A composite material recycling waste nylon and a preparation method thereof

Abstract

The application discloses a kind of composite material for recycling waste nylon and preparation method thereof, the composite material is made of the following weight parts of each component: waste nylon, 45-70 parts, preferably 50-60 parts;Microencapsulated flame retardant, 12-30 parts, preferably 16-24 parts;Hollow glass microsphere, 20-40 parts, preferably 25-35 parts;Auxiliary agent, 1-3 parts, preferably 1.5-2.5 parts;The microencapsulated flame retardant has the microencapsulated structure with flame retardant as the core, with epoxy silane oligomer MP200 as the coating shell.The composite material has excellent mechanical properties and flame retardant properties, and has the advantage of lighter quality.

Description

Technical Field

[0001] This invention relates to a composite material and its preparation method, and more particularly to a composite material and its preparation method that utilizes recycled waste nylon. Background Technology

[0002] Long-chain nylon plays an irreplaceable role in cooling pipes, industrial pipelines, and gas pipelines due to its low density, good low-temperature toughness, low water absorption, dimensional stability, and excellent solvent resistance. Furthermore, this type of material has excellent electrical properties, making it promising for applications in electronics, smart wearables, new energy vehicles, and photovoltaics.

[0003] In recent years, countries around the world have been actively advocating and promoting environmentally friendly, low-carbon green materials, and major enterprises have been actively responding to government calls for the secondary recycling of materials. Long-chain nylon, as a high-cost and high-performance material, is particularly relevant in this regard. However, long-chain nylon that has undergone one or more injection molding processes (referred to as "waste nylon" in this article) has lost its original performance advantages due to degradation and a decrease in molecular weight. On the other hand, the amide bond density of waste nylon further decreases, making flame retardancy even more challenging. Therefore, how to utilize waste nylon to produce flame-retardant nylon composite materials has become an urgent problem to be solved.

[0004] Reports on the reuse of waste nylon in Chinese patents are scarce. CN104861644A proposes a flame-retardant, recyclable, and insulating modified material, which is prepared by melt-blending nylon 6 / 66, surface-modified glass fiber with coupling agent, and microencapsulated red phosphorus to obtain a nylon material suitable for medium and high voltage electrical equipment. However, it does not describe a method for reusing the nylon material after injection molding, thus failing to address the technical problem proposed in this invention. Furthermore, this patent, relying solely on melt blending, cannot effectively combine nylon 6 / 66, surface-modified glass fiber with coupling agent, and microencapsulated red phosphorus. Therefore, not only is the mechanical property of the resin significantly compromised, but the microencapsulated red phosphorus still easily precipitates, resulting in the material's flame-retardant performance failing to meet requirements. Summary of the Invention

[0005] To address the above technical problems, this invention proposes a composite material for recycling waste nylon and its preparation method. This composite material has excellent mechanical properties and flame retardant properties.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A composite material made from recycled waste nylon, comprising the following components in parts by weight:

[0008] S1, waste nylon, 45-70 parts, preferably 50-60 parts;

[0009] S2, microencapsulated flame retardant, 12-30 parts, preferably 16-24 parts;

[0010] S3, hollow glass microspheres, 20-40 parts, preferably 25-35 parts;

[0011] S4, additives, 1-3 parts, preferably 1.5-2.5 parts;

[0012] The microencapsulated flame retardant has a microencapsulated structure with the flame retardant as the core and the epoxy silane oligomer MP200 as the outer shell.

[0013] In some examples, the epoxy silane oligomer MP200 has an epoxy value of 4-5 mmol / g and a viscosity of 30-40 Pa·s, preferably Momentive COATOSIL*MP200.

[0014] In some examples, the mass ratio of the flame retardant to the epoxy silane oligomer MP200 in the microencapsulated flame retardant is (0.2-5):1, preferably (0.3-3):1.

[0015] In some examples, the flame retardant is one or more of red phosphorus, melamine pyrophosphate, aluminum diethylphosphite, magnesium hydroxide, and composite phosphorus-nitrogen flame retardants.

