High-strength wire cable for rail transit and preparation method and application thereof

Abstract

The invention relates to the technical field of wires and cables, and provides a high-strength wire and cable for rail transit and a preparation method and application thereof. A high-strength wire cable for rail transit comprises a conductor, an insulating layer, an inner protective layer, an armor layer and an outer protective layer from inside to outside in sequence, and the outer protective layer is prepared from, by weight, 70-80 parts of polyethylene, 20-30 parts of ethylene-vinyl acetate copolymer, 10-15 parts of polyvinyl chloride, 10-12 parts of compatilizer, 70-80 parts of flame retardant, 2-3 parts of lubricant, 1-3 parts of antioxidant and 2-4 parts of cross-linking agent; the flame retardant is prepared from magnesium hydroxide, composite hollow glass microspheres and melamine cyanurate. According to the technical scheme, the problem of poor flame retardance of the outer protective layer of the high-strength wire cable for rail transit in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of wires and cables, and in particular to a high-strength wire and cable for rail transit, and a preparation method and application thereof. Background Art

[0002] Currently, polymer materials such as polyethylene, ethylene-vinyl acetate copolymer, and polyvinyl chloride are widely used as the outer sheath base materials for high-strength rail transit wires and cables. However, these materials struggle to meet the stringent flame retardancy requirements of rail transit, necessitating the addition of flame retardants to enhance their flame retardancy. Traditional flame retardants, such as halogenated flame retardants, while highly effective, release large amounts of toxic gases during combustion, polluting the environment and posing serious hazards to personnel and equipment. This is inconsistent with the green and safe development philosophy of rail transit. Common inorganic flame retardants, such as aluminum hydroxide and magnesium hydroxide, offer advantages such as low smoke, non-toxicity, and environmental friendliness, but suffer from relatively low flame retardancy. Large amounts of these agents are often required to achieve the desired flame retardancy level, significantly degrading the mechanical properties of the outer sheath of high-strength rail transit wires and cables, such as brittleness and reduced tensile strength. This impacts the overall performance and service life of the outer sheath. Furthermore, these inorganic flame retardants have poor dispersion in the matrix and are prone to agglomeration, further weakening their flame retardant effectiveness.

[0003] Given the extremely high requirements of rail transit on the flame retardant properties of the outer sheath of wires and cables, developing new and efficient flame retardants and improving the flame retardant system to improve the flame retardant properties of the outer sheath of high-strength wires and cables for rail transit has become a key issue that needs to be urgently addressed in this field. Summary of the Invention

[0004] The present invention provides a high-strength wire and cable for rail transit, a preparation method and an application thereof, which solve the problem of poor flame retardancy of the outer sheath of the high-strength wire and cable for rail transit in the related art.

[0005] The technical solutions of the present invention are as follows: The present invention provides a high-strength wire and cable for rail transit, characterized in that the wire and cable comprises, from the inside to the outside, a conductor, an insulating layer, an inner sheath, an armor layer, and an outer sheath, wherein the outer sheath comprises the following components in parts by weight: 70-80 parts of polyethylene, 20-30 parts of ethylene-vinyl acetate copolymer, 10-15 parts of polyvinyl chloride, 10-12 parts of a compatibilizer, 70-80 parts of a flame retardant, 2-3 parts of a lubricant, 1-3 parts of an antioxidant, and 2-4 parts of a cross-linking agent; The flame retardant includes magnesium hydroxide, composite hollow glass microspheres and melamine cyanurate; The preparation method of the composite hollow glass microspheres comprises the following steps: The hollow glass microspheres are added into water, and copper chloride, tin tetrachloride and sodium hydroxide are added thereto, mixed evenly, subjected to hydrothermal reaction, concentrated and calcined to obtain the composite hollow glass microspheres.

[0006] As a further technical solution, the mass ratio of the hollow glass microspheres, copper chloride, and tin tetrachloride is 20:9:7-8; The concentration of the sodium hydroxide in water is 0.3-0.5 mol / L; The hydrothermal reaction temperature is 220-230° C., the pressure is 3.4-3.6 MPa, and the time is 16-20 h.

[0007] As a further technical solution, the mass volume ratio of hollow glass microspheres and water is 1g:30~40mL.

[0008] As a further technical solution, the mass ratio of the magnesium hydroxide, the composite hollow glass microspheres, and melamine cyanurate is 7:7:3-4.

[0009] In the outer sheath of the high-strength wire and cable for rail transit of the present invention, the mass ratio of magnesium hydroxide, composite hollow glass microspheres, and melamine cyanurate can be 7:7:3, 7:7:3.1, 7:7:3.2, 7:7:3.3, 7:7:3.4, 7:7:3.5, 7:7:3.6, 7:7:3.7, 7:7:3.8, 7:7:3.9, or 7:7:4, preferably 7:7:4.

