A low dielectric loss flexible cable and a method of making the same

Abstract

This invention discloses a low-dielectric-loss flexible cable and its manufacturing method, relating to the field of cable technology. The cable, from the outside in, comprises an outer sheath, an outer shielding layer, a foam buffer layer, and a cable core. The cable core consists of six insulated cores twisted around a central axis. Each insulated core includes a conductor and its outer insulation layer, inner sheath, and shielding layer. The inner and outer sheaths are made of a flexible rubber material composed of amino-containing silicone rubber, modified recycled rubber, plasticized modified lignin, cerium oxide nanosheets, silica nanosheets, sulfur, and an accelerator (CZ). This invention, through optimized material formulation and structural design, significantly improves the cable's flexibility, flame retardancy, and low-dielectric-loss performance, making it suitable for high-frequency signal transmission scenarios such as 5G communication, the Internet of Things, high-speed data transmission, and portable electronic devices.

Description

Technical Field

[0001] This invention relates to the field of cable technology, specifically to a low dielectric loss flexible cable and its preparation method. Background Technology

[0002] With the rapid development of 5G communication, the Internet of Things, high-speed data transmission, and portable and wearable electronic devices, more stringent requirements are being placed on the performance of cables—the core component connecting these devices. Cables used for high-frequency signal transmission, in particular, not only need extremely low dielectric loss to ensure signal integrity and reduce energy loss, but also must possess excellent flexibility to adapt to complex wiring and frequent bending scenarios. Simultaneously, the flame-retardant properties of cable materials are also crucial in confined spaces or environments with high safety requirements.

[0003] Currently, the sheath layer of flexible cables is often made of materials such as polyvinyl chloride (PVC), thermoplastic polyurethane (TPU), or ordinary silicone rubber (i.e., the same type of silicone rubber without surface amination). While PVC is low in cost, its flexibility, environmental friendliness, and dielectric properties are poor. Thermoplastic polyurethane (TPU) has good flexibility, but its dielectric loss at high frequencies is relatively high, and some grades lack sufficient flame retardancy. Ordinary silicone rubber (i.e., the same type of silicone rubber without surface amination) has excellent dielectric properties and is flexible, but the mechanical strength of pure silicone rubber often fails to meet the requirements of long-term use, and flame retardancy usually requires the addition of large amounts of flame retardants, which may reduce its flexibility and processing performance, and even increase dielectric loss.

[0004] To improve the flame retardancy of cables, traditional methods typically involve adding halogenated flame retardants or large amounts of inorganic fillers. However, halogenated flame retardants present environmental and potential toxicity issues, while the addition of inorganic fillers, although improving flame retardancy, often significantly impairs the material's flexibility and processing flowability, leading to cable stiffening and decreased bending performance. High filler content can also adversely affect dielectric properties. On the other hand, while recycling waste rubber helps with environmental protection and cost reduction, directly using recycled rubber powder as a filler results in poor compatibility and weak interfacial bonding with the matrix rubber, severely reducing the mechanical properties and durability of the composite material. Its inherent flame retardancy is also low, limiting its application in high-performance cables.

[0005] In recent years, nanofillers have attracted attention due to their ability to simultaneously improve the mechanical, barrier, and flame-retardant properties of materials. However, the uniform dispersion of nanofillers in rubber matrices and the effective construction of barrier structures remain technical challenges. Simple physical blending often leads to filler agglomeration, failing to fully realize their reinforcing and barrier effects. Achieving a highly oriented arrangement of nanosheets in a polymer matrix to form a dense physical barrier network, and enabling it to synergistically interact with the matrix and other components, is key to improving the overall performance of cable sheaths. Summary of the Invention

[0006] The purpose of this invention is to provide a low dielectric loss flexible cable and its preparation method to solve the problems existing in the prior art.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a low dielectric loss flexible cable, comprising, from the outside to the inside, an outer sheath layer, an outer shielding layer, a foam buffer layer, and a cable core. The cable core includes six insulated wire cores twisted around a central axis. Each insulated wire core includes a conductor, an insulation layer covering the conductor, an inner sheath layer covering the insulation layer, and an inner shielding layer covering the inner sheath layer. Both the inner and outer sheath layers are made of flexible rubber material, which is composed of the following raw materials in parts by weight: 20-25 parts of amino-containing silicone rubber, 20-25 parts of modified recycled rubber, 6-10 parts of plasticized modified lignin, 1-5 parts of cerium oxide nanosheets, 1-5 parts of silica nanosheets, 0.3-0.4 parts of sulfur, and 1.9-2.5 parts of accelerator CZ.

[0008] The preparation method of the flexible rubber material is as follows: add the formulated amounts of amino-containing silicone rubber, modified reclaimed rubber, plasticized modified lignin, cerium oxide nanosheets, and silica nanosheets into a two-roll mill, mix them evenly at 40-50℃, then add sulfur and accelerator CZ, and continue mixing for 10-15 minutes to obtain the compound; vulcanize the compound on a flat vulcanizing machine at 160-170℃ and 10-15MPa pressure for 20-30 minutes to obtain the final product.

