Polytetrafluoroethylene wrapped high temperature resistant cable

Abstract

The application relates to the technical field of cables, and particularly discloses a polytetrafluoroethylene (PTFE) high-temperature-resistant cable, which comprises a conductor and a PTFE composite film layer wrapped around the conductor, the PTFE composite film is composed of three PTFE single-layer films with different dielectric constants, the dielectric constants of the PTFE single-layer films from inside to outside are sequentially reduced, the difference between the dielectric constants of adjacent layers is less than or equal to 0.4, and the PTFE single-layer film is a PTFE film doped with nanoparticles. Through gradient dielectric design and nanoparticle doping, the problems of signal reflection, phase distortion and high-temperature stability of the traditional PTFE wrapped cable in high-frequency transmission are solved, and the cable has high-frequency performance and high-temperature resistance.

Description

Technical Field

[0001] This invention relates to the field of cable technology, and in particular to a polytetrafluoroethylene-wrapped high-temperature resistant cable. Background Technology

[0002] Polytetrafluoroethylene (PTFE) is widely used in cable insulation and wrapping structures due to its excellent high-temperature resistance, chemical stability, and low dielectric loss. However, existing technologies have the following limitations: Traditional PTFE wrapping layers are prone to abrupt changes in interlayer dielectric constant at millimeter-wave frequencies due to process limitations, leading to signal reflection and phase distortion. For example, conventional wrapped cables have an insertion loss exceeding 0.5 dB / m and a phase consistency deviation greater than 5° at 60 GHz. Moreover, most PTFE wrapped cables improve high-temperature resistance by adding inorganic fillers, but do not control dielectric properties. Furthermore, traditional wrapping processes result in weak interlayer bonding, making it difficult to eliminate air gaps.

[0003] Existing technologies focus on high temperature resistance, mechanical protection, or surface smoothness, neglecting dielectric uniformity in high-frequency signal transmission. Especially in scenarios such as 5G signal stations and satellite communications, cables cannot simultaneously meet the requirements of high temperature resistance and high-frequency signal fidelity. Summary of the Invention

[0004] In view of this, the present invention proposes a polytetrafluoroethylene-wrapped high-temperature resistant cable with good signal fidelity performance.

[0005] The technical solution of the present invention is implemented as follows: The present invention provides a polytetrafluoroethylene (PTFE) wrapped high-temperature resistant cable, which includes: a conductor and a PTFE composite film layer wrapped around the conductor. The PTFE composite film is obtained by combining three PTFE monolayer films with different dielectric constants. The dielectric constant of the PTFE monolayer films decreases sequentially from the inside to the outside, and the difference in dielectric constant between adjacent layers is ≤0.4. The PTFE monolayer film is a PTFE film doped with nanoparticles.

[0006] In the above embodiments, a composite film is obtained by combining three PTFE monolayer films from the inside out, with the dielectric constants of the three monolayer films decreasing sequentially, and the difference in dielectric constant between adjacent layers ≤0.4. When electromagnetic waves propagate from a high dielectric layer to a low dielectric layer, the abrupt change in dielectric constant can cause interface reflection. Gradient design achieves impedance gradient matching through a small dielectric difference (≤0.4), significantly reducing the reflectivity of high-frequency signals (30-100GHz) (return loss <-30dB). Traditional cables suffer from signal phase delay differences due to abrupt changes in dielectric constant between layers, while the gradient structure improves phase consistency by homogenizing the electromagnetic wave propagation path (measured phase deviation <2°).

[0007] In some embodiments, the nanoparticles are nano-silica or nano-titanium dioxide with a particle size of 10-50 nm.

[0008] Doping with nano-silica / titanium dioxide can adjust the polarization characteristics of PTFE, optimizing the dielectric constant and loss factor through the interfacial polarization effect.

[0009] In some embodiments, the surface of the nanoparticles is modified with a silane coupling agent.

