Graphene copper wire manufacturing process capable of painting and enameled wire produced by graphene copper wire manufacturing process

Abstract

The invention provides a manufacturing process of a paintable graphene copper wire and an enameled wire produced by the same, belongs to the technical field of enameled wire manufacturing, and aims at solving the problems that the conductivity of a conventional copper wire enameled wire is reduced at high temperature, an insulating layer is easy to age and the mechanical strength is insufficient, and an existing graphene composite wire is poor in graphene dispersion, weak in interface bonding and poor in conductivity. The method comprises the following process steps that the copper wire is pretreated to remove oxides and impurities, a functionalized graphene oxide solution is prepared, and the graphene copper wire is formed through electrochemical reduction deposition; the graphene copper wire is twisted and then coated with copper foil, argon arc welding is conducted to form a closed pipe shape, drawing or rolling is conducted to enable the copper foil and the graphene copper wire to be tightly combined, and finally insulating paint is coated and solidified. The enameled wire produced by the process is excellent in conductivity, heat resistance and mechanical strength, solves the problem of graphene copper wire painting, and is suitable for electromagnetic element windings such as motors and transformers.

Description

Technical Field

[0001] This invention relates to the field of enameled wire manufacturing technology, specifically to a process for manufacturing enamelable graphene copper wire and the enameled wire produced therefrom. Background Technology

[0002] Enameled wire is widely used in the windings of electromagnetic components such as motors, transformers, and inductors. These components may face high temperatures and mechanical vibrations during operation, which places high demands on the conductivity, heat resistance, mechanical strength, and insulation stability of the enameled wire.

[0003] Current conventional copper enameled wires have significant shortcomings: conductivity decreases at high temperatures, affecting component efficiency; the insulation layer is prone to aging and failure, shortening the wire's lifespan; and overall mechanical strength is insufficient, making them susceptible to damage during installation or under vibration. To address these issues, the industry has attempted to develop graphene composite conductors. Existing technologies often employ physical mixing or electroplating processes to prepare graphene copper wires. However, graphene exhibits poor dispersion in copper wires, and the interfacial bonding between graphene and copper is weak, resulting in limited improvements in conductivity, heat resistance, and other properties.

[0004] In addition, some technologies attempt to directly coat graphene copper wires with paint to improve the performance of conventional enameled wires. However, after drawing and annealing, the surface of graphene copper wires is hydrophobic, which greatly reduces the adhesion of paint to its surface and makes it difficult to form a uniform and firm insulating varnish layer. Other technologies prepare graphene copper composite materials through graphene coating or electrodeposition, but have not solved the compatibility problem between the coating layer and the graphene interface, or are difficult to achieve large-scale production due to complex processes and high costs.

[0005] To address this, a process for manufacturing varnishable graphene copper wire and the resulting enameled wire are proposed. Summary of the Invention

[0006] The present invention aims to solve the problems mentioned in the background art by providing a process for manufacturing enamelable graphene copper wire and the enameled wire produced therefrom.

[0007] The specific technical solution is as follows: A process for manufacturing paintable graphene copper wire and the enameled wire produced therefrom, comprising the following steps: (1) Copper wire surface pretreatment: Remove oxides and impurities from the surface of copper wire using physical or chemical methods; (2) Preparation of functionalized graphene oxide solution: The graphene oxide dispersion was mixed with a silane coupling agent and then subjected to ultrasonic treatment to obtain a functionalized graphene oxide solution; (3) Electrochemical reduction deposition: The pretreated copper wire is immersed in a functionalized graphene oxide solution and a pulsed current is applied to reduce the graphene oxide to graphene in situ on the surface of the copper wire, forming a dense graphene composite layer, and thus obtaining graphene copper wire. (4) Graphene copper wire stranding: multiple graphene copper wires are stranded according to preset stranding parameters; (5) Copper foil coating: A layer of copper foil is uniformly coated on the outside of the stranded graphene copper wire; (6) Argon arc welding: Argon arc welding is used to weld the joints of the copper foil to form a closed tubular structure. (7) Tight bonding treatment: The copper wire after welding is subjected to copper tube drawing or rolling treatment to make the copper foil and graphene copper wire tightly bonded. (8) Insulating varnish coating: Insulating varnish is coated on the outside of the tightly bonded copper foil, and after curing, enameled wire is obtained.

[0008] This process removes oxides and impurities from the copper wire surface through pretreatment, providing a clean substrate for the subsequent formation of the graphene composite layer and preventing impurities from affecting interlayer bonding. The preparation of functionalized graphene oxide solution makes the graphene oxide more uniformly dispersed, and the modification with silane coupling agent improves its compatibility with the copper wire surface. Electrochemical reduction deposition allows graphene oxide to be reduced in situ on the copper wire surface to form a dense graphene composite layer, effectively leveraging the role of graphene in optimizing electron transport. After the graphene copper wire is stranded, it is wrapped with copper foil, and the combination of argon arc welding and drawing / rolling tightly solves the problem of paint adhesion caused by the hydrophobicity of graphene copper wire. The hydrophilicity of copper foil can reduce the paint contact angle. Finally, an insulating varnish is coated and cured, giving the finished enameled wire excellent conductivity, heat resistance, and mechanical strength, and the insulation layer adheres firmly, avoiding delamination.

[0009] In the above-mentioned process for manufacturing paintable graphene copper wire, in step (1), the specific method of surface pretreatment of copper wire is as follows: first pickling with an acid pickling solution, and then plasma cleaning; the acid pickling solution is dilute sulfuric acid, and the pickling time is 10-20 minutes; the power of plasma cleaning is 200-500W, and the cleaning time is 5-15 minutes.

[0010] By combining pickling and plasma cleaning as pretreatment methods, pickling can specifically remove the oxide layer on the surface of copper wires, while plasma cleaning can further remove residual impurities and activate the surface of copper wires, making it easier for the surface of copper wires to contact the subsequent functionalized graphene oxide solution. This improves the adhesion stability of the graphene composite layer on the surface of copper wires, avoids the graphene composite layer from falling off or cracking in subsequent processes, and lays the foundation for the graphene composite layer to fully exert its performance.

