A composite insulated cable, its preparation method and application

Abstract

This invention discloses a composite insulated cable, its preparation method, and its application. The cable includes a conductor and a composite insulation layer, which comprises a fluoroplastic layer and a modified polyester elastomer layer. The modified polyester elastomer layer is prepared using thermoplastic polyester elastomer, silica aerogel, and benzoxazine resin prepolymer, and is manufactured through a process of extrusion followed by heat treatment curing. By optimizing the structure and composition of the cable insulation layer and controlling the production process, this invention achieves a comprehensive upgrade in the performance of various materials, giving the cable characteristics of high temperature resistance, low dielectric constant, low cost, and high flexibility, making it highly suitable for stable high-frequency data transmission.

Description

Technical Field

[0001] This invention belongs to the field of wire and cable technology, specifically relating to a composite insulated cable, its preparation method, and its application. Background Technology

[0002] In fields such as 5G communications, high-performance computing, and aerospace, the internal ambient temperature of equipment is rising daily, while the requirements for high-frequency data transmission are becoming increasingly stringent. Existing polyolefin or fluoroplastic insulated cables have limitations: polyolefins have insufficient heat resistance, typically below 105℃, and dielectric loss increases sharply at high temperatures; while fluoroplastics, although heat-resistant, typically have a relative dielectric constant of around 2.1, with limited room for further reduction, and are also costly and difficult to process. In existing technologies, insulated cables made from a single material or simple blends are difficult to operate stably at temperatures of 150℃ and above for extended periods, and also struggle to maintain excellent and stable high-frequency dielectric properties, such as low dielectric constant and low loss factor. Summary of the Invention

[0003] The purpose of this invention is to provide a composite insulated cable, its preparation method, and its application, so as to solve at least one aspect of the problems and defects mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A composite insulated cable includes a conductor and a composite insulation layer; The composite insulation layer includes a fluoroplastic layer and a modified polyester elastomer layer; The raw materials for preparing the modified polyester elastomer layer include thermoplastic polyester elastomer (TPEE), silica aerogel, and benzoxazine resin prepolymer.

[0005] As a further aspect of the present invention, the mass ratio of the thermoplastic polyester elastomer, silica aerogel and benzoxazine resin prepolymer is 100:5~15:3~10.

[0006] As a further aspect of the present invention, the Shore hardness of the thermoplastic polyester elastomer is D40~D55.

[0007] As a further aspect of the present invention, the thermoplastic polyester elastomer includes a hexamethyldisilazane-modified thermoplastic polyester elastomer.

[0008] As a further aspect of the present invention, the hexamethyldisilazane-modified thermoplastic polyester elastomer is prepared by the following method: Thermoplastic polyester elastomer is dissolved in toluene, and hexamethyldisilazane is added in an amount of 0.04 to 0.06 times the mass of the thermoplastic polyester elastomer. The mixture is reacted at 70 to 90 °C for 1 to 5 h to obtain hexamethyldisilazane modified thermoplastic polyester elastomer.

[0009] As a further embodiment of the present invention, the silica aerogel is a nanoporous silica aerogel powder with a particle size of 15~50μm, a pore size of 10~50nm, and a specific surface area of ​​200~1000m² / g.

[0010] As a further aspect of the present invention, the silica aerogel comprises hexamethyldisilazane modified silica aerogel.

[0011] As a further aspect of the present invention, the hexamethyldisilazane-modified silica aerogel is prepared by the following method: Silica aerogel is dispersed in toluene, and hexamethyldisilazane is added in an amount of 0.1 to 0.3 times the mass of the silica aerogel. The mixture is reacted at 70 to 90 °C for 1 to 5 h to obtain the hexamethyldisilazane-modified silica aerogel.

[0012] In a preferred embodiment of the present invention, by modifying the thermoplastic polyester elastomer with hexamethyldisilazane, hydrophobic groups are introduced to improve the hydrophobicity and moisture resistance of the TPEE matrix; at the same time, by modifying the silica aerogel with hexamethyldisilazane, the compatibility and dispersibility of the aerogel and the polyester elastomer can be improved, the uniformity and mechanical properties of the modified polyester elastomer layer can be improved, and the long-term stability of the insulation performance can be improved.

