Insulated electric wire, method for manufacturing the same, coil, and electronic / electrical device

Abstract

This invention belongs to the technical field of wires and cables, specifically proposing an insulated wire and its preparation method, coil, and electronic / electrical equipment. The insulated wire includes: a conductor; a first modified resin layer covering the outside of the conductor, the first modified resin layer being obtained by melt extrusion molding of modified resin, the modified resin comprising a matrix resin and modified inorganic fillers; and a second modified resin layer covering the outside of the first modified resin layer, with a crystallinity ≤20%. This application improves the adhesion between the resin layer and the conductor under thermal shock by setting a first modified resin layer with a coefficient of linear thermal expansion (CTE) close to that of common conductors as an intermediate layer, and by using a second modified resin layer with low crystallinity, the insulated wire exhibits better flexibility.

Description

Technical Field

[0001] This application belongs to the field of wire and cable technology, and particularly relates to an insulated wire and its preparation method, a coil, and electronic / electrical equipment. Background Technology

[0002] In inductor manufacturing, the processing of inductor pins involves three core steps: paint removal, electroplating, and soldering. This process chain places stringent requirements on the overall performance of the insulated wires. In the paint removal stage, improper energy control using high-energy methods such as lasers or plasma can easily damage the conductor surface. If mechanical paint removal is used, uneven force application can cause localized stress concentration on the conductor surface, and the bending operations during inductor pin processing further exacerbate this stress concentration effect.

[0003] When the adhesion between the insulating varnish and the conductor is insufficient, localized peeling of the varnish from the metal conductor can easily occur in areas of stress concentration, leading to varnish warping. In subsequent electroplating processes, the plating solution seeps into and accumulates in the peeled areas, further amplifying the warping. Finally, the high temperature of the soldering process generates thermal stress, exacerbating the separation of the varnish from the conductor. This can result in large-area peeling and detachment of the varnish, or even cracking of the electroplated layer. These defects directly lead to problems such as poor soldering (cold solder joints) and decreased conductivity in inductors. Simultaneously, they significantly deteriorate the environmental resistance (resistance to moisture and salt spray corrosion) of inductor devices, severely impacting their long-term reliability.

[0004] Existing insulated wires generally suffer from the following problems: insufficient flexibility during bending, leading to stress concentration; poor adhesion between the insulation layer and the conductor, making them prone to interlayer delamination under mechanical and thermal stress; and poor resistance to acidic plating solutions and interfacial stability under high-temperature soldering conditions, failing to meet the processing requirements of the entire inductor pin end process chain. Therefore, there is an urgent need to develop an insulated wire that combines excellent flexibility, interlayer adhesion, resistance to acidic plating solutions, and high-temperature stability to solve technical challenges such as enamel film warping in inductor manufacturing. Summary of the Invention

[0005] In a first aspect, this application provides an insulated wire, comprising: conductor; A first modified resin layer is coated on the outside of the conductor. The first modified resin layer is obtained by melt extrusion molding of modified resin, and the modified resin includes a matrix resin and modified inorganic fillers. The second modified resin layer is coated on the outside of the first modified resin layer, and its crystallinity is ≤20%.

[0006] Furthermore, the second modified resin layer comprises polyetheretherketone resin and polyetherketoneketone resin, and the mass ratio of the two is 95:5 to 5:95.

[0007] Furthermore, the melt flow rate of the second modified resin layer is ≥8 g / 10 min; wherein the melt flow rate is measured according to ISO 1133 international standard at 400 °C and 2.16 kg load.

[0008] Furthermore, the modified inorganic filler accounts for less than 35 wt% of the total mass of the modified resin, and the average linear thermal expansion coefficient of the first modified resin layer is 18~50 ppm / K. The matrix resin includes a first resin and a second resin, wherein the first resin is polyetheretherketone (PEEK) and accounts for more than 50 wt% of the total mass of the matrix resin; the second resin includes at least one of polyether diphenyl etherketone (PED- ... The modified inorganic filler is an inorganic filler whose outer surface is at least partially coated with a compatible resin layer, and the inorganic filler includes a first filler and a second filler; 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.

