A B1-level flame-retardant coaxial feeder for low-loss and ultra-flexible in-building distribution

Abstract

The present invention discloses a B1 - level flame - retardant coaxial feeder for low - loss and ultra - flexible in - building distribution, which relates to the technical field of cables. The cable of the present invention includes a composite - coated fine copper wire bundle, a polytetrafluoroethylene insulation layer, a coated copper wire shielding layer, an elastic polyester fiber layer, and a modified rubber sheath layer. Through this structural design, the signal attenuation during transmission is effectively reduced. At the same time, the plastic toughness of each layer is close, enabling synchronous deformation during multiple bending deformations, further improving the cable performance. The coaxial feeder involved in the present invention has relatively small attenuation values at both high and low frequencies, with a tensile strength between 16.6 and 18.4 MPa, and can be bent multiple times, showing more excellent mechanical properties and anti - bending effects in practical applications. In addition, the oxygen index of this feeder is as high as 36% or above, does not release hydrogen halide gas, and can meet the B1 - level flame - retardant standard.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and particularly to a B1 - class flame - retardant coaxial feeder for low - loss and ultra - flexible in - building distribution systems. Background Art

[0002] During the implementation of in - building distribution systems (DAS), as a key component for signal transmission, the performance of radio - frequency coaxial feeders has a decisive impact on the stability, transmission efficiency, and construction flexibility of communication systems. With the increasing complexity of modern building structures, especially in specific environments such as high - rise buildings, commercial complexes, and underground transportation hubs, the laying of feeders often needs to pass through restricted spaces such as enclosed ceilings, narrow corner aisles, and elevator shafts.

[0003] However, traditional radio - frequency cables face several technical challenges in practical applications, which limit their performance in complex indoor environments. The conductors of traditional coaxial feeders mostly adopt rigid corrugated copper or aluminum tube structures. When repeatedly bent in narrow spaces, the conductors are prone to deformation and the insulation layer is damaged. Secondly, the insulation layer materials of traditional cables (such as foamed polyethylene) have relatively high dielectric constants and loss tangent values, which cause significant skin effects in the high - frequency band (such as 2.6 GHz, 3.5 GHz), thereby exacerbating signal attenuation. This high transmission loss is difficult to meet the strict requirements of 5G indoor coverage for low insertion loss (less than 0.1 dB / m @ 3.5 GHz).

[0004] Ordinary flame - retardant cables can meet the B2 - class flame - retardant standard, but they will produce a large amount of thick smoke and toxic gases (such as HCl, HBr) when burning, which does not meet the strict requirements of GB31247 - 2014 "Classification of the Burning Performance of Cables and Optical Fibre Cables" for B1 - class flame - retardant (peak heat release rate ≤ 30 kW, smoke density grade ≤ 75, burning droplets / particles ≤ 0). Therefore, they pose a fire safety hazard.

[0005] Traditional cables also have deficiencies in environmental adaptability. For example, in scenarios such as elevator shafts, where vibrations and temperature - humidity changes are frequent, the sheath materials of traditional cables have poor fatigue resistance, and problems such as sheath cracking and shielding layer oxidation are likely to occur after long - term use, which will seriously affect the service life of the system.

[0006] In response to the above problems, existing technologies have tried to make improvements by optimizing the foaming process, adopting flexible braided outer conductors, or adding flame retardants. However, there are still some contradictions in these improvement measures, such as the mutual restriction between bending performance and transmission loss, and the difficulty in balancing flame - retardant efficiency and environmental protection requirements. Therefore, there is an urgent need to develop a new type of coaxial feeder that should have an ultra - flexible structure, low - loss characteristics, and high - grade flame - retardant performance to adapt to the high - quality communication requirements in complex indoor scenarios. Summary of the Invention

[0007] The object of the present invention is to provide a B1 - class flame - retardant coaxial feeder for low - loss and ultra - flexible in - building distribution, so as to solve the problems existing in the prior art.

[0008] To solve the above - mentioned technical problems, on the one hand, the present invention provides a B1 - class flame - retardant coaxial feeder for low - loss and ultra - flexible in - building distribution. The B1 - class flame - retardant coaxial feeder for low - loss and ultra - flexible in - building distribution includes a composite - coated fine copper wire bundle, a polytetrafluoroethylene insulation layer, a coated copper wire shielding layer, an elastic polyester fiber layer, and a modified rubber sheath layer;

[0009] The coated fine copper wire bundle is obtained by stranding and bundling coated copper wires; the coated copper wire shielding layer is obtained by weaving coated copper wires into a net; wherein, the preparation method of the coated copper wire is: placing a copper wire with a diameter of 0.15 mm in an unbalanced magnetron sputtering device, magnetron sputtering and depositing it with a silver - zirconium binary material as the target in a nitrogen - containing atmosphere, then placing it in an ion nitriding device, evacuating to below 15 Pa and then introducing ammonia gas, keeping the air pressure at 200 Pa, raising the furnace temperature to 500 - 520 °C, then performing plasma nitriding surface treatment, with a holding time of 15 min, and after the treatment is completed, cooling it to room temperature with the furnace;

[0010] The modified rubber sheath layer is obtained by mixing, vulcanizing, and extruding 75 - 115 parts of modified rubber, 18 - 26 parts of modified vermiculite, 6 - 10 parts of stearic acid, 4 - 10 parts of carbon black, and 2.6 - 3.8 parts of sulfur;

[0011] The modified rubber is obtained by graft - modifying ethylene - propylene - diene monomer rubber with a hydroxyl - containing conjugated diene monomer.

[0012] In the present invention, a braided copper wire shielding layer and an elastic polyester fiber layer are provided, which reduce the probability of shielding layer movement and internal wear, thereby extending the service life of the cable. In addition, when the modified rubber is used as the sheath raw material and is hot - extruded onto the surface of the fiber layer, the flow pressure of the rubber tightly wraps it around the fiber, filling the tiny depressions and pores on the fiber surface to form a mechanical interlock. When the cable is subjected to external forces, the mechanically interlocked part can withstand a part of the external forces, enhancing the bonding stability and thus enhancing the overall mechanical properties of the cable.

[0013] Further, the preparation method of the coated copper wire is: placing a copper wire with a diameter of 0.15 mm in an unbalanced magnetron sputtering device, magnetron sputtering and depositing it with a silver - zirconium binary material as the target in a nitrogen - containing atmosphere, then placing it in an ion nitriding device, evacuating to below 15 Pa and then introducing ammonia gas, keeping the air pressure at 200 Pa, raising the furnace temperature to 500 °C, then performing plasma nitriding surface treatment, with a holding time of 15 min, and after the treatment is completed, cooling it to room temperature with the furnace to obtain the coated copper wire; the composition and weight percentage of the silver - zirconium binary material are: Zr is 22%, and the balance is Ag and unavoidable impurities. The vacuum degree of the nitrogen - containing atmosphere is mbar, the volume ratio of nitrogen to argon in the nitrogen-containing atmosphere is 1:1.2, the deposition power of magnetron sputtering is 50 kW, and the surface film thickness is 10 nm; in the present invention, silver and zirconium ions are first evenly coated on the surface of the copper wire through an unbalanced magnetron sputtering device, and the zirconium-silver ions and the copper wire form an equal-gradient structure, evenly distributing the external stress, reducing the phenomenon of internal vibration and friction damaging the copper wire, significantly improving the overall strength of the cable, and then through plasma nitriding treatment. When the copper wires rub against each other, the existence of the nitride layer can reduce the direct contact between metals, thereby reducing the wear between conductors and further achieving multiple bends.

