A core-shell structure aluminum diethylphosphinate flame retardant, and a preparation method and application thereof

Abstract

This invention relates to the field of coated flame retardant materials technology, specifically to a core-shell structured aluminum diethylphosphonate flame retardant, its preparation method, and its application. The flame retardant has a core-shell structure, with the core material being aluminum diethylphosphonate and the shell material being a catalytically cured organosilazane formed by an in-situ curing reaction on the surface of the core material. Specifically, an organosilazane compound and a curing catalyst are mixed to form a precursor mixture, which is then uniformly coated onto the surface of the aluminum diethylphosphonate. An in-situ curing reaction occurs within a certain temperature range, yielding a core-shell structured aluminum diethylphosphonate flame retardant. The resulting flame retardant exhibits good surface wettability, low corrosion, high thermal stability, and high flame retardant performance, demonstrating good application performance in polymer materials.

Description

Technical Field

[0001] This invention relates to the field of coated flame retardant materials technology, specifically to a core-shell structured aluminum diethylphosphinate flame retardant, its preparation method, and its application. Background Technology

[0002] Aluminum diethylphosphonate (ADP) is a highly efficient halogen-free flame retardant with the chemical formula Al(PO2C4H10)3 and CAS number 225789-38-8. It is a white powder with a density of 1.35 g / cm³. It catalyzes the formation of a dense char layer from polymers to form carbon, while simultaneously capturing combustion free radicals. Suitable for engineering plastics such as PA and PBT, it offers high flame retardant efficiency and is environmentally friendly. Its excellent balance between flame retardant efficiency, material properties, and environmental requirements has established its irreplaceable "cornerstone" position in the field of engineering plastics, especially in high-end applications. ADP contains no controversial halogen elements such as bromine or chlorine. It produces low smoke during combustion and generates very few corrosive and toxic gases, easily meeting the most stringent global environmental regulations such as EU RoHS and REACH, making it a key contributor to the greening of electronic and electrical products.

[0003] However, ADP has some problems in practical applications, such as its low bulk density, which easily generates a lot of dust and makes it difficult to feed during granulation; ADP is also highly acidic, with a pH of approximately 4.1, which can easily corrode processing equipment and materials containing metal inserts. Therefore, modification techniques are needed to improve the performance of ADP in engineering applications.

[0004] Currently, the surface treatment methods for ADP flame retardants used in engineering plastics and thermoplastic elastomers mainly include: silane coupling agent surface treatment, such as KH-550, KH-560, A-151, etc., which have the disadvantage of being a single layer and having general temperature resistance and migration resistance; organic polymer coating, such as polydopamine (PDA) coating, PMMA / polystyrene / epoxy resin coating, etc., which have the disadvantages of high cost, complex process, and relatively low thermal stability of the organic layer; inorganic compound coating, such as silica (SiO2) sol-gel coating, magnesium aluminum hydrotalcite (LDHs) coating, metal oxide (Al2O3, TiO2, ZnO) coating, etc., which have the disadvantage of significantly affecting the mechanical properties of the flame retardant matrix material; composite / double-layer coating, such as multiple coatings of organic and inorganic materials, coatings of multiple inorganic materials, multi-layer gradient coating, etc., which have the disadvantages of complex process and high cost. Summary of the Invention

[0005] To address the technical problem of poor application performance of existing ADP (aluminum diethylphosphonate), this invention provides a core-shell structured aluminum diethylphosphonate flame retardant, its preparation method, and its application. This invention employs catalytically cured organopolysilazane to surface-coat ADP particles, resulting in good surface wettability, low corrosivity, high thermal stability, and highly efficient flame retardant properties.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] The first aspect of this invention provides a core-shell structured aluminum diethylphosphinate flame retardant, wherein the flame retardant has a core-shell structure, the core material is aluminum diethylphosphinate, and the shell material is a catalytically cured organopolysilazane formed by an in-situ curing reaction on the surface of the core material.

[0008] The catalytically cured organopolysilazane accounts for 1%-10% of the mass percentage in the flame retardant; preferably, the catalytically cured organopolysilazane accounts for 3%-6% of the mass percentage in the flame retardant.

[0009] Furthermore, the catalytically cured organopolysilazane comprises the following parts by weight of materials reacted to form: 97-99.8 parts of organosilazane compound and 0.2-3 parts of curing catalyst.

