High-performance aramid composite conductive fiber and preparation method and preparation system thereof

Abstract

The application discloses a kind of high-performance aramid composite conductive fiber and its preparation method and preparation system, comprising the following steps: S1, preparation PU melt-blowing preform rod;S2, preparation liquid metal mixed solution;S3, preparation PU melt-blowing intermediate layer while liquid metal mixed solution is perfused to PU melt-blowing intermediate layer;S4, PU melt-blowing intermediate layer and aramid core yarn are carried out heat bonding and obtained aramid composite conductive fiber.The beneficial effects of the application are: excellent conductivity and ductility are improved at the same time Fireproof heat insulation performance of conductive fiber, can be applicable to the needs of different functions in various places.

Description

Technical Field

[0001] This invention relates to the field of composite conductive fiber preparation technology, specifically to a high-performance aramid composite conductive fiber and its preparation method and system. Background Technology

[0002] With the rapid development of smart flexible wearable textiles and the smart home industry, conductive fibers with higher flexibility and safety have gradually become a hot research direction in the field of flexible conductive materials. Researchers have begun to explore composite conductive materials with higher safety factor, better performance, and excellent conductivity, which can achieve lightweight production.

[0003] In existing technologies, conductive fiber preparation methods often use solution spinning to obtain single fiber filaments as the substrate or MXene-based as the functional composite conductive core layer. Conductive coatings are then used for coating and finishing. After surface modification, chemical groups are grafted or conductive dispersions are added by etching the surface of the filaments. However, the conductivity obtained in this way is often not good enough or durable. Moreover, the conductive layer is on the outer layer of the fiber, and its surface is easily damaged, which can cause safety hazards and affect its conductivity and safety.

[0004] For example, patent CNCN116815494A proposes a method for preparing aramid conductive fibers. This method utilizes ultrasonic swelling to align aramid fibers, creating microcracks on their surface. Finally, a conductive filler dispersion is filled into the aramid surface and the microcracks. The mechanical properties of the aramid composite conductive fibers obtained by this method mainly rely on the properties of the aramid fibers themselves, failing to leverage the structural advantages of composite materials. Furthermore, the uniformity of the conductive filler dispersion significantly affects the conductivity of the composite conductive fibers, leading to unstable electrical properties. Patent CN113235184B proposes a core-sheath structure aramid composite conductive fiber. This method uses wet solution spinning to prepare aramid nanofibers as the sheath and aramid nanofibers and MXene-based composite conductive fibers as the core. Finally, a coagulation bath is used to solidify the sheath and core layers. The aramid composite conductive fibers prepared by this method are nanofibers with good conductivity, but the excessively fine fiber diameter is unfavorable for most practical applications, resulting in a lower load current capacity and making lightweight production difficult. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this application proposes a high-performance aramid composite conductive fiber and its preparation method and system, which possesses excellent conductivity and ductility while improving the fireproof and heat insulation properties of the conductive fiber.

[0006] The following is the technical solution of the present invention: a method for preparing high-performance aramid composite conductive fiber, comprising the following steps:

[0007] S1. Prepare PU meltblown preforms;

[0008] S2. Prepare a liquid metal mixed solution;

[0009] S3. Simultaneously, while preparing the PU meltblown interlayer, inject the liquid metal mixture solution into the PU meltblown interlayer;

[0010] S4. The PU meltblown interlayer and aramid core-spun yarn are thermally bonded to obtain aramid composite conductive fiber.

[0011] As a preferred option, the specific steps of S1 are as follows:

[0012] Polyurethane chips are processed into PU meltblown fabric using a meltblown process. The PU meltblown fabric is then wound onto a stainless steel tube in a layered structure. The PU meltblown fabric on the stainless steel tube is heated using a ring-shaped ultrasonic heating device to soften and bond it. The steel tube is then removed to obtain a PU meltblown preform.

[0013] The polyurethane chips have a melt index of 280 g / (10 min), a melt temperature of 210℃, a spinning speed of 200 m / min, a wind speed of 200 m / min, and a receiving distance of 20 cm; the PU meltblown fabric has a surface density of 1.2-1.3 g / cm3 and a thickness of 0.2-0.3 mm; the stainless steel tube has an outer diameter of 12 mm; the PU meltblown fabric has 5-6 winding layers; and the annular ultrasonic heating device has a heating temperature of 180-200℃.

[0014] As a preferred option, the specific steps of S2 are as follows:

[0015] GaN liquid metal was immersed in hydrochloric acid solution, allowed to stand, washed with anhydrous ethanol, magnesium nanoparticles were added, and stirred evenly with a magnetic stirrer to obtain a liquid metal mixed solution with magnesium nanoparticles uniformly mixed.

[0016] The concentration of hydrochloric acid solution is 5%-20%, the concentration of anhydrous ethanol is 99.9%, the mass ratio of gallium indium tin liquid metal to magnesium nanoparticles ranges from 1:1 to 10:1, the diameter of magnesium nanoparticles is 5-10 nm, and the rotation speed of the magnetic stirrer is 600-800 r / min.

[0017] As a preferred option, the specific steps of S3 are as follows:

[0018] The bottom ends of the PU meltblown preforms are bonded together in an annular ultrasonic heating device. The principle of thermal stretching is used to shrink and refine the PU meltblown preforms until they are stretched into fibrous PU meltblown intermediate layers.

[0019] The drawing speed is 2cm / s, the diameter of the PU meltblown intermediate layer is 1.5-2.0mm, the upper temperature zone is 190-210℃, the middle temperature zone is 150-170℃, and the lower temperature zone is 110-130℃.

[0020] While the PU meltblown intermediate layer is being hot-stretched, a liquid metal mixture solution is injected into the PU meltblown intermediate layer of the PU meltblown preform through the top opening of the PU meltblown preform using an injection pump.

[0021] The hot stretching temperature range is 100-190℃, the diameter of the PU meltblown interlayer is 0.3-0.4mm, the injection pump flow rate is 226.2ml / h, and the injection pump needle diameter is 1.5mm.

