Method for preparing nanofiber wrap yarn for personal thermal management through coaxial conjugate electrostatic spinning

Abstract

The invention discloses a method for preparing nanofiber wrap yarn for personal thermal management through coaxial conjugate electrostatic spinning. The method comprises the steps that 1, a core layer spinning solution and a shell layer spinning solution are prepared; 2, a coaxial conjugate electrostatic spinning device is built; 3, the nanofiber wrap yarn for personal thermal management is formed, wherein the core yarn serves as a core layer, and the outer wrapping layer of the core-shell structure nanofiber with the temperature adjusting function serves as a skin layer. Coaxial electrostatic spinning and conjugate electrostatic spinning are combined, the core-shell structure nanofibers with the phase-change material as the core layer are rotationally wrapped on the core yarn, meanwhile, the temperature-adjusting functional material is loaded on the core-shell structure nanofibers, and the temperature-adjusting nanofiber wrap yarn suitable for personal thermal management is formed.

Description

Technical Field

[0001] The present invention relates to the field of personal thermal management, and specifically to a method for preparing nanofiber-coated yarn for personal thermal management by coaxial conjugate electrospinning. Background Art

[0002] Currently, the goal of personal thermal management (PTM) technology is to regulate the human body temperature without wasting excess energy, including personal heat preservation, cooling, and temperature adjustment. The related intelligent textiles that can achieve spontaneous temperature regulation and control are more flexible and extensive in application, and can efficiently promote human thermal comfort. Due to their flexibility, scalability, and the ability to meet the energy-saving and diverse personal temperature regulation needs, intelligent textiles have good development prospects in PTM technology. Reducing energy consumption is the key to sustainable development. So far, photothermal conversion and radiative cooling have shown great prospects on intelligent textiles.

[0003] Solar energy, as a green, clean, and renewable energy, mainly brings light and heat to the earth in the form of electromagnetic radiation. Due to the inexhaustible and renewable nature of solar energy, using solar energy as the energy source for intelligent temperature regulation has become a research hotspot. By using the photothermal conversion mechanism of photothermal conversion materials, the absorbed light energy is converted into heat energy, thereby providing heat for fabrics and the human body. This can alleviate the problem of resource shortage to a certain extent. However, solar energy is unstable and discontinuous, and cannot ensure all-weather intelligent temperature regulation. To alleviate this instability of energy supply and demand, thermal energy storage technology can be adopted. Phase change materials (PCMs), as energy storage media, can store or release a large amount of energy at a nearly constant temperature during the melting or solidification process. Among them, solid-liquid phase change materials are more commonly used. However, when the external temperature reaches its phase change temperature, a solid-liquid state transition will occur, and there will be disadvantages such as easy leakage during the heat utilization process, thereby reducing the heat utilization efficiency and service life, etc. Therefore, the encapsulation technology has become one of the essential technological links. Currently, the main methods for encapsulating PCMs are: hollow impregnation method, microencapsulation method, and electrospinning method.

[0004] Passive radiative cooling (PRC) technology requires no energy input and mainly relies on the excellent light management capabilities of materials, including high solar reflectivity and mid-infrared emissivity. By reflecting sunlight (wavelength 0.3 - 2.5 μm) and, based on excellent mid-infrared light emission performance, emitting heat from the infrared atmospheric window (wavelength 8 - 13 μm) to outer space, it realizes the spontaneous cooling of the object surface without the consumption of external energy. In recent years, researchers have applied PRC technology to fabrics to prepare PRC textiles with cooling or refrigeration functions, which have broad application prospects in the fields of high-temperature energy conservation and radiative cooling. PRC textiles can be designed using the optical properties and structures of materials. Materials with high infrared emissivity can dissipate heat in a timely manner, and high solar reflection materials can minimize heat absorption to the greatest extent. At the same time, structural design can also achieve an ideal cooling effect, including loading nanoparticles, porous structures, multi-layer structures, etc. These material and structural designs enable PRC textiles to exhibit ideal refrigeration effects.

[0005] Therefore, combining photothermal conversion, radiative cooling with phase change materials and applying them to the field of personal thermal management textiles has practical significance and development prospects. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a method for preparing nanofiber-coated yarn for personal thermal management by coaxial conjugate electrospinning.

[0007] The technical solution of the present invention to solve the above technical problem is to provide a method for preparing nanofiber-coated yarn for personal thermal management by coaxial conjugate electrospinning, which includes the following steps:

[0008] Step 1: Prepare the core layer spinning solution and the shell layer spinning solution;

[0009] Heat the phase change material to melt it into a liquid state to obtain the core layer spinning solution;

[0010] Dissolve the polymer in an organic solvent to obtain a polymer solution; then add the temperature-regulating functional material to the polymer solution and disperse it evenly to obtain the shell layer spinning solution; the temperature-regulating functional material is one of a photothermal material or a radiative cooling material;

[0011] Step 2: Set up a coaxial conjugate electrospinning device;

[0012] The device includes a shell layer spinning solution propeller, a core layer spinning solution propeller, a coaxial needle, a positive electrode, a negative electrode, a unwinding roller, a metal rotary funnel and a collecting device;

[0013] The coaxial needle has a coaxial structure with a core layer channel and a shell layer channel, and the shell layer channel is nested outside the core layer channel; both the shell layer spinning solution propeller and the core layer spinning solution propeller are installed on the coaxial needle; the shell layer spinning solution propeller is communicated with the shell layer channel and pushes the shell layer spinning solution into the shell layer channel during spinning; the core layer spinning solution propeller is communicated with the core layer channel and pushes the core layer spinning solution into the core layer channel during spinning;

[0014] A unwinding roller, a metal rotary funnel and a collecting device are arranged in sequence along the advancing direction of the core yarn; the core yarn is wound on the unwinding roller and is released during spinning; the collecting device is used for collecting the nanofiber-coated yarn for personal thermal management and controlling the moving speed of the core yarn;

[0015] The two coaxial needles are on the same horizontal plane; the metal rotary funnel is at the same distance from the two coaxial needles, is on the vertical plane in the middle of the two, and is within the electrostatic field range generated by the coaxial needles when high voltage is applied; one of the two coaxial needles is connected to the positive pole of the power supply, and the other is connected to the negative pole of the power supply for generating an electrostatic field; the metal rotary funnel can rotate along its own central axis;

[0016] Step 3: Prepare the nanofiber-coated yarn for personal thermal management;

[0017] Set the spinning parameters; place the shell layer spinning solution in the shell layer spinning solution propeller and the core layer spinning solution in the core layer spinning solution propeller; one end of the core yarn is wound on the unwinding roller, passes through the metal rotary funnel, and the other end is wound on the collecting device, and the core yarn is pulled and moved by the collecting device;

[0018] Start coaxial conjugate electrospinning to uniformly coat the core yarn with core-shell structure nanofibers with a phase change material as the core layer and a polymer and temperature-regulating functional material as the shell layer, forming a primary coated yarn with the core yarn as the core layer and the core-shell structure nanofibers as the skin layer; then dry the primary coated yarn until all the solvent volatilizes to obtain the nanofiber-coated yarn for personal thermal management.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] (1) The present invention combines coaxial electrospinning and conjugate electrospinning, rotates and wraps the nanofibers with a core-shell structure with a phase change material as the core layer on the core yarn, and at the same time loads a temperature-regulating functional material on the core-shell structure nanofibers to form a temperature-regulating nanofiber-coated yarn suitable for personal thermal management.