[0013] As a further embodiment of the present invention, the fluoroplastic layer has a foamed structure with a foaming degree of 30% to 50%.

[0014] As a further aspect of the present invention, the fluoroplastic is selected from at least one of polytetrafluoroethylene (PTFE) and fusible polytetrafluoroethylene (PFA).

[0015] As a further aspect of the present invention, the dielectric constant of the cable changes by less than 3% after being heated at 150~180°C for 1~1000 h, preferably less than 2%.

[0016] As a further aspect of the present invention, the loss factor change rate of the cable after heating at 150~180℃ for 1~1000 h is <6%, preferably <5%.

[0017] As a further aspect of the present invention, the characteristic impedance of the cable is 50Ω ±2Ω.

[0018] As a further aspect of the present invention, the dielectric constant of the cable is 1.8~2.1, preferably 1.87~1.95, under conditions of 25°C and 1GHz.

[0019] As a further aspect of the present invention, the cable has a loss factor of 0.0006~0.0015, preferably 0.0007~0.0011, under the conditions of 25°C and 1GHz.

[0020] As a further embodiment of the present invention, the thickness of the fluoroplastic layer is 0.5~0.8mm.

[0021] As a further embodiment of the present invention, the thickness of the modified polyester elastomer layer is 0.4~0.8 mm.

[0022] The method for preparing the composite insulated cable as described in any of the above includes the following steps: S1. A first wire core is obtained by covering the conductor with a fluoroplastic layer; S2. Cover the first core with a modified polyester elastomer layer to obtain the second core; S3. Heat-treat the second core to obtain the third core; S4. A shielding layer and an outer sheath are formed on the third conductor to obtain the composite insulated cable.

[0023] As a further aspect of the present invention, the processing temperature of the modified polyester elastomer layer in step S2 is 180~220℃. By precisely controlling the processing temperature, it is possible to ensure that the benzoxazine prepolymer is not completely cured, thus preserving its subsequent reactivity.

[0024] As a further embodiment of the present invention, the raw material composition for preparing the modified polyester elastomer layer in step S2 includes: 100 parts of thermoplastic polyester elastomer, 5-15 parts of silica aerogel, 3-10 parts of benzoxazine resin prepolymer, 1-5 parts of compatibilizer, 0.5-2 parts of antioxidant, and 0.5-1.5 parts of lubricant.

[0025] In the modified polyester elastomer layer, the huge specific surface area and nanoscale pores of silica aerogel can effectively adsorb and fix the polar ester bonds in the thermoplastic polyester elastomer chain segments, and introduce a large amount of air, thereby physically reducing the overall polarization ability and dielectric constant of the material.

[0026] During heat treatment, benzoxazine resin prepolymer undergoes ring-opening polymerization to form a dense thermosetting network. This network forms an interpenetrating polymer network with the flexible chains of thermoplastic polyester elastomer. On the one hand, this network restricts the thermal motion of thermoplastic polyester elastomer chain segments at high temperatures, inhibiting the increase in dielectric loss caused by dipole relaxation. On the other hand, it can significantly improve the heat distortion temperature and long-term thermal aging performance of the material.

[0027] The thermoplastic polyester elastomer matrix provides the necessary flexibility, processability and mechanical support for the entire system. The addition of compatibilizers ensures the uniform dispersion and strong interfacial bonding of nanoparticles in the matrix, avoiding the generation of new polarization centers or breakdown weaknesses due to interfacial defects.

[0028] Therefore, by combining thermoplastic polyester elastomer, silica aerogel and benzoxazine resin prepolymer in a specific ratio and process, the three properties of reducing dielectric constant, stabilizing high-temperature dielectric loss and improving heat resistance are simultaneously optimized. This effect cannot be achieved by single components or simple blending.

[0029] As a further aspect of the present invention, the compatibilizer is an epoxy-functionalized polyolefin.

[0030] As a further aspect of the present invention, the antioxidant is a mixture of hindered phenol and phosphite.

