CN117586073A - Preparation method of sulfur/polyurethane composite coated fertilizer - Google Patents
Preparation method of sulfur/polyurethane composite coated fertilizer Download PDFInfo
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- CN117586073A CN117586073A CN202311736340.6A CN202311736340A CN117586073A CN 117586073 A CN117586073 A CN 117586073A CN 202311736340 A CN202311736340 A CN 202311736340A CN 117586073 A CN117586073 A CN 117586073A
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- Prior art keywords
- sulfur
- fertilizer
- polyurethane
- coating
- polycaprolactone
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- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 title claims abstract description 107
- 239000003337 fertilizer Substances 0.000 title claims abstract description 100
- 239000011593 sulfur Substances 0.000 title claims abstract description 100
- 229910052717 sulfur Inorganic materials 0.000 title claims abstract description 100
- 239000004814 polyurethane Substances 0.000 title claims abstract description 56
- 229920002635 polyurethane Polymers 0.000 title claims abstract description 54
- 239000002131 composite material Substances 0.000 title claims abstract description 38
- 238000002360 preparation method Methods 0.000 title abstract description 6
- 229920001610 polycaprolactone Polymers 0.000 claims abstract description 49
- 239000004632 polycaprolactone Substances 0.000 claims abstract description 49
- 239000000463 material Substances 0.000 claims abstract description 44
- 239000002245 particle Substances 0.000 claims abstract description 31
- 238000013270 controlled release Methods 0.000 claims abstract description 22
- 239000007921 spray Substances 0.000 claims abstract description 20
- 239000000203 mixture Substances 0.000 claims abstract description 18
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000004202 carbamide Substances 0.000 claims abstract description 16
- 150000002513 isocyanates Chemical class 0.000 claims abstract description 16
- 239000012948 isocyanate Substances 0.000 claims abstract description 15
- 238000000034 method Methods 0.000 claims abstract description 14
- 238000005507 spraying Methods 0.000 claims abstract description 13
- 238000006243 chemical reaction Methods 0.000 claims abstract description 11
- 239000012530 fluid Substances 0.000 claims abstract description 10
- 238000000889 atomisation Methods 0.000 claims abstract description 6
- 238000002156 mixing Methods 0.000 claims abstract description 5
- 235000011837 pasties Nutrition 0.000 claims abstract description 5
- 238000000576 coating method Methods 0.000 claims description 77
- 239000011248 coating agent Substances 0.000 claims description 73
- 238000004519 manufacturing process Methods 0.000 claims description 13
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 claims description 10
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 8
- 150000001875 compounds Chemical class 0.000 claims description 8
- 239000007788 liquid Substances 0.000 claims description 8
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims description 6
- 239000000843 powder Substances 0.000 claims description 6
- 230000008569 process Effects 0.000 claims description 5
- 238000001125 extrusion Methods 0.000 claims description 4
- 125000002887 hydroxy group Chemical group [H]O* 0.000 claims description 4
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 claims description 4
- 229920001485 poly(butyl acrylate) polymer Polymers 0.000 claims description 4
- -1 polytetramethylene Polymers 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 4
- 238000010521 absorption reaction Methods 0.000 claims description 3
- 210000002700 urine Anatomy 0.000 claims description 3
- PAWQVTBBRAZDMG-UHFFFAOYSA-N 2-(3-bromo-2-fluorophenyl)acetic acid Chemical compound OC(=O)CC1=CC=CC(Br)=C1F PAWQVTBBRAZDMG-UHFFFAOYSA-N 0.000 claims description 2
- 239000005696 Diammonium phosphate Substances 0.000 claims description 2
- 239000005864 Sulphur Substances 0.000 claims description 2
- WZLMXYBCAZZIRQ-UHFFFAOYSA-N [N].[P].[K] Chemical compound [N].[P].[K] WZLMXYBCAZZIRQ-UHFFFAOYSA-N 0.000 claims description 2
- 229910000387 ammonium dihydrogen phosphate Inorganic materials 0.000 claims description 2
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 claims description 2
- 229910052921 ammonium sulfate Inorganic materials 0.000 claims description 2
- 235000011130 ammonium sulphate Nutrition 0.000 claims description 2
- MNNHAPBLZZVQHP-UHFFFAOYSA-N diammonium hydrogen phosphate Chemical compound [NH4+].[NH4+].OP([O-])([O-])=O MNNHAPBLZZVQHP-UHFFFAOYSA-N 0.000 claims description 2
