CN111362752A - Prepolymerization liquid for preparing water-retaining coated urea and method for preparing water-retaining coated urea by using prepolymerization liquid - Google Patents
Prepolymerization liquid for preparing water-retaining coated urea and method for preparing water-retaining coated urea by using prepolymerization liquid Download PDFInfo
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- CN111362752A CN111362752A CN202010346859.3A CN202010346859A CN111362752A CN 111362752 A CN111362752 A CN 111362752A CN 202010346859 A CN202010346859 A CN 202010346859A CN 111362752 A CN111362752 A CN 111362752A
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- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 title claims abstract description 116
- 239000004202 carbamide Substances 0.000 title claims abstract description 116
- 238000000034 method Methods 0.000 title claims abstract description 31
- 239000007788 liquid Substances 0.000 title claims description 23
- 239000000463 material Substances 0.000 claims abstract description 56
- 238000000576 coating method Methods 0.000 claims abstract description 53
- 239000011248 coating agent Substances 0.000 claims abstract description 52
- 238000006116 polymerization reaction Methods 0.000 claims abstract description 40
- 238000002360 preparation method Methods 0.000 claims abstract description 17
- 239000000243 solution Substances 0.000 claims description 68
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims description 18
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 18
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 claims description 15
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 claims description 14
- 229910000013 Ammonium bicarbonate Inorganic materials 0.000 claims description 14
- 206010016807 Fluid retention Diseases 0.000 claims description 14
- 235000012538 ammonium bicarbonate Nutrition 0.000 claims description 14
- 239000001099 ammonium carbonate Substances 0.000 claims description 14
- 229920005615 natural polymer Polymers 0.000 claims description 11
- 238000005507 spraying Methods 0.000 claims description 10
- 238000006243 chemical reaction Methods 0.000 claims description 9
- 239000005995 Aluminium silicate Substances 0.000 claims description 8
- 239000011837 N,N-methylenebisacrylamide Substances 0.000 claims description 8
- 235000012211 aluminium silicate Nutrition 0.000 claims description 8
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 claims description 8
- ZIUHHBKFKCYYJD-UHFFFAOYSA-N n,n'-methylenebisacrylamide Chemical group C=CC(=O)NCNC(=O)C=C ZIUHHBKFKCYYJD-UHFFFAOYSA-N 0.000 claims description 8
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical group [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 claims description 8
- 238000003756 stirring Methods 0.000 claims description 8
- IXPNQXFRVYWDDI-UHFFFAOYSA-N 1-methyl-2,4-dioxo-1,3-diazinane-5-carboximidamide Chemical compound CN1CC(C(N)=N)C(=O)NC1=O IXPNQXFRVYWDDI-UHFFFAOYSA-N 0.000 claims description 7
- 239000003431 cross linking reagent Substances 0.000 claims description 7
- 239000003999 initiator Substances 0.000 claims description 7
- 239000000661 sodium alginate Substances 0.000 claims description 7
- 235000010413 sodium alginate Nutrition 0.000 claims description 7
- 229940005550 sodium alginate Drugs 0.000 claims description 7
- 239000002734 clay mineral Substances 0.000 claims description 6
- 239000002861 polymer material Substances 0.000 claims description 6
- 239000002994 raw material Substances 0.000 claims description 6
- 239000002245 particle Substances 0.000 claims description 5
- 238000010528 free radical solution polymerization reaction Methods 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 229920001661 Chitosan Polymers 0.000 claims description 3
- 239000005909 Kieselgur Substances 0.000 claims description 3
- 239000004113 Sepiolite Substances 0.000 claims description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 3
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 claims description 3
- 239000007864 aqueous solution Substances 0.000 claims description 3
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 3
- 239000007857 degradation product Substances 0.000 claims description 3
- GUJOJGAPFQRJSV-UHFFFAOYSA-N dialuminum;dioxosilane;oxygen(2-);hydrate Chemical compound O.[O-2].[O-2].[O-2].[Al+3].[Al+3].O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O GUJOJGAPFQRJSV-UHFFFAOYSA-N 0.000 claims description 3
- 229910052901 montmorillonite Inorganic materials 0.000 claims description 3
- 230000017854 proteolysis Effects 0.000 claims description 3
- 229910052624 sepiolite Inorganic materials 0.000 claims description 3
- 235000019355 sepiolite Nutrition 0.000 claims description 3
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 claims description 3
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 2
- 238000007873 sieving Methods 0.000 claims 1
- 239000003795 chemical substances by application Substances 0.000 abstract description 31
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 24
- 230000008569 process Effects 0.000 abstract description 12
- 238000010521 absorption reaction Methods 0.000 abstract description 8
- 238000004519 manufacturing process Methods 0.000 abstract description 5
- 230000007246 mechanism Effects 0.000 abstract description 4
