Medium voltage power cable and method of manufacturing the same

Abstract

The present application relates to the technical field of cable, and proposes a medium-voltage power cable and a manufacturing method thereof.The 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 lining layer, an armor layer and a sheath layer.The raw material of the sheath layer comprises the following components 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, and then crushing and carbonizing.The above technical solution solves the problem of insufficient low-temperature resistance of the sheath layer of the medium-voltage power cable in the related art.

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 to improve 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:

[0006] 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.

[0007] 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 cracking is avoided.

[0008] The medium-voltage power cable of this invention can effectively inhibit or delay the oxidative degradation process of polyvinyl chloride by adding antioxidants, reduce the aging phenomenon caused by oxidation, help the outer sheath layer maintain good flexibility, strength and other mechanical properties for a long time, and avoid the failure of protection effect due to aging, which would affect the overall structural stability of the cable.

[0009] As a further technical solution, the mass ratio of the silica, lignin and 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, preferably 50:7:3.

[0010] This invention relates to a medium-voltage power cable, which limits the mass ratio of silica, lignin, and polyethylene glycol dimethacrylate in the inorganic composite material to 50:7:2~4, further improving the low-temperature performance of the medium-voltage power cable. If the amount of polyethylene glycol dimethacrylate is too large, it will decompose and generate more gas and pores during the subsequent carbonization process. These defects are prone to cracking under low-temperature stress. If the amount of polyethylene glycol dimethacrylate is too small, it is insufficient to form a complete and uniform coating layer and cross-linking network with lignin, resulting in insufficient surface modification of some silica. After carbonization, there are defects at the interface, and the interfacial gap will increase at low temperatures, which cannot effectively improve the low-temperature resistance of the sheath layer.

[0011] As a further technical solution, the preparation method of the inorganic composite material includes the following steps:

[0012] A1. After mixing lignin and polyethylene glycol dimethacrylate in a solvent until homogeneous, add fumed silica, mix, dry, and pulverize to obtain a premix.

[0013] A2. The premixed material is carbonized under an inert gas to obtain an inorganic composite material.

[0014] As a further technical solution, in step A2, the carbonization temperature is 350~450℃ and the carbonization time is 2~3h.

[0015] As a further technical solution, in step A2, the inert gas is argon.

[0016] As a further technical solution, the flame retardant is obtained by modifying magnesium hydroxide with methyl 2-acetamidoacrylate.

[0017] In this invention, the medium-voltage power cable uses magnesium hydroxide modified with 2-acetamidomethyl acrylate as a flame retardant, which significantly improves the flame retardancy of the sheath layer. Although unmodified magnesium hydroxide has a flame retardant effect, its surface polarity is strong and its compatibility with the polyvinyl chloride organic matrix is ​​poor, resulting in a reduction in flame retardant performance. However, 2-acetamidomethyl acrylate can reduce its surface polarity by forming hydrogen bonds with magnesium hydroxide, improving its compatibility with the polyvinyl chloride matrix, allowing magnesium hydroxide to be more evenly dispersed in the sheath layer, forming a continuous flame retardant barrier, exerting a flame retardant effect, and further improving the flame retardancy of the cable.

[0018] As a further technical solution, the mass ratio of magnesium hydroxide to methyl 2-acetamidoacrylate is 100:7~9, for example, it can be 100:7, 4:0.3, 25:2, 100:9, preferably 25:2.

[0019] As a further technical solution, the preparation method of the flame retardant includes the following steps: 2-acetamidomethyl acrylate is added to a solvent and dispersed evenly, then magnesium hydroxide is added and mixed, and then dried to obtain the flame retardant.

[0020] As a further technical solution, the mixing temperature is 40°C and the mixing time is 2 hours.

[0021] As a further technical solution, the plasticizer includes one or more of dibutyl phthalate, dioctyl phthalate, triphenyl phosphate, and dioctyl sebacate.

