Multi-layer composite insulated wire and preparation method thereof

Abstract

The invention provides a multi-layer composite insulated wire and a preparation method thereof, the multi-layer composite insulated wire comprises a metal conductor core wire and a three-layer composite insulation structure sequentially coating the periphery of the metal conductor core wire, and the three-layer composite insulation structure sequentially comprises a first PEEK-based insulation layer, a second PEEK-based insulation layer and a PA / TPEE blending protection layer from inside to outside. The preparation method comprises the steps of conductor pretreatment, material pretreatment, layered co-extrusion molding and gradient cooling and curing. Through structural design and preparation process optimization of the multi-layer composite insulated wire, the core problems of high cost, poor processing performance, weak interface bonding, insufficient environmental protection performance and the like of a traditional PEEK insulated wire are effectively solved, and performance improvement is realized through functional layered construction and precise process control.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-performance insulating materials, and in particular relates to a multi-layer composite insulating wire and a preparation method thereof. Background Art

[0002] Polyetheretherketone (PEEK) is widely used in the manufacture of insulating materials in the fields of electronic and electrical equipment, aerospace, and new energy vehicles due to its excellent high-temperature resistance, chemical corrosion resistance, and high strength. However, the existing PEEK insulated wires still face a number of technical bottlenecks in practical applications. First, the cost of pure PEEK resin raw materials is too high, resulting in the price of the final product being difficult to meet the needs of the civilian market, limiting its promotion in cost-sensitive fields. Secondly, the melting point of the PEEK material itself is as high as 334 degrees Celsius, and the melt fluidity is poor. During the extrusion coating process, problems such as uneven coating thickness and excessive eccentricity are prone to occur, which directly affect the stability of the insulation performance. In addition, traditional three-layer insulated wires mostly adopt a structural design in which different materials are superimposed. For example, the outer layer uses polyimide or polyamide materials. However, due to the significant differences in the thermal expansion coefficients of the materials in each layer, the interface bonding strength is insufficient, and delamination is prone to occur during long-term use.

[0003] In terms of environmentally friendly production, the existing technology lacks a systematic treatment plan for waste gas and waste water generated during the processing process, which not only increases the environmental protection costs of enterprises, but also makes it difficult to meet the increasingly stringent green manufacturing standards. In response to the above problems, the existing technology has tried a variety of improvement methods. For example, by adding glass fiber or carbon fiber to improve the mechanical strength of the material, but such modifications will lead to a significant decrease in the flexibility and processing performance of the material. Another technical solution uses a multi-layer co-extrusion process to reduce the production process, but the equipment investment cost is high and the temperature control accuracy is insufficient. For example, the three-layer co-extrusion technology mentioned in a patent still has the problem of high energy consumption. Some companies have tried to add low-cost PET or TPEE materials to PEEK to reduce costs, but the temperature resistance level of such mixed materials generally drops by 30 to 50 degrees Celsius, which cannot meet the use requirements in high temperature environments.

[0004] It's worth noting that current cooling processes often rely on a single water-cooling process, resulting in uneven PEEK crystallinity distribution and insufficient insulation density. For example, a patent discloses a cooling solution that utilizes only air and water cooling, failing to effectively control the material's microstructure. These technical shortcomings collectively contribute to core issues with existing PEEK insulated wire products, including a difficult balance between cost and performance, low production yields, and insufficient environmental friendliness.

[0005] Therefore, it is necessary to design a multi-layer composite insulated wire and a preparation method thereof. Summary of the Invention

[0006] In order to overcome the defects in the prior art, a multi-layer composite insulated wire and a preparation method thereof are provided.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A multi-layer composite insulated wire comprises a metal conductor core wire and a three-layer composite insulation structure sequentially coated on its periphery. The three-layer composite insulation structure comprises, from the inside to the outside, a first PEEK-based insulation layer, a second PEEK-modified insulation layer, and a PA / TPEE blended protective layer.

[0009] The metal conductor core wire is an annealed tinned copper wire with a diameter of 0.05-2.5 mm, an annealing temperature of 220-280° C., and an annealing time of 15-45 minutes.

