Method for preparing network cross-linked polymer coating layer flame retardant with phosphorus and nitrogen components on surface by utilizing waste wind power blade and application of network cross-linked polymer coating layer flame retardant

Abstract

The invention provides a method for preparing a netlike cross-linked polymer coating layer flame retardant with phosphorus and nitrogen components on the surface by utilizing a waste wind power blade and application of the netlike cross-linked polymer coating layer flame retardant. The method comprises the following steps: grinding and crushing a waste wind power blade material in a millstone-shaped solid-phase mechanochemical reactor, and then carrying out surface modification on wind power blade powder by dopamine; and then carrying out substitution reaction with cyclophosphazene and a polyfunctional amino compound to prepare the network cross-linked polymer coating layer flame retardant with phosphorus and nitrogen components on the surface. Wind power blade powder with special performance is obtained based on an industrial millstone-shaped solid-phase mechanochemical reactor for grinding a waste wind power blade material, the high-efficiency flame retardant is prepared after modification, and a composite material formed by compounding the flame retardant and a thermosetting polymer has good mechanical performance and flame retardant performance; and a high-value application scene is expanded for recycling of the waste wind power blade.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-value reuse of waste / retired wind turbine blade materials and flame retardants, and specifically relates to a method for preparing a flame retardant having a network cross-linked polymer coating layer with phosphorus and nitrogen components on the surface using waste wind turbine blades and its application, and especially relates to using an industrial grinding disc-shaped solid phase force chemical reactor disclosed in Chinese invention patent CN114534660B to process the above-mentioned waste wind turbine blade materials. Background Art

[0002] With the gradual depletion of fossil energy, the global demand for renewable energy has increased dramatically. Among them, wind energy, as a clean and renewable energy, occupies an important position in the global energy composition. Generally, the design service life of wind power generation systems is 20 to 25 years. Therefore, with the expiration of the service life of the equipment installed earlier and the replacement of equipment, a wave of wind power generation system retirement is coming. Along with it is a large amount of wind power blade waste composed of glass fiber / carbon fiber and epoxy. The three-dimensional cross-linked network of the waste epoxy resin makes it difficult to reshape and dissolve, which leads to major challenges related to the disposal of composite waste. Current estimates show that about 2 million tons of waste wind power blades will be generated each year, and it is expected that by 2050, 43 million tons of wind power blades will be discarded worldwide, which will cause serious environmental problems. At present, the main methods for large-scale disposal of waste wind power blades are still focused on incineration and landfilling, which not only seriously pollute the environment and waste precious resources, but also conflict with the principle of carbon neutrality. Therefore, it is urgent to develop innovative recycling models for wind power blades that are environmentally compatible and promote resource reuse. In order to meet these challenges, several new recycling methods have been developed in recent years to address the challenges faced by the recycling of thermosetting composites. These methods include mechanical recycling (e.g., grinding and crushing), chemical recycling (e.g., solvent decomposition), and thermal treatment (e.g., pyrolysis and supercritical fluid method). However, these methods all have inevitable limitations. For example, the pyrolysis method has very high requirements for energy consumption, cost, and equipment; the chemical recycling method also has great challenges in the separation of products. Therefore, from the perspective of environment and resource utilization, it is still a challenge to achieve green, efficient, and value-added recycling of epoxy thermosetting composites.

[0003] It is worth noting that among these recycling methods, mechanical processing recycling is considered to be an efficient and large-scale application method, but this method of recycling will inevitably cause the breakage of glass fibers in waste wind turbine blades and reduce the aspect ratio. Therefore, waste wind turbine blades recycled by mechanical processing are usually only used as low-value-added fillers, such as building fillers, concrete fillers, and polymer fillers.

[0004] In order to provide a new approach for the recycling and utilization of waste wind turbine blades, the inventor's prior patent application "Glass fiber reinforced plastic recycled products using waste wind turbine blades as raw materials and their preparation methods" (CN118063854A) provided a method for preparing highly compatible and reactive fillers using waste wind turbine blades. The method involves grinding and pulverizing waste wind turbine blade products in a disc-shaped solid-phase force chemical reactor after pretreatment to obtain ultra-fine powder of wind turbine blades, then mixing the ultra-fine powder of wind turbine blades with an activator and co-grinding to obtain highly compatible and reactive fillers, and then using the highly compatible and reactive fillers as partial raw materials to prepare glass fiber reinforced plastic recycled products.

[0005] However, in the above patent application, although a new basic approach for the recycling and utilization of waste wind turbine blades was provided, the highly compatible and reactive fillers prepared therein successfully achieved the application of being added to resin-based binders as partial raw materials, that is, they possessed basic enhancing functionality, and a new reuse approach for waste wind turbine blades was successfully pointed out. However, in terms of endowing high value to the reuse of waste wind turbine blades, it is still difficult to reasonably match the large number of waste wind turbine blades to be recycled every year. On this basis, it is necessary to form multi-channel medium- and high-value recycling technical approaches for waste wind turbine blades in order to recycle and reuse them in a more diversified manner. Summary of the Invention

[0006] The present invention aims to provide a new reuse approach for waste wind turbine blades, and provides a method for preparing a flame retardant with a phosphorus- and nitrogen-component network cross-linked polymer coating layer on the surface using waste wind turbine blades and its application. Based on the wind turbine blade powder with special properties obtained by grinding waste wind turbine blade materials in an industrial disc-shaped solid-phase force chemical reactor, a high-efficiency flame retardant is prepared after modification. The composite material formed by compounding the flame retardant and a thermosetting polymer has good mechanical properties and flame retardant properties, expanding high-value application scenarios for the reuse of waste wind turbine blades.

[0007] To achieve the above object, the present invention is implemented by a technical solution composed of the following technical measures.

[0008] On the one hand, the present invention provides a method for preparing a flame retardant with a phosphorus- and nitrogen-component network cross-linked polymer coating layer on the surface using waste wind turbine blades, mainly including the following steps:

[0009] (1) After the waste wind turbine blade materials are pretreated including washing, they are processed and pulverized into wind turbine blade fragments with an average particle size not higher than 3 cm.

