nitrogen in the entire fertilizer granule, phosphorus accounts for 5% of total phosphorus, and potassium accounts for 20% of total potassium.
  • Fertilizer layer 110 including urea, diammonium phosphate, potassium chloride. Nitrogen accounts for 20% of total nitrogen in the entire fertilizer granule, phosphorus accounts for 20% of total phosphorus, and potassium accounts for 30% of total potassium.
  • Fertilizer layer 110 including urea, calcium magnesium phosphate fertilizer, diammonium phosphate, potassium chloride, polyurea formaldehyde. Nitrogen accounts for 33% of total nitrogen in the entire fertilizer granule, phosphorus accounts for 70% of total phosphorus, and potassium accounts for 40% of total potassium.
  • the multi-layered envelope structure controlled release fertilizer of the embodiment of the invention has the quick, medium and long-acting NPK nutrient distribution, and achieves a reasonable combination of various elements for controlled release.
  • Quick-acting fertilizers such as urea, ammonium sulfate, monoammonium phosphate, diammonium phosphate, potassium chloride, etc. in multi-layer envelope structure controlled release fertilizer can be quickly released for crop absorption, and calcium magnesium phosphate fertilizer provides soluble phosphorus and calcium magnesium silicon.
  • the polyurea formaldehyde in the fertilizer can provide intermediate and long-acting nitrogen nutrients through soil microbial decomposition, which can meet the nutrient demand of the whole slow growth cycle of the crop, and can be mixed with phosphorus and other medium and trace elements and urea formaldehyde. Control release.
  • the methylol urea has an adsorption function, which promotes the combination of fertilizer nutrients and soil particles, adsorbs on the roots of the crops, forms a gel-like chelate, thereby reducing nutrient loss and reaching nutrients. It is fully absorbed by crops and improves fertilizer utilization. Compared with other controlled release fertilizers, the product is less affected by climate (temperature) and soil conditions during nutrient release, and the fertilizer effect is more stable and lasting.
  • a method of preparing the above multi-layered envelope structure controlled release fertilizer includes the steps of: applying fertilizer corresponding to the fertilizer layer 110 and the coating layer 120 to the periphery of the fertilizer core 100 in a predetermined order to form layer-covered fertilizer particles.
  • the application is carried out by spraying, rolling pellets or a combination thereof.
  • the main steps of the spraying method include: separately preparing coating material liquids of different carbon chain lengths in a plurality of reaction kettles, and proportioning in the plurality of chemical pulp tanks or powder discharging tanks 310.
  • the composition of each fertilizer layer 110 is configured.
  • the ingredients as the fertilizer core 100 are first fed to the drum granulator 370, and then the coating material liquid of different carbon chain lengths in the plurality of continuous reaction tanks, the chemical tank or the fertilizer layer in the powder tank 310
  • the 110 components are sequentially sprayed into the drum granulator 370 in a predetermined order so that the fertilizer granules are continuously increased in thickness according to the set fertilizer layer 110 and the coating layer 120 until the target is reached.
  • spraying sequences and spraying times can form the fertilizer layer 110 and the coating layer 120 of different thicknesses to form controlled fertilizers with different fertilizer effects.
  • spraying may be carried out intermittently or continuously according to the preparation of the fertilizer, and the granulation drying may also be carried out in different granulation dryers 380, respectively.
  • one layer of the fertilizer layer 110 may be a fertilizer layer 110 which is sprayed into one or more times and sprayed in multiple layers.
  • the fertilizers sprayed multiple times may be different or the same.
  • the coating layer 120 may be a coating layer 120 which is sprayed into one or more times and sprayed multiple times.
  • the composition of the polyurea formaldehyde slow-release fertilizer which is sprayed multiple times may be different or the same. of.
  • the preparation of the multi-layered envelope structure controlled-release fertilizer comprises a reaction kettle, a slurry tank or (and) powder-slurry tank 310, a granulation dryer 380 and its supporting facilities, and is characterized in that it can control each layer of fertilizer according to a design procedure.
  • the entire process can be carried out batchwise or continuously, and can be produced on a large scale.
  • the formed fertilizer granules are sprayed with hot air into the dryer 380 for drying, and then sieved, cooled, packaged, and stored.
  • the coating layer 120 polyurea formaldehyde is obtained by in-situ polymerization while evaporating and removing water on the surface of the fertilizer layer 110 under acidic conditions by a coating material liquid containing methylol urea.
  • urea and formaldehyde are formed into a methylol urea at a pH of 7.5 to 11.5 and a temperature of 50 to 75 ° C, and then the pH is adjusted to 2 to 5.5 to form a polyurea formaldehyde coating raw material liquid.
  • the coating material liquid is sprayed on the surface of the fertilizer core 100 to form the coating layer 120, and then the second layer of fertilizer is sprayed on the surface of the coating layer 120 to form the fertilizer layer 110, and then the coating material liquid is sprayed to form the second coating layer 120. Loop in turn.
  • the polyurea formaldehyde coating raw material liquid may be mixed and sprayed as a fertilizer layer 110 component together with a fertilizer as needed.
  • the fertilizer core 100 can be preheated.
  • the fertilizer core 100 is preheated to 60 ° C - 120 ° C, or 65 ° C - 105 ° C, or 70 ° C - 100 ° C, or 80 ° C - 90 ° C.
  • polyurea formaldehyde Since polyurea formaldehyde has a carbon chain length of 2-5, the water content is only 35%-45%, and the concentration is high.
  • the polyurea formaldehyde carbon chain length for forming the coating layer 120 can be varied by adjusting the molar ratio of urea to formaldehyde, the pH of the reaction system, and the temperature.
  • the water content of the coating material liquid is from 35% to 45% by weight.
  • the preparation method of the controlled release fertilizer according to the embodiment of the invention has the characteristics of short process route and low energy consumption. Industrial production can be carried out on a large scale.
  • the fertilizer requirement of corn on the fluvo-aquic soil in the alluvial plain of the Yellow River and the test results of the soil in the experimental field were used to understand the release and utilization of various nutrients in the multi-layer envelope structure controlled release fertilizer in the previous plot.
  • the fertilizer core 100, each fertilizer layer 110, and the coating layer 120 are designed, and the corn special fertilizer with the content of 27-8-5 is produced according to the design, and the field test is carried out.
  • the main raw materials of fertilizer are: urea, 37% formaldehyde solution, powdered monoammonium phosphate with a content of 11-44-0, potassium chloride, zinc sulfate and dolomite powder with a content of 0-0-60.
  • the second layer of fertilizer layer 110 containing nitrogen, phosphorus and potassium are respectively 13%, 20%, 15% of the total NPK of the fertilizer granules.
  • the nitrogen content of the first coating layer 120 accounts for 7% of the total nitrogen of the fertilizer particles, and the nitrogen content of the second coating layer 120 accounts for 10% of the total nitrogen of the fertilizer particles.
  • the polyurea formaldehyde slow release nitrogen content accounts for 20% of the total nitrogen of the fertilizer granules.
  • the fertilizer core 100 is: urea, monoammonium phosphate, potassium chloride, and the fertilizer core 100 is provided according to the mass ratio of 26.8:6.6:1.
  • urea, monoammonium phosphate and potassium chloride are used in advance to produce fertilizer granules having a diameter of about 1.5 mm for use.
  • Reaction kettle Put urea and formaldehyde into the reaction kettle at a molar ratio of 2:1, heat while stirring, add sodium carbonate solution, adjust the pH to 8.5-9.5, and raise the temperature to 50-70 °C to control the reaction time. 45min or so. Add dilute sulfuric acid solution, adjust the pH to 2.5 ⁇ 4.5, and control the reaction time for about 25min.
  • the first chemical slurry tank 320 265 kg of urea, 118 kg of monoammonium phosphate, and 67 kg of potassium chloride are poured into a tank which has been added with water and continuously stirred, and heated to 95 ° C for use.
  • Powder pulverization tank 310 50 kg of urea already treated, 36 kg of monoammonium phosphate, 13 kg of potassium chloride, 5 kg of zinc sulfate, and 165 kg of dolomite powder are poured into a tank and mixed for use.
  • the calculated amount of fertilizer core 100 pellets is first fed to a drum granulator 370, and the fertilizer pellets are preheated to about 90 °C with hot air at 300 °C.