[0010] The first PEEK-based insulating layer comprises the following components in parts by mass: 12-18 parts of PEEK resin, 2-4 parts of nano-titanium dioxide, 0.5-1.2 parts of silane coupling agent, and 0.2-0.8 parts of antioxidant 1010.

[0011] The particle size of the nano titanium dioxide is 15-35nm, and the specific surface area is 50-80m 2 / g; the surface of the nano titanium dioxide is modified with stearic acid.

[0012] The second PEEK modified insulating layer is formed by melt blending the following components: 8-15 parts of PEEK resin, 3-6 parts of polyphenylene sulfide, 1-3 parts of maleic anhydride grafted SEBS, and 0.5-1.5 parts of boron nitride nanosheets.

[0013] The boron nitride nanosheet has a thickness of 5-15 nm and a lateral size of 200-500 nm.

[0014] The mass percentage of TPEE in the PA / TPEE blended protective layer is 20-35%, and 0.3-0.8% of erucamide is added as a lubricant.

[0015] A method for preparing a multi-layer composite insulated wire, the method comprising the following steps:

[0016] (1) Conductor pretreatment: The copper wire is processed in an alkaline cleaning tank, an acid cleaning tank and an ultrasonic cleaning machine in sequence, and then blown dry after cleaning;

[0017] (2) Material pretreatment:

[0018] a. First PEEK-based insulation layer raw material processing: PEEK resin is vacuum dried at 140-180°C for 6-12 hours, with a moisture content of ≤80ppm; nano-titanium dioxide is modified with stearic acid;

[0019] b. Second PEEK modified insulation layer raw material processing - Boron nitride nanosheets are sequentially subjected to hydrochloric acid ultrasonic dispersion, deionized water washing, and vacuum drying at 120°C;

[0020] c. PA / TPEE blend protective layer raw material processing: PA6 is baked at 140℃ for 6 hours, and TPEE is baked at 120℃ for 4 hours;

[0021] (3) Layered co-extrusion molding:

[0022] a. First layer extrusion: Using a twin-screw extruder, set the temperature segmentation to 295-320℃ for the feeding section, 320-330℃ for the compression section, 340-350℃ for the metering section, and 350-360℃ for the die head. The first PEEK-based insulation layer raw material is melt-extruded to coat the conductor;

[0023] b. Second layer extrusion: The co-rotating extruder melts and extrude the second PEEK modified insulation layer raw material to cover the first PEEK-based insulation layer. The temperature is increased by 5-10°C and the screw speed is reduced by 10-20 rpm.

[0024] c. Third layer extrusion: Conical twin-screw extruder processes PA / TPEE blend to coat the second PEEK modified insulation layer, with the die temperature at 310-325°C;

[0025] (4) Gradient cooling solidification:

[0026] a. Air slow cooling section, cooling rate 5-10℃ / min, length 1-2m;

[0027] b. Hot water quenching section, water temperature 80-95℃, length 2-3m;

[0028] c. Secondary crystallization stage, hot air circulation at 60-75℃, wind speed 0.5-1.2m / s;

[0029] d. Room temperature setting section, cooling water flow rate 10-15L / min;

[0030] (5) Online testing: Products that pass the test are multi-layer composite insulated wires.

[0031] The specific steps of modifying the nano-titanium dioxide with stearic acid are as follows: mixing the nano-titanium dioxide and molten stearic acid in a mass ratio of 1:0.1-0.25, stirring at 80-120° C. for 30-60 minutes, and centrifuging to obtain the modified nano-titanium dioxide powder.

[0032] The screw aspect ratio of step (3)a is 28:1, the melt pressure is maintained at 12-18 MPa, and the die lip gap is adjusted with an accuracy of ±0.01 mm;

[0033] The hot water quenching section of step (4) b adopts a three-stage gradient cooling: the first section is at a water temperature of 90-95°C, staying for 30-40 seconds, the second section is at 80-85°C, staying for 50-70 seconds, and the third section is at 60-65°C, staying for 2-3 minutes;

[0034] The melt blending temperature of the PA / TPEE blended protective layer in step (3) c is 270-290°C, and the screw shear rate is controlled to 150-200s -1 When erucamide is added, inert gas is injected simultaneously to prevent oxidation.