[0010] (2) Add the wind turbine blade scraps obtained in step (1) to a disk-shaped solid-phase force chemical reactor for grinding and pulverization. After the grinding is completed, collect the wind turbine blade powder. Among them, the process parameters of the disk-shaped solid-phase force chemical reactor are: the grinding pressure is 4-6 MPa, the temperature of the disk surface of the grinding disk is controlled at 20-30 °C by introducing circulating cooling liquid, the number of grinding times is at least 1 time, and the rotational speed of the grinding disk is 30-60 revolutions per minute;

[0011] (3) Prepare amino-functionalized modified wind turbine blade powder by surface modification of the wind turbine blade powder obtained in step (2) with dopamine.

[0012] (4) By mass, dissolve 20-50 parts of a polyfunctional amino compound in an organic solvent to prepare a polyfunctional amino compound solution.

[0013] Add 8-12 parts of the amino-functionalized modified wind turbine blade powder obtained in step (3), 16-20 parts of cyclophosphazene to the organic solvent and add an acid-binding agent, and stir and react at a temperature of 60-80 °C for 20-30 minutes. After the time is up, dropwise add the polyfunctional amino compound solution and keep stirring at 60-80 °C. After the dropping is completed, continue to stir and react at a temperature of 60-80 °C for 5-10 hours. After the time is up, prepare a flame retardant with a phosphorus and nitrogen component network cross-linked polymer coating layer on the surface through filtration, washing and drying.

[0014] The polyfunctional amino compound includes any one of 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,4-diaminobenzenesulfonic acid, 2,4-diaminobenzaldehyde, 2,3-diaminobenzamide, 4-fluoro-1,3-diaminobenzene.

[0015] In this article, the pretreatment described in step (1) includes washing, which mainly removes the surface impurities of the waste wind turbine blade material. If necessary, the part that is not the wind turbine blade material also needs to be removed. Those skilled in the art can perform specific treatments according to the actual situation of the waste wind turbine blade products that need to be recycled and utilized, according to the existing technology.

[0016] In this article, the wind turbine blade scraps processed and pulverized to an average particle size not higher than 3 cm in step (1) are sized to facilitate their placement in the disk-shaped solid-phase force chemical reactor for grinding. The processing and pulverization method can adopt a conventional pulverization method, such as processing through existing conventional pulverization equipment such as a jaw crusher, a planetary ball mill, a cryogenic ball mill, etc.

[0017] Among them, the disk-shaped solid-phase force chemical reactor described in step (2) is the industrial disk-shaped solid-phase force chemical reactor disclosed in Chinese invention patent CN114534660B.

[0018] It should be noted that this industrial grinding disk-shaped solid-phase force chemical reactor is an industrial device finally improved based on the principle of the force chemical reactor disclosed in the prior authorized patent ZL95111258.9. It is significantly different from the structure of the laboratory prototype machine when ZL95111258.9 was applied for. A new grinding disk structure was designed for industrial high-efficiency force chemical milling treatment. The grinding disk was improved from being vertically arranged in the past to being horizontally arranged, and the size of the grinding disk was greatly increased. Based on the horizontally arranged and large-sized grinding disk, relevant fixed grinding disk components and a hydraulic lifting system were innovatively designed, greatly increasing its three-dimensional shear force, thus having the efficiency of industrial batch production.

[0019] Generally, the number of grinding times is at least 1 time. When the number of grinding times is 2 times or more, the actual process operation is to grind the material through the grinding disk-shaped solid-phase force chemical reactor, collect the product at the discharge end, and then place it again in the grinding disk-shaped solid-phase force chemical reactor for grinding treatment. The above process is regarded as 2 times of grinding times.

[0020] In this article, the temperature of the grinding disk surface in step (2) is controlled at 20 - 30 °C by introducing a circulating cooling liquid, and the cooling liquid is water, ethylene glycol or glycerol.

[0021] In this article, the wind power blade powder in step (3) is prepared into an amino-functionalized modified wind power blade powder by dopamine surface modification, which is a conventional dopamine surface modification process method in the technical field. That is, surface modification is carried out based on the oxidative self-polymerization reaction of dopamine. The specific modification conditions and operations can all refer to the conventional dopamine surface modification method or the records in the existing technical literature. For example, the method of adding dopamine hydrochloride through the oxidative self-polymerization reaction in the prior art.

[0022] To better illustrate the present invention and provide a technical solution for reference, the wind power blade powder in step (3) is prepared into an amino-functionalized modified wind power blade powder by dopamine surface modification. By mass fraction, 2 - 4 parts of dopamine hydrochloride are dissolved in Tris buffer solution, and then 8 - 12 parts of wind power blade powder are added as a reaction mixture, and stirred and reacted at a temperature of 20 - 30 °C for at least 24 hours. After the time is up, the amino-functionalized modified wind power blade powder is prepared through filtration, washing and drying.

[0023] Based on this technical solution, further preferably, 2 - 4 parts of dopamine hydrochloride are dissolved in a mixed solution of Tris buffer solution and ethanol, and the volume ratio of Tris buffer solution to ethanol is 7:3, the concentration of Tris buffer solution is 0.1 mol / L, and the mass concentration of dopamine hydrochloride is 2 - 4 g / L.

[0024] Based on this technical solution, in order to shorten the reaction time, further preferably, 1 to 3 parts of copper sulfate and 1 to 3 parts of hydrogen peroxide are further added to the reaction mixture, and the reaction is stirred at a temperature of 20 to 30 °C for at least 4 hours.

[0025] In this article, the acid-binding agent described in step (4) is a conventional acid-binding agent selection commonly used in the substitution reaction in the technical field. Those skilled in the technical field can select a suitable acid-binding agent according to actual needs. For example, one of triethylamine, pyridine, and 4-dimethylaminopyridine can be selected, and the specific addition amount can refer to the conventional dosage of the selected acid-binding agent.

[0026] In order to better illustrate the present invention and provide a technical solution for reference, when the acid-binding agent is triethylamine, its addition amount is 80 to 120 parts.

[0027] In one of the technical solutions, the cyclophosphazene described in step (4) includes any one of hexachlorocyclotriphosphazene, trichlorocyclotriphosphazene, hexafluorocyclotriphosphazene, ethoxy(pentafluoro)cyclotriphosphazene, and pentafluoro(phenoxy)cyclotriphosphazene.

[0028] In this article, the organic solvent described in step (4) is a conventional solvent selection used in the reaction of cyclophosphazene and amino compounds. For example, one or more of acetonitrile, n-hexane, cyclohexane, dichloromethane, n-heptane, n-octane, acetone, benzene, and toluene can be selected.

