Direct-current low-voltage power cable and preparation method thereof

Abstract

The invention belongs to the technical field of cable manufacturing, and discloses a direct-current low-voltage power cable and a preparation method thereof.The direct-current low-voltage power cable comprises a conductor, an insulating layer and an outer protective layer, the insulating layer wraps the periphery of the conductor, the insulating layer comprises a silicon-based inner layer and a modified polypropylene outer layer, the silicon-based inner layer comprises a rubber base material and nano titanium dioxide, and the modified polypropylene outer layer comprises a modified polypropylene outer layer; the modified polypropylene outer layer comprises ethylene copolymerization modified polypropylene, styrene grafting modified polypropylene, an elastomer, an anti-copper agent and color master batch, and the outer protective layer wraps the periphery of the insulating layer. According to the direct-current low-voltage power cable provided by the invention, the problems that the processing steps of an existing cable are increased and the production cost is increased due to the defects that the problems of charge accumulation and poor low-temperature resistance are solved by adding a semi-conductive layer and a thermal insulation material in the existing cable can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of cable manufacturing, and in particular to a DC low-voltage power cable and a preparation method thereof. Background Art

[0002] Polypropylene is currently the most widely used cable insulation material. However, polypropylene easily accumulates space charge in DC fields, causing electric field distortion in the cable, accelerating insulation aging, and reducing cable service life. Furthermore, polypropylene's poor low-temperature resistance makes the insulation layer difficult to meet the requirements of high-current-carrying scenarios such as energy storage systems.

[0003] Existing cables mostly address the issues of space charge accumulation and low-temperature resistance by adding structural enhancements. For example, a semiconducting layer is added between the conductor and insulation layer to evenly distribute the charge. Insulating material is wrapped around the insulation layer to improve the cable's low-temperature resistance. However, the addition of a semiconducting layer and mica tape increases the number of processing steps and production costs.

[0004] Therefore, there is an urgent need for a DC low-voltage power cable and a preparation method thereof to solve the above technical problems. Summary of the Invention

[0005] The first object of the present invention is to provide a DC low-voltage power cable that can solve the problems of existing cables that increase processing steps and increase production costs by adding semi-conductive layers and thermal insulation materials to solve the shortcomings of charge accumulation and poor low-temperature resistance.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A DC low-voltage power cable, comprising:

[0008] A conductor and an insulating layer, wherein the insulating layer is coated on the outer periphery of the conductor, and the insulating layer comprises a silicon-based inner layer and a modified polypropylene outer layer; the silicon-based inner layer comprises a silicone rubber base material and nano-titanium dioxide, and the modified polypropylene outer layer comprises ethylene copolymer modified polypropylene, styrene grafted modified polypropylene, an elastomer, an anti-copper agent, and a masterbatch;

[0009] An outer protective layer is coated on the outer periphery of the insulating layer.

[0010] As a preferred technical solution for DC low-voltage power cables, the silicon-based inner layer comprises 65 to 75 parts of silicone rubber base material and 2 to 10 parts of nano-titanium dioxide in parts by weight;

[0011] The modified polypropylene outer layer comprises, by weight, 50 to 60 parts of ethylene copolymer modified polypropylene, 15 to 25 parts of styrene graft modified polypropylene, 15 to 25 parts of elastomer, 0.2 to 1.5 parts of anti-copper agent and 0.3 to 2.0 parts of masterbatch.

[0012] As an optimal technical solution for the DC low-voltage power cable, the silicon-based inner layer and the modified polypropylene outer layer are integrally formed by double-layer co-extrusion.

[0013] As a preferred technical solution for DC low-voltage power cables, the thickness of the silicon-based inner layer is 0.3 mm to 0.8 mm;

[0014] The thickness of the modified polypropylene outer layer is 0.4 mm to 2.8 mm.

[0015] As a preferred technical solution of the DC low-voltage power cable, the DC low-voltage power cable further includes a metal shielding layer, and the metal shielding layer is located between the insulating layer and the outer sheath.

[0016] As a preferred technical solution for the DC low-voltage power cable, the metal shielding layer is formed by copper tape wrapped around the outer periphery of the insulating layer;

[0017] Alternatively, the metal shielding layer is formed by braiding multiple tinned copper wires.