[0035] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0036] 1. This application effectively solves the core problems faced by traditional PEEK insulated wires, such as high cost, poor processing performance, weak interface bonding, and insufficient environmental protection, through the design of multi-layer composite insulated wire structure and optimization of preparation process, and achieves performance improvement through functional layered structure and precise process control.

[0037] 2. To control material costs, a three-layer composite structure replaces the pure PEEK insulation layer. A modified second insulation layer reduces PEEK resin usage, while a PA / TPEE blend outer layer balances cost and performance. This PA6 / TPEE blend retains the elastomeric properties of TPEE while leveraging the heat resistance of PA to create an economical protective layer. The compatibility of TPEE and PA is optimized through a melt blending process, avoiding the sudden drop in temperature resistance typically associated with PET incorporation and maintaining stable performance at operating temperatures between 150°C and 180°C.

[0038] 3. Stearic acid-modified nano-titanium dioxide is added to the first layer. The surface active groups form a physical anchoring effect with the PEEK molecular chains, improving dielectric strength while reducing melt viscosity. In the second layer, boron nitride nanosheets and maleic anhydride-grafted SEBS work synergistically. The former creates a three-dimensional thermal network to accelerate heat diffusion, while the latter alleviates stress concentration caused by the addition of polyphenylene sulfide through interfacial volume expansion. In conjunction with a differentiated temperature control strategy during the three-layer co-extrusion process, precise matching of melt flow rates is achieved by reducing the processing temperature of the second layer and adjusting the screw speed.

[0039] 4. The thermal expansion coefficient gradient design of the multi-layer material strengthens the interfacial bonding. The first layer of PEEK matrix forms a rigid bond with the conductor core, the second layer introduces polyphenylene sulfide to enhance the temperature resistance of the interlayer, and the outer PA / TPEE blend layer forms a flexible transition through molecular chain entanglement. The thermal expansion coefficient of the three-layer structure increases in a step-by-step manner from the inside to the outside, effectively buffering the interfacial stress generated by temperature changes. Experiments show that the structure maintains an intact interface after 1000 cycles of -40-180°C heating and cooling, and the delamination rate is reduced to less than 0.5%.

[0040] 5. The use of co-rotating twin-screw co-extrusion equipment shortens the processing flow and reduces the volatile organic compounds (VOCs) generated by traditional multi-step production. The gradient cooling system integrates slow air cooling and rapid hot water cooling, achieving significant energy savings compared to pure water cooling. A specially designed secondary crystallization section regulates the crystallization rate through hot air circulation, increasing the uniformity of PEEK crystallinity to over 92%, while avoiding the microporous defects caused by rapid cooling in traditional processes.

[0041] 6. The migration properties of erucamide in the outer PA / TPEE blend create a self-lubricating surface, reducing the coefficient of friction while maintaining tensile strength. The two-dimensional structural alignment of the inner boron nitride nanosheets enhances radial compressive strength, and combined with the enhanced interfacial bonding provided by the silane coupling agent, improves the overall scratch resistance of the composite insulated wire.

[0042] 7. The synergistic effect of multiple dielectric layers improves electrical performance reliability. The first layer of nano-titanium dioxide creates electron traps to suppress leakage current, the second layer of boron nitride nanosheets provides high thermal conductivity to dissipate localized heat, and the low dielectric constant of the outer layer of PA / TPEE mitigates electric field distortion. The three-layer composite structure achieves a breakdown field strength of 45kV / mm, approximately 60% higher than single-layer PEEK insulated wire, and keeps partial discharge below 5pC. DETAILED DESCRIPTION

[0043] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0044] In this application, the sources of various raw materials are briefly described as follows:

[0045] Tinned copper wire raw material for metal conductor core wire: purchased from China Aluminum Luotong Materials Co., Ltd., model is T2 tinned copper wire, in line with GB / T 4910-2009 standard.

[0046] PEEK resin: purchased from Evonik Industries AG, Germany, with CAS number 29658-26-2 and model VESTAKEEP4000G.

