An organosilicon coating material and a method for preparing a controlled-release fertilizer therefrom

Abstract

The present invention discloses a silicone coating material, which comprises the following components by mass fraction: 20 to 31.5 parts of silane; 1 to 1.6 parts of cetyltrimethylammonium bromide; 1 to 2 parts of pH regulator; 40 to 80 parts of water. The present invention also discloses a method for preparing a controlled-release fertilizer using the silicone coating material. The present invention is applicable to the technical field of coated fertilizers. The silicone material has the characteristics of both organic materials and inorganic materials. The prepared polymer has extremely strong physiological inertia, stable material properties, and the main component is silicon dioxide, which is also pollution-free to the environment. It has strong molecular designability, and corresponding functional groups can be added according to needs to achieve functions such as hydrophobicity and antibacterial, realizing the multifunctionality of the coated controlled-release fertilizer, and greatly improving the controlled-release performance and utilization efficiency of the coated controlled-release fertilizer. It improves the film layer uniformity and controlled-release property of the coated fertilizer, and realizes the continuous production of the coated controlled-release fertilizer.

Description

Technical Field

[0001] The present invention belongs to the technical field of coated fertilizers, and specifically relates to an organosilicon coating material and a method for preparing a controlled-release fertilizer therefrom. Background Art

[0002] A controlled-release fertilizer refers to a fertilizer that, through various regulation mechanisms, presets the release mode of the fertilizer during the crop growth season so that the nutrient release thereof is consistent with the fertilizer requirement law of the crop. It is mainly an organic polymer-coated fertilizer, and the film material is usually an organic polymer such as polyurethane or polyethylene. However, in the process of preparing the organic polymer-coated fertilizer, there are not only problems of pollution caused by the volatilization of organic solvents, but also the film shell is not easily degraded when the fertilizer is applied to the soil, resulting in microplastics. Therefore, how to make the polymer coating material green and environmentally friendly has become the main problem of polymer-coated fertilizers.

[0003] Organosilicon materials belong to high-molecular materials with an inorganic hetero-chain as the main chain and an organic structure as the side chain, and have the characteristics of both organic materials and inorganic materials. They have characteristics such as low surface tension, small intermolecular force, low cohesive energy density, excellent air permeability, heat resistance, weather resistance, water repellency, non-toxic, odorless, and physiological inertness. The organosilicon film prepared with it as the matrix is a new type of high-molecular material with excellent performance and wide applications. It can be widely used as a separation and purification, protection material in agriculture, industry, and the electronics industry.

[0004] Organoalkoxysilanes and chlorosilanes are one of the commonly used materials for preparing organosilicon materials at present. The principle is that silane or chlorosilane is first acid-catalyzed and polycondensed into a prepolymer in water or an aqueous alcohol solution. The solution contains a large number of hydrolyzed silanol groups, unreacted alkoxy groups, etc. Heating or adding a basic catalyst is used to promote the condensation reaction between the hydroxyl group and the alkoxy group to form a crosslinked network structure.

[0005] A method for preparing an organosilicon coating disclosed in Publication No. CN117343640A. This technical solution hydrolyzes and polycondenses using silicone oil, silicone resin, and a modified organosilicon material to form a continuous and smooth organosilicon coating material at room temperature. However, the application field of this solution is coatings, so this technical solution does not explore the problems that occur when it is applied in the coating field; A method for preparing an organosilicon-coated potassium silicate water-soluble slow-release conditioner and its preparation method and application disclosed in Publication No. CN117185864A. This method uses methyltriethoxysilane and dimethyldiethoxysilane to synthesize an organosilicon-coated fertilizer under hydrochloric acid catalysis at 60-90°C. It completely uses acid catalysis and does not use a solvent. This reaction is exothermic. The absence of a solvent may lead to difficulties in heat dissipation, resulting in local explosion polymerization, uneven polymerization degree, and affecting the performance of the film shell. Secondly, the absence of a solvent will cause a sharp increase in the viscosity of the coating solution, restricting the coating process.