[0029] In one of the technical solutions, 20 to 50 parts of the polyfunctional amino compound are dissolved in an organic solvent in step (4) to prepare a polyfunctional amino compound solution, and the mass concentration of the polyfunctional amino compound is 40 to 100 g / L.

[0030] In one of the technical solutions, 8 to 12 parts of the amino-functionalized modified wind turbine blade powder obtained in step (3) and 16 to 20 parts of cyclophosphazene are added to an organic solvent and an acid-binding agent is added, wherein the mass concentration of the amino-functionalized modified wind turbine blade powder in the organic solvent is 5 to 8 g / L.

[0031] The main inventive point of the present invention lies in the fact that the wind turbine blade powder obtained by grinding with a disk-shaped solid-phase force chemical reactor has been proven in previous published patents and papers to be able to maximize the aspect ratio of glass fibers therein while enabling the best mechanical treatment process for restoring the reaction activity and processability of the powder. Based on the wind turbine blade powder with special properties obtained by the disk-shaped solid-phase force chemical reactor, after dopamine surface modification, in a reaction system with polyfunctional amino compounds and cyclophosphazene, through a multi-step synergistic reaction in which substitution reaction and cross-linking reaction occur simultaneously, a phosphorus- and nitrogen-component network cross-linked polymer coating layer is formed on the powder surface, thereby constructing a high-value flame retardant with high mechanical properties and flame retardancy based on the recycling of waste wind turbine blades.

[0032] It should be emphasized that through experiments, it has been confirmed that in order to form a phosphorus- and nitrogen-component network cross-linked polymer coating layer on the surface of the wind turbine blade powder, that is, to form a coating layer similar to a "sweater" microscopically, the following essential conditions are required: 1. The wind turbine blade powder needs to be surface-modified with dopamine; 2. The addition amount of the polyfunctional amino compound and the control of the reaction rate by dropping the polyfunctional amino compound solution; 3. Reacting under specific temperature conditions to further control the reaction rate. Through comparative experimental characterization, if the addition amount of the polyfunctional amino compound is too large, the addition rate is too fast, or it is significantly lower or higher than the reaction temperature conditions described in the present invention, it will cause the coating layer to be unable to completely coat the powder or unable to form a network cross-linked polymer coating layer.

[0033] Based on the above technical solution, the method for preparing a flame retardant with a phosphorus- and nitrogen-component network cross-linked polymer coating layer on the surface using waste wind turbine blades, the finally prepared flame retardant with a phosphorus- and nitrogen-component network cross-linked polymer coating layer on the surface can be directly used as a flame retardant in an epoxy resin system, for example, to prepare an epoxy flame retardant composite material.

[0034] It should be noted that when using the flame retardant with a phosphorus- and nitrogen-component network cross-linked polymer coating layer on the surface provided by the present invention in an epoxy resin system, the addition amount and process conditions of this flame retardant can be used with reference to conventional epoxy resin flame retardants without special conditions.

[0035] To better illustrate the present invention, and to provide an epoxy flame retardant composite material using a flame retardant with a phosphorus- and nitrogen-component network cross-linked polymer coating layer on the surface, the raw materials of this epoxy flame retardant composite material by mass include:

[0036] 10 - 40 parts of a flame retardant with a phosphorus- and nitrogen-component network cross-linked polymer coating layer on the surface,

[0037] 100 parts of epoxy resin,

[0038] 10 - 30 parts of a curing agent.

[0039] For the above epoxy flame-retardant composite material, its preparation method can refer to the preparation method of conventional epoxy composite materials. For example, first, a flame retardant with a phosphorus and nitrogen component network cross-linked polymer coating layer on the surface is mixed evenly with epoxy resin, and then a curing agent is added and cured under the specified conditions of the curing agent.

[0040] Among them, the epoxy resin is the epoxy resin raw material conventionally used in the prior art, such as bisphenol A epoxy resin, bisphenol F epoxy resin, phenolic epoxy resin, glycidylamine type epoxy resin, brominated epoxy resin, etc.

[0041] Among them, the curing agent is the curing agent conventionally used in the epoxy resin system, such as amine curing agents (such as diethylenetriamine, isophorone diamine, m-phenylenediamine, 2,2'-diaminodiphenyl disulfide, 4,4'-diaminodiphenylmethane, polyamide), acid anhydride curing agents (such as methyltetrahydrophthalic anhydride, maleic anhydride, dodecenyl succinic anhydride, phthalic anhydride, pyromellitic dianhydride), etc.

[0042] In this article, the filtration, washing, and drying all follow the conventional principles in chemical engineering processes, and those skilled in the art can perform specific operations according to common knowledge.

[0043] The present invention has the following beneficial effects:

[0044] (1) The present invention provides a method for preparing a flame retardant with a phosphorus and nitrogen component network cross-linked polymer coating layer on the surface from waste wind turbine blades and its application. First, based on prior research results, the waste wind turbine blades are ground into powder by a disk-shaped solid-phase force chemical reactor, and then the powder of the wind turbine blades modified by polydopamine reacts with cyclophosphazene and polyfunctional amino compounds through substitution reaction to generate a flame retardant rich in nitrogen and phosphorus elements. After testing, it shows excellent flame retardant performance. The epoxy flame-retardant composite material prepared by using it has good mechanical properties and flame retardant performance, which expands high-value application scenarios for the reuse of waste wind turbine blade materials.

[0045] (2) The present invention provides a method for preparing a flame retardant with a phosphorus and nitrogen component network cross-linked polymer coating layer on the surface from waste wind turbine blades and its application. The prepared flame retardant has a unique "sweater-like" coating layer on the surface, which not only improves the interfacial compatibility between the flame retardant and the polymer matrix, but also endows the recycled material with specific flame retardant functional applications. It not only challenges the traditional concept that mechanically recycled wind turbine blades can only be used as low-value fillers, but also demonstrates the great potential for the value-added recycling and reuse of waste wind turbine blades to enhance polymers. Description of the Drawings

[0046] Figure 1SEM image of the wind turbine blade powder collected in step (2) of Example 2 of the present invention.

