Process for the preparation of polar bear-like hair polyurethane aerogel fibers

Abstract

The application belongs to the field of thermal management fibers and textile applications, and particularly relates to a preparation method of polar bear-like hair polyurethane aerogel fibers (polyurethane aerogel fibers with hierarchical pores in core-sheath structure), which comprises the following steps: SiO2 aerogel preparation; preparing a coating liquid by using SiO2 aerogel, a surfactant and water-based polyurethane; preparation of homogeneous porous polyurethane fibers; taking the homogeneous porous polyurethane fibers as a core layer and the coating liquid as a shell layer, and through a continuous dip-coating process, the homogeneous porous polyurethane fibers are provided with the shell layer on the outer surface, and then drying and cooling are performed to obtain polar bear-like hair polyurethane aerogel fibers with high mechanical properties (high elasticity) and high thermal insulation performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of thermal management fibers and textile applications, and particularly relates to a preparation method of polar bear-like hair polyurethane aerogel fibers (polyurethane aerogel fibers with hierarchical porosity in core-sheath structure). BACKGROUND

[0002] Aerogels have ultralow density, high porosity, and low thermal conductivity, which endow them with ultrahigh thermal insulation performance, and are one of the most recognized optimal thermal insulation materials. However, the structural defects of high porosity to mechanical properties result in poor mechanical properties, and most of them exist in the form of powder and particles, which limits their application prospects. In the field of textiles, aerogels are applied to fabrics through filling and coating, but the dense coating will affect the air permeability and comfort of the fabric (the coating will seal the pores between the fibers in the whole fabric), and the filling will cause partial powder leakage, so the application of aerogels in thermal management textiles is greatly limited, and therefore a new form of aerogel needs to be explored for application in textiles.

[0003] Aerogel fibers are high-performance fiber materials that combine three-dimensional porous network structure and one-dimensional fibers. They can be woven and knitted into textile fabrics, providing a new direction for the development of thermal management textiles, and have potential applications in functional textiles and thermal management wearable devices.

[0004] The invention of CN113718369A "Method for constructing ultralight polyurethane aerogel fibers by polymer nanofibers" discloses that by adding polymer nanofibers to the polyurethane solution, the fiber coagulation and molding process in the wet spinning process is controlled, and after freeze-drying, an ultralight, high-elastic, porous polyurethane aerogel fiber is obtained. By adding polymer nanofibers, a uniform and dense porous structure is formed inside the polyurethane aerogel fiber, which can retain air in the internal cavity, contain a large amount of static air, and have a small air exchange with the outside air, so that the resulting textile has better warmth-keeping effect and can be applied to personal thermal management to reduce energy waste.

[0005] Therefore, it is a key problem to be solved at the present stage to develop a green and environmentally friendly, low-cost, and simple aerogel fiber preparation technology, and to obtain an aerogel fiber product with high thermal insulation performance and high mechanical properties. SUMMARY

[0006] The technical problem to be solved by the present application is to provide a method for constructing polar bear-like hair polyurethane aerogel fibers using a dip coating process, which is green and environmentally friendly, low in cost, and simple in process.

[0007] To solve the above technical problems, the present application provides a preparation method of polar bear-like hair polyurethane aerogel fibers, comprising the following steps:

[0008] S1, SiO2 aerogel preparation:

[0009] SiO2 aerogel (powdery SiO2 aerogel) is prepared by using silica sol;

[0010] S2, coating liquid preparation:

[0011] The coating liquid is composed of SiO2 aerogel with a content of 0.1-5wt% (preferably 0.5-2.5wt%), surfactant with a content of 0.1-2wt% (preferably 0.2-0.6wt%), and water-based polyurethane as the balance;

[0012] Specifically, the SiO2 aerogel, surfactant and water-based polyurethane obtained in step S1 are mixed and uniformly dispersed (cell crushing and ultrasonic treatment can be used), to obtain the coating liquid;

[0013] S3, preparation of porous (homogeneous porous) polyurethane fiber:

[0014] The polyurethane primary particles are dissolved in an organic solvent to obtain a polyurethane solution with a mass fraction of 19%-21% (preferably 20%);

[0015] A non-solvent composed of ethanol and water is used as the mixed coagulation bath, and the weight content of ethanol in the non-solvent is 58-62% (preferably 60%);

[0016] The polyurethane solution is injected into the mixed coagulation bath by a micro-pump, and after the phase separation (phase separation of the solvent in the polyurethane solution and the non-solvent) is completed, the porous (homogeneous porous) polyurethane fiber is prepared by normal pressure drying; the temperature of the mixed coagulation bath is 60-70°C (preferably 65°C);

[0017] S4, dip coating process:

[0018] The porous (homogeneous porous) polyurethane fiber obtained in step S3 is used as the core layer, and the coating liquid obtained in step S2 is used as the shell layer, so that the outer surface of the porous (homogeneous porous) polyurethane fiber has a shell layer, and then dried and cooled to prepare the polar bear-like hair polyurethane aerogel fiber.

