Preparation method of high-slip enameled wire and application thereof

Abstract

This invention relates to the field of electrical winding wire preparation technology, specifically to a method for preparing high-slip enameled wire and its application. This invention addresses the aspects of substrate source control, process control, and functional varnish modification: high-purity T1 copper rods are selected, and subsurface defects are strictly controlled through multiple wire drawing processes combined with intermediate pre-annealing; a two-stage finished product annealing process is employed to precisely control the copper conductor grain structure; gradient curing of the bottom layer of polyurethane insulating varnish improves the adhesion of the varnish film; and a functional layer is constructed using a polyether-modified polysiloxane-modified self-lubricating polyamide-imide varnish. The resulting enameled wire has a static friction coefficient ≤0.07, and surface pinholes and particle defects are reduced by more than 90%. This invention solves the problems of high friction, easy varnish film cracking, numerous surface defects, and poor lubrication stability in traditional enameled wires during high-speed automatic winding and vertical winding processes. It can be widely applied to automated winding production in fields such as micromotors, servo motors, and vertical winding transformers.

Description

Technical Field

[0001] This invention relates to the field of electrical winding wire preparation technology, and in particular to a method for preparing high-slip enameled wire and its application. Background Technology

[0002] Enameled wire is a core material for electromagnetic devices such as motors, transformers, and inductors, and its performance directly determines the quality and production efficiency of downstream products. With the automation upgrade of manufacturing, high-speed automatic winding technology has completely replaced traditional manual winding. In fields such as micro motors and servo motors, winding speeds can reach over 3000 rpm. Meanwhile, flat wire vertical winding technology, with its advantages of high slot fill factor and high power density, is widely used in the fields of new energy and industrial electrical systems.

[0003] The above automated winding process places stringent requirements on the performance of enameled wires in all dimensions. However, existing conventional enameled wires have the following core problems that cannot be solved in a coordinated manner in practical applications:

[0004] Inherent defects in the substrate lead to poor surface quality: Current technologies for controlling copper materials focus on purity and size, ignoring the latent defects on the subsurface of copper wires. Continuous grooves, pits, burrs, and other defects on the subsurface will generate a large amount of copper powder during the wire drawing process, ultimately leading to particle and pinhole defects on the surface of the enameled wire. This not only increases local friction during winding but also causes electrical safety problems such as inter-turn breakdown and short circuits. The number of pinholes per 10,000 meters of conventional enameled wire can reach more than 30.

[0005] Insufficient flexibility makes it unsuitable for high-speed deformation conditions: Existing annealing processes cannot achieve precise control of the grain structure of copper conductors. If the annealing temperature is too high, it will easily lead to grain coarsening, while if the temperature is too low, recrystallization will be insufficient. The resulting enameled wire has low elongation and large springback angle. Under the high-frequency bending and stretching conditions of high-speed winding, problems such as enamel film cracking, copper exposure, and wire breakage are very likely to occur, making it unsuitable for winding scenarios with small wire diameter and high speed.

[0006] The lubrication system has inherent defects: Currently, the mainstream lubrication solutions fall into two categories: one is external application of lubricants such as liquid paraffin or solid paraffin, which suffers from poor compatibility with the impregnating varnish and is prone to being precipitated by the refrigerant, clogging the refrigeration system pipes; the other is adding solid lubricants such as molybdenum disulfide or graphite to the insulating varnish, which requires large doses and will severely degrade the mechanical and insulating properties of the varnish film. Existing self-lubricating modification solutions cannot achieve a balance between "low coefficient of friction" and "basic varnish film properties." The static friction coefficient of conventional enameled wire is generally above 0.5, which cannot meet the low friction requirements of high-speed winding.

[0007] Existing technologies mostly involve single-stage modifications, optimizing lubrication performance without addressing substrate defects and flexibility issues, or optimizing annealing processes without resolving lubrication problems. These technologies fail to achieve a synergistic improvement in the surface quality, flexibility, lubricity, and electrical performance of enameled wires, making it difficult to fully adapt to the full-condition requirements of high-speed automated winding.

[0008] Therefore, based on the relevant technologies mentioned above, there is an urgent need to develop a method for preparing high-slip enameled wire and its application. Summary of the Invention

[0009] In view of this, the purpose of this invention is to propose a method for preparing high-slip enameled wire and its application. By controlling the subsurface of the substrate, precisely regulating the two-stage annealing process, and modifying the self-lubricating coating film, this method solves the problems of high friction coefficient, insufficient flexibility, numerous surface defects, and poor lubrication stability of traditional enameled wire, thereby achieving a comprehensive improvement in the overall performance of the enameled wire and meeting the industrial needs of high-speed automatic winding and vertical winding processes.

[0010] To achieve the above objectives, the present invention provides a method for preparing high-slip enameled wire and its application.

[0011] A method for preparing high-slip enameled wire includes the following steps:

[0012] Step S1. Preparation of high-purity, low-defect copper substrate: Select copper with a content ≥99.99% and a total impurity mass fraction ≤350×10⁻⁶. -6 Using high-purity T1 oxygen-free copper rod as raw material, the wire is continuously drawn through 6-12 passes, combined with intermediate online pre-annealing treatment. The copper powder generation rate during the wire drawing process is controlled at ≤0.03 g·h. -1 A copper conductor substrate with dimensional accuracy and no obvious defects on the subsurface was obtained.

[0013] Step S2. Two-stage finished product annealing and cleaning treatment: The copper conductor substrate obtained in step S1 is fed into the annealing furnace of the vertical enameling machine for two-stage gradient finished product annealing. The first-stage annealing temperature is controlled at 540-560℃, the second-stage annealing temperature is controlled at 530-550℃, and the annealing line speed is controlled at 65-75 m·min. -1 ;

[0014] After annealing, the copper conductor is cleaned by ultrasonic cleaning and cooled and dried to remove copper powder and oil residue from the surface, thus obtaining a clean copper conductor.

