Polyurethane-based environment-friendly water-tree-resistant insulating strong acid corrosion-resistant low-voltage power cable

Abstract

The utility model relates to a polyurethane-based environment-friendly water-tree-resistant insulating strong-acid-corrosion-resistant low-voltage power cable, which is structurally characterized in that a cable core is sequentially wrapped by a second wrapping layer, an outer sheath and a macromolecular strong-acid-corrosion-resistant waterproof layer from inside to outside; the cable core is formed by twisting wire cores and waterproof and anti-corrosion fillers; the waterproof anti-corrosion filler is composed of polyurethane foam, the polyurethane foam is of a hard foam closed-cell structure, and pores are completely isolated from one another; the second wrapping layer is formed by wrapping a layer of double-sided insulating water-blocking tape; the outer sheath is formed by extruding a low-smoke halogen-free flame-retardant thermosetting EVA (Ethylene Vinyl Acetate) material; the macromolecular strong-acid-corrosion-resistant waterproof layer is formed by coating a polyurethane coating; each wire core structurally comprises a conductor, an insulating layer and a first wrapping layer from inside to outside in sequence. The conductor is of a circular structure formed by twisting second-class special-shaped monofilaments; and the first wrapping layer is formed by overlapping and wrapping a layer of semi-conductive nylon tape. The cable has excellent water tree resistance, environmental protection, strong acid corrosion resistance and waterproof performance.

Description

Technical Field

[0001] The utility model relates to a low-voltage power cable based on polyurethane environment-friendly water-tree-resistant insulation and strong acid corrosion resistance, which is suitable for plastic power cables with a rated voltage of 0.6 / 1kV and belongs to the technical field of cables. Background Art

[0002] With the continuous development of science and technology and economy, the market has put forward more requirements for the use scenarios of cables on the basis of meeting electrical performance. Anti-corrosion coating is one of the most important ways and means to solve surface corrosion in the current anti-corrosion field, and ensures the electrical performance, safety performance, mechanical performance, environmental protection, etc. of the cable. Polyurethane materials in polymer materials can be used in the anti-corrosion and waterproof structures of cables due to their anti-corrosion, waterproof, and environmental protection characteristics. There are also discussions in the existing technology:

[0003] The "a moisture-proof and waterproof power cable" with announcement number CN212750446U includes an outer sheath, the outer wall of the outer sheath is provided with a plurality of groups of inflatable strip bubbles, the outer sheath is provided with a metal soft mesh layer, the metal soft mesh layer is provided with an anti-corrosion layer, the anti-corrosion layer is provided with a water-absorbing layer, the water-absorbing layer is provided with an insulating layer, the insulating layer is provided with a waterproof layer, the waterproof layer is provided with a cable core assembly, the cable core assembly includes polyurethane foam filled inside, and the polyurethane foam is provided with a plurality of groups of cable core protection layers, and the cable core is provided inside the cable core protection layer. The outer wall of the cable adopts inflatable strip bubbles. In the actual installation and laying process, the strength of the outer sheath cannot be guaranteed and is easy to be damaged, causing safety hazards. Polyurethane foam of conventional structure has poor flame retardant performance.

[0004] The "watertight cross-linked polyethylene insulated polyurethane sheathed shielded power cable" with announcement number 202694942U is equipped with a tinned copper conductor, a cross-linked polyethylene insulation layer, a water-blocking yarn filling, a water-blocking tape, a tinned copper wire leakage wire, an aluminum-plastic tape shielding layer, a water-blocking tape, and a polyether polyurethane sheath. The tinned copper conductor and the cross-linked polyethylene insulation layer on its outside form an insulated wire core; a water-blocking yarn filling is provided between the outside of the insulated wire core and the water-blocking tape, a tinned copper wire leakage wire is provided in the water-blocking tape, an aluminum-plastic tape shielding layer is provided on the outside of the water-blocking tape, a water-blocking tape is provided on the outside of the aluminum-plastic tape shielding layer, and a polyether polyurethane sheath is provided on the outside of the water-blocking tape. The cable is provided with a tinned copper wire leakage wire in the water-blocking tape. During use, if the cable is flooded, the tinned copper wire leakage wire is easily oxidized and damaged. An aluminum-plastic composite tape is used as a waterproof layer, and the inner and outer layers of the aluminum-plastic composite tape are both water-blocking tapes. The aluminum-plastic composite tape has no attachment layer, and its strength cannot be guaranteed. Its own structural stability and waterproof performance cannot be guaranteed during use.