[0009] Furthermore, the modified inorganic filler accounts for 5wt% to 30wt% of the total mass of the modified resin; 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; 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.

[0010] Furthermore, the polyetherketone resin is phenolphthalein-based polyaryletherketone.

[0011] Furthermore, the particle size range of the first and second fillers is: D90 is less than 1 μm.

[0012] Furthermore, the conductor is at least one of copper, aluminum, copper alloy, and aluminum alloy.

[0013] Secondly, this application proposes a method for preparing an insulated wire, used to prepare the insulated wire in any of the above-mentioned technical solutions, comprising: S1: Dissolve the compatible resin in an organic solvent to obtain a primary mixture; S2: Add inorganic filler to the primary mixture and disperse it evenly to obtain a secondary mixture; S3: The secondary mixture is made into powder to obtain modified inorganic filler; S4: After uniformly mixing the first resin particles, the second resin particles, and the modified inorganic filler obtained in S3, the first modified resin particles are obtained by blending and granulating through a twin-screw extruder; after uniformly mixing the polyetheretherketone resin particles and the polyetherketoneketone resin particles, the second modified resin particles are obtained by blending and granulating through a twin-screw extruder. S5: The first modified resin particles and the second modified resin particles obtained in S4 are extruded sequentially onto the outside of the conductor using an extruder to form the first modified resin layer and the second modified resin layer, thus obtaining a wire. S6: The wire obtained in S5 is guided into a cooling device for cooling to obtain the insulated wire.

[0014] Furthermore, the process of making the secondary mixture into powder as described in S3 includes atomizing the secondary mixture and contacting the formed tiny droplets with dry, hot air to obtain the powder.

[0015] Thirdly, this application proposes a coil composed of an insulated wire from any of the above-mentioned technical solutions, or an insulated wire prepared by the method for preparing an insulated wire from any of the above-mentioned technical solutions.

[0016] Fourthly, this application proposes an electronic / electrical device that includes the coil described in the above-mentioned technical solution.

[0017] The above-described technical solution of the present invention has at least the following beneficial technical effects: By setting a first modified resin layer with a low coefficient of linear thermal expansion (CTE) close to that of common conductors as an intermediate layer, the adhesion performance between the resin layer and the conductor under thermal shock is improved. The second modified resin layer with low crystallinity is used to make the insulated wire more flexible. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of an insulated wire in one embodiment of this application.

[0019] in, Figure 1 The correspondence between the reference numerals and component names in the attached drawings is as follows: 1. Conductor; 2. First modified resin layer; 3. Second modified resin layer. Detailed Implementation

[0020] 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.

[0021] In one aspect, an embodiment of this application provides an insulated wire, including a conductor 1 and a first modified resin layer sequentially covering the outside of the conductor 1 from the inside out, and a second modified resin layer 3 covering the outside of the first modified resin layer 2. Both the first modified resin layer 2 and the second modified resin layer 3 contain polyetheretherketone (PEEK) and have similar microstructures, which can ensure the adhesion of the two layers.

[0022] The first modified resin layer 2 is obtained by melt extrusion of modified resin, which includes a matrix resin and modified inorganic fillers.

[0023] The crystallinity of the second modified resin layer 3 is ≤20%. This significantly improves the overall flexibility of the wire, making it less prone to stress concentration during bending and preventing localized delamination between the two resin layers and conductor 1. Simultaneously, the low CTE allows the first modified resin layer 2 to also act as an intermediate transition, effectively mitigating thermal and mechanical stresses caused by thermal shock, high soldering temperatures, and bending operations, reducing stress concentration. The synergistic effect of the two resin layer structures fundamentally prevents film warping and peeling, ensuring the stability of the interface adhesion between the insulation layer and conductor 1.