[0047] Figure 2 Schematic diagrams of the reaction processes in steps (3) and (4) of Example 2 of the present invention, physical digital photos of the intermediate products and the final product, FTIR spectra, XPS spectra, high-resolution carbon / phosphorus spectra, SEM images, and TG curves. Among them, Figure (a) is the schematic diagram of the reaction processes in steps (3) and (4) of Example 2; Figure (b) is the physical digital photos of the intermediate product wind turbine blade powder (WGE) obtained in step (2) of Example 2, the intermediate product amino-functionalized modified wind turbine blade powder (WGE@PDA) obtained in step (3), and the final product flame retardant (Fr@WGE@PDA) with a network cross-linked polymer coating layer containing phosphorus and nitrogen components on the surface obtained in step (4); Figure (c) is the SEM and elemental mapping diagrams of the flame retardant with a network cross-linked polymer coating layer containing phosphorus and nitrogen components on the surface obtained in Example 2; Figure (d) is the infrared spectra of the above intermediate products and the final product in Example 2; Figure (e) is the XPS comparison spectra of the above intermediate products and the final product in Example 2; Figure (f) is the high-resolution carbon spectra of the intermediate product wind turbine blade powder (upper) and the final product (lower) obtained in Example 2; Figure (g) is the high-resolution phosphorus spectrum of the final product in Example 2; Figure (h) is the content comparison diagram of C, N, O, and P elements of the above intermediate products and the final product in Example 2; Figure (i) is the TG curve comparison diagram of the above intermediate products and the final product in Example 2.

[0048] Figure 3 TG curve comparison diagram of the samples prepared in Examples 1-4 and Comparative Example 1 of the present invention.

[0049] Figure 4 SEM image of the comparative sample prepared in Comparative Example 2 of the present invention. It can be clearly seen that a network cross-linked polymer coating layer can hardly be formed on the surface.

[0050] Figure 5 SEM image of the comparative sample prepared in Comparative Example 3 of the present invention. It can be clearly seen that a complete network cross-linked polymer coating layer cannot be formed on the surface.

[0051] Figure 6 Summary diagram of the combustion states of the materials prepared in Application Example 1 and Application Comparative Examples 1-3 of the present invention in the vertical combustion test. Among them, EP refers to the epoxy material prepared in Application Comparative Example 1, EP / WGE refers to the epoxy composite material prepared in Application Comparative Example 2, EP / WGE@PDA refers to the epoxy composite material prepared in Application Comparative Example 3, and EP / Fr@WGE@PDA refers to the epoxy flame retardant composite material prepared in Application Example 1. Detailed implementation manners

[0052] To further understand the present invention, the preferred embodiments of the present invention will be described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the invention. Those skilled in the art can draw on the content of this article and appropriately modify the process parameters to achieve. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The methods and applications of the present invention have been described through preferred embodiments, and those skilled in the art can obviously make changes or appropriate modifications and combinations to the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention. Although it is believed that those of ordinary skill in the art are fully aware of the following terms, the following definitions are still presented to help illustrate the subject matter disclosed by the present invention.

[0053] In one aspect, the present invention provides a method for preparing a flame retardant with a phosphorus and nitrogen component network cross-linked polymer coating layer on the surface by using waste wind power blades, which mainly includes the following steps:

[0054] (1) After the waste wind power blade material is pretreated including washing, it is processed and crushed into wind power blade fragments with an average particle size not higher than 3 cm.

[0055] (2) The wind power blade fragments obtained in step (1) are added to a disk-shaped solid-phase force chemical reactor for grinding and crushing. After the grinding is completed, wind power blade powder is collected. Among them, the process parameters of the disk-shaped solid-phase force chemical reactor are: the grinding pressure is 4 - 6 MPa, the temperature of the disk surface of the grinding disk is controlled at 20 - 30 °C by introducing circulating cooling liquid, the number of grinding times is at least 1 time, and the rotation speed of the grinding disk is 30 - 60 revolutions per minute;

[0056] (3) The wind power blade powder obtained in step (2) is surface-modified with dopamine to prepare amino-functionalized modified wind power blade powder.

[0057] (4) By mass, 20 - 50 parts of a polyfunctional amino compound are dissolved in an organic solvent to prepare a polyfunctional amino compound solution.

[0058] 8 - 12 parts of the amino-functionalized modified wind power blade powder obtained in step (3) and 16 - 20 parts of cyclophosphazene are added to the organic solvent and an acid-binding agent is added. The mixture is stirred and reacted at a temperature of 60 - 80 °C for 20 - 30 minutes. After the time is up, the polyfunctional amino compound solution is added dropwise and stirring is maintained at 60 - 80 °C. After the addition is completed, the mixture is continuously stirred and reacted at a temperature of 60 - 80 °C for 5 - 10 hours. After the time is up, a flame retardant with a phosphorus and nitrogen component network cross-linked polymer coating layer on the surface is prepared through filtration, washing and drying;

[0059] The polyfunctional amino compound includes any one of 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,4-diaminobenzenesulfonic acid, 2,4-diaminobenzaldehyde, 2,3-diaminobenzamide, and 4-fluoro-1,3-diaminobenzene.

[0060] In this article, the pretreatment described in step (1) includes cleaning, which mainly removes impurities on the surface of waste wind turbine blade materials. If necessary, parts that are not wind turbine blade materials also need to be removed. Those skilled in the art can perform specific treatments according to the actual situation of the waste wind turbine blade products to be recycled and utilized, based on existing technologies.

[0061] In this article, the wind turbine blade fragments obtained by processing and crushing in step (1) to a uniform particle size not higher than 3 cm are sized to facilitate their placement in a disk-shaped solid-phase force chemical reactor for grinding. The processing and crushing method can adopt conventional crushing methods. In one implementation, for example, it can be processed by existing conventional crushing equipment such as jaw crushers, planetary ball mills, and cryogenic ball mills.

[0062] Among them, the disk-shaped solid-phase force chemical reactor described in step (2) is the industrial disk-shaped solid-phase force chemical reactor disclosed in Chinese invention patent CN114534660B.

[0063] It should be noted that this industrial disk-shaped solid-phase force chemical reactor is an industrial equipment finally improved based on the principle of the force chemical reactor disclosed in the prior authorized patent ZL95111258.9. It is significantly different from the structure of the laboratory prototype machine when ZL95111258.9 was applied. A new disk structure was designed for industrial high-efficiency force chemical grinding treatment. The disk was improved from being vertically arranged in the past to being horizontally arranged, and the disk size was significantly increased. Based on the horizontally arranged and large-sized disk, relevant fixed disk components and a hydraulic lifting system were innovatively designed, greatly improving its three-dimensional shear force, and thus having the efficiency of industrial batch production.