[0005] The "lightweight, waterproof, and corrosion-resistant overhead cable" with announcement number 203573715U includes several aluminum alloy conductors, which are covered with glass fiber yarn braided layers and polyester rubber insulation layers in sequence to form an insulating core. The insulating core is centered on an elastic column extruded from polyurethane rubber material to form a cable core. The center of the elastic column is provided with phosphating steel wire. The cable core is provided with an aluminum-plastic composite tape wrapping layer and a polyester rubber outer sheath layer in sequence. The outer wall of the polyester rubber outer sheath layer is provided with an epoxy resin layer and a waterproof membrane formed by polyurethane waterproof coating in sequence. The polyurethane waterproof coating of the cable is coated on the surface of the outer sheath. During transportation and laying, it is very easy to be damaged and fall off, and lose its water-blocking performance. The cable of this application is wrapped with a layer of non-woven fabric on the outer layer of the cable as a protective layer for the polyurethane coating, which does not need to be removed after laying. Utility Model Content

[0006] Technical issues to be solved

[0007] In order to meet the requirements of strong acid corrosion resistance and environmental protection in a variety of use environments, the main problems that the utility model cable needs to solve are:

[0008] The existing cable design standards lack relevant design guidelines for cable resistance to strong acid corrosion, while industry users have requirements for strong acid corrosion resistance and environmental protection performance, so environmentally friendly polyurethane materials are introduced as the waterproof and anti-corrosion structure of low-voltage power cables.

[0009] During the design and trial production process, due to the flame retardant requirements of low-voltage power cables and the flammable characteristics of polyurethane materials, it was difficult to obtain products that met the flame retardant requirements according to the existing design guidelines.

[0010] The main reason is that most conventional polyurethane foam materials are open-cell structures with low strength and oxygen in the gaps, which makes the product flammable and releases toxic gases when burned. In order to eliminate these negative effects and make full use of the advantages of polyurethane materials, the following aspects are mainly designed in the structural design of this cable:

[0011] 1. Use closed-cell polyurethane foam, which has a certain strength and helps to enhance the overall mechanical properties of the cable.

[0012] 2. Increase the dehydration of polyurethane foam into carbon in advance, and form a dense expanded carbon layer with heat insulation and oxygen isolation effects on the surface of polyurethane foam to improve flame retardant properties.

[0013] During the foaming process of conventional polyurethane foam, the foam volume cannot be controlled and is prone to absorbing too much oxygen, resulting in instability of its own structure. This cable also has a wrapping structure (such as longitudinally wrapping double-sided insulating water-blocking tape) when it is cabled, which effectively controls the foaming volume, and the material of the wrapping structure is tightly adhered to the polyurethane foam, greatly enhancing the mechanical properties of the cable.

[0014] Through the above design, this cable not only meets the electrical properties of low-voltage power cables, but also meets the requirements of strong acid corrosion resistance test assessment, and improves the corrosion resistance, low toxicity and environmental protection performance of the cable filling and sheath.

[0015] Technical solutions adopted to solve the above technical problems

[0016] A low-voltage power cable based on polyurethane environmentally friendly anti-water tree insulation and strong acid corrosion resistance, the structure of which is:

[0017] It is composed of a second wrapping layer, an outer sheath and a polymer strong acid corrosion resistant waterproof layer wrapped around the cable core from the inside to the outside.

[0018] The cable core is composed of a wire core and a waterproof and anti-corrosion filling twisted together, and the cable pitch ratio ranges from 18 to 35 times; the waterproof and anti-corrosion filling is composed of polyurethane foam, which is a rigid foam closed-cell structure, and the pores are completely isolated from each other, with a pore size of 0.045 to 0.3 mm and a density of 35 to 40 kg / m 3 , thermal conductivity is 0.018~0.023W / (m·K);

[0019] Preferably, the waterproof and anti-corrosion filled polyurethane foam is dehydrated into carbon in advance, and the polyurethane foam surface has an expanded carbon layer. The polyurethane foam dehydrated into carbon in advance forms a dense expanded carbon layer with heat insulation and oxygen isolation on the surface of the polyurethane foam, which helps to improve the flame retardant performance.

[0020] The second wrapping layer is formed by wrapping a layer of double-sided insulating water-blocking tape;

[0021] The outer sheath is made of low-smoke halogen-free flame-retardant thermosetting EVA material extrusion, with a nominal thickness of not less than 3.0 mm and a thickness at the thinnest point of not less than 90% of the nominal thickness;

[0022] The polymer strong acid corrosion resistant waterproof layer is formed by coating with polyurethane coating; the thickness of the polymer strong acid corrosion resistant waterproof layer ranges from 0.5 to 2.2 mm.