[0024] Preferably, the average linear thermal expansion coefficient (CTE) of the first modified resin layer 2 is 18~50ppm / K. This CTE value is close to that of conventional conductors such as copper, aluminum, silver and copper-aluminum alloys (the CTE of copper is 17ppm / K; the CTE of aluminum is 23ppm / K; and the CTE of copper-aluminum alloys is 17-23ppm / K). During heating and cooling, the difference in deformation between the two is small, and they have the same elongation and the same shrinkage, which reduces the stress caused by deformation. Therefore, gaps between conductor 1 and the first modified resin layer 2 can be avoided, as well as microcracks in the first modified resin layer 2.

[0025] In one embodiment, the second modified resin layer 3 contains polyetheretherketone (PEEK) resin and polyetherketoneketone (PEKK) resin, which are mixed in a mass ratio of 95:5 to 5:95. The PEEK segments have more ether bonds, giving them a certain degree of flexibility but also a faster crystallization rate; the PEKK segments have more ketone bonds, resulting in greater rigidity and inhibiting crystallization. This mass ratio range achieves and maintains a low crystallinity (≤20%) while preserving the material's heat resistance and strength.

[0026] In one embodiment, the melt flow rate (MFR) of the second modified resin layer 3 is ≥8 g / 10 min; wherein the melt flow rate is measured according to ISO 1133 international standard at 400°C and a load of 2.16 kg. This range of melt flow rate values ​​ensures that, during the extrusion coating process, the resin can uniformly and smoothly coat the surface of the first modified resin layer 2, forming a dense and defect-free insulating layer; combined with a crystallinity of ≤20%, the finished layer possesses excellent coating processability, flexibility due to low crystallinity, and a stable interfacial bond with the first modified resin layer 2.

[0027] In one embodiment, the modified inorganic filler accounts for less than 35 wt% of the total mass of the modified resin; preferably, the modified inorganic filler accounts for 5 wt%-30 wt% of the total mass of the modified resin. The matrix resin includes a first resin and a second resin. The first resin is polyetheretherketone (PEEK), and 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). Polyetheretherketone has a high heat distortion temperature and rigidity. The introduction of the second resin can improve the melt viscoelasticity of the composite material at processing and service temperatures without significantly reducing its temperature resistance. Furthermore, the polyetheretherketone (PEEK) and the second resin form a microscopically blended continuous phase or a partially compatible system, which can more evenly transmit and disperse stress when heated or subjected to force, thus avoiding stress concentration at the interface between PEEK and conductor 1.

[0028] The modified inorganic filler is an inorganic filler whose outer surface is at least partially coated with a compatible resin layer. The inorganic filler includes a first filler and a second filler. The first filler is talc, and the second filler is one or more of the following: boron nitride, mica, silica, titanium dioxide, molybdenum disulfide, titanium oxide, alumina, 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. The resin constituting the compatible resin layer is a polyetherketone resin, preferably phenolphthalein-based polyaryletherketone (PEK-C). Using PEK-C as a compatibilizer greatly improves the interfacial bonding between the inorganic filler and the polyetherketone resin matrix, prevents particle agglomeration, ensures uniform dispersion within the layer, and enables the inorganic filler to form good microscopic connections with the polyetherketone layers, thereby improving the mechanical properties and interfacial adhesion of the first modified resin layer 2. Furthermore, both the first and second fillers possess low linear thermal expansion coefficients, and their uniform dispersion effectively reduces the overall CTE of the first modified resin layer 2, stabilizing it within the range of 18-50 ppm / K. Talc, as the primary inorganic phase, provides basic CTE regulation, while the second filler can be introduced with specific functions such as thermal conductivity, insulation, and wear resistance as needed.

