Nickel-plated carbon fiber shielding plastic capable of being used at low frequency and preparation method thereof

Abstract

The invention discloses nickel-plated carbon fiber shielding plastic capable of being used at low frequency and a preparation method, the nickel-plated carbon fiber shielding plastic comprises the following components in percentage by weight: 10-40% of nickel-plated carbon fiber, magnetic nanoparticles are deposited on the surface of the nickel-plated carbon fiber, the magnetic nanoparticles account for 1-5% of the weight of the nickel-plated carbon fiber, and the magnetic nanoparticles account for 1-5% of the weight of the nickel-plated carbon fiber. The magnetic nanoparticles have two kinds of magnetic nanoparticles with different granularities; the composite material comprises the following components in percentage by weight: 0-30% of nickel-coated graphite, 0-25% of flame retardant, 0.2-5% of lubricant, 0.1-5% of compatilizer, 0.1-2% of antioxidant and the balance of matrix resin. The residual length of the obtained fiber is long, the mechanical property and the shielding property of the material can be greatly improved, the binding force of the nickel plating layer and the carbon fiber is strong, the shielding effectiveness in the frequency range of 30MHz-1000MHz can reach 30-95dB, the shielding effectiveness of the material in the low-frequency band of 10kHz-1MHz is obviously improved, and the material can be used in the low-frequency band.

Description

Technical Field

[0001] The present invention belongs to the field of functional carbon fiber composites, and particularly relates to a nickel-plated carbon fiber shielding plastic and a preparation method thereof. Background Art

[0002] Filled composite electromagnetic shielding composites are the most important and promising high-performance electromagnetic shielding materials at present and in the future. In recent years, the market demand has increased rapidly. Given the important role of electromagnetic shielding materials, their research and development have become an important topic that people pay increasing attention to. Currently, the main conductive fillers are carbon black, graphite, metal powder, carbon fiber or metal fiber, etc. Carbon black and graphite have a low aspect ratio and cannot endow plastics with high conductivity, and can only make plastics have antistatic and semi-conductive capabilities; the insufficient conductivity of carbon fiber makes the shielding effectiveness of the filled plastic difficult to reach 30 dB even in the frequency range of 30 MHz to 1000 MHz. Although the shielding plastic filled with metal fiber can obtain a shielding effectiveness of 60 dB or even higher in the frequency range of 30 MHz to 1000 MHz, its main defects are high specific gravity and insufficient mechanical properties. Therefore, nickel-plated carbon fibers have been manufactured since the 1990s and are used to develop high-performance shielding plastics. Nickel-plated carbon fibers have both the high strength and high modulus of carbon fibers and the high conductivity of metal fibers, and are the most ideal conductive filler so far. The plastic filled with nickel-plated carbon fibers not only has excellent mechanical properties but also has high shielding effectiveness. However, the existing technology does not effectively surface-treat nickel-plated carbon fibers. Therefore, it is difficult for the fibers to disperse in the matrix, and forced dispersion will cause the residual length of the fibers to become shorter, and the potential of nickel-plated carbon fibers cannot be fully exerted; in addition, the shielding effectiveness of the plastic filled with pure nickel-plated carbon fibers is not ideal in the low-frequency band (10 kHz to 1 MHz), so it cannot meet the requirements in some low-frequency applications. Summary of the Invention

[0003] In view of the above-mentioned prior art, the present invention provides a nickel-plated carbon fiber shielding plastic that can be used at low frequencies and a preparation method thereof.

[0004] In order to solve the above technical problems, the components (weight percentage content) of the nickel-plated carbon fiber shielding plastic that can be used at low frequencies according to the present invention are: 10-40% of nickel-plated carbon fibers, magnetic nanoparticles are deposited on the surface of the nickel-plated carbon fibers, and the weight percentage content of the magnetic nanoparticles in the nickel-plated carbon fibers is 1-5%; 0-30% of nickel-coated graphite, 0-25% of flame retardant, 0.2-5% of lubricant, 0.1-5% of compatibilizer, 0.1-2% of antioxidant, and the balance is matrix resin.

