A modified nylon material and a method for preparing the same

Abstract

The application discloses a modified nylon material and a preparation method thereof, and belongs to the technical field of nylon materials. The modified nylon material comprises the following components in percentage by weight: a modified flame retardant 15-20 wt%; a lubricant 0.35-0.45 wt%; an antioxidant 0.31-0.40 wt%; and a filler 15-20 wt%; and the balance is a nylon 66 resin. The modified flame retardant is substituted by diphenyl phosphine and 1,2-dichloroethylene to form an intermediate 1, then tri-methoxy silane is added to the intermediate 1 by a silicon-hydrogen addition to form an intermediate 2, then the intermediate 2 is substituted by melamine to form an intermediate 3, and finally the intermediate 3 is hydrolyzed and condensed by using the multi-methoxy silane structure at the molecular end to coat the phosphorus-nitrogen structure in the middle of the molecule, so that the 'core-shell' composite structure is formed to protect the phosphorus-nitrogen structure from being damaged by high temperature, the mechanical properties and the thermal stability of the material are improved, and the flame-retardant efficiency is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nylon materials, and particularly relates to a modified nylon material and a preparation method thereof. BACKGROUND

[0002] Nylon 66, also known as polyhexamethylene adipamide, is prepared by using hexamethylene diamine and adipic acid as raw materials through step-by-step polymerization reaction, and its excellent comprehensive performance shows irreplaceable value in many fields. However, the flammability of nylon material greatly limits the application of nylon 66.

[0003] At present, phosphorus-nitrogen flame retardants are the mainstream choice for nylon flame-retardant modification, which play a flame-retardant role through gas-phase flame retardation and condensed-phase flame retardation. However, the existing phosphorus-nitrogen flame retardants still have the following key problems: 1. Insufficient thermal stability: the processing temperature of nylon is usually as high as 250-300℃, and the traditional phosphorus-nitrogen flame retardant is easy to decompose at this temperature, which leads to a decrease in flame-retardant efficiency and may release small-molecule gases, affecting the stability of the nylon molecular chain and reducing the mechanical properties of the material. At present, the method for solving the insufficient thermal stability of the flame retardant is mainly coating. The interface bonding force of the coating layer prepared by the traditional coating method through physical adsorption or simple chemical modification is weak and easy to fall off. Moreover, an additional coating material needs to be introduced, which increases the raw material cost and process steps, and the coating process conditions are complex, so the industrialized production is difficult. SUMMARY

[0004] In order to solve the technical problems mentioned in the background, the purpose of the present application is to provide a modified nylon material and a preparation method thereof.

[0005] The purpose of the present application can be achieved by the following technical solutions.

[0006] A modified nylon material, the weight percentage components of which are as follows: a modified flame retardant 15-20wt%; a filler 15-20wt%; a lubricant 0.35-0.45wt%; and an antioxidant 0.36-0.40wt%; and the balance is a nylon 66 resin.

[0007] The modified flame retardant is prepared by the following method.

[0008] Step A1: under the protection of nitrogen, diphenylphosphine and anhydrous tetrahydrofuran are mixed, cooled to 0-5℃ by ice bath, sodium hydride is slowly added, stirred for 30-40min, and then 1,2-dichloroethylene is added, and the reaction is carried out at room temperature for 6-7h. After the reaction is completed, quenching, extraction and distillation are carried out to prepare an intermediate 1.

[0009] Further, the feeding ratio of diphenylphosphine, 1,2-dichloroethylene, sodium hydride and anhydrous tetrahydrofuran is 1 mol: 1-1.5 mol: 0.5-0.6 mol: 4-4.5 L. Diphenylphosphine and 1,2-dichloroethylene undergo substitution reaction to generate phosphole compound. The specific reaction process is as follows:

[0010]

[0011] Step A2: Tetrahydrofuran and intermediate 1 are mixed, and then trimethoxysilane is added. After stirring uniformly, Karstedt catalyst is slowly added, and stirring is performed at 40-50°C for 4-6h. After the reaction is completed, rotary evaporation is performed to obtain intermediate 2.

