CN101323545A - Degradable polymer-coated controlled-release fertilizer and its preparation method and special coating material - Google Patents

Abstract

The invention discloses a polymer-coated controlled-release fertilizer, a preparation method thereof and a special coating material. The coating material includes: isocyanate, polyol, degradable functional monomer, film-forming agent and chain extender; wherein, the molar ratio of the isocyanate group in the isocyanate to the hydroxyl group in the polyol is 1: 2-2:1, the mass of the degradable functional monomer is 1%-20% of the mass of the coating material. The coated controlled-release fertilizer provided by the present invention consists of a core and a nuclear membrane, wherein the core is a granular fertilizer, the nuclear membrane is made of the coating material, and the quality of the nuclear membrane is the 2%-10% of core mass. The coating material has good film-forming and water-resistance properties, and can be degraded in nature. The hardness and elasticity of the material can be adjusted by changing the ratio of the coating material to prepare controlled-release fertilizers with different release periods.

Description

Degradable polymer-coated controlled-release fertilizer and its preparation method and special coating material

technical field

The invention relates to a novel degradable polymer-coated controlled-release fertilizer, a preparation method and a special coating material.

Background technique

my country is a large agricultural country, and the proportion of chemical fertilizers in agricultural production investment accounts for about 50%, but the utilization rate of fertilizers in our country is only 30%, which causes a huge waste of economic energy and various environmental problems. Therefore, controlled-release fertilizers have become the development direction of agricultural fertilizers in the future, and polymer-coated fertilizers are called real controlled-release fertilizers by relevant experts. It uses polymer materials to form a film on the surface of fertilizers, controls the dissolution rate of fertilizers in the soil, and makes the dissolution rate consistent with the growth needs of plants, so as to save fertilizers, improve fertilizer utilization and increase agricultural economic benefits. Purpose.

Polymer coating materials can be divided into three main forms: organic solvent-based, water-based polymers and in-situ polymerization of small molecule monomers to form films on the surface of fertilizers. Most of the domestic research is on organic solvent-based polymer materials, mostly polyolefins or recycled old plastics are used as film materials, which are dissolved in organic solvents and sprayed on the surface of fertilizers to form films. However, it has high production costs, serious environmental pollution caused by incomplete recovery of organic solvents in the production process, and the coating material is not easy to be degraded by microorganisms, which is easy to cause so-called "white pollution" and other problems. Long-term use will bring serious problems to the soil. Consequences, thus limiting its large-scale application.

The use of water-based polymer materials as the coating agent has significant advantages. It uses water as the solvent, has no environmental pollution problems, does not have expensive solvent recovery devices, and the price of coated fertilizers is significantly lower than that of solvent-based coated fertilizers. At present, the focus of research on water-based polymer-coated controlled-release fertilizers in China is to find existing commercial polymer materials for coated controlled-release fertilizers, but research on materials specifically for controlled-release fertilizers is very rare. In the process of water-based polymer coating materials, there is a common problem that the fertilizer is melted due to the high-humidity environment of the coating, so that the ideal controlled release effect cannot be achieved, which seriously restricts the development of water-based polymer coating materials.

In recent years, more and more foreign research institutes have focused on in-situ polymerization: that is, small molecular monomers are directly reacted on the surface of fertilizers to form films to prepare coated controlled-release fertilizers, which can further reduce the cost of coated fertilizers and make It is possible to apply coated controlled-release fertilizers on a large scale to field crops. The main materials used in the reaction-forming film-coated controlled-release fertilizer are polyurethane and alkyd resin. Researchers from the United States, Japan, Israel and Canada have applied for many related US patents. For example: In a series of patents by William P. Moore (US 4711659, US 4804403, US 4969947, etc.), it is described that chemical bonding with fertilizers is used to form the first layer of coating, and then polyurethane materials are used for the second layer of coating controlled release fertilizers. Alice P. Hudson (US 5538531) patent clearly describes the use of isocyanates and polyols. It uses toluene diisocyanates purchased from Dow Chemical under the trade name Monder TD, TDS, and TD-80, and includes castor oil The preparation method of the polyurethane-coated controlled-release fertilizer made of a variety of polyols including hydrogenated castor oil as raw materials. In its U.S. patent (US5851261, US6358296B1, US6503288B1), Bayer Corporation improved the uniform integrity of the coating of the polyurethane coating material on the fertilizer particles by maintaining the slow mixing process of the fertilizer particles during the application of the coating material. In its series of patents (US7018440 B2, US7018 441 B2, US2003/003843A1, US2003/0051523A1), Nobuaki Tabei describes the use of polyurethane materials for the manufacture of controlled-release fertilizers. Homogenization, thereby improving the controlled release effect. Nick P.Wynnyk etc. published a series of patents (US2007/0137274A1, US2007/0169527A1, US 2006/0032282A1, US2004/0020254A1, US2004/0016276A1) about optimizing the method of polyurethane coated controlled-release fertilizer after 2004. The optimized polyurethane-based coating process has applied for related patents in China (CN 101006032A): method and device for producing coated products, and method and device for coating controlled-release products in rotating drums. In these related patents, published Ways, methods and related equipment to improve the integrity of the polyurethane material coating are discussed.

