Wear-resistant and battery-shielding PC / ABS composite material and preparation method thereof

Abstract

The invention relates to the technical field of organic materials, and discloses a wear-resistant and battery-shielding PC / ABS (polycarbonate / acrylonitrile butadiene styrene) composite material and a preparation method of the wear-resistant and battery-shielding PC / ABS composite material. The micron-sized metal powder is coated with polar silicone, and the mass percentage content of the micron-sized metal powder coated with the polar silicone is 2%-15%; a compatilizer, wherein the mass percentage content of the compatilizer is 0.5%-5%; a wear-resistant auxiliary agent, wherein the mass percentage content of the wear-resistant auxiliary agent is 0.1%-3%; the balance is one or more of an antioxidant, a heat stabilizer and a processing lubricant; wherein the mass ratio of PC to ABS in the PC / ABS resin base material is (3: 7)-(7: 3); and the polar silicone forms a coating layer on the surface of the metal powder. According to the invention, the wear-resistant and electromagnetic shielding requirements of the battery structural member can be met, and excellent mechanical properties and thermal deformation temperature can be maintained at the same time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic materials, in particular, relates to a PC / ABS composite material with wear resistance and battery shielding and a preparation method thereof. BACKGROUND

[0002] PC / ABS alloy materials are widely used in the fields of automotive interior and exterior, electronic and electrical shell and power battery related structural parts, etc. due to the heat resistance, dimensional stability of polycarbonate and the processing fluidity, impact resistance of acrylonitrile-butadiene-styrene copolymer. With the development of new energy power battery system towards high energy density and high integration, the battery pack shell, module end plate, connecting bracket and surrounding protective parts need not only to meet the requirements of heat resistance, flame retardance, mechanical support and long-term reliability, but also to face the electromagnetic interference problem caused by the high-frequency switching of electric drive system, battery management system and wire harness coupling. Therefore, the electromagnetic shielding ability of the material becomes one of the important performance indicators. At the same time, the above-mentioned parts often exist in the working conditions of sliding friction, plug-in wear, vibration impact and the like during assembly and use, so that the wear resistance, scratch resistance and surface stability of the material also become key requirements.

[0003] In the prior art, in order to improve the electromagnetic shielding performance of PC / ABS material, the method of introducing conductive fillers such as metal powder, metal fiber, carbon-based conductive materials (carbon black, graphite, carbon nanotube, etc.) or conductive coating / plating scheme into the resin matrix is usually adopted. However, high-density conductive fillers such as metal powder are prone to agglomeration and sedimentation in the PC / ABS system, which leads to discontinuity of the conductive network, fluctuation of shielding efficiency, and local stress concentration which reduces impact toughness and elongation. At the same time, the interface compatibility between metal fillers and PC / ABS matrix is insufficient, which easily forms interface defects, so that micro-cracks occur in the product under the conditions of thermal cycling or vibration, affecting the long-term reliability. On the other hand, in order to improve the wear resistance and scratch resistance, the existing schemes mostly use PTFE micro powder, silicone lubricating master batch, ultra-high molecular weight polyethylene micro powder or inorganic solid lubricant, etc. However, when such additives are used together with conductive fillers, the stability of the conductive network is easily weakened due to the migration of lubricating phase and the enhancement of interface slip, resulting in the attenuation of shielding performance. Moreover, it is difficult to disperse the wear-resistant additives and metal fillers together, and uneven dispersion will cause surface defects, processing torque fluctuation and product performance dispersion.

[0004] Furthermore, PC / ABS alloys are highly sensitive to moisture content; moisture content control, melt shear history, and venting conditions significantly affect the degree of material degradation and interfacial structure. In existing twin-screw melt blending processes, conductive fillers are often added all at once at the main feed port. When the melt viscosity is not yet stable, the fillers are subjected to strong shear, which easily leads to agglomeration or morphological damage. Simultaneously, volatiles and entrained gases are difficult to fully expel, resulting in increased internal porosity and interfacial defects in the product, further impacting the balance of electromagnetic shielding, wear resistance, and mechanical properties. Therefore, achieving stable, refined, and uniform dispersion of micron-sized metal powder in the PC / ABS system, improving the interfacial bonding between the filler and the matrix, while simultaneously ensuring wear resistance, mechanical properties, and electromagnetic shielding performance within the processing window, and reducing performance fluctuations and batch variations, remains a pressing technical challenge in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a wear-resistant and battery-shielding PC / ABS composite material and its preparation method to solve the above-mentioned problems.

