220-grade corona-resistant polyimide enameled copper round wire for new energy driving motor and production method thereof

Abstract

The application discloses a 220-grade corona-resistant polyimide enameled copper round wire for a new energy driven motor and a production method thereof. The copper round wire comprises a copper conductor and a plurality of enameled layers coated on the copper conductor. The interface between adjacent enameled layers is in a wave shape. The surface of the outermost enameled layer is provided with a spiral shallow groove. The enameled layers comprise, from inside to outside, a primer layer, a gradient corona-resistant layer, an interface transition layer and a topcoat layer. The production method comprises the following steps: conductor pretreatment, primer layer coating, gradient corona-resistant layer coating, interface transition layer coating, topcoat layer coating and post-treatment. The gradient corona-resistant layer coating adopts multi-pass coating to form a gradient corona-resistant layer, which comprises an inner sublayer, a middle sublayer and an outer sublayer, and is respectively added with nano inorganic fillers and polyimide nanofibers. Through the synergistic design of the wave-shaped interface between layers, the nanofiber network in the enameled layer and the surface spiral shallow groove, the application solves the technical problems of easy peeling between layers, insufficient corona resistance and low heat dissipation efficiency in the prior art.

Description

Technical Field

[0001] This invention relates to the field of enameled wire technology, and in particular to 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motors and its production method. Background Technology

[0002] New energy drive motors employ variable frequency speed control technology. The high-frequency pulse voltage output by the inverter can cause severe partial discharge (corona) at the winding ends. At the same time, the motor operates at high temperatures (up to 220℃), experiences frequent thermal cycles (-40℃ to 220℃), and is in long-term contact with cooling media such as ATF oil. This places stringent requirements on the corona resistance, thermal cycling reliability, and oil-resistant heat dissipation performance of the enameled wire.

[0003] The existing 220-grade corona-resistant polyimide enameled wires have the following main problems: First, the interface between the enamel layers is a flat plane, resulting in insufficient interlayer bonding and easy peeling after long-term thermal cycling; second, the corona-resistant filler is uniformly distributed in the enamel layer, which cannot simultaneously meet the multiple requirements of thermal conductivity, corona resistance, and surface hardness; third, the enamel film surface is smooth, resulting in limited heat dissipation efficiency; and fourth, the enamel film lacks an effective crack-blocking mechanism, so once corona damage causes cracks, they propagate rapidly.

[0004] Therefore, there is an urgent need to develop a 220-grade polyimide enameled copper round wire with excellent corona resistance, interlayer bonding strength, and heat dissipation capacity, as well as its corresponding production method. Summary of the Invention

[0005] The purpose of this invention is to provide a 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motors and a production method thereof. This invention solves the technical problems of easy peeling between enameled wire layers, insufficient corona resistance, and low heat dissipation efficiency in existing technologies through the synergistic design of interlayer wavy interfaces, nanofiber networks within the enamel layer, and spiral shallow grooves on the surface.

[0006] The technical solution of the present invention:

[0007] The 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motors includes a copper conductor and multiple layers of enamel coating covering the copper conductor. The interface between adjacent enamel coating layers is a wavy shape extending along the axial direction. The surface of the outermost enamel coating layer is provided with a spiral shallow groove. The multiple enamel coating layers include, from the inside out, a primer layer, a gradient corona-resistant layer, an interface transition layer, and a topcoat layer.

[0008] In the aforementioned 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motors, the thickness of the primer layer is 3-8 μm, the thickness of the gradient corona-resistant layer is 15-30 μm, the thickness of the interface transition layer is 2-5 μm, and the thickness of the topcoat layer is 3-6 μm.

[0009] In the aforementioned 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motors, the depth of the spiral shallow groove is 30%-50% of the thickness of the topcoat layer, the pitch is 0.5-2mm, and the helix angle is 15°-45°; the spiral shallow groove is a single helix or a double helix.

[0010] In the aforementioned 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motors, the height of the wave crest is 15%-30% of the thickness of the corresponding enamel layer, and the wavelength is 0.5-2mm.

