Rare earth-aluminum alloy fire-resistant power cable for electric power with a rated voltage of 35 kv or less

Abstract

The application relates to the technical field of power cables, and discloses a rare earth aluminum alloy fire-resistant power cable with a rated voltage of 35 kV or below, which comprises, from inside to outside, a cable core, an inner fire-retardant layer, a fire-resistant layer, an oxygen isolation layer, a middle fire-retardant layer, an inner sheath layer, a wrapping layer, an armored layer, an outer fire-retardant layer and an outer sheath layer; the cable core comprises, from inside to outside, a conductor, an inner shielding layer, a crosslinked polyethylene insulation layer, an outer shielding layer and a metal shielding layer; a filling rope is arranged between the cable core and the inner fire-retardant layer; the raw material of the crosslinked polyethylene insulation layer comprises polyethylene, a nitro-containing phosphate ester compound modified inorganic porous particle and a crosslinking agent; the nitro-containing phosphate ester compound in the nitro-containing phosphate ester compound modified inorganic porous particle is a diester phosphate compound containing a nitro group and / or a triester phosphate compound containing two or more nitro groups. Through the technical scheme, the problem of poor fire resistance and fire retardance of the rare earth aluminum alloy power cable in the related art is solved.

Description

Technical Field

[0001] This invention relates to the field of power cable technology, specifically to a rare earth aluminum alloy fire-resistant power cable for power applications with a rated voltage of 35kV and below. Background Technology

[0002] Rare earth aluminum alloy power cables are power cables that use rare earth aluminum alloys as conductors. Rare earth aluminum alloys are formulated by adding a small amount of rare earth metals to aluminum. They have advantages such as high strength, good plasticity, wear resistance, corrosion resistance, electrical conductivity, and thermal conductivity, and their application in power cables has attracted much attention.

[0003] With increasing public concern for personal and property safety, higher demands are being placed on the fire resistance and flame retardancy of rare-earth aluminum alloy power cables. Good fire resistance ensures the continuous operation of critical loads such as fire-fighting equipment, emergency lighting, and evacuation guidance during a fire, buying time for evacuation and firefighting rescue. Good flame retardancy inhibits or slows combustion upon contact with flames and self-extinguishes after the flame is removed, preventing the spread of flames along the cable and reducing the fire's extent. Therefore, improving the fire resistance and flame retardancy of rare-earth aluminum alloy power cables is a pressing technical challenge that needs to be addressed. Summary of the Invention

[0004] This invention proposes a rare earth aluminum alloy fire-resistant power cable for power applications with a rated voltage of 35kV and below, which solves the problem of poor fire resistance and flame retardancy of rare earth aluminum alloy power cables in related technologies.

[0005] The technical solution of the present invention is as follows:

[0006] A rare-earth aluminum alloy fire-resistant power cable with a rated voltage of 35kV and below comprises, from the inside out, a cable core, an inner flame-retardant layer, a fire-resistant layer, an oxygen barrier layer, a middle flame-retardant layer, an inner sheath layer, a wrapping layer, an armor layer, an outer flame-retardant layer, and an outer sheath layer; the cable core comprises, from the inside out, a conductor, an inner shielding layer, a cross-linked polyethylene insulation layer, an outer shielding layer, and a metal shielding layer; the number of cable cores is 3; a filler rope is provided between the cable cores and the inner flame-retardant layer; the raw materials of the cross-linked polyethylene insulation layer include polyethylene, inorganic porous granules modified with nitro-containing phosphate ester compounds, and a cross-linking agent; the nitro-containing phosphate ester compounds in the inorganic porous granules modified with nitro-containing phosphate ester compounds are nitro-containing diester compounds and / or nitro-containing trister compounds.

[0007] As a further technical solution, the raw materials for the nitro-containing phosphate ester compound modified inorganic porous granules include nitro-containing phosphate ester compounds and inorganic porous granules in a mass ratio of 1~10:100.

[0008] In the raw materials of the phosphate ester compound modified inorganic porous granules of the present invention, the mass ratio of the nitro phosphate ester compound to the inorganic porous granules is 1 to 10:100, for example, it can be 1:100, 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100 or 10:100, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0009] As a further technical solution, the preparation method of the inorganic porous granules modified by the nitro phosphate compound includes the following steps: dissolving the nitro phosphate compound, adding it to the inorganic porous granules and stirring, drying, to obtain the inorganic porous granules modified by the nitro phosphate compound.