[0005] Furthermore, for the nickel-plated carbon fiber shielding plastic that can be used at low frequencies according to the present invention, among them:

[0006] The magnetic nanoparticles include but are not limited to Fe3 O 4 、 Fe 2 O 3 、 Co 3 O 4 and one of NiO.

[0007] The magnetic nanoparticles have two different particle sizes, and their particle diameters and weight percentage contents are as follows: those with a particle diameter of 10 - 30 nm account for 30 - 80%, and those with a particle diameter of 300 - 500 nm account for 20 - 70%.

[0008] The matrix resin includes, but is not limited to, one selected from nylon 6, nylon 6,6, polycarbonate / acrylonitrile - styrene - butadiene copolymer alloy, polybutylene terephthalate, and polypropylene, and its melt index is 10 - 30 g / 10 min.

[0009] The preparation method of the nickel - plated carbon fiber shielding plastic that can be used at low frequencies according to the present invention includes the following steps:

[0010] 1) Surface - activate the magnetic nanoparticles with a titanate coupling agent, and then dry them at 110°C for 8 hours;

[0011] 2) Add the magnetic nanoparticles with a particle diameter less than 100 nm and those with a particle diameter greater than 100 nm processed in step 1) into the surface treatment liquid of nickel - plated carbon fiber composed of epoxy emulsion and coupling agent respectively. The weight of the two kinds of magnetic nanoparticles accounts for 0.1 - 10% of the surface treatment liquid of nickel - plated carbon fiber. The two surface treatment liquids are respectively abbreviated as surface treatment liquid A and surface treatment liquid B;

[0012] 3) Continuously introduce the nickel - plated carbon fiber into the treatment tanks containing the above - mentioned surface treatment liquid A and B of nickel - plated carbon fiber successively, and continuously circulate and stir. The treatment time of the nickel - plated carbon fiber in the A and B treatment tanks is 2 - 6 minutes. Dry the nickel - plated carbon fiber with magnetic nanoparticles deposited on its surface obtained thereby at 80 - 110°C for 48 hours;

[0013] 4) Mix 0 - 30% of nickel - coated graphite, 0 - 25% of flame retardant, 0.2 - 5% of lubricant, 0.1 - 5% of compatibilizer, and 0.1 - 2% of antioxidant;

[0014] 5) Use a twin - screw extruder. Load the matrix resin into the barrel of the extruder, add the mixture obtained in step 4) from the side - feeding barrel of the extruder, and make the nickel - plated carbon fiber with magnetic nanoparticles deposited on its surface obtained in step 4) enter the coating die of the extruder in a direction perpendicular to the matrix resin, and perform extrusion, pelletizing, and injection molding to obtain the nickel - plated carbon fiber shielding plastic that can be used at low frequencies.

[0015] Furthermore, in the preparation method described in the present invention:

[0016] The nickel-plated carbon fiber is prepared by one of electroplating or electroless plating methods; the nickel layer thickness of the nickel-plated carbon fiber is 0.1 - 1.0 μm; and the carbon fiber is pretreated in a NaOH solution (concentration: 1 mol / L) before nickel plating (treatment conditions: solution temperature 40°C, time 40 minutes).