[0015] Step S3. Gradient curing and coating of the bottom insulating varnish film: The clean copper conductor obtained in step S2 is coated with multiple layers of 155 grade direct solderable polyurethane insulating varnish. After each coating, three stages of gradient baking and curing are performed to form a uniform, dense, and highly adhesive bottom insulating varnish film on the outer surface of the copper conductor, thus obtaining the enameled wire semi-finished product.

[0016] Step S4. Coating and shaping of the self-lubricating outer layer: The enameled wire semi-finished product obtained in step S3 is coated with 1-2 layers of polyether-modified polysiloxane-modified self-lubricating polyamide-imide varnish. After high-temperature baking and curing, a self-lubricating functional layer of uniform thickness is formed on the outside of the bottom insulating varnish film. After post-processing, the enameled wire is obtained.

[0017] Step S5. Online monitoring and finished product collection: The enameled wire processed in step S4 is fed into the online monitoring system to complete the real-time detection of dimensional parameters, electrical performance, static friction coefficient and surface defects, and to remove unqualified products;

[0018] Qualified products are wound up under constant tension control to obtain high-slip enameled wire finished products.

[0019] Preferably, the total mass fraction of harmful impurities O, N, Pb, Bi, Se, and Te in the high-purity T1 oxygen-free copper rod described in step S1 is ≤200 × 10⁻⁶. -6 This reduces the negative impact of impurities on the plasticity and surface quality of copper materials from the source.

[0020] The intermediate online pre-annealing temperature is 350-450℃, and the annealing line speed is 800-1200 m·min. -1 Pre-annealing eliminates internal stress during wire drawing, repairs subsurface micro-damage, and reduces copper powder generation.

[0021] The copper conductor substrate obtained is either a round copper conductor or a flat copper conductor, wherein the round copper conductor has a non-roundness of ≤0.003mm and the flat copper conductor has a dimensional tolerance of ≤±0.005mm.

[0022] Preferably, the optimal process parameters for the two-stage finished product annealing in step S2 are: first-stage annealing temperature 550℃, second-stage annealing temperature 540℃, and annealing linear speed 70m·min. -1 ;

[0023] The copper conductor is uniformly recrystallized by gradient annealing, avoiding abnormal grain coarsening. The resulting copper conductor substrate has an average grain size of 6-8μm, an elongation of ≥42%, and a springback angle of ≤33°, exhibiting excellent flexibility and deformation adaptability.

[0024] Preferably, the polyurethane insulating varnish applied in step S3 is applied in 6-8 coats, and the temperature zones for the three-stage gradient baking and curing are set as follows: low temperature pre-baking zone 180-220℃, medium temperature curing zone 280-320℃, and high temperature setting zone 350-380℃.

[0025] Gradient curing avoids pinholes and sagging defects in the coating film, improves the density and adhesion of the coating film, and the normal breakdown voltage of the cured bottom insulating coating film is ≥1.7kV. After 10% elongation, the coating film does not crack after 1 day of winding. The soldering time at 390℃±5℃ is ≤2s, which far exceeds the industry standard requirements.

[0026] Preferably, the preparation method of the self-lubricating polyamide-imide paint in step S4 is as follows: add polyether-modified polysiloxane at 0.12%-0.50% of the dry weight of the polyamide-imide paint, disperse and stir at 200 r / min for 30 min at room temperature to obtain a uniform and stable self-lubricating paint.

[0027] This formulation does not affect the viscosity, solid content, or film-forming properties of the polyamide-imide paint, while significantly improving the surface lubrication performance of the paint film.

[0028] Preferably, the coating thickness of the self-lubricating functional layer in step S4 is 1-3 μm, and the baking curing temperature is 540-560℃;

[0029] The cured self-lubricating functional layer has an adhesion grade of ≥4B, and the static friction coefficient remains ≤0.10 after wiping with ethanol. It exhibits excellent lubrication performance stability and has no issues with precipitation or poor compatibility.

[0030] Preferably, the post-processing process in step S4 is as follows: the enameled wire is passed into a double-channel constant temperature coating device, and a solvent-free environmentally friendly hot-melt lubricating oil is used for full-surface supplementary coating. The coating temperature is controlled at 50±2℃. After coating, it is dried by low-temperature hot air at 60-80℃ to form an ultra-thin auxiliary lubrication layer outside the self-lubricating functional layer, which further reduces the coefficient of friction and is suitable for heavy-duty lubrication requirements such as flat wire vertical winding.

[0031] The preparation process of the polyether-modified siloxane for the high-slip enameled wire is as follows:

[0032] Step T1. Raw material pretreatment and dehydration: Add allyl polyether to a stainless steel reactor, start stirring, set the speed to 150-200 r / min, purge with high-purity N2 3 times to remove oxygen, heat to 100-110℃, maintain the temperature at a vacuum of -0.095--0.098 MPa for 1.5-2 hours until the moisture content is ≤50ppm, cool to 80℃ for later use. Strictly prevent cross-linking side reactions caused by moisture to obtain dehydrated allyl polyether.

[0033] Step T2. Hydrosilylation reaction: Add side-chain hydrogen-containing silicone oil to the dehydrated allyl polyether at a molar ratio of Si-H:C=C=1:1.05-1.10, stir evenly, add a polymerization inhibitor at a rate of 0.05%-0.1% of the total mass, continue to purge with N2 for protection, raise the temperature to 90-95℃, add Karstedt catalyst dropwise at a rate of 5-10 ppm of the total mass, complete the addition within 30 min, raise the temperature to 100-110℃, and maintain the temperature for 3.5-5 h. Monitor in real time for the disappearance of the infrared absorption peak of the Si-H bond to confirm that the reaction is complete.

[0034] Step T3. Reaction termination and devolatilization purification: Add organic weak acid neutralizing agent, amount 0.01%-0.03%, stir for 30 min to terminate the catalytic reaction, heat to 120-130℃, and devolve under reduced pressure at a vacuum degree of -0.098MPa to remove unreacted monomers and trace amounts of low-boiling substances, keep warm for 2 h, cool to 60-70℃, stop the vacuum, and maintain N2 protection;

[0035] Step T4. Fine filtration: Use a 0.5μm high-precision filter element for pressure filtration to remove mechanical impurities and catalyst colloids, and obtain a clear and transparent polyether-modified siloxane product free of mechanical impurities.