[0022] As a preferred option, the specific steps of S4 are as follows:

[0023] Aramid filaments and aramid rovings are twisted with PU meltblown interlayer in the form of Sirofil spinning, and the residual heat during the hot stretching process is used to thermally bond the surface of the PU meltblown interlayer with the aramid core-spun yarn in a softened state to obtain aramid composite conductive fiber.

[0024] The diameter of the aramid filament is 0.02-0.03 mm, the twisting speed of the aramid core-spun yarn is 80-100 TPM, and the surface temperature of the PU meltblown interlayer is 140-150℃.

[0025] A high-performance aramid composite conductive fiber includes: a mixed solution conductive core layer, a PU meltblown intermediate layer connected to the mixed solution conductive core layer, and an aramid core-spun yarn skin layer formed by hot twisting the PU meltblown intermediate layer with aramid filaments and aramid rovings using a Sirosier spinning process.

[0026] A high-performance aramid composite conductive fiber preparation system, comprising:

[0027] Meltblown fabric winding device, used to wind PU meltblown fabric onto a stainless steel tube;

[0028] A ring-shaped ultrasonic heating device is used to uniformly spot bond PU meltblown fabric wound on a stainless steel tube to obtain PU meltblown preforms, and is connected to a meltblown fabric winding device.

[0029] The hot stretching device is used to hot stretch the produced PU meltblown preforms and is connected to an annular ultrasonic heating device.

[0030] A mixed solution injection device is used to inject a liquid metal mixed solution into the PU meltblown intermediate layer of the PU meltblown preform, and is connected to the wire drawing tower hot stretching device;

[0031] The serofil spinning apparatus is used to prepare aramid core-spun yarn and is connected to the drawing tower and hot stretching device.

[0032] Preferably, the thermal stretching device for the wire drawing tower includes:

[0033] The spatial position control module is used to control the position of the suspended PU meltblown preform.

[0034] Laser diameter measuring and planar position measuring instrument is used to limit the diameter of PU meltblown preforms during hot stretching.

[0035] The pressure adjustment module is used to limit the pressure applied to the PU meltblown preform during hot stretching;

[0036] Fiber position limiting module, used to limit the position of PU meltblown preform during hot stretching;

[0037] The fiber drawing module is used to wind and collect the fibers obtained after the PU meltblown preform is compressed and refined.

[0038] An inert gas delivery module is used to participate in controlling the thermal stretching conditions in three temperature zones;

[0039] The heating furnace temperature control module is used to control the thermal stretching conditions in the three temperature zones.

[0040] High-temperature heating module, used to heat PU meltblown preforms;

[0041] Preform suspension module for suspending PU meltblown preforms;

[0042] The concentricity control module is used to fine-tune the center of the produced fibers.

[0043] Preferably, the Sirofil spinning apparatus includes:

[0044] Filament winding module, used for feeding in winding filaments;

[0045] Roving module for feeding in roving;

[0046] Tension plate is used to adjust the tension of filaments to ensure that the filaments are evenly distributed;

[0047] Guide rollers are used to pull filaments and rovings, and to connect filaments and rovings;

[0048] The front roller is used to twist filaments and rovings to form aramid core-spun yarn.

[0049] Core-spun yarn winding module, used for sorting and recycling aramid core-spun yarn.

[0050] The beneficial effects of this invention are:

[0051] 1. The high-performance aramid composite conductive yarn provided by this invention has a PU intermediate layer with uniform interlayer gaps, which has excellent adhesion and excellent structural mechanical properties. It has excellent composite effect with the liquid conductive metal core layer and the aramid core-spun yarn skin layer. The aramid composite conductive fiber has both flexibility and mechanical properties, as well as excellent conductivity and fireproof and heat insulation properties. This greatly improves the practicality and safety of the conductive material. Moreover, no chemical reagents are needed for bonding in the production process of this composite material. At the same time, the conductive core material is a gallium indium tin liquid alloy, which is non-toxic, harmless and environmentally friendly.

[0052] 2. The electrical conductivity of this aramid composite conductive fiber is 5600 S / m. According to the GB / T 5455-2014 standard, the fire rating is V-0, which means that the sample will self-extinguish under the test flame and the burning time is very short. The tensile breaking strength is 890 MPa, which shows excellent mechanical properties. The elongation at break is 7%, which effectively enhances the ductility of the aramid composite fiber. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the structure of the high-performance aramid composite conductive fiber of the present invention;

[0054] Figure 2 This is a flowchart of the method for preparing high-performance aramid composite conductive fibers according to the present invention;

[0055] Figure 3 This is a diagram of a PU meltblown fabric winding process for the preparation method of high-performance aramid composite conductive fibers according to the present invention.

[0056] Figure 4 This is a schematic diagram of the high-performance aramid composite conductive fiber preparation system of the present invention. Figure 1 ;

[0057] Figure 5 This is a schematic diagram of the high-performance aramid composite conductive fiber preparation system of the present invention. Figure 2 ;

[0058] Figure 6 This is a schematic diagram of the annular ultrasonic heating device in the high-performance aramid composite conductive fiber preparation system of the present invention.

[0059] Figure 7 This is a schematic diagram of the thermal stretching device of the drawing tower in the high-performance aramid composite conductive fiber preparation system of the present invention.

[0060] Figure 8 This is a schematic diagram of the Sirofil spinning apparatus of the high-performance aramid composite conductive fiber preparation system of the present invention.

[0061] In the diagram: 1. Annular ultrasonic heating device; 2. Hot stretching device for drawing tower; 3. Sirofil spinning device; 4. Meltblown fabric winding device; 5. Mixed solution injection device; 6. Conductive core layer of mixed solution; 7. PU meltblown intermediate layer; 8. Aramid core-spun yarn outer layer; 201. Spatial position control module; 202. Laser diameter measuring and planar position measuring instrument; 203. Pressure adjustment module; 204. Fiber position limiting module; 205. Drawing module; 206. Inert gas conveying module; 207. Heating furnace temperature control module; 208. Hot-drawn yarn; 209. High-temperature heating module; 210. Preform suspension module; 211. Concentricity control module; 301. Filament winding module; 302. Roving winding module; 303. Tension plate; 304. Front roller; 305. Guide roller; 306. Core-spun yarn winding module. Detailed Implementation

[0062] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. 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.