[0016] MP200 is an epoxy silane oligomer that readily aggregates at the solid-liquid interface, undergoing hydrolysis and condensation reactions. When mixed with flame retardants, it can hydrolyze and condense into large molecules on their surface, thus coating the flame retardants. This makes it difficult for the flame retardants to precipitate out and allows for more uniform dispersion, preventing agglomeration and resulting in excellent flame retardant performance.

[0017] Based on the structural characteristics of MP200, its reaction process with flame retardants can be achieved through... Figure 1 Demonstrate. For example... Figure 1 As shown, after hydrolysis, the multiple silanol groups at the head of MP200 are used to coat flame retardants, and the multiple epoxy groups at the tail can be used to graft hollow glass microspheres and broken nylon chains (the long molecular chains of injection-molded nylon are broken to a certain extent, and the broken nylon chains contain a large number of exposed amino or carboxyl groups, which can be regenerated into long-chain nylon through reaction with epoxy groups, thereby restoring excellent performance). The long ether bonds in the middle can make the grafted product have a certain degree of flexibility, preventing the hollow microspheres from being crushed by pressure during extrusion and losing their reinforcing effect, thus obtaining a reinforced renewable nylon composite material.

[0018] In some examples, the waste nylon is selected from at least one of long-chain nylons PA66, PA6, PA610, PA612, PA11, PA1010, and PA12; preferably, the waste nylon is unfilled or has a filler content of <5% granular resin particles.

[0019] In some examples, the density of the hollow glass microspheres is 0.2-0.8 g / cm³. 3 The preferred concentration is 0.4-0.65 g / cm³. 3 The compressive strength is 20-210MPa, preferably 60-200MPa.

[0020] In some examples, the additive is any one or more of heat stabilizers, light stabilizers, and lubricants;

[0021] Preferably, the heat stabilizer is one or more of copper salt antioxidants, phosphate antioxidants, hindered phenolic antioxidants, phosphite antioxidants, thioester antioxidants, and polymeric antioxidants; more preferably, it is a copper salt antioxidant; and even more preferably, it is one or more of H320, H324, H1607, H3336, H3376, H3344, S5050, S5070, and AO-K.

[0022] Preferably, the light stabilizer is one or more of salicylates, substituted acrylonitriles, triazines, benzotriazoles, xylene ketones, and amine stabilizers, and more preferably one or more of UV234, UV360, TFB117, and H2002;

[0023] Preferably, the lubricant is one or more of olefins, esters, stearates, and stearates.

[0024] This invention also provides a method for preparing a composite material from recycled waste nylon as described above, comprising the following steps:

[0025] 1) Mix a portion of the microencapsulated flame retardant, hollow glass microspheres, and optionally a lubricant in a mixer to obtain mixture A;

[0026] 2) Add waste nylon granules, optional geothermal stabilizer, light stabilizer and lubricant from the main feed port of the twin-screw extruder; add the remaining microencapsulated flame retardant from the first side feed port; add mixture A from the second side feed port; extrude and granulate to obtain the composite material.

[0027] The method of the present invention preferentially mixes microencapsulated flame retardants with hollow glass microspheres, so that the hydroxyl groups on the surface of the hollow glass microspheres react with the epoxy groups on the surface of the microencapsulated flame retardants, thereby making the two firmly bonded and enhancing the overall bonding of the composite material. In addition, since there are long ether segments with good elasticity between the hollow glass microspheres and the flame retardant, the hollow glass microspheres can be protected from damage during the material processing.

[0028] In some examples, the mixing conditions of the internal mixer in step 1) are: temperature 210-260℃, preferably 245-255℃, speed 20-100rpm, preferably 30-40rpm, and mixing time 2-10min, preferably 3-4min;

[0029] The extrusion conditions of the twin-screw extruder in step 2) are: feeding section 80-220℃, melting section 220-255℃, die head section 210-250℃; screw speed 200-400rpm, preferably 250-350rpm;

[0030] Preferably, the amount of microencapsulated flame retardant added in step 1) accounts for 25-75% of its total mass.

[0031] In some examples, the preparation method of the microencapsulated flame retardant is as follows:

[0032] A. Add flame retardant and emulsifier to water-alcohol solution, adjust pH to 8-11 (preferably 9-10), and stir under heating conditions;

[0033] B. Add MP200 to the above solution, react and then age to obtain a solid product;

[0034] C. Wash the solid product with alcohol and dry it to obtain the microencapsulated flame retardant.