[0021] (2) The nanofiber-coated yarn for personal thermal management prepared by coaxial conjugate electrospinning is formed by taking the core yarn as the core layer and the outer coating of the core-shell structured nanofibers with temperature-regulating function as the cortex layer. Compared with the film formed by spraying, this form of winding the core-shell structured nanofibers around the core yarn greatly improves the mechanical properties of the fabric, making it not easy to fall off and wear during use, and avoiding the problem of poor adhesion of the film directly attached to the fabric.

[0022] (3) The temperature-regulating nanofiber-coated yarn for personal thermal management of the present invention can be woven as a basic unit, and further processed and compounded to make fabrics with various structural tissues and patterns, realizing the functionalization and mechanical properties of intelligent temperature-regulating textiles. The fabric woven with the coated yarn as the base has been greatly improved in air permeability, comfort, aesthetics, and wearing performance compared with the fabric attached with the nanofiber film.

[0023] (4) Compared with ordinary photothermal performance-coated yarns, the photothermal phase change nanofiber-coated yarn prepared by the present invention uses photothermal phase change nanofibers with a core-shell structure. Nanofibers of this structure have stronger encapsulation of the phase change material, avoiding leakage and other situations of the phase change material during use, having a long service life, being stable and continuous, and having good durability, realizing a stable and continuous heat storage and temperature regulation effect. Combining the photothermal material with the phase change material can store the solar heat absorbed by the photothermal material in the phase change material, realizing comprehensive properties such as high heat storage capacity, excellent photothermal conversion performance, good thermal conductivity, and heat dissipation.

[0024] (5) Compared with ordinary radiation cooling yarns, the passive radiation cooling nanofiber-coated yarn prepared by the present invention uses passive radiation cooling nanofibers with a core-shell structure. The excellent heat storage effect of the PCM in the core layer and the dual combination of high solar reflectance and high infrared emission in the shell layer make the cooling effect more stable and continuous. At the same time, the superiority of the structure has stronger encapsulation of the PCM, avoiding leakage and other situations of the PCM during use, having a long service life, being stable and continuous, and having good durability, realizing a stable and continuous cooling effect. The porous structure in which the nanofibers in the passive radiation cooling nanofiber-coated yarn are intertwined and overlapped can scatter and diffract the solar spectrum multiple times, and the added high-reflection particles also have a high reflectivity to the solar spectrum. At the same time, the polymer used is also a high-emission material, which can dissipate heat in time, and finally has a high reflectivity and solar emissivity to the solar spectrum. Description of the Drawings

[0025] Figure 1 It is a schematic diagram of the preparation process of the nanofiber-coated yarn of the present invention;

[0026] Figure 2 It is a schematic diagram of the structure of the coaxial needle of the present invention;

[0027] Figure 3 SEM surface image of the photothermal phase change nanofiber coated yarn prepared in Example 1 of the present invention, magnified 1000 times;

[0028] Figure 4 SEM surface image of the photothermal phase change nanofiber coated yarn prepared in Example 1 of the present invention, magnified 2000 times;

[0029] Figure 5 SEM cross-sectional image of the photothermal phase change nanofiber coated yarn prepared in Example 1 of the present invention, magnified 150 times;

[0030] Figure 6 SEM cross-sectional image of the photothermal phase change nanofiber coated yarn prepared in Example 1 of the present invention, magnified 300 times;

[0031] Figure 7 Photothermal conversion performance test diagram of the photothermal phase change nanofiber coated yarn prepared in Example 1 of the present invention;

[0032] Figure 8 DSC performance test diagram of the photothermal phase change nanofiber coated yarn prepared in Example 1 of the present invention;

[0033] Figure 9 SEM surface image of the passive radiative cooling nanofiber coated yarn prepared in Example 5 of the present invention, magnified 200 times;

[0034] Figure 10 SEM surface image of the passive radiative cooling nanofiber coated yarn prepared in Example 5 of the present invention, magnified 500 times;

[0035] Figure 11 DSC performance test diagram of the passive radiative cooling nanofiber coated yarn prepared in Example 5 of the present invention;

[0036] Figure 12 Temperature curve diagram for comparing the cooling effects of the core yarn used in Example 5 of the present invention and the passive radiative cooling nanofiber coated yarn prepared;

[0037] Figure 1 Among them, the shell spinning solution propeller 1, the core spinning solution propeller 2, the coaxial needle 3, the positive electrode 4, the negative electrode 5, the core-shell structure nanofiber 6, the core yarn 7, the unwinding roller 8, the metal rotary funnel 9, the fiber web 10, the nanofiber coated yarn for personal thermal management 11, the collecting device 12; the shell channel 301, the core channel 302. Detailed implementation manners

[0038] The following are specific embodiments of the present invention. The specific embodiments are only used to further illustrate the present invention in detail and do not limit the protection scope of the present invention.

[0039] The present invention provides a method for preparing nanofiber-coated yarn for personal thermal management by coaxial conjugate electrospinning (hereinafter referred to as the method), which includes the following steps:

[0040] Step 1: Prepare the core layer spinning solution and the shell layer spinning solution;

[0041] Heat the phase change material to melt it into a liquid state to obtain the core layer spinning solution;

[0042] Dissolve the polymer in an organic solvent to obtain a polymer solution; then add the temperature-regulating functional material to the polymer solution and disperse it evenly to obtain the shell layer spinning solution;

[0043] Preferably, in Step 1, the phase change material is one of n-octadecane, n-tetradecane, polyethylene glycol, or paraffin.

[0044] Preferably, in Step 1, the heating process of the phase change material is: heating at 40 - 50 °C for 0.5 - 1 h; preferably carried out in a water bath.

[0045] Preferably, in Step 1, the polymer is polyacrylonitrile (PAN) or polyvinylidene fluoride (PVDF); the organic solvent is DMF (N,N-dimethylformamide) and / or acetone; when the polymer is PVDF, the organic solvent is a mixed solvent of DMF and acetone with a mass ratio of 6 - 7:3 - 4.

[0046] Preferably, in Step 1, the polymer dissolution process is: stirring at 60 - 70 °C at 1000 - 2000 rpm for 6 - 10 h.

[0047] Preferably, in Step 1, the temperature-regulating functional material is one of a photothermal material or a radiative cooling material.