[0063] Example 1:

[0064] like Figure 1 As shown, a high-performance aramid composite conductive fiber includes: a mixed solution conductive core layer 6, a PU meltblown intermediate layer 7, and an aramid core-spun yarn outer layer 8.

[0065] Among them, the mixed solution conductive core layer 6 is a liquid metal conductive solution obtained by uniformly mixing gallium indium tin liquid metal solution after surface deoxidation treatment with magnesium nanoparticles;

[0066] PU meltblown intermediate layer 7 is an intermediate layer with interlayer gap bonding. The PU meltblown cloth is uniformly bonded at points and then thermally stretched to obtain the PU meltblown intermediate layer 7.

[0067] The aramid core-spun yarn skin layer 8 is formed by bonding aramid filaments and aramid rovings with the PU meltblown intermediate layer 7 using the Sirofil spinning process.

[0068] The conductive core layer 6 of the aramid composite conductive fiber is a mixed solution of gallium indium tin liquid metal. The outer layer of the conductive core layer 6 is a PU meltblown intermediate layer 7. The aramid filament and aramid roving are twisted with the PU meltblown intermediate layer 7 using the Sirofil spinning process, and then thermally bonded to form the aramid core-spun yarn skin layer 8.

[0069] The PU meltblown intermediate layer 7 is produced by meltblowing, layered winding and gap bonding, and has good ductility and mechanical properties. It is then stretched and compressed at a low temperature. While retaining the interlayer gap at low temperature, the treated and mixed gallium indium tin liquid alloy metal is injected, which can effectively increase the effective contact area between the liquid alloy and the intermediate layer, enhance the conductivity and stability of the mixed solution conductive core layer 6, and utilize the residual heat during hot stretching to uniformly and densely composite the aramid yarn with the PU meltblown intermediate layer 7 in the form of Sirofil spinning and thermal bonding.

[0070] Example 2:

[0071] like Figure 2 As shown, a method for preparing a high-performance aramid composite conductive fiber includes the following steps:

[0072] S1. Prepare PU meltblown preforms;

[0073] S2. Prepare a liquid metal mixed solution;

[0074] S3. While preparing the PU meltblown intermediate layer 7, the liquid metal mixture solution is injected into the PU meltblown intermediate layer 7;

[0075] S4. The PU meltblown intermediate layer 7 and the aramid core-spun yarn are thermally bonded to obtain aramid composite conductive fiber.

[0076] In step S1, a PU meltblown preform is prepared. For example... Figure 3 As shown, PU nonwoven fabric (i.e., PU meltblown fabric) produced by meltblowing is wound into a layered structure on a stainless steel tube. Then, a ring-shaped ultrasonic heating device 1 is used to heat the PU meltblown fabric on the steel tube, softening and bonding it together. The steel tube is then removed, yielding a PU meltblown preform. Controlling the softening temperature allows the layered PU meltblown fabric to partially bond, forming interlayer gaps between different meltblown layers. This improves the flexibility and mechanical properties of the final composite conductive fiber.

[0077] Specifically, polyurethane chips are manufactured into PU nonwoven fabric rolls using a meltblown process. The PU nonwoven fabric manufactured by the meltblown process is wound onto a stainless steel tube with a diameter of 12mm, with 5-6 layers. Then, a ring-shaped ultrasonic heating device 1 is used to uniformly spot bond the layered PU meltblown fabric to obtain a PU meltblown preform.

[0078] The meltblown process parameters for the PU meltblown fabric are as follows: the melt index (MFI) of the polyurethane chips used is 280 g / (10 min); the melt temperature is 210℃; the spinning speed is 200 m / s; the hot stretching airflow velocity is 200 m / s; and the receiving distance is 20 cm. The areal density of the resulting PU meltblown fabric is 1.26 g / cm³. 3 The thickness is 0.2mm.

[0079] In step S2, a liquid metal mixed solution is prepared. Gallium indium tin liquid metal is poured into a hydrochloric acid solution, covering the gallium indium alloy. After standing, a liquid metal solution is obtained. This solution is then washed with anhydrous ethanol, and finally, magnesium nanoparticles are added. The mixture is stirred evenly using a magnetic stirrer to obtain a gallium indium liquid metal mixed solution with uniformly mixed magnesium nanoparticles.

[0080] Specifically, gallium indium tin liquid metal was poured into a hydrochloric acid solution with an equivalent concentration of 0.01 mol / L until the hydrochloric acid solution completely submerged the liquid metal solution. After standing for 4 hours, a liquid metal solution without surface treatment was obtained. Subsequently, it was washed with 99% anhydrous ethanol and dried. Finally, magnesium nanoparticles with an average diameter of 7 nm were added. The mass ratio of liquid metal to magnesium nanoparticles was 4:1. The liquid metal solution containing magnesium nanoparticles was stirred evenly using a magnetic stirrer with a rotation speed of 800 r / min to obtain a gallium indium liquid metal mixed solution with uniformly mixed magnesium nanoparticles (i.e., the conductive core layer 6 of the mixed solution).

[0081] Liquid gallium indium tin (CITi) metal is poured into a beaker. An acidic solution is used to remove the oxide layer from the liquid gallium indium metal while reducing the surface tension of the liquid metal. Magnesium nanoparticles are then doped into the treated liquid gallium indium metal to increase wettability while maintaining high conductivity and ductility.

[0082] In step S3, while preparing the PU meltblown intermediate layer 7, a liquid metal mixture solution is injected into the PU meltblown intermediate layer 7. Specifically, to prepare the PU meltblown intermediate layer 7, the PU meltblown preform is hung in the thermal stretching device 2 of the drawing tower, and its bottom ends are bonded together. Using the principle of thermal stretching, the PU meltblown preform is compressed and refined until it is stretched into a fibrous PU meltblown intermediate layer 7.

[0083] The temperatures of the three zones in the hot stretching device 2 of the wire drawing tower are: 190℃ for the upper zone, 150℃ for the middle zone, and 110℃ for the lower zone; the wire drawing speed of the preform is 2cm / s, and the diameter of the hollow fiber PU meltblown intermediate layer 7 is 2.0mm.

