Insulated electric wire, coil, and electronic / electrical device
By combining modified resin layers and thermoplastic resin layers, the interfacial stress problem caused by the difference in thermal expansion coefficients between the conductor and the external PEEK resin is solved, thereby improving the thermal cycling stability and breakdown voltage of the insulated wire.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WELL ASCENT ELECTRONIC (GANZHOU) CO LTD
- Filing Date
- 2026-05-07
- Publication Date
- 2026-06-05
AI Technical Summary
The large difference in linear thermal expansion coefficients between the conductor and the external PEEK resin in existing insulated wires leads to the accumulation of interfacial stress under thermal cycling, resulting in microcracks and reduced BDV.
A modified resin layer, comprising a matrix resin and modified inorganic fillers, is used. The modified inorganic filler is melt-extruded and coated with a compatible resin layer. The linear thermal expansion coefficient of the modified resin layer is adjusted to be close to that of a conductor. A thermoplastic resin layer is added on the outside to distribute the temperature evenly.
It improves the deformation consistency of insulated wires under thermal cycling, avoids the formation of microcracks, and improves BDV retention and flexibility.
Smart Images
Figure CN122158233A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of wire and cable technology, and particularly relates to an insulated wire, coil and electronic / electrical equipment. Background Technology
[0002] Polyetheretherketone (PEEK) resin can be used as the insulation layer for insulated wires. The linear coefficient of thermal expansion (CTE) of PEEK resin at 23°C is 55 ppm / K, while the CTEs of commonly used conductors, such as copper, aluminum, and silver, at room temperature are: copper 17 ppm / K; aluminum 23 ppm / K; copper-aluminum alloys 17-23 ppm / K; and silver 18.5 ppm / K. The significant difference in CTEs between the conductor and the PEEK resin insulation layer leads to stress accumulation at the interface during use, resulting in microcracks. These microcracks become electric field concentration points, causing partial discharge (PD) and ultimately reducing the breakdown voltage (BDV).
[0003] In existing technologies, adjusting the linear thermal expansion coefficient by adding inorganic fillers often faces problems such as uneven filler dispersion, poor interfacial bonding, and decreased flexibility. Therefore, there is an urgent need for an insulated wire with an outer insulation layer whose linear thermal expansion coefficient is close to that of commonly used conductors and whose inorganic fillers are evenly dispersed, so that it can still have a high BDV retention rate after bending and thermal shock. Summary of the Invention
[0004] This application provides an insulated wire, including a conductor and a modified resin layer covering the outside of the conductor, wherein the average linear thermal expansion coefficient of the modified resin layer is 18~50ppm / K.
[0005] Furthermore, the modified resin layer is obtained by melt extrusion molding of modified resin, wherein the modified resin comprises a matrix resin and modified inorganic fillers.
[0006] Furthermore, the modified inorganic filler accounts for less than 30 wt% of the total mass of the modified resin.
[0007] Furthermore, the modified inorganic filler accounts for 5wt% to 30wt% of the total mass of the modified resin.
[0008] Furthermore, the matrix resin includes a first resin and a second resin; The first resin is polyetheretherketone, and the polyetheretherketone accounts for more than 50 wt% of the total mass of the matrix resin; The second resin is at least one of polyether diphenyl ether ketone, polyether o-ether ketone, polyether ketone, polyether ketone ketone, polyether ether ketone-polyether diphenyl ether ketone, polyether ether ketone-polyether o-ether ketone, and polyether diphenyl ether ketone-polyether o-ether ketone.
[0009] Furthermore, the modified inorganic filler is an inorganic filler whose outer surface is at least partially coated with a compatible resin layer.
[0010] Furthermore, the compatibility resin layer accounts for 0.5-5 wt% of the total mass of the modified inorganic filler, and the resin constituting the compatibility resin layer is a polyetherketone resin.
[0011] Furthermore, the polyetherketone resin is phenolphthalein-based polyaryletherketone.
