Medium-voltage power cable and preparation method thereof

Abstract

The invention relates to the technical field of power cables, and provides a medium-voltage power cable and a preparation method thereof.The medium-voltage power cable sequentially comprises a conductor, an insulating layer, an armor layer and a sheath layer from inside to outside, and the sheath layer is prepared from, by weight, 60-70 parts of polystyrene, 10-20 parts of filler, 1-2 parts of antioxidant and 5-10 parts of flame retardant; the polystyrene consists of high impact polystyrene and syndiotactic polystyrene, and the mass ratio of the high impact polystyrene to the syndiotactic polystyrene is (1: 10)-(10: 1). According to the technical scheme, the problem of low strength of the medium-voltage power cable in the prior art is solved.

Description

Technical Field

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

[0002] Medium voltage power cable is a key component of the power transmission system. It is mainly used to transmit and distribute electric energy at a medium voltage level to ensure that electricity is stably and efficiently transmitted from the power generation end to various power consumption terminals. However, medium voltage power cables still have shortcomings in terms of strength. For example, in urban construction, underground cables will be affected by engineering activities such as road construction and excavation. They are easily damaged by external forces during laying and use. In addition, during the cable laying process, they need to pass through various complex road conditions, such as turns, ups and downs, etc., which are prone to stress concentration, resulting in cracks in the cable sheath and insulation layer, which in turn affects the reliability of power supply, has a serious impact on industrial production and residents' lives, and may even cause safety accidents such as fires, causing immeasurable losses. Therefore, how to improve the strength of medium voltage power cables is an urgent problem to be solved. Summary of the invention

[0003] The present invention provides a medium voltage power cable and a preparation method thereof, which solves the problem of low strength of the medium voltage power cable in the related art.

[0004] The technical solution of the present invention is as follows: The present invention provides a medium voltage power cable, which comprises a conductor, an insulating layer, an armor layer and a sheath layer from the inside to the outside, wherein the sheath layer comprises the following component raw materials in parts by weight: 60-70 parts of polystyrene, 10-20 parts of filler, 1-2 parts of antioxidant, and 5-10 parts of flame retardant; The polystyrene consists of high impact polystyrene and syndiotactic polystyrene, and the mass ratio of the high impact polystyrene to the syndiotactic polystyrene is 1:10 to 10:1.

[0005] As a further technical solution, the conductor is made of copper.

[0006] As a further technical solution, the insulating layer is a cross-linked polyethylene insulating layer.

[0007] As a further technical solution, the material of the armor layer is steel strip.

[0008] As a further technical solution, the mass ratio of the high impact polystyrene to the syndiotactic polystyrene is 1-2:3.

[0009] As a further technical solution, the filler includes one or more of carbon fiber, glass fiber, and boron fiber.

[0010] As a further technical solution, the antioxidant includes one or more of antioxidant MB, antioxidant TNP, and antioxidant DNP.

[0011] As a further technical solution, the flame retardant includes one or both of zinc phosphate and zinc aluminate.

[0012] As a further technical solution, when the filler is boron fiber, the boron fiber is modified boron fiber, and the modifier of the modified boron fiber is a phenylfuranol compound.

[0013] In the present invention, the boron fiber is modified by using a phenyl furanol compound, and the π-π stacking force is generated by the phenyl group and the furan group, thereby enhancing the bonding strength between the boron fiber and the polystyrene matrix, and further improving the strength of the medium voltage power cable.

[0014] As a further technical solution, the phenylfuranol compound includes one or more of (5-phenyl-2-furanyl)methanol, [5-(3-aminophenyl)-2-furanyl]methanol, and (5-phenoxy-2-furanyl)methanol.

[0015] In the present invention, the preferred phenylfuranol compound is [5-(3-aminophenyl)-2-furanyl]methanol, which contains an amino group with higher activity than the other two compounds, and can further enhance the bonding strength between the boron fiber and the polystyrene matrix, thereby improving the strength of the medium voltage power cable.

[0016] As a further technical solution, the raw material of the modified boron fiber includes a modifier and boron fiber in a mass ratio of 1 to 2:40.

[0017] As a further technical solution, the preparation method of the modified boron fiber comprises the following steps: dissolving the modifier in a solvent, adding the boron fiber, heating the reaction, filtering and drying to obtain the modified boron fiber.

[0018] The present invention also provides a method for preparing a medium voltage power cable, comprising the following steps: S1. After sequentially coating the conductor with an insulating layer and an armor layer, a semi-finished product is obtained; S2, mixing the raw materials of the sheath layer evenly, extruding and coating the semi-finished product to obtain a cable.

[0019] As a further technical solution, the extrusion temperature is 150-180°C.