[0084] While preparing the PU meltblown intermediate layer 7, a liquid metal mixture solution is injected into the PU meltblown intermediate layer 7. Specifically, while the PU meltblown intermediate layer 7 is being thermally stretched, the prepared liquid metal mixture solution is injected into the PU meltblown intermediate layer 7 of the PU meltblown preform through the top opening of the PU meltblown preform using an injection pump. This allows the injection of the conductive core layer 6 of the mixture solution and the compaction and refinement of the PU meltblown intermediate layer 7 to occur simultaneously, further enhancing the effective contact and stability between the conductive core layer 6 of the mixture solution and the PU meltblown intermediate layer 7.

[0085] The flow rate of the injection pump for injecting the liquid metal mixed solution is 226.2 ml / h, the diameter of the injection pump needle is 1.5 mm, and the average diameter of the stretched and refined PU hollow fiber is 2 mm inner diameter and 2.7 mm outer diameter.

[0086] When the PU meltblown preform is stretched and refined in the hot stretching device 2 of the drawing tower, it is necessary to monitor and control its temperature change in the three temperature zones of 100-190℃ to ensure that the interlayer gap of the PU meltblown fabric can be preserved relatively completely. At the same time, the PU meltblown preform is compressed and refined. At this time, the PU meltblown preform is in a viscoelastic state, with its top end being the stretched and refined PU meltblown intermediate layer 7, and its bottom end becoming a solid segment of PU fiber due to bonding together. At this time, the prepared gallium-indium liquid metal mixed solution is injected into the PU meltblown intermediate layer 7 using the injection pump needle, realizing the simultaneous injection of the mixed solution conductive core layer 6 and the compression and refinement of the PU meltblown intermediate layer 7.

[0087] In step S4, the PU meltblown interlayer 7 and the aramid core-spun yarn are thermally bonded to obtain aramid composite conductive fiber. Specifically, Sirofil spinning is performed using the Sirofil spinning device 3. The aramid filament and aramid roving are twisted with the PU meltblown interlayer 7 in the form of Sirofil spinning. The residual heat from the hot stretching process is used to thermally bond the surface of the PU meltblown interlayer 7 to the aramid core-spun yarn in a softened state to obtain aramid composite conductive fiber.

[0088] The aramid filament has a diameter of 0.02 mm, the twisting speed of the aramid core-spun yarn is 80 TPM, and the surface temperature of the PU meltblown intermediate layer 7 is 100℃ during thermal bonding.

[0089] Example 3:

[0090] Unlike Example 2, this example changes the number of winding layers of the preform, changing the number of winding layers in Example 2 from 5-6 layers to 8-9 layers in this example.

[0091] A method for preparing high-performance aramid composite conductive fiber includes the following steps:

[0092] S11. Prepare PU meltblown preforms;

[0093] PU nonwoven fabric manufactured by meltblown process is wound onto a stainless steel tube with a diameter of 12mm, with 8-9 layers. Then, a ring-shaped ultrasonic heating device 1 is used to uniformly spot bond the layered PU meltblown fabric to obtain a PU meltblown preform.

[0094] The meltblown process parameters for the PU meltblown fabric are as follows: the melt index (MFI) of the polyurethane chips used is 280 g / (10 min); the melt temperature is 190℃; and the receiving distance is 20 cm. The resulting PU meltblown fabric has an areal density of 1.2-1.3 g / cm3 and a thickness of 0.2-0.3 mm.

[0095] S12. Prepare a liquid metal mixed solution;

[0096] GaInTl liquid metal was poured into a 0.01 mol / L hydrochloric acid solution until the hydrochloric acid solution completely submerged the liquid metal solution. After standing for 4 hours, a surface-treated liquid metal solution was obtained. The solution was then washed with 99% anhydrous ethanol and dried. Finally, magnesium nanoparticles with a diameter of 7 nm were added, with a mass ratio of liquid metal to magnesium nanoparticles of 4:1. The liquid metal solution containing magnesium nanoparticles was stirred evenly using a magnetic stirrer at a speed of 800 r / min to obtain a GaInTl liquid metal mixed solution with uniformly mixed magnesium nanoparticles.

[0097] S13. While preparing the PU meltblown intermediate layer 7, the liquid metal mixture solution is injected into the PU meltblown intermediate layer 7;

[0098] Preparation of PU meltblown intermediate layer 7: The PU meltblown preform is hung in the thermal stretching device 2 of the drawing tower and its bottom ends are bonded together. Using the principle of thermal stretching, the PU meltblown preform is compressed and refined until it is stretched into a fibrous PU meltblown intermediate layer 7.

[0099] The temperatures of the three zones of the hot stretching device 2 are as follows: the upper zone temperature is 190℃, the middle zone temperature is 150℃, and the lower zone temperature is 110℃; the drawing speed of the preform is 2cm / s, and the diameter of the hollow fiber PU meltblown intermediate layer 7 is 1.8mm.

[0100] Simultaneously, the liquid metal mixture solution is injected into the PU meltblown intermediate layer 7: while the PU meltblown intermediate layer 7 is being thermally stretched, the prepared liquid metal mixture solution is injected into the PU meltblown intermediate layer 7 of the PU meltblown preform through the top opening of the PU meltblown preform using an injection pump. This allows the injection of the conductive core layer 6 of the mixture solution and the compaction and refinement of the PU meltblown intermediate layer 7 to occur simultaneously, further enhancing the effective contact and stability between the conductive core layer 6 of the mixture solution and the PU meltblown intermediate layer 7.

[0101] The flow rate of the injection pump for injecting liquid metal is 226.2 ml / h, the diameter of the injection pump needle is 1.5 mm, and the diameter range of the stretched and refined PU hollow fiber is: inner diameter 1.8 mm and outer diameter 2.9 mm.

[0102] S4. Thermally bond the PU meltblown intermediate layer 7 and the aramid core-spun yarn to obtain aramid composite conductive fiber.

[0103] Aramid filaments and aramid rovings are twisted together with PU meltblown interlayer 7 in the form of Sirofil spinning, and the residual heat during the hot stretching process is used to thermally bond the surface of PU meltblown interlayer 7 to the aramid core-spun yarn in a softened state to obtain aramid composite conductive fiber.

