Medium-voltage power cable and manufacturing method thereof

Abstract

The invention relates to the technical field of cables, and provides a medium-voltage power cable and a manufacturing method thereof.The medium-voltage power cable sequentially comprises a conductor, a conductor shielding layer, an insulating layer, an insulating shielding layer, a metal shielding layer, a lining layer, an armor layer and a sheath layer from inside to outside; the sheath layer comprises the following raw material components in parts by weight: 100 parts of polyvinyl chloride, 20-25 parts of a flame retardant, 30-40 parts of a plasticizer, 1-3 parts of an antioxidant and 20-25 parts of an inorganic composite material; the inorganic composite material is obtained by treating white carbon black with lignin and polyethylene glycol dimethacrylate, crushing and carbonizing. According to the technical scheme, the problem that the low temperature resistance of the medium-voltage power cable sheath layer is insufficient in the prior art is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable, in particular, to a medium voltage power cable and a manufacturing method thereof. BACKGROUND

[0002] The medium voltage power cable is widely used in urban power distribution network, industrial park and large building power supply system, and needs to be operated in complex environments such as long-term underground direct burial, pipeline laying or outdoor overhead, so higher requirements are put forward for the structural stability and environmental adaptability of the medium voltage power cable.

[0003] At present, the sheath layer with polyvinyl chloride as the base material is widely used in this type of cable, which has the advantages of relatively low cost, good processing formability, and certain chemical corrosion resistance. However, the existing polyvinyl chloride base sheath layer still has obvious shortcomings, that is, the movement ability of polyvinyl chloride molecular chain is weakened in low temperature environment, the mechanical properties are significantly reduced, and cracks or even damage may occur when subjected to external pressure or impact, which leads to the penetration of water and impurities into the cable, affecting the operation safety. Therefore, it is of great significance to develop a medium voltage power cable with excellent low temperature resistance for improving the operation reliability of the medium voltage power cable in complex environments. SUMMARY

[0004] The present application provides a medium voltage power cable and a manufacturing method thereof, which solves the problem of insufficient low temperature resistance of the sheath layer of the medium voltage power cable in the related art.

[0005] The technical scheme of the present application is as follows: The present application provides a medium voltage power cable, which comprises a conductor, a conductor shielding layer, an insulation layer, an insulation shielding layer, a metal shielding layer, an inner lining layer, an armor layer and a sheath layer from inside to outside, and the raw material of the sheath layer comprises the following components by weight: polyvinyl chloride 100 parts, flame retardant 20-25 parts, plasticizer 30-40 parts, antioxidant 1-3 parts, and inorganic composite material 20-25 parts; the inorganic composite material is white carbon black treated by lignin and polyethylene glycol dimethyl acrylate, and then crushed and carbonized.

[0006] The medium voltage power cable of the present application can weaken the intermolecular interaction force by adding plasticizer, thereby significantly improving the flowability during processing, ensuring uniform extrusion molding of the sheath layer and smooth surface, and improving the production efficiency; at the same time, the plasticizer can improve the flexibility of the outer sheath layer, so that the cable sheath can better withstand bending and mechanical stress during installation, laying and operation, and avoid cracking.

[0007] The medium voltage power cable in the application can effectively inhibit or delay the oxidative degradation process of polyvinyl chloride by adding an antioxidant, reduce the aging phenomenon caused by oxidation, help the outer sheath layer to maintain good flexibility, strength and other mechanical properties for a long time, and avoid the failure of the protection effect caused by aging, thereby affecting the overall structural stability of the cable.

[0008] As a further technical solution, the mass ratio of the white carbon black, the lignin and the polyethylene glycol dimethacrylate is 50:7:2~4, for example, it can be 50:7:2, 50:7:2.5, 50:7:3, 50:7:4, and preferably 50:7:3.

[0009] The medium voltage power cable in the application limits the mass ratio of the white carbon black, the lignin and the polyethylene glycol dimethacrylate in the inorganic composite material to be 50:7:2~4, further improves the low temperature performance of the medium voltage power cable, and if the amount of polyethylene glycol dimethacrylate is too much, more gas and pores will be generated during the subsequent carbonization process, and these defects are prone to cracks under low temperature stress; if the amount of polyethylene glycol dimethacrylate is too small, it is not enough to form a complete and uniform coating layer and crosslinking network with the lignin, resulting in insufficient modification of the surface of part of the white carbon black; after carbonization, defects exist in the interface, the interface gap will increase at low temperature, and the low temperature performance of the sheath layer cannot be effectively improved.

