Tin-plated copper core polytetrafluoroethylene propylene insulated wires for aerospace applications and their preparation method

Abstract

The application discloses a kind of aerospace aviation with tin-plated copper core poly perfluoroethylene propylene insulated electric wires and preparation method, it is related to special wire and cable manufacturing technical field.The preparation method includes S1: preparation modified FEP composite material;S2: pretreatment is carried out to extruder;S3: using double-stage decompression type extrusion process, the modified FEP composite material of step S1 is extruded and covered tin-plated copper core forming;S4: using the step cooling mode of partition temperature control to the tin-plated copper core line after covering is cooled.The application is successfully solved the apparent defect problem when FEP high-speed extrusion by the combination technology of " modified formula + vacuum exhaust + step cooling", screw rotation speed can be promoted from traditional <20rpm to 35-50rpm, production efficiency can be improved more than one time, and product surface is smooth, dense, realize high-efficiency defect-free extrusion.

Description

Technical Field

[0001] This invention relates to the field of special wire and cable manufacturing technology, and in particular to a method for manufacturing tin-plated copper core poly(fluoroethylene propylene) (FEP) insulated wires for use in the aerospace field. Specifically, it is a processing method and formulation system that can effectively suppress surface defects in the FEP insulation layer during rapid extrusion. Background Technology

[0002] Perfluoroethylene propylene (FEP) is an ideal material for insulation layers of electrical wires used in aerospace applications due to its excellent electrical properties, wide temperature range, extremely low dielectric constant and loss factor, and non-flammability. However, FEP resin presents significant technical challenges during melt extrusion molding: its high melt viscosity, low melt strength, and rapid crystallization rate from the molten state to the crystalline state. These characteristics lead to air bubbles, pores, and gaps easily forming within the melt under conventional high-speed extrusion processes. Simultaneously, the unstable flow of the melt at the die and the internal stress generated by rapid crystallization can easily cause defects such as glue leakage, poor plasticization, roughness, or wrinkles on the insulation surface. These surface defects can severely impair the electrical performance of wires (e.g., reduced partial discharge voltage), mechanical integrity (becoming the starting point for stress cracking), and environmental sealing (corrosive media intrusion), posing a potential risk to aerospace equipment with extremely high reliability requirements.

[0003] Currently, to ensure quality, the industry mostly uses low-speed extrusion (such as screw speed below 20 rpm) and high draw ratio processes to produce FEP insulation layers. However, this severely sacrifices production efficiency and cannot meet the manufacturing needs of large-scale, long cables. Therefore, developing a method to improve the extrusion efficiency of FEP insulation layers while ensuring high quality has become an urgent technical problem to be solved in this field. Summary of the Invention

[0004] To address the issues of low efficiency and easy surface defects in existing FEP insulation extrusion processes, a new processing method and matching formula are provided. This method significantly improves extrusion line speed and production efficiency while obtaining a smooth, dense, and defect-free FEP insulation layer.

[0005] The technical solution of the present invention is as follows:

[0006] The aerospace-grade tin-plated copper core polytetrafluoroethylene (PTFE) insulated wire includes a tin-plated copper core and a PTFE insulation layer covering the tin-plated copper core. The PTFE insulation layer is made of modified FEP composite material and is coated onto the tin-plated copper core through an extrusion process.

[0007] The method for preparing the aerospace-grade tin-plated copper core polytetrafluoroethylene propylene insulated wire includes the following steps:

[0008] S1: Preparation of modified FEP composite materials;

[0009] S2: Pre-treatment of the extruder;

[0010] S3: The modified FEP composite material from step S1 is extruded and coated with a tin-plated copper core using a two-stage decompression extrusion process.

[0011] S4: A stepped cooling method with zoned temperature control is used to cool the coated tin-plated copper core wire.

[0012] In step S1, the modified FEP composite material is composed of the following raw material components in parts by weight: 100 parts of FEP resin, 0.5-2 parts of surface-modified nano silica, 0.1-0.5 parts of perfluoropolyether processing aid, and 0.05-0.2 parts of sodium phenyl phosphate.

[0013] In some specific embodiments, the raw material components further include 0-2.5 parts of inorganic pigment, preferably 0.5-2.5 parts; the inorganic pigment is selected from one of rutile titanium dioxide (TiO2), high-purity carbon black, cobalt blue (CoO·Al2O3), chromium oxide green (Cr2O3), iron oxide red (Fe2O3), or molybdenum chromium red, and cadmium sulfide (CdS). The inorganic pigment must be thermally stable at 350°C for at least 30 minutes without decomposition or discoloration, and its addition must not cause a change in the dielectric constant of the FEP insulating layer exceeding ±10% or a significant increase in the dielectric loss factor.

[0014] The surface-modified nano-silica is prepared by surface modification treatment of nano-SiO2 with a silane coupling agent, and the steps are as follows:

[0015] 1) Disperse nano-SiO2 in a mixed solvent of anhydrous ethanol and deionized water to prepare a nano-SiO2 suspension with a solid content of 10-15 wt%.