[0014] Further, the hydroxyl-containing conjugated diene monomer is one of 2,4-heptadien-1-ol, trans-2,4-hexadien-1-ol, and 2,4-octadien-1-ol.

[0015] Further, the preparation method of the modified vermiculite: Mix 50 parts by mass of hydroxylated vermiculite powder, 50 - 100 parts by mass of acrylic acid, and 16 - 20 parts by mass of water, stir evenly, then drop 5 - 15 parts by mass of silver nitrate solution at 30 °C while stirring, let it stand for 2 h after dropping, then add 0.4 - 3 parts by mass of initiator, and stir at 60 - 90 °C for 1 - 2 h. After stirring, filter by suction, wash with water, dry, and carbonize.

[0016] Further, the initiator is a peroxide or a persulfide.

[0017] Further, the persulfide is potassium persulfate, and the peroxide is cumene hydroperoxide.

[0018] Further, the particle size of the vermiculite powder is 200 mesh.

[0019] Further, the stirring is carried out at a speed of 150 - 300 r / min.

[0020] Further, the specific process of carbonization is: Feed it into a carbonization furnace, under normal pressure, introduce nitrogen, heat it to 160 - 220 °C at a rate of 5 - 10 °C / min. After the temperature is stable, keep it warm for 30 - 50 min, then introduce air, heat it to 250 - 320 °C at a rate of 3 - 6 °C / min. After the temperature is stable, keep it warm for 60 - 120 min, then introduce nitrogen again, heat it to 600 - 650 °C at a rate of 3 - 6 °C / min. After the temperature is stable, keep it warm for 20 - 40 min.

[0021] Further, the concentration of the silver nitrate solution is 1 mol / L.

[0022] On the other hand, the low-loss ultra-flexible in-building distribution B1-level flame-retardant coaxial feeder is applied to the in-building distribution DAS system.

[0023] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0024] 1. The modified rubber first uses a conjugated diene monomer containing a hydroxyl group to modify ethylene-propylene rubber, making it hydroxyl-functionalized. The presence of polar groups improves the compatibility and adhesion with other materials, and at the same time can promote the vulcanization process, enhance the crosslinked network structure, reduce the negative effects of additives on it, and improve the mechanical strength of the cable. By introducing a conjugated diene as the third monomer, the present invention promotes the formation of a denser crosslinked network, thereby enhancing the tensile strength, elasticity and wear resistance, and can also improve the compatibility with fillers or other polymers; then it is filled and modified with modified vermiculite, significantly enhancing the mechanical strength and flame retardancy of the cable. The existence of the coating layer on the surface of vermiculite not only improves the compatibility between rubber and modified vermiculite, but also can improve the interaction between interfaces, thereby further improving the mechanical, antioxidant and flame retardant properties of the coaxial feeder. Through this dual modification treatment, the overall performance of the cable has been significantly improved, making it show more excellent mechanical properties in practical applications.

[0025] 2. The present invention uses a copper-based inner conductor plated with silver and zirconium on the outer surface. The zirconium-silver ions form an equal-gradient structure with the copper wire, evenly distributing the external stress, reducing the phenomenon of internal vibration friction damaging the copper wire, and significantly improving the overall strength of the cable. Subsequently, after plasma nitriding treatment, when the copper wires rub against each other, the existence of the nitride layer can reduce the direct contact between metals, thereby reducing the wear between conductors and realizing multiple bends. The present invention also uses polytetrafluoroethylene as the insulating layer, reducing the cable loss, thereby reducing the signal attenuation during transmission.

[0026] 3. In the present invention, the plastic toughness of the copper wire surface coating, polytetrafluoroethylene insulating layer and sheath layer is close, so that each layer inside can deform synchronously during the process of multiple bending deformations, and it is not easy to have relative mechanical displacement. At the same time, the present invention also lays a flexible elastic polyester fiber layer, and thus can realize multiple bends.

[0027] 4. The coaxial feeder of the present invention can be used in the indoor distributed antenna system (DAS), solving the problem that the laying of radio frequency cables is affected by the site location, especially in narrow areas such as the corner aisles of closed ceilings, and the up and down, front and back of elevator shafts. Detailed implementation manners

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the protection scope of the present invention.

[0029] Example 1: (1) At 50 °C, ethylene propylene diene monomer (EPDM) was added to a flask containing xylene and stirred until completely dissolved. Under a nitrogen atmosphere at 65 °C, 2,4-heptadien-1-ol and azobisisobutyronitrile were successively added thereto and stirred for reaction for 3 h. The mass ratio of EPDM, 2,4-heptadien-1-ol, and azobisisobutyronitrile was 1:0.05:0.005. Acetone precipitation and N,N-dimethylformamide extraction were carried out, followed by vacuum drying to obtain modified EPDM;

[0030] (2) A copper wire with a diameter of 0.15 mm was placed in an unbalanced magnetron sputtering device and deposited by magnetron sputtering in a nitrogen-containing atmosphere using a silver-zirconium binary material as a target. Then it was placed in an ion nitriding device. After evacuating to below 15 Pa, ammonia gas was introduced, and the gas pressure was maintained at 200 Pa. The furnace temperature was raised to 500 °C, and then plasma nitriding surface treatment was carried out. The holding time was 15 min. After the treatment was completed, it was cooled to room temperature with the furnace to obtain a coated copper wire; the composition and weight percentage of the silver-zirconium binary material were as follows: Zr was 22%, and the balance was Ag and unavoidable impurities. The vacuum degree of the nitrogen-containing atmosphere was mbar, the volume ratio of nitrogen to argon in the nitrogen-containing atmosphere was 1:1.2, the deposition power of magnetron sputtering was 50 kW, and the surface film thickness was 10 nm;

[0031] (3) 10 g of vermiculite powder with a particle size of 200 mesh and 200 mL of hydrogen peroxide aqueous solution (30 wt%) were ultrasonically dispersed for 10 min. Under mechanical stirring, the temperature was raised to 105 °C and reacted for 6 h. After cooling, it was centrifuged at 5000 rpm for 5 min, washed 3 times with deionized water, and vacuum dried at 80 °C for 5 h to obtain hydroxylated vermiculite powder;

