Metal wire polymer film micro-fused coating and stretching forming process

Abstract

This invention relates to the field of metal material processing technology. It discloses a method for micro-melting-coating and stretching a polymer film onto a metal wire, comprising the following steps: first, pre-treating the metal wire substrate to remove grease, impurities, and oxide layers to obtain a clean and activated substrate; then, conveying a polymer coating material to a coating die and bonding it to the substrate; next, applying high-frequency ultrasonic vibration to the coating die to cause localized micro-melting of the coating at the die opening, resulting in a tight adhesion to the substrate surface and forming an initial coating layer; subsequently, simultaneously stretching and sizing the metal wire with the initial coating layer while applying ultrasonic vibration to further bond the coating to the substrate and achieve a fixed coating thickness and wire diameter; then, performing low-temperature post-curing on the composite metal wire to densify the coating; finally, surface post-treatment to remove residual impurities, yielding the finished polymer insulating composite metal wire. This invention utilizes ultrasonic assistance to achieve molecular-level bonding between the coating and the metal wire, improving adhesion and reducing coating porosity.

Description

Technical Field

[0001] This invention relates to the field of metal material processing technology, and in particular to a process for micro-melting-coating and stretching metal wire polymer films. Background Technology

[0002] Polymer-insulated composite metal wires, with their excellent conductivity and insulation properties, are widely used in electronic component leads, precision equipment insulating electrode wires, low-voltage insulated cables, and many other fields. Their core manufacturing process involves integrated polymer coating and wire stretching and sizing. Currently, the mainstream process in the industry is the traditional method of integral hot-melt coating followed by direct stretching and sizing. This traditional process is simple to operate, requires no complex supporting control devices, and is suitable for basic industrial mass production needs. Therefore, it is commonly used in small and medium-scale production. However, due to limitations in its process principle, it suffers from many intractable technical defects in coating quality, metal substrate protection, and the overall performance of the finished product.

[0003] Traditional processes require heating the polymer material to a high temperature until it is completely melted before coating. High temperatures can alter the metallographic structure of the metal wire matrix, leading to a decrease in its tensile and flexural mechanical properties. Furthermore, the melting process generates numerous microbubbles, resulting in high coating porosity. The coating and metal substrate are only physically bonded, with low molecular-level adhesion and poor bonding strength, making them prone to peeling and edge curling during use. In addition, traditional processes lack coordinated control in the stretching, sizing, coating, and curing stages. The lack of energy assistance during stretching can cause internal stress in the coating, leading to cracking. The absence of constant tension during curing results in low dimensional accuracy and poor circumferential uniformity. The finished product exhibits poor aging resistance in humid and hot environments with varying temperatures and humidity. Moreover, the poor adaptability of process parameters makes it difficult to meet the processing requirements of metal wires of different materials and diameters, and it is no longer suitable for the high-quality requirements of composite metal wires in fields such as precision electronics and high-end equipment. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention discloses a metal wire polymer film micro-cladding-stretching forming process that can meet the processing needs of metal wires of different materials and diameters, and is suitable for the high-quality requirements of composite metal wires in fields such as precision electronics and high-end equipment.

[0005] This invention discloses a micro-cladding-stretching forming process for metal wire polymer films, which includes the following steps:

[0006] The first step is to pretreat the metal wire substrate to remove grease, impurities and oxide layer from the surface of the metal wire substrate, so as to obtain a clean and surface-activated metal wire substrate.

[0007] The second step is to transport the polymer coating material to the coating die, so that the polymer coating material can form a coating and bond with the clean metal wire substrate at the die.

[0008] The third step is to apply high-frequency ultrasonic vibration to the coating mold. The cavitation and thermal effects of the ultrasonic vibration cause the polymer coating material at the mold opening to form a local micro-melting state, allowing the micro-melting polymer coating material to adhere tightly to the surface of the metal wire substrate, forming a polymer initial coating layer.

[0009] The fourth step involves simultaneously stretching and sizing the metal wire with the initial polymer coating. During the stretching process, high-frequency ultrasonic vibration is applied in conjunction to further bond the micro-molten polymer coating to the metal wire substrate under the action of stretching force, thereby achieving the shaping of the coating thickness and the diameter of the metal wire.

[0010] The fifth step is to perform low-temperature post-curing treatment on the stretched and sized composite metal wire to allow the micro-molten polymer coating to complete curing and forming a dense polymer composite coating.

[0011] The sixth step is to perform surface post-treatment on the cured polymer insulating composite metal wire to remove residual impurities and obtain the finished metal wire.

[0012] Furthermore, the high-frequency ultrasonic vibration is applied in a contact manner, with the ultrasonic transducer fixedly connected to the outer wall of the coating mold, so that the ultrasonic vibration is transmitted through the mold to the polymer coating material and the metal wire substrate at the mold opening.

[0013] Furthermore, the frequency of the high-frequency ultrasonic vibration is 20-100kHz, the power of the ultrasonic vibration is 500-2000W, the amplitude of the ultrasonic vibration is 5-20μm, and the duration of ultrasonic vibration covers the entire process of micro-melting coating of polymer coating materials and stretching and sizing of metal wires.

[0014] The process also includes: setting an infrared temperature sensor at the mold opening to monitor the temperature of the bonding surface in real time, and dynamically adjusting the ultrasonic vibration power according to the temperature feedback to maintain the micro-melting temperature of the bonding surface at 50-350℃.

[0015] Furthermore, the polymer coating material is a thermoplastic polymer material, including at least one of polyimide, polyolefin, polytetrafluoroethylene, and nylon resin;

[0016] The polymer coating material is compounded in a mass ratio of polyimide to polyolefin of 1:10 to 10:1, and the compounded material meets the process characteristics of local micro-melting at the die opening.

[0017] Furthermore, the metal wire matrix is ​​one of steel wire, copper wire, aluminum wire, nickel alloy wire, or copper-nickel alloy wire, and the diameter of the metal wire matrix is ​​0.05-5mm.