[0012] Furthermore, the inorganic packing includes a first packing and a second packing. The first filler is talc; The second filler is one or more of the following: boron nitride, mica, silicon dioxide, titanium dioxide, molybdenum disulfide, titanium oxide, aluminum oxide, calcium sulfate, calcium carbonate, ferrite, clay, glass powder, zinc oxide, nickel carbonate, iron oxide, quartz powder, magnesium carbonate, fluorocarbon resin, graphite, graphene, graphene oxide, carbon powder, ceramic powder, metal powder, flame retardant powder, nanotubes, and barium sulfate.
[0013] Further, the first filler accounts for 0.1-30 wt% of the total mass of the modified resin, and the second filler accounts for 0.1-30 wt% of the total mass of the modified resin.
[0014] Furthermore, the particle size of the inorganic filler satisfies: D90 < 1 μm.
[0015] Furthermore, at least one thermoplastic resin layer is also included on the outside of the modified resin layer.
[0016] Furthermore, the linear coefficient of thermal expansion of the thermoplastic resin layer is greater than or equal to the linear coefficient of thermal expansion of the modified resin layer. In another aspect, this application proposes a coil composed of insulated wires as described in any of the above-mentioned technical solutions, or insulated wires prepared by the method for preparing insulated wires according to any of the above-mentioned technical solutions.
[0017] In another aspect, this application proposes an electronic / electrical device, characterized in that it includes the coil described above.
[0018] The above-described technical solution of the present invention has at least the following beneficial technical effects: The modified resin layer (insulation layer) of the insulated wire of this application has a linear thermal expansion coefficient close to that of common conductors. During heating and cooling, the difference in deformation between the two is small, for example, they have the same elongation and the same shrinkage. There is almost no stress between them due to deformation, so gaps between them can be avoided, and microcracks in the modified resin layer can also be avoided. Attached Figure Description
[0019] Figure 1This is a cross-sectional structural diagram (I) of the insulated wire of the present invention. Figure 2 This is a schematic cross-sectional view (II) of the insulated wire of the present invention.
[0020] in, Figure 1 and Figure 2 The correspondence between the reference numerals and component names in the attached drawings is as follows: 1. Conductor; 2. Modified resin layer; 3. Thermoplastic resin layer. Detailed Implementation
[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the embodiments of this application will be described in detail below with reference to the accompanying drawings.
[0022] One embodiment of this application provides an insulated wire, such as Figure 1 As shown, the device includes a conductor 1 and a modified resin layer 2 covering the outside of the conductor 1. The average linear thermal expansion coefficient of the modified resin layer 2 is 18~50 ppm / K. Common conductors 1 are copper and aluminum, where the linear thermal expansion coefficient of copper is 17 ppm / K; the linear thermal expansion coefficient of aluminum is 23 ppm / K; and the linear thermal expansion coefficient of copper-aluminum alloy is 17-23 ppm / K. The linear thermal expansion coefficient of the modified resin layer 2 (insulation layer) of the insulated wire in this application is close to that of the common conductor 1. During heating and cooling, the difference in deformation between the two is small, for example, they have the same elongation and the same shrinkage. There is almost no stress caused by deformation between the two, thus avoiding gaps between them and preventing microcracks from forming in the modified resin layer 2.
[0023] In some embodiments, the modified resin layer 2 is obtained by melt extrusion molding of the modified resin. The modified resin includes a matrix resin and modified inorganic fillers. The proportion of the modified inorganic fillers in the total mass of the modified resin is less than 30 wt%. The proportion of the modified inorganic fillers affects not only the linear thermal expansion coefficient of the modified resin layer 2, but also the flexibility. Too much filler will reduce the flexibility of the modified resin, while too little filler will limit the effect of reducing the linear thermal expansion coefficient. Therefore, preferably, the proportion of the modified inorganic fillers in the total mass of the modified resin is 5 wt% to 30 wt%.
[0024] In some embodiments, the matrix resin includes a first resin and a second resin; the first resin is polyetheretherketone (PEEK) resin, and the polyetheretherketone accounts for more than 50 wt% of the total mass of the matrix resin. The second resin is at least one of polyether diphenyl etherketone (PEDEK), polyether o-etherketone (PEOEK), polyetherketone (PEK), polyetherketone ketone (PEKK), polyetheretherketone-polyether diphenyl etherketone (PEEK-PEDEK), polyetheretherketone-polyether o-etherketone (PEEK-PEOEK), and polyether diphenyl etherketone-polyether o-etherketone (PEDEK-PEOEK).