[0009] Furthermore, the amino-containing silicone rubber on the surface is a methyl vinyl silicone rubber with particles of 0.1-1 mm in diameter, which is then modified by immersing in a toluene solution of KH-550.

[0010] Furthermore, the modified recycled rubber is obtained by treating waste rubber powder with acid twice, wherein the first acid soaking treatment is an acidic solution and the second acid soaking treatment is a phytic acid solution.

[0011] Furthermore, the acidic solution is obtained by mixing concentrated sulfuric acid with a mass concentration of 98% and deionized water at a volume ratio of 1:1, and the phytic acid solution is obtained by mixing 70wt% phytic acid and deionized water at a volume ratio of 1:1.

[0012] Furthermore, the preparation method of the plasticized modified lignin is as follows: lignin, 1,2-propanediol, triethyl citrate, and urea are mixed evenly in a mass ratio of (10-20):(8-12):(4-6):(1-2), and then melt-extruded and granulated using a twin-screw extruder at a temperature of 70-105°C. During the high-temperature vulcanization process, the plasticized modified lignin undergoes secondary melting, forming a stronger interfacial bond with the rubber matrix, and facilitating its subsequent migration to the surface to form a char layer under combustion conditions.

[0013] Furthermore, both the cerium oxide nanosheets and the silicon dioxide nanosheets are surface-modified with KH-550.

[0014] Furthermore, the insulating layer is made of low dielectric loss polypropylene material, which is composed of the following raw materials in parts by weight: 50-100 parts polypropylene resin, 25-40 parts low density polyethylene resin, 5-20 parts EPDM rubber, 1.2-2.5 parts antioxidant, and 0.3-0.8 parts lubricant.

[0015] The preparation method of the low dielectric loss polypropylene material for the insulating layer is as follows: add the formulated amount of polypropylene resin, low density polyethylene resin, EPDM rubber, antioxidant, and lubricant to a high-speed mixer and mix evenly. Then, melt-blend and granulate the mixture through a twin-screw extruder at 180-220℃ to obtain the final product.

[0016] Furthermore, both the outer and inner shielding layers are made of silver-plated copper wire braiding with a braiding density of ≥90%.

[0017] Furthermore, the foam buffer layer is made of polyethylene foam material with a thickness of 1-2 mm.

[0018] Furthermore, the melt index of the low-density polyethylene at 190℃ / 2.16Kg is 1-3g / 10min.

[0019] Furthermore, the polypropylene resin is Daqing Petrochemical EPS30R.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are: (1) The present invention uses amino-containing silicone rubber, modified recycled rubber, plasticized modified lignin, cerium oxide nanosheets, and silica nanosheets as flexible rubber materials, and uses them as the material for the inner and outer sheath layers. It has good softness and bending performance, and also has certain mechanical properties.

[0021] (2) The modified recycled rubber of the present invention uses waste rubber as raw material and undergoes two acid treatments. The first acid treatment grafts active functional groups such as carboxyl and hydroxyl groups onto the surface of the rubber powder. The second acid treatment achieves the grafting modification of the surface by phytic acid, thereby improving its flame retardant properties. With the introduction of phytic acid on the surface, the phosphate groups on its molecules may form hydrogen bonds or ionic interactions with the amino groups on the surface of the amino-containing silicone rubber, thereby improving the compatibility of the two-phase interface, improving the mechanical properties of the layer material, and reducing the cracks caused by twisting.

[0022] (3) After pretreatment, cerium oxide nanosheets and silica nanosheets can achieve good dispersion of rubber materials. At the same time, there is a strong hydrogen bond interaction between cerium oxide nanosheets and silica nanosheets. Under the action of hydrogen bonds, after melt extrusion, they are expected to be tightly stacked together and highly oriented along the plane direction to form a dense physical barrier layer with a "brick and mortar" structure, thereby effectively exerting the barrier effect and playing a synergistic flame retardant effect with plasticized modified lignin and modified recycled rubber.

[0023] (4) The present invention incorporates plasticized modified lignin, which exists in the rubber matrix in the form of uniformly dispersed particles at room temperature, effectively playing a role in toughening and strengthening. Under high temperature or combustion conditions, it can melt and flow to form a continuous and dense carbonized layer on the material surface. This carbonized layer, as an efficient physical barrier, not only significantly delays the transfer of heat to the interior of the matrix and hinders the escape of combustible gases and the diffusion of oxygen, thereby greatly improving the flame retardant performance of the material, but also effectively protects the internal structure from high temperature damage.