[0018] Furthermore, the local micro-melting state of the polymer coating material is that the micro-melting area is limited to the bonding surface between the polymer coating and the metal wire substrate at the die opening, and the micro-melting temperature of the bonding surface is 50-350℃, and this temperature does not exceed the metallographic structure change temperature of the metal wire substrate.

[0019] Furthermore, the stretching speed of the synchronous stretching and sizing operation is 5-30 m / min, and the stretching force during the stretching process is 1-30 N; during the stretching process, the ultrasonic vibration power is reduced by 50-200 W according to the preset gradient for every meter the metal wire travels.

[0020] Furthermore, the low-temperature post-curing treatment is hot air circulation curing, with a curing temperature of 60-120℃ and a curing time of 10-40s. During the curing process, the metal wire is conveyed under constant tension, and the tension value is consistent with the tensile force in the stretching and sizing stage.

[0021] Furthermore, the surface post-treatment includes high-pressure cold air dust removal and coating appearance inspection. The wind speed of the high-pressure cold air is 1-5 m / s, and it is used only to blow away dust from the surface of the metal wire.

[0022] The appearance inspection of the coating must ensure that the polymer coating of the finished metal wire is free of pinholes, bubbles, and scratches, and the circumferential uniformity deviation of the coating is ≤0.1mm.

[0023] Furthermore, the polymer insulating composite metal wire prepared using this process has a bonding force between the polymer coating and the metal wire substrate of ≥15 N / mm². 2 The porosity of the polymer coating is ≤0.5%, and the finished metal wire has an aging resistance time of ≥1000h in a humid and hot environment with a temperature of -40-120℃ and a humidity of 85%, with no peeling, cracking, or powdering of the coating.

[0024] The beneficial effects of this invention are:

[0025] The high-frequency ultrasonic vibration-assisted micro-cladding-stretching forming process for polymer films using metal wires of this invention offers advantages in process implementation, effectively addressing many pain points of traditional coating processes. The process leverages the cavitation and localized thermal effects of high-frequency ultrasound to achieve molecular-level bonding between the polymer coating and the metal wire substrate, enhancing coating adhesion strength and eliminating microbubbles during the coating process, thus reducing coating porosity. The consistently low-temperature process design avoids damage to the metallographic structure and mechanical properties of the metal wire substrate caused by high temperatures. Gradient ultrasonic power control during stretching and sizing, along with constant tension delivery during the curing stage, effectively alleviates internal stress in the coating, preventing defects such as cracking and edge warping. Combined with closed-loop temperature control and process parameter settings, this ensures the stability and consistency of the entire process. Furthermore, the process requires no modification to existing production equipment; only a few auxiliary devices need to be added, resulting in low modification costs and suitability for continuous industrial production.

[0026] The polymer-insulated composite metal wire prepared by this process possesses excellent and comprehensive performance characteristics. The coating exhibits high adhesion to the metal substrate and extremely low porosity, resulting in a dense coating with excellent insulation and protective effects. The finished product demonstrates long-term aging resistance in a wide temperature range and high-humidity environments, with no peeling, cracking, or powdering of the coating, making it suitable for various complex working conditions. The coating exhibits good circumferential uniformity and high dimensional accuracy, and the process is adaptable to metal wire substrates of different materials and diameters. Applications cover a wide range of fields, including precision electronic component leads, insulated electrode wires, and low-voltage insulated cables. Compared to products prepared using traditional processes, the composite metal wire of this invention offers improved quality and stability, possessing outstanding market competitiveness and practical industrial application value. Attached Figure Description

[0027] Figure 1 This is a flowchart of a metal wire polymer film micro-cladding-stretching forming process in the embodiments of this application. Detailed Implementation

[0028] To enable those skilled in the art to better understand the present invention, the technical solutions in the specific embodiments of the present invention will be clearly and completely described below.

[0029] This invention discloses a micro-cladding-stretching forming process for metal wire polymer films, which includes the following steps:

[0030] The first step is to pretreat the metal wire substrate to remove grease, impurities and oxide layer from the surface of the metal wire substrate, so as to obtain a clean and surface-activated metal wire substrate.

[0031] The second step is to transport the polymer coating material to the coating die, so that the polymer coating material can form a coating and bond with the clean metal wire substrate at the die.

[0032] The third step is to apply high-frequency ultrasonic vibration to the coating mold. The cavitation and thermal effects of the ultrasonic vibration cause the polymer coating material at the mold opening to form a local micro-melting state, allowing the micro-melting polymer coating material to adhere tightly to the surface of the metal wire substrate, forming a polymer initial coating layer.

[0033] The fourth step involves simultaneously stretching and sizing the metal wire with the initial polymer coating. During the stretching process, high-frequency ultrasonic vibration is applied in conjunction to further bond the micro-molten polymer coating to the metal wire substrate under the action of stretching force, thereby achieving the shaping of the coating thickness and the diameter of the metal wire.

[0034] The fifth step is to perform low-temperature post-curing treatment on the stretched and sized composite metal wire to allow the micro-molten polymer coating to complete curing and forming a dense polymer composite coating.

[0035] The sixth step is to perform surface post-treatment on the cured polymer insulating composite metal wire to remove residual impurities and obtain the finished metal wire.

[0036] This process achieves the formation of a polymer insulating composite layer for metal wires through multi-step continuous collaborative operation. First, the metal wire substrate undergoes degreasing, impurity removal, and activation treatment to eliminate surface adhesion barriers, laying the foundation for tight adhesion between the polymer coating and the metal substrate. After the polymer coating material is conveyed to the coating die and bonded to the metal wire substrate, high-frequency ultrasonic vibration is applied to the coating die. The cavitation and thermal effects of the ultrasound induce localized micro-melting of the polymer coating material at the die, allowing the micro-molten polymer to form a preliminary tight bond with the metal substrate. Then, through simultaneous stretching and sizing operations combined with high-frequency ultrasonic vibration, the micro-molten coating further adheres to the metal wire substrate under tensile force, simultaneously defining the coating thickness and metal wire diameter. Subsequent low-temperature curing treatment allows the micro-molten polymer coating to achieve dense curing and shaping. Finally, surface post-treatment removes residual impurities, completing the preparation of the finished metal wire. All steps in the entire process are closely integrated, achieving a continuous, integrated operation of coating, forming, and curing.