[0010] As a further technical solution, the magnesium hydroxide is composite magnesium hydroxide; The raw materials of the composite magnesium hydroxide include magnesium hydroxide and butyl p-hydroxybenzoate.

[0011] As a further technical solution, the preparation method of the composite magnesium hydroxide comprises the following steps: Magnesium hydroxide is added to ethanol, butyl p-hydroxybenzoate is added, the mixture is stirred, concentrated, and dried to obtain the composite magnesium hydroxide.

[0012] In the outer sheath of the high-strength wire and cable for rail transit of the present invention, magnesium hydroxide compounded with butyl parahydroxybenzoate is used, which improves the compatibility of the magnesium hydroxide with the system, makes it easier for the magnesium hydroxide to be mixed evenly with other materials during the mixing process, reduces agglomeration, and therefore reduces the stress concentration phenomenon of the outer sheath of the high-strength wire and cable for rail transit when subjected to external effects, thereby improving the tensile strength of the outer sheath of the high-strength wire and cable for rail transit.

[0013] As a further technical solution, in the raw materials of the composite magnesium hydroxide, the mass ratio of magnesium hydroxide to butyl parahydroxybenzoate is 30-50:1.

[0014] In the outer sheath of the high-strength wire and cable for rail transit of the present invention, when the mass ratio of magnesium hydroxide to butyl parahydroxybenzoate is 30 to 50:1, the tensile strength of the outer sheath of the high-strength wire and cable for rail transit is further improved.

[0015] In the outer sheath of the high-strength wire and cable for rail transit of the present invention, the mass ratio of magnesium hydroxide to butyl parahydroxybenzoate can be 30:1, 31:1, 32:1, 33:1, 34:1, 35:1, 36:1, 37:1, 38:1, 39:1, 40:1, 41:1, 42:1, 43:1, 44:1, 45:1, 46:1, 47:1, 48:1, 49:1, 50:1, and preferably 50:1.

[0016] As a further technical solution, the stirring speed is 400-500 rpm, the temperature is 50-55° C., and the time is 4-4.5 h.

[0017] As a further technical solution, the mass volume ratio of the magnesium hydroxide to ethanol is 1g:15~20mL.

[0018] As a further technical solution, the conductor is made of aluminum.

[0019] As a further technical solution, the material of the insulating layer is silane cross-linked polyethylene.

[0020] As a further technical solution, the material of the armor layer is steel strip.

[0021] As a further technical solution, the compatibilizer includes one of maleic anhydride grafted polyethylene and maleic anhydride grafted polypropylene.

[0022] In the outer sheath of the high-strength wire and cable for rail transit of the present invention, the compatibilizer can be any one or more of conventional compatibilizers, and can be one or more of maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene, ethylene-acrylic acid copolymer, and styrene-maleic anhydride copolymer, preferably one of maleic anhydride grafted polyethylene and maleic anhydride grafted polypropylene.

[0023] As a further technical solution, the lubricant includes one of stearic acid and paraffin.

[0024] In the outer sheath of the high-strength wire and cable for rail transit of the present invention, the lubricant can be any one or more conventional lubricants, and can be one or more of polyethylene wax, oxidized polyethylene wax, zinc stearate, stearic acid, and paraffin, preferably one of stearic acid and paraffin.

[0025] As a further technical solution, the antioxidant includes one of antioxidant 1010 and antioxidant 1076.

[0026] In the outer sheath of the high-strength wire and cable for rail transit of the present invention, the antioxidant can be any one or more of conventional antioxidants, and can be one or more of antioxidant 168, antioxidant 3114, antioxidant 2246, antioxidant 1010, and antioxidant 1076, preferably one of antioxidant 1010 and antioxidant 1076.

[0027] As a further technical solution, the cross-linking agent includes one of trimethylolpropane triacrylate and trimethylolpropane trimethacrylate.

[0028] In the outer sheath of the high-strength wire and cable for rail transit of the present invention, the crosslinking agent can be any one or more of conventional crosslinking agents, and can be one or more of triallyl isocyanurate, triallyl cyanurate, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate, preferably one of trimethylolpropane triacrylate and trimethylolpropane trimethacrylate.

[0029] The present invention also provides a method for preparing a high-strength wire and cable for rail transit, which is used to prepare the high-strength wire and cable for rail transit, comprising the following steps: S1. An insulating layer, an inner protective layer and an armor layer are sequentially arranged outside the conductor; S2. The raw materials of the outer sheath are mixed and extruded outside the armor layer, and irradiated and cross-linked to obtain the high-strength wire and cable for rail transit.