[0048] Preferably, in Step 1, the photothermal material is Mxene or graphene; the radiative cooling material is one or more of TiO2, SiO2, BaSO4, or ZnO (preferably a composition of ZnO and SiO2 with a mass ratio of 1:1); the particle size of the radiative cooling material is 80 - 1600 nm (preferably 80 - 100 nm).

[0049] Preferably, in Step 1, the dispersion process of the temperature-regulating functional material is: first stirring at a speed of 1000 - 2000 rpm for 1 - 2 h, and then ultrasonic treating at 80 - 120 Hz / min for 1 - 2 h.

[0050] Preferably, in Step 1, in the shell layer spinning solution, the mass fraction of the polymer is 10 - 15%; the mass fraction of the photothermal material is 1 - 5%; the mass fraction of the radiative cooling material is 2 - 8% (preferably 4 - 6%).

[0051] Preferably, in step 1, Mxene is subjected to centrifugal swelling treatment, or graphene is dispersed so that Mxene or graphene can be dissolved in the organic solvent in step 1, which is the prior art.

[0052] Step 2: Set up a coaxial conjugate electrospinning device;

[0053] The device includes a shell layer spinning solution propeller 1, a core layer spinning solution propeller 2, a coaxial needle 3, a positive electrode 4, a negative electrode 5, a unwinding roller 8, a metal rotary funnel 9, and a collecting device 12;

[0054] The coaxial needle 3 has a coaxial structure with a core layer channel 302 and a shell layer channel 301. The shell layer channel 301 is nested outside the core layer channel 302; both the shell layer spinning solution propeller 1 and the core layer spinning solution propeller 2 are installed on the coaxial needle 3; the shell layer spinning solution propeller 1 is communicated with the shell layer channel 301, and when spinning, the shell layer spinning solution is pushed into the shell layer channel 301; the core layer spinning solution propeller 2 is communicated with the core layer channel 302, and when spinning, the core layer spinning solution is pushed into the core layer channel 302;

[0055] An unwinding roller 8, a metal rotary funnel 9, and a collecting device 12 are arranged in sequence along the advancing direction of the core yarn 7; the core yarn 7 is wound on the unwinding roller 8 and the core yarn 7 is released during spinning; the collecting device 12 is used to collect the final product, namely the nanofiber-coated yarn 11 for personal thermal management (abbreviated as coated yarn 11) and control the moving speed of the core yarn 7;

[0056] The two coaxial needles 3 are on the same horizontal plane; the metal rotary funnel 9 is at the same distance from the two coaxial needles 3, is located on the mid-perpendicular plane of the two, and is within the electrostatic field range generated by the coaxial needles 3 when high voltage is applied; one of the two coaxial needles 3 is connected to the positive electrode 4 of the power supply, and the other is connected to the negative electrode 5 of the power supply for generating an electrostatic field; the metal rotary funnel 9 can rotate along its own central axis;

[0057] Preferably, in step 2, the core yarn 7 is a yarn, preferably one of cotton yarn, polyester yarn, nylon yarn, or polyester-cotton yarn.

[0058] Preferably, in step 2, the metal rotary funnel 9 is in the shape of a flared opening.

[0059] Preferably, in step 2, to avoid interference, the outer wall of the coaxial needle 3 is provided with an opening, and the shell layer spinning solution propeller 1 is fixed at the opening of the outer wall of the coaxial needle 3 and is communicated with the side wall of the shell layer channel 301; more preferably, the shell layer spinning solution propeller 1 and the core layer spinning solution propeller 2 are perpendicular to each other.

[0060] Step 3: Prepare the nanofiber-coated yarn 11 for personal thermal management;

[0061] Set spinning parameters; place the shell spinning solution in the shell spinning solution propeller 1 and the core spinning solution in the core spinning solution propeller 2; one end of the core yarn 7 is wound around the unwinding roller 8, passes through the metal rotary funnel 9, and the other end is wound around the collecting device 12. The core yarn 7 is pulled and moved by the collecting device 12.

[0062] Start coaxial conjugate electrospinning to uniformly coat the core-shell structured nanofibers 6 with the core layer being the phase change material and the shell layer being the polymer and temperature-regulating functional material on the outer side of the core yarn 7, forming a primary coated yarn with the core yarn 7 as the core layer and the core-shell structured nanofibers 6 as the cortical layer; then dry the primary coated yarn until all the solvent volatilizes to obtain the nanofiber coated yarn 11 for personal thermal management.

[0063] Preferably, in step 3, the specific process of coaxial conjugate electrospinning is as follows: Turn on the DC power supply and start spinning. During the spinning process, the core yarn 7 is in a straight state; under the action of the high-voltage electric field, the spinning solutions in the two coaxial needles 3 are stretched into fibrous shapes in the electric field, respectively forming the core-shell structured nanofibers 6; the difference in positive and negative charges causes the core-shell structured nanofibers 6 spun by the two coaxial needles 3 to be entangled with each other. At the same time, electrostatic induction will occur between the two coaxial needles 3 and the metal rotary funnel 9, and the core-shell structured nanofibers 6 will be collected on the metal rotary funnel 9; through the traction effect of the core yarn 7 on the electrospun fibers, a triangular fiber web 10 formed by a fiber bundle of multiple core-shell structured nanofibers 6 is formed at the opening of the metal rotary funnel 9; through the stretching and traction of the collecting device 12 on the core yarn 7, the fiber bundles in the fiber web 10 are oriented; at the same time, the rotation of the metal rotary funnel 9 causes the fiber bundles to be evenly entangled and coated on the outer surface of the core yarn 7 to form an outer coating layer, and finally a primary coated yarn with the core yarn 7 as the core layer and the outer coating layer as the cortical layer is formed on the collecting device 12.

[0064] Preferably, in step 3, the spinning parameters are as follows: the distance between the two coaxial needles 3 is 15 - 20 cm; the distance between the coaxial needle 3 and the metal rotary funnel 9 is 12 - 15 cm; the voltage of the positive electrode 4 is 5 - 7 kV, and the voltage of the negative electrode 5 is -7 - -5 kV; the propulsion rate of the shell spinning solution is 0.4 - 0.7 mL / h, and the propulsion rate of the core spinning solution is 0.1 - 0.2 mL / h; by adjusting the rotation speed of the collecting device 12 to adjust the moving speed (i.e., the collecting speed) of the core yarn 7, so that the collecting speed is adapted to the spinning speed, and the moving speed of the core yarn 7 is 0.1 - 0.4 mm / s; the rotation speed of the metal rotary funnel 9 is 300 - 500 rpm; the spinning environment temperature is 25 ± 5 °C, and the humidity is 40 ± 5%.

[0065] Preferably, in step 3, the mass ratio of the core-shell structured nanofibers 6 to the core yarn 7 is 0.2 - 0.5:1 (preferably 0.2 - 0.3:1).