[0010] Furthermore, the molecular structure of the organosilazane compound contains both NH bonds and Si-N bonds, has or does not have Si-H bonds, and has alkyl and / or aryl substituents on the Si atom. The viscosity of the organosilazane compound is 1-5000 mPa·s.

[0011] Furthermore, the organosilazane compound is selected from one or more of alkyl- and aryl-containing silazanes, alkyl- and aryl-containing polysilazanes, alkyl-containing silazanes, alkyl-containing polysilazanes, aryl-containing silazanes, and aryl-containing polysilazanes; wherein the viscosity of the alkyl- and aryl-containing silazanes and the alkyl- and aryl-containing polysilazanes are 200-2000 mPa·s; wherein the viscosity of the alkyl-containing silazanes and the alkyl-containing polysilazanes are 1-400 mPa·s; and wherein the viscosity of the aryl-containing silazanes and the aryl-containing polysilazanes are 500-5000 mPa·s.

[0012] Furthermore, the alkyl and aryl silazane is selected from one or more of 1,3-dimethyl-1,1,3,3-tetraphenyldisilazane (CAS No. 7453-26-1), 1,1,3,3-tetramethyl-1,3-diphenyldisilazane (CAS No. 3449-26-1), 1,3-bis(4-biphenyl)-1,1,3,3-tetramethyldisilazane (CAS No. 916667-75-9), 1,3-divinyl-1,3-diphenyl-1,3-dimethyldisilazane (CAS No. 23038-10-0), and organopolysilazane IOTA 9108;

[0013] The alkyl-containing polysilazane is selected from one or more of methyl polysilazane (CAS No. 475645-84-2), poly(1,1-dimethylsilazane) (CAS No. 89535-60-4), and organopolysilazane IOTA 9150;

[0014] The alkyl-containing silazane is selected from 1,3-dioctyltetramethylsilazane (CAS No. 82356-82-9), hexamethyldisilazane (CAS No. 999-97-3), 1,3-dibutyl-1,1,3,3-tetramethylsilazane (CAS No. 82356-80-7), 1,3-diethyl-1,1,3,3-tetramethyldisilazane (CAS No. 17882-94-9), 1,3-di-n-octyltetramethyldisilazane (CAS No. 69519-51-3), hexaethyldisilazane (CAS No. 2117-18-2), tetramethyldisilazane (C... One or more of the following: AS No. 15933-59-2, octamethylcyclotetrasilazane (CAS No. 1020-84-4), hexamethylcyclotrisilazane (CAS No. 1009-93-4), 1,1,3,3-tetramethyl-1,3-divinyldisilazane (CAS No. 7691-02-3), trivinyltrimethylcyclotrisilazane (CAS No. 5505-72-6), 1,3-di-n-propyl-1,1,3,3-tetramethyldisilazane (CAS No. 14579-90-9), and heptamethyldisilazane (CAS No. 134340-00-4);

[0015] The aryl-containing silazane is selected from one or more of hexaphenylcyclotrisilazane (CAS No. 4570-25-6) and triphenylaminosilane (CAS No. 4215-80-9). All of these substances contain NH bonds, Si-N bonds, and optionally Si-H bonds.

[0016] Furthermore, the curing catalyst is selected from one or more of ethylenediamine, triethanolamine, KH-550, dibutyltin dilaurate, zinc acetate, boron trifluoride ether, and tetrabutylammonium fluoride.

[0017] Furthermore, the median particle size of the aluminum diethylphosphonate is 2-50 micrometers.

[0018] A second aspect of the present invention provides a core-shell structured aluminum diethylphosphinic acid flame retardant, suitable for preparing the aforementioned core-shell structured flame retardant, comprising the following steps:

[0019] S1. A precursor mixture is formed by mixing an organosilazane compound with a curing catalyst; the organosilazane compound contains at least 20% of the precursor mixture.

[0020] S2. The precursor mixture is uniformly coated on the surface of aluminum diethylphosphonate, and an in-situ curing reaction is carried out in the temperature range of 50-120℃ to obtain a flame retardant with a core-shell structure aluminum diethylphosphonate.