[0037] The pretreatment activation process effectively improves the surface bonding performance of the metal wire substrate, avoiding the problem of poor coating adhesion caused by surface impurities. High-frequency ultrasonic vibration only achieves local micro-melting of the polymer coating at the die opening, which not only meets the molecular-level adhesion requirements between the coating and the substrate, but also avoids the damage to the metallographic structure and mechanical properties of the metal wire substrate caused by the high temperature of overall hot melting. The synergistic application of the stretching and sizing stage and high-frequency ultrasonic vibration ensures that the coating remains in close contact with the substrate throughout the shaping process, effectively alleviating the generation of internal stress in the coating during stretching. The low-temperature post-curing treatment ensures that the polymer coating is fully cured and dense, while avoiding the damage to the interface between the coating and the substrate caused by high-temperature curing. Subsequent surface post-treatment further ensures the surface quality of the finished metal wire. The process design of each step works together to produce a composite metal wire that combines strong coating adhesion, precise dimensions, and a clean surface.

[0038] In one implementation method, the high-frequency ultrasonic vibration is applied by contact, with the ultrasonic transducer fixedly connected to the outer wall of the coating mold, so that the ultrasonic vibration is transmitted through the mold to the polymer coating material and the metal wire substrate at the mold opening.

[0039] A contact application process is adopted to transmit high-frequency ultrasonic vibration. The ultrasonic transducer is directly fixed to the outer wall of the coating mold, so that the high-frequency vibration generated by the ultrasonic transducer is transmitted to the mold opening through the body of the coating mold in a mechanical transmission manner. The vibration energy is applied to the contact area between the polymer coating material and the metal wire substrate at the mold opening, realizing the direct transmission of vibration energy from the transducer to the process surface. Moreover, this application method can stably apply high-frequency ultrasonic vibration throughout the micro-melt coating and stretching sizing process, meeting the vibration coordination requirements of each stage of the process.

[0040] The contact-type ultrasonic vibration application method offers technological advantages. The direct, fixed connection reduces energy loss during transmission, allowing the cavitation and thermal effects of the ultrasound to fully act on the coating surface of the die, ensuring effective localized micro-melting of the polymer coating. Furthermore, this method requires no modification to the internal structure of the coating mold; simply fixing the vibrator to the outer wall of the mold is sufficient for the process upgrade. It is compatible with existing metal wire coating equipment, resulting in low modification costs and simple installation. In addition, the vibration is uniformly transmitted to the die opening through the mold body, ensuring uniform vibration at the contact area between the polymer coating and the metal wire substrate. This avoids uneven micro-melting caused by localized vibration, resulting in more uniform adhesion between the polymer coating and the metal wire substrate, laying a solid foundation for subsequent coating shaping.

[0041] As one implementation method, the frequency of high-frequency ultrasonic vibration is 20-100kHz, the power of ultrasonic vibration is 500-2000W, the amplitude of ultrasonic vibration is 5-20μm, and the duration of ultrasonic vibration covers the entire process of micro-melting coating of polymer coating material and stretching and sizing of metal wire.

[0042] The process also includes: setting an infrared temperature sensor at the mold opening to monitor the temperature of the bonding surface in real time, and dynamically adjusting the ultrasonic vibration power according to the temperature feedback to maintain the micro-melting temperature of the bonding surface at 50-350℃.

[0043] The process parameters for high-frequency ultrasonic vibration are defined, with the vibration frequency set between 20-100kHz, the ultrasonic vibration power controlled between 500-2000W, and the amplitude controlled between 5-20μm. This high-frequency ultrasonic vibration is continuously applied, fully covering the entire process of micro-melting coating of the polymer coating material and wire stretching and sizing. Simultaneously, an infrared temperature sensor is installed at the coating die to capture and monitor the temperature of the bonding surface between the polymer coating and the wire substrate in real time. The ultrasonic vibration power is dynamically adjusted based on the temperature monitoring feedback data to ensure that the micro-melting temperature of the bonding surface is consistently maintained within the process range of 50-350℃.

[0044] The process design's parameter settings and temperature control methods offer multiple advantages. The appropriate ultrasonic vibration parameters allow cavitation and thermal effects to act on the die-fitting surface, satisfying the energy requirements for localized micro-melting of the polymer coating without causing waste or process damage due to improper vibration parameters. The continuous vibration application ensures the consistency of process effects across the micro-melting coating and stretching / sizing stages. Real-time temperature monitoring and dynamic power adjustment at the die-fitting point form a closed-loop process control system. This effectively prevents excessive ultrasonic power from causing the bonding surface temperature to exceed limits, preventing over-melting and carbonization of the polymer coating or high-temperature effects on the metal wire substrate. It also eliminates insufficient micro-melting caused by insufficient power, ensuring the polymer coating remains in an ideal localized micro-melting state and providing stable process conditions for tight bonding between the coating and the metal wire substrate.

[0045] As one implementation method, the polymer coating material is a thermoplastic polymer material, including at least one of polyimide, polyolefin, polytetrafluoroethylene, and nylon resin;

[0046] The polymer coating material is compounded in a mass ratio of polyimide to polyolefin of 1:10 to 10:1, and the compounded material meets the process characteristics of local micro-melting at the die opening.

[0047] Thermoplastic polymer materials are selected as coating raw materials for metal wires. Specifically, one or more of polyimide, polyolefin, polytetrafluoroethylene, and nylon resin can be used in combination. Polyimide and polyolefin are compounded in a mass ratio of 1:10 to 10:1. During the compounding process, the local micro-melting process requirements at the die opening are taken into account. By adjusting the compounding ratio of the two materials, the mixed polymer coating material has the physical characteristics of being suitable for local micro-melting at 50-350℃. Under the action of the thermal effect and cavitation effect of ultrasonic vibration, a stable local micro-melting state is formed on the die opening bonding surface, while retaining the excellent properties of the material itself.

