Electromagnetic shielding composite material and preparation method and application thereof

Abstract

The invention belongs to the technical field of composite materials, and provides an electromagnetic shielding composite material and a preparation method and application thereof.The preparation method specifically comprises the following steps that phoenix tree wood is subjected to delignification treatment, and a wood test piece is obtained; the wood test piece and the graphene oxide solution are mixed and then subjected to hot pressing, and a graphene-wood-based material is obtained; the graphene-wood-based material, the carbon nano tube-metal solution and the trimethylolpropane triacrylate solution are mixed and then cross-linked, and the electromagnetic shielding composite material is obtained. The electromagnetic shielding composite material provided by the invention has the characteristics of light weight, good processability, flexibility and high shielding, and can be applied to electronic equipment with requirements on the shape to realize the target of efficiently shielding electromagnetic waves; the method provided by the invention is simple, has low process requirements and can be popularized and prepared on a large scale.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and particularly relates to an electromagnetic shielding composite material, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of society, communication technologies and electronic devices have become an essential part of modern society, affecting all aspects of human activities. In daily life, the fluctuations of related devices are not noticed, but communication and electronic devices carry electrical signals and transmissions, involving changes in current and magnetic fields. Such electromagnetic fluctuations can cause significant interference to electronic components, resulting in unstable signal transmission. Seriously, it can lead to malfunctions of various electronic devices and loss of control of factory systems, bringing serious potential safety hazards. According to statistics, huge economic losses are caused by electromagnetic interference every year. Therefore, in order to eliminate the influence of electromagnetic waves, researchers have studied electromagnetic shielding materials.

[0003] Due to their high conductivity and outstanding electromagnetic shielding performance, metal materials have become the primary electromagnetic shielding materials. However, in use, problems such as excessive mass, poor flexibility, shape mismatch, and high processing difficulty of metal materials have been found, making them unable to match the increasingly miniaturized and refined various types of equipment. Therefore, developing a new type of electromagnetic shielding composite material has become a research direction in the fields of electronics and communication. Summary of the Invention

[0004] The purpose of the present invention is to overcome the prior art and provide an electromagnetic shielding composite material, a preparation method thereof, and an application thereof.

[0005] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions: The present invention provides a preparation method of an electromagnetic shielding composite material, comprising the following steps: (1) Perform delignification treatment on Chinese parasol wood to obtain a wood specimen; (2) Mix the wood specimen and a graphene oxide solution and then hot-press to obtain a graphene-wood-based material; (3) Mix the graphene-wood-based material, a carbon nanotube-metal solution, and a trimethylolpropane triacrylate solution and then crosslink to obtain the electromagnetic shielding composite material.

[0006] Preferably, in step (1), the solvent for the delignification treatment is an NaClO2 solution, the mass fraction of the NaClO2 solution is 3-5 wt%, and the pH of the NaClO2 solution is 4-5.

[0007] Preferably, in step (1), the temperature of the delignification treatment is 90-100 °C, and the time is 16-24 h.

[0008] Preferably, in step (2), the concentration of the graphene oxide solution is 15-20 mg / mL; The mass-volume ratio of the wood specimen to the graphene oxide solution is 1 g: 10-15 mL.

[0009] Preferably, in step (2), the mixing time is 10-12 h, and the ultrasonic frequency is 30-50 kHz.

[0010] Preferably, in step (2), the temperature of the hot pressing is 80-95 °C, the pressure is 3-5 MPa, and the time is 4-6 h.

[0011] Preferably, in step (3), the carbon nanotube-metal solution contains carbon nanotubes, ferric chloride, manganese chloride, and ethylene glycol; The mass-volume ratio of the carbon nanotubes, ferric chloride, manganese chloride, and ethylene glycol is 5-10 mg: 0.5-1 g: 0.1-0.3 g: 25-35 mL; In step (3), the trimethylolpropane triacrylate solution contains trimethylolpropane triacrylate and N,N-dimethylformamide; The mass-volume ratio of the trimethylolpropane triacrylate to the N,N-dimethylformamide is 10-20 mg: 80-100 mL; In step (3), the mass-volume ratio of the graphene-wood-based material, the carbon nanotube-metal solution, and the trimethylolpropane triacrylate solution is 1 g: 200-300 mL: 600-800 mL.