[0010] Meanwhile, the nanoparticles, as physical cross-linking points, restrict the free movement of PTFE molecular chains at high temperatures and delay thermal decomposition. In the above embodiments, the modified nanoparticles can be applied only to the inner layer, middle layer, or outer layer, or to two or three of them.

[0011] In some embodiments, the dielectric constant of the inner polytetrafluoroethylene monolayer film is 2.5-2.8, the dielectric constant of the middle polytetrafluoroethylene monolayer film is 2.2-2.5, and the dielectric constant of the outer polytetrafluoroethylene monolayer film is 1.9-2.2.

[0012] In some embodiments, the concentration of nanoparticles in the inner polytetrafluoroethylene monolayer film is 7 wt%, the concentration of nanoparticles in the middle polytetrafluoroethylene monolayer film is 4 wt%, and the concentration of nanoparticles in the outer polytetrafluoroethylene monolayer film is 0.4 wt%.

[0013] High-concentration nanoparticles increase the dielectric constant of the inner layer, enhancing electromagnetic coupling efficiency with the conductor. Low-concentration nanoparticles maintain the low dielectric properties of the PTFE matrix, reducing dielectric loss in high-frequency signal transmission. The nanoparticle concentration decreases from the inner layer to the outer layer (7wt%→0.4wt%), synergizing with the dielectric gradient to avoid abrupt changes in interlayer dielectric properties.

[0014] In some embodiments, the thickness ratio of the inner polytetrafluoroethylene monolayer film: the middle polytetrafluoroethylene monolayer film: the outer polytetrafluoroethylene monolayer film is 1:(0.8-1):(0.6-0.8).

[0015] A thicker inner layer enhances the conductor shielding effect, while a thinner outer layer reduces the total dielectric thickness, lowers the overall capacitance, and improves the signal transmission rate.

[0016] In some embodiments, the wrapping overlap rate of the polytetrafluoroethylene composite film layer is 30%-50%, and the angle between the wrapping direction and the cable axis is 15-30°.

[0017] The spiral wrapping angle affects the distribution of the cable's equivalent dielectric constant. Simulation verification shows that an angle of 15°-30° ensures a uniform electric field distribution between the wrapping layers, avoiding the risk of breakdown caused by localized field strength concentration. An overlap rate of 30%-50% ensures that the contact area between the wrapping layers is ≥70%, and combined with vacuum hot pressing, it improves the interlayer peel strength.

[0018] Secondly, the present invention also provides a method for preparing the above-mentioned polytetrafluoroethylene-wrapped high-temperature resistant cable, comprising the following steps:

[0019] Step 1: Form a polytetrafluoroethylene composite film layer through a co-extrusion process;

[0020] Step 2: Pre-sinter the polytetrafluoroethylene composite film at 350-380℃ for 10-30 minutes;

[0021] Step 3: Under a vacuum of ≤10Pa, spirally wrap the pre-sintered polytetrafluoroethylene composite film to the outside of the conductor, and simultaneously perform hot pressing.

[0022] Step 4: Heat to 375-385℃ and hold for 20 minutes, heat to 395-405℃ and hold for 15 minutes, heat to 355-365℃ and hold for 25 minutes, and then cool to obtain a polytetrafluoroethylene-wrapped high-temperature resistant cable.

[0023] In step four above, the heating and cooling rates are both controlled at 2-5℃ / min.

[0024] Pre-sintering allows for the directional alignment of molecular chains, enabling interlayer bonding at lower hot-pressing temperatures and reducing energy consumption. Simultaneous hot-pressing during spiral wrapping in a vacuum environment eliminates interlayer gaps.

[0025] The first stage mainly achieves the sliding and reorganization of molecular chains in the amorphous region to fill the interlayer micropores. The second stage involves melting of the crystalline region, with nanoparticles diffusing and migrating in the molten PTFE to form a uniformly dispersed "particle-matrix" network, reducing the range of dielectric constant fluctuations. The third stage involves slow cooling to allow the molecular chains to arrange themselves in an orderly manner, reducing residual stress and avoiding the risk of delamination at high temperatures.