[0035] In some examples, the emulsifier is one or more of organosilicon, alkyl salt, and ether, and the amount of emulsifier used is 0.5-2% of the total mass of the flame retardant and MP200, preferably 1-1.5%.

[0036] Preferably, in step A, the heating temperature is 35-65℃, more preferably 40-50℃, and the stirring time is 20-60min, more preferably 30-40min; in step B, the reaction time is 3-6h, more preferably 4-5h, and the aging time after the reaction is 6-30h, more preferably 12-18h.

[0037] In some examples, the aqueous alcohol solution in step A is a mixture of deionized water and anhydrous ethanol in a mass ratio of 1:0.25-4, preferably 1:0.5-2.

[0038] The beneficial effects of this invention are as follows:

[0039] This invention proposes a novel scheme for preparing composite materials from waste nylon, which addresses existing waste nylon products on the market. This scheme can effectively restore the excellent properties of long-chain nylon and add excellent flame retardant properties. In addition, the flame retardant in this composite material is not easily released, the product is lightweight and has excellent mechanical properties, and has wide industrial applicability. Attached Figure Description

[0040] Figure 1 This diagram illustrates the reaction process between MP200 and the flame retardant. Detailed Implementation

[0041] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0042] Information on the raw materials used in the examples and comparative examples is shown in Table 1:

[0043] Table 1. Raw Material Information

[0044]

[0045]

[0046] The hollow glass microspheres in the following embodiments are all subjected to acid washing treatment before use, specifically as follows:

[0047] Hollow glass microspheres were added to a 5% hydrofluoric acid solution and stirred at room temperature for 2 hours. The microspheres were then filtered out. The microspheres were first washed with a 1% sodium carbonate aqueous solution, and then washed with deionized water until the pH of the washing solution was approximately 7.

[0048] The internal mixer used was manufactured by Taixing Ruixing Rubber Machinery Co., Ltd.

[0049] The twin-screw extruder used was a product of Coperon Nanjing Machinery Co., Ltd.

[0050] The oxygen index (OLI, in %) test method in the examples and comparative examples was carried out according to ISO 4589 standard; the smoke density test was carried out according to ISO 5659 standard; the tensile strength test was carried out according to ISO 527 and the impact strength test was carried out according to ISO 180; the mold fouling was graded by visual observation, where Grade 1: virtually no mold fouling; Grade 2: partially visible; Grade 3: very serious mold fouling.

[0051]

Preparation of Example 1

[0052] Microencapsulated flame retardant a was prepared according to the following process:

[0053] Step 1: Add 250ml of a mixture of deionized water and anhydrous ethanol in a 4:1 ratio to a four-necked flask equipped with a thermometer, stirrer, and reflux condenser. Heat to 35°C and stir for 60 minutes.

[0054] Step 2: Continue to add 50g MPP and 1.25g emulsifier OP-10, adjust the pH of the solution to 8 with ammonia water, and then stir for 60 minutes.

[0055] Step 3: Slowly add 200g of MP200 to the solution, continue the reaction for 6 hours, then stop the reaction and allow it to cool and age at room temperature for 6 hours.

[0056] Step 4: Wash the reaction product with ethanol and dry it in a vacuum oven to obtain microcapsule flame retardant a.

[0057]

Preparation of Example 2

[0058] Microencapsulated flame retardant b was prepared according to the following process:

[0059] Step 1: Add 250ml of a 1:4 mixture of deionized water and anhydrous ethanol to a four-necked flask equipped with a thermometer, stirrer, and reflux condenser. Heat to 65℃ and stir for 20 minutes.

[0060] Step 2: Continue to add 25g MPP and 3g emulsifier OP-10, adjust the pH of the solution to 11 with ammonia water, and then stir for 20 minutes.

[0061] Step 3: Slowly add 125g of MP200 to the solution, continue the reaction for 5 hours, then stop the reaction and allow it to age at room temperature for 18 hours.

[0062] Step 4: Wash the reaction product with ethanol and dry it in a vacuum oven to obtain microcapsule flame retardant b.

