A halogen-free flame-retardant glass fiber modified polypropylene material and preparation method thereof

Abstract

This invention relates to the field of flame retardant materials technology, and more particularly to a halogen-free flame retardant glass fiber modified polypropylene material and its preparation method. The material, by weight, comprises the following components: 60-80 parts polypropylene, 15-30 parts long glass fibers, 8-15 parts halogen-free intumescent flame retardant, 2-5 parts synergist, 3-8 parts compatibilizer, 2-3 parts interface modifier, 2-4 parts dynamic crosslinking agent, and 1-3 parts functional additives. The halogen-free flame retardant glass fiber modified polypropylene material and its preparation method involve compounding the intumescent halogen-free flame retardant melamine polyphosphate with mechanical montmorillonite, nano-zinc borate, and MXene. Through a synergistic effect, the flame retardant efficiency is improved, and the release of smoke and toxic gases during combustion is suppressed, resulting in a good flame retardant effect for the halogen-free flame retardant glass fiber modified polypropylene material. Furthermore, by introducing maleic anhydride-grafted polypropylene as a compatibilizer, the surface of the long glass fibers is modified, enhancing the interfacial bonding between the long glass fibers and the matrix.

Description

Technical Field

[0001] This invention relates to the field of flame retardant materials technology, specifically to a halogen-free flame retardant glass fiber modified polypropylene material and its preparation method. Background Technology

[0002] Polypropylene, or PP for short, is a semi-crystalline thermoplastic polymer made from propylene monomers through an addition polymerization reaction. It is usually a white, waxy solid, non-toxic, odorless, transparent in appearance, and lightweight. Fiber-reinforced plastic is currently one of the most widely used polymer-based composite materials. Long glass fiber reinforced polypropylene (PP / LGF) prepared by melt impregnation technology has advantages such as high strength, low density, good low-temperature toughness, good heat resistance, and low molding shrinkage.

[0003] However, PP / LGF composite materials are now more flammable than pure PP. Once ignited in air, they easily produce flaming drips during combustion, which spreads the flame very easily. This limits their application in electronic, electrical, transportation, and office automation products. At the same time, with the increasing attention of modern society to green environmental protection and human health, halogen flame retardants, which have high flame retardant efficiency but produce a lot of smoke and toxic gases during combustion, will gradually be replaced by halogen-free flame retardants. However, halogen-free flame retardants generally have the defects of low flame retardant efficiency and low heat resistance. Summary of the Invention

[0004] The purpose of this invention is to provide a halogen-free flame-retardant glass fiber modified polypropylene material and its preparation method, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the first aspect of the present invention provides a halogen-free flame-retardant glass fiber modified polypropylene material, wherein the material comprises the following components by weight: 60-80 parts of polypropylene, 15-30 parts of long glass fiber, 8-15 parts of halogen-free intumescent flame retardant, 2-5 parts of synergist, 3-8 parts of compatibilizer, 2-3 parts of interface modifier, 2-4 parts of dynamic crosslinking agent, and 1-3 parts of functional additive.

[0006] The retained length of the long glass fiber is 2-40 mm, and it is distributed in a gradient in the matrix. The halogen-free intumescent flame retardant is melamine polyphosphate and graphite, with an amount of 10-25 wt%. The synergist is organomontmorillonite, nano zinc borate, and MXene, with an amount of 1-8 wt%. MXene is a two-dimensional nanomaterial composed of transition metal carbides and nitrides. The compatibilizer is polypropylene grafted with maleic anhydride, with an amount of 1-5 wt%. The interface modifier is furanylsilane, with an amount of 0.5-3 wt%. The dynamic crosslinking agent is bismaleimide, with an amount of 2-5 wt%. The functional additive is nano metal powder and core-shell microcapsules, with an amount of 1-3 wt%.