[0030] As a further technical solution, the irradiation dose is 15~18 Mard.

[0031] The present invention also proposes the application of the high-strength wire and cable for rail transit or the high-strength wire and cable for rail transit prepared by the preparation method of the high-strength wire and cable for rail transit in the field of rail transit.

[0032] The working principle and beneficial effects of the present invention are: The present invention adopts a flame retardant system composed of magnesium hydroxide, composite hollow glass microspheres, and melamine cyanurate to improve the flame retardancy of the outer sheath of high-strength wires and cables for rail transit. The magnesium hydroxide in the flame retardant can decompose under heating conditions, absorb a large amount of heat energy, reduce the temperature of the outer sheath material, and thus slow down the thermal decomposition process. Moreover, after the hollow glass microspheres are compounded by the present invention, during combustion, the copper oxide and tin oxide on the surface of the composite hollow glass microspheres can synergistically catalyze the carbonization process of organic matter, thereby improving the flame retardancy of the outer sheath of high-strength wires and cables for rail transit. The hollow glass microspheres, with their low density and high thermal insulation performance, slow down the inward transfer of heat during the combustion process and reduce the thermal degradation rate of the outer sheath. In addition, the hollow glass microspheres can improve the dispersibility of magnesium hydroxide in the polymer, further improving the flame retardancy. Melamine cyanurate will produce a large amount of difficult-to-burn gas during combustion, which can dilute the combustible gas and oxygen. In summary, the present invention improves the flame retardancy of the outer sheath of high-strength wires and cables for rail transit through the synergistic effect of multiple mechanisms of the three components. DETAILED DESCRIPTION

[0033] 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 embodiments described 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 making any creative efforts are within the scope of protection of the present invention.

[0034] In the following examples and comparative examples, the model of polyethylene is 2102TN00, the model of polyvinyl chloride is SG-5, the model of ethylene-vinyl acetate copolymer is EV360, the model of maleic anhydride grafted polyethylene is FUSABOND E226, the model of maleic anhydride grafted polypropylene is OREVAC 18751, the particle size of magnesium hydroxide is 1 μm, and the model of hollow glass microspheres is 3M-S15.

[0035] Example 1 A high-strength wire and cable for rail transit, comprising, from inside to outside, an aluminum conductor, a silane cross-linked polyethylene insulation layer, an inner sheath, a steel tape armor layer, and an outer sheath. The outer sheath comprises the following components in parts by weight: 80 parts of polyethylene, 30 parts of ethylene-vinyl acetate copolymer, 15 parts of polyvinyl chloride, 12 parts of maleic anhydride grafted polyethylene, 80 parts of a flame retardant, 3 parts of stearic acid, 3 parts of an antioxidant 1010, and 4 parts of trimethylolpropane triacrylate. The flame retardant includes magnesium hydroxide, composite hollow glass microspheres and melamine cyanurate in a mass ratio of 7:7:6; The preparation method of composite hollow glass microspheres comprises the following steps: Hollow glass microspheres were added to water (the mass volume ratio of hollow glass microspheres to water was 1 g:40 mL), copper chloride and tin tetrachloride were added (the mass ratio of hollow glass microspheres, copper chloride, and tin tetrachloride was 20:9:8), and sodium hydroxide was added to a concentration of 0.5 mol / L. The mixture was mixed evenly, and a hydrothermal reaction was carried out at 230°C and 3.6 MPa for 16 h to obtain composite hollow glass microspheres. A method for preparing high-strength wires and cables for rail transit comprises the following steps: S1. A silane cross-linked polyethylene insulation layer, an inner sheath, and a steel tape armor layer are sequentially arranged on the outside of the aluminum conductor; S2. The raw materials of the outer sheath are mixed and extruded outside the steel belt armor layer, and irradiated and cross-linked at a dose of 18 Mard to obtain high-strength wires and cables for rail transit.