- 230000014759 maintenance of location Effects 0.000 abstract description 3
- 230000007613 environmental effect Effects 0.000 abstract description 2
- 239000002689 soil Substances 0.000 description 21
- 239000003337 fertilizer Substances 0.000 description 20
- 235000015097 nutrients Nutrition 0.000 description 15
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 14
- 230000000694 effects Effects 0.000 description 11
- 239000000843 powder Substances 0.000 description 11
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 8
- 238000002386 leaching Methods 0.000 description 8
- 239000011591 potassium Substances 0.000 description 8
- 229910052700 potassium Inorganic materials 0.000 description 8
- 230000015556 catabolic process Effects 0.000 description 7
- 238000006731 degradation reaction Methods 0.000 description 7
- 229910052757 nitrogen Inorganic materials 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- 239000012528 membrane Substances 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 5
- 240000008042 Zea mays Species 0.000 description 5
- 235000002017 Zea mays subsp mays Nutrition 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- 239000011574 phosphorus Substances 0.000 description 5
- 229910052698 phosphorus Inorganic materials 0.000 description 5
- 235000005824 Zea mays ssp. parviglumis Nutrition 0.000 description 4
- 235000005822 corn Nutrition 0.000 description 4
- 238000004090 dissolution Methods 0.000 description 4
- 230000001580 bacterial effect Effects 0.000 description 3
- 238000011161 development Methods 0.000 description 3
- 230000012010 growth Effects 0.000 description 3
- 239000000725 suspension Substances 0.000 description 3
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 238000013270 controlled release Methods 0.000 description 2
- 239000012153 distilled water Substances 0.000 description 2
- 238000003306 harvesting Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- 239000010410 layer Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000000618 nitrogen fertilizer Substances 0.000 description 2
- 239000002686 phosphate fertilizer Substances 0.000 description 2
- 230000000379 polymerizing effect Effects 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 238000012876 topography Methods 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- 239000002028 Biomass Substances 0.000 description 1
- 239000004971 Cross linker Substances 0.000 description 1
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 1
- 235000016383 Zea mays subsp huehuetenangensis Nutrition 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- YYRMJZQKEFZXMX-UHFFFAOYSA-L calcium bis(dihydrogenphosphate) Chemical compound [Ca+2].OP(O)([O-])=O.OP(O)([O-])=O YYRMJZQKEFZXMX-UHFFFAOYSA-L 0.000 description 1
- 229910000389 calcium phosphate Inorganic materials 0.000 description 1
- 238000005341 cation exchange Methods 0.000 description 1
- 235000013339 cereals Nutrition 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- LRMILOBPOZGOSH-UHFFFAOYSA-N diazanium;carboxylato carbonate Chemical compound [NH4+].[NH4+].[O-]C(=O)OC([O-])=O LRMILOBPOZGOSH-UHFFFAOYSA-N 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 238000003973 irrigation Methods 0.000 description 1
- 230000002262 irrigation Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 235000009973 maize Nutrition 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 235000019691 monocalcium phosphate Nutrition 0.000 description 1
- 230000014075 nitrogen utilization Effects 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 230000008635 plant growth Effects 0.000 description 1
- 229940072033 potash Drugs 0.000 description 1
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Substances [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 1
- 235000015320 potassium carbonate Nutrition 0.000 description 1
- 239000001103 potassium chloride Substances 0.000 description 1
- 235000011164 potassium chloride Nutrition 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 239000003516 soil conditioner Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000011550 stock solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000002459 sustained effect Effects 0.000 description 1
- 238000013268 sustained release Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05C—NITROGENOUS FERTILISERS
- C05C9/00—Fertilisers containing urea or urea compounds
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Fertilizers (AREA)
Abstract
The invention discloses a prepolymerization solution for preparing water-retaining coated urea and a method for preparing the water-retaining coated urea by using the prepolymerization solution. In the preparation process of the water-retaining coated urea, the characteristics of organic coating materials and inorganic coating materials contained in the pre-polymerization solution are utilized, the water-retaining agent polymerization solution is loaded on the surface of urea, and the surface polymerization mechanism is utilized to directly polymerize the water-retaining agent on the surface of the urea to prepare the water-retaining agent coated urea in one step, so that the process is simple and the production cost is reduced. The prepared coated urea has the water absorption and retention slow control/release performance, and has the advantages of environmental friendliness, low price, difficult falling of film materials and the like.