[0007] The second aspect of this invention provides a method for preparing a halogen-free flame-retardant glass fiber modified polypropylene material, applicable to the aforementioned halogen-free flame-retardant glass fiber modified polypropylene material, comprising the following preparation steps:

[0008] A1. Select raw materials: polypropylene, long glass fiber, halogen-free intumescent flame retardant, synergist, compatibilizer, interface modifier, dynamic crosslinking agent and functional additive. Then prepare a co-rotating twin-screw extruder and a pelletizer. The co-rotating twin-screw extruder has five zones, which are divided according to temperature. The specific zone temperatures are 180℃→200℃→220℃→210℃→200℃.

[0009] A2. Prepare a 5 wt% ethanol solution, then add furanylsilane to the ethanol solution and stir to mix. After mixing, add long glass fibers, and then treat with an ultrasonic cleaner and dry in an oven to allow the interface modifier to chemically bond to the surface of the long glass fibers.

[0010] A3. Polypropylene, compatibilizer and dynamic crosslinking agent are premixed to form a premixed raw material. The premixed raw material is then added to the co-rotating twin-screw extruder from the main feed port. The co-rotating twin-screw extruder then conveys the premixed raw material toward the discharge port. During the conveying of the premixed raw material, functional additives, halogen-free intumescent flame retardants, synergists and long glass fibers are added from the side feed port of the co-rotating twin-screw extruder.

[0011] A4. Then, the raw materials are continuously heated and melted by a co-rotating twin-screw extruder. After the raw materials are fused, the co-rotating twin-screw extruder extrudes the fused raw materials from the discharge port. The pelletizer is started to cut and granulate the raw materials at the discharge port of the co-rotating twin-screw extruder to obtain unshaped masterbatch. The unshaped masterbatch after pelleting is collected and put into a dryer for drying. After drying, the flame retardant masterbatch is obtained.

[0012] In a further embodiment, the core-shell microcapsules are prepared as follows:

[0013] A301. Prepare styrene monomer, butyl acrylate comonomer, potassium persulfate and halogen-free intumescent flame retardant. Then disperse the halogen-free intumescent flame retardant in deionized water and add it to styrene and butyl acrylate for mixing.

[0014] A302. Potassium persulfate is added as an initiator to a mixture of halogen-free intumescent flame retardant, styrene, and butyl acrylate, and heated to form APP microcapsules encapsulated in a polystyrene-b-polyacrylate shell. The APP microcapsules are then separated and dried by centrifugation to obtain core-shell microcapsules.

[0015] In a further embodiment, the mass ratio of styrene to butyl acrylate is 1:1, the purity of potassium persulfate is 0.5 wt%, the heating reaction temperature of the mixture of potassium persulfate, halogen-free intumescent flame retardant, styrene, and butyl acrylate is 70-80°C, the reaction time is 4-6 h, the particle size of the core-shell microcapsules is 1-10 μm, and the centrifugation drying time of the APP microcapsules is 10-12 h, the centrifugation speed is 1200 rpm, and the centrifugation temperature is 50-60°C.

[0016] In a further embodiment, the preparation method of the nano-metal powder is as follows:

[0017] A311. Prepare ZIF-8 nanoparticles and anhydrous ethanol. Then pour the ZIF-8 nanoparticles into the anhydrous ethanol and mix. Transfer the mixture to an ultrasonic disperser and start ultrasonic dispersion.

[0018] A312. The dispersion is transferred from the ultrasonic disperser to a spray dryer, and then the dispersion is sprayed out by the spray dryer to obtain ZIF-8 nano metal powder.

[0019] In a further embodiment, the mass ratio of the ZIF-8 nanoparticles to anhydrous ethanol is 1:10, the ultrasonic dispersion temperature of the ultrasonic disperser is 30-40°C, the internal temperature of the spray dryer is 180°C, and the outlet temperature of the spray dryer is 80°C.

[0020] In a further embodiment, the solution of furanylsilane and ethanol is ultrasonically treated with long glass fibers in an ultrasonic cleaner for 30 min to 2 h, with an ultrasonic power of 200 W and a frequency of 40 kHz. The drying temperature of the oven is 80-10 °C and the drying time is 2-3 h.