[0016] 2) Add the silane coupling agent dropwise to an acidic ethanol-water solution with a pH of 4-5 to hydrolyze it into silanol (Si-OH), thus obtaining a silane coupling agent hydrolysate;

[0017] 3) The hydrolysate of the silane coupling agent is slowly added dropwise to the nano-SiO2 suspension prepared in step 1) under stirring conditions, and the temperature of the reaction system is controlled at 60±2℃ during the process;

[0018] 4) After the addition is complete, maintain the temperature and stirring speed, and continue the reaction for 4-5 hours;

[0019] 5) After the reaction is complete, the mixture is filtered, washed with anhydrous ethanol, dried, and ground to obtain surface-modified nano-silica.

[0020] Preferably, the particle size of the nano-SiO2 is 20-30 nm; the silane coupling agent is selected from γ-aminopropyltriethoxysilane (KH-550) or γ-(methacryloyloxy)propyltrimethoxysilane (KH-570); the amount of the silane coupling agent is 2.0-4.0% of the mass of the nano-SiO2.

[0021] In some specific embodiments, the preparation method of the surface-modified nano-silica is as follows:

[0022] 1) Disperse nano-SiO2 in a mixed solvent of anhydrous ethanol and deionized water at a mass ratio of 8:2 to prepare a nano-SiO2 suspension with a solid content of 10-15wt%; place the nano-SiO2 suspension in an ultrasonic disperser and ultrasonically disperse it for 60 minutes at a power of 800W and a temperature of 25℃ to fully deagglomerate the nano-SiO2 and form a uniform and stable suspension system.

[0023] 2) Add silane coupling agent KH-550 or KH-570 dropwise to an acidic ethanol-water solution with a pH of 4-5, wherein the mass ratio of silane coupling agent to acidic ethanol-water solution is 1:20; under magnetic stirring, hydrolyze in a 50°C water bath for 30 minutes to fully hydrolyze it to generate silanol (Si-OH), thus obtaining a silane coupling agent hydrolysate;

[0024] 3) The hydrolysate of the silane coupling agent is slowly added dropwise to the nano-SiO2 suspension prepared in step 1) under stirring at 500-600 rpm (the addition is completed within 30 minutes using a constant pressure dropping funnel), and the temperature of the reaction system is controlled at 60±2℃ during the process.

[0025] 4) After the addition is complete, maintain the temperature and stirring speed, and continue the reaction for 4-5 hours to allow the hydrolyzed silane coupling agent to undergo a full condensation reaction with the silanol groups on the surface of nano-SiO2, forming a strong -Si-O-Si- chemical bond, thereby grafting an organic functional group molecular layer onto the surface of nano-SiO2 particles.

[0026] 5) After the reaction is complete, the mixture is filtered. The resulting filter cake is washed repeatedly with anhydrous ethanol 3-5 times to remove excess silane coupling agent, byproducts and solvent. The washed filter cake is then placed in a vacuum drying oven and dried at 80°C for 12 hours. The dried block material is then lightly ground and passed through a 500-mesh sieve to obtain surface-modified nano silica with hydrophobic surface and good flowability. It is then sealed and stored for later use.

[0027] The perfluoropolyether processing aids can be selected from DuPont's Viton® FreeFlow FF, 3M's Dyneon™ series of fluoropolymer processing aids, or Solvay's Polymist® ultrafine polytetrafluoroethylene (PTFE) powder, etc. Perfluoropolyether processing aids are low-molecular-weight fluorinated surfactants or fluorinated polymer processing aids with extremely high thermal stability and chemical inertness. Their molecular backbone is composed of carbon, oxygen, and fluorine atoms (such as -CF2-CF2-O-, -CF2-O-, etc.), and the ends usually have functional groups that impart certain functions (such as -CF3, -COOH, -OH). Their mechanism of action is as follows: during processing, due to their incompatibility with ordinary polymers and extremely low surface tension, they migrate from the melt to the metal (mold / barrel) interface and the melt surface, forming a lubricating film. This significantly reduces the frictional resistance between the melt and the equipment, as well as the viscous dissipation within the melt, thereby eliminating surface defects.

[0028] The modified FEP composite material of the present invention was prepared by melt blending and extrusion granulation, as detailed below:

[0029] Premixing: According to the raw material composition ratio of the modified FEP composite material, place the FEP resin, surface-modified nano silica, perfluoropolyether processing aid, sodium phenyl phosphate and inorganic pigment in a high-speed mixer (such as a Henschel mixer) and mix at 500-1000 rpm for 5-10 minutes at room temperature to ensure that each component is uniformly dispersed.

[0030] Melt blending and granulation: The premixed material is fed into a twin-screw extruder for melt blending, extrusion and granulation;

[0031] The extruder temperature range is set to 250℃-300℃, and the screw speed is 200-300 rpm. During the extrusion process, the melt is evacuated and degassed (vacuum degree ≥-0.08MPa) to remove moisture and low molecular weight volatiles that may be introduced during the mixing process, thereby reducing the generation of pores from the source.

[0032] Cooling and pelletizing: The extruded strip melt is cooled by a water bath at a temperature of 20-40℃ and then cut into uniform pellets by a pelletizer.

[0033] Drying: Place the chopped granules in a forced-air drying oven and dry at 100-120℃ for 2-4 hours to obtain the modified FEP composite material.