[0006] However, existing organosilanes have many disadvantages when used in the coating field:

[0007] 1. Studies have shown that most organosilicon materials are synthesized without solvent or with organic solvents. Without solvent, the reaction may be highly exothermic, and the viscosity will increase as the reaction proceeds, which will limit the coating process. Organic solvents have problems such as high cost and difficulty in recycling.

[0008] 2. Hydrochloric acid is often used as a catalyst. Some plants are chlorine-averse, so if you want to prepare fertilizers, you should avoid using hydrochloric acid as much as possible.

[0009] 3. Metal salts are often added as catalysts during the synthesis process, such as manganese, copper, and yttrium. If used for a long time, it may cause metal accumulation and cause heavy metal poisoning.

[0010] 4. If the selection ratio of the organosilane is unreasonable, the organosilane will generate a structural prepolymer after acid hydrolysis. If the acidity in the reaction is too strong, it will directly lead to acid curing of the prepolymer. The prepolymer will cure too quickly under alkaline conditions and easily gel to form a loose structure, blocking the fluidized bed spray head. In addition, the prepared silicone film layer is too brittle and has almost no toughness, resulting in the breakage of the film shell and failure to achieve the ideal release effect. Summary of the invention

[0011] The purpose of the present invention is to overcome the defects of the prior art and provide an organosilicon coating material and a method for preparing a controlled-release fertilizer thereof.

[0012] To achieve the above object, the present invention adopts the following technical solutions:

[0013] An organosilicon coating material and a method for preparing a controlled-release fertilizer thereof, comprising the following components by mass fraction:

[0014] 20 to 31.5 parts of organosilane;

[0015] 1-1.6 parts of hexadecyltrimethylammonium bromide;

[0016] 1-2 parts pH adjuster;

[0017] 40-80 parts of water.

[0018] Preferably, the organosilane comprises the following components by mass fraction:

[0019] 10-20 parts of methyltrimethoxysilane;

[0020] 4 to 13 parts of dimethyldimethoxysilane;

[0021] 1 to 5 parts of tetraethoxysilane;

[0022] 0.2 to 0.315 parts of 1H,1H,2H,2H,-perfluorodecyltrimethoxysilane.

[0023] Preferably, the methyltrialkoxysilane is methyltrimethoxysilane or methyltriethoxysilane; the tetraalkoxysilane is tetramethoxysilane or tetraethoxysilane.

[0024] Preferably, the molar ratio of the methyltrimethoxysilane, dimethyldimethoxysilane to tetraethoxysilane is 1 to 3: 0.5 to 1.5: 0.1 to 0.5; the mass of cetyltrimethylammonium bromide is 5% of the total amount of the methyltrimethoxysilane, dimethyldimethoxysilane and tetraethoxysilane.

[0025] Preferably, the mass of the water is not less than 3 times the mass of the methyltrimethoxysilane.

[0026] Preferably, the overall concentration of the methyltrimethoxysilane, dimethyldimethoxysilane and tetraethoxysilane is 20 to 40 wt%; the initial pH is 3 to 6.

[0027] Preferably, the pH regulator is hydrochloric acid, acetic acid and ammonia water.

[0028] In a second aspect, a method for preparing a controlled-release fertilizer with an organosilicon coating material includes the following steps:

[0029] S1 Add the formulated amount of acid, the formulated amount of cetyltrimethylammonium bromide, and the formulated amount of water into a beaker and stir on a magnetic stirrer;

[0030] S2 Weigh the formulated amounts of methyltrimethoxysilane, dimethyldimethoxysilane, tetraethoxysilane, and 1H,1H,2H,2H,-perfluorodecyltrimethoxysilane, and add them into the beaker in the first step in sequence, and pay attention to keeping the temperature of the beaker at 20 to 30 °C to obtain a silane prepolymer;