[0104] The aramid filament has a diameter of 0.02 mm, the twisting speed of the aramid core-spun yarn is 80 TPM, and the surface temperature of the PU meltblown intermediate layer 7 is 100℃ during thermal bonding.

[0105] Example 4:

[0106] Unlike Example 2, this example changes the three temperature zones of the thermal stretching device 2 in the wire drawing tower. The upper temperature zone temperature is changed from 190°C to 210°C, the middle temperature zone temperature is changed from 150°C to 170°C, and the lower temperature zone temperature is changed from 110°C to 130°C.

[0107] A method for preparing high-performance aramid composite conductive fiber includes the following steps:

[0108] S21. Prepare PU meltblown preforms;

[0109] The PU nonwoven fabric manufactured by meltblown process is wound onto a stainless steel tube with a diameter of 12mm, with 5-6 layers. Then, the layered PU meltblown fabric is uniformly spot-bonded using a ring-shaped ultrasonic heating device 1 to obtain a PU meltblown preform.

[0110] The meltblown process parameters for the PU meltblown fabric are as follows: the melt index (MFI) of the polyurethane chips used is 280 g / (10 min); the melt temperature is 210℃; the spinning speed is 200 m / s; the hot stretching airflow velocity is 200 m / s; and the receiving distance is 20 cm. The resulting PU meltblown fabric has an areal density of 1.26 g / cm³ and a thickness of 0.2 mm.

[0111] S22. Preparation of liquid metal mixed solution;

[0112] GaInT liquid metal was poured into a 0.01 mol / L hydrochloric acid solution until the hydrochloric acid solution completely submerged the liquid metal solution. After standing for 4 hours, a surface-treated liquid metal solution was obtained. The solution was then washed with 99% anhydrous ethanol and dried. Finally, magnesium nanoparticles with an average diameter of 7 nm were added, with a mass ratio of liquid metal to magnesium nanoparticles of 4:1. The liquid metal solution containing magnesium nanoparticles was stirred evenly using a magnetic stirrer at a speed of 800 r / min to obtain a GaIn liquid metal mixed solution with magnesium nanoparticles.

[0113] S23. While preparing the PU meltblown intermediate layer 7, a liquid metal mixture solution is injected into the PU meltblown intermediate layer 7;

[0114] Preparation of PU meltblown intermediate layer 7: The PU meltblown preform is hung in the thermal stretching device 2 of the drawing tower and its bottom ends are bonded together. Using the principle of thermal stretching, the PU meltblown preform is compressed and refined until it is stretched into a fibrous PU meltblown intermediate layer 7.

[0115] The temperatures of the three zones of the hot stretching device 2 are as follows: the upper zone temperature is 210℃, the middle zone temperature is 170℃, and the lower zone temperature is 130℃; the drawing speed of the preform is 2cm / s, and the diameter of the hollow fiber PU meltblown intermediate layer 7 is 1.5mm.

[0116] Simultaneously, the liquid metal mixture solution is injected into the PU meltblown intermediate layer 7: while the PU meltblown intermediate layer 7 is being thermally stretched, the liquid metal mixture solution is injected into the PU meltblown intermediate layer 7 of the PU meltblown preform through the top opening of the PU meltblown preform using an injection pump. This allows the injection of the mixed solution conductive core layer 6 and the compaction and refinement of the PU meltblown intermediate layer 7 to occur simultaneously, further enhancing the effective contact and stability between the mixed solution conductive core layer 6 and the PU meltblown intermediate layer 7.

[0117] The flow rate of the injection pump for injecting liquid metal is 226.2 ml / h, the diameter of the injection pump needle is 1.5 mm, and the average diameter of the stretched and refined PU hollow fiber is 2 mm inner diameter and 2.7 mm outer diameter.

[0118] S24. The PU meltblown intermediate layer 7 and the aramid core-spun yarn are thermally bonded to obtain aramid composite conductive fiber.

[0119] Aramid filaments and aramid rovings are twisted together with PU meltblown interlayer 7 in the form of Sirofil spinning, and the residual heat during the hot stretching process is used to thermally bond the surface of PU meltblown interlayer 7 to the aramid core-spun yarn in a softened state to obtain aramid composite conductive fiber.

[0120] The aramid filament has a diameter of 0.02 mm, the twisting speed of the aramid core-spun yarn is 80 TPM, and the surface temperature of the PU meltblown intermediate layer 7 is 100℃ during thermal bonding.

[0121] Example 5:

[0122] like Figure 4 and Figure 5 As shown, a system for preparing high-performance aramid composite conductive fibers includes:

[0123] Meltblown fabric winding device 4 is used to wind PU meltblown fabric on a stainless steel tube and is connected to an annular ultrasonic heating device 1.

[0124] The annular ultrasonic heating device 1 is used to uniformly spot bond the multi-layer PU meltblown cloth wound on a stainless steel tube to obtain a PU meltblown preform with uniform interlayer gap, and connects the meltblown cloth winding device 4 and the wire drawing tower hot stretching device 2.

[0125] The hot stretching device 2 is used to hot stretch the prepared PU meltblown preform, and is connected to the mixed solution injection device 5, the annular ultrasonic heating device 1, and the Sirofil spinning device 3.

[0126] The mixed solution injection device 5 is used to inject the liquid metal mixed solution into the PU meltblown intermediate layer 7 of the PU meltblown preform, and is connected to the wire drawing tower hot stretching device 2.

[0127] The serifil spinning device 3 is used to prepare aramid core-spun yarn and is connected to the drawing tower hot stretching device 2.

[0128] The meltblown fabric winding device 4 winds the PU meltblown fabric manufactured by the meltblown process onto a stainless steel tube, with several layers. After winding, the annular ultrasonic heating device 1 uniformly spots-bonds the multiple layers of PU meltblown fabric wound on the stainless steel tube, obtaining a PU meltblown preform with uniform interlayer gaps. The wire drawing tower hot stretching device 2 hangs the PU meltblown preform in the wire drawing tower hot stretching device 2 and bonds its bottom ends together. Utilizing the principle of hot stretching, the PU meltblown preform is compressed and refined until it is stretched into a fibrous PU meltblown intermediate layer 7. While the PU meltblown intermediate layer 7 is being thermally stretched, a liquid metal mixture solution is injected into the PU meltblown intermediate layer 7 of the PU meltblown preform through the top opening of the PU meltblown preform using a mixture solution injection device 5. Then, aramid core-spun yarn from the Sirofil spinning device 3 is added. The aramid filaments and aramid rovings are twisted together with the PU meltblown intermediate layer 7 in the form of Sirofil spinning. Using the residual heat from the thermal stretching process, the surface of the PU meltblown intermediate layer 7 is thermally bonded to the aramid core-spun yarn in a softened state to obtain aramid composite conductive fiber.