[0021] Furthermore, S2 specifically involves spraying the precursor mixture onto the surface of aluminum diethylphosphinate under continuous stirring at 400-1000 rpm, allowing it to undergo in-situ curing at 60-110°C, and continuing the stirring reaction for 30-120 minutes. The core mechanism of in-situ curing reaction to form catalytically cured organosilazane is that the curing catalyst activates the active groups in the organosilazane compound molecule, such as Si-H, NH, and Si-N bonds, reducing the activation energy of dehydrogenation crosslinking or hydrolytic crosslinking reactions. For example, when an amine catalyst is added, the amine group (-NH2) can undergo an addition reaction with the Si-H bond to form an intermediate transition state on the surface of the core material, thereby promoting the formation of Si-N crosslinking bonds and reducing the curing temperature to room temperature to 150°C. Some curing catalysts undergo trace hydrolysis during the curing reaction (with the participation of moisture in the air): the Si-N bond reacts with H2O to generate Si-OH, and then crosslinking is assisted on the surface of the core material through dehydration condensation between Si-OH (Si-OH + HO-Si≡ → ​​Si-O-Si≡ + H2O).

[0022] The third aspect of this invention provides the application of the above-described core-shell structured aluminum diethylphosphinate flame retardant or the flame retardant prepared by the above methods in polymer materials.

[0023] Furthermore, the amount of the core-shell structured aluminum diethylphosphinic acid flame retardant added to the polymer material is in the range of 5%-20%; preferably, the amount of the flame retardant added to the polymer material is 10%-18%; the polymer material includes plastics, rubber, fibers, adhesives, coatings, etc.

[0024] Beneficial technical effects: This invention uses Si-N Organosilazane compounds with active groups on the main chain are used as precursor materials for preparing ADP-coated core-shell flame retardants. Under the action of a curing catalyst, these precursor materials can lower the activation energy of the crosslinking reaction, triggering chemical bonding between molecular chains without high temperatures. They can then be in-situ cured at relatively low temperatures to form a continuous three-dimensional network film shell on the ADP core layer surface. The film-forming properties after low-temperature in-situ curing are good, forming a continuous layer at low temperatures. The coating adhesion on the ADP surface is strong, and the shell layer is not easily detached during preparation or subsequent applications, effectively preventing ADP precipitation. Furthermore, the shell layer (coating layer) formed on the ADP surface has high thermal stability, with a heat resistance temperature of approximately 400℃, and good water and solvent resistance. In addition, the presence of Si and N elements in the organosilazane compounds helps to further improve the flame retardant performance of the core-shell structure flame retardant. The original organic groups (methyl, phenyl) of the organosilazane compounds, after being incorporated into the ADP surface, contribute to increased compatibility between the core-shell structure flame retardant and the polymer matrix material.

[0025] Compared with untreated ADP flame retardants, the core-shell structure of this invention has the following advantages:

[0026] Firstly, it has good surface wettability, which can effectively reduce dust during use and facilitate material feeding during extrusion granulation.

[0027] Secondly, it produces low corrosiveness. The pH value of core-shell structured ADP is between 4.4 and 5, while the pH value of untreated ADP is 4.1. The coating treatment reduces the corrosiveness of ADP to processing equipment and products with metal inserts.

[0028] Third, it has high flame retardant efficiency. The core-shell structure of ADP has Si-N bonds and Si-O-Si bonds, which can produce a synergistic flame retardant effect with ADP.

[0029] Fourth, it has high thermal stability. The core-shell structure ADP formed by in-situ crosslinking and curing organosilazane compounds on the surface of ADP has good high temperature resistance of its shell material, which can effectively improve the thermal stability of ADP. The temperature of untreated ADP when it loses 2% of its weight is 350-357℃, while the temperature of the core-shell structure ADP of this invention when it loses 2% of its weight is 365-372℃. Attached Figure Description

[0030] Figure 1 The images show SEM images of the core-shell structure ADP of Embodiment 1 of the present invention and the unprocessed ADP of Comparative Example 1. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Unless otherwise specifically stated, the numerical values ​​set forth in these embodiments do not limit the scope of the invention. Techniques and methods known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques and methods should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that values ​​expressed, for example, as "within the range of ab" or "between the range of ab," do not include the endpoint values ​​a and b; values ​​expressed as "for ab," "is ab," or "ab" include the endpoint values ​​a and b.

[0033] Experimental methods not specified in the following examples are generally performed according to national standards; if there is no corresponding national standard, they are performed according to general standard requirements or general methods.

[0034] Example 1

[0035] A core-shell structured aluminum diethylphosphinate flame retardant, wherein the flame retardant has a core-shell structure, the core material is aluminum diethylphosphinate (ADP), and the shell material is a catalytically cured organopolysilazane formed by an in-situ curing reaction on the surface of the core material; wherein the catalytically cured organopolysilazane accounts for 4% of the mass percentage of the flame retardant.