[0011] A method for producing 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motors includes the following steps:

[0012] S1. Conductor pretreatment: The copper rod is drawn to the target diameter and then annealed online to obtain a copper conductor.

[0013] S2, Primer coating: Polyamide-imide primer is coated on the surface of the copper conductor. The primer contains polyether block copolymer and polyimide nanofibers. After coating, it is semi-cured. Then, a wavy pattern is pressed on the surface of the primer layer by an embossing mold and then cured.

[0014] S3. Gradient corona-resistant layer coating: A gradient corona-resistant layer is formed by multiple coating passes. The gradient corona-resistant layer includes an inner sublayer, a middle sublayer, and an outer sublayer, which are respectively filled with nano-inorganic fillers and polyimide nanofibers. The content of the nano-inorganic fillers changes in a gradient from the inside to the outside. After each coating pass, a semi-curing treatment is performed, and a wavy pattern is pressed on the surface using an embossing mold. Finally, it is cured.

[0015] S4. Interface transition layer coating: Apply silicone-modified polyamide-imide transition paint to the surface of the gradient corona resistant layer, perform semi-curing treatment, and then press wavy patterns on the surface using an embossing mold.

[0016] S5. Topcoat coating: Polyamide-imide topcoat is coated on the surface of the interface transition layer. Fluorinated graphene microsheets and polyimide nanofibers are added to the topcoat. After semi-curing, spiral shallow grooves are opened on the surface of the topcoat, and finally it is fully cured.

[0017] S6. Post-processing: Online detection and cable recovery.

[0018] In the aforementioned method for producing 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motors, in step S2, the content of the polyether block copolymer is 5-10 wt%, the content of the polyimide nanofibers is 1-2 wt%, the fiber diameter is 50-200 nm, and the length is 5-20 μm; the semi-curing temperature is 280-320℃, and the time is 2-4 s; the peak height of the wavy texture of the primer layer is 15-25% of the thickness of the primer layer, and the wavelength is 0.5-2 mm; after embossing, the layer is fully cured at 380-420℃ for 3-5 s.

[0019] In the aforementioned production method of 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motors, the embossing mold is an annular mold with wavy protrusions on the surface. The wavy protrusions extend along the axial direction of the mold, the height of the protrusions is 15-30% of the corresponding paint layer thickness, and the protrusion spacing is 0.5-2mm.

[0020] In the aforementioned method for producing 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motors, in step S3, the content of nano-Al2O3 in the inner sublayer is 5-8 wt%, and the content of polyimide nanofibers is 1-2 wt%; the content of nano-Al2O3 in the middle sublayer is 10-15 wt%, and the content of polyimide nanofibers is 2-3 wt%; the content of nano-SiO2 in the outer sublayer is 3-5 wt%, and the content of polyimide nanofibers is 0.5-1 wt%; the nano-inorganic filler is surface-modified with a silane coupling agent.

[0021] In the aforementioned method for producing 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motors, step S3 specifically includes:

[0022] Apply 2-3 coats of inner layer paint, with each coat applied to the outer surface of the primer layer, naturally replicating the wavy pattern on the outer surface of the primer layer on the inner surface; after coating, semi-cur at 280-320℃ for 2-4 seconds, and then press the wavy pattern onto the outer surface of the inner layer using an embossing mold.

[0023] Apply 2-4 coats of intermediate layer paint, with each coat applying intermediate layer paint to the outer surface of the inner layer, naturally replicating the wavy pattern of the outer surface of the inner layer on the inner surface; after coating, semi-cur at 320-380℃ for 2-4 seconds, and press the wavy pattern on the outer surface of the intermediate layer using an embossing mold.

[0024] Apply 1-3 coats of outer sublayer paint, with each coat applying the outer sublayer paint to the outer surface of the middle sublayer, and the inner surface naturally replicating the wavy pattern of the outer surface of the middle sublayer; after coating, semi-cur at 380-420℃ for 2-4 seconds, and press the wavy pattern on the outer surface of the outer sublayer using an embossing mold.