[0011] In the above-mentioned process for manufacturing paintable graphene copper wire, in step (2), the silane coupling agent is γ-aminopropyltriethoxysilane; the mass ratio of graphene oxide dispersion to silane coupling agent is 100:5-15; the ultrasonic treatment power is 300-600W, and the ultrasonic time is 20-40 minutes.

[0012] The selection of specific silane coupling agents can effectively functionalize and modify graphene oxide, improving the interfacial bonding ability between graphene oxide and the copper wire surface. The reasonable ratio of graphene oxide dispersion and silane coupling agent, as well as ultrasonic treatment, can prevent graphene oxide from agglomerating in the solution, ensuring uniform dispersion of graphene oxide. This results in a denser and more uniform graphene composite layer structure formed by subsequent electrochemical deposition, reducing defects in the composite layer and ensuring the improvement effect of graphene on the conductivity and mechanical properties of copper wire.

[0013] In the above-mentioned process for manufacturing paintable graphene copper wire, in step (3), the current density of the pulse current is 1-5A / dm², the pulse frequency is 50-200Hz, the deposition time is 30-60 minutes, and the thickness of the graphene composite layer is 1-5μm.

[0014] By controlling the relevant parameters of the pulse current, the reduction and deposition process of graphene oxide on the surface of copper wire can be precisely regulated, avoiding the loose composite layer caused by excessively fast deposition or the low efficiency caused by excessively slow deposition. The resulting graphene composite layer has a suitable thickness and a dense structure, which can stably play the role of graphene in optimizing the electron transport path. At the same time, the composite layer can block heat diffusion to a certain extent, providing support for improving the heat resistance of the enameled wire and avoiding the impact of unstable composite layer performance on the overall performance of the enameled wire.

[0015] In the above-mentioned process for manufacturing varnishable graphene copper wire, in step (5), the copper foil is made of oxygen-free copper and has a thickness of 0.01-0.05 mm; during the coating process, the adhesion between the copper foil and the graphene copper wire is ≥95% and the overlap width of the copper foil is 0.5-2 mm.

[0016] Oxygen-free copper foil itself has good hydrophilicity, which meets the requirements of subsequent coating. The reasonable setting of copper foil thickness, adhesion and overlap width can ensure that the copper foil completely and tightly wraps the stranded graphene copper wire, avoiding problems such as wrinkles and gaps in the copper foil, ensuring the continuity and integrity of the copper foil layer, and thus allowing the paint to adhere evenly to the copper foil surface during subsequent coating. This completely solves the problem of coating difficulties caused by the hydrophobicity of graphene copper wire and improves the bonding stability between the insulating varnish layer and the copper foil layer.

[0017] In the above-mentioned process for manufacturing paintable graphene copper wire, in step (6), the welding current of the argon arc welding is 10-30A, the argon flow rate is 5-15L / min, and the welding speed is 50-150mm / min; the welding strength at the copper foil joint after welding is ≥20MPa.

[0018] Optimization of argon arc welding parameters ensures a strong weld at the copper foil joint, preventing damage to the copper foil caused by incomplete, missed, or over-welded welds. This guarantees the formation of a closed and complete tubular structure in the copper foil layer. Sufficient welding strength prevents the copper foil layer from cracking during subsequent drawing or rolling processes, maintaining the structural stability of the copper foil layer. This provides a reliable guarantee for the tight bonding of the copper foil layer with the graphene copper wire and subsequent coating processes, avoiding the impact of welding problems on the overall quality of the enameled wire.

[0019] In the above-mentioned process for manufacturing varnishable graphene copper wire, in step (7), if copper tube drawing is used, the deformation amount of drawing is 10%-30%; if rolling is used, the rolling pressure is 5-15MPa; after processing, the bonding force between copper foil and graphene copper wire is ≥50N / m.

[0020] Reasonable control of drawing deformation or rolling pressure can fully eliminate the gap between copper foil and graphene copper wire, greatly improve the bonding force between the two, and prevent the copper foil layer and graphene copper wire from separating during use; the tightly bonded structure can enhance the overall structural stability of the enameled wire, reduce the impact of interlayer loosening on mechanical properties, and thus improve the tensile strength of the enameled wire, ensuring that the enameled wire is not easily damaged under stress.

[0021] In the above-mentioned process for manufacturing varnishable graphene copper wire, in step (8), the insulating varnish is polyimide varnish or high-temperature resistant epoxy resin varnish; the coating adopts a multi-coating-curing process, the thickness of each coating is 5-15μm, the curing temperature is 180-250℃, and the curing time is 10-30 minutes; the total thickness of the final insulating varnish layer is 20-50μm.

[0022] The selected polyimide varnish or high-temperature resistant epoxy resin varnish has excellent heat resistance, which meets the high-temperature requirements of enameled wire. The multi-coating-curing process can avoid defects such as uneven varnish thickness and pinholes caused by single coating, forming a dense and uniform insulating varnish layer. The appropriate curing temperature and time can ensure that the insulating varnish is fully cured, improve the adhesion and temperature stability of the varnish layer, and make the insulation layer less prone to aging and cracking in high-temperature environment, thus ensuring the insulation performance of the enameled wire during long-term use.

[0023] In the above-mentioned process for manufacturing paintable graphene copper wire, in step (4), the graphene copper wire is stranded in a concentric stranding manner, and a constant tension is applied to each graphene copper wire during the stranding process; the outer roundness error of the stranded graphene copper wire bundle is ≤0.1mm.

[0024] The concentric stranding method ensures that multiple graphene copper wires form a regular circular cross-section after stranding, avoiding irregularities in the copper wire bundle cross-section caused by improper stranding. Constant tension control prevents some graphene copper wires from being stretched and damaging the graphene composite layer due to excessive force during stranding, or from becoming loose due to insufficient force, ensuring the stable position of each graphene copper wire in the stranded structure. The outer roundness error is controlled within ≤0.1mm, providing a flat and regular base for the subsequent uniform coating of copper foil. This reduces localized overthickness, wrinkles, or gaps caused by differences in the outer roundness of the base during copper foil coating, further improving the tightness of the fit between the copper foil and the graphene copper wire bundle. This lays the foundation for the integrity of subsequent argon arc welding and the uniformity of drawing / rolling, ultimately ensuring the consistency of the overall enameled wire structure and the stability of its mechanical properties.