[0019] As an improvement of the preparation method of the polar bear-like hair polyurethane aerogel fiber of the present application, the step S1 is:

[0020] Tetraethyl orthosilicate is hydrolyzed into silica sol under acidic conditions, the silica sol is condensed into a gel under alkaline conditions, the gel is aged (two-step aging), and then the aged gel is hydrophobically modified by a hydrophobic reagent, and then normal pressure drying is performed to prepare the SiO2 aerogel (powdery SiO2 aerogel).

[0021] As a further improvement of the preparation method of the polar bear-like hair polyurethane aerogel fiber of the present application, the step S1 is to sequentially perform the following steps:

[0022] 1.1), hydrolysis: mixing in a molar ratio of tetraethyl orthosilicate: ethanol: HCl (10 -2 mol / L) = 1:3:1.5, and reacting at 80±10℃ for 6±0.5h to obtain a silica sol solution; the HCl is a 10 -2 mol / L HCl solution;

[0023] 1.2), condensation: mixing 5ml of the silica sol solution with 5±0.5ml of ethanol, and then adding 0.5±0.05ml of 0.6M ammonia water solution to coagulate into a block-shaped gel;

[0024] 1.3), gel aging (divided into two-step aging): first placing the block-shaped gel into a 50±5℃ aging solution, soaking and aging at (50±5℃) for 0.1-2h (preferably 0.2-1.5h), and then taking it out for crushing (to about 1.3-1.7 microns), and then placing the crushed gel particles back into the aging solution, heating to 80±5℃, and soaking and aging at (80±5℃) for 0.2-1.9h (preferably 0.6-1.8h);

[0025] The aging solution is tetraethyl orthosilicate / ethanol = 1:2 in volume ratio;

[0026] Note: the amount of the aging solution only needs to ensure that the block-shaped gel is always immersed, and generally 20±5ml is used for the block-shaped gel obtained from 5ml of the silica sol solution;

[0027] 1.4), hydrophobic modification: adding the aged gel particles into a modification solution obtained by mixing trimethylchlorosilane and n-hexane in a volume ratio of 1:4 to perform hydrophobic modification for 40±5 minutes, to obtain a slurry containing hydrophobic organic gel particles;

[0028] Note: the amount of the modification solution only needs to ensure that the aged gel particles are always immersed, and generally 25±5ml is used for the block-shaped gel obtained from 5ml of the silica sol solution;

[0029] 1.5), normal pressure drying: filtering the slurry containing the hydrophobic organic gel particles, and drying the obtained solid at 150±10℃ for 2±0.2h to obtain a SiO2 aerogel powder.

[0030] The obtained SiO2 aerogel has a particle size of 900-5000nm (preferably 1000-4800nm).

[0031] As a further improvement of the preparation method of the polar bear hair-like polyurethane aerogel fiber of the present application, in step S2, the surfactant is at least one of dispersant 5040, AEO-9 and dispersant NNO (preferably AEO-9).

[0032] As a further improvement of the preparation method of the polar bear hair-like polyurethane aerogel fiber of the present application, the solid content of the aqueous polyurethane is 8-20wt% (preferably 9-11wt%, more preferably 10wt%).

[0033] As a further improvement of the preparation method of the polar bear hair-like polyurethane aerogel fiber of the present application, in step S4, the drying temperature is 50-120℃ (preferably 60-110℃); the cooling temperature is 0-30℃ (preferably 5-25℃).

[0034] As a further improvement of the preparation method of the polar bear hair-like polyurethane aerogel fiber of the present application, in step S4, the immersion time of the core layer in the coating liquid is controlled to be 2-10 seconds (preferably 5 seconds). The drying time is about 1 minute, and the cooling time is about 15 seconds.