[0020] The working principle and beneficial effects of the present invention are: In the present invention, polystyrene is used as raw material in the cable sheath layer, and the polystyrene is composed of high-impact polystyrene and syndiotactic polystyrene. By limiting the mass ratio of the two, the synergistic effect of the two is fully exerted, and the mechanical strength and dimensional stability of the cable sheath layer are improved by absorbing impact energy and dispersing stress, effectively resisting the influence of external pressure and tension on the internal structure of the cable, preventing the conductor, the insulating layer, etc. from being squeezed, deformed, stretched and broken, which affects the electrical performance and service life of the cable, thereby enhancing the strength of the medium-voltage power cable. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In the following examples and comparative examples: Conductor: Material is copper; Insulation layer: cross-linked polyethylene insulation layer; Armor layer: material is steel belt; Impact polystyrene: model GH-660; Syndiotactic polystyrene: model WA552; Boron fiber: diameter 50μm, length 10mm.

[0023] Example 1 A method for preparing a medium voltage power cable comprises the following steps: S1. After sequentially coating the conductor with an insulating layer and an armor layer, a semi-finished product is obtained; S2. Weigh 60 parts of polystyrene, 10 parts of carbon fiber, 1 part of antioxidant MB, and 5 parts of zinc phosphate, mix them evenly, extrude and coat the semi-finished product at 165° C. to obtain a cable; wherein the polystyrene is composed of high-impact polystyrene and syndiotactic polystyrene in a mass ratio of 1:10.

[0024] Example 2 A method for preparing a medium voltage power cable comprises the following steps: S1. After sequentially coating the conductor with an insulating layer and an armor layer, a semi-finished product is obtained; S2. Weigh 65 parts of polystyrene, 15 parts of glass fiber, 1.5 parts of antioxidant TNP, and 8 parts of zinc phosphate, mix them evenly, extrude and coat the semi-finished product at 150° C. to obtain a cable; wherein the polystyrene is composed of high-impact polystyrene and syndiotactic polystyrene in a mass ratio of 3:10.

[0025] Example 3 A method for preparing a medium voltage power cable comprises the following steps: S1. After sequentially coating the conductor with an insulating layer and an armor layer, a semi-finished product is obtained; S2. Weigh 70 parts of polystyrene, 20 parts of boron fiber, 2 parts of antioxidant DNP, and 10 parts of zinc aluminate, mix them evenly, extrude and coat the semi-finished product at 180° C. to obtain a cable; wherein the polystyrene is composed of high-impact polystyrene and syndiotactic polystyrene in a mass ratio of 10:1.

[0026] Example 4 Compared with Example 3, the difference of Example 4 is that the polystyrene consists of high impact polystyrene and syndiotactic polystyrene in a mass ratio of 1:3.

[0027] Example 5 Compared with Example 3, the difference of Example 5 is that the polystyrene consists of high impact polystyrene and syndiotactic polystyrene in a mass ratio of 2:3.

[0028] Example 6 Compared with Example 3, the difference of Example 6 is that the polystyrene consists of high impact polystyrene and syndiotactic polystyrene in a mass ratio of 1:4.

[0029] Example 7 The preparation method of modified boron fiber includes the following steps: dissolving 0.5 parts of (5-phenyl-2-furanyl)-methanol in 400 parts of toluene, adding 20 parts of boron fiber, heating to 80°C for reaction for 12 hours, filtering and drying to obtain modified boron fiber.

[0030] Compared with Example 5, the difference of Example 7 is that the boron fiber is replaced by an equal amount of modified boron fiber obtained by the above preparation method.

[0031] Example 8 Compared with Example 7, the difference in Example 8 is that the added amount of (5-phenyl-2-furanyl)-methanol is 1 part.

[0032] Example 9 Compared with Example 8, Example 9 is different in that (5-phenyl-2-furanyl)-methanol is replaced with an equal amount of [5-(3-aminophenyl)-2-furanyl]methanol.

[0033] Example 10 Compared with Example 8, Example 10 is different in that (5-phenyl-2-furanyl)-methanol is replaced with an equal amount of (5-phenoxy-2-furanyl)methanol.

[0034] Comparative Example 1 Compared with Example 3, the difference in Comparative Example 1 is that the polystyrene is high impact polystyrene.

[0035] Comparative Example 2 Compared with Example 3, the difference in Comparative Example 2 is that the polystyrene is syndiotactic polystyrene.

[0036] The medium voltage power cables prepared in Examples 1 to 10 and Comparative Examples 1 to 2 were tested according to the following method: Sample preparation: Cut the cable sheath along the cable axis and take a narrow strip to make a small dumbbell specimen with a thickness of 3mm, which is the sample to be tested.