[0036] Preferably, the allyl polyether is allyl polyethylene glycol monomethyl ether, the side-chain hydrogen-containing silicone oil is methyl hydrogen-containing silicone oil, the polymerization inhibitor is p-hydroxyanisole, and the organic weak acid neutralizer is glacial acetic acid.

[0037] Preferably, the real-time detection indicators of the online monitoring system in step S5 include: outer diameter of the enameled wire, thickness of the enamel film, conductor size, breakdown voltage, static friction coefficient, and number of surface particles and pinholes; the resulting high-slip enameled wire has a static friction coefficient ≤0.07, ≤5 particles and ≤1 pinhole per 10,000 meters of enameled wire, and 0 pinholes detected by salt water at 12V for 1 minute, fully meeting the performance requirements of high-speed winding.

[0038] An application of high-slip enameled wire is specifically to apply high-slip enameled wire to the automated fabrication of high-speed automatic winding motor windings, vertically wound transformer coils, and vertically wound inductor coils with a speed ≥3000rpm.

[0039] During high-speed automatic winding, the high-slip enameled wire exhibits no enamel film damage, no copper exposure due to stretching, and no wire breakage. The coil winding yield is ≥99.5%, and the production efficiency is more than 40% higher than that of conventional enameled wire.

[0040] The beneficial effects of this invention are:

[0041] (1) This invention selects high-purity, low-impurity copper materials and, in conjunction with an intermediate pre-annealing process, strictly controls subsurface defects, thereby stabilizing the copper powder generation rate at 0.03 g·h. -1 Within the critical threshold, the number of surface particles and pinholes of the enameled wire produced is reduced by more than 90% per 10,000 meters. This not only significantly improves the electrical safety performance of the product, but also avoids the problem of increased local friction caused by surface defects, providing a basic guarantee for the stable performance of lubrication.

[0042] (2) The optimized two-stage gradient annealing process of this invention can achieve precise control of the grain structure of copper conductors, and the enameled wire produced has an elongation of ≥42% and a springback angle of ≤33°. Under optimal working conditions, the elongation can reach 44.1% and the springback angle is as low as 32.0°, which far exceeds the flexibility level of conventional enameled wires. It is perfectly adapted to the high-frequency bending and stretching conditions in the high-speed winding process, and solves the problems of enamel film cracking, copper exposure and wire breakage.

[0043] (3) The present invention uses polyether-modified polysiloxane-modified polyamide-imide varnish. With a low addition amount of 0.12%-0.50%, the static friction coefficient of the enameled wire surface can be reduced to below 0.07, and the optimal value can reach about 0.06, which is more than 85% lower than that of conventional enameled wire. At the same time, it does not affect the mechanical properties, insulation properties and heat resistance properties of the varnish film, and solves the problems of poor compatibility and easy precipitation of traditional external lubricating oil, and the deterioration of varnish film performance by solid lubricant.

[0044] (4) This invention achieves a comprehensive and synergistic improvement in the surface quality, softness, lubricity and electrical performance of enameled wire through substrate control, process regulation and coating film modification. The preparation process is compatible with existing enameled wire production equipment and can achieve mass production without large-scale production line modification. The products are compatible with existing high-speed automatic winding machines and vertical winding machines. Downstream customers can use them directly without modifying their production lines, which has broad application prospects. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0046] The raw materials and equipment used in the following examples are all commercially available products in the field, and the test methods used all comply with national standards and industry specifications.

[0047] Example 1:

[0048] This embodiment provides a method for preparing a Φ0.150mm high-slip polyurethane enameled round wire, suitable for the production of small-scale covered motors with 3500rpm high-speed automatic winding. The specific steps are as follows:

[0049] S1. Raw material pretreatment and dehydration: Allyl polyether is put into a stainless steel reactor, stirring is started, the speed is set to 150 r / min, high-purity N2 is introduced to replace the oxygen three times, the oxygen is purged, the temperature is raised to 100℃, and the temperature is maintained at -0.095MPa for 1.5h until the moisture content is ≤50ppm. The temperature is then lowered to 80℃ for later use. Crosslinking side reactions caused by moisture are strictly prevented to obtain dehydrated allyl polyether.

[0050] S2. Hydrosilylation reaction: Add side-chain hydrogen-containing silicone oil to the dehydrated allyl polyether at a molar ratio of Si-H:C=C=1:1.05, stir evenly, add a polymerization inhibitor at a rate of 0.05% of the total mass, continue to purge with N2 for protection, heat to 90°C, add Karstedt catalyst at a rate of 5 ppm of the total mass, add over 30 min, heat to 100°C, and maintain the temperature for 3.5 h. Monitor in real time for the disappearance of the infrared absorption peak of the Si-H bond to confirm that the reaction is complete.

[0051] S3. Reaction termination and devolatilization purification: Add 0.01% organic weak acid neutralizing agent, stir for 30 min to terminate the catalytic reaction, heat to 120℃, and devolve under vacuum of -0.098MPa to remove unreacted monomers and trace amounts of low-boiling substances. Keep warm for 2 h, cool to 600℃, stop the vacuum, and maintain N2 protection.

[0052] S4. Fine filtration: Pressurized filtration using a 0.5μm high-precision filter element to remove mechanical impurities and catalyst colloids, resulting in a clear, transparent polyether-modified siloxane product free of mechanical impurities;

[0053] The allyl polyether is allyl polyethylene glycol monomethyl ether, the side-chain hydrogen-containing silicone oil is methyl hydrogen-containing silicone oil, the polymerization inhibitor is p-hydroxyanisole, and the organic weak acid neutralizer is glacial acetic acid.