[0031] S3 After the solution reacts for 90 to 110 min, turn on the Roots blower. After the air flow is buffered and balanced by the buffer tank and then heated by the electric heater, it circulates in the fluidized bed for about 15 to 20 min, and ensure that the temperature in the fluidized bed is 70 to 80 °C to make the fluidized bed in a working state;

[0032] S4 Add 1 to 2 Kg of large granular fertilizer into the fluidized bed for preheating for 2 to 5 min, and then use the compressed air provided by the air compressor to pass through the nozzle to pre-treat the surface of the urea particles, and the treatment time is 2 to 5 min;

[0033] S5 Add the silane prepolymer obtained in step S2 into the coating liquid storage tank, and use a peristaltic pump to transport it to the nozzle to atomize it onto the surface of the fertilizer particles;

[0034] The reaction materials of S6 are input into the nozzle for atomization at a speed of 10 - 20 ml / min, and the operation is carried out for 20 - 40 min. Then, the addition of the reaction materials is stopped, the film coating is completed, and the film-coated sample is taken out.

[0035] Preferably, the large granular fertilizer includes ammonium chloride, ammonium sulfate, monoammonium phosphate, urea, and compound fertilizer.

[0036] Preferably, the dosage of 1H,1H,2H,2H,-perfluorodecyltrimethoxysilane is 1% of the total mass of methyltrimethoxysilane, tetraethoxysilane, and dimethyldimethoxysilane.

[0037] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0038] In the present invention, water is used as the solvent, which is green, pollution-free, low in price, and the viscosity of the film coating liquid is small, not easy to block the channels, and easy to clean, etc.;

[0039] In the present invention, the silicone material has the characteristics of both organic materials and inorganic materials. The prepared polymer has extremely strong physiological inertness, the material is stable, and the main component is silicon dioxide material, which is also pollution-free to the environment.

[0040] In the present invention, the molecular designability is strong, and corresponding functional groups can be added to the material according to needs to achieve functions such as hydrophilicity, hydrophobicity, and antibacterial. Thus, the film-coated fertilizer has multiple functions.

[0041] In the present invention, the production efficiency of the slow-release and controlled-release fertilizer can be improved to a large extent, and because the reaction is carried out continuously, the quality of the film-coated fertilizer is more stable and reliable. Description of the Drawings

[0042] Figure 1 is the microscopic photograph of the silicone film coating material film in Example 7 of the present invention;

[0043] Figure 2 is the microscopic photograph of the prepared silicone film-coated fertilizer in Example 8 of the present invention;

[0044] Figure 3 is the contact angle photograph of the prepared silicone film-coated fertilizer in Example 8 of the present invention;

[0045] Figure 4 is the contact angle photograph of the prepared fertilizer containing 1H,1H,2H,2H,-perfluorodecyltrimethoxysilane in Example 9 of the present invention;

[0046] Figure 5 is the process flow chart of the silicone film-coated fertilizer of the present invention;

[0047] Reference numerals: 1, Roots blower; 2, gas buffer tank; 3, heater; 4, air compressor; 5, fluidized bed; 6, peristaltic pump; 7, coating liquid storage tank. Detailed implementation manners

[0048] The following further illustrates the detailed implementation manners of an organosilicon coating material and a method for preparing a controlled-release fertilizer thereof according to the present invention. The organosilicon coating material and the method for preparing a controlled-release fertilizer thereof according to the present invention are not limited to the descriptions of the following embodiments.

[0049] Example 1:

[0050] An organosilicon coating material, by mass fraction, comprises the following components:

[0051] 20 parts of organosilane;

[0052] 1 part of cetyltrimethylammonium bromide;

[0053] 1 part of pH regulator;

[0054] 78 parts of water.

[0055] Furthermore, the organosilane, by mass fraction, comprises the following components:

[0056] 10 parts of methyltrimethoxysilane;

[0057] 8 parts of dimethyldimethoxysilane;

[0058] 2 parts of tetraethoxysilane;

[0059] 0.2 part of 1H,1H,2H,2H,-perfluorodecyltrimethoxysilane.

