Cool-feeling polyurethane elastic fiber and method for producing the same

Abstract

This invention provides a cooling polyurethane elastic fiber and its preparation method, belonging to the field of high-performance fiber preparation technology. This application involves a two-step surface modification of boron nitride nanosheets, making them easily dispersed in polyurethane and maintaining a relatively continuous thermally conductive network in a wet state. A eutectic liquid is loaded onto hollow silica microspheres to obtain a loaded cooling agent with a slow-release cooling effect, capable of slowly releasing menthol, prolonging the subjective cooling time, and complementing the physical thermal management effect of the fiber. A polyurethane-polysiloxane compatibilizer containing flexible siloxane segments and multi-branched polar end groups is constructed using hydroxyl-terminated polydimethylsiloxane, diphenylmethane diisocyanate, and trimethylolpropane. The zwitterionic modified boron nitride and the loaded cooling agent are uniformly coated to form a functional slurry, which is then wet-spun with a polyurethane matrix to prepare composite fibers. This achieves a synergistic effect of thermal conductivity and sensory cooling while maintaining good elasticity and hand feel.

Description

Technical Field

[0001] This invention belongs to the field of high-performance fiber preparation technology, specifically relating to a method for preparing cool-feeling high-performance spandex by combining functional filler interface modification, functional slurry construction and wet spinning, and particularly relating to a cool-feeling polyurethane elastic fiber and its preparation method. Background Technology

[0002] With the improvement of living standards and the enhancement of sports and health awareness, textiles with thermal and moisture management functions are increasingly favored by consumers. Among them, cooling elastic fibers (such as cooling spandex and cooling TPU fibers) have become a research hotspot in the field of functional textiles because they can give tight-fitting sportswear, underwear and other close-fitting clothing excellent contact cooling sensation.

[0003] Currently, the mainstream preparation technology mostly involves adding a high content of thermally conductive inorganic mineral powders (such as jade powder, mica, or boron nitride) to the polyurethane matrix to achieve physical cooling upon contact. However, this technology, which relies solely on physical blending, has significant drawbacks: on the one hand, to achieve the ideal cooling value, a high filler content is often required, which disrupts the microphase structure of the soft and hard segments of the polyurethane, leading to increased fiber modulus, decreased resilience, and a rough feel; on the other hand, the inorganic filler has poor compatibility with the organic matrix interface. During repeated fiber stretching, the interface is prone to debonding, creating micropores that cut off the thermal conductivity pathway, resulting in the phenomenon of "the more it is stretched, the worse the cooling sensation becomes," making it difficult to meet the comprehensive requirements of maintaining the elasticity, stable thermal conductivity, and continuous cooling sensation of high-performance spandex in high-intensity sports scenarios.

[0004] Furthermore, existing single physical heat conduction mechanisms lose their cooling effect once the temperature difference disappears after the skin and fabric reach thermal equilibrium, lacking a long-lasting maintenance mechanism. Although sensory agents such as menthol or phase change materials can be introduced to prolong the cooling sensation, traditional menthol components are highly volatile, have a pungent odor, and poor washability, making it difficult to achieve a long-lasting and controllable sustained release in fibers. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a cooling polyurethane elastic fiber and its preparation method. By introducing functionally modified slurry during the spinning process to impart in-situ functionality to the fiber structure, the resulting fiber achieves stable thermal conductivity and heat dissipation performance and a lasting sensory cooling sensation while maintaining its original elasticity and feel. This application employs a two-step surface modification method using KH-570 and sulfobetaine methacrylate to modify boron nitride nanosheets, enabling them to be easily dispersed in polyurethane and maintain a relatively continuous thermally conductive network in a wet state. By loading L-menthol / lauric acid eutectic liquid onto hollow silica microspheres, a loaded cooling agent with slow-release cooling effect is obtained, which can slowly release menthol, prolonging the subjective cooling time and complementing the physical thermal management effect of the fiber. Furthermore, a polyurethane-polysiloxane compatibilizer containing flexible siloxane segments and multi-branched polar end groups is constructed using hydroxyl-terminated polydimethylsiloxane, diphenylmethane diisocyanate, and trimethylolpropane. This compatibilizer uniformly coats the zwitterionic modified boron nitride and the loaded cooling agent to form a functional slurry, which is then wet-spun with a polyurethane matrix to prepare composite fibers. This achieves a synergistic effect of thermal conductivity and sensory cooling while maintaining good elasticity and hand feel.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a cooling-feeling polyurethane elastic fiber, the method comprising:

[0008] S1: Boron nitride nanosheets were dispersed in a mixed solution to obtain a boron nitride dispersion. A silane coupling agent was added to obtain reaction solution A. The pH value was adjusted using acetic acid solution to obtain reaction solution B. The reaction was refluxed, centrifuged, washed, and dried to obtain modified boron nitride. Modified boron nitride was dispersed in deionized water, and sulfobetaine methacrylate and ammonium persulfate were added to obtain reaction solution C. The reaction was stirred under a nitrogen atmosphere, and boron nitride modified with zwitterionic polymer was obtained by dialysis and freeze-drying.

[0009] S2: L-menthol and lauric acid are mixed and magnetically stirred to obtain a eutectic solvent; hollow silica microspheres are immersed in the eutectic solvent to obtain mixture D, which is then vacuum impregnated, removed, and sprayed with anhydrous ethanol to remove the free eutectic solvent on the particle surface, and then dried to obtain a loaded cooling agent.

[0010] S3: Hydroxyl-terminated polydimethylsiloxane was added to dimethylacetamide to obtain dispersion D. Diphenylmethane diisocyanate was added under nitrogen protection to obtain reaction solution E. The reaction yielded a prepolymer solution. Trimethylolpropane dimethylacetamide solution was added dropwise to the prepolymer solution to obtain reaction solution F. The reaction yielded a dispersion. The dispersion was cooled, and zwitterionic polymer-modified boron nitride and a supported cooling agent were added sequentially. Dimethylacetamide was added to adjust the solid content to obtain reaction solution G. After heat preservation, the mixture was sheared and dispersed to obtain a functional modified slurry.

[0011] S4: Thermoplastic polyurethane is added to dimethylacetamide to obtain a matrix solution, and functional modified slurry is added to obtain a spinning solution. Vacuum degassing is performed to obtain a spinning solution. The spinning solution is used to form polyurethane elastic fibers and introduce functional components in situ through a wet spinning process. The spinning solution is extruded through a spinneret into a coagulation bath to obtain nascent fibers. The nascent fibers are drawn and heat-set through a drying tunnel to obtain preliminary fibers. Oiling and winding are then performed to obtain cool-feeling polyurethane elastic fibers.