[0029] 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. The addition of these two types of inorganic fillers can ensure that the CTE of the first modified resin layer 2 is effectively reduced to the required range, while avoiding increased layer brittleness, decreased flexibility, or poor adhesion to the conductor 1 / second modified resin layer 3 due to excessive inorganic fillers. An appropriate amount of PEK-C can fully wet the particle surface, forming effective coupling and compatibility, and optimizing the particle-resin interface; too little will result in insufficient modification effect, while too much may have the opposite effect due to PEK-C agglomeration or affecting particle dispersion.

[0030] In some embodiments, the inorganic filler has a microstructure that is spherical, plate-like, or irregular in shape.

[0031] Small particle sizes of inorganic fillers are prone to agglomeration; large particle sizes may prevent complete bonding with the first or second 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), potentially leading to localized breakdown. Therefore, the particle size range for inorganic fillers is: D90 < 1 μm; that is, at least 90% of the particles in the inorganic filler must have a particle size less than 1 μm. Small-sized inorganic fillers have a larger specific surface area, allowing for more thorough contact with the resin and more effective control of CTE, thus contributing to improved mechanical properties and flexibility of the first modified resin layer 2.

[0032] In some embodiments, the thickness of the first modified resin layer 2 is less than 10 μm, ensuring that it serves as a functional transition layer without affecting the overall size and flexibility of the wire. The total insulation thickness is 5-1000 μm, covering the needs of wires from small to standard sizes, and is particularly suitable for precision electronic components (such as inductors) with space constraints. The combination of a thinner, low-CTE layer and a low-crystallinity resin layer of appropriate total thickness provides sufficient electrical insulation while maintaining excellent overall flexibility and bending performance of the wire, meeting the requirements of inductor winding and pin forming processes.

[0033] Secondly, this application proposes a method for preparing an insulated wire, used to prepare the insulated wire in any of the above-mentioned technical solutions, comprising: S1: Dissolve the compatible resin in an organic solvent to obtain a primary mixture; S2: Add inorganic filler to the primary mixture and disperse it evenly to obtain a secondary mixture; S3: The secondary mixture is made into powder to obtain modified inorganic filler; S4: After uniformly mixing the first resin particles, the second resin particles, and the modified inorganic filler obtained in S3, the first modified resin particles are obtained by blending and granulating through a twin-screw extruder; after uniformly mixing the polyetheretherketone resin particles and the polyetherketoneketone resin particles, the second modified resin particles are obtained by blending and granulating through a twin-screw extruder. S5: The first modified resin particles and the second modified resin particles obtained in S4 are extruded sequentially through an extruder to form the first modified resin layer 2 and the second modified resin layer 3 on the outside of the conductor 1 to obtain a wire. S6: The wire obtained in S5 is guided into a cooling device for cooling to obtain an insulated wire. Optionally, a cold water tank can be used as the cooling device, and the temperature of the cold water in the cold water tank is controlled within the range of 0-30℃.

[0034] Preferably, in S5, conductor 1 is preheated before entering the extruder, and the preheating temperature is above 400°C.

[0035] S6 employs a "direct cold water cooling after extrusion" method, which rapidly lowers the temperature of the second modified resin layer 3 below the crystallization temperature, allowing it to quickly pass through the resin's crystallization temperature range. This effectively suppresses the crystallization process of the second resin layer, thereby obtaining an amorphous or low-crystallinity structure with a crystallinity of ≤20%, ensuring the flexibility of the insulation layer.

[0036] Preferably, the process of turning the secondary mixture into powder in step S3 includes atomizing the secondary mixture using a spray dryer, and setting the inlet and outlet temperatures of the spray dryer (to avoid thermal degradation of phenolphthalein polyarylether ketone); wherein the inlet temperature needs to be higher than the boiling point of the organic solvent, such as an inlet temperature of 150-250°C. The small droplets formed by atomization are rapidly dried into powder upon contact with hot, dry air, resulting in a powder with good flowability.

[0037] Thirdly, this application proposes a coil composed of an insulated wire from any of the above-mentioned technical solutions, or an insulated wire prepared by the method for preparing an insulated wire from any of the above-mentioned technical solutions.