[0025] The present invention also provides an enameled wire, produced by the above-described process for manufacturing varnishable graphene copper wire; the enameled wire comprises, from the inside out, a copper wire substrate, a graphene composite layer, a copper foil layer, and an insulating varnish layer; the graphene composite layer is a dense graphene layer formed by in-situ reduction of graphene oxide, and is tightly attached to the outside of the copper wire substrate; the copper foil layer is a closed tubular structure and is tightly wrapped around the outside of the graphene composite layer; the insulating varnish layer is tightly attached to the outside of the copper foil layer.

[0026] In the layered structure design of this enameled wire, the copper wire substrate provides basic support for conductivity; the graphene composite layer is tightly attached to the outside of the copper wire substrate, which can effectively optimize the electron transport path and block heat diffusion; the closed tubular structure of the copper foil layer ensures hydrophilicity, creating conditions for the stable adhesion of the insulating varnish layer; the insulating varnish layer is tightly attached to the outside of the copper foil layer, providing reliable insulation protection; the close combination and synergistic effect of each layer gives the enameled wire excellent conductivity, heat resistance, mechanical strength and insulation performance at the same time, and the layers are not easy to delaminate, meeting the needs of enameled wire in complex working conditions.

[0027] The enameled wire described above has the following characteristics: its conductivity is 5%-15% higher than that of pure copper wire; the long-term temperature resistance of the insulating varnish layer is ≥240℃; and the tensile strength of the enameled wire is 10%-25% higher than that of pure copper wire of the same specification.

[0028] The improved conductivity of enameled wire stems from the optimization of electron transport paths by graphene in the graphene composite layer, reducing losses during electron transport. The excellent temperature resistance of the insulating varnish layer is due to the heat diffusion barrier effect of the graphene composite layer and the good heat resistance and full curing of the insulating varnish itself. The improved tensile strength is attributed to the enhanced interfacial bonding between the copper wire matrix and each layer by the graphene composite layer, while the tight bonding between the copper foil layer and the graphene copper wire further enhances the overall structural strength. This ensures stable conductivity of the enameled wire at high temperatures, prevents insulation layer aging, and allows it to withstand certain mechanical forces, expanding its application scenarios.

[0029] The present invention has the following beneficial effects: 1. Improved conductivity: By removing the oxide layer and impurities and activating the surface through copper wire pretreatment, combined with the uniform dispersion and electrochemical in-situ reduction deposition of functionalized graphene oxide, the graphene composite layer is tightly and densely attached to the surface of the copper wire. Graphene can optimize the electron transport path and reduce the scattering loss of electrons on the surface of the copper wire, thereby making the conductivity of the enameled wire superior to that of conventional pure copper enameled wire.

[0030] 2. Enhanced heat resistance: The dense graphene composite layer can block heat diffusion and slow down the transfer of heat generated by the copper wire to the insulation layer during operation; at the same time, the selected polyimide or high-temperature resistant epoxy resin paint itself has excellent heat resistance, and the insulation layer structure formed by multiple coating and curing is stable. With the synergistic effect of the two, the insulation layer is not easy to age or crack due to high temperature, ensuring the stable use of enameled wire under high temperature conditions.

[0031] 3. Improved mechanical strength: The tight bonding between the graphene composite layer and the copper wire enhances the tensile strength of the copper wire itself; concentric stranding (with constant tension) makes the graphene copper wire bundle structure regular and without looseness; argon arc welding makes the copper foil form a closed and stable structure; and drawing / rolling further enhances the interfacial bonding force between the copper foil and the graphene copper wire bundle. Each layer works closely together to avoid interlayer separation during use, greatly improves the overall tensile strength of the enameled wire, and reduces the risk of damage during mechanical vibration or installation.

[0032] 4. Solving the painting problem: The hydrophobic surface of graphene copper wires makes it difficult for paint to adhere, while copper foil has good hydrophilicity. By uniformly covering the copper foil and welding it into a closed tube, the contact angle between the paint and the substrate can be significantly reduced. At the same time, the tight bonding between the copper foil and the graphene copper wire bundle prevents the copper foil from loosening during the painting process, ensuring that the insulating paint can be uniformly and firmly adhered to the copper foil surface to form a stable insulating layer, thus solving the core pain point of the existing difficulty in painting graphene copper wires.

[0033] 5. Adaptable to large-scale production: The parameters of electrochemical deposition are highly controllable throughout the process, and continuous production can be achieved by adjusting the current, time, etc. The stranding, copper foil coating, argon arc welding, drawing / rolling, painting and other steps all use conventional equipment (only the parameters need to be adapted), without the need for special and complex equipment. The process cost is controllable and it is easy to promote and apply industrially. Attached Figure Description

[0034] Figure 1 A flowchart illustrating the fabrication process of paintable graphene copper wire provided in an embodiment of the present invention. Detailed Implementation

[0035] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0036] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual images. They should not be construed as limiting the scope of this application. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0037] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present application. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0038] In the description of this invention, unless otherwise explicitly specified and limited, the term "connection" or similar designation indicating a connection between components should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0039] Reference Figure 1 This application provides the following three embodiments: Example 1: Preparation of high-performance coated graphene copper wire and enameled wire I. Complete Technical Solution 1. Copper wire surface pretreatment: Select oxygen-free copper wire with a diameter of 0.5mm as the substrate. First, use 10% dilute sulfuric acid for pickling for 15 minutes to remove the surface oxide layer. Then, perform plasma cleaning with a plasma power of 350W for 10 minutes to further remove residual impurities and activate the copper wire surface.

[0040] 2. Preparation of functionalized graphene oxide solution: Prepare a graphene oxide (GO) dispersion with a concentration of 0.5 mg / mL. Add silane coupling agent at a mass ratio of 100:10 between the graphene oxide dispersion and γ-aminopropyltriethoxysilane. Place the mixture in an ultrasonic device, set the ultrasonic power to 450 W, and the ultrasonic time to 30 minutes to obtain a uniformly dispersed functionalized graphene oxide solution.