[0048] The selection and compounding of polymer coating materials offer significant advantages in terms of process and performance. The properties of thermoplastic polymers are highly compatible with the ultrasonic localized micro-melting process. After micro-melting, they can adhere tightly to the metal wire substrate and are easily shaped during subsequent stretching, sizing, and low-temperature curing, ensuring the dimensional accuracy of the coating. The wide range of compounding ratios of polyimide and polyolefin can be flexibly adjusted according to the material, diameter, and finished product requirements of the metal wire substrate. Combining the performance advantages of both materials allows the coating to possess excellent adhesion, aging resistance, and mechanical properties. Furthermore, by combining materials such as polytetrafluoroethylene (PTFE) and nylon resin, the insulation, wear resistance, and temperature resistance of the coating can be optimized as needed. The compounded materials are adapted to the process characteristics of localized micro-melting, avoiding problems such as insufficient micro-melting and weak adhesion due to excessively high melting points, and preventing over-melting and sagging due to excessively low melting points. This provides a raw material guarantee for the uniform forming and density of the coating.

[0049] In one embodiment, the metal wire substrate is one of steel wire, copper wire, aluminum wire, nickel alloy wire, or copper-nickel alloy wire, and the diameter of the metal wire substrate is 0.05-5mm.

[0050] The material and specifications of the metal wire substrate are clearly defined. Any one of steel wire, copper wire, aluminum wire, nickel alloy wire, or copper-nickel alloy wire can be selected as the substrate material for the forming process. The diameter of the metal wire substrate is controlled within the range of 0.05-5mm. The process parameters of each step, such as pretreatment, ultrasonic micro-melting, and stretching sizing, can be flexibly adapted according to the selected substrate material and actual diameter specifications. This allows metal wire substrates of different materials and diameters to be matched with this micro-melting cladding-stretching forming process, so as to complete the stable coating and forming of polymer coatings.

[0051] The selection and specification limitations of the metal wire substrate give the process excellent adaptability and practicality. In terms of materials, it covers commonly used metals and alloy wires with different performance requirements, such as conductivity, wear resistance, and corrosion resistance, meeting the substrate material requirements of various applications, including electronic component leads, precision insulated electrode wires, and low-voltage insulated cables. The wide diameter range of 0.05-5mm accommodates both fine-diameter metal wires for micro-precision devices and the processing needs of coarse-diameter metal wires for conventional industrial use, broadening the application scope of the process. At the same time, the fixed diameter range provides a clear control range for process parameter settings, allowing for more targeted parameter adjustments at each stage. This effectively avoids process control issues caused by excessive differences in substrate diameter, ensuring processing stability and product consistency for metal wire substrates of different specifications.

[0052] As one implementation method, the local micro-melting state of the polymer coating material is that the micro-melting area is limited to the bonding surface between the polymer coating and the metal wire substrate at the die opening, and the micro-melting temperature of the bonding surface is 50-350℃, and this temperature does not exceed the metallographic structure change temperature of the metal wire substrate.

[0053] By controlling the process, directional localized micro-melting of the polymer coating material is achieved. Relying on the energy-directional transmission characteristics of high-frequency ultrasonic vibration, the cavitation and thermal effects of the ultrasound are applied only to the bonding surface of the polymer coating and the metal wire substrate at the die opening. This strictly limits the micro-melting area to this bonding surface. At the same time, by using real-time temperature monitoring at the die opening and dynamic adjustment of ultrasonic power, the micro-melting temperature of the bonding surface is controlled between 50-350℃. Combined with the metallographic structure change characteristics of different metal wire substrates, this temperature range is always kept lower than the metallographic structure change temperature of the corresponding metal wire substrate. This achieves the process effect of micro-melting only at the bonding surface, while the coating surface and the metal wire substrate maintain their original state.

[0054] The micro-melting zone is limited to the bonding surface, avoiding problems such as sagging and uneven thickness caused by the overall melting of the polymer coating. This effectively maintains the initial morphology of the coating, laying the foundation for subsequent dimensional control during stretching and sizing. The low-temperature micro-melting range of 50-350℃ satisfies the molecular-level melting and bonding requirements of the polymer materials on the bonding surface, improving the tightness of the bond between the coating and the metal wire matrix. Furthermore, because the temperature does not exceed the metallographic transformation temperature of the metal wire matrix, it fundamentally avoids damage to the metallographic structure and mechanical properties of the metal wire matrix caused by high temperatures, fully preserving the original physical properties of the metal wire matrix. At the same time, low-temperature micro-melting also reduces the thermal degradation of the polymer materials, ensuring the excellent insulation and aging resistance properties of the coating material itself. This allows the finished composite metal wire to possess both stable matrix properties and a strong coating bond.

[0055] As one implementation method, the stretching speed of the synchronous stretching and sizing operation is 5-30 m / min, and the stretching force during the stretching process is 1-30 N; during the stretching process, the ultrasonic vibration power is reduced by 50-200 W according to a preset gradient for every 1 meter the metal wire travels.

[0056] Process parameters are set for the synchronous stretching and sizing of the metal wire, controlling the stretching speed at 5-30 m / min and maintaining the applied tensile force at 1-30 N to ensure smooth operation. High-frequency ultrasonic vibration is continuously applied during stretching, with the ultrasonic power adjusted gradient according to preset control rules. For every meter the metal wire travels, the ultrasonic vibration power is reduced by 50-200 W, synchronizing the ultrasonic power change with the wire's stretching progress. This adapts to the morphological changes and shaping requirements of the coating during stretching, achieving coordinated control of stretching, sizing, and ultrasonic vibration.