  • the coating liquid in the reaction vessel is sprayed onto the surface of the fertilizer core 100 by a slurry pump 360 to cause polymerization on the surface of the particles and solidified, and sprayed for 7 minutes, while removing moisture by evaporation by hot air to form a first coating layer 120. .
  • the slurry pump 360 of the first chemical slurry tank 320 is started, and the slurry containing urea, monoammonium phosphate and potassium chloride is sprayed onto the particles rolling in the drum granulator 370 to make it uniformly adhered and covered.
  • a layer of coating layer 120 was sprayed for 15 minutes while moisture was removed by hot air evaporation to form a first layer of fertilizer layer 110.
  • the slurry pump 360 that starts the reaction kettle sprays the coating liquid onto the surface of the first fertilizer layer 110, causes polymerization on the surface of the particles to be solidified, and is sprayed for 12 minutes, and simultaneously removes moisture by hot air evaporation to form a second coating film.
  • Layer 120 is the slurry containing urea, monoammonium phosphate and potassium chloride
  • the powder pulverizer 311 of the powder pulverizing tank 310 is started, and the urea, the monoammonium phosphate, the potassium chloride, the zinc sulfate and the dolomite powder which have been processed and mixed are uniformly fed into the granulator, and the reactor liquid slurry pump 360 is started to be gathered.
  • the urea formaldehyde is sprayed into the granulator, and the urea formaldehyde and the powder are adhered to the surface of the second coating layer 120 until the material is added, and the moisture is evaporated by hot air to form the second fertilizer layer 110. Then sieve, cool, and package.
  • the fertilizer requirement of wheat on the fluvo-aquic soil in the alluvial plain of the Yellow River the test results of the soil in the experimental field, and the release and utilization of various nutrients in the multi-layer envelope structure controlled release fertilizer in the previous plot test
  • the fertilizer core 100, each fertilizer layer 110, and the coating layer 120 are designed, and the wheat special fertilizer with the content of 25-12-8 is produced according to the design, and the field test is carried out.
  • the raw materials of fertilizer mainly include: urea, 37% formaldehyde solution, powdered monoammonium phosphate with a content of 11-44-0, potassium chloride, zinc sulfate, borax and dolomite powder with a content of 0-0-60.
  • the second layer of fertilizer layer 110 containing nitrogen, phosphorus and potassium are respectively 25%, 40%, 20% of the total NPK of the fertilizer granules.
  • the nitrogen content of the first coating layer 120 accounts for 10% of the total nitrogen of the fertilizer particles
  • the nitrogen content of the second coating layer 120 accounts for 12% of the total nitrogen of the fertilizer particles
  • the nitrogen content of the third coating layer 120 accounts for the fertilizer. 8% of total particulate nitrogen.
  • the outermost layer is a third layer of encapsulating layer 120 of polyurea formaldehyde.
  • the polyurea formaldehyde slow release nitrogen content accounts for 30% of the total nitrogen of the fertilizer granules.
  • the fertilizer core 100 is: urea, monoammonium phosphate, potassium chloride, and the fertilizer core 100 is provided according to the mass ratio of 1.7:1.4:1.
  • urea, monoammonium phosphate and potassium chloride are used in advance to produce fertilizer granules having a diameter of about 1.5 mm for use.
  • First reactor 340 urea and formaldehyde are placed in the first reactor 340 in a molar ratio of 2.2:1, heated while stirring, and a sodium carbonate solution is added thereto, the pH is adjusted to 8.5 to 9.5, and the temperature is raised to 50 to 50. At 70 ° C, the reaction time was controlled for about 45 minutes. Add dilute sulfuric acid solution, adjust the pH to 2.5 ⁇ 4.5, and control the reaction time for about 25min.
  • the second reactor 350 urea and formaldehyde are placed in the second reaction kettle 350 at a molar ratio of 1.8:1, heated while stirring, and a sodium carbonate solution is added thereto, the pH is adjusted to 8.5 to 9.5, and the temperature is raised to 50 to 50. 70 ° C, control reaction time of about 40min. Add dilute sulfuric acid solution, adjust the pH to 2.5 ⁇ 4.5, and control the reaction time for about 20min.
  • the first chemical slurry tank 320 137 kg of urea, 110 kg of monoammonium phosphate, and 67.5 kg of potassium chloride are poured into a tank which has been added with water and continuously stirred, and heated to 95 ° C for use.
  • the second chemical slurry tank 330 110 kg of urea, 110 kg of monoammonium phosphate, and 27 kg of potassium chloride are poured into a tank which has been added with water and continuously stirred, and heated to 95 ° C for use.
  • Powder pulverizing tank 310 Pour 5 kg of zinc sulphate, 55 kg of borax and 75 kg of dolomite powder into the tank and mix for use.
  • the calculated amount of fertilizer core 100 pellets is first fed to a drum granulator 370, and the fertilizer pellets are preheated to about 100 °C with hot air at 350 °C.
  • the coating liquid in the first reaction kettle 340 is sprayed onto the surface of the particle of the fertilizer core 100 by the liquid slurry pump 360, and is polymerized and solidified on the surface of the particle, sprayed for 9 minutes, and simultaneously evaporated by hot air to form a first layer package. Film layer 120.
  • the slurry pump 360 of the first chemical slurry tank 320 is started, and the slurry containing urea, monoammonium phosphate and potassium chloride is sprayed onto the particles rolling in the drum granulator 370 to make it uniformly adhered and covered.
  • a layer of coating layer 120 was sprayed for 13 minutes while moisture was removed by hot air evaporation to form a first layer of fertilizer layer 110.
  • the slurry pump 360 that starts the second reaction kettle 350 sprays the coating liquid onto the surface of the first fertilizer layer 110, causes polymerization on the surface of the particles to be solidified, and is sprayed for 14 minutes, and simultaneously removes moisture by hot air to form a second. Layer coating layer 120.
  • the slurry pump 360 of the second slurry tank 330 is started, and the slurry containing urea, monoammonium phosphate and potassium chloride is sprayed onto the particles rolling in the drum granulator 370 to make it uniformly adhered and covered.
  • the surface of the second layer of the coating layer 120 is sprayed for 12 minutes to start the powder pulverizer 311 of the powder pulverizing tank 310, and the zinc sulphate, borax and dolomite powder which have been processed and mixed are uniformly fed into the drum granulator 370, and simultaneously The hot air evaporates to remove moisture to form a second fertilizer layer 110.
  • the slurry pump 360 of the first reactor 340 is started, and the remaining coating liquid is sprayed onto the surface of the second fertilizer layer 110 while removing moisture by evaporation with hot air to form a third coating layer 120.
  • the fertilizer granules are then further dried in a dryer 380, sieved through a sieving machine 390, and then cooled and packaged.
  • the fertilizer requirement of rice on the fluvo-aquic soil in the alluvial plain of the Yellow River the test results of the soil in the experimental field, and the release and utilization of various nutrients in the multi-layer envelope structure controlled release fertilizer in the previous plot test
  • the fertilizer core 100, each fertilizer layer 110, and the coating layer 120 are designed, and the rice special fertilizer with the content of 28-12-10 is produced according to the design, and the field test is carried out.
  • the main raw materials of the fertilizer are: urea, 37% formaldehyde solution, powdered diammonium phosphate with a content of 18-46-0, calcium magnesium phosphate fertilizer of 0-18-0, and potassium chloride with a content of 0-0-60.
  • the second layer of fertilizer layer 110 containing nitrogen, phosphorus and potassium are respectively 20%, 20%, 30% of the total NPK of the fertilizer granules
  • the third layer of fertilizer layer 110 containing nitrogen, phosphorus and potassium respectively It is 33%, 70%, 40% of the total NPK of the fertilizer granules.
  • the nitrogen content of the first coating layer 120 accounts for 7% of the total nitrogen of the fertilizer particles
  • the nitrogen content of the second coating layer 120 accounts for 10% of the total nitrogen of the fertilizer particles
  • the nitrogen content of the third coating layer 120 accounts for the fertilizer. 10% of the total nitrogen of the particles.
