WO2023035193A1 - Slow-release coated fertilizer and preparation method therefor - Google Patents

Abstract

A slow-release coated fertilizer and a preparation method therefor, belonging to the field of composite materials. The slow-release coated fertilizer comprises a fertilizer particle and a thin film coated outside the fertilizer particle. The thin film is prepared from a silicone polymeric material, wherein the silicone polymeric material is prepared by a Diels-Alder reaction between a modified polysiloxane A and a modified polysiloxane B. The organopolysiloxane A has at least one non-aromatic conjugated diene bond in one molecule, and the organopolysiloxane B has at least one substituted olefinic bond which is subjected to the Diels-Alder reaction with the non-aromatic conjugated diene bond in one molecule. The slow-release coated fertilizer has a high coating uniformity, which is beneficial for the slow release of the fertilizer and gives a good slow-release effect; and the thin film of the slow-release coated fertilizer has a good hydrophobic property, permeability, film-forming property and reusability, so that the slow-release coated fertilizer uses a small amount of coating material, has significant advantages and has a positive effect on environmental protection.

Description

[Title of the invention established by the ISA under Rule 37.2] Slow-release coated fertilizers and processes for their preparation technical field

The application relates to a slow-release coated fertilizer and a preparation method thereof, belonging to the field of fertilizer preparation.

Background technique

With the rapid growth of the world's population and the gradual improvement of people's living standards, the demand for grain production and quality is increasing year by year. The application of fertilizers has become the most effective method to improve grain quality and production. With the rapid development of agriculture, the phenomenon of excessive application of fertilizers in agricultural production is not uncommon. The reason is that after the application of fertilizers, due to the impact of external factors such as rain erosion and light decomposition, most of the nutrients have been lost before being absorbed by crops. The rate is greatly reduced, which leads to the phenomenon of over-application of fertilizer. Excessive application of fertilizers will inhibit the growth of crops, reduce the quality of agricultural products, lead to soil structure damage and non-point source pollution. Therefore, how to improve the utilization rate of fertilizers on the premise of ensuring high and stable grain production, thereby reducing agricultural production costs, reducing non-point source pollution caused by agricultural growth and development, and realizing the sustainable development of agricultural green ecology has become the current agricultural development in my country and the world. Key questions of the research.

Silicone polymer materials are a special class of polymer materials, and their unique Si-O segments make them exhibit unique advantages in terms of thermal properties, flexibility, film-forming properties, and hydrophobicity. Previous research results show that organosilicon polymers can form a dense protective film on the surface of the substrate, which can still prevent corrosion of the substrate under the action of strong acids and alkalis, and have excellent hydrophobicity. The above research results show that organosilicon polymers Can be used as a hydrophobic coating for slow release of fertilizers. However, the Pt catalyst is often required in the preparation process of organosilicon polymers, and the cost is relatively high, which hinders the application of organosilicon polymers in the agricultural field. On the other hand, the slow-release effect of existing slow-release fertilizers is poor due to the poor performance of the coating material, which causes the problems of waste of resources and indiscriminate application of fertilizers.

Contents of the invention

In order to solve the above problems, the application provides a slow-release coated fertilizer and a preparation method thereof. The uniformity of the coating of the slow-release coated fertilizer is high, which is beneficial to the slow-release of the fertilizer, and the slow-release effect is good; the slow-release package The coating material of the outer layer of the film fertilizer has good hydrophobicity, permeability, film-forming property and reusability, so the low amount of coating material used in the slow-release coated fertilizer has a significant advantage and has a positive effect on protecting the environment; The processing cost of release coated fertilizer is low.

According to one aspect of the present application, a slow-release coated fertilizer is provided, which includes fertilizer granules and a film coated outside the fertilizer granules, and the film is made of a silicone polymer material;

Wherein, the organosilicon polymer material is prepared by the Diels-Alder reaction of the modified polysiloxane A and the modified polysiloxane B, and the organopolysiloxane A has at least one substituted olefin in one molecule. The organopolysiloxane B has at least one non-aromatic conjugated diene bond group that undergoes a Diels-Alder reaction with the substituted olefin bond group in one molecule.

The Si-O segment in organopolysiloxane makes it exhibit unique advantages in terms of thermal performance, flexibility, film-forming property, hydrophobicity, etc., and organopolysiloxane forms a dense protective film on the surface of the fertilizer. Under the action of strong acid and strong alkali, it can still prevent its corrosion to fertilizers, and has excellent hydrophobicity, and has excellent characteristics as a fertilizer coating; The coating cost of the fertilizer is reduced, and the porosity of the prepared organopolysiloxane can ensure the release of the fertilizer, and the release rate is relatively slow, which is conducive to the plant to fully absorb the fertilizer nutrients and improve the utilization rate of the fertilizer; and the organopolysiloxane Oxane can undergo Diels-Alder reaction so that repeated coating can be achieved to provide uniformity of the formed film, so as to avoid the problem of uneven fertilizer release caused by uneven coating.

Optionally, the mass ratio of the organosilicon polymer material to the fertilizer granules is 0.3%-5%. Optionally, the upper and lower limits of the mass ratio of the organosilicon polymer material to the fertilizer granules are independently selected from 0.5%, 1%, 2%, 3% or 4%. Selected from 0.5%-5%. Preferably, the mass ratio of the organosilicon polymer material to the fertilizer particles is 0.3%-3%, more preferably 1%-3%. The control of the mass ratio can not only ensure the integrity of the fertilizer coating, but also reduce the usage of coating materials, and at the same time help to control the optimal release rate of the fertilizer.

Optionally, the particle size of the fertilizer particles is 10-40 mesh. Preferably, the particle size of the fertilizer particles is 20-30 mesh. The mesh size of the fertilizer granules can make the fertilizer fully released in a suitable time. If it is too large, the nutrients cannot be fully released in a limited time, and finally the fertilizer utilization rate will be reduced; if it is too small, the fertilizer will be completely released before it reaches 28 days. Release, not up to the slow-release fertilizer standard.

Optionally, the fertilizer particles are selected from at least one of urea, NPK compound fertilizer, diammonium phosphate, medium element fertilizer, biological fertilizer and organic fertilizer.

Optionally, the substituted olefin bond group in the modified polysiloxane A may be a maleimide group, and the non-aromatic dien bond group in the organopolysiloxane B The group is a furoyl group; alternatively, the group containing a substituted olefin bond in the modified polysiloxane A can be a maleimide derivative, and the group in the organopolysiloxane B Diethylenic groups containing non-aromatic hydrocarbons are furoacetyl derivatives.

Optionally, the group containing a substituted olefin bond in the modified polysiloxane A is a maleimide group, and the group containing a non-aromatic double olefin bond in the organopolysiloxane B is furoacetyl;

The modified polysiloxane A and the modified polysiloxane B are cross-linked and polymerized to produce at least one reversible substituted cyclohexenyl group to obtain the silicone polymer material, and the structure of the reversible substituted cyclohexenyl group is as follows: Formula I shows:

Optionally, the modified polysiloxane A and the modified polysiloxane B are reversibly cross-linked and polymerized through multiple maleimide groups and furoacetyl groups, so that the obtained silicone polymer material It is a porous material and can be used as a sustained-release coating material.