[0032] (4) 50 parts by mass of hydroxylated vermiculite powder, 50 parts by mass of acrylic acid, and 16 parts by mass of water were mixed and stirred evenly. At 30 °C, 5 parts by mass of 1 mol / L silver nitrate solution was added dropwise while stirring at a speed of 150 r / min. After standing for 2 h, 0.4 parts by mass of potassium persulfate was added, and it was stirred at 60 °C and 150 r / min for 1 h. After the stirring was completed, it was filtered, washed with water, and dried, and then sent into a carbonization furnace. Under normal pressure conditions, nitrogen was introduced, and the temperature was raised to 160 °C at a rate of 5 °C / min. After the temperature was stabilized, it was held for 30 min. Then air was introduced, and the temperature was raised to 250 °C at a rate of 3 °C / min. After the temperature was stabilized, it was held for 60 min. Then nitrogen was introduced, and the temperature was raised to 600 °C at a rate of 3 °C / min. After the temperature was stabilized, it was held for 20 min to obtain modified vermiculite;

[0033] (5) Polytetrafluoroethylene was coated on the periphery of a bundle composed of 100 composite coated copper wires to form an insulating layer with a thickness of 0.8 mm to obtain an insulating core;

[0034] (6) Place the insulated core in a braiding machine. After braiding a copper-coated wire shielding layer at a braiding angle of 30°, braid an elastic polyester fiber layer with a thickness of 0.2 mm at an elastic polyester fiber diameter of 0.05 mm and a braiding temperature of 80°C. Among them, the elastic polyester fiber item number is 1008, provided by Yangzhou Tianlun Fiber Co., Ltd. Subsequently, mix 75 parts of modified rubber, 18 parts of modified vermiculite, 6 parts of stearic acid, 4 parts of carbon black, and 2.6 parts of sulfur, and vulcanize at 150°C and 11 MPa for 17 min, and then vulcanize at 215°C for 1 h. Subsequently, extrude and coat it outside the elastic polyester fiber layer to form a sheath with a thickness of 2 mm, and naturally cool it to room temperature to obtain a B1-level flame-retardant coaxial feeder for low-loss ultra-flexible indoor distribution.

[0035] Example 2: (1) At 50°C, add ethylene propylene diene monomer rubber to a flask containing xylene and stir until completely dissolved. Under a nitrogen atmosphere at 70°C, sequentially add trans-2,4-hexadien-1-ol and azobisisobutyronitrile to it and stir and react for 3 h. The mass ratio of ethylene propylene diene monomer rubber, trans-2,4-hexadien-1-ol, and azobisisobutyronitrile is 1:0.06:0.005. Precipitate with acetone, extract with N,N-dimethylformamide, and vacuum dry to obtain modified ethylene propylene diene monomer rubber;

[0036] (2) Place a copper wire with a diameter of 0.15 mm in an unbalanced magnetron sputtering device, and deposit it by magnetron sputtering in a nitrogen-containing atmosphere using a silver-zirconium binary material as the target. Then place it in an ion nitriding device, evacuate to below 15 Pa and then introduce ammonia gas, keep the gas pressure at 200 Pa, raise the furnace temperature to 520°C, and then perform plasma nitriding surface treatment. The holding time is 15 min. After the treatment is completed, cool it to room temperature with the furnace to obtain a copper-coated wire; the composition and weight percentage of the silver-zirconium binary material are: Zr is 24%, and the balance is Ag and unavoidable impurities. The vacuum degree of the nitrogen-containing atmosphere is mbar, the volume ratio of nitrogen and argon in the nitrogen-containing atmosphere is 1:1.3, the deposition power of magnetron sputtering is 50 kW, and the surface film layer thickness is 10 nm;

[0037] (3) Ultrasonically disperse 10 g of vermiculite powder with a particle size of 200 mesh and 200 mL of hydrogen peroxide aqueous solution (30 wt%) for 10 min. Under mechanical stirring, raise the temperature to 105°C and react for 6 h. After cooling, centrifuge at 5000 rpm for 5 min, wash 3 times with deionized water, and vacuum dry at 80°C for 5 h to obtain hydroxylated vermiculite powder;

[0038] (4) Mix 50 parts by mass of hydroxylated vermiculite powder, 75 parts by mass of acrylic acid, and 18 parts by mass of water. After stirring evenly, add 10 parts by mass of 1 mol / L silver nitrate solution dropwise at 30°C, and stir at a speed of 200 r / min while adding. Then let it stand for 2 h, and then add 0.4 parts by mass of potassium persulfate. Stir at 60°C and 200 r / min for 1 h. After the stirring is completed, filter by suction, wash with water, and dry, and then send it into a carbonization furnace. Under normal pressure conditions, introduce nitrogen, heat up to 200°C at a rate of 7°C / min. After the temperature is stable, keep it warm for 30 min, then introduce air, heat up to 300°C at a rate of 4°C / min. After the temperature is stable, keep it warm for 100 min, then introduce nitrogen, heat up to 620°C at a rate of 4°C / min. After the temperature is stable, keep it warm for 30 min to obtain modified vermiculite;

[0039] (5) Coating the outer periphery of the bundle made of 100 composite coated copper wires with polytetrafluoroethylene to form an insulating layer with a thickness of 0.8 mm, and obtaining an insulating core;

[0040] (6) Place the insulating core in a braiding machine, braid a coated copper wire shielding layer at a braiding angle of 34°, and then braid an elastic polyester fiber layer with a thickness of 0.3 mm at an elastic polyester fiber diameter of 0.10 mm and a braiding temperature of 90°C. Among them, the elastic polyester fiber product number is 1008, provided by Yangzhou Tianlun Fiber Co., Ltd. Subsequently, mix 95 parts of modified rubber, 22 parts of modified vermiculite, 8 parts of stearic acid, 7 parts of carbon black, and 3.2 parts of sulfur, and vulcanize at 150°C and 11 MPa for 17 min, and vulcanize at 215°C for 1 h. Then extrude and coat it outside the elastic polyester fiber layer to form a sheath with a thickness of 3 mm, and naturally cool to room temperature to obtain a low-loss ultra-flexible indoor distribution B1-class flame-retardant coaxial feeder.

[0041] Example 3: (1) At 50°C, add ethylene propylene diene monomer rubber to a flask containing xylene and stir until completely dissolved. Under a nitrogen atmosphere at 75°C, sequentially add 2,4-octadien-1-ol and azobisisobutyronitrile and stir and react for 3 h. The mass ratio of ethylene propylene diene monomer rubber, 2,4-octadien-1-ol, and azobisisobutyronitrile is 1:0.07:0.005. Precipitate with acetone, extract with N,N-dimethylformamide, and dry in vacuum to obtain modified ethylene propylene diene monomer rubber;

[0042] (2)A copper wire with a diameter of 0.15 mm is placed in an unbalanced magnetron sputtering device and deposited by magnetron sputtering in a nitrogen-containing atmosphere using a silver-zirconium binary material as the target. Then it is placed in an ion nitriding device. After evacuating to below 15 Pa, ammonia gas is introduced, the air pressure is maintained at 200 Pa, the furnace temperature is raised to 520 °C, and then plasma nitriding surface treatment is carried out. The holding time is 15 min. After the treatment is completed, it is cooled to room temperature with the furnace to obtain a coated copper wire; the composition and weight percentage of the silver-zirconium binary material are: Zr is 26%, and the balance is Ag and unavoidable impurities. The vacuum degree of the nitrogen-containing atmosphere is mbar, the volume ratio of nitrogen to argon in the nitrogen-containing atmosphere is 1:1.5, the deposition power of magnetron sputtering is 50 kW, and the surface film layer thickness is 10 nm;