[0025] Finally, cure completely at 420-450℃ for 5-8 seconds.

[0026] In the aforementioned method for producing 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motors, in step S4, the silicone content in the silicone-modified polyamide-imide transition varnish is 10-15 wt%, the semi-curing temperature is 320-380℃, and the time is 2-4 s.

[0027] In the aforementioned method for producing 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motors, in step S5, the content of the fluorinated graphene microsheets is 0.5-2wt%, the sheet diameter is 0.5-2μm, and the thickness is 3-5nm; the content of the polyimide nanofibers is 0.5-1wt%.

[0028] In the aforementioned method for producing 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motors, grooving is performed in step S5 by means of laser or other methods.

[0029] Compared with the prior art, the beneficial effects of this application are as follows:

[0030] 1. The wavy interface between layers increases the contact area between adjacent paint film layers, forming a mechanical interlocking effect and significantly improving the interlayer bonding strength; at the same time, the wavy interface extends the travel path of corona damage, so that corona discharge needs to bypass the peaks and troughs to penetrate the paint film.

[0031] 2. The polyimide nanofibers within the paint layer form a three-dimensional entangled network, acting as a bridge. When microcracks occur inside the paint layer, the nanofibers cross the two sides of the crack, preventing the crack from propagating. At the same time, the nanofibers increase the toughness of the paint layer and absorb the stress generated by thermal cycling.

[0032] 3. The spiral shallow grooves on the surface of the topcoat layer increase the surface area of ​​the enameled wire, thereby improving heat dissipation efficiency; the spiral shallow grooves change the surface electric field distribution, reducing local electric field concentration; at the same time, the spiral shallow grooves act as stress relief textures, alleviating thermal stress concentration.

[0033] 4. The wavy interface, nanofiber network and spiral shallow groove work synergistically. The wavy interface disperses stress and extends the corona path on a macroscopic level, the nanofiber bridges cracks and enhances toughness on a microscopic level, and the spiral shallow groove increases heat dissipation and releases stress on the surface, thus achieving a simultaneous improvement in corona resistance, interlayer bonding strength and heat dissipation capacity. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of the enameled wire of the present invention;

[0035] Figure 2 This is a schematic cross-sectional view of the enameled wire of the present invention;

[0036] Figure 3This is a top view of the surface of the enameled wire of the present invention;

[0037] Figure 4 This is a flowchart of the production method of the present invention.

[0038] The markings in the attached diagram are: 1-copper conductor, 2-primer layer, 3-gradient corona resistant layer, 4-interface transition layer, 5-topcoat layer, 6-spiral shallow groove. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0040] Example 1.

[0041] 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motors, such as... Figure 1-3 As shown, it includes a copper conductor 1 and a multilayer coating layer covering the copper conductor 1. The interface between adjacent coating layers is a wavy shape extending along the axial direction. The surface of the outermost coating layer is provided with a spiral shallow groove 6. The multilayer coating layer includes, from the inside to the outside, a primer layer 2, a gradient corona resistant layer 3, an interface transition layer 4, and a topcoat layer 5.

[0042] Production method of 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motors, specification Φ1.0mm, such as... Figure 4 The steps are as follows:

[0043] S1. Conductor pretreatment: T2 grade oxygen-free copper rod is drawn to Φ1.0mm and annealed online (temperature 500℃, nitrogen protection).

[0044] S2, Primer Layer 2 Coating: Polyamide-imide primer (32% solids content, with 8 wt% polytetrahydrofuran glycol and 1.5 wt% polyimide nanofibers, fiber diameter 100 nm, length 10 μm) is applied using a felt coating mold; after coating, it is semi-cured at 300℃ for 3 s, and then a wavy pattern is pressed onto the primer surface using an embossing mold (the inner surface of the wavy protrusions has a height of 1 μm and a wavelength of 1 mm); finally, it is cured at 400℃ for 4 s.