[0022] As a further technical solution, the antioxidant includes one or more of antioxidant 1010, antioxidant 168, and antioxidant 2246.

[0023] The present invention also proposes a method for manufacturing a medium-voltage power cable, which includes the following steps:

[0024] S1. Extruding the conductor shielding material around the conductor to form a conductor shielding layer;

[0025] S2. Extruding the insulating material outside the conductor shielding layer to form an insulating layer;

[0026] S3. Extruding the insulating shielding layer material over the insulating layer to form an insulating shielding layer;

[0027] S4. Wrap the metal shielding layer around the outside of the insulating shielding layer to form a metal shielding layer;

[0028] S5. Extruding the inner lining material over the metal shielding layer to form an inner lining layer;

[0029] S6. Wrap the armor layer material around the outside of the inner lining layer to form an armor layer;

[0030] S7. After the raw materials for the sheath layer are mixed evenly, they are melt-extruded and wrapped around the outside of the armor layer to form the sheath layer, thus obtaining a medium-voltage power cable.

[0031] The working principle and beneficial effects of this invention are as follows:

[0032] This invention provides a medium-voltage power cable with a sheath layer based on polyvinyl chloride (PVC). The addition of inorganic composite materials improves the low-temperature mechanical properties of the sheath layer. Under low-temperature conditions, ordinary fillers are prone to debonding and material embrittlement due to compatibility and interfacial bonding with the polymer matrix. However, the composite material in this invention, lignin and polyethylene glycol dimethacrylate are coated on the surface of silica through hydrogen bonds and van der Waals forces, and then carbonized, which improves the compatibility and interfacial bonding between the inorganic filler and the PVC matrix under low-temperature conditions. This ensures that the cable can maintain good mechanical strength in harsh environments such as extreme cold, thus guaranteeing the long-term reliability of the cable. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0034] In the following embodiments and comparative examples:

[0035] Polyvinyl chloride, model: SG-3, manufacturer: Xinjiang Tianye Group Co., Ltd.;

[0036] Polyethylene glycol dimethacrylate, model: lbw, manufacturer: Hubei Langbowan Biomedical Co., Ltd.;

[0037] The silica is precipitated silica with an average particle size of 100 mesh.

[0038] Lignin, model: 1-111, manufacturer: Leling Chenhao Polymer Technology Co., Ltd.

[0039] Example 1

[0040] A medium-voltage power cable comprises, from the inside out, 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 parts magnesium hydroxide, 30 parts dibutyl phthalate, 1 part antioxidant 1010, and 20 parts inorganic composite material.

[0041] The preparation method of inorganic composite materials includes the following steps:

[0042] A1. Add lignin and polyethylene glycol dimethacrylate to water and mix at 80°C for 30 minutes. Then add fumed silica and mix. After drying and pulverizing, pass through a 60-mesh sieve to obtain a premix. The mass ratio of fumed silica, water, lignin and polyethylene glycol dimethacrylate is 50:40:7:2.

[0043] A2. The premixed material was carbonized at 350°C for 3 hours in an argon atmosphere to obtain an inorganic composite material.

[0044] A method for manufacturing a medium-voltage power cable includes the following steps:

[0045] S1. Extruding the conductor shielding material around the conductor to form a conductor shielding layer;

[0046] S2. Extruding the insulating material around the conductor shielding layer to form an insulating layer;

[0047] S3. Extrude the insulating shielding layer material onto the outside of the insulating layer to form an insulating shielding layer;

[0048] S4. Wrap the copper strip around the outside of the insulating shielding layer to form a metal shielding layer;

[0049] S5. Extrude the inner lining material over the metal shielding layer to form the inner lining layer;

[0050] S6. Wrap the armor layer material around the outside of the inner lining layer to form the armor layer;

[0051] S7. After the raw materials for the sheath layer are mixed evenly, they are melt-extruded and wrapped around the outside of the armor layer to form the sheath layer, thus obtaining a medium-voltage power cable.