[0025] Polyetheretherketone (PEEK) possesses high heat distortion temperature and rigidity. The introduction of a second resin can improve the melt viscoelasticity of the composite material at processing and service temperatures without significantly reducing its temperature resistance. This allows the material to better wet and coat the surface of conductor 1 during extrusion, forming a tight physical bond. Furthermore, the PEEK and the second resin form a microscopically blended continuous phase or partially compatible system, which can more uniformly transfer and disperse stress under heat or stress, avoiding stress concentration at the interface between PEEK and conductor 1.
[0026] In some embodiments, the modified inorganic filler is an inorganic filler whose outer surface is at least partially coated with a compatible resin layer, the compatible resin layer accounting for 0.5-5 wt% of the total mass of the modified inorganic filler, and the resin constituting the compatible resin layer is a polyetherketone resin. Preferably, the polyetherketone resin is phenolphthalein-based polyaryletherketone.
[0027] Modified inorganic fillers can improve the thermal conductivity of polyetheretherketone (PEEK) and make the crystalline regions of the inner and outer layers more uniform. Since thermal shock can cause uneven distribution of crystalline regions in PEEK (e.g., rapid cooling of the surface to form an amorphous layer, while slow cooling of the interior leads to crystallization), the dielectric properties decrease. Furthermore, impurities or moisture easily accumulate at grain boundaries, forming conductive pathways. Adding modified inorganic filler particles can adjust the linear thermal expansion coefficient of the modified resin, making it closer to that of conductor 1.
[0028] In some embodiments, the inorganic filler includes a first filler and a second filler; the first filler accounts for 0.1-30 wt% of the total mass of the modified resin, and the second inorganic filler accounts for 0.1-30 wt% of the total mass of the modified resin. The first filler is talc; the second filler is one or more of boron nitride, mica, silicon dioxide, titanium dioxide, molybdenum disulfide, titanium oxide, aluminum oxide, calcium sulfate, calcium carbonate, ferrite, clay, glass powder, zinc oxide, nickel carbonate, iron oxide, quartz powder, magnesium carbonate, fluorocarbon resin, graphite, graphene, graphene oxide, carbon powder, ceramic powder, metal powder, flame retardant powder, nanotubes, and barium sulfate.
[0029] In some embodiments, the microstructure of the inorganic filler particles is spherical, plate-like, or irregular in shape.
[0030] Small particle size of inorganic filler particles makes them prone to agglomeration; large particle size may prevent complete bonding with the second or first resin, creating voids or air gaps. The electric field strength of these air gaps (dielectric constant ≈ 1) is much higher than that of polyetheretherketone (ε ≈ 3.2), which may lead to localized breakdown. Therefore, the particle size range of inorganic filler particles is: D90 < 1 μm, that is, at least 90% of the particles in the inorganic filler have a particle size of less than 1 μm.
[0031] In some embodiments, at least one thermoplastic resin layer 3 is further included on the outside of the modified resin layer 2. Preferably, the linear coefficient of thermal expansion of the thermoplastic resin layer 3 is greater than or equal to the linear coefficient of thermal expansion of the modified resin layer 2, which helps to distribute the temperature evenly and reduce the problem of thermal stress concentration caused by local overheating.
[0032] Furthermore, the material of conductor 1 is selected from at least one of copper, aluminum, copper alloys, and aluminum alloys. Optionally, the material of conductor 1 may be silver, which has a linear thermal expansion coefficient of 18.5 ppm / K, similar to that of the modified resin layer 2.
[0033] Another aspect of this application discloses a method for preparing an insulated wire, comprising: S1. Phenolphthalein polyarylether ketone is added to N,N-dimethylacetamide (DMAc) and dissolved to obtain a primary mixture.
[0034] S2. Add inorganic filler particles to the primary mixture, and after ultrasonic stirring to disperse them evenly, a secondary mixture is obtained. Then, the evenly mixed secondary mixture is made into powder, so that the inorganic filler particles are coated with a layer of phenolphthalein polyarylether ketone, to obtain inorganic filler masterbatch.