[0010] In this invention, the nitro phosphate diester compound can be any one or more nitro phosphate diester compounds, such as bis(p-nitrophenyl) phosphate, bis(p-nitrobenzyl) phosphate, preferably bis(p-nitrophenyl) phosphate.

[0011] In this invention, the phosphate triester compound containing two or more nitro groups can be any one or more phosphate triester compounds containing two or more nitro groups, such as tris(4-nitrophenyl) phosphate, tris(p-nitrobenzyl) phosphate, preferably tris(4-nitrophenyl) phosphate.

[0012] In this invention, when dissolving phosphate compounds containing nitro groups, the solvent used can be any conventional solvent that can dissolve them. For example, methanol can be used to dissolve bis(p-nitrophenyl) phosphate, and chloroform can be used to dissolve tris(4-nitrophenyl) phosphate.

[0013] As a further technical solution, the stirring includes a first stirring and a second stirring; the rotation speed of the first stirring is 3000~5000 rpm; for example, it can be 3000 rpm, 3200 rpm, 3500 rpm, 4000 rpm, 4500 rpm, 4700 rpm, or 5000 rpm, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable; the first stirring time is 15~25 min, for example, it can be 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min, or 25 min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable; The same applies; the second stirring speed is 200~300 rpm, for example, it can be 200 rpm, 210 rpm, 220 rpm, 230 rpm, 240 rpm, 250 rpm, 260 rpm, 270 rpm, 280 rpm, 290 rpm or 300 rpm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable; the second stirring time is 10~20 min, for example, it can be 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min or 20 min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0014] As a further technical solution, the nitro-containing phosphate compound is a nitro-containing phosphate diester compound, preferably a bis(p-nitrophenyl) phosphate.

[0015] In this invention, the use of nitro-containing phosphate diester compounds to modify inorganic porous granules further improves the flame retardancy and mechanical strength of cross-linked polyethylene insulation layers. This is because the molecular structure of the nitro-containing phosphate diester compound contains individual hydroxyl groups, which can form strong hydrogen bonds with the hydroxyl groups on the surface of the inorganic porous granules, thus providing a good modification effect.

[0016] In this invention, the inorganic porous granules can be any one or more conventional inorganic porous granules in the art, preferably porous silica.

[0017] In this invention, the conductor is a rare earth aluminum alloy conductor with the composition Al-Mg-Si-Re.

[0018] In this invention, the metal shielding layer can be a copper wire shielding layer or a copper strip shielding layer, preferably a copper strip shielding layer.

[0019] As a further technical solution, the inner flame-retardant layer, the middle flame-retardant layer, and the outer flame-retardant layer are each independently a low-smoke halogen-free flame-retardant strip.

[0020] As a further technical solution, the refractory layer is a ceramicized polyolefin oxygen barrier material.

[0021] As a further technical solution, the oxygen barrier layer is a low-smoke, halogen-free, flame-retardant polyolefin oxygen barrier material.

[0022] As a further technical solution, the wrapping layer is a double-sided ceramicized armor strip; the armor layer is a galvanized steel strip.

[0023] As a further technical solution, the mass ratio of the polyethylene, the nitrophosphate ester modified inorganic porous granules, and the crosslinking agent is 100:10~20:1~3, for example, it can be 100:10:1, 100:10:2, 100:10:3, 100:15:1, 100:15:2, 100:15:3, 100:20:1 or 100:20:3, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0024] In this invention, the crosslinking agent can be any one or more conventional crosslinking agents in the art, such as peroxides, preferably dicumyl peroxide.

[0025] The working principle and beneficial effects of this invention are as follows:

[0026] 1. The cable structure in this invention comprises, from the inside out, a cable core, an inner flame-retardant layer, a fire-resistant layer, an oxygen barrier layer, a middle flame-retardant layer, an inner sheath layer, a wrapping layer, an armor layer, an outer flame-retardant layer, and an outer sheath layer; wherein the cable core comprises, from the inside out, a conductor, an inner shielding layer, a cross-linked polyethylene insulation layer, an outer shielding layer, and a metal shielding layer. By optimizing the cable structure and incorporating a fire-resistant layer, the fire resistance of the rare earth aluminum alloy power cable is improved. The resulting rare earth aluminum alloy power cable, after undergoing fire resistance testing according to the methods in TICW 8-2012 "Extruded Insulated Fire-Resistant Power Cables with Rated Voltages from 6kV (Um=7.2kV) to 35kV (Um=40.5kV)," all showed satisfactory performance.

