Shielded power line and preparation method thereof

Abstract

The invention relates to the technical field of wires and cables, and provides a shielding power line which comprises a conductor layer. The insulating layer is coated outside the conductor layer; the shielding layer is coated outside the insulating layer, and the shielding layer is a graphene composite coating formed by electrostatic spraying and hot-pressing curing; the outer sheath is coated outside the shielding layer; wherein the graphene composite coating is prepared from three-dimensional graphene, polypyrrole and nano silver. The insulating layer, the composite shielding layer with graphene and the outer sheath are sequentially arranged on the surface of the conductor layer, and the graphene composite shielding layer adopts a spraying process to replace complex metal weaving, so that the process is simplified, and the production efficiency can be improved by more than 50%; meanwhile, the unit area cost of the graphene composite shielding layer is lower than that of a copper braid layer, and the comprehensive material and manufacturing cost is reduced by about 15%; the density of the graphene composite material is far lower than that of copper, so that the overall weight of the cable is reduced by more than 38%, and the weight reduction requirement of a new energy automobile is effectively met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric wire and cable, in particular to a shielded power cord and a preparation method thereof. BACKGROUND

[0002] With the rapid development of new energy vehicles, its high-voltage electrical system puts forward higher requirements on the connecting cable: it needs to have large current carrying capacity, excellent electromagnetic shielding performance, good flexibility and light weight characteristics to meet the vehicle layout, safety and energy efficiency requirements.

[0003] At present, the traditional high-voltage cable structure commonly used in the industry is: conductor (multi-stranded copper stranded wire) + insulation layer (such as cross-linked polyethylene XLPE) + shielding layer (copper wire braiding or aluminum foil composite shielding) + outer sheath. For large cross-sectional area (such as 70mm2 and above) cables, the traditional structure has the following obvious shortcomings:

[0004] Cost and efficiency: copper braided shielding process is complex, relying on manual or special braiding equipment, low production efficiency, and high cost of copper material; Weight: high-density metal shielding layer significantly increases the overall weight of the cable, which is contrary to the lightweight design trend of new energy vehicles; Shielding effectiveness: copper braided shielding is prone to electromagnetic leakage due to gaps at high frequencies (>10MHz), and the shielding effectiveness (SE) decreases, making it difficult to effectively suppress high-frequency electromagnetic interference (EMI); Flexibility: large cross-sectional area cables have high rigidity, and the structure of the metal shielding layer limits the minimum bending radius to 10-12 times the diameter of the cable, making it difficult to lay in narrow spaces in the vehicle, and the shielding layer is prone to fatigue damage after repeated bending; Therefore, there is an urgent market demand and technical value to develop a new type of large square automobile high-voltage cable with low cost, light weight, high shielding effectiveness and excellent flexibility. SUMMARY

[0005] In view of the high cost of metal braiding, slow production efficiency, high weight, and insufficient high-frequency shielding effectiveness of the prior art, the present application aims to provide a shielded power cord and a preparation method thereof.

[0006] To solve the above problems, the present application provides the following technical solutions: A shielded power cord, comprising: a conductor layer; An insulation layer covering the conductor layer; A shielding layer covering the insulation layer, the shielding layer being a graphene composite coating formed by electrostatic spraying and hot pressing and curing; An outer sheath covering the shielding layer; The graphene composite coating comprises three-dimensional graphene, polypyrrole and nano-silver.

[0007] In some embodiments, in the graphene composite coating, the mass ratio of three-dimensional graphene, polypyrrole and nano-silver is 4:1:0.1.

[0008] In some embodiments, the cross-sectional area of the conductor layer is 60mm2-80mm2, and the conductor layer is twisted by multiple strands of tinned copper wires, and the twisting pitch is less than or equal to 15 times the diameter of a single wire.

[0009] In some embodiments, the materials of the insulating layer and the outer sheath are both cross-linked polyethylene.

[0010] The embodiment also provides a preparation method of the shielding power line, comprising the shielding power line as described above, and comprising the following steps: S1. preparing a wire core with an insulating layer; S2. cleaning and activating the outer surface of the insulating layer of the wire core; S3. preparing a graphene composite coating material comprising three-dimensional graphene, polypyrrole and nano-silver; S4. spraying the graphene composite coating material to the surface of the treated wire core by electrostatic spraying; S5. heat-pressing and curing the sprayed wire core to form the graphene composite coating; S6. extruding and sheathing an outer sheath outside the cured shielding layer In some embodiments, in step S3, the mass ratio of three-dimensional graphene, polypyrrole and nano-silver is 4:1:0.1.

[0011] In some embodiments, in step S4, the voltage of electrostatic spraying is 40-60kV.

[0012] In some embodiments, in step S5, the temperature range of heat-pressing and curing is 160-200℃, the pressure range is 8-12MPa, and the time range is 5-15 minutes.

[0013] In some embodiments, in step S2, the activation treatment is plasma treatment or ultraviolet light treatment.