[0060] Furthermore, the molar ratio of methyltrimethoxysilane, dimethyldimethoxysilane to tetraethoxysilane is 1:0.9:0.13; the mass of cetyltrimethylammonium bromide is 5% of the total amount of methyltrimethoxysilane, dimethyldimethoxysilane and tetraethoxysilane.

[0061] Furthermore, the mass of water is not less than 3 times the mass of methyltrimethoxysilane.

[0062] Furthermore, the overall concentration of methyltrimethoxysilane, dimethyldimethoxysilane and tetraethoxysilane is 20 wt%; the initial pH is 5.

[0063] Furthermore, the pH regulator is hydrochloric acid, acetic acid and ammonia water.

[0064] Example 2:

[0065] An organosilicon coating material, by mass fraction, comprises the following components:

[0066] 25 parts of organosilane;

[0067] 1.25 parts of cetyltrimethylammonium bromide;

[0068] 1.5 parts of pH regulator;

[0069] 56 parts of water.

[0070] Further, the organosilane, by mass fraction, includes the following components:

[0071] 15 parts of methyltrimethoxysilane;

[0072] 8.5 parts of dimethyldimethoxysilane;

[0073] 1.5 parts of tetraethoxysilane;

[0074] 0.25 part of 1H,1H,2H,2H,-perfluorodecyltrimethoxysilane.

[0075] Further, the molar ratio of methyltrimethoxysilane, dimethyldimethoxysilane to tetraethoxysilane is 2:1.28:0.12; the mass of cetyltrimethylammonium bromide is 5% of the total amount of methyltrimethoxysilane, dimethyldimethoxysilane and tetraethoxysilane.

[0076] Further, the mass of water is not less than 3 times the mass of methyltrimethoxysilane.

[0077] Further, the overall concentration of methyltrimethoxysilane, dimethyldimethoxysilane and tetraethoxysilane is 30 wt%; the initial pH is 4.

[0078] Further, the pH regulator is hydrochloric acid, acetic acid and ammonia water.

[0079] Example 3:

[0080] An organosilicon coating material, by mass fraction, includes the following components:

[0081] 31.5 parts of organosilane;

[0082] 1.6 parts of cetyltrimethylammonium bromide;

[0083] 2 parts of pH regulator;

[0084] 42 parts of water.

[0085] Further, the organosilane, by mass fraction, includes the following components:

[0086] 12 parts of methyltrimethoxysilane;

[0087] 13 parts of dimethyldimethoxysilane;

[0088] 5 parts of tetraethoxysilane;

[0089] 0.315 part of 1H,1H,2H,2H-perfluorodecyltrimethoxysilane.

[0090] Furthermore, the molar ratio of methyltrimethoxysilane, dimethyldimethoxysilane to tetraethoxysilane is 1:1.22:0.27; the mass of cetyltrimethylammonium bromide is 5% of the total amount of methyltrimethoxysilane, dimethyldimethoxysilane and tetraethoxysilane.

[0091] Furthermore, the mass of water is not less than 3 times the mass of methyltrimethoxysilane.

[0092] Furthermore, the overall concentration of methyltrimethoxysilane, dimethyldimethoxysilane and tetraethoxysilane is 40 wt%; the initial pH is 3.

[0093] Furthermore, the pH regulator is hydrochloric acid and acetic acid ammonia water.