[0012] Preferably, in step (3), the mixing temperature is 15-25 °C, and the time is 20-30 h; In step (3), the crosslinking temperature is 100-110 °C, and the time is 1-1.5 h.

[0013] The present invention also provides an electromagnetic shielding composite material prepared by the preparation method of the electromagnetic shielding composite material.

[0014] The present invention also provides the application of the electromagnetic shielding composite material in 5G communication devices.

[0015] The present invention provides an electromagnetic shielding composite material, whose matrix is a wood material; the present invention also provides a preparation method of the composite material, and the specific steps are as follows: (1) The paulownia wood is subjected to delignification treatment to obtain a wood specimen; (2) The wood specimen and the graphene oxide solution are mixed and then hot-pressed to obtain a graphene-wood-based material; (3) The graphene-wood-based material, the carbon nanotube-metal solution, and the trimethylolpropane triacrylate solution are mixed and crosslinked to obtain the electromagnetic shielding composite material. The present invention uses paulownia wood as the matrix material. Paulownia wood grows fast, has loose wood, and has many conduit structures. After removing lignin, a wood specimen with many pores can be formed, and the specific surface area is greatly increased. It can not only carry more materials, but also allow electromagnetic waves to be reflected multiple times in the internal three-dimensional structure, realizing the weakening of electromagnetic waves; secondly, graphene oxide is loaded on the wood specimen, and a conductive transition layer is formed on the wood surface by hot pressing. The high conductivity of graphene is conducive to the conduction and absorption of electromagnetic waves, effectively guiding the entry of electromagnetic waves and enhancing the electromagnetic shielding performance of the material. Finally, the graphene-wood-based material, the carbon nanotube-metal solution, and the trimethylolpropane triacrylate solution are mixed. The carbon nanotubes and the magnetic metal are arranged in an oriented manner in the composite coating. The carbon nanotubes and the metal material have excellent electromagnetic shielding and conductivity, achieving a high shielding effect; and under the action of temperature, the trimethylolpropane triacrylate is crosslinked, realizing the firm bonding of the material on the wood surface, and obtaining a surface coating structure with crosslinking enhancement.

[0016] The electromagnetic shielding composite material provided by the present invention has the characteristics of light weight, good processing performance, flexibility and high shielding, and can be applied to electronic devices with shape requirements to achieve the goal of efficient shielding of electromagnetic waves; the method provided by the present invention is simple, has low process requirements, and can be widely prepared on a large scale. Specific embodiments

[0017] The present invention provides a preparation method of an electromagnetic shielding composite material, which comprises the following steps: (1) The paulownia wood is subjected to delignification treatment to obtain a wood specimen; (2) The wood specimen and the graphene oxide solution are mixed and then hot-pressed to obtain a graphene-wood-based material; (3) The graphene-wood-based material, the carbon nanotube-metal solution, and the trimethylolpropane triacrylate solution are mixed and crosslinked to obtain the electromagnetic shielding composite material.

[0018] In the present invention, the solvent for the delignification treatment in step (1) is an NaClO2 solution, and the mass fraction of the NaClO2 solution is preferably 3 - 5 wt%, more preferably 3.5 - 4.5 wt%, and still more preferably 3.8 - 4.2 wt%; acetic acid is used to adjust the pH of the NaClO2 solution, and the pH of the NaClO2 solution is preferably 4 - 5, more preferably 4.2 - 4.8, and still more preferably 4.4 - 4.6.

[0019] In the present invention, the temperature for the delignification treatment in step (1) is preferably 90 - 100 °C, more preferably 92 - 98 °C, and still more preferably 94 - 96 °C; the time is preferably 16 - 24 h, more preferably 17 - 23 h, and still more preferably 18 - 20 h.

[0020] In the present invention, after the delignification treatment, it is washed thoroughly with water and dried to a constant weight after the washing is completed.

[0021] In the present invention, the concentration of the graphene oxide solution in step (2) is preferably 15 - 20 mg / mL, more preferably 16 - 19 mg / mL, and still more preferably 17 - 18 mg / mL.

[0022] In the present invention, the mass - to - volume ratio of the wood specimen to the graphene oxide solution is preferably 1 g: 10 - 15 mL, more preferably 1 g: 11 - 14 mL, and still more preferably 1 g: 12 - 13 mL.

