PPS polymer material monofilament cable and preparation method thereof

Abstract

The invention discloses a PPS polymer material monofilament cable and a preparation method thereof, and relates to the technical field of cables, the disclosed PPS polymer material monofilament cable comprises four groups of round core copper conductors arranged in a regular quadrangle shape, a filling layer and an insulating layer, the filling layer is composed of PPS and nano silicon dioxide composite materials, and the insulating layer is composed of an insulating layer and an insulating layer. The filling layer is filled in gaps of the round core copper conductors, and the insulating layer is wrapped outside the filling layer by a PPS and PTFE blended material. The round core copper conductors are arranged in a regular quadrangle shape, current distribution is optimized, the skin effect is reduced, and meanwhile a uniform supporting structure is provided for the filling layer. The filling layer is made of PPS and nano silicon dioxide composite materials, interface bonding is enhanced, and therefore the high temperature resistance and the mechanical strength of the monofilament cable are effectively improved. And the insulating layer is formed by coating a PPS and PTFE blended material outside the filling layer, so that the high-temperature stability of PPS is maintained, and the insulating layer is endowed with good corrosion resistance.

Description

Technical Field

[0001] This application relates to the technical field of cables, and particularly to a single-filament cable made of PPS polymer material and its manufacturing method. Background Art

[0002] In the field of new energy, single-filament cables are key components for connecting high-power devices, energy storage systems, and high-frequency electronic devices. In the prior art, single-filament cables are generally composed of a single copper conductor or aluminum conductor coated with traditional insulating materials such as polyethylene (PE) and polyvinyl chloride (PVC). However, these traditional insulating materials have disadvantages such as easy aging, decreased insulation performance, and poor flame resistance in high-temperature, high-humidity, or high-frequency electromagnetic field environments, making it difficult to meet the high-performance requirements for cables in the new energy field.

[0003] The above content is only used to assist in understanding the technical solution of this application, and does not represent an admission that the above content is prior art. Summary of the Invention

[0004] The main purpose of this application is to provide a single-filament cable made of PPS polymer material and its manufacturing method, aiming to improve the cable performance.

[0005] To achieve the above purpose, this application proposes a single-filament cable made of PPS polymer material, which is characterized by including:

[0006] Four groups of round-core copper conductors arranged in a regular quadrilateral;

[0007] A filling layer, composed of a composite material of PPS and nano-silica, filled in the gaps between the round-core copper conductors;

[0008] An insulating layer, coated with a blend material of PPS and PTFE outside the filling layer.

[0009] In one embodiment, the single diameter of the round-core copper conductor is 0.05 - 0.2 mm, the total cross-sectional area is 0.5 - 2.0 mm², and a silver layer is plated on the surface of the round-core copper conductor with a silver layer thickness of 1 - 3 μm.

[0010] In one embodiment, the mass percentage of nano-silica in the filling layer is 10% - 20%, and the particle size of nano-silica is 20 - 50 nm.

[0011] In one embodiment, the mass percentage of PTFE in the insulating layer is 5% - 15%, and the thickness of the insulating layer is 0.1 - 0.3 mm.

[0012] In one embodiment, 0.5% - 2% of antioxidant is further added to the insulating layer material, and the antioxidant is a phosphite or a hindered phenol compound.

[0013] In addition, to achieve the above object, the present application also proposes a preparation method for preparing a single-filament cable of the PPS polymer material, and the preparation method includes:

[0014] Drawing a copper wire rod into a round-core copper conductor with a diameter of 0.05 - 0.2 mm by a wire drawing machine, and performing annealing treatment under nitrogen protection, with an annealing temperature of 400 - 500 °C and a holding time of 10 - 20 minutes;

[0015] Immersing the annealed round-core copper conductor in a silver ammonia solution for electroplating, controlling the current density to be 0.5 - 1.5 A / dm², and the electroplating time to be 3 - 8 minutes to form a silver layer with a thickness of 1 - 3 μm;

[0016] Arranging four groups of silver-plated round-core copper conductors in a regular quadrilateral, fixing the spacing through a guiding die, and the spacing between adjacent conductors is 1.2 - 1.5 times the diameter of the conductor;

[0017] Adding a premix of PPS and nano-silica into a twin-screw extruder, melting and extruding at 180 - 220 °C, and coating it in the gaps between the arranged conductors to form a filling layer;

[0018] Adding a premix of PPS and PTFE into a single-screw extruder, melting and extruding at 280 - 320 °C and a pressure of 10 - 15 MPa, and coating it outside the filling layer to form an insulating layer;

[0019] Adopting a two-stage cooling system, first cooling with water to 80 - 100 °C, and then cooling with air to room temperature, and controlling the cooling rate to be 3 - 5 °C / s.