[0027] 2. In this invention, inorganic porous granules are modified with nitro-containing phosphate compounds, wherein the nitro-containing phosphate compounds are nitro-containing diester compounds and / or nitro-containing triester compounds, which improve the flame retardancy of the cross-linked polyethylene insulation layer, thereby improving the flame retardancy of rare earth aluminum alloy power cables. Furthermore, after inorganic porous granules are modified with phosphate diester compounds containing nitro groups and / or phosphate triester compounds containing two or more nitro groups, the nitro groups can form hydrogen bonds with the hydroxyl groups on the surface of the inorganic porous granules due to the presence of free hydroxyl groups in the molecular structure of the nitro phosphate diester compounds, causing the nitro groups to turn outwards. Although the phosphate triester compounds containing two or more nitro groups do not have free hydroxyl groups in their molecular structure, they do contain two or more nitro groups, which can form hydrogen bonds with the hydroxyl groups on the surface of the inorganic porous granules, and at the same time, some nitro groups turn outwards. After modification with the above two substances, the surface of the inorganic porous granules can be organically modified, so that its outer surface has nitro groups. The nitro groups have low polarity, which improves the compatibility with the cross-linked polyethylene insulation layer base material, thereby improving the mechanical strength of the cross-linked polyethylene insulation layer. Detailed Implementation

[0028] 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.

[0029] In the following embodiments and comparative examples:

[0030] The polyethylene is low-density polyethylene (LDPE) from Yanshan Petrochemical, specifically LD113.

[0031] The inorganic porous granules are fumed silica with a particle size of 500 nm and a density of 2.66 g / cm³. 3 Its specific surface area is 126.53 m². 2 / g;

[0032] A rare-earth aluminum alloy fire-resistant power cable with a rated voltage of 35kV and below comprises, from the inside out, three cable cores, a first low-smoke halogen-free flame-retardant strip, a ceramicized polyolefin oxygen barrier, a second low-smoke halogen-free flame-retardant strip, a polyolefin sheath layer, a double-sided ceramicized armor strip, a galvanized steel strip armor layer, a third low-smoke halogen-free flame-retardant strip, and a low-smoke halogen-free polyolefin outer sheath layer; a filler rope is provided between the cable cores and the first low-smoke halogen-free flame-retardant strip; each cable core comprises, from the inside out, a rare-earth aluminum alloy conductor with an Al-Mg-Si-Re composition, an inner shielding layer, a cross-linked polyethylene insulation layer, an outer shielding layer, and a copper strip shielding layer; the inner shielding layer, the cross-linked polyethylene insulation layer, and the outer shielding layer are produced using a three-layer co-extrusion process; the cross-linked polyethylene insulation layer is prepared by the following method:

[0033] Example 1

[0034] S1. Dissolve 1 part of bis(p-nitrophenyl) phosphate in 150 parts of methanol, add 100 parts of inorganic porous granules, stir at 5000 rpm for 15 min, then stir at 300 rpm for 10 min, and dry to obtain modified inorganic porous granules.

[0035] S2. After mixing 100 parts of polyethylene and 10 parts of modified inorganic porous granules evenly, add 3 parts of dicumyl peroxide and continue mixing. Co-extrude the blend with the blends of the other two layers and cross-link at 170℃ and 15MPa for 30min to obtain a cross-linked polyethylene insulation layer.

[0036] Example 2

[0037] S1. Dissolve 1 part of bis(p-nitrophenyl) phosphate in 150 parts of methanol, add 100 parts of inorganic porous granules, stir at 3000 rpm for 25 min, then stir at 200 rpm for 20 min, and dry to obtain modified inorganic porous granules.

[0038] S2. After mixing 100 parts of polyethylene and 20 parts of modified inorganic porous granules evenly, add 1 part of dicumyl peroxide and continue mixing. Co-extrude the blend with the blends of the other two layers and cross-link at 170℃ and 15MPa for 30min to obtain a cross-linked polyethylene insulation layer.

