Low-voltage power cable

Abstract

The invention relates to the technical field of cables, and provides a low-voltage power cable which sequentially comprises a conductor, an insulating layer, a lining layer, an armor layer and a sheath layer from inside to outside. The armor layer is formed by winding two layers of parallel steel belts outside the cable lining layer in a spiral or longitudinal wrapping manner; the conductor is formed by twisting tinned copper wires; the sheath layer is a polyvinyl chloride resin sheath layer.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable, in particular, to a low-voltage power cable. BACKGROUND

[0002] Low-voltage power cable is the core carrier of urban power grid, industrial power supply and building power distribution system, and its long-term operation reliability is directly related to energy transmission safety and infrastructure stability. In recent years, with the development of new energy grid connection, intelligent rail transit and green building, higher requirements are put forward for the comprehensive performance of the cable.

[0003] The outermost layer of the low-voltage power cable is the protective layer, and polyvinyl chloride is widely used in the protective layer of the low-voltage power cable because of its excellent insulation and non-flammability. However, it will produce a lot of smoke when burning. Although the addition of flame retardant can effectively reduce the HCL release and smoke emission of flame-retardant polyvinyl chloride resin, the mechanical properties of the low-voltage power cable will decrease significantly when the amount of flame retardant is too high. Therefore, it is of great significance to develop a low-voltage power cable with excellent mechanical properties and flame retardant properties. SUMMARY

[0004] The present application provides a low-voltage power cable, which solves the problem of poor mechanical properties of the sheath layer of the low-voltage power cable in the related art.

[0005] The technical scheme of the present application is as follows: The present application provides a low-voltage power cable, which is composed of a conductor, an insulation layer, an inner liner layer, an armor layer and a sheath layer from inside to outside. The armor layer is composed of two parallel steel belts wrapped around the inner liner layer in a spiral or longitudinal manner. The conductor is composed of a tin-plated copper wire. The sheath layer is a polyvinyl chloride resin sheath layer. As a further technical scheme, the thickness of the insulation layer is 0.6-0.9mm.

[0006] As a further technical scheme, the insulation layer is a polyvinyl chloride insulation layer.

[0007] As a further technical scheme, the material of the inner liner layer is a polypropylene tape.

[0008] As a further technical scheme, the thickness of the inner liner layer is 0.5-0.8mm.

[0009] As a further technical scheme, the thickness of the sheath layer is 1.2-1.8mm.

[0010] As a further technical scheme, the thickness of the inner liner layer is 0.5-0.8mm.

[0011] As a further technical scheme, the thickness of the armor layer is 0.5-0.6mm.

[0012] As a further technical solution, the raw material of the sheath layer comprises the following components by weight: 50-60 parts of polyvinyl chloride resin, 15-25 parts of ethylene-vinyl acetate copolymer, 10-15 parts of chlorosulfonated polyethylene, 8-12 parts of polyhexamethylene adipate, 20-30 parts of filler, and 2-4 parts of compatibilizer.

[0013] As a further technical solution, the raw material of the sheath layer further comprises 20-25 parts of flame retardant, 1-4 parts of plasticizer, and 1-3 parts of antioxidant.

[0014] The addition of the plasticizer in the low-voltage power cable of the present application can balance the rigidity of the polyvinyl chloride and the flexibility of the ethylene-vinyl acetate copolymer, so that the sheath layer still maintains good flexibility in a low-temperature environment and avoids cracking at low temperature.

[0015] The addition of the filler in the low-voltage power cable of the present application can be dispersed in the polymer matrix. When the material is subjected to external force, these particles bear part of the load and share the stress of the polymer molecular chain, thereby improving the overall rigidity and resistance to deformation of the material.

[0016] As a further technical solution, the flame retardant is magnesium hydroxide modified by 2-aminoresorcinol.

[0017] The flame retardant in the sheath layer of the low-voltage power cable of the present application is magnesium hydroxide modified by 2-aminoresorcinol, which can improve the mechanical properties and flame retardant properties of the sheath layer of the low-voltage power cable. The reason is that, on the one hand, 2-aminoresorcinol introduces organic functional groups on the surface of magnesium hydroxide, which significantly improves the compatibility of magnesium hydroxide with the PVC resin matrix and the mechanical properties of the sheath layer. On the other hand, it also improves the flame retardant properties of the sheath layer of the low-voltage power cable.