[0020] In one embodiment, in the step of adding the premix of PPS and nano-silica into the twin-screw extruder, melting and extruding at 180 - 220 °C, and coating it in the gaps between the arranged conductors to form a filling layer, the screw rotation speed of the twin-screw extruder is 80 - 120 rpm, the length-diameter ratio is 40:1, and the surface roughness Ra of the filling layer after extrusion is ≤ 1.6 μm.

[0021] In one embodiment, in the step of adding the premix of PPS and PTFE into the single-screw extruder, melting and extruding at 280 - 320 °C and a pressure of 10 - 15 MPa, and coating it outside the filling layer to form an insulating layer, the temperature of the feeding section of the single-screw extruder is set to 280 - 290 °C; the temperature of the compression section of the single-screw extruder is set to 300 - 310 °C; the temperature of the homogenizing section of the single-screw extruder is set to 310 - 320 °C; the temperature of the die head section of the single-screw extruder is set to 315 - 320 °C.

[0022] In one embodiment, in the step of adopting a two-stage cooling system, first cooling with water to 80 - 100 °C and then cooling with air to room temperature, with the cooling rate controlled at 3 - 5 °C / s, the water temperature in the water cooling tank is 10 - 25 °C, the air cooling wind speed is 5 - 8 m / s, and an axial tension is applied to the cable during the cooling process, with the tension value being 5 - 10 N.

[0023] In one embodiment, in the step of adding the PPS and nano-silica premix to a twin-screw extruder, melt-extruding at 180 - 220 °C, and coating it in the gaps between the arranged conductors to form a filling layer, and adding the PPS and PTFE premix to a single-screw extruder, melt-extruding at 280 - 320 °C under a pressure of 10 - 15 MPa and coating it outside the filling layer to form an insulating layer, the premixes are all subjected to vacuum drying treatment, with the drying temperature being 120 - 150 °C, the vacuum degree ≤ -0.08 MPa, and the drying time ≥ 4 hours.

[0024] The single-filament cable made of PPS polymer material in the technical solution of this application includes four groups of round-core copper conductors arranged in a regular quadrilateral. Compared with the traditional single conductor or disordered multi-conductor structure, this arrangement optimizes the current distribution, reduces the skin effect, and at the same time provides a uniform support structure for the filling layer. The single-filament cable made of PPS polymer material also includes a filling layer composed of a composite material of PPS and nano-silica, which is filled in the gaps between the round-core copper conductors. Since the phenylthioether structure (-S-aromatic ring-S-) in the main chain of PPS provides high-temperature anti-deformation ability through strong thioether bonds and rigid benzene rings, PPS itself has excellent thermal stability. And the thioether bond of PPS has strong electronegativity, which can form hydrogen bonds or electrostatic interactions with the hydroxyl groups (-Si-OH) on the surface of nano-silica, enhancing the interfacial bonding, thereby effectively improving the high-temperature resistance performance and mechanical strength of the single-filament cable. At the same time, the addition of nano-silica can also effectively improve the hardness and wear resistance of the PPS material and extend the service life of the cable. In addition, the single-filament cable made of PPS polymer material also includes an insulating layer formed by coating the outside of the filling layer with a blend material of PPS and PTFE. PTFE has excellent dielectric properties and can effectively prevent current leakage and improve the insulation performance of the cable. The blending of PPS and PTFE combines the advantages of the two materials, maintaining the high-temperature stability of PPS and endowing the insulating layer with good corrosion resistance. The single-filament cable made of PPS polymer material in this application and its preparation method significantly improve the comprehensive performance of the single-filament cable through its structural design and material selection, meeting the requirements for high-performance cables in the new energy field. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings here are incorporated into the specification and form a part of this specification, showing embodiments in line with this application, and are used together with the specification to explain the principles of this application.

[0026] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 It is a schematic flow chart provided by an embodiment of the preparation method of the present application.

[0028] The realization of the purpose, functional characteristics and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. Detailed implementation manners

[0029] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions of the present invention in combination with the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention.

[0030] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail. Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, that is, they are intended to include but not limited to. Unless otherwise clearly stated in the context, the expressions "a" and "an" used herein include plural referents. It should be noted that "first", "second", etc. are only for convenience of description and easy distinction, and cannot be understood as indicating or implying relative importance. The term "about" used herein means a range of ±20% of the subsequent value. In some embodiments, the term "about" means a range of ±10% of the subsequent value. In some embodiments, the term "about" means a range of ±5% of the subsequent value.

[0031] In the field of new energy, single-wire cables are key components for connecting high-power devices, energy storage systems and high-frequency electronic devices. In the prior art, single-wire cables are generally composed of a single copper conductor or aluminum conductor coated with traditional insulating materials such as polyethylene (PE) and polyvinyl chloride (PVC). However, these traditional insulating materials have disadvantages such as easy aging, decreased insulation performance and poor flame resistance in high-temperature, high-humidity or high-frequency electromagnetic field environments, and it is difficult to meet the high-performance requirements for cables in the new energy field.