[0014] In some embodiments, in step S3, the graphene composite coating material further comprises an organic solvent and a binder, the organic solvent is N-methyl pyrrolidone, and the binder is epoxy resin.

[0015] The beneficial effects of the present application are: by sequentially arranging the insulating layer, the graphene composite shielding layer and the outer sheath on the surface of the conductor layer, the graphene composite shielding layer adopts a spraying process to replace complex metal weaving, the process is simplified, and the production efficiency can be improved by more than 50%; at the same time, the unit area cost of the graphene composite shielding layer is lower than that of the copper woven layer, and the comprehensive material and manufacturing cost is reduced by about 15%; The density of the graphene composite material is much lower than that of copper, so that the overall weight of the cable is reduced by more than 38%, effectively supporting the weight reduction demand of new energy vehicles; the shielding effectiveness in the high frequency band (> 10MHz) is improved by up to 40dB compared with the traditional copper woven layer, which can more effectively suppress electromagnetic interference; The minimum bending radius of the cable can be reduced to 7 times the outer diameter, greatly improving the wiring flexibility and space adaptability. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a perspective view of the shielding power cable of the present application; Figure 2 It is a process flow chart of the preparation method of the shielding power cable of the present application.

[0017] Reference signs: Conductor layer 100; insulating layer 200; shielding layer 300; outer sheath 400. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0019] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0020] For the convenience of describing the first direction, the second direction and the third direction in the embodiments of the present application, the first direction is the left-right direction in the drawings, the second direction is the front-rear direction in the drawings, and the third direction is the up-down direction in the drawings. Among them, the x-axis arrow direction is as "right" direction in the following, the y-axis arrow direction is as "up" direction in the following, and the z-axis arrow direction is as "back" direction in the following. In the actual application of the present application, it is not limited to this.

[0021] AsFigure 1 As shown, this embodiment provides a shielded power cord, which includes a conductor layer 100; An insulating layer 200 covering the conductor layer 100; A shielding layer 300 covering the insulating layer 200 is a graphene composite coating formed by electrostatic spraying and hot pressing curing. An outer sheath 400 covering the shielding layer 300; The graphene composite coating comprises three-dimensional graphene, polypyrrole, and nano-silver.

[0022] Reference Figure 1 A shielded power cord, comprising, from the inside out: Conductor layer 100: It is made of multiple strands of tin-plated soft copper wire with a diameter of 0.2mm, with a cross-sectional area of ​​70mm² and a stranding pitch of 12 times the diameter of a single wire.

[0023] Insulation layer 200: XLPE (cross-linked polyethylene) layer with a thickness of 2.0 mm and a long-term operating temperature of 125℃.

[0024] Shielding layer 300: A graphene composite coating with a thickness of 0.15 mm. Its raw materials, by mass ratio, are: 4 parts three-dimensional graphene, 1 part polypyrrole, and 0.1 parts nano-silver. The volume resistivity of this coating is less than 0.05 Ω·cm.

[0025] Outer sheath 400: 1.5mm thick black XLPE layer.

[0026] like Figure 1 As shown, in this embodiment, the mass ratio of three-dimensional graphene, polypyrrole and nano-silver in the graphene composite coating is 4:1:0.1.

[0027] like Figure 1 As shown, in this embodiment, the conductor layer 100 has a cross-sectional area of ​​60 mm² to 80 mm², and is composed of multiple strands of tin-plated copper wire twisted together, with a twist pitch less than or equal to 15 times the diameter of a single wire. In this embodiment, the conductor layer 100 has a cross-sectional area of ​​70 mm².

[0028] like Figure 1 As shown, in this embodiment, both the insulating layer 200 and the outer sheath 400 are made of XLPE (cross-linked polyethylene).

[0029] like Figure 2 As shown, this embodiment also provides a method for preparing a shielded power cord, including the shielded power cord as described above, comprising the following steps: S1. Preparing a wire core with an insulation layer 200; S2. The outer surface of the insulation layer 200 of the wire core is cleaned and activated; S3. Preparation of graphene composite coatings containing three-dimensional graphene, polypyrrole and nano-silver; S4. Apply the graphene composite coating to the treated wire core surface using electrostatic spraying; S5. The coated wire core is hot-pressed and cured to form the graphene composite coating; S6. Extrude an outer sheath 400 onto the cured shielding layer 300.

[0030] (1) A wire core with an XLPE insulation layer 200 was prepared by conventional process.

[0031] (2) Plasma treatment is performed on the surface of the insulated wire core to improve the adhesion of the coating.

[0032] (3) 40g of three-dimensional graphene, 10g of polypyrrole and 1g of nano silver were dispersed in a mixture containing 200g of N-methylpyrrolidone and 50g of epoxy resin (E-44), and dispersed by ultrasonication and high-speed shearing (5000 rpm, 30 min) to obtain a uniform coating.

[0033] (4) Use an automatic electrostatic spraying equipment to spray the coating onto the surface of the treated wire core at a voltage of 50kV, and control the wet film thickness to about 0.25mm.