Optionally, the grafting rate of the maleimide group in the modified polysiloxane A is X, and the grafting rate of the furoacetyl group in the modified polysiloxane B is Y, so The ratio of the grafting rate X to the grafting rate Y is 1:1.2-1.5.

Preferably, the ratio of the grafting rate X to the grafting rate Y is 1:1.2-1.5; more preferably, the ratio of the grafting rate X to the grafting rate Y is 1:1.5, so that the grafted horse The imide group and furoacetyl can fully react to improve the utilization rate of grafting raw materials.

Specifically, the grafting rate X is 8%-20%, the grafting rate Y is 5%-25%; preferably, the grafting rate X is 10%-20%, and the grafting rate Y is 12% -twenty four%. The values of the grafting ratio X and the grafting ratio Y can ensure the slow-release effect of the prepared organosilicon polymer material, especially the slow-release effect as a fertilizer coating.

The calculation of the grafting ratio of X and Y is carried out according to the following method: Accurately weigh about 1.5g of modified polysiloxane in a conical flask with an analytical balance, add about 20mL of tetrahydrofuran and toluene to dissolve, and then add 0.1mol/ L of hydrochloric acid solution, shake well for 5 minutes, add phenolphthalein indicator, measure the excess acid with calibrated sodium hydroxide standard solution, until the solution changes color. In addition, do a blank sample again for the hydrochloric acid solution. Calculate the amino group concentration and the grafting ratio of X and Y according to the following formula:

Amino concentration=(V ₀ -V)C _NaOH /m;

Grafting rate=(amino group concentration before reaction-amino group concentration after reaction)/amino group concentration before reaction×100%

Among them: V ₀ ——the volume of sodium hydroxide consumed for titrating the blank sample (mL);

V—the volume of sodium hydroxide consumed by the titration sample (mL);

C _NaOH - standard sodium hydroxide concentration (mol/L);

m—sample mass (g).

Optionally, the polysiloxane A and the polysiloxane B are independently selected from poly(diorganosiloxanes).

Optionally, the polysiloxane A has a structural formula as shown in Formula II:

Among them, R1, R2, R3 and R4 are independently selected from one of hydrocarbon groups, substituted hydrocarbon groups, heteroaryl groups, substituted heteroaryl groups and non-hydrocarbon substituents; m1 and n1 are respectively taken from integers>0, the formula The weight-average molecular weight of the aminated polysiloxane A of II is 2000-20000, and the grafting rate of amino groups in the aminated polysiloxane A is 3%-30%; the R ₁ , R ₂ , R At least one of ₃ and R ₄ is linked to the maleimide group of the reversibly substituted cyclohexenyl of formula I.

Optionally, the structural formulas of the polysiloxane B are shown in formula III:

Among them, R5, R6, R7 and R8 are independently selected from one of hydrocarbon groups, substituted hydrocarbon groups, heteroaryl groups, substituted heteroaryl groups and non-hydrocarbon substituents; m2 and n2 are respectively taken from integers>0, the formula The weight average molecular weight of the aminated polysiloxane B of III is 2,000 to 20,000, and the grafting rate of amino groups in the aminated polysiloxane B is 3%-30%; the R5, R6, R7 and R8 The imino group contained in is connected to the furoacetyl group of the reversibly substituted cyclohexenyl of formula I.

Preferably, the R1, R2, R3 and R4 are independently selected from an alkyl group; one of the R1, R2, R3 and R4 is connected to the nitrogen atom of the reversibly substituted cyclohexenyl of formula I; preferably , the R5, R6, R7 and R8 are independently selected from imino substituted alkyl; the imino group of one of the R5, R6, R7 and R8 and the furoacetyl of the reversibly substituted cyclohexenyl of formula I connect.

More preferably, the carbon chain parts in R1, R2, R3, R4 and R5, R6, R7 and R8 are independently selected from one of C1-C5 alkyl groups.

Most preferably, the R2 and R6 are respectively propyl and imino substituted propyl or the molecular formula shown in formula VI, and the R3, R4, R5, R7 and R8 are respectively methyl;

Wherein, m3 and n3 are respectively selected from integers not less than 1, specifically, m3 is 2, and n3 is 3.

Specifically, the preparation of aminated polysiloxane is based on aminodialkoxysilane coupling agent, dimethyldialkoxysilane and hexamethyldisiloxane hydrolysis, capping preparation, amino grafting The calculation of the rate is according to the NMR method, by calculating the ratio of the amino peak area to the Si-CH3 peak area:

Grafting rate=3*amino peak area/2*Si-CH3 peak area*100%.

Preferably, the ratio between the m1 value and the m2 value is 1:1.5, so as to ensure that the Diels-Alder reaction can proceed completely.

Optionally, the modified polysiloxane A and the modified polysiloxane B are linear polysiloxanes respectively, which increases the flexibility and film-forming properties of the obtained organosilicon polymer material.

According to another aspect of the present application, a method for preparing a self-healing silicone polymer material is provided, which includes the following steps:

Provide modified polysiloxane A, the modified polysiloxane A is polysiloxane A having at least one maleimide group substitution in one molecule;

Provide modified polysiloxane B, said modified polysiloxane B is polysiloxane B having at least one furoacetyl group substitution in one molecule;

The modified polysiloxane A and modified polysiloxane B are dissolved and then heated to cause a Diels-Alder reaction to generate the organosilicon polymer material crosslinked by at least one reversibly substituted cyclohexene.

Optionally, the preparation method of the modified polysiloxane A comprises the following steps:

Aminated polysiloxane A is provided;

The modified polysiloxane A is obtained by dissolving the aminated polysiloxane A and maleic anhydride in the organic solvent I and heating to reflux for at least 3 hours.

Optionally, the molecular weight of the aminated polysiloxane A is 2000-20000; and the grafting rate of the amino groups in the aminated polysiloxane A is 3%-30%, and the amino groups in the amino group The molar ratio of polysiloxane A to the maleic anhydride is 1:1-3. The weight-average molecular weight range of the aminated polysiloxane A is 2000-20000. Because the amino grafting rate is low, this molecular weight range can promote the free stretching of the molecular chain in a benign solvent, which is beneficial to the maleic anhydride and the side chain. The amino group reacts to avoid the incomplete reaction caused by the inability of the molecular chain to stretch freely due to too large a molecular weight. The grafting rate of amino groups in the aminated polysiloxane A is conducive to the grafting of maleimide functional groups with larger steric volumes, avoiding the steric hindrance between maleimide groups. The response is incomplete. The molar ratio of the amino group to the maleic anhydride is favorable for the sufficient reaction between the maleic anhydride and the amino group, avoiding the problem of incomplete reaction.