[0012] As a preferred technical solution of the present invention, in step S1, the mass-to-volume ratio of the boron nitride nanosheets to the mixed solution is 1g:(50-100)mL, for example, it can be 1g:50mL, 1g:55mL, 1g:60mL, 1g:65mL, 1g:70mL, 1g:75mL, 1g:80mL, 1g:85mL, 1g:90mL, 1g:95mL or 1g:100mL, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0013] In some optional embodiments, the volume ratio of ethanol to deionized water in the mixed solution is (4-9):1, for example, it can be 4.0:1, 4.5:1, 5.0:1, 5.5:1, 6.0:1, 6.5:1, 7.0:1, 7.5:1, 8.0:1, 8.5:1 or 9.0:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0014] In some optional embodiments, the mass ratio of the silane coupling agent to the boron nitride nanosheets is (0.2-0.4):1, for example, it can be 0.20:1, 0.22:1, 0.24:1, 0.26:1, 0.28:1, 0.30:1, 0.32:1, 0.34:1, 0.36:1, 0.38:1 or 0.40:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0015] In some optional embodiments, the concentration of the acetic acid solution is 5-10 wt.%, for example, it may be 5.0 wt.%, 5.5 wt.%, 6.0 wt.%, 6.5 wt.%, 7.0 wt.%, 7.5 wt.%, 8.0 wt.%, 8.5 wt.%, 9.0 wt.%, 9.5 wt.% or 10.0 wt.%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0016] In some alternative embodiments, the pH of the reaction solution A is adjusted to 4-5 using an acetic acid solution, for example, to 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9 or 5.0, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0017] In some optional embodiments, the reflux reaction temperature of the reaction solution B is 60-75°C, for example, it can be 60.0°C, 61.5°C, 63.0°C, 64.5°C, 66.0°C, 67.5°C, 69.0°C, 70.5°C, 72.0°C, 73.5°C or 75.0°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0018] In some optional embodiments, the reflux reaction time of the reaction solution B is 6-12 hours, for example, 6.0 hours, 6.6 hours, 7.2 hours, 7.8 hours, 8.4 hours, 9.0 hours, 9.6 hours, 10.2 hours, 10.8 hours, 11.4 hours, or 12.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0019] In some optional embodiments, the mass ratio of the sulfobetaine methacrylate to the modified boron nitride is (0.1-0.3):1, for example, it can be 0.10:1, 0.12:1, 0.14:1, 0.16:1, 0.18:1, 0.20:1, 0.22:1, 0.24:1, 0.26:1, 0.28:1 or 0.30:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0020] In some optional embodiments, the mass ratio of ammonium persulfate to sulfobetaine methacrylate is (0.01-0.05):1, for example, it can be 0.010:1, 0.014:1, 0.018:1, 0.022:1, 0.026:1, 0.030:1, 0.034:1, 0.038:1, 0.042:1, 0.046:1 or 0.050:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0021] In some optional embodiments, the reaction temperature of the reaction solution C is 55-70°C, for example, it can be 55.0°C, 56.5°C, 58.0°C, 59.5°C, 61.0°C, 62.5°C, 64.0°C, 65.5°C, 67.0°C, 68.5°C or 70.0°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0022] In some optional embodiments, the reaction time of the reaction solution C is 4-8 hours, for example, 4.0 hours, 4.4 hours, 4.8 hours, 5.2 hours, 5.6 hours, 6.0 hours, 6.4 hours, 6.8 hours, 7.2 hours, 7.6 hours or 8.0 hours, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0023] As a preferred technical solution of the present invention, in step S2, the molar ratio of L-menthol to lauric acid is (1-1.5):1, for example, it can be 1.00:1, 1.05:1, 1.10:1, 1.15:1, 1.20:1, 1.25:1, 1.30:1, 1.35:1, 1.40:1, 1.45:1 or 1.50:1, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0024] In some alternative embodiments, the temperature of the magnetic stirring is 40-50°C, for example, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C or 50°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0025] In some optional embodiments, the magnetic stirring time is 1-2 hours, for example, it can be 1.0 hours, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours or 2.0 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0026] In some optional embodiments, the mass ratio of the hollow silica microspheres to the eutectic solvent is 1:(0.8-1.2), for example, it can be 1:0.80, 1:0.84, 1:0.88, 1:0.92, 1:0.96, 1:1.00, 1:1.04, 1:1.08, 1:1.12, 1:1.16 or 1:1.20, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0027] In some optional embodiments, the pressure of the vacuum impregnation treatment is -0.08 to -0.1 MPa, for example, it can be -0.100 MPa, -0.098 MPa, -0.096 MPa, -0.094 MPa, -0.092 MPa, -0.090 MPa, -0.088 MPa, -0.086 MPa, -0.084 MPa, -0.082 MPa or -0.080 MPa, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0028] In some optional embodiments, the vacuum impregnation treatment time is 2-4 hours, for example, it can be 2.0 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, 3.0 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours or 4.0 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0029] In some alternative embodiments, the drying temperature is 30-40°C, for example, 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C or 40°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0030] As a preferred technical solution of the present invention, in step S3, the mass ratio of the terminal hydroxyl polydimethylsiloxane to dimethylacetamide is 1:(2-4), for example, it can be 1:2.0, 1:2.2, 1:2.4, 1:2.6, 1:2.8, 1:3.0, 1:3.2, 1:3.4, 1:3.6, 1:3.8 or 1:4.0, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0031] In