[0045] S3, Gradient Corona Resistant Layer 3 Coating: Coated in three sub-layers:

[0046] Inner layer: PI paint (28% solid content) + 6wt% nano Al2O3 (30nm, KH-550 modified) + 1.5wt% polyimide nanofibers, coated in 2 coats, each coat semi-cured at 300℃ for 3s, embossed (wave height 1.5μm, wavelength 1mm).

[0047] Intermediate layer: PI paint (28% solid content) + 12wt% nano Al2O3 (80nm, KH-550 modified) + 2.5wt% polyimide nanofibers, coated in 3 coats, each coat semi-cured at 350℃ for 3s, embossed (wave height 2μm, wavelength 1mm).

[0048] Outer layer: PI paint (28% solid content) + 4wt% nano SiO2 (20nm, KH-570 modified) + 0.8wt% polyimide nanofibers, coated in 2 coats, each coat semi-cured at 400℃ for 3s, embossed (wave height 1.5μm, wavelength 1mm).

[0049] Finally, it was cured at 430℃ for 6 seconds;

[0050] S4, Interface transition layer 4 coating: Use silicone-modified PAI paint (silicone content 12%, solid content 28%), apply 1 coat, semi-cur at 350℃ for 3s, and emboss (wave height 1μm, wavelength 1mm).

[0051] S5, Topcoat Layer 5: Apply two coats of PAI topcoat (32% solids content, with 1 wt% fluorinated graphene microflakes and 0.6 wt% polyimide nanofibers added); each coat is semi-cured at 420℃ for 4 seconds, then spiral shallow grooves are created using a laser; finally, it is fully cured at 420℃ for 5 seconds.

[0052] S6. Post-processing: Laser diameter gauge monitors outer diameter (1.18-1.20mm), and high-frequency spark tester (6kV) detects pinholes.

[0053] Performance testing:

[0054] Corona resistance life (20kHz, 2kV, 155℃): 185h;

[0055] Interlayer peel strength (180° peel): 8.5 N / cm;

[0056] Thermal shock (-40℃ / 2h ↔ 220℃ / 2h): No cracking after 55 cycles;

[0057] Paint film adhesion (cross-cut test): Grade 0;

[0058] Breakdown voltage: ≥9.5kV;

[0059] Surface heat dissipation coefficient (infrared thermal imager): 22% higher than that of a smooth surface.

[0060] Example 2. The new energy drive motor uses 220-grade corona-resistant polyimide enameled copper round wire, which is the same as in Example 1, except that the spiral shallow groove 6 adopts a left-right double helix.

[0061] Performance testing: Corona resistance life 172h, interlayer peel strength 8.0N / cm, no cracking after 52 thermal shocks.

[0062] Example 3. 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motors, the same as in Example 1, except that the polyimide nanofiber content in step S3 of the production method is 2wt% (without gradient).

[0063] Performance testing: Corona resistance life 168h, interlayer peel strength 8.2N / cm.

[0064] Comparative Example 1: The difference from Example 1 is that there is no wavy interface (flat interface), no spiral groove, and no nanofibers.

[0065] Performance testing: Corona resistance life 55h, interlaminar peel strength 4.2N / cm, cracking after 18 thermal shocks.

[0066] Comparative Example 2: The difference from Example 1 is that it has a wavy interface and spiral grooves, but no nanofibers.

[0067] Performance testing: Corona resistance life 125h, interlaminar peel strength 6.5N / cm, cracking after 38 thermal shocks.

[0068] Comparative Example 3: The difference from Example 1 is that it has nanofibers, but no wavy interface and spiral groove.

[0069] Performance testing: Corona resistance life 140h, interlaminar peel strength 5.8N / cm, cracking after 42 thermal shocks.

[0070] As can be seen from the above embodiments and comparative examples, the wavy interface, spiral heat dissipation grooves, and nanofiber network have a significant synergistic effect, and none of them can be omitted.