[0006] To achieve the above objectives, the present invention provides the following solution: A wear-resistant and battery-shielding PC / ABS composite material and its preparation method, the composite material comprising: PC / ABS resin substrate; Micron-sized metal powder coated with polar silicone, wherein the mass percentage of the micron-sized metal powder coated with polar silicone is 2% to 15%; A compatibilizer, wherein the compatibilizer has a mass percentage content of 0.5% to 5%; Wear-resistant additives, wherein the wear-resistant additives have a mass percentage content of 0.1% to 3%; The balance consists of one or more of antioxidants, heat stabilizers, and processing lubricants; The PC / ABS resin substrate has a PC to ABS mass ratio of 3:7 to 7:3; the polar silicone forms a coating layer on the surface of the metal powder.

[0007] Furthermore, the D50 particle size of the micron-sized metal powder is 0.5μm to 10μm, and the D90 particle size is not greater than 20μm; the coating amount of the coating layer is 0.2% to 5% based on the mass of the metal powder, and / or the thickness of the coating layer is 20nm to 300nm.

[0008] Furthermore, the metal powder includes one or more of nickel powder, copper powder, aluminum powder, stainless steel powder, and nickel-coated copper powder, and the metal powder is flake powder, spherical powder, or a mixture of flake powder and spherical powder.

[0009] Furthermore, the polar silicone is a polyorganosiloxane containing polar side groups, wherein the polar side groups are one or more of amino, epoxy, hydroxy, carboxyl, and polyether groups; and / or the metal powder is activated at the interface by adding a silane coupling agent before or during the silicone coating process, wherein the silane coupling agent is one or more of aminopropyltriethoxysilane, glycidyltrimethoxysilane, and methacryloxypropyltrimethoxysilane.

[0010] Furthermore, the compatibilizer is one or more of maleic anhydride-grafted ABS, maleic anhydride-grafted SEBS, epoxy functional group chain extender, and styrene-acrylate compatibilizer; the wear-resistant additive is one or more of PTFE micro powder, silicone masterbatch, ultra-high molecular weight polyethylene micro powder, graphite, and molybdenum disulfide.

[0011] On the other hand, the present invention also provides a method for preparing the above-mentioned PC / ABS composite material, comprising: S1. Raw material pretreatment: Drying PC resin and ABS resin; S2. Metal powder coating: Micron-sized metal powder is contacted with polar silicone and mixed and coated to obtain coated metal powder with a coating layer on the surface; S3. Melt blending: PC resin, ABS resin, the coated metal powder, compatibilizer and wear-resistant additive are added to a twin-screw extruder according to the formula and melt blended extrusion is carried out at an extrusion temperature of 240℃~260℃. S4. Cooling and granulation: The extrudate is pulverized after being cooled by water to obtain composite material granules; S5. Post-processing: The composite material granules are uniformly mixed and packaged.

[0012] Further, S2 includes: high-speed shear mixing and / or ultrasonic dispersion of metal powder and polar silicone under solvent or solvent-free conditions, until the polar silicone is adsorbed or reacted and fixed on the surface of the metal powder; followed by desolvation and drying to obtain the coated metal powder.

[0013] Furthermore, in S3, segmented feeding is adopted: the PC / ABS resin substrate is added at the main feed port, and the coated metal powder is added to the screw section where a stable melt has been formed through the side feed port; and a vacuum exhaust section is set in the extruder to remove volatiles and entrained gases; the screw speed of the twin-screw extruder is 150 r / min to 400 r / min.

[0014] Furthermore, after step S4, the composite material granules are dried to reduce the moisture content of the granules to ≤0.05%.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This application introduces micron-sized metal powder coated with polar silicone into a PC / ABS resin substrate, and combines it with a synergistic system of compatibilizers and wear-resistant additives to achieve a more stable and uniform dispersion of the metal powder in the resin melt. This significantly reduces the problem of discontinuous conductive networks caused by metal powder agglomeration, sedimentation, and interfacial debonding. As a result, a more continuous electromagnetic shielding path can be formed under lower filling conditions, improving the stability and consistency of shielding performance, and reducing the dispersion of shielding effectiveness with batch and processing variations.