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] In the present invention, due to the presence of magnetic nanoparticles on the surface of the nickel-plated carbon fiber, it can be used in the low-frequency region; due to the doping of nickel-coated graphite, the cost can be appropriately reduced under the condition of maintaining a high shielding effectiveness; due to the use of coated particles, the residual length of the fiber is long, and the mechanical properties and shielding properties of the material can be greatly improved; due to the pretreatment of the carbon fiber in a NaOH solution before nickel plating, the bonding force between the nickel coating and the carbon fiber is enhanced. The shielding plastic of the present invention can reach 30 - 95 dB in the frequency range of 30 MHz - 1000 MHz, and significantly improve the shielding effectiveness of the material in the low-frequency band of 10 kHz - 1 MHz. Description of the Drawings

[0019] Figure 1 is the SEM photograph of the nickel-plated carbon fiber with Fe 3 O 4 nanoparticles on its surface prepared in Example 1;

[0020] Figure 2 is the energy spectrum diagram of the nickel-plated carbon fiber with Fe 3 O 4 nanoparticles on its surface prepared in Example 1;

[0021] Figure 3 is the tissue photograph (100 times) of the nickel-plated carbon fiber shielding plastic that can be used at low frequencies prepared in Example 1;

[0022] Figure 4 is the tissue photograph (500 times) of the nickel-plated carbon fiber shielding plastic that can be used at low frequencies prepared in Example 2. Detailed Embodiments

[0023] The design idea of a preparation method of nickel-plated carbon fiber shielding plastic that can be used at low frequencies proposed by the present invention is as follows: nickel-plated carbon fibers coated with magnetic nanoparticles are used in a resin matrix, and appropriate surface treatment is carried out on the fibers, so as to increase the dispersion of the fibers in the matrix, strengthen the bonding between the nickel coating and the carbon fibers, improve the mechanical and shielding properties of the shielding plastic, and at the same time improve the shielding effectiveness of the shielding plastic in the low-frequency band. The components and weight percentage contents of the nickel-plated carbon fiber shielding plastic are as follows: nickel-plated carbon fibers 10-40%, magnetic nanoparticles are deposited on the surface of the nickel-plated carbon fibers, and the weight percentage content of the magnetic nanoparticles in the nickel-plated carbon fibers is 1-5%; nickel-coated graphite 0-30%, flame retardant 0-25%, lubricant 0.2-5%, compatibilizer 0.1-5%, antioxidant 0.1-2%, and the balance is matrix resin. Among them, the magnetic nanoparticles include but are not limited to Fe 3 O 4 、Fe 2 O 3 、Co 3 O 4 and one of NiO. The magnetic nanoparticles have two different particle sizes, and their particle sizes and weight percentage contents are as follows: those with a particle size of 10-30 nm account for 30-80%, and those with a particle size of 300-500 nm account for 20-70%. The matrix resin includes but is not limited to one of nylon 6, nylon 6,6, polycarbonate / acrylonitrile-styrene-butadiene copolymer alloy, acrylonitrile-styrene-butadiene copolymer alloy poly, polybutylene terephthalate, and polypropylene, and its melt index is 10-30 g / 10 min. The preparation steps of the nickel-plated carbon fiber shielding plastic include:

[0024] (1) Surface activation treatment of the magnetic nanoparticles with a titanate coupling agent, and then drying at 110°C for 8 hours;

[0025] (2) Add magnetic nanoparticles with a particle size less than 100 nm and magnetic nanoparticles with a particle size greater than 100 nm treated in step (1) into the surface treatment liquid of nickel-plated carbon fibers composed of epoxy emulsion and coupling agent respectively. The weight of the two magnetic nanoparticles accounts for 0.1-10% of the surface treatment liquid of nickel-plated carbon fibers, and the two surface treatment liquids are named A and B respectively;

[0026] (3) Continuously introduce the nickel-plated carbon fibers into the treatment tanks containing the surface treatment liquid A and B of the nickel-plated carbon fibers successively, and continuously circulate and stir. The treatment time of the nickel-plated carbon fibers in the A and B treatment tanks is 2-6 minutes, and the nickel-plated carbon fibers with magnetic nanoparticles deposited on the surface obtained therefrom are dried at 80-110°C for 48 hours;

[0027] (4) Weigh nickel-coated graphite, flame retardant, lubricant, compatibilizer and antioxidant according to the designed weight percentage, and mix them;

[0028] (5) Use a twin-screw extruder. Load the matrix resin into the barrel of the extruder, add the mixture obtained in step (4) from the side feeding barrel of the extruder, and make the nickel-plated carbon fiber with magnetic nanoparticles deposited on its surface obtained in step (3) enter the coating die of the extruder in a direction perpendicular to the matrix resin, and then perform extrusion, pelletizing, and injection molding to obtain a nickel-plated carbon fiber shielding plastic that can be used at low frequencies.