Claims

1. A 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motor, characterized in that: It includes a copper conductor (1) and a multilayer coating layer covering the copper conductor (1). The interface between adjacent coating layers is a wavy shape extending along the axial direction. The surface of the outermost coating layer is provided with a spiral shallow groove (6). The multilayer coating layer includes, from the inside to the outside, a primer layer (2), a gradient corona resistant layer (3), an interface transition layer (4), and a topcoat layer (5). ​ 2. The 220-grade corona-resistant polyimide enameled copper round wire for new energy driving motor according to claim 1, characterized in that: The thickness of the primer layer (2) is 3-8 μm, the thickness of the gradient corona resistant layer (3) is 15-30 μm, the thickness of the interface transition layer (4) is 2-5 μm, and the thickness of the topcoat layer (5) is 3-6 μm.

3. The 220-grade corona-resistant polyimide enameled copper round wire for new energy driving motor according to claim 2, characterized in that: The depth of the spiral shallow groove (6) is 30%-50% of the thickness of the topcoat layer (5), the pitch is 0.5-2mm, and the helix angle is 15°-45°.

4. The method for producing enameled copper round wire according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Conductor pretreatment: The copper rod is drawn to the target diameter and then annealed online to obtain a copper conductor (1). S2, Primer layer (2) coating: Polyamide-imide primer is coated on the surface of copper conductor (1). The primer contains polyether block copolymer and polyimide nanofiber. After coating, semi-curing treatment is performed, and then wavy patterns are pressed on the surface of primer layer (2) by embossing mold for curing. S3, Gradient corona resistant layer (3) coating: The gradient corona resistant layer (3) is formed by multiple coating passes. The gradient corona resistant layer (3) includes an inner sublayer, a middle sublayer and an outer sublayer, which are respectively filled with nano-inorganic fillers and polyimide nanofibers. The content of the nano-inorganic fillers changes in a gradient from the inside to the outside. After each coating pass, a semi-curing treatment is performed, and a wavy pattern is pressed on the surface by an embossing mold. Finally, it is cured. S4, Interface transition layer (4) coating: Apply silicone-modified polyamide-imide transition paint to the surface of gradient corona resistant layer (3), perform semi-curing treatment, and then press wavy patterns on the surface using an embossing mold. S5, Topcoat layer (5) coating: Polyamide-imide topcoat is coated on the surface of the interface transition layer (4). Fluorinated graphene microsheets and polyimide nanofibers are added to the topcoat. After semi-curing, spiral shallow grooves (6) are opened on the surface of the topcoat. Finally, it is fully cured. S6. Post-processing: Online detection and cable recovery.

5. The method for producing 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motors according to claim 4, characterized in that: In step S2, the content of the polyether block copolymer is 5-10 wt%, the content of the polyimide nanofiber is 1-2 wt%, the fiber diameter is 50-200 nm, and the length is 5-20 μm; the semi-curing temperature is 280-320℃, and the time is 2-4 s.

6. The method for producing 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motors according to claim 4, characterized in that: In step S3, the content of nano-Al2O3 in the inner sublayer is 5-8 wt%, and the content of polyimide nanofibers is 1-2 wt%; the content of nano-Al2O3 in the middle sublayer is 10-15 wt%, and the content of polyimide nanofibers is 2-3 wt%; the content of nano-SiO2 in the outer sublayer is 3-5 wt%, and the content of polyimide nanofibers is 0.5-1 wt%; the nano-inorganic filler is surface modified with a silane coupling agent.

7. The method for producing 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motors according to claim 4, characterized in that: In step S4, the silicone content in the silicone-modified polyamide-imide transition paint is 10-15 wt%, the semi-curing temperature is 320-380℃, and the time is 2-4 s.

8. The method for producing 220-grade corona-resistant polyimide enameled copper round wire for new energy drive motors according to claim 4, characterized in that: In step S5, the content of the fluorinated graphene microsheets is 0.5-2wt%, the sheet diameter is 0.5-2μm, and the thickness is 3-5nm; the content of the polyimide nanofibers is 0.5-1wt%.

Images