[0035] The step S1 of the present application uses sol-gel method and pore repair method to prepare SiO2 aerogel powder, and the specific process includes: hydrolysis, condensation, aging (gel aging), hydrophobic modification and normal pressure drying.

[0036] The step S3 of the present application relates to a phase separation process based on wet spinning technology, and the step S4 relates to a coating process (dip coating process).

[0037] The present application has the following technical advantages:

[0038] 1. In the preparation of SiO2 aerogel, two-step aging is adopted, which greatly shortens the aging time compared with the existing conventional one-step aging method which requires 2-7 days.

[0039] 2. Preparation of coating liquid: SiO2 aerogel is dispersed by using surfactants such as AEO-9, and the dispersion method can combine cell crushing and ultrasonic dispersion.

[0040] 3. The coating method of the present application is to coat on a single fiber, and then the fibers are woven into a fabric, so the pores of the fabric can be preserved, and therefore the present application can avoid affecting the air permeability and comfort of the fabric.

[0041] 4. The present application provides a continuous dip coating device, so that a continuous dip coating process can be realized.

[0042] 5. The present application constructs a core-sheath structure polyurethane aerogel fiber by adjusting the content of SiO2 aerogel in the coating liquid and the thickness of the shell layer (relatively speaking, the greater the solid content of polyurethane, the thicker the shell layer).

[0043] 6、The present application often prepares high mechanical performance (high elasticity) and high thermal insulation performance of polar bear-like hair polyurethane aerogel fibers after drying and setting under normal pressure. The core-sheath structure and hierarchical porous structure (nanoporous structure in the shell layer and microporous structure in the core layer) of the polar bear-like hair polyurethane aerogel fibers endow the fibers with ultra-high thermal insulation performance, providing potential applications for thermal management textiles.

[0044] 7、The method of the present application is simple, easy to realize, easy to control, low cost, green and environmentally friendly, and convenient for industrialized production. BRIEF DESCRIPTION OF DRAWINGS

[0045] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0046] Figure 1 A continuous dip coating device used in the present application.

[0047] Figure 2 A cross-sectional electron microscope image of the polar bear-like hair polyurethane aerogel fibers prepared in Example 5;

[0048] Figure 2 In the figure, (b) is a cross-sectional electron microscope image of the polar bear-like hair polyurethane aerogel fibers, (a) is a nanometer pore electron microscope image of the fiber shell layer in (b), and (c) is a micropore electron microscope image of the core layer in (b).

[0049] Figure 3 Stress-strain curve graphs of Examples 1-5.

[0050] Figure 4 Temperature rise curve graphs of Examples 1-5 in a 35℃ heating environment. DETAILED DESCRIPTION

[0051] The present application will be further described below in conjunction with specific examples, but the scope of protection of the present application is not limited thereto:

[0052] Example 1, a method for constructing polar bear-like hair polyurethane aerogel fibers by a continuous dip coating process, comprising the following steps:

[0053] (1) SiO2 aerogel preparation:

[0054] 1.1) Hydrolysis:

[0055] Mix the molar ratio of tetraethyl orthosilicate: ethanol: HCl (10 -2 mol / L HCl solution) = 1:3:1.5 at 80℃ for 6h to obtain a silica sol solution;

[0056] 1.2), condensation:

[0057] 5ml of the silica sol solution was mixed with 5ml of ethanol, and 0.5ml of 0.6M ammonia solution was added to coagulate the gel into a block under alkaline conditions;

[0058] 1.3) aging (divided into two steps of aging):

[0059] The block gel obtained in step 1.2) was first soaked in 20ml of an aging solution at 50°C for 0.2 hours, and then taken out for crushing (to a particle size of about 1.5 microns). The crushed gel particles were then placed back into the aging solution, which was heated to 80°C, for 1.8 hours of soaking and aging;

[0060] The aging solution was tetraethyl orthosilicate / ethanol = 1:2 in volume;

[0061] 1.4) hydrophobic modification:

[0062] The aged gel particles obtained in step 1.3) were soaked in a mixture of 5ml of trimethylchlorosilane and 20ml of n-hexane for 40 minutes of hydrophobic modification. A slurry containing hydrophobic organic gel particles (i.e., modified gel particles) was obtained.

[0063] 1.5) normal pressure drying:

[0064] The slurry containing hydrophobic organic gel particles obtained in step 1.4) was filtered, and the solid obtained by filtration was dried at 150°C under ambient pressure for 2 hours to obtain a powdered SiO2 aerogel.