[0066] Preferably, in step 3, the average diameter of the nanofiber-coated yarn 11 for personal thermal management is 380 - 600 μm (preferably 400 - 500 μm).

[0067] Preferably, in step 3, the drying process is as follows: drying for at least 4 h in an indoor environment (i.e., at a temperature of 20 - 35 °C and a humidity of 20 - 40%).

[0068] Preferably, in step 3, the core-shell structured nanofiber 6 is a core-shell structured photothermal phase change nanofiber or a core-shell structured passive radiative cooling nanofiber.

[0069] Preferably, in step 3, the nanofiber-coated yarn 11 for personal thermal management is a photothermal phase change nanofiber-coated yarn or a passive radiative cooling nanofiber-coated yarn.

[0070] Example 1:

[0071] (1) Prepare the core layer spinning solution and the shell layer spinning solution;

[0072] Heat the n-octadecane crystals at 45 °C for 0.5 h to obtain the core layer spinning solution;

[0073] Dissolve PAN in DMF, heat at 60 °C, stir at 1000 rpm for 8 h until completely dissolved to obtain the PAN solution; then add the centrifugally expanded MXene to the PAN solution, first stir at a speed of 1000 rpm for 1.5 h, and then ultrasonically treat at 100 Hz / min for 1.5 h to make it evenly dispersed to obtain the PAN-MXene suspension as the shell layer spinning solution; the mass fraction of PAN in the shell layer spinning solution is 13%, and the mass fraction of MXene is 3%;

[0074] (2) Set up a coaxial conjugate electrospinning device: Wind the cotton yarn as the core yarn 7 around the unwinding roller 8, and pass the core yarn 7 through the center of the metal rotary funnel 9 and fix it on the collecting device 12 in the electrostatic field area;

[0075] (3) Prepare the nanofiber-coated yarn 11 for personal thermal management;

[0076] The distance between the two coaxial needles 3 is 18 cm; the distance between the coaxial needle 3 and the metal rotary funnel 9 is 13 cm; the voltage of the positive electrode 4 is 6 kV, and the voltage of the negative electrode 5 is -6 kV; the feeding rate of the shell layer spinning solution is 0.6 mL / h, and the feeding rate of the core layer spinning solution is 0.15 mL / h; the moving speed of the core yarn 7 is 0.2 mm / s; the rotation speed of the metal rotary funnel 9 is 350 rpm; the spinning environment temperature is 25 ± 5 °C, and the humidity is 40 ± 5%;

[0077] The core-spinning solution and the sheath-spinning solution are respectively transported to the core channel 302 and the sheath channel 301 of the coaxial needle 3; the DC power supply is turned on to start spinning. During the spinning process, the core yarn 7 is in a straight state; under the action of the high-voltage electric field, the spinning solutions in the two coaxial needles 3 are stretched into fibrous shapes in the electric field, respectively forming core-shell structured photothermal phase change nanofibers; the core-shell structured photothermal phase change nanofibers are collected on the metal rotary funnel 9; a triangular fiber web 10 formed by a fiber bundle of multiple core-shell structured photothermal phase change nanofibers is formed at the opening of the metal rotary funnel 9; the rotation of the metal rotary funnel 9 causes the fiber bundle to be evenly entangled and coated on the outer surface of the core yarn 7 to form an outer coating layer, and finally a primary coated yarn with the core yarn 7 as the core layer and the outer coating layer as the skin layer is formed on the collecting device 12; then the primary coated yarn is dried at room temperature for 4 h until the solvent completely volatilizes, obtaining a photothermal phase change nanofiber coated yarn with an average diameter of 500 μm, wherein the mass ratio of the core-shell structured nanofibers 6 to the core yarn 7 is 0.4:1.

[0078] It can be seen from Figure 3 and Figure 4 that the structural morphology of the photothermal phase change nanofiber coated yarn prepared in Example 1 is good.

[0079] It can be seen from Figure 5 and Figure 6 that the photothermal phase change nanofibers prepared in Example 1 are evenly entangled and coated on the core yarn 7.

[0080] It can be seen from Figure 7 that the photothermal phase change nanofiber coated yarn prepared in Example 1 has good photothermal conversion effect.

[0081] It can be seen from Figure 8 that the photothermal phase change nanofiber coated yarn prepared in Example 1 has good heat storage and temperature regulation performance.

[0082] Example 2:

[0083] (1) Prepare the core-spinning solution and the sheath-spinning solution;

[0084] The n-tetradecane crystals are heated at 45 °C for 1 h to obtain the core-spinning solution;

[0085] PAN is dissolved in DMF, heated at 60 °C, and stirred at 1000 rpm for 8 h until completely dissolved to obtain a PAN solution; then the graphene after dispersion treatment is added to the PAN solution, first stirred at a speed of 1000 rpm for 1.5 h, and then ultrasonically treated at 100 Hz / min for 1.5 h to make it evenly dispersed, obtaining a PAN-graphene suspension as the sheath-spinning solution; the mass fraction of PAN in the sheath-spinning solution is 13%, and the mass fraction of graphene is 3%;

[0086] (2) Set up a coaxial conjugate electrospinning device: Wind the polyester yarn as the core yarn 7 around the unwinding roller 8, and pass the core yarn 7 through the center of the metal rotary funnel 9 and fix it on the collecting device 12 through the electrostatic field area;

[0087] (3) Prepare the nanofiber-coated yarn 11 for personal thermal management;

[0088] The distance between the two coaxial needles 3 is 18 cm; the distance between the coaxial needle 3 and the metal rotary funnel 9 is 13 cm; the voltage of the positive electrode 4 is 6 kV, and the voltage of the negative electrode 5 is -6 kV; the feeding rate of the shell layer spinning solution is 0.6 mL / h, and the feeding rate of the core layer spinning solution is 0.15 mL / h; the moving speed of the core yarn 7 is 0.2 mm / s; the rotation speed of the metal rotary funnel 9 is 350 rpm; the spinning environment temperature is 25 ± 5 °C, and the humidity is 40 ± 5%;

[0089] Feed the shell layer spinning solution and the core layer spinning solution into the shell layer channel 301 and the core layer channel 302 of the coaxial needle 3 respectively; turn on the DC power supply and start spinning. During the spinning process, the core yarn 7 is in a straight state; under the action of the high-voltage electric field, the spinning solutions in the two coaxial needles 3 are stretched into fibrous shapes in the electric field, respectively forming core-shell structured photothermal phase change nanofibers; collect the core-shell structured photothermal phase change nanofibers on the metal rotary funnel 9; a triangular fiber web 10 formed by a fiber bundle of multiple core-shell structured photothermal phase change nanofibers is formed at the opening of the metal rotary funnel 9; the rotation of the metal rotary funnel 9 causes the fiber bundle to be evenly entangled and coated on the outer surface of the core yarn 7 to form an outer coating, and finally a primary coated yarn with the core yarn 7 as the core layer and the outer coating as the cortex is formed on the collecting device 12; then dry the primary coated yarn at room temperature for 5 h until the solvent completely volatilizes, and obtain a photothermal phase change nanofiber-coated yarn with an average diameter of 450 μm, where the mass ratio of the core-shell structured nanofibers 6 to the core yarn 7 is 0.4:1.