[0041] 3. Electrochemical reduction deposition: The pretreated copper wire is used as the working electrode, the platinum sheet as the counter electrode, and the saturated calomel electrode as the reference electrode. The three-electrode system is constructed by immersing the pretreated copper wire in the functionalized graphene oxide solution. A pulsed current is applied with a current density of 3 A / dm², a pulse frequency of 125 Hz, and a deposition time of 45 minutes. This allows the graphene oxide to be reduced to graphene in situ on the surface of the copper wire, forming a dense graphene composite layer with a thickness of 3 μm, thus obtaining the graphene copper wire.

[0042] 4. Graphene copper wire stranding: Take 6 of the above-mentioned graphene copper wires and strand them in a concentric stranding manner. During the stranding process, a constant tension of 5N is applied to each graphene copper wire through a tension controller to ensure that the cross-section of the stranded copper wire bundle is regular and there is no loosening or excessive stretching.

[0043] 5. Copper foil wrapping: Select oxygen-free copper foil with a thickness of 0.03mm and wrap it evenly on the outside of the stranded graphene copper wire bundle. Control the adhesion between the copper foil and the graphene copper wire to be ≥95%, and the overlap width of the copper foil is 1mm to ensure no wrinkles or gaps.

[0044] 6. Argon arc welding: The copper foil joints are welded using argon arc welding equipment. The welding current is set to 20A, the argon flow rate is 10L / min, and the welding speed is 100mm / min. The copper foil is made into a closed tubular structure. After welding, the joints are checked for any incomplete welds or missing welds.

[0045] 7. Tight bonding treatment: After welding, the copper wire is subjected to copper tube drawing treatment. The drawing deformation is set to 20%. The drawing force is used to make the copper foil and the graphene copper wire bundle fit tightly together, eliminating the interlayer gap.

[0046] 8. Insulating varnish coating: Polyimide varnish is selected as the insulating varnish. A multi-coat-curing process is adopted. The thickness of each coating is 10μm. After coating, the coating is placed in a curing oven with a curing temperature of 215℃ and a curing time of 20 minutes. The coating is repeated 3 times to finally form an insulating varnish layer with a total thickness of 35μm, thus obtaining the enameled wire.

[0047] II. Working Principle 1. Pretreatment stage: Dilute sulfuric acid pickling dissolves oxides such as cuprous oxide and copper oxide on the surface of copper wire through chemical reaction, thus initially purifying the surface; Plasma cleaning uses high-energy particles to impact the surface of copper wire, which can not only remove trace impurities remaining from pickling, but also break some chemical bonds on the surface of copper wire, forming active sites, providing an "anchoring basis" for the subsequent adhesion of graphene composite layers.

[0048] 2. Functionalization and Deposition Stage: The amino group of γ-aminopropyltriethoxysilane can chemically bond with the hydroxyl and carboxyl groups on the surface of graphene oxide. Its alkoxy group can react with the hydroxyl group on the surface of copper wire in the subsequent process to achieve the interface bridging of "graphene oxide-silane coupling agent-copper wire" and solve the problem of poor compatibility between graphene and copper wire. The pulsed current can control the reduction rate of graphene oxide, avoid the interlayer porosity caused by excessively fast single reduction, and make graphene deposited uniformly in the form of dense layer, thus optimizing the electron transport path.

[0049] 3. Stranding and Coating Stage: Concentric stranding combined with constant tension ensures that multiple graphene copper wires form a circular cross-section after stranding, avoiding local bulges or depressions; the hydrophilicity of oxygen-free copper foil can improve the hydrophobicity of graphene copper wires, solving the problem of paint adhesion, while the closed tubular structure can prevent impurities from entering the interlayer during subsequent processes.

[0050] 4. Bonding and Coating Stage: Pulling deformation compresses the interlayer gap between the copper foil and the graphene copper wire bundle through mechanical force, improving the interfacial bonding force; the multi-coat-curing of polyimide paint can eliminate pinholes and bubble defects of single-coat. During the curing process, the paint molecules cross-link to form a dense network, and at the same time combine with the active sites on the copper foil surface to ensure that the insulation layer is firmly attached.

[0051] III. Experimental Data 1. Conductivity test: The volume resistivity of the enameled wire was tested using a four-probe tester. The results showed that its conductivity was better than that of pure copper enameled wire of the same specification, and there was no significant loss during electron transmission.

[0052] 2. Heat resistance test: The enameled wire was placed in a constant temperature chamber at 240℃ for 1000 hours. After being taken out, the dielectric loss value of the insulation layer was tested by a dielectric loss meter. The dielectric loss value did not change significantly, and the graphene composite layer did not fall off and the insulation layer did not crack.

[0053] 3. Mechanical performance testing: The tensile strength of the enameled wire was tested using a universal testing machine, and no delamination was observed upon fracture; the adhesion of the insulating varnish layer was tested using the cross-cut test, and no peeling of the varnish layer was observed after the cross-cut test.

[0054] 4. Coating effect test: The contact angle between the insulating varnish and the copper foil surface was tested using a contact angle meter. The contact angle was significantly lower than that between the insulating varnish and the graphene copper wire surface, indicating good uniformity of the coating.

[0055] IV. Technical Effects 1. Improved conductivity: The dense graphene composite layer optimizes the electron transport path and reduces electron scattering loss on the copper wire surface, making the enameled wire more conductive than conventional pure copper enameled wire, meeting the requirements of high conductivity applications.

[0056] 2. Heat resistance and insulation stability: The graphene composite layer can block heat diffusion and slow down the transfer of heat to the insulation layer; the dense structure and firm adhesion of the polyimide varnish make the insulation layer less prone to aging and cracking in high-temperature environments, ensuring the long-term heat resistance of the enameled wire.

[0057] 3. Mechanical and coating reliability: Concentric stranding and constant tension ensure the neatness of the copper wire bundle, and the drawing process enhances the interlayer bonding force, so that there is no interlayer separation when the enameled wire is tensile; the hydrophilicity of copper foil solves the problem of coating graphene copper wire, and the coating layer is uniform and has strong adhesion, avoiding coating peeling during use.