[0037] 1. Tensile strength: Test the tensile strength of the sample according to the test method specified in GB / T 12706.3-2020 "Extruded insulated power cables and accessories with rated voltage of 1kV (Um=1.2kV) to 35kV (Um=40.5kV) Part 3: Cables with rated voltage of 35kV (Um=40.5kV)".

[0038] 2. Elongation at break: According to the test method specified in GB / T 12706.3-2020 "Extruded insulated power cables and accessories with rated voltage of 1 kV (Um=1.2 kV) to 35 kV (Um=40.5 kV) Part 3: Cables with rated voltage of 35 kV (Um=40.5 kV)", the elongation at break of the test sample is tested.

[0039] The test results are shown in the following table: Table 1 Performance test results of the sheath layer of the medium voltage power cables prepared in Examples 1 to 10 and Comparative Examples 1 to 2

[0040] Compared with Comparative Examples 1 and 2, Example 3 simultaneously adds high-impact polystyrene and syndiotactic polystyrene. As a result, the tensile strength and elongation at break of Example 3 are better than those of Comparative Examples 1 and 2, indicating that high-impact polystyrene and syndiotactic polystyrene play a synergistic role and can improve the strength of medium-voltage power cables. In Examples 3 to 6, high-impact polystyrene and syndiotactic polystyrene are added in different mass ratios. As a result, the tensile strength and elongation at break of Examples 4 and 5 are better than those of Examples 3 and 6, indicating that when the mass ratio of high-impact polystyrene to syndiotactic polystyrene is 1 to 2:3, the strength of the obtained medium-voltage power cable is better.

[0041] Compared with Example 5, Examples 7 to 10 added modified boron fibers modified with phenylfuranol compounds. As a result, the tensile strength and elongation at break of Examples 7 to 10 were better than those of Example 5, indicating that the addition of modified boron fibers modified with phenylfuranol compounds can improve the strength of medium voltage power cables.

[0042] Compared with Example 8, Examples 9 and 10 added different types of phenylfuranol compounds. As a result, the tensile strength and elongation at break of Example 9 were better than those of Examples 8 and 10, indicating that when the modifier is [5-(3-aminophenyl)-2-furanyl]methanol, the strength of the obtained medium voltage power cable is better.

[0043] The above are only 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 in the protection scope of the present invention.

Claims

1. A medium voltage power cable, characterized in that: The invention comprises a conductor, an insulating layer, an armor layer and a sheath layer in order from the inside to the outside. The sheath layer comprises the following component raw materials in parts by weight: 60 to 70 parts of polystyrene, 10 to 20 parts of filler, 1 to 2 parts of antioxidant and 5 to 10 parts of flame retardant. The polystyrene consists of high-impact polystyrene and syndiotactic polystyrene, and the mass ratio of the high-impact polystyrene to the syndiotactic polystyrene is 1:10 to 10:

1.

2. A medium voltage power cable according to claim 1, characterized in that: The mass ratio of the high impact polystyrene to the syndiotactic polystyrene is 1-2:

3.

3. A medium voltage power cable according to claim 1, characterized in that: The filler includes one or more of carbon fiber, glass fiber and boron fiber.

4. A medium voltage power cable according to claim 1, characterized in that: The antioxidant includes one or more of antioxidant MB, antioxidant TNP and antioxidant DNP.

5. A medium voltage power cable according to claim 1, characterized in that: The flame retardant includes one or both of zinc phosphate and zinc aluminate.

6. A medium voltage power cable according to claim 3, characterized in that: When the filler is boron fiber, the boron fiber is modified boron fiber, and the modifier of the modified boron fiber is a phenylfuranol compound.

7. A medium voltage power cable according to claim 6, characterized in that: The phenyl furanol compound includes one or more of (5-phenyl-2-furanyl)methanol, [5-(3-aminophenyl)-2-furanyl]methanol, and (5-phenoxy-2-furanyl)methanol.

8. A medium voltage power cable according to claim 6, characterized in that: The raw materials of the modified boron fiber include a modifier and boron fiber in a mass ratio of 1 to 2:

40.

9. A medium voltage power cable according to claim 6, characterized in that: The preparation method of the modified boron fiber comprises the following steps: dissolving a modifier in a solvent, adding the boron fiber, heating the reaction, filtering and drying to obtain the modified boron fiber.

10. A method for preparing a medium voltage power cable according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. After sequentially coating the conductor with an insulating layer and an armor layer, a semi-finished product is obtained; S2, mixing the raw materials of the sheath layer evenly, extruding and coating the semi-finished product to obtain a cable.

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