[0038] Fourthly, this application proposes an electronic / electrical device that includes the coil described in the above-mentioned technical solution.

[0039] The following specific embodiments are further illustrations of this application. The examples given do not represent all the implementation methods of this application; only some are used as examples for illustration. Specific embodiments are as follows:

[0040] Example 1: The conductor of the insulated wire is a flat copper wire with dimensions of 0.2mm × 2.0mm; the total thickness of the insulation layer is 50μm.

[0041] The first modified resin layer contains polyetheretherketone (PEEK), polyether diphenyl etherketone (PEDEK), talc, and silica; the ratio of PEEK to PDEK is 95:5. The ratio of talc to silica is 1:2, and talc and silica account for 30 wt% of the first modified resin layer, with a D90 particle size range of 5 nm-900 nm. Phenolic phthaloyl polyaryletherketone accounts for 2 wt% of the total mass of the modified inorganic filler; the linear thermal expansion coefficient of the modified resin used to prepare the first modified resin layer is 18 ppm / K.

[0042] The second modified resin layer contains polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) in a ratio of 95:5. The crystallinity is 13%. In this embodiment, during the preparation of the insulated wire: after the second modified resin layer is extruded using an extruder, it is immediately cooled in a cold water bath.

[0043] Example 2: The conductor of the insulated wire is a flat copper wire with dimensions of 0.2mm × 2.0mm; the total thickness of the insulation layer is 50μm.

[0044] The first modified resin layer contains polyetheretherketone (PEEK), polyether diphenyl etherketone (PEDEK), talc, and silica; the ratio of PEEK to PDEK is 95:5. The ratio of talc to silica is 1:2, and talc and silica together account for 30 wt% of the first modified resin layer, with a D90 particle size range of 5 nm-900 nm. Phenolic phthaloyl polyaryletherketone accounts for 2 wt% of the total mass of the modified inorganic filler; the linear thermal expansion coefficient of the modified resin used to prepare the first modified resin layer is 18 ppm / K.

[0045] The second modified resin layer contains polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) in a ratio of 95:5. The crystallinity is 20%. In this embodiment, during the preparation of the insulated wire: after the second modified resin layer is extruded from the extruder, it is immediately sent to an insulated box and kept at a temperature above 260°C for 1.5 seconds, and then immediately sent to a cold water bath for cooling.

[0046] Example 3: The conductor of the insulated wire is a flat copper wire with dimensions of 0.2mm × 2.0mm; the total thickness of the insulation layer is 50μm.

[0047] The first modified resin layer contains polyetheretherketone (PEEK), polyether diphenyl etherketone (PEDEK), talc, and silica; the ratio of PEEK to PDEK is 95:5. The ratio of talc to silica is 1:2, and talc and silica together account for 30 wt% of the first modified resin layer, with a D90 particle size range of 5 nm-900 nm. Phenolphthalein-based polyaryletherketone accounts for 2 wt% of the total mass of the modified inorganic filler; the linear thermal expansion coefficient of the modified resin used to prepare the first modified resin layer is 18 ppm / K.

[0048] The second modified resin layer contains polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) in a ratio of 90:10. The crystallinity is 12%. In this embodiment, during the preparation of the insulated wire: after the second modified resin layer is extruded using an extruder, it is immediately cooled in a cold water bath.

[0049] Example 4: The conductor of the insulated wire is a flat copper wire with dimensions of 0.2mm × 2.0mm; the total thickness of the insulation layer is 50μm.

[0050] The first modified resin layer contains polyetheretherketone (PEEK), polyether diphenyl etherketone (PEDEK), talc, and silica; the ratio of PEEK to PDEK is 95:5. The ratio of talc to silica is 1:2, and talc and silica together account for 30 wt% of the first modified resin layer, with a D90 particle size range of 5 nm-900 nm. Phenolic phthaloyl polyaryletherketone accounts for 2 wt% of the total mass of the modified inorganic filler; the linear thermal expansion coefficient of the modified resin used to prepare the first modified resin layer is 18 ppm / K.