[0065] The SiO2 aerogel had a particle size of 1200nm.

[0066] (2) Coating liquid preparation:

[0067] 0.5g of SiO2 aerogel and 0.2g of surfactant AEO-9 were added to 99.3g of aqueous polyurethane, and magnetic stirring (speed 100rpm) was used for 30 minutes. The mixed solution after stirring was uniformly dispersed by cell crushing (ice water bath, ultrasonic working for 2s, intermittent 2s, time 5min, power 50%) and ultrasonic dispersion (ultrasonic frequency 40KHZ, time 30 minutes) to obtain an aqueous polyurethane mixed solution with a SiO2 aerogel mass fraction of 0.5%, which was used as a coating liquid;

[0068] The solid content of the aqueous polyurethane was 10% (mass %), and the aqueous polyurethane 1926 produced by Shenzhen Jitian Chemical Co., Ltd. was diluted with water to a solid content of 10%.

[0069] (3) Preparation of homogeneous porous polyurethane fibers:

[0070] 10 g polyurethane granules were added into 40 g N,N-dimethylformamide as solvent and stirred until the polyurethane granules were completely dissolved, obtaining a polyurethane solution with a polyurethane mass fraction of 20%;

[0071] The polyurethane granules were 1180A10 purchased from BASF (China) Co., Ltd., with a particle size of 2 cm.

[0072] The non-solvent composed of ethanol and water was used as the mixed coagulation bath, and the weight content of ethanol in the non-solvent was 60%;

[0073] The wet spinning was performed by using the wet spinning method:

[0074] Under the flow rate control of the micro-flow pump, the polyurethane solution was injected into the spinneret with a diameter of 400 microns at a speed of 1.5 mL / min, and then sprayed into the mixed coagulation bath for wet spinning. The solvent in the polyurethane solution and the non-solvent in the mixed coagulation bath were separated, thereby obtaining a polyurethane gel fiber. The temperature of the mixed coagulation bath was 65°C. The collection rate of the wet spinning was 20 m / min.

[0075] The obtained polyurethane gel fiber was dried at 50°C under normal pressure for 2h, obtaining a homogeneous porous polyurethane fiber.

[0076] Note: The injection speed of the polyurethane solution is controlled by the micro-flow pump, and the spinneret is located in the mixed coagulation bath, which is a conventional technology.

[0077] (4) Using a continuous dip-coating process, the homogeneous porous polyurethane fiber is used as the core layer, and the aqueous polyurethane mixture is used as the shell layer dip-coating liquid. After drying at 90°C under normal pressure and a collection rate of 25 m / min, a polar bear-like polyurethane aerogel fiber is obtained.

[0078] Specifically as follows:

[0079] Using the continuous dip-coating device as described in Figure 1 The homogeneous porous polyurethane fiber is wound on the roller as the core layer fiber. One end of the core layer fiber sequentially passes through the container containing the coating liquid, the drying device (drying under normal pressure), and the cooling device, and is connected to the collection roller. By adjusting the collection rate of the collection roller, the soaking time, drying time, and cooling time of the homogeneous porous polyurethane fiber in the coating liquid can be controlled.

[0080] The collection rate of the collection roller is set to 25 m / min, and the homogeneous porous polyurethane fiber passes through the dip-coating liquid at a rate of 25 m / min, with a soaking time of 5 seconds. Then, it is dried at 90°C under normal pressure in the drying device for 1 minute, and then cooled at 5°C in the cooling device for 15 seconds. The final shell layer has a thickness of about 100 μm.

[0081] Example 2, a method for constructing a polar bear-like polyurethane aerogel fiber by a continuous dip-coating process,

[0082] The following changes are made relative to Example 1:

[0083] (2) Coating liquid preparation:

[0084] 1 g of SiO2 aerogel and 0.3 g of AEO-9 are added to 98.7 g of aqueous polyurethane, and the rest is the same as step (2) of Example 1 to obtain an aqueous polyurethane mixed solution with a SiO2 aerogel mass fraction of 1%; this is used as the coating liquid;

[0085] The rest is the same as Example 1.