Description
Technical Field
The invention relates to the technical field of water-retaining slow/controlled release fertilizers, in particular to a prepolymerization solution for preparing water-retaining coated urea and a method for preparing the water-retaining coated urea by using the prepolymerization solution.
Background
The statistics of the food and agriculture organization of the United nations shows that the contribution rate of the chemical fertilizer to the grain production is about 40 percent. However, the fertilizer utilization rate is low because the fertilizer consumption per unit area in China is high. A large number of researches show that the season utilization rate of the farmland fertilizer in China is only 30-50 percent of nitrogenous fertilizer, 10-20 percent of phosphate fertilizer and 35-50 percent of potash fertilizer, which are about 5-20 percent lower than that of the similar fertilizer abroad. Meanwhile, water resources in China are relatively poor, the water consumption per person is only about one fourth of the world, the water consumption per person is not uniform, and the shortage of water resources becomes an important factor for limiting the sustainable development of the industry and agriculture in China. The development of high-efficiency water-saving agriculture is a necessary way for sustainable development of agriculture in China.
The water-retaining agent is used as a carrier of fertilizer nutrients, and the nutrient is absorbed and bonded, so that the release of the nutrients of the fertilizer is delayed, and the loss of the nutrients is reduced; meanwhile, due to the water absorption and retention effects of the water retention agent, the water absorbed during rainfall or irrigation can be used for crops in dry land; the water-retaining agent is a good soil conditioner due to the influence on soil micro-aggregates and the like. Therefore, the water retention agent is used as a coating material to prepare the water retention slow release fertilizer, and is an important way for improving the utilization rate of fertilizer and water and improving soil.
The existing preparation method of the water-retaining agent coated fertilizer is mainly a secondary coating method, wherein water-retaining agent powder is prepared firstly, and then the water-retaining agent is coated on the surface of the fertilizer through an adhesive, so that the process is complex; part of the processes are reverse phase polymerization film forming processes, and a large amount of organic solvents are used in the polymerization process, so that the environmental pollution is caused; the water-retaining agent is synthesized on the surface of the urea by a part of processes by adopting a stock solution polymerization method, so that the preparation of the water-retaining agent and the preparation of the slow-release fertilizer are combined into a whole, and the process is simplified. Meanwhile, the water-retaining agent coated fertilizer prepared at present has the problems of high price, difficult degradation of film materials, easy falling and the like.
In view of this, the invention is particularly proposed.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a prepolymerization solution for preparing water-retaining coated urea and a method for preparing the water-retaining coated urea by using the prepolymerization solution.
The invention is realized by the following steps:
in a first aspect, an embodiment of the present invention provides a pre-polymerization solution of water-retention coated urea, which is prepared by using acrylic acid, ammonium bicarbonate, acrylamide, a solution of an organic coating material, and an inorganic coating material as main raw materials and adopting an aqueous solution polymerization method.