  • the innermost layer of the outermost layer is an inner layer fertilizer of mixed urea, diammonium phosphate and potassium chloride
  • the outer layer is an outer layer fertilizer of mixed calcium magnesium phosphate fertilizer and polyurea formaldehyde slow release nitrogen fertilizer.
  • the polyurea formaldehyde slow release nitrogen content accounts for 30% of the total nitrogen of the fertilizer granules.
  • the fertilizer core 100 is: urea, diammonium phosphate, potassium chloride, and the fertilizer core 100 is provided according to the mass ratio of 3.7:1.2:1. Fertilizer pellets having a diameter of about 1.3 mm are prepared in advance by using a high-tower granulation apparatus to produce urea, diammonium phosphate, and potassium chloride in the above ratio.
  • First reactor 340 Put urea and formaldehyde in a reaction kettle at a molar ratio of 2:1, and while stirring, heat, while adding sodium hydroxide solution, the pH is adjusted to 9.5 to 10.5, and the temperature is raised to 50 to 70 ° C. , control reaction time of about 40min. Add dilute sulfuric acid solution, adjust the pH to 2.5 ⁇ 4.5, and control the reaction time for about 25min.
  • Second reaction kettle 350 Put urea and formaldehyde into the reaction kettle at a molar ratio of 1.6:1, and heat while stirring, while adding sodium hydroxide solution, the pH is adjusted to 8.5 to 10.0, and the temperature is raised to 50 to 70 ° C. , control reaction time of about 40min. Add 10% sulfuric acid solution, adjust the pH to 2.5 ⁇ 4.0, and control the reaction time for about 20min.
  • the first chemical slurry tank 320 56 kg of urea, 13 kg of diammonium phosphate, and 33.5 kg of potassium chloride are poured into a tank which has been added with water and continuously stirred, and heated to 100 ° C for use.
  • the second chemical slurry tank 330 117 kg of urea, 52 kg of diammonium phosphate, and 66.8 kg of potassium chloride are poured into a tank which has been added with water and continuously stirred, and heated to 95 ° C for use.
  • the third chemical slurry tank 103 g of urea, 163 kg of diammonium phosphate and 50 kg of potassium chloride are poured into a tank which has been added with water and continuously stirred, and heated to 95 ° C for use.
  • Powder Bowl 310 Pour calcium magnesium phosphate into the tank for use.
  • the calculated amount of the fertilizer core 100 pellets was first fed into a drum granulator 370, and the fertilizer pellets were preheated to about 120 °C with hot air at 350 °C.
  • the coating liquid in the first reaction kettle 340 is sprayed onto the surface of the particle of the fertilizer core 100 by the slurry pump 360, and is polymerized and solidified on the surface of the particle, sprayed for 6 minutes, and simultaneously evaporated by hot air to form a first layer package. Film layer 120.
  • the slurry pump 360 of the first chemical slurry tank 320 is started, and the slurry containing urea, monoammonium phosphate and potassium chloride is sprayed onto the particles rolling in the drum granulator 370 to make it uniformly adhered and covered.
  • a layer of coating layer 120 was sprayed for 5 minutes while moisture was removed by hot air evaporation to form a first layer of fertilizer layer 110.
  • the slurry pump 360 that starts the second reaction kettle 350 sprays the coating liquid onto the surface of the first fertilizer layer 110, causes polymerization on the surface of the particles to be solidified, and is sprayed for 10 minutes, and simultaneously removes moisture by hot air evaporation to form a second.
  • Layer coating layer 120 is sprayed onto the surface of the first fertilizer layer 110.
  • the slurry pump 360 of the second chemical slurry tank 330 is started, and the slurry containing urea, diammonium phosphate and potassium chloride is sprayed onto the particles rolling in the drum granulator 370 to be uniformly adhered and covered.
  • the surface of the second coating layer 120 was sprayed for 5 minutes while moisture was removed by hot air evaporation to form a second fertilizer layer 110.
  • the liquid slurry pump 360 that starts the second reaction kettle 350 again sprays the coating liquid onto the surface of the second fertilizer layer 110, and polymerizes and solidifies on the surface of the particles, and sprays the material for 10 minutes, and simultaneously removes moisture by hot air evaporation to form the first Three layers of cladding layer 120.
  • the slurry pump 360 of the third chemical slurry tank is started, and the slurry containing urea, diammonium phosphate and potassium chloride is sprayed onto the particles rolling in the drum granulator 370 to make it uniformly adhered and covered.
  • the surface of the three layers of the coating layer 120 is applied until the spraying is completed, and the moisture is removed by hot air evaporation to form the inner layer fertilizer of the third fertilizer layer 110.
  • the first reaction kettle 340 is started again, and the powder pulverizer 311 of the powder pulverizing tank 310 is started at the same time, and the calcium magnesium phosphate fertilizer is uniformly fed into the granulator, and the urea formaldehyde and the powder material are adhered to the surface of the fertilizer granule together, and the moisture is evaporated by hot air to remove the water.
  • the outer layer of fertilizer forming the third layer of fertilizer layer 110. Then sieve, cool, and package.
  • the fertilizer of Comparative Example 1 was a common compound fertilizer having the same fertilizer content as that of Example 1.
  • the fertilizer of Comparative Example 2 was a common compound fertilizer having the same fertilizer content as in Example 2.
  • the fertilizer of Comparative Example 3 was a common compound fertilizer having the same fertilizer content as that of Example 3.
  • the multi-layered envelope structure controlled release fertilizer of Examples 1-3 and the common compound fertilizer of Comparative Example 1-3 were applied to the test plots of corn, wheat and rice in different plots, and the base fertilizer was used for one-time fertilization, without top dressing. .
  • the experimental field is located in Henan, and the soil is fluvo-aquic soil.
  • the test plots were subjected to soil tests, and the test plan was designed according to the results. The agronomic matters were recorded during the growth process, and the crop yields were counted after the harvest.
  • the common quick-acting compound fertilizer and the multi-layer envelope structure have the same dosage of slow-release fertilizer. They are used as a base fertilizer for one-time application and no longer topdressing; the NPK content is also the same, among which the corn fertilizer specification: 27-8-5, wheat fertilizer Specifications: 25-12-8, rice fertilizer specifications: 28-12-10.
  • the multilayer envelope structure of the embodiment of the present invention is controlled.
  • the release of fertilizer can provide the nutrients needed by the crop in time.
  • Each growth cycle shows a healthy growth trend, and the crop yield has a significant increase, indicating that the fertilizer utilization rate has been significantly improved and has a good promotion value.
  • the common compound fertilizer can quickly provide the nutrients needed by the crops in the early stage of crop growth, it shows a significant lack of fertilizer in the middle and late stages of crop growth. The crops grow slowly and the seeds are not full due to the inability to obtain nutrients in time.
  • corn cobs are long, bald, small, and light in 100 grains; wheat, rice, inefficient tillers, few grains per spike, and light weight in 1000 grains, eventually leading to a decline in yield.
  • the multi-layer envelope structure slow-release fertilizer can be designed into a layer of slowly releasing package structure according to crop growth needs, providing nutrients in the crop growth cycle in time, so that the crop grows healthily and well, the number of seeds is full and full, yield high.
  • the micronutrient can also be designed to be prepared in a suitable fertilizer layer 110 for the crop to be absorbed at a certain stage.
  • the embodiments of the present invention are some embodiments of the present invention, and not all of the embodiments.