[0023] In the present invention, the mixing time in step (2) is preferably 10 - 12 h, more preferably 10.5 - 11.5 h, and still more preferably 10.8 - 11.2 h; the ultrasonic frequency is preferably 30 - 50 kHz, more preferably 35 - 45 kHz, and still more preferably 38 - 42 kHz.

[0024] In the present invention, the temperature for the hot pressing in step (2) is preferably 80 - 95 °C, more preferably 85 - 90 °C, and still more preferably 88 - 89 °C; the pressure is preferably 3 - 5 MPa, more preferably 3.5 - 4.5 MPa, and still more preferably 3.8 - 4.2 MPa; the time is preferably 4 - 6 h, more preferably 4.5 - 5.5 h, and still more preferably 4.8 - 5.2 h.

[0025] In the present invention, the carbon nanotube - metal solution in step (3) contains carbon nanotubes, ferric chloride, manganese chloride, and ethylene glycol.

[0026] In the present invention, the mass-volume ratio of the carbon nanotubes, iron chloride, manganese chloride, and ethylene glycol is preferably 5-10 mg: 0.5-1 g: 0.1-0.3 g: 25-35 mL, more preferably 6-9 mg: 0.6-0.9 g: 0.15-0.25 g: 26-34 mL, and even more preferably 7-8 mg: 0.7-0.8 g: 0.18-0.22 g: 28-32 mL.

[0027] In the present invention, the trimethylolpropane triacrylate solution in step (3) contains trimethylolpropane triacrylate and N,N-dimethylformamide.

[0028] In the present invention, the mass-volume ratio of the trimethylolpropane triacrylate and N,N-dimethylformamide is preferably 10-20 mg: 80-100 mL, more preferably 12-18 mg: 85-95 mL, and even more preferably 14-16 mg: 88-92 mL.

[0029] In the present invention, the mass-volume ratio of the graphene-wood-based material, carbon nanotube-metal solution, and trimethylolpropane triacrylate solution in step (3) is preferably 1 g: 200-300 mL: 600-800 mL, more preferably 1 g: 220-280 mL: 650-750 mL, and even more preferably 1 g: 240-260 mL: 680-720 mL.

[0030] In the present invention, the temperature of the mixing in step (3) is preferably 15-25 °C, more preferably 16-24 °C, and even more preferably 18-22 °C; the time is preferably 20-30 h, more preferably 22-28 h, and even more preferably 24-26 h.

[0031] In the present invention, the temperature of the crosslinking in step (3) is preferably 100-110 °C, more preferably 102-108 °C, and even more preferably 104-106 °C; the time is preferably 1-1.5 h, more preferably 1.1-1.4 h, and even more preferably 1.2-1.3 h.

[0032] In the present invention, after the crosslinking is completed, it is washed thoroughly with water, and after the washing is completed, it is dried to a constant weight.

[0033] The present invention also provides an electromagnetic shielding composite material prepared by the preparation method of the electromagnetic shielding composite material.

[0034] The present invention also provides the application of the electromagnetic shielding composite material in 5G communication devices.

[0035] The following is a detailed description of the technical solutions provided by the present invention in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0036] Example 1

[0037] Take the peeled Firmiana simplex wood, place the Firmiana simplex wood in a 4 wt% NaClO2 solution (adjust the pH to 4.5 using acetic acid), keep the temperature at 95 °C and treat for 20 h. After the treatment, wash it thoroughly with distilled water and dry it to a constant weight in an oven to obtain a wood specimen; mix the wood specimen and a 18 mg / mL graphene oxide solution in a ratio of 1 g:10 mL, and ultrasonicate for 10 h under the condition of 40 kHz; take it out after ultrasonication and hot press it at 4 MPa and 90 °C for 5 h to obtain a graphene-wood-based material; prepare a carbon nanotube-metal solution by mixing carbon nanotubes, ferric chloride, manganese chloride and ethylene glycol in a ratio of 5 mg:0.6 g:0.2 g:30 mL; prepare a trimethylolpropane triacrylate solution by mixing trimethylolpropane triacrylate and N,N-dimethylformamide in a ratio of 15 mg:90 mL; mix the graphene-wood-based material, the carbon nanotube-metal solution and the trimethylolpropane triacrylate solution in a ratio of 1 g:250 mL:700 mL and mix at 20 °C for 25 h; then place it at 105 °C for crosslinking for 1 h; after crosslinking, wash it thoroughly with water and dry it to a constant weight after washing to obtain an electromagnetic shielding composite material.