[0094] Example 4:

[0095] A method for preparing a controlled-release fertilizer with an organosilicon coating material, comprising the following steps, wherein the formulation amounts of each component are as shown in Example 1:

[0096] S1 Add the formulated amount of acid, the formulated amount of cetyltrimethylammonium bromide, and the formulated amount of water to a beaker and stir on a magnetic stirrer;

[0097] S2 Weigh the formulated amounts of methyltrimethoxysilane, dimethyldimethoxysilane, tetraethoxysilane, and 1H,1H,2H,2H-perfluorodecyltrimethoxysilane, and add them to the beaker in the first step in sequence, and note that the temperature of the beaker is kept at 20 °C to obtain a silane prepolymer;

[0098] S3 After the solution reacts for 90 min, turn on Roots blower 1. After the air flow is buffered and balanced by buffer tank 2 and then output, it is heated by electric heater 3 and then enters fluidized bed 5 and circulates for about 15 min to ensure that the temperature in the fluidized bed is 70 °C to make the fluidized bed in a working state;

[0099] S4 Add 1 Kg of large granular fertilizer to the fluidized bed and preheat it for 2 min, and then use the compressed air provided by air compressor 4 to pass through the nozzle to pretreat the surface of the urea particles for 2 min;

[0100] S5 Add the silane prepolymer obtained in step S2 to the coating liquid storage tank 7, then add 1 part of ammonia water and stir to mix evenly. Use peristaltic pump 6 to transport it to the nozzle and atomize it onto the surface of the fertilizer particles;

[0101] The reaction materials are input into the nozzle for atomization at a speed of 10 ml / min, and the operation is carried out for 20 min. Then, the addition of the reaction materials is stopped, the coating is completed, and the coated sample is taken out.

[0102] Furthermore, the large granular fertilizer includes ammonium chloride, ammonium sulfate, monoammonium phosphate, urea, and compound fertilizer.

[0103] Furthermore, the dosage of 1H,1H,2H,2H,-perfluorodecyltrimethoxysilane is 1% of the total mass of methyltrimethoxysilane, tetraethoxysilane, and dimethyldimethoxysilane.

[0104] Example 5:

[0105] A method for preparing a controlled-release fertilizer with an organosilicon coating material, comprising the following steps, wherein the formulation amounts of each component are as shown in Example 2:

[0106] S1 Add the formulated amount of acid, the formulated amount of cetyltrimethylammonium bromide, and the formulated amount of water into a beaker and stir on a magnetic stirrer;

[0107] S2 Weigh the formulated amounts of methyltrimethoxysilane, dimethyldimethoxysilane, tetraethoxysilane, and 1H,1H,2H,2H,-perfluorodecyltrimethoxysilane, and add them into the beaker in the first step in sequence. Note that the temperature of the beaker is kept at 25 °C to obtain a silane prepolymer;

[0108] S3 After the solution reacts for 100 min, turn on Roots blower 1. After the air flow is buffered and balanced by buffer tank 2 and then heated by electric heater 3, it enters fluidized bed 5 and circulates for about 18 min. Ensure that the temperature in the fluidized bed is 75 °C to make the fluidized bed in a working state;

[0109] S4 Add 1.5 Kg of large granular fertilizer into the fluidized bed for preheating for 4 min, and then use the compressed air provided by air compressor 4 to pass through the nozzle to pretreat the surface of the urea particles for 4 min;

[0110] S5 Add the silane prepolymer obtained in step S2 into coating liquid storage tank 7, then add 1.5 parts of ammonia water and stir to mix evenly. Use peristaltic pump 6 to transport it to the nozzle and atomize it onto the surface of the fertilizer particles;

[0111] S6 The reaction materials are input into the nozzle for atomization at a speed of 15 ml / min, and the operation is carried out for 30 min. Then, the addition of the reaction materials is stopped, the coating is completed, and the coated sample is taken out.

[0112] Furthermore, the large granular fertilizer includes ammonium chloride, ammonium sulfate, monoammonium phosphate, urea, and compound fertilizer.

[0113] Further, the dosage of 1H,1H,2H,2H,-perfluorodecyltrimethoxysilane is 1% of the total mass of methyltrimethoxysilane, tetraethoxysilane and dimethyldimethoxysilane.