[0031] As a further aspect of the present invention, the lubricant is a silicone masterbatch, preferably with a silicone content of 50% to 55%.

[0032] As a further aspect of the present invention, the raw materials for preparing the benzoxazine resin prepolymer include bisphenol A, aniline, and paraformaldehyde.

[0033] As a further aspect of the present invention, the raw materials for preparing the benzoxazine resin prepolymer also include 3-aminopropyltriethoxysilane (APTES), hydroxyl-terminated polybutadiene (HTPB), polyvinyl methacrylate glycerol isobutylene copolymer, and KH-560 silane.

[0034] As a further aspect of the present invention, the heat treatment temperature in step S3 is 180~210℃. Under this heat treatment, the benzoxazine resin in the insulating outer layer undergoes a ring-opening polymerization crosslinking reaction, thereby ultimately fixing the material morphology and achieving performance improvement.

[0035] As a further embodiment of the present invention, the shielding layer in step S4 includes at least one of an aluminum-plastic tape layer and a tin-plated copper wire braided layer.

[0036] As a further embodiment of the present invention, the outer sheath in step S4 includes a PVC layer outer sheath.

[0037] As a further aspect of the present invention, the preparation method includes the following steps: S1. Wrap foamed fluoroplastic around the conductor to obtain the first wire core; S2. At 180~220℃, a modified polyester elastomer material is extruded onto the first core to obtain the second core; S3. The second core is subjected to heat treatment at 180~210℃ for 2~6 hours to obtain the third core; S4. A shielding layer is formed on the third conductor by braiding or wrapping, and then an outer sheath is formed by sheath extrusion to obtain the composite insulated cable.

[0038] As a further aspect of the present invention, step S2 further includes at least one of plasma treatment and silane coupling agent spraying.

[0039] As a further embodiment of the present invention, in step S2, the first wire core is first subjected to plasma treatment and then modified polyester elastomer material is extruded.

[0040] As a further aspect of the present invention, the gas atmosphere for plasma treatment is a mixture of N2 and O2.

[0041] As a further aspect of the present invention, the gas atmosphere for plasma treatment is N2 and O2 in a volume ratio of 9:1.

[0042] As a further embodiment of the present invention, the power of the plasma treatment is 150~250W and the treatment time is 1~10 min.

[0043] As a further embodiment of the present invention, in step S2, the first wire core is first subjected to plasma treatment, then coated with silane coupling agent, and finally extruded with a modified polyester elastomer layer.

[0044] As a further aspect of the present invention, the silane coupling agent is KH-560.

[0045] As a further aspect of the present invention, the concentration of the silane coupling agent is 3-7 wt%.

[0046] As a further aspect of the present invention, the amount of the silane coupling agent is 0.005 to 0.007 times the mass of the modified polyester elastomer material.

[0047] As a further aspect of the present invention, the silane coupling agent uses at least one of ethanol and water as a solvent.

[0048] As a further aspect of the present invention, step S2 includes: The first wire core was subjected to plasma treatment in an atmosphere of N2 and O2 gas, with a treatment power of 150~250W and a treatment time of 1~10 min; Then, a silane coupling agent solution with a concentration of 3-7 wt% is sprayed onto the surface, and the amount of silane coupling agent is 0.005-0.007 times the mass of the modified polyester elastomer material. The modified polyester elastomer material was extruded at 180~220℃ to obtain the second core.

[0049] In a preferred embodiment of the present invention, plasma treatment is used to introduce active groups on the surface of the fluoroplastic layer, and then a chemical bonding interface is formed between the first core and the second core using a silane coupling agent KH-560, thereby enhancing the bonding force between the fluoroplastic layer and the modified polyester elastomer layer and improving the overall performance of the cable.

[0050] The composite insulated cable or preparation method described above enables the application of composite insulated cables in high-frequency data transmission.