[0018] As a further technical solution, the preparation method of the flame retardant comprises the following steps: dispersing 2-aminoresorcinol in anhydrous ethanol, then adding magnesium hydroxide, filtering and drying to obtain the flame retardant.

[0019] As a further technical solution, the addition amount of 2-aminoresorcinol is 4%-5% of the mass of magnesium hydroxide.

[0020] As a further technical solution, the mass-to-volume ratio of magnesium hydroxide to anhydrous ethanol is 1g:8mL.

[0021] As a further technical solution, the raw material of the sheath layer further comprises 5-hydroxyisophthalic acid dimethyl ester in an amount of 2-4 parts.

[0022] The raw material of the sheath layer of the low-voltage power cable of the application further adds 5-hydroxy isophthalic acid dimethyl ester, and the hydroxyl in the molecular structure of the 5-hydroxy isophthalic acid dimethyl ester can form a hydrogen bond with the hydroxyl on the surface of the filler in the preparation process, so as to promote the dispersibility of the filler in the base material and improve the mechanical properties of the sheath layer.

[0023] As a further technical solution, the filler comprises one or both of carbon black and wollastonite.

[0024] As a further technical solution, the plasticizer comprises one or more of dioctyl phthalate, diisononyl phthalate, and epoxy soybean oil.

[0025] As a further technical solution, the compatibilizer comprises one or more of propylene oxide graft copolymer, glycidyl ester, and maleic anhydride grafted polypropylene.

[0026] As a further technical solution, the antioxidant is a hindered phenolic antioxidant, and the hindered phenolic antioxidant comprises one or more of antioxidant 1010, antioxidant 1076, and antioxidant 1035.

[0027] The phenolic hydroxyl in the hindered phenolic antioxidant added in the low-voltage power cable can capture free radicals, inhibit the oxidative degradation of the sheath layer under long-term operation, and prolong the service life of the sheath layer of the low-voltage power cable.

[0028] The working principle and beneficial effects of the application are as follows: The low-voltage power cable of the application sequentially comprises an insulation layer, an inner liner layer, an armor layer, and a sheath layer from inside to outside, forming a multi-layer protection system. The insulation layer insulates the conductor from the outside world, prevents electric leakage, and ensures the safety of electricity use; the inner liner layer further buffers external pressure and protects the insulation layer from damage; the armor layer is wound in a spiral or longitudinal wrapping manner by two parallel steel belts, which can effectively resist external mechanical force and enhance the structural strength of the cable; and the polyvinyl chloride resin sheath layer can improve the flame retardant effect of the low-voltage power cable. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0030] In the following examples and comparative examples: Polyvinyl chloride resin: model: SG-1; Chlorosulfonated polyethylene: model: 3304, manufacturer: Jihua; Ethylene-vinyl acetate copolymer: Model: 18J3, Manufacturer: Yanshan Petrochemical; Poly(hexanediol adipate): Model: YK2225, Manufacturer: Hubei Yongkuo Technology Co., Ltd. Maleic anhydride grafted polypropylene: ZJ-900P, Guangzhou Zhongjie Chemical Technology Co., Ltd. Wollastonite: 3000 mesh; Magnesium hydroxide: 1250 mesh; Conductor: Made of twisted tinned copper wire; Insulation layer: PVC insulation layer.