[0063] [Preparation Example 3]

[0064] Microencapsulated flame retardant c was prepared according to the following process:

[0065] Step 1: Add 240 ml of a 1:2 mixture of deionized water and anhydrous ethanol to a four-necked flask equipped with a thermometer, stirrer, and reflux condenser. Heat the mixture to 50°C and stir for 30 min.

[0066] Step 2: Continue to add 40g of red phosphorus powder WQ12 and 1.6g of emulsifier OP-10, adjust the pH of the solution to 10 with ammonia water, and then stir for 30 minutes.

[0067] Step 3: Slowly add 120g of MP200 to the solution, continue the reaction for 4 hours, then stop the reaction and let it cool and age at room temperature for 30 hours.

[0068] Step 4: Wash the reaction product with ethanol and dry it in a vacuum oven to obtain microcapsule flame retardant c.

[0069] [Preparation Example 4]

[0070] Microencapsulated flame retardant d was prepared according to the following process:

[0071] Step 1: Add 320ml of a 2:1 mixture of deionized water and anhydrous ethanol to a four-necked flask equipped with a thermometer, stirrer, and reflux condenser. Heat to 40℃ and stir for 40 minutes.

[0072] Step 2: Continue to add 40g MPP and 0.96g emulsifier OP-10, adjust the pH of the solution to 9 with ammonia water, and then stir for 40 minutes.

[0073] Step 3: Slowly add 8g of MP200 to the solution, continue the reaction for 3 hours, then stop the reaction and let it cool and age at room temperature for 12 hours.

[0074] Step 4: Wash the reaction product with ethanol and dry it in a vacuum oven to obtain microcapsule flame retardant d.

[0075] [Preparation Example 5]

[0076] Microencapsulated flame retardant e was prepared according to the following process:

[0077] Step 1: Add 280ml of a 3:1 mixture of deionized water and anhydrous ethanol to a four-necked flask equipped with a thermometer, stirrer, and reflux condenser. Heat to 45℃ and stir for 50min.

[0078] Step 2: Continue to add 40g of OP1312 and 0.8g of emulsifier OP-10, adjust the pH of the solution to 9 with ammonia water, and then stir for 50 minutes.

[0079] Step 3: Slowly add 13.3g of MP200 to the solution, continue the reaction for 3.5h, then stop the reaction and let it age at room temperature for 20h.

[0080] Step 4: Wash the reaction product with ethanol and dry it in a vacuum oven to obtain microcapsule flame retardant e.

[0081] [Preparation Example 6]

[0082] The preparation was carried out in essentially the same manner as in Preparation Example 2, except that MP200 was replaced with KH550. The resulting product is designated as microencapsulated flame retardant f.

[0083] [Preparation Example 7]

[0084] The preparation was carried out in essentially the same manner as in Preparation Example 2, except that MP200 was replaced with GR216. The resulting product is denoted as microencapsulated flame retardant g.

[0085]

Example 1

[0086] 6g of microencapsulated flame retardant a, 20g of HS46 and 0.2g of E wax were placed in a mixer and mixed for 2 minutes at a temperature of 210℃ and a speed of 20rpm to obtain mixture A.

[0087] The extrusion process employs a twin-screw extruder. 45g of recycled PA6, 0.2g of 1010, 0.2g of 168, 0.3g of UV234, 0.3g of S-EED, and 0.2g of E-wax are added via the main feed. 6g of microencapsulated flame retardant is added via the first side feed, and mixture A is added via the second side feed. The feeding section maintains a temperature of 80-220℃, the melting section 230-245℃, and the die head section 210-230℃, with a rotation speed of 200 rpm.

[0088]

Example 2

[0089] 10g of microencapsulated flame retardant b, 40g of HS46, and 0.5g of E wax were placed in an internal mixer and mixed for 10 minutes at a temperature of 260℃ and a speed of 100rpm to obtain mixture A.

[0090] The process employs a twin-screw extruder. 45g of recycled PA6, 0.6g of H3344, 0.3g of UV234, 0.4g of S-EED, and 0.5g of E-wax are uniformly mixed and fed into the main feed. 20g of microencapsulated flame retardant is fed into the first side feed, and mixture A is fed into the second side feed. The feeding section maintains a temperature of 80-220℃, the melting section 235-245℃, and the die head section 210-230℃, with a rotation speed of 400 rpm.