  • the detailed description of the embodiments of the invention is not intended to All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

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Abstract

一种多层包膜结构缓控释肥料及其制备方法，涉及肥料领域。多层包膜结构缓控释肥料，包括层层包覆的肥料层和包膜层，肥料层与包膜层间隔设置，肥料层设置至少两层，包膜层设置至少一层，且肥料层的其中一层作为肥料核心；肥料层含有氮肥、磷肥和钾肥中的至少一种，包膜层为聚脲甲醛，聚脲甲醛至少包含碳原子数为2～5的聚脲甲醛。其能较好地控制释放肥料中的氮磷钾钙镁锌等元素以满足不同作物在不同生长阶段对不同养分的需求。该缓控释肥料的制备利用反应釜、料浆槽、扑粉槽及其配套设施进行，其能根据设计程序控制每层肥料的量及其在整个肥料颗粒中被包覆的位置。整个工序可以间歇进行，也可以连续进行，能够大规模生产。

Description

一种多层包膜结构缓控释肥料及其制备方法 技术领域
本发明涉及肥料领域，且特别涉及一种多层包膜结构缓控释肥料及其制备方法。
背景技术
作物的生长由种子开始直到成熟，经历了出苗、分蘖、拔节、孕穗、扬花、结籽等过程，包括营养生长和生殖生长两个主要吸收养分的阶段，每个阶段需要的营养元素的量不同，而土壤中原有的养分一般满足不了作物的营养需要，需要施一定比例的肥料。
现在市场上的肥料大都是所含元素固定，如尿素是氮肥，普通过磷酸钙含磷和钙，磷酸二氢钾含磷和钾等等，无论有机肥、无机肥，单一肥还是复合肥、复混肥，其所含的营养元素只能满足作物某一阶段某方面的需要，不能满足作物整个生长周期营养元素的合理需要。
在实际耕作中，为了保证作物在不同生长阶段能吸收到相应的营养，必须计算好需要的元素量，通过配制不同种类的肥料给作物 进行追肥，这种施肥方法因只是不同种类肥料的简单搭配，营养元素的作用往往得不到充分发挥，肥料的利用率不高。如要提高产量，提高肥料的利用率，需在作物不同生长阶段进行多次追肥，施肥劳动强度大，施肥成本高。
随着人们对种植技术的改进，出现了无土栽培，可随时检测水中的营养元素并及时补充作物需要的元素。但该方法只能在小范围内如温室大棚等特定场所应用，投资、维护强度大，无法应用于大田农业。
发明内容
本发明的目的在于提供一种多层包膜结构缓控释肥料，其能及时释放肥料中的营养元素以吻合不同作物在不同生长阶段对不同养分的需求，达到一次施肥，无须追肥的目的。
本发明的另一目的在于提供一种多层包膜结构缓控释肥料的制备方法，该制备方法简单易行，能够大规模生产，应用于大田农业。
本发明解决其技术问题是采用以下技术方案来实现的。
本发明提出一种多层包膜结构缓控释肥料，包括层层包覆的肥料层和包膜层，肥料层与包膜层间隔设置，肥料层设置至少两层，包膜层设置至少一层，且肥料层的其中一层作为肥料核心；肥料层含有氮肥、磷肥和钾肥中的至少一种，包膜层为聚脲甲醛，聚脲甲 醛的原料为尿素和甲醛，尿素与所述甲醛摩尔比为1-2.5:1，聚脲甲醛至少包含碳原子数为2～5的聚脲甲醛。
本发明提出一种多层包膜结构缓控释肥料的制备方法，包括以下步骤：
将肥料层及包膜层对应的肥料按预设次序施加于肥料核心周围以形成层层包覆的肥料颗粒。
本发明实施例的一种多层包膜结构缓控释肥料及其制备方法的有益效果是：
多层包膜结构缓控释肥由肥料层和包膜层组成，肥料层与包膜层间隔设置，层层包覆形成环球状。可根据不同土壤结构、不同气候条件下的不同作物的生长需要，设计肥料层中氮、磷、钾和中微量元素等养分的比例。作为包膜层的聚脲甲醛，可根据不同作物的生长需要，使被包覆的肥料按作物的需肥规律缓慢及时释放。被包覆的肥料层中的部分水溶性的营养元素，可以通过包膜层中水溶性的部分被溶解后形成的孔洞释放出来供作物吸收。包膜层中水不溶的部分，在土壤中微生物的作用下缓慢分解，释放肥料层中剩余的没有溶解的全部肥料供作物吸收。随着包膜层的层层分解，被包覆 的肥料层层释放，直到整个肥料颗粒完全分散于土壤。由于包膜层本身也是肥料，从而使得肥料在满足作物生长的同时不产生任何残留。
附图说明
图1为根据本发明实施方式的第一种多层包膜结构缓控释肥料的截面图；
图2为根据本发明实施方式的第二种多层包膜结构缓控释肥料的截面图；
图3为本发明实施例2的生产工艺流程简图。
图标：100-肥料核心；110-肥料层；120-包膜层；310-扑粉槽；311-扑粉机；320-第一化浆槽；330-第二化浆槽；340-第一反应釜；350-第二反应釜；360-液浆泵；370-转鼓造粒机；380-烘干机；390-筛分机。
具体实施方式
为使本发明实施方式的目的、技术方案和优点更加清楚，下面将对本发明实施方式中的技术方案进行清楚、完整地描述。实施方式中未注明具体条件者，按照常规条件或制造商建议的条件进行。 所用试剂或仪器未注明生产厂商者，均为可以通过市售购买获得的常规产品。
下面对本发明实施方式的一种多层包膜结构缓控释肥料及其制备方法进行具体说明。
一方面，本发明提供了一种控释肥料(或多层包膜结构缓控释肥料)，包括：层层包覆的肥料层110和包膜层120，肥料层110与包膜层120间隔设置，肥料层110设置至少两层，包膜层120设置至少一层，且肥料层110的其中一层作为肥料核心100；肥料层110含有氮肥、磷肥和钾肥中的至少一种，包膜层120为聚脲甲醛，聚脲甲醛的原料为尿素和甲醛，尿素与甲醛摩尔比为1-2.5:1，聚脲甲醛至少包含碳原子数为2～5的聚脲甲醛。
其中，聚脲甲醛的碳原子数可以是2～3，包括能溶于冷水的二羟甲基脲、一甲叉二脲；也可以是2～5，包括能够溶解于冷水的聚脲甲醛，不溶于冷水而能溶于热水的二甲叉三脲、三甲叉四脲及热水也不能溶解的碳链长度超过四个的脲。
在一些实施方式中，聚脲甲醛至少包含碳原子数为2～5的聚脲甲醛。
需要说明的是，当肥料层110中含有氮肥、磷肥或钾肥等某种肥料时，单个组分可为一层肥料层110。当肥料层110中含有氮肥、磷肥和钾肥中的两种时，两种组分的混合物为一层肥料层110；或者两种组分单独为一层，两层共同组成一层肥料层110。当肥料层110中含有氮肥、磷肥和钾肥时，这三者组分的混合物为一层肥料层110；或者两种组分的混合物为一层，另一种组分为一层，这两层共同组成一层肥料层110；或者三种组分单独为一层，三层共同组成一层肥料层110。氮磷钾肥可以是速效的尿素、硫酸铵、磷酸氢铵、硫酸钾，也可以是和缓释的脲甲醛、异丁叉二脲、草酰胺等组成的混合物。需要说明的是，氮磷钾肥中自身可包含其它中微量元素，也可以是特别添加的某几种中微量元素。
多层包膜结构缓控释肥由肥料层110和包膜层120层层包覆形成环球状，肥料层110与包膜层120间隔设置，可根据不同土壤结构、不同气候条件、不同作物的生长需要，设计肥料层110中氮、磷和钾及其他中微量元素等养分的比例。作为包膜层120的聚脲甲醛，可根据不同作物的生长需要，使被包覆的肥料层110中的肥料按作物的需肥规律缓慢及时释放。被包覆的肥料层110中的部分水溶性的营养元素，可以通过包膜层120中水溶性的部分被溶解后形 成的孔洞释放出来供作物吸收。包膜层120中水不溶的部分，在土壤中微生物的作用下缓慢分解，释放肥料层110中剩余的没有溶解的全部肥料供作物吸收。随着包膜层120的层层分解，被包覆的肥料层110层释放，直到整个肥料颗粒完全分散于土壤。由于包膜层120的聚脲甲醛本身也是肥料，从而使得肥料在满足作物生长的同时不产生任何残留。