[0032] To solve the above problems, the present application proposes a single-filament cable made of PPS polymer material, which includes four groups of round-core copper conductors arranged in a regular quadrilateral, a filling layer, and an insulating layer. The filling layer is composed of a composite material of PPS and nano-silica, and is filled in the gaps between the round-core copper conductors. The insulating layer is coated on the outside of the filling layer with a blend material of PPS and PTFE.

[0033] In this embodiment, the four groups of round-core copper conductors are arranged in a regular quadrilateral. Compared with the traditional single-conductor or disordered multi-conductor structure, this arrangement optimizes the current distribution, reduces the skin effect, and at the same time provides a uniform support structure for the filling layer. The filling layer is composed of a composite material of PPS (polyphenylene sulfide) and nano-silica, and is filled in the gaps between the round-core copper conductors. Since the phenylthioether structure (-S-aromatic ring-S-) in the main chain of PPS provides high-temperature deformation resistance through strong thioether bonds and rigid benzene rings, PPS itself has excellent thermal stability. Moreover, the thioether bonds of PPS have strong electronegativity and can form hydrogen bonds or electrostatic interactions with the hydroxyl groups (-Si-OH) on the surface of nano-silica, enhancing the interfacial bonding, thereby effectively improving the high-temperature resistance and mechanical strength of the single-filament cable. At the same time, the addition of nano-silica can also effectively improve the hardness and wear resistance of the PPS material and extend the service life of the cable. In addition, the single-filament cable made of PPS polymer material also includes an insulating layer formed by coating the outside of the filling layer with a blend material of PPS and PTFE (polytetrafluoroethylene). PTFE has excellent dielectric properties and can effectively prevent current leakage and improve the insulation performance of the cable. The blending of PPS and PTFE combines the advantages of the two materials, maintaining the high-temperature stability of PPS and endowing the insulating layer with good corrosion resistance. The single-filament cable made of PPS polymer material and its preparation method according to the present application significantly improve the comprehensive performance of the single-filament cable through its structural design and material selection, meeting the requirements for high-performance cables in the new energy field.

[0034] In a feasible implementation manner, the single diameter of the round-core copper conductor is 0.05 - 0.2 mm, the total cross-sectional area is 0.5 - 2.0 mm², and the surface of the round-core copper conductor is plated with a silver layer with a thickness of 1 - 3 μm.

[0035] It is understandable that traditional thick-diameter conductors (such as a single diameter > 0.3 mm) have an increased resistance due to the skin effect under high-frequency currents, resulting in a decrease in transmission efficiency, and a single thick conductor cannot balance the high current-carrying capacity and flexibility of the cable. In this application, copper wire can be drawn into round-core copper conductors with a diameter of 0.05 - 0.2 mm by a wire drawing machine, so as to disperse the total cross-sectional area into multiple thin conductors, increase the surface area, suppress the skin effect, and reduce the high-frequency resistance. At the same time, the total cross-sectional area of the four groups of thin conductors is 0.5 - 2.0 mm², which improves the flexibility through the dispersed arrangement of multiple thin conductors while ensuring the current-carrying capacity. In addition, by plating a silver layer with a thickness of 1 - 3 μm on the surface of the round-core copper conductor, the silver layer on the surface of the round-core copper conductor isolates copper from contact with air, significantly reducing the risk of resistance deterioration.

[0036] In a feasible implementation manner, the mass percentage of nano-silica in the filler layer is 10% - 20%, and the particle size of the nano-silica is 20 - 50 nm.

[0037] It is understandable that when the content of nano-silica is less than 10%, its strengthening effect on the filler layer is limited, and it is difficult to significantly improve the arc resistance and creep resistance; while exceeding 20% will cause a sharp increase in the material viscosity, making extrusion molding difficult and prone to interface defects. Nano-particles with a particle size of 20 - 50 nm have a high specific surface area, which can effectively increase the physical entanglement and chemical bonding with the PPS molecular chain, strengthen the structural stability of the filler layer, and at the same time avoid the agglomeration problem caused by van der Waals forces for too small particle size (< 20 nm), or the risk of stress concentration and interface peeling caused by too large particle size (> 50 nm). Therefore, in this application, by precisely controlling the content and particle size of nano-silica, the optimal effect is achieved while ensuring the balance between the mechanical strength and processing performance of the PPS-based composite material.

[0038] In a feasible implementation manner, the mass percentage of PTFE in the insulating layer is 5% - 15%, and the thickness of the insulating layer is 0.1 - 0.3 mm. When the addition amount of PTFE is within this range, it can not only effectively exert its excellent dielectric properties and corrosion resistance, but also maintain good physical and mechanical properties, avoiding insufficient mechanical strength caused by too thin an insulating layer or material waste and increased processing difficulty caused by too thick an insulating layer. The thickness design of the insulating layer takes into account both electrical insulation and the lightweight requirement of the overall cable.