[0064] Generally, the number of grinding times is at least 1 time. When the number of grinding times is 2 times or more, the actual operation of the process is to collect the product at the discharge end after grinding the material in the disk-shaped solid-phase force chemical reactor and then place it again in the disk-shaped solid-phase force chemical reactor for grinding treatment. The above process is regarded as 2 times of grinding times.

[0065] In this article, the temperature of the disk surface in step (2) is controlled at 20 - 30 °C by introducing circulating cooling liquid. In one implementation, the cooling liquid is water, ethylene glycol, or glycerol.

[0066] In this text, the wind power blade powder described in step (3) is prepared into an amino-functionalized modified wind power blade powder by dopamine surface modification, which is a conventional dopamine surface modification process in this technical field, that is, surface modification based on the oxidative self-polymerization reaction of dopamine. The specific modification conditions and operations can all refer to the conventional dopamine surface modification method or the records in the existing technical literature. For example, in the existing technology, the method of adding dopamine hydrochloride through the oxidative self-polymerization reaction is used.

[0067] To better illustrate the present invention and provide a reference implementation method, the wind power blade powder described in step (3) is prepared into an amino-functionalized modified wind power blade powder by dopamine surface modification. By mass fraction, 2-4 parts of dopamine hydrochloride are dissolved in Tris buffer solution, and then 8-12 parts of wind power blade powder are added as the reaction mixture, and the mixture is stirred and reacted at a temperature of 20-30 °C for at least 24 hours. After the time is up, the amino-functionalized modified wind power blade powder is prepared through filtration, washing and drying.

[0068] Based on this implementation method, further preferably, 2-4 parts of dopamine hydrochloride are dissolved in a mixed solution of Tris buffer solution and ethanol, and the volume ratio of Tris buffer solution to ethanol is 7:3, the concentration of Tris buffer solution is 0.1 mol / L, and the mass concentration of dopamine hydrochloride is 2-4 g / L.

[0069] Based on this implementation method, in order to shorten the reaction time, further preferably, 1-3 parts of copper sulfate and 1-3 parts of hydrogen peroxide are added to the reaction mixture, and the mixture is stirred and reacted at a temperature of 20-30 °C for at least 4 hours.

[0070] In this text, the acid-binding agent described in step (4) is a conventional acid-binding agent selection commonly used for substitution reactions in this technical field. Those skilled in the art of this technical field can select a suitable acid-binding agent according to actual needs. In one implementation method, for example, any one of triethylamine, pyridine, and 4-dimethylaminopyridine is selected, and the specific addition amount can refer to the conventional dosage of the selected acid-binding agent.

[0071] To better illustrate the present invention and provide a reference implementation method, when the acid-binding agent is triethylamine, its addition amount is 80-120 parts.

[0072] In one implementation method, the cyclophosphazene described in step (4) is selected from any one of hexachlorocyclotriphosphazene, trichlorocyclotriphosphazene, hexafluorocyclotriphosphazene, ethoxy(pentafluoro)cyclotriphosphazene, and pentafluoro(phenoxy)cyclotriphosphazene.

[0073] In this article, the organic solvent described in step (4) is a conventional solvent selection used in the reaction of cyclophosphazene and amino compounds. In one embodiment, for example, any one or more of acetonitrile, n-hexane, cyclohexane, dichloromethane, n-heptane, n-octane, acetone, benzene, and toluene are selected.

[0074] In one embodiment, in step (4), 20 to 50 parts of a polyfunctional amino compound are dissolved in an organic solvent to prepare a polyfunctional amino compound solution, and the mass concentration of the polyfunctional amino compound is 40 to 100 g / L.

[0075] In one embodiment, in step (4), 8 to 12 parts of the amino-functionalized modified wind turbine blade powder obtained in step (3) and 16 to 20 parts of cyclophosphazene are added to an organic solvent and an acid-binding agent is added, wherein the mass concentration of the amino-functionalized modified wind turbine blade powder in the organic solvent is 5 to 8 g / L.

[0076] The main inventive point of the present invention lies in that the wind turbine blade powder obtained by milling with a disk-shaped solid-phase force chemical reactor has been proven in previous published patents and papers to be able to maximize the aspect ratio of glass fibers therein while restoring the reaction activity and workability of the powder through the best mechanical treatment process. Based on the wind turbine blade powder with special properties obtained by the disk-shaped solid-phase force chemical reactor, after dopamine surface modification, in the reaction system with polyfunctional amino compounds and cyclophosphazene, through a multi-step synergistic reaction in which substitution reaction and cross-linking reaction occur simultaneously, a phosphorus and nitrogen component network cross-linked polymer coating layer is formed on the surface of the powder, thereby constructing a high-value flame retardant with high mechanical properties and flame retardant properties based on the recycling of waste wind turbine blades.

[0077] It should be emphasized that through experiments, it is confirmed that in order to form a phosphorus and nitrogen component network cross-linked polymer coating layer on the surface of the wind turbine blade powder, that is, to form a coating layer similar to a "sweater" microscopically, the following essential conditions are required: 1. The wind turbine blade powder needs to be surface-modified with dopamine; 2. The addition amount of the polyfunctional amino compound, and the reaction rate is controlled by dropwise addition of the polyfunctional amino compound solution; 3. The reaction is carried out under specific temperature conditions to further control the reaction rate. Through comparative experimental characterization, if the addition amount of the polyfunctional amino compound is too large, the addition rate is too fast, significantly lower or higher than the reaction temperature conditions described in the present invention, it will cause the coating layer to be unable to completely coat the powder or unable to form a network cross-linked polymer coating layer.

[0078] Based on the above technical solution, the method for preparing a flame retardant with a phosphorus and nitrogen component network cross-linked polymer coating layer on the surface using waste wind turbine blades, and the finally prepared flame retardant with a phosphorus and nitrogen component network cross-linked polymer coating layer on the surface can be directly used as a flame retardant in an epoxy resin system, for example, to prepare an epoxy flame retardant composite material.

[0079] It should be noted that when the flame retardant with a phosphorus and nitrogen component network cross-linked polymer coating layer on the surface provided by the present invention is applied to an epoxy resin system, the addition amount and process conditions of this flame retardant can be used with reference to conventional epoxy resin flame retardants without special conditions.