[0052] Example 2

[0053] A medium-voltage power cable comprises, from the inside out, 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, 23 parts magnesium hydroxide, 35 parts dibutyl phthalate, 2 parts antioxidant 1010, and 23 parts inorganic composite material.

[0054] The preparation method of inorganic composite materials includes the following steps:

[0055] A1. Add lignin and polyethylene glycol dimethacrylate to water and mix at 80°C for 30 minutes. Then add fumed carbon black and mix. After drying and pulverizing, pass through a 60-mesh sieve to obtain a premix. The mass ratio of fumed carbon black, water, lignin and polyethylene glycol dimethacrylate is 50:40:7:2.

[0056] A2. The premixed material was carbonized at 400°C for 2.5 hours in an argon atmosphere to obtain an inorganic composite material.

[0057] A method for manufacturing a medium-voltage power cable includes the following steps:

[0058] S1. Extruding the conductor shielding material around the conductor to form a conductor shielding layer;

[0059] S2. Extruding the insulating material around the conductor shielding layer to form an insulating layer;

[0060] S3. Extrude the insulating shielding layer material onto the outside of the insulating layer to form an insulating shielding layer;

[0061] S4. Wrap the copper strip around the outside of the insulating shielding layer to form a metal shielding layer;

[0062] S5. Extrude the inner lining material over the metal shielding layer to form the inner lining layer;

[0063] S6. Wrap the armor layer material around the outside of the inner lining layer to form the armor layer;

[0064] S7. After the raw materials for the sheath layer are mixed evenly, they are melt-extruded and wrapped around the outside of the armor layer to form the sheath layer, thus obtaining a medium-voltage power cable.

[0065] Example 3

[0066] A medium-voltage power cable comprises, from the inside out, 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, 25 parts magnesium hydroxide, 40 parts dibutyl phthalate, 3 parts antioxidant 1010, and 25 parts inorganic composite material.

[0067] The preparation method of inorganic composite materials includes the following steps:

[0068] A1. Add lignin and polyethylene glycol dimethacrylate to water and mix at 80°C for 30 minutes. Then add fumed silica and mix. After drying and pulverizing, pass through a 60-mesh sieve to obtain a premix. The mass ratio of fumed silica, water, lignin and polyethylene glycol dimethacrylate is 50:40:7:2.

[0069] A2. The premixed material was carbonized at 450°C for 2 hours under an argon atmosphere to obtain an inorganic composite material.

[0070] A method for manufacturing a medium-voltage power cable includes the following steps:

[0071] S1. Extruding the conductor shielding material around the conductor to form a conductor shielding layer;

[0072] S2. Extruding the insulating material around the conductor shielding layer to form an insulating layer;

[0073] S3. Extrude the insulating shielding layer material onto the outside of the insulating layer to form an insulating shielding layer;

[0074] S4. Wrap the copper strip around the outside of the insulating shielding layer to form a metal shielding layer;

[0075] S5. Extrude the inner lining material over the metal shielding layer to form the inner lining layer;

[0076] S6. Wrap the armor layer material around the outside of the inner lining layer to form the armor layer;

[0077] S7. After the raw materials for the sheath layer are mixed evenly, they are melt-extruded and wrapped around the outside of the armor layer to form the sheath layer, thus obtaining a medium-voltage power cable.

[0078] Example 4

[0079] The only difference between this embodiment and Example 2 is that the mass ratio of silica, water, lignin, and polyethylene glycol dimethacrylate is 50:40:7:3.

[0080] Example 5

[0081] The only difference between this embodiment and Embodiment 2 is that the mass ratio of silica, water, lignin, and polyethylene glycol dimethacrylate is 50:40:7:4.