[0043] (3)10 g of vermiculite powder with a particle size of 200 mesh and 200 mL of hydrogen peroxide aqueous solution (30 wt%) are ultrasonically dispersed for 10 min. Under mechanical stirring, the temperature is raised to 105 °C and reacted for 6 h. After cooling, it is centrifuged at 5000 rpm for 5 min, washed 3 times with deionized water, and vacuum dried at 80 °C for 5 h to obtain hydroxylated vermiculite powder;

[0044] (4)50 parts by mass of hydroxylated vermiculite powder, 100 parts by mass of acrylic acid, and 20 parts by mass of water are mixed and stirred evenly. At 30 °C, 15 parts by mass of 1 mol / L silver nitrate solution is added dropwise, and stirring is carried out at a speed of 200 r / min while adding. Then it is left standing for 2 h, and then 0.4 part by mass of potassium persulfate is added. Stirring is carried out at 60 °C and 200 r / min for 1 h. After the stirring is completed, it is filtered, washed with water, and dried, and then sent into a carbonization furnace. Under normal pressure conditions, nitrogen is introduced, and the temperature is raised to 220 °C at a rate of 10 °C / min. After the temperature is stabilized, it is held for 50 min. Then air is introduced, and the temperature is raised to 320 °C at a rate of 6 °C / min. After the temperature is stabilized, it is held for 120 min. Then nitrogen is introduced, and the temperature is raised to 650 °C at a rate of 4 °C / min. After the temperature is stabilized, it is held for 430 min to obtain modified vermiculite;

[0045] (5)Polytetrafluoroethylene is coated on the periphery of a bundle composed of 100 composite coated copper wires to form an insulating layer with a thickness of 0.8 mm, and an insulating core is obtained;

[0046] (6) Place the insulated core in a braiding machine. After braiding the copper-plated wire shielding layer at a braiding angle of 38°, braid an elastic polyester fiber layer with a thickness of 0.4 mm using elastic polyester fibers with a diameter of 0.15 mm at a braiding temperature of 100°C. Among them, the product number of the elastic polyester fiber is 1008, provided by Yangzhou Tianlun Fiber Co., Ltd. Subsequently, 115 parts of modified rubber, 26 parts of modified vermiculite, 10 parts of stearic acid, 10 parts of carbon black, and 3.8 parts of sulfur are mixed and kneaded. At 150°C and 11 MPa, vulcanize for 17 minutes, and at 215°C, vulcanize for 1 hour. Then, extrude and coat it outside the elastic polyester fiber layer to form a sheath with a thickness of 4 mm, and naturally cool it to room temperature to obtain a B1-class flame-retardant coaxial feeder for low-loss ultra-flexible indoor distribution.

[0047] Perform performance tests on the coaxial feeders of Examples 1 to 3:

[0048] (1) Attenuation test: Under the test conditions of 1 standard atmosphere, horizontal plane and 25°C, install the components of the coaxial feeder of the present invention and then test the attenuation of a 10 m coaxial feeder, and convert the attenuation value per meter. The typical attenuation indexes are shown in Table 1.

[0049]

[0050] As can be seen from Table 1, the attenuation values of the coaxial feeder prepared by the present invention are both small at high frequencies and low frequencies, so that the transmission distance and transmission effect of the cable are good, and the cable has the characteristics of low transmission loss and anti-signal interference.

[0051] (2) Flame retardancy test:

[0052]

[0053] As can be seen from Table 2, the coaxial feeder prepared by the present invention has good flame retardancy and can reach the B1 flame retardant grade.

[0054] Comparative Example 1 (only using pure copper wire): (1) At 50°C, add ethylene propylene diene monomer rubber to a flask containing xylene and stir until completely dissolved. Under a nitrogen atmosphere at 70°C, successively add trans-2,4-hexadien-1-ol and azobisisobutyronitrile thereto and stir and react for 3 hours. The mass ratio of ethylene propylene diene monomer rubber, trans-2,4-hexadien-1-ol, and azobisisobutyronitrile is 1:0.06:0.005. Precipitate with acetone, extract with N,N-dimethylformamide, and dry in vacuum to obtain modified ethylene propylene diene monomer rubber;

[0055] (2) 10 g of vermiculite powder with a particle size of 200 mesh and 200 mL of hydrogen peroxide aqueous solution (30 wt%) were ultrasonically dispersed for 10 min. Under mechanical stirring, the temperature was raised to 105 °C and reacted for 6 h. After cooling, it was centrifuged at 5000 rpm for 5 min, washed 3 times with deionized water, and vacuum dried at 80 °C for 5 h to obtain hydroxylated vermiculite powder;

[0056] (3) 50 parts by mass of hydroxylated vermiculite powder, 75 parts by mass of acrylic acid, and 18 parts by mass of water were mixed and stirred evenly. At 30 °C, 10 parts by mass of 1 mol / L silver nitrate solution was added dropwise, and stirred at a speed of 200 r / min while adding. After that, it was left standing for 2 h, then 0.4 parts by mass of potassium persulfate was added, and stirred at 60 °C and 200 r / min for 1 h. After the stirring was completed, it was filtered, washed with water, and dried, and then sent into a carbonization furnace. Under normal pressure conditions, nitrogen was introduced, and the temperature was raised to 200 °C at a rate of 7 °C / min. After the temperature was stabilized, it was kept warm for 30 min, then air was introduced, and the temperature was raised to 300 °C at a rate of 4 °C / min. After the temperature was stabilized, it was kept warm for 100 min, then nitrogen was introduced, and the temperature was raised to 620 °C at a rate of 4 °C / min. After the temperature was stabilized, it was kept warm for 30 min to obtain modified vermiculite;

[0057] (4) Polytetrafluoroethylene was coated on the periphery of a bundle composed of 100 copper wires with a diameter of 0.15 mm to form an insulating layer with a thickness of 0.8 mm, and an insulated electric core was obtained;

[0058] (5) The insulated electric core was placed in a knitting machine, and a copper wire shielding layer with a diameter of 0.15 mm was knitted at a knitting angle of 34°. Then, an elastic polyester fiber layer with a thickness of 0.3 mm was knitted with an elastic polyester fiber with a diameter of 0.10 mm at a knitting temperature of 90 °C. Among them, the elastic polyester fiber product number is 1008, provided by Yangzhou Tianlun Fiber Co., Ltd. Subsequently, 95 parts of modified rubber, 22 parts of modified vermiculite, 8 parts of stearic acid, 7 parts of carbon black, and 3.2 parts of sulfur were mixed and kneaded. At 150 °C and 11 MPa, it was vulcanized for 17 min, and at 215 °C, it was vulcanized for 1 h. Then, it was extruded and coated outside the elastic polyester fiber layer to form a sheath with a thickness of 3 mm, and naturally cooled to room temperature to obtain a low-loss ultra-flexible indoor distribution B1-class flame-retardant coaxial feeder.