[0080] To better illustrate the present invention, an epoxy flame retardant composite material using a flame retardant with a phosphorus and nitrogen component network cross-linked polymer coating layer on the surface is provided. The raw materials of this epoxy flame retardant composite material by mass include:

[0081] 10 - 40 parts of a flame retardant with a phosphorus and nitrogen component network cross-linked polymer coating layer on the surface,

[0082] 100 parts of epoxy resin,

[0083] 10 - 30 parts of a curing agent.

[0084] For the above-mentioned epoxy flame retardant composite material, its preparation method can be referred to the preparation method of conventional epoxy composite materials. For example, first, uniformly mix the flame retardant with a phosphorus and nitrogen component network cross-linked polymer coating layer on the surface with the epoxy resin, and then add the curing agent and cure it under the specified conditions of the curing agent.

[0085] Among them, the epoxy resin is a conventional epoxy resin raw material used in the prior art. In one embodiment, for example, bisphenol A epoxy resin, bisphenol F epoxy resin, phenolic epoxy resin, glycidylamine type epoxy resin, brominated epoxy resin, etc.

[0086] Among them, the curing agent is a conventional curing agent used in an epoxy resin system. In one embodiment, for example, amine curing agents (such as diethylenetriamine, isophorone diamine, m-phenylenediamine, 2,2'-diaminodiphenyl disulfide, 4,4'-diaminodiphenylmethane, polyamide), anhydride curing agents (such as methyltetrahydrophthalic anhydride, maleic anhydride, dodecenyl succinic anhydride, phthalic anhydride, pyromellitic dianhydride), etc.

[0087] In this article, the filtration, washing, and drying all follow the conventional principles in chemical engineering, and those skilled in the art can perform specific operations according to common knowledge.

[0088] The present application will be further explained in detail with reference to the embodiments below. However, those skilled in the art should understand that these embodiments are provided for illustrative purposes only and are not intended to limit the present application.

[0089] Embodiment

[0090] The implementation scheme of the present application will be described in detail below in combination with the embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. For those conditions not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase. The present application should not be construed as being limited by the specific embodiments described.

[0091] 1. Raw materials

[0092] Waste wind turbine blades, provided by Tianjin Longjin Energy Saving Technology Co., Ltd.;

[0093] Epoxy resin (EP-128), Chengdu Kemite Technology Co., Ltd.;

[0094] Hexachlorocyclotriphosphazene (HCCP), triethylamine (TEA), 4,4'-diaminodiphenylmethane (DDM), dopamine hydrochloride, copper sulfate pentahydrate, Tris buffer solution, Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0095] 30% hydrogen peroxide, deionized water, acetonitrile, ethanol, Chengdu Kelong Reagent Factory.

[0096] 2. Preparation method

[0097] (1) After the waste wind turbine blade material is pretreated including washing, it is processed and crushed into wind turbine blade fragments with an average particle size not higher than 3 cm;

[0098] (2) The wind turbine blade fragments obtained in step (1) are added to a disk-shaped solid-phase force chemical reactor for grinding and crushing. After the grinding is completed, the wind turbine blade powder is collected and denoted as WGE. Among them, the process parameters of the disk-shaped solid-phase force chemical reactor are: the grinding pressure is 5 MPa, the temperature of the disk surface of the grinding disk is controlled at 20 - 30 °C by introducing circulating cooling liquid, the number of grinding times is 3 times, and the rotation speed of the grinding disk is 50 revolutions per minute;

[0099] (3) Dissolve 0.2 g of dopamine hydrochloride, 0.125 g of anhydrous copper sulfate pentahydrate, and 0.15 mL of hydrogen peroxide in a 100 mL mixed solution of Tris buffer (0.1 mol / L) and ethanol, and mix well. The volume ratio of Tris buffer to ethanol is 7:3. Then add 1 g of wind turbine blade powder as the reaction mixture, and stir and react at 30 °C for 4 hours. After the time is up, filter the precipitate under vacuum, wash it three times with ethanol and deionized water respectively, and dry it in an oven at 60 °C to prepare amino-functionalized modified wind turbine blade powder, denoted as WGE@PDA;

[0100] (4) Dissolve 2 - 5 g of 4,4'-diaminodiphenylmethane in 50 mL of acetonitrile to prepare a multi-functional amino compound solution;

[0101] Add 1 g of amino-functionalized modified wind turbine blade powder and 1.75 g of hexachlorocyclotriphosphazene to 150 mL of acetonitrile and add 15 mL of triethylamine. Stir and react at 70 °C for 30 minutes. After the time is up, add the multi-functional amino compound solution dropwise while maintaining 70 °C and stirring. After adding dropwise in about 30 minutes, continue to stir and react at 70 °C for 7 hours. After the time is up, filter the product under vacuum, wash it three times with ethanol and deionized water respectively, and dry it in an oven at 60 °C to prepare a flame retardant with a phosphorus and nitrogen component network cross-linked polymer coating layer on the surface.

[0102] 3. Test methods

[0103] For convenient testing, referring to the standards GB / T 2408 - 2008 (vertical burning test), GB / T 2406 - 93 (limiting oxygen index test), and ISO 5660 (cone calorimeter test), prepare epoxy flame-retardant composites on a polytetrafluoroethylene mold with a specific shape by the casting method, and cure them at 80 °C and 120 °C for 2 hours respectively to obtain samples for cone calorimeter test, limiting oxygen index test, and UL-94 test. Among them, the size of the sample for vertical burning is 125×13×3 mm 3 ; the size of the sample for limiting oxygen index test is 100×6×3.2 mm 3 ; the size of the sample for cone calorimeter test is 100×100×4 mm 3 .

[0104] Fourier transform infrared spectroscopy (FTIR) test

[0105] Use a Nicolet iS50 Fourier transform infrared spectrometer from Thermo Fisher Scientific Company in the United States to perform transmission mode spectral analysis on the samples. Among them, the spectral scanning range of the spectrometer is 4000 - 400 cm -1, with a resolution of 4 cm -1 , and the number of scans is 32 times. The test was carried out by co-milling and pressing with KBr in transmission mode.

[0106] X-ray photoelectron spectroscopy (XPS) test

[0107] The AXIS Ultra DLD type X-ray photoelectron spectrometer of Kratos Analytical Instruments Company in the UK was used to analyze the element types and compositions in the samples. It was carried out at room temperature using a monochromatic Al Kα X-ray source (40 kV, 40 mA). All binding energies were calibrated with the 284.8 eV of the C1 s characteristic peak as the reference. All samples were dried in a vacuum oven at 65 °C for 24 hours before testing. And the energy spectrum data and spectra of elements such as C, N, O, and P were recorded.