[0054] S5. Preparation of high-purity, low-defect copper substrate: Copper content ≥ 99.99% and total impurity mass fraction 334.81 × 10⁻⁶ are selected. -6 The raw material is high-purity T1 oxygen-free copper rod, in which the total mass fraction of harmful impurities such as O, N, Pb, and Bi is 185.3 × 10⁻⁶. -6 The wire is drawn through eight continuous drawing processes, followed by an intermediate online pre-annealing treatment at a temperature of 400℃ and a wire speed of 1000 m / min. -1 The copper powder generation rate during the wire drawing process is controlled at 0.024 g·h. -1 A round copper conductor with a diameter of 0.150 mm ± 0.003 mm and a conductor non-roundness of 0.002 mm was obtained.

[0055] S6. Two-stage finished product annealing and cleaning treatment: The obtained round copper conductor is fed into the vertical enameling machine annealing furnace, and the optimal two-stage annealing process is adopted. The first-stage annealing temperature is 550℃, the second-stage annealing temperature is 540℃, and the annealing line speed is 70m·min. -1 After annealing, the copper conductor is ultrasonically cleaned, cooled and dried to remove copper powder and oil residue from the surface, resulting in a clean copper conductor with an average grain size of 6.8 μm, an elongation of 43.5%, and a springback angle of 32.0°.

[0056] S7. Gradient Curing Coating of Underlying Insulating Film: The clean copper conductor is coated with 7 layers of 155-grade direct-soldering polyurethane insulating varnish. Each layer is followed by three stages of gradient baking and curing: a low-temperature pre-baking zone at 200℃, a medium-temperature curing zone at 300℃, and a high-temperature setting zone at 360℃. This forms a 0.020mm thick underlying insulating film on the outside of the copper conductor, producing a semi-finished enameled wire. After curing, the average breakdown voltage of the varnish under normal conditions is 4.48kV. After 10% elongation, the varnish does not crack after 1 day of winding. The soldering time at 390℃ is 2 seconds.

[0057] S8. Self-lubricating outer layer coating and shaping: Polyether-modified polysiloxane is added at 0.50% of the dry weight of polyamide-imide varnish, and dispersed and stirred at 200 r / min for 30 min at room temperature to obtain self-lubricating polyamide-imide varnish; the obtained enameled wire semi-finished product is coated with one layer of self-lubricating varnish with a coating thickness of 2 μm, and cured by baking at 550℃ to form a uniform self-lubricating functional layer outside the bottom insulating varnish film. After post-treatment, the enameled wire is obtained. The post-treatment process is as follows: the enameled wire is passed through a double constant temperature coating device, and solvent-free environmentally friendly hot melt lubricating oil is used for full-surface supplementary coating. The coating temperature is controlled at 50±2℃. After coating, it is dried by low-temperature hot air at 60℃ to form an ultra-thin auxiliary lubricating layer outside the self-lubricating functional layer, which further reduces the friction coefficient and is suitable for heavy-duty lubrication requirements such as flat wire vertical winding.

[0058] S9. Online monitoring and finished product winding: The treated enameled wire is fed into an online monitoring system to detect dimensions, breakdown voltage, static friction coefficient, and surface defects in real time, and unqualified products are rejected; qualified products are wound under constant tension to obtain high-slip enameled round wire finished product with a specification of Φ0.150mm.

[0059] Example 2:

[0060] This embodiment provides a method for preparing a high-slip enameled round wire with a specification of Φ0.800mm, suitable for high-speed winding production of industrial motors. The specific steps are as follows:

[0061] S1. Raw material pretreatment and dehydration: Allyl polyether is put into a stainless steel reactor, stirring is started, the speed is set to 160 r / min, high-purity N2 is introduced to replace the oxygen three times, the oxygen is purged, the temperature is raised to 103℃, and the temperature is maintained at -0.096MPa for 1.6h until the moisture content is ≤50ppm. The temperature is then lowered to 80℃ for later use. Crosslinking side reactions caused by moisture are strictly prevented to obtain dehydrated allyl polyether.

[0062] S2. Hydrosilylation reaction: Add side-chain hydrogen-containing silicone oil to the dehydrated allyl polyether at a molar ratio of Si-H:C=C=1:1.06, stir evenly, add a polymerization inhibitor at a rate of 0.06% of the total mass, continue to purge with N2 for protection, heat to 91°C, add Karstedt catalyst dropwise at a rate of 6 ppm of the total mass, complete the addition within 30 min, heat to 103°C, and react at a constant temperature for 4 h. Monitor in real time for the disappearance of the infrared absorption peak of the Si-H bond to confirm that the reaction is complete.

[0063] S3. Reaction termination and devolatilization purification: Add 0.015% organic weak acid neutralizing agent, stir for 30 min to terminate the catalytic reaction, raise the temperature to 123℃, and devolve under reduced pressure at a vacuum of -0.098MPa to remove unreacted monomers and trace amounts of low-boiling substances. Keep warm for 2 h, cool down to 63℃, stop the vacuum, and maintain N2 protection.

[0064] S4. Fine filtration: Pressurized filtration using a 0.5μm high-precision filter element to remove mechanical impurities and catalyst colloids, resulting in a clear, transparent polyether-modified siloxane product free of mechanical impurities;

[0065] The allyl polyether is allyl polyethylene glycol monomethyl ether, the side-chain hydrogen-containing silicone oil is methyl hydrogen-containing silicone oil, the polymerization inhibitor is p-hydroxyanisole, and the organic weak acid neutralizer is glacial acetic acid.

[0066] S5. Preparation of high-purity, low-defect copper substrate: Copper content ≥ 99.99% and total impurity mass fraction 334.81 × 10⁻⁶ are selected. -6 Using high-purity T1 oxygen-free copper rod as raw material, the wire is processed through 9 continuous drawing steps, combined with intermediate online pre-annealing treatment at a pre-annealing temperature of 420℃ and an annealing line speed of 900m·min. -1 The copper powder generation rate during the wire drawing process is controlled at 0.028 g·h. -1 A round copper conductor with a diameter of 0.800 mm ± 0.003 mm and a conductor non-roundness of 0.002 mm was obtained.