[0018] As an optimal technical solution for the DC low-voltage power cable, the conductor is formed by twisting a plurality of copper wires, and the twisted pitch-diameter ratio of the plurality of copper wires is 8-10.

[0019] As an optimal technical solution for the DC low-voltage power cable, the outer sheath is made of halogen-free flame-retardant rubber.

[0020] A second object of the present invention is to provide a preparation method for preparing any of the above-mentioned DC low-voltage power cables. To achieve this object, the present invention adopts the following technical solutions:

[0021] A preparation method for preparing any one of the above-mentioned DC low-voltage power cables, the preparation method comprising the following steps:

[0022] Step 1: Twisting multiple guide wires to form a conductor;

[0023] Step 2: mixing a silicone rubber base material and nano-titanium dioxide to form a silicone-based mixture, extruding and coating the silicone-based mixture on the periphery of the conductor to form a silicone-based inner layer, mixing ethylene copolymer modified polypropylene, styrene grafted modified polypropylene, an elastomer, an anti-copper agent, and a masterbatch to form a modified polypropylene mixture, extruding and coating the modified polypropylene mixture on the periphery of the silicone-based inner layer to form a modified polypropylene outer layer; the silicone-based inner layer and the modified polypropylene outer layer are combined to form an insulating layer;

[0024] Step 3: Extrude and cover the outer protective material on the outer periphery of the insulating layer to form an outer protective layer.

[0025] As a preferred technical solution of the method for preparing a DC low-voltage power cable, a step 20 is further included between step 2 and step 3:

[0026] A metal shielding layer is provided on the outer periphery of the insulating layer.

[0027] The beneficial effects of the present invention are:

[0028] The DC low-voltage power cable provided by the present invention has an insulating layer provided with a silicon-based inner layer and a modified polypropylene outer layer. The silicon-based inner layer includes a silicone rubber base material and nano-titanium dioxide. The silicone rubber base material has excellent electrical resistance under a DC electric field. The addition of nano-titanium dioxide can inhibit charge accumulation under a DC electric field, so that the charge is evenly distributed in the silicon-based inner layer, thereby avoiding accelerated aging of the insulating layer and improving the service life of the insulating layer. The modified polypropylene outer layer includes ethylene copolymer modified polypropylene, styrene grafted modified polypropylene, an elastomer, an anti-copper agent and a masterbatch. Ethylene and polyethylene are combined by copolymerization modification to form ethylene copolymer modified polypropylene. Ethylene has good low-temperature resistance and electrical insulation, which can make up for the shortcomings of poor low-temperature toughness and poor insulation of polypropylene, making the modified The outer layer of polypropylene has good insulation and mechanical properties; styrene and polypropylene are combined through grafting modification to form styrene grafted modified polypropylene, and an anti-copper agent is added. The addition of styrene can reduce the brittleness of polypropylene, balance the original rigidity of polypropylene while improving its ductility, so that the styrene grafted modified polypropylene has good toughness in low temperature environment. The addition of the anti-copper agent can introduce trap energy levels into the styrene grafted modified polypropylene, increase the trap density of the styrene grafted modified polypropylene, further inhibit the degree of charge accumulation during operation of the DC low-voltage power cable, and thereby reduce the aging speed of the insulation layer; the addition of the elastomer can improve the low-temperature toughness of the modified polypropylene outer layer, so that the modified polypropylene outer layer has good low-temperature resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the DC low-voltage power cable provided by the present invention;

[0030] Figure 2 It is a schematic diagram of the preparation process of the DC low-voltage power cable provided by the present invention.

[0031] In the picture:

[0032] 1. Conductor; 2. Insulation layer; 21. Silicone-based inner layer; 22. Modified polypropylene outer layer; 3. Metal shielding layer; 4. Outer sheath. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0034] In the description of the present invention, unless otherwise expressly specified or limited, the terms "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific circumstances.

[0035] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0036] In the description of this embodiment, the terms "upper," "lower," "right," and other orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for ease of description and simplified operation. They do not indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used solely for descriptive purposes and have no special meanings.