[0114] Example 6:

[0115] A method for preparing a controlled-release fertilizer with an organosilicon coating material, comprising the following steps, wherein the formulation amounts of each component are as shown in Example 3:

[0116] S1 Add the formulated amount of acid, the formulated amount of cetyltrimethylammonium bromide, and the formulated amount of water to a beaker and stir on a magnetic stirrer;

[0117] S2 Weigh the formulated amounts of methyltrimethoxysilane, dimethyldimethoxysilane, tetraethoxysilane, and 1H,1H,2H,2H,-perfluorodecyltrimethoxysilane, and add them to the beaker in the first step in sequence. Note that the temperature of the beaker is maintained at 30 °C to obtain a silane prepolymer;

[0118] S3 After the solution reacts for 110 min, turn on the Roots blower 1. After the air flow is buffered and balanced by the buffer tank 2 and then heated by the electric heater 3, it enters the fluidized bed 5 and circulates for about 20 min to ensure that the temperature in the fluidized bed is 80 °C, so that the fluidized bed is in a working state;

[0119] S4 Add 2 Kg of large granular fertilizer to the fluidized bed and preheat it for 5 min, and then use the compressed air provided by the air compressor 4 to pass through the nozzle to pretreat the surface of the urea particles for 5 min;

[0120] S5 Add the silane prepolymer obtained in step S2 to the coating liquid storage tank 7, then add 2 parts of ammonia water and stir evenly. Use the peristaltic pump 6 to transport it to the nozzle and atomize it onto the surface of the fertilizer particles;

[0121] S6 The reaction material is input into the nozzle for atomization at a speed of 20 ml / min, and the operation is carried out for 40 min. Then, stop adding the reaction material, and the coating is completed. Take out the coated sample.

[0122] Further, the large granular fertilizer includes ammonium chloride, ammonium sulfate, monoammonium phosphate, urea, and compound fertilizer.

[0123] Further, the dosage of 1H,1H,2H,2H,-perfluorodecyltrimethoxysilane is 1% of the total mass of methyltrimethoxysilane, tetraethoxysilane and dimethyldimethoxysilane.

[0124] Example 7:

[0125] A method for preparing an organosilicon coating material film, comprising the following steps:

[0126] Preparation of water-soluble coating solution: S1, Weigh 1.25 g of cetyltrimethylammonium bromide, 1.5 ml of acetic acid, and 56 ml of water and add them to a beaker and stir; S2, Weigh 15 g of methyltrimethoxysilane, 1.5 g of tetraethoxysilane, and 8.5 g of dimethyldimethoxysilane and add them to S1, and stir for 120 min.

[0127] Preparation of the simulated film: Add 1.5 ml of ammonia water to the reacted solution and stir quickly for 10 s, pour it into a mold, and place it in an oven at 80 °C for curing for 1 h.

[0128] After testing, the elongation at break of the silicone film material obtained in this example is 5.63%, and the water absorption rate is 0.77%, meeting the mechanical requirements of the film material for controlled-release fertilizer preparation.

[0129] Example 8:

[0130] Method for preparing silicone-coated controlled-release fertilizer, comprising the following steps:

[0131] The specific production process is as follows:

[0132] First step, add 15 ml of acetic acid, 12.5 g of cetyltrimethylammonium bromide, and 600 ml of deionized water to a 2 L beaker and stir on a magnetic stirrer.

[0133] Second step, weigh 150 g of methyltrimethoxysilane, 85 g of dimethyldimethoxysilane, and 15 g of tetraethoxysilane and add them to the beaker in the first step in sequence, and note that the temperature of the beaker is kept at about 20 °C.

[0134] Third step, after the solution reacts for 100 min, turn on Roots blower 1. After the air flow is buffered and balanced by buffer tank 2 and then heated by electric heater 3, it enters fluidized bed 5 and circulates for about 20 min, ensuring that the temperature in the fluidized bed is 80 °C and making the fluidized bed in a working state.

[0135] Second step, add 1 Kg of large granular urea to the fluidized bed for preheating for 2 min, and then use the compressed air provided by air compressor 4 to pass through the nozzle to pre-treat the surface of the urea particles, and the treatment time is 2 min.