[0036] The catalytically cured organopolysilazane comprises the following materials: 98.7 kg of poly(1,1-dimethylsilazane) (CAS: 89535-60-4, viscosity: >50 mPa·s, 25℃) and 1.3 kg of triethanolamine as a curing catalyst; wherein the median particle size of ADP is 20 micrometers.

[0037] The preparation method of the flame retardant in this case includes the following steps:

[0038] S1. According to the above ratio, 98.7 kg of poly(1,1-dimethylsilazane) and 1.3 kg of triethanolamine are poured into a mixer and mixed at medium speed. The mixing temperature is room temperature and the mixing time is 12 min. After mixing evenly, the precursor mixture liquid is discharged.

[0039] S2. Add 96 kg of ADP powder to a mixer. Under continuous stirring at 600 rpm, take 4 kg of the precursor mixture liquid and spray it onto the surface of the ADP powder in the form of a spray. Heat to 90°C and allow in-situ curing reaction to occur for 50 min under continuous stirring. The resulting material is a core-shell structure aluminum diethylphosphinate flame retardant, abbreviated as core-shell structure ADP.

[0040] Example 2

[0041] A core-shell structured aluminum diethylphosphinate flame retardant, wherein the flame retardant has a core-shell structure, the core material is aluminum diethylphosphinate (ADP), and the shell material is a catalytically cured organopolysilazane formed by an in-situ curing reaction on the surface of the core material; wherein the catalytically cured organopolysilazane accounts for 5% of the mass percentage of the flame retardant.

[0042] The catalytically cured organopolysilazane comprises the following materials reacted to form: 98.7 kg of 1,3-diethyl-1,1,3,3-tetramethyldisilazane (CAS: 17882-94-9, viscosity 1.0~1.5 mPa·s) and 1.3 kg of triethanolamine as a curing catalyst; wherein the median particle size of ADP is 20 micrometers.

[0043] The preparation method of the flame retardant in this case includes the following steps:

[0044] S1. According to the above ratio, 98.7 kg of 1,3-diethyl-1,1,3,3-tetramethyldisilazane and 1.3 kg of triethanolamine are poured into a mixer and mixed at medium speed. The mixing temperature is room temperature and the mixing time is 10 min. After mixing evenly, the precursor mixture liquid is discharged.

[0045] S2. Add 95 kg of ADP powder to a mixer. Under continuous stirring at 800 rpm, take 5 kg of the precursor mixture liquid and spray it onto the surface of the ADP powder in the form of a spray. Heat to 80°C and allow in-situ curing reaction to occur for 60 min under continuous stirring. The resulting material is a core-shell structure aluminum diethylphosphinate flame retardant, abbreviated as core-shell structure ADP.

[0046] Example 3

[0047] The core-shell structured aluminum diethylphosphinic acid flame retardant in this case and its preparation process are the same as in Example 1, except that ethylenediamine is used as the curing catalyst.

[0048] Example 4

[0049] The core-shell structured aluminum diethylphosphinic acid flame retardant in this case and its preparation process are the same as in Example 2, except that ethylenediamine is used as the curing catalyst.

[0050] Example 5

[0051] A core-shell structured aluminum diethylphosphinate flame retardant, wherein the flame retardant has a core-shell structure, the core material is aluminum diethylphosphinate (ADP), and the shell material is a catalytically cured organopolysilazane formed by an in-situ curing reaction on the surface of the core material; wherein the catalytically cured organopolysilazane accounts for 6% of the mass percentage of the flame retardant.

[0052] The catalytically cured organopolysilazane comprises 98.7 kg of methylphenyl organopolysilazane (IOTA 9108, viscosity 10-30 mPa·s) and 1.3 kg of triethanolamine as a curing catalyst; wherein the median particle size of ADP is 20 micrometers.

[0053] The preparation method of the flame retardant in this case includes the following steps:

[0054] S1. According to the above ratio, 98.7 kg of methylphenyl organopolysilazane and 1.3 kg of triethanolamine are poured into a mixer and mixed at medium speed. The mixing temperature is room temperature and the mixing time is 15 min. After uniform mixing, the precursor mixture liquid is discharged.