[0023] The structure of a single wire core is conductor, insulation layer and first wrapping layer from inside to outside; the conductor is a circular structure composed of two types of special-shaped single wires twisted together;

[0024] The cross-sectional area of ​​the conductor ranges from 6 to 300 mm 2 ;

[0025] The thickness of the insulation layer ranges from 0.20 to 2.90 mm;

[0026] The first wrapping layer is formed by overlapping and wrapping a layer of semi-conductive nylon tape.

[0027] In order to enhance the mechanical properties of the cable, this cable uses thermosetting EVA material as the outer sheath material, with a nominal thickness of not less than 3.0 mm and a thickness at the thinnest point of not less than 90% of the nominal thickness. This thickness of thermosetting EVA material ensures its own strength and the mechanical properties of the cable.

[0028] Furthermore: a layer of semi-conductive nylon tape with a nominal thickness of 0.25 mm is wrapped between the conductor and the insulating layer, and the semi-conductive nylon tape should overlap with an overlap rate of not less than 15%.

[0029] Specifically: the conductor is a copper conductor, an aluminum conductor or an aluminum alloy conductor;

[0030] The copper conductor is composed of twisted shaped copper wires, and the twist pitch diameter ratio ranges from 16 to 32 times;

[0031] The aluminum conductor is composed of twisted shaped aluminum wires, and the twist pitch diameter ratio ranges from 17 to 38 times;

[0032] The aluminum alloy conductor is composed of twisted special-shaped aluminum alloy wires, and the twisted pitch diameter ratio ranges from 17 to 39 times.

[0033] Furthermore: the insulating layer is formed by extruding an environmentally friendly water-tree resistant cross-linked polyethylene insulating material.

[0034] Further: For case a: the cable is composed of copper conductors with a nominal cross-sectional area not exceeding 50mm2, and the cable core has a cable pitch diameter ratio of 18 to 21 times; in other cases except case a, the cable core has a cable pitch diameter ratio of 15 to 35 times.

[0035] Preferred:

[0036] The nominal thickness of the semi-conductive nylon tape of the first wrapping layer is 0.25 mm, and the wrapping overlap rate is not less than 15%;

[0037] The nominal thickness of the double-sided insulating water-blocking tape of the second wrapping layer is 0.35 mm, and the overlap rate is not less than 25%.

[0038] During the foaming process of conventional polyurethane foam, the foam volume cannot be controlled and it is easy to absorb too much oxygen, causing its own structural instability. The second wrapping layer of this cable is a double-sided insulating water-blocking tape wrapped longitudinally during cabling, which effectively controls the foaming volume, and the double-sided insulating water-blocking tape is tightly adhered to the polyurethane foam, greatly enhancing the mechanical properties of the cable.

[0039] The structural performance advantages of the polymer strong acid corrosion resistant waterproof layer using polyurethane coating are as follows:

[0040] Good anti-corrosion performance. The coating has good adhesion, toughness, wear resistance, elasticity and resistance to acid, alkali, salt, oil, petroleum products, benzene solvents and water, boiling water, seawater and chemical atmosphere.

[0041] Strong weather resistance. The coating has good weather resistance, light and color retention, high gloss and decorative properties, as well as good temperature resistance (can withstand 160°C).

[0042] Easy to construct. It dries quickly and can be cured normally at 0℃. It forms a thick film in one go and requires few construction passes. It can be constructed using common construction methods.

[0043] The structural performance advantages of polyurethane foam filling materials are as follows:

[0044] Compared with traditional filling materials, polyurethane has excellent natural properties such as tensile strength, tear strength, impact resistance, wear resistance, weather resistance, hydrolysis resistance, and oil resistance.

[0045] After adopting the above technical solution, the cable has the following beneficial effects:

[0046] (1) Extruded low-smoke halogen-free flame-retardant thermosetting EVA sheath material has good stability while meeting the traditional requirements for resistance to external stress and impact. It does not release harmful gases during long-term use, and the main structure does not collapse, so it can meet the requirements of mobile use.

[0047] (2) Based on the introduction of new materials and new structures, the specific structure of this cable also ensures the requirements of the cable's electrical and mechanical properties.

[0048] This cable can pass the flame retardant B1 bundled combustion test in GB / T18380.33-2008, meet the qualified indicators of low toxicity performance in GB / T 19666-2019, and pass the water permeability test requirements in GB / T 12706-2020.

[0049] The utility model cable uses environmentally friendly filling and flame retardant layers and a specific structure to achieve the effects of improving anti-water tree, anti-corrosion and waterproof performance, and can be used in bridges, offshore platforms, port machinery, factory equipment, storage tanks, pipelines and airports, stadiums and other building power facilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Schematic diagram of the radial cross-section structure of this embodiment.