[0067] S6. Two-stage finished product annealing and cleaning treatment: The obtained round copper conductor is passed into the vertical enameling machine annealing furnace. The first-stage annealing temperature is 550℃, the second-stage annealing temperature is 540℃, and the annealing line speed is 70m·min. -1 After annealing, the copper conductor is ultrasonically cleaned, cooled and dried to obtain a clean copper conductor with an average grain size of 7.0 μm, an elongation of 43.3%, and a springback angle of 32.0°.

[0068] S7. Gradient curing and coating of the bottom insulating varnish: The clean copper conductor is coated with 6 layers of 155 grade direct solderable polyurethane insulating varnish. After each coating, three stages of gradient baking and curing are performed: low temperature pre-baking zone 220℃, medium temperature curing zone 320℃, and high temperature setting zone 380℃. A bottom insulating varnish film with a thickness of 0.075mm is formed on the outside of the copper conductor to obtain the enameled wire semi-finished product.

[0069] S8. Self-lubricating outer layer coating and shaping: Polyether-modified polysiloxane is added at 0.28% of the dry weight of polyamide-imide varnish, and dispersed and stirred at 200 r / min for 30 min at room temperature to obtain self-lubricating polyamide-imide varnish; the obtained enameled wire semi-finished product is coated with one layer of self-lubricating varnish with a coating thickness of 2 μm, and cured by baking at 550℃ to form a self-lubricating functional layer. After post-treatment, the enameled wire is obtained. The post-treatment process is as follows: the enameled wire is passed into a double constant temperature coating device, and solvent-free environmentally friendly hot melt lubricating oil is used for full-surface supplementary coating. The coating temperature is controlled at 50±2℃. After coating, it is dried by low-temperature hot air at 65℃ to form an ultra-thin auxiliary lubricating layer outside the self-lubricating functional layer, which further reduces the friction coefficient and is suitable for heavy-duty lubrication requirements such as flat wire vertical winding.

[0070] S9. Online monitoring and finished product take-up: Same as in Example 1, to obtain a finished product of high-slip enameled round wire with a specification of Φ0.800mm.

[0071] Example 3:

[0072] This embodiment provides a method for preparing a Φ1.200mm high-slip enameled round wire, the specific steps of which are as follows:

[0073] S1. Raw material pretreatment and dehydration: Allyl polyether is put into a stainless steel reactor, stirring is started, the speed is set to 180 r / min, high-purity N2 is introduced to replace the oxygen three times, the oxygen is purged, the temperature is raised to 108℃, and the temperature is maintained at -0.097MPa for 1.8h until the moisture content is ≤50ppm. The temperature is then lowered to 80℃ for later use. Crosslinking side reactions caused by moisture are strictly prevented to obtain dehydrated allyl polyether.

[0074] S2. Hydrosilylation reaction: Add side-chain hydrogen-containing silicone oil to the dehydrated allyl polyether at a molar ratio of Si-H:C=C=1:1.08, stir evenly, add a polymerization inhibitor at a rate of 0.09% of the total mass, continue to purge with N2 for protection, heat to 94℃, add Karstedt catalyst dropwise at a rate of 9 ppm of the total mass, complete the addition within 30 min, heat to 109℃, and maintain the temperature for 4.5 h. Monitor in real time for the disappearance of the infrared absorption peak of the Si-H bond to confirm that the reaction is complete.

[0075] S3. Reaction termination and devolatilization purification: Add 0.02% organic weak acid neutralizing agent, stir for 30 min to terminate the catalytic reaction, heat to 128℃, and devolve under reduced pressure at -0.098MPa to remove unreacted monomers and trace amounts of low-boiling substances. Keep warm for 2 h, cool down to 68℃, stop the vacuum, and maintain N2 protection.

[0076] S4. Fine filtration: Pressurized filtration using a 0.5μm high-precision filter element to remove mechanical impurities and catalyst colloids, resulting in a clear, transparent polyether-modified siloxane product free of mechanical impurities;

[0077] The allyl polyether is allyl polyethylene glycol monomethyl ether, the side-chain hydrogen-containing silicone oil is methyl hydrogen-containing silicone oil, the polymerization inhibitor is p-hydroxyanisole, and the organic weak acid neutralizer is glacial acetic acid.

[0078] S5. Preparation of high-purity, low-defect copper substrate: Copper content ≥ 99.99% and total impurity mass fraction 334.81 × 10⁻⁶ are selected. -6 Using high-purity T1 oxygen-free copper rod as raw material, the wire is processed through 12 continuous drawing steps, combined with intermediate online pre-annealing treatment at a pre-annealing temperature of 380℃ and an annealing line speed of 1200m·min. -1 The copper powder generation rate during the wire drawing process is controlled at 0.021 g·h. -1 A round copper conductor with a diameter of 1.200 mm ± 0.005 mm was obtained;

[0079] S6. Two-stage finished product annealing and cleaning treatment: The round copper conductor is passed into the vertical enameling machine annealing furnace. The first-stage annealing temperature is 550℃, the second-stage annealing temperature is 540℃, and the annealing line speed is 70m·min. -1 After annealing, the copper conductor is ultrasonically cleaned, cooled and dried to obtain a clean copper conductor with an average grain size of 7.0 μm, an elongation of 44.1%, and a springback angle of 32.0°.

[0080] S7. Gradient curing coating of the bottom insulating varnish: The clean copper conductor is coated with 8 layers of 155 grade direct solderable polyurethane insulating varnish. After each coating, three stages of gradient baking and curing are performed: low temperature pre-baking zone 180℃, medium temperature curing zone 280℃, and high temperature setting zone 350℃ to obtain the enameled wire semi-finished product.

[0081] S8. Self-lubricating outer layer coating and shaping: Polyether-modified polysiloxane is added at 0.36% of the dry weight of polyamide-imide varnish to prepare self-lubricating polyamide-imide varnish; the prepared enameled wire semi-finished product is coated with two layers of self-lubricating varnish with a total coating thickness of 3μm, and cured by baking at 560℃ to form a self-lubricating functional layer. After post-treatment, the enameled wire is obtained. The post-treatment process is as follows: the enameled wire is passed through a double constant temperature coating device, and solvent-free environmentally friendly hot melt lubricating oil is used for full-surface supplementary coating. The coating temperature is controlled at 50±2℃. After coating, it is dried by low-temperature hot air at 60-80℃ to form an ultra-thin auxiliary lubricating layer outside the self-lubricating functional layer, which further reduces the coefficient of friction and is suitable for heavy-duty lubrication requirements such as flat wire vertical winding.