[0029] The following further illustrates the present invention in conjunction with the accompanying drawings and specific embodiments, but the following embodiments are by no means any limitation to the present invention.

[0030] Example 1

[0031] Preparation of a nickel-plated carbon fiber shielding plastic that can be used at low frequencies. The components and weight percentage contents of the shielding plastic are as follows: nickel-plated carbon fiber 18%, and magnetic nanoparticles Fe 3 O 4 are deposited on the surface of the nickel-plated carbon fiber, and the weight percentage of the magnetic nanoparticles Fe 3 O 4 in the nickel-plated carbon fiber is 2.5%; nickel-coated graphite 18%, flame retardant 15%, lubricant 1%, compatibilizer 2%, antioxidant 0.5%, and the rest is matrix resin. It is prepared according to the following steps:

[0032] (1) Use a titanate coupling agent to perform surface activation treatment on magnetic nanoparticles Fe 3 O 4 with two particle sizes. The particle size and mass percentage content of the magnetic nanoparticles Fe 3 O 4 are 10 nm / 30% and 350 nm / 70% respectively, and then dry at 110 °C for 8 hours;

[0033] (2) The nickel-plated carbon fiber is prepared by a common electroplating method, and the thickness of the nickel coating is 0.8 μm; the carbon fiber is pretreated in a NaOH solution (concentration: 1 mol / L) before nickel plating (treatment conditions: solution temperature 40 °C, time 40 minutes).

[0034] (3) Add the treated magnetic nanoparticles Fe with particle sizes of 10 nm and 350 nm 3 O 4 to the surface treatment solutions of the nickel-plated carbon fiber (epoxy emulsion and coupling agent) respectively. The two surface treatment solutions are denoted as surface treatment solution A and surface treatment solution B. The weight percentage of the two magnetic nanoparticles Fe 3 O 4 in the surface treatment solutions of the nickel-plated carbon fiber is 6% each, so that the obtained nickel-plated carbon fiber contains 2.5% of the magnetic nanoparticles Fe 3 O4 ; The nickel-plated carbon fibers are successively and continuously introduced into the tanks containing surface treatment liquids A and B (the length of the tanks is 2 m), and continuously and circularly stirred for 2 minutes. The traveling rate of the nickel-plated carbon fibers in the treatment tanks is 1 m / min. The nickel-plated carbon fibers with magnetic nanoparticles Fe 3 O 4 deposited on the surface are dried at 110 °C for 48 hours and then reserved for use; Figure 1 is the SEM photograph of the nickel-plated carbon fibers with Fe 3 O 4 nanoparticles on the surface; Figure 2 is the energy spectrum diagram of the nickel-plated carbon fibers with Fe 3 O 4 nanoparticles on the surface.

[0035] (4) Using a twin-screw extruder, load the polycarbonate / acrylonitrile-butadiene-styrene copolymer alloy PC / ABS matrix resin into the barrel of the extruder; Weigh nickel-coated graphite, flame retardant, lubricant, compatibilizer and antioxidant according to the weight percentage content of the relevant components determined previously, mix them evenly and add them from the side feeding barrel; 18% of the nickel-plated carbon fibers with 2.5% magnetic nanoparticles Fe 3 O 4 deposited on the surface enter the coating die in a direction perpendicular to the resin, and after extrusion, a polycarbonate / acrylonitrile-butadiene-styrene copolymer alloy PC / ABS resin is coated on the outer surface of the nickel-plated carbon fibers with 2.5% magnetic nanoparticles Fe 3 O 4 deposited on the surface. Then, it is cut into particles with a pelletizer to obtain the particles of the nickel-plated carbon fiber shielding plastic that can be used at low frequencies. Finally, the obtained pelletized material is injection molded to obtain a shielding plastic sample with a thickness of 2 mm. Figure 3 is the tissue photograph of the obtained shielding plastic, and its shielding effectiveness is 60 - 90 dB (in the frequency band of 30 - 1120 MHz).