[0051] In the figure: 1. Conductor; 2. Insulation layer; 3. First winding layer; 4. Waterproof and anti-corrosion filling; 5. Second winding layer; 6. Outer sheath; 7. Polymer strong acid corrosion resistant waterproof layer. DETAILED DESCRIPTION

[0052] The cable is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0053] like Figure 1As shown, in this example, a low-voltage power cable based on polyurethane environmentally friendly anti-water tree insulation and strong acid corrosion resistance has the following structure:

[0054] The cable core is composed of a second wrapping layer 5, an outer sheath 6 and a polymer strong acid corrosion resistant waterproof layer 7 wrapped in sequence from the inside to the outside;

[0055] The cable core is composed of a wire core and a waterproof and anti-corrosion filling 4 twisted together, and the cable pitch ratio ranges from 18 to 35 times; the waterproof and anti-corrosion filling is composed of polyurethane foam, which is a rigid foam closed-cell structure, and the pores are completely isolated from each other, with a pore size of 0.045 to 0.3 mm and a density of 35 to 40 kg / m 3 , thermal conductivity is 0.018~0.023W / (m·K);

[0056] The second wrapping layer 5 is formed by wrapping a layer of double-sided insulating water-blocking tape;

[0057] The outer sheath 6 is made of low-smoke halogen-free flame-retardant thermosetting EVA material extruded, with a nominal thickness of not less than 3.0 mm and a thickness at the thinnest point of not less than 90% of the nominal thickness;

[0058] The polymer strong acid corrosion resistant waterproof layer 7 is formed by coating with polyurethane coating; the thickness of the polymer strong acid corrosion resistant waterproof layer ranges from 0.5 to 2.2 mm;

[0059] The structure of a single wire core is, from inside to outside, conductor 1, insulation layer 2 and first wrapping layer 3; the conductor is a circular structure consisting of two types of special-shaped single wires twisted together;

[0060] The cross-sectional area of ​​the conductor ranges from 6 to 300 mm2;

[0061] The thickness of the insulation layer ranges from 0.20 to 2.90 mm;

[0062] The first wrapping layer is formed by overlapping and wrapping a layer of semi-conductive nylon tape.

[0063] In this example: a layer of semi-conductive nylon tape with a nominal thickness of 0.25 mm is wrapped between the conductor 1 and the insulating layer 2. The semi-conductive nylon tape should overlap with an overlap rate of not less than 15%.

[0064] The conductor is a copper conductor, an aluminum conductor or an aluminum alloy conductor;

[0065] The copper conductor is composed of twisted shaped copper wires, and the twist pitch diameter ratio ranges from 16 to 32 times;

[0066] The aluminum conductor is composed of twisted shaped aluminum wires, and the twist pitch diameter ratio ranges from 17 to 38 times;

[0067] The aluminum alloy conductor is composed of twisted special-shaped aluminum alloy wires, and the twisted pitch diameter ratio ranges from 17 to 39 times.

[0068] The insulating layer 2 is formed by extruding an environmentally friendly water-tree resistant cross-linked polyethylene insulating material.

[0069] There are two situations of cabling pitch diameter ratio. Situation a: For cables composed of copper conductors with a nominal cross-sectional area not exceeding 50mm2, the cabling pitch diameter ratio of the cable core is 18 to 21 times; in other situations except situation a, the cabling pitch diameter ratio of the cable core is 15 to 35 times.

[0070] The nominal thickness of the semi-conductive nylon tape of the first wrapping layer is 0.25 mm, and the wrapping overlap rate is not less than 15%;

[0071] The nominal thickness of the double-sided insulating water-blocking tape of the second wrapping layer is 0.35 mm, and the overlap rate is not less than 25%.

[0072] The polyurethane foam used for waterproof and anti-corrosion filling is dehydrated into carbon in advance, and there is an expanded carbon layer on the surface of the polyurethane foam.

[0073] Polyurethane foam is a common material. Generally, part of polyether polyol (white material) and diisocyanate (black material) are first made into prepolymer, and then the other part of polyether or polyester polyol and diisocyanate, water, catalyst, surfactant, other additives, etc. are added, and mixed under high-speed stirring for foaming. Generally, it is foamed at room temperature, and the molding process is relatively simple.