[0021] In a further embodiment, the screw speed of the co-rotating twin-screw extruder is 300 rpm, and the feeding speed of the co-rotating twin-screw extruder is 10 kg / h.

[0022] In a further embodiment, the post-processing preparation steps of the flame retardant masterbatch are as follows:

[0023] B1. The finished flame retardant masterbatch and polypropylene are mixed in a mass ratio of 7:3 to obtain mixed injection granules. Then, the mixed injection granules are heated and injected. The mold tank of the injection molding equipment is the same as that of the flame retardant masterbatch. The heating injection process is a two-stage injection. The first stage injection is set at a temperature of 290℃ to inject the outer layer, which causes the core-shell microcapsules to rupture and release APP, quickly forming a dense carbon layer. Then, the second stage injection is at a temperature of 230℃ to inject the core layer, retaining the glass fiber length and dynamic cross-linked network structure.

[0024] B2. After injection molding, the post-processed flame retardant masterbatch is removed from the injection molding machine and then cooled to obtain the treated flame retardant masterbatch. Subsequently, the cooled flame retardant masterbatch is placed in a thermo-oxygen aging chamber. The aging chamber is set at a temperature of 120℃, an oxygen concentration of 50%, and an aging time of 24 hours. After the aging process is completed, the aging chamber is heated to 150℃ and maintained for 2 hours to activate the dynamic covalent bonds between bismaleimide and furan groups, forming a self-healing network, and obtaining the final finished flame retardant masterbatch.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. This invention uses an intumescent halogen-free flame retardant, melamine polyphosphate (APP), compounded with mechanical montmorillonite, nano zinc borate, and MXene. Through a synergistic effect, it improves flame retardant efficiency, inhibits the release of smoke and toxic gases during combustion, and utilizes the two-dimensional layered structure of MXene to form a dense barrier during combustion, effectively hindering the diffusion of oxygen and heat, and slowing down the combustion process. This results in halogen-free flame retardant glass fiber modified polypropylene material with good flame retardant effect and better material quality.

[0027] 2. In this invention, maleic anhydride-grafted polypropylene is introduced as a compatibilizer to modify the surface of long glass fibers, enhance the interfacial bonding force between the long glass fibers and the matrix, delay the interfacial debonding caused by thermo-oxidative aging, and thus improve the surface strength of halogen-free flame-retardant glass fiber modified polypropylene materials.

[0028] 3. This invention, by controlling the injection molding temperature gradient, with the outer layer temperature 20-60℃ higher than the core layer, enables the glass fiber to form a gradient distribution structure in the matrix, thereby improving the overall resistance of the material to thermo-oxidative aging. At the same time, by combining ultrathin slicing and surface energy dispersive spectroscopy (EDS) analysis technology, the flame retardant is uniformly dispersed in the matrix, inhibiting the migration and enrichment during the aging process, and improving the flame retardant effect of halogen-free flame-retardant glass fiber modified polypropylene material. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1

[0031] A halogen-free flame-retardant glass fiber modified polypropylene material and its preparation method are disclosed. The halogen-free flame-retardant glass fiber modified polypropylene material contains the following components by weight: 60-80 parts of polypropylene, 15-30 parts of long glass fiber, 8-15 parts of halogen-free intumescent flame retardant, 2-5 parts of synergist, and 3-8 parts of compatibilizer.

[0032] Formulation: Polypropylene: 50%, Long glass fiber: 20%, Halogen-free intumescent flame retardant: 15% (melamine polyphosphate), Synergist: 10%, Compatibilizer: 5%;

[0033] The preparation steps include the following:

[0034] A1. Select raw materials: polypropylene, long glass fiber, halogen-free intumescent flame retardant, synergist and compatibilizer. Then prepare a co-rotating twin-screw extruder and a pelletizer. The co-rotating twin-screw extruder has five zones, which are divided according to temperature. The specific zone temperatures are 180℃→200℃→220℃→210℃→200℃.