[0034] The pretreatment in step S2 specifically involves cleaning the extruder with fluoroplastic cleaning material before extrusion begins, and spraying a stable perfluoropolyether lubricant film onto the inner surface of the die and the surface of the forming sleeve. The fluoroplastic cleaning material can be commercial products such as Chemours' Krytox® Purge Compound, 3M's Dyneon™ Fluoroplastic Purge Compound, or Clariant's CESA®-purge for Fluoropolymers. The cleaning temperature should be set within a range of 20-40°C higher than the normal FEP processing temperature, following the principle of "low speed, high pressure" until the extrudate is pure and free of contamination. The perfluoropolyether lubricant can be Chemours' Krytox® GPL 100 series, Solvay's Fomblin® Y-LVAC series, or equivalent commercial perfluoropolyether lubricant products.

[0035] In step S3, the two-stage decompression extrusion process specifically involves: using a two-stage screw extruder equipped with a vacuum exhaust device. The screw of the two-stage screw extruder is divided into a melting and plasticizing section (first stage) and a homogenization and decompression section (second stage). A vacuum extraction port is opened at the front end of the homogenization and decompression section to actively remove volatile substances and trapped gases from the melt through vacuuming. The process parameters are controlled as follows: the temperature of the melting and plasticizing section (first stage) is set to 300-330℃, and the temperature of the homogenization and decompression section (second stage) is set to 320-350℃; the screw speed is increased to 35-50 rpm; the die head pressure is controlled at 15-25 MPa; and the vacuum degree is maintained at -0.06 to -0.09 MPa.

[0036] In S4, the stepped cooling method with zoned temperature control specifically involves the tin-plated copper core wire passing through three cooling tanks sequentially after leaving the mold, as detailed below:

[0037] The first section (pre-cooling zone) uses warm water at 60-80℃ to cool the surface melt appropriately and set it in shape, avoiding internal stress caused by rapid cooling.

[0038] The second stage (main cooling zone): Cooled by room temperature water at 25-35℃, to complete the main crystallization process;

[0039] The third stage (final cooling zone): final cooling is performed using cold water at 15-25℃ to ensure complete curing of the insulation layer.

[0040] This invention successfully solves the problem of surface defects during high-speed FEP extrusion by combining "modified formula + vacuum degassing + stepped cooling" technology. The screw speed can be increased from the traditional <20rpm to 35-50rpm, the production efficiency can be increased by more than 100%, and the product surface is smooth and dense, achieving efficient and defect-free extrusion.

[0041] In this invention, the modified FEP composite material uses a synergistic formulation that builds a robust "molecular bridge" between inorganic nano-SiO2 and organic FEP resin through chemical bonding, greatly improving the compatibility and bonding force at the interface between the two phases and avoiding stress concentration points caused by poor compatibility. The modified nano-SiO2 surface changes from hydrophilic to hydrophobic, significantly improving its wettability with non-polar FEP resin, effectively preventing its re-aggregation in the resin matrix and ensuring uniform dispersion at the nanoscale. As a heterogeneous nucleation point, nano-SiO2 can refine the crystal structure, improve the density, surface hardness, and mechanical strength of the product, and reduce internal stress and surface roughness caused by uneven crystallization shrinkage. The perfluoropolyether processing aid can effectively reduce the coefficient of friction between the melt and the metal surface of the equipment and the melt viscosity, improve melt flowability, stabilize extrusion pressure, help the discharge of encapsulated gas, and suppress the generation of apparent defects. Sodium phenyl phosphate can synergistically regulate crystallization behavior, making crystallization faster and more uniform, and reducing internal stress caused by uneven crystallization rate.

[0042] This invention specifically optimizes the extrusion process of modified FEP composite materials, with vacuum degassing directly removing air bubbles; warm water precooling avoids defects such as sudden surface hardening and inner layer shrinkage and stretching caused by excessive temperature difference between the melt and cooling water; and mold pretreatment prevents scratches and flow instability caused by melt adhesion.

[0043] The FEP insulation layer prepared by this invention not only has excellent appearance quality, but also more uniform crystallinity. Its mechanical strength, crack resistance, and electrical properties (especially partial discharge resistance) are significantly improved, fully meeting the stringent requirements of aerospace wires. Attached Figure Description

[0044] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 The aerospace-grade tin-plated copper core polytetrafluoroethylene propylene insulated wire prepared in Example 1;

[0046] Figure 2 The aerospace-grade tin-plated copper core polytetrafluoroethylene propylene insulated wire prepared in Example 4;

[0047] Figure 3 The aerospace-grade tin-plated copper core polytetrafluoroethylene propylene insulated wire prepared in Example 6;

[0048] Figure 4 The wire prepared for Comparative Example 1;

[0049] Figure 5 The wire prepared for Comparative Example 2;

[0050] Figure 6 The wire prepared for Comparative Example 3;

[0051] Figure 7 The wire prepared for Comparative Example 4 (with the tin-plated copper core stripped).

[0052] Figure 8 The wire prepared for Comparative Example 5;

[0053] Figure 9 The wire prepared for Comparative Example 6. Detailed Implementation

[0054] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0056] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0057] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0058] The preparation methods of surface-modified nano silica A, surface-modified nano silica B, and surface-modified nano silica C involved in the following examples or comparative examples are as follows, and the particle size of the nano SiO2 used is 20-30nm.