some optional embodiments, the molar ratio of the diphenylmethane diisocyanate to the hydroxyl-terminated polydimethylsiloxane is (2.5-3.5):1, for example, it can be 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3.0:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1 or 3.5:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0032] In some optional embodiments, the reaction temperature of the reaction solution E is 60-70°C, for example, it can be 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C or 70°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0033] In some optional embodiments, the reaction time of the reaction solution E is 2-3 hours, for example, it can be 2.0 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3.0 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0034] In some optional embodiments, the concentration of the trimethylolpropane in dimethylacetamide solution is 15-25 wt.%, for example, it can be 15 wt.%, 16 wt.%, 17 wt.%, 18 wt.%, 19 wt.%, 20 wt.%, 21 wt.%, 22 wt.%, 23 wt.%, 24 wt.%, or 25 wt.%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0035] In some optional embodiments, the mass ratio of trimethylolpropane to hydroxyl-terminated polydimethylsiloxane is (0.08-0.15):1, for example, it can be 0.080:1, 0.087:1, 0.094:1, 0.101:1, 0.108:1, 0.115:1, 0.122:1, 0.129:1, 0.136:1, 0.143:1 or 0.150:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0036] In some optional embodiments, the reaction temperature of the reaction liquid F is 80-90°C, for example, it can be 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C or 90°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0037] In some optional embodiments, the reaction time of the reaction solution F is 3-5 hours, for example, it can be 3.0 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours, 4.0 hours, 4.2 hours, 4.4 hours, 4.6 hours, 4.8 hours or 5.0 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0038] In some optional embodiments, the temperature of the dispersion after cooling is 50-60°C, for example, it can be 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C or 60°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0039] In some optional embodiments, the mass ratio of the zwitterionic polymer-modified boron nitride to the dispersion is (0.1-0.25):1, for example, it can be 0.100:1, 0.115:1, 0.130:1, 0.145:1, 0.160:1, 0.175:1, 0.190:1, 0.205:1, 0.220:1, 0.235:1 or 0.250:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0040] In some optional embodiments, the mass ratio of the supported cooling agent to the zwitterionic polymer-modified boron nitride is (0.1-0.2):1, for example, it can be 0.10:1, 0.11:1, 0.12:1, 0.13:1, 0.14:1, 0.15:1, 0.16:1, 0.17:1, 0.18:1, 0.19:1 or 0.20:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0041] In some optional embodiments, the addition of dimethylacetamide to adjust the solid content to 25-35% to obtain reaction solution G can be, for example, adjusting the solid content to 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34% or 35%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0042] In some optional embodiments, the reaction solution G is kept warm for 1-2 hours, for example, 1.0h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2.0h, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0043] As a preferred technical solution of the present invention, in step S4, the mass fraction of the matrix solution is 20-35%, for example, it can be 20.0%, 21.5%, 23.0%, 24.5%, 26.0%, 27.5%, 29.0%, 30.5%, 32.0%, 33.5% or 35.0%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] In some optional embodiments, the mass ratio of the functional modified slurry to the matrix solution is (8-15):100, for example, it can be 8.0:100, 8.7:100, 9.4:100, 10.1:100, 10.8:100, 11.5:100, 12.2:100, 12.9:100, 13.6:100, 14.3:100 or 15.0:100, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0045] In some optional embodiments, the volume ratio of dimethylacetamide to deionized water in the coagulation bath is (10-20):100, for example, it can be 10:100, 11:100, 12:100, 13:100, 14:100, 15:100, 16:100, 17:100, 18:100, 19:100 or 20:100, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0046] In some optional embodiments, the temperature of the coagulation bath is 25-35°C, for example, it can be 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C or 35°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0047] In some optional embodiments, the stretching factor is 2.0-3.0 times, for example, it can be 2.0 times, 2.1 times, 2.2 times, 2.3 times, 2.4 times, 2.5 times, 2.6 times, 2.7 times, 2.8 times, 2.9 times or 3.0 times, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0048] In some alternative embodiments, the initial fiber heat setting temperature is 100-120°C, for example, 100°C, 102°C, 104°C, 106°C, 108°C, 110°C, 112°C, 114°C, 116°C, 118°C or 120°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0049] In some optional embodiments, the heat setting time for the initial fiber heat setting is 30-90s, for example, 30s, 36s, 42s, 48s, 54s, 60s, 66s, 72s, 78s, 84s or 90s, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0050] Secondly, this application provides a cool-feeling polyurethane elastic fiber prepared by the above-described preparation method.