[0039] Example 3

[0040] S1. Dissolve 5 parts of bis(p-nitrophenyl) phosphate in 150 parts of methanol, add 100 parts of inorganic porous granules, stir at 5000 rpm for 15 min, then stir at 300 rpm for 10 min, and dry to obtain modified inorganic porous granules.

[0041] S2. After mixing 100 parts of polyethylene and 10 parts of modified inorganic porous granules evenly, add 3 parts of dicumyl peroxide and continue mixing. Co-extrude the blend with the blends of the other two layers and cross-link at 170℃ and 15MPa for 30min to obtain a cross-linked polyethylene insulation layer.

[0042] Example 4

[0043] S1. Dissolve 10 parts of bis(p-nitrophenyl) phosphate in 150 parts of methanol, add 100 parts of inorganic porous granules, stir at 5000 rpm for 15 min, then stir at 300 rpm for 10 min, and dry to obtain modified inorganic porous granules.

[0044] S2. After mixing 100 parts of polyethylene and 10 parts of modified inorganic porous granules evenly, add 3 parts of dicumyl peroxide and continue mixing. Co-extrude the blend with the blends of the other two layers and cross-link at 170℃ and 15MPa for 30min to obtain a cross-linked polyethylene insulation layer.

[0045] Example 5

[0046] S1. Dissolve 5 parts of tris(4-nitrophenyl) phosphate in 150 parts of chloroform, add 100 parts of inorganic porous granules, stir at 5000 rpm for 15 min, then stir at 300 rpm for 10 min, and dry to obtain modified inorganic porous granules.

[0047] S2. After mixing 100 parts of polyethylene and 10 parts of modified inorganic porous granules evenly, add 3 parts of dicumyl peroxide and continue mixing. Co-extrude the blend with the blends of the other two layers and cross-link at 170℃ and 15MPa for 30min to obtain a cross-linked polyethylene insulation layer.

[0048] Comparative Example 1

[0049] After mixing 100 parts of polyethylene and 10 parts of inorganic porous granules evenly, 3 parts of dicumyl peroxide are added and the mixture is continued to be mixed. The mixture is then co-extruded with the other two layers of the mixture and cross-linked at 170℃ and 15MPa for 30 minutes to obtain a cross-linked polyethylene insulation layer.

[0050] The oxygen index of the cross-linked polyethylene insulation layer was tested according to the method in GB / T 2406.2-2009. The sample size was 100 mm in length, 10 mm in width, and 4 mm in thickness. The ignition method was Method A, top-side ignition. The tensile strength was tested according to the method in GB / T 2951.11-2008, "General Test Methods for Insulation and Sheath Materials of Cables and Optical Fibers - Part 11: General Test Methods - Thickness and Dimensional Measurements - Mechanical Properties Tests". The test sample was a dumbbell specimen with a thickness of 3 mm. The test results are recorded in Table 1.

[0051] Table 1. Test results of flame retardancy and tensile strength of cross-linked polyethylene insulation layer

[0052]

[0053] As shown in Table 1, the oxygen index and tensile strength of the cross-linked polyethylene insulation layers obtained in Examples 1-5 are higher than those in Comparative Example 1. This indicates that modifying inorganic porous granules with nitro-containing phosphate compounds, especially when the nitro-containing phosphate compounds are nitro-containing diesters and / or triesters containing two or more nitro groups, can improve the flame retardancy and mechanical strength of the cross-linked polyethylene insulation layers. However, if nitro-containing mono-phosphate compounds, such as p-nitrophenyl phosphate, are used, their molecular structure contains two hydroxyl groups on the phosphate group, which easily form intramolecular hydrogen bonds. Since hydrogen bonds are saturable, when these compounds are used to modify inorganic porous granules, the nitro groups tend to form hydrogen bonds with the hydroxyl groups on their surface, causing the hydroxyl groups on the phosphate group to turn outward. The high polarity of the hydroxyl groups results in poor compatibility with the cross-linked polyethylene insulation layer base material, easily leading to interfacial defects within the material. Simultaneously, it causes agglomeration and migration of the inorganic porous granules, affecting the overall performance of the material.

