Method for manufacturing electromagnetic shielding film and electromagnetic shielding film

Abstract

The present invention discloses a method for manufacturing an electromagnetic shielding film and an electromagnetic shielding film, the method comprising: providing a prefabricated carbon nanotube dispersion; adding special engineering plastics to the carbon nanotube dispersion, and adding a viscosity regulator and a surface wetting agent to obtain a polyetherimide solution of a predetermined viscosity; immersing metal fibers in the polyetherimide solution to obtain metal core conductive fibers coated with carbon nanotube-modified polyetherimide; weaving the metal core conductive fibers to obtain a fiber woven cloth; pressing a polyetheretherketone film on the surface of the fiber woven cloth to obtain an electromagnetic shielding film. The electromagnetic shielding film obtained by the present invention has an electromagnetic shielding energy efficiency of ≥30dB, which improves its shielding energy efficiency, and has the characteristics of high strength, corrosion resistance, wear resistance, good flexibility, and weldability.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic shielding, and in particular to a method for manufacturing an electromagnetic shielding film and the electromagnetic shielding film. Background Art

[0002] Current electrical and electronic equipment will radiate a large amount of electromagnetic waves during use, which poses a significant hazard to the normal and safe operation of electronic equipment and the living environment of human beings. With the rapid increase in the number of various wireless communication systems and high-frequency electronic devices, electromagnetic interference and electromagnetic pollution problems have become increasingly prominent. In related technologies, existing blended fabrics are mostly ordinary wearable products, which can achieve electromagnetic shielding effects through polymer fiber electroplating, but the shielding efficiency of blended fabrics is limited, the product performance stability is poor, and the shielding efficiency per unit thickness is low; especially in high temperature, high humidity, acid and alkali environments, metal electromagnetic shielding materials have problems such as poor corrosion resistance. Similarly, ordinary plastic electromagnetic shielding modified materials have defects such as poor temperature resistance and chemical resistance. Summary of the invention

[0003] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, one object of the present invention is to provide a method for manufacturing an electromagnetic shielding film, comprising:

[0004] providing a pre-made carbon nanotube dispersion;

[0005] Adding special engineering plastics, viscosity modifiers and surface wetting agents to the carbon nanotube dispersion to obtain a polyetherimide solution with a predetermined viscosity;

[0006] Immersing the metal fiber in the polyetherimide solution to obtain a metal core conductive fiber coated with carbon nanotube-modified polyetherimide;

[0007] Weaving the metal core conductive fibers to obtain a fiber woven cloth;

[0008] A polyetheretherketone film is pressed on the surface of the fiber woven cloth to obtain an electromagnetic shielding film.

[0009] Optionally, the method for prefabricating the carbon nanotube dispersion comprises:

[0010] Providing a mixed solvent;

[0011] Add a dispersing aid and carbon nanotubes or sulfonated nanotubes into the mixed solvent and disperse under predetermined temperature and ultrasonic conditions to obtain a carbon nanotube dispersion with a content of 0.1-3wt%; the dispersing aid accounts for 3-30% of the mass of the carbon nanotubes.

[0012] Optionally, the mixed solvent comprises at least one or more of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, tetramethylene sulfone (sulfolane), diphenyl sulfone and chloroform.

[0013] Optionally, the step of adding special engineering plastics to the carbon nanotube dispersion, and adding a viscosity modifier and a surface wetting agent to obtain a polyetherimide solution of a predetermined viscosity comprises:

[0014] Adding special engineering plastics to the carbon nanotube dispersion to prepare the polyetherimide solution; the special engineering plastics include PEI, or one or more polymer mixtures including 10-40% by mass of PEI, including PAI, PES, PPSU, PSU, PEK-C

[0015] 0.1-1 wt % of the viscosity modifier and 0.1-1 wt % of the surface wetting agent are added to the polyetherimide solution to adjust the polyetherimide solution to a predetermined viscosity; the predetermined viscosity is 350-5000 mPa.s.

[0016] Optionally, the step of immersing the metal fiber in the polyetherimide solution to obtain a metal core conductive fiber coated with carbon nanotube-modified polyetherimide comprises:

[0017] Degreasing the metal fiber with a diameter of 6-100 um, and immersing the metal fiber in the polyetherimide solution after degreasing;

[0018] After the immersion is completed, the metal fiber is baked at a temperature of 100-350° C. for 1-10 minutes to remove the mixed solvent, the viscosity modifier and the surface wetting agent to obtain a metal core conductive fiber coated with carbon nanotube-modified polyetherimide.