[0016] Because polar silicone forms a coating layer on the surface of the metal powder, it enhances the interfacial wetting and bonding ability between the metal powder and the PC / ABS matrix, reducing filler-matrix interface defects and stress concentration. On the other hand, the coating layer regulates the surface energy of the metal powder, which helps maintain the morphological integrity and effective contact of the sheet / spherical metal powder during the melting and shearing process. Thus, while taking into account impact toughness, tensile strength and elongation, it achieves a synergistic improvement in electromagnetic shielding and mechanical properties, avoiding the toughness reduction and microcrack propagation risks caused by direct filling of traditional metal powder.

[0017] Meanwhile, this application further enhances the compatibility and structural stability between the PC phase, ABS phase, and filler interface by setting compatibilizers (such as maleic anhydride grafting systems or epoxy functional group chain extenders), so that the composite system can still maintain good interface integrity under working conditions such as thermal cycling and vibration shock. In combination with wear-resistant additives such as PTFE micro powder, silicone masterbatch, ultra-high molecular weight polyethylene micro powder or solid lubricants, a more stable lubrication and wear-resistant structure is formed on the surface friction pair, reducing wear and scratch damage, and achieving the effect of improving wear resistance without significantly sacrificing shielding performance. Therefore, it is more suitable for application scenarios such as battery pack shells and module structural components where there is assembly friction, insertion and removal wear and long-term vibration.

[0018] Regarding the preparation method, this application adopts a process path of raw material drying pretreatment, metal powder coating pretreatment, and twin-screw melt blending. In the blending stage, segmented feeding and vacuum degassing are used to feed the coated metal powder into the section where the melt viscosity has stabilized, reducing the probability of metal powder agglomeration in the unstable melt stage and reducing structural damage caused by excessive shearing. Vacuum degassing removes volatiles and entrained gases, reducing the adverse effects of pore defects and degradation by-products on the interface structure. After granulation, the moisture content is controlled to improve the material processing stability and internal density of the product, further ensuring the comprehensive consistency of wear resistance, electromagnetic shielding performance, and mechanical properties. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Example 1

[0020] Based on a total mass of 100 parts by weight of composite materials, the formulation composition is as follows: 1. PC / ABS resin substrate (total 86.4 parts), of which PC resin 51.8 parts: bisphenol A linear polycarbonate; ABS resin 34.6 parts.

[0021] 2. 10.0 parts of micron-sized metal powder coated with polar silicone. Metal powder type: nickel-coated copper powder. Morphology: flake powder: spherical powder = 7:3 (mass ratio). Particle size: D50 = 3.5 μm, D90 ≤ 15 μm. Coating layer: 1.5% polar silicone coating by weight of metal powder; coating layer thickness approximately 80–150 nm.

[0022] 3. Compatibilizer 2.0 parts, selected from maleic anhydride grafted ABS (ABS-g-MAH), with MAH grafting content of 0.5% to 1.5% (mass fraction), used to improve the wetting and adhesion of the metal powder / silicone coating layer and the PC / ABS two-phase interface.

[0023] 4. Wear-resistant additive 1.2 parts.

[0024] 0.7 parts of PTFE micro powder: average particle size 3-10 μm, used to reduce the coefficient of friction and wear; 0.5 parts of silicone masterbatch, with an effective silicone content of 50% to 70%, and ABS or PC / ABS is preferred as the carrier resin to improve surface wear resistance and scratch resistance stability.

[0025] 5. Additive package, totaling 0.40 parts. Of which, 0.20 parts are antioxidant: hindered phenolic antioxidant, preferably pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenylpropionic acid)]. 0.15 parts are heat stabilizer: phosphite heat / processing stabilizer, preferably tris(2,4-di-tert-butylphenyl) phosphite. 0.05 parts are processing lubricant, a combination of internal and external lubricants, preferably 0.03 parts pentaerythritol tetrastearate + 0.02 parts ethylene bis-stearamide.