[0136] Third step, add the silane prepolymer and 10 ml of alkali catalyst to storage tank 7 according to the metering ratio and stir and mix evenly. Use peristaltic pump 6 to transport it to the nozzle and atomize it onto the surface of the fertilizer particles.

[0137] Fourth step, input the reaction material into the nozzle for atomization at a speed of 10 ml / min, operate for 20 min, then stop adding the reaction material, the coating is finished, and the coated sample is taken out.

[0138] After testing, the initial dissolution rate of the controlled-release fertilizer obtained in this example is 2.7%, the differential dissolution rate is 3.36%, the water contact angle is 90°, and the release period is 30 days.

[0139] Example 9:

[0140] A method for preparing a hydrophobic-coated fertilizer containing 1H,1H,2H,2H,-perfluorodecyltrimethoxysilane, comprising the following steps:

[0141] First step, add 15 ml of acetic acid, 12.5 g of cetyltrimethylammonium bromide, and 600 ml of deionized water into a 2 L beaker and stir on a magnetic stirrer.

[0142] Second step, weigh 150 g of methyltrimethoxysilane, 85 g of dimethyldimethoxysilane, 15 g of tetraethoxysilane, and 2.5 g of 1H,1H,2H,2H,-perfluorodecyltrimethoxysilane, and add them to the beaker in the first step in sequence, noting that the temperature of the beaker is maintained at about 20 °C.

[0143] Third step, after the solution reacts for 100 min, turn on Roots blower 1. After the air flow is buffered and balanced by buffer tank 2 and then heated by electric heater 3, it enters fluidized bed 5 and circulates for about 20 min to ensure that the temperature in the fluidized bed is 80 °C, making the fluidized bed in a working state.

[0144] Second step, add 1 Kg of large granular urea to the fluidized bed for preheating for 2 min, and then use the compressed air provided by air compressor 4 to pass through the nozzle to pretreat the surface of the urea particles for 2 min.

[0145] Third step, add the silane prepolymer and 10 ml of alkali catalyst to storage tank 7 according to the metering ratio and stir and mix evenly. Use peristaltic pump 6 to transport it to the nozzle and atomize it onto the surface of the fertilizer particles.

[0146] Fourth step, input the reaction materials into the nozzle for atomization at a speed of 10 ml / min, operate for 20 min, then stop adding the reaction materials, end the coating, and take out the coated sample.

[0147] After testing, the initial dissolution rate of the controlled-release fertilizer obtained in this example is 0.9%, the differential dissolution rate is 1.84%, the water contact angle is 145°, and the release period is 65 days.

[0148] The present invention provides a preparation of an organosilicon coating material and its controlled-release fertilizer. Its film shell is prepared by hydrolysis of methyltrimethoxysilane, tetraethoxysilane, and dimethyldimethoxysilane in acid and condensation in alkali. The reaction mechanism is as follows:

[0149] Hydrolysis of silane (taking methyltrimethoxysilane as an example):

[0150]

[0151] Similarly, dimethyldimethoxysilane and tetraethoxysilane respectively produce dihydroxysilane and tetraoxysilane:

[0152]

[0153] The condensation reactions of various silanols:

[0154]

[0155] By adopting the above technical solution:

[0156] By using water as the solvent, the hydrolysis and condensation reactions of various organosilanes form a stable film shell on the surface of large particle urea at low temperature through a fluidized bed device. Using water as the solvent solves the disadvantages of high cost and pollution caused by the use of organic solvents in most traditional polymer coatings; the organosilicon material film shell is an organic-inorganic hybrid film shell with both inorganic structure and organic groups, solving the problems of poor film-forming property of traditional inorganic materials and good film-forming property of organic materials but causing environmental pollution; the film material is prepared by the sol-gel method, and its characteristic is that the pore size on the film shell material can be artificially controlled, so as to control the controlled release performance of the coated fertilizer; since the film shell contains silicon element, it can provide silicon nutrient elements for crops; the types and functions of organosilicon materials are rich and diverse, and a variety of functional composite system film layers can be formed, solving the problem of single function of coated fertilizers. This coating material is suitable for mass continuous production of coated fertilizers.