Although a lot of research has been done on polyurethane thermosetting resin coating materials, there are still some problems that have not been completely resolved in the process of use: the mixing degree of isocyanate components and polyol components on fertilizer particles is low, the coating The utilization rate of raw materials is low; due to the increase of the viscosity of the monomer raw materials during the transition from liquid to solid state, and because there is no anti-adhesive effect of the solvent, after the monomer raw materials are evenly coated on the granular fertilizer, they will be in the solidification process. There are macro defects such as tearing, pinholes, and poor uniformity, which seriously affect the controlled release performance. The various measures mentioned in the Chinese patent applied by Nick P. Wynnyk and others to adopt staged curing and minimize the contact in the fertilizer curing stage have improved the integrity of the coating process to a large extent, but the existing process is relatively complicated. However, it does not advocate sufficient mixing of polyurethane raw materials before reaching the fertilizer, thereby reducing the uniformity of the chemical composition of the coating material. Therefore, relying on the contact between fertilizers on the fertilizer particles makes the two types of polyurethane raw materials Mixing, the degree of mixing is limited, will inevitably affect the film performance of the final film.

On the other hand, due to the high chemical stability of polyurethane materials, if such controlled-release fertilizers are widely used in field crops, the problem that must be solved is the biodegradability of the coating materials. Because if the non-degradable membrane material is used for a long time, the residual membrane material will inevitably bring serious environmental problems to the soil. Therefore, there is a lot of room for improvement in terms of the preparation process and the innovation of membrane materials for polyurethane-coated controlled-release fertilizers.

Contents of the invention

The purpose of the present invention is to provide a novel degradable polymer-coated controlled-release fertilizer, its preparation method and special coating material.

The special coating material for controlled-release fertilizer provided by the present invention includes: isocyanate, polyol, degradable functional monomer, film-forming agent and chain extender; wherein, the isocyanate group contained in the isocyanate and The molar ratio of hydroxyl groups contained in the polyol is 1:2 to 2:1, the mass of the degradable functional monomer is 1%-20% of the mass of the coating material, and the mass of the film-forming agent The mass ratio of the chain extender to the coating material is greater than 0 and less than or equal to 30%, and the mass ratio of the chain extender to the coating material is greater than 0 and less than or equal to 15%.

The composition of the coating material also includes a catalyst, and the mass ratio of the catalyst to the coating material is greater than 0 and less than or equal to 0.05%.

The coating material is made of polyurethane with good release control and biodegradability.

The polymer-coated controlled-release fertilizer provided by the present invention consists of a core and a nuclear membrane, wherein the core is a granular fertilizer, the nuclear membrane is made of the coating material provided by the present invention, and the nuclear membrane The mass is 2%-10% of the core mass.

Wherein, the average particle diameter of the granular fertilizer is 2-6mm.

Another object of the present invention is to provide a coating solution (polyurethane solution with good release control and biodegradability) of coated fertilizer.

The coating solution provided by the present invention is prepared according to the following method:

1) The following a) and b) are preheated to a molten state respectively, the a) is the isocyanate and the film-forming agent in the coating material provided by the present invention; the b) includes the coating provided by the present invention Polyols, degradable functional monomers and chain extenders in materials;

2) The a) and b) are mixed, and the mixing time is 0.1-20 seconds to prepare the coating solution.

b) in the step 1) may also include the catalyst in the coating material provided by the present invention.

Wherein, the preheating temperature of the isocyanate-containing component in the step 1) can be 50-100°C, the preheating temperature of the polyol-containing component can be 65-95°C, and the conveying pipelines are all insulated pipelines; the step 2) Medium mixing can achieve fast and good mixing of high-viscosity liquids through fast mixing devices.