本发明实施方式的多层包膜结构缓控释肥料一次施肥可满足作物整个生长周期对所有营养元素的需要，养分释放可根据作物量身定制，使肥料的养分释放时间和强度同农作物需肥规律基本同步，在作物需要大量养分的时候，能很快有效供给，而在需要量少的时候，可以缓慢提供，中微量元素也可以设计放置到不同肥料层110。这种缓控释效果提高了肥料利用率，减少了肥料流失和(或)被固定。达到一次施足底肥，无需追肥的目的。
肥料核心100、肥料层110的组成和含量及包膜层120的碳链长度及包覆厚度，可根据不同土壤及气候条件下，不同作物在其生长周期的需肥规律计算确定。需肥规律依据全国乃至世界各地科研机构所做的作物肥效试验，或生产单位自己做的土壤化验及肥效试验确定。
具体地，聚脲甲醛主要由以下步骤制备得到：将尿素和甲醛按照1-2.5:1的摩尔比混合，调节反应体系的pH值为7.5-11.5、温度为50℃-75℃，然后调节pH值至2.5～5.5。
与传统的聚脲甲醛制备方法相比，传统的聚脲甲醛制备是将颗粒尿素先溶解于水中，然后加入甲醛溶液，将混合溶液加热到一定温度，调节pH值，使其发生羟甲基化反应。等反应完成后，再调节pH值和温度，使其发生聚合反应。传统方法制备得到的聚脲甲醛为悬浊液，在水中即完全发生聚合反应。这种制备方法在聚合反应完成后含水量高达70％以上，需要放料、冷却、离心或板框压滤出部分水分，这时滤饼中还含有35％～45％的水分，这部分水必须经过烘干机380高温加热脱除，最后得到粉状和块状混合的聚脲甲醛。由于传统方法制备的聚脲甲醛含水量较高，无法单独喷涂成膜。虽然与其他粘结剂混合后能包裹成膜，但各分子之间不会再发生交联和纠缠作用，膜的结构不够致密，在土壤中很容易分散崩解，其肥料核心100颗粒无法缓慢释放。
本发明实施方式中作为包膜层120的聚脲甲醛制备方法中，尿素不需要先溶解于水而是在甲醛溶液中溶解、反应，制得的羟甲基脲、尿素混合溶液含水量较低，例如35％-45％，在调节至酸性后， 聚合反应不在水相中发生，而是喷涂至肥料核心100或是肥料层110表面，在水分蒸发的同时聚合固化成膜，各分子之间发生交联和纠缠作用，膜的结构致密，在土壤中不崩解，从而达到控制肥料核心100和肥料层110中各种营养元素缓慢释放的目的。
在本发明的一些实施方式中，尿素与甲醛的摩尔比为1.2-2.2:1或1.5-2:1或1.6-1.8:1。
在一些实施方式中，多层包膜结构缓控释肥料中的各包膜层120厚度及其组成决定被包覆的肥料释放时间。在本发明的一些实施方式中，多层包膜结构缓控释肥料包括至少两层包膜层120，至少两层包膜层120的厚度相同。在本发明的一些实施方式中，至少两层包膜层120的厚度不同。在本发明的一些实施方式中，至少两层包膜层120的所述聚脲甲醛具有相同的碳链长度的组分。在一些实施方式中，至少两层包膜层120的聚脲甲醛具有不同的碳链长度的组分。
通常，聚脲甲醛是脲甲醛中含有四种形式氮的缓释性氮肥，包含部分没有反应的过量尿素，能溶于冷水的一羟甲基脲、二羟甲基脲、一甲叉二脲，不溶于冷水而能溶于热水的二甲叉三脲、三甲叉四脲和热水也不能溶解的碳链长度超过四个碳原子数的脲。聚脲甲 醛的主要成分是二甲叉三脲、三甲叉四脲等一系列链长的尿素与甲醛的缩合物，该缩合物微溶于水，能控制氮元素的释放量，防止氮素流失，能在土壤中被微生物缓慢分解。用聚脲甲醛做包膜层120，能够控制被包覆肥料的释放量，使其被植物及时充分的吸收利用。
在一些实施方式中，聚脲甲醛为含有以上四种形式氮的缓控释肥料。在一些实施方式中，聚脲甲醛为含有前三种形式氮的缓控释肥料。在一些实施方式中，聚脲甲醛为含有后三种形式氮的缓控释肥料。在一些实施方式中，聚脲甲醛为含有不能在冷水中溶解的氮而能在热水中溶解的氮，和热水中也不能溶解的氮，两种形式氮的缓控释肥料。
本发明中，术语“肥料层110”包含氮肥、磷肥和钾肥中的至少一种。在一些实施方式中，肥料层110包含：(a)选自氮肥、磷肥或钾肥中的至少一种大量元素肥料；以及可选地(b)至少一种微量元素肥料。在一些实施方式中，肥料层110包含：(a)大量元素肥料氮肥、磷肥和钾肥；以及可选地(b)至少一种微量元素肥料。在一些实施方式中，微量元素肥料选自硼肥、锌肥、钼肥、铁肥、锰肥、铜肥等或其组合。在一些实施方式中，肥料层110为除单独的聚脲甲醛之外的肥料。
另外，需要说明的是，作为包膜层120的聚脲甲醛本身为氮肥。作为被包覆的肥料层110中的氮肥可为聚脲甲醛、尿素、异丁叉二脲、丁烯叉二脲、草酰胺、硫酸铵和硝酸铵中的一种或多种缓效或速效肥料。
需要说明的是，作为被包覆的肥料层110可以混合聚脲甲醛和其他营养元素，例如Ca、Mg等。或者是磷肥和钾肥中也可混合Ca、Mg等其他元素，这样就能在作为包膜层120的聚脲甲醛缓慢分解时，为作物提供其所需的其他营养元素。
具体地，在一些实施方式中，多层包膜结构缓控释肥料包括一层或多层包膜层120。在一些实施方式中，多层包膜结构缓控释肥料包括至少两层包膜层120，或至少三层包膜层120，或至少四层包膜层120。在一些实施方式中，多层包膜结构缓控释肥料的最外层为聚脲甲醛包膜层120，请参照图1。在一些实施方式中，多层包膜结构缓控释肥料的最外层为含聚脲甲醛的肥料层110，请参照图2。在一些实施方式中，多层包膜结构缓控释肥料的最外层为不含聚脲甲醛的肥料层110。
肥料核心100可以是从市场上购买的普通化肥，也可以是按比例配置的肥料成分，还可以是含有聚脲甲醛的颗粒肥料，例如，肥料成分中可以包括尿素、磷酸一胺、磷酸二胺、磷酸二氢钾、氯化钾、硫酸钾、硝酸钾、硫酸铵和氯化铵等中的至少一种。
在一些实施方式中，多层包膜结构缓控释肥料被构造成各肥料元素的释放量与玉米作物的需肥规律基本一致(本文中，简称“玉米专用肥料”)。
在一些实施方式中，玉米专用肥料从内到外包括：
(a)肥料核心100，包括尿素、磷酸一铵、氯化钾，氮约占整个肥料颗粒总氮的20％，磷占总磷的15％，钾占总钾的5％。
(b)聚脲甲醛包膜层120，氮约占整个肥料颗粒总氮的7％。
(c)肥料层110，包括尿素、磷酸一铵、氯化钾。氮占整个肥料颗粒总氮的50％，磷占总磷的65％，钾占总钾的80％。
(d)聚脲甲醛包膜层120，氮约占整个肥料颗粒总氮的10％。
(e)肥料层110，包括尿素、磷酸一铵、氯化钾，聚脲甲醛、硫酸锌、白云石粉。氮占整个肥料颗粒总氮的13％，磷占总磷的20％，钾占总钾的15％。
在一些实施方式中，多层包膜结构缓控释肥料被构造成各肥料元素的释放量与小麦作物的需肥规律基本一致(本文中，简称“小麦专用肥料”)。在一些实施方式中，小麦专用肥料从内到外包括：
(a)肥料核心100，包括尿素、磷酸一铵、氯化钾，氮约占整个肥料颗粒总氮的15％，磷占总磷的20％，钾占总钾的30％。
(b)聚脲甲醛包膜层120，氮约占整个肥料颗粒总氮的10％。
(c)肥料层110，包括尿素、磷酸一铵、氯化钾。氮占整个肥料颗粒总氮的30％，磷占总磷的40％，钾占总钾的50％。