[0051] Compared with the prior art, the beneficial effects of the present invention include: The composite insulation layer structure formed by the low dielectric foamed insulation inner layer and the modified polymer insulation outer layer optimizes the overall performance of the cable. At the same time, the outer insulation material provides good mechanical strength, wear resistance and processing convenience, and has a greater cost advantage and flexibility than pure fluoroplastic cables. Introducing nanoporous silica aerogel into the outer insulating layer can effectively reduce the dielectric constant and loss factor of the insulating material; the later cross-linking of benzoxazine resin makes the network structure of the material more stable at high temperatures, ensuring the long-term stability of high-frequency signal transmission in cable environments of 150℃~200℃; the main insulating material TPEE provides basic flexibility and processability. The three are combined through compatibilizers and specific processes to solve the technical contradiction of difficulty in balancing high temperature resistance and low dielectric. During the manufacturing process, an extrusion followed by heat treatment and curing is adopted, which further optimizes the performance of the insulation material after molding, thereby achieving a comprehensive improvement in cable performance. This makes it very suitable for stable high-frequency data transmission. Attached Figure Description

[0052] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0053] Figure 1 This is a graph showing the analysis results of aging tests in an embodiment of the present invention. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments.

[0055] Therefore, the following detailed description of embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0056] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0057] In the following embodiments: Melt-resistant polytetrafluoroethylene (PFA): tensile strength (23℃) is 24~35 MPa, elongation at break (23℃) is 300~350%, and specific gravity is 2.12~2.17 g / cm³. 3 Dielectric constant (10 6 Hz) ≤2.1, dielectric loss (10 6 Hz) ≤1x10 -4 Melting point is 300~310℃, volatile matter ≤0.3%, Shore hardness is 50~60D, flame retardancy rating is V~0, limiting oxygen index (1.57mm) >95%; Polytetrafluoroethylene (PTFE): tensile strength ≥28 MPa, elongation ≥350%, bulk density 475±100 g / L, average particle size 650±250 µm, extrusion pressure (RR: 100:1) 5.5~14.0 MPa, melting point 327±5℃, standard relative density 2.140~2.190, thermal instability index 50; Thermoplastic polyester elastomer (TPEE): Shore hardness 45D, density 1.17 g / cm³ 3 The shrinkage rate is 0.7%, the tensile strength is 30 MPa, the tensile modulus is 98 MPa, the elongation at break is 600%, the tear strength is 120 KN / m, the flexural modulus is 118 MPa, and the melting point is 190℃. Silica aerogel is made of nanoporous silica aerogel powder with a thermal conductivity (25℃) ≤0.012-0.016 W / (M·K), a specific surface area of ​​600~800 m² / g, and a tap density of 60~120 kg / m³. 3 The particle size is 15~50μm, the pore size is 20~50nm, and the porosity is 90~95%; The compatibilizer is an ethylene-methyl acrylate-glycidyl methacrylate terpolymer, model number LOTADER. ® AX8900 has a methacrylate content of 24wt%, a glycidyl methacrylate content of 8wt%, a melt index (190℃ / 2.16kg) of 6g / 10min, a melting point of 65℃, and a density of 0.94g / cm³. 3 Vicat softening temperature <40℃, flexural modulus <30MPa, elongation at break 1100%, tensile strength at break 4MPa, particle size 5mm. The antioxidant is composed of hindered phenol and phosphite complex, model Irganox B215, with a bulk density of 530~630g / L, ash content of 0.1%, volatile matter ≤0.5%, pH value of 5.9, melting point of 116~179℃, flash point >150℃, thermal decomposition temperature >350℃, water solubility (23℃) <0.1g / L, and transmittance ≥96.0% at 425nm and ≥97.0% at 500nm. The lubricant is a silicone masterbatch, PE-based, containing 50% siloxane; Hydroxyl-terminated polybutadiene (HTPB): CAS No. 69102-90-5, hydroxyl value 1.00~1.40mmol / g, viscosity at 40℃ ≤5.0 Pa.s, peroxide mass fraction (as H2O2) ≤0.1%, moisture ≤0.1%, volatile matter ≤1%; Bisphenol A: CAS number 80-05-7; Aniline: CAS number 62-53-3; Paraformaldehyde: CAS number 30525-89-4; 3-Aminopropyltriethoxysilane (APTES): CAS No. 919-30-2; Polyvinyl methacrylate glycerol isobutylene copolymer: CAS No. 51541-08-3; KH-560 silane: CAS number is 2530-83-8; Hexamethyldisilazane (HMDS): CAS number 999-97-3.