[0090] Example 3:

[0091] (1) Prepare the core layer spinning solution and the shell layer spinning solution;

[0092] Heat the paraffin crystals at 45 °C for 0.5 h to obtain the core layer spinning solution;

[0093] Dissolve PVDF in a mixed solvent with a mass ratio of DMF to acetone of 7:3, heat at 60 °C, stir at 1000 rpm for 8 h until completely dissolved to obtain a PVDF solution; then add the centrifugally expanded MXene to the PVDF solution, first stir at a speed of 1000 rpm for 1.5 h, and then ultrasonically treat at 100 Hz / min for 1.5 h to make it evenly dispersed to obtain a PVDF-MXene suspension as the shell layer spinning solution; the mass fraction of PVDF in the shell layer spinning solution is 12%, and the mass fraction of MXene is 3%;

[0094] (2) Set up a coaxial conjugate electrospinning device: Wind the polyamide yarn as the core yarn 7 around the unwinding roller 8, and pass the core yarn 7 through the center of the metal rotary funnel 9 and fix it on the collecting device 12 through the electrostatic field area;

[0095] (3) Prepare the nanofiber-coated yarn 11 for personal thermal management;

[0096] The distance between the two coaxial needles 3 is 18 cm; the distance between the coaxial needle 3 and the metal rotary funnel 9 is 13 cm; the voltage of the positive electrode 4 is 6 kV, and the voltage of the negative electrode 5 is -6 kV; the feeding rate of the shell layer spinning solution is 0.6 mL / h, and the feeding rate of the core layer spinning solution is 0.15 mL / h; the moving speed of the core yarn 7 is 0.2 mm / s; the rotation speed of the metal rotary funnel 9 is 350 rpm; the spinning environment temperature is 25 ± 5 °C, and the humidity is 40 ± 5%;

[0097] Feed the shell layer spinning solution and the core layer spinning solution into the shell layer channel 301 and the core layer channel 302 of the coaxial needle 3 respectively; turn on the DC power supply and start spinning. During the spinning process, the core yarn 7 is in a straight state; under the action of the high-voltage electric field, the spinning solutions in the two coaxial needles 3 are stretched into fibrous shapes in the electric field, respectively forming core-shell structured photothermal phase change nanofibers; collect the core-shell structured photothermal phase change nanofibers on the metal rotary funnel 9; a triangular fiber web 10 formed by a fiber bundle of multiple core-shell structured photothermal phase change nanofibers is formed at the opening of the metal rotary funnel 9; the rotation of the metal rotary funnel 9 causes the fiber bundles to be evenly entangled and coated on the outer surface of the core yarn 7 to form an outer coating, and finally a primary coated yarn with the core yarn 7 as the core layer and the outer coating as the cortex is formed on the collecting device 12; then dry the primary coated yarn at room temperature for 4 h until the solvent completely volatilizes, and obtain a photothermal phase change nanofiber-coated yarn with an average diameter of 450 μm, where the mass ratio of the core-shell structured nanofibers 6 to the core yarn 7 is 0.3:1.

[0098] Example 4:

[0099] (1) Prepare the core layer spinning solution and the shell layer spinning solution;

[0100] Heat the polyethylene glycol crystal at 45 °C for 1 h to obtain the core layer spinning solution;

[0101] Dissolve PVDF in a mixed solvent with a mass ratio of DMF to acetone of 7:3, heat it at 60 °C, stir at 1000 rpm for 8 h until completely dissolved to obtain a PVDF solution; add the centrifugally dispersed graphene to the PVDF solution, first stir at a speed of 1000 rpm for 1.5 h, and then ultrasonically treat it at 100 Hz / min for 1.5 h to make it evenly dispersed, obtaining a PVDF-graphene suspension as the shell spinning solution; the mass fraction of PVDF in the shell spinning solution is 12%, and the mass fraction of graphene is 3%.

[0102] (2) Set up a coaxial conjugate electrospinning device: Use polyester-cotton yarn as the core yarn 7 and wind it around the unwinding roller 8, pass the core yarn 7 through the center of the metal rotating funnel 9 and fix it on the collecting device 12 in the electrostatic field area;

[0103] (3) Prepare the nanofiber-coated yarn 11 for personal thermal management;

[0104] The distance between the two coaxial needles 3 is 18 cm; the distance between the coaxial needle 3 and the metal rotating funnel 9 is 13 cm; the voltage of the positive electrode 4 is 6 kV, and the voltage of the negative electrode 5 is -6 kV; the feeding rate of the shell spinning solution is 0.6 mL / h, and the feeding rate of the core spinning solution is 0.15 mL / h; the moving speed of the core yarn 7 is 0.2 mm / s; the rotation speed of the metal rotating funnel 9 is 350 rpm; the spinning environment temperature is 25 ± 5 °C, and the humidity is 40 ± 5%;

[0105] Feed the shell spinning solution and the core spinning solution into the shell channel 301 and the core channel 302 of the coaxial needle 3 respectively; turn on the DC power supply and start spinning. During the spinning process, the core yarn 7 is in a straight state; under the action of the high-voltage electric field, the spinning solutions in the two coaxial needles 3 are stretched into fibrous shapes in the electric field, respectively forming core-shell structured photothermal phase change nanofibers; collect the core-shell structured photothermal phase change nanofibers on the metal rotating funnel 9; a triangular fiber mesh 10 formed by a fiber bundle of multiple core-shell structured photothermal phase change nanofibers is formed at the opening of the metal rotating funnel 9; the rotation of the metal rotating funnel 9 makes the fiber bundle evenly entangle and coat on the outer surface of the core yarn 7 to form an outer coating, and finally a primary coated yarn with the core yarn 7 as the core layer and the outer coating as the skin layer is formed on the collecting device 12; then dry the primary coated yarn at room temperature for 4 h until the solvent completely volatilizes, obtaining a photothermal phase change nanofiber-coated yarn with an average diameter of 500 μm, where the mass ratio of the core-shell structured nanofibers 6 to the core yarn 7 is 0.3:1.

[0106] Table 1

[0107]

[0108]

[0109] Table 1 shows the heat storage and temperature regulation performance of the photothermal phase change nanofiber-coated yarn. It can be seen from Table 1 that the photothermal phase change nanofiber-coated yarn of the present invention has good effects in thermal management.