[0091]

Example 3

[0092] 6g of microencapsulated flame retardant c, 27g of HS46, and 0.7g of E wax were placed in a mixer and mixed for 5 minutes at a temperature of 230℃ and a speed of 80 rpm to obtain mixture A.

[0093] The extrusion process employs a twin-screw extruder. 55g of recycled PA66, 0.6g of H3344, 0.4g of UV234, 0.4g of S-EED, and 0.4g of AC540A are uniformly mixed and fed into the main feed. 15g of microencapsulated flame retardant is fed into the first side feed, and mixture A is fed into the second side feed. The feeding section maintains a temperature of 80-220℃, the melting section 240-245℃, the die head section 220-250℃, and the rotation speed 260 rpm.

[0094]

Example 4

[0095] 12g of microencapsulated flame retardant d, 25g of HS65, and 1g of E wax were placed in a mixer and mixed for 3 minutes at a temperature of 245℃ and a speed of 30 rpm to obtain mixture A.

[0096] The process employs a twin-screw extruder. 50g of recycled PA66, 0.6g of H3344, 0.3g of UV234, 0.3g of S-EED, and 0.2g of AC540A are uniformly mixed and fed into the main feed. 4g of microencapsulated flame retardant is fed into the first side feed, and mixture A is fed into the second side feed. The feeding section maintains a temperature of 100-220℃, the melting section 220-245℃, the die head section 210-230℃, and the rotation speed is 250 rpm.

[0097]

Example 5

[0098] 6g of microencapsulated flame retardant e, 35g of HS65, and 0.6g of AC540A were placed in an internal mixer and mixed for 4 minutes at a temperature of 255℃ and a speed of 40 rpm to obtain mixture A.

[0099] The process employs a twin-screw extruder. 60g of recycled PA66, 0.6g of H3344, 0.3g of UV234, 0.3g of S-EED, and 0.5g of E-wax are uniformly mixed and fed into the main feed. 18g of microencapsulated flame retardant is fed into the first side feed, and mixture A is fed into the second side feed. The feeding section maintains a temperature of 80-220℃, the melting section 220-245℃, and the die head section 220-235℃, with a rotation speed of 350 rpm.

[0100]

Example 6

[0101] The twin-screw granulator is used. 60g of recycled PA66, 0.6g of H3344, 0.3g of UV234, 0.3g of S-EED, 0.5g of E-wax, and 0.6g of AC540A are added from the main feed. 24g of microencapsulated flame retardant e is added from the first side feed, and 35g of HS65 is added from the second side feed. The feeding section is at 80-220℃, the melting section at 220-245℃, and the die head section at 220-235℃, with a rotation speed of 350 rpm.

[0102] Comparative Example 1

[0103] The composite material was prepared using essentially the same method as in Example 2, except that the microencapsulated flame retardant b was replaced with microencapsulated flame retardant f.

[0104] Comparative Example 2

[0105] The composite material was prepared using essentially the same method as in Example 2, except that the microencapsulated flame retardant b was replaced with microencapsulated flame retardant g.

[0106] Comparative Example 3

[0107] The composite material was prepared using essentially the same method as in Example 2, except that the microencapsulated flame retardant b was replaced with unmicroencapsulated MPP and MP200. Specifically:

[0108] Place 1.7g MPP, 8.3g MP200, 40g HS46, and 0.5g E wax into a mixer, set the temperature to 260℃, and mix for 10 minutes at 100 rpm to obtain mixture A.

[0109] The twin-screw granulator is used. 45g of renewable PA1012, 0.6g of H3344, 0.3g of UV234, 0.4g of S-EED, and 0.5g of E-wax are uniformly mixed and added through the main feed. 3.3g of MPP and 16.7g of MP200 are added through the first side feed, and mixture A is added through the second side feed. The feeding section is at 80-220℃, the melting section at 235-245℃, and the die head section at 210-230℃, with a rotation speed of 400 rpm.