[0034] (5) The coated wire core is sent into a continuous hot press and treated at 180°C and 10MPa pressure for 10 minutes to allow the coating to fully cure.

[0035] (6) Finally, XLPE outer sheath 400 is extruded over the shielding layer 300, cooled and then wound up to obtain the finished product.

[0036] like Figure 2 As shown, in this embodiment, in step S3, the mass ratio of the three-dimensional graphene, polypyrrole and nanosilver is 4:1:0.1.

[0037] like Figure 2 As shown, in this embodiment, the voltage for electrostatic spraying in step S4 is 40-60 kV.

[0038] like Figure 2 As shown, in this embodiment, in step S5, the temperature range of hot pressing curing is 160-200℃, the pressure range is 8-12 MPa, and the time range is 5-15 minutes.

[0039] like Figure 2 As shown, in this embodiment, in step S2, the activation treatment is plasma treatment or ultraviolet light treatment.

[0040] like Figure 2As shown, in this embodiment, in step S3, the graphene composite coating further includes an organic solvent and a binder, wherein the organic solvent is N-methylpyrrolidone and the binder is epoxy resin.

[0041] Optionally, a flame-retardant layer is provided between the shielding layer 300 and the outer jacket layer. The flame-retardant layer material is flame-retardant polyolefin, and the thickness of the flame-retardant layer is 0.25-0.30mm. After prolonged use, electrical wires require regular inspection and maintenance. Aging wires need to be replaced promptly. Generally, electrical wires have poor flame-retardant resistance and frequently burn during use, causing fires. Therefore, it is necessary to improve the flame-retardant resistance of the wires. This can be achieved by wrapping a flame-retardant layer around the outside of the shielding layer 300. The flame-retardant layer has good flame-retardant effect and is relatively environmentally friendly, thus improving the flame-retardant resistance of the wires.

[0042] Alternatively, the traditional metal braided shielding layer 300 is a dense metal and is resistant to moisture. However, the graphene composite coating, as a porous nanomaterial system, may be threatened by moisture intrusion and electrolytic corrosion in its long-term shielding stability.

[0043] In this embodiment, a hydrophobic passivation layer is added between the insulating layer 200 and the graphene composite shielding layer 300 in the shielded power cable. This layer, approximately 0.5-2 micrometers in size, is a monolayer or thin film formed on the surface of the insulating layer 200 using a fluorosilane coupling agent through vapor deposition or impregnation. This makes the surface of the insulating layer 200 superhydrophobic (water contact angle >150°), effectively preventing water molecules from accumulating at the interface and isolating any trace ions that may precipitate from the insulating layer 200, thus protecting the graphene shielding layer 300 from electrochemical corrosion.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A shielded power cord, characterized by The shielding power line comprises: a conductor layer; an insulating layer covering the conductor layer; a shielding layer covering the insulating layer, the shielding layer being a graphene composite coating formed by electrostatic spraying and heat pressing solidification; an outer sheath covering the shielding layer; wherein the graphene composite coating comprises three-dimensional graphene, polypyrrole and nano-silver.

2. The shielding power line according to claim 1, wherein: in the graphene composite coating, the mass ratio of three-dimensional graphene, polypyrrole and nano-silver is 4:1:0.

1.

3. The shielding power line according to claim 1, wherein: the cross-sectional area of the conductor layer is 60mm2-80mm2, and the conductor layer is twisted by multiple tinned copper wires, and the twisting pitch is less than or equal to 15 times the diameter of a single wire.

4. The shielding power line according to claim 1, wherein: the materials of the insulating layer and the outer sheath are both cross-linked polyethylene.

5. A method of manufacturing a shielded power cord comprising the shielded power cord of any one of claims 1-4, wherein, The method comprises the following steps: S1. preparing a wire core with an insulating layer; S2. cleaning and activating the outer surface of the insulating layer of the wire core; S3. preparing a graphene composite coating containing three-dimensional graphene, polypyrrole and nano-silver; S4. spraying the graphene composite coating onto the surface of the treated wire core by electrostatic spraying; S5. heat pressing solidification of the sprayed wire core to form the graphene composite coating; S6. extruding an outer sheath outside the solidified shielding layer.

6. The method for preparing the shielding power line according to claim 5, wherein: in step S3, the mass ratio of three-dimensional graphene, polypyrrole and nano-silver is 4:1:0.

1.

7. The method for preparing the shielding power line according to claim 5, wherein: in step S4, the voltage of electrostatic spraying is 40-60kV.

8. The method for preparing the shielding power line according to claim 5, wherein: in step S5, the temperature range of heat pressing solidification is 160-200℃, the pressure range is 8-12MPa, and the time range is 5-15 minutes.

9. The method for preparing the shielding power line according to claim 5, wherein: in step S2, the activation treatment is plasma treatment or ultraviolet light treatment.

10. The method of claim 5, wherein: in step S3, the graphene composite coating further comprises an organic solvent and a binder, the organic solvent is N-methyl pyrrolidone, and the binder is epoxy resin.

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