[0059] Comparative Example 2 (only using a pure silver target during sputtering): (1) At 50 °C, ethylene propylene diene monomer was added to a flask containing xylene and stirred until completely dissolved. Under a nitrogen atmosphere at 70 °C, trans-2,4-hexadien-1-ol and azobisisobutyronitrile were successively added thereto and stirred for 3 h. The mass ratio of ethylene propylene diene monomer, trans-2,4-hexadien-1-ol, and azobisisobutyronitrile is 1:0.06:0.005. It was precipitated with acetone, extracted with N,N-dimethylformamide, and vacuum dried to obtain modified ethylene propylene diene monomer;

[0060] (2) Place a copper wire with a diameter of 0.15 mm in an unbalanced magnetron sputtering device, deposit it by magnetron sputtering with a silver target in a nitrogen-containing atmosphere, then place it in an ion nitriding device. After evacuating to below 15 Pa, introduce ammonia gas, keep the gas pressure at 200 Pa, raise the furnace temperature to 520 °C, and then carry out plasma nitriding surface treatment. The holding time is 15 min. After the treatment is completed, cool it in the furnace to room temperature to obtain coated copper wire; the vacuum degree of the nitrogen-containing atmosphere is mbar, the volume ratio of nitrogen to argon in the nitrogen-containing atmosphere is 1:1.3, the deposition power of magnetron sputtering is 50 kW, and the surface film layer thickness is 10 nm;

[0061] (3) Ultrasonically disperse 10 g of vermiculite powder with a particle size of 200 mesh and 200 mL of hydrogen peroxide aqueous solution (30 wt%) for 10 min. Under mechanical stirring, raise the temperature to 105 °C and react for 6 h. After cooling, centrifuge at 5000 rpm for 5 min, wash 3 times with deionized water, and vacuum dry at 80 °C for 5 h to obtain hydroxylated vermiculite powder;

[0062] (4) Mix 50 parts by mass of hydroxylated vermiculite powder, 75 parts by mass of acrylic acid, and 18 parts by mass of water, stir evenly, and dropwise add 10 parts by mass of 1 mol / L silver nitrate solution at 30 °C while stirring at a speed of 200 r / min. After dropping, let it stand for 2 h, then add 0.4 parts by mass of potassium persulfate, stir at 60 °C and 200 r / min for 1 h. After the stirring is completed, filter, wash with water, and dry, then send it into a carbonization furnace. Under normal pressure, introduce nitrogen gas, heat up to 200 °C at a rate of 7 °C / min. After the temperature is stable, hold for 30 min, then introduce air, heat up to 300 °C at a rate of 4 °C / min. After the temperature is stable, hold for 100 min, then introduce nitrogen gas, heat up to 620 °C at a rate of 4 °C / min. After the temperature is stable, hold for 30 min to obtain modified vermiculite;

[0063] (5) Coating the outside of the bundle made of 100 composite coated copper wires with polytetrafluoroethylene to form an insulating layer with a thickness of 0.8 mm to obtain an insulating core;

[0064] (6) Place the insulating core in a braiding machine, braid a coated copper wire shielding layer at a braiding angle of 34°, and then braid a 0.3 mm thick elastic polyester fiber layer with an elastic polyester fiber diameter of 0.10 mm and a braiding temperature of 90 °C. Among them, the elastic polyester fiber product number is 1008, provided by Yangzhou Tianlun Fiber Co., Ltd. Subsequently, mix 95 parts of modified rubber, 22 parts of modified vermiculite, 8 parts of stearic acid, 7 parts of carbon black, and 3.2 parts of sulfur, vulcanize at 150 °C and 11 MPa for 17 min, and vulcanize at 215 °C for 1 h. Then extrude and coat it outside the elastic polyester fiber layer to form a sheath with a thickness of 3 mm, and naturally cool to room temperature to obtain a low-loss ultra-flexible indoor distribution B1-level flame-retardant coaxial feeder.

[0065] Comparative Example 3 (only using a pure zirconium target during sputtering): (1) At 50°C, add ethylene propylene diene monomer rubber to a flask containing xylene and stir until completely dissolved. Under a nitrogen atmosphere at 70°C, successively add trans-2,4-hexadien-1-ol and azobisisobutyronitrile thereto and stir for 3 h. The mass ratio of ethylene propylene diene monomer rubber, trans-2,4-hexadien-1-ol, and azobisisobutyronitrile is 1:0.06:0.005. Precipitate with acetone, extract with N,N-dimethylformamide, and dry in vacuo to obtain modified ethylene propylene diene monomer rubber;

[0066] (2) Place a copper wire with a diameter of 0.15 mm in an unbalanced magnetron sputtering device and deposit it by magnetron sputtering with a zirconium target in a nitrogen-containing atmosphere. Then place it in an ion nitriding device. After evacuating to below 15 Pa, introduce ammonia gas, maintain the gas pressure at 200 Pa, raise the furnace temperature to 520°C, and then perform plasma nitriding surface treatment. The holding time is 15 min. After the treatment is completed, cool it to room temperature with the furnace to obtain a coated copper wire; the vacuum degree of the nitrogen-containing atmosphere is mbar, the volume ratio of nitrogen to argon in the nitrogen-containing atmosphere is 1:1.3, the deposition power of magnetron sputtering is 50 kW, and the surface film thickness is 10 nm;

[0067] (3) Ultrasonically disperse 10 g of vermiculite powder with a particle size of 200 mesh and 200 mL of hydrogen peroxide aqueous solution (30 wt%) for 10 min. Under mechanical stirring, raise the temperature to 105°C and react for 6 h. After cooling, centrifuge at 5000 rpm for 5 min, wash 3 times with deionized water, and dry in vacuo at 80°C for 5 h to obtain hydroxylated vermiculite powder;

[0068] (4) Mix 50 parts by mass of hydroxylated vermiculite powder, 75 parts by mass of acrylic acid, and 18 parts by mass of water, stir evenly, and dropwise add 10 parts by mass of 1 mol / L silver nitrate solution at 30°C while stirring at a speed of 200 r / min. After dropping, let it stand for 2 h, then add 0.4 parts by mass of potassium persulfate, stir at 60°C and 200 r / min for 1 h. After the stirring is completed, filter by suction, wash with water, and dry. Send it into a carbonization furnace. Under normal pressure conditions, introduce nitrogen gas, heat up to 200°C at a rate of 7°C / min. After the temperature is stabilized, hold for 30 min, then introduce air, heat up to 300°C at a rate of 4°C / min. After the temperature is stabilized, hold for 100 min, then introduce nitrogen gas, heat up to 620°C at a rate of 4°C / min. After the temperature is stabilized, hold for 30 min to obtain modified vermiculite;

[0069] (5) Coating the outer periphery of a bundle composed of 100 composite coated copper wires with polytetrafluoroethylene to form an insulating layer with a thickness of 0.8 mm to obtain an insulating core;

[0070] (6) Place the insulated core in a braiding machine. After braiding a coated copper wire shielding layer at a braiding angle of 34°, braid an elastic polyester fiber layer with a thickness of 0.3 mm using elastic polyester fibers with a diameter of 0.10 mm at a braiding temperature of 90 °C. Among them, the item number of the elastic polyester fiber is 1008, provided by Yangzhou Tianlun Fiber Co., Ltd. Subsequently, mix 95 parts of modified rubber, 22 parts of modified vermiculite, 8 parts of stearic acid, 7 parts of carbon black, and 3.2 parts of sulfur, and vulcanize at 150 °C and 11 MPa for 17 min, and then vulcanize at 215 °C for 1 h. Subsequently, extrude and coat it outside the elastic polyester fiber layer to form a sheath with a thickness of 3 mm, and naturally cool it to room temperature to obtain a B1-level flame-retardant coaxial feeder for low-loss ultra-flexible indoor distribution.