[0047] Nano-titanium dioxide: purchased from Pangang Group Vanadium Titanium Resources Co., Ltd., CAS No. 13463-67-7, model CR-50, particle size range 15-35 nm.

[0048] Silane coupling agent: purchased from Nanjing Shuguang Chemical Group Co., Ltd., CAS No. 919-30-2, model KH-550.

[0049] Antioxidant 1010: purchased from BASF, Germany, with CAS number 6683-19-8 and model number IRGANOX 1010.

[0050] Polyphenylene sulfide: purchased from Zhejiang Xinhecheng Co., Ltd., CAS No. 26125-40-6, model XH-330G.

[0051] Maleic anhydride grafted SEBS: purchased from Kraton Corporation of the United States, CAS No. 66070-58-4, model KRATONFG1901X.

[0052] Boron nitride nanosheets: purchased from Hefei Fenghua New Materials Co., Ltd., CAS number 10043-11-5, model FH-BNNS-01, thickness 5-15 nm.

[0053] PA6 resin: purchased from DuPont Company of the United States, CAS No. 25038-54-4, model ZYTEL 101L.

[0054] TPEE elastomer: purchased from Toray Industries, Ltd. of Japan, CAS No. 25038-04-8, model Hytrel 7248.

[0055] Erucamide: purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., CAS No. 112-84-5, model E279508.

[0056] Stearic acid: purchased from Sinopharm Chemical Reagent Co., Ltd., CAS No. 57-11-4, model No. 20110216.

[0057] The meanings of the relevant English abbreviations in this application are:

[0058] PEEK, short for Polyether Ether Ketone, is a special engineering plastic with the characteristics of high temperature resistance (long-term use temperature 260°C), corrosion resistance, and high mechanical strength. It is used as the core material of the insulation layer in this article.

[0059] PA stands for polyamide, which is nylon material (such as PA6, PA66, etc.). It is used as the outer protective layer material in this article to provide mechanical protection and wear resistance.

[0060] TPEE, short for Thermoplastic Polyester Elastomer, is a material that combines rubber elasticity with plastic processing properties. Here, it is compounded with PET for a protective layer, balancing flexibility and temperature resistance.

[0061] A multi-layer composite insulated wire comprises a metal conductor core wire and a three-layer composite insulation structure sequentially coated on its periphery. The three-layer composite insulation structure comprises, from the inside to the outside, a first PEEK-based insulation layer, a second PEEK-modified insulation layer, and a PA / TPEE blended protective layer.

[0062] The metal conductor core wire is an annealed tinned copper wire with a diameter of 0.05-2.5 mm, an annealing temperature of 220-280° C., and an annealing time of 15-45 minutes.

[0063] The first PEEK-based insulating layer comprises the following components in parts by mass: 12-18 parts of PEEK resin, 2-4 parts of nano-titanium dioxide, 0.5-1.2 parts of silane coupling agent, and 0.2-0.8 parts of antioxidant 1010.

[0064] The particle size of the nano titanium dioxide is 15-35nm, and the specific surface area is 50-80m 2 / g; the surface of the nano titanium dioxide is modified with stearic acid.

[0065] The second PEEK modified insulating layer is formed by melt blending the following components: 8-15 parts of PEEK resin, 3-6 parts of polyphenylene sulfide, 1-3 parts of maleic anhydride grafted SEBS, and 0.5-1.5 parts of boron nitride nanosheets.

[0066] The boron nitride nanosheet has a thickness of 5-15 nm and a lateral size of 200-500 nm.

[0067] The mass percentage of TPEE in the PA / TPEE blended protective layer is 20-35%, and 0.3-0.8% of erucamide is added as a lubricant.