[0157] The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A silicone-coated material, characterized in that, By mass fraction, it includes the following components: 20 - 31.5 parts of organosilane; 1 - 1.6 parts of cetyltrimethylammonium bromide; 1 - 2 parts of pH regulator; 40 - 80 parts of water; The organosilane, by mass fraction, includes the following components: 10 - 20 parts of methyltrimethoxysilane; 4 - 13 parts of dimethyldimethoxysilane; 1 - 5 parts of tetraethoxysilane; 0.2 - 0.315 part of 1H,1H,2H,2H,-perfluorodecyltrimethoxysilane.

2. The organosilicon coating material according to claim 1, wherein The molar ratio of methyltrimethoxysilane, dimethyldimethoxysilane to tetraethoxysilane is 1 - 3:0.5 - 1.5:0.1 - 0.5; the mass of cetyltrimethylammonium bromide is 5% of the total amount of methyltrimethoxysilane, dimethyldimethoxysilane and tetraethoxysilane.

3. The organosilicon coating material according to claim 1, characterized in that, The mass of the water is not less than 3 times the mass of methyltrimethoxysilane.

4. The organosilicon coating material according to claim 1, wherein The overall concentration of methyltrimethoxysilane, dimethyldimethoxysilane and tetraethoxysilane is 20 - 40 wt%; the initial pH is 3 - 6.

5. The organosilicon coating material according to claim 1, characterized in that: The pH regulator is hydrochloric acid, acetic acid and ammonia water.

6. A method for preparing a controlled-release fertilizer with a silicone coating material, characterized in that, It includes the following steps: S1 Add the formulated amount of acid, the formulated amount of cetyltrimethylammonium bromide, and the formulated amount of water into a beaker and stir on a magnetic stirrer; S2 Weigh the formulated amount of methyltrimethoxysilane, the formulated amount of dimethyldimethoxysilane, the formulated amount of tetraethoxysilane, and the formulated amount of 1H,1H,2H,2H,-perfluorodecyltrimethoxysilane, and add them into the beaker in the first step in sequence, and note that the temperature of the beaker is maintained at 20 - 30 °C to obtain a silane prepolymer; S3 After the solution reacts for 90 - 110 min, turn on the Roots blower (1). After the air flow is buffered and balanced by the buffer tank (2) and then heated by the electric heater (3) and enters the fluidized bed (5) and circulates for about 15 - 20 min, ensure that the temperature in the fluidized bed is 70 - 80 °C to make the fluidized bed in a working state; S4 Add 1 - 2 Kg of large granular fertilizer into the fluidized bed for preheating for 2 - 5 min, and then use the compressed air provided by the air compressor (4) to pass through the nozzle to pretreat the surface of the particles, and the treatment time is 2 - 5 min; S5 Add the silane prepolymer obtained in step S2 into the coating liquid storage tank (7), then add 1 - 2 parts of ammonia water and stir and mix evenly, and use a peristaltic pump (6) to transport it to the nozzle to atomize it onto the surface of the fertilizer particles; S6 The reaction material is input into the nozzle for atomization at a speed of 10 - 20 ml / min, and the operation is carried out for 20 - 40 min. Then stop adding the reaction material, the coating is completed, and the coated sample is taken out.

7. The method for preparing a controlled-release fertilizer with an organosilicon coating material as claimed in claim 6, wherein The large granular fertilizer includes ammonium chloride, ammonium sulfate, monoammonium phosphate, urea, and compound fertilizer.

8. The method for preparing a controlled-release fertilizer with an organosilicon coating material as claimed in claim 6, wherein, The dosage of 1H,1H,2H,2H,-perfluorodecyltrimethoxysilane is 1% of the total mass of methyltrimethoxysilane, tetraethoxysilane and dimethyldimethoxysilane.

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