[0086] Example 3, a method for constructing polar bear-like hair polyurethane aerogel fibers by a continuous dip-coating process,

[0087] The following changes are made relative to Example 1:

[0088] (2) Coating liquid preparation:

[0089] 1.5 g of SiO2 aerogel and 0.4 g of AEO-9 are added to 98.1 g of aqueous polyurethane, and the rest is the same as step (2) of Example 1 to obtain an aqueous polyurethane mixed solution with a SiO2 aerogel mass fraction of 1.5%; this is used as the coating liquid;

[0090] The rest is the same as Example 1.

[0091] Example 4, a method for constructing polar bear-like hair polyurethane aerogel fibers by a continuous dip-coating process,

[0092] The following changes are made relative to Example 1:

[0093] (2) Coating liquid preparation:

[0094] 2 g of SiO2 aerogel and 0.5 g of AEO-9 are added to 97.5 g of aqueous polyurethane, and the rest is the same as step (2) of Example 1 to obtain an aqueous polyurethane mixed solution with a SiO2 aerogel mass fraction of 2%; this is used as the coating liquid;

[0095] The rest is the same as Example 1.

[0096] Example 5, a method for constructing polar bear-like hair polyurethane aerogel fibers by a continuous dip-coating process,

[0097] The following changes are made relative to Example 1:

[0098] (2) Coating liquid preparation:

[0099] 2.5g SiO2 aerogel and 0.6g AEO-9 were added into 96.9g aqueous polyurethane, the rest was the same as step (2) of Example 1, to obtain an aqueous polyurethane mixture with a SiO2 aerogel mass fraction of 2.5%; this was used as the coating liquid;

[0100] The rest was the same as Example 1.

[0101] The cross-section of the polar bear-like hair polyurethane aerogel fiber prepared in Experiment 1, Example 5, was analyzed; the electron microscope image thereof is as follows: Figure 2 .

[0102] According to Figure 2 , it can be known that the fiber of Example 5 formed a hierarchical porous structure, the inside of the fiber presented a micron-level pore structure, and the shell layer presented a nanometer-level pore structure.

[0103] Experiment 2, the polar bear-like hair polyurethane aerogel fibers prepared in Examples 1-5 were detected according to GB / T 3923.1-2013, and the stress-strain curve thereof is as follows: Figure 3 According to Figure 3 , it can be known that with the increase of the SiO2 aerogel content in the shell layer of the fiber, the breaking strength of the fiber slightly decreased, and the breaking elongation increased, and Example 5 had the highest breaking elongation of 1150%.

[0104] Experiment 3, the polar bear-like hair polyurethane aerogel fibers prepared in Examples 1-5 were heated in a 35℃ heating environment; the temperature rise curve thereof is as follows: Figure 4 According to Figure 4 , it can be known that in the 35℃ heating environment, with the increase of the SiO2 aerogel content in the shell layer of the fiber, the heat insulation performance of the fiber gradually improved, and when the temperature reached equilibrium, the temperature differences of Examples 1-5 were 4.78, 5.43, 5.82, 6.01 and 6.16℃ respectively, and Example 5 had the highest thermal insulation performance (6.16℃).

[0105] The performance comparison of the polar bear-like hair polyurethane aerogel fibers obtained in the above cases is as follows:

[0106] Table 1, statistics of the heat insulation performance and stress-strain performance of the fibers

[0107]

[0108] Example 6, the dispersant in Example 5 was changed from “AEO-9” to “5040”, the dosage remained unchanged, still 0.6g, and the rest was the same as Example 5.

[0109] Example 7, the dispersant in Example 5 was changed from “AEO-9” to “NNO”, the dosage remained unchanged, still 0.6g, and the rest was the same as Example 5.

[0110] Comparative Example 1-1, the coating solution in Example 5 is changed from "2.5 g SiO2 aerogel, 0.6 g AEO-9, 96.9 g waterborne polyurethane" to "0.1 g SiO2 aerogel, 0.6 g AEO-9, 99.3 g waterborne polyurethane", and the rest is the same as Example 5.

[0111] Comparative Example 1-2, the coating solution in Example 5 is changed from "2.5 g SiO2 aerogel, 0.6 g AEO-9, 96.9 g waterborne polyurethane" to "3 g SiO2 aerogel, 0.6 g AEO-9, 96.4 g waterborne polyurethane", and the rest is the same as Example 5.