[0071] Comparative Example 4 (without plasma nitriding treatment): (1) At 50 °C, add ethylene propylene diene monomer rubber to a flask containing xylene and stir until completely dissolved. Under a nitrogen atmosphere at 70 °C, sequentially add trans-2,4-hexadien-1-ol and azobisisobutyronitrile thereto and stir and react for 3 h. The mass ratio of ethylene propylene diene monomer rubber, trans-2,4-hexadien-1-ol, and azobisisobutyronitrile is 1:0.06:0.005. Precipitate with acetone, extract with N,N-dimethylformamide, and vacuum dry to obtain modified ethylene propylene diene monomer rubber;

[0072] (2) Place a copper wire with a diameter of 0.15 mm in an unbalanced magnetron sputtering device, and deposit it by magnetron sputtering in a nitrogen-containing atmosphere using a silver-zirconium binary material as a target to obtain a coated copper wire; the composition and weight percentage of the silver-zirconium binary material are: Zr is 24%, and the balance is Ag and unavoidable impurities. The vacuum degree of the nitrogen-containing atmosphere is mbar, the volume ratio of nitrogen to argon in the nitrogen-containing atmosphere is 1:1.3, the deposition power of magnetron sputtering is 50 kW, and the surface film layer thickness is 10 nm;

[0073] (3) Ultrasonically disperse 10 g of vermiculite powder with a particle size of 200 mesh and 200 mL of hydrogen peroxide aqueous solution (30 wt%) for 10 min. Under mechanical stirring, heat up to 105 °C and react for 6 h. After cooling, centrifuge at 5000 rpm for 5 min, wash 3 times with deionized water, and vacuum dry at 80 °C for 5 h to obtain hydroxylated vermiculite powder;

[0074] (4) Mix 50 parts by mass of hydroxylated vermiculite powder, 75 parts by mass of acrylic acid, and 18 parts by mass of water. After stirring evenly, add 10 parts by mass of 1 mol / L silver nitrate solution dropwise at 30 °C, and stir at a speed of 200 r / min while adding. Then let it stand for 2 h, and then add 0.4 parts by mass of potassium persulfate. Stir at 60 °C and 200 r / min for 1 h. After the stirring ends, perform suction filtration, washing with water, and drying, and then send it into a carbonization furnace. Under normal pressure conditions, introduce nitrogen, heat up to 200 °C at a rate of 7 °C / min. After the temperature stabilizes, keep it warm for 30 min. Then introduce air, heat up to 300 °C at a rate of 4 °C / min. After the temperature stabilizes, keep it warm for 100 min. Then introduce nitrogen again, heat up to 620 °C at a rate of 4 °C / min. After the temperature stabilizes, keep it warm for 30 min to obtain modified vermiculite;

[0075] (5) Coating the outer periphery of the bundle made of 100 composite coated copper wires with polytetrafluoroethylene to form an insulating layer with a thickness of 0.8 mm, and obtaining an insulating core;

[0076] (6) Place the insulating core in a knitting machine, knit a coated copper wire shielding layer at a knitting angle of 34°, and then knit an elastic polyester fiber layer with a thickness of 0.3 mm at an elastic polyester fiber diameter of 0.10 mm and a knitting temperature of 90 °C. Among them, the elastic polyester fiber product number is 1008, provided by Yangzhou Tianlun Fiber Co., Ltd. Subsequently, mix 95 parts of modified rubber, 22 parts of modified vermiculite, 8 parts of stearic acid, 7 parts of carbon black, and 3.2 parts of sulfur, and vulcanize at 150 °C and 11 MPa for 17 min, and vulcanize at 215 °C for 1 h. Then extrude and coat it outside the elastic polyester fiber layer to form a sheath with a thickness of 3 mm, and naturally cool to room temperature to obtain a B1-level flame-retardant coaxial feeder for low-loss ultra-flexible indoor distribution.

[0077] Comparative Example 5 (without adding an elastic polyester fiber braided layer): (1) At 50 °C, add ethylene propylene diene monomer rubber to a flask containing xylene and stir until completely dissolved. Under a nitrogen atmosphere at 70 °C, sequentially add trans-2,4-hexadien-1-ol and azobisisobutyronitrile to it and stir and react for 3 h. The mass ratio of ethylene propylene diene monomer rubber, trans-2,4-hexadien-1-ol, and azobisisobutyronitrile is 1:0.06:0.005. Precipitate with acetone and extract with N,N-dimethylformamide, and dry in vacuum to obtain modified ethylene propylene diene monomer rubber;

[0078] (2) A copper wire with a diameter of 0.15 mm is placed in an unbalanced magnetron sputtering device and deposited by magnetron sputtering using a silver-zirconium binary material as the target in a nitrogen-containing atmosphere. Then it is placed in an ion nitriding device. After evacuating to below 15 Pa, ammonia gas is introduced, the air pressure is maintained at 200 Pa, the furnace temperature is raised to 520 °C, and then plasma nitriding surface treatment is carried out. The holding time is 15 min. After the treatment is completed, it is cooled to room temperature with the furnace, and the coated copper wire is obtained; the composition and weight percentage of the silver-zirconium binary material are: Zr is 24%, and the balance is Ag and unavoidable impurities. The vacuum degree of the nitrogen-containing atmosphere is mbar, the volume ratio of nitrogen to argon in the nitrogen-containing atmosphere is 1:1.3, the deposition power of magnetron sputtering is 50 kW, and the surface film layer thickness is 10 nm;

[0079] (3) 10 g of vermiculite powder with a particle size of 200 mesh and 200 mL of hydrogen peroxide aqueous solution (30 wt%) are ultrasonically dispersed for 10 min. Under the action of mechanical stirring, the temperature is raised to 105 °C and reacted for 6 h. After cooling, it is centrifuged at 5000 rpm for 5 min, washed 3 times with deionized water, and vacuum dried at 80 °C for 5 h to obtain hydroxylated vermiculite powder;