[0012] Further, the feeding ratio of intermediate 1, trimethoxysilane, Karstedt catalyst and tetrahydrofuran is 1 mol: 1-1.2 mol: 3.6-4 g: 500-600 mL. Silicon hydride addition reaction generates phosphine derivative. Under the catalysis of Karstedt catalyst, trimethoxysilane and the carbon-carbon double bond in intermediate 1 undergo addition reaction to generate intermediate 2. The specific reaction process is as follows:

[0013]

[0014] Step A3: Melamine, anhydrous potassium carbonate, intermediate 2 and anhydrous N,N-dimethylformamide are mixed under nitrogen protection, and then stirring is performed. After uniform stirring, the temperature is increased to 120-140°C, and reaction is performed for 8-9h. After the reaction is completed, filtration and drying are performed to obtain intermediate 3.

[0015] Further, the feeding ratio of melamine, intermediate 2, anhydrous potassium carbonate and anhydrous N,N-dimethylformamide is 1 mol: 3 mol: 3-3.3 mol: 3.5-4 L. Intermediate 2 and melamine undergo nucleophilic substitution reaction. The amino group in melamine acts as a nucleophile to attack the carbon atom connected to the chlorine atom in intermediate 2, and the chlorine atom acts as a leaving group to leave to generate intermediate 3 containing an aminosilane structure.

[0016]

[0017] Step A4: Intermediate 3 is pre-mixed with ethanol, and then mixed with water. While stirring, dilute hydrochloric acid is slowly added dropwise until the pH is 3-4, and reaction is performed at room temperature for 2-4h. Then, the temperature is increased to 60-80°C, and stirring is performed for 3-5h. After the reaction is completed, modified flame retardant is obtained by distillation under reduced pressure.

[0018] Further, the feeding ratio of intermediate 3, water and ethanol is 1 mol: 4.5-5 mol: 600-800 mL. Under the action of water, the methoxysilane structure at the end of the molecule of intermediate 3 is hydrolyzed to generate a silicon hydroxyl, and further intermolecular condensation occurs to form a Si-O-Si network, which coats the phosphorus-nitrogen structure in the middle.

[0019] Preferably, the antioxidant is antioxidant 1790, which has high antioxidant efficiency, excellent thermal stability, good compatibility, and can maintain product color stability, strong resistance to extraction.

[0020] Preferably, the lubricant is zinc stearate, which has good lubricity, high thermal stability, and good compatibility with nylon 66 resin.

[0021] Preferably, the filler is short-cut glass fiber, which can improve the mechanical properties of the material, and also can enhance the structural stability of the carbon layer and reduce the molten droplets.

[0022] A preparation method of a modified nylon material, specifically: nylon 66 resin, modified flame retardant, lubricant, antioxidant are stirred in a high-speed mixer for 10 min, then added into a double-screw extruder, and a filler is added from a side feeding port, after extrusion, cooling and granulation, a modified nylon material is obtained.

[0023] The beneficial effects of the present application are:

[0024] The application is based on a traditional flame-retardant nylon system, and a modified flame retardant is introduced for blending modification. The modified flame retardant is a compound containing phosphorus olefin structure formed by substituting diphenyl phosphine and 1,2-dichloroethylene, that is, intermediate 1. Then, trimethoxysilane is added to intermediate 1 by hydrosilylation to introduce a methoxysilane structure to form intermediate 2. Then, intermediate 2 is substituted with melamine to form a phosphorus-nitrogen compound, that is, intermediate 3. Finally, the multiple methoxysilane structures at the molecular ends of intermediate 3 are hydrolyzed and condensed to coat the phosphorus-nitrogen structure in the middle of the molecule. Compared with the phosphorus-nitrogen flame retardant in the prior art, the modified flame retardant prepared by the application has the following advantages: the multiple methoxysilane structures at the molecular ends can spontaneously condense to form a silicone network, which can protect the core phosphorus-nitrogen structure in situ without additional harsh conditions, effectively improving the overall decomposition temperature of the flame-retardant system, and matching the processing temperature range of the nylon matrix. The processing temperature range of the nylon matrix can be avoided. In the condensation process, the silicone network and the phosphorus-nitrogen structure form a "core-shell" composite structure through intercalation and envelope action: the active center of the inner core phosphorus-nitrogen is tightly coated by the outer shell silicone layer, which can isolate the interference of external environmental factors such as oxygen and moisture, and reduce the migration and loss of active components; the outer shell three-dimensional silicon-oxygen network also improves the mechanical properties and thermal stability of the material through chemical bonding and physical entanglement. At the same time, in a high-temperature combustion environment, the composite structure presents a synergistic flame-retardant mechanism: the inner core phosphorus-nitrogen component decomposes to produce inert gas and releases phosphoric acid to catalyze the formation of carbon from the nylon matrix; the outer shell silicone network forms a silicon-carbon reinforced layer through dehydration and condensation, which suppresses the common defect of loose and porous structure in the carbonization process of traditional phosphorus-nitrogen flame retardants, and builds a high-strength and dense integrated flame-retardant carbon layer on the surface of the nylon matrix, effectively blocking heat transfer and oxygen diffusion, and preventing combustion from spreading to the inside of the material, thus greatly improving the flame-retardant efficiency. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0026] Example 1, preparation of modified nylon material, the implementation process is as follows:

[0027] I. Synthesis of modified flame retardant

[0028] Step A1: Diphenylphosphine and anhydrous tetrahydrofuran were mixed under nitrogen protection, cooled to 0℃ in an ice bath, and sodium hydride was slowly added, stirred for 30 min, then 1,2-dichloroethylene was added, and the reaction was carried out at room temperature for 6 h. The feeding ratio of diphenylphosphine, 1,2-dichloroethylene, sodium hydride and anhydrous tetrahydrofuran was 1 mol: 1.5 mol: 1.2 mol: 4 L. After the reaction was completed, about 20 mL of saturated ammonium chloride solution was slowly added dropwise under ice bath cooling to quench the excess sodium hydride without bubbles. The solution was separated by extraction with toluene, and the organic phase was washed with about 40 mL of saturated brine, dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation to obtain intermediate 1.

[0029] Step A2: Tetrahydrofuran and intermediate 1 were mixed, then trimethoxysilane was added, stirred uniformly, then Karstedt catalyst was slowly added, and stirred at 40℃ for 4 h. The feeding ratio of intermediate 1, trimethoxysilane, Karstedt catalyst and tetrahydrofuran was 1 mol: 1.2 mol: 3.6 g: 500 mL. After the reaction was completed, the tetrahydrofuran and excess trimethoxysilane were removed by rotary evaporation to obtain intermediate 2.

[0030] Step A3: Melamine, anhydrous potassium carbonate, intermediate 2 and anhydrous N,N-dimethylformamide were mixed under nitrogen protection, stirred uniformly, then heated to 120℃ and reacted for 8 h. The feeding ratio of melamine, intermediate 2, anhydrous potassium carbonate and anhydrous N,N-dimethylformamide was 1 mol: 3 mol: 3.3 mol: 4 L. After the reaction was completed, the potassium carbonate was removed by filtration and dried to obtain intermediate 3.

[0031] Step A4: Intermediate 3 was pre-mixed with ethanol, then mixed with water, and slowly added dropwise with stirring until the pH was 3-4, and reacted at room temperature for 2-4 h. Then heated to 60-80℃ and stirred for 3-5 h. The feeding ratio of intermediate 3, water and ethanol was 1 mol: 5 mol: 800 mL. After the reaction was completed, ethanol and water were removed by distillation under reduced pressure to obtain the modified flame retardant.