(d)聚脲甲醛包膜层120，氮约占整个肥料颗粒总氮的12％。
(e)肥料层110，包括尿素、磷酸一铵、氯化钾、硫酸锌、硼砂、白云石粉。氮占整个肥料颗粒总氮的25％，磷占总磷的40％，钾占总钾的20％。
(f)聚脲甲醛包膜层120，氮约占整个肥料颗粒总氮的8％。
在一些实施方式中，多层包膜结构缓控释肥料被构造成各肥料元素的释放量与水稻作物的需肥规律基本一致(本文中，简称“水稻专用肥料”)。在一些实施方式中，水稻专用肥料从内到外包括：
(a)肥料核心100，包括尿素、磷酸二铵、氯化钾，氮约占整个肥料颗粒总氮的10％，磷占总磷的5％，钾占总钾的10％。
(b)聚脲甲醛包膜层120，氮约占整个肥料颗粒总氮的7％。
(c)肥料层110，包括尿素、磷酸二铵、氯化钾。氮占整个肥料颗粒总氮的10％，磷占总磷的5％，钾占总钾的20％。
(d)聚脲甲醛包膜层120，氮约占整个肥料颗粒总氮的10％。
(e)肥料层110，包括尿素、磷酸二铵、氯化钾。氮占整个肥料颗粒总氮的20％，磷占总磷的20％，钾占总钾的30％。
(f)聚脲甲醛包膜层120，氮约占整个肥料颗粒总氮的10％。)
(g)肥料层110，包括尿素、钙镁磷肥、磷酸二铵、氯化钾、聚脲甲醛。氮占整个肥料颗粒总氮的33％，磷占总磷的70％，钾占总钾的40％。
本发明实施方式的多层包膜结构缓控释肥料具有速效、中效和长效的氮磷钾养分分配，达到各种元素合理组合缓控释放。多层包膜结构缓控释肥料中的速效肥如尿素、硫酸铵、磷酸一铵、磷酸二 铵、氯化钾等可迅速释放供作物吸收，钙镁磷肥提供拘溶性的磷和钙镁硅，肥料中的聚脲甲醛经土壤微生物分解可提供中效和长效的氮素养分，满足作物整个缓慢生长周期的养分需求，且可以设置磷钾及其它中微量元素和脲甲醛混合在一起缓控释放。
并且，在本发明实施方式的包膜层120中，羟甲基脲具有吸附作用，可促使肥料养分和土壤微粒结合，吸附在作物根部，形成胶状螯合物，从而减少养分流失，达到养分被作物充分吸收和提高肥料利用率的目的。与其它控释肥相比，该产品在养分释放过程中受气候(温度)和土壤条件的影响小，肥效更加稳定持久。
在本发明的实施方式中，还提供制备上述多层包膜结构缓控释肥料的方法。包括以下步骤：将肥料层110及包膜层120对应的肥料按预设次序施加于肥料核心100周围以形成层层包覆的肥料颗粒。其中，施加通过喷涂、滚动团粒或其组合进行。
具体地，在本发明的一些实施方式中，喷涂方法主要步骤包括：先在多个反应釜中分别制备不同碳链长度的包膜原料液，在多个化浆槽或扑粉槽310中按照比例配置好各肥料层110的成分。将作为肥料核心100的成分首先送入转鼓造粒机370，然后将多个连续反应 釜中的不同碳链长度的包膜原料液，化浆槽或(和)扑粉槽310中的肥料层110成分按照预设的顺序依次喷入转鼓造粒机370，以使肥料颗粒按设定的肥料层110和包膜层120厚度不断增大直至达到目标。
需要说明的是，不同的喷涂次序和喷涂时间可以形成不同厚度的肥料层110和包膜层120，以形成不同肥效的控释肥料。另外，喷涂根据肥料制备需要可间歇也可连续进行，造粒烘干也可以分别在不同的造粒烘干机380中进行。
另外，一层肥料层110可以是分为一次或多次喷涂而成，多层喷涂而成的肥料层110，多次喷涂的肥料可以是不同的，也可以是相同的。一层包膜层120可以是分为一次或多次喷涂而成，多次喷涂而成的包膜层120，多次喷涂的聚脲甲醛缓释肥的成分可以是不同的，也可以是相同的。
该多层包膜结构缓控释肥料的制备包括反应釜、料浆槽或(和)扑粉槽310、造粒烘干机380及其配套设施，制备特点是能根据设计程序控制每层肥料的配比、包覆量、在整个肥料颗粒中被包覆的位 置以及每层包膜层120的厚度和碳链长度。整个工序可以间歇进行，也可以连续进行，能够大规模生产。
进一步地，将形成的肥料颗粒用热风喷入到烘干机380中进行烘干，然后筛分、冷却、包装、入库。
进一步地，包膜层120聚脲甲醛是通过含羟甲基脲的包膜原料液在酸性条件下在肥料层110表面蒸发去除水分的同时原位聚合得到的。
具体地，将尿素和甲醛在pH值为7.5-11.5、温度50℃-75℃下生成羟甲基脲，然后调节pH值至2～5.5，生成聚脲甲醛包膜原料液。将包膜原料液喷涂于肥料核心100表面形成包膜层120，然后将第二层肥料喷涂在包膜层120表面形成肥料层110，再喷涂包膜原料液形成第二层包膜层120，依次循环。另外，根据需要，聚脲甲醛包膜原料液也可以作为肥料层110成分和肥料一起混合喷涂。
在一些实施方式中，为了加快水分蒸发速度，肥料核心100可以是预热的。例如，肥料核心100被预热到60℃-120℃，或65℃-105℃，或70℃-100℃，或80℃-90℃。
由于聚脲甲醛含有的碳链长度大多是2-5，含水量仅为35％-45％，浓度较高。在包膜原料液喷涂到肥料层110表面上时，水分蒸发聚合固化，从而包覆在肥料层110表面。通过调节尿素和甲醛的摩尔比例、反应体系的pH值及温度，可以改变生成包膜层120的聚脲甲醛碳链长度。
由于在蒸发的同时进行聚合固化，链长不同的分子在形成包膜层120的过程中相互交联在一起。在土壤中，包膜层120中部分水溶性的成分先溶解出来形成孔洞，使肥料层110中的部分水溶性的成分溶解出来，为作物提供营养，包膜层120被缓慢分解，使被包覆的肥料成分缓慢释放，从而为作物提供更多的营养。操作条件不同，包膜层120碳链长度分布不同，缓控释强度也有所不同。在土壤中微生物的作用下，包膜层120从外到内层层溶解和分解，被包覆的肥料层110层缓慢释放供作物吸收。
在本发明的一些实施方式中，包膜原料液的含水量按重量计在35％～45％。
本发明实施方式的控释肥料的制备方法，均具有工艺路线短，能耗低的特点。可以大规模地进行工业化生产。
以下结合实施例对本发明的特征和性能作进一步的详细描述。
实施例1 河南地区玉米专用肥
根据文献资料查得的黄河冲积平原潮土轻壤上的玉米需肥规律、试验田土壤的化验结果，在前期小区试验对多层包膜结构缓控释肥料中各营养元素的释放及利用率了解的基础上，设计出肥料核心100、各肥料层110、包膜层120，根据设计生产出了含量为：27-8-5的玉米专用肥，进行田间试验。
肥料原材料主要有：尿素、37％的甲醛溶液、含量为11-44-0的粉状磷酸一铵、含量为0-0-60的氯化钾、硫酸锌、白云石粉。
按制备1000kg玉米专用肥料计算各元素的配比，需聚脲甲醛135kg、尿素425kg、磷酸一铵185kg、氯化钾85kg、硫酸锌5kg、白云石粉165kg。其中核心颗粒含氮、磷、钾分别为肥料颗粒总氮磷钾的20％、15％、5％，第一层肥料层110含氮、磷、钾分别为肥料颗粒总氮磷钾的50％、65％、80％，第二层肥料层110含氮、磷、钾分别为肥料颗粒总氮磷钾的13％、20％、15％。第一层包膜层120氮素含量占肥料颗粒总氮的7％，第二层包膜层120氮素含量占肥料颗粒总氮的10％。聚脲甲醛缓释氮含量占肥料颗粒总氮的20％。
肥料核心100为：尿素、磷酸一铵、氯化钾，根据计算按质量比26.8：6.6：1配备肥料核心100。提前用高塔造粒设备将尿素、磷酸一铵、氯化钾按上述的比例造出直径为1.5mm左右的肥料颗粒待用。