[0039] Furthermore, 0.5% - 2% of antioxidant is added to the insulating layer material, and the antioxidant is a phosphite or a hindered phenol compound. The addition of phosphite or hindered phenol compounds can effectively capture free radicals generated by factors such as heat, light, and oxygen during the use of the cable, delay material aging, and improve the service life and long-term stability of the cable. The addition amount of the antioxidant is carefully selected to avoid negative impacts on the cable performance caused by excessive addition.

[0040] In this embodiment, the monofilament cable made of PPS polymer material includes four groups of round-core copper conductors arranged in a regular quadrilateral. Compared with the traditional single conductor or disordered multi-conductor structure, this arrangement optimizes the current distribution, reduces the skin effect, and at the same time provides a uniform support structure for the filling layer. The monofilament cable made of PPS polymer material also includes a filling layer composed of a composite material of PPS and nano-silica, which is filled in the gaps between the round-core copper conductors. Since the phenylene sulfide structure (-S-aromatic ring-S-) in the main chain of PPS provides high-temperature anti-deformation ability through strong sulfide bonds and rigid benzene rings, PPS itself has excellent thermal stability. Moreover, the sulfide bonds of PPS have strong electronegativity, which can form hydrogen bonds or electrostatic interactions with the hydroxyl groups (-Si-OH) on the surface of nano-silica, enhancing the interfacial bonding, thereby effectively improving the high-temperature resistance and mechanical strength of the monofilament cable. At the same time, the addition of nano-silica can also effectively improve the hardness and wear resistance of the PPS material and extend the service life of the cable. In addition, the monofilament cable made of PPS polymer material also includes an insulating layer formed by coating the outside of the filling layer with a blend material of PPS and PTFE. PTFE has excellent dielectric properties and can effectively prevent current leakage and improve the insulation performance of the cable. The blending of PPS and PTFE combines the advantages of the two materials, not only maintaining the high-temperature stability of PPS but also endowing the insulating layer with good corrosion resistance. The monofilament cable made of PPS polymer material and its preparation method in this application significantly improve the comprehensive performance of the monofilament cable through its structural design and material selection, meeting the requirements for high-performance cables in the new energy field.

[0041] This application also provides a preparation method for preparing the monofilament cable made of the PPS polymer material, referring to Figure 1 , the preparation method includes steps S100 to S600, where:

[0042] In step S100, the copper wire is drawn into a round-core copper conductor with a diameter of 0.05 - 0.2 mm by a wire drawing machine and annealed under nitrogen protection. The annealing temperature is 400 - 500 °C, and the holding time is 10 - 20 minutes.

[0043] In this embodiment, drawing the copper wire into a round-core copper conductor with a fine diameter and annealing it can effectively improve the flexibility and conductivity of the conductor. During the annealing process, nitrogen protection can prevent the copper conductor from oxidizing at high temperatures to avoid forming an oxide layer on the surface of the copper conductor, which affects the conductivity.

[0044] In this embodiment, the recrystallization starting temperature of copper is about 200 - 250 °C, but to completely eliminate the cold drawing processing stress, the recrystallization temperature range (300 - 450 °C) needs to be reached. An annealing temperature of 400 - 500 °C can ensure sufficient grain refinement (grain size 5 - 10 μm), restore the conductor conductivity to ≥100% IACS (International Annealed Copper Standard), and at the same time avoid grain coarsening (grain > 20 μm) and the risk of nitrogen protection failure caused by too high temperature (> 500 °C). The holding time of 10 - 20 minutes ensures that the heat evenly penetrates into the core of the conductor (when the diameter ≤ 0.2 mm, the heat conduction time is about 8 - 15 minutes), ensures a stress elimination rate ≥ 95%, and avoids energy waste and excessive grain boundary migration (the grain boundary energy increases, resulting in a 5% - 10% decrease in mechanical strength) caused by too long time (> 20 minutes).

[0045] Step S200, immerse the annealed round-core copper conductor in a silver ammonia solution for electroplating, control the current density at 0.5 - 1.5 A / dm², and the electroplating time at 3 - 8 minutes to form a silver layer with a thickness of 1 - 3 μm.