[0058] Example 1 A composite insulated cable includes a conductor, a composite insulation layer, a shielding layer, and an outer sheath. The composite insulation layer includes an inner insulation layer and an outer insulation layer. The inner layer includes a fluoroplastic layer, and the outer layer includes a modified polyester elastomer layer.

[0059] The preparation method includes the following steps: S1. Inner insulation: The conductor is a single 0.5mm diameter silver-plated soft copper wire. Foamed fluoroplastic is extruded onto the conductor to form an insulating inner layer with a foaming degree of 40%, resulting in the first wire core with an outer diameter of 1.8mm. S2, Outer Insulation: Modified polyester elastomer material is extruded onto the first wire core to form an insulating outer layer. The extrusion die temperature is 200℃, resulting in a second wire core with an outer diameter of 3.0mm. S3. Heat curing: The second core is placed in a 190℃ circulating hot air oven for 4 hours to allow the benzoxazine resin in the modified polyester elastomer material to undergo ring-opening polymerization and cross-linking reaction, thereby fixing the material morphology and obtaining the third core. S4. Shielding and Sheath: The third core is wrapped with aluminum-plastic tape, braided with tinned copper wire (braiding density of 90%), and finally extruded with a flame-retardant PVC sheath to obtain a composite insulated cable.

[0060] In this embodiment: Fluoroplastics are made of meltable polytetrafluoroethylene (PFA). The modified polyester elastomer material is obtained by mixing the following raw materials by weight: 100 parts thermoplastic polyester elastomer, 10 parts silica aerogel, 6 parts benzoxazine resin prepolymer, 3 parts compatibilizer, 1 part antioxidant and 1 part lubricant. The benzoxazine resin prepolymer was prepared by the following method: 228.3 g of bisphenol A, 186.2 g of aniline, 120.0 g of paraformaldehyde and 500 mL of toluene were added sequentially to a reaction vessel, and the mixture was heated at 85 °C for 3 h under nitrogen protection, during which water generated was continuously removed through a water separator; after the reaction was completed, the temperature was lowered to 70 °C, and 22.1 g of 3-aminopropyltriethoxysilane (APTES) was added and reacted for 1 h; then the temperature was lowered to 50 °C, and 20.5 g of hydroxyl-terminated polybutadiene (HTPB), 11.2 g of polyvinyl methacrylate glycerol isobutylene copolymer and 1.12 g of KH-560 silane were added and the mixture was stirred for 20 min. After the reaction was completed, the solvent was removed by vacuum distillation to obtain the benzoxazine resin prepolymer.

[0061] Example 2 The difference from Example 1 is as follows: Fluoroplastics are made of polytetrafluoroethylene (PTFE). The modified polyester elastomer material is obtained by mixing the following raw materials by weight: 100 parts thermoplastic polyester elastomer, 5 parts silica aerogel, 10 parts benzoxazine prepolymer, 5 parts compatibilizer, 2 parts antioxidant and 1.5 parts lubricant.

[0062] Example 3 The difference from Example 1 is as follows: In step S1, the foaming degree is adjusted to 50%; In step S2, the outer diameter is adjusted to 3.5mm; In step S3, the temperature of the circulating hot air oven is adjusted to 210℃.

[0063] Example 4 The difference from Example 1 is as follows: Step S2 is replaced with: First, the first wire core is placed in a plasma processor for activation. The gas atmosphere is N2 to O2 volume ratio of 9:1, the processing power is 200W, and the processing time is 5 min. Then, spray a 5 wt% KH-560 silane coupling agent solution onto the surface. The solvent used is a 9:1 volume ratio of ethanol / water mixed solvent. The amount of KH-560 silane coupling agent is 0.006 times the mass of the modified polyester elastomer material. Let it air dry at room temperature for 10 minutes. Finally, the modified polyester elastomer material was extruded at a die temperature of 200℃ to obtain a second core with an outer diameter of 3.0mm.