[0024] In summary, the sheath material of the present invention, through the synergistic effect of modified recycled rubber, plasticized modified lignin and nanosheets, significantly improves the mechanical strength and flame retardant properties of silicone rubber while maintaining its excellent flexibility. Detailed Implementation

[0025] 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.

[0026] To more clearly illustrate the method provided by the present invention, the following embodiments are provided in detail. The testing methods for various indicators of the cables produced in the following embodiments are as follows: Mechanical properties: The inner and outer sheaths of the cables prepared in the examples and comparative examples were sampled together, and tensile strength and elongation at break were tested in accordance with standard GB / T528-2009. The average value of 10 tests was recorded in Table 1.

[0027] Flame retardancy test of cables: Flame retardancy tests were conducted on the cables prepared in the examples and comparative examples, with reference to standards UL758 and UL1581. The results are recorded in Table 1.

[0028] Low dielectric loss performance: The insulation layer of the cable prepared in the example was sampled and the dielectric loss factor of the insulation layer of the cable prepared in the example was tested using a high-frequency dielectric analyzer at frequencies of 1 GHz, 5 GHz and 10 GHz, with reference to the IPC-TM-6502.5.5.9 standard. The test results are recorded in Table 2.

[0029] Example 1 A low dielectric loss flexible cable comprises, from the outside to the inside, an outer sheath, an outer shielding layer, a foam buffer layer, and a cable core. The cable core includes six insulated wires twisted around a central axis. Each insulated wire includes a conductor, an insulation layer covering the conductor, an inner sheath covering the insulation layer, and an inner shielding layer covering the inner sheath. Both the outer and inner shielding layers are braided from silver-plated copper wire with a braiding density ≥90%. The foam buffer layer is made of polyethylene foam material with a thickness of 1.3 mm. Both the outer and inner sheath layers are made of flexible rubber material, which is composed of the following raw materials in parts by weight: 21 parts of amino-containing silicone rubber, 22 parts of modified recycled rubber, 7 parts of plasticized modified lignin, 2 parts of cerium oxide nanosheets, 2 parts of silica nanosheets, 0.32 parts of sulfur, and 2.0 parts of accelerator CZ (N-cyclohexyl-2-benzothiazole sulfenamide). Both the cerium oxide nanosheets and silica nanosheets were surface-modified with KH-550 (γ-aminopropyltriethoxysilane). The specific process is as follows: 8g of silane coupling agent KH-550 was added to 120mL of a 1:1 water-alcohol mixture (ethanol and deionized water in a 1:1 volume ratio). A condenser was connected, and the temperature was maintained at 55℃ while stirring for 45min. Then, 22g of cerium oxide nanosheets or silica nanosheets were added, and the stirring speed was adjusted to 1700r / s for 2h. The mixture was then filtered and collected, washed five times with acetone to remove surface impurities, and then dried under vacuum at 80℃ for 11h. The preparation method of the amino-containing silicone rubber is as follows: Methyl vinyl silicone rubber particles with a particle size of 0.1-1 mm are immersed in a toluene solution of KH-550, the mass ratio of silicone rubber to the volume of the toluene solution of KH-550 is 1 g: 50 mL, and the volume percentage of KH-550 to the toluene solution is 25%. The reaction is carried out in a closed container at 35°C with shaking for 6 hours; the silicone rubber is taken out and washed with anhydrous ethanol, and dried in a vacuum oven at 50°C for 12 hours to obtain the amino-containing silicone rubber. The modified reclaimed rubber is prepared by washing 150-mesh waste rubber powder with clean water, drying it in an oven at 80°C, and then mixing and reacting it with an acidic solution. The acidic solution is obtained by slowly adding 98% concentrated sulfuric acid to an equal volume of deionized water while continuously stirring and cooling to 25±5°C. The mass-to-volume ratio of the waste rubber powder to the acidic solution is 1.5 g / mL. After soaking for 4 hours, the mixture is filtered, washed with deionized water until neutral, and then vacuum dried at 75±5°C. The rubber powder is then mixed and reacted with a phytic acid solution. The phytic acid solution is obtained by mixing 70 wt% phytic acid with deionized water at a volume ratio of 1:1. The mass-to-volume ratio of the waste rubber powder to the phytic acid solution is 1.5 g / mL. After soaking for 2 hours, the mixture is filtered, washed with deionized water until neutral, and then vacuum dried at 75±5°C to obtain the modified reclaimed rubber. The preparation method of the plasticized modified lignin is as follows: lignin, 1,2-propanediol, triethyl citrate and urea are mixed evenly in a mass ratio of 15:10:5:1.5, and then melt-extruded and granulated by a twin-screw extruder at a temperature of 70-105°C to obtain plasticized modified lignin. The insulating layer is made of low dielectric loss polypropylene material, which is composed of the following raw materials in parts by weight: 65 parts polypropylene resin, 32 parts low density polyethylene resin, 12 parts EPDM rubber, 1.8 parts pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and 0.45 parts polyethylene wax with a number average molecular weight of 3500.