[0046] In this embodiment, immerse the annealed round-core copper conductor in a silver ammonia solution (containing 50 - 80 g / L silver nitrate and 100 - 150 mL / L ammonia water) for electroplating, use a titanium basket as the anode and the copper conductor as the cathode, control the current density at 0.5 - 1.5 A / dm² and the electroplating time at 3 - 8 minutes, and form a continuous and dense silver layer with a thickness of 1 - 3 μm on the conductor surface through ion migration. Since when the current density is lower than 0.5 A / dm², the deposition rate of silver ions is too slow (< 0.1 μm / min), it is easy to cause discontinuous plating (coverage rate < 90%); when it is higher than 1.5 A / dm², due to the aggravation of concentration polarization, the plating crystal grains are coarsened (grain size > 200 nm) and dendrites are generated (surface roughness Ra > 0.5 μm). The electroplating time of 3 - 8 minutes and the current density jointly control the thickness of the silver layer, ensuring that the deposition rate is stable at 0.3 - 0.5 μm / min, which can not only avoid pinhole defects caused by too short time (when the thickness < 1 μm, the porosity ≥ 5%), but also prevent the peeling of the too thick silver layer (> 3 μm) due to the increase of internal stress. The oxygen content on the surface of the obtained silver layer ≤ 0.5 at%, the contact resistance ≤ 0.02 Ω·mm² / m, which is 80% lower than that of bare copper, and the resistance change rate ≤ 3% after aging for 1000 hours in an 85 °C / 85% humidity environment, significantly improving the antioxidant property and high-frequency transmission stability of the conductor.

[0047] Step S300, arrange the four groups of silver-plated round-core copper conductors in a regular quadrilateral, fix the spacing through a guiding die, and the spacing between adjacent conductors is 1.2 - 1.5 times the diameter of the conductor.

[0048] In this embodiment, four groups of silver-plated round core copper conductors can be passed through a regular quadrilateral guiding die. The distance between the inner guide grooves of the die is adjusted to 1.2 - 1.5 times the diameter of the conductor (for example, for a conductor with a diameter of 0.1 mm, the distance between conductors is 0.12 - 0.15 mm). An axial tensile force of 5 - 10 N is applied through a tension roller to fix the position of the conductors, forming a symmetric and stable regular quadrilateral arrangement structure. When the distance between adjacent conductors is less than 1.2 times the diameter, the high-frequency electromagnetic coupling effect between adjacent conductors is enhanced, resulting in a decrease in signal integrity; when it is greater than 1.5 times, the filling layer material cannot fully cover the gap, reducing the mechanical support and arc resistance performance. The regular quadrilateral arrangement equalizes the current distribution. Compared with the traditional circular or disordered arrangement, the skin effect loss can be reduced by 40%. At the same time, the geometric symmetry reduces the capacitance imbalance caused by conductor displacement. The precise guide grooves and tension control of the guiding die ensure that the fluctuation of the conductor distance is ≤ ±3%, providing a uniform gap for the subsequent extrusion of the filling layer, thereby ensuring that the cable still maintains stable electrical performance when the bending radius ≤ 5D (D is the cable diameter).

[0049] Step S400: The PPS and nano-silica premix are added to a twin-screw extruder and melt-extruded at 180 - 220 °C to coat the gaps between the arranged conductors, forming a filling layer.

[0050] In this embodiment, since the melt viscosity is too high below 180 °C, resulting in a sharp increase in extrusion pressure and incomplete filling, and above 220 °C, it causes PPS thermal degradation and reduces the mechanical properties of the filling layer, so it is melt-extruded at 180 - 220 °C. The high-shear effect of the twin-screw can evenly disperse nano-silica in the PPS matrix, forming physical entanglement and hydrogen bond binding. The nano-particles fill the polymer defects, thereby improving the tensile strength and volume resistivity of the filling layer. During the extrusion process, the die head flow channel can be designed with a gradually changing cross-section to ensure that the melt flow rate is synchronized with the moving speed of the conductors, avoiding interlayer peeling or bubbles.

[0051] In a feasible implementation manner, in the step S400, the screw speed of the twin-screw extruder is 80 - 120 rpm, the length-diameter ratio is 40:1, and the surface roughness Ra of the filling layer after extrusion is ≤ 1.6 μm.

[0052] In this embodiment, when the rotational speed is lower than 80 rpm, the shearing force is insufficient, and the nano-silica is unevenly dispersed in the PPS matrix, resulting in a decrease in the mechanical strength of the filling layer (tensile strength < 40 MPa). When the rotational speed is higher than 120 rpm, significant heat generation due to shearing causes the breakage of PPS molecular chains, and the nano-particles agglomerate due to turbulence. The range of 80 - 120 rpm can balance the dispersibility and thermal stability to ensure the uniform distribution of nano-particles. If the aspect ratio is too small (such as 30:1), the residence time of the material is insufficient, and the mixing of PPS and nano-particles is not sufficient. An aspect ratio of 40:1 provides sufficient lengths for the melting section and the kneading section, allowing the material to experience a gradient temperature rise, ensuring the formation of chemical bonds between the hydroxyl groups on the surface of the nano-particles and the sulfonic acid groups of PPS, and avoiding local overheating and degradation. If the roughness is too high (Ra > 2 μm), micro-gaps will exist at the interface between the filling layer and the conductor, leading to partial discharge and reducing the arc resistance. A filling layer with a roughness Ra ≤ 1.6 μm can improve the bonding force with the insulating layer and suppress the high-frequency signal transmission loss.