- 229910000388 diammonium phosphate Inorganic materials 0.000 claims description 2
- 235000019838 diammonium phosphate Nutrition 0.000 claims description 2
- 235000019837 monoammonium phosphate Nutrition 0.000 claims description 2
- 239000006012 monoammonium phosphate Substances 0.000 claims description 2
- 239000001103 potassium chloride Substances 0.000 claims description 2
- 235000011164 potassium chloride Nutrition 0.000 claims description 2
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 claims description 2
- 229910052939 potassium sulfate Inorganic materials 0.000 claims description 2
- 235000011151 potassium sulphates Nutrition 0.000 claims description 2
- 229940057995 liquid paraffin Drugs 0.000 claims 4
- 239000012752 auxiliary agent Substances 0.000 claims 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims 2
- 239000008187 granular material Substances 0.000 claims 2
- 240000007594 Oryza sativa Species 0.000 claims 1
- 235000007164 Oryza sativa Nutrition 0.000 claims 1
- 241000209140 Triticum Species 0.000 claims 1
- 235000021307 Triticum Nutrition 0.000 claims 1
- 240000008042 Zea mays Species 0.000 claims 1
- 235000005824 Zea mays ssp. parviglumis Nutrition 0.000 claims 1
- 235000002017 Zea mays subsp mays Nutrition 0.000 claims 1
- 235000005822 corn Nutrition 0.000 claims 1
- 229920005862 polyol Polymers 0.000 claims 1
- 150000003077 polyols Chemical class 0.000 claims 1
- 235000009566 rice Nutrition 0.000 claims 1
- 239000000377 silicon dioxide Substances 0.000 claims 1
- 239000011787 zinc oxide Substances 0.000 claims 1
- 229920000642 polymer Polymers 0.000 abstract description 18
- 229910010272 inorganic material Inorganic materials 0.000 abstract description 3
- 239000011147 inorganic material Substances 0.000 abstract description 3
- 239000011368 organic material Substances 0.000 abstract description 3
- 230000001105 regulatory effect Effects 0.000 abstract 1
- 239000010410 layer Substances 0.000 description 18
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 11
- 239000002356 single layer Substances 0.000 description 10
- 235000015097 nutrients Nutrition 0.000 description 8
- 238000002844 melting Methods 0.000 description 6
- 230000008018 melting Effects 0.000 description 6
- 230000008901 benefit Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 229920000877 Melamine resin Polymers 0.000 description 4
- 238000013329 compounding Methods 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 238000004073 vulcanization Methods 0.000 description 3
- 239000001993 wax Substances 0.000 description 3
- 229910021536 Zeolite Inorganic materials 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 239000008098 formaldehyde solution Substances 0.000 description 2
- 239000010440 gypsum Substances 0.000 description 2
- 229910052602 gypsum Inorganic materials 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical group NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 description 2
- 239000012188 paraffin wax Substances 0.000 description 2
- 239000011527 polyurethane coating Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 239000000565 sealant Substances 0.000 description 2
- 150000003463 sulfur Chemical class 0.000 description 2
- 239000010457 zeolite Substances 0.000 description 2
- 241001391944 Commicarpus scandens Species 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 235000013871 bee wax Nutrition 0.000 description 1
- 239000012166 beeswax Substances 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000004359 castor oil Substances 0.000 description 1
- 235000019438 castor oil Nutrition 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 239000000806 elastomer Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000004720 fertilization Effects 0.000 description 1
- IVJISJACKSSFGE-UHFFFAOYSA-N formaldehyde;1,3,5-triazine-2,4,6-triamine Chemical compound O=C.NC1=NC(N)=NC(N)=N1 IVJISJACKSSFGE-UHFFFAOYSA-N 0.000 description 1
- ZEMPKEQAKRGZGQ-XOQCFJPHSA-N glycerol triricinoleate Natural products CCCCCC[C@@H](O)CC=CCCCCCCCC(=O)OC[C@@H](COC(=O)CCCCCCCC=CC[C@@H](O)CCCCCC)OC(=O)CCCCCCCC=CC[C@H](O)CCCCCC ZEMPKEQAKRGZGQ-XOQCFJPHSA-N 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 230000007794 irritation Effects 0.000 description 1
- 150000002632 lipids Chemical class 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 239000004200 microcrystalline wax Substances 0.000 description 1