[0110] Comparative Example 4

[0111] The composite material was prepared using essentially the same method as in Example 2, except that the microencapsulated flame retardant b was replaced with MPP, specifically:

[0112] Place 10g MPP, 40g HS46, and 0.5g E wax into a mixer, set the temperature to 260℃, and mix for 10 minutes at 100 rpm to obtain mixture A.

[0113] The twin-screw granulator is used. 45g of renewable PA1012, 0.6g of H3344, 0.3g of UV234, 0.4g of S-EED, and 0.5g of E-wax are uniformly mixed and added through the main feed. 20g of MPP is added through the first side feed, and mixture A is added through the second side feed. The feeding section is at 80-220℃, the melting section at 235-245℃, and the die head section at 210-230℃, with a rotation speed of 400 rpm.

[0114] The nylon composite materials prepared in each embodiment and comparative example were subjected to the performance tests shown in Table 2, and the results are as follows:

[0115] Table 2. Performance Tests and Results of Nylon Composite Materials

[0116]

[0117] Comparing Comparative Examples 1 and 2 with Example 2, it can be seen that if MP200 is replaced with conventional silane coupling agents KH550 or POE-g-MAH, the flame retardant performance of the material is very poor. Especially after the addition of the elastomer, the oxygen index of the material decreases significantly due to increased flammability, and the smoke density increases. Furthermore, the density of the material increases due to severe breakage of the glass microspheres. In addition, the mechanical properties of the material decrease significantly. Comparing Comparative Example 3 with Example 2, it can be seen that if no flame retardant coating treatment is applied, and only MP200 and the flame retardant are added separately, the flame retardant performance of the material is slightly better than that of Comparative Examples 1 and 2 due to the introduction of silicon and the phosphorus-silicon synergy. However, the problems of poor mechanical properties and high density still exist due to the aforementioned reasons. Furthermore, the flame retardant is prone to precipitation during long-term storage. Comparative Example 4, with only the flame retardant added, shows even worse overall performance of the composite material. In addition, Example 6 differs slightly from Example 2 in its preparation process. The microencapsulated flame retardant was not blended with hollow glass microspheres, which does not offer advantages in material compatibility and cannot maximize the supporting effect of the hollow glass microspheres. As a result, the material performance is slightly worse and the density is slightly higher. However, compared with other comparative examples, it still has significant advantages, demonstrating the advanced nature of the composite material formulation of the present invention.

[0118] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A composite material for recycling waste nylon, characterized in that, It is made from the following components in parts by weight: S1, waste nylon, 45-70 pieces S2, microencapsulated flame retardant, 12-30 parts. S3, hollow glass microspheres, 20-40 parts S4, additives, 1-3 parts The microencapsulated flame retardant has a microencapsulated structure with the flame retardant as the core and the epoxy silane oligomer MP200 as the outer shell, wherein the mass ratio of the flame retardant to the epoxy silane oligomer MP200 is (0.2-5):

1. The preparation method of the microencapsulated flame retardant is as follows: A. Add flame retardant and emulsifier to the water-alcohol solution, adjust the pH to 8-11, and stir under heating conditions; B. Add MP200 to the above solution, react and then age to obtain a solid product; C. Wash the solid product with alcohol and dry it to obtain the microencapsulated flame retardant.

2. The composite material for recycling waste nylon according to claim 1, characterized in that, It is made from the following components in parts by weight: S1, waste nylon, 50-60 portions; S2, microencapsulated flame retardant, 16-24 parts; S3, hollow glass microspheres, 25-35 parts; S4, additives, 1.5-2.5 parts.

3. The composite material for recycling waste nylon according to claim 1, characterized in that, In the microencapsulated flame retardant, the mass ratio of the flame retardant to the epoxy silane oligomer MP200 is (0.3-3):

1.

4. The composite material for recycling waste nylon according to claim 1, characterized in that, The flame retardant is one or more of the following: red phosphorus, melamine pyrophosphate, aluminum diethylphosphite, magnesium hydroxide, and composite phosphorus-nitrogen flame retardants.

5. The composite material for recycling waste nylon according to claim 1, characterized in that, The waste nylon is selected from at least one of the long-chain nylons PA66, PA6, PA610, PA612, PA11, PA1010, and PA12.

6. The composite material for recycling waste nylon according to claim 5, characterized in that, The waste nylon is unfilled or has a filler content of less than 5% granular resin particles.