[0082] Example 6

[0083] The only difference between this embodiment and Example 4 is that magnesium hydroxide is replaced with modified magnesium hydroxide. The preparation method of modified magnesium hydroxide includes the following steps: methyl 2-acetamidoacrylate is added to anhydrous ethanol and dispersed evenly, then magnesium hydroxide is added and mixed at 40°C for 1.5 h, and dried to obtain modified magnesium hydroxide. The mass ratio of magnesium hydroxide to methyl 2-acetamidoacrylate is 100:7, and the mass-volume ratio of magnesium hydroxide to water is 1 g:10 mL.

[0084] Example 7

[0085] The only difference between this embodiment and Example 6 is that methyl 2-acetamidoacrylate is replaced with an equal amount of silane coupling agent KH550.

[0086] Example 8

[0087] The only difference between this embodiment and Example 6 is that the mass ratio of magnesium hydroxide to methyl 2-acetamidoacrylate is 25:2.

[0088] Example 9

[0089] The only difference between this embodiment and Example 6 is that the mass ratio of magnesium hydroxide to methyl 2-acetamidoacrylate is 100:9.

[0090] Comparative Example 1

[0091] The only difference between this comparative example and Example 1 is that lignin is replaced with an equal amount of polyethylene glycol dimethacrylate.

[0092] Comparative Example 2

[0093] The only difference between this comparative example and Example 1 is that polyethylene glycol dimethacrylate is replaced with an equal amount of lignin.

[0094] Comparative Example 3

[0095] The only difference between this comparative example and Example 1 is that the inorganic composite material is silica.

[0096] Experimental Example 1

[0097] The sheath layers of the medium-voltage power cables prepared in Examples 1-9 and Comparative Examples 1-3 were tested according to the following method:

[0098] 1. Mechanical properties: The tensile strength and elongation at break were tested according to GB / T 2951.11-2008 "General test methods for insulation and sheath materials of cables and optical cables - Part 11: General test methods for thickness and dimensional measurement of mechanical properties". The test specimen was a dumbbell specimen with a thickness of 1.5 mm. The test results are shown in Table 1 below.

[0099] 2. Elongation at break under tensile stress at -40℃: The elongation at break under tensile stress at -40℃ was tested according to GB / T 2951.14-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Fibers - Part 14: General Test Methods - Low Temperature Test". The test specimen was a dumbbell specimen with a thickness of 1.5 mm. The specimen was placed at -40℃ for 16 hours before the test. The test results are shown in Table 1 below.

[0100] 3. Flame retardant performance: The oxygen index was tested according to GB / T 2406.2-2009 "Determination of flammability by oxygen index method for plastics - Part 2: Room temperature test". The sample shape was IV, and the test method was Method A. The test results are shown in Table 2 below.

[0101] Table 1 Performance test results of the sheath layer in Examples 1-5 and Comparative Examples 1-3

[0102]

[0103] The elongation at break and the elongation at break under low temperature of -40℃ in Examples 1-5 are higher than those in Comparative Examples 1-3, indicating that the inorganic composite material obtained by adding fumed silica to the sheath layer, modifying it with lignin and polyethylene glycol dimethacrylate, and then carbonizing it, has higher elongation at break and elongation at break under low temperature of -40℃.

[0104] Table 2 Performance test results of Examples 4 and 6-9

[0105]

[0106] The oxygen indexes of Examples 6 and 8-9 are higher than those of Examples 4 and 7, indicating that the present invention improves the flame retardant performance by adding modified magnesium hydroxide to the sheath layer.

[0107] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A medium-voltage power cable, characterized in that, From the inside out, it 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. 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 pulverization and carbonization. The mass ratio of the silica, lignin, and polyethylene glycol dimethacrylate is 50:7:2~4.

2. 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.

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

4. 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.

5. A medium-voltage power cable according to claim 4, characterized in that, The mass ratio of magnesium hydroxide to methyl 2-acetamidoacrylate is 100:7~9.

6. A medium-voltage power cable according to claim 4, 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.

7. 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.

8. 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.

9. 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 8, 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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