- 235000019808 microcrystalline wax Nutrition 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 210000004400 mucous membrane Anatomy 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 230000002572 peristaltic effect Effects 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229920006254 polymer film Polymers 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 229920006264 polyurethane film Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 210000002345 respiratory system Anatomy 0.000 description 1
- 238000007761 roller coating Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 230000001568 sexual effect Effects 0.000 description 1
- 238000009751 slip forming Methods 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000014233 sulfur utilization Effects 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 235000015112 vegetable and seed oil Nutrition 0.000 description 1
- 239000008158 vegetable oil Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
- C05G3/00—Mixtures of one or more fertilisers with additives not having a specially fertilising activity
- C05G3/40—Mixtures of one or more fertilisers with additives not having a specially fertilising activity for affecting fertiliser dosage or release rate; for affecting solubility
-
- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05C—NITROGENOUS FERTILISERS
- C05C9/00—Fertilisers containing urea or urea compounds
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Pest Control & Pesticides (AREA)
- Fertilizers (AREA)
Abstract
The invention relates to a sulfur/polyurethane composite material and a preparation method of a coated controlled release fertilizer thereof. The method comprises the steps of forming a uniform pasty mixture by physically blending inorganic material sulfur and organic material polycaprolactone, spraying the mixture on the surfaces of fertilizer particles by utilizing a two-fluid spray head, and simultaneously spraying isocyanate on the surfaces of the fertilizer particles by utilizing an atomization spray head to perform polyurethane reaction with the polycaprolactone in the mixture, so that a stable inorganic/organic composite film layer is formed on the surfaces of the fertilizer particles. The invention can greatly improve the release performance of the coated fertilizer taking sulfur as a main material, achieves the same S-shaped release mode as the polymer coated fertilizer, and solves the problems of easy rupture and poor release performance of the sulfur-coated urea film. The sulfur/polyurethane composite coated controlled release fertilizer with a release period of 1-3 months can be prepared by regulating the dosage ratio of sulfur to polyurethane.
Description
Technical Field
The invention relates to a sulfur/polyurethane composite material and a preparation method of a coated fertilizer thereof. According to the method, sulfur and polyurethane are mixed and coated on the surface of the large-particle fertilizer to form a stable inorganic/organic composite film layer, so that the mechanical property of the sulfur can be greatly improved, the S-shaped release mode same as that of a polymer coated fertilizer is achieved, the release performance of the coated fertilizer taking the sulfur as a main material is improved, and the problems that the sulfur coated urea film layer is easy to crack and poor in release performance are solved.
Background
The slow/controlled release technology is widely applied to fertilizers, and the slow/controlled release fertilizer can realize one-time fertilization to supply nutrients for the whole growth period of plants, so that the release rate of the nutrients is consistent with the fertilizer requirement rule of crops in the growth and development period, thereby achieving the purposes of time saving, labor saving, yield increasing and synergy. The existing slow/controlled release fertilizer mainly takes coated fertilizer as main material, and the research on the coated fertilizer begins with sulfur coated urea at the earliest. In the 20 s of the twentieth century, the united states began an agricultural study of sulfur to solve the problem of byproduct sulfur utilization in the smelting industry, which was the initial study assumption of sulfur-coated urea. Over thirty years of development, sulfur Coated Urea (SCU), the earliest inorganic coated slow release fertilizer, was developed by TVA company in the united states in 1961. Compared with common urea, the sulfur-coated urea can prolong the release period of urea, slowly release urea nutrients through the sulfur shell for crop absorption and utilization, reduce nutrient loss, improve the utilization rate of fertilizer, supplement soil sulfur, and improve the quality of crops to a certain extent.