[0059] The preparation method of surface-modified nano-silica A is as follows:

[0060] 1) Disperse nano-SiO2 in a mixed solvent of anhydrous ethanol and deionized water at a mass ratio of 8:2 to prepare a nano-SiO2 suspension with a solid content of 12wt%; place the nano-SiO2 suspension in an ultrasonic disperser and ultrasonically disperse it for 60 minutes at a power of 800W and a temperature of 25℃ to form a uniform and stable suspension system.

[0061] 2) Add silane coupling agent KH-550 (3.0% of the mass of nano-SiO2) dropwise to an acidic ethanol-water solution with a pH of 4.5. The mass ratio of silane coupling agent to acidic ethanol-water solution is 1:20. Under magnetic stirring, hydrolyze in a water bath at 50°C for 30 minutes to obtain silane coupling agent hydrolysate.

[0062] 3) The hydrolysate of the silane coupling agent was slowly added dropwise to the nano-SiO2 suspension prepared in step 1) under stirring at 550 rpm, and the temperature of the reaction system was controlled at 60±2℃.

[0063] 4) After the addition is complete, maintain the temperature and stirring speed, and continue the reaction for 4.5 hours;

[0064] 5) After the reaction is complete, the mixture is filtered and the resulting filter cake is washed repeatedly with anhydrous ethanol 4 times. The washed filter cake is then placed in a vacuum drying oven and dried at 80°C for 12 hours. The dried block material is then lightly ground and passed through a 500-mesh sieve to obtain surface-modified nano silica A, which is then sealed and stored for later use.

[0065] The preparation method of surface-modified nano-silica B is as follows:

[0066] 1) Disperse nano-SiO2 in a mixed solvent of anhydrous ethanol and deionized water in a mass ratio of 7:3 to prepare a nano-SiO2 suspension with a solid content of 10wt%; place the nano-SiO2 suspension in an ultrasonic disperser and ultrasonically disperse it for 50 minutes at a power of 800W and a temperature of 25℃ to form a uniform and stable suspension system.

[0067] 2) Add silane coupling agent KH-570 (2.0% of the mass of nano-SiO2) dropwise to an acidic ethanol-water solution with a pH of 4. The mass ratio of silane coupling agent to acidic ethanol-water solution is 1:18. Hydrolyze the solution in a 50°C water bath for 30 minutes under magnetic stirring to obtain a silane coupling agent hydrolysate.

[0068] 3) The hydrolysate of the silane coupling agent was slowly added dropwise to the nano-SiO2 suspension prepared in step 1) under stirring at 500 rpm, and the temperature of the reaction system was controlled at 60±2℃.

[0069] 4) After the addition is complete, maintain the temperature and stirring speed, and continue the reaction for 4 hours;

[0070] 5) After the reaction is complete, the mixture is filtered. The resulting filter cake is washed three times with anhydrous ethanol. The washed filter cake is then placed in a vacuum drying oven and dried at 85°C for 10 hours. The dried block material is then lightly ground and passed through a 500-mesh sieve to obtain surface-modified nano silica B, which is then sealed and stored for later use.

[0071] The preparation method of surface-modified nano-silica C is as follows:

[0072] 1) Disperse nano-SiO2 in a mixed solvent of anhydrous ethanol and deionized water at a mass ratio of 8:2 to prepare a nano-SiO2 suspension with a solid content of 15wt%; place the nano-SiO2 suspension in an ultrasonic disperser and ultrasonically disperse it for 70 minutes at a power of 800W and a temperature of 25℃ to form a uniform and stable suspension system.

[0073] 2) Add silane coupling agent KH-550 (4.0% of the mass of nano-SiO2) dropwise to an acidic ethanol-water solution with a pH of 5. The mass ratio of silane coupling agent to acidic ethanol-water solution is 1:20. Under magnetic stirring, hydrolyze in a water bath at 50°C for 30 minutes to obtain silane coupling agent hydrolysate.

[0074] 3) The hydrolysate of the silane coupling agent was slowly added dropwise to the nano-SiO2 suspension prepared in step 1) under stirring at 600 rpm, and the temperature of the reaction system was controlled at 60±2℃.

[0075] 4) After the addition is complete, maintain the temperature and stirring speed, and continue the reaction for 5 hours;

[0076] 5) After the reaction is complete, the mixture is filtered and the resulting filter cake is washed repeatedly with anhydrous ethanol 5 times. The washed filter cake is then placed in a vacuum drying oven and dried at 80°C for 15 hours. The dried block material is then lightly ground and passed through a 500-mesh sieve to obtain surface-modified nano silica C, which is then sealed and stored for later use.

[0077] The perfluoropolyether processing aid A is DuPont's Viton® FreeFlow FF.

[0078] Perfluoropolyether processing aid B is Solvay's Polymist® ultrafine polytetrafluoroethylene powder.

[0079] The preparation methods of the modified FEP composite material A, modified FEP composite material B, and modified FEP composite material C involved in the following examples or comparative examples are as follows.

[0080] The preparation method of modified FEP composite material A is as follows:

[0081] Premixing: By weight, place 100 parts of FEP resin, 1.5 parts of surface-modified nano silica A, 0.3 parts of perfluoropolyether processing aid A, and 0.1 parts of sodium phenyl phosphate into a Henschel mixer and mix at 800 rpm for 8 minutes at room temperature to ensure uniform dispersion of each component;

[0082] Melt blending and granulation: The premixed material is fed into a twin-screw extruder for melt blending, extrusion, and granulation; the extruder temperature range is set to 250℃-300℃ (the temperatures of the feeding section, compression section, metering section, die head, and die are set sequentially to 250℃→270℃→280℃→290℃→300℃), and the screw speed is 250 rpm; during the extrusion process, the melt is evacuated (vacuum degree -0.10MPa).