[0129] like Figure 6 As shown, the heating part of the annular ultrasonic heating device 1 has an annular structure.

[0130] like Figure 7 As shown, the hot drawing tower device 2 includes: a spatial position control module 201, a laser diameter measuring and planar position measuring instrument 202, a pressure adjustment module 203, a fiber position limiting module 204, a drawing module 205, an inert gas conveying module 206, a heating furnace temperature control module 207, a hot-drawn filament 208, a high-temperature heating module 209, a preform suspension module 210, and a concentricity control module 211.

[0131] The system includes: a spatial position control module 201 for controlling the position of the suspended PU meltblown preform; a laser diameter measuring and planar position measuring instrument 202 for limiting the diameter of the PU meltblown preform during hot stretching; a pressure adjustment module 203 for limiting the pressure applied to the PU meltblown preform during hot stretching; a fiber position limiting module 204 for limiting the position of the PU meltblown preform during hot stretching, which may be a limiting ring; and a fiber drawing module 205 for winding, collecting, and compressing the PU meltblown preform. The refined fibers are processed by the following modules: drawing module 205 (which can be a drawing disc); inert gas delivery module 206 (used to control the hot stretching conditions in the three temperature zones); furnace temperature control module 207 (used to control the hot stretching conditions in the three temperature zones); hot-stretched filament 208 (the fiber obtained after shrinking and refining the PU meltblown preform); high-temperature heating module 209 (used to heat the PU meltblown preform); preform suspension module 210 (used to suspend the PU meltblown preform); and concentricity control module 211 (used to fine-tune the center of the obtained fibers).

[0132] A preform suspension module 210 suspends a PU meltblown preform. A high-temperature heating module 209 is externally mounted on the preform suspension module 210 to heat the PU meltblown preform. An inert gas delivery module 206 and a furnace temperature control module 207 jointly control the thermal stretching conditions in three temperature zones. The fibers obtained after the PU meltblown preform is compressed and refined are thermally stretched filaments 208. A drawing module 205 winds and collects the fibers obtained after the PU meltblown preform is compressed and refined. A spatial position control module 201 controls the position of the suspended PU meltblown preform. A laser diameter measuring and planar position measuring instrument 202 limits the diameter of the PU meltblown preform during thermal stretching. A pressure adjustment module 203 limits the pressure applied to the PU meltblown preform during thermal stretching. A fiber position limiting module 204 limits the position of the PU meltblown preform during thermal stretching. A concentricity control module 211 fine-tunes the center of the resulting fibers. The fiber position limiting module 204 can be a limiting ring, the drawing module 205 can be a drawing disc, and the high-temperature heating module 209 can be a ZYL-type high-temperature heating furnace. The liquid metal mixture is injected from the top opening of the PU meltblown preform into the PU meltblown intermediate layer 7 of the PU meltblown preform through the mixing solution injection device 5, which is equipped with an injection pump.

[0133] The Sirofil spinning device 3 utilizes an aramid filament and an aramid roving, which are simultaneously fed into the spinning frame. After drafting, the filament is directly fed into the nip of the front roller 304 of the spinning frame, maintaining a certain distance from the simultaneously fed roving, and together they are twisted to form aramid core-spun yarn. For example... Figure 8 As shown, the Sirofil spinning device 3 includes: a filament winding module 301, a roving winding module 302, a tension disc 303, a front roller 304, a guide roller 305, and a core-spun yarn winding module 306.

[0134] Among them, the filament winding module 301 is used to feed in the winding filament;

[0135] Roving module 302 is used to feed in roving for winding;

[0136] Tension plate 303 is used to adjust the tension of the filaments to ensure that the filaments are evenly distributed;

[0137] Guide roller 305 is used to pull filaments and rovings and to connect filaments and rovings;

[0138] Front roller 304 is used to twist filaments and rovings to form aramid core-spun yarn;

[0139] Core-spun yarn winding module 306 is used to process and recycle aramid core-spun yarn.

[0140] The filament winding module 301 feeds in the wound filament. After being adjusted by the tension plate 303, the filament is evenly passed through the guide roller 305 and merged with the roving at the front roller 304. The roving winding module 302 feeds in the wound roving. The roving is pulled by the guide roller 305 and merged with the filament at the front roller 304. The front roller 304 twists the filament and roving into aramid core-spun yarn, and the core-spun yarn winding module 306 sorts and recycles the aramid core-spun yarn for subsequent use.

[0141] Comparative Example 1

[0142] Unlike step S1 in Example 2, the fabrication of the PU meltblown preform in this comparative example is changed to compression molding. Step S1 is as follows:

[0143] The hollow cylindrical compression molding mold is preheated, and polyurethane material is evenly placed in the mold in sheet form. The mold is closed and the material is formed into a stable cylindrical shape inside the mold by high temperature and high pressure. After the polyurethane is completely cured, the pressure is gradually reduced and the mold is cooled to facilitate demolding and maintain the product dimensional accuracy. After demolding, a hollow PU meltblown preform is obtained.

[0144] The preheating temperature of the compression molding die is 180℃, the working temperature after the die is closed is 200℃, and the working pressure is 30MPa. The resulting PU meltblown preform is a hollow column with an inner diameter of 12mm, an outer diameter of 17mm, and a height of 1.5m.

[0145] Comparative Example 2

[0146] Unlike step S3 in Example 2, in this comparative example, the infusion of the conductive core layer 6 of the mixed solution and the compaction and refinement of the PU meltblown intermediate layer 7 are no longer performed simultaneously. Step S3 is as follows:

[0147] After the PU meltblown preform is fully stretched and refined to obtain PU fibers with an average inner diameter of 2 mm and an average outer diameter of 2.7 mm, the PU fibers are then suspended and the prepared liquid metal mixture solution is injected from their tops until it fills the entire PU meltblown intermediate layer 7 of the PU fibers.