7. The composite material for recycling waste nylon according to claim 1, characterized in that, The density of the hollow glass microspheres is 0.2-0.8 g / cm³. 3 The compressive strength is 20-210 MPa.

8. The composite material for recycling waste nylon according to claim 7, characterized in that, The density of the hollow glass microspheres is 0.4-0.65 g / cm³. 3 The compressive strength is 60-200MPa.

9. The composite material for recycling waste nylon according to any one of claims 1-8, characterized in that, The additive is any one or more of heat stabilizers, light stabilizers, and lubricants.

10. The composite material for recycling waste nylon according to claim 9, characterized in that, The heat stabilizer is one or more of the following: copper salt antioxidants, phosphate antioxidants, hindered phenolic antioxidants, phosphite antioxidants, thioester antioxidants, and polymeric antioxidants.

11. The composite material for recycling waste nylon according to claim 10, characterized in that, The heat stabilizer is a copper salt antioxidant.

12. The composite material for recycling waste nylon according to claim 11, characterized in that, The heat stabilizer is one or more of H320, H324, H1607, H3336, H3376, H3344, S5050, S5070, and AO-K.

13. The composite material for recycling waste nylon according to claim 9, characterized in that, The light stabilizer is one or more of the following: salicylates, substituted acrylonitriles, triazines, benzotriazoles, xylene ketones, and amine stabilizers.

14. The composite material for recycling waste nylon according to claim 13, characterized in that, The light stabilizer is one or more of UV234, UV360, TFB117, and H2002.

15. The composite material for recycling waste nylon according to claim 9, characterized in that, The lubricant is one or more of the following: olefins, esters, stearates, and stearates.

16. A method for preparing a composite material from recycled waste nylon as described in any one of claims 1-15, characterized in that, Includes the following steps: 1) Mix a portion of the microencapsulated flame retardant, hollow glass microspheres, and optionally a lubricant in a mixer to obtain mixture A; 2) Add waste nylon granules, optional geothermal stabilizer, light stabilizer and lubricant from the main feed port of the twin-screw extruder; add the remaining microencapsulated flame retardant from the first side feed port; add mixture A from the second side feed port; extrude and granulate to obtain the composite material.

17. The method for preparing a composite material from recycled waste nylon according to claim 16, characterized in that, The mixing conditions in step 1) of the internal mixer are: temperature 210-260℃, speed 20-100rpm, and mixing time 2-10min; The extrusion conditions of the twin-screw extruder in step 2) are: feeding section 80-220℃, melting section 220-255℃, die head section 210-250℃; screw speed 200-400rpm.

18. The method for preparing a composite material from recycled waste nylon according to claim 17, characterized in that, The mixing conditions in step 1) are: temperature 245-255℃, speed 30-40rpm, and mixing time 3-4min.

19. The method for preparing a composite material from recycled waste nylon according to claim 17, characterized in that, In step 2), the screw speed of the twin-screw extruder is 250-350 rpm.

20. The method for preparing a composite material from recycled waste nylon according to claim 17, characterized in that, In step 1), the amount of microencapsulated flame retardant added accounts for 25-75% of its total mass.

21. The method for preparing a composite material from recycled waste nylon according to claim 16, characterized in that, In the preparation method of the microencapsulated flame retardant, step A is as follows: adding the flame retardant and emulsifier to the aqueous alcohol solution, adjusting the pH to 9-10, and stirring under heating conditions.

22. The method for preparing a composite material from recycled waste nylon according to claim 16, characterized in that, The emulsifier is one or more of organosilicon, alkyl salt, and ether, and the amount of emulsifier used is 0.5-2% of the total mass of flame retardant and MP200.

23. The method for preparing a composite material from recycled waste nylon according to claim 22, characterized in that, In step A, the heating temperature is 35-65℃ and the stirring time is 20-60 min; in step B, the reaction time is 3-6 h and the aging time after the reaction is 6-30 h.

24. The method for preparing a composite material from recycled waste nylon according to claim 23, characterized in that, In step A, the heating temperature is 40-50℃ and the stirring time is 30-40 min; in step B, the reaction time is 4-5 h and the aging time after the reaction is 12-18 h.

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