[0058] Example 2: Preparation of High-Temperature Resistant Paintable Graphene Copper Wire and Enameled Wire I. Complete Technical Solution 1. Copper wire surface pretreatment: Select oxygen-free copper wire with a diameter of 0.8mm, first pickle it with 15% dilute sulfuric acid for 20 minutes to deeply remove the surface oxide layer; then perform plasma cleaning, set the power to 500W and the cleaning time to 15 minutes to enhance the surface activation effect.

[0059] 2. Preparation of functionalized graphene oxide solution: Prepare a GO dispersion with a concentration of 0.8 mg / mL, add a coupling agent at a mass ratio of 100:15 of graphene oxide dispersion to γ-aminopropyltriethoxysilane, and sonicate at 600 W for 40 minutes to prepare a highly dispersible functionalized GO solution.

[0060] 3. Electrochemical reduction deposition: A three-electrode system was constructed, with a pulse current density of 5 A / dm², a pulse frequency of 200 Hz, and a deposition time of 60 minutes, to form a graphene composite layer with a thickness of 4 μm on the surface of the copper wire.

[0061] 4. Graphene copper wire stranding: Take 8 graphene copper wires and strand them concentrically. Apply a constant tension of 8N to ensure that the outer roundness error of the stranded copper wire bundle is ≤0.08mm.

[0062] 5. Copper foil wrapping: Select oxygen-free copper foil with a thickness of 0.05mm. When wrapping, control the adhesion to be ≥96% and the overlap width to 2mm to avoid the copper foil edges from lifting.

[0063] 6. Argon arc welding: Set the welding current to 30A, argon flow rate to 15L / min, and welding speed to 150mm / min to ensure that the welding strength at the copper foil joint meets the standard.

[0064] 7. Tight bonding process: The copper foil is tightly bonded to the graphene copper wire bundle by a rolling process with a rolling pressure of 15MPa.

[0065] 8. Insulating varnish coating: High-temperature resistant epoxy resin varnish is selected, with each coat being 15μm thick, cured at 250℃ for 30 minutes; the coating is repeated 3 times to form an insulating varnish layer with a total thickness of 45μm.

[0066] II. Working Principle 1. High-temperature resistant pretreatment design: Longer pickling time and higher power plasma cleaning can thoroughly remove stubborn oxide layers and impurities on the surface of copper wires, avoiding interface oxidation caused by residual impurities under high temperature conditions; the degree of surface activation is improved, making the bonding between the graphene composite layer and the copper wire more stable at high temperatures and less prone to falling off due to thermal expansion differences.

[0067] 2. High proportion of coupling agent and thick composite layer: The higher quality ratio of silane coupling agent can enhance the interfacial bonding force between graphene oxide and copper wire, reducing the risk of interlayer delamination at high temperatures; the 4μm thick graphene composite layer can form a more effective thermal barrier, slowing down the heat transfer from copper wire to insulation layer and reducing the thermal aging rate of insulation layer.

[0068] 3. Thick copper foil and high pressure rolling: 0.05mm thick oxygen-free copper foil has higher mechanical strength and is not easily deformed at high temperatures; the rolling pressure of 15MPa can eliminate the interlayer gap to the maximum extent, so that the copper foil and graphene copper wire bundle form an "integrated" structure, avoiding structural loosening caused by interlayer air expansion at high temperatures.

[0069] 4. High-temperature resistant paint and high-temperature curing: High-temperature resistant epoxy resin paint itself has excellent high-temperature resistance. High-temperature curing at 250℃ can fully cross-link the paint molecules, forming a more stable three-dimensional network structure, which improves the insulation layer's anti-aging and anti-cracking ability at high temperatures.

[0070] III. Experimental Data 1. Long-term high temperature resistance test: The enameled wire was placed in a constant temperature environment of 260℃ for 1500 hours. The resistance of the copper wire matrix was tested with a resistance tester, and the resistance change rate was extremely small. The insulation resistance of the insulation layer was tested with an insulation resistance tester, and the insulation resistance did not decrease significantly.

[0071] 2. Thermal shock test: The enameled wire was cycled between -40℃ (for 2 hours) and 260℃ (for 2 hours) 200 times. After the test, the appearance was observed. The graphene composite layer did not peel off, the copper foil layer did not crack, and the insulation layer did not peel off.

[0072] 3. Welding strength test: The welding strength of the copper foil joint was tested using a tensile testing machine. The fracture location was in the copper foil body rather than the weld, which proved that the weld strength met the standard.

[0073] 4. Temperature resistance test of insulation layer: The glass transition temperature of the insulating varnish layer was tested by differential scanning calorimetry (DSC). The glass transition temperature was significantly higher than that of conventional epoxy resin varnish.

[0074] IV. Technical Effects 1. Excellent long-term high temperature resistance: Thorough pretreatment, the thermal barrier effect of the thick graphene composite layer, and the stable structure of the high-temperature resistant paint ensure that the enameled wire maintains stable conductivity and is not prone to aging when used in high-temperature environments for a long time, meeting the requirements of high-temperature conditions (such as high-temperature areas of motors and transformers).

[0075] 2. Strong thermal shock resistance: The tightly bonded copper foil layer with high mechanical strength can buffer the thermal expansion and contraction stress caused by high and low temperature cycles, avoid interlayer separation or structural cracking, and improve the reliability of the enameled wire under temperature fluctuation scenarios.

[0076] 3. Stable welding and insulation performance: High welding current and argon flow rate ensure strong welds and prevent weld failure at high temperatures; the high-temperature cured insulating varnish layer has a stable structure and maintains its insulation performance for a long time, reducing the risk of leakage at high temperatures.

[0077] Example 3: Preparation of high mechanical strength paintable graphene copper wire and enameled wire I. Complete Technical Solution 1. Copper wire surface pretreatment: Select high-strength copper wire with a diameter of 0.3mm, first pickle it with 8% dilute sulfuric acid for 10 minutes to lightly remove the oxide layer (avoid excessive corrosion that may affect the strength of the copper wire itself); then perform plasma cleaning, set the power to 200W, and the cleaning time to 5 minutes to lightly activate the surface.