[0019] Optionally, pressing a polyetheretherketone film on the surface of the fiber woven cloth to obtain an electromagnetic shielding film comprises:

[0020] Preheating the fiber woven cloth and the polyetheretherketone film at 230-280° C., and then subjecting the polyetheretherketone film to corona discharge treatment;

[0021] The polyetheretherketone film after corona discharge is coated on the surface of the fiber woven cloth, and is pressed by a pressing roller or a pressing plate at a temperature of 280-330° C. and a pressure of 0.5-3 Mpa to obtain the electromagnetic shielding film.

[0022] Optionally, the polyetheretherketone film has at least one frosted surface, and the roughness of the frosted surface is Ra0.4-Ra25.

[0023] Optionally, the thickness of the polyetheretherketone film is 5-500 um, the output voltage of the corona discharge is 2-100 kV, and the discharge frequency is 2-100 kHz.

[0024] Another object of the present invention is to provide an electromagnetic shielding film, comprising:

[0025] A braided layer, wherein the braided layer is braided from a plurality of bundles of metal core conductive fibers;

[0026] A film layer is coated on the surface of the braided layer and is integrated with the braided layer.

[0027] Optionally, the film layer has at least one frosted surface, and the frosted surface is in contact with the woven layer.

[0028] The method for making an electromagnetic shielding film provided by the present invention is as follows: first, special engineering plastics are added to a prefabricated carbon nanotube dispersion for treatment so that the carbon nanotube dispersion can be processed to form a polyetherimide solution, and then a viscosity regulator and a surface wetting agent are added to the polyetherimide solution, so that the viscosity of the polyetherimide solution can be adjusted to a predetermined viscosity, and finally the metal fiber is pulled and immersed in the polyetherimide solution, and after pulling, the mixed solvent, the viscosity regulator and the surface wetting agent are removed by baking, so that a metal core conductive fiber coated with carbon nanotube modified polyetherimide can be obtained, and a fiber woven cloth can be obtained by weaving the metal core conductive fiber, thereby using the fiber woven cloth as a sandwich, and pressing polyetheretherketone film is coated on both sides of the fiber woven cloth, and it is pressed into one by a pressing roller or a pressing plate, thereby obtaining an electromagnetic shielding film; the electromagnetic shielding film obtained by the present invention has an electromagnetic shielding energy efficiency ≥30dB, so that its shielding energy efficiency is further improved, and has the characteristics of high strength, corrosion resistance, wear resistance, good flexibility, and weldability.

[0029] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0031] Figure 1 is a schematic structural diagram of an electromagnetic shielding film provided in an embodiment of the present invention;

[0032] Figure 2 is a cross-sectional view of an electromagnetic shielding film provided in an embodiment of the present invention.

[0033] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0034] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but are not to be construed as limiting the present invention. All other embodiments obtained by ordinary technicians in the field without creative work based on the embodiments of the present invention are within the scope of protection of the present invention.

[0035] The following describes in detail a method for manufacturing an electromagnetic shielding film and an electromagnetic shielding film according to an embodiment of the present invention with reference to the accompanying drawings.

[0036] Reference Figure 1 and Figure 2 As shown, the method for manufacturing an electromagnetic shielding film provided in an embodiment of the present invention comprises:

[0037] S10, providing a prefabricated carbon nanotube dispersion;

[0038] S20, adding special engineering plastics to the carbon nanotube dispersion, and adding a viscosity modifier and a surface wetting agent to obtain a polyetherimide solution of a predetermined viscosity;

[0039] S30, immersing the metal fiber in a polyetherimide solution to obtain a metal core conductive fiber coated with carbon nanotube-modified polyetherimide;

[0040] S40, weaving the metal core conductive fibers to obtain a fiber woven cloth;

[0041] S50, pressing a polyetheretherketone film on the surface of the fiber woven cloth to obtain an electromagnetic shielding film.

[0042] The method for making an electromagnetic shielding film provided by the present invention is as follows: first, special engineering plastics are added to a prefabricated carbon nanotube dispersion for treatment so that the carbon nanotube dispersion can be processed to form a polyetherimide solution, and then a viscosity regulator and a surface wetting agent are added to the polyetherimide solution, so that the viscosity of the polyetherimide solution can be adjusted to a predetermined viscosity, and finally the metal fiber is pulled and immersed in the polyetherimide solution, and after pulling, the mixed solvent, the viscosity regulator and the surface wetting agent are removed by baking, so that a metal core conductive fiber coated with carbon nanotube modified polyetherimide can be obtained, and a fiber woven cloth can be obtained by weaving the metal core conductive fiber, thereby using the fiber woven cloth as a sandwich, and pressing polyetheretherketone film is coated on both sides of the fiber woven cloth, and it is pressed into one by a pressing roller or a pressing plate, thereby obtaining an electromagnetic shielding film; the electromagnetic shielding film obtained by the present invention has an electromagnetic shielding energy efficiency ≥30dB, so that its shielding energy efficiency is further improved, and has the characteristics of high strength, corrosion resistance, wear resistance, good flexibility, and weldability.