[0051] The second modified resin layer contains polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) in a ratio of 5:95. The crystallinity is 11%. In this embodiment, during the preparation of the insulated wire: after the second modified resin layer is extruded using an extruder, it is immediately cooled in a cold water bath.

[0052] Example 5: The conductor of the insulated wire is a flat copper wire with dimensions of 0.2mm × 2.0mm; the total thickness of the insulation layer is 50μm.

[0053] The first modified resin layer contains polyetheretherketone (PEEK), polyether diphenyl etherketone (PEDEK), talc, and silica; the ratio of PEEK to PDEK is 95:5. The ratio of talc to silica is 1:2, and talc and silica together account for 5 wt% of the first modified resin layer, with a D90 particle size range of 5 nm-900 nm. Phenolic phthaloyl polyaryletherketone accounts for 1 wt% of the total mass of the modified inorganic filler; the linear thermal expansion coefficient of the modified resin used to prepare the first modified resin layer is 50 ppm / K.

[0054] The second modified resin layer contains polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) in a ratio of 95:5. The crystallinity is 13%. In this embodiment, during the preparation of the insulated wire: after the second modified resin layer is extruded using an extruder, it is immediately cooled in a cold water bath.

[0055] Example 6: The conductor of the insulated wire is a flat copper wire with dimensions of 0.2mm × 2.0mm; the total thickness of the insulation layer is 50μm.

[0056] The first modified resin layer contains polyetheretherketone (PEEK), polyether diphenyl etherketone (PEDEK), talc, and silica; the ratio of PEEK to PDEK is 95:5. The ratio of talc to silica is 1:2, and talc and silica together account for 20 wt% of the first modified resin layer, with a D90 particle size range of 5 nm-900 nm. Phenolic phthaloyl polyaryletherketone accounts for 3 wt% of the total mass of the modified inorganic filler; the linear thermal expansion coefficient of the modified resin used to prepare the first modified resin layer is 35 ppm / K.

[0057] The second modified resin layer contains polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) in a ratio of 95:5. The crystallinity is 13%. In this embodiment, during the preparation of the insulated wire: after the second modified resin layer is extruded using an extruder, it is immediately cooled in a cold water bath.

[0058] Comparative Example 1: The conductor of the insulated wire is a flat copper wire with dimensions of 0.2mm × 2.0mm; the total thickness of the insulation layer is 50μm.

[0059] The first modified resin layer contains polyetheretherketone (PEEK), polyether diphenyl etherketone (PEDEK), talc, and silica; the ratio of PEEK to PDEK is 95:5. The ratio of talc to silica is 1:2, and talc and silica together account for 30 wt% of the first modified resin layer, with a D90 particle size range of 5 nm-900 nm. Phenolic phthaloyl polyaryletherketone accounts for 2 wt% of the total mass of the modified inorganic filler; the linear thermal expansion coefficient of the modified resin used to prepare the first modified resin layer is 18 ppm / K.

[0060] The second modified resin layer contains polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) in a ratio of 95:5. The crystallinity is 25%. In this embodiment, during the preparation of the insulated wire: after the second modified resin layer is extruded from the extruder, it is immediately placed in an insulated box and kept at above 260°C for 4 seconds, then immediately cooled in a cold water bath.

[0061] Comparative Example 2: The conductor of the insulated wire is a flat copper wire with dimensions of 0.2mm × 2.0mm; the total thickness of the insulation layer is 50μm.