[0054] The rare earth aluminum alloy fire-resistant power cables with rated voltage of 35kV and below obtained in each embodiment were subjected to fire resistance tests according to the method in TICW 8-2012 "Extruded Insulated Fire-Resistant Power Cables with Rated Voltage of 6kV (Um=7.2kV) to 35kV (Um=40.5kV)". All of them passed the test, indicating that the rare earth aluminum alloy power cables provided by the present invention have good fire resistance.

[0055] 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 rare-earth aluminum alloy fire-resistant power cable with a rated voltage of 35kV and below, characterized in that, The cable core comprises, from the inside out, a cable core, an inner flame-retardant layer, a fire-resistant layer, an oxygen barrier layer, a middle flame-retardant layer, an inner sheath layer, a wrapping tape layer, an armor layer, an outer flame-retardant layer, and an outer sheath layer. The cable core comprises, from the inside out, a conductor, an inner shielding layer, a cross-linked polyethylene insulation layer, an outer shielding layer, and a metal shielding layer. There are three cable cores. A filler rope is provided between the cable cores and the inner flame-retardant layer. The raw materials for the cross-linked polyethylene insulation layer include polyethylene, inorganic porous granules modified with nitro-containing phosphate ester compounds, and a cross-linking agent. The nitro-containing phosphate ester compounds in the inorganic porous granules modified with nitro-containing phosphate ester compounds are nitro-containing diester compounds and / or nitro-containing triester compounds.

2. The rare-earth aluminum alloy fire-resistant power cable for power applications with a rated voltage of 35kV and below as described in claim 1, characterized in that, The raw materials for the nitro-containing phosphate ester compound modified inorganic porous granules include nitro-containing phosphate ester compounds and inorganic porous granules in a mass ratio of 1~10:

100.

3. A rare-earth aluminum alloy fire-resistant power cable with a rated voltage of 35kV and below for power applications, as described in claim 2, is characterized in that... The method for preparing the inorganic porous granules modified with nitro phosphate ester compounds includes the following steps: dissolving the nitro phosphate ester compound, adding it to the inorganic porous granules and stirring, then drying to obtain the inorganic porous granules modified with nitro phosphate ester compounds.

4. A rare-earth aluminum alloy fire-resistant power cable with a rated voltage of 35kV and below for power applications, as described in claim 3, is characterized in that... The stirring includes a first stirring and a second stirring. The first stirring has a rotation speed of 3000~5000 rpm and a time of 15~25 min, while the second stirring has a rotation speed of 200~300 rpm and a time of 10~20 min.

5. A rare-earth aluminum alloy fire-resistant power cable with a rated voltage of 35kV and below for power applications, as described in claim 2, is characterized in that... The nitro-containing phosphate ester compound is a nitro-containing phosphate diester compound; The inorganic porous granules are porous silica.

6. A rare-earth aluminum alloy fire-resistant power cable with a rated voltage of 35kV and below for power applications, as described in claim 5, is characterized in that... The nitro-containing phosphate diester compound is a bis(p-nitrophenyl) phosphate.

7. A rare-earth aluminum alloy fire-resistant power cable with a rated voltage of 35kV and below for power applications, as described in claim 1, is characterized in that... The conductor is a rare-earth aluminum alloy conductor; the metal shielding layer is a copper strip shielding layer.

8. A rare-earth aluminum alloy fire-resistant power cable with a rated voltage of 35kV and below, as described in claim 1, is characterized in that... The inner flame-retardant layer, the middle flame-retardant layer, and the outer flame-retardant layer are each independently a low-smoke halogen-free flame-retardant strip; The refractory layer is a ceramicized polyolefin oxygen barrier material; The oxygen barrier layer is a low-smoke, halogen-free, flame-retardant polyolefin oxygen barrier material.

9. A rare-earth aluminum alloy fire-resistant power cable with a rated voltage of 35kV and below for power applications, as described in claim 1, is characterized in that... The wrapping layer is a double-sided ceramicized armor strip; the armor layer is a galvanized steel strip.

10. A rare-earth aluminum alloy fire-resistant power cable with a rated voltage of 35kV and below, as described in claim 1, is characterized in that... The mass ratio of the polyethylene, the nitrophosphate ester modified inorganic porous granules, and the crosslinking agent is 100:10~20:1~3.

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