[0057] A stretching speed of 5-30 m / min and a stretching force of 1-30 N create a process range suitable for metal wires of different diameters. This ensures dimensional stability of the metal wire and coating while preventing deformation of the metal wire substrate or cracking and warping of the coating due to excessive stretching speed or force. It also prevents insufficient sizing accuracy and poor coating adhesion caused by excessively small parameters. The gradual reduction of ultrasonic power during stretching maintains a high ultrasonic power in the early stages, preserving the coating's micro-melting state and facilitating a tighter bond between the coating and the metal wire substrate under stretching force. Gradually decreasing the power in the later stages reduces the impact of vibration on the initially shaped coating, effectively alleviating internal stress during stretching. Simultaneously, it allows the coating to extend evenly with the metal wire, ensuring consistent coating thickness and circumferential uniformity, thus improving the dimensional accuracy and coating quality of the finished composite metal wire.

[0058] As one implementation method, the low-temperature post-curing treatment is hot air circulation curing, with a curing temperature of 60-120℃ and a curing time of 10-40s. During the curing process, the metal wire is kept under constant tension, and the tension value is consistent with the tensile force during the stretching and sizing stage.

[0059] The composite metal wire, after stretching and sizing, undergoes low-temperature post-curing using hot air circulation. The curing temperature is controlled within the range of 60-120℃, and the curing duration is set to 10-40 seconds. The heat transfer through hot air circulation ensures that heat is evenly distributed throughout the coating of the composite metal wire. Throughout the curing process, the composite metal wire is maintained under constant tension, with the tension value consistent with the tensile force applied during the stretching and sizing stage. This allows the metal wire to complete the curing and shaping of the micro-molten polymer coating under stable tension.

[0060] The low-temperature curing range of 60-120℃, combined with a curing time of 10-40 seconds, allows the micro-molten polymer coating to fully cross-link and cure, forming a dense polymer composite coating. This avoids thermal aging and embrittlement problems caused by prolonged high-temperature curing, while also preventing thermal stress at the interface between the coating and the metal wire substrate, ensuring the stability of the coating-substrate bond. The hot air circulation curing method ensures uniform heat coverage of the composite metal wire, eliminating defects such as uneven curing and edge curling caused by uneven heating. The constant tension delivery, consistent with the stretching and sizing stage, effectively maintains the dimensional accuracy of the composite metal wire, alleviates internal stress generated during coating curing, and prevents cracking and uneven shrinkage, resulting in a more regular coating morphology and higher dimensional consistency in the finished composite metal wire.

[0061] As one implementation method, the surface post-treatment includes high-pressure cold air dust removal and coating appearance inspection in sequence. The wind speed of the high-pressure cold air is 1-5m / s, and it is used only to blow away dust from the surface of the metal wire.

[0062] The appearance inspection of the coating must ensure that the polymer coating of the finished metal wire is free of pinholes, bubbles, and scratches, and the circumferential uniformity deviation of the coating is ≤0.1mm.

[0063] The cured polymer insulating composite metal wire undergoes a step-by-step surface post-treatment process. First, a high-pressure cold air dust removal operation is performed, with the air velocity controlled at 1-5 m / s. The blowing force of the high-pressure cold air acts on the surface of the metal wire to clean only the residual impurities on the surface of the metal wire. After dust removal, the coating appearance inspection operation is carried out. The coating condition of the composite metal wire is comprehensively inspected according to the established standards to ensure that the polymer coating of the finished metal wire is free of defects such as pinholes, bubbles, and scratches, and that the circumferential uniformity deviation of the coating is controlled within 0.1 mm.

[0064] A high-pressure cold air velocity of 1-5 m / s provides sufficient blowing force to effectively remove residual impurities adhering to the surface of the metal wire during production, ensuring the cleanliness of the finished product surface. However, excessive air velocity will not impact or damage the formed polymer coating, preventing secondary defects such as scratches and edge lifting. The sequence of dust removal followed by inspection ensures more accurate visual inspection results. Strict coating visual inspection standards effectively control the quality of finished products from the end of production, eliminating products with coating defects or substandard dimensional accuracy. This ensures that the finished metal wire coating is neatly formed and meets dimensional accuracy standards, improving overall product quality and batch consistency, making the finished product more suitable for various precision applications.

[0065] As one implementation method, the polymer insulating composite metal wire prepared using this process has a bonding force between the polymer coating and the metal wire substrate of ≥15 N / mm. 2 The porosity of the polymer coating is ≤0.5%, and the finished metal wire has an aging resistance time of ≥1000h in a humid and hot environment with a temperature of -40-120℃ and a humidity of 85%, with no peeling, cracking, or powdering of the coating.

[0066] The activation treatment of the substrate pretreatment lays the foundation for a tight bond between the coating and the substrate. The cavitation effect of high-frequency ultrasonic vibration breaks up microbubbles during the coating formation process, reducing the coating porosity. The local micro-melting effect of ultrasound achieves molecular-level adhesion between the coating and the substrate. Combined with gradient ultrasonic synergy during stretching and sizing and constant tension delivery during the curing stage, the bonding strength between the coating and the substrate is further improved. The low-temperature design of the entire process and the formation of a dense coating ensure that the finished metal wire maintains structural stability even under harsh temperature and humidity conditions, ultimately achieving a bonding strength between the coating and the metal wire substrate of no less than 15 N / mm. 2 The coating porosity is not higher than 0.5%, and the aging resistance time in a humid and hot environment of -40 to 120℃ and 85% humidity is not less than 1000 hours, with no peeling, cracking and powdering performance indicators.

[0067] The high bonding strength prevents peeling and curling of the coating from the metal substrate during use, ensuring the structural stability of the product. The extremely low coating porosity allows the coating to form a dense insulating protective layer, effectively improving the product's insulation and corrosion resistance, and eliminating media penetration problems caused by coating porosity. Long-lasting aging resistance under wide temperature and high humidity conditions allows the product to adapt to various complex operating conditions such as outdoor use, industrial workshops, and the interior of precision electronic equipment, overcoming the limitations of poor weather resistance in traditional composite metal wires. At the same time, stable performance indicators ensure batch consistency, meeting the large-scale application needs of multiple fields such as electronic component leads, precision insulated electrode wires, and low-voltage insulated cables.