[0036] Example 2 A high-strength wire and cable for rail transit, comprising, from inside to outside, an aluminum conductor, a silane cross-linked polyethylene insulation layer, an inner sheath, a steel tape armor layer, and an outer sheath. The outer sheath comprises the following components in parts by weight: 70 parts of polyethylene, 20 parts of ethylene-vinyl acetate copolymer, 10 parts of polyvinyl chloride, 10 parts of maleic anhydride grafted polypropylene, 70 parts of a flame retardant, 2 parts of paraffin wax, 1 part of an antioxidant 1076, and 2 parts of trimethylolpropane trimethacrylate. The flame retardant includes magnesium hydroxide, composite hollow glass microspheres and melamine cyanurate in a mass ratio of 7:7:2; The preparation method of composite hollow glass microspheres comprises the following steps: Hollow glass microspheres were added to water (the mass volume ratio of hollow glass microspheres to water was 1 g:30 mL), copper chloride and tin tetrachloride were added (the mass ratio of hollow glass microspheres, copper chloride, and tin tetrachloride was 20:9:7), and sodium hydroxide was added to a concentration of 0.3 mol / L. The mixture was mixed evenly and subjected to hydrothermal reaction at 220°C and 3.4 MPa for 20 h to obtain composite hollow glass microspheres. A method for preparing high-strength wires and cables for rail transit comprises the following steps: S1. A silane cross-linked polyethylene insulation layer, an inner sheath, and a steel tape armor layer are sequentially arranged on the outside of the aluminum conductor; S2. The raw materials of the outer sheath are mixed and extruded outside the steel belt armor layer, and irradiated and cross-linked at a dose of 15 Mard to obtain high-strength wires and cables for rail transit.

[0037] Example 3 The only difference between this embodiment and embodiment 2 is that the flame retardant in this embodiment includes magnesium hydroxide, composite hollow glass microspheres, and melamine cyanurate in a mass ratio of 7:7:5.

[0038] Example 4 The only difference between this embodiment and embodiment 2 is that the flame retardant in this embodiment includes magnesium hydroxide, composite hollow glass microspheres, and melamine cyanurate in a mass ratio of 7:7:3.

[0039] Example 5 The only difference between this embodiment and embodiment 2 is that the flame retardant in this embodiment includes magnesium hydroxide, composite hollow glass microspheres, and melamine cyanurate in a mass ratio of 7:7:4.

[0040] Example 6 The only difference between this embodiment and embodiment 5 is that the magnesium hydroxide in this embodiment is replaced by composite magnesium hydroxide. The preparation method of composite magnesium hydroxide includes the following steps: Magnesium hydroxide was added to ethanol, and butyl parahydroxybenzoate was added (the mass ratio of magnesium hydroxide to butyl parahydroxybenzoate was 50:1, and the mass volume ratio of magnesium hydroxide to ethanol was 1 g:20 mL). The mixture was stirred at 55° C. and 500 rpm for 4 h, concentrated, and dried to obtain composite magnesium hydroxide.

[0041] Example 7 The only difference between this embodiment and embodiment 5 is that the magnesium hydroxide in this embodiment is replaced by composite magnesium hydroxide. The preparation method of composite magnesium hydroxide includes the following steps: Magnesium hydroxide was added to ethanol, and butyl parahydroxybenzoate was added (the mass ratio of magnesium hydroxide to butyl parahydroxybenzoate was 30:1, and the mass volume ratio of magnesium hydroxide to ethanol was 1 g:15 mL). The mixture was stirred at 400 rpm at 50° C. for 4.5 h, concentrated, and dried to obtain composite magnesium hydroxide.

[0042] Comparative Example 1 The only difference between this comparative example and Example 2 is that the flame retardant in this comparative example includes composite hollow glass microspheres and melamine cyanurate in a mass ratio of 7:2.

[0043] Comparative Example 2 The only difference between this comparative example and Example 2 is that the flame retardant in this comparative example includes magnesium hydroxide and melamine cyanurate in a mass ratio of 7:2.

[0044] Comparative Example 3 The only difference between this comparative example and Example 2 is that the flame retardant in this comparative example includes magnesium hydroxide and composite hollow glass microspheres in a mass ratio of 1:1.

[0045] Comparative Example 4 The only difference between this comparative example and Example 2 is that the flame retardant in this comparative example includes magnesium hydroxide, hollow glass microspheres and melamine cyanurate in a mass ratio of 7:7:2.

[0046] Experimental Example 1 The outer sheaths of the high-strength wires and cables for rail transit prepared in Examples 1-5 and Comparative Examples 1-4 were tested for oxygen index according to the method specified in GB / T 2406.2-2009, "Determination of Combustion Behavior of Plastics by Oxygen Index Method - Part 2: Room Temperature Test." The specimens were Type I specimens and the ignition method was A. The test results are shown in Table 1.

[0047] Table 1 Oxygen index test results

[0048] As can be seen from Table 1, the oxygen index of the outer sheath of the high-strength wire and cable for rail transit prepared in Examples 1 to 5 of the present invention reaches more than 31.2%. Therefore, the present invention uses hollow glass microspheres of magnesium hydroxide, composite copper oxide and tin oxide and melamine cyanurate as flame retardants to improve the flame retardancy of the outer sheath of the high-strength wire and cable for rail transit.