[0036] Example 2

[0037] The preparation of a nickel-plated carbon fiber shielding plastic that can be used at low frequencies. The components and weight percentage content of the shielding plastic are as follows: 12% nickel-plated carbon fibers, and magnetic nanoparticles Fe 2 O 3 are deposited on the surface of the nickel-plated carbon fibers. The weight percentage content of the magnetic nanoparticles Fe 2 O 3 in the nickel-plated carbon fibers is 0.5%; 1.5% lubricant, 1% compatibilizer, 1% antioxidant, and the rest is acrylonitrile-butadiene-styrene copolymer alloy ABS matrix resin. It is prepared according to the following steps:

[0038] (1) Surface activation treatment was carried out on magnetic nanoparticles Fe 2 O 3 with two particle sizes (their particle sizes and mass percentages are 50 nm / 45% and 300 nm / 55% respectively), and then dried at 110 °C for 8 hours;

[0039] (2) The nickel-plated carbon fibers were prepared by a common electroplating method, and the thickness of the nickel coating was 0.4 μm; the carbon fibers were pretreated in a NaOH solution (concentration: 1 mol / L) before nickel plating (treatment conditions: solution temperature 40 °C, time 40 minutes).

[0040] (3) The two kinds of magnetic nanoparticles Fe 2 O 3 with particle sizes of 50 nm and 300 nm after treatment were respectively added to the surface treatment solutions of nickel-plated carbon fibers (epoxy emulsion and coupling agent). The two surface treatment solutions were respectively denoted as surface treatment solution A and surface treatment solution B. The weight percentage of the two kinds of magnetic nanoparticles Fe 2 O 3 in the surface treatment solution of nickel-plated carbon fibers was 2%, so that the obtained nickel-plated carbon fibers contained 0.5% of magnetic nanoparticles Fe 2 O 3 ; the nickel-plated carbon fibers were successively and continuously introduced into the tanks containing surface treatment solution A and B (the length of the tank was 2 m), and continuously and circularly stirred for 2.5 minutes. The traveling rate of the nickel-plated carbon fibers in the treatment tank was 0.8 m / min. The nickel-plated carbon fibers with magnetic nanoparticles Fe 2 O 3 deposited on the surface were dried at 110 °C for 48 hours and then used;

[0041] (4) Using a twin-screw extruder, the ABS matrix resin material was loaded into the barrel of the extruder, and the uniformly mixed filler (including 5%, 1.5% lubricant, 1% compatibilizer and 1% antioxidant) was added from the side feeding barrel. The nickel-plated carbon fibers with magnetic nanoparticles Fe 2 O 3 deposited on the surface after the above treatment entered the coating die in a direction perpendicular to the resin. After extrusion, a polyacrylonitrile-styrene-butadiene copolymer alloy ABS resin was coated on the outer surface of the nickel-plated carbon fibers with 0.5% magnetic nanoparticles Fe 2 O 3 deposited on the surface. Then it was cut into particles with a granulator, and the particles of nickel-plated carbon fiber shielding plastic that could be used at low frequencies were obtained. Finally, the obtained particle material was injection molded to obtain a shielding plastic sample with a thickness of 2 mm. Figure 4 Figure is the tissue photo of the obtained shielding plastic, and its shielding effectiveness is 40 - 65 dB (in the frequency band of 30 - 1120 MHz).