[0026] Based on the above formula, the preparation steps are as follows: S1: Raw material pretreatment (drying) PC resin: Dehumidify and dry at 115℃ for 4 hours, target moisture content ≤0.05%; ABS resin: Dry at 85℃ for 3 hours; Metal powder: Dry at 100℃ for 2 hours to avoid uneven coating and extrusion of air bubbles caused by surface water adsorption.

[0027] S2: Metal powder coating Interface activation: Take 100 parts by weight of metal powder and premix it in a high-speed mixer for 1 min; add aminopropyltriethoxysilane at 0.3% by weight of metal powder (ethanol can also be used as a carrier to form a spray liquid), and perform high-speed shearing for 5-10 min to complete surface activation; Polar silicone coating: Polyorganosiloxanes containing amino / polyether side groups are selected (viscosity at 25℃: 1000~5000mPa·s). Add 1.5% of the metal powder by weight and shear and mix at 1000-1500 rpm for 10-20 minutes to form a continuous coating layer of silicone on the surface of the metal powder. Solvent removal / drying: Vacuum drying at 80℃ for 2 hours yields a coated metal powder with good flowability.

[0028] S3: Melt blending (twin-screw extrusion) Extruder: Twin screw, L / D≥40, equipped with vacuum exhaust section; Temperature: 240~260℃ (zone settings: 240 / 245 / 250 / 255 / 255 / 250℃, head unit 250℃); Screw speed: 250 r / min; Feeding method (segmented feeding): Main feed port: PC, ABS, compatibilizer, wear-resistant additive, antioxidant, heat stabilizer, lubricant; Side feed port: Coated metal powder is added to the stable melt section; Vacuum exhaust: −0.06~−0.09MPa, reducing porosity defects caused by volatiles and entrained gases.

[0029] S4: Cooling Granulation Water-cooled traction and pelletizing, with a particle size of approximately 2–4 mm.

[0030] S5: Post-processing The granules were dried at 85℃ for 2-4 hours until the moisture content was ≤0.05%, and then mixed and packaged.

[0031] The technical solution of the present invention will be described below by comparison. Unless otherwise specified, the ingredients used in the formulation are the same as those in Example 1.

[0032] Comparative Example 1 Formulation composition (based on a total mass of 100 parts of composite material): PC resin: 55 parts; ABS resin: 45 parts; Metal powder (copper powder): 10 parts, uncoated, added directly; Compatibilizer: 1 part; Wear-resistant additive: 0.5 parts; Antioxidant: 0.2 parts; Heat stabilizer: 0.15 parts; Processing lubricant: 0.1 parts; Preparation method: Raw material pretreatment: PC resin and ABS resin are dried separately. The drying temperature of PC resin is 110℃ and the drying time is 4 hours; the drying temperature of ABS resin is 85℃ and the drying time is 3 hours.

[0033] Metal powder addition: 10 parts of copper powder (D50=5μm, uncoated) are added to the dry resin without any surface treatment.

[0034] Melt blending: PC resin, ABS resin, metal powder, compatibilizer, wear-resistant agent, antioxidant, heat stabilizer and lubricant are added to a twin-screw extruder according to the formula for melt blending. The extruder temperature is set to 240℃~260℃ and the screw speed is 200r / min.

[0035] Cooling and granulation: The molten material is pulverized by water cooling to obtain composite material granules with a particle size of 2-4 mm.

[0036] Post-processing: The granules are dried at a temperature of 80-90℃ for 2-4 hours, with the moisture content controlled to ≤0.05%, and then uniformly mixed and packaged.

[0037] Comparative Example 2 Formulation composition (based on a total mass of 100 parts of composite material): PC resin: 60 parts; ABS resin: 40 parts; Metal powder (aluminum powder): 5 parts (uncoated); Compatibilizer: 1.0 part (maleic anhydride-grafted ABS); Wear-resistant additive: 3 parts (a combination of graphite and PTFE micro powder, in a ratio of 2 parts graphite and 1 part PTFE micro powder). Antioxidant: 0.2 parts (hindered phenolic antioxidant); Heat stabilizer: 0.15 parts (phosphite heat stabilizer); Processing lubricant: 0.1 parts (ethylene bis-stearamide).