[0108] Scanning electron microscopy (SEM) analysis

[0109] The Inspect F type scanning electron microscope of FEI Company in the United States was used to observe the surface morphologies of all samples. Test conditions: acceleration voltage 20 kV, and the samples need to be sputter-coated with gold before testing. The elemental maps were obtained by the energy dispersive X-ray spectroscopy (EDS) elemental composition analyzer installed on the scanning electron microscope.

[0110] Thermogravimetric (TGA) test

[0111] The Q50 type thermogravimetric analyzer of TA Instruments Company in the United States was used to test the change of the sample mass with temperature in N 2 atmosphere. Heating rate: 10 °C / min; temperature range: 40 - 700 °C.

[0112] Horizontal and vertical burning tester

[0113] Model HK-581, Zhuhai Huake Testing Company

[0114] Limiting oxygen index test

[0115] Model JF-3, Nanjing Jiangning Analytical Instrument Company Cone calorimeter test

[0116] Cone calorimeter

[0117] Model FTT0476 cone calorimeter, FTT Company in the UK.

[0118] Example 1

[0119] Example 1 was prepared according to the steps of the above "2. Preparation method". In step (4), 2 g of 4,4'-diaminodiphenylmethane was dissolved in 50 mL of acetonitrile, and finally a flame retardant with a phosphorus and nitrogen component network cross-linked polymer coating layer on the surface was prepared as the sample.

[0120] Example 2

[0121] Example 2 is prepared according to the steps of the above-mentioned "2. Preparation method". In step (4), 3 g of 4,4'-diaminodiphenylmethane is dissolved in 50 mL of acetonitrile, and finally a flame retardant with a phosphorus and nitrogen component network cross-linked polymer coating layer on the surface is prepared as a sample, denoted as Fr@WGE@PDA.

[0122] The sample is tested according to the above-mentioned "3. Test method", as shown in the appendix Figures 1-2 as follows.

[0123] Example 3

[0124] Example 3 is prepared according to the steps of the above-mentioned "2. Preparation method". In step (4), 4 g of 4,4'-diaminodiphenylmethane is dissolved in 50 mL of acetonitrile, and finally a flame retardant with a phosphorus and nitrogen component network cross-linked polymer coating layer on the surface is prepared as a sample.

[0125] Example 4

[0126] Example 4 is prepared according to the steps of the above-mentioned "2. Preparation method". In step (4), 5 g of 4,4'-diaminodiphenylmethane is dissolved in 50 mL of acetonitrile, and finally a flame retardant with a phosphorus and nitrogen component network cross-linked polymer coating layer on the surface is prepared as a sample.

[0127] Comparative Example 1

[0128] Comparative Example 1 refers to the steps of the above-mentioned "2. Preparation method", but in step (4), 1 g of 4,4'-diaminodiphenylmethane is dissolved in 50 mL of acetonitrile, and finally the prepared flame retardant is used as a comparative sample.

[0129] The samples obtained in Examples 1 to 4 and Comparative Example 1 are tested, as shown in Figure 3 the figure. When the addition amount of 4,4'-diaminodiphenylmethane is too low, the flame retardancy of the flame retardant will be significantly deteriorated.

[0130] Comparative Example 2

[0131] Comparative Example 2 refers to the steps of the above-mentioned "2. Preparation method". In step (4), 3 g of 4,4'-diaminodiphenylmethane is dissolved in 50 mL of acetonitrile, but in step (4), the reaction temperature is 50 °C, and finally the prepared flame retardant is used as a comparative sample.

[0132] As Figure 4 shown in the figure, when the reaction temperature in step (4) is too low, a network cross-linked polymer coating layer can hardly be formed on the surface.

[0133] Comparative Example 3

[0134] Comparative Example 3 refers to the above-mentioned "2. Preparation method". In step (4), 3 g of 4,4'-diaminodiphenylmethane was dissolved in 50 mL of acetonitrile, but the reaction temperature in step (4) was 100 °C, and the finally prepared flame retardant was used as a comparative sample.

[0135] As Figure 5 shown, when the reaction temperature in step (4) is too high, a network cross-linked polymer coating layer cannot be completely formed on the surface.

[0136] Comparative Example 4

[0137] Comparative Example 4 refers to the above-mentioned "2. Preparation method" steps, but in step (4), 8 g of 4,4'-diaminodiphenylmethane was dissolved in 50 mL of acetonitrile, and the finally prepared flame retardant was used as a comparative sample.

[0138] After testing, when the addition amount of 4,4'-diaminodiphenylmethane is too high, its characterization is the same as that of Comparative Example 3 Figure 5 , and a network cross-linked polymer coating layer cannot be completely formed on the surface of the amino-functionalized modified wind turbine blade powder.

[0139] Comparative Example 5

[0140] Comparative Example 5 refers to the above-mentioned "2. Preparation method" steps. In step (4), 3 g of 4,4'-diaminodiphenylmethane was dissolved in 50 mL of acetonitrile, but in step (4), the polyfunctional amino compound solution was directly added for blending and stirring instead of dropping, and the finally prepared flame retardant was used as a comparative sample.

[0141] After testing, when the acetonitrile solution of 4,4'-diaminodiphenylmethane is directly added for blending, its characterization is the same as that of Comparative Example 3 Figure 5 , and a network cross-linked polymer coating layer cannot be completely formed on the surface of the amino-functionalized modified wind turbine blade powder.

[0142] Application Example 1

[0143] Using the epoxy flame-retardant composite material with a flame retardant having a network cross-linked polymer coating layer containing phosphorus and nitrogen components prepared in Example 2, the raw materials of the epoxy flame-retardant composite material include, by mass:

[0144] Flame retardant with a network cross-linked polymer coating layer containing phosphorus and nitrogen components on the surface: 20 parts,

[0145] Epoxy resin (EP-128): 100 parts,

[0146] 4,4'-Diaminodiphenylmethane: 20 parts.

[0147] The preparation method of the epoxy flame-retardant composite material is to first blend and stir the epoxy resin and the flame retardant evenly at 80°C, then add the curing agent and stir at 80°C for 15 minutes to make the curing agent disperse evenly, and finally cure according to the above "3. Test method".

[0148] Application Comparative Example 1

[0149] Based on Application Example 1, but without using the flame retardant with a phosphorus and nitrogen component network cross-linked polymer coating layer on the surface, that is, the raw materials only include epoxy resin (EP-128) and 4,4'-diaminodiphenylmethane, and an epoxy material is prepared for comparison.