[0032] II. Preparation of modified nylon material

[0033] According to the component preparation, the modified flame retardant was 15 wt%, self-made in this example; the lubricant was 0.45 wt%, and zinc stearate was selected, with the specific model SY-F0128; the antioxidant was 0.4 wt%, and antioxidant 1790 was selected; the filler was 20 wt%, and short glass fiber was selected, with the specific model 988A; and the balance was nylon resin, and nylon 66 resin was selected.

[0034] The nylon 66 resin, modified flame retardant, lubricant and antioxidant were stirred in a high-speed mixer for 10 min, then added to a twin-screw extruder, and the filler was added from the side feeding port. After extrusion, the mixture was cooled and pelletized to obtain the modified nylon material.

[0035] Example 2, preparation of modified nylon material, the implementation process as follows:

[0036] I. Synthesis of modified flame retardant

[0037] Step A1: under nitrogen protection, diphenyl phosphine and anhydrous tetrahydrofuran were mixed, cooled to 0℃ in ice bath, sodium hydride was slowly added, stirred for 30 min, then 1,2-dichloroethylene was added, and the reaction was carried out at room temperature for 6h. Among them, the feeding ratio of diphenyl phosphine, 1,2-dichloroethylene, sodium hydride and anhydrous tetrahydrofuran was 1mol:1.5mol:1.2mol:4L. After the reaction was completed, about 20mL saturated ammonium chloride solution was slowly added dropwise under ice bath cooling to quench the excess sodium hydride without bubbles. Extraction separation was carried out with toluene, the organic phase was washed with about 40mL saturated brine, dried with anhydrous sodium sulfate, and the solvent was removed by rotary evaporation to obtain intermediate 1.

[0038] Step A2: tetrahydrofuran and intermediate 1 were mixed, then trimethoxysilane was added, stirred uniformly, then Karstedt catalyst was slowly added, and stirred at 40℃ for 4h. Among them, the feeding ratio of intermediate 1, trimethoxysilane, Karstedt catalyst and tetrahydrofuran was 1mol:1.2mol:3.6g:500mL. After the reaction was completed, tetrahydrofuran and excess trimethoxysilane were removed by rotary evaporation to obtain intermediate 2.

[0039] Step A3: under nitrogen protection, melamine, anhydrous potassium carbonate, intermediate 2 and anhydrous N,N-dimethylformamide were mixed, stirred uniformly, then heated to 120℃ and reacted for 8h. Among them, the feeding ratio of melamine, intermediate 2, anhydrous potassium carbonate and anhydrous N,N-dimethylformamide was 1mol:3mol:3.3mol:4L. After the reaction was completed, the potassium carbonate was removed by filtration and dried to obtain intermediate 3.

[0040] Step A4: intermediate 3 was pre-mixed with ethanol, then mixed with water, and diluted hydrochloric acid was slowly added dropwise while stirring until the pH was 3-4, and the reaction was carried out at room temperature for 2-4h. Then the temperature was increased to 60-80℃ and stirred for 3-5h. Among them, the feeding ratio of intermediate 3, water and ethanol was 1mol:5mol:800mL. After the reaction was completed, ethanol and water were removed by distillation under reduced pressure to obtain the modified flame retardant.

[0041] II. Preparation of modified nylon material

[0042] According to the component preparation, the modified flame retardant was 20wt%, self-made in this example; the lubricant was 0.35wt%, and zinc stearate was selected, with the specific model SY-F0128; the antioxidant was 0.36wt%, and antioxidant 1790 was selected; the filler was 15wt%, and short glass fiber was selected, with the specific model 988A; the rest was nylon resin, and nylon 66 resin was selected.

[0043] The nylon 66 resin, modified flame retardant, lubricant, antioxidant were stirred in a high-speed mixer for 10 min, then added into a twin-screw extruder, and the filler was added from the side feeding port. After extrusion, the mixture was cooled and cut into particles to obtain the modified nylon material.