[0010] As a further technical solution, the preparation method of the inorganic composite material comprises the following steps: A1, the lignin and the polyethylene glycol dimethacrylate are added to the solvent and mixed uniformly, then the white carbon black is added and mixed, dried, and crushed to obtain a premix; A2, the premix is carbonized under inert gas to obtain an inorganic composite material.

[0011] As a further technical solution, in step A2, the carbonization temperature is 350~450℃, and the carbonization time is 2~3h.

[0012] As a further technical solution, in step A2, the inert gas is argon.

[0013] As a further technical solution, the flame retardant is magnesium hydroxide modified by 2-acetamidomethyl acrylate.

[0014] The medium voltage power cable in the application adopts magnesium hydroxide modified by 2-acetamidomethyl acrylate as a flame retardant, which significantly improves the flame retardance of the sheath layer. Although the unmodified magnesium hydroxide has a flame-retardant effect, it has poor compatibility with the polyvinyl chloride organic matrix due to its strong surface polarity, resulting in reduced flame-retardant performance. However, 2-acetamidomethyl acrylate can reduce the surface polarity of magnesium hydroxide by forming hydrogen bonding force between them, thereby improving the compatibility with the polyvinyl chloride matrix and enabling magnesium hydroxide to be more uniformly dispersed in the sheath layer to form a continuous flame-retardant barrier and play a flame-retardant role, further improving the flame retardance of the cable.

[0015] As a further technical solution, the mass ratio of the magnesium hydroxide and 2-acetamidomethyl acrylate is 100:7~9, for example, it can be 100:7, 4:0.3, 25:2, 100:9, and preferably 25:2.

[0016] As a further technical solution, the preparation method of the flame retardant comprises the following steps: after 2-acetamidomethyl acrylate is uniformly dispersed in a solvent, magnesium hydroxide is added and mixed, and then dried to obtain the flame retardant.

[0017] As a further technical solution, the mixing temperature is 40℃, and the mixing time is 2h.

[0018] As a further technical solution, the plasticizer includes one or more of dibutyl phthalate, dioctyl phthalate, triphenyl phosphate, and dioctyl sebacate.

[0019] As a further technical solution, the antioxidant includes one or more of antioxidant 1010, antioxidant 168, and antioxidant 2246.

[0020] The application also proposes a manufacturing method of a medium voltage power cable for preparing the above-mentioned medium voltage power cable, comprising the following steps: S1, extruding a conductor shielding layer material outside the conductor to form a conductor shielding layer; S2, extruding an insulation layer material outside the conductor shielding layer to form an insulation layer; S3, extruding an insulation shielding layer material outside the insulation layer to form an insulation shielding layer; S4, winding a metal shielding layer outside the insulation shielding layer to form a metal shielding layer; S5, extruding an inner liner layer material outside the metal shielding layer to form an inner liner layer; S6, winding an armor layer material outside the inner liner layer to form an armor layer; S7, uniformly mixing the raw materials of the sheath layer, melt extruding and coating outside the armor layer to form a sheath layer, and obtaining a medium voltage power cable.

[0021] The working principle and beneficial effects of the present application are as follows: The present application provides a medium-voltage power cable, the sheath layer of which uses polyvinyl chloride as the base material, and the addition of inorganic composite material improves the low-temperature mechanical properties of the sheath layer. Under low-temperature conditions, ordinary fillers are prone to cause interface debonding and material embrittlement due to compatibility and interface bonding force with the polymer matrix. However, the composite material in the present application, lignin and polyethylene glycol dimethacrylate, are coated on the surface of white carbon black through hydrogen bonding and van der Waals force, and then subjected to carbonization treatment, thereby improving the compatibility and interface bonding force of the inorganic filler with the polyvinyl chloride matrix under low-temperature conditions, ensuring that the cable can still maintain good mechanical strength in harsh environments such as severe cold, and guaranteeing the long-term use reliability of the cable. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

[0023] In the following examples and comparative examples: Polyvinyl chloride, model: SG-3, manufacturer: Xinjiang Tianye Group Co., Ltd.; Polyethylene glycol dimethacrylate, model: lbw, manufacturer: Hubei Langbowan Biomedicine Co., Ltd.; The white carbon black is a precipitated white carbon black with an average particle size of 100 mesh; Lignin, model: 1-111, manufacturer: Leling Chenhao Polymer Technology Co., Ltd.