[0150] Application Comparative Example 2

[0151] Based on Application Example 1, but using the intermediate product wind turbine blade powder obtained in step (2) of Example 2 to replace the flame retardant, that is, the raw materials are wind turbine blade powder, epoxy resin (EP-128) and 4,4'-diaminodiphenylmethane, and an epoxy composite material is prepared for comparison.

[0152] Application Comparative Example 3

[0153] Based on Application Example 1, but using the intermediate product amino-functionalized modified wind turbine blade powder obtained in step (3) of Example 2 to replace the flame retardant, that is, the raw materials are amino-functionalized modified wind turbine blade powder, epoxy resin (EP-128) and 4,4'-diaminodiphenylmethane, and an epoxy composite material is prepared for comparison.

[0154] Application Example 1 and Application Comparative Examples 1 to 3 were tested, and the results are as attached Figure 6 As shown, the epoxy flame-retardant composite material prepared in Application Example 1 reaches the UL-94 V-0 grade.

[0155] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for preparing a flame retardant having a network cross-linked polymer coating layer with phosphorus and nitrogen components on the surface by using waste wind turbine blades, characterized in that The main steps include: (1) After pretreatment including cleaning, the waste wind turbine blade materials are crushed into wind turbine blade fragments with an average particle size of no more than 3 cm; (2) adding the wind turbine blade fragments obtained in step (1) into a grinding disc-shaped solid phase force chemical reactor for grinding and pulverization, and collecting the wind turbine blade powder after the grinding is completed; wherein the process parameters of the grinding disc-shaped solid phase force chemical reactor are: grinding pressure of 4 to 6 MPa, the grinding disc surface temperature is controlled at 20 to 30° C. by passing a circulating cooling liquid, the grinding number is at least 1, and the grinding disc speed is 30 to 60 rpm; (3) subjecting the wind turbine blade powder obtained in step (2) to surface modification with dopamine to obtain amino-functionalized modified wind turbine blade powder; (4) dissolving 20 to 50 parts by weight of a multifunctional amino compound in an organic solvent to prepare a multifunctional amino compound solution; 8 to 12 parts of the amino-functionalized modified wind turbine blade powder obtained in step (3) and 16 to 20 parts of cyclophosphazene are added to an organic solvent and an acid binding agent is added, and the mixture is stirred and reacted at a temperature of 60 to 80° C. for 20 to 30 minutes. After the time is up, a multifunctional amino compound solution is added dropwise and the temperature is maintained at 60 to 80° C. and stirred. After the addition is completed, the mixture is stirred and reacted for 5 to 10 hours at a temperature of 60 to 80° C. After the time is up, a flame retardant having a network cross-linked polymer coating layer with phosphorus and nitrogen components on the surface is prepared by filtering, washing and drying; The multifunctional amino compound includes any one of 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,4-diaminobenzenesulfonic acid, 2,4-diaminobenzaldehyde, 2,3-diaminobenzamide and 4-fluoro-1,3-diaminobenzene.

2. The method according to claim 1, characterized in that: The wind turbine blade powder described in step (3) is surface modified by dopamine to obtain amino-functionalized modified wind turbine blade powder. By weight, 2 to 4 parts of dopamine hydrochloride are dissolved in Tris buffer, and then 8 to 12 parts of wind turbine blade powder are added as a reaction mixture. The reaction is stirred at a temperature of 20 to 30°C for at least 24 hours. After the time is up, the amino-functionalized modified wind turbine blade powder is prepared by filtering, washing and drying.

3. The method according to claim 2, characterized in that: The method comprises dissolving 2 to 4 parts of dopamine hydrochloride in a mixed solution of Tris buffer and ethanol, wherein the volume ratio of Tris buffer to ethanol is 7:3, the concentration of Tris buffer is 0.1 mol / L, and the mass concentration of dopamine hydrochloride is 2 to 4 g / L.

4. The method according to claim 1, characterized in that: The wind turbine blade powder described in step (3) is surface modified by dopamine to obtain amino-functionalized modified wind turbine blade powder. By weight, 2 to 4 parts of dopamine hydrochloride, 1 to 3 parts of copper sulfate and 1 to 3 parts of hydrogen peroxide are dissolved in Tris buffer, and then 8 to 12 parts of wind turbine blade powder are added as a reaction mixture. The reaction is stirred at a temperature of 20 to 30° C. for at least 4 hours. After the time is up, the amino-functionalized modified wind turbine blade powder is prepared by filtering, washing and drying.

5. The method according to claim 1, characterized in that: The cyclophosphazene in step (4) includes any one of hexachlorocyclotriphosphazene, trichlorocyclotriphosphazene, hexafluorocyclotriphosphazene, ethoxy (pentafluoro) cyclotriphosphazene and pentafluoro (phenoxy) cyclotriphosphazene.

6. The method according to claim 1, characterized in that: In step (4), 20 to 50 parts of the multifunctional amino compound are dissolved in an organic solvent to prepare a multifunctional amino compound solution, wherein the mass concentration of the multifunctional amino compound is 40 to 100 g / L.

7. The method according to claim 1, characterized in that: In step (4), 8 to 12 parts of the amino-functionalized modified wind turbine blade powder obtained in step (3) and 16 to 20 parts of cyclophosphazene are added to an organic solvent and an acid binding agent is added, wherein the mass concentration of the amino-functionalized modified wind turbine blade powder in the organic solvent is 5 to 8 g / L.

8. The flame retardant having a network cross-linked polymer coating layer with phosphorus and nitrogen components on the surface prepared by the method for preparing a flame retardant having a network cross-linked polymer coating layer with phosphorus and nitrogen components on the surface using discarded wind turbine blades as claimed in claim 1.

9. The flame retardant having a network cross-linked polymer coating layer with phosphorus and nitrogen components on the surface as claimed in claim 8 is used to prepare epoxy flame retardant composite materials.

10. An epoxy flame retardant composite material, characterized in that The flame retardant having a network cross-linked polymer coating layer with phosphorus and nitrogen components on the surface as claimed in claim 8, wherein the raw materials thereof include, by weight: The surface has a phosphorus and nitrogen component network cross-linked polymer coating layer 10 to 40 parts flame retardant, Epoxy resin 100 parts, 10 to 30 parts of curing agent.

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