The method for preparing the above-mentioned polymer-coated controlled-release fertilizer provided by the present invention comprises the following steps:

1) Preheat the granular fertilizer in a drum or fluidized bed;

2) Atomizing the coating solution provided by the present invention on the surface of the preheated granular fertilizer to make a coated controlled-release fertilizer.

Wherein, the preheating temperature of the fertilizer granules in the drum or fluidized bed in the step 1) can be 50-90°C; in the step 2), atomizing the coating solution on the surface of the preheated fertilizer granules is Realized by atomizing nozzle, the atomizing nozzle is a pressure type nozzle, the atomization pressure range is 0.0015MPa～0.8MPa; the atomization flow rate of the coating solution is 0.01～1kg/min, by adjusting the atomization flow rate range, so that the droplets can reach the surface of the rotating fertilizer particles to the maximum extent, mix quickly and evenly, and solidify into a film.

The isocyanate described in the present invention is one of the following 27 kinds of isocyanates or any combination thereof: toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), hexaethylene diisocyanate (TDI), Methyl diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), naphthalene diisocyanate (NDI), p-phenylmethane diisocyanate, 1,4-dicyclohexane diisocyanate, xylylene diisocyanate, Cyclohexane dimethylene diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, tetramethyl iso-xylylene diisocyanate, dimethyl biphenyl diisocyanate, methylcyclohexyl diisocyanate Isocyanate, norbornane diisocyanate, polymethylene polyphenyl isocyanate (PAPI), liquefied diphenylmethane diisocyanate, toluene diisocyanate dimer (liquefied MDI, TDI dimer), toluene diisocyanate (TDI) Trimer, toluene diisocyanate-trimethylolpropane (TDI-TMP) adduct, toluene diisocyanate-hexamethylene diisocyanate (TDI-HDI) mixed polymer, hexamethylene diisocyanate (HDI ) trimer, hexamethylene diisocyanate (HDI) biuret, isophorone diisocyanate (IPDI) trimer, triphenylmethane triisocyanate, thiophosphoric acid tris(4-phenylisocyanate) and Dimethyltriphenylmethane tetraisocyanate.

Described polyhydric alcohol is following a) and/or b) and/or c) and/or d):

The a) is at least one of the following fourteen kinds of polyether polyols: polyoxyethylene polyols, polyoxypropylene diols, polyoxypropylene triols, highly active polyether triols, polyether tetraols, Ethylenediamine polyether polyol, high-functionality polyether polyol, polytetrahydrofuran diol, branched polytetrahydrofuran diol, tetrahydrofuran-propylene oxide copolyether diol, tetrahydrofuran-ethylene oxide copolyethylene glycol, polyurea polyol , polyacrylate polyol and polyethylene polyol;

The b) is at least one of the following three kinds of vegetable oil polyols: castor oil, soybean oil polyols and palm oil polyols;

The c) is at least one of the following eight polyester polyols: polyethylene succinate, polybutylene succinate, polyethylene adipate, polyadipate butanediol esters, aromatic polyester polyols, polyethylene carbonate, polycarbonate diols and polycaprolactone polyols;

Said d) is at least one of the following five substances: polysuccinimide, polyglycolic acid, polylactic acid, polycaprolactone and poly(ε-caprolactone) diol.

The degradable functional monomer is at least one of the following substances:

Tannin, lignin, chitosan, cellulose, polyamino acid, molasses, modified cellulose, chitin, chitosan and other sugars and their modified materials;

From gelatin-modified resins, sericin-modified resins, lignin-modified resins and other protein-modified resins and natural polymers from vegetable oils;

Monosaccharides, disaccharides, oligosaccharides, polysaccharides and their derivatives and modified compounds;

Cellulose Nitrate, Cellulose Acetate, Ethyl Cellulose, Celluloid Viscose Rayon, Regenerated Cellulose, Cellophane, Copper Yarn, Copper Spun, Bemberg Silk, Hemicellulose, Starch, Gum Arabic, Guano Glue, chitin, chitosan and their modified substances;

The monosaccharide is at least one of the following sugars: erythrose, ribose, arabinose, xylose, lyxose, allose, altrose, glucose, mannose, gulose, idose , galactose, talose, fructose, glucopyranose, glucofuranose, galactofuranose, arabinopyranose, fructopyranose, xylulose, ribulose, sedoheptulose, rhamnose, fucose sugars, glucosamine and galactosamine;