[0038] Preparation method Raw material pretreatment: PC resin and ABS resin are dried. PC resin is dried at 110℃ for 4 hours; ABS resin is dried at 85℃ for 3 hours.

[0039] Metal powder addition: 5 parts aluminum powder (D50=3μm, uncoated) are added to the resin matrix without any surface treatment.

[0040] Melt blending: PC resin, ABS resin, metal powder, compatibilizer, wear-resistant agent, antioxidant, heat stabilizer and lubricant are added to a twin-screw extruder according to the formula for melt blending. The extruder temperature is set to 240℃~260℃ and the screw speed is 200r / min.

[0041] Cooling and granulation: The molten material is pulverized by water cooling to obtain composite material granules with a particle size of 2-4 mm.

[0042] Post-processing: The granules are dried at a temperature of 80-90℃ for 2-4 hours, with the moisture content controlled to ≤0.05%, and then uniformly mixed and packaged.

[0043] Comparative Example 3 Formulation composition (based on a total mass of 100 parts of composite material): PC resin: 65 parts; ABS resin: 35 parts; Metal powder (not added): 0 parts; Compatibilizer: 2.0 parts (maleic anhydride-grafted ABS); Wear-resistant additives: 4 parts (2 parts ultra-high molecular weight polyethylene micro powder, 2 parts PTFE micro powder); Antioxidant: 0.2 parts (hindered phenolic antioxidant); Heat stabilizer: 0.15 parts (phosphite heat stabilizer); Processing lubricant: 0.1 parts (pentaerythritol tetrastearate).

[0044] Preparation method Raw material pretreatment: PC resin and ABS resin are dried. PC resin is dried at 110℃ for 4 hours; ABS resin is dried at 85℃ for 3 hours.

[0045] Melt blending: PC resin, ABS resin, compatibilizer, wear-resistant agent, antioxidant, heat stabilizer and lubricant are added to a twin-screw extruder according to the formula for melt blending. The extruder temperature is set to 240℃~260℃ and the screw speed is 200r / min.

[0046] Cooling and granulation: The molten material is pulverized by water cooling to obtain composite material granules with a particle size of 2-4 mm.

[0047] Post-processing: The granules are dried at a temperature of 80-90℃ for 2-4 hours, with the moisture content controlled to ≤0.05%, and then uniformly mixed and packaged.

[0048] Experimental tests were conducted on Example 1 and Comparative Examples 1-3. The test results are shown in Table 1, and the test contents are as follows: 1. Electromagnetic shielding effectiveness test Experimental item: Electromagnetic shielding effectiveness (EMI shielding effectiveness) Test method: Electromagnetic shielding effectiveness is tested according to ASTM D4935-17 standard.

[0049] step: The frequency of the injection-molded sample was scanned using an electromagnetic shielding effectiveness tester (such as an HP8510B network analyzer or a Keysight 85070A). The sample size was 100mm × 100mm, and the measurement frequency range was 1GHz to 3GHz.

[0050] Calculate the electromagnetic shielding effectiveness (SE) value, in dB.

[0051] Evaluation criteria: The shielding effectiveness should reach ≥30dB, proving that the electromagnetic shielding performance is stable and effective.

[0052] 2. Abrasion resistance test Experimental item: Abrasion resistance (Taber abrasion test) Test method: Taber abrasion test according to ASTM D4060 standard.

[0053] step: Standard circular specimens, 50 mm in size, were prepared. The Taber abrasion tester was used, with a grinding wheel load of 1 kg, and 1000 tests were performed. The mass loss of the specimens was measured, and the abrasion amount (unit: mg) was calculated. Changes in surface morphology after wear were recorded (observed using a microscope or scanning electron microscope (SEM)). Evaluation criteria: The abrasion amount should be as low as possible, and the surface should maintain high flatness and stability to verify wear resistance.

[0054] 3. Mechanical property testing Experimental items: impact strength, tensile strength, flexural strength, and flexural modulus.

[0055] Detection method: Impact strength: The notched impact test is performed according to ISO 179-1 standard to test the impact resistance of the specimen.

[0056] Tensile strength: The maximum tensile strength of the material is determined by performing a tensile test according to ISO 527-2 standard.