[0068] Example

[0069] Example 1

[0070] (a) Test materials

[0071] Metal wire substrate: copper wire, 0.5mm in diameter;

[0072] Polymer coating material: thermoplastic material, polyimide:polyolefin = 1:5 (mass ratio), all of which are industrial grade pure materials.

[0073] (II) Process Steps

[0074] Pretreatment: The copper wire is degreased for 15 seconds in an alkaline degreasing solution (sodium hydroxide: sodium carbonate = 3:1, mass ratio, concentration 10%), rinsed with water, activated with 5% dilute sulfuric acid for 5 seconds to remove the surface oxide layer, rinsed quickly with water and dried with hot air to obtain a clean and surface-activated copper wire substrate.

[0075] Coating and bonding: The polyimide-polyolefin composite material is heated to 45°C to soften it, and then conveyed to the coating die through an SJ-20 screw coating machine, so that the softened polymer material tightly wraps the surface of the copper wire substrate at the die, forming an initial coating layer.

[0076] Ultrasonic micro-melting: High-frequency ultrasonic vibration is applied in contact. The CSB-20100 high-frequency ultrasonic transducer is fixedly connected to the outer wall of the coating mold. The initial ultrasonic parameters are set as follows: frequency 60kHz, power 1200W, amplitude 10μm. The IRTP-300L infrared temperature sensor at the mold opening monitors the temperature of the bonding surface in real time. The ultrasonic power is dynamically adjusted according to the temperature feedback to stabilize the micro-melting temperature of the bonding surface at 80℃. By utilizing the cavitation and thermal effects of ultrasound, the polymer material at the mold opening forms a local micro-melting state and adheres tightly to the surface of the copper wire substrate to form a polymer initial coating layer.

[0077] Synchronous stretching and sizing: The copper wire with the initial coating layer is stretched and sizing simultaneously using a WDW-05 electronic universal stretching machine. The stretching speed is set to 15m / min and the stretching force is 15N. During the stretching process, ultrasonic vibration is applied in conjunction, and the ultrasonic vibration power is reduced by 100W for every meter the metal wire travels, until the initial coating layer is initially shaped, and finally the coating thickness is 0.08mm and the finished copper wire diameter is 0.45mm.

[0078] Low-temperature curing: The stretched and sized composite copper wire is sent into the DHG-9030A hot air circulating curing oven, the curing temperature is set to 80℃, the curing time is 25s, and a constant tension of 15N is maintained during the curing process to allow the micro-molten polymer coating to complete the curing and forming a dense polymer composite coating.

[0079] Post-treatment of surface: First, the surface of the composite copper wire is swept and dust is removed by high-pressure cold air at 1.5m / s. Then, the appearance and circumferential uniformity of the coating are inspected by stereomicroscope and laser diameter gauge in turn to remove residual impurities on the surface and obtain the finished polymer insulating composite copper wire.

[0080] (III) Results of Finished Product Performance Tests

[0081] The adhesion between the coating and the substrate is 18.2 N / mm. 2 The polymer coating has a porosity of 0.3%, a damp heat aging time (85℃ / 85%RH) of 1100h, a circumferential uniformity deviation of 0.006mm, and no pinholes, bubbles, or scratches on the coating surface under a 200x microscope.

[0082] Example 2

[0083] Unlike Example 1:

[0084] The metal wire matrix is ​​low-carbon steel wire with a diameter of 1.0 mm;

[0085] The polymer coating material is formulated with a ratio of polyimide to polyolefin of 3:1 (mass ratio).

[0086] Initial ultrasonic parameters: frequency 40kHz, power 1000W, amplitude 8μm, and the micro-melting temperature of the bonding surface stabilized at 70℃.

[0087] Synchronous stretching and sizing parameters: stretching speed 12m / min, stretching force 20N, ultrasonic power decreases by 80W for every meter the metal wire travels;

[0088] Low-temperature curing parameters: curing temperature 75℃, curing time 20s, constant tension 20N.

[0089] The remaining process steps, instruments, equipment, and operating methods are the same as in Example 1.

[0090] Finished product performance test results: Coating-substrate adhesion strength 17.5 N / mm 2 The porosity is 0.4%, the damp heat aging time is 1080h, the circumferential uniformity deviation of the coating is 0.007mm, and there are no pinholes, bubbles, or scratches on the coating surface under a 200x microscope.

[0091] Example 3

[0092] Unlike Example 1:

[0093] The metal wire matrix is ​​a nickel alloy wire with a diameter of 0.1 mm;

[0094] The polymer coating material is formulated with a ratio of polyimide to polyolefin of 10:1 (mass ratio).

[0095] Initial ultrasonic parameters: frequency 80kHz, power 800W, amplitude 6μm, and the micro-melting temperature of the bonding surface stabilized at 60℃.

[0096] Synchronous stretching and sizing parameters: stretching speed 8m / min, stretching force 10N, ultrasonic power decreases by 50W for every meter the metal wire travels;

[0097] Low-temperature curing parameters: curing temperature 65℃, curing time 15s, constant tension 10N.

[0098] The remaining process steps, instruments, equipment, and operating methods are the same as in Example 1.

[0099] Finished product performance test results: Coating-substrate adhesion strength 16.8 N / mm 2 The porosity is 0.2%, the damp heat aging time is 1150h, the circumferential uniformity deviation of the coating is 0.005mm, and there are no pinholes, bubbles, or scratches on the coating surface under a 200x microscope.

[0100] Example 4

[0101] Unlike Example 1:

[0102] The metal wire matrix is ​​a copper-nickel alloy wire with a diameter of 5.0 mm;

[0103] The polymer coating material is formulated with a ratio of polyimide to polyolefin of 1:10 (mass ratio).

[0104] Initial ultrasonic parameters: frequency 100kHz, power 2000W, amplitude 20μm, and the micro-melting temperature of the bonding surface stabilized at 120℃.

[0105] Synchronous stretching and sizing parameters: stretching speed 20m / min, stretching force 30N, ultrasonic power decreases by 200W for every meter the metal wire travels;

[0106] Low-temperature curing parameters: curing temperature 110℃, curing time 35s, constant tension 30N.