[0110] Example 5:

[0111] (1) Prepare the core layer spinning solution and the shell layer spinning solution;

[0112] Heat the n-octadecane crystals at 45°C for 0.5 h to obtain the core layer spinning solution

[0113] Dissolve PVDF in a mixed solvent with a mass ratio of DMF to acetone of 7:3, heat at 60°C, stir at 1000 rpm for 8 h until completely dissolved to obtain a PVDF solution; then add SiO2 to the PVDF solution in small amounts and multiple times. First, stir at a speed of 1000 rpm for 1.5 h, and then ultrasonically treat at 100 Hz / min for 1.5 h to obtain a PVDF-SiO2 suspension as the shell layer spinning solution; the mass fraction of PVDF in the shell layer spinning solution is 10%, and the mass fraction of SiO2 is 5%;

[0114] (2) Set up a coaxial conjugate electrospinning device: Use cotton yarn as the core yarn 7 and wind it around the unwinding roller 8. Pass the core yarn 7 through the center of the metal rotary funnel 9 and fix it on the collecting device 12 in the electrostatic field area;

[0115] (3) Prepare the nanofiber-coated yarn 11 for personal thermal management;

[0116] The distance between the two coaxial needles 3 is 18 cm; the distance between the coaxial needle 3 and the metal rotary funnel 9 is 13 cm; the voltage of the positive electrode 4 is 6 kV, and the voltage of the negative electrode 5 is -6 kV; the feeding rate of the shell layer spinning solution is 0.6 mL / h, and the feeding rate of the core layer spinning solution is 0.15 mL / h; the moving speed of the core yarn 7 is 0.2 mm / s; the rotation speed of the metal rotary funnel 9 is 350 rpm; the spinning environment temperature is 25 ± 5°C, and the humidity is 40 ± 5%;

[0117] The shell spinning solution and the core spinning solution are respectively transported to the shell channel 301 and the core channel 302 of the coaxial needle 3; the DC power supply is turned on to start spinning. During the spinning process, the core yarn 7 is in a straight state; under the action of the high-voltage electric field, the spinning solutions in the two coaxial needles 3 are stretched into fibrous shapes in the electric field, respectively forming core-shell structured passive radiative cooling nanofibers; the core-shell structured passive radiative cooling nanofibers are collected on the metal rotary funnel 9; a triangular fiber web 10 formed by a fiber bundle of multiple core-shell structured passive radiative cooling nanofibers is formed at the opening of the metal rotary funnel 9; the rotation of the metal rotary funnel 9 causes the fiber bundles to be evenly entangled and coated on the outer surface of the core yarn 7 to form an outer coating layer, and finally a primary coated yarn with the core yarn 7 as the core layer and the outer coating layer as the skin layer is formed on the collecting device 12; then the primary coated yarn is dried at room temperature for 4 h until the solvent completely volatilizes, and a passive radiative cooling nanofiber coated yarn with an average diameter of 400 μm is obtained, where the mass ratio of the core-shell structured nanofibers 6 to the core yarn 7 is 0.3:1.

[0118] It can be seen from Figure 9 and Figure 10 that the prepared passive radiative cooling nanofiber coated yarn has a good morphological structure.

[0119] It can be seen from Figure 11 that the prepared passive radiative cooling nanofiber coated yarn has a good heat storage effect.

[0120] It can be seen from Figure 12 that the prepared passive radiative cooling nanofiber coated yarn has a good cooling effect.

[0121] Example 6:

[0122] (1) Prepare the core spinning solution and the shell spinning solution;

[0123] Heat the n-tetradecane crystals at 45 °C for 1 h to obtain the core spinning solution;

[0124] Dissolve PVDF in a mixed solvent with a mass ratio of DMF to acetone of 7:3, heat at 60 °C, stir at 1000 rpm for 8 h until completely dissolved to obtain a PVDF solution; then add ZnO to the PVDF solution in small amounts and multiple times, first stir at a speed of 1000 rpm for 1.5 h, and then ultrasonically treat at 100 Hz / min for 1.5 h to obtain a PVDF-ZnO suspension as the shell spinning solution; the mass fraction of PVDF in the shell spinning solution is 10%, and the mass fraction of ZnO is 5%;

[0125] (2) Set up a coaxial conjugate electrospinning device: Wind the polyester yarn as the core yarn 7 on the unwinding roller 8, pass the core yarn 7 through the center of the metal rotary funnel 9 and fix it on the collecting device 12 through the electrostatic field area;

[0126] (3) Prepare the nanofiber-coated yarn 11 for personal thermal management;

[0127] The distance between the two coaxial needles 3 is 18 cm; the distance between the coaxial needle 3 and the metal rotating funnel 9 is 13 cm; the voltage of the positive electrode 4 is 6 kV, and the voltage of the negative electrode 5 is -6 kV; the propulsion rate of the shell spinning solution is 0.6 mL / h, and the propulsion rate of the core spinning solution is 0.15 mL / h; the moving speed of the core yarn 7 is 0.2 mm / s; the rotation speed of the metal rotating funnel 9 is 350 rpm; the spinning environment temperature is 25 ± 5 °C, and the humidity is 40 ± 5%;

[0128] Feed the shell spinning solution and the core spinning solution into the shell channel 301 and the core channel 302 of the coaxial needle 3 respectively; turn on the DC power supply and start spinning. During the spinning process, the core yarn 7 is in a straight state; under the action of the high-voltage electric field, the spinning solutions in the two coaxial needles 3 are stretched into fibrous shapes in the electric field, respectively forming core-shell structured passive radiative cooling nanofibers; collect the core-shell structured passive radiative cooling nanofibers on the metal rotating funnel 9; form a triangular fiber web 10 composed of fiber bundles of multiple core-shell structured passive radiative cooling nanofibers at the opening of the metal rotating funnel 9; the rotation of the metal rotating funnel 9 makes the fiber bundles evenly tangle and wrap around the outer surface of the core yarn 7 to form an outer coating, and finally form a primary coated yarn with the core yarn 7 as the core layer and the outer coating as the cortex layer on the collecting device 12; then dry the primary coated yarn at room temperature for 5 h until the solvent completely volatilizes, and obtain a passive radiative cooling nanofiber-coated yarn with an average diameter of 400 μm, where the mass ratio of the core-shell structured nanofibers 6 to the core yarn 7 is 0.2:1.