[0035] S3. The inorganic filler masterbatch and polyether ether ketone powder are mixed evenly and then melt-co-extruded and granulated by a twin-screw extruder to obtain a modified resin with a low linear coefficient of thermal expansion; wherein, the proportion of polyether ether ketone is more than 50 wt%.
[0036] Preferably, the polyetheretherketone (PEEK) powder is subjected to surface plasma treatment before mixing the inorganic filler masterbatch with the PEEK powder. The principle of surface plasma treatment is as follows: under a nitrogen or argon atmosphere, charged high-speed ions induce the molecular chain breakage on the surface of the PEEK particles, thereby generating active sites such as free radicals. These active sites are used to initiate monomer graft polymerization, forming new cross-linked structures, changing the chemical composition, hydrophilic / hydrophobic properties, and adhesion of the material surface, and improving the adhesion of PEEK to phenolphthalein-based polyaryletherketone and inorganic fillers.
[0037] In some embodiments, the amount of phenolphthalein-based polyaryletherketone encapsulated in the inorganic filler masterbatch is 0.5-5 wt% of the inorganic filler particles.
[0038] In some embodiments, the melt co-extrusion process includes: adding a mixture of inorganic filler masterbatch and PEEK powder into the barrel of a twin-screw extruder, heating it to 370-410°C to make the mixture melt, and then granulating it to obtain modified resin particles with a particle size of 2-3 mm.
[0039] In some embodiments, step three involves preparing the secondary mixture into a powder, including: Adjust the viscosity of the secondary mixture.
[0040] The secondary mixture is atomized using a spray dryer. The inlet and outlet temperatures of the spray dryer are set (to avoid thermal degradation of phenolphthalein polyarylether ketone). The inlet temperature must be higher than the boiling point of the organic solvent, such as 150-250°C. The atomized droplets are rapidly dried into powder upon contact with hot, dry air. The resulting powder has good flowability, facilitating subsequent mixing with resin particles and extrusion processing.
[0041] The dried powder is collected and recovered through a cyclone separator or bag filter to obtain inorganic filler masterbatch.
[0042] This application also proposes a coil composed of insulated wires as described in any of the above-mentioned technical solutions.
[0043] In another aspect, this application proposes an electronic / electrical device, characterized in that it includes the coil described above.
[0044] The following are performance tests conducted on the insulated wires in specific embodiments of this application. The examples given do not represent all the embodiments of this application; only some are used as examples for illustration. Specific embodiments are as follows: Example 1
[0045] The conductor of the insulated wire is made of low-oxygen copper or oxygen-free copper, with dimensions of 1.5 mm × 3.0 mm. The conductor is surrounded by a single layer of modified resin, with a thickness of 120-150 μm. The modified resin layer contains 5 wt% inorganic filler with a D90 particle size range of 100-900 nm. The inorganic filler is a 1:2 mass ratio of talc and silica. Phenolphthalein-based polyaryletherketone accounts for 0.5 wt% of the inorganic filler. The remainder of the modified resin layer is polyetheretherketone. Example 2
[0046] The modified inorganic filler accounted for 10 wt%, and phenolphthalein-based polyaryletherketone accounted for 1 wt% of the inorganic filler. Other parameters were the same as in Example 1. Example 3
[0047] The modified inorganic filler accounted for 15 wt%, and phenolphthalein-based polyaryletherketone accounted for 2 wt% of the inorganic filler. Other parameters were the same as in Example 1. Example 4
[0048] The modified inorganic filler accounted for 20 wt%, and phenolphthalein-based polyaryletherketone accounted for 3 wt% of the inorganic filler. Other parameters were the same as in Example 1. Example 5
[0049] The modified inorganic filler accounted for 25 wt%, and phenolphthalein-based polyarylether ketone accounted for 4 wt% of the inorganic filler. Other parameters were the same as in Example 1. Example 6
[0050] The modified inorganic filler accounted for 30 wt%, and phenolphthalein-based polyaryletherketone accounted for 5 wt% of the inorganic filler. Other parameters were the same as in Example 1.
[0051] Comparative Example 1 The proportion of inorganic filler is 0, and other parameters are the same as in Example 1.