[0053] In a feasible implementation manner, in step S400, the premix is subjected to vacuum drying treatment. The drying temperature is 120 - 150 °C, the vacuum degree ≤ -0.08 MPa, and the drying time ≥ 4 hours.

[0054] In this embodiment, the premix needs to be subjected to vacuum drying treatment to remove the moisture and volatiles in PPS and nano-silica, avoiding bubbles or interface delamination caused by water vaporization during the processing. The moisture absorption rate of PPS is about 0.05% - 0.1%, and the nano-silica has a large specific surface area and is more likely to adsorb moisture. The vaporization of moisture at the high extrusion temperature (> 280 °C) will cause melt foaming and reduce the density of the insulating layer. Vacuum drying reduces the boiling point of water, enabling the rapid removal of moisture at 120 - 150 °C while avoiding high-temperature oxidation. The drying time ≥ 4 hours ensures that the moisture diffuses from the interior of the material to the surface, preventing the "false drying" phenomenon (surface drying while residual moisture remains in the core). In this embodiment, this parameter combination balances the drying efficiency and the thermal stability of the material, ensuring the process stability of subsequent extrusion molding.

[0055] In step S500, the PPS and PTFE premix is added to a single-screw extruder and melt-extruded at 280 - 320 °C and a pressure of 10 - 15 MPa to coat the outside of the filling layer to form an insulating layer.

[0056] In this embodiment, the PPS and PTFE blend material has good melt fluidity in the temperature range of 280 - 320°C, ensuring that the insulating layer uniformly coats the filling layer without obvious defects. At the same time, a pressure of 10 - 15 MPa is beneficial to removing the gas in the melt, avoiding the formation of bubbles, and improving the density and electrical insulation performance of the insulating layer. The use of a single-screw extruder simplifies the extrusion process and improves production efficiency. During the extrusion process, the thickness of the insulating layer can be controlled by adjusting the screw speed and the feeding rate to ensure that it is within the range of 0.1 - 0.3 mm to meet the dual requirements of light weight and electrical insulation.

[0057] In a feasible implementation manner, in step S500, the temperature of the feeding section of the single-screw extruder is set to 280 - 290°C; the temperature of the compression section of the single-screw extruder is set to 300 - 310°C; the temperature of the homogenizing section of the single-screw extruder is set to 310 - 320°C; the temperature of the die head section of the single-screw extruder is set to 315 - 320°C.

[0058] In this embodiment, the temperature of the feeding section (280 - 290°C) is slightly higher than the melting point of PPS (280°C), which preliminarily melts the material and softens the PTFE particles, avoiding cold material blockage (feeding pressure ≤ 5 MPa), and at the same time preventing the pre-sintering of PTFE due to too high temperature (when > 300°C, PTFE particles bond and the dispersibility decreases). The temperature of the compression section (300 - 310°C) can increase the temperature to reduce the melt viscosity (from 1000 Pa·s to 400 Pa·s), enhance the shear effect, make PTFE fibrillate (fiber diameter 0.1 - 0.5 μm) and entangle with the PPS molecular chain, and improve the toughness of the insulating layer. The temperature of the homogenizing section (310 - 320°C) can further homogenize the melt and maintain the PTFE fiber morphology (decomposition temperature > 327°C). When the temperature exceeds 310°C, it improves the fluidity of PPS, ensures that the material fully fills the die cavity), and at the same time avoids excessive heating of PTFE and loss of lubricity. The temperature of the die head section (315 - 320°C) is slightly higher than that of the homogenizing section to compensate for the heat dissipation of the die head, maintain the melt fluidity, make the surface of the insulating layer smooth, and inhibit the residual stress caused by the temperature difference. In this way, it can be ensured that the insulating layer material maintains appropriate viscosity and fluidity during the extrusion process, realizes uniform coating without obvious defects. The design of the temperature gradient helps the full melting and mixing of the PPS and PTFE blend material, promotes the physical entanglement and chemical bonding between the two, and thus improves the overall performance of the insulating layer.

[0059] In a feasible implementation manner, in step S500, the premix is vacuum-dried, the drying temperature is 120 - 150°C, the vacuum degree ≤ -0.08 MPa, and the drying time ≥ 4 hours.

[0060] In this embodiment, the premix needs to be vacuum-dried to remove the moisture and volatiles in PPS and PTFE, avoiding bubbles or interfacial delamination caused by water vaporization during the processing. Vacuum drying reduces the boiling point of water, enabling rapid removal of moisture at 120 - 150°C while avoiding high-temperature oxidation. The drying time ≥ 4 hours ensures that the moisture diffuses from the interior of the material to the surface, preventing the phenomenon of "false drying" (surface drying while residual moisture remains in the core). In this embodiment, this parameter combination balances the drying efficiency and the thermal stability of the material, ensuring the process stability of subsequent extrusion molding.

[0061] Step S600: Adopt a two-stage cooling system. First, cool it with water to 80 - 100°C, and then cool it with air to room temperature. The cooling rate is controlled at 3 - 5°C / s.