[0031] Example 1 A low-voltage power cable comprises, from the inside out, a conductor, an insulation layer, an inner lining layer, an armor layer, and a sheath layer; wherein the raw materials of the sheath layer include the following components in parts by weight: 50 parts of polyvinyl chloride resin, 15 parts of ethylene-vinyl acetate copolymer, 10 parts of chlorosulfonated polyethylene, 8 parts of poly(hexamethylene adipate), 10 parts of chlorosulfonated polyethylene, 20 parts of wollastonite, 2 parts of maleic anhydride grafted polypropylene, 20 parts of flame retardant, 1 part of dioctyl phthalate, and 1 part of antioxidant 1010; The flame retardant is prepared as follows: 2-aminoresorcinol is added to anhydrous ethanol and uniformly dispersed, and then magnesium hydroxide is added. The mixture is mixed at 40°C for 3 hours, and filtered and dried to obtain a filler. The amount of 2-aminoresorcinol added is 3% of the mass of the magnesium hydroxide, and the mass-to-volume ratio of magnesium hydroxide to anhydrous ethanol is 1 g:8 mL. A method for preparing a low-voltage power cable comprises the following steps: S1. Extrude the insulation material onto the conductor to form an insulation layer with a thickness of 0.6 mm. S2. Wrap the polypropylene tape around the insulation layer to form a 0.5mm thick lining layer; S3, wrap two parallel layers of steel strips around the inner lining in a spiral wrapping manner to form a 0.5 mm armor layer; S4, after the raw materials of the sheath layer are evenly mixed, the raw materials are melt-extruded onto the outer side of the armor layer through a twin-screw extruder to form a sheath layer with a thickness of 0.8 mm to obtain a low-voltage power cable; Among them, the mixing time in S4 is 20 minutes.

[0032] Example 2 A low-voltage power cable, from inside to outside, is a conductor, an insulation layer, an inner lining layer, an armored layer and a sheath layer; wherein the raw material of the sheath layer comprises the following components by weight: 60 parts of polyvinyl chloride resin, 25 parts of ethylene-vinyl acetate copolymer, 15 parts of chlorosulfonated polyethylene, 12 parts of polyhexamethylene adipate, 15 parts of chlorosulfonated polyethylene, 30 parts of wollastonite, 4 parts of maleic anhydride grafted polypropylene, 25 parts of flame retardant, 4 parts of dioctyl phthalate, and 3 parts of antioxidant 1010; The preparation method of the flame retardant is as follows: 2-aminoresorcinol is uniformly dispersed in anhydrous ethanol, then magnesium hydroxide is added, and mixed at 40℃ for 3h, and then filtered and dried to obtain the filler; wherein the addition amount of 2-aminoresorcinol is 3% of the mass of magnesium hydroxide, and the mass-volume ratio of magnesium hydroxide to anhydrous ethanol is 1g:8mL; A preparation method of a low-voltage power cable, comprising the following steps: S1, the insulation layer material is extruded and wrapped outside the conductor to form an insulation layer with a thickness of 0.6mm; S2, a polypropylene wrapping tape is wrapped outside the insulation layer to form an inner lining layer with a thickness of 0.5mm; S3, two parallel steel belts are spirally wrapped outside the inner lining layer to form an armored layer with a thickness of 0.5mm; S4, the raw material of the sheath layer is uniformly mixed, then melted and extruded outside the armored layer by a double screw extruder to form a sheath layer with a thickness of 0.8mm, thereby obtaining a low-voltage power cable.

[0033] Example 3 The difference between this embodiment and example 1 is only that the addition amount of 2-aminoresorcinol is 4% of the mass of magnesium hydroxide.

[0034] Example 4 The difference between this embodiment and example 1 is only that the addition amount of 2-aminoresorcinol is 5% of the mass of magnesium hydroxide.

[0035] Example 5 The difference between this embodiment and example 1 is only that the addition amount of 2-aminoresorcinol is 6% of the mass of magnesium hydroxide.

[0036] Example 6 The difference between this embodiment and example 1 is only that 2-aminoresorcinol is replaced by an equal amount of γ-aminopropyl triethoxysilane.

[0037] Example 7 The difference between this embodiment and example 1 is only that the flame retardant in this embodiment is only magnesium hydroxide.

[0038] Example 8 The difference between this example and Example 1 is that 2 parts of dimethyl 5-hydroxyisophthalate is further included in the raw material of the sheath layer.

[0039] Example 9 The difference between this example and Example 1 is that 3 parts of dimethyl 5-hydroxyisophthalate is further included in the raw material of the sheath layer.

[0040] Example 10 The difference between this example and Example 1 is that 4 parts of dimethyl 5-hydroxyisophthalate is further included in the raw material of the sheath layer.