[0030] Example 2 A low dielectric loss flexible cable comprises, from the outside to the inside, an outer sheath, an outer shielding layer, a foam buffer layer, and a cable core. The cable core includes six insulated wires twisted around a central axis. Each insulated wire includes a conductor, an insulation layer covering the conductor, an inner sheath covering the insulation layer, and an inner shielding layer covering the inner sheath. Both the outer and inner shielding layers are braided from silver-plated copper wire with a braiding density ≥90%. The foam buffer layer is made of polyethylene foam material with a thickness of 1.5 mm. Both the outer sheath and the inner sheath are made of flexible rubber material, which is composed of the following raw materials in parts by weight: 22 parts of amino-containing silicone rubber, 23 parts of modified recycled rubber, 8 parts of plasticized modified lignin, 3 parts of cerium oxide nanosheets, 3 parts of silica nanosheets, 0.35 parts of sulfur, and 2.1 parts of accelerator CZ. Both the cerium oxide nanosheets and silica nanosheets were surface-modified with KH-550. The specific process is as follows: In a sealed container equipped with a reflux condenser, 12g of silane coupling agent KH-550 was added to 150mL of a 1:1 water-alcohol mixture (ethanol and deionized water in a 1:1 volume ratio). A condenser was connected, and the temperature was maintained at 60℃ while stirring for 50min. Then, 25g of cerium oxide nanosheets or silica nanosheets were added, and the stirring speed was adjusted to 1850r / s for 2.5h. The mixture was then filtered and collected, washed five times with acetone to remove surface impurities, and then dried under vacuum at 85℃ for 11h. The preparation method of the amino-containing silicone rubber is as follows: Methyl vinyl silicone rubber particles with a particle size of 0.1-1 mm are immersed in a toluene solution of KH-550, the mass ratio of silicone rubber to the volume of the toluene solution of KH-550 is 1 g: 30 mL, and the volume percentage of KH-550 to the toluene solution is 15%. The reaction is carried out in a closed container at 40°C with shaking for 4 hours; the silicone rubber is taken out and washed with anhydrous ethanol, and dried in a vacuum oven at 50°C for 12 hours to obtain the amino-containing silicone rubber. The modified reclaimed rubber is prepared by washing 120-mesh waste rubber powder with clean water, drying it in an oven at 80°C, and then mixing and reacting it with an acidic solution. The acidic solution is obtained by slowly adding 98% concentrated sulfuric acid to an equal volume of deionized water while continuously stirring and cooling to 25±5°C. The mass-to-volume ratio of the waste rubber powder to the acidic solution is 1.2 g / mL. After soaking for 4 hours, the mixture is filtered, washed with deionized water until neutral, and then vacuum dried at 75±5°C. The rubber powder is then mixed and reacted with a phytic acid solution. The phytic acid solution is obtained by mixing 70 wt% phytic acid with deionized water at a volume ratio of 1:1. The mass-to-volume ratio of the waste rubber powder to the phytic acid solution is 1.8 g / mL. After soaking for 2 hours, the mixture is filtered, washed with deionized water until neutral, and then vacuum dried at 75±5°C to obtain the modified reclaimed rubber. The preparation method of the plasticized modified lignin is as follows: lignin, 1,2-propanediol, triethyl citrate and urea are mixed evenly in a mass ratio of 18:9:4.5:1.2, and then melt-extruded and granulated by a twin-screw extruder at a temperature of 70-105°C to obtain plasticized modified lignin. The insulating layer is made of low dielectric loss polypropylene material, which is composed of the following raw materials in parts by weight: 75 parts polypropylene resin, 35 parts low-density polyethylene resin, 8 parts EPDM rubber, 1.5 parts 2,2'-thiobis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and 0.5 parts polyethylene with a number average molecular weight of 4200.