[0024] Example 1 A medium-voltage power cable comprises, from inside to outside, a conductor, a conductor shielding layer, an insulation layer, an insulation shielding layer, a metal shielding layer, an inner liner layer, an armor layer, and a sheath layer. The raw material of the sheath layer comprises the following components by weight: polyvinyl chloride 100 parts, magnesium hydroxide 20 parts, dibutyl phthalate 30 parts, antioxidant 1010 1 part, and inorganic composite material 20 parts. The preparation method of the inorganic composite material comprises the following steps: A1, lignin and polyethylene glycol dimethacrylate are added to water and mixed at 80℃ for 30min, then white carbon black is added and mixed, and then dried, crushed, and sieved through a 60-mesh sieve to obtain a premix, wherein the mass ratio of white carbon black, water, lignin, and polyethylene glycol dimethacrylate is 50:40:7:2; A2, the premix is carbonized at 350℃ for 3h under an argon atmosphere to obtain an inorganic composite material; A manufacturing method of a medium-voltage power cable, comprising the following steps: S1, extruding a conductor shielding layer material outside the conductor to form a conductor shielding layer; S2, extruding an insulation layer material outside the conductor shielding layer to form an insulation layer; S3, extruding an insulation shielding layer material outside the insulation layer to form an insulation shielding layer; S4, winding a copper tape outside the insulation shielding layer to form a metal shielding layer; S5, extruding an inner liner layer material outside the metal shielding layer to form an inner liner layer; S6, winding an armor layer material outside the inner liner layer to form an armor layer; S7, uniformly mixing raw materials of a sheath layer, and then melt-extruding the raw materials outside the armor layer to form the sheath layer, thereby obtaining the medium-voltage power cable.

[0025] Example 2 A medium-voltage power cable comprises, from inside to outside, a conductor, a conductor shielding layer, an insulation layer, an insulation shielding layer, a metal shielding layer, an inner liner layer, an armor layer, and a sheath layer. Raw materials of the sheath layer comprise the following components by weight: 100 parts of polyvinyl chloride, 23 parts of magnesium hydroxide, 35 parts of dibutyl phthalate, 2 parts of antioxidant 1010, and 23 parts of inorganic composite material. A preparation method of the inorganic composite material comprises the following steps: A1, mixing lignin and polyethylene glycol dimethacrylate in water at 80°C for 30 min, then adding white carbon black and mixing, drying, crushing, and passing through a 60-mesh sieve to obtain a premix, wherein the mass ratio of white carbon black, water, lignin, and polyethylene glycol dimethacrylate is 50:40:7:2; A2, carbonizing the premix under an argon atmosphere at 400°C for 2.5 h to obtain the inorganic composite material; A manufacturing method of a medium-voltage power cable, comprising the following steps: S1, extruding a conductor shielding layer material outside the conductor to form a conductor shielding layer; S2, extruding an insulation layer material outside the conductor shielding layer to form an insulation layer; S3, extruding an insulation shielding layer material outside the insulation layer to form an insulation shielding layer; S4, winding a copper tape outside the insulation shielding layer to form a metal shielding layer; S5, extruding an inner liner layer material outside the metal shielding layer to form an inner liner layer; S6, winding an armor layer material outside the inner liner layer to form an armor layer; S7, uniformly mixing raw materials of a sheath layer, and then melt-extruding the raw materials outside the armor layer to form the sheath layer, thereby obtaining the medium-voltage power cable.