[0129] Example 7:

[0130] (1) Prepare the core spinning solution and the shell spinning solution;

[0131] Heat the paraffin crystals at 45 °C for 0.5 h to obtain the core spinning solution

[0132] Dissolve PAN in DMF, heat at 60 °C, stir at 1000 rpm for 8 h until completely dissolved to obtain a PAN solution; then add TiO2 to the PAN solution in small amounts and multiple times. First, stir at a rotation speed of 1000 rpm for 1.5 h, and then ultrasonically treat at 100 Hz / min for 1.5 h to obtain a PAN-TiO2 suspension as the shell spinning solution; the mass fraction of PAN in the shell spinning solution is 13%, and the mass fraction of TiO2 is 5%;

[0133] (2) Set up the coaxial conjugate electrospinning device: Wind the polyamide yarn as the core yarn 7 around the unwinding roller 8, and pass the core yarn 7 through the center of the metal rotating funnel 9 and fix it on the collecting device 12 through the electrostatic field area;

[0134] (3) Prepare the nanofiber-coated yarn 11 for personal thermal management;

[0135] The distance between the two coaxial needles 3 is 18 cm; the distance between the coaxial needle 3 and the metal rotary funnel 9 is 13 cm; the voltage of the positive electrode 4 is 6 kV, and the voltage of the negative electrode 5 is -6 kV; the propulsion rate of the shell spinning solution is 0.6 mL / h, and the propulsion rate of the core spinning solution is 0.15 mL / h; the moving speed of the core yarn 7 is 0.2 mm / s; the rotation speed of the metal rotary funnel 9 is 350 rpm; the spinning environment temperature is 25 ± 5 °C, and the humidity is 40 ± 5%;

[0136] Feed the shell spinning solution and the core spinning solution into the shell channel 301 and the core channel 302 of the coaxial needle 3 respectively; turn on the DC power supply and start spinning. During the spinning process, the core yarn 7 is in a straight state; under the action of the high-voltage electric field, the spinning solutions in the two coaxial needles 3 are stretched into fibrous shapes in the electric field, respectively forming core-shell structured passive radiative cooling nanofibers; collect the core-shell structured passive radiative cooling nanofibers on the metal rotary funnel 9; form a triangular fiber web 10 formed by a fiber bundle of multiple core-shell structured passive radiative cooling nanofibers at the opening of the metal rotary funnel 9; the rotation of the metal rotary funnel 9 causes the fiber bundle to be evenly entangled and coated on the outer surface of the core yarn 7 to form an outer coating, and finally form a primary coated yarn with the core yarn 7 as the core layer and the outer coating as the skin layer on the collecting device 12; then dry the primary coated yarn at room temperature for 4 h until all the solvent evaporates, and obtain a passive radiative cooling nanofiber-coated yarn with an average diameter of 500 μm, where the mass ratio of the core-shell structured nanofibers 6 to the core yarn 7 is 0.4:1.

[0137] Example 8:

[0138] (1) Prepare the core spinning solution and the shell spinning solution;

[0139] Heat the polyethylene glycol crystal at 45 °C for 1 h to obtain the core spinning solution;

[0140] Dissolve PAN in DMF, heat it at 60 °C, and stir at 1000 rpm for 8 h until completely dissolved to obtain a PAN solution; then add BaSO4 to the PAN solution in small amounts and multiple times. First, stir at a speed of 1000 rpm for 1.5 h, and then ultrasonically treat it at 100 Hz / min for 1.5 h to make it evenly dispersed, and obtain a PAN-BaSO4 suspension as the shell spinning solution; the mass fraction of PAN in the shell spinning solution is 13%, and the mass fraction of BaSO4 is 3%;

[0141] (2) Set up the coaxial conjugate electrospinning device: Wind the polyester-cotton yarn as the core yarn 7 on the unwinding roller 8, and pass the core yarn 7 through the center of the metal rotary funnel 9 and fix it on the collecting device 12 through the electrostatic field area;

[0142] (3) Prepare the nanofiber-coated yarn 11 for personal thermal management;

[0143] The distance between the two coaxial needles 3 is 18 cm; the distance between the coaxial needle 3 and the metal rotary funnel 9 is 13 cm; the voltage of the positive electrode 4 is 6 kV, and the voltage of the negative electrode 5 is -6 kV; the propulsion rate of the shell spinning solution is 0.6 mL / h, and the propulsion rate of the core spinning solution is 0.15 mL / h; the moving speed of the core yarn 7 is 0.2 mm / s; the rotation speed of the metal rotary funnel 9 is 350 rpm; the spinning environment temperature is 25 ± 5 °C, and the humidity is 40 ± 5%;

[0144] Feed the shell spinning solution and the core spinning solution into the shell channel 301 and the core channel 302 of the coaxial needle 3 respectively; turn on the DC power supply and start spinning. During the spinning process, the core yarn 7 is in a straight state; under the action of the high-voltage electric field, the spinning solutions in the two coaxial needles 3 are stretched into fibrous shapes in the electric field, respectively forming core-shell structured passive radiative cooling nanofibers; collect the core-shell structured passive radiative cooling nanofibers on the metal rotary funnel 9; a triangular fiber web 10 formed by a fiber bundle of multiple core-shell structured passive radiative cooling nanofibers is formed at the opening of the metal rotary funnel 9; the rotation of the metal rotary funnel 9 causes the fiber bundles to be evenly entangled and coated on the outer surface of the core yarn 7 to form an outer coating, and finally a primary coated yarn with the core yarn 7 as the core layer and the outer coating as the skin layer is formed on the collecting device 12; then dry the primary coated yarn at room temperature for 5 h until all the solvents evaporate, and obtain a passive radiative cooling nanofiber-coated yarn with an average diameter of 450 μm, where the mass ratio of the core-shell structured nanofibers 6 to the core yarn 7 is 0.3:1.

[0145] Table 2

[0146]

[0147]

[0148] Table 2 shows the heat storage and temperature regulation performance of the passive radiative cooling nanofiber-coated yarn. It can be seen from Table 2 that the passive radiative cooling nanofiber-coated yarn of the present invention has a good effect in thermal management.

[0149] Matters not described in the present invention are applicable to the prior art.