[0068] A method for preparing a multi-layer composite insulated wire, the method comprising the following steps:

[0069] (1) Conductor pretreatment: The copper wire is processed in an alkaline cleaning tank, an acid cleaning tank and an ultrasonic cleaning machine in sequence, and then blown dry after cleaning;

[0070] (2) Material pretreatment:

[0071] a. First PEEK-based insulation layer raw material processing: PEEK resin is vacuum dried at 140-180°C for 6-12 hours, with a moisture content of ≤80ppm; nano-titanium dioxide is modified with stearic acid;

[0072] b. Second PEEK modified insulation layer raw material processing - Boron nitride nanosheets are sequentially subjected to hydrochloric acid ultrasonic dispersion, deionized water washing, and vacuum drying at 120°C;

[0073] c. PA / TPEE blend protective layer raw material processing: PA6 is baked at 140℃ for 6 hours, and TPEE is baked at 120℃ for 4 hours;

[0074] (3) Layered co-extrusion molding:

[0075] a. First layer extrusion: Using a twin-screw extruder, set the temperature segmentation to 295-320℃ for the feeding section, 320-330℃ for the compression section, 340-350℃ for the metering section, and 350-360℃ for the die head. The first PEEK-based insulation layer raw material is melt-extruded to coat the conductor;

[0076] b. Second layer extrusion: The co-rotating extruder melts and extrude the second PEEK modified insulation layer raw material to cover the first PEEK-based insulation layer. The temperature is increased by 5-10°C and the screw speed is reduced by 10-20 rpm.

[0077] c. Third layer extrusion: Conical twin-screw extruder processes PA / TPEE blend to coat the second PEEK modified insulation layer, with the die temperature at 310-325°C;

[0078] (4) Gradient cooling solidification:

[0079] a. Air slow cooling section, cooling rate 5-10℃ / min, length 1-2m;

[0080] b. Hot water quenching section, water temperature 80-95℃, length 2-3m;

[0081] c. Secondary crystallization stage, hot air circulation at 60-75℃, wind speed 0.5-1.2m / s;

[0082] d. Room temperature setting section, cooling water flow rate 10-15L / min;

[0083] (5) Online testing: Products that pass the test are multi-layer composite insulated wires.

[0084] The specific steps of modifying the nano-titanium dioxide with stearic acid are as follows: mixing the nano-titanium dioxide and molten stearic acid in a mass ratio of 1:0.1-0.25, stirring at 80-120° C. for 30-60 minutes, and centrifuging to obtain the modified nano-titanium dioxide powder.

[0085] The screw aspect ratio of step (3)a is 28:1, the melt pressure is maintained at 12-18 MPa, and the die lip gap is adjusted with an accuracy of ±0.01 mm;

[0086] The hot water quenching section of step (4) b adopts a three-stage gradient cooling: the first section is at a water temperature of 90-95°C, staying for 30-40 seconds, the second section is at 80-85°C, staying for 50-70 seconds, and the third section is at 60-65°C, staying for 2-3 minutes;

[0087] The melt blending temperature of the PA / TPEE blended protective layer in step (3) c is 270-290°C, and the screw shear rate is controlled to 150-200s -1 When erucamide is added, inert gas is injected simultaneously to prevent oxidation.

[0088] The technical solution of the present invention is further illustrated by the following examples and comparative examples, but the protection scope of the present invention is not limited thereto.

[0089] Example 1

[0090] When preparing the multi-layer composite insulated wire, the metal conductor core wire is selected to have a diameter of 0.05 mm, an annealing temperature of 220° C., and a annealing time of 15 minutes.

[0091] The first PEEK-based insulating layer contains 12 parts of PEEK resin and 2 parts of nano-titanium dioxide (particle size 15 nm, specific surface area 50 m 2 / g), 0.5 parts of silane coupling agent, 0.2 parts of antioxidant 1010, stearic acid modification ratio of 1:0.1, treatment temperature of 80 ° C, time of 30 minutes.

[0092] The second PEEK modified insulating layer contains 15 parts of PEEK resin, 6 parts of polyphenylene sulfide, 3 parts of maleic anhydride grafted SEBS, and 1.5 parts of boron nitride nanosheets (thickness 15 nm, lateral size 500 nm).

[0093] Boron nitride was pretreated by ultrasonic dispersion of 12 mol / L hydrochloric acid for 30 minutes. The mass percentage of TPEE in the PA / TPEE blend protective layer was 20%, and erucamide was added at 0.8%.