[0042] Example 3

[0043] Preparation of a nickel-plated carbon fiber shielding plastic that can be used at low frequencies. The components and weight percentage contents of the shielding plastic are as follows: nickel-plated carbon fiber 30% (magnetic nanoparticles Fe 2 O 3 are deposited on the surface of the nickel-plated carbon fiber, and the weight percentage of the magnetic nanoparticles Fe 2 O 3 in the nickel-plated carbon fiber is 2%), lubricant 2.5%, compatibilizer 2%, antioxidant 1%, and the rest is nylon 6 (PA6) matrix resin. It is prepared according to the following steps:

[0044] (1) Use a titanate coupling agent to perform surface activation treatment on two particle sizes of magnetic nanoparticles Fe 2 O 3 (their particle sizes and mass percentage contents are 30 nm / 40% and 500 nm / 60% respectively), and then dry at 110 °C for 8 hours;

[0045] (2) The nickel-plated carbon fiber is prepared by a common electroplating method, and the thickness of the nickel coating is 1.0 micrometer; the carbon fiber is pretreated in a NaOH solution (concentration: 1 mol / L) before nickel plating (treatment conditions: solution temperature 40 °C, time 40 minutes).

[0046] (3) Add the two kinds of magnetic nanoparticles Fe 2 O 3 with particle sizes of 30 nm and 500 nm after treatment into the surface treatment solutions of the nickel-plated carbon fiber (epoxy emulsion and coupling agent) respectively. The two surface treatment solutions are respectively denoted as surface treatment solution A and surface treatment solution B. The weight percentage of the two kinds of magnetic nanoparticles Fe 2 O 3 in the surface treatment solution of the nickel-plated carbon fiber is 3%, so that the obtained nickel-plated carbon fiber contains 2% of the magnetic nanoparticles Fe 2 O 3 ; Continuously introduce the nickel-plated carbon fiber into the tanks containing surface treatment solution A and B successively (the length of the tank is 2 m), and continuously circulate and stir for 4 minutes. The traveling rate of the nickel-plated carbon fiber in the treatment tank is 0.5 m / min. Dry the nickel-plated carbon fiber with magnetic nanoparticles Fe 2 O 3 deposited on its surface at 100 °C for 48 hours and then use it;

[0047] (4) Use a twin-screw extruder. Load the PA6 resin material into the barrel of the extruder, and add the uniformly mixed filler (including 2.5% lubricant, 2% compatibilizer, 1% antioxidant) from the side feeding barrel. The surface of the above-treated material is deposited with magnetic nanoparticles Fe 2O 3 The nickel-plated carbon fibers and carbon fibers enter the coating die in a direction perpendicular to the resin, and after extrusion, 2% magnetic nanoparticles Fe are deposited on the surface of the carbon fibers 2 O 3 The outer surfaces of the nickel-plated carbon fibers are all coated with PA6 resin, and then cut into particles by a pelletizer to obtain the particles of nickel-plated carbon fiber shielding plastic that can be used at low frequencies. Finally, the obtained particle material is injection-molded to obtain a shielding plastic sample with a thickness of 2 mm, and its shielding effectiveness is 68 - 95 dB (in the frequency band of 30 - 1120 MHz).

[0048] In summary, the residual length of the fibers obtainable by the present invention is long, the mechanical properties and shielding properties of the material can be greatly improved, the bonding force between the nickel coating and the carbon fiber is strong, the shielding effectiveness in the frequency range of 30 MHz to 1000 MHz can reach 30 - 95 dB, and the shielding effectiveness of the material in the low frequency band of 10 kHz to 1 MHz is significantly improved, enabling it to be used in the low frequency band.

[0049] Although the present invention has been described above in conjunction with the drawings, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many variations without departing from the purpose of the present invention, and all of these fall within the protection scope of the present invention.