[0026] In some implementations, the wrapping speed is ≤5m / min.

[0027] In some embodiments, the hot-pressing temperature is 190-230°C, and the hot-pressing pressure is 0.5-1.2 MPa.

[0028] The present invention has the following advantages over the prior art:

[0029] This invention solves the problems of signal reflection, phase distortion and high-temperature stability in traditional PTFE-wrapped cables during high-frequency transmission by using gradient dielectric design and nanoparticle doping, thus combining high-frequency performance with high-temperature resistance. Detailed Implementation

[0030] 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 a part of the embodiments of the present invention, and not all of the 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.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of this invention pertain. If any definition stated in this section is contrary to or otherwise inconsistent with a definition stated in a patent, patent application, published patent application, or other publication incorporated herein by reference, the definitions listed here shall prevail over those incorporated herein by reference.

[0032] Unless otherwise specified, the methods used in the following embodiments are conventional methods. Unless otherwise specified, the materials, reagents, and instruments used are conventional materials, reagents, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0033] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1 to 5” is disclosed, the described range should be interpreted as including ranges “1 to 4”, “1 to 3”, “1 to 2”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range. In this specification and claims, range definitions may be combined and / or interchanged, unless otherwise stated, these ranges include all subranges contained therein.

[0034] In the following examples and comparative examples, the conductors used are all annealed copper wires with a diameter of 0.5 mm.

[0035] Example 1

[0036] Step 1: A three-layer polytetrafluoroethylene (PTFE) composite film is formed through a co-extrusion process. The inner layer consists of PTFE + 7wt% nano-SiO2 (particle size 20nm, purity ≥99.9%); the middle layer consists of PTFE + 4wt% nano-SiO2 (particle size 30nm, purity ≥99.9%); and the outer layer consists of PTFE + 0.4wt% nano-SiO2 (particle size 15nm, purity ≥99.9%). The dielectric constant of the inner layer is 2.7; the dielectric constant of the middle layer is 2.3; and the dielectric constant of the outer layer is 2.0. The thickness ratio of the inner layer:middle layer:outer layer is 1:0.9:0.7, and the total thickness is 0.26mm.

[0037] Step 2: Pre-sinter the polytetrafluoroethylene composite film at 370℃ under nitrogen atmosphere for 20 minutes;

[0038] Step 3: Under a vacuum of ≤5Pa, spirally wrap the pre-sintered polytetrafluoroethylene composite film to the outside of the conductor. The wrapping angle is 20°, the wrapping overlap rate is 40%, and the wrapping speed is 3m / min. At the same time, hot pressing is performed at a temperature of 220℃, a pressure of 1.0MPa, and a time of 10min.

[0039] Step 4: Heat to 380℃ and hold for 20 minutes, then heat to 400℃ at 5℃ / min and hold for 15 minutes, then cool to 360℃ at 5℃ / min and hold for 25 minutes. After cooling, you will get a polytetrafluoroethylene wrapped high-temperature resistant cable.

[0040] Example 2

[0041] This embodiment is based on Embodiment 1, except that the amount of nano-silica used in each layer is different, and the dielectric constant is different, as detailed below.

[0042] Step 1: A three-layer polytetrafluoroethylene (PTFE) composite film is formed through a co-extrusion process. The inner layer consists of PTFE + 5wt% nano-SiO2 (particle size 20nm, purity ≥99.9%); the middle layer consists of PTFE + 3wt% nano-SiO2 (particle size 30nm, purity ≥99.9%); and the outer layer consists of PTFE + 0.4wt% nano-SiO2 (particle size 15nm, purity ≥99.9%). The dielectric constant of the inner layer is 2.5; the dielectric constant of the middle layer is 2.2; and the dielectric constant of the outer layer is 1.9. The thickness ratio of the inner layer:middle layer:outer layer is 1:0.8:0.6, and the total thickness is 0.24mm.