The embodiment of the invention provides a pre-polymerization liquid: the acrylic acid, ammonium bicarbonate, acrylamide, organic coating material solution and inorganic coating material are used as main raw materials and prepared by an aqueous solution polymerization method. The pre-polymerization solution contains both the solution of the organic coating material and the inorganic coating material, so that the characteristics of the inorganic coating material and the organic coating material can be fully utilized, on one hand, the biodegradability of the organic coating material is utilized, the degradability of the coated urea film material is improved, the inorganic coating material has higher cation exchange capacity and special effect on nutrient maintenance, and the inorganic coating material is added into the raw materials, so that the raw material cost of the coated urea is also reduced. More importantly, in the process of coating the surface of the urea by using the pre-polymerization solution, the characteristics of an inorganic coating material and an organic coating material are utilized, and the water-retaining agent is uniformly coated on the surface of the urea at one time in an in-situ polymerization manner to form a water-retaining agent coating layer, so that the problems of complex process and uneven coating caused by the fact that the water-retaining agent is coated on the surface of a fertilizer by using an adhesive in the preparation process of the traditional water-retaining coated urea are solved.
In an alternative embodiment, the acrylic acid is present in an amount of 40 to 60 parts and the ammonium bicarbonate is present in an amount of 60% to 85% of the acrylic acid.
In an alternative embodiment, acrylamide is used in an amount of 25 to 40 parts.
In an alternative embodiment, the organic coating material is used in an amount of 4 to 12 parts;
preferably, the organic coating material is a natural polymer material and a derivative thereof;
preferably, the natural polymer material comprises at least one of sodium alginate, protein degradation products, sodium carboxymethyl cellulose and chitosan;
more preferably, the concentration of the natural polymer material solution is 1% to 3%.
In an alternative embodiment, the inorganic coating material is used in an amount of 3 to 10 parts;
preferably, the inorganic coating material is a clay mineral;
preferably, the clay mineral includes at least one of kaolin, montmorillonite, sepiolite and diatomaceous earth.
In a second aspect, an embodiment of the present invention provides a preparation method of the above-mentioned pre-polymerization solution, including the following steps: adding acrylamide and a cross-linking agent into a solution obtained by reacting acrylic acid with ammonium bicarbonate, stirring and mixing uniformly, then mixing uniformly with a solution of an organic coating material and an inorganic coating material, and adding an initiator to prepare a pre-polymerization solution.
In an alternative embodiment, the crosslinker is present in an amount of 0.08 to 0.2 parts and the initiator is present in an amount of 0.5 to 1.0 part;
preferably, the cross-linking agent is N, N-methylene-bis-acrylamide; the initiator is potassium persulfate.
In a third aspect, an embodiment of the present invention provides a method for preparing a water-retention coated urea by using the above-mentioned pre-polymerization solution, including: and spraying the pre-polymerization solution into urea, and heating to ensure that the pre-polymerization solution directly reacts on the surface of the urea through polymerization reaction to form a film, thereby preparing the water-retaining coated urea.
The embodiment of the invention provides a preparation method of water-retaining coated urea. The method is characterized in that the water-retaining agent is uniformly coated on the surface of urea at one time in an in-situ polymerization mode, namely, the water-retaining agent polymerization liquid is loaded on the surface of urea by utilizing the viscosity of an organic coating material and an inorganic coating material, the water-retaining agent is directly polymerized on the surface of the urea to prepare the water-retaining agent by utilizing a surface polymerization mechanism, the water-retaining agent coated urea is synthesized in one step, and the water-retaining agent is directly synthesized on the surface of the urea, so that a film material is difficult. The prepared coated urea has the water absorption and retention slow release performance, and has the advantages of environmental friendliness, low price, difficult falling of film materials and the like.