[0107] The remaining process steps, instruments, equipment, and operating methods are the same as in Example 1.

[0108] Finished product performance test results: Coating-substrate adhesion strength 15.8 N / mm 2 The porosity is 0.5%, the damp heat aging time (85℃ / 85%RH) is 1000h, the circumferential uniformity deviation of the coating is 0.009mm, and there are no pinholes, bubbles, or scratches on the coating surface under a 200x microscope.

[0109] Comparative Example

[0110] Comparative Example 1

[0111] (a) Test materials

[0112] Completely consistent with Example 1: copper wire (0.5 mm in diameter), polyimide:polyolefin = 1:5 (mass ratio).

[0113] (II) Traditional process steps

[0114] Pretreatment: Completely consistent with Example 1;

[0115] Overall hot melt coating: Without ultrasonic vibration assistance, the polyimide-polyolefin composite material is directly heated to 180°C and completely melted, and then coated onto the surface of the copper wire substrate through the die of the same type of screw coating machine.

[0116] Direct stretching and sizing: Using the same model of electronic universal stretching machine, the stretching speed is set to 15m / min and the stretching force to 15N, without ultrasonic vibration coordination and without power gradient adjustment;

[0117] Curing process: The coated copper wire is fed into an oven of the same model without constant tension and cured at 120℃ for 30 seconds.

[0118] Surface treatment: Only 1.5m / s high-pressure cold air is used for dust removal, and there is no coating. Special testing is conducted on appearance and circumferential uniformity.

[0119] (III) Results of Finished Product Performance Tests

[0120] The adhesion between the coating and the substrate is 7.3 N / mm. 2 The polymer coating has a porosity of 7.8%, a damp heat aging time (85℃ / 85%RH) of 320h, a coating circumferential uniformity deviation of 0.025mm, and a large number of pinholes and microbubbles are present on the coating surface under a 200x microscope.

[0121] Comparative Example 2

[0122] (a) Test materials

[0123] Completely consistent with Example 4: copper-nickel alloy wire (5.0 mm in diameter), polyimide:polyolefin = 1:10 (mass ratio).

[0124] (II) Traditional process steps

[0125] Pretreatment: Completely consistent with Example 4;

[0126] Overall hot melt coating: Without ultrasonic vibration assistance, the composite material is heated to 200℃ and completely melted, and then coated onto the surface of the alloy wire substrate through the die of the same type of screw coating machine;

[0127] Direct stretching and sizing: Using the same model of electronic universal stretching machine, the stretching speed is set to 20m / min and the stretching force to 30N, without ultrasonic vibration coordination and without power gradient adjustment;

[0128] Curing process: The coated alloy wire is fed into an oven of the same model without constant tension and cured at 130℃ for 40 seconds.

[0129] Surface treatment: Only 2.0m / s high-pressure cold air is used for dust removal, and there is no coating. Special testing is conducted on appearance and circumferential uniformity.

[0130] (III) Results of Finished Product Performance Tests

[0131] The coating-substrate adhesion is 6.5 N / mm. 2 The polymer coating has a porosity of 6.2%, a damp heat aging time (85℃ / 85%RH) of 360h, a circumferential uniformity deviation of 0.022mm, and pinholes and bubbles are present on the coating surface under a 200x microscope, with tensile scratches in some areas.

[0132] Performance testing methods

[0133] Coating adhesion to the metal wire substrate: According to GB / T5270-2015 "Test Method for Adhesion Strength of Electrodeposited and Chemically Deposited Coatings on Metallic Substrates", the cross-cut tensile test was used. The coating was divided into 1mm × 1mm grids, tensile test specimens were bonded, and tensile tests were performed at a speed of 5mm / min. The maximum tensile force at which the coating peeled off was recorded and converted into adhesion strength (N / mm²). 2 Five samples were tested in each group, and the average value was taken.

[0134] Porosity of polymer coatings: According to ASTM B799-2015 "Determination of porosity of electrodeposited coatings (filter paper method)", the potassium ferricyanide filter paper method was used. After the filter paper was attached for 10 minutes, the number of blue spots was counted and converted into porosity (%). Five samples were tested in each group and the average value was taken.

[0135] Resistance to damp heat aging: According to GB / T2423.3-2016 "Environmental testing - Part 2: Test methods - Test Cab: Constant damp heat test", the sample was placed in a damp heat test chamber at a temperature of 85℃ and a humidity of 85%RH. The sample was taken out every 100h to observe the appearance of the coating and the time (h) when the coating first showed peeling, cracking and chalking was recorded.

[0136] Coating circumferential uniformity: The coating thickness is measured at multiple points along the circumference of the metal wire using a laser diameter gauge. The difference between the maximum and minimum thickness is calculated as the coating circumferential uniformity deviation (mm).

[0137] Coating appearance: The coating surface is observed under a stereomicroscope at 200x magnification to determine whether there are defects such as pinholes, bubbles, and scratches.

[0138] The performance comparison between the examples and the comparative examples is shown in Table 1 below.

[0139]

[0140] Table 1

[0141] The polymer insulating composite metal wire prepared by the process of this invention has superior performance indicators compared to existing traditional polymer coating-stretching processes. It is also adaptable to metal wire substrates of different diameters and materials, exhibiting strong industrial applicability. The technological advantages stem from the innovative combination of contact-type high-frequency ultrasonic vibration, closed-loop temperature feedback control of the bonding surface, gradient power ultrasonic synergy during the stretching process, and constant tension curing. Specifically, this is reflected in:

[0142] The cavitation effect of high-frequency ultrasound can completely eliminate microbubbles generated during the coating process of polymer coatings, reduce coating porosity, improve coating density from the root, and solve the problems of easy water ingress and poor corrosion resistance of traditional coating processes.

[0143] The local micro-melting effect of ultrasound enables the polymer material and the metal wire matrix to be tightly bonded at the molecular level, which improves the bonding force between the coating and the matrix. Moreover, the low temperature characteristics of local micro-melting avoid the damage to the metallographic structure and mechanical properties of the metal wire matrix caused by the high temperature of the traditional overall hot melting process.