[0043] Specifically, in the above step S10, the method for prefabricating the carbon nanotube dispersion includes: providing a mixed solvent; adding a dispersing aid and carbon nanotubes or sulfonated nanotubes to the mixed solvent, and dispersing under predetermined temperature conditions and ultrasonic conditions to obtain a carbon nanotube dispersion with a content of 0.1-3wt%; the dispersing aid is 3-30% of the mass of the carbon nanotubes.

[0044] In this embodiment, the predetermined temperature condition can be 3-100°C, the predetermined ultrasonic condition can be 50-500W, and the mixed solvent includes at least one or more of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, tetramethylene sulfone (cyclobutyl sulfone), diphenyl sulfone, and chloroform; when dispersing carbon nanotubes or sulfonated carbon nanotubes, a carbon nanotube water dispersant (TNWDIS) can be added, and the mixed solvent is added at the same time, and then the temperature is controlled at 30-100°C, and ultrasonic dispersion is performed under ultrasonic conditions with a power of 50-500W, thereby obtaining a carbon nanotube dispersion.

[0045] Specifically, the above step S20 includes: adding special engineering plastics to the carbon nanotube dispersion to prepare a polyetherimide solution; the special engineering plastics include PEI, or a polymer mixture of PAI, PES, PPSU, PSU, PEK-C with a content of 10-40% by mass of PEI; adding 0.1-1wt% of a viscosity regulator and 0.1-1% of a surface wetting agent to the polyetherimide solution to adjust the polyetherimide solution to a predetermined viscosity; the predetermined viscosity is 350-5000mPa.s.

[0046] In this embodiment, the content of the mixed solvent in the polyetherimide solution is 40-80wt%, and the rest is filler and solutes such as PEI or PEI mixture and dispersing aids; the special engineering plastics may include polyetherimide PEI, or a mixture of polyetherimide PEI and one or more of polyimide PAI, polyethersulfone PES, polyphenylene sulfone PPSU, polysulfone PSU, and polyaryletherketone PEK-C. It can be understood that the 10-40% content of PEI mass means that the PEI mass proportion in the obtained polymer mixture is 10-40%; the characteristic engineering plastics and the carbon nanotube dispersion are mixed to obtain a polyetherimide solution, and after adding a viscosity regulator and a surface wetting agent to the polyetherimide solution, the viscosity can reach 350-5000mPa.s, and when the metal fiber is immersed, the adhesion can be higher and the viscosity can be better.

[0047] Optionally, immersing the metal fiber in a polyetherimide solution to obtain a metal core conductive fiber coated with carbon nanotube-modified polyetherimide, comprising: degreasing the metal fiber with a diameter of 6-100 um, and immersing it in a polyetherimide solution after the degreasing treatment; after the immersion is completed, baking the metal fiber at a temperature of 100-350°C for 1-10 minutes to remove the mixed solvent, viscosity regulator and surface wetting agent to obtain a metal core conductive fiber coated with carbon nanotube-modified polyetherimide.

[0048] In this embodiment, 1-50 strands of metal fibers can be used as a bundle for weaving, and the weaving method can be the same as the existing weaving method. During the weaving process, the metal fibers can be pulled first, and degreased in the middle of the pulling process, and then immersed in polyetherimide for soaking. After the soaking is completed, they can be baked at high temperature to remove the viscosity regulator and the surface wetting agent. After the removal is completed, multiple bundles of metal fibers are wound and woven under the traction of the machine to obtain a fiber woven cloth; optionally, the diameter of the metal fiber can be 6-50um, and more preferably 10-20um can be used for PEI solution coating, baking and weaving.

[0049] Specifically, the above step S50 includes: preheating the fiber woven cloth and the polyetheretherketone film at 230-280°C, and then subjecting the polyetheretherketone film to corona discharge treatment; coating the polyetheretherketone film after corona discharge on the surface of the fiber woven cloth, and using a pressing roller or a pressing plate to press and form it at a temperature of 280-330°C and a pressure of 0.5-3Mpa to obtain an electromagnetic shielding film.

[0050] In this embodiment, the polyetheretherketone film has at least one frosted surface, and the roughness of the frosted surface is Ra0.4-Ra25; when the polyetheretherketone film and the fiber woven cloth are pressed into shape, the fiber woven cloth and the polyetheretherketone film can be preheated first, and the polyetheretherketone film can be corona discharged after preheating. The surface of the polyetheretherketone film after corona discharge treatment can increase the surface roughness and surface activity, so that it has higher adhesion, and then after the corona discharge treatment, the frosted surface of the polyetheretherketone film and the fiber woven cloth are bonded and then enter the pressing roller or pressing plate for pressing to obtain an electromagnetic shielding film; optionally, the frosted surface of the polyetheretherketone film needs to be controlled within the 1-300s stroke range before pressing during the corona discharge process; and the thickness of the polyetheretherketone film is 5-2000um, the output voltage of the corona discharge is 2-100kV, and the discharge frequency is 2-100kHz.