Specifically, the upper and lower limits of the weight average molecular weight range of the aminated polysiloxane A can be selected from 3000, 5000, 8000, 11000, 14000, 17000 or 19000, respectively. The weight average molecular weight may be 3000, 5000, 8000, 10000 or 15000.

Preferably, the grafting rate of amino groups in the aminated polysiloxane A is 3%-30%. Furthermore, the grafting rate of amino groups in the aminated polysiloxane A is 10%-15%.

Preferably, the molar ratio of the aminated polysiloxane A to the maleic anhydride in terms of amino groups is 1:1.5-2.5.

Preferably, the organic solvent I is glacial acetic acid.

Optionally, after dissolving aminated polysiloxane A and maleic anhydride in organic solvent I, the heating reaction temperature is 140-180°C, and the reflux reaction time is 4-8h, that is, the modified polysiloxane Alkane A.

Optionally, the preparation method of the modified polysiloxane B comprises the following steps:

Aminated polysiloxane B is provided;

In an inert atmosphere, after mixing the aminated polysiloxane B dissolved in the organic solvent II and the acid-binding agent, adding furoacetyl chloride dissolved in the organic solvent II, and heating under reflux for at least 0.5 hours, the described Modified Polysiloxane B.

Preferably, the molecular weight of the aminated polysiloxane B is 2000-20000;

The grafting rate of the amino group in the aminated polysiloxane B is 3%-30%, and the molar ratio of the amino group to the furoacetyl chloride is 1:1-5; the acid-binding agent and the The mass ratio of aminated polysiloxane B is 3wt%-7wt%. The weight-average molecular weight range of the aminated polysiloxane B is beneficial to the reaction between furoacetyl chloride and the amino side chain in the aminated polysiloxane, and avoids incomplete reaction. The grafting ratio of amino groups in the aminated polysiloxane B is beneficial to the dispersed distribution of amino side chains on the polysiloxane main chain, and avoids the problem of incomplete reaction caused by too concentrated dispersion. The molar ratio of the amino group to the furoyl chloride is conducive to the completeness of the reaction between the furoyl chloride and the side chain amino group, and avoids incomplete reaction. The mass ratio of the acid-binding agent to the aminated polysiloxane B is conducive to the timely adsorption of hydrogen chloride produced by the reaction of acid chlorides and amino groups, and avoids the breakage of polysiloxane chains caused by excessive acidity.

Specifically, the upper limit and the lower limit of the range of the weight average molecular weight of the aminated polysiloxane B can be selected from 3000, 5000, 8000, 11000, 14000, 17000 or 19000 respectively, the specific aminated polysiloxane B The weight average molecular weight may be 3000, 5000, 8000, 10000 or 15000.

Preferably, the grafting rate of amino groups in the aminated polysiloxane B is 3%-30%. Furthermore, the grafting rate of amino groups in the aminated polysiloxane B is 10%-15%.

Preferably, the molar ratio of the aminated polysiloxane B to the furoacetyl chloride in terms of amino groups is 1:1-1.5.

Preferably, the mass ratio of the acid-binding agent to the aminated polysiloxane B is 4wt%-6wt%.

Preferably, the acid-binding agent is at least one selected from pyridine, triethylamine, 4-dimethylaminopyridine, potassium carbonate, sodium carbonate and cesium carbonate. More preferably, the acid-binding agent is pyridines.

Preferably, the organic solvent II is at least one selected from anhydrous ether, tetrahydrofuran and dichloromethane.

Alternatively, in a nitrogen atmosphere, after mixing the aminated polysiloxane B dissolved in the organic solvent II and the acid-binding agent, add furoacetyl chloride dissolved in the organic solvent II, and heat and reflux for 1-3 hours to obtain The modified polysiloxane B was obtained.

Optionally, the modified polysiloxane A and modified polysiloxane B are dissolved in the organic solvent III and reacted at a temperature of 150°C-200°C for at least 15h, preferably 24h-48h, to ensure the reaction yield It can reach more than 95%.

The molar ratio of modified polysiloxane A based on maleimide group to modified polysiloxane B based on furoacetyl group is 1:1-4. Preferably, the molar ratio of the modified polysiloxane A based on maleimide groups to the modified polysiloxane B based on furoacetyl groups is 1:2-3.

Preferably, the organic solvent III is selected from one of dimethyl ether, xylene, benzyl alcohol, dicarboxylate and ethyl benzoate.

According to another aspect of the present application, there is provided a method for preparing the slow-release coated fertilizer described in any one of the above, which includes the following steps:

providing said fertilizer granules having a target mesh;

providing said silicone polymeric material;

Add the fertilizer granules into the drum coating machine, adjust the coating machine to rotate at an angle of 35°-45°, and preheat to control the micro-melting of the surface of the fertilizer granules;

Spray the organosilicon polymer material dissolved in the organic solvent VI onto the surface of the fertilizer granules to obtain the slow-release coated fertilizer.

In this application, by controlling the angle of the coating machine, the fertilizer particles in the coating machine are further controlled to present a continuous material curtain, so that the organosilicon polymer material can be directly sprayed on the surface of the suspended fertilizer particles and form a film before falling into the coating. On the inner wall of the clothing machine, it is more conducive to the uniformity of film formation. In addition, controlling the temperature to make the surface of the fertilizer micro-melt is conducive to better adhesion and bonding of the fertilizer surface and the organic silicon polymer material.

Optionally, the coating machine rotates at a speed of 40-80r/m. Preferably, the rotating speed of the coating machine is 50-70r/m. The control of the rotation speed can prevent the coated fertilizers from sticking to each other.

Optionally, the mass ratio of the organosilicon polymer material to the fertilizer granules is 1%-8%.

Optionally, the temperature of the preheated fertilizer granules is 80-140°C. Preferably, the temperature of the preheated fertilizer granules is 90-110°C. The fertilizer preferably applicable to the preheating temperature is urea.

The beneficial effects of this application include but are not limited to:

1. According to the slow-release coated fertilizer of the present application, the coated organosilicon polymer material used in the slow-release coated fertilizer can realize the breaking and cross-linking of cross-linked bonds at a specific temperature, and can be used as a fertilizer coating material , using the temperature reversibility of the Diels-Alder reaction, the bonding and dissociation characteristics of chemical bonds can be controlled by temperature. If the coating is uneven, the coating treatment can be repeated many times, reducing the defective rate and improving the coating quality. The yield rate is high, and the problem of poor fertilizer slow-release effect caused by uneven coating is avoided.

2. According to the slow-release coated fertilizer of the present application, although the Si-O segment of the coated organic silicon material in the slow-release coated fertilizer has extremely strong hydrophobic properties, the maleimide group and furan acetylation The reversible cross-linking of the group provides holes inside the composite material, which ensures the slow-release effect of the coated fertilizer.

3. According to the slow-release coated fertilizer of the present application, the slow-release coated fertilizer can realize industrialization and has huge economic value and industry influence; it is green and environmentally friendly, and can realize "recycling of polymer materials" and has huge potential develop potential.