[0148] Comparative Example 3

[0149] Unlike step S4 in Example 2, Sirofil spinning is not performed under residual heat conditions in this comparative example. Step S4 is as follows:

[0150] After the outer surface temperature of the PU fiber approaches room temperature, aramid filaments and aramid rovings are twisted with the PU meltblown interlayer 7 in a Siroserische form, so that the PU meltblown interlayer 7 and the aramid core-spun yarn are twisted together to form the aramid core-spun yarn skin layer 8. The diameter of the aramid filament is 0.02 mm, the twisting speed of the aramid core-spun yarn is 80 TPM, and the temperature of the outer surface of the PU meltblown interlayer 7 during twisting is 25℃.

[0151] The performance of the high-performance aramid composite conductive fibers prepared in Examples 2 to 4 and Comparative Examples 1 to 3 was tested. The test parameters included conductivity, fire rating, tensile breaking strength, elongation at break, bending resistance, chemical resistance and thermal stability.

[0152] The standards for conductivity testing are GB / T 3048.4-2007; fire resistance testing is GB / T 5455-2014; tensile strength and elongation at break testing are GB / T3923.1-2013; flexural strength testing is GB / T 21196.1-2007; chemical resistance testing involves immersion testing, where the sample is completely immersed in a specific chemical substance for a certain period, and then the changes in mass, loss of mechanical properties, or changes in appearance are evaluated; thermal stability testing uses thermogravimetric analysis (TGA) to measure the mass change of the material during heating, which is used to evaluate the material's thermal decomposition temperature and thermal stability. The performance test results are shown in Table 1.

[0153] Table 1. Performance test parameter values.

[0154]

[0155] Based on the data in Table 1, compared with other examples and comparative examples, the high-performance aramid composite conductive fiber prepared in Example 2 exhibits superior conductivity, reaching 1×10⁷ Siemens per meter. This is a result of the synergistic effect of the liquid metal and magnesium nanoparticles. Furthermore, the composite fiber possesses excellent mechanical properties, with a tensile breaking strength of 3268 MPa. Compared to traditional conductive fibers and ordinary aramid composite fibers, the ductility of this aramid composite conductive fiber is also improved to 4.1%, effectively avoiding the bending breakage and limited use problems caused by poor ductility in conductive fibers. In the bending resistance test, it achieved a bending count of 5214 times, demonstrating that the thickness of the PU meltblown interlayer 7 and the diameter of the composite fiber are not the decisive factors for bending performance. Example 2 demonstrates the optimal chemical resistance parameters. In the thermal stability test, Example 2 achieved a heat resistance temperature of 265℃, indicating that the thermal stability of this aramid composite conductive fiber is mainly reflected in the stability of the aramid core-shell structure and the composite architecture.

[0156] Compared with Example 2, the thermal stability and fire resistance of the aramid composite conductive fiber prepared in Comparative Example 1 decreased. Under the process conditions, the structural stability of the composite conductive fiber was significantly reduced, indicating that the preform fabrication and its combination with stretching and refining proposed in this invention have better structural stability than ordinary compression molding followed by hot stretching. It can also achieve uniform and effective bonding with the aramid core-spun yarn skin layer 8. Compared with the stretching and refining process with a uniform layered structure, the integral molding of compression molding results in lower tensile breaking strength, chemical resistance, and thermal stability of the fiber. This further demonstrates the structural advantages of the layered uniform point-bonded preform in the stretching and refining process.

[0157] Compared to Example 2, the conductivity of the aramid composite conductive fiber prepared in Comparative Example 2 decreased significantly, reaching only 5E+0.5 S / m. This indicates that simultaneously infusing the mixed solution conductive core layer 6 and shrinking and refining the PU meltblown interlayer 7 is essential for maintaining the high conductivity of the composite fiber. Filling the mixed solution conductive core layer 6 while stretching and refining the fiber improves the adhesion and contact quality between the mixed solution conductive core layer 6 and the PU meltblown interlayer 7, thereby enhancing the overall mechanical strength and conductivity of the structure. Simultaneously, the ineffective contact between the mixed solution conductive core layer 6 and the PU meltblown interlayer 7 also led to a significant decrease in elongation at break, resulting in a lack of toughness in the prepared composite fiber and limiting its application scenarios and service life.

[0158] Compared to Example 2, the mechanical properties of the aramid composite conductive fiber prepared in Comparative Example 3 decreased significantly. The direct twisting of the aramid core-spun yarn sheath 8 led to a significant reduction in its composite strength and elongation at break with the PU meltblown interlayer 7. The decrease in the toughness of the composite fiber also directly resulted in a reduction in its bending resistance. At the same time, its chemical resistance and thermal stability were also weakened. This indicates that the combination of thermal bonding and twisting indeed enabled the aramid core-spun yarn sheath 8 to be uniformly and stably bonded together with the PU meltblown interlayer 7. This is mainly reflected in two aspects. On the one hand, this composite method can make the aramid core-spun yarn skin layer 8 and the PU meltblown intermediate layer 7 bond more tightly and stably, thereby enhancing the mechanical strength of the composite fiber and preventing chemical corrosives from penetrating into the interior of the composite fiber. On the other hand, the combination of the spun yarn form and thermal bonding allows both the PU meltblown intermediate layer 7 and the aramid core-spun yarn skin layer 8 to retain a certain elongation strain capacity. The aramid core-spun yarn will be partially embedded into the PU meltblown intermediate layer 7 due to thermal bonding, which also provides possible space for the elongation of the aramid core-spun yarn skin layer 8 during stretching, further improving the toughness of the composite fiber.

[0159] It should be noted that in this invention, the polyurethane chips are specifically type 1580 PU, and the processing level is extrusion grade; the hydrochloric acid solution has an equivalent concentration of 0.01 mol / L; the anhydrous ethanol has an ethanol content of 99.99%; and the magnesium nanoparticles have a particle size of nanoscale.