[0031] Example 3 A low dielectric loss flexible cable comprises, from the outside to the inside, an outer sheath, an outer shielding layer, a foam buffer layer, and a cable core. The cable core includes six insulated cores twisted around a central axis. Each insulated core includes a conductor, an insulation layer covering the conductor, an inner sheath covering the insulation layer, and an inner shielding layer covering the inner sheath. Both the outer and inner shielding layers are braided from silver-plated copper wire with a braiding density ≥90%. The foam buffer layer is made of polyethylene foam material with a thickness of 1.8 mm. Both the outer sheath layer and the inner sheath layer are made of flexible rubber material, which is composed of the following raw materials in parts by weight: Amino-containing silicone rubber on the surface: 23 parts Modified recycled rubber: 21 parts Plasticized modified lignin: 9 parts Cerium oxide nanosheets: 4 parts Silica nanosheets: 1 part Sulfur: 0.38 parts Accelerator CZ: 2.3 parts; Both the cerium oxide nanosheets and silica nanosheets were surface-modified with KH-550. The specific process is as follows: In a sealed container equipped with a reflux condenser, 5g of silane coupling agent KH-550 was added to 80mL of a 1:1 water-alcohol mixture (ethanol and deionized water in a 1:1 volume ratio). A condenser was connected, and the temperature was maintained at 45℃ while stirring for 55min. Then, 18g of cerium oxide nanosheets or silica nanosheets were added, and the stirring speed was adjusted to 1550r / s for 1.2h. The mixture was then filtered and collected, washed five times with acetone to remove surface impurities, and then dried under vacuum at 75℃ for 12h. The preparation method of the amino-containing silicone rubber is as follows: Methyl vinyl silicone rubber particles with a particle size of 0.1-1 mm are immersed in a toluene solution of KH-550, the mass ratio of silicone rubber to the volume of the toluene solution of KH-550 is 1 g: 10 mL, and the volume percentage of KH-550 to the toluene solution is 40%. The reaction is carried out in a closed container at 45°C with shaking for 8 hours; the silicone rubber is taken out and washed with anhydrous ethanol, and dried in a vacuum oven at 50°C for 12 hours to obtain the amino-containing silicone rubber. The modified reclaimed rubber is prepared by washing 180-mesh waste rubber powder with clean water, drying it in an oven at 80°C, and then mixing and reacting it with an acidic solution. The acidic solution is obtained by slowly adding 98% concentrated sulfuric acid to an equal volume of deionized water while continuously stirring and cooling to 25±5°C. The mass-to-volume ratio of the waste rubber powder to the acidic solution is 1.8 g / mL. After soaking for 4 hours, the mixture is filtered, washed with deionized water until neutral, and then vacuum dried at 75±5°C. The rubber powder is then mixed and reacted with a phytic acid solution. The phytic acid solution is obtained by mixing 70 wt% phytic acid with deionized water at a volume ratio of 1:1. The mass-to-volume ratio of the waste rubber powder to the phytic acid solution is 1.3 g / mL. After soaking for 2 hours, the mixture is filtered, washed with deionized water until neutral, and then vacuum dried at 75±5°C to obtain the modified reclaimed rubber. The preparation method of the plasticized modified lignin is as follows: lignin, 1,2-propanediol, triethyl citrate and urea are mixed evenly in a mass ratio of 12:11:5.5:1.8, and then melt-extruded and granulated by a twin-screw extruder at a temperature of 70-105°C to obtain plasticized modified lignin. The insulating layer is made of low dielectric loss polypropylene material, which is composed of the following raw materials in parts by weight: Polypropylene resin: 85 parts Low-density polyethylene resin: 28 parts EPDM rubber: 15 parts Pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]: 2.0 parts Polyethylene wax with a number average molecular weight of 3800: 0.35 parts.

[0032] Example 4 A low dielectric loss flexible cable comprises, from the outside to the inside, an outer sheath, an outer shielding layer, a foam buffer layer, and a cable core. The cable core includes six insulated cores twisted around a central axis. Each insulated core includes a conductor, an insulation layer covering the conductor, an inner sheath covering the insulation layer, and an inner shielding layer covering the inner sheath. Both the outer and inner shielding layers are braided from silver-plated copper wire with a braiding density ≥90%. The foam buffer layer is made of polyethylene foam material with a thickness of 1.4 mm. Both the outer sheath layer and the inner sheath layer are made of flexible rubber material, which is composed of the following raw materials in parts by weight: Amino-containing silicone rubber on the surface: 24 parts Modified recycled rubber: 24 parts Plasticized modified lignin: 6.5 parts Cerium oxide nanosheets: 1.5 parts Silica nanosheets: 4 parts Sulfur: 0.33 parts Accelerator CZ: 2.4 parts; Both the cerium oxide nanosheets and silica nanosheets were surface-modified with KH-550. The specific process is as follows: In a sealed container equipped with a reflux condenser, 3g of silane coupling agent KH-550 was added to 60mL of a 1:1 water-alcohol mixture (ethanol and deionized water in a 1:1 volume ratio). A condenser was connected, and the temperature was maintained at 65℃ while stirring for 35min. Then, 28g of cerium oxide nanosheets or silica nanosheets were added, and the stirring speed was adjusted to 1950r / s for 2.8h. The mixture was then filtered and collected, washed five times with acetone to remove surface impurities, and then dried under vacuum at 87℃ for 10h. The preparation method of the amino-containing silicone rubber is as follows: Methyl vinyl silicone rubber particles with a particle size of 0.1-1 mm are immersed in a toluene solution of KH-550, the mass ratio of silicone rubber to the volume of KH-550 to the toluene solution is 1 g: 80 mL, and the volume percentage of KH-550 to the toluene solution is 5%. The reaction is carried out in a closed container at 30°C with shaking for 10 hours; the silicone rubber is taken out and washed with anhydrous ethanol, and dried in a vacuum oven at 50°C for 12 hours to obtain the amino-containing silicone rubber. The modified recycled rubber is prepared by washing 100-mesh waste rubber powder with clean water, drying it in an oven at 80°C, and then mixing and reacting it with an acidic solution. The acidic solution is obtained by slowly adding 98% concentrated sulfuric acid to an equal volume of deionized water while continuously stirring and cooling to 25±5°C. The mass-to-volume ratio of the waste rubber powder to the acidic solution is 1.1 g / mL. After soaking for 4 hours, the mixture is filtered, washed with deionized water until neutral, and then vacuum dried at 75±5°C. The rubber powder is then mixed and reacted with a phytic acid solution. The phytic acid solution is obtained by mixing 70 wt% phytic acid with deionized water at a volume ratio of 1:1. The mass-to-volume ratio of the waste rubber powder to the phytic acid solution is 1.9 g / mL. After soaking for 2 hours, the mixture is filtered, washed with deionized water until neutral, and then vacuum dried at 75±5°C to obtain the modified recycled rubber. The preparation method of the plasticized modified lignin is as follows: lignin, 1,2-propanediol, triethyl citrate and urea are mixed evenly in a mass ratio of 20:8.5:4.2:1.1, and then melt-extruded and granulated by a twin-screw extruder at a temperature of 70-105°C to obtain plasticized modified lignin. The insulating layer is made of low dielectric loss polypropylene material, which is composed of the following raw materials in parts by weight: Polypropylene resin: 55 parts Low-density polyethylene resin: 38 parts EPDM rubber: 18 parts 2,2'-Thiobis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]: 2.2 parts Polyethylene wax with a number average molecular weight of 4500: 0.65 parts.