[0035] A2. Polypropylene and compatibilizer are premixed to form a premixed raw material. The premixed raw material is then added to the co-rotating twin-screw extruder from the main feed port. The co-rotating twin-screw extruder then conveys the premixed raw material toward the discharge port. During the conveying of the premixed raw material, halogen-free intumescent flame retardant, synergist and long glass fiber are added from the side feed port of the co-rotating twin-screw extruder.

[0036] A3. Then, the raw materials are continuously heated and melted by a co-rotating twin-screw extruder. After the raw materials are fused, the co-rotating twin-screw extruder extrudes the fused raw materials from the discharge port. The pelletizer is started to cut and granulate the raw materials at the discharge port of the co-rotating twin-screw extruder to obtain unshaped masterbatch. The unshaped masterbatch after pelleting is collected and put into a dryer for drying. After drying, the flame retardant masterbatch is obtained.

[0037] Example 2

[0038] A halogen-free flame-retardant glass fiber modified polypropylene material, characterized in that the material comprises the following components by weight: 60-80 parts of polypropylene, 15-30 parts of long glass fiber, 8-15 parts of halogen-free intumescent flame retardant, 2-5 parts of synergist, 3-8 parts of compatibilizer and 1-3 parts of functional additive.

[0039] Formulation: Polypropylene: 50%, Long glass fiber: 20%, Halogen-free intumescent flame retardant: 15% (melamine polyphosphate), Synergist: 6%, Compatibilizer: 5%, and Functional additive: 4% (core-shell microcapsules);

[0040] The preparation steps include the following:

[0041] A1. Select raw materials: polypropylene, long glass fiber, halogen-free intumescent flame retardant, synergist, compatibilizer and functional additives. Then prepare a co-rotating twin-screw extruder and a pelletizer. The co-rotating twin-screw extruder has five zones, which are divided according to temperature. The specific zone temperatures are 180℃→200℃→220℃→210℃→200℃.

[0042] A2. Polypropylene and compatibilizer are premixed to form a premixed raw material. The premixed raw material is then added to the co-rotating twin-screw extruder from the main feed port. The co-rotating twin-screw extruder then conveys the premixed raw material toward the discharge port. During the conveying of the premixed raw material, functional additives, halogen-free intumescent flame retardants, synergists and long glass fibers are added from the side feed port of the co-rotating twin-screw extruder.

[0043] A3. Then, the raw materials are continuously heated and melted by a co-rotating twin-screw extruder. After the raw materials are fused, the co-rotating twin-screw extruder extrudes the fused raw materials from the discharge port. The pelletizer is started to cut and granulate the raw materials at the discharge port of the co-rotating twin-screw extruder to obtain unshaped masterbatch. The unshaped masterbatch after pelleting is collected and put into a dryer for drying. After drying, the flame retardant masterbatch is obtained.

[0044] Example 3

[0045] A halogen-free flame-retardant glass fiber modified polypropylene material, characterized in that the material comprises the following components by weight: 60-80 parts polypropylene, 15-30 parts long glass fiber, 8-15 parts halogen-free intumescent flame retardant, 2-5 parts synergist, 3-8 parts compatibilizer, 2-4 parts dynamic crosslinking agent, and 1-3 parts functional additive.

[0046] Formulation: Polypropylene: 55%, Long glass fiber: 18%, Halogen-free intumescent flame retardant: 12% (melamine polyphosphate), Synergist: 5%, Compatibilizer: 4%, Functional additives: 3% (nano-metal powder), and Dynamic crosslinking agent: 3%;

[0047] The preparation steps include the following:

[0048] A1. Select raw materials: polypropylene, long glass fiber, halogen-free intumescent flame retardant, synergist, compatibilizer and functional additives. Then prepare a co-rotating twin-screw extruder and a pelletizer. The co-rotating twin-screw extruder has five zones, which are divided according to temperature. The specific zone temperatures are 180℃→200℃→220℃→210℃→200℃.