[0062] The first modified resin layer contains polyetheretherketone (PEEK), polyether diphenyl etherketone (PEDEK), talc, and silica; the ratio of PEEK to PDEK is 95:5. The ratio of talc to silica is 1:2, and talc and silica together account for 30 wt% of the first modified resin layer, with a D90 particle size range of 5 nm-900 nm. Phenolic phthaloyl polyaryletherketone accounts for 2 wt% of the total mass of the modified inorganic filler; the linear thermal expansion coefficient of the modified resin used to prepare the first modified resin layer is 18 ppm / K.

[0063] The second modified resin layer contains polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) in a ratio of 100:0. The crystallinity is 28%. In this embodiment, during the preparation of the insulated wire: after the second modified resin layer is extruded from the extruder, it is immediately sent to an insulated box and kept at a temperature above 260°C for 4 seconds, and then immediately sent to a cold water bath for cooling.

[0064] Comparative Example 3: The conductor of the insulated wire is a flat copper wire with dimensions of 0.2mm × 2.0mm; the total thickness of the insulation layer is 50μm.

[0065] The first modified resin layer contains polyether ether ketone (PEEK) and polyether diphenyl ether ketone (PEDEK), and no modified inorganic filler is added. The ratio of PEEK to PDEK is 95:5, and the linear thermal expansion coefficient of the modified resin used to prepare the first modified resin layer is 55 ppm / K.

[0066] The second modified resin layer contains polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) in a ratio of 95:5. The crystallinity is 13%. In this embodiment, during the preparation of the insulated wire: after the second modified resin layer is extruded using an extruder, it is immediately cooled in a cold water bath.

[0067] 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.

[0068] (2) Insulation breakdown voltage (BDV) test: The test shall be conducted according to the breakdown voltage test method provided in IEC 60851-5-2019 Test Method 13. The specific steps are as follows: Remove the outer layer from one end of the insulated wire, and then... (The sentence is incomplete and requires more context to translate accurately. 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.

[0069] (3) Thermal shock test machine test, the test conditions are: high temperature 200℃ / 60min-low temperature 40℃ / 60min, switching time <2min, switching from high temperature to low temperature and then back to high temperature is one cycle, 100 cycles.

[0070] The insulated wires, after undergoing thermal shock, were immersed in salt water for 6 days before being subjected to BDV testing.

[0071] Table 1 Performance of insulated wires in the examples and comparative examples

[0072] In Table 1, the heat preservation time indicates the heat preservation time when the material is immediately sent to the heat preservation box after being extruded from the extruder and kept at a temperature of 260°C or higher; no heat preservation means that the material is directly sent to the cold water tank for cooling after being extruded from the extruder.

[0073] As can be seen from Table 1, Examples 1, 5, and 6 (with added modified inorganic fillers) have higher BDV retention rates.

[0074] Comparative Example 3 (without modified inorganic filler) had the same low crystallinity (13%) as Example 1, and under conditions where no heat preservation was applied after extruding the second modified resin layer, the BDV retention rate of the insulated wire in Comparative Example 3 plummeted to 65.63%. This indicates that the presence of modified inorganic filler is a key feature ensuring the stable performance of insulated wires under thermal shock and salt water corrosion. Without this feature, even with a flexible insulation layer of low crystallinity (Comparative Example 3), it is unable to resist the synergistic damage of stress and corrosion, resulting in severe performance degradation.

[0075] Examples 1-6 had a crystallinity of 11-20%, and their BDV retention rates were all greater than 93%, especially Example 4 (11% crystallinity), which achieved the highest retention rate of 98.88%. This indicates that the higher the crystallinity, the more brittle the material, and the more prone it is to interfacial failure under stress. Comparative Example 2 used pure PEEK for its second modified resin layer, and under the condition of heat preservation followed by cooling, its crystallinity reached as high as 28%. Although its retention rate (75.38%) was slightly higher than that of Comparative Example 1 (74.58%), it was still far lower than that of the low-crystallinity Examples 1-6, proving that pure PEEK is not the optimal choice.