[0051] Reference Figure 2 As shown, the electromagnetic shielding membrane provided in an embodiment of the present invention includes a woven layer 10 and a thin film layer 20. The woven layer 10 is woven from multiple bundles of metal core conductive fibers; the thin film layer 20 is coated on the surface of the woven layer 10 and formed as a whole with the woven layer 10; and the thin film layer 20 has at least one frosted surface, and the frosted surface is in contact with the woven layer 10.

[0052] In this embodiment, the film layer 20 can be the above-mentioned polyetheretherketone film, or other films can be used. The woven layer 10 can be obtained by being processed by the above-mentioned manufacturing method and then woven, and when the film layer 20 and the woven layer 10 are pressed into shape, they can be pressed by the above-mentioned manufacturing method. Of course, technical personnel in this field can also use other methods for pressing and forming. Therefore, the electromagnetic shielding film obtained by the present invention has an electromagnetic shielding energy efficiency of ≥30dB, which makes its shielding energy efficiency higher, and has the characteristics of high strength, corrosion resistance, wear resistance, good flexibility, and weldability.

[0053] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0054] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for manufacturing an electromagnetic shielding film, characterized in that: include: providing a pre-made carbon nanotube dispersion; Adding polyetherimide to the carbon nanotube dispersion, and adding a viscosity modifier and a surface wetting agent to obtain a polyetherimide solution with a predetermined viscosity; Immersing the metal fiber in the polyetherimide solution to obtain a metal core conductive fiber coated with carbon nanotube-modified polyetherimide; Weaving the metal core conductive fibers to obtain a fiber woven cloth; Pressing a polyetheretherketone film on the surface of the fiber woven cloth to obtain an electromagnetic shielding film; The method for prefabricating the carbon nanotube dispersion comprises: Providing a mixed solvent; Adding a dispersing aid and carbon nanotubes to the mixed solvent, and dispersing under a predetermined temperature and ultrasonic conditions to obtain a carbon nanotube dispersion with a content of 0.1-3wt%; the dispersing aid is 3-30% of the mass of the carbon nanotubes; The method of pressing a polyetheretherketone film on the surface of the fiber woven cloth to obtain an electromagnetic shielding film comprises: Preheating the fiber woven cloth and the polyetheretherketone film at 230-280° C., and then subjecting the polyetheretherketone film to corona discharge treatment; The polyetheretherketone film after corona discharge is coated on the surface of the fiber woven cloth, and is pressed by a pressing roller or a pressing plate at a temperature of 280-330° C. and a pressure of 0.5-3 Mpa to obtain the electromagnetic shielding film.

2. The method for manufacturing an electromagnetic shielding film according to claim 1, characterized in that: The mixed solvent is obtained by mixing one or more of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, tetramethylene sulfone (sulfolane), diphenyl sulfone and chloroform.

3. The method for manufacturing an electromagnetic shielding film according to claim 1, characterized in that: 0.1-1 wt % of the viscosity modifier and 0.1-1 wt % of the surface wetting agent are added to the polyetherimide solution to adjust the polyetherimide solution to a predetermined viscosity; the predetermined viscosity is 350-5000 mPa.s.

4. The method for producing an electromagnetic shielding film according to claim 1 or 2, characterized in that: The step of immersing the metal fiber in the polyetherimide solution to obtain a metal core conductive fiber coated with carbon nanotube-modified polyetherimide comprises: Degreasing the metal fiber with a diameter of 6-100 um, and immersing the metal fiber in the polyetherimide solution after degreasing; After the immersion is completed, the metal fiber is baked at a temperature of 100-350° C. for 1-10 minutes to remove the mixed solvent, the viscosity modifier and the surface wetting agent to obtain a metal core conductive fiber coated with carbon nanotube-modified polyetherimide.

5. The method for manufacturing an electromagnetic shielding film according to claim 1, characterized in that: The polyetheretherketone film has at least one frosted surface.

6. The method for producing an electromagnetic shielding film according to claim 1 or 5, characterized in that: The thickness of the polyetheretherketone film is 5-2000um, the output voltage of the corona discharge is 2-100kV, and the discharge frequency is 2-100kHz.

7. An electromagnetic shielding film, characterized in that: The electromagnetic shielding film is prepared by the preparation method according to any one of claims 1 to 6.

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