[0026] Example 3 A medium voltage power cable comprises, from inside to outside, a conductor, a conductor shield layer, an insulation layer, an insulation shield layer, a metal shield layer, an inner liner layer, an armor layer and a sheath layer, and the raw material of the sheath layer comprises the following components by weight: 100 parts of polyvinyl chloride, 25 parts of magnesium hydroxide, 40 parts of dibutyl phthalate, 3 parts of antioxidant 1010 and 25 parts of inorganic composite material. The preparation method of the inorganic composite material comprises the following steps: A1, lignin and polyethylene glycol dimethacrylate are added to water and mixed at 80℃ for 30min, then white carbon black is added and mixed, and then dried, crushed and passed through a 60 mesh sieve to obtain a premix, wherein the mass ratio of white carbon black, water, lignin and polyethylene glycol dimethacrylate is 50:40:7:2; A2, the premix is carbonized at 450℃ for 2h under an argon atmosphere to obtain an inorganic composite material; A method for manufacturing a medium voltage power cable, comprising the following steps: S1, the conductor shield layer material is extruded and wrapped outside the conductor to form a conductor shield layer; S2, the insulation layer material is extruded and wrapped outside the conductor shield layer to form an insulation layer; S3, the insulation shield layer material is extruded and wrapped outside the insulation layer to form an insulation shield layer; S4, the copper strip is wrapped around the outside of the insulation shield layer to form a metal shield layer; S5, the inner liner layer material is extruded and wrapped outside the metal shield layer to form an inner liner layer; S6, the armor layer material is wrapped around the outside of the inner liner layer to form an armor layer; S7, the raw material of the sheath layer is uniformly mixed and then melt-extruded and wrapped outside the armor layer to form a sheath layer, thereby obtaining a medium voltage power cable.

[0027] Example 4 The difference between this example and Example 2 is only that the mass ratio of white carbon black, water, lignin and polyethylene glycol dimethacrylate is 50:40:7:3.

[0028] Example 5 The difference between this example and Example 2 is only that the mass ratio of white carbon black, water, lignin and polyethylene glycol dimethacrylate is 50:40:7:4.

[0029] Example 6 The difference between this embodiment and embodiment 4 is only that the magnesium hydroxide is replaced by modified magnesium hydroxide, and the preparation method of the modified magnesium hydroxide comprises the following steps: 2-acetamidomethyl acrylate is uniformly dispersed in anhydrous ethanol, then magnesium hydroxide is added, and mixed at 40℃ for 1.5h, dried to obtain modified magnesium hydroxide, wherein the mass ratio of magnesium hydroxide to 2-acetamidomethyl acrylate is 100:7, and the mass-volume ratio of magnesium hydroxide to water is 1g:10mL.

[0030] Example 7 The difference between this embodiment and embodiment 6 is only that the 2-acetamidomethyl acrylate is replaced by an equal amount of silane coupling agent KH550.

[0031] Example 8 The difference between this embodiment and embodiment 6 is only that the mass ratio of magnesium hydroxide to 2-acetamidomethyl acrylate is 25:2.

[0032] Example 9 The difference between this embodiment and embodiment 6 is only that the mass ratio of magnesium hydroxide to 2-acetamidomethyl acrylate is 100:9.

[0033] Comparative Example 1 The difference between this comparative example and embodiment 1 is only that the lignin is replaced by an equal amount of polyethylene glycol dimethacrylate.

[0034] Comparative Example 2 The difference between this comparative example and embodiment 1 is only that the polyethylene glycol dimethacrylate is replaced by an equal amount of lignin.

[0035] Comparative Example 3 The difference between this comparative example and embodiment 1 is only that the inorganic composite material is white carbon black.

[0036] Test Example 1 The sheath layer of the medium-voltage power cable prepared in embodiments 1-9 and comparative examples 1-3 is tested according to the following method: 1. 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-Insulation and sheath materials-General test methods-Part 11:General test methods-Thickness and outer dimension measurement-Mechanical property test", and the test specimen is a dumbbell specimen with a thickness of 1.5mm, and the test results are shown in Table 1 below.

[0037] 2. Elongation at break at -40℃: The elongation at break at -40℃ was tested according to the method of GB / T 2951.14-2008 "Cable and optical cable insulation and sheath materials-General test methods-Part 14: General test methods-Low temperature test", the test sample was dumbbell sample, the thickness was 1.5mm, the sample was placed at -40℃ for 16h before testing, the test results were shown in Table 1.