[0064] Example 5 The difference from Example 1 is as follows: In the modified polyester elastomer materials, thermoplastic polyester elastomers are replaced with HMDS-modified thermoplastic polyester elastomers, and silica aerogels are replaced with HMDS-modified silica aerogels.

[0065] HMDS-modified thermoplastic polyester elastomer was prepared by the following method: thermoplastic polyester elastomer was added to dry toluene at a solid-liquid ratio of 1g:10mL, and heated to 80℃ under nitrogen protection while stirring to dissolve; hexamethyldisilazane was slowly heated dropwise at 0.05 times the mass of the thermoplastic polyester elastomer, and the reaction was carried out at 80℃ for 3 h; after the reaction was completed, the solvent was removed by vacuum distillation, and the product was dried under vacuum at 80℃ for 12 h to obtain HMDS-modified thermoplastic polyester elastomer.

[0066] HMDS-modified silica aerogel was prepared by the following method: Silica aerogel was added to dry toluene at a solid-liquid ratio of 1 g: 10 mL and ultrasonically dispersed for 30 min to form a suspension. Under nitrogen protection, hexamethyldisilazane (0.2 times the mass of silica aerogel) was slowly added dropwise and reacted at 80 °C for 4 h. After the reaction was completed, the mixture was centrifuged, washed three times with anhydrous ethanol, and vacuum dried at 80 °C for 12 h to obtain HMDS-modified silica aerogel.

[0067] Comparative Example 1 The difference from Example 1 is as follows: The mass fraction of silica aerogel in the modified polyester elastomer material was adjusted to 0 parts; In step S1, the foaming degree is adjusted to 80%.

[0068] Comparative Example 2 The difference from Example 1 is as follows: In the modified polyester elastomer material, the silica aerogel was adjusted to 20 parts and the benzoxazine resin prepolymer was adjusted to 0 parts. In step S3, the temperature of the circulating hot air oven is adjusted to 230℃.

[0069] Comparative Example 3 The difference from Example 1 is as follows: Replace silica aerogel with silica nanoparticles with a particle size D50 of 20 nm. In step S3, the temperature of the circulating hot air oven is adjusted to 170℃.

[0070] The composite insulated cables obtained in Examples 1-5 and Comparative Examples 1-3 are coaxial cables. Their performance was tested, and the results are shown in Table 1.

[0071] Table 1

[0072] The composite insulated cable samples obtained in Examples 1-5 and Comparative Examples 1-3 were placed in an oven at 200°C for thermal aging tests. Samples were removed from the oven every 24 hours. After cooling, insulation sheath slices were prepared and subjected to mechanical property testing at 23°C. The elongation at break was calculated, and the results are as follows: Figure 1 As shown in Table 2, the elongation at break after aging at 200℃ for 168 hours retains its elongation at break.

[0073] Table 2

[0074] The results show that the composite insulated cables obtained in Examples 1-5 have a characteristic impedance of 50Ω ±2Ω, a dielectric constant (1GHz) of 1.87~1.95 and a loss factor of 0.0007~0.0011 at 25℃, a dielectric constant change rate of <2% and a loss factor change rate of <5% at 1GHz after being kept at 180℃ for 1000 hours, and a breaking elongation retention rate of ≥89% after passing a long-term thermal aging test at 200℃×168h, which far exceeds the performance of conventional high-speed data cables.

[0075] In contrast, in Comparative Example 1, increasing the foaming degree of PFA to 80% led to the easy breakage of ester bonds in TPEE under long-term thermo-oxidative conditions, generating polar carbonyl groups, which resulted in an increase in the drift of dielectric constant and loss factor. Furthermore, excessive foaming also thinned the PFA cell walls, increasing the risk of local collapse and reducing the characteristic impedance of the cable. Simultaneously, due to the lack of the low dielectric and thermal insulation effects of silica aerogel, heat was concentrated in the TPEE phase, accelerating oxidation; after aging at 200 ℃ for 168 h, the elongation at break retention rate was only 75%.