[0049] A2. Polypropylene, compatibilizer and dynamic crosslinking agent are premixed to form a premixed raw material. The premixed raw material is then added to the co-rotating twin-screw extruder from the main feed port. The co-rotating twin-screw extruder then conveys the premixed raw material toward the discharge port. During the conveying of the premixed raw material, functional additives, halogen-free intumescent flame retardant, synergist and long glass fiber are added from the side feed port of the co-rotating twin-screw extruder.

[0050] A3. Then, the raw materials are continuously heated and melted by a co-rotating twin-screw extruder. After the raw materials are fused, the co-rotating twin-screw extruder extrudes the fused raw materials from the discharge port. The pelletizer is started to cut and granulate the raw materials at the discharge port of the co-rotating twin-screw extruder to obtain unshaped masterbatch. The unshaped masterbatch after pelleting is collected and put into a dryer for drying. After drying, the flame retardant masterbatch is obtained.

[0051] Example 4

[0052] A halogen-free flame-retardant glass fiber modified polypropylene material, characterized in that the material comprises the following components by weight: 60-80 parts of polypropylene, 15-30 parts of long glass fiber, 8-15 parts of halogen-free intumescent flame retardant, 2-5 parts of synergist, 3-8 parts of compatibilizer and 1-3 parts of functional additive.

[0053] Formulation: Polypropylene: 55%, Long glass fiber: 18%, Halogen-free intumescent flame retardant: 12% (graphite), Synergist: 5%, Compatibilizer: 4%, Functional additives: 3% (nano-metal powder), and Dynamic crosslinking agent: 3%;

[0054] The preparation steps include the following:

[0055] A1. Select raw materials: polypropylene, long glass fiber, halogen-free intumescent flame retardant, synergist, compatibilizer and functional additives. Then prepare a co-rotating twin-screw extruder and a pelletizer. The co-rotating twin-screw extruder has five zones, which are divided according to temperature. The specific zone temperatures are 180℃→200℃→220℃→210℃→200℃.

[0056] A2. Polypropylene, compatibilizer and dynamic crosslinking agent are premixed to form a premixed raw material. The premixed raw material is then added to the co-rotating twin-screw extruder from the main feed port. The co-rotating twin-screw extruder then conveys the premixed raw material toward the discharge port. During the conveying of the premixed raw material, functional additives, halogen-free intumescent flame retardant, synergist and long glass fiber are added from the side feed port of the co-rotating twin-screw extruder.

[0057] A3. Then, the raw materials are continuously heated and melted by a co-rotating twin-screw extruder. After the raw materials are fused, the co-rotating twin-screw extruder extrudes the fused raw materials from the discharge port. The pelletizer is started to cut and granulate the raw materials at the discharge port of the co-rotating twin-screw extruder to obtain unshaped masterbatch. The unshaped masterbatch after pelleting is collected and put into a dryer for drying. After drying, the flame retardant masterbatch is obtained.

[0058] Example 5

[0059] A halogen-free flame-retardant glass fiber modified polypropylene material, characterized in that the material comprises the following components by weight: 60-80 parts polypropylene, 15-30 parts long glass fiber, 8-15 parts halogen-free intumescent flame retardant, 2-5 parts synergist, 3-8 parts compatibilizer, 2-3 parts interface modifier, and 1-3 parts functional additive.

[0060] Formulation: Polypropylene: 45%, Long glass fiber: 20%, Halogen-free intumescent flame retardant: 10% (melamine polyphosphate and graphite), Synergist: 10%, Compatibilizer: 5%, Functional additives: 5% (nano-metal powder and core-shell microcapsules), Dynamic crosslinking agent: 3%, and Interface modifier: 2%.

[0061] The preparation steps include the following:

[0062] A1. Select raw materials: polypropylene, long glass fiber, halogen-free intumescent flame retardant, synergist, compatibilizer, interface modifier, dynamic crosslinking agent and functional additive. Then prepare a co-rotating twin-screw extruder and a pelletizer. The co-rotating twin-screw extruder has five zones, which are divided according to temperature. The specific zone temperatures are 180℃→200℃→220℃→210℃→200℃.