[0080] (4) 50 parts by mass of hydroxylated vermiculite powder, 75 parts by mass of acrylic acid, and 18 parts by mass of water are mixed and stirred evenly. At 30 °C, 10 parts by mass of 1 mol / L silver nitrate solution is added dropwise, and stirring is carried out at a speed of 200 r / min while adding. After that, it is left standing for 2 h, then 0.4 parts by mass of potassium persulfate is added, and stirring is carried out at 60 °C and 200 r / min for 1 h. After the stirring is completed, it is filtered, washed with water, and dried, and then sent into a carbonization furnace. Under normal pressure conditions, nitrogen is introduced, and the temperature is raised to 200 °C at a rate of 7 °C / min. After the temperature is stabilized, it is held for 30 min, then air is introduced, and the temperature is raised to 300 °C at a rate of 4 °C / min. After the temperature is stabilized, it is held for 100 min, and then nitrogen is introduced, and the temperature is raised to 620 °C at a rate of 4 °C / min. After the temperature is stabilized, it is held for 30 min to obtain modified vermiculite;

[0081] (5) Polytetrafluoroethylene is coated on the periphery of a bundle composed of 100 composite coated copper wires to form an insulating layer with a thickness of 0.8 mm, and an insulated core is obtained;

[0082] (6) The insulated core is placed in a braiding machine, and a coated copper wire shielding layer is braided at a braiding angle of 34°. Subsequently, 95 parts of modified rubber, 22 parts of modified vermiculite, 8 parts of stearic acid, 7 parts of carbon black, and 3.2 parts of sulfur are mixed and kneaded. At 150 °C and 11 MPa, vulcanization is carried out for 17 min, and at 215 °C, vulcanization is carried out for 1 h. Subsequently, it is extruded and coated on the outside of the elastic polyester fiber layer to form a sheath with a thickness of 3 mm, and it is naturally cooled to room temperature to obtain a low-loss ultra-flexible indoor distribution B1-class flame-retardant coaxial feeder.

[0083] Comparative Example 6 (without adding hydroxyl-containing conjugated diene monomer): (1) A copper wire with a diameter of 0.15 mm was placed in an unbalanced magnetron sputtering device and deposited by magnetron sputtering in a nitrogen-containing atmosphere using a silver-zirconium binary material as the target. Then it was placed in an ion nitriding device. After evacuating to below 15 Pa, ammonia gas was introduced, and the gas pressure was maintained at 200 Pa. The furnace temperature was raised to 520 °C, and then plasma nitriding surface treatment was carried out. The holding time was 15 min. After the treatment was completed, it was cooled to room temperature with the furnace, and a coated copper wire was obtained. The composition and weight percentage of the silver-zirconium binary material were: Zr was 24%, and the balance was Ag and unavoidable impurities. The vacuum degree of the nitrogen-containing atmosphere was mbar, the volume ratio of nitrogen to argon in the nitrogen-containing atmosphere was 1:1.3, the deposition power of magnetron sputtering was 50 kW, and the surface film layer thickness was 10 nm;

[0084] (2) 10 g of vermiculite powder with a particle size of 200 mesh and 200 mL of hydrogen peroxide aqueous solution (30 wt%) were ultrasonically dispersed for 10 min. Under mechanical stirring, the temperature was raised to 105 °C and reacted for 6 h. After cooling, it was centrifuged at 5000 rpm for 5 min, washed 3 times with deionized water, and vacuum dried at 80 °C for 5 h to obtain hydroxylated vermiculite powder;

[0085] (3) 50 parts by mass of hydroxylated vermiculite powder, 75 parts by mass of acrylic acid, and 18 parts by mass of water were mixed and stirred evenly. Then, 10 parts by mass of 1 mol / L silver nitrate solution was added dropwise at 30 °C, and stirred at a speed of 200 r / min while adding. After that, it was left standing for 2 h, and then 0.4 part by mass of potassium persulfate was added. It was stirred at 60 °C and 200 r / min for 1 h. After the stirring was completed, it was filtered, washed with water, and dried, and then sent into a carbonization furnace. Under normal pressure conditions, nitrogen was introduced, and the temperature was raised to 200 °C at a rate of 7 °C / min. After the temperature was stabilized, it was held for 30 min. Then, air was introduced, and the temperature was raised to 300 °C at a rate of 4 °C / min. After the temperature was stabilized, it was held for 100 min. Then, nitrogen was introduced again, and the temperature was raised to 620 °C at a rate of 4 °C / min. After the temperature was stabilized, it was held for 30 min to obtain modified vermiculite;

[0086] (4) Polytetrafluoroethylene was coated on the periphery of a bundle composed of 100 composite coated copper wires to form an insulating layer with a thickness of 0.8 mm, and an insulated core was prepared;

[0087] (5) Place the insulated core in a braiding machine. After braiding a coated copper wire shielding layer at a braiding angle of 34°, braid a 0.3 mm thick polyester fiber layer with a polyester fiber diameter of 0.10 mm at a braiding temperature of 90 °C. Among them, the elastic polyester fiber product number is 1008, provided by Yangzhou Tianlun Fiber Co., Ltd. Subsequently, 95 parts of ethylene propylene diene monomer rubber, 22 parts of modified vermiculite, 8 parts of stearic acid, 7 parts of carbon black, and 3.2 parts of sulfur are mixed and kneaded. At 150 °C and 11 MPa, vulcanize for 17 min, and at 215 °C, vulcanize for 1 h. Subsequently, extrude and coat it outside the polyester fiber layer to form a sheath with a thickness of 3 mm, and naturally cool it to room temperature to obtain a B1-level flame-retardant coaxial feeder for low-loss ultra-flexible indoor distribution.

[0088] Comparative Example 7 (only using vermiculite): (1) At 50 °C, add ethylene propylene diene monomer rubber to a flask containing xylene and stir until completely dissolved. Under a nitrogen atmosphere at 70 °C, successively add trans-2,4-hexadien-1-ol and azobisisobutyronitrile to it and stir and react for 3 h. The mass ratio of ethylene propylene diene monomer rubber, trans-2,4-hexadien-1-ol, and azobisisobutyronitrile is 1:0.06:0.005. Precipitate with acetone, extract with N,N-dimethylformamide, and vacuum dry to obtain modified ethylene propylene diene monomer rubber;

[0089] (2) Place a copper wire with a diameter of 0.15 mm in an unbalanced magnetron sputtering device, deposit it by magnetron sputtering in a nitrogen-containing atmosphere using a silver-zirconium binary material as the target, and then place it in an ion nitriding device. After evacuating to below 15 Pa, introduce ammonia gas, keep the gas pressure at 200 Pa, raise the furnace temperature to 520 °C, and then perform plasma nitriding surface treatment. The holding time is 15 min. After the treatment is completed, cool it to room temperature with the furnace to obtain a coated copper wire; The composition and weight percentage of the silver-zirconium binary material are: Zr is 24%, and the balance is Ag and unavoidable impurities. The vacuum degree of the nitrogen-containing atmosphere is mbar, the volume ratio of nitrogen and argon in the nitrogen-containing atmosphere is 1:1.3, the deposition power of magnetron sputtering is 50 kW, and the surface film layer thickness is 10 nm;