Claims

1. A nickel-plated carbon fiber shielding plastic that can be used at low frequencies, the components and weight percentages of which are: 10-40% nickel-plated carbon fiber, magnetic nanoparticles are deposited on the surface of the nickel-plated carbon fiber, and the weight percentage of the magnetic nanoparticles in the nickel-plated carbon fiber is 1-5%; 0-30% nickel-coated graphite, 0-25% flame retardant, 0.2-5% lubricant, 0.1-5% compatibilizer, 0.1-2% antioxidant, and the balance is matrix resin.

2. The nickel-plated carbon fiber shielding plastic according to claim 1, characterized in that: The magnetic nanoparticles include one of Fe3O4, Fe2O3, Co3O4 and NiO.

3. The nickel-plated carbon fiber shielding plastic according to claim 1, characterized in that: The magnetic nanoparticles have two different particle sizes, and the particle sizes and weight percentage contents are as follows: the particle sizes of 10 to 30 nanometers account for 30 to 80%, and the particle sizes of 300 to 500 nanometers account for 20 to 70%.

4. The nickel-plated carbon fiber shielding plastic according to claim 1, characterized in that: The matrix resin comprises one of nylon 6, nylon 6,6, polycarbonate / acrylonitrile-styrene-butadiene copolymer alloy, acrylonitrile-styrene-butadiene copolymer alloy, polybutylene terephthalate and polypropylene, and the melt index of the matrix resin is 10 to 30 g / 10 min.

5. The method for preparing the nickel-plated carbon fiber shielding plastic according to any one of claims 1 to 4, comprising the following steps: Step 1) Surface activation treatment of magnetic nanoparticles is performed using a titanate coupling agent, followed by drying at 110° C. for 8 hours; Step 2) adding the magnetic nanoparticles with a particle size less than 100 nm and the magnetic nanoparticles with a particle size greater than 100 nm treated in step 1) to a surface treatment solution of nickel-plated carbon fiber composed of epoxy emulsion and coupling agent, respectively, the weight of the two magnetic nanoparticles respectively accounts for 0.1-10% of the surface treatment solution of the nickel-plated carbon fiber, and the surface treatment solutions containing the magnetic nanoparticles with a particle size less than 100 nm and the magnetic nanoparticles with a particle size greater than 100 nm are referred to as surface treatment solution A and surface treatment solution B, respectively; Step 3) The nickel-plated carbon fiber is successively introduced into the treatment tank containing the surface treatment liquid A and the surface treatment liquid B of the nickel-plated carbon fiber, and the treatment time of the nickel-plated carbon fiber in the surface treatment liquid A and the surface treatment liquid B treatment tank is 2 to 6 minutes, and the nickel-plated carbon fiber with magnetic nanoparticles deposited on the surface obtained is dried at 80 to 110 ° C for 48 hours; Step 4) calculating the required weight of nickel-coated graphite, flame retardant, lubricant, compatibilizer and antioxidant according to the weight percentage of nickel-coated graphite, flame retardant, lubricant, compatibilizer and antioxidant in the nickel-plated carbon fiber shielding plastic, and then mixing these components to obtain a mixture; Step 5) Calculate the required matrix resin according to the weight percentage of the matrix resin in the nickel-plated carbon fiber shielding plastic, use a twin-screw extruder, load the matrix resin into the extruder barrel, add the mixture obtained in step 4) from the side feeding barrel of the extruder, and feed the nickel-plated carbon fiber with magnetic nanoparticles deposited on the surface obtained in step 3) into the coating die of the extruder in a direction perpendicular to the matrix resin for extrusion, pelletizing and injection molding to obtain a nickel-plated carbon fiber shielding plastic that can be used at a low frequency.

6. The preparation method according to claim 5, characterized in that: The nickel-plated carbon fiber is prepared by electroplating or chemical plating, and the thickness of the nickel layer of the nickel-plated carbon fiber is 0.1-1.0 μm.

7. The preparation method according to claim 5, characterized in that: In step 2), the carbon fiber is pretreated in a NaOH solution with a concentration of 1 mol / L before nickel plating, with the treatment temperature being 40° C. and the treatment time being 40 minutes.

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