[0043] Step 2: Pre-sinter the polytetrafluoroethylene composite film at 370℃ under nitrogen atmosphere for 20 minutes;

[0044] Step 3: Under a vacuum of ≤5Pa, spirally wrap the pre-sintered polytetrafluoroethylene composite film to the outside of the conductor. The wrapping angle is 15°, the wrapping overlap rate is 30%, and the wrapping speed is 3m / min. At the same time, hot pressing is performed at a temperature of 190℃, a pressure of 0.5MPa, and a time of 10min.

[0045] Step 4: Heat to 380℃ and hold for 20 minutes, then heat to 400℃ at 5℃ / min and hold for 15 minutes, then cool to 360℃ at 5℃ / min and hold for 25 minutes. After cooling, you will get a polytetrafluoroethylene wrapped high-temperature resistant cable.

[0046] Example 3

[0047] This embodiment is based on Embodiment 1, except that it uses nano-titanium dioxide and undergoes silane modification treatment, as detailed below.

[0048] Step 1: A three-layer polytetrafluoroethylene (PTFE) composite film is formed through a co-extrusion process. The inner layer consists of PTFE + 8wt% nano-TiO2 (particle size 20nm, purity ≥99.9%); the middle layer consists of PTFE + 4wt% nano-TiO2 (particle size 30nm, purity ≥99.9%); and the outer layer consists of PTFE + 0.5wt% nano-TiO2 (particle size 15nm, purity ≥99.9%). The dielectric constant of the inner layer is 2.8; the dielectric constant of the middle layer is 2.5; and the dielectric constant of the outer layer is 2.2. The thickness ratio of the inner layer:middle layer:outer layer is 1:1:0.8, and the total thickness is 0.28mm.

[0049] Step 2: Pre-sinter the polytetrafluoroethylene composite film at 380℃ under nitrogen atmosphere for 10 minutes;

[0050] Step 3: Under a vacuum of ≤5Pa, spirally wrap the pre-sintered polytetrafluoroethylene composite film to the outside of the conductor. The wrapping angle is 20°, the wrapping overlap rate is 40%, and the wrapping speed is 3m / min. At the same time, hot pressing is performed at a temperature of 230℃, a pressure of 1.2MPa, and a time of 10min.

[0051] Step 4: Heat to 380℃ and hold for 20 minutes, then heat to 400℃ at 5℃ / min and hold for 15 minutes, then cool to 360℃ at 5℃ / min and hold for 25 minutes. After cooling, you will get a polytetrafluoroethylene wrapped high-temperature resistant cable.

[0052] Example 4

[0053] This embodiment is based on Example 1, keeping other conditions unchanged, except that the nano-silica used has not undergone modification treatment.

[0054] Example 5

[0055] This embodiment is based on Embodiment 1, keeping other conditions unchanged, except that there is no heat pressing treatment after wrapping.

[0056] Comparative Example 1

[0057] This comparative example uses a conventional single-layer undoped PTEF film with a total thickness of 0.26 mm and a dielectric constant of 2.1. It employs a conventional wrapping process with a wrapping angle of 20°, a wrapping overlap rate of 40%, and a wrapping speed of 3 m / min. After wrapping, it is sintered at 380°C for 60 min.

[0058] Comparative Example 2

[0059] The difference between this comparative example and Example 1 is that each of the three-layer polytetrafluoroethylene composite film has the same thickness and dielectric constant. They are all PTFE films doped with 5wt% nano-TiO2 (particle size 30nm, purity ≥99.9%), with a dielectric constant of 2.5 and a total thickness of 0.26mm.