4. According to the preparation method of the slow-release coated fertilizer of the present application, the film formed by the coating is uniform, the fertilizer particles and the film are well bonded, and the process can be repeated to repair the uneven coating produced, so as to avoid solving the problem caused by the coating. Non-uniformity produces waste.

5. According to the preparation method of the slow-release coated fertilizer of the present application, the coated organosilicon polymer material used in the slow-release coated fertilizer is a mixture of maleimide functionalization and furan acetylated polysiloxane. Constructed by catalyst-type Diels-Alder reaction, there is no problem of catalyst removal and residue, and the post-treatment steps are simple.

Description of drawings

The drawings described here are used to provide a further understanding of the application and constitute a part of the application. The schematic embodiments and descriptions of the application are used to explain the application and do not constitute an improper limitation to the application. In the attached picture:

Fig. 1 (A) and (B) are respectively the infrared spectrograms of maleimidated polysiloxane A1# and furan acetylated polysiloxane B1# involved in Example 1 of the present application;

Fig. 2 (A) and (B) are respectively embodiment 1 and maleimidated polysiloxane A1#, furan acetylated polysiloxane B1# GPC spectrogram;

Fig. 3 (A) is the thermogravimetric analysis figure of organosilicon polymer material 1# under nitrogen and air; (B) is the DSC spectrogram of organosilicon polymer material 1#;

Fig. 4 is the microstructure schematic diagram of the organosilicon polymer material 1# obtained in embodiment 1;

Fig. 5 is the optical performance spectrogram of the organosilicon polymer material 1# obtained in embodiment 1, (A) is the ultraviolet spectrum and (B) is the fluorescence spectrogram;

Fig. 6 (A) is the urea granule figure that embodiment 2 uses; (B) is the coated fertilizer 1# photograph behind the organosilicon polymeric material 1# coated urea granule;

Fig. 7 is the coated fertilizer 1#-3# slow-release property spectrogram that embodiment 2,4,6 makes respectively in 60d;

Fig. 8 is the self-repair diagram of the organosilicon compound fertilizer obtained in Example 2, (A) the 1# shell of the organosilicon polymer material after urea release; (B) the 2# shell of the organosilicon polymer material after the Diels-Alder reverse reaction repair occurred .

Fig. 9 is a schematic diagram of the process and structure of the preparation of the organosilicon polymer material in the embodiment.

Detailed ways

The present application is described in detail below in conjunction with the examples, but the present application is not limited to these examples.

"Hydrocarbyl" includes alkyl, alkenyl, alkynyl and aryl.

"Alkyl" means a monovalent aliphatic hydrocarbon group. An alkyl group can have any number of carbon atoms. Many alkyl groups are C1 to C30. Some alkyl groups can be C1 or larger, such as C2 or larger, C4 or larger, C6 or larger, or C8 or larger. Some alkyl groups can be C22 or less, C16 or less, C12 or less, C8 or less, or C4 or less. Unless otherwise specified, any alkyl groups may independently be linear, branched, cyclic, or combinations thereof (eg, cyclic alkyl groups may also have linear or branched components.) Exemplary Alkyl includes methyl, ethyl, propyl, isopropyl, n-butyl, tert-butyl, sec-butyl, isobutyl, 2-ethylhexyl, isooctyl, dodecyl, hexadecane base, docosyl group and so on.

"Aryl" refers to a monovalent aromatic group. Aryl groups may include only carbon and hydrogen, or may also include one or more heteroatoms, such as one or more of oxygen, nitrogen, and sulfur. Aryl groups can have an aromatic ring with three or more atoms, four or more atoms, or five or more atoms. Aryl groups can have rings with ten or fewer atoms, eight or fewer atoms, seven or fewer atoms, or six or fewer atoms. Exemplary aryl groups include phenyl, furyl, naphthyl, anthracenyl, and the like. Phenyl is a common aryl substituent.

"Amino" means a group having the formula -Nc(H)p(R')q, wherein each R' is independently an alkyl, alkenyl, alkynyl, aryl, or alkaryl group, any of which One may be optionally substituted, p+q is 2 or 3, and c represents the charge on the nitrogen atom, which is 0 or 1+. Typically, each R' is an alkyl group. When p+q is 2, c is 0; when p+q is 3, c is 1+. The amino group can be primary, secondary, tertiary or quaternary, depending on the value of q. Amino groups with q values of 0, 1, 2 and 3 are primary, secondary, tertiary and quaternary ammonia, respectively.

"Polydiorganosiloxane" refers to a polymer having the repeating unit -Si(G) _2O- , wherein each occurrence of G is independently an organic moiety. Each occurrence of G is typically independently alkyl, aryl, alkenyl or alkynyl. Alkyl and aryl are the most common, and alkyl is more common than aryl. When G is aryl, it may be any aryl group, for example any group referred to herein by the definition of "aryl". Typical aryl groups include phenyl. Typical alkyl groups include those discussed with reference to the definition of alkyl herein, and also include C1 to C22 alkyl, C1 to C16 alkyl, C1 to C12 alkyl, C1 to C8 alkyl, or C1 to C4 Alkyl groups such as methyl, ethyl, propyl, butyl (such as tert-butyl, isobutyl, n-butyl and sec-butyl), and C8 alkyl groups such as 2-ethylhexyl and isooctyl. When not specified, the end groups of polydiorganosiloxanes can vary; typical end groups include triorganosilyl groups and hydroxyl groups, as well as capping, quenching, and chain transfer groups .

Unless otherwise specified, the raw materials, reagents and fertilizers in the examples of the present application were purchased through commercial channels. Among them, the raw material aminated polysiloxane is self-made in the laboratory, using aminopropylmethyldiethoxysilane or 3-(2-aminoethyl)-aminopropylmethyldiethoxysilane and dimethyl Side aminopolysiloxane prepared by hydrolysis of diethoxysilane, prepared by hydrolysis of aminopropyldimethylethoxysilane or 3-(2-aminoethyl)-aminopropyldimethylethoxysilane become.

Analytic method is as follows in the embodiment of the application:

Use the Nicolet710 infrared instrument of Nicolet Company of the United States to conduct infrared analysis and testing;

Gel Permeation Chromatography (GPC) analysis test was carried out by using DAWN HELEOS II Gel Permeation Chromatography Instrument of Wyatt Company of the United States;

Use Mettler-Tolley TGA2 thermal analysis instrument for thermal analysis test;

Using German Zeiss company SUPRA

Model 55 scanning electron microscope for microstructure analysis and testing;

Utilize the Cary 5000 model instrument of Agilent Company to carry out the ultraviolet spectrum test;

Use the FLS-1000 model instrument of Edinburgh company to carry out the fluorescence spectrum analysis test;

Using GB/T23348-2009 Determination of Total Nitrogen Content in Compound Fertilizers-Distillation Titration Method to analyze and test the release rate of nitrogen in water; the test method is the method of soaking in water, leaching the coating with water or a certain concentration of salt solution Controlled-release fertilizers to calculate the amount of nutrients dissolved within a certain period of time. Add 4g of the fertilizer to be tested into a beaker filled with 80mL of deionized water, cover it, place it in a 30°C incubator, and take samples every 6h, taking 2.5mL each time to measure the nitrogen content in the leachate .