[0076] The data in Table 1 proves that the technical solution of this application obtains a second modified resin layer with low crystallinity (≤20%) by introducing a first modified resin layer with low CTE, using a PEEK and PEKK blend system and combining it with a rapid cooling process, and finally enables the insulated wire to achieve a BDV retention rate of more than 93% in the above experiments.

[0077] 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, characterized in that, include: Conductor (1); The first modified resin layer (2) covers the outside of the conductor (1). The first modified resin layer (2) is obtained by melt extrusion molding of modified resin. The modified resin includes a matrix resin and modified inorganic filler. The second modified resin layer (3) is coated on the outside of the first modified resin layer (2), and its crystallinity is ≤20%.

2. The insulated wire according to claim 1, characterized in that, The second modified resin layer (3) comprises polyether ether ketone resin and polyether ketone ketone resin, and the mass ratio of the two is 95:5~5:

95.

3. The insulated wire according to claim 2, characterized in that, The melt flow rate of the second modified resin layer (3) is ≥8 g / 10 min; wherein the melt flow rate is measured according to ISO 1133 international standard at 400 °C and 2.16 kg load.

4. The insulated wire according to claim 1, characterized in that, The modified inorganic filler accounts for less than 35 wt% of the total mass of the modified resin; The matrix resin includes a first resin and a second resin, wherein the first resin is polyetheretherketone (PEEK) and accounts for more than 50 wt% of the total mass of the matrix resin; the second resin includes at least one of polyether diphenyl etherketone (PED), polyether o-etherketone (PEO), polyetherketone (PEK), polyetherketone ketone (PEKK), polyetheretherketone-polyether diphenyl etherketone (PED), polyetheretherketone-polyether o-etherketone (PEO), and polyether diphenyl etherketone-polyether o-etherketone (PEO). The modified inorganic filler is an inorganic filler whose outer surface is at least partially coated with a compatible resin layer, and the inorganic filler includes a first filler and a second filler; 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.

5. The insulated wire according to claim 4, characterized in that, The modified inorganic filler accounts for 5 wt% to 30 wt% of the total mass of the modified resin.

6. The insulated wire according to claim 4, 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. 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.

7. The insulated wire according to claim 6, characterized in that, The polyetherketone resin is phenolphthalein-based polyaryletherketone.

8. The insulated wire according to claim 4, characterized in that, The particle size range of the first and second fillers is: D90 is less than 1 μm.

9. The insulated wire according to claim 1, characterized in that, The conductor (1) is at least one of copper, aluminum, copper alloy and aluminum alloy.

10. A method for preparing an insulated wire, used to prepare the insulated wire according to any one of claims 4-9, characterized in that, include: S1: Dissolve the compatible resin in an organic solvent to obtain a primary mixture; S2: Add inorganic filler to the primary mixture and disperse it evenly to obtain a secondary mixture; S3: The secondary mixture is made into powder to obtain modified inorganic filler; S4: After uniformly mixing the first resin particles, the second resin particles, and the modified inorganic filler obtained in S3, the first modified resin particles are obtained by blending and granulating through a twin-screw extruder; after uniformly mixing the polyetheretherketone resin particles and the polyetherketoneketone resin particles, the second modified resin particles are obtained by blending and granulating through a twin-screw extruder. S5: The first modified resin particles and the second modified resin particles obtained in S4 are extruded sequentially onto the outside of the conductor using an extruder to form the first modified resin layer and the second modified resin layer, thus obtaining a wire. S6: The wire obtained in S5 is guided into a cooling device for cooling to obtain the insulated wire.

11. The method for preparing an insulated wire according to claim 10, characterized in that, The process of making the secondary mixture into powder as described in S3 includes atomizing the secondary mixture and contacting the formed tiny droplets with dry, hot air to obtain the powder.

12. A coil, characterized in that, It is composed of an insulated wire as described in any one of claims 1-9 or an insulated wire prepared by the method described in any one of claims 10-11.

13. An electronic / electrical device, characterized in that, It includes the coil as described in claim 12.

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