However, the sulfur film is easy to break due to the poor physical property of the pure sulfur coating, and the nutrients in the sulfur film are rapidly dissolved and released after the moisture enters the sulfur film. Therefore, the improvement of the controlled release performance of the sulfur-coated fertilizer by methods such as wax fixation and sealing, organic-inorganic multilayer coating, sulfur-modified polymer and the like is a mainstream technical idea. The initial release rate of sulfur-coated urea (coating rate 20%) with the addition of paraffin wax as a sealant can be reduced from 15% to 0.4% (Rindt et al 1968). The inventor (CN 103553849A) coated natural beeswax on the sulfur coating, and the nutrient dissolution rate is more than 15% in 24 hours. The addition of the sealant can improve the slow release property of the sulfur-coated fertilizer, but the impact resistance and abrasion resistance of the coating are low. The inventor coats molten sulfur+polyurethane (ZL 95190939.8), polyurethane+molten sulfur+modified wax (CN 106316620A) and molten sulfur+polycaprolactone (CN 116964023A) outside the granular fertilizer to prepare the modified sulfur coated fertilizer, wherein the release period can reach about 7-60 days. The sulfur-coated fertilizer with the polymer coating has more wear resistance and mechanical degradation caused by impact, handling, transportation, storage and the like, slows down the cracking rate of a pure sulfur film, greatly improves the controlled release performance, but increases the complexity and cost of the coating process. These studies have only combined coatings and have better controlled release properties by the polymer coated fertilizers themselves. The sulfur and polymer (such as castor oil, vegetable oil, etc.) can be subjected to inverse vulcanization reaction at high temperature to generate a controlled release film layer with good mechanical properties, and the release period of the prepared compound coated fertilizer can reach about one month. However, the coating operation is complicated due to the high temperature and organic solvents required in the production process, and industrial production is difficult (Zhao, xiaohan, 2020; ghumman et al, 2022).
In view of the above, there are still some disadvantages in the current process for producing sulfur-coated fertilizers.
(1) The preparation of coated fertilizer is still carried out by using the traditional method of melting sulfur, but the requirement of the sulfur melting spray coating process is high, and the spray nozzle is easy to be blocked by melt liquid when the melt liquid is cooled.
(2) The release performance of the sulfur-coated fertilizer is improved by adding a polymer film layer. Because of the complex multi-layer coating process, the coating materials need to be added step by step. The polymer has high usage ratio, has insignificant advantages compared with the fertilizer coated by the polymer alone, and can not synergistically improve the controlled release effect.
(3) The sulfur modified polymer coated fertilizer is prepared by performing a reverse vulcanization reaction on sulfur and polymer, the reverse vulcanization reaction process is complex, the low-price sulfur consumption is low in proportion, and the core effect of the polymer material cannot be changed.
Disclosure of Invention
The invention aims to directly and physically mix sulfur powder with liquid polyester to prepare a pasty inorganic/organic composite coating material. No need of melting sulfur, no need of multi-layer coating and no need of chemical reaction. The roller coating equipment is used, and the two-fluid spray head is used for coating the composite coating material on the surface of the large-particle fertilizer to prepare a uniform and stable controlled release film layer, so that the sulfur/polyurethane composite coated fertilizer is developed.
The invention relates to an inorganic/organic composite material, which is formed by compounding sulfur and polyurethane.
The sulfur is solid powder at normal temperature, is difficult to directly coat on the surface of fertilizer particles, and needs to be fixed by adding a binder. And the sulfur has poorer mechanical property and needs to be compounded with a material with stronger mechanical property. Polyurethane is a mature and common coating material in the field of controlled release fertilizers, and a solvent is not required to be added in the production process. Polyurethane film layers with different strength and toughness can be produced through polyurethane reaction of different monomers and isocyanate. Polyurethane prepared by reacting polycaprolactone with isocyanate is an elastomer. The polycaprolactone has better reaction controllability, higher stability, excellent product performance and biodegradability with isocyanate. Compounding sulfur with polyurethane is a key to improve the mechanical properties of the sulfur coating film.
The invention also adopts a one-step method to prepare the sulfur/polyurethane compound coated fertilizer. Firstly, the coating materials are quickly and uniformly mixed and then coated on the surfaces of fertilizer particles, so that the coating process is quickly carried out, a product is formed while the coating materials are added, the coating materials are continuously carried out, and a layer of inorganic/organic composite film is continuously formed on the surfaces of the fertilizer particles.
To achieve the purpose, the invention adopts the following technical scheme:
forming a sulfur/polyurethane composite coating material, and mixing and coating the sulfur/polyurethane composite coating material on the surface of fertilizer particles in coating equipment to prepare the coated fertilizer with a stable controlled release coating layer.
The sulfur is usually pure sulfur, is light yellow powder, and has a particle size of 100-800 meshes. Preferably, the particle size is 200-600 mesh.
The soft segment of the synthetic polyurethane comprises Polycaprolactone (PCL), polybutyl acrylate (PBA), polytetramethylene glycol (PTMG) and polytetramethylene glycol (PEG), the molecular weight is 200-1000, the hydroxyl value is 560-110, and the functionality is 2. Preferably, polycaprolactone (PCL) with molecular weight of 400-600 and hydroxyl value of 280-190 is colorless transparent liquid at normal temperature.