[0094] In the layered co-extrusion process, the first-layer extruder temperature was set at 320°C in the feeding section, 330°C in the compression section, 350°C in the metering section, and 360°C in the die head. The screw aspect ratio was 28:1, and the melt pressure was 18 MPa. The second-layer extrusion temperature was increased by 10°C, and the screw speed was reduced by 20 rpm.

[0095] The third layer die temperature is 325℃ and the shear rate is 200s -1 , inert gas flow rate 15L / h. Gradient cooling stage: air slow cooling rate 10℃ / min, length 2m; hot water quenching three stages at 95℃ (40 seconds), 85℃ (70 seconds), and 65℃ (3 minutes); secondary crystallization stage at 75℃ hot air circulation speed 1.2m / s; room temperature setting stage cooling water flow 15L / min.

[0096] Example 2

[0097] In this embodiment, the same points as in Example 1 are not described in detail, and the differences are as follows:

[0098] The metal conductor core wire is a tinned copper wire with a diameter of 2.5 mm. The annealing temperature is set to 280° C. and the annealing time is 45 minutes.

[0099] The first PEEK-based insulating layer material is 18 parts of PEEK resin, 4 parts of nano titanium dioxide (particle size 35nm, specific surface area 80m 2 / g), 1.2 parts of silane coupling agent, 10100.8 parts of antioxidant. Nano-titanium dioxide and stearic acid are modified in a mass ratio of 1:0.25, the treatment temperature is 120°C, and the time is 60 minutes.

[0100] The second layer contained 11 parts of PEEK resin, 4.5 parts of polyphenylene sulfide, 2 parts of maleic anhydride grafted SEBS, and 1.0 part of boron nitride nanosheets (thickness 10 nm, lateral size 350 nm). The hydrochloric acid concentration was 6 mol / L and ultrasonically treated for 20 minutes.

[0101] The mass percentage of TPEE is 30%, and the mass percentage of erucamide is 0.55%.

[0102] Coextrusion temperature: First layer feeding section 305℃, compression section 325℃, metering section 345℃, die head 355℃; second layer temperature increased by 5℃, screw speed reduced by 10rpm; third layer die head temperature 310℃, shear rate 150s -1 .

[0103] Cooling process: air slow cooling rate 8℃ / min, length 1.5m; hot water rapid cooling three stages with water temperature 92℃ (35 seconds), 82℃ (60 seconds), and 63℃ (2.5 minutes); secondary crystallization stage with wind speed 0.8m / s at 68℃; cooling water flow rate 12L / min.

[0104] Example 3

[0105] In this embodiment, the same points as in Example 1 are not described in detail, and the differences are as follows:

[0106] Conductor diameter 1.25mm, annealing temperature 250℃, time 30 minutes. The first layer of PEEK resin 15 parts, nano titanium dioxide 3 parts (particle size 25nm, specific surface area 65m 2 / g), 0.8 parts of silane coupling agent, 0.5 parts of antioxidant, 1010, stearic acid modification ratio of 1:0.18, treatment temperature of 100 ° C, time of 45 minutes.

[0107] The second PEEK modified insulation layer contains 8 parts of PEEK resin, 3 parts of polyphenylene sulfide, 1 part of maleic anhydride grafted SEBS, and 0.5 parts of boron nitride nanosheets (5 nm thick, 200 nm lateral dimension), and is treated with 9 mol / L hydrochloric acid for 45 minutes.

[0108] The mass percentage of TPEE is 35%, and the mass percentage of erucamide is 0.3%.

[0109] Coextrusion parameters: first layer feeding section 295℃, compression section 320℃, metering section 340℃, die head 350℃; second layer temperature increased by 8℃, third layer shear rate 175s -1 .

[0110] Cooling stage: air slow cooling rate 5℃ / min, length 1m; hot water rapid cooling three stages: water temperature 90℃ (30 seconds), 80℃ (50 seconds), 60℃ (2 minutes); secondary crystallization stage 60℃ wind speed 0.5m / s; cooling water flow rate 10L / min.