Referring to Figure 9, the figure shows the process of reversible reaction and thermal self-repair, and the structure diagram of the obtained organosilicon composite material, in which, 1 is the Si-O-Si segment in polysiloxane, and 2 is maleyl Imino group, 3 is furoacetyl, 4 is

The process of reacting and according to an embodiment of the present application, the preparation method of self-healing silicone polymer material comprises the following steps:

Step 1, preparation of modified polysiloxane A (maleimidated polysiloxane A): Amine-terminated polysiloxane A or Side aminated polysiloxane A and maleic anhydride were placed in a 100mL round-bottomed flask equipped with an air duct, a constant pressure low liquid funnel and a spherical condenser, heated to 140-180°C under electromagnetic stirring and refluxed to react 4- After 8 hours, remove glacial acetic acid under reduced pressure and dissolve the residue with chloroform, purify and wash with saturated sodium chloride aqueous solution several times and separate the organic phase; add anhydrous magnesium sulfate to the organic phase and dry overnight, remove the organic solvent under reduced pressure to obtain a brown transparent oil Liquid, that is, the modified polysiloxane A is obtained;

Among them, the weight average molecular weight of aminated polysiloxane A includes but not limited to 3000, 5000, 10000, 15000, the grafting ratio of amino groups in aminated polysiloxane A includes but not limited to 3%-30%. The molar ratio of maleic anhydride is 1:1-1:3;

Step 2. Preparation of modified polysiloxane B (furan acetylated polysiloxane B): Three extractions and three discharges were performed on a 50mL round bottom flask, and then nitrogen was introduced for protection. Terminal amino-modified polysiloxane B or pendant amino-modified polysiloxane B, dissolved in 20mL organic solvent II, and introduced acid-binding agent, the amount of acid-binding agent added is amino-modified polysiloxane B 3%-7% of the mass; after electromagnetic stirring for 15-30min, slowly drop the furoyl chloride dissolved in the organic solvent II into the round bottom flask, the molar ratio of amino group to furoyl chloride is 1:1-1:1.5 , and reacted for 1h-3h under reflux; vacuum distillation and purification were performed to remove the generated salt by suction filtration to obtain a light yellow oily liquid, which was to obtain modified polysiloxane B;

Among them, the weight-average molecular weight of amino-modified polysiloxane B includes but is not limited to 3000, 5000, 10000, and 15000, and the amino graft ratio of amino-modified polysiloxane B includes but is not limited to 3%-30%. Solvent II includes but not limited to anhydrous ether, tetrahydrofuran, dichloromethane; acid-binding agents include but not limited to pyridine, triethylamine, 4-dimethylaminopyridine, potassium carbonate, sodium carbonate, cesium carbonate, etc.; organic solvents The volume of furoacetyl chloride in II: the volume (v:v) ratio is 1:5-1:10;

Step 3, preparation of silicone polymer material: Dissolve modified polysiloxane A (maleimidated polysiloxane A) and modified polysiloxane B (furan acetylated polysiloxane B) in After the organic solvent III, transfer to a round bottom flask, heat to 150°C-200°C under electromagnetic stirring and react for 24h-48h; after the reaction is completed, pour it into anhydrous methanol solution to obtain a light red precipitate, remove the organic solvent by suction filtration After Ⅲ, repeatedly wash with anhydrous methanol for several times, and vacuum dry overnight to obtain the organosilicon polymer material;

Wherein, the molar ratio of maleimide group to furanacetyl group is 1:1-1:4, organic solvent III includes but not limited to dimethyl ether, xylene, benzyl alcohol, diformic acid ester, ethyl benzoate Esters etc.

According to another embodiment of the present application, the application of the self-healing organosilicon polymer material as a fertilizer coating includes the following steps:

Organosilicon polymer material as fertilizer coating process: After sieving the fertilizer with sieves of different meshes (10-40 mesh), divide the fertilizer into 50g portions;

Take a portion of fertilizer in the rotary drum coater, adjust the angle of the coater to 35°-45°, and control the speed at 40-80r/m, so that the fertilizer can form a continuous material curtain in the coater; carry out pre-treatment after 15 minutes. Heating, the temperature is controlled at about 90°C-110°C, so that the surface of the fertilizer granules is in a slightly molten state, and the organic silicon polymer material dissolved in the methylene chloride solution is sprayed. The injected organic silicon polymer material accounts for 0.5%-5% of the fertilizer mass. %, so that it forms a uniform film on the surface of fertilizer granules. The uniformity of silicone polymer material coating on the surface of fertilizer particles can be observed under ultraviolet light. Further, during the coating process, the rotation speed is adjusted to prevent mutual sticking.

Example 1 Preparation of organosilicon polymer material 1#

The reaction equations of modified polysiloxane A1# and modified polysiloxane B1# of the present embodiment are as follows respectively

The preparation method of self-healing organosilicon polymer material 1# comprises the following steps:

(1) Preparation of modified polysiloxane A1# (maleimidated polysiloxane A1#): Aminopropyl-terminated polysiloxane with a weight-average molecular weight of 5000 dispersed in 30 mL of glacial acetic acid Alkanes and maleic anhydride are placed in a 100mL round-bottomed flask equipped with an airway tube, a constant pressure low liquid funnel and a spherical condenser at a molar ratio of amino to maleic anhydride of 1:1, and heated to 140°C under electromagnetic stirring After reflux for 4 hours, the glacial acetic acid was removed under reduced pressure and the residue was dissolved in chloroform, purified and washed several times with saturated aqueous sodium chloride solution, and the organic phase was separated. After adding anhydrous magnesium sulfate to the organic phase and drying it overnight, remove the organic solvent under reduced pressure to obtain a brown transparent oily liquid, that is, the modified polysiloxane A1# (maleimidated polysiloxane A1#), infrared The test results are shown in Figure 1 (A), and the GPC spectrum of the GPC test is shown in Figure 2 (A);

(2) Modified polysiloxane B1# (furan acetylated polysiloxane B1#): the 50mL round-bottomed flask was pumped three times and vented three times, and then passed into nitrogen for protection. In order to ensure the modified polysiloxane A and The Diels-Alder reaction between the modified polysiloxane B is more complete, and the performance of the obtained film is better, and the selected aminopropyl polysiloxane is the same as that selected in A1#. Dissolve aminopropyl-terminated polysiloxane with a weight-average molecular weight of 5000 in 20 mL of anhydrous ether, add acid-binding agent pyridine, and the amount of pyridine added is 3% of the mass of aminopropyl-terminated polysiloxane; After electromagnetic stirring for 15 min, furoyl chloride dissolved in the organic solvent anhydrous ether with a volume to mass ratio (mL:g) of 10:1 was slowly dropped into the round-bottomed flask, wherein the molar ratio of amino group to furoyl chloride was 1:1, after reacting for 1 hour under reflux, remove the generated salt by suction filtration, and carry out vacuum distillation and purification to obtain a light yellow oily liquid, which is the modified polysiloxane B1#. The infrared test results are shown in Figure 1 ( B), GPC test GPC spectrogram is shown in Fig. 2 (B);