The hard segment of the synthetic polyurethane is isocyanate (MDI), the brand is PM200, the viscosity is 150-250, and the appearance is brown liquid.
The dosage ratio of the sulfur to the polyurethane of the composite coating material is between 0.4 and 3. Preferably, the dosage ratio of the sulfur to the polyurethane is 0.5-2. The sulfur and the Polycaprolactone (PCL) are firstly mixed to form a uniform light yellow pasty mixture, and after the mixture is sprayed on the surface of fertilizer particles, isocyanate (MDI) and the Polycaprolactone (PCL) in the mixture are subjected to polyurethane reaction.
The fertilizer particles can be potassium chloride (KCl), potassium sulfate (K) 2 SO 4 ) Ammonium sulfate ((NH) 4 ) 2 SO 4 ) Ammonium Nitrate (NH) 4 NO 3 ) Monoammonium phosphate (NH) 4 H 2 PO 4 ) Diammonium phosphate ((NH) 4 ) 2 HPO 4 ) Urea, composite nitrogen-phosphorus-potassium fertilizer or mixtures thereof. Preferably, urea is used as a fertilizer core, and the particle size is 0.5-10 mm, preferably particles with the particle size of 2-4 mm.
The production equipment comprises a Roots blower, a buffer tank, an electric heater, an air compressor, coating equipment and a spraying device.
The coating equipment is a roller, a fluidized bed or a coating pot, etc., and the fluidized bed is further preferably used as the coating equipment.
The spraying device comprises an atomization spray head, an extrusion type injector and a two-fluid spray head.
In the production method, after sulfur powder and liquid Polycaprolactone (PCL) are uniformly mixed into paste at the temperature below the melting point of sulfur, a compound material is extruded by an injector device, the mixture of sulfur and Polycaprolactone (PCL) is uniformly sprayed onto the surface of fertilizer particles in a continuous motion state through a two-fluid spray head, and meanwhile, isocyanate (MDI) is uniformly sprayed out by an atomization spray head to react with the Polycaprolactone (PCL) in the mixture to be solidified on the surface of large-particle fertilizer to form a uniform and stable single film. The injection rate of the injector extrusion can be selected by those skilled in the art according to the process requirements.
In the production method, the dosage of sulfur required per 100 parts of fertilizer particles is 2.5-7.5 parts, the dosage of Polycaprolactone (PCL) required is 1.65-4.96 parts, and the dosage of isocyanate (MDI) required is 0.85-2.54 parts.
The coating temperature is 40-80 ℃, preferably 50 ℃.
The spraying speed of the paste coating material is 1-3 g/min, and the spraying speed of isocyanate is 0.5-1.5 g/min. The coating time is 10-25 minutes.
According to the invention, polycaprolactone (PCL) and sulfur are physically mixed into paste, and then sprayed on the surface of a large-particle fertilizer in a motion state through a two-fluid spray head, and simultaneously, isocyanate (MDI) is atomized to react with the Polycaprolactone (PCL) in the paste coating material, so that the single-layer coated sulfur/polyurethane composite coated fertilizer is prepared. Compared with the prior art, the invention has the advantages that:
(1) The invention uses the sulfur powder as the coating material, does not need to be melted, and solves the problem that the melted sulfur blocks the spray head to prevent production when encountering cold.
(2) The invention takes sulfur/polyurethane as coating material, and the composite material can be added simultaneously to prepare uniform and stable single-layer composite coated fertilizer. According to the release period requirement of the coated fertilizer, the material dosage proportion is designed. The dosage of polyurethane can be reduced pertinently, and the material proportion with economic price is designed. Compared with the existing coating reaction materials, the coating material sulfur and polyurethane selected by the invention do not need to carry out chemical reaction, and a solvent is not needed to be added.
(3) Compared with the polyurethane coating material, the polyurethane coating material has improved hydrophobicity and mechanical property, and can resist acting force to the film layer due to the concentration difference of nutrients inside and outside the film layer. 4. The invention is not limited by coating equipment, and the preparation of the coated fertilizer in a fluidized bed or a roller and a coating pot can be realized by adding the two fluid spray heads and the atomization spray heads.
The invention can combine the advantages of sulfur-coated fertilizer and polymer-coated fertilizer, reduce the dosage of polymer, take sulfur as main material, make polymer function as binder, have single-layer coating, stable film layer, simple production process and can be produced in factory.