[0052] Comparative Example 2 The inorganic filler content was 40 wt%, and the phenolphthalein-based polyaryletherketone was 5 wt% of the inorganic filler. Other parameters were the same as in Example 1.
[0053] Comparative Example 3 The inorganic filler content is 10 wt%, the particle size range of D90 is 1000-2000 nm, the phenolphthalein-based polyaryletherketone is 1 wt% of the inorganic filler, and other parameters are the same as in Example 1.
[0054] Comparative Example 4 The modified inorganic filler accounts for 20 wt%, the particle size range of D90 is 1000-2000 nm, the phenolphthalein-based polyaryletherketone is 3 wt% of the inorganic filler, and other parameters are the same as in Example 1.
[0055] Comparative Example 5 The modified inorganic filler accounts for 20 wt% and does not contain phenolphthalein polyarylether ketone. Other parameters are the same as in Example 1.
[0056] The insulated wires of the above embodiments and comparative examples were tested according to the following methods: (1) The test standard for the linear thermal expansion coefficient is ISO11359-2.
[0057] (2) The sample line was treated with a thermal shock tester. The test conditions were: high temperature 200℃ / 60min-low temperature -40℃ / 60min, switching time <2min, switching from high temperature to low temperature and then back to high temperature was one cycle, and 100 cycles were performed.
[0058] (3) Insulation breakdown voltage (BDV) test after thermal shock: The test method provided in IEC 60851-5-2019 Test Method 13 is adopted. The specific steps are as follows: Remove the insulation layer from one end of the insulated wire after thermal shock to expose a conductor. (The following text appears to be incomplete and requires further context: "With a diameter...") After bending the wider side of a 25mm round rod, place it into a container of metal balls at least 5mm thick, ensuring the insulated wire end extends sufficiently to prevent flashover. Apply a test voltage between the conductor and the metal balls. Increase the voltage at a rate of 500V / second and a leakage current of 5mA. Perform the test five times and take the average voltage as the insulation breakdown voltage.
[0059] (4) Flexibility test method after thermal shock: The flexibility test method provided in IEC 60851-3-2019 Test Method 8 is adopted. The specific steps are as follows: Take two straight insulated wires with a length of 500mm. Bend the two insulated wires around a polished test core by 180±2°. One wire is wound horizontally (core diameter = wire thickness 2 times) and the other wire is wound vertically (core diameter = wire width 2 times). In this test, after horizontal and vertical winding, the product surface is recorded as "qualified" if it is smooth and without cracks; the surface is recorded as "unqualified" if cracks are found.
[0060] Table 1 Performance of insulated wires in the examples and comparative examples
[0061] As can be seen from Table 1, In Examples 1-6, the modified inorganic filler accounted for 5-30 wt%, the D90 particle size ranged from 100-900 nm, and the linear thermal expansion coefficient was lower than that of PEEK resin. The BDV retention rate after thermal shock was above 90%, and the flexibility after thermal shock was satisfactory. In Example 6, the modified inorganic filler accounted for 30 wt%, the linear thermal expansion coefficient of the insulating layer was 18 ppm / K, close to the linear thermal expansion coefficient of conductor copper (17 ppm / K), and it had the highest BDV retention rate after thermal shock, at 93.13%.
[0062] In Comparative Example 1, no inorganic filler was added, the linear thermal expansion coefficient of the insulation layer was 55 ppm / K, the BDV retention rate after thermal shock was 79.14%, and the flexibility after thermal shock was unqualified.
[0063] In Comparative Example 2, the modified inorganic filler accounted for 40 wt%, the linear thermal expansion coefficient of the insulation layer was 12 ppm / K, which was lower than that of the conductor copper. The BDV retention rate after thermal shock was 86.58%, and only the vertical winding was qualified in the flexibility test after thermal shock.
[0064] In Comparative Examples 3 and 4, the proportion of modified inorganic fillers was 10wt% and 20wt%, respectively, but the particle size was 1000-2000nm and 3000-5000nm. The BDV retention rate after thermal shock was low, and the flexibility after thermal shock was unqualified.