反应釜：将尿素和甲醛按2：1的摩尔比放入反应釜中，一边搅拌一边加热，同时加入碳酸钠溶液，PH值调至8.5～9.5、温度升到50～70℃，控制反应时间45min左右。加入稀硫酸溶液，PH值调至2.5～4.5，控制反应时间25min左右。
第一化浆槽320：将尿素265kg，磷酸一铵118kg，氯化钾67kg倒入已添加水并不断不断搅拌的槽中，加热升温至95℃待用。
扑粉槽310：将已经处理好的尿素50kg、磷酸一铵36kg、氯化钾13kg、硫酸锌5kg、白云石粉165kg倒入槽中混合均匀待用。
将计算好量的肥料核心100颗粒首先送入转鼓造粒机370中，用300℃热风将肥料颗粒预热至90℃左右。用液浆泵360将反应釜中的包膜液喷涂到肥料核心100颗粒表面，使其在颗粒表面发生聚合反应并固化，喷涂7min，同时用热风蒸发去除水分以形成第一层包膜层120。然后启动第一化浆槽320的液浆泵360，将含有尿素、 磷酸一铵、氯化钾的料浆喷至转鼓造粒机370内滚动的颗粒上，使其均匀粘、覆在第一层包膜层120表面，喷料15min，同时用热风蒸发去除水分以形成第一层肥料层110。启动反应釜的液浆泵360将包膜液喷涂到第一层肥料层110表面，使其在颗粒表面发生聚合反应并固化，喷料12min，同时用热风蒸发去除水分以形成第二层包膜层120。最后启动扑粉槽310的扑粉机311，将已经处理并混合好的尿素、磷酸一铵、氯化钾、硫酸锌、白云石粉均匀送入造粒机内，同时启动反应釜液浆泵360将聚脲甲醛喷入造粒机，脲甲醛和粉料一起粘覆于第二层包膜层120表面，直至物料加完，同时用热风蒸发去除水分以形成第二层肥料层110。然后筛分、冷却、包装。
实施例2 河南地区小麦专用肥
根据文献资料查得的黄河冲积平原潮土轻壤上的小麦需肥规律，试验田土壤的化验结果，在前期小区试验对多层包膜结构缓控释肥料中各营养元素的释放及利用率了解的基础上，设计出肥料核心100、各肥料层110、包膜层120，根据设计生产出了含量为：25-12-8的小麦专用肥，进行田间试验。
肥料原材料主要有：尿素、37％的甲醛溶液、含量为11-44-0的粉状磷酸一铵、含量为0-0-60的氯化钾、硫酸锌、硼砂、白云石粉。
按制备1000kg小麦专用肥料计算各元素的配比，需聚脲甲醛190kg、尿素315kg、磷酸一铵275kg、氯化钾135kg、硫酸锌5kg、硼砂5kg、白云石粉75kg。其中核心颗粒含氮、磷、钾分别为肥料颗粒总氮磷钾的15％、20％、30％，第一层肥料层110含氮、磷、钾分别为肥料颗粒总氮磷钾的30％、40％、50％，第二层肥料层110含氮、磷、钾分别为肥料颗粒总氮磷钾的25％、40％、20％。第一层包膜层120氮素含量占肥料颗粒总氮的10％，第二层包膜层120氮素含量占肥料颗粒总氮的12％，第三层包膜层120氮素含量占肥料颗粒总氮的8％。最外层为聚脲甲醛的第三层包膜层120。聚脲甲醛缓释氮含量占肥料颗粒总氮的30％。
肥料核心100为：尿素、磷酸一铵、氯化钾，根据计算按质量比1.7：1.4：1配备肥料核心100。提前用高塔造粒设备将尿素、磷酸一铵、氯化钾按上述的比例造出直径为1.5mm左右的肥料颗粒待用。
第一反应釜340：将尿素和甲醛按2.2：1的摩尔比放入第一反应釜340中，一边搅拌一边加热，同时加入碳酸钠溶液，PH值调至8.5～9.5、温度升到50～70℃，控制反应时间45min左右。加入稀硫酸溶液，PH值调至2.5～4.5，控制反应时间25min左右。
第二反应釜350：将尿素和甲醛按1.8：1的摩尔比放入第二反应釜350中，一边搅拌一边加热，同时加入碳酸钠溶液，PH值调至8.5～9.5、温度升到50～70℃，控制反应时间40min左右。加入稀硫酸溶液，PH值调至2.5～4.5，控制反应时间20min左右。
第一化浆槽320：将尿素137kg，磷酸一铵110kg，氯化钾67.5kg倒入已添加水并不断不断搅拌的槽中，加热升温至95℃待用。
第二化浆槽330：将尿素110kg，磷酸一铵110kg，氯化钾27kg倒入已添加水并不断不断搅拌的槽中，加热升温至95℃待用。
扑粉槽310：将已经处理好的硫酸锌5kg、硼砂55kg、白云石粉75kg倒入槽中混合均匀待用。
将计算好量的肥料核心100颗粒首先送入转鼓造粒机370中，用350℃热风将肥料颗粒预热至100℃左右。用液浆泵360将第一反 应釜340中的包膜液喷涂到肥料核心100颗粒表面，使其在颗粒表面发生聚合反应并固化，喷涂9min，同时用热风蒸发去除水分以形成第一层包膜层120。然后启动第一化浆槽320的液浆泵360，将含有尿素、磷酸一铵、氯化钾的料浆喷至转鼓造粒机370内滚动的颗粒上，使其均匀粘、覆在第一层包膜层120表面，喷料13min，同时用热风蒸发去除水分以形成第一层肥料层110。启动第二反应釜350的液浆泵360将包膜液喷涂到第一层肥料层110表面，使其在颗粒表面发生聚合反应并固化，喷料14min，同时用热风蒸发去除水分以形成第二层包膜层120。然后再启动第二化浆槽330的液浆泵360，将含有尿素、磷酸一铵、氯化钾的料浆喷至转鼓造粒机370内滚动的颗粒上，使其均匀粘、覆在第二层包膜层120表面，喷料12min，启动扑粉槽310的的扑粉机311，将已经处理并混合好的硫酸锌、硼砂、白云石粉均匀送入转鼓造粒机370内，同时用热风蒸发去除水分以形成第二层肥料层110。最后启动第一反应釜340的液浆泵360，将其余的包膜液喷涂到第二层肥料层110表面，同时用热风蒸发去除水分以形成第三层包膜层120。然后在烘干机380中对肥料颗粒进一步烘干后，经筛分机390筛分后冷却、包装。
实施例3 河南地区水稻专用肥
根据文献资料查得的黄河冲积平原潮土轻壤上的水稻需肥规律，试验田土壤的化验结果，在前期小区试验对多层包膜结构缓控释肥料中各营养元素的释放及利用率了解的基础上，设计出肥料核心100、各肥料层110、包膜层120，根据设计生产出了含量为：28-12-10的水稻专用肥，进行田间试验。
肥料原材料主要有：尿素、37％的甲醛溶液、含量为18-46-0的粉状磷酸二铵、0-18-0的钙镁磷肥、含量为0-0-60的氯化钾。
按制备1000kg水稻专用肥料计算各元素的配比，需聚脲甲醛210kg、尿素332kg、磷酸二铵241kg、钙镁磷肥50kg、氯化钾167kg。其中核心颗粒含氮、磷、钾分别为肥料颗粒总氮磷钾的10％、5％、10％，第一层肥料层110含氮、磷、钾分别为肥料颗粒总氮磷钾的10％、5％、20％，第二层肥料层110含氮、磷、钾分别为肥料颗粒总氮磷钾的20％、20％、30％，第三层肥料层110含氮、磷、钾分别为肥料颗粒总氮磷钾的33％、70％、40％。第一层包膜层120氮素含量占肥料颗粒总氮的7％，第二层包膜层120氮素含量占肥料颗粒总氮的10％，第三层包膜层120氮素含量占肥料颗粒总氮的10％。最外层的里层为混合尿素、磷酸二铵、氯化钾的里层肥料，外层为混 合钙镁磷肥和聚脲甲醛缓释氮肥的外层肥料。聚脲甲醛缓释氮含量占肥料颗粒总氮的30％。
肥料核心100为：尿素、磷酸二铵、氯化钾，根据计算按质量比3.7：1.2：1配备肥料核心100。提前用高塔造粒设备将尿素、磷酸二铵、氯化钾按上述的比例造出直径为1.3mm左右的肥料颗粒待用。
第一反应釜340：将尿素和甲醛按2：1的摩尔比放入反应釜中，一边搅拌一边加热，同时加入氢氧化钠溶液，PH值调至9.5～10.5、温度升到50～70℃，控制反应时间40min左右。加入稀硫酸溶液，PH值调至2.5～4.5，控制反应时间25min左右。