[0033] Example 5 A low dielectric loss flexible cable comprises, from the outside to the inside, an outer sheath, an outer shielding layer, a foam buffer layer, and a cable core. The cable core includes six insulated cores twisted around a central axis. Each insulated core includes a conductor, an insulation layer covering the conductor, an inner sheath covering the insulation layer, and an inner shielding layer covering the inner sheath. Both the outer and inner shielding layers are braided from silver-plated copper wire with a braiding density ≥90%. The foam buffer layer is made of polyethylene foam material with a thickness of 1.6 mm. Both the outer sheath layer and the inner sheath layer are made of flexible rubber material, which is composed of the following raw materials in parts by weight: Amino-containing silicone rubber on the surface: 20.5 parts Modified reclaimed rubber: 20.5 parts Plasticized modified lignin: 7.5 parts Cerium oxide nanosheets: 2.5 parts Silica nanosheets: 2.5 parts Sulfur: 0.37 parts Accelerator CZ: 1.95 parts; Both the cerium oxide nanosheets and silica nanosheets were surface-modified with KH-550. The specific process is as follows: In a sealed container equipped with a reflux condenser, 10g of silane coupling agent KH-550 was added to 180mL of a 1:1 water-alcohol mixture (ethanol and deionized water in a 1:1 volume ratio). A condenser was connected, and the temperature was maintained at 50℃ while stirring for 40min. Then, 16g of cerium oxide nanosheets or silica nanosheets were added, and the stirring speed was adjusted to 1600r / s for 1.8h. The mixture was then filtered and collected, washed five times with acetone to remove surface impurities, and then dried under vacuum at 82℃ for 11.5h. The preparation method of the amino-containing silicone rubber is as follows: Methyl vinyl silicone rubber particles with a particle size of 0.1-1 mm are immersed in a toluene solution of KH-550, the mass ratio of silicone rubber to the volume of KH-550 to the toluene solution is 1 g: 5 mL, and the volume percentage of KH-550 to the toluene solution is 45%. The reaction is carried out in a closed container at 48°C with shaking for 3 hours; the silicone rubber is taken out and washed with anhydrous ethanol, and dried in a vacuum oven at 50°C for 12 hours to obtain the amino-containing silicone rubber. The modified recycled rubber is prepared by washing 200-mesh waste rubber powder with clean water, drying it in an oven at 80℃, and then mixing and reacting it with an acidic solution. The acidic solution is obtained by slowly adding 98% concentrated sulfuric acid to an equal volume of deionized water while continuously stirring and cooling to 25±5℃. The mass-to-volume ratio of the waste rubber powder to the acidic solution is 1.9 g / mL. After soaking for 4 hours, the mixture is filtered, washed with deionized water until neutral, and then vacuum dried at 75±5℃. The rubber powder is then mixed and reacted with a phytic acid solution. The phytic acid solution is obtained by mixing 70wt% phytic acid with deionized water at a volume ratio of 1:1. The mass-to-volume ratio of the waste rubber powder to the phytic acid solution is 1.1 g / mL. After soaking for 2 hours, the mixture is filtered, washed with deionized water until neutral, and then vacuum dried at 75±5℃ to obtain the modified recycled rubber. The preparation method of the plasticized modified lignin is as follows: lignin, 1,2-propanediol, triethyl citrate and urea are mixed evenly in a mass ratio of 14:11.5:5.8:1.6, and then melt-extruded and granulated by a twin-screw extruder at a temperature of 70-105°C to obtain plasticized modified lignin. The insulating layer is made of low dielectric loss polypropylene material, which is composed of the following raw materials in parts by weight: Polypropylene resin: 95 parts Low-density polyethylene resin: 26 parts EPDM rubber: 6 parts Pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]: 1.3 parts Polyethylene wax with a number average molecular weight of 3200: 0.55 parts.