[0065] In Comparative Example 5, inorganic fillers were directly added to the matrix resin without encapsulating them with phenolphthalein-based polyaryletherketone. This resulted in filler agglomeration, leading to stress concentration and consequently reducing the breakdown voltage and flexibility of the insulated wire. Furthermore, the BDV retention rate was low after thermal shock, and the flexibility after thermal shock was substandard.
[0066] The data in Table 1 show that whether the outer surface of the modified inorganic filler is coated with a compatible resin, the addition ratio of the modified inorganic filler, and the particle size directly affect the linear thermal expansion coefficient of the modified resin layer, the BDV retention rate after thermal shock, and the flexibility after thermal shock. In the modified resin layer with PEEK as the main material, the proportion of modified inorganic filler is 30wt%. The linear thermal expansion coefficient of the insulation layer is close to that of copper, the BDV retention rate after thermal shock is high, and the flexibility test after thermal shock is qualified.
[0067] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of this application and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of this application should be included within the protection scope of this application. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.
Claims
1. An insulated wire, comprising a conductor (1) and a modified resin layer (2) covering the outside of said conductor (1), characterized in that, The average linear thermal expansion coefficient of the modified resin layer (2) is 18~50ppm / K.
2. The insulated wire according to claim 1, characterized in that, The modified resin layer is obtained by melt extrusion molding of modified resin, and the modified resin includes a matrix resin and modified inorganic fillers.
3. The insulated wire according to claim 2, characterized in that, The modified inorganic filler accounts for less than 30 wt% of the total mass of the modified resin.
4. The insulated wire according to claim 2, characterized in that, The modified inorganic filler accounts for 5 wt% to 30 wt% of the total mass of the modified resin.
5. The insulated wire according to claim 2, characterized in that, The matrix resin includes a first resin and a second resin; The first resin is polyetheretherketone, and the polyetheretherketone accounts for more than 50 wt% of the total mass of the matrix resin; The second resin is at least one of polyether diphenyl ether ketone, polyether o-ether ketone, polyether ketone, polyether ketone ketone, polyether ether ketone-polyether diphenyl ether ketone, polyether ether ketone-polyether o-ether ketone, and polyether diphenyl ether ketone-polyether o-ether ketone.
6. The insulated wire according to claim 2, characterized in that, The modified inorganic filler is an inorganic filler whose outer surface is at least partially coated with a compatible resin layer.
7. The insulated wire according to claim 5, characterized in that, The compatibility resin layer accounts for 0.5-5 wt% of the total mass of the modified inorganic filler, and the resin constituting the compatibility resin layer is a polyetherketone resin.
8. The insulated wire according to claim 7, characterized in that, The polyetherketone resin is phenolphthalein-based polyaryletherketone.
9. The insulated wire according to claim 6, characterized in that, The inorganic packing includes a first packing and a second packing. The first filler is talc; The second filler is one or more of the following: boron nitride, mica, silicon dioxide, titanium dioxide, molybdenum disulfide, titanium oxide, aluminum oxide, calcium sulfate, calcium carbonate, ferrite, clay, glass powder, zinc oxide, nickel carbonate, iron oxide, quartz powder, magnesium carbonate, fluorocarbon resin, graphite, graphene, graphene oxide, carbon powder, ceramic powder, metal powder, flame retardant powder, nanotubes, and barium sulfate.
10. The insulated wire according to claim 9, characterized in that, The first filler accounts for 0.1-30 wt% of the total mass of the modified resin, and the second filler accounts for 0.1-30 wt% of the total mass of the modified resin.
11. The insulated wire according to claim 6, characterized in that, The particle size of the inorganic filler satisfies: D90 < 1 μm.
12. The insulated wire according to claim 1, characterized in that, Outside the modified resin layer (2), there is also at least one thermoplastic resin layer (3).
13. The insulated wire according to claim 12, characterized in that, The linear thermal expansion coefficient of the thermoplastic resin layer (3) is greater than or equal to the linear thermal expansion coefficient of the modified resin layer (2).
14. A coil, characterized in that, It is composed of an insulated wire as described in any one of claims 1-13.
15. An electronic / electrical device, characterized in that, Includes the coil as described in claim 14.