(3) Preparation of organosilicon polymer material 1#: Maleimidated polysiloxane A1# and furanacetylated polysiloxane B1# were calculated by maleimide group and furanacetyl group in a molar ratio of 1:2 dissolved in the organic solvent dimethyl ether, the volume-to-mass ratio (mL:g) between the solvent and the raw material is 20:1, and transferred to a round bottom flask, heated to 150°C under electromagnetic stirring and reacted for 24h Then pour it into anhydrous methanol solution to obtain a light red precipitate, remove the solvent by suction filtration, wash with anhydrous methanol several times, and dry in vacuo overnight to obtain organosilicon polymer material 1#.

The thermogravimetric analysis of organosilicon polymer material 1# under nitrogen and air is shown in Figure 3(A), the DSC spectrum of organosilicon polymer material 1# is shown in Figure 3(B), and the schematic diagram of the microstructure of organosilicon polymer material 1# is shown in Figure 4 . The ultraviolet spectrum of organosilicon composite material 1# is shown in Figure 5(A) and the fluorescence spectrum is shown in Figure 5(B).

The preparation of embodiment 2 coated fertilizer 1#

Use the organosilicon polymeric material 1# of embodiment 1# as the fertilizer coating process: after sieving the urea with a 10-mesh sieve, pack it with 50g as a portion; get a portion of urea in a drum coating machine, adjust The angle of the coating machine is 35°, and the speed is controlled at 40r/m, so that the urea can form a continuous material curtain in the coating machine; preheat after 15 minutes, and the temperature is controlled at about 90°C, so that the surface of the urea particles is in a slightly molten state , spray into the organosilicon polymer material 1# dissolved in dichloromethane solution, the addition amount of the organosilicon polymer material 1# is selected as 1% of the fertilizer mass, and the rotation speed is adjusted during the coating process to prevent mutual adhesion, so that the organosilicon polymerizes Material 1# forms a uniform film on the surface of urea granules to obtain coated fertilizer 1#.

Observe the uniformity of silicone polymer material wrapping on the surface of urea particles under ultraviolet light. Fig. 6(A) is a photo of urea granules; Fig. 6(B) is a photo of coated fertilizer 1#.

Example 3 Preparation of organosilicon polymer material 2#

The preparation method of self-repairing organosilicon polymer material 2# comprises the following steps:

(1) Preparation of modified polysiloxane A2# (maleimidated polysiloxane A2#): The side aminopropyl modified polysiloxane with a weight average molecular weight of 5000 dispersed in 30mL of glacial acetic acid Alkanes and maleic anhydride are placed in the 100mL round-bottomed flask that airway is housed with amino group and maleic anhydride mol ratio as 1:3, amino graft rate 15%, constant pressure low liquid funnel and spherical condenser, in After heating to 160°C under electromagnetic stirring and reflux for 6 hours, the glacial acetic acid was removed under reduced pressure and the residue was dissolved with chloroform, purified and washed several times with saturated aqueous sodium chloride solution, and the organic phase was separated. After adding anhydrous magnesium sulfate to the organic phase and drying it overnight, the organic solvent was removed under reduced pressure to obtain a brown transparent oily liquid, and the modified polysiloxane A2# (maleimidated polysiloxane A2#) was obtained;

(2) Modified polysiloxane B2# (furan acetylated polysiloxane B2#): the 50mL round-bottomed flask was pumped three times and discharged three times, and then passed through nitrogen for protection. The side aminopropyl group with a weight average molecular weight of 5000 The modified polysiloxane was dissolved in 20mL of anhydrous ether, the grafting rate of amino group was 15%, and the acid-binding agent triethylamine was added, and the amount of triethylamine added was 5% of the mass of the side aminopropyl modified polysiloxane ; After electromagnetic stirring for 20min, the furoyl chloride dissolved in the organic solvent tetrahydrofuran was slowly dropped into the round-bottomed flask with a volume to mass ratio (mL:g) of 15:1, wherein the molar ratio of amino group to furoyl chloride was 1 :3, after reacting for 2h under the reflux state, carry out vacuum distillation purification after removing the salt produced by suction filtration, obtain light yellow oily liquid, promptly make modified polysiloxane B2#;

(3) Preparation of organosilicon polymer material 2#: Maleimidated polysiloxane A2# and furanacetylated polysiloxane B2# were calculated by maleimide group and furanacetyl group in a molar ratio of 1:2.5 was dissolved in the organic solvent xylene, the volume-to-mass ratio (mL:g) between the solvent and the raw material was 25:1, and transferred into a round bottom flask, heated to 180°C under electromagnetic stirring and reacted for 36h, Then pour it into anhydrous methanol solution to obtain a light red precipitate, remove the solvent by suction filtration, wash with anhydrous methanol several times, and vacuum dry overnight to obtain organosilicon polymer material 2#.

The preparation of embodiment 4 coated fertilizer 2#

Use the organosilicon polymeric material 2# of embodiment 3# as the fertilizer coating process: after the urea is sieved with a 39-purpose sieve, it is divided into parts with 50g; get a part of urea in a drum coating machine, adjust The angle of the coating machine is 40°, and the speed is controlled at 60r/m, so that the urea can form a continuous material curtain in the coating machine; preheat after 15 minutes, and the temperature is controlled at about 100°C, so that the surface of the urea particles is in a slightly molten state , spray into the organosilicon polymer material 2# dissolved in dichloromethane solution, the addition amount of the organosilicon polymer material 2# is selected as 1.5% of the fertilizer mass, and the rotation speed is adjusted during the coating process to prevent mutual adhesion, so that the organosilicon polymerizes Material 1# forms a uniform film on the surface of urea granules.

Observe the uniformity of silicone polymer material wrapping on the surface of urea particles under ultraviolet light.