第二反应釜350：将尿素和甲醛按1.6：1的摩尔比放入反应釜中，一边搅拌一边加热，同时加入氢氧化钠溶液，PH值调至8.5～10.0、温度升到50～70℃，控制反应时间40min左右。加入10％的硫酸溶液，PH值调至2.5～4.0，控制反应时间20min左右。
第一化浆槽320：将尿素56kg，磷酸二铵13kg，氯化钾33.5kg倒入已添加水并不断不断搅拌的槽中，加热升温至100℃待用。
第二化浆槽330：将尿素117kg，磷酸二铵52kg，氯化钾66.8kg倒入已添加水并不断不断搅拌的槽中，加热升温至95℃待用。
第三化浆槽：将尿素103g，磷酸二铵163kg，氯化钾50kg倒入已添加水并不断不断搅拌的槽中，加热升温至95℃待用。
扑粉槽310：将钙镁磷肥倒入槽中待用。
将计算好量的肥料核心100颗粒首先送入转鼓造粒机370中，用350℃热风将肥料颗粒预热至120℃左右。用液浆泵360将第一反应釜340中的包膜液喷涂到肥料核心100颗粒表面，使其在颗粒表面发生聚合反应并固化，喷涂6min，同时用热风蒸发去除水分以形成第一层包膜层120。然后启动第一化浆槽320的液浆泵360，将含有尿素、磷酸一铵、氯化钾的料浆喷至转鼓造粒机370内滚动的颗粒上，使其均匀粘、覆在第一层包膜层120表面，喷料5min，同时用热风蒸发去除水分以形成第一层肥料层110。启动第二反应釜350的液浆泵360将包膜液喷涂到第一层肥料层110表面，使其在颗粒表面发生聚合反应并固化，喷料10min，同时用热风蒸发去除水分以形成第二层包膜层120。然后再启动第二化浆槽330的液浆泵360，将含有尿素、磷酸二铵、氯化钾的料浆喷至转鼓造粒机370内滚动 的颗粒上，使其均匀粘、覆在第二层包膜层120表面，喷料5min，同时用热风蒸发去除水分以形成第二层肥料层110。再次启动第二反应釜350的液浆泵360将包膜液喷涂到第二层肥料层110表面，使其在颗粒表面发生聚合反应并固化，喷料10min，同时用热风蒸发去除水分以形成第三层包膜层120。然后再启动第三化浆槽的液浆泵360，将含有尿素、磷酸二铵、氯化钾的料浆喷至转鼓造粒机370内滚动的颗粒上，使其均匀粘、覆在第三层包膜层120表面，直至喷涂完，同时用热风蒸发去除水分以形成第三层肥料层110的里层肥料。再次启动第一反应釜340，同时启动扑粉槽310的扑粉机311，将钙镁磷肥均匀送入造粒机内，脲甲醛和粉料一起粘覆于肥料颗粒表面，同时用热风蒸发去除水分以形成第三层肥料层110的外层肥料。然后筛分、冷却、包装。
对比例1
对比例1的肥料为与实施例1的肥料含量相同的普通复合肥料。
对比例2
对比例2的肥料为与实施例2的肥料含量相同的普通复合肥料。
对比例3
对比例3的肥料为与实施例3的肥料含量相同的普通复合肥料。
试验例1
将实施例1-3的多层包膜结构缓控释肥料和对比例1-3的普通复合肥料施于不同地块的玉米、小麦、水稻的试验田中，均采用基肥一次性施肥，不追肥。试验田位于河南地区，土壤为潮土轻壤。实施前对试验地块进行土壤化验，根据结果对试验方案进行设计，生长过程中记录各项农学事项，收获后对作物产量进行统计。
表1试验田统计结果
Figure PCTCN2018109655-appb-000001
Figure PCTCN2018109655-appb-000002
Figure PCTCN2018109655-appb-000003
备注：普通速效复合肥和多层包膜结构缓控释肥料用量相同，均是做基肥一次性施入，不再追肥；NPK含量也相同，其中玉米肥规格：27-8-5、小麦肥规格：25-12-8、水稻肥规格：28-12-10。
结果分析：通过以上田间试验结果对比可以看出：实施例1-3与对比例1-3相比，在生长周期和施肥量相等的情况下，本发明实施例的多层包膜结构缓控释肥料能及时提供作物需要的营养，每个生长周期都表现了健康的生长态势，作物产量有明显的增加，说明肥料的利用率得到了明显提高，具有很好的推广价值。普通复合肥虽然在作物生长前期能迅速提供作物需要的营养元素，但到作物生长的中后期就表现出了明显的缺肥态势，作物因不能及时得到营养而出现生长缓慢、籽粒不饱满等现象，比如玉米棒秃顶长、棒小，百粒重轻；小麦、水稻无效分蘖多，穗粒数少、千粒重轻等情况，最终导致产量下降。多层包膜结构缓控释肥料则能够根据作物生长需要被设计成层层缓慢释放的包裹结构，在作物各个生长周期及时提供营养元素，使作物健康良好地生长，籽粒数多且饱满，产量高。微肥也可以被设计制备在合适的肥料层110供作物在某一阶段吸收。
综上所述，本发明实施例是本发明一部分实施例，而不是全部的实施例。本发明的实施例的详细描述并非旨在限制要求保护的本发明的范围，而是仅仅表示本发明的选定实施例。基于本发明中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。

Claims (10)

  1. 一种多层包膜结构缓控释肥料，其特征在于，包括层层包覆的肥料层和包膜层，所述肥料层与所述包膜层间隔设置，所述肥料层设置至少两层，所述包膜层设置至少一层，且所述肥料层的其中一层作为肥料核心；所述肥料层含有氮肥、磷肥和钾肥中的至少一种，所述包膜层为聚脲甲醛，所述聚脲甲醛的原料为尿素和甲醛，所述尿素与所述甲醛摩尔比为1-2.5:1，所述聚脲甲醛至少包含碳原子数为2～5的聚脲甲醛。
  2. 根据权利要求1所述的多层包膜结构缓控释肥料，其特征在于，所述多层包膜结构缓控释肥料的最外层为肥料层。
  3. 根据权利要求1所述的多层包膜结构缓控释肥料，其特征在于，所述多层包膜结构缓控释肥料的最外层为包膜层。
  4. 根据权利要求1至3中任一项所述的多层包膜结构缓控释肥料，其特征在于，所述多层包膜结构缓控释肥料包括至少两层包膜 层，所述至少两层包膜层的所述聚脲甲醛具有不同的碳链长度的组分。
  5. 据权利要求1至3中任一项所述的多层包膜结构缓控释肥料，其特征在于，所述多层包膜结构缓控释肥料包括至少两层包膜层120，所述至少两层包膜层的所述聚脲甲醛具有相同的碳链长度的组分。
  6. 根据权利要求1至3中任一项所述的多层包膜结构缓控释肥料，其特征在于，所述多层包膜结构缓控释肥料包括至少两层包膜层，所述至少两层包膜层的厚度相同或不同。
  7. 根据权利要求1至3中任一项所述的多层包膜结构缓控释肥料，其特征在于，所述多层包膜结构缓控释肥料被构造成各肥料元素的释放量与作物的需肥规律基本一致。
  8. 一种如权利要求1-7任一项所述的多层包膜结构缓控释肥料的制备方法，其特征在于，包括以下步骤：
    将所述肥料层及所述包膜层对应的肥料按预设次序施加于所述肥料核心周围以形成层层包覆的肥料颗粒。
  9. 根据权利要求8所述的多层包膜结构缓控释肥料的制备方法，其特征在于，所述施加通过喷涂、滚动团粒或其组合进行。
  10. 根据权利要求8所述的多层包膜结构缓控释肥料的制备方法，其特征在于，所述包膜层的聚脲甲醛是通过含羟甲基脲的包膜原料液在酸性条件下在所述肥料层表面蒸发去除水分的同时原位聚合得到的。
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