[0082] S9. Online monitoring and finished product take-up: Same as in Example 1, to obtain a finished product of high-slip enameled round wire with a specification of Φ1.200mm.

[0083] Example 4:

[0084] This embodiment provides a method for preparing a 2.0mm × 0.8mm high-slip polyurethane flat enameled wire, suitable for vertical winding transformer production. The specific steps are as follows:

[0085] S1. Raw material pretreatment and dehydration: Allyl polyether is put into a stainless steel reactor, stirring is started, the speed is set to 200 r / min, high-purity N2 is introduced to replace the oxygen three times, the oxygen is purged, the temperature is raised to 110℃, and the temperature is maintained at -0.098MPa for 2 hours until the moisture content is ≤50ppm. The temperature is then lowered to 80℃ for later use. Crosslinking side reactions caused by moisture are strictly prevented to obtain dehydrated allyl polyether.

[0086] S2. Hydrosilylation reaction: Add side-chain hydrogen-containing silicone oil to the dehydrated allyl polyether at a molar ratio of Si-H:C=C=1:1.10, stir evenly, add a polymerization inhibitor at a rate of 0.1% of the total mass, continue to purge with N2 for protection, heat to 95°C, add Karstedt catalyst dropwise at a rate of 10 ppm of the total mass, complete the addition within 30 min, heat to 110°C, and react at a constant temperature for 5 h. Monitor in real time for the disappearance of the infrared absorption peak of the Si-H bond to confirm that the reaction is complete.

[0087] S3. Reaction termination and devolatilization purification: Add 0.03% organic weak acid neutralizing agent, stir for 30 min to terminate the catalytic reaction, heat to 130℃, and devolve under vacuum of -0.098MPa to remove unreacted monomers and trace amounts of low-boiling substances. Keep warm for 2 h, cool to 70℃, stop vacuum, and maintain N2 protection.

[0088] S4. Fine filtration: Pressurized filtration using a 0.5μm high-precision filter element to remove mechanical impurities and catalyst colloids, resulting in a clear, transparent polyether-modified siloxane product free of mechanical impurities;

[0089] The allyl polyether is allyl polyethylene glycol monomethyl ether, the side-chain hydrogen-containing silicone oil is methyl hydrogen-containing silicone oil, the polymerization inhibitor is p-hydroxyanisole, and the organic weak acid neutralizer is glacial acetic acid.

[0090] S5. Preparation of high-purity, low-defect copper substrate: Copper content ≥ 99.99% and total impurity mass fraction 334.81 × 10⁻⁶ are selected. -6 Using high-purity T1 oxygen-free copper rod as raw material, the wire undergoes 12 continuous flat wire drawing processes, combined with intermediate online pre-annealing treatment at a pre-annealing temperature of 420℃ and an annealing wire speed of 800m·min. -1 The copper powder generation rate during the wire drawing process is controlled at 0.030 g·h. -1 A flat copper conductor with dimensions of 2.0mm × 0.8mm and a tolerance of ±0.005mm was obtained;

[0091] S6. Two-stage finished product annealing and cleaning treatment: The obtained flat copper conductor is passed into the vertical enameling machine annealing furnace. The first-stage annealing temperature is 560℃, the second-stage annealing temperature is 550℃, and the annealing line speed is 65m·min. -1 After annealing, the conductor is ultrasonically cleaned, cooled and dried to obtain a clean flat copper conductor with an elongation of 42.0% and a springback angle of 33.0°.

[0092] S7. Gradient curing and coating of the bottom insulating varnish: The clean flat copper conductor is coated with 6 layers of 155 grade direct solderable polyurethane insulating varnish, combined with three-stage gradient baking and curing, to form a uniform and dense bottom insulating varnish film on the outside of the flat copper conductor, and to obtain the enameled wire semi-finished product.

[0093] S8. Self-lubricating outer layer coating and supplementary lubrication: First, a 0.28% polyether-modified polysiloxane-modified self-lubricating polyamide-imide varnish is applied as a single coating, with a coating thickness of 2μm, and baked and cured at 550℃; then, a double-stage constant temperature coating device is introduced, and solvent-free environmentally friendly hot-melt lubricating oil is used for full-surface supplementary coating at a coating temperature of 50±2℃. After coating, the wire is dried at a low temperature of 70℃ to form an auxiliary lubrication layer. After post-processing, the enameled wire is obtained. The post-processing process is as follows: the enameled wire is introduced into a double-stage constant temperature coating device, and solvent-free environmentally friendly hot-melt lubricating oil is used for full-surface supplementary coating at a coating temperature controlled at 50±2℃. After coating, the wire is dried at a low temperature of 80℃ to form an ultra-thin auxiliary lubrication layer outside the self-lubricating functional layer, further reducing the coefficient of friction and adapting to the heavy-duty lubrication requirements of flat wire vertical winding, etc.

[0094] S9. Online monitoring and finished product winding: Same as in Example 1, to obtain a finished product of high-slip flat enameled wire with specifications of 2.0mm×0.8mm.

[0095] Comparative Example 1:

[0096] This comparative example uses Φ0.150mm polyurethane enameled round wire prepared by conventional processes, serving as a control compared to Example 1. The specific steps are as follows: Ordinary T2 copper rod was used as raw material, with a total impurity mass fraction of 489.11 × 10⁻⁶. -6 After wire drawing, a single-stage 500℃ conventional annealing process is used to obtain a 0.150mm copper conductor; five layers of conventional polyurethane varnish are applied and baked and cured in a single temperature zone to obtain a semi-finished enameled wire; a solvent-based paraffin lubricant is applied and a single layer of felt is applied, and the wire is naturally dried and then wound up to obtain the finished enameled wire.