[0076] In Comparative Example 2, the excessive amount of silica aerogel caused a sharp increase in the viscosity of the modified polyester elastomer material, making processing more difficult. Without the addition of benzoxazine resin prepolymer, the TPEE relied solely on physical entanglement, resulting in low crosslinking density and rapid molecular chain relaxation at high temperatures. To improve the degree of crosslinking, the hot air curing temperature was increased from 190℃ to 230℃, which resulted in partial thermal degradation of the hard segments of the TPEE, significantly increasing the material's brittleness. After 200℃×168h of heat aging, the elongation at break retention rate was only 68%.

[0077] In Comparative Example 3, silica nanoparticles were used to replace the aerogel in equal amounts. The high density of silanol groups on the particle surface made them prone to agglomeration and defect formation during production. These defects became rapid channels for oxygen and ion diffusion during thermo-oxidative aging. After 180℃ for 1000h, the dielectric constant drift and loss factor drift were significantly higher than those of the cable obtained in Example 1. At the same time, the density of interfacial microcracks increased, and the elongation at break retention rate dropped to 79% after aging at 200℃ for 168h, resulting in long-term reliability degradation.

[0078] In summary, this invention optimizes the structure and composition of the cable insulation layer and controls the production process to achieve a comprehensive upgrade of material performance, enabling the cable to possess characteristics of high temperature resistance, low dielectric constant, low cost, and high flexibility, making it highly suitable for stable high-frequency data transmission.

[0079] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A composite insulated cable, characterized in that, Includes conductors and composite insulation layers; The composite insulation layer includes a fluoroplastic layer and a modified polyester elastomer layer; The raw materials for preparing the modified polyester elastomer layer include thermoplastic polyester elastomer, silica aerogel, and benzoxazine resin prepolymer.

2. The composite insulated cable according to claim 1, characterized in that, The mass ratio of the thermoplastic polyester elastomer, silica aerogel, and benzoxazine resin prepolymer is 100:5~15:3~10; And / or, the thermoplastic polyester elastomer comprises a hexamethyldisilazane-modified thermoplastic polyester elastomer; And / or, the silica aerogel comprises hexamethyldisilazane modified silica aerogel; And / or, the foaming degree of the fluoroplastic layer is 30%~50%.

3. The composite insulated cable according to claim 1, characterized in that, The dielectric constant of the cable changes by less than 3% after being heated at 150-180℃ for 1-1000 hours. And / or, the loss factor change rate of the cable after heating at 150~180℃ for 1~1000 h is <6%.

4. The composite insulated cable according to claim 1, characterized in that, The dielectric constant of the cable is 1.8~2.1 at 25℃ and 1GHz. And / or, the cable has a loss factor of 0.0006~0.0015 at 25°C and 1GHz.

5. The composite insulated cable according to claim 1, characterized in that, The thickness of the fluoroplastic layer is 0.5~0.8mm; And / or, the thickness of the modified polyester elastomer layer is 0.4~0.8 mm.

6. The method for preparing the composite insulated cable according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. A first wire core is obtained by covering the conductor with a fluoroplastic layer; S2. Cover the first core with a modified polyester elastomer layer to obtain the second core; S3. Heat-treat the second core to obtain the third core; S4. A shielding layer and an outer sheath are formed on the third conductor to obtain the composite insulated cable.

7. The preparation method according to claim 6, characterized in that, The processing temperature of the modified polyester elastomer layer in step S2 is 180~220℃; And / or, step S2 further includes at least one of plasma treatment and silane coupling agent spraying; And / or, the heat treatment temperature in step S3 is 180~210℃.

8. The preparation method according to claim 6, characterized in that, The raw material composition for preparing the modified polyester elastomer layer in step S2 includes: 100 parts of thermoplastic polyester elastomer, 5-15 parts of silica aerogel, 3-10 parts of benzoxazine resin prepolymer, 1-5 parts of compatibilizer, 0.5-2 parts of antioxidant, and 0.5-1.5 parts of lubricant.

9. The preparation method according to claim 8, characterized in that, The raw materials for preparing the benzoxazine resin prepolymer include bisphenol A, aniline, and paraformaldehyde.

10. The composite insulated cable as described in any one of claims 1 to 5 or the preparation method as described in any one of claims 6 to 9, is used in high-frequency data transmission.

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