[0044] Example 3, preparation of modified nylon material, the implementation process is as follows:

[0045] I. Synthesis of modified flame retardant

[0046] Step A1: Diphenylphosphine and anhydrous tetrahydrofuran were mixed under nitrogen protection, cooled to 0°C in an ice bath, and sodium hydride was slowly added. After stirring for 30 min, 1,2-dichloroethylene was added, and the reaction was carried out at room temperature for 6 h. The feeding ratio of diphenylphosphine, 1,2-dichloroethylene, sodium hydride and anhydrous tetrahydrofuran was 1 mol:1.5 mol:1.2 mol:4 L. After the reaction was completed, about 20 mL of saturated ammonium chloride solution was slowly added dropwise under ice bath cooling to quench the excess sodium hydride without bubbles. The mixture was extracted with toluene, and the organic phase was washed with about 40 mL of saturated brine, dried with anhydrous sodium sulfate, and the solvent was removed by rotary evaporation to obtain intermediate 1.

[0047] Step A2: Tetrahydrofuran and intermediate 1 were mixed, and then trimethoxysilane was added. After stirring, Karstedt catalyst was slowly added, and the mixture was stirred at 40°C for 4 h. The feeding ratio of intermediate 1, trimethoxysilane, Karstedt catalyst and tetrahydrofuran was 1 mol:1.2 mol:3.6 g:500 mL. After the reaction was completed, the tetrahydrofuran and excess trimethoxysilane were removed by rotary evaporation to obtain intermediate 2.

[0048] Step A3: Melamine, anhydrous potassium carbonate, intermediate 2 and anhydrous N,N-dimethylformamide were mixed under nitrogen protection, and then stirred uniformly. The mixture was heated to 120°C and reacted for 8 h. The feeding ratio of melamine, intermediate 2, anhydrous potassium carbonate and anhydrous N,N-dimethylformamide was 1 mol:3 mol:3.3 mol:4 L. After the reaction was completed, the potassium carbonate was removed by filtration, and dried to obtain intermediate 3.

[0049] Step A4: Intermediate 3 was pre-mixed with ethanol, and then mixed with water. While stirring, dilute hydrochloric acid was slowly added dropwise until the pH was 3-4, and the mixture was reacted at room temperature for 2-4 h. Then the temperature was increased to 60-80°C, and the mixture was stirred for 3-5 h. The feeding ratio of intermediate 3, water and ethanol was 1 mol:5 mol:800 mL. After the reaction was completed, ethanol and water were removed by distillation under reduced pressure to obtain the modified flame retardant.

[0050] II. Preparation of modified nylon material

[0051] According to the component preparation, the modified flame retardant is 17wt%, the self-made of this embodiment; the lubricant is 0.42wt%, the zinc stearate is selected, and the specific model is SY-F0128; the antioxidant is 0.38wt%, the antioxidant 1790 is selected; the filler is 18wt%, the chopped glass fiber is selected, and the specific model is 988A; and the balance is nylon resin, and the nylon 66 resin is selected.

[0052] The nylon 66 resin, the modified flame retardant, the lubricant and the antioxidant are stirred in the high-speed mixer for 10 minutes, and then added into the double-screw extruder; the filler is added from the side feeding port; after extrusion, cooling and granulation, the modified nylon material is obtained.

[0053] Example 4, the preparation of the modified nylon material, the implementation process is as follows:

[0054] I. Synthesis of modified flame retardant

[0055] Step A1: under the protection of nitrogen, diphenyl phosphine and anhydrous tetrahydrofuran are mixed, cooled to 0℃ in an ice bath, sodium hydride is slowly added, stirred for 30min, then 1,2-dichloroethylene is added, and the reaction is carried out at room temperature for 6h. The feeding ratio of diphenyl phosphine, 1,2-dichloroethylene, sodium hydride and anhydrous tetrahydrofuran is 1mol:1.5mol:1.2mol:4L. After the reaction is completed, about 20mL of saturated ammonium chloride solution is slowly added dropwise under ice bath cooling to quench the excess sodium hydride until there is no bubble. Extracted by toluene, the organic phase is washed with about 40mL of saturated brine, dried with anhydrous sodium sulfate, and the solvent is removed by rotary evaporation to obtain intermediate 1.