[0063] A2. Prepare a 5wt% ethanol solution, then add the interface modifier to the ethanol solution and stir to mix. After mixing, add long glass fibers, and then perform ultrasonic treatment in an ultrasonic cleaner and drying in an oven to allow the interface modifier to chemically bond to the surface of the long glass fibers.

[0064] A3. Polypropylene, compatibilizer and dynamic crosslinking agent are premixed to form a premixed raw material. The premixed raw material is then added to the co-rotating twin-screw extruder from the main feed port. The co-rotating twin-screw extruder then conveys the premixed raw material toward the discharge port. During the conveying of the premixed raw material, functional additives, halogen-free intumescent flame retardants, synergists and long glass fibers are added from the side feed port of the co-rotating twin-screw extruder.

[0065] A4. Then, the raw materials are continuously heated and melted by a co-rotating twin-screw extruder. After the raw materials are fused, the co-rotating twin-screw extruder extrudes the fused raw materials from the discharge port. The pelletizer is started to cut and granulate the raw materials at the discharge port of the co-rotating twin-screw extruder to obtain unshaped masterbatch. The unshaped masterbatch after pelleting is collected and put into a dryer for drying. After drying, the flame retardant masterbatch is obtained.

[0066] Comparative Example

[0067] The preparation methods for existing traditional halogen-free flame-retardant polypropylene materials will not be elaborated here.

[0068] The following performance tests were performed on the aforementioned polypropylene material:

[0069] Flame retardancy (LOI, UL-94, PHRR), mechanical properties (tensile strength, impact strength retention rate), and environmental friendliness (smoke density).

[0070] Table 1 shows the performance test results of polypropylene materials:

[0071]

[0072]

[0073] The conclusions are drawn from the analysis of the performance test data in Table 1.

[0074] Flame retardant performance: Example 5 showed the best performance, with an LOI of 33% and a PHRR reduction of 55%, while the comparative example, due to the lack of gradient distribution and core-shell flame retardant, had a PHRR as high as 300 kW / m. 2 Mechanical properties: Example 3 significantly improved tensile and impact retention rates (≥90%), while the comparative example had the lowest retention rate due to interface degradation. Environmental performance: Example 4 reduced smoke density to 120, and Example 5 further optimized it to 100. The comparative example exceeded the standards for both CO yield and smoke density.

[0075] Therefore, through the synergistic effect of dynamic interface, core-shell flame retardant and nano metal powder catalysis, Example 5 has the best overall performance, is suitable for the production of different high-end injection molded products, has good flame retardancy, and does not produce a large amount of smoke and toxic gas in high-temperature combustion environments.

[0076] Table 2 shows the combustion behavior of halogen-free intumescent flame retardant / long glass fiber reinforced polypropylene composites under different thermo-oxidative aging times:

[0077] Aging time (days) 0 10 30 50 Thermal ignition time / s 32 33 35 37 <![CDATA[Peak heat release rate / (kWm 2 )]]> 197.2 178.3 153.8 122.5 <![CDATA[Average heat release rate / (kWm 2 )]]> 110.2 93.1 78.9 81.6 <![CDATA[Total heat release / (MJm 2 )]]> 136.1 125.8 117.2 105.7 Average carbon monoxide yield (kg / kg) 0.0305 0.0287 0.0268 0.0245 Average carbon dioxide yield (kg / kg) 2.14 1.95 1.79 1.68 UL-94 flame retardant rating V-0 V-0 V-0 V-0

[0078] Table 3 shows the combustion behavior of traditional halogen-free flame-retardant polypropylene materials under different thermo-oxidative aging times:

[0079]

[0080]

[0081] Referring to Table 2: Glass fiber modified polypropylene materials can maintain a relatively stable state for a long time after thermo-oxidative aging, which is attributed to the thermal stability and anti-permeation properties of the halogen-free intumescent flame retardant, as well as the small impact of thermo-oxidative aging on the thermal stability of the composite material.