Drawings
FIG. 1 is a flow chart of the production of the compound coated fertilizer according to the present invention.
In the figure: 1-Roots blower; 2-a buffer tank; 3-an electric heater; 4-an air compressor; 5-a fluidized bed; 6-atomizing spray heads; 7-a syringe; 8-two fluid spray head.
The present invention will be described in further detail below. The following examples are merely illustrative of the present invention and are not intended to represent or limit the scope of the invention as defined in the claims.
Description of the embodiments
For a better illustration of the present invention, which is convenient for understanding the technical solution of the present invention, exemplary but non-limiting examples of the present invention are as follows:
EXAMPLE 1 Effect of coating Material amount and ratio on controlled Release Properties of coated fertilizers
In order to verify the influence of the dosage ratio of sulfur to polyurethane on the controlled release performance under the same coating rate, the study adopts several different formulas, and the influence of the dosage of materials on the controlled release performance is compared. The coating operation method comprises the following steps:
(1) Firstly, uniformly stirring and mixing sulfur powder and Polycaprolactone (PCL) at 50 ℃.
(2) Starting the Roots blower, and enabling the air flow to enter the roller after being heated by the electric heater after being buffered and balanced by the buffer tank. The temperature in the fluidized bed is ensured to be 50 ℃ so that the fluidized bed is in a working state.
(3) Adding 0.5. 0.5 kg large-particle urea into a fluidized bed, adding a mixture of sulfur powder and Polycaprolactone (PCL) into an extrusion type injector, pushing the injector to inject the material into a two-fluid spray nozzle, uniformly spraying the material onto the surface of the large-particle urea through the spray nozzle, and conveying isocyanate (MDI) to an atomization spray nozzle through a peristaltic pump to spray the material onto the surface of the fertilizer particles.
(4) The spraying speed of the pasty coating material is 2g/min, the spraying speed of isocyanate (MDI) is 1g/min, and after the sample injection of the coating material is finished, the coating is finished, and the coated fertilizer is taken out.
The measured release properties of the prepared compound coated fertilizer are shown in table 1.
TABLE 1 Effect of different Sulfur/polyurethane usage ratios on coated Fertilizer Release Properties
| Treatment of | S（g） | PCL（g） | MDI（g） | S：PU | Coating ratio (%) | Release period (Tian) |
| 1 | 25 | 8.26 | 4.24 | 2.00 | 7.50 | 27 |
| 2 | 12.5 | 16.52 | 8.48 | 0.50 | 7.50 | 48 |
| 3 | 35.89 | 9.33 | 4.78 | 2.54 | 10.00 | 31 |
| 4 | 25 | 16.52 | 8.48 | 1.00 | 10.00 | 77 |
| 5 | 14.11 | 23.72 | 12.17 | 0.39 | 10.00 | 87 |
| 6 | 37.5 | 16.52 | 8.48 | 1.50 | 12.50 | 69 |
| 7 | 25 | 24.79 | 12.71 | 0.67 | 12.50 | 92 |
As can be seen from table 1: the release period of the prepared sulfur/polyurethane composite coated fertilizer is generally 1-3 months, and the higher the polymer dosage is, the longer the release period is under the same coating rate condition; when the coating rate is between 10 and 15 percent, the defect structure of the film layer is reduced and the number of pores is reduced because the film layer is thicker, and even if the dosage of sulfur is higher than that of a polymer, the release period of the sulfur can be stabilized at about 70 to 90 days. The release period is increased compared with the polymer coated fertilizer with 5 percent of coating rate.
Example 2 Effect of coating Rate on controlled Release Properties of coated fertilizers
The same process conditions as in example 1 were employed to control the usage ratio of sulfur to polyurethane to be 1, and a sulfur/polyurethane composite coated fertilizer was prepared with coating rates of 5.64%, 10% and 14.36%, respectively. The nutrient release period of the coated fertilizer was measured by the water immersion method, and the results are shown in Table 2.
TABLE 2 influence of coating ratio on release properties of sulphur/polyurethane composite coated fertilizer
| Treatment of | S（g） | PCL（g） | MDI（g） | S：PU | Coating ratio (%) | Release period (Tian) |
| 1 | 14.11 | 9.33 | 4.78 | 1.00 | 5.64 | 35 |
| 2 | 25 | 16.52 | 8.48 | 1.00 | 10.00 | 77 |
| 3 | 35.89 | 23.72 | 12.17 | 1.00 | 14.36 | 98 |
As can be seen from Table 2, when the material usage ratio is 1, the higher the coating rate, the longer the release period of the compound coated fertilizer, but the release period of the coating rate is increased from 10% to 15% to a degree lower than the coating rate from 5% to 10%. In comparison, when the material dosage ratio is 1, the coated controlled release fertilizer with the coating rate of 10 percent has higher economic benefit.