[0160] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0161] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing high-performance aramid composite conductive fibers, characterized in that, Includes the following steps: S1. Prepare PU meltblown preforms; Polyurethane chips are processed into PU meltblown fabric using a meltblown process. The PU meltblown fabric is then wound onto a stainless steel tube in a layered structure. The PU meltblown fabric on the stainless steel tube is heated using a ring-shaped ultrasonic heating device to soften and bond it. The steel tube is then removed to obtain a PU meltblown preform. S2. Prepare a liquid metal mixed solution; GaN liquid metal was immersed in hydrochloric acid solution, allowed to stand, washed with anhydrous ethanol, magnesium nanoparticles were added, and stirred evenly with a magnetic stirrer to obtain a liquid metal mixed solution with magnesium nanoparticles uniformly mixed. S3. Simultaneously, while preparing the PU meltblown interlayer, inject the liquid metal mixture solution into the PU meltblown interlayer; The bottom ends of the PU meltblown preforms are bonded together in an annular ultrasonic heating device. The principle of thermal stretching is used to shrink and refine the PU meltblown preforms until they are stretched into fibrous PU meltblown intermediate layers. While the PU meltblown intermediate layer is being hot-stretched, a liquid metal mixture solution is injected into the PU meltblown intermediate layer of the PU meltblown preform through the top opening of the PU meltblown preform using an injection pump. S4. Thermally bond the PU meltblown interlayer and the aramid core-spun yarn to obtain aramid composite conductive fiber. Aramid filaments and aramid rovings are twisted with PU meltblown interlayer in the form of Sirofil spinning, and the residual heat during the hot stretching process is used to thermally bond the surface of the PU meltblown interlayer with the aramid core-spun yarn in a softened state to obtain aramid composite conductive fiber. Aramid composite conductive fibers include: The mixed solution conductive core layer is covered with a PU meltblown intermediate layer. The outer side of the PU meltblown intermediate layer is an aramid core-spun yarn skin layer formed by hot twisting and hot bonding of aramid filaments and aramid rovings through Sirofil spinning process. The PU meltblown intermediate layer is a layered meltblown structure with interlayer gaps.

2. The method for preparing high-performance aramid composite conductive fiber according to claim 1, characterized in that, In S1, the polyurethane chip melt index is 280g / 10min, the melt temperature is 210℃, the spinning speed is 200m / min, the wind speed is 200m / min, and the receiving distance is 20cm; the areal density of the PU meltblown fabric is 1.2-1.3g / cm3, and the thickness is 0.2-0.3mm; the outer diameter of the stainless steel tube is 12mm, the number of winding layers of the PU meltblown fabric is 5-6 layers, and the heating temperature of the annular ultrasonic heating device is 180-200℃.

3. The method for preparing high-performance aramid composite conductive fiber according to claim 1, characterized in that, In S2, the concentration of hydrochloric acid solution is 5%-20%, the concentration of anhydrous ethanol is 99.9%, the mass ratio of gallium indium tin liquid metal to magnesium nanoparticles ranges from 1:1 to 10:1, the diameter of magnesium nanoparticles is 5-10 nm, and the rotation speed of the magnetic stirrer is 600-800 r / min.

4. The method for preparing high-performance aramid composite conductive fiber according to claim 1, characterized in that, In S3, the drawing speed is 2cm / s, the diameter of the PU meltblown intermediate layer is 1.5-2.0mm, the upper temperature zone is 190-210℃, the middle temperature zone is 150-170℃, and the lower temperature zone is 110-130℃. The hot stretching temperature range is 100-190℃, the diameter of the PU meltblown interlayer is 0.3-0.4mm, the flow rate of the injection pump is 226.2ml / h, and the diameter of the injection pump needle is 1.5mm.

5. The method for preparing high-performance aramid composite conductive fiber according to claim 1, characterized in that, In S4, the diameter of the aramid filament is 0.02-0.03 mm, the twisting speed of the aramid core-spun yarn is 80-100 TPM, and the surface temperature of the PU meltblown interlayer is 140-150℃.

6. A high-performance aramid composite conductive fiber preparation system, applicable to the high-performance aramid composite conductive fiber preparation method as described in any one of claims 1-5, characterized in that, include: Meltblown fabric winding device, used to wind PU meltblown fabric onto a stainless steel tube; A ring-shaped ultrasonic heating device is used to uniformly spot bond PU meltblown fabric wound on a stainless steel tube to obtain PU meltblown preforms, and is connected to a meltblown fabric winding device. The hot stretching device is used to hot stretch the produced PU meltblown preforms and is connected to an annular ultrasonic heating device. A mixed solution injection device is used to inject a liquid metal mixed solution into the PU meltblown intermediate layer of the PU meltblown preform, and is connected to the wire drawing tower hot stretching device; The serofil spinning apparatus is used to prepare aramid core-spun yarn and is connected to the drawing tower and hot stretching device.

7. The high-performance aramid composite conductive fiber preparation system according to claim 6, characterized in that, The thermal stretching device for the wire drawing tower includes: The spatial position control module is used to control the position of the suspended PU meltblown preform. Laser diameter measuring and planar position measuring instrument is used to limit the diameter of PU meltblown preforms during hot stretching. The pressure adjustment module is used to limit the pressure applied to the PU meltblown preform during hot stretching; Fiber position limiting module, used to limit the position of PU meltblown preform during hot stretching; The fiber drawing module is used to wind and collect the fibers obtained after the PU meltblown preform is compressed and refined. An inert gas delivery module is used to participate in controlling the thermal stretching conditions in three temperature zones; The heating furnace temperature control module is used to participate in controlling the thermal stretching conditions in the three temperature zones. High-temperature heating module, used to heat PU meltblown preforms; Preform suspension module for suspending PU meltblown preforms; The concentricity control module is used to fine-tune the center of the produced fibers.

8. The high-performance aramid composite conductive fiber preparation system according to claim 6, characterized in that, The Sirofil spinning apparatus includes: Filament winding module, used for feeding in winding filaments; Roving module for feeding in roving; Tension plate is used to adjust the tension of filaments to ensure that the filaments are evenly distributed; Guide rollers are used to pull filaments and rovings, and to connect filaments and rovings; The front roller is used to twist filaments and rovings to form aramid core-spun yarn. Core-spun yarn winding module, used for sorting and recycling aramid core-spun yarn.

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