[0056] Step A2: tetrahydrofuran and intermediate 1 are mixed, then trimethoxysilane is added, stirred uniformly, then Karstedt catalyst is slowly added, stirred at 40℃ for 4h. The feeding ratio of intermediate 1, trimethoxysilane, Karstedt catalyst and tetrahydrofuran is 1mol:1.2mol:3.6g:500mL. After the reaction is completed, the tetrahydrofuran and excess trimethoxysilane are removed by rotary evaporation to obtain intermediate 2.

[0057] Step A3: under the protection of nitrogen, melamine, anhydrous potassium carbonate, intermediate 2 and anhydrous N,N-dimethylformamide are mixed, stirred uniformly, then heated to 120℃ for 8h. The feeding ratio of melamine, intermediate 2, anhydrous potassium carbonate and anhydrous N,N-dimethylformamide is 1mol:3mol:3.3mol:4L. After the reaction is completed, the potassium carbonate is removed by filtration, and dried to obtain intermediate 3

[0058] Step A4: Intermediate 3 was pre-mixed with ethanol, then mixed with water, and then slowly added with dilute hydrochloric acid while stirring until the pH was 3-4, and then reacted at room temperature for 2-4 h. Then, the temperature was increased to 60-80 °C and stirred for 3-5 h. In this process, the ratio of intermediate 3, water and ethanol was 1 mol: 5 mol: 800 mL. After the reaction was completed, ethanol and water were removed by distillation under reduced pressure to obtain the modified flame retardant.

[0059] II. Preparation of modified nylon material

[0060] According to the component preparation, the modified flame retardant is 19wt%, which is self-made in this example; the lubricant is 0.38wt%, which is selected as zinc stearate, and the specific model is SY-F0128; the antioxidant is 0.37wt%, which is selected as antioxidant 1790; the filler is 17wt%, which is selected as chopped glass fiber, and the specific model is 988A; and the balance is nylon resin, which is selected as nylon 66 resin.

[0061] The nylon 66 resin, modified flame retardant, lubricant and antioxidant were stirred in a high-speed mixer for 10 min, then added to a twin-screw extruder, and the filler was added from the side feeding port. After extrusion, cooling and granulation, the modified nylon material was obtained.

[0062] In the comparative example, referring to Example 4, the modified flame retardant was replaced by 19wt% ammonium polyphosphate APP1002, and the rest of the process was the same.

[0063] The modified flame retardant prepared above was sampled, and the thermal decomposition onset temperature test was carried out according to the ASTM E1131-2020 standard. The modified nylon material prepared above was made into a sample bar according to the following requirements, and the sample was tested. The tensile strength test was carried out according to the GB / T 1040-2006 standard, and the sample bar specification was 80mm×10mm×4mm. The limiting oxygen index (LOI) test was carried out according to the GB / T 2406.2-2009 standard, and the sample bar specification was 80mm×10mm×4mm. Horizontal and vertical burning method (UL-94): according to the GB / T 2408-2021 standard, the sample bar specification was 130mm×13mm×3mm. The specific test results are as follows:

[0064] Thermal decomposition temperature / °C Tensile strength / MPa LOI / % UL-94 Example 1 318 72.34 29.8 V-1 Example 2 335 63.27 32.2 V-0 Example 3 323 68.78 31.3 V-0 Example 4 326 65.49 31.8 V-0 Comparative Example 290 60.51 24.7 V-1

[0065] From the above test results, it can be seen that the above samples all have good thermal stability, flame retardancy and mechanical properties, and compared with the previous flame retardant, the modified flame retardant has a higher thermal decomposition onset temperature, and the sample nylon material has better flame retardancy and mechanical properties. From the test data of the comparative example, it can be seen that with the increase of the proportion of the modified flame retardant, the thermal stability, flame retardancy and mechanical properties are better and better. Combined with Example 4 and the comparative example, the modified nylon material prepared by using the existing flame retardant has slightly lower thermal stability, flame retardancy and mechanical property parameters.