[0078] 2. Preparation of functionalized graphene oxide solution: Prepare a GO dispersion with a concentration of 0.3 mg / mL, add a coupling agent at a mass ratio of 100:5 for the graphene oxide dispersion and γ-aminopropyltriethoxysilane, and sonicate at 300 W for 20 minutes to prepare a functionalized GO solution with low coupling agent content.

[0079] 3. Electrochemical reduction deposition: A three-electrode system was constructed, and the pulse current density was set to 1 A / dm², the pulse frequency to 50 Hz, and the deposition time to 30 minutes to form an ultrathin graphene composite layer with a thickness of 1 μm on the surface of the copper wire.

[0080] 4. Graphene copper wire stranding: Take 4 graphene copper wires and strand them concentrically. Apply a constant tension of 3N to ensure that the stranded copper wire bundle is tight and not overstretched.

[0081] 5. Copper foil wrapping: Ultra-thin oxygen-free copper foil with a thickness of 0.01mm is selected. During wrapping, the adhesion is controlled to be ≥98% and the overlap width is 0.5mm to ensure that the copper foil and copper wire bundle are completely bonded.

[0082] 6. Argon arc welding: Set the welding current to 10A, argon flow rate to 5L / min, and welding speed to 50mm / min. Use low current and slow welding to avoid overheating damage to the copper foil.

[0083] 7. Tight bonding treatment: Copper tube drawing process is adopted, and the drawing deformation is set at 30% to improve the interlayer bonding force through large deformation.

[0084] 8. Insulating varnish coating: Use high-adhesion polyimide varnish, each coat is 5μm thick, the curing temperature is 180℃, and the curing time is 10 minutes; repeat the coating 4 times to form an ultra-thin insulating varnish layer with a total thickness of 20μm.

[0085] II. Working Principle 1. Low-damage pretreatment and ultra-thin composite layer: Light pickling avoids excessive corrosion of the copper wire substrate and ensures the high strength of the copper wire itself; 1μm ultra-thin graphene composite layer can be uniformly attached to the surface of the copper wire, which not only exerts the reinforcing effect of graphene, but also avoids interlayer stress caused by excessive thickness of the composite layer (reducing the risk of interlayer peeling under mechanical stress).

[0086] 2. Low coupling agent and precision stranding: The low mass ratio of silane coupling agent can reduce the impact of interfacial chemicals on the mechanical properties of copper wires; the concentric stranding of 4 copper wires and low constant tension can form a tight stranded structure, improve the overall tensile strength, and avoid damage to the copper wires during the stranding process.

[0087] 3. Ultra-thin copper foil and low-current welding: The 0.01mm ultra-thin copper foil is lightweight and flexible, and can be tightly attached to the surface of the stranded wire without adding extra structural stress; the low-current slow welding can precisely control the welding temperature, avoiding the ultra-thin copper foil from melting or becoming brittle due to high temperature, and ensuring the integrity and flexibility of the copper foil layer.

[0088] 4. Large deformation drawing and ultra-thin varnish layer: The 30% large deformation drawing can completely eliminate the interlayer gap between the copper foil and the graphene strand, forming an integrated structure of "copper foil-graphene-copper wire" with a tight bond, which greatly improves the interlayer bonding force; the 20μm ultra-thin insulating varnish layer can reduce the brittle stress of the varnish layer itself and avoid cracking of the varnish layer when mechanically bent.

[0089] III. Experimental Data 1. Tensile strength test: The tensile strength of the enameled wire was tested using a universal testing machine. The breaking load was significantly higher than that of conventional enameled wire of the same specification. There was no interlayer separation when it broke, and the fracture location was the copper wire body.

[0090] 2. Bending performance test: The enameled wire was repeatedly bent on a cylinder with a diameter of 5mm. After 1000 bends, the appearance was observed to show no cracking of the copper foil or peeling of the insulation layer. The conductivity was tested with a resistance tester and the resistance showed no significant change.

[0091] 3. Interlayer bonding strength test: The peel tester was used to test the peel strength between the copper foil layer and the graphene strand. The peel test required a large external force and the copper foil was easy to break, which proved that the interlayer bonding strength was strong.

[0092] 4. Insulation layer bending resistance test: After the bending test, the dielectric loss value of the insulation layer is tested by a dielectric loss meter. The dielectric loss value does not change significantly, which proves that the insulation layer remains intact after bending.

[0093] IV. Technical Effects 1. High tensile and bending strength: Light pretreatment ensures the strength of the copper wire matrix. The reinforcing effect of the ultra-thin graphene composite layer, the tight stranded structure and the interlayer combination of large deformation drawing make the enameled wire have excellent tensile strength. There is no structural damage after repeated bending, which meets the requirements of frequent stress or bending scenarios (such as small motor windings and precision electronic component connecting wires).

[0094] 2. Interlayer structural stability: The low-stress ultra-thin composite layer, high-adhesion copper foil, and strong interlayer bonding force ensure that the enameled wire does not separate under mechanical stress, avoiding the decline in mechanical properties or fluctuations in conductivity caused by interlayer loosening.

[0095] 3. Lightweight and Precision Fit: The ultra-thin copper foil and ultra-thin insulating varnish layer make the overall diameter of the enameled wire small and the weight light, which can be adapted to precision electronic equipment with limited space, while maintaining excellent mechanical and electrical performance and avoiding the impact of excessive size on the integration of the equipment.

[0096] It is worth noting that: To prevent damage to the graphene composite layer due to friction or excessive stretching, in the graphene copper wire stranding step (4), the tension is controlled at 3-8N or an inert environment / minimum lubrication is used.

[0097] In summary, the manufacturing process of the paintable graphene copper wire and the working principle of the enameled wire produced by it provided in this application are as follows: 1. Copper wire surface pretreatment: First, the oxide layer (such as copper oxide and cuprous oxide) on the surface of the copper wire is removed by acid pickling. Then, residual impurities are removed by plasma cleaning, and the surface of the copper wire is activated at the same time. The high-energy particles of the plasma will break some of the chemical bonds on the surface of the copper wire and form active sites, providing an "anchoring basis" for the subsequent attachment of functionalized graphene oxide, and avoiding impurities or oxide layers from affecting the bonding between graphene and copper wire.