In an alternative embodiment, the specific steps are as follows: and (2) putting urea into coating equipment, preheating to 70-90 ℃, continuously spraying the pre-polymerization liquid at the rotating speed of the coating equipment of 13-26 r/min according to 2-3 mL/min, controlling the reaction temperature to 70-100 ℃, and reacting for 20-30 min after the pre-polymerization liquid is completely sprayed to obtain the water-retaining coated urea.
In an alternative embodiment, the urea is sieved to obtain particles with a size of 2-5 mm before preheating.
The invention has the following beneficial effects:
the invention provides a prepolymerization solution for preparing water-retaining coated urea and a method for preparing the water-retaining coated urea by using the prepolymerization solution. The method is characterized in that acrylic acid, ammonium bicarbonate, acrylamide, a solution of an organic coating material and an inorganic coating material are used as main raw materials for preparing the water-retaining coated urea pre-polymerized solution, in the process of preparing the water-retaining coated urea by using the pre-polymerized solution, the water-retaining agent polymerized solution is loaded on the surface of urea by using the characteristics of the organic coating material and the inorganic coating material, a surface polymerization mechanism is used for directly polymerizing the surface of the urea to prepare the water-retaining agent, the water-retaining agent coated urea is synthesized in one step, the coating on the surface of the urea is uniform and stable, the process is simple, and the production cost is reduced.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a scanning electron micrograph of a water-retaining coated urea prepared in example 1 of the present invention;
FIG. 2 is a scanning electron micrograph of the water-retaining coated urea prepared in example 2 of the present invention;
fig. 3 is a scanning electron microscope image of the water-retaining coated urea prepared in example 3 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
① Process for preparing the pre-polymerizing liquid includes such steps as reaction between acrylic acid and ammonium dicarbonate, adding acrylamide and cross-linking agent, stirring, adding natural high-molecular solution and its derivatives, clay mineral powder, and adding trigger, and features simple process, low cost and high performance:
the dosage of the acrylic acid is 40-60 parts, and the dosage of the ammonium bicarbonate is 60-85% of the acrylic acid;
25-40 parts of acrylamide;
the cross-linking agent is N, N-methylene-bisacrylamide, and the using amount is 0.08-0.2 part;
the natural polymer and the derivatives thereof can be sodium alginate, protein degradation products, sodium carboxymethylcellulose, chitosan and the like, and the dosage is 4-12 parts;
the clay mineral can be kaolin, montmorillonite, sepiolite, diatomaceous earth, etc., with a dosage of 3-10 parts;
the initiator is potassium persulfate, and the using amount is 0.5-1.0 part;
② adding urea (sieved to obtain 2-5 mm diameter whole granule), preheating to 70-90 deg.C, continuously spraying the solution at 2-3 mL/min at a rotation speed of 13-26 r/min, controlling the reaction temperature at 70-100 deg.C, and reacting for 20-30 min after the solution is completely sprayed to obtain the final product.
The features and properties of the present invention are described in further detail below with reference to examples.
First, an embodiment
Example 1
A preparation method of water-retention type coated urea comprises the following steps:
preparation of a pre-polymerization solution: firstly, fully reacting 120g of acrylic acid with 90g of ammonium bicarbonate, then adding 50g of acrylamide and 0.4g of N, N-methylene-bisacrylamide, stirring, and then adding 500mL of 2.5% sodium alginate solution and 10g of kaolin powder; then 3g of potassium persulfate is added to obtain the pre-polymerization solution.
Adding 2kg of urea into a coating machine, preheating to 70 ℃, continuously spraying the prepolymerization liquid at the rotating speed of 26r/min according to 2mL/min, controlling the reaction temperature to be 90 ℃, and reacting for half an hour after the prepolymerization liquid is completely sprayed to obtain a product.
And (3) testing results:
the topography of the coated urea obtained in example 1 above is shown in fig. 1, and it can be seen that: the membrane material is tightly connected with the core urea, no obvious interface exists, and the membrane material is difficult to fall off.
The nitrogen content of the obtained coated urea is 41.8 percent, the water absorption rate in water is 30.2g/g, and the dissolution rate of 1-month nutrients in soil is 52.0 percent;
the degradation rate of the obtained coated urea film material in soil for 90 days is 25.9 percent, and the degradation rate in soil bacterial suspension for 90 days is 42.8 percent.