[0112] Comparative Example 1-3, the coating solution in Example 5 is changed from "2.5 g SiO2 aerogel, 0.6 g AEO-9, 96.9 g waterborne polyurethane" to "5 g SiO2 aerogel, 0.6 g AEO-9, 94.4 g waterborne polyurethane", and the rest is the same as Example 5.

[0113] Comparative Example 2, the "solid content of waterborne polyurethane" in Example 5 is changed from 10% to 20%; and the rest is the same as Example 5.

[0114] The performance of the above cases is as shown in Table 2.

[0115] Table 2, statistics of fiber thermal insulation performance and stress-strain performance

[0116]

[0117] Comparative Example 3-1, change Example 1 step 1.3) from block-shaped gel to immerse in aging liquid at 50℃ all the time, immerse for 10 hours, after drying, it is found that the internal pore structure of the gel collapses and cannot form a three-dimensional porous structure, so it is far from the aging condition.

[0118] Comparative Example 3-2, change Example 1 step 1.3) from block-shaped gel to immerse in aging liquid at 80℃ all the time, immerse for 10 hours, after drying, it is found that the internal pore structure of the gel collapses and cannot form a three-dimensional porous structure, so it is far from the aging condition.

[0119] Finally, it should be noted that the above only lists several specific embodiments of the present application. Obviously, the present application is not limited to the above embodiments, but can also have many variations. All variations that can be directly derived or inferred from the disclosure of the present application by those of ordinary skill in the art should be considered as falling within the scope of the present application.

Claims

1. A process for the preparation of arctic-fox-like hair polyurethane aerogel fibers, characterized by The method comprises the following steps: S1, SiO2 aerogel preparation, the following steps are carried out in turn: 1.1), hydrolysis: mixing tetraethyl orthosilicate: ethanol: HC1 = 1 : 3 : 1.5 in molar ratio, reacting at 80±10°C for 6±0.5h to obtain a silica sol solution; the HC1 is a HC1 solution with a concentration of 10 -2 mol / L; 1.2), condensation: 5 ml of silica sol solution is mixed with 5±0.5 ml of ethanol, and then 0.5±0.05 ml of 0.6 mol / L ammonia solution is added to condense into a blocky gel; 1.3), gel aging: first, the blocky gel is placed in a 50±5°C aging solution for 0.1~2h, then taken out for crushing, and then the crushed gel particles are placed back into the aging solution and heated to 80±5°C for 0.2~1.9h; The aging solution is tetraethyl orthosilicate / ethanol=1:2 by volume ratio; 1.4), hydrophobic modification: the aged gel particles are added to a modification liquid obtained by mixing trimethylchlorosilane and n-hexane at a volume ratio of 1:4 for hydrophobic modification for 40±5 minutes, to obtain a slurry containing hydrophobic organic gel particles; 1.5), normal pressure drying: the slurry containing hydrophobic organic gel particles is filtered, and the solid obtained by filtration is dried at 150±10°C for 2±0.2 hours to obtain SiO2 aerogel powder; S2, coating liquid preparation: The coating liquid is composed of 0.5~2.5wt% SiO2 aerogel, 0.2~0.6wt% surfactant, and the rest is water-based polyurethane; The surfactant is AEO-9, and the solid content of the water-based polyurethane is 9~11wt%; S3, porous polyurethane fiber preparation: The polyurethane master particles are dissolved in an organic solvent to obtain a polyurethane solution with a polyurethane mass fraction of 19%~21%; A non-solvent composed of ethanol and water is used as a mixed coagulation bath, and the weight content of ethanol in the non-solvent is 58~62%; The polyurethane solution is injected into the mixed coagulation bath by a micro-pump, and after phase separation, porous polyurethane fibers are prepared by normal pressure drying; the temperature of the mixed coagulation bath is 60~70°C; S4, dip coating process: The porous polyurethane fibers obtained in step S3 are used as the core layer, and the coating liquid obtained in step S2 is used as the shell layer, and through continuous dip coating process, the outer surface of the porous polyurethane fibers is coated with the shell layer, and then dried and cooled to prepare the polar bear-like hair polyurethane aerogel fibers.

2. The preparation method of the polar bear-like hair polyurethane aerogel fibers according to claim 1, wherein: In step S4, the drying temperature is 50~120°C, and the cooling temperature is 0~30°C.

3. The preparation method of the polar bear-like hair polyurethane aerogel fibers according to claim 2, wherein: In step S4, the immersion time of the core layer in the coating liquid is controlled to be 2~10 seconds.

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