[0034] Example 6 A low dielectric loss flexible cable comprises, from the outside to the inside, an outer sheath, an outer shielding layer, a foam buffer layer, and a cable core. The cable core includes six insulated cores twisted around a central axis. Each insulated core includes a conductor, an insulation layer covering the conductor, an inner sheath covering the insulation layer, and an inner shielding layer covering the inner sheath. Both the outer and inner shielding layers are braided from silver-plated copper wire with a braiding density ≥90%. The foam buffer layer is made of polyethylene foam material with a thickness of 1.7 mm. Both the outer sheath layer and the inner sheath layer are made of flexible rubber material, which is composed of the following raw materials in parts by weight: Amino-containing silicone rubber on the surface: 24.5 parts Modified reclaimed rubber: 24.5 parts Plasticized modified lignin: 8.5 parts Cerium oxide nanosheets: 3.5 parts Silica nanosheets: 3.5 parts Sulfur: 0.36 parts Accelerator CZ: 2.45 parts; Both the cerium oxide nanosheets and silica nanosheets were surface-modified with KH-550. The specific process is as follows: In a sealed container equipped with a reflux condenser, 14g of silane coupling agent KH-550 was added to 160mL of a 1:1 water-alcohol mixture (ethanol and deionized water in a 1:1 volume ratio). A condenser was connected, and the temperature was maintained at 70℃ while stirring for 55min. Then, 19g of cerium oxide nanosheets or silica nanosheets were added, and the stirring speed was adjusted to 1450r / s for 1.5h. The mixture was then filtered and collected, washed five times with acetone to remove surface impurities, and then dried under vacuum at 88℃ for 10.5h. The preparation method of the amino-containing silicone rubber is as follows: Methyl vinyl silicone rubber particles with a particle size of 0.1-1 mm are immersed in a toluene solution of KH-550, the mass ratio of silicone rubber to the volume of KH-550 to the toluene solution is 1 g: 100 mL, and the volume percentage of KH-550 to the toluene solution is 0.5%. The reaction is carried out by shaking in a closed container at 25°C for 11 hours; the silicone rubber is taken out and washed with anhydrous ethanol, and dried in a vacuum oven at 50°C for 12 hours to obtain the amino-containing silicone rubber. The modified reclaimed rubber is prepared by washing 110-mesh waste rubber powder with clean water, drying it in an oven at 80°C, and then mixing and reacting it with an acidic solution. The acidic solution is obtained by slowly adding 98% concentrated sulfuric acid to an equal volume of deionized water while continuously stirring and cooling to 25±5°C. The mass-to-volume ratio of the waste rubber powder to the acidic solution is 1.4 g / mL. After soaking for 4 hours, the mixture is filtered, washed with deionized water until neutral, and then vacuum dried at 75±5°C. The rubber powder is then mixed and reacted with a phytic acid solution. The phytic acid solution is obtained by mixing 70 wt% phytic acid with deionized water at a volume ratio of 1:1. The mass-to-volume ratio of the waste rubber powder to the phytic acid solution is 1.7 g / mL. After soaking for 2 hours, the mixture is filtered, washed with deionized water until neutral, and then vacuum dried at 75±5°C to obtain the modified reclaimed rubber. The preparation method of the plasticized modified lignin is as follows: lignin, 1,2-propanediol, triethyl citrate and urea are mixed evenly in a mass ratio of 16:8.2:4.8:1.7, and then melt-extruded and granulated by a twin-screw extruder at a temperature of 70-105°C to obtain plasticized modified lignin. The insulating layer is made of low dielectric loss polypropylene material, which is composed of the following raw materials in parts by weight: Polypropylene resin: 70 parts Low-density polyethylene resin: 33 parts EPDM rubber: 14 parts 2,2'-Thiobis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]: 2.3 parts Polyethylene wax with a number average molecular weight of 4800: 0.4 parts.

[0035] Comparative Example 1 The difference between Comparative Example 1 and Example 6 is that ordinary silicone rubber, i.e., the same type of silicone rubber without surface amination modification, is used instead of silicone rubber containing amino groups on the surface. The other components are the same as in Example 6.

[0036] Comparative Example 2 The difference between Comparative Example 2 and Example 6 is that only an acidic solution is used in the preparation of the modified reclaimed rubber, while the other components are the same as in Example 6.