[0144] The gradient power ultrasonic co-application during the stretching process, combined with the constant tension delivery during the curing stage, effectively alleviates the internal stress generated in the coating during stretching and curing, avoids defects such as coating cracking, edge curling, and stretching scratches, and improves the circumferential uniformity and dimensional accuracy of the coating.

[0145] The synergistic effect of the dense coating structure and high adhesion improves the resistance of the finished metal wire to damp heat aging, making it suitable for complex working conditions in various application scenarios such as electronic component leads, precision equipment insulating electrode wires, and low-voltage insulated cables.

[0146] Meanwhile, the process of this invention only requires the addition of an ultrasonic transducer and an infrared temperature sensor to the existing traditional metal wire coating-stretching production line, without the need for a complete overhaul of the original production line. The modification cost is low, the process parameters are controllable, the mass production stability is high, and it has industrial application value.

[0147] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for micro-cladding-stretching forming of metal wire polymer films, characterized in that, Includes the following steps: The first step is to pretreat the metal wire substrate to remove grease, impurities and oxide layer from the surface of the metal wire substrate, so as to obtain a clean and surface-activated metal wire substrate. The second step is to transport the polymer coating material to the coating die, so that the polymer coating material can form a coating and bond with the clean metal wire substrate at the die. The third step is to apply high-frequency ultrasonic vibration to the coating mold. The cavitation and thermal effects of the ultrasonic vibration cause the polymer coating material at the mold opening to form a local micro-melting state, allowing the micro-melting polymer coating material to adhere tightly to the surface of the metal wire substrate, forming a polymer initial coating layer. The fourth step involves simultaneously stretching and sizing the metal wire with the initial polymer coating. During the stretching process, high-frequency ultrasonic vibration is applied in conjunction to further bond the micro-molten polymer coating to the metal wire substrate under the action of stretching force, thereby achieving the shaping of the coating thickness and the diameter of the metal wire. The fifth step is to perform low-temperature post-curing treatment on the stretched and sized composite metal wire to allow the micro-molten polymer coating to complete curing and forming a dense polymer composite coating. The sixth step is to perform surface post-treatment on the cured polymer insulating composite metal wire to remove residual impurities and obtain the finished metal wire.

2. The method for micro-cladding-stretching forming of a metal wire polymer film according to claim 1, characterized in that: The high-frequency ultrasonic vibration is applied in a contact manner, with the ultrasonic transducer fixedly connected to the outer wall of the coating mold, so that the ultrasonic vibration is transmitted through the mold to the polymer coating material and the metal wire substrate at the mold opening.

3. The method for micro-cladding-stretching forming of a metal wire polymer film according to claim 1, characterized in that: The frequency of high-frequency ultrasonic vibration is 20-100kHz, the power of ultrasonic vibration is 500-2000W, the amplitude of ultrasonic vibration is 5-20μm, and the duration of ultrasonic vibration covers the entire process of micro-melting coating of polymer coating materials and stretching and sizing of metal wires. The process also includes: setting an infrared temperature sensor at the mold opening to monitor the temperature of the bonding surface in real time, and dynamically adjusting the ultrasonic vibration power according to the temperature feedback to maintain the micro-melting temperature of the bonding surface at 50-350℃.

4. The method for micro-cladding-stretching forming of a metal wire polymer film according to claim 1, characterized in that: The polymer coating material is a thermoplastic polymer material, including at least one of polyimide, polyolefin, polytetrafluoroethylene, and nylon resin; The mass ratio of the polymer coating material is polyimide:polyolefin = 1:10 to 10:

1.

5. The method for micro-cladding-stretching forming of a metal wire polymer film according to claim 1, characterized in that: The metal wire matrix is ​​one of steel wire, copper wire, aluminum wire, nickel alloy wire, or copper-nickel alloy wire, and the diameter of the metal wire matrix is ​​0.05-5mm.

6. The method for micro-cladding-stretching forming of a metal wire polymer film according to claim 1, characterized in that: The local micro-melting state of the polymer coating material is that the micro-melting area is limited to the bonding surface between the polymer coating and the metal wire substrate at the die opening. The micro-melting temperature of the bonding surface is 50-350℃, and this temperature does not exceed the metallographic structure change temperature of the metal wire substrate.

7. The method for micro-cladding-stretching forming of a metal wire polymer film according to claim 1, characterized in that: The stretching speed of the synchronous stretching and sizing operation is 5-30 m / min, and the stretching force during the stretching process is 1-30 N. During the stretching process, the ultrasonic vibration power is reduced by 50-200 W according to the preset gradient for every 1 meter the metal wire travels.

8. The method for micro-cladding-stretching forming of a metal wire polymer film according to claim 1, characterized in that: The low-temperature post-curing treatment is hot air circulation curing, with a curing temperature of 60-120℃ and a curing time of 10-40s. During the curing process, the metal wire is kept under constant tension, and the tension value is consistent with the tensile force in the stretching and sizing stage.

9. The method for micro-cladding-stretching forming of a metal wire polymer film according to claim 1, characterized in that: The surface post-treatment includes high-pressure cold air dust removal and coating appearance inspection. The wind speed of the high-pressure cold air is 1-5m / s, and it is only used to blow away dust from the surface of the metal wire. The appearance inspection of the coating must ensure that the polymer coating of the finished metal wire is free of pinholes, bubbles, and scratches, and the circumferential uniformity deviation of the coating is ≤0.1mm.

10. The method for micro-cladding-stretching forming of a metal wire polymer film according to claim 1, characterized in that: The polymer insulating composite wire prepared by the process has a polymer coating and a metal wire substrate, wherein the bonding force between the polymer coating and the metal wire substrate is greater than or equal to 15 N / mm 2 , the porosity of the polymer coating is less than or equal to 0.5%, and the finished metal wire has an aging resistance time greater than or equal to 1000 h in a temperature range of -40-120 DEG C and a humidity of 85%, and the coating has no peeling, cracking or pulverization.

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