[0037] like Figure 1As shown in , this embodiment provides a DC low-voltage power cable, comprising a conductor 1, an insulating layer 2, and an outer sheath 4. The insulating layer 2 is coated on the outer periphery of the conductor 1, and the insulating layer 2 comprises a silicon-based inner layer 21 and a modified polypropylene outer layer 22. The silicon-based inner layer 21 comprises a silicone rubber base material and nano-titanium dioxide. The silicone rubber base material has excellent electrical resistance under a DC electric field. The addition of nano-titanium dioxide can inhibit charge accumulation under a DC electric field, uniformly distribute the charge in the silicon-based inner layer 21, avoid accelerated aging of the insulating layer 2, and increase the life of the insulating layer 2. The modified polypropylene outer layer 22 comprises ethylene copolymer modified polypropylene, styrene grafted modified polypropylene, an elastomer, an anti-copper agent, and a masterbatch. Ethylene and polyethylene are combined by copolymerization modification to form ethylene copolymer modified polypropylene. Ethylene has good low-temperature resistance and electrical insulation, which can make up for the shortcomings of poor low-temperature toughness and poor insulation of polypropylene, so that the modified polypropylene outer layer 22 has good insulation and mechanical properties. By grafting modification, styrene and polypropylene are combined to form styrene grafted modified polypropylene, and an anti-copper agent is added. The addition of styrene can reduce the brittleness of polypropylene, balance the original rigidity of polypropylene while improving its ductility, and achieve good toughness of styrene grafted modified polypropylene in a low-temperature environment. The addition of the anti-copper agent can introduce trap energy levels into the styrene grafted modified polypropylene, increase the trap density of the styrene grafted modified polypropylene, further suppress the degree of charge accumulation during operation of the DC low-voltage power cable, and thereby reduce the aging rate of the insulating layer 2. The addition of the elastomer can improve the low-temperature toughness of the modified polypropylene outer layer 22, so that the modified polypropylene outer layer 22 has good low-temperature resistance. The outer sheath 4 is coated on the periphery of the insulating layer 2, so that the DC low-voltage power cable has mechanical properties, can resist friction and extrusion, and improve the service life of the DC low-voltage power cable.

[0038] Exemplarily, the silicon-based inner layer 21 comprises 65 to 75 parts by weight of a silicone rubber base material and 2 to 10 parts by weight of nano-titanium dioxide. This prevents excessive addition of nano-titanium dioxide to the silicon-based inner layer 21, which reduces the electrical resistance. While achieving good electrical resistance for the silicon-based inner layer 21, the problem of charge accumulation does not occur, effectively ensuring the service life of the insulating layer 2. Exemplarily, the modified polypropylene outer layer 22 comprises 50 to 60 parts by weight of ethylene copolymer modified polypropylene, 15 to 25 parts of styrene grafted modified polypropylene, 15 to 25 parts of an elastomer, 0.2 to 1.5 parts of an anti-copper agent, and 0.3 to 2.0 parts of a masterbatch. In this way, it is possible to avoid the reduction of the toughness of the modified polypropylene outer layer 22 in a low-temperature environment and the mechanical properties in a normal environment due to excessive addition of anti-copper agents and masterbatches, so that the modified polypropylene outer layer 22 has both mechanical and low-temperature toughness, and has the performance of inhibiting charge accumulation, further ensuring the service life of the insulating layer 2, and thereby achieving the purpose of improving the service life of the DC low-voltage power cable.

[0039] Furthermore, the silicon-based inner layer 21 and the modified polypropylene outer layer 22 are integrated into one body by double-layer co-extrusion. In this way, the silicon-based inner layer 21 and the modified polypropylene outer layer 22 can be tightly fitted to prevent water vapor from entering the interior of the insulating layer 2, further improving the service life of the insulating layer 2. At the same time, the double-layer co-extrusion processing method can further improve the processing efficiency of the insulating layer 2. Furthermore, the thickness of the silicon-based inner layer 21 is 0.3mm to 0.8mm, and the thickness of the modified polypropylene outer layer 22 is 0.4mm to 2.8mm. Regarding the specific thickness of the silicon-based inner layer 21 and the modified polypropylene outer layer 22, it can be selected according to the specifications of the DC low-voltage power cable, and no specific restrictions are made here.