[0066] In the description, references to "one embodiment," "an example," "certain examples" etc. mean that the particular feature, structure, material, or characteristic being described is included in at least one embodiment or example of the application. The appearances of an item in various examples or embodiments is not necessarily indicative of a frequency of occurrence in the various examples or embodiments. Moreover, descriptions of well-known or conventional features, structures, materials, or characteristics can be superseded by similar features, structures, materials, or characteristics.

[0067] The above description is merely illustrative of the application and is not intended to limit the scope of the application which is defined by the appended claims.

Claims

1. A modified nylon material characterized in that, The specific components are: modified flame retardant 15-20wt%; lubricant 0.35-0.45wt%; antioxidant 0.31-0.40wt% and filler 15-20wt%; the balance is nylon 66 resin; The modified flame retardant is prepared by the following method: Step A1: under nitrogen protection, diphenylphosphine and anhydrous tetrahydrofuran are mixed, cooled to 0-5℃ in an ice bath, sodium hydride is slowly added, stirred for 30-40min, then 1,2-dichloroethylene is added, and the reaction is carried out at room temperature for 6-7h; after the reaction is completed, quenching, extraction and distillation are carried out to obtain intermediate 1; Step A2: tetrahydrofuran and intermediate 1 are mixed, then trimethoxysilane is added, stirred uniformly, then Karstedt catalyst is slowly added, stirred at 40-50℃ for 4-6h, after the reaction is completed, vacuum distillation is carried out to obtain intermediate 2; Step A3: under nitrogen protection, melamine, anhydrous potassium carbonate, intermediate 2 and anhydrous N,N-dimethylformamide are mixed, stirred uniformly, then heated to 120-140℃ for 8-9h, after the reaction is completed, filtration and drying are carried out to obtain intermediate 3; Step A4: intermediate 3 is pre-mixed with ethanol, then mixed with water, and dilute hydrochloric acid is slowly added dropwise under stirring until the pH is 3-4, then the reaction is carried out at room temperature for 2-4h, then heated to 60-80℃ for stirring for 3-5h, after the reaction is completed, vacuum distillation is carried out to obtain the modified flame retardant.

2. The modified nylon material of claim 1, wherein, The feeding ratio of diphenylphosphine, 1,2-dichloroethylene, sodium hydride and anhydrous tetrahydrofuran is 1mol:1-1.5mol:0.5-0.6mol:4-4.5L.

3. The modified nylon material of claim 1, wherein, The feeding ratio of intermediate 1, trimethoxysilane, Karstedt catalyst and tetrahydrofuran is 1mol:1-1.2mol:3.6-4g:500-600mL.

4. The modified nylon material of claim 1, wherein, The feeding ratio of melamine, intermediate 2, anhydrous potassium carbonate and anhydrous N,N-dimethylformamide is 1mol:3mol:3-3.3mol:3.5-4L.

5. The modified nylon material of claim 1, wherein, The feeding ratio of intermediate 3, water and ethanol is 1mol:4.5-5mol:600-800mL.

6. The modified nylon material of claim 1, wherein, The antioxidant is antioxidant 1790.

7. The modified nylon material of claim 1, wherein, The lubricant is zinc stearate.

8. The modified nylon material of claim 1, wherein, The filler is chopped glass fiber.

9. A method for preparing a modified nylon material according to any one of claims 1-8, characterized in that, Specifically, the nylon 66 resin, the modified flame retardant, the lubricant and the antioxidant are uniformly mixed, then the filler is added from the side feeding port of the twin-screw extruder, and the extrudate is cooled and pelletized to obtain the modified nylon material.

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