[0083] Cooling and pelletizing: The extruded strip melt is cooled in a water bath at a temperature of 30±5℃ and then cut into uniform pellets by a pelletizer.

[0084] Drying: Place the cut particles in a forced-air drying oven and dry at 110°C for 3 hours to obtain the modified FEP composite material A.

[0085] The preparation method of modified FEP composite material B is as follows:

[0086] Premixing: By weight, place 100 parts of FEP resin, 0.5 parts of surface-modified nano silica B, 0.1 parts of perfluoropolyether processing aid B, and 0.05 parts of sodium phenyl phosphate into a Henschel mixer and mix at 500 rpm for 10 minutes at room temperature to ensure uniform dispersion of each component.

[0087] Melt blending and granulation: The premixed material is fed into a twin-screw extruder for melt blending, extrusion, and granulation; the extruder temperature range is set to 250℃-300℃ (the temperatures of the feeding section, compression section, metering section, die head, and die are set sequentially to 250℃→270℃→280℃→290℃→300℃), and the screw speed is 200 rpm; during the extrusion process, the melt is evacuated (vacuum degree -0.08MPa).

[0088] Cooling and pelletizing: The extruded strip melt is cooled in a water bath at a temperature of 25±5℃ and then cut into uniform pellets by a pelletizer.

[0089] Drying: Place the cut granules in a forced-air drying oven and dry at 100°C for 4 hours to obtain the modified FEP composite material B.

[0090] The preparation method of modified FEP composite material C is as follows:

[0091] Premixing: By weight, place 100 parts FEP resin, 2 parts surface-modified nano silica C, 0.5 parts perfluoropolyether processing aid A, and 0.2 parts sodium phenyl phosphate into a Henschel mixer and mix at 1000 rpm for 5 minutes at room temperature to ensure uniform dispersion of each component;

[0092] Melt blending and granulation: The premixed material is fed into a twin-screw extruder for melt blending, extrusion, and granulation; the extruder temperature range is set to 250℃-300℃ (the temperatures of the feeding section, compression section, metering section, die head, and die are set sequentially to 250℃→270℃→280℃→290℃→300℃), and the screw speed is 300 rpm; during the extrusion process, the melt is evacuated (vacuum degree ≥ -0.12MPa).

[0093] Cooling and pelletizing: The extruded strip melt is cooled in a water bath at a temperature of 35±5℃ and then cut into uniform pellets by a pelletizer.

[0094] Drying: Place the cut particles in a forced-air drying oven and dry at 120°C for 2 hours to obtain the modified FEP composite material C.

[0095] In the following examples or comparative examples, the fluoroplastic washing machine material is Chemours' Krytox® PurgeCompound, and the perfluoropolyether lubricant is Solvay's Fomblin® Y-Lube LVAC25 / 6.

[0096] Example 1

[0097] The method for preparing aerospace-grade tin-plated copper core polytetrafluoroethylene propylene insulated wire according to this embodiment includes the following steps in sequence:

[0098] Before extrusion begins, the extruder is cleaned with fluoroplastic cleaning material, and a layer of perfluoropolyether lubricant film is sprayed onto the inner surface of the mold and the surface of the sizing sleeve.

[0099] The modified FEP composite material A was extruded and coated with a tin-plated copper core. Specifically, a two-stage screw extruder equipped with a vacuum exhaust device was used. The screw of the two-stage screw extruder was divided into a melting and plasticizing section and a homogenization and decompression section. A vacuum extraction port was opened at the front end of the homogenization and decompression section to actively remove volatile substances and trapped gases from the melt. The process parameters were controlled as follows: the temperature of the melting and plasticizing section was set at 320℃, the temperature of the homogenization and decompression section was set at 340℃; the screw speed was increased to 45 rpm; the die head pressure was controlled at 20 MPa; and the vacuum degree was maintained at -0.08 MPa.

[0100] After the coated tin-plated copper core wire leaves the mold, it passes through three cooling tanks in sequence. Specifically, the first tank uses warm water at 70±5℃, the second tank uses room temperature water at 30±5℃, and the third tank uses cold water at 20±5℃ for final cooling.

[0101] Example 2

[0102] The method for preparing aerospace-grade tin-plated copper core polytetrafluoroethylene propylene insulated wire according to this embodiment includes the following steps in sequence:

[0103] Before extrusion begins, the extruder is cleaned with fluoroplastic cleaning material, and a layer of perfluoropolyether lubricant film is sprayed onto the inner surface of the mold and the surface of the sizing sleeve.

[0104] The modified FEP composite material A was extruded and coated with a tin-plated copper core. Specifically, a two-stage screw extruder equipped with a vacuum exhaust device was used. The screw of the two-stage screw extruder was divided into a melting and plasticizing section and a homogenization and decompression section. A vacuum extraction port was opened at the front end of the homogenization and decompression section to actively remove volatile substances and trapped gases from the melt. The process parameters were controlled as follows: the temperature of the melting and plasticizing section was set at 300℃, the temperature of the homogenization and decompression section was set at 320℃, the screw speed was increased to 35 rpm, the die head pressure was controlled at 15 MPa, and the vacuum degree was maintained at -0.06 MPa.