[0062] In this embodiment, the design of the two-stage cooling system aims to rapidly and uniformly reduce the temperature of the extruded cable, preventing stress relaxation and shape deformation inside the material at high temperatures. During the water-cooling stage (80 - 100°C), the high thermal conductivity of water is utilized to quickly remove the heat from the cable surface, causing the cable temperature to rapidly drop to near the glass transition temperature (Tg ≈ 100°C) of the PPS and PTFE blend material. The cooling rate in this stage is relatively fast (4 - 5°C / s), which helps to maintain the shape stability of the extruded cable. Subsequently, it enters the air-cooling stage, cooling the cable to room temperature. The air-cooling rate is moderate (3 - 4°C / s) to avoid excessive residual stress generated inside the material due to too fast cooling rate, which may affect the flexibility and long-term service performance of the cable. The two-stage cooling system works together to ensure that the internal and external temperatures of the cable drop evenly during the cooling process, avoiding thermal stress concentration and shape distortion, while maintaining the excellent properties of the cable material.

[0063] In a feasible implementation manner, in step S600, the water temperature in the water-cooling tank is 10 - 25°C, the air-cooling wind speed is 5 - 8 m / s, and an axial tension is applied to the cable during the cooling process, with the tension value being 5 - 10 N.

[0064] In this embodiment, when the water temperature in the water cooling tank is lower than 10°C, it will cause sudden surface cooling, which may generate thermal stress cracks due to the excessive temperature difference between the inside and outside. When the temperature is higher than 25°C, the cooling rate is insufficient, resulting in coarsening of the internal grains of the material and a decrease in dielectric strength. Therefore, setting the water temperature in the water cooling tank to 10-25°C can quickly reduce the surface temperature of the cable, while avoiding embrittlement of the insulation layer caused by excessive crystallinity due to slow cooling of the molten PPS / PTFE. If the wind speed is too low, it will lead to insufficient heat dissipation in the core and cause secondary crystallization. If the wind speed is too high, it will cause surface supercooling and a large difference in shrinkage rate from the core, resulting in warping of the insulation layer. Therefore, setting the air cooling wind speed to 5-8 m / s can evenly and slowly cool the cable core, balance the crystallinity, and reduce residual stress. When the axial tension applied to the cable is insufficient, shrinkage will cause uneven insulation layer thickness and unbalanced capacitance distribution. When the axial tension applied to the cable is too large, it will stretch the conductor, resulting in microcracks in the silver plating layer and increasing the contact resistance. Therefore, applying an axial tension to the cable during the cooling process, with a tension value of 5-10 N, can offset the material shrinkage (the shrinkage rate of PPS / PTFE is 1-2%), maintain the straightness of the cable, and enhance the interfacial bonding force between the conductor and the insulation layer. In this embodiment, by quickly shaping the surface with water cooling, regulating the core structure with air cooling, and maintaining geometric stability with axial tension, the combination of the three makes the crystallinity of the insulation layer uniform and the residual stress low, ensuring that the cable does not crack during the thermal cycle from -40°C to 250°C.

[0065] In this embodiment, the single-filament cable made of PPS polymer material prepared by this preparation method includes four groups of round-core copper conductors arranged in a regular quadrilateral. Compared with the traditional single-conductor or disordered multi-conductor structure, this arrangement optimizes the current distribution, reduces the skin effect, and at the same time provides a uniform support structure for the filling layer. The single-filament cable made of PPS polymer material also includes a filling layer composed of a composite material of PPS and nano-silica, which is filled in the gaps between the round-core copper conductors. Since the phenylthioether structure (-S-aromatic ring-S-) in the main chain of PPS provides high-temperature anti-deformation ability through strong thioether bonds and rigid benzene rings, PPS itself has excellent thermal stability. Moreover, the thioether bonds of PPS have strong electronegativity and can form hydrogen bonds or electrostatic interactions with the hydroxyl groups (-Si-OH) on the surface of nano-silica, enhancing the interfacial bonding, thereby effectively improving the high-temperature resistance and mechanical strength of the single-filament cable. At the same time, the addition of nano-silica can also effectively improve the hardness and wear resistance of the PPS material and extend the service life of the cable. In addition, the single-filament cable made of PPS polymer material also includes an insulating layer formed by coating the outside of the filling layer with a blend material of PPS and PTFE. PTFE has excellent dielectric properties and can effectively prevent current leakage and improve the insulation performance of the cable. The blending of PPS and PTFE combines the advantages of the two materials, maintaining the high-temperature stability of PPS and endowing the insulating layer with good corrosion resistance. The single-filament cable made of PPS polymer material and its preparation method of the present application significantly improve the comprehensive performance of the single-filament cable through its structural design and material selection, meeting the requirements for high-performance cables in the new energy field.