Example 3 comparison of controlled Release Properties of Sulfur/polyurethane coated composite fertilizers and other Sulfur-modified coated fertilizers
Comparing the coated fertilizer prepared by the invention with the modified sulfur coated fertilizer prepared by other researches or inventions, it can be seen from Table 3 that the inorganic material composite coating with lower cost has poorer controlled release performance and the release period is about 4 days. The release period of the coated fertilizer prepared by the organic/inorganic material composite is also greatly different: when the selected organic material is a high water absorption material, the release period of the single-layer coated fertilizer is only about 20 minutes even if the coating rate reaches 22%; when 2% of polyurethane and molten sulfur are used for multi-layer coating, the release period of the coated fertilizer is only about 25 days, and a larger lifting space is provided; when about 4% of formaldehyde resin and molten sulfur are used for compounding to prepare a single-layer coating, the release period of the coated fertilizer can reach about 70 days, but the coating rate is higher, and the melamine-formaldehyde resin prepolymer is melamine: the molar ratio of formaldehyde is 1:5, the melamine and formaldehyde react to prepare the formaldehyde solution, and the formaldehyde solution has irritation to human bodies, is easy to damage mucous membranes and stimulates respiratory systems; the sulfur/polyurethane composite single-layer coated fertilizer has the advantages that the sulfur does not need to be melted, solvents and other materials do not need to be added, and the release period can reach 77 days when the coating rate is 10%.
TABLE 3 comparison of the Performance of coated fertilizers prepared from different composite materials
| Name of the name | Materials and amounts | Coating rate | Release period | Sulfur state | Film layer | Source |
| Organic/inorganic composite buffer Urea release | 5% PVA+10% Gypsum+5% Sulfur+2% Paraffin | 22% | 20 minutes | Powder | Monolayer of | Bilal Beig，2020， Sustainability |
| Stone sealed with microcrystalline wax Paste-sulfur-zeolite coated urine Element (A) | Gypsum: sulfur zeolite=1: 1:2 | 25% | for 4 days | Powder | Double-layer | Farahnaz Eghbali Babadi, 2021，ACS Omega |
| Environment-friendly slow-release fertilizer | Melamine-formaldehyde tree Lipid prepolymer: sulfur = 1: 5 | 25% | for 70 days | Melting | Monolayer of | CN 109987991 |
| Polymer sulfur coated slow release Fertilizer | 2% polyurethane+5.5% change Modified Polymer with sexual Sulfur+0.3% Composite wax | 8% | 25 days | Melting | Three layers | CN 106316620 |
| Sulfur/polyurethane composite Single-layer coated fertilizer | Sulfur: polyurethaneEster=1:1 | 10% | For 77 days | Powder | Monolayer of | Homemade |
The applicant states that the invention is illustrated by the above examples of the production method of the invention, but the invention is not limited to the above operation steps, i.e. it does not mean that the invention must be carried out in dependence on the above operation steps. It should be apparent to those skilled in the art that any modification of the present invention, equivalent substitution of selected raw materials, addition of auxiliary components, selection of specific modes, etc. fall within the scope of the present invention and the scope of disclosure.
Claims (21)
1. The invention relates to an inorganic/organic composite coating material, which is a composite coating material formed by uniformly mixing sulfur, polyurethane, an auxiliary agent and the like, and a production method for preparing a composite coated fertilizer by using the material.
2. The sulfur of claim 1, wherein the sulfur is a pale yellow powder with a particle size of 100-800 mesh. Preferably, the particle size is 200-600 mesh. No heat to melt is required for blending with polyurethane.
3. Polyurethane according to claim 1, wherein the polyol of the synthetic polyurethane is selected from the group consisting of Polycaprolactone (PCL), polybutyl acrylate (PBA), polytetramethylene glycol (PTMG), polytetramethylene glycol (PEG). Preferably polycaprolactone PCL.
4. A Polycaprolactone (PCL) according to claim 3, wherein the molecular weight is 200-1000, the hydroxyl number is 560-110, and the functionality is 2. Preferably, polycaprolactone (PCL) with molecular weight of 400-600 and hydroxyl value of 280-190 is colorless transparent liquid at normal temperature.