[0105] After the coated tin-plated copper core wire leaves the mold, it passes through three cooling tanks in sequence. Specifically, the first tank uses warm water at 65±5℃, the second tank uses room temperature water at 30±5℃, and the third tank uses cold water at 20±5℃ for final cooling.

[0106] Example 3

[0107] The method for preparing aerospace-grade tin-plated copper core polytetrafluoroethylene propylene insulated wire according to this embodiment includes the following steps in sequence:

[0108] Before extrusion begins, the extruder is cleaned with fluoroplastic cleaning material, and a layer of perfluoropolyether lubricant film is sprayed onto the inner surface of the mold and the surface of the sizing sleeve.

[0109] The modified FEP composite material A was extruded and coated with a tin-plated copper core. Specifically, a two-stage screw extruder equipped with a vacuum exhaust device was used. The screw of the two-stage screw extruder was divided into a melting and plasticizing section and a homogenization and decompression section. A vacuum extraction port was opened at the front end of the homogenization and decompression section to actively remove volatile substances and trapped gases from the melt. The process parameters were controlled as follows: the temperature of the melting and plasticizing section was set at 330℃, the temperature of the homogenization and decompression section was set at 350℃, the screw speed was increased to 50 rpm, the die head pressure was controlled at 25 MPa, and the vacuum degree was maintained at -0.09 MPa.

[0110] After the coated tin-plated copper core wire leaves the mold, it passes through three cooling tanks in sequence. Specifically, the first tank uses warm water at 75±5℃, the second tank uses room temperature water at 30±5℃, and the third tank uses cold water at 20±5℃ for final cooling.

[0111] Example 4

[0112] The method for preparing aerospace-grade tin-plated copper core polytetrafluoroethylene propylene insulated wire according to this embodiment includes the following steps in sequence:

[0113] Before extrusion begins, the extruder is cleaned with fluoroplastic cleaning material, and a layer of perfluoropolyether lubricant film is sprayed onto the inner surface of the mold and the surface of the sizing sleeve.

[0114] The modified FEP composite material B was extruded and coated with a tin-plated copper core. Specifically, a two-stage screw extruder equipped with a vacuum exhaust device was used. The screw of the two-stage screw extruder was divided into a melting and plasticizing section and a homogenization and decompression section. A vacuum extraction port was opened at the front end of the homogenization and decompression section to actively remove volatile substances and trapped gases from the melt. The process parameters were controlled as follows: the temperature of the melting and plasticizing section was set at 320℃, the temperature of the homogenization and decompression section was set at 340℃, the screw speed was increased to 38 rpm, the die head pressure was controlled at 21 MPa, and the vacuum degree was maintained at -0.08 MPa.

[0115] After the coated tin-plated copper core wire leaves the mold, it passes through three cooling tanks in sequence. Specifically, the first tank uses warm water at 70±5℃, the second tank uses room temperature water at 30±5℃, and the third tank uses cold water at 20±5℃ for final cooling.

[0116] Example 5

[0117] The method for preparing aerospace-grade tin-plated copper core polytetrafluoroethylene propylene insulated wire according to this embodiment includes the following steps in sequence:

[0118] Before extrusion begins, the extruder is cleaned with fluoroplastic cleaning material, and a layer of perfluoropolyether lubricant film is sprayed onto the inner surface of the mold and the surface of the sizing sleeve.

[0119] The modified FEP composite material C is extruded and coated with a tin-plated copper core. Specifically, a two-stage screw extruder equipped with a vacuum exhaust device is used. The screw of the two-stage screw extruder is divided into a melting and plasticizing section and a homogenization and decompression section. A vacuum extraction port is opened at the front end of the homogenization and decompression section to actively remove volatile substances and trapped gases from the melt. The process parameters are controlled as follows: the temperature of the melting and plasticizing section is set at 310℃, the temperature of the homogenization and decompression section is set at 330℃, the screw speed is increased to 40 rpm, the die head pressure is controlled at 18 MPa, and the vacuum degree is maintained at -0.07 MPa.

[0120] After the coated tin-plated copper core wire leaves the mold, it passes through three cooling tanks in sequence. Specifically, the first tank uses warm water at 65±5℃, the second tank uses room temperature water at 30±5℃, and the third tank uses cold water at 20±5℃ for final cooling.

[0121] Example 6

[0122] The method for preparing aerospace-grade tin-plated copper core polytetrafluoroethylene propylene insulated wire according to this embodiment includes the following steps in sequence:

[0123] Before extrusion begins, the extruder is cleaned with fluoroplastic cleaning material, and a layer of perfluoropolyether lubricant film is sprayed onto the inner surface of the mold and the surface of the sizing sleeve.

[0124] The modified FEP composite material C is extruded and coated with a tin-plated copper core. Specifically, a two-stage screw extruder equipped with a vacuum exhaust device is used. The screw of the two-stage screw extruder is divided into a melting and plasticizing section and a homogenization and decompression section. A vacuum extraction port is opened at the front end of the homogenization and decompression section to actively remove volatile substances and trapped gases from the melt. The process parameters are controlled as follows: the temperature of the melting and plasticizing section is set at 300℃, the temperature of the homogenization and decompression section is set at 330℃, the screw speed is increased to 38 rpm, the die head pressure is controlled at 20 MPa, and the vacuum degree is maintained at -0.09 MPa.