Example 2
A preparation method of water-retention type coated urea comprises the following steps:
preparation of a pre-polymerization solution: firstly, fully reacting 120g of acrylic acid with 90g of ammonium bicarbonate, then adding 50g of acrylamide and 0.4g of N, N-methylene-bisacrylamide, stirring, and then adding 400mL of 2.5% sodium alginate solution and 10g of kaolin powder; then 3g of potassium persulfate is added to obtain the pre-polymerization solution.
Adding 2kg of urea into a coating machine, preheating to 70 ℃, continuously spraying the prepolymerization liquid at the rotating speed of 26r/min according to 2mL/min, controlling the reaction temperature to be 90 ℃, and reacting for half an hour after the prepolymerization liquid is completely sprayed to obtain a product.
And (3) testing results:
the morphology of the coated urea obtained in example 2 above is shown in fig. 2, and it can be seen that: the membrane material is tightly connected with the core urea, no obvious interface exists, and the membrane material is difficult to fall off.
The nitrogen content of the obtained coated urea is 41.3 percent, the water absorption rate in water is 32.4g/g, and the dissolution rate of 1-month nutrients in soil is 56.8 percent;
the degradation rate of the obtained film material of the coated urea in soil for 90 days is 23.7 percent, and the degradation rate of the film material in soil bacterial suspension for 90 days is 38.5 percent.
Example 3
Preparation of a pre-polymerization solution: firstly, fully reacting 240g of acrylic acid with 180g of ammonium bicarbonate, then adding 100g of acrylamide and 0.8g of N, N-methylene-bisacrylamide, stirring, and then adding 1000mL of 2.5% sodium alginate solution and 20g of kaolin powder; then 6g of potassium persulfate is added to obtain the pre-polymerization solution.
Adding 2kg of urea into a coating machine, preheating to 70 ℃, continuously spraying the prepolymerization liquid at the rotating speed of 26r/min by 3mL/min, controlling the reaction temperature at 90 ℃, and reacting for half an hour after the prepolymerization liquid is completely sprayed to obtain a product.
And (3) testing results:
the topography of the coated urea obtained in example 3 above is shown in fig. 3, and it can be seen that: the membrane material is tightly connected with the core urea, no obvious interface exists, and the membrane material is difficult to fall off.
The nitrogen content of the obtained coated urea is 35.1 percent, the water absorption rate in water is 37.2g/g, and the dissolution rate of 1-month nutrients in soil is 48.7 percent;
the degradation rate of the obtained film material of the coated urea in soil for 90 days is 22.3 percent, and the degradation rate of the film material in soil bacterial suspension for 90 days is 34.1 percent.
Comparative example 1
Preparation of a pre-polymerization solution: firstly, fully reacting 120g of acrylic acid with 90g of ammonium bicarbonate, adding 500ml of distilled water, then adding 50g of acrylamide and 0.4g of N, N-methylene-bisacrylamide, and stirring, wherein 10g of kaolin powder; then 3g of potassium persulfate is added to obtain the pre-polymerization solution.
Adding 2kg of urea into a coating machine, preheating to 70 ℃, continuously spraying the prepolymerization liquid at the rotating speed of 26r/min according to 2mL/min, controlling the reaction temperature to be 90 ℃, and reacting for half an hour after the prepolymerization liquid is completely sprayed to obtain a product.
And (3) testing results:
the urea can not react on the surface to form a film material.
Comparative example 2
Preparation of a pre-polymerization solution: firstly, fully reacting 120g of acrylic acid with 90g of ammonium bicarbonate, adding 400mL of distilled water, then adding 50g of acrylamide and 0.4g of N, N-methylene-bisacrylamide, stirring, and then adding 100mL of 2.5% sodium alginate solution and 10g of kaolin powder; then 3g of potassium persulfate is added to obtain the pre-polymerization solution.