The polysaccharide is at least one of the following sugars: chitosan, molasses, chitin, chitosan, cellulose, modified cellulose, starch and gum arabic;

The cellulose is at least one of the following materials: nitrocellulose, cellulose acetate, ethyl cellulose, regenerated cellulose, celluloid viscose rayon, cellophane, copper yarn, copper spinning, semi-fiber lignin and lignin;

The catalyst is one of the following eighteen substances or any combination thereof: dibutyltin dilaurate, stannous octoate, triethylamine, dimethyl hexadecylamine, bis-dimethylaminoethyl ether, Diethylenetriamine, triethylenediamine, tetramethylbutanediamine, N-ethylmorpholine, N,N-dimethylcyclohexylamine, triethanolamine, methyldiethanolamine, dimethyl Ethanolamine, pyridine, N,N'-lutidine, 1,2,4-trimethylpiperazine, diketimine, and α-mercaptobenzimidazole.

The chain extender is one of 1,4-butanediol, 2,3-butanediol, diethylene glycol, 1,6-hexanediol, glycerol, trimethylolpropane and sorbitol or its random combination.

The film-forming agent is one of paraffin, chlorinated paraffin, sulfonated paraffin, rosin ester, petroleum resin, terpene resin and asphalt, or any combination thereof.

The granular fertilizer described in the present invention can be various water-soluble granular fertilizers, including urea, ammonium carbonate, ammonium nitrate, ammonium sulfate, potassium sulfate, potassium chloride, potassium nitrate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, etc. It also includes fertilizers of various trace elements (iron, manganese, boron, zinc, copper, molybdenum); it can be a simple fertilizer or a compound fertilizer in various proportions. The water-soluble fertilizer is granular, and can be large-grained urea with uniform granulation, or compound fertilizer with uneven granulation, with a particle size of 2 to 6mm. Sieve to remove the powder, the particle size is controlled at 2-6mm, and then preheat for application.

The invention discloses a biodegradable thermosetting resin material applied to coated controlled-release fertilizers. The material has good biodegradability in the natural environment. By introducing biodegradable chemical groups during the preparation of polymer membranes, the membranes can be safely discarded in the natural environment. This polymer membrane can be obtained under mild reaction conditions and has Good environmental degradation ability, that is, hydrolysis ability and biodegradation ability. Compared with the conventional process, the preparation process of the present invention adopts a micro-spraying process that can fully mix the isocyanate component and the polyol component. This process greatly improves the utilization rate of the coating material and realizes the isocyanate component. Fully mixed with the polyol component, the controlled-release performance of the fertilizer is improved, and it can be widely used in the process of in-situ reaction film formation of thermosetting resins such as polyurethane on the particle surface. The preparation process of the degradable polymer coating material and the coating controlled-release fertilizer involved in the invention is economically feasible and has high operation stability. The degradable polymer-coated controlled-release fertilizer of the present invention and its preparation process have not been reported at home and abroad, and have not been used in China.

Compared with the previous film-coated controlled-release fertilizers, the present invention uses biodegradable polyurethane as the film material, and adopts the method of rapid stirring and mixing of raw materials and micro-spraying, which has the following obvious advantages:

1) A biodegradable group is introduced during the formation of the polyurethane coating material, so that the coating material has the ability to degrade the environment, ensuring that the coated controlled-release fertilizer will not bring the so-called The "white pollution" has achieved environmental friendliness;

2) This technological process realizes the uniform mixing of isocyanate and polyol components before reaching the fertilizer granules, which improves the chemical composition uniformity of the membrane material reaching the fertilizer granules, thereby improving the controlled release performance of the membrane material;

3) This process adopts the method of micro-spraying, so that the uniformly mixed membrane material can directly reach the surface of the fertilizer to the greatest extent, and solidify to form a film, thereby greatly improving the uniformity of the membrane material distribution on the fertilizer particles and improving the quality of the controlled-release membrane. comprehensive performance.

Description of drawings

Fig. 1 is a process flow chart of the present invention for producing coated controlled-release fertilizers, wherein 1 and 2 are reactors, 3 is a proportional pump, 4 is a mixer, and 5 is a drum or a fluidized bed.

Detailed ways

The process steps of the present invention's production coated controlled-release fertilizer are as follows:

1. Weigh a certain amount of fertilizer granules and place them in a drum or a fluidized bed (shown as 5 in Figure 1) for preheating, keeping the preheating temperature within the range of 50-90°C.