[0125] After the coated tin-plated copper core wire leaves the mold, it passes through three cooling tanks in sequence. Specifically, the first tank uses warm water at 65±5℃, the second tank uses room temperature water at 30±5℃, and the third tank uses cold water at 20±5℃ for final cooling.

[0126] The aerospace-grade tin-plated copper core polytetrafluoroethylene propylene insulated wires prepared in Examples 1-6 were subjected to appearance testing and partial discharge testing (referring to the requirements for partial discharge testing in GJB773A-2000 standard). The test results are shown in Table 1 below:

[0127] Table 1. Detection results of Examples 1-6

[0128]

[0129] Example 1 shows the aerospace-grade tin-plated copper core polytetrafluoroethylene propylene insulated wire prepared as follows: Figure 1 As shown.

[0130] Example 4 shows the aerospace-grade tin-plated copper core polytetrafluoroethylene propylene insulated wire prepared as follows: Figure 2 As shown.

[0131] Example 6 shows the aerospace-grade tin-plated copper core polytetrafluoroethylene propylene insulated wire prepared as follows: Figure 3 As shown.

[0132] In the research and development process of this invention, based on Example 1, the following comparative experiments were also conducted.

[0133] Comparative Example 1

[0134] The difference between the preparation method of this comparative example wire and that of Example 1 is that the modified FEP composite material A in Example 1 is replaced with perfluoroethylene propylene (FEP), while the other preparation steps are the same as in Example 1.

[0135] Comparative Example 2

[0136] The difference between the preparation method of this comparative wire and that of Example 1 is that the vacuuming operation is omitted in the homogenization and decompression stage, while the other preparation steps are the same as those in Example 1.

[0137] Comparative Example 3

[0138] The difference between the preparation method of this comparative wire and that of Example 1 is that the first stage of cooling with warm water at 70±5℃ is omitted in the cooling step, while the other preparation steps are the same as those in Example 1.

[0139] Comparative Example 4

[0140] The preparation method of this comparative example wire differs from that of Example 1 in that the modified FEP composite material A (raw material composition of 100 parts FEP resin, 1.5 parts surface modified nano silica A, 0.3 parts perfluoropolyether processing aid A, and 0.1 parts sodium phenyl phosphate) in Example 1 is replaced with the modified FEP composite material of this comparative example, while the other preparation steps are the same as in Example 1.

[0141] The preparation method of the modified FEP composite material in this comparative example differs from that of modified FEP composite material A in that the surface-modified nano-silica A in the raw material components of modified FEP composite material A is replaced with nano-silica (i.e., the nano-silica is not modified), while the other preparation steps are the same as those of modified FEP composite material A.

[0142] Comparative Example 5

[0143] The preparation method of this comparative example wire differs from that of Example 1 in that the modified FEP composite material A (raw material composition of 100 parts FEP resin, 1.5 parts surface modified nano silica A, 0.3 parts perfluoropolyether processing aid A, and 0.1 parts sodium phenyl phosphate) in Example 1 is replaced with the modified FEP composite material of this comparative example, while the other preparation steps are the same as in Example 1.

[0144] The preparation method of the modified FEP composite material in this comparative example differs from that of modified FEP composite material A in that the raw material components of the modified FEP composite material in this comparative example do not include perfluoropolyether processing aids, while the other preparation steps are the same as those of modified FEP composite material A.

[0145] Comparative Example 6

[0146] The preparation method of this comparative example wire differs from that of Example 1 in that the modified FEP composite material A (raw material composition of 100 parts FEP resin, 1.5 parts surface modified nano silica A, 0.3 parts perfluoropolyether processing aid A, and 0.1 parts sodium phenyl phosphate) in Example 1 is replaced with the modified FEP composite material of this comparative example, while the other preparation steps are the same as in Example 1.

[0147] The preparation method of the modified FEP composite material in this comparative example differs from that of modified FEP composite material A in that the raw material components of the modified FEP composite material in this comparative example do not include sodium phenyl phosphate, while the other preparation steps are the same as those of modified FEP composite material A.

[0148] The wires prepared in Comparative Examples 1-6 were subjected to appearance inspection and partial discharge quantity testing (referring to the requirements for partial discharge quantity testing in GJB773A-2000 standard). The test results are shown in Table 2 below:

[0149] Table 2. Test results of Comparative Examples 1-6

[0150]

[0151] The wire prepared in Comparative Example 1 is as follows Figure 4 As shown, there is a local area where the insulation layer is not covered (referred to as glue leakage).

[0152] The wire prepared in Comparative Example 2 is as follows Figure 5 As shown, a large number of bubbles appear in the insulation layer.

[0153] The wire prepared in Comparative Example 3 is as follows Figure 6 As shown, an air gap is created in the insulating layer.

[0154] The wire prepared in Comparative Example 4 (with the tin-plated copper core stripped) is as follows: Figure 7 As shown, the surface of the insulating layer is rough.

[0155] The wire prepared in Comparative Example 5 is as follows Figure 8 As shown, a large number of bubbles appear in the insulation layer.