[0055] S2. Add 94 kg of ADP powder to a mixer. Under continuous stirring at 1000 rpm, take 6 kg of the precursor mixture liquid and spray it onto the surface of the ADP powder in the form of a spray. Heat to 70°C and allow in-situ curing reaction to occur for 120 min under continuous stirring. The resulting material is a core-shell structure aluminum diethylphosphinate flame retardant, abbreviated as core-shell structure ADP.

[0056] Example 6

[0057] The core-shell structured aluminum diethylphosphinic acid flame retardant in this case and its preparation process are the same as in Example 5, except that ethylenediamine is used as the curing catalyst.

[0058] Comparative Example 1

[0059] This case involves untreated ADP powder.

[0060] Comparative Example 2

[0061] The core-shell structured aluminum diethylphosphonate flame retardant and its preparation process in this case are the same as in Example 1, except that no curing catalyst is added. Organopolysilazane cannot be cured, preventing the formation of a continuous cured film on the surface of the aluminum diethylphosphonate flame retardant.

[0062] Comparative Example 3

[0063] ADP was surface-treated using KH550 silane coupling agent. KH550 was mixed with deionized water and ethanol at a mass ratio of 1:1:10 and stirred to fully hydrolyze the coupling agent to generate active silanol. The pH of the system was adjusted to 9-10 to obtain a hydrolysate, which was then sprayed onto the surface of ADP (the weight of ADP and hydrolysate and subsequent operations were performed according to S2 of Example 1).

[0064] Test Example 1

[0065] The performance of the materials in the above cases was tested, and the results are shown in Table 1.

[0066] Table 1. Material properties of the examples and comparative examples

[0067]

[0068] As shown in Table 1, the pH value of the core-shell structured ADP of this invention is more than 7% higher than that of untreated ADP, indicating that the core-shell structured ADP of this invention has weaker acidity, which helps to reduce its corrosiveness to equipment and products containing metal inserts in applications. The thermogravimetric temperature of the core-shell structured ADP of this invention is more than 2% higher than that of untreated ADP, indicating that the material of this invention has high heat resistance, which is beneficial to its engineering applications. The carbonization rate of the core-shell structured ADP of this invention is 1.5%-5% higher than that of untreated ADP, indicating that the material of this invention has better flame retardant properties.

[0069] Application examples

[0070] The materials from the above embodiments and comparative examples were applied to prepare halogen-free flame-retardant glass fiber reinforced PA66 composite materials. The preparation process is as follows:

[0071] The mixture consists of 54.7 parts by weight of PA66, 30 parts by weight of continuous glass fiber (untwisted roving fiber diameter 14μm, linear density 1500tcx), 12.5 parts by weight of main flame retardant, 1 part by weight of auxiliary flame retardant, and 2.8 parts by weight of other additives.

[0072] The main flame retardant used was the material from Examples 1-6 and Comparative Examples 1-3, respectively;

[0073] The auxiliary flame retardant used is melamine polyphosphate (MPP) flame retardant;

[0074] Other additives include antioxidant S9228, antioxidant 1098, and dispersant PETS.

[0075] Weigh the above materials according to the specified ratio and mix them in a high-speed mixer for 6-8 minutes at a mixing temperature of 40-80℃ and a stirring speed of 700-900 rpm. After uniform mixing, granulate the mixture using a twin-screw extruder. The extrusion temperature distribution in the twin-screw extruder is as follows: T1=245℃, T2=250℃, T3=260℃, T4=260℃, T5=250℃, T6=250℃, T7=25℃, T8=260℃, T9=260℃, T... 机头 The performance of the granulated flame-retardant composite material was tested at 255℃. The results are shown in Table 2 below.

[0076] Table 2 Properties of Flame-Retardant Composite Materials

[0077]

[0078] Table 2 shows that the flame-retardant composite material prepared by using the core-shell structure ADP material of the present invention as the main flame retardant in PA66 has significantly better mechanical and flame-retardant properties than the comparative case.

[0079] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A core-shell structured aluminum diethylphosphinate flame retardant, characterized in that, The flame retardant has a core-shell structure, with the core material being aluminum diethylphosphinate and the shell material being a catalytically cured organopolysilazane formed by an in-situ curing reaction on the surface of the core material. The mass percentage of the catalytically cured organopolysilazane in the flame retardant is 1%-10%.

2. The core-shell structured aluminum diethylphosphinate flame retardant according to claim 1, characterized in that, The catalytically cured organopolysilazane comprises the following parts by weight of materials reacted to form: 97-99.8 parts of organosilazane compound and 0.2-3 parts of curing catalyst.