Example 5 Preparation of self-healing silicone polymer material 3#

The preparation method of the organic silicon polymer material 3# of self-healing comprises the following steps:

(1) Preparation of modified polysiloxane A3# (maleimidated polysiloxane A3#): The side aminopropyl modified polysiloxane with a weight average molecular weight of 15000 dispersed in 30mL of glacial acetic acid Alkane and maleic anhydride are placed in the 100mL round-bottomed flask of constant pressure low liquid funnel and spherical condenser with airway tube being housed in the amount of 1:2.5 with amino group and maleic anhydride mol ratio, amino grafting rate 30%. After heating to 160°C under electromagnetic stirring and reflux for 8 hours, remove glacial acetic acid under reduced pressure and dissolve the residue with chloroform, purify and wash with saturated sodium chloride aqueous solution several times, and separate the organic phase. After adding anhydrous magnesium sulfate to the organic phase and drying it overnight, the organic solvent was removed under reduced pressure to obtain a brown transparent oily liquid, and the modified polysiloxane A3# (maleimidated polysiloxane A3#) was obtained;

(2) Modified polysiloxane B3# (furan acetylated polysiloxane B3#): the 50mL round-bottomed flask was pumped three times and released three times, and then passed through nitrogen for protection. The side aminopropyl group with a weight average molecular weight of 15000 The modified polysiloxane was dissolved in 20mL of anhydrous ether, the grafting rate of the amino group was 30%, and the acid-binding agent 4-dimethylaminopyridine was added, and the amount of 4-dimethylaminopyridine added was the 5% of the quality of oxane B3#; after electromagnetic stirring for 30min, the furoyl chloride dissolved in the organic solvent methylene chloride of 30:1 was slowly dropped into the round-bottomed flask with a volume to mass ratio (mL:g), The molar ratio of amino group to furoacetyl chloride is 1:5. After reacting under reflux for 3 hours, remove the generated salt by suction filtration, and carry out distillation and purification under reduced pressure to obtain a light yellow oily liquid, which is the modified polysiloxane B3. #;

(3) Preparation of organosilicon polymer material 3#: Maleimidated polysiloxane A3# and furanacetylated polysiloxane B3# were calculated by maleimide group and furanacetyl group in molar ratio of 1:3 dissolved in the organic solvent benzyl alcohol, the volume-to-mass ratio between the solvent and the raw material (mL:g) is 30:1, and transferred to a round bottom flask, heated to 200°C under electromagnetic stirring and reacted for 48h , and then poured into anhydrous methanol solution to obtain a light red precipitate. After the solvent was removed by suction filtration, it was repeatedly washed with anhydrous methanol several times, and vacuum-dried overnight to obtain organosilicon polymer material 3#.

The preparation of embodiment 6 coated fertilizer 3#

Use the organosilicon polymer material 3# of embodiment 5# as the fertilizer coating process: after the urea is sieved with a 40-mesh sieve, 50g is used as a portion to pack respectively; get a portion of urea in a drum coating machine, adjust The angle of the coating machine is 45°, and the speed is controlled at 80r/m, so that the urea can form a continuous material curtain in the coating machine; preheat after 15 minutes, and the temperature is controlled at about 110°C, so that the surface of the urea particles is in a slightly molten state , spray into the organosilicon polymer material 3# dissolved in dichloromethane solution, the addition amount of the organosilicon polymer material 3# is selected as 2% of the fertilizer mass, and the rotation speed is adjusted during the coating process to prevent mutual adhesion, so that the organosilicon polymerizes Material 3# forms a uniform film on the surface of urea granules.

Observe the uniformity of silicone polymer material wrapping on the surface of urea particles under ultraviolet light.

Example 7 The slow-release performance test of coated fertilizer 1-3#

The slow-release properties of the coated fertilizers 1-3# prepared in Examples 2, 4, and 6 were tested respectively, and the test method was the water soaking method. The test results are shown in Figure 7. It can be seen from Figure 7 that Example 3 has a better slow-release effect than 1 and 2, and the cumulative release rate within 28 days has not exceeded 80%, which has met the requirements of slow-release fertilizers.

Test the coating fertilizer 1-3# that embodiment 2, 4, 6 makes respectively and commercially available product nutrient release period (d), 28 days cumulative nitrogen release rate, coating material repairable times contrast see table 1 .

Table 1

As can be seen from Table 1, the coated fertilizer prepared by the present application has a slow slow release rate, can maintain nutrients and can be fully absorbed by crops, has a low fertilizer loss rate, and greatly improves the fertilizer utilization rate, thereby avoiding excessive application of fertilizers. The prepared coated fertilizers 1#, 2# and 3# did not exceed 80% of the cumulative nitrogen release rate in 28 days, which has reached the requirements of GB/T 23348-2009, and the coated fertilizer 3# accumulated nitrogen in 28 days The release rate is lower than 1#, 2# and commercially available products, indicating that the slow-release effect of coated fertilizer 3# is better.

Fig. 8(A) is the shell surface of the organosilicon composite material after the nutrient release of the prepared coated fertilizer 1#. It can be seen from Fig. 8(A) that the organosilicon composite material can form a shell with holes on the surface of the fertilizer, but as the nutrients After release, the surface may collapse and create debris around it. Figure 8(B) shows the 2# shell of the organic silicon composite material repaired by the Diels-Alder reverse reaction after the conditioned treatment of the coated fertilizer 3# material. It can be seen from Figure 8(B) that the organic silicon composite material can still be on the surface of the fertilizer A dense protective layer is formed, but the number of pores on the surface becomes larger after repairing, which means that the silicone composite material designed in this application has a certain number of self-repairing times.

Example 8

According to the conditions different from the method of Example 1 and Example 2 in Table 2, coated fertilizers 4#-10# and contrast coated materials D1#-D2# were respectively tested using the test method of Example 7 The 28-day cumulative nitrogen release rate and the repairable times of the coating material are shown in Table 2.

Table 2

As can be seen from Table 2, when the weight-average molecular weight of the coated fertilizer D1# exceeds the protection scope of the present application, although the nitrogen release rate is not much different from the coated fertilizer 4#, 5#, but due to the reversible substitution cyclohexene structure The proportion is low, so that the number of repairs of the coated fertilizer is significantly reduced; the grafting rate of the compared coated fertilizer D2# exceeds the scope of protection of the application, and the proportion of the reversible substitution cyclohexene structure is improved, and the maleimide group, The increase of the cross-linking density of furoacetyl groups increases the void density in the coating material, resulting in a high cumulative nitrogen release rate in 28 days and a poor slow-release effect. On the whole, only when the molecular weight and grafting rate are within the protection range, can the obtained coated fertilizer have good slow-release effect and many repair times.