[0156] The wire prepared in Comparative Example 6 is as follows Figure 9 As shown, the insulation layer exhibits defects due to poor plasticization.

[0157] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for producing a tinned copper core polytetrafluoroethylene ethylene insulated wire for aerospace, characterized by, The method comprises the following steps: S1: preparing a modified FEP composite material; S2: pretreating an extruder; S3: using a double-stage decompression extrusion process to extrude and coat the tinned copper core with the modified FEP composite material prepared in step S1; S4: cooling the coated tinned copper core wire using a step cooling method with partitioned temperature control; In step S1, the modified FEP composite material is composed of the following components by weight: 100 parts of FEP resin, 0.5-2 parts of surface-modified nano-silicon dioxide, 0.1-0.5 parts of perfluoropolyether processing aid, 0.05-0.2 parts of sodium phenylphosphonate, and 0-2.5 parts of inorganic pigment; the surface-modified nano-silicon dioxide is prepared by surface modification treatment of nano-SiO2 with a silane coupling agent. In step S3, the double-stage decompression extrusion process is as follows: a double-stage screw extruder equipped with a vacuum exhaust device is used, the screw of the double-stage screw extruder is divided into a melting plasticizing section and a homogenizing decompression section, a vacuum exhaust port is opened at the front end of the homogenizing decompression section, and volatile substances and wrapped gas in the melt are actively removed by vacuum pumping; the process parameters are controlled as follows: the temperature of the melting plasticizing section is set to 300-330℃, the temperature of the homogenizing decompression section is set to 320-350℃, the screw rotation speed is raised to 35-50 rpm, the head pressure is controlled to 15-25 MPa, and the vacuum degree is maintained at -0.06 to -0.09 MPa.

2. The production method according to claim 1, characterized by, The surface-modified nano-silicon dioxide is prepared by surface modification treatment of nano-SiO2 with a silane coupling agent, and the steps are as follows: 1) nano-SiO2 is dispersed in a mixed solvent of anhydrous ethanol and deionized water to prepare a nano-SiO2 suspension with a solid content of 10-15 wt%; 2) the silane coupling agent is added dropwise to an acidic ethanol-water solution with a pH of 4-5 to hydrolyze and generate silanol, obtaining a silane coupling agent hydrolysate; 3) the silane coupling agent hydrolysate is slowly added dropwise to the nano-SiO2 suspension prepared in step 1) under stirring, and the temperature of the reaction system is controlled at 60±2℃; 4) after the addition is completed, the temperature and stirring speed are maintained, and the reaction is continued for 4-5 hours; 5) after the reaction is completed, filtration, anhydrous ethanol washing, and then drying and grinding are performed to obtain the surface-modified nano-silicon dioxide.

3. The preparation method according to claim 2, characterized in that, The particle size of the nano-SiO2 is 20-30 nm; the silane coupling agent is selected from γ-aminopropyl triethoxysilane or γ-(methacryloyloxy)propyl trimethoxysilane; and the amount of the silane coupling agent is 2.0-4.0% of the mass of the nano-SiO2.

4. The method of claim 1, wherein, The inorganic pigment is selected from one of rutile titanium dioxide, high-purity carbon black, cobalt blue, chromium oxide green, iron oxide red, or molybdenum chromium red, and cadmium sulfide.

5. The method of any one of claims 1-4, wherein, The modified FEP composite material is prepared by melt blending and extrusion granulation.

6. The preparation method according to claim 5, characterized in that, The modified FEP composite material is prepared by melt blending and extrusion granulation, specifically as follows: Premixing: according to the weight ratio of raw material components of the modified FEP composite, FEP resin, surface modified nano-silica, perfluoropolyether processing aid, sodium phenylphosphate and inorganic pigment are mixed at room temperature for 5-10 minutes at a speed of 500-1000 rpm to uniformly disperse; Melt blending and granulation: the above pre-mixed material is sent into a double screw extruder for melt blending and extrusion granulation; the temperature interval of the double screw extruder is set to 250-300 DEG C, and the screw rotation speed is 200-300 rpm; the melt is vacuumed and exhausted during the extrusion process; Cooling and granulation: the extruded melt is cooled by a water tank with water temperature of 20-40 DEG C, and then cut into uniform particles; Drying: the cut particles are dried at 100-120 DEG C for 2-4 hours to obtain the modified FEP composite.

7. The preparation method according to claim 1, characterized in that, In the step S2, the pretreatment is specifically as follows: before the extrusion starts, the extruder is cleaned by using fluoroplastic washing material, and a stable thin film of perfluoropolyether lubricant is sprayed on the inner surface of the mold and the surface of the shaping sleeve.

8. The method of claim 1, wherein, In the step S4, the step cooling mode of the partition temperature control is specifically as follows: after the coated tinned copper core wire leaves the mold, it sequentially passes through three cooling tanks, and the specific process is as follows: the first tank is cooled by warm water with a temperature of 60-80 DEG C, the second tank is cooled by normal temperature water with a temperature of 25-35 DEG C, and the third tank is finally cooled by cold water with a temperature of 15-25 DEG C.

9. A tinned copper core polyfluoroethylene propylene insulated wire for aerospace, characterized by, The preparation method is prepared by using the preparation method of any one of claims 1-8.

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