[0038] Use a vector network analyzer to test the electromagnetic shielding effectiveness of the material. The electromagnetic shielding effectiveness is 82.2 dB at a frequency of 9 GHz, 82.7 dB at a frequency of 10 GHz, and 83.1 dB at a frequency of 11 GHz.

[0039] Example 2

[0040] Take the peeled plane tree wood, place the plane tree wood in a 3 wt% NaClO₂ solution (adjust the pH to 4.2 with acetic acid), keep the temperature at 92 °C and treat for 24 h. After the treatment, wash it thoroughly with distilled water and dry it to constant weight in an oven to obtain a wood specimen; mix the wood specimen and a 15 mg / mL graphene oxide solution in a ratio of 1 g:12 mL, and ultrasonicate for 11 h under the condition of 32 kHz; take it out after ultrasonication and hot press at 3.5 MPa and 82 °C for 4.5 h to obtain a graphene-wood-based material; configure a carbon nanotube-metal solution with carbon nanotubes, ferric chloride, manganese chloride and ethylene glycol in a ratio of 7 mg:1 g:0.1 g:34 mL; configure a trimethylolpropane triacrylate solution with trimethylolpropane triacrylate and N,N-dimethylformamide in a ratio of 12 mg:98 mL; mix the graphene-wood-based material, the carbon nanotube-metal solution and the trimethylolpropane triacrylate solution in a ratio of 1 g:230 mL:650 mL, and mix at 15 °C for 27 h; then place it at 110 °C for crosslinking for 1.3 h; after crosslinking, wash it thoroughly with water, and after washing, dry it to constant weight to obtain an electromagnetic shielding composite material.

[0041] Perform performance tests according to the method of Example 1. The electromagnetic shielding effectiveness is 82.1 dB at a frequency of 9 GHz, 82.3 dB at a frequency of 10 GHz, and 82.7 dB at a frequency of 11 GHz.

[0042] Example 3

[0043] Take the peeled plane tree wood, place the plane tree wood in a 4.8 wt% NaClO₂ solution (adjust the pH to 4.6 with acetic acid), keep the temperature at 97 °C and treat for 22 h. After the treatment, wash it thoroughly with distilled water and dry it to constant weight in an oven to obtain a wood specimen; mix the wood specimen and a 17 mg / mL graphene oxide solution in a ratio of 1 g:12.5 mL, and ultrasonicate for 10.5 h under the condition of 44 kHz; take it out after ultrasonication and hot press at 4.6 MPa and 92 °C for 5 h to obtain a graphene-wood-based material; configure a carbon nanotube-metal solution with carbon nanotubes, ferric chloride, manganese chloride and ethylene glycol in a ratio of 8 mg:0.7 g:0.3 g:28 mL; configure a trimethylolpropane triacrylate solution with trimethylolpropane triacrylate and N,N-dimethylformamide in a ratio of 14 mg:86 mL; mix the graphene-wood-based material, the carbon nanotube-metal solution and the trimethylolpropane triacrylate solution in a ratio of 1 g:260 mL:740 mL, and mix at 23 °C for 30 h; then place it at 100 °C for crosslinking for 1 h; after crosslinking, wash it thoroughly with water, and after washing, dry it to constant weight to obtain an electromagnetic shielding composite material.

[0044] The performance test was carried out according to the method of Example 1. The electromagnetic shielding effectiveness was 82.3 dB at a frequency of 9 GHz, 82.4 dB at a frequency of 10 GHz, and 82.6 dB at a frequency of 11 GHz.