Example 9

Coated fertilizer 11#- and contrast coated material D2#- were prepared respectively according to the conditions different from the method in Example 1 and Example 2 in Table 3, and the test method of Example 7 was used to test the accumulated nitrogen in 28 days respectively Table 3 shows the release rate of the hormone and the number of times the coating material can be repaired.

table 3

It can be seen from Table 3 that in the comparison of coated fertilizer D3#, the angle of the coating machine is too high or too low will have a negative impact on the nitrogen release rate. When the coating angle of the coating machine is low, the fertilizer will appear in the coating machine. Arc motion, the angle is too small, the fertilizer will fall too fast due to insufficient centrifugal force, and it is easy to cause uneven distribution of coating materials caused by friction fitting, and the slow-release effect is not good, but when the angle is high, although the centrifugal force is greater, However, the coating effect is not much different from that of coated fertilizer 1#, but the cost is increased due to higher energy consumption; compared with coated fertilizer D4#, the speed of rotation will also have a negative impact on the slow-release effect. , the rotation speed of the material curtain in the coating machine is fast, and the curing time of the coating material on the surface of the fertilizer is short. When it collides with other fertilizer particles, the coating material is easy to fall off from the surface of the fertilizer or create gaps, resulting in poor slow-release effect. But when the rotation speed is low, although the coating material has enough solidification time on the fertilizer surface, the coating efficiency is low because the speed is too slow; compared with the coated fertilizer D5#, with the mass ratio of the organic silicon polymer material to the fertilizer particle On the one hand, it can increase the viscosity of the coating liquid, so that its adhesion on the surface of the fertilizer can be increased; Reduce the 28-day cumulative nitrogen release rate, but the European Standards Committee pointed out in the relevant regulations on slow-release fertilizers: within the specified time, the nutrient release rate of slow-release fertilizers should not be less than 75%, although the 28-day accumulation of coated fertilizer D5# The nitrogen release rate is lower than that of the examples, but the low release rate causes the fertilizer to fail to provide sufficient nutrients for the crops within the specified time and does not meet the slow-release fertilizer standard, so it cannot be put into the slow-release fertilizer market for use.

The foregoing is only an embodiment of the application, and the protection scope of the application is not limited by these specific embodiments, but is determined by the claims of the application. For those skilled in the art, various modifications and changes may occur in this application. Any modifications, equivalent replacements, improvements, etc. made within the technical ideas and principles of this application shall be included within the protection scope of this application.

Claims (17)

1. A slow-release coated fertilizer, characterized in that it includes fertilizer granules and a film coated outside the fertilizer granules, and the film is made of organic silicon polymer material;

   Wherein, the organosilicon polymer material is prepared by the Diels-Alder reaction of the modified polysiloxane A and the modified polysiloxane B, and the organopolysiloxane A has at least one substituted olefin in one molecule. The organopolysiloxane B has at least one non-aromatic conjugated diene bond group that undergoes a Diels-Alder reaction with the substituted olefin bond group in one molecule.
2. The slow-release coated fertilizer according to claim 1, characterized in that the mass ratio of the organic silicon polymer material to the fertilizer granules is 0.3%-5%.
3. The slow-release coated fertilizer according to claim 2, characterized in that the mass ratio of the organic silicon polymer material to the fertilizer granules is 1%-3%.
4. The slow-release coated fertilizer according to claim 1, characterized in that the particle size of the fertilizer particles is 10-40 mesh.
5. The slow-release coated fertilizer according to claim 4, characterized in that the particle size of the fertilizer particles is 20-30 mesh.
6. The slow-release coated fertilizer according to claim 1, wherein the fertilizer particles are selected from at least one of urea, nitrogen, phosphorus and potassium compound fertilizer, diammonium phosphate, medium element fertilizer, biological fertilizer and organic fertilizer .
7. The slow-release coated fertilizer according to any one of claims 1-6, wherein the group comprising a substituted olefin bond in the modified polysiloxane A is a maleimide group, and the The non-aromatic dienyl group in organopolysiloxane B is furoacetyl;

   The modified polysiloxane A and the modified polysiloxane B are cross-linked and polymerized to produce at least one reversible substituted cyclohexenyl group to obtain the silicone polymer material, and the structure of the reversible substituted cyclohexenyl group is as follows: Formula I shows:

   
8. The slow-release coated fertilizer according to claim 7, wherein the graft ratio X of the maleimide group in the modified polysiloxane A is the same as that in the modified polysiloxane B. The ratio between the grafting ratio Y of the furoacetyl group is 1:1.2-1.5;

   The polysiloxane A and the polysiloxane B are independently selected from poly(diorganosiloxanes).
9. The slow-release coated fertilizer according to claim 1, wherein the polysiloxane A has a structural formula as shown in Formula II:

   

   Wherein, R ₁ , R ₂ , R ₃ and R ₄ are each independently selected from one of hydrocarbon groups, substituted hydrocarbon groups, heteroaryl groups, substituted heteroaryl groups and non-hydrocarbon substituents; m1 and n1 are respectively selected from >0 is an integer, the weight average molecular weight of the aminated polysiloxane A of formula II is 2,000 to 20,000, and the grafting rate of amino groups in the aminated polysiloxane A is 3%-30%; the R ₁ , At least one of R ₂ , R ₃ and R ₄ is connected to the maleimide group of the reversibly substituted cyclohexenyl of formula I;

   The structural formulas of the polysiloxane B are shown in formula III:

   

   Among them, R5, R6, R7 and R8 are independently selected from one of hydrocarbon groups, substituted hydrocarbon groups, heteroaryl groups, substituted heteroaryl groups and non-hydrocarbon substituents; m2 and n2 are respectively taken from integers>0, the formula The weight average molecular weight of the aminated polysiloxane B of III is 2,000 to 20,000, and the grafting rate of amino groups in the aminated polysiloxane B is 3%-30%; the R5, R6, R7 and R8 At least one of them is connected to the furoacetyl group of the reversibly substituted cyclohexenyl of formula I.
10. The slow-release coated fertilizer according to claim 9, wherein said R1, R2, R3 and R4 are independently selected from alkyl groups; one of said R1, R2, R3 and R4 is the same as formula I The maleimido linkage of the reversibly substituted cyclohexenyl group.
11. The slow-release coated fertilizer according to claim 9, wherein at least one of said R5, R6, R7 and R8 is selected from imino-substituted alkyl groups, and the rest are alkyl groups; said R5, R6, R7 and The imino group contained in R8 is connected to the furoacetyl group of the reversibly substituted cyclohexenyl of formula I.
12. The slow-release coated fertilizer according to claim 9, wherein the carbon chains in R1, R2, R3, R4 and R5, R6, R7 and R8 are independently selected from C1-C5 alkanes one of the bases.
13. The slow-release coated fertilizer according to claim 9, wherein said R2 and R6 are respectively propyl and imino substituted propyl, and said R3, R4, R5, R7 and R8 are respectively methyl.
14. A preparation method of the slow-release coated fertilizer according to any one of claims 1-13, characterized in that it comprises the steps of:

    providing said fertilizer granules having a target mesh;

    providing said silicone polymeric material;

    Add the fertilizer granules into the drum coating machine, adjust the coating machine to rotate at an angle of 35°-45°, and preheat to control the micro-melting of the surface of the fertilizer granules;

    Spray the organosilicon polymer material dissolved in the organic solvent VI onto the surface of the fertilizer granules to obtain the slow-release coated fertilizer.
15. The slow-release coated fertilizer according to claim 14, wherein the speed at which the coating machine rotates is 40-80r/m;

    The mass ratio of the organosilicon polymer material to the fertilizer granules is 1%-8%.
16. The slow-release coated fertilizer according to claim 14, characterized in that the temperature of the preheated fertilizer granules is 80-140°C.
17. The slow-release coated fertilizer according to claim 16, characterized in that the temperature of the preheated fertilizer granules is 90-110°C.

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