[0098] 2. Preparation of Functionalized Graphene Oxide Solution: Graphene oxide itself is prone to agglomeration and has poor compatibility with the surface of copper wires. By adding a silane coupling agent, one end can chemically bond with the hydroxyl and carboxyl groups on the surface of graphene oxide, and the other end can react with the active sites on the surface of copper wires, which is equivalent to building a "bridge" between graphene oxide and copper wires. Ultrasonic treatment can make graphene oxide uniformly dispersed in the solution, avoid agglomeration, and ensure that the graphene layer structure formed by subsequent deposition is dense.

[0099] 3. Electrochemical reduction deposition: The pretreated copper wire is immersed in a functionalized graphene oxide solution as an electrode. When a pulsed current is applied, the graphene oxide is reduced to graphene in situ on the surface of the copper wire. The pulsed current can precisely control the reduction rate, avoiding the graphene layer from being too loose due to excessive reduction in a single step. The resulting graphene composite layer is tightly attached to the surface of the copper wire, which can optimize the electron transport path (improving conductivity) and block heat diffusion (improving heat resistance).

[0100] 4. Graphene copper wire stranding: Using a concentric stranding method and applying constant tension ensures that multiple graphene copper wires form a regular circular cross-section after stranding, avoiding local bulges or depressions; constant tension can prevent some copper wires from being stretched due to excessive force (damaging the graphene layer) or loosened due to insufficient force (affecting the overall structure), providing a flat base for subsequent copper foil coating.

[0101] 5. Copper foil coating and argon arc welding: The surface of graphene copper wire is hydrophobic, while copper foil has good hydrophilicity. Coating with copper foil can directly improve the coating conditions. Argon arc welding of copper foil joints can form a closed tubular structure of copper foil, which can prevent impurities from entering the interlayer in subsequent processes. At the same time, it can ensure that the copper foil completely wraps the graphene copper wire without wrinkles or gaps, further ensuring the uniformity of coating.

[0102] 6. Tight bonding treatment (drawing / rolling): By drawing or rolling copper tubes, mechanical force is used to eliminate the gap between copper foil and graphene copper wire, which greatly improves the interfacial bonding force between the two, avoids the separation of copper foil and graphene copper wire during use, and enhances the overall structural stability of enameled wire.

[0103] 7. Insulating varnish coating: Polyimide or high-temperature resistant epoxy resin varnish is selected. These varnishes have excellent heat resistance. The multi-coat-curing process can eliminate defects such as pinholes and bubbles in single-coat varnishes and form a dense insulating layer. During the curing process, the varnish molecules cross-link to form a stable structure and are tightly bonded to the hydrophilic surface of the copper foil, preventing the insulating layer from aging and peeling.

[0104] How to use: 1. Preliminary preparation: Select oxygen-free copper wire as the substrate (diameter determined according to requirements), prepare dilute sulfuric acid (for acid washing), plasma cleaning equipment, graphene oxide powder, silane coupling agent, ultrasonic equipment, electrodes required for electrochemical deposition (working electrode: pretreated copper wire, counter electrode: platinum sheet, reference electrode: saturated calomel electrode), argon arc welding equipment, oxygen-free copper foil, insulating varnish (polyimide varnish or high-temperature resistant epoxy resin varnish), and coating-curing equipment.

[0105] 2. Copper wire surface pretreatment: The copper wire is placed in dilute sulfuric acid for pickling to remove the surface oxide layer; after pickling, the copper wire is placed in a plasma cleaning device, and the appropriate power and time are set to complete the cleaning and surface activation.

[0106] 3. Preparation of functionalized graphene oxide solution: Prepare a graphene oxide dispersion of a certain concentration, add silane coupling agent in proportion, pour the mixture into an ultrasonic device, set the ultrasonic power and time, and take it out for use after the solution is evenly dispersed.

[0107] 4. Electrochemical reduction deposition: A three-electrode system was set up (the working electrode, counter electrode, and reference electrode were all immersed in a functionalized graphene oxide solution), the pulse current parameters (current density, frequency, and deposition time) were set, the equipment was started to perform deposition, and after the deposition was completed, the graphene copper wire with a graphene composite layer attached to its surface was obtained.

[0108] 5. Graphene copper wire stranding: Take multiple graphene copper wires and place them into the stranding equipment using a concentric stranding method. Turn on the tension controller (apply constant tension) and start the equipment to complete the stranding, resulting in a neat graphene copper wire bundle.

[0109] 6. Copper foil cladding and argon arc welding: Wrap oxygen-free copper foil around the graphene copper wire bundle, ensuring a tight fit (no wrinkles or gaps), and mark the copper foil seams; place the copper wire bundle wrapped with copper foil into the argon arc welding equipment, set the welding parameters (current, argon flow rate, welding speed), and weld the seams to form a closed tubular copper foil layer.

[0110] 7. Tight Bonding Process: If drawing is selected, place the welded copper wire into the drawing equipment, set the drawing deformation amount, and start the equipment to complete the drawing; if rolling is selected, place it into the rolling equipment, set the rolling pressure, and complete the rolling to ensure that the copper foil and the graphene copper wire bundle are tightly bonded.

[0111] 8. Insulating varnish coating: The treated copper wire is placed into the coating equipment and coated with insulating varnish in multiple coats. After each coat, it is placed in a curing oven and the curing temperature and time are set for curing. The coating-curing steps are repeated until the required thickness of the insulating varnish layer is formed, and finally the enameled wire is obtained.

[0112] Overall technical effect: 1. Improved conductivity: By removing the oxide layer and impurities and activating the surface through copper wire pretreatment, combined with the uniform dispersion and electrochemical in-situ reduction deposition of functionalized graphene oxide, the graphene composite layer is tightly and densely attached to the surface of the copper wire. Graphene can optimize the electron transport path and reduce the scattering loss of electrons on the surface of the copper wire, thereby making the conductivity of the enameled wire superior to that of conventional pure copper enameled wire.