[0040] In this embodiment, the DC low-voltage power cable further includes a metal shielding layer 3, which is positioned between the insulation layer 2 and the outer sheath 4. The provision of the metal insulation layer 2 can enhance the DC low-voltage power cable's resistance to external electromagnetic interference, enabling the DC low-voltage power cable to transmit current more stably. On one hand, the metal shielding layer 3 can be formed by wrapping a copper tape around the outer periphery of the insulation layer. Specifically, the copper tape can be wrapped around the outer periphery of the insulation layer 2 by spiral winding or longitudinal wrapping, without specific limitations. On the other hand, the metal shielding layer 3 can be woven from multiple tinned copper wires. These multiple tinned copper wires can be woven to form a metal shielding sleeve, which is then placed around the outer periphery of the insulation layer 2 to form a metal braided layer. When the metal braided layer is woven from multiple tinned copper wires, the braiding density of the multiple tinned copper wires is 80% to 90%, thereby enhancing the DC low-voltage power cable's resistance to external electromagnetic interference while maintaining a certain degree of flexibility.

[0041] In this embodiment, the conductor 1 is formed by twisting a plurality of copper wires, and the pitch-to-diameter ratio of the twisted plurality of conductor wires is 8 to 10. In this way, the conductor 1 can transmit current while having a certain degree of softness, further improving the flexibility of the DC low-voltage power cable, and making it more convenient for the layout of the DC low-voltage power cable. Preferably, a wrapping layer can be provided between the conductor 1 and the insulating layer 2. The wrapping layer is formed by spirally wrapping a non-woven fabric around the outer periphery of the conductor 1. The provision of the wrapping layer can prevent the conductor 1 from loosening, further improving the stability of the current transmitted by the DC low-voltage power cable. Preferably, the copper wire used for twisting the conductor 1 can be tinned copper wire, further improving the flexibility of the DC low-voltage power cable. In this embodiment, the bending radius of the DC low-voltage power cable can reach 6D, where D is the outer diameter of the DC low-voltage power cable.

[0042] In this embodiment, the outer sheath 4 is made of halogen-free flame-retardant rubber, which exhibits excellent mechanical and flame retardancy, as well as low smoke and toxicity. These excellent mechanical properties provide the outer sheath 4 with excellent compression and abrasion resistance. This excellent flame retardancy ensures that the outer sheath 4 will self-extinguish after a fire in the DC low-voltage power cable, ensuring public safety. Furthermore, the low smoke and toxicity of the halogen-free flame-retardant rubber mean that the outer sheath 4 will not produce significant amounts of dense smoke or toxic gases when burning, allowing personnel sufficient time to escape and further enhancing the safety of the DC low-voltage power cable.

[0043] The DC low-voltage power cable of this embodiment has a 67.4% higher elongation at break, an 8.0% higher penetration resistance, and a volume resistivity of ≥10 by providing the insulating layer 2 with a silicon-based inner layer 21 and a modified polypropylene outer layer 22 compared to the existing cable. 16 Ω·m. Impact at -40℃ will not cause insulation failure, the flexural modulus can reach 450Mpa, and the space charge density can be reduced by 60% to 1.2C / m. 3 , after 2500 hours of aging, the insulation resistance retention rate is ≥95%.

[0044] Example 2

[0045] like Figure 2 As shown in , this embodiment provides a method for preparing a DC low-voltage power cable, which is used to prepare the DC low-voltage power cable in Example 1. The method for preparing the DC low-voltage power cable includes the following steps:

[0046] Step 1: Twisting a plurality of copper wires to form a conductor 1. The copper wires are twisted at a pitch-to-diameter ratio of 8 to 10 to ensure that the conductor 1 can stably transmit current while maintaining a certain degree of flexibility.

[0047] Step 2: Mix the silicone rubber base material and nano-titanium dioxide to form a silicone-based mixture, extrude and coat the silicone-based mixture on the periphery of the conductor 1 to form a silicone-based inner layer 21, mix ethylene copolymer modified polypropylene, styrene grafted modified polypropylene, elastomer, anti-copper agent and masterbatch to form a modified polypropylene mixture, extrude and coat the modified polypropylene mixture on the periphery of the silicone-based inner layer 21 to form a modified polypropylene outer layer 22. Specifically, the silicone-based inner layer 21 and the modified polypropylene outer layer 22 are combined to form the insulating layer 2. The silicone-based inner layer 21 and the modified polypropylene outer layer 22 are extruded and coated on the periphery of the conductor 1 by double-layer co-extrusion, thereby further improving the processing efficiency of the insulating layer 2.