[0082] Referring to Table 3: After artificial intervention and aging, the flame retardant performance of traditional halogen-free flame-retardant polypropylene materials shows a significant decrease. Therefore, by adding halogen-free intumescent flame retardants to compare the flame retardant performance of traditional halogen-free flame-retardant polypropylene materials, the flame retardant effect of polypropylene composites can be effectively improved.

[0083] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A halogen-free flame-retardant glass fiber modified polypropylene material, characterized in that, The material comprises the following components by weight: 60-80 parts polypropylene, 15-30 parts long glass fiber, 8-15 parts halogen-free intumescent flame retardant, 2-5 parts synergist, 3-8 parts compatibilizer, 2-3 parts interface modifier, 2-4 parts dynamic crosslinking agent, and 1-3 parts functional additive. The retained length of the long glass fiber is 2-40 mm, and it is distributed in a gradient in the matrix. The halogen-free intumescent flame retardant is melamine polyphosphate and graphite, with an amount of 10-25 wt%. The synergist is organomontmorillonite, nano zinc borate, and MXene, with an amount of 1-8 wt%. MXene is a two-dimensional nanomaterial composed of transition metal carbides and nitrides. The compatibilizer is polypropylene grafted with maleic anhydride, with an amount of 1-5 wt%. The interface modifier is furanylsilane, with an amount of 0.5-3 wt%. The dynamic crosslinking agent is bismaleimide, with an amount of 2-5 wt%. The functional additive is nano metal powder and core-shell microcapsules, with an amount of 1-3 wt%.

2. A method for preparing a halogen-free flame-retardant glass fiber modified polypropylene material, applied to the halogen-free flame-retardant glass fiber modified polypropylene material according to claim 1, characterized in that, The preparation steps include the following: A1. Select raw materials: polypropylene, long glass fiber, halogen-free intumescent flame retardant, synergist, compatibilizer, interface modifier, dynamic crosslinking agent and functional additive. Then prepare a co-rotating twin-screw extruder and a pelletizer. The co-rotating twin-screw extruder has five zones, which are divided according to temperature. The specific zone temperatures are 180℃→200℃→220℃→210℃→200℃. A2. Prepare a 5wt% ethanol solution, then add the interface modifier to the ethanol solution and stir to mix. After mixing, add long glass fibers, and then perform ultrasonic treatment in an ultrasonic cleaner and drying in an oven to allow the interface modifier to chemically bond to the surface of the long glass fibers. A3. Polypropylene, compatibilizer and dynamic crosslinking agent are premixed to form a premixed raw material. The premixed raw material is then added to the co-rotating twin-screw extruder from the main feed port. The co-rotating twin-screw extruder then conveys the premixed raw material toward the discharge port. During the conveying of the premixed raw material, functional additives, halogen-free intumescent flame retardants, synergists and long glass fibers are added from the side feed port of the co-rotating twin-screw extruder. A4. Then, the raw materials are continuously heated and melted by a co-rotating twin-screw extruder. After the raw materials are fused, the co-rotating twin-screw extruder extrudes the fused raw materials from the discharge port. The pelletizer is started to cut and granulate the raw materials at the discharge port of the co-rotating twin-screw extruder to obtain unshaped masterbatch. The unshaped masterbatch after pelleting is collected and put into a dryer for drying. After drying, the flame retardant masterbatch is obtained.

3. The method for preparing a halogen-free flame-retardant glass fiber modified polypropylene material according to claim 2, characterized in that, The preparation method of the core-shell microcapsules is as follows: A301. Prepare styrene monomer, butyl acrylate comonomer, potassium persulfate and halogen-free intumescent flame retardant. Then disperse the halogen-free intumescent flame retardant in deionized water and add it to styrene and butyl acrylate for mixing. A302. Potassium persulfate is added as an initiator to a mixture of halogen-free intumescent flame retardant, styrene, and butyl acrylate, and heated to form APP microcapsules encapsulated in a polystyrene-b-polyacrylate shell. The APP microcapsules are then separated and dried by centrifugation to obtain core-shell microcapsules.