[0111] Comparative Example 1

[0112] In this comparative example, the same points as in Example 1 are not repeated here, and the differences are as follows:

[0113] The second PEEK modified insulation layer is omitted, and only the double-layer structure is retained.

[0114] Comparative Example 2

[0115] In this comparative example, the same points as Example 2 are not repeated here, and the differences are as follows:

[0116] The proportion of TPEE in the PA / TPEE layer is 40%, which exceeds the upper limit of the technical solution.

[0117] Comparative Example 3

[0118] In this comparative example, the same points as in Example 3 are not repeated here, and the differences are as follows:

[0119] No gradient cooling was performed, and single water cooling (20°C) was used.

[0120] Comparative Example 4

[0121] In this comparative example, the same points as in Example 1 are not repeated here, and the differences are as follows:

[0122] The boron nitride nanosheets were replaced with an equal amount of glass fibers.

[0123] Comparative Example 5

[0124] In this comparative example, the same points as in Example 1 are not repeated here, and the differences are as follows:

[0125] No nano-titanium dioxide was added to the first layer.

[0126] Performance test results and analysis

[0127] Products were prepared according to the parameters of the embodiment and the comparative example, and the obtained multi-layer composite insulated wire was subjected to performance tests. The test results are shown in Table 1.

[0128] Table 1 Analysis and test results

[0129]

[0130] Test results show that the breakdown field strength of the multilayer composite insulated wire in the examples is significantly higher than that of conventional PEEK insulated wire (approximately 28 kV / mm), due to the dielectric synergy of the three-layer structure. The first layer of nano-titanium dioxide suppresses leakage current by trapping electrons, the second layer of boron nitride nanosheets creates a thermal network to dissipate local heat, and the low dielectric constant of the outer layer of PA / TPEE mitigates electric field distortion. The breakdown field strength of Comparative Example 5 (without nano-titanium dioxide) dropped to 34.6 kV / mm, confirming the key role of nanoparticles in electric field regulation.

[0131] In Examples 1-3, the thermal expansion coefficient of the three layers of PEEK-modified layer-PA / TPEE is increased in a step-by-step manner, and the delamination rate after hot and cold cycles is less than 0.5%. In Comparative Example 1, the second layer is omitted, and the delamination rate soars to 8.2%, highlighting the stress buffering effect of the intermediate layer. This indirectly proves that the second layer of maleic anhydride grafted SEBS alleviates the stress concentration of polyphenylene sulfide through interfacial compatibilization.

[0132] The embodiment adopts a gradient cooling of slow cooling with air → rapid cooling with hot water → secondary crystallization, so that the uniformity of PEEK crystallinity reaches 92%, avoiding microporous defects. Comparative Example 3 is single water cooling, the melt flow rate is only 12.4g / 10min (66% of the embodiment), and the delamination rate is 2.1%, indicating that rapid cooling causes disordered arrangement of molecular chains. The extrusion temperature of the second layer is increased by 5-10°C and the screw speed is reduced to adjust the melt flow rate matching and avoid excessive eccentricity. PA6 and TPEE blending maintains the stability of the working condition of 150-180°C while reducing costs, avoiding the strength retention rate of only 65.3% in Comparative Example 2 due to the sudden drop in temperature resistance.

[0133] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A multi-layer composite insulated wire, characterized in that: It includes a metal conductor core wire and a three-layer composite insulation structure sequentially wrapped around the outer periphery. The three-layer composite insulation structure is sequentially composed of a first PEEK-based insulation layer, a second PEEK modified insulation layer and a PA / TPEE blended protective layer from the inside to the outside.

2. The multi-layer composite insulated wire according to claim 1, characterized in that: The metal conductor core wire is an annealed tinned copper wire with a diameter of 0.05-2.5 mm, an annealing temperature of 220-280° C., and an annealing time of 15-45 minutes.

3. The multi-layer composite insulated wire according to claim 1, characterized in that: The first PEEK-based insulating layer comprises the following components in parts by mass: 12-18 parts of PEEK resin, 2-4 parts of nano-titanium dioxide, 0.5-1.2 parts of silane coupling agent, and 0.2-0.8 parts of antioxidant 1010.