2. Calculate the amount of coating material according to 2% to 10% of the mass of the core fertilizer granules. Taking the fertilizer dosage of 10kg as an example, the dosage range of the coating material is 200g~1000g. When calculating the content of the two components of isocyanate and polyol, the ratio of the amount of the isocyanate group to the OH (hydroxyl) group is guaranteed. 1:2～2:1, the content of degradable functional monomer is 1%～20% of the total film material; the content of film-forming agent is 0%～30% of the total film material; the content of chain extender is 0% to 15% of the total weight of the material; the content of the catalyst is 0% to 0.05% of the total weight of the membrane material. Preheat the isocyanate and polyol components in a constant temperature heating reactor (shown as 1 and 2 in Figure 1), the preheating temperature of the isocyanate component is 50-100 ° C, and the preheating temperature of the polyol component is 65 ~95°C.

3. Turn on the proportional pump (shown as 3 in Figure 1), the proportional pump can adjust the ratio of volume ratio and output pressure, adjust the flow rate and atomization pressure (pressure is 0.0015 ~ 8MPa), and the two-component liquid is mixed through the high-efficiency mixer Finally, start spraying, and the spraying time is 1 to 30 minutes. After spraying, keep the temperature at 50-90° C., turn off the heating system after 10 minutes, cool down, and obtain the coated controlled-release fertilizer.

The above-mentioned coated controlled-release fertilizer is tested for controlled-release performance:

Use the water immersion method to measure the release period of the coated controlled-release fertilizer, that is, weigh 10.00g of the developed fertilizer sample, put it into a nylon mesh bag, then immerse it in a plastic bottle containing 200mL of distilled water, seal it, and place it in a constant temperature culture at 25°C Stand in the box, leaching, and set three replicates for each sample. When sampling, ensure that the nylon mesh bag is placed in a plastic bottle, shake the extract and take it out for the determination of N, P, and K. At the same time, add 200 mL of distilled water and continue culturing in a constant temperature incubator. The sampling and determination time is 1 day, 7 days , 10 days, 14 days, 21 days, 28 days. Among them, the determination of N element adopts GB/T 8572-2001 standard; the determination of P element adopts GB/T 8573-1999 standard; the determination of K element adopts GB/T 8574-1988 standard.

Controlled release performance evaluation index of coated controlled release fertilizer:

Initial dissolution rate η _t1 = M _t1 /M × 100%, differential dissolution rate η _Δt = (η _tn -η _t1 )/(t _n -t ₁ ) × 100%, cumulative release rate η = Σ(η _tn ), The nutrient release period T=1+(80%-η _t1 )/η _Δt . t _n is the nth day, _t1 is the 1st day, η _tn is the cumulative release rate of the ni day, η _t1 is the initial dissolution rate, M _t1 is the nutrient amount dissolved on the 1st day, and M is the nutrient in the coated fertilizer total amount.

Evaluation of biodegradability: Accurately weigh the film materials of different polymer-coated controlled-release fertilizers and bury them in the soil, take samples every month, wash off the soil on the surface, dry them, weigh them again, and calculate the test results. Sample weight loss rate.

The following specific examples are given to further illustrate the present invention.

Embodiment 1,

Weigh 10 kg of large granular urea with a particle diameter of 3 mm, place it in the drum, turn on the heating switch of the drum, and preheat the fertilizer until the temperature is constant at 85° C. Weigh 150 g of diphenylmethane diisocyanate (MDI), add 60 g of paraffin (film-forming agent), and place it in a heating kettle to melt and keep the temperature at 75°C. Weigh 210g of polyether polyol series (Type 635 of Jingzhou Longhua Petrochemical Company), 20g of 2,3-butanediol (chain extender), 20g of tannin (degradable functional monomer), and place in a heating kettle to melt at constant temperature 90°C. Then open the vent valve of the proportional pump, and then open the pump inlet valve, so that the two-component liquid is mixed through the high-efficiency mixer, adjust the pressure of the pump to 0.1Mpa, and the total spray rate is 0.15 liters/minute, and start spraying. After continuous spraying for 3 minutes, stop spraying, keep warm at 90° C., react for 8 minutes and then cool down to obtain coated controlled-release fertilizer. The controlled-release performance was measured by water immersion method, the initial dissolution rate was 1.2%, the controlled-release period was 48 days, and the polymer film degraded 12% within 12 months.