[0097] Comparative Example 2:

[0098] This comparative example uses Φ0.150mm enameled round wire as the control specification and uses the same high-purity T1 oxygen-free copper rod as the raw material as in Example 1. It undergoes 8 continuous wire drawing processes without intermediate online pre-annealing. The remaining two-stage finished product annealing, ultrasonic cleaning, bottom gradient curing coating, self-lubricating outer coating, post-treatment, online monitoring and winding processes are exactly the same as in Example 1.

[0099] Comparative Example 3:

[0100] This comparative example uses Φ0.150mm enameled round wire as the control specification, and adopts the same copper substrate preparation and intermediate pre-annealing process as in Example 1. After wire drawing, it undergoes single-stage conventional annealing (annealing temperature 500℃, wire speed 70m·min). -1 There is no two-stage gradient temperature control; the remaining cleaning, bottom coating, self-lubricating outer layer, post-treatment, and winding processes are exactly the same as in Example 1.

[0101] Comparative Example 4:

[0102] This comparative example uses Φ0.150mm enameled round wire as the control specification. It adopts the same copper substrate and annealing process as Example 1. The clean copper conductor is coated with 7 layers of 155 grade polyurethane varnish and cured at a constant temperature of 300℃ in a single temperature zone. There is no gradient setting of low temperature pre-baking, medium temperature curing and high temperature shaping. The remaining self-lubricating outer coating, post-treatment and winding process are exactly the same as in Example 1.

[0103] Comparative Example 5:

[0104] This comparative example uses Φ0.150mm enameled round wire as the control specification. It adopts the same copper substrate, annealing, and undercoating process as Example 1. Unmodified ordinary polyamide-imide paint is used to coat the outer layer without adding polyether-modified polysiloxane. The remaining curing, post-treatment, online monitoring, and take-up processes are exactly the same as in Example 1.

[0105] Comparative Example 6:

[0106] This comparative example uses Φ0.150mm enameled round wire as the control specification and adopts the same full process as Example 1, except that the double constant temperature coating and solvent-free lubricant supplementary coating post-treatment steps are omitted, and only the self-lubricating functional layer is retained; the remaining curing, online monitoring and wire take-up processes are exactly the same as in Example 1.

[0107] Performance testing:

[0108] The following performance tests were performed on the products in Examples 1-4 and Comparative Examples 1-5 above:

[0109] All tests were conducted under standard conditions of 23℃±2℃ and 50%±5% relative humidity, and the test methods strictly followed national standards.

[0110] Static friction coefficient: tested using a dynamic and static friction coefficient tester;

[0111] Surface particle / pinhole count: The number of particles per 10,000 meters was counted using an online particle / pinhole detector.

[0112] Elongation: Universal testing machine, tensile rate 3 mm / min;

[0113] Springback angle: Tested by an automatic springback angle tester;

[0114] Normal breakdown voltage: Breakdown voltage tester, room temperature rapid voltage boost test;

[0115] 10% Elongation Winding Test: After the conductor elongates by 10%, wind it for 1 day and visually inspect for cracking of the varnish film;

[0116] Direct soldering time: Solder at 390℃±5℃, record the time for complete melting of the coating film;

[0117] Saltwater pinhole test: 12V voltage, energized for 1 minute, record the number of pinholes.

[0118] The test data are shown in Tables 1-3 below:

[0119] Table 1 Summary of performance test results for Examples 1-3

[0120]

[0121] Table 2 Summary of performance test results for Example 4 and Comparative Examples 1-2

[0122]

[0123] Table 3 Summary of performance test results for Comparative Examples 3-5

[0124]

[0125] Data Analysis:

[0126] As shown in Tables 1-3, the four sets of examples have ≤5 particles and ≤1 pinhole per 10,000 meters, with zero pinholes in the brine solution. Surface defects are reduced by more than 90% compared to conventional enameled wire. The core reason is the use of high-purity T1 copper rods and intermediate online pre-annealing, resulting in a copper powder generation rate ≤0.03 g·h. -1 Eliminate subsurface defects at the source.

[0127] In contrast, Comparative Example 1, which used conventional T2 copper and no pre-annealing, resulted in a sharp increase in the final particle / pinhole count and the most surface defects.

[0128] Comparative Example 2 had no intermediate pre-annealing, which resulted in a large amount of copper powder generated, with the particle / pinhole number being more than 10 times that of Example 1;

[0129] Comparative Examples 3 and 5: The substrate control process was retained, and the surface quality was close to that of the Example;

[0130] In Comparative Example 4, the curing process without gradient resulted in poor density of the final undercoat film and a significant increase in the number of pinholes.

[0131] The products in the four examples exhibit elongation ≥42.0% and springback angle ≤33.0°, demonstrating flexibility far exceeding industry standards and adaptability to high-speed winding and high-frequency deformation. This is due to the two-stage gradient annealing process, which allows for precise control of grain size (6-8μm) and uniform recrystallization without coarsening.

[0132] In contrast, Comparative Example 1, which uses single-stage annealing, resulted in a product with an elongation of only 25.6% and a springback angle of 58°. The wire was hard and brittle, making it unsuitable for high-speed winding.

[0133] Comparative Example 3 uses single-stage annealing: the final product has a 12% decrease in elongation, a 13° increase in springback angle, and a significant deterioration in softness;

[0134] Other comparative examples: The two-stage annealing process was retained, and the softness was not significantly different from that of the examples.

[0135] The static friction coefficient of the products in the four sets of examples is ≤0.068, which is more than 85% lower than that of conventional enameled wire, and the lubrication stability is excellent. The polyether-modified polysiloxane-modified PAI varnish and solvent-free post-treatment achieve ultra-low friction with low addition amounts.

[0136] In contrast, Comparative Example 1, which used paraffin wax as an external coating, resulted in a product with a friction coefficient of 0.532, indicating extremely poor lubricity.

[0137] Comparative Example 5, without self-lubricating modification, resulted in a product with a friction coefficient of 0.112, which is 1.8 times that of the Example, failing to meet the low friction requirements for high-speed winding.

[0138] The other comparative examples: retain the self-lubricating process, and the coefficient of friction is ≤0.071, which meets the requirements for high slippage.