Adding 2kg of urea into a coating machine, preheating to 70 ℃, continuously spraying the prepolymerization liquid at the rotating speed of 26r/min according to 2mL/min, controlling the reaction temperature to be 90 ℃, and reacting for half an hour after the prepolymerization liquid is completely sprayed to obtain a product.
And (3) testing results:
the nitrogen content of the coated urea is 42.1 percent, the water absorption rate in water is 17.2g/g, and the dissolution rate of nutrients in soil in 1 month is 85.3 percent.
As can be seen from the above examples 1-3 and comparative examples 1-2 provided by the present invention: by adopting the scheme provided in examples 1-3 of the present invention, the pre-polymerized solution is prepared first, and then the pre-polymerized solution is sprayed on the surface of the urea, the surface of the urea can be directly coated with the water retention agent layer, and the coated urea with the water retention agent layer has good properties, but in the preparation process of the pre-polymerized solution in comparative example 1, the solution of the natural polymer powder is not added, and the amount of the solution of the natural polymer powder added in comparative example 2 is lower than that set in the examples of the present invention, therefore, the water absorption multiplying power of the urea after being coated with the film is far lower than the corresponding numerical value in examples 1-3 of the present invention, which shows that: the coated urea with the performance of the embodiment of the invention cannot be obtained by adding no solution of the natural polymer powder into the pre-polymerization solution or using too little solution of the natural polymer powder.
II, verification test:
the influence of the water-retaining coated urea provided by the embodiment of the invention on the growth of plants
Test work: zhongnuo No. one corn.
In the experiment, nitrogen fertilizer (CK) is not applied, Urea (Urea) (Urea is Urea of Fudao brand produced by Zhonghai petrochemical company limited) is applied, and 3 kinds of water-retaining slow-release Urea provided in examples 1 to 3 of the present invention are applied, and the total number of the treatments is 5, and each treatment is set to four levels. Wherein the nitrogen level is 120 mg-N/kg soil, and the phosphorus level is 80 mg-P2O5Per kg of soil, potassium level 100 mg-K2O/kg soil. The phosphate fertilizer uses calcium superphosphate as a phosphorus source, and the potassium fertilizer uses potassium chloride as a potassium source. 4kg of air-dried soil is filled in each pot, 1 seedling is formed by 3 seeds in each pot, the growth of the seedlings is carefully managed, and water is filled in each pot in an equivalent manner. This was repeated until harvest.
TABLE 1 Effect on nutrient leaching loss
As can be seen from Table 1 above, the effect of applying the water-retaining coated urea provided in examples 1-3 of the present invention on nutrient leaching loss: the nitrogen leaching amount, the phosphorus leaching amount and the potassium leaching amount are lower than those of Urea (Urea) application groups, and therefore the water-retention type coated Urea provided by the embodiment of the invention can effectively form a coating effect on the surface of Urea, and the leaching loss of nutrients is reduced. The urea slow-release agent has good slow-release performance and can slowly release urea, so that the leaching loss of the urea can be reduced; meanwhile, the film material of the water-retention type coated urea has an adsorption effect on nutrients and can adsorb potassium in soil, so that the leaching loss of potassium can be reduced.
TABLE 2 Water and fertilizer utilization efficiency of corn
As can be seen from Table 2 above, the application of the water-retaining coated urea provided in examples 1-3 of the present invention has an effect on the water and fertilizer utilization efficiency of corn: the water utilization rate is improved compared with urea, and the nitrogen utilization rate is improved compared with urea.
TABLE 3 growth Effect on maize
As can be seen from table 3 above, the application of the water-retaining coated urea provided in examples 1-3 of the present invention has an effect on the growth of corn: the application of the water-retention coated Urea provided in the embodiments 1-3 of the present invention has higher biomass than the group of Urea (Urea), which shows that the water-retention coated Urea provided in the embodiments of the present invention can effectively improve the use efficiency of Urea.