Claims

1. A method for preparing nanofiber coated yarn for personal thermal management by coaxial conjugate electrospinning, characterized in that: The method comprises the following steps: Step 1, preparing a core layer spinning solution and a shell layer spinning solution; The phase change material is heated and melted into a liquid state to obtain a core layer spinning solution; The polymer is dissolved in an organic solvent to obtain a polymer solution; a temperature regulating functional material is added to the polymer solution and dispersed evenly to obtain a shell spinning solution; the temperature regulating functional material is one of a photothermal material or a radiation refrigeration material; Step 2, building a coaxial conjugate electrospinning device; The device comprises a shell layer spinning solution propeller (1), a core layer spinning solution propeller (2), a coaxial needle (3), a positive electrode (4), a negative electrode (5), an unwinding roller (8), a metal rotating funnel (9) and a collecting device (12); The coaxial needle (3) is a coaxial structure having a core layer channel (302) and a shell layer channel (301), wherein the shell layer channel (301) is nested on the outside of the core layer channel (302); the shell layer spinning solution propeller (1) and the core layer spinning solution propeller (2) are both mounted on the coaxial needle (3); the shell layer spinning solution propeller (1) is connected to the shell layer channel (301), and pushes the shell layer spinning solution into the shell layer channel (301) during spinning; the core layer spinning solution propeller (2) is connected to the core layer channel (302), and pushes the core layer spinning solution into the core layer channel (302) during spinning; An unwinding roller (8), a metal rotating funnel (9) and a collecting device (12) are sequentially arranged along the forward direction of the core yarn (7); the core yarn (7) is wound on the unwinding roller (8) and the core yarn (7) is released during spinning; the collecting device (12) is used to collect the nanofiber coated yarn (11) for personal thermal management and control the moving speed of the core yarn (7); The two coaxial needles (3) are located on the same horizontal plane; the metal rotating funnel (9) is at the same distance from the two coaxial needles (3), is located on the mid-vertical plane between the two coaxial needles (3), and is within the range of the electrostatic field generated by the coaxial needles (3) when high voltage is applied; one of the two coaxial needles (3) is connected to the positive electrode (4) of the power supply, and the other is connected to the negative electrode (5) of the power supply, so as to generate an electrostatic field; the metal rotating funnel (9) can rotate along its own central axis; Step 3, preparing nanofiber coated yarn (11) for personal thermal management; Setting spinning parameters; placing the shell layer spinning solution in a shell layer spinning solution propeller (1), and placing the core layer spinning solution in a core layer spinning solution propeller (2); one end of the core yarn (7) is wound around an unwinding roller (8), passes through a metal rotating funnel (9), and the other end is wound around a collecting device (12), and the core yarn (7) is pulled and moved by the collecting device (12); Coaxial conjugate electrospinning is started to achieve that the core-shell structured nanofibers (6) with a core layer of phase change material and a shell layer of polymer and temperature regulating functional material are uniformly coated on the outside of the core yarn (7), thereby forming a primary coated yarn with the core yarn (7) as the core layer and the core-shell structured nanofibers (6) as the skin layer; the primary coated yarn is then dried until the solvent is completely volatilized, thereby obtaining a nanofiber coated yarn (11) for personal thermal management.

2. The method for preparing nanofiber coated yarn for personal thermal management by coaxial conjugate electrospinning according to claim 1, characterized in that: In step 1, the phase change material is one of n-octadecane, n-tetradecane, polyethylene glycol or paraffin; In step 1, the phase change material heating process is: heating at 40-50° C. for 0.5-1 h.

3. The method for preparing nanofiber coated yarn for personal thermal management by coaxial conjugate electrospinning according to claim 1, characterized in that: In step 1, the polymer is PAN or PVDF; the organic solvent is DMF and / or acetone; In step 1, the polymer dissolution process is: stirring at 60-70° C. and 1000-2000 rpm for 6-10 hours.

4. The method for preparing nanofiber coated yarn for personal thermal management by coaxial conjugate electrospinning according to claim 1, characterized in that: In step 1, the photothermal material is Mxene or graphene; the radiation cooling material is one or more of TiO2, SiO2, BaSO4 or ZnO; the particle size of the radiation cooling material is 80 to 1600 nm; In step 1, the temperature regulating functional material dispersion process is: first stirring at a speed of 1000-2000 rpm for 1-2 hours, and then ultrasonic treatment at 80-120 Hz / min for 1-2 hours; In step 1, in the shell spinning solution, the mass fraction of the polymer is 10-15%; the mass fraction of the photothermal material is 1-5%; and the mass fraction of the radiation refrigeration material is 2-8%.

5. The method for preparing nanofiber coated yarn for personal thermal management by coaxial conjugate electrospinning according to claim 1, characterized in that: In step 2, a hole is opened on the outer wall of the coaxial needle (3), and the shell spinning liquid propeller (1) is fixed to the hole on the outer wall of the coaxial needle (3) and is connected to the side wall of the shell channel (301).

6. The method for preparing nanofiber coated yarn for personal thermal management by coaxial conjugate electrospinning according to claim 1, characterized in that: In step 2, the core yarn (7) is yarn; and the metal rotating funnel (9) is a bell-mouth type.

7. The method for preparing nanofiber coated yarn for personal thermal management by coaxial conjugate electrospinning according to claim 1, characterized in that: In step 3, the specific process of coaxial conjugate electrospinning is as follows: turn on the power supply to start spinning, and during the spinning process, the core yarn (7) is in a straight state; under the action of the high-voltage electric field, the spinning solution in the two coaxial needles (3) is stretched into fibers in the electric field to form core-shell structure nanofibers (6) respectively; the difference in positive and negative charges causes the core-shell structure nanofibers (6) spun by the two coaxial needles (3) to entangle with each other, and at the same time, electrostatic induction is generated between the two coaxial needles (3) and the metal rotating funnel (9), so that the core-shell structure nanofibers (6) are collected on the metal rotating funnel (9); Through the pulling effect of the core yarn (7) on the electrospun fibers, a triangular pyramidal fiber net (10) formed by fiber bundles of multiple bundles of core-shell structured nanofibers (6) is formed at the opening of the metal rotating funnel (9); the core yarn (7) is stretched and pulled by the collecting device (12), so that the fiber bundles in the fiber net (10) have orientation; at the same time, the rotation of the metal rotating funnel (9) causes the fiber bundles to be evenly entangled and coated on the outer surface of the core yarn (7) to form an outer cladding, and finally a primary coated yarn with the core yarn (7) as the core layer and the outer cladding as the skin layer is formed on the collecting device (12).

8. The method for preparing nanofiber coated yarn for personal thermal management by coaxial conjugate electrospinning according to claim 1, characterized in that: In step 3, the spinning parameters are as follows: the distance between the two coaxial needles (3) is 15 to 20 cm; the distance between the coaxial needles (3) and the metal rotating funnel (9) is 12 to 15 cm; the voltage of the positive electrode (4) is 5 to 7 kV, and the voltage of the negative electrode (5) is -7 to -5 kV; the propulsion rate of the shell layer spinning solution is 0.4 to 0.7 mL / h, and the propulsion rate of the core layer spinning solution is 0.1 to 0.2 mL / h; the moving speed of the core yarn (7) is adjusted by adjusting the rotation speed of the collecting device (12) so that the collecting speed is adapted to the spinning speed, and the moving speed of the core yarn (7) is 0.1 to 0.4 mm / s; the rotation speed of the metal rotating funnel (9) is 300 to 500 rpm; the spinning environment temperature is 25±5°C, and the humidity is 40±5%.

9. The method for preparing nanofiber coated yarn for personal thermal management by coaxial conjugate electrospinning according to claim 1, characterized in that: In step 3, the mass ratio of the core-shell structure nanofiber (6) to the core yarn (7) is 0.2-0.5:1; In step 3, the average diameter of the nanofiber coated yarn (11) for personal thermal management is 380-600 μm.

10. The method for preparing nanofiber coated yarn for personal thermal management by coaxial conjugate electrospinning according to claim 1, characterized in that: In step 3, the drying process is: drying in an indoor environment for at least 4 hours.

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