[0048] Step 3: Extruding and coating the outer protective material on the outer periphery of the insulating layer 2 to form the outer protective layer 4. Specifically, the halogen-free flame retardant rubber material is extruded and coated on the outer periphery of the insulating layer 2 through an extruder to form the outer protective layer 4.

[0049] In this embodiment, step 20 is further included between step 2 and step 3:

[0050] A metal shielding layer 3 is provided on the outer periphery of the insulating layer 2. This can improve the DC low-voltage power cable's ability to resist external electromagnetic interference and further improve the stability of the DC low-voltage power cable's current transmission.

[0051] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. A person skilled in the art would be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A DC low-voltage power cable, characterized in that: include: A conductor (1) and an insulating layer (2), wherein the insulating layer (2) is coated on the outer periphery of the conductor (1), and the insulating layer (2) comprises a silicon-based inner layer (21) and a modified polypropylene outer layer (22); the silicon-based inner layer (21) comprises a silicone rubber base material and nano-titanium dioxide, and the modified polypropylene outer layer (22) comprises ethylene copolymer modified polypropylene, styrene grafted modified polypropylene, an elastomer, an anti-copper agent, and a masterbatch; An outer protective layer (4), the outer protective layer (4) is coated on the outer periphery of the insulating layer (2).

2. The DC low-voltage power cable according to claim 1, characterized in that: The silicon-based inner layer (21) comprises 65 to 75 parts of a silicone rubber base material and 2 to 10 parts of nano-titanium dioxide in proportions by weight; The modified polypropylene outer layer (22) comprises, by weight, 50 to 60 parts of ethylene copolymer modified polypropylene, 15 to 25 parts of styrene graft modified polypropylene, 15 to 25 parts of elastomer, 0.2 to 1.5 parts of anti-copper agent and 0.3 to 2.0 parts of masterbatch.

3. The DC low-voltage power cable according to claim 2, characterized in that: The silicon-based inner layer (21) and the modified polypropylene outer layer (22) are integrally formed by double-layer co-extrusion.

4. The DC low-voltage power cable according to claim 1, characterized in that: The thickness of the silicon-based inner layer (21) is 0.3 mm to 0.8 mm; The thickness of the modified polypropylene outer layer (22) is 0.4 mm to 2.8 mm.

5. The DC low-voltage power cable according to claim 1, characterized in that: The DC low-voltage power cable further comprises a metal shielding layer (3), wherein the metal shielding layer (3) is located between the insulating layer (2) and the outer sheath (4).

6. The DC low-voltage power cable according to claim 5, characterized in that: The metal shielding layer (3) is formed by copper tape wrapped around the outer periphery of the insulating layer (2); Alternatively, the metal shielding layer (3) is formed by braiding a plurality of tinned copper wires.

7. The DC low-voltage power cable according to any one of claims 1 to 6, characterized in that: The conductor (1) is formed by twisting a plurality of copper wires, and the twisted pitch-diameter ratio of the plurality of copper wires is 8-10.

8. The DC low-voltage power cable according to any one of claims 1 to 6, characterized in that: The outer protective layer (4) is made of halogen-free flame-retardant rubber.

9. A preparation method, characterized in that: For preparing the DC low-voltage power cable according to any one of claims 1 to 8, the preparation method comprises the following steps: Step 1: twisting a plurality of guide wires to form a conductor (1); Step 2: mixing a silicone rubber base material and nano-titanium dioxide to form a silicone-based mixture, extruding and coating the silicone-based mixture on the periphery of the conductor (1) to form a silicone-based inner layer (21), mixing ethylene copolymer modified polypropylene, styrene graft modified polypropylene, elastomer, anti-copper agent and masterbatch to form a modified polypropylene mixture, extruding and coating the modified polypropylene mixture on the periphery of the silicone-based inner layer (21) to form a modified polypropylene outer layer (22); the silicone-based inner layer (21) and the modified polypropylene outer layer (22) are combined to form an insulating layer (2); Step 3: Extruding and covering the outer protective material on the outer periphery of the insulating layer (2) to form an outer protective layer (4).

10. The preparation method according to claim 9, characterized in that Also included between step 2 and step 3 is step 20: A metal shielding layer (3) is provided on the periphery of the insulating layer (2).

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