[0139] The products obtained in the four sets of examples have a breakdown voltage ≥4.36kV, no cracking when wound with 10% elongation, and a direct welding time ≤2s, achieving optimal electrical and processing performance. The bottom layer of polyurethane undergoes three-stage gradient curing, resulting in a high-density film with strong adhesion, and optimal synergy between insulation and direct welding performance.

[0140] In contrast, Comparative Example 4, which uses single-temperature zone curing, resulted in a product with a breakdown voltage of <1.7kV, severe winding cracking, and insulation failure.

[0141] Comparative Example 1 exhibits the worst overall performance, with substandard breakdown voltage, winding cracking, and excessive direct soldering time.

[0142] Other comparative examples: The gradient curing process is retained, and the electrical and processing properties are consistent with the examples.

[0143] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

[0144] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for preparing high-slip enameled wire, characterized in that, Includes the following steps: Step S1. Preparation of high-purity, low-defect copper substrate: Select copper with a content ≥99.99% and a total impurity mass fraction ≤350×10⁻⁶. -6 Using high-purity T1 oxygen-free copper rod as raw material, the wire is continuously drawn through 6-12 passes, combined with intermediate online pre-annealing treatment. The copper powder generation rate during the wire drawing process is controlled at ≤0.03 g·h. -1 A copper conductor substrate was prepared. Step S2. Two-stage finished product annealing and cleaning treatment: The copper conductor substrate obtained in step S1 is fed into the annealing furnace of the vertical enameling machine for two-stage gradient finished product annealing. The first-stage annealing temperature is controlled at 540-560℃, the second-stage annealing temperature is controlled at 530-550℃, and the annealing line speed is controlled at 65-75 m·min. -1 After annealing, the copper conductor is obtained by ultrasonic cleaning, cooling and drying. Step S3. Gradient curing and coating of the bottom insulating varnish: The clean copper conductor obtained in step S2 is coated with multiple layers of 155 grade direct solderable polyurethane insulating varnish. After each coating, three stages of gradient baking and curing are performed to form a bottom insulating varnish film on the outer surface of the copper conductor, and the enameled wire semi-finished product is obtained. Step S4. Coating and shaping of the self-lubricating outer layer: The enameled wire semi-finished product obtained in step S3 is coated with 1-2 layers of self-lubricating polyamide-imide varnish modified with polyether and polysiloxane. After high-temperature baking and curing, a self-lubricating functional layer of uniform thickness is formed on the outside of the bottom insulating varnish film. After post-processing, the enameled wire is obtained. Step S5. Online monitoring and finished product collection: The enameled wire processed in step S4 is fed into the online monitoring system to complete the real-time detection of dimensional parameters, electrical performance, static friction coefficient and surface defects, and to remove unqualified products; Qualified products are wound up under constant tension control to obtain high-slip enameled wire finished products.

2. The method for preparing high-slip enameled wire according to claim 1, characterized in that, In step S1, the total mass fraction of harmful impurities O, N, Pb, Bi, Se, and Te in the high-purity T1 oxygen-free copper rod is ≤200×10⁻⁶. -6 ; The intermediate online pre-annealing temperature is 350-450℃, and the annealing line speed is 800-1200 m·min. -1 ; The copper conductor substrate obtained is either a round copper conductor or a flat copper conductor, wherein the round copper conductor has a non-roundness of ≤0.003mm and the flat copper conductor has a dimensional tolerance of ≤±0.005mm.

3. The method for preparing high-slip enameled wire according to claim 1, characterized in that, The process parameters for the two-stage finished product annealing in step S2 are: first-stage annealing temperature 550℃, second-stage annealing temperature 540℃, and annealing linear speed 70m·min. -1 ; The obtained copper conductor substrate has an average grain size of 6-8 μm, an elongation of ≥42%, and a springback angle of ≤33°.

4. The method for preparing high-slip enameled wire according to claim 1, characterized in that, In step S3, the multi-coat 155 grade direct-weldable polyurethane insulating varnish is applied in 6-8 coats, and the temperature zones for the three-stage gradient baking and curing are set as follows: low temperature pre-baking zone 180-220℃, medium temperature curing zone 280-320℃, and high temperature setting zone 350-380℃. The cured bottom insulating varnish film has a normal breakdown voltage of ≥1.7kV, does not crack after being wound for 1 day after 10% elongation, and has a soldering time of ≤2s at 390℃±5℃.

5. The method for preparing high-slip enameled wire according to claim 1, characterized in that, The preparation method of the self-lubricating polyamide-imide paint in step S4 is as follows: add polyether-modified polysiloxane at 0.12%-0.50% of the dry weight of the polyamide-imide paint, disperse and stir at 200r / min for 30min at room temperature to obtain a uniform and stable self-lubricating polyamide-imide paint.

6. The method for preparing high-slip enameled wire according to claim 1, characterized in that, The coating thickness of the self-lubricating functional layer in step S4 is 1-3 μm, and the high-temperature baking curing temperature is 540-560℃.

7. The method for preparing high-slip enameled wire according to claim 1, characterized in that, The post-processing steps described in step S4 are as follows: The enameled wire is passed into a double-channel constant temperature coating device, and a solvent-free environmentally friendly hot-melt lubricating oil is used for full-surface supplementary coating. The coating temperature is controlled at 50±2℃. After coating, it is dried with low-temperature hot air at 60-80℃ to form an ultra-thin auxiliary lubrication layer outside the self-lubricating functional layer.

8. The method for preparing high-slip enameled wire according to claim 1, characterized in that, The real-time detection indicators of the online monitoring system mentioned in step S5 include: outer diameter of enameled wire, thickness of enamel film, conductor size, breakdown voltage, static friction coefficient, and number of surface particles and pinholes.

9. An application of a high-slip enameled wire prepared by the preparation method according to any one of claims 1-8, characterized in that, The high-slip enameled wire is applied to the automated fabrication of high-speed automatic winding motor windings, vertically wound transformer coils, and vertically wound inductor coils with a speed ≥3000rpm.

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