[0045] Example 4

[0046] Take peeled Firmiana simplex wood, place the Firmiana simplex wood in a 3.5 wt% NaClO2 solution (adjust the pH to 5 with acetic acid), keep the temperature at 96 °C for 18 h, after the treatment, wash it thoroughly with distilled water, and dry it to a constant weight in an oven to obtain a wood specimen; mix the wood specimen and a 20 mg / mL graphene oxide solution in a ratio of 1 g:14.5 mL, and ultrasonicate it for 11 h under the condition of 35 kHz; after the ultrasonication, take it out and hot press it at 5 MPa and 84 °C for 4 h to obtain a graphene-wood-based material; configure a carbon nanotube-metal solution with carbon nanotubes, ferric chloride, manganese chloride and ethylene glycol in a ratio of 6 mg:0.6 g:0.1 g:30 mL; configure a trimethylolpropane triacrylate solution with trimethylolpropane triacrylate and N,N-dimethylformamide in a ratio of 18 mg:90 mL; mix the graphene-wood-based material, the carbon nanotube-metal solution and the trimethylolpropane triacrylate solution in a ratio of 1 g:300 mL:650 mL, and mix them at 20 °C for 24 h; then place them at 105 °C for crosslinking for 1.5 h; after the crosslinking, wash it thoroughly with water, and after the washing, dry it to a constant weight to obtain an electromagnetic shielding composite material.

[0047] The performance test was carried out according to the method of Example 1. The electromagnetic shielding effectiveness was 82.4 dB at a frequency of 9 GHz, 82.5 dB at a frequency of 10 GHz, and 83.2 dB at a frequency of 11 GHz.

[0048] As can be seen from the above examples, the electromagnetic shielding composite material provided by the present invention has the characteristics of light weight, good processing performance, flexibility and high shielding. The electromagnetic shielding effectiveness reaches 82.4 dB at a frequency of 9 GHz, 82.7 dB at a frequency of 10 GHz, and 83.2 dB at a frequency of 11 GHz. It is an electromagnetic shielding material with excellent performance.

[0049] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of an electromagnetic shielding composite material, characterized in that, It includes the following steps: (1) Carry out delignification treatment on Chinese parasol tree wood to obtain wood specimens; (2) Mix the wood specimens and graphene oxide solution and then hot-press to obtain graphene-wood-based materials; (3) Mix the graphene-wood-based materials, carbon nanotube-metal solution, and trimethylolpropane triacrylate solution and crosslink them to obtain the electromagnetic shielding composite material.

2. The preparation method of the electromagnetic shielding composite material according to claim 1, wherein, In step (1), the solvent for the delignification treatment is NaClO2 solution, the mass fraction of the NaClO2 solution is 3-5 wt%, and the pH of the NaClO2 solution is 4-5.

3. The preparation method of the electromagnetic shielding composite material according to claim 2, characterized in that, In step (1), the temperature of the delignification treatment is 90-100 °C, and the time is 16-24 h.

4. The preparation method of the electromagnetic shielding composite material according to claim 3, wherein In step (2), the concentration of the graphene oxide solution is 15-20 mg / mL; The mass-volume ratio of the wood specimens to the graphene oxide solution is 1 g: 10-15 mL.

5. The preparation method of the electromagnetic shielding composite material according to claim 4, characterized in that, In step (2), the mixing time is 10-12 h, and the ultrasonic frequency is 30-50 kHz.

6. The preparation method of the electromagnetic shielding composite material according to claim 5, characterized in that, In step (2), the temperature of the hot pressing is 80-95 °C, the pressure is 3-5 MPa, and the time is 4-6 h.

7. The preparation method of the electromagnetic shielding composite material according to claim 6, characterized in that In step (3), the carbon nanotube-metal solution contains carbon nanotubes, ferric chloride, manganese chloride, and ethylene glycol; The mass-volume ratio of the carbon nanotubes, ferric chloride, manganese chloride, and ethylene glycol is 5-10 mg: 0.5-1 g: 0.1-0.3 g: 25-35 mL; In step (3), the trimethylolpropane triacrylate solution contains trimethylolpropane triacrylate and N,N-dimethylformamide; The mass-volume ratio of the trimethylolpropane triacrylate to the N,N-dimethylformamide is 10-20 mg: 80-100 mL; In step (3), the mass-volume ratio of the graphene-wood-based materials, carbon nanotube-metal solution, and trimethylolpropane triacrylate solution is 1 g: 200-300 mL: 600-800 mL.

8. The preparation method of the electromagnetic shielding composite material according to claim 7, characterized in that, In step (3), the mixing temperature is 15-25 °C, and the time is 20-30 h; In step (3), the crosslinking temperature is 100-110 °C, and the time is 1-1.5 h.

9. The electromagnetic shielding composite material prepared by the preparation method of the electromagnetic shielding composite material according to any one of claims 1-8.

10. The application of the electromagnetic shielding composite material according to claim 9 in 5G communication equipment.