[0037] Comparative Example 3 The difference between Comparative Example 3 and Example 6 is that only phytic acid solution is used in the preparation of the modified reclaimed rubber, while the other components are the same as in Example 6.

[0038] Comparative Example 4 The difference between Comparative Example 4 and Example 6 is that waste rubber powder is used instead of modified recycled rubber, while the other components are the same as in Example 6.

[0039] Comparative Example 5 The difference between Comparative Example 5 and Example 6 is that no modified recycled rubber is added, while the other components are the same as in Example 6.

[0040] Comparative Example 6 The difference between Comparative Example 6 and Example 6 is that lignin is used instead of plasticized modified lignin, while the other components are the same as in Example 6.

[0041] Comparative Example 7 The difference between Comparative Example 7 and Example 6 is that no plasticized modified lignin is added, while the other components are the same as in Example 6.

[0042] Comparative Example 8 The difference between Comparative Example 8 and Example 6 is that no cerium oxide nanosheets or silicon dioxide nanosheets KH-550 are modified on the surface; the other components are the same as in Example 6.

[0043] Comparative Example 9 The difference between Comparative Example 9 and Example 6 is that cerium oxide nanosheets are not added, while the other components are the same as in Example 6.

[0044] Comparative Example 10 The difference between Comparative Example 10 and Example 6 is that silica nanosheets are not added, while the other components are the same as in Example 6.

[0045] Comparative Example 11 The difference between Comparative Example 11 and Example 6 is that silica nanosheets and cerium oxide nanosheets are not added, while the other components are the same as in Example 6.

[0046] Example of effect Table 1 below shows the performance analysis results of the cable sheath layer using Embodiments 1 to 6 of the present invention and Comparative Examples 1 to 11, and Table 2 below shows the performance analysis results of the cable insulation layer using Embodiments 1 to 6 of the present invention.

[0047] Table 1

[0048] Table 2

[0049] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A low dielectric loss flexible cable, comprising, from the outside to the inside, an outer sheath layer, an outer shielding layer, a foam buffer layer, and a cable core, characterized in that, The cable core includes six insulated wire cores twisted together around a central axis. Each insulated wire core includes a conductor, an insulation layer covering the conductor, an inner sheath layer covering the insulation layer, and an inner shielding layer covering the inner sheath layer. Both the inner and outer sheath layers are made of flexible rubber material, which is composed of the following raw materials in parts by weight: 20-25 parts of amino-containing silicone rubber, 20-25 parts of modified recycled rubber, 6-10 parts of plasticized modified lignin, 1-5 parts of cerium oxide nanosheets, 1-5 parts of silica nanosheets, 0.3-0.4 parts of sulfur, and 1.9-2.5 parts of accelerator CZ.

2. The low dielectric loss flexible cable according to claim 1, characterized in that, The amino-containing silicone rubber on the surface is methyl vinyl silicone rubber with particles of 0.1-1 mm in diameter, which is modified by immersing in a toluene solution of KH-550.

3. The low dielectric loss flexible cable according to claim 1, characterized in that, The modified recycled rubber is obtained by treating waste rubber powder with acid twice, wherein the first acid soaking treatment is an acidic solution and the second acid soaking treatment is a phytic acid solution.

4. A low dielectric loss flexible cable according to claim 1, characterized in that, The acidic solution is obtained by mixing concentrated sulfuric acid with a mass concentration of 98% and deionized water at a volume ratio of 1:1, and the phytic acid solution is obtained by mixing 70wt% phytic acid and deionized water at a volume ratio of 1:

1.

5. A low dielectric loss flexible cable according to claim 1, characterized in that, The preparation method of the plasticized modified lignin is as follows: lignin, 1,2-propanediol, triethyl citrate and urea are mixed evenly in a mass ratio of (10~20):(8~12):(4~6):(1~2), and then melt-extruded and granulated by a twin-screw extruder at a temperature of 70~105℃.

6. A low dielectric loss flexible cable according to claim 1, characterized in that, Both the cerium oxide nanosheets and the silicon dioxide nanosheets were surface-modified with KH-550.

7. A low dielectric loss flexible cable according to claim 1, characterized in that, The insulating layer is made of low dielectric loss polypropylene material, which is composed of the following raw materials in parts by weight: 50-100 parts polypropylene resin, 25-40 parts low density polyethylene resin, 5-20 parts EPDM rubber, 1.2-2.5 parts antioxidant, and 0.3-0.8 parts lubricant.

8. A low dielectric loss flexible cable according to claim 1, characterized in that, Both the outer and inner shielding layers are made of silver-plated copper wire braiding with a braiding density of ≥90%.

9. A low dielectric loss flexible cable according to claim 1, characterized in that, The foam buffer layer is made of polyethylene foam material with a thickness of 1-2 mm.

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