[0066] The above are only some embodiments of the present application, and thus do not limit the patent scope of the present application. Any equivalent structural transformation made under the technical concept of the present application by using the content of the specification and drawings of the present application, or any direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. A monofilament cable made of PPS polymer material, characterized in that, Comprising: Four groups of round-core copper conductors arranged in a regular quadrilateral; A filling layer, composed of a PPS and nano-silica composite material, filled in the gaps between the round-core copper conductors; An insulating layer, coated with a PPS and PTFE blend material outside the filling layer.

2. The monofilament cable of the PPS polymer material according to claim 1, characterized in that, The single diameter of the round-core copper conductor is 0.05 - 0.2 mm, the total cross-sectional area is 0.5 - 2.0 mm², and the surface of the round-core copper conductor is plated with a silver layer, and the thickness of the silver layer is 1 - 3 μm.

3. The monofilament cable made of PPS polymer material as claimed in claim 1, wherein, The mass percentage of nano-silica in the filling layer is 10% - 20%, and the particle size of nano-silica is 20 - 50 nm.

4. The monofilament cable made of the PPS polymer material according to claim 1, characterized in that, The mass percentage of PTFE in the insulating layer is 5% - 15%, and the thickness of the insulating layer is 0.1 - 0.3 mm.

5. The monofilament cable made of the PPS polymer material according to claim 1, characterized in that, 0.5% - 2% of antioxidant is also added to the insulating layer material, and the antioxidant is a phosphite or hindered phenol compound.

6. A preparation method for preparing a monofilament cable of the PPS polymer material according to any one of claims 1 to 5, characterized in that, The preparation method includes: Drawing copper wire into a round-core copper conductor with a diameter of 0.05 - 0.2 mm by a wire drawing machine, and annealing it under nitrogen protection, the annealing temperature is 400 - 500 °C, and the holding time is 10 - 20 minutes; Immersing the annealed round-core copper conductor in silver ammonia solution for electroplating, controlling the current density to be 0.5 - 1.5 A / dm², and the electroplating time is 3 - 8 minutes to form a 1 - 3 μm silver layer; Arranging four groups of silver-plated round-core copper conductors in a regular quadrilateral, fixing the spacing through a guiding die, and the spacing between adjacent conductors is 1.2 - 1.5 times the conductor diameter; Adding a PPS and nano-silica premix to a twin-screw extruder, melting and extruding at 180 - 220 °C, and coating it on the gaps between the arranged conductors to form a filling layer; Adding a PPS and PTFE premix to a single-screw extruder, melting and extruding at 280 - 320 °C and a pressure of 10 - 15 MPa, and coating it outside the filling layer to form an insulating layer; Adopting a two-stage cooling system, first water-cooling to 80 - 100 °C, and then air-cooling to room temperature, and controlling the cooling rate to be 3 - 5 °C / s.

7. The method for preparing a single-filament cable according to claim 6, characterized in that, In the step of adding the PPS and nano-silica premix to the twin-screw extruder, melting and extruding at 180 - 220 °C, and coating it on the gaps between the arranged conductors to form a filling layer, the screw speed of the twin-screw extruder is 80 - 120 rpm, the length-diameter ratio is 40:1, and the surface roughness Ra of the filling layer after extrusion is ≤ 1.6 μm.

8. The preparation method of the monofilament cable according to claim 6, characterized in that, In the step of adding the PPS and PTFE premix to the single-screw extruder, melting and extruding at 280 - 320 °C and a pressure of 10 - 15 MPa, and coating it outside the filling layer to form an insulating layer, set the temperature of the feeding section of the single-screw extruder to 280 - 290 °C; set the temperature of the compression section of the single-screw extruder to 300 - 310 °C; set the temperature of the homogenizing section of the single-screw extruder to 310 - 320 °C; set the temperature of the die head section of the single-screw extruder to 315 - 320 °C.

9. The method for preparing a single-filament cable according to claim 6, characterized in that, In the step of adopting a two-stage cooling system, first water-cooling to 80 - 100 °C and then air-cooling to room temperature, with the cooling rate controlled at 3 - 5 °C / s, the water temperature in the water-cooling tank is 10 - 25 °C, the air-cooling wind speed is 5 - 8 m / s, and an axial tension is applied to the cable during the cooling process, with the tension value being 5 - 10 N.

10. The method for preparing a monofilament cable according to claim 6, characterized in that, In the steps of adding the PPS and nano-silica premix into a twin-screw extruder, melt-extruding at 180 - 220 °C, and coating it in the gaps between the arranged conductors to form a filling layer, and adding the PPS and PTFE premix into a single-screw extruder, melt-extruding at 280 - 320 °C under a pressure of 10 - 15 MPa, and coating it outside the filling layer to form an insulating layer, the premixes are all subjected to vacuum drying treatment, with the drying temperature being 120 - 150 °C, the vacuum degree ≤ -0.08 MPa, and the drying time ≥ 4 hours.

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