TABLE 4 Effect on post-harvest soil nutrient residue
As can be seen from Table 4 above, the effect on the residual amount of soil nutrients of the application of the water-retaining coated urea provided in examples 1 to 3 of the present invention: it can be seen from the table that the water-retaining coated urea provided in the embodiments 1 to 3 of the present invention has different improvements in the contents of alkaline-hydrolyzable nitrogen, available phosphorus and available potassium in soil compared with the conventional urea, which indicates that the water-retaining coated urea provided in the embodiments of the present invention not only can play a role of sustained and controlled release, but also can improve the residual amount of potassium and phosphorus in soil and prolong the fertilizer efficiency.
In summary, the embodiments of the present invention provide a prepolymerization solution for preparing a water-retaining coated urea and a method for preparing a water-retaining coated urea by using the prepolymerization solution. In the preparation process of the coated urea in the embodiment of the invention, the characteristics of an organic coating material and an inorganic coating material are utilized to load the polymerization liquid of the water-retaining agent on the surface of the urea, a surface polymerization mechanism is utilized to directly polymerize the water-retaining agent on the surface of the urea, the water-retaining agent coated urea is synthesized in one step, the coating on the surface of the urea is uniform and stable, the process is simple, and the production cost is reduced.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The pre-polymerized liquid for preparing water-retaining coated urea is characterized by being prepared by using acrylic acid, ammonium bicarbonate, acrylamide, organic coating material solution and inorganic coating material as main raw materials and adopting an aqueous solution polymerization method.
2. The pre-polymerization solution as claimed in claim 1, wherein the acrylic acid is used in an amount of 40-60 parts, and the ammonium bicarbonate is used in an amount of 60-85% of the acrylic acid.
3. The prepolymerization solution according to claim 1, wherein the acrylamide is used in an amount of 25 to 40 parts.
4. The pre-polymerization solution as claimed in claim 1, wherein the organic coating material is used in an amount of 4-12 parts;
preferably, the organic coating material is a natural polymer material and a derivative thereof;
preferably, the natural polymer material comprises at least one of sodium alginate, protein degradation products, sodium carboxymethyl cellulose and chitosan;
more preferably, the concentration of the natural polymer material solution is 1% -3%.
5. The pre-polymerization solution as claimed in claim 1, wherein the inorganic coating material is used in an amount of 3 to 10 parts;
preferably, the inorganic coating material is a clay mineral;
preferably, the clay mineral includes at least one of kaolin, montmorillonite, sepiolite, and diatomaceous earth.
6. A method of preparing the prepolymer solution of any one of claims 1 to 5 comprising the steps of: adding acrylamide and a cross-linking agent into a solution obtained by reacting acrylic acid with ammonium bicarbonate, stirring and mixing uniformly, then mixing uniformly with a solution of an organic coating material and an inorganic coating material, and adding an initiator to prepare the pre-polymerization solution.
7. The method according to claim 6, wherein the amount of the crosslinking agent is 0.08 to 0.2 part;
preferably, the cross-linking agent is N, N-methylene-bis-acrylamide.
8. The method according to claim 6, wherein the initiator is used in an amount of 0.5 to 1.0 part;
preferably, the initiator is potassium persulfate.
9. A method for preparing water-retention coated urea by using the prepolymerization solution according to any one of claims 1 to 5 and the prepolymerization solution prepared by the preparation method according to any one of claims 6 to 8, comprising: and spraying the prepolymerization solution on the surface of urea, and heating to ensure that the prepolymerization solution is directly reacted on the surface of the urea to form a film through polymerization reaction, thereby preparing the water-retaining coated urea.
10. The method according to claim 9, characterized by the following specific steps: sieving urea to obtain particles with the particle size of 2-5 mm, then putting the particles into coating equipment, preheating the particles to 70-90 ℃, continuously spraying the prepolymerization liquid according to the volume ratio of 2-3 mL/min under the condition that the rotating speed of the coating equipment is 13-26 r/min, controlling the reaction temperature to be 70-100 ℃, and reacting for 20-30 min after the prepolymerization liquid is completely sprayed, thereby obtaining the water-retaining coated urea.
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