[0057] Bending strength and bending modulus: Bending strength and bending modulus were determined by a three-point bending test according to ISO 178 standard.

[0058] 4. Heat distortion temperature test Experimental item: Heat distortion temperature (HDT) Test method: Heat distortion temperature test according to ISO 75 standard.

[0059] Procedure: Heat the sample under a load of 1.8 MPa and record the temperature at which the material begins to deform.

[0060] Table 1

[0061] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A wear-resistant and battery-shielding PC / ABS composite material, characterized in that, The composite material includes: PC / ABS resin substrate; Micron-sized metal powder coated with polar silicone, wherein the mass percentage of the micron-sized metal powder coated with polar silicone is 2% to 15%; A compatibilizer, wherein the compatibilizer has a mass percentage content of 0.5% to 5%; Wear-resistant additives, wherein the wear-resistant additives have a mass percentage content of 0.1% to 3%; The balance consists of one or more of antioxidants, heat stabilizers, and processing lubricants; The PC / ABS resin substrate has a PC to ABS mass ratio of 3:7 to 7:3; the polar silicone forms a coating layer on the surface of the metal powder.

2. The PC / ABS composite material according to claim 1, characterized in that, The micron-sized metal powder has a D50 particle size of 0.5μm to 10μm and a D90 particle size of no more than 20μm; the coating amount of the coating layer is 0.2% to 5% based on the mass of the metal powder, and / or the thickness of the coating layer is 20nm to 300nm.

3. The PC / ABS composite material according to claim 1, characterized in that, The metal powder includes one or more of nickel powder, copper powder, aluminum powder, stainless steel powder, and nickel-coated copper powder, and the metal powder is flake powder, spherical powder, or a mixture of flake powder and spherical powder.

4. The PC / ABS composite material according to claim 1, characterized in that, The polar silicone is a polyorganosiloxane containing polar side groups, wherein the polar side groups are one or more of amino, epoxy, hydroxy, carboxyl, and polyether groups; and / or the metal powder is activated at the interface by adding a silane coupling agent before or during the silicone coating process, wherein the silane coupling agent is one or more of aminopropyltriethoxysilane, glycidyltrimethoxysilane, and methacryloxypropyltrimethoxysilane.

5. The PC / ABS composite material according to claim 1, characterized in that, The compatibilizer is one or more of maleic anhydride-grafted ABS, maleic anhydride-grafted SEBS, epoxy functional group chain extender, and styrene-acrylate compatibilizer; the wear-resistant additive is one or more of PTFE micro powder, silicone masterbatch, ultra-high molecular weight polyethylene micro powder, graphite, and molybdenum disulfide.

6. A method for preparing the PC / ABS composite material according to any one of claims 1 to 5, characterized in that, include: S1. Raw material pretreatment: Drying PC resin and ABS resin; S2. Metal powder coating: Micron-sized metal powder is contacted with polar silicone and mixed and coated to obtain coated metal powder with a coating layer on the surface; S3. Melt blending: PC resin, ABS resin, the coated metal powder, compatibilizer and wear-resistant additive are added to a twin-screw extruder according to the formula and melt blended extrusion is carried out at an extrusion temperature of 240℃~260℃. S4. Cooling and granulation: The extrudate is pulverized after being cooled by water to obtain composite material granules; S5. Post-processing: The composite material granules are uniformly mixed and packaged.

7. The preparation method according to claim 6, characterized in that, S2 includes: high-speed shear mixing and / or ultrasonic dispersion of metal powder and polar silicone under solvent or solvent-free conditions, until the polar silicone is adsorbed or reacted and fixed on the surface of the metal powder; followed by desolvation and drying to obtain the coated metal powder.

8. The preparation method according to claim 6, characterized in that, In S3, segmented feeding is adopted: PC / ABS resin substrate is added at the main feed port, and the coated metal powder is added to the screw section where a stable melt has been formed through the side feed port; and a vacuum exhaust section is set in the extruder to remove volatiles and entrained gases; the screw speed of the twin-screw extruder is 150r / min to 400r / min.

9. The preparation method according to claim 6, characterized in that, After step S4, the composite material granules are dried to ensure that the moisture content of the granules is ≤0.05%.

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