4. The method for preparing a halogen-free flame-retardant glass fiber modified polypropylene material according to claim 3, characterized in that, The mass ratio of styrene to butyl acrylate is 1:1, the purity of potassium persulfate is 0.5 wt%, the heating reaction temperature of the mixture of potassium persulfate, halogen-free intumescent flame retardant, styrene, and butyl acrylate is 70-80℃, and the reaction time is 4-6 h, the particle size of the core-shell microcapsules is 1-10 μm, and the centrifugation and drying time of the APP microcapsules is 10-12 h, the centrifugation speed is 1200 rpm, and the centrifugation temperature is 50-60℃.

5. The method for preparing a halogen-free flame-retardant glass fiber modified polypropylene material according to claim 2, characterized in that, The preparation method of the nano-metal powder is as follows: A311. Prepare ZIF-8 nanoparticles and anhydrous ethanol. Then pour the ZIF-8 nanoparticles into the anhydrous ethanol and mix. Transfer the mixture to an ultrasonic disperser and start ultrasonic dispersion. A312. The dispersion is transferred from the ultrasonic disperser to a spray dryer, and then the dispersion is sprayed out by the spray dryer to obtain ZIF-8 nano metal powder.

6. The method for preparing a halogen-free flame-retardant glass fiber modified polypropylene material according to claim 5, characterized in that, The ZIF-8 nanoparticles and anhydrous ethanol are mixed in a mass ratio of 1:

10. The ultrasonic dispersion temperature of the ultrasonic disperser is 30-40℃. The internal temperature of the spray dryer is 180℃. The outlet temperature of the spray dryer is 80℃.

7. The method for preparing a halogen-free flame-retardant glass fiber modified polypropylene material according to claim 2, characterized in that, The solution of furanylsilane and ethanol is subjected to ultrasonic treatment of long glass fibers in an ultrasonic cleaner for 30 min to 2 h, with an ultrasonic power of 200 W and a frequency of 40 kHz. The drying temperature of the oven is 80-10℃ and the drying time is 2-3 h.

8. The method for preparing a halogen-free flame-retardant glass fiber modified polypropylene material according to claim 2, characterized in that, The screw speed of the co-rotating twin-screw extruder is 300 rpm, and the feeding speed of the co-rotating twin-screw extruder is 10 kg / h.

9. The method for preparing a halogen-free flame-retardant glass fiber modified polypropylene material according to claim 2, characterized in that, The post-processing preparation steps of the flame retardant masterbatch are as follows: B1. The finished flame retardant masterbatch and polypropylene are mixed in a mass ratio of 7:3 to obtain mixed injection granules. Then, the mixed injection granules are heated and injected. The mold tank of the injection molding equipment is the same as that of the flame retardant masterbatch. The heating injection process is a two-stage injection. The first stage injection is set at a temperature of 290℃ to inject the outer layer, which causes the core-shell microcapsules to rupture and release APP, quickly forming a dense carbon layer. Then, the second stage injection is at a temperature of 230℃ to inject the core layer, retaining the glass fiber length and dynamic cross-linked network structure. B2. After injection molding, the post-processed flame retardant masterbatch is removed from the injection molding machine and then cooled to obtain the treated flame retardant masterbatch. Subsequently, the cooled flame retardant masterbatch is placed in a thermo-oxygen aging chamber. The aging chamber is set at a temperature of 120℃, an oxygen concentration of 50%, and an aging time of 24 hours. After the aging process is completed, the aging chamber is heated to 150℃ and maintained for 2 hours to activate the dynamic covalent bonds between bismaleimide and furan groups, forming a self-healing network, and obtaining the final finished flame retardant masterbatch.

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