[0038] 3. Flame retardant property: The oxygen index was tested according to the method of GB / T 2406.2-2009 "Plastics-Determination of the burning behavior in terms of flame spread-Part 2: Test methods at room temperature", the sample shape was IV, the determination method was method A, the test results were shown in Table 2.

[0039] Table 1. Performance test results of sheath layer in Examples 1-5 and Comparative Examples 1-3

[0040] The elongation at break and the elongation at break at -40℃ of Examples 1-5 were higher than those of Comparative Examples 1-3, which indicated that the inorganic composite material obtained by adding white carbon black modified by lignin and polyethylene glycol dimethacrylate and then carbonizing to the sheath layer improved the elongation at break and the elongation at break at -40℃ of the sheath layer.

[0041] Table 2. Performance test results of Examples 4 and 6-9

[0042] The oxygen index of Examples 6, 8-9 was higher than that of Examples 4 and 7, which indicated that the modified magnesium hydroxide added to the sheath layer improved the flame retardant property.

[0043] The above only is the preferred embodiment of the present application, and does not 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 medium-voltage power cable, characterized in that, From the inside out, it includes a conductor, a conductor shielding layer, an insulation layer, an insulation shielding layer, a metal shielding layer, an inner lining layer, an armor layer, and a sheath layer. The raw materials of the sheath layer include the following components by weight: 100 parts polyvinyl chloride, 20-25 parts flame retardant, 30-40 parts plasticizer, 1-3 parts antioxidant, and 20-25 parts inorganic composite material. The inorganic composite material is obtained by treating fumed silica with lignin and polyethylene glycol dimethacrylate, followed by crushing and carbonization.

2. A medium-voltage power cable according to claim 1, characterized in that, The mass ratio of the silica, lignin, and polyethylene glycol dimethacrylate is 50:7:2~4.

3. A medium-voltage power cable according to claim 1, characterized in that, The preparation method of the inorganic composite material includes the following steps: A1. After mixing lignin and polyethylene glycol dimethacrylate in a solvent until homogeneous, add fumed silica, mix, dry, and pulverize to obtain a premix. A2. The premixed material is carbonized under an inert gas to obtain an inorganic composite material.

4. A medium-voltage power cable according to claim 3, characterized in that, In step A2, the carbonization temperature is 350~450℃ and the carbonization time is 2~3h.

5. A medium-voltage power cable according to claim 1, characterized in that, The flame retardant is obtained by modifying magnesium hydroxide with methyl 2-acetamidoacrylate.

6. A medium-voltage power cable according to claim 5, characterized in that, The mass ratio of magnesium hydroxide to methyl 2-acetamidoacrylate is 100:7~9.

7. A medium-voltage power cable according to claim 5, characterized in that, The preparation method of the flame retardant includes the following steps: methyl 2-acetamidoacrylate is added to a solvent and dispersed evenly, magnesium hydroxide is added and mixed, and then dried to obtain the flame retardant.

8. A medium-voltage power cable according to claim 1, characterized in that, The plasticizer includes one or more of dibutyl phthalate, dioctyl phthalate, triphenyl phosphate, and dioctyl sebacate.

9. A medium-voltage power cable according to claim 1, characterized in that, The antioxidant includes one or more of antioxidant 1010, antioxidant 168, and antioxidant 2246.

10. A method for manufacturing a medium-voltage power cable, used to prepare a medium-voltage power cable as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Extruding the conductor shielding material around the conductor to form a conductor shielding layer; S2. Extruding the insulating material outside the conductor shielding layer to form an insulating layer; S3. Extruding the insulating shielding layer material over the insulating layer to form an insulating shielding layer; S4. Wrap the metal shielding layer around the outside of the insulating shielding layer to form a metal shielding layer; S5. Extruding the inner lining material over the metal shielding layer to form an inner lining layer; S6. Wrap the armor layer material around the outside of the inner lining layer to form an armor layer; S7. After the raw materials of the sheath layer are mixed evenly, they are melt-extruded and wrapped around the outside of the armor layer to form a sheath layer, thus obtaining a medium-voltage power cable.

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