Example 2

Weigh 10Kg of the 16-16-16 Russia Akon compound fertilizer, place it in the drum, turn on the heating switch of the drum, and preheat the fertilizer until the temperature is constant at 85°C. Weigh 100 g of hexamethylene diisocyanate (HDI), add 80 g of rosin ester (film-forming agent), and place it in a heating kettle to melt at a constant temperature of 75°C. Take by weighing castor oil 260g, 1,4-butanediol 20g (chain extender), regenerated cellulose 30g (degradable functional monomer), and add 0.1g diethylenetriamine (catalyst), place heating kettle The medium melting temperature is 80°C. Then open the air release valve of the proportional pump, and then open the pump inlet valve to mix the two-component liquids. After mixing by the high-efficiency mixer, adjust the pump pressure to 0.1MPa, and the total spray rate to 0.15 liters/minute, and start spraying. Spray continuously for 12 minutes each time, then keep warm for 4 minutes and continue spraying until the coating solution is completely sprayed, then stop spraying, keep warm at 85°C for 10 minutes, cool down to obtain coated controlled-release fertilizer. The controlled-release performance was measured by water immersion method, the initial dissolution rate was 0.9%, the controlled-release period was 63 days, and the polymer membrane material degraded 9% within 12 months.

Example 3

Weigh 10Kg of 15-15-15 Sacofu compound fertilizer, put it in the drum, turn on the heating switch of the drum, and preheat the fertilizer until the temperature is constant at 85°C. Weigh 200 g of toluene diisocyanate (TDI), add 140 g of sulfonated paraffin (film-forming agent), and place it in a heating kettle to melt at a constant temperature of 70°C. Take polybutylene adipate 420g, 1,6-hexanediol (chain extender) 40g, chitosan (degradable functional monomer) 65g, and add 0.1g stannous octoate (catalyst), place Melt in a heating kettle at a constant temperature of 80°C. Then open the vent valve of the proportional pump, and then open the pump inlet valve to mix the two-component liquid through the high-efficiency mixer, adjust the pump pressure to 0.1MPa, and the total spray rate to 0.075 liters/minute, and start spraying. Continuous spraying for 6 minutes, until the coating solution is completely sprayed, stop spraying, keep warm at 90°C for 10 minutes, cool down, and obtain coated controlled-release fertilizer. The controlled-release performance was measured by water immersion method, the initial dissolution rate was 0.3%, the controlled-release period was 89 days, and the polymer membrane material degraded 7% within 12 months.

Example 4

Weigh 10Kg of large granular urea with a particle diameter of 3mm, place it in the drum, turn on the heating switch of the drum, and preheat the fertilizer until the temperature is constant at 85°C. Weigh 165g of dicyclohexylmethane diisocyanate (HMDI), add 90g of petroleum resin (film-forming agent), place in a heating kettle and melt at a constant temperature of 80°C, weigh 240g of polyethylene succinate, sorbitol (chain extender) agent) 35g, glucose (degradable functional monomer) 60g, and 0.1g triethylamine (catalyst) was added, and placed in a heating kettle to melt at a constant temperature of 90°C. Then open the vent valve of the proportional pump, and then open the pump inlet valve to mix the two-component liquid through the high-efficiency mixer, adjust the pump pressure to 0.1MPa, and the total spray rate to 0.075L/min, and start spraying. Continuous spraying for 6 minutes, until the coating solution is completely sprayed, stop spraying, keep warm at 90°C for 10 minutes, cool down, and obtain coated controlled-release fertilizer. The controlled-release performance was measured by water immersion method, the controlled-release period was 79 days, and the polymer membrane material degraded 8% within 12 months.

Example 5

Weigh 10Kg of 15-15-15 Sacofu compound fertilizer, place it in the drum, turn on the heating switch of the drum, and preheat the fertilizer until the temperature is constant at 85°C. Weigh 150 g of toluene diisocyanate (TDI), add 90 g of rosin ester (film-forming agent), and place it in a heating kettle to melt at a constant temperature of 85°C. Weigh 320g of polyolefin polyol, 23g of trimethylolpropane (chain extender), 30g of sucrose (degradable functional monomer), add 0.05g of triethanolamine (catalyst), and place in a heating kettle to melt at a constant temperature of 80°C. Then open the vent valve of the proportional pump, and then open the pump inlet valve to mix the two-component liquid through the high-efficiency mixer, adjust the pump pressure to 0.1MPa, and the total spray rate to 0.075L/min, and start spraying. Continuous spraying for 6 minutes, until the coating solution is completely sprayed, stop spraying, keep warm at 90°C for 10 minutes, then cool down to obtain coated controlled-release fertilizer. The controlled-release performance was measured by water immersion method, the initial dissolution rate was 0.5%, the controlled-release period was 92 days, and the polymer membrane material degraded 7% within 12 months.