[0041] The low-voltage power cable prepared in Examples 1-10 is tested according to the following method: 1. Flame retardancy: The oxygen index test is performed according to the method of GB / T 2406.2-2009 "Determination of the flammability of plastics - Part 2: Test method in room temperature", and the test result is the average value of 3 samples; the test results are shown in Table 1.

[0042] 2. Mechanical properties: The tensile strength and elongation at break are tested according to the method of GB / T 2951.11-2008 "Cables and optical fibers - Determination of the characteristics of insulation and sheaths - Part 11: General test methods - Measurement of thickness and outer dimensions - Mechanical properties test", and the test result is the average value of 5 samples; the test results are shown in Table 1 and Table 2.

[0043] Table 1 Determination results of the flame retardancy of the sheath layer of the low-voltage power cable in Examples 1-7

[0044] Compared with Example 1, Examples 3-5 change the addition amount of 2-aminophenol, and the results show that the oxygen index of the sheath layer of the low-voltage power cable in Examples 4-5 is higher than that of Example 1, 3, indicating that when the magnesium hydroxide is modified, the addition amount of 2-aminophenol is 4%-5% of the mass of magnesium hydroxide, which can further improve the oxygen index and mechanical properties of the sheath layer of the low-voltage power cable.

[0045] Table 2 Determination results of the mechanical properties of the sheath layer of the low-voltage power cable in Example 1 and Examples 8-10

[0046] Compared with Example 1, the tensile strength and elongation at break of the sheath layer of the low-voltage power cable in Examples 8-10 are higher than those of Example 1, indicating that the addition of dimethyl 5-hydroxyisophthalate in the raw material of the sheath layer can improve the mechanical properties of the sheath layer of the low-voltage power cable.

[0047] The above merely preferred embodiments of the present application are not used to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A low voltage power cable, characterized in that: From the inside to the outside, they are conductor, insulation layer, inner lining layer, armor layer, and sheath layer; the armor layer is composed of two layers of parallel steel strips wrapped spirally or longitudinally around the outer surface of the cable inner lining layer; the conductor is twisted tinned copper wires; the sheath layer is a polyvinyl chloride resin sheath layer.

2. A low-voltage power cable according to claim 1, characterized in that: The thickness of the insulating layer is 0.6-0.9 mm.

3. A low-voltage power cable according to claim 1, characterized in that: The insulating layer is a polyvinyl chloride insulating layer.

4. A low-voltage power cable according to claim 1, characterized in that: The material of the inner lining layer is polypropylene tape.

5. A low-voltage power cable according to claim 1, characterized in that: The thickness of the sheath layer is 1.2-1.8 mm.

6. A low-voltage power cable according to claim 1, characterized in that: The raw materials of the sheath layer include the following components in parts by weight: 50-60 parts of polyvinyl chloride resin, 15-25 parts of ethylene-vinyl acetate copolymer, 10-15 parts of chlorosulfonated polyethylene, 8-12 parts of poly(hexamethylene adipate), 20-30 parts of filler, and 2-4 parts of compatibilizer.

7. A low-voltage power cable according to claim 6, characterized in that: The raw materials of the sheath layer also include 20-25 parts of flame retardant, 1-4 parts of plasticizer, and 1-3 parts of antioxidant. The flame retardant is obtained by modifying magnesium hydroxide with 2-aminoresorcinol.

8. A low-voltage power cable according to claim 6, characterized in that: The raw materials of the sheath layer also include 2 to 4 parts of 5-hydroxydimethyl isophthalate.

9. A low-voltage power cable according to claim 6, characterized in that: The filler includes one or both of carbon black and wollastonite; and / or, The compatibilizer includes one or more of propylene oxide graft copolymer, glycidyl esters, and maleic anhydride grafted polypropylene.

10. A low-voltage power cable according to claim 7, characterized in that: The plasticizer includes one or more of dioctyl phthalate, diisononyl phthalate, and epoxidized soybean oil; and / or, The antioxidant is a hindered phenol antioxidant, and the hindered phenol antioxidant includes one or more of antioxidant 1010, antioxidant 1076, and antioxidant 1035.

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