[0090] (3) Wrap polytetrafluoroethylene around the periphery of a bundle made of 100 composite coated copper wires to form an insulating layer with a thickness of 0.8 mm to obtain an insulated core;

[0091] (4) Place the insulated core in a braiding machine. After braiding a coated copper wire shielding layer at a braiding angle of 34°, braid a 0.3 mm thick polyester fiber layer with a polyester fiber diameter of 0.10 mm at a braiding temperature of 90°C. Among them, the elastic polyester fiber product number is 1008, provided by Yangzhou Tianlun Fiber Co., Ltd. Subsequently, mix 95 parts of modified rubber, 22 parts of vermiculite powder with a particle size of 200 mesh, 8 parts of stearic acid, 7 parts of carbon black, and 3.2 parts of sulfur, and vulcanize at 150°C and 11 MPa for 17 min, and then vulcanize at 215°C for 1 h. Subsequently, extrude and coat it outside the polyester fiber layer to form a sheath with a thickness of 3 mm, and naturally cool it to room temperature to obtain a B1-level flame-retardant coaxial feeder for low-loss ultra-flexible in-building distribution.

[0092] Select 3 coaxial feeders prepared from Examples 1-3 and Comparative Examples 1-7 respectively as test samples, and conduct tensile strength and elongation at break tests on the test samples according to the standard of GB / T 2951-2008, and calculate the average values of the tensile strength and elongation at break of each group. The results are shown in Table 3.

[0093]

[0094] Use a bending test machine to conduct an anti-bending performance swing test on Experimental Samples 1-3 and Comparative Samples 1-7 respectively. The cable will not be overly bent at the interface. Add a heavy object to the cable as a load so that the applied force is 5 N. Use a clamping plate with R = 10 mm swing mechanism to swing at an angle of 180° (90° on each side of the plumb line), the number of swings is 5000, and the swing rate is 30 times per minute. During the test, a current of 0.5 A needs to be passed; those that do not break after the experiment are recorded as '0', and those that break or have cracks are recorded as '1'. The results are shown in Table 4.

[0095]

[0096] Select 3 coaxial feeders prepared from Examples 1-3 and Comparative Examples 1-7 respectively as test samples, and conduct abrasion resistance tests on the test samples according to the standard of GB / T 5013-2008. After each group of coaxial feeders pass through 20,000 one-way movements respectively, record the length of the exposed part of the cable insulation of each group of test samples, and calculate the average value of the length of the exposed part of the cable insulation of each group of test samples. The results are shown in Table 5.

[0097]

[0098] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in any regard, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Accordingly, all changes that fall within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claim concerned.

Claims

1. A B1 - level flame - retardant coaxial feeder for low - loss and ultra - flexible in - building distribution, characterized in that, The low-loss and super-flexible Class B1 fire-retardant coaxial feeder for in-building distribution includes a composite-coated fine copper wire bundle, a polytetrafluoroethylene insulation layer, a coated copper wire shielding layer, an elastic polyester fiber layer, and a modified rubber sheath layer; The coated fine copper wire bundle is obtained by stranding and bundling coated copper wires; the coated copper wire shielding layer is obtained by weaving coated copper wires into a net; wherein, the preparation method of the coated copper wire is: placing a copper wire with a diameter of 0.15 mm in an unbalanced magnetron sputtering device, using a silver-zirconium binary material as a target, and magnetron sputtering and depositing in a nitrogen-containing atmosphere, then placing it in an ion nitriding device, evacuating to below 15 Pa and then introducing ammonia gas, keeping the gas pressure at 200 Pa, raising the furnace temperature to 500-520 °C, and then performing plasma nitriding surface treatment, with a holding time of 15 min, and cooling to room temperature with the furnace after the treatment is completed; The modified rubber sheath layer is obtained by mixing, vulcanizing, and extruding 75-115 parts of modified rubber, 18-26 parts of modified vermiculite, 6-10 parts of stearic acid, 4-10 parts of carbon black, and 2.6-3.8 parts of sulfur; The modified rubber is obtained by graft-modifying ethylene-propylene-diene monomer rubber with a hydroxyl-containing conjugated diene monomer.

2. The B1 - level flame - retardant coaxial feeder for low - loss and ultra - flexible in - building distribution according to claim 1, wherein, The hydroxyl-containing conjugated diene monomer is one of 2,4-heptadien-1-ol, trans-2,4-hexadien-1-ol, and 2,4-octadien-1-ol.

3. A B1 - level flame - retardant coaxial feeder for low - loss and ultra - flexible in - building distribution according to claim 1, characterized in that, The preparation method of the modified vermiculite: mixing 50 parts by mass of hydroxylated vermiculite powder, 50-100 parts by mass of acrylic acid, and 16-20 parts by mass of water, stirring evenly, dropping 5-15 parts by mass of silver nitrate solution at 30 °C while stirring, standing for 2 h after dropping, then adding 0.4-3 parts by mass of initiator, reacting at 60-90 °C with stirring for 1-2 h, and after the stirring ends, performing suction filtration, washing, drying, and carbonization.

4. A Class B flame-retardant coaxial feeder for low-loss and ultra-flexible in-building distribution according to claim 3, characterized in that, The initiator is a peroxide or a persulfide.

5. A Class B1 flame-retardant coaxial feeder for low-loss and ultra-flexible in-building distribution according to claim 4, characterized in that, The persulfide is potassium persulfate, and the peroxide is cumene hydroperoxide.

6. A B1 - class flame - retardant coaxial feeder for low - loss and ultra - flexible in - building distribution according to claim 3, characterized in that, The particle size of the vermiculite powder is 200 mesh.

7. A B1 - level flame - retardant coaxial feeder for low - loss and ultra - flexible in - building distribution according to claim 3, characterized in that, The stirring is carried out at a speed of 150-300 r / min.

8. A B1 - class flame - retardant coaxial feeder for low - loss and ultra - flexible in - building distribution according to claim 3, characterized in that, The specific process of the carbonization is: feeding into a carbonization furnace, under normal pressure conditions, introducing nitrogen gas, heating to 160-220 °C at a rate of 5-10 °C / min, after the temperature is stabilized, holding for 30-50 min, then introducing air, heating to 250-320 °C at a rate of 3-6 °C / min, after the temperature is stabilized, holding for 60-120 min, then introducing nitrogen gas, heating to 600-650 °C at a rate of 3-6 °C / min, after the temperature is stabilized, holding for 20-40 min.

9. A B1 - level flame - retardant coaxial feeder for low - loss and ultra - flexible in - building distribution according to claim 3, characterized in that, The concentration of the silver nitrate solution is 1 mol / L.

10. The application of a Class B1 flame-retardant coaxial feeder for low-loss and ultra-flexible in-building distribution according to claim 1, characterized in that, The low-loss and super-flexible Class B1 fire-retardant coaxial feeder for in-building distribution is applied to the in-building DAS system.

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