[0074] The insulation layer is formed by extrusion of environmentally friendly water-tree resistant cross-linked polyethylene insulation material. In this example, the grade of environmentally friendly water-tree resistant cross-linked polyethylene insulation material constituting the insulation layer is TR-YJ-66 (WMY-4202S), and the manufacturer is Zhejiang Wanma Polymer Materials Group Co., Ltd. The insulation material contains cross-linked polyethylene insulation containing additives, polymer modifiers or fillers that can delay the development and growth of water trees in the insulation. The water-tree resistant insulation material has the characteristics of high cleanliness and stable electrical properties, and has excellent water-tree resistant performance, which has a positive effect on improving the performance of cable products.

[0075] The test results of this cable product are as follows, and the test results are qualified:

[0076]

[0077]

Claims

1. A low-voltage power cable based on polyurethane environmentally friendly anti-water tree insulation and strong acid corrosion resistance, characterized by The structure is: It is composed of a second wrapping layer, an outer sheath and a polymer strong acid corrosion resistant waterproof layer wrapped around the cable core from the inside to the outside. The cable core is composed of a wire core and a waterproof and anti-corrosion filling twisted together, and the cable pitch ratio ranges from 18 to 35 times; the waterproof and anti-corrosion filling is composed of polyurethane foam, which is a rigid foam closed-cell structure, and the pores are completely isolated from each other, with a pore size of 0.045 to 0.3 mm and a density of 35 to 40 kg / m 3 , thermal conductivity is 0.018~0.023W / (m·K); The second wrapping layer is formed by wrapping a layer of double-sided insulating water-blocking tape; The outer sheath is made of low-smoke halogen-free flame-retardant thermosetting EVA material extrusion, with a nominal thickness of not less than 3.0 mm and a thickness at the thinnest point of not less than 90% of the nominal thickness; The polymer strong acid corrosion resistant waterproof layer is formed by coating with polyurethane coating; the thickness of the polymer strong acid corrosion resistant waterproof layer ranges from 0.5 to 2.2 mm; The structure of a single wire core is conductor, insulation layer and first wrapping layer from inside to outside; the conductor is a circular structure composed of two types of special-shaped single wires twisted together; The cross-sectional area of ​​the conductor ranges from 6 to 300 mm 2 ; The thickness of the insulation layer ranges from 0.20 to 2.90 mm; The first wrapping layer is formed by overlapping and wrapping a layer of semi-conductive nylon tape.

2. The polyurethane-based environmentally friendly water-tree-resistant and acid-corrosion-resistant low-voltage power cable according to claim 1 is characterized in that A layer of semi-conductive nylon tape with a nominal thickness of 0.25 mm is also wrapped between the conductor and the insulating layer. The semi-conductive nylon tape should overlap with an overlapping rate of not less than 15%.

3. The polyurethane-based environmentally friendly water-tree-resistant and acid-corrosion-resistant low-voltage power cable according to claim 1 is characterized in that The conductor is a copper conductor, an aluminum conductor or an aluminum alloy conductor; The copper conductor is composed of twisted shaped copper wires, and the twist pitch diameter ratio ranges from 16 to 32 times; The aluminum conductor is composed of twisted shaped aluminum wires, and the twist pitch diameter ratio ranges from 17 to 38 times; The aluminum alloy conductor is composed of twisted special-shaped aluminum alloy wires, and the twisted pitch diameter ratio ranges from 17 to 39 times.

4. The polyurethane-based environmentally friendly water-tree-resistant and acid-corrosion-resistant low-voltage power cable according to claim 1 is characterized in that The insulating layer is formed by extruding an environmentally friendly water-tree resistant cross-linked polyethylene insulating material.

5. The polyurethane-based environmentally friendly water-tree-resistant and acid-corrosion-resistant low-voltage power cable according to claim 1 is characterized in that for case a: the nominal cross-sectional area is not more than 50 mm 2 For cables composed of copper conductors, the cable core-to-cable pitch diameter ratio is 18 to 21 times; in other cases except case a, the cable core-to-cable pitch diameter ratio is 15 to 35 times.

6. The polyurethane-based environmentally friendly water-tree-resistant and acid-corrosion-resistant low-voltage power cable according to claim 1 is characterized in that The nominal thickness of the semi-conductive nylon tape of the first wrapping layer is 0.25 mm, and the wrapping overlap rate is not less than 15%; The nominal thickness of the double-sided insulating water-blocking tape of the second wrapping layer is 0.35 mm, and the overlap rate is not less than 25%.

7. The polyurethane-based environmentally friendly water-tree-resistant and acid-corrosion-resistant low-voltage power cable according to claim 1 is characterized in that The polyurethane foam used for waterproof and anti-corrosion filling is dehydrated into carbon in advance, and there is an expanded carbon layer on the surface of the polyurethane foam.

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