3. The core-shell structured aluminum diethylphosphinate flame retardant according to claim 2, characterized in that, The molecular structure of the organosilazane compound contains both NH bonds and Si-N bonds, has or does not have Si-H bonds, and has alkyl and / or aryl substituents on the Si atom. The viscosity of the organosilazane compound is 1-5000 mPa·s.

4. The core-shell structured aluminum diethylphosphinate flame retardant according to claim 3, characterized in that, The organosilazane compound is selected from one or more of alkyl- and aryl-containing silazanes, alkyl- and aryl-containing polysilazanes, alkyl-containing silazanes, alkyl-containing polysilazanes, aryl-containing silazanes, and aryl-containing polysilazanes; wherein the viscosity of the alkyl- and aryl-containing silazanes and the alkyl- and aryl-containing polysilazanes are 200-2000 mPa·s; wherein the viscosity of the alkyl-containing silazanes and the alkyl-containing polysilazanes are 1-400 mPa·s; wherein the viscosity of the aryl-containing silazanes and the aryl-containing polysilazanes are 500-5000 mPa·s.

5. The core-shell structured aluminum diethylphosphonic acid flame retardant according to claim 4, characterized in that, The alkyl and aryl-containing silazane is selected from one or more of 1,3-dimethyl-1,1,3,3-tetraphenyldisilazane, 1,1,3,3-tetramethyl-1,3-diphenyldisilazane, 1,3-bis(4-biphenyl)-1,1,3,3-tetramethyldisilazane, 1,3-divinyl-1,3-diphenyl-1,3-dimethyldisilazane, and organopolysilazane IOTA 9108; The alkyl-containing polysilazane is selected from one or more of methyl polysilazane, poly(1,1-dimethylsilazane), and organopolysilazane IOTA 9150; The alkyl-containing silazane is selected from one or more of 1,3-dioctyltetramethylsilazane, hexamethyldisilazane, 1,3-dibutyl-1,1,3,3-tetramethylsilazane, 1,3-diethyl-1,1,3,3-tetramethyldisilazane, 1,3-di-n-octyltetramethyldisilazane, hexaethyldisilazane, tetramethyldisilazane, octamethylcyclotetrasilazane, hexamethylcyclotrisilazane, 1,1,3,3-tetramethyl-1,3-divinyldisilazane, trivinyltrimethylcyclotrisilazane, 1,3-di-n-propyl-1,1,3,3-tetramethyldisilazane, and heptamethyldisilazane. The aryl-containing silazane is selected from one or more of hexaphenylcyclotrisilazane and triphenylaminosilane.

6. A core-shell structured aluminum diethylphosphonic acid flame retardant according to any one of claims 1-5, characterized in that, The curing catalyst is selected from one or more of ethylenediamine, triethanolamine, KH-550, dibutyltin dilaurate, zinc acetate, boron trifluoride ether, and tetrabutylammonium fluoride.

7. A core-shell structured aluminum diethylphosphonic acid flame retardant according to any one of claims 1-5, characterized in that, The median particle size of the aluminum diethylphosphonate is 2-50 micrometers.

8. A method for preparing a core-shell structured aluminum diethylphosphonate flame retardant, applicable to the preparation of the flame retardant according to any one of claims 1-7, characterized in that, Includes the following steps: S1. A precursor mixture is formed by mixing an organosilazane compound with a curing catalyst; the organosilazane compound contains at least 20% of the precursor mixture. S2. The precursor mixture is uniformly coated on the surface of aluminum diethylphosphonate, and an in-situ curing reaction is carried out in the temperature range of 50-120℃ to obtain a flame retardant with a core-shell structure aluminum diethylphosphonate.

9. The method for preparing a core-shell structured aluminum diethylphosphonate flame retardant according to claim 8, characterized in that, S2 specifically involves spraying the precursor mixture onto the surface of aluminum diethylphosphinate under continuous stirring at 400-1000 rpm, allowing it to undergo in-situ curing at 60-110°C, and continuing the stirring reaction for 30-120 minutes.

10. The application of a core-shell structured aluminum diethylphosphinic acid flame retardant in polymer materials, characterized in that, The flame retardant according to any one of claims 1-7 or the flame retardant prepared by the preparation method according to any one of claims 8-9 is added to the polymer material, wherein the amount of the flame retardant added to the polymer material is in the range of 5%-20%.

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