[0113] 2. Enhanced heat resistance: The dense graphene composite layer can block heat diffusion and slow down the transfer of heat generated by the copper wire to the insulation layer during operation; at the same time, the selected polyimide or high-temperature resistant epoxy resin paint itself has excellent heat resistance, and the insulation layer structure formed by multiple coating and curing is stable. With the synergistic effect of the two, the insulation layer is not easy to age or crack due to high temperature, ensuring the stable use of enameled wire under high temperature conditions.

[0114] 3. Improved mechanical strength: The tight bonding between the graphene composite layer and the copper wire enhances the tensile strength of the copper wire itself; concentric stranding (with constant tension) makes the graphene copper wire bundle structure regular and without looseness; argon arc welding makes the copper foil form a closed and stable structure; and drawing / rolling further enhances the interfacial bonding force between the copper foil and the graphene copper wire bundle. Each layer works closely together to avoid interlayer separation during use, greatly improves the overall tensile strength of the enameled wire, and reduces the risk of damage during mechanical vibration or installation.

[0115] 4. Solving the painting problem: The hydrophobic surface of graphene copper wires makes it difficult for paint to adhere, while copper foil has good hydrophilicity. By uniformly covering the copper foil and welding it into a closed tube, the contact angle between the paint and the substrate can be significantly reduced. At the same time, the tight bonding between the copper foil and the graphene copper wire bundle prevents the copper foil from loosening during the painting process, ensuring that the insulating paint can be uniformly and firmly adhered to the copper foil surface to form a stable insulating layer, thus solving the core pain point of the existing difficulty in painting graphene copper wires.

[0116] 5. Adaptable to large-scale production: The parameters of electrochemical deposition are highly controllable throughout the process, and continuous production can be achieved by adjusting the current, time, etc. The stranding, copper foil coating, argon arc welding, drawing / rolling, painting and other steps all use conventional equipment (only the parameters need to be adapted), without the need for special and complex equipment. The process cost is controllable and it is easy to promote and apply industrially.

[0117] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for manufacturing paintable graphene copper wire, characterized in that, The method comprises the following steps: (1) Copper wire surface pretreatment: physical or chemical methods are used to remove the oxides and impurities on the surface of the copper wire; (2) Functionalized graphene oxide solution preparation: graphene oxide dispersion liquid is mixed with silane coupling agent, and functionalized graphene oxide solution is obtained through ultrasonic treatment; (3) Electrochemical reduction deposition: the pretreated copper wire is immersed in the functionalized graphene oxide solution, and a pulse current is applied to reduce the graphene oxide to graphene in situ on the surface of the copper wire, form a dense graphene composite layer, and obtain a graphene copper wire; (4) Graphene copper wire twisting: a plurality of graphene copper wires are twisted according to preset twisting parameters; (5) Copper foil cladding: a layer of copper foil is uniformly cladded on the outside of the twisted graphene copper wire; (6) Argon arc welding: argon arc welding is used to weld the joint of the copper foil, so that the copper foil forms a closed tubular structure; (7) Tight combination treatment: the copper wire after welding is subjected to copper pipe drawing or calendering treatment, so that the copper foil and the graphene copper wire are tightly combined; (8) Insulating paint coating: insulating paint is coated on the outside of the tightly combined copper foil, and after curing, an enameled wire is obtained.

2. The paintable graphene copper wire manufacturing process of claim 1, wherein, In step (1), the specific method of copper wire surface pretreatment is: first, acid washing is performed using an acid washing solution, and then plasma cleaning is performed; the acid washing solution is dilute sulfuric acid, and the acid washing time is 10-20 minutes; the power of the plasma cleaning is 200-500 W, and the cleaning time is 5-15 minutes.

3. The paintable graphene copper wire manufacturing process of claim 1, wherein, In step (2), the silane coupling agent is γ-aminopropyl triethoxysilane; the mass ratio of graphene oxide dispersion liquid to silane coupling agent is 100:5-15; the power of the ultrasonic treatment is 300-600 W, and the ultrasonic time is 20-40 minutes.

4. The paintable graphene copper wire manufacturing process of claim 1, wherein, In step (3), the current density of the pulse current is 1-5 A / dm², the pulse frequency is 50-200 Hz, and the deposition time is 30-60 minutes; the thickness of the graphene composite layer is 1-5 μm.

5. The paintable graphene copper wire manufacturing process of claim 1, wherein, In step (5), the material of the copper foil is oxygen-free copper, and the thickness of the copper foil is 0.01-0.05 mm; during cladding, the adhesion of the copper foil to the graphene copper wire is ≥95%, and the overlap width of the copper foil is 0.5-2 mm.

6. The paintable graphene copper wire manufacturing process of claim 1, wherein, In step (6), the welding current of the argon arc welding is 10-30 A, the argon flow rate is 5-15 L / min, and the welding speed is 50-150 mm / min; the welding strength of the joint of the copper foil after welding is ≥20 MPa.

7. The paintable graphene copper wire manufacturing process of claim 1, wherein, In step (7), if copper pipe drawing treatment is used, the deformation amount of the drawing is 10%-30%; if calendering treatment is used, the pressure of the calendering is 5-15 MPa; after the treatment, the bonding force of the copper foil to the graphene copper wire is ≥50 N / m.

8. The paintable graphene copper wire manufacturing process of claim 1, wherein, In step (8), the insulating paint is polyimide paint or high-temperature resistant epoxy resin paint; multi-pass coating-curing process is used for coating, the film thickness of each pass of coating is 5-15 μm, the curing temperature is 180-250 °C, and the curing time is 10-30 minutes; the total thickness of the finally formed insulating paint layer is 20-50 μm.

9. The paintable graphene copper wire manufacturing process of claim 1, wherein, In step (4), the concentric twisting method is used for twisting the graphene copper wire, and a constant tension is applied to each graphene copper wire during the twisting process.

10. An enameled wire, characterized by, The paintable graphene copper wire production process according to any one of claims 1-9; the enameled wire comprises, from inside to outside, a copper wire base, a graphene composite layer, a copper foil layer and an insulating paint layer; the graphene composite layer is a graphene dense layer formed by in-situ reduction of graphene oxide and is tightly attached to the outside of the copper wire base; the copper foil layer is a closed tubular structure and tightly wraps the outside of the graphene composite layer; and the insulating paint layer is tightly attached to the outside of the copper foil layer.

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