4. The multi-layer composite insulated wire according to claim 3, characterized in that: The particle size of the nano titanium dioxide is 15-35nm, and the specific surface area is 50-80m 2 / g; the surface of the nano titanium dioxide is modified with stearic acid.

5. The multi-layer composite insulated wire according to claim 1, characterized in that: The second PEEK modified insulating layer is formed by melt blending the following components: 8-15 parts of PEEK resin, 3-6 parts of polyphenylene sulfide, 1-3 parts of maleic anhydride grafted SEBS, and 0.5-1.5 parts of boron nitride nanosheets.

6. The multi-layer composite insulated wire according to claim 5, characterized in that: The boron nitride nanosheet has a thickness of 5-15 nm and a lateral size of 200-500 nm.

7. The multi-layer composite insulated wire according to claim 1, characterized in that: The mass percentage of TPEE in the PA / TPEE blended protective layer is 20-35%, and 0.3-0.8% of erucamide is added as a lubricant.

8. A method for preparing the multi-layer composite insulated wire according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: (1) Conductor pretreatment: The copper wire is processed in an alkaline cleaning tank, an acid cleaning tank and an ultrasonic cleaning machine in sequence, and then blown dry after cleaning; (2) Material pretreatment: a. First PEEK-based insulation layer raw material processing: PEEK resin is vacuum dried at 140-180°C for 6-12 hours, with a moisture content of ≤80ppm; nano-titanium dioxide is modified with stearic acid; b. Second PEEK modified insulation layer raw material processing - Boron nitride nanosheets are sequentially subjected to hydrochloric acid ultrasonic dispersion, deionized water washing, and vacuum drying at 120°C; c. PA / TPEE blend protective layer raw material processing: PA6 is baked at 140℃ for 6 hours, and TPEE is baked at 120℃ for 4 hours; (3) Layered co-extrusion molding: a. First layer extrusion: Using a twin-screw extruder, set the temperature segmentation to 295-320℃ for the feeding section, 320-330℃ for the compression section, 340-350℃ for the metering section, and 350-360℃ for the die head. The first PEEK-based insulation layer raw material is melt-extruded to coat the conductor; b. Second layer extrusion: The co-rotating extruder melts and extrude the second PEEK modified insulation layer raw material to cover the first PEEK-based insulation layer. The temperature is increased by 5-10°C and the screw speed is reduced by 10-20 rpm. c. Third layer extrusion: Conical twin-screw extruder processes PA / TPEE blend to coat the second PEEK modified insulation layer, with the die temperature at 310-325°C; (4) Gradient cooling solidification: a. Air slow cooling section, cooling rate 5-10℃ / min, length 1-2m; b. Hot water quenching section, water temperature 80-95℃, length 2-3m; c. Secondary crystallization stage, hot air circulation at 60-75℃, wind speed 0.5-1.2m / s; d. Room temperature setting section, cooling water flow rate 10-15L / min; (5) Online testing: Products that pass the test are multi-layer composite insulated wires.

9. The method for preparing a multi-layer composite insulated wire according to claim 8, wherein: The specific steps of modifying the nano-titanium dioxide with stearic acid are as follows: mixing the nano-titanium dioxide and molten stearic acid in a mass ratio of 1:0.1-0.25, stirring at 80-120° C. for 30-60 minutes, and centrifuging to obtain the modified nano-titanium dioxide powder.

10. The method for preparing a multi-layer composite insulated wire according to claim 8, wherein: The screw aspect ratio of step (3)a is 28:1, the melt pressure is maintained at 12-18 MPa, and the die lip gap is adjusted with an accuracy of ±0.01 mm; The hot water quenching section of step (4) b adopts a three-stage gradient cooling: the first section is at a water temperature of 90-95°C, staying for 30-40 seconds, the second section is at 80-85°C, staying for 50-70 seconds, and the third section is at 60-65°C, staying for 2-3 minutes; The melt blending temperature of the PA / TPEE blended protective layer in step (3) c is 270-290°C, and the screw shear rate is controlled to 150-200s -1 When erucamide is added, inert gas is injected simultaneously to prevent oxidation.

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