Example 6

Weigh 10Kg of Russian Acon 16-16-16 compound fertilizer, put it in the drum, turn on the heating switch of the drum, and preheat the fertilizer until the temperature is constant at 80°C. Weigh 240 g of polymethylene polyphenyl isocyanate (PAPI), add 100 g of chlorinated paraffin (film-forming agent), and place it in a heating kettle to melt at a constant temperature of 85°C. Weigh 390g of polytetrahydrofuran glycol, 15g of glycerin (chain extender), 50g of cellulose acetate (degradable functional monomer), add 0.1g of N-ethylmorpholine, and place it in a heating kettle to melt at a constant temperature of 80°C. Then open the air release valve of the proportional pump, and then open the pump inlet valve to mix the two-component liquid through the high-efficiency mixer, adjust the pump pressure to 0.1MPa, and the total spray rate to 0.065L/min, and start spraying. Spray continuously for 5 minutes until the coating solution is completely sprayed, then stop, keep the temperature at 80°C for 8 minutes, then cool down to obtain a coated controlled-release fertilizer. The controlled-release performance was measured by water immersion method, the controlled-release period was 88 days, and the polymer membrane material degraded 8% within 12 months.

Claims (10)

1, a kind of coated fertilizer of polymer coating controlled release fertilizer comprises: isocyanic ester, polyvalent alcohol, degradable function monomer, furtherance film and chainextender; Wherein, the mol ratio of oh group is 1: 2～2: 1 in isocyano group in the described isocyanic ester and the polyvalent alcohol, the quality of described degradable function monomer is the 1%-20% of described coated fertilizer quality, the quality of described furtherance film and the mass ratio of described coated fertilizer are greater than 0 smaller or equal to 30%, and the quality of described chainextender and the mass ratio of described coated fertilizer are smaller or equal to 15% greater than 0.

2, coated fertilizer according to claim 1 is characterized in that: described coated fertilizer also comprises catalyzer, and the quality of described catalyzer and the mass ratio of described coated fertilizer are smaller or equal to 0.05% greater than 0.

3, coated fertilizer according to claim 1 and 2 is characterized in that:

Described isocyanic ester is a kind of or its arbitrary combination in following 27 kinds of isocyanic ester: tolylene diisocyanate, diphenylmethanediisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexyl methane diisocyanate, naphthalene diisocyanate, to the phenylmethane vulcabond, 1,4-bicyclohexane vulcabond, xylylene diisocyanate, the cyclohexanedimethyleterephthalate vulcabond, trimethylammonium-1, the 6-hexamethylene diisocyanate, tetramethyl-mphenylenedimethylim-vulcabond, the dimethyl diphenyl vulcabond, Methylcyclohexyl diisocyanate, norbornene alkyl diisocyanate, polymethylene multi-phenenyl isocyanate, the liquefaction diphenylmethanediisocyanate, toluene diisocyanate dimer, toluene diisocyanate trimer, tolylene diisocyanate-TriMethylolPropane(TMP) affixture, tolylene diisocyanate-hexamethylene diisocyanate mixing polymer, hexamethylene diisocyanate trimer, the hexamethylene diisocyanate biuret, isophorone diisocyanate trimer, triphenylmethane triisocyanate, tri o cresyl thiophosphate (4-phenyl isocyanate) and dimethyl triphenyl methane tetraisocyanate;

Described polyvalent alcohol be following a) and/or b) and/or c) and/or d):

Described a) at least a in following 14 kinds of polyether glycols: polyoxyethylene polyvalent alcohol, polyoxypropyleneglycol, polyoxytrimethylene triol, high activity polyether triol, polyether tetrols, quadrol polyether glycol, high functionality polyether glycol, polytetrahydrofuran diol, contain side chain polytetrahydrofuran diol, tetrahydrofuran (THF)-propylene oxide copolyether glycol, tetrahydrofuran (THF)-ethylene oxide copolymerization glycol, polyurea polylol, polyacrylate polyol and polyethylene polyvalent alcohol;

Described b) is at least a in the following three vegetable oil polyvalent alcohols: Viscotrol C, soybean oil polyvalent alcohol and plam oil polyvalent alcohol;

Described c) is at least a in following eight kinds of polyester polyols: polyethylene glycol succinate, poly butylene succinate, polyethylene glycol adipate, poly adipate succinic acid ester, Aromatic Polyester Polyols, polymerized thylene carbonate ethyl ester, polycarbonate diol and polycaprolactone polyol;

Described d) is at least a in following five kinds of materials: polysuccinimide, polyglycolic acid, poly(lactic acid), polycaprolactone and poly-(ε-ketone in oneself) glycol.