5. The polyurethane of claim 1 wherein the isocyanate of the synthetic polyurethane is polymeric MDI, having a PM200 brand, a viscosity of 150 to 250, and a brown liquid appearance.
6. The auxiliary agent according to claim 1, wherein the auxiliary agent is liquid paraffin, nano silica, nano zinc oxide. Preferably the auxiliary is liquid paraffin.
7. The liquid paraffin as claimed in claim 6, wherein the liquid paraffin has a molecular weight of 250 to 450 and a viscosity of 3 to 10cSt.
8. The composite coating material of claim 1, wherein the ratio of sulfur to polyurethane is between 0.4 and 3. Preferably, the dosage ratio of the sulfur to the polyurethane is 0.5-2. The sulfur and the Polycaprolactone (PCL) are firstly mixed to form a uniform light yellow pasty mixture, and after the mixture is sprayed on the surface of fertilizer particles, the isocyanate and the Polycaprolactone (PCL) in the mixture are subjected to polyurethane reaction.
9. The mixture according to claim 8, wherein the sulphur is admixed with the polycaprolactone at a temperature of 30-80 ℃, preferably at a temperature of 40-60 ℃.
10. The large granule fertilizer as set forth in claim 1, characterized in that it is any granular fertilizer, such as potassium chloride (KCl), potassium sulfate (K 2 SO 4), ammonium sulfate ((NH) 4 ） 2 SO 4 ) Ammonium Nitrate (NH) 4 NO 3 ) Monoammonium phosphate (NH) 4 H 2 PO 4 ) Diammonium phosphate ((NH) 4 ） 2 HPO 4 ) Urine (urine)Plain, composite nitrogen phosphorus potassium fertilizer or a mixture thereof. Preferably, urea is used as a fertilizer core, and the particle size is 0.5-10 mm, preferably particles with the particle size of 2-4 mm.
11. The production equipment as claimed in claim 1, characterized in that the production equipment used comprises a Roots blower (1), a buffer tank (2), an electric heater (3), an air compressor (4), a coating equipment (5), a spraying device.
12. The coating apparatus of claim 11, wherein the coating device is a coating pan, a roller, a fluidized bed, or the like. Preferably, a fluidized bed is used as the coating means.
13. A spraying device according to claim 1, characterized by comprising an atomizer (6), an extrusion injector (7), a two-fluid nozzle (8).
14. The method according to claim 1, wherein the amount of sulfur required per 100 parts by weight of the fertilizer granule is 2.5 to 7.5 parts, the amount of Polycaprolactone (PCL) required is 1.65 to 4.96 parts, and the amount of MDI required is 0.85 to 2.54 parts.
15. The method according to claim 1, wherein the specific operation steps are that the compound material is extruded by an injector device, the mixture of sulfur and Polycaprolactone (PCL) is uniformly sprayed on the surface of the large-particle fertilizer in a continuous motion state through a two-fluid spray nozzle, and simultaneously isocyanate (MDI) is uniformly sprayed out by an atomization spray nozzle to react with the polycaprolactone to solidify the mixture on the surface of the large-particle fertilizer to form a uniform and stable single film layer.
16. The process according to claim 15, wherein the coating temperature is 40-80 ℃, preferably 50 ℃.
17. The operation of claim 15, wherein the paste coating material is sprayed at a rate of 1-3 g/min; the spraying speed is 0.5-1.5 g/min; the coating time is 10-25 minutes.
18. The coated fertilizer of claim 1, wherein the release period of the sulfur/polyurethane composite coated fertilizer is 1-3 months, and can substantially meet the production requirements of crops.
19. The coated fertilizer of claim 1, wherein the controlled release film layer of the sulfur/polyurethane composite coated fertilizer has good hydrophobicity, the water absorption rate is below 1.5%, and the water contact angle is between 95 and 100 ℃.
20. The coated fertilizer of claim 1, wherein the mechanical properties of the controlled release film of the sulfur/polyurethane composite coated fertilizer are affected by the sulfur to polyurethane usage ratio, and when the sulfur to polyurethane usage ratio is less than 1, the elongation at break is greater than 10%.
21. The coated fertilizer of claim 1, wherein the sulfur/polyurethane compound coated fertilizer is suitable for paddy field and dry land crops, such as rice, wheat, corn, etc.
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