[0049] Experimental Example 2 The outer sheaths of the high-strength wires and cables for rail transit prepared in Examples 5-7 were tested for tensile strength according to the method specified in GB / T 2951.11-2008, "General Test Methods for Insulation and Sheathing Materials of Electrical and Optical Cables - Part 11: General Test Methods - Thickness and Dimensional Measurements - Mechanical Properties Tests." The test specimens were dumbbells with a thickness of 1 mm and a tensile rate of 250 mm / min. The test results are shown in Table 2.

[0050] Table 2 Tensile strength test results

[0051] As can be seen from Table 2, the tensile strength of the outer sheath of the high-strength wire and cable for rail transit prepared in Examples 6 to 7 of the present invention reaches more than 15.8 MPa. Therefore, the present invention uses butyl parahydroxybenzoate composite magnesium hydroxide to improve the tensile strength of the outer sheath of the high-strength wire and cable for rail transit.

[0052] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-strength wire and cable for rail transit, characterized in that: From inside to outside, the conductor, insulation layer, inner sheath, armor layer, and outer sheath are arranged in order. The raw materials of the outer sheath include the following components in parts by weight: 70-80 parts of polyethylene, 20-30 parts of ethylene-vinyl acetate copolymer, 10-15 parts of polyvinyl chloride, 10-12 parts of a compatibilizer, 70-80 parts of a flame retardant, 2-3 parts of a lubricant, 1-3 parts of an antioxidant, and 2-4 parts of a cross-linking agent. The flame retardant includes magnesium hydroxide, composite hollow glass microspheres and melamine cyanurate; The preparation method of the composite hollow glass microspheres comprises the following steps: The hollow glass microspheres are added into water, and copper chloride, tin tetrachloride and sodium hydroxide are added thereto, mixed evenly, subjected to hydrothermal reaction, concentrated and calcined to obtain the composite hollow glass microspheres.

2. A high-strength wire and cable for rail transit according to claim 1, characterized in that: The mass ratio of the hollow glass microspheres, copper chloride and tin tetrachloride is 20:9:7-8; The concentration of the sodium hydroxide in water is 0.3-0.5 mol / L; The hydrothermal reaction temperature is 220-230° C., the pressure is 3.4-3.6 MPa, and the time is 16-20 h.

3. The high-strength wire and cable for rail transit according to claim 1, characterized in that: The mass ratio of the magnesium hydroxide, the composite hollow glass microspheres and the melamine cyanurate is 7:7:3-4.

4. A high-strength wire and cable for rail transit according to any one of claims 1 to 3, characterized in that: The magnesium hydroxide is composite magnesium hydroxide; The raw materials of the composite magnesium hydroxide include magnesium hydroxide and butyl p-hydroxybenzoate.

5. The high-strength wire and cable for rail transit according to claim 4, characterized in that: The preparation method of the composite magnesium hydroxide comprises the following steps: Magnesium hydroxide is added to ethanol, butyl p-hydroxybenzoate is added, the mixture is stirred, concentrated, and dried to obtain the composite magnesium hydroxide.

6. The high-strength wire and cable for rail transit according to claim 5, characterized in that: In the raw materials of the composite magnesium hydroxide, the mass ratio of magnesium hydroxide to butyl parahydroxybenzoate is 30-50:

1.

7. The high-strength wire and cable for rail transit according to claim 5, characterized in that: The stirring speed is 400-500 rpm, the temperature is 50-55° C., and the time is 4-4.5 hours.

8. The high-strength wire and cable for rail transit according to claim 1, characterized in that: The material of the conductor is aluminum; The material of the insulating layer is silane cross-linked polyethylene; The material of the armor layer is steel strip; The compatibilizer includes one of maleic anhydride grafted polyethylene and maleic anhydride grafted polypropylene; The lubricant includes one of stearic acid and paraffin; The antioxidant includes one of antioxidant 1010 and antioxidant 1076; The cross-linking agent includes one of trimethylolpropane triacrylate and trimethylolpropane trimethacrylate.

9. A method for preparing a high-strength wire and cable for rail transit, for preparing a high-strength wire and cable for rail transit according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. An insulating layer, an inner protective layer and an armor layer are sequentially arranged outside the conductor; S2. The raw materials of the outer sheath are mixed and extruded outside the armor layer, and irradiated and cross-linked to obtain the high-strength wire and cable for rail transit.

10. Application of a high-strength wire and cable for rail transit prepared by the method for preparing a high-strength wire and cable for rail transit according to any one of claims 1 to 8 or claim 9 in the field of rail transit.

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