[0060] The cables prepared above were tested for high-frequency performance, mechanical properties, and high-temperature stability, and the data results are shown in the table below:

[0061]

[0062] The dielectric loss tanδ and high-temperature stability fluctuation data for each embodiment and comparative example are shown in the table below:

[0063] Grouping Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Dielectric loss tanδ 0.0008 0.0009 0.0010 0.0015 0.0012 0.0003 0.0005 Dielectric loss fluctuation ±0.0001 ±0.0001 ±0.0001 ±0.0004 ±0.0003 ±0.0003 ±0.0002

[0064] A comparison of the data from Example 1 and Comparative Example 2 shows that the phase deviation in Example 1 was reduced by 77% compared to Example 2, demonstrating that gradient dielectric design plays a crucial role in the integrity of high-frequency signals.

[0065] A comparison of Example 1 and Example 4 shows that the unmodified nanoparticles led to an 87.5% increase in tanδ, indicating the inhibitory effect of the silane coupling agent on interfacial polarization.

[0066] Compared with Example 5, vacuum hot pressing reduced the air gap thickness from 8 μm to 2 μm and the partial discharge quantity from 55 pC to 3 pC, a reduction of 94%.

[0067] When conducting the 30GHz insertion loss test, Example 2 showed a value of 0.18, while Comparative Example 1 showed a value of 0.52, indicating that Example 2 was more efficient.

[0068] Example 3 shows that the dielectric fluctuation at 250°C does not exceed 0.07, which meets the high temperature resistance requirement, indicating that high concentrations of TiO2 are also feasible.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high temperature resistant cable wrapped with polytetrafluoroethylene, characterized in that, The polytetrafluoroethylene composite film layer is formed by three layers of polytetrafluoroethylene single-layer films with different dielectric constants, and the dielectric constants of the polytetrafluoroethylene single-layer films from inside to outside decrease in turn, and the difference in dielectric constant between adjacent layers is ≤0.4, the polytetrafluoroethylene single-layer film is a polytetrafluoroethylene film doped with nanoparticles, the nanoparticles are nanosilica or nanotitanium dioxide, the particle size is 10-50 nm, the surface of the nanoparticles is modified by a silane coupling agent, the concentration of the nanoparticles in the inner layer of the polytetrafluoroethylene single-layer film is 7wt%, the concentration of the nanoparticles in the middle layer of the polytetrafluoroethylene single-layer film is 4wt%, and the concentration of the nanoparticles in the outer layer of the polytetrafluoroethylene single-layer film is 0.4wt%, the dielectric constant of the inner layer of the polytetrafluoroethylene single-layer film is 2.5-2.8, the dielectric constant of the middle layer of the polytetrafluoroethylene single-layer film is 2.2-2.5, and the dielectric constant of the outer layer of the polytetrafluoroethylene single-layer film is 1.9-2.2, the thickness ratio of the inner layer of the polytetrafluoroethylene single-layer film to the middle layer of the polytetrafluoroethylene single-layer film to the outer layer of the polytetrafluoroethylene single-layer film is 1:(0.8-1):(0.6-0.8), and the preparation method comprises the following steps: Step one, forming a polytetrafluoroethylene composite film layer by co-extrusion process; Step two, pre-sintering the polytetrafluoroethylene composite film layer at 350-380℃ for 10-30min; Step three, spiral wrapping the pre-sintered polytetrafluoroethylene composite film layer outside the conductor in a vacuum degree ≤10Pa environment, and simultaneously performing hot pressing treatment, the hot pressing temperature is 190-230℃, and the hot pressing pressure is 0.5-1.2MPa; Step four, heating to 375-385℃ for 20min, heating to 395-405℃ for 15min, and heating to 355-365℃ for 25min, and then cooling to obtain a polytetrafluoroethylene wrapped high-temperature resistant cable. The wrapping overlap rate of the polytetrafluoroethylene composite film layer is 30%-50%, and the angle between the wrapping direction and the cable axis is 15-30°.

2. The polytetrafluoroethylene wrapped high temperature resistant cable of claim 1, wherein, The wrapping speed is ≤5m / min.

3. The polytetrafluoroethylene wrapped high temperature resistant cable of claim 1, wherein, ​

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