Described degradable function monomer is at least a in the following substances: tannin, xylogen, polyamino acid, gelatin modified resin, sericin modified resins, lignin modified resin, birds droppings glue, the natural high polymer from vegetables oil, monose, disaccharides, oligosaccharides, polysaccharide;

Described monose is at least a in the following sugar: erythrose, ribose, pectinose, wood sugar, lyxose, allose, altrose, glucose, seminose, gulose, her shut out sugar, semi-lactosi, talose, fructose, Glucopyranose, glucofuranose, galactofuranose, arabopyranose, pyranofructose, xylulose, ribulose, sedoheptulose, rhamnosyl, Fucose, glycosamine and GalN;

Described polysaccharide is at least a in the following sugar: chitosan, molasses, chitin, take off second phthalein chitin, Mierocrystalline cellulose, modified-cellulose, starch and Sudan Gum-arabic;

Described Mierocrystalline cellulose is at least a in the following substances: nitrocellulose, cellulose acetate, ethyl cellulose, regenerated cellulose, match fine jade Lip river viscose rayon, glassine paper, copper are by silk, cuprophane, hemicellulose and lignin;

Described furtherance film is a kind of or its arbitrary combination in paraffin, clorafin, sulfonation paraffin, rosin ester, petroleum resin, terpine resin and the pitch;

Described chainextender is 1,4-butyleneglycol, 2,3-butyleneglycol, glycol ether, 1, a kind of or its arbitrary combination in 6-hexylene glycol, glycerine, TriMethylolPropane(TMP) and the sorbyl alcohol.

4, according to claim 2 or 3 described coated fertilizers, it is characterized in that: described catalyzer is a kind of or its arbitrary combination in following 18 kinds of materials: dibutyl tin laurate, stannous octoate, triethylamine, the dimethyl cetylamine, two dimethyl amine benzyl ethyl ethers, diethylenetriamine, triethylenediamine, tetramethyl butane diamine, N-Ethylmorphine quinoline, N, the N-dimethylcyclohexylamine, trolamine, methyldiethanolamine, dimethylethanolamine, pyridine, N, N '-lutidine, 1,2, the 4-tri methyl piperazine, two ketoimines and α-Qiu Jibenbingmizuo.

5, a kind of polymer coating controlled release fertilizer is made up of nuclear core and nuclear membrane, and wherein, described nuclear core is a granulated fertilizer, and described nuclear membrane is made by arbitrary described coated fertilizer among the claim 1-4, and described nuclear membrane quality is the 2%-10% of described nuclear core quality.

6, fertilizer according to claim 5 is characterized in that: the median size of described granulated fertilizer is 2-6mm.

7, a kind of coating liquid of coated fertilizer is prepared according to following method:

1) with following a) and b) be preheated to molten state respectively, described a) is isocyanic ester in arbitrary described coated fertilizer and furtherance film among the claim 1-5; Described b) comprises the polyvalent alcohol in arbitrary described coated fertilizer, degradable function monomer and chainextender among the claim 1-5;

2) with described a) and b) mix, mixing time is 0.1-20 second, makes described coating liquid.

8, coating liquid according to claim 7 is characterized in that: the b in the described step 1)) also comprise the catalyzer in arbitrary described coated fertilizer among the claim 2-4.

9, a kind of method for preparing claim 5 or 6 described polymer coating controlled release fertilizers may further comprise the steps:

1) granulated fertilizer is placed rotary drum or fluidized-bed carry out preheating;

2) claim 7 or 8 described coating liquids are atomized on particles preheated fertilizer surface, make film-coated controlled release fertilizer.

10, according to the described method of claim 9, it is characterized in that: realize by atomizer on the fertiliser granulates surface that described step 2) described coating liquid is atomized on preheating, described atomizer is the pressure type shower nozzle, the atomizing pressure scope is 0.0015MPa～0.8MPa, and the atomizing flow velocity of described coating solution is 0.01～1kg/ minute.

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