[0051] This application utilizes a two-step surface modification process to prepare a thermally conductive filler with excellent dispersibility and humidity response characteristics for boron nitride nanosheets. First, KH-570 is introduced into an ethanol / water mixture and hydrolyzed and condensed under weakly acidic conditions to form a silane condensation layer on the boron nitride surface, providing a basis for improved wettability and physical / chemical anchoring of the subsequent polymer layer. Subsequently, ammonium persulfate is used to initiate the polymerization of sulfobetaine methacrylate in an aqueous phase, forming a zwitterionic polymer layer with sulfonic acid and quaternary ammonium groups. This polymer layer improves the dispersion stability of boron nitride in polar media and polyurethane matrices, mitigating the mechanical weakening and increased thermal resistance caused by filler agglomeration. Furthermore, the zwitterionic segments hydrate and swell upon increased humidity or contact with sweat, altering the microstructure of the interface around the filler to some extent. This allows the thermally conductive network to maintain good continuity under humid conditions, thus providing a foundation for subsequent humidity-assisted thermal management.

[0052] This application prepares a loaded cooling agent with both storage stability and sustained-release capability by preparing and loading an L-menthol / lauric acid eutectic system. L-menthol and lauric acid are mixed to form a room-temperature flowing eutectic liquid, reducing the volatility of menthol and improving its compatibility in organic systems. This eutectic liquid is impregnated into the pores of hollow silica microspheres under vacuum conditions, achieving physical encapsulation through capillary action and pore structure. Subsequent ethanol spraying removes the free eutectic phase from the outer surface of the particles, reducing menthol loss and migration during processing. The resulting loaded cooling agent acts as a cooling source in the fiber, slowly releasing small amounts of menthol molecules during wear or friction, prolonging the duration of the subjective cooling sensation and complementing physical thermal management.

[0053] This application employs hydroxyl-terminated polydimethylsiloxane, diphenylmethane diisocyanate, and trimethylolpropane to construct a polyurethane-polysiloxane dispersion phase, thereby obtaining an interfacial compatibilizer possessing both flexible siloxane segments and a multi-branched structure with polar end groups. Diphenylmethane diisocyanate reacts with hydroxyl-terminated polydimethylsiloxane to generate a prepolymer with hard segments, followed by the introduction of multifunctional trimethylolpropane, introducing a high end-group density while ensuring the system remains soluble and dispersible. This hyperbranched polymer provides a soft, low-surface-energy local microphase environment through the flexible siloxane segments, contributing to improved fiber feel and bending properties. Simultaneously, its polar end groups, such as hydroxyl groups, can form hydrogen bonds or other interactions with the polyurethane matrix, zwitterionic polymer-modified boron nitride, and the surface of the supported cooling agent, improving the dispersion stability of the filler in the matrix and reducing interfacial voids and microcracks. The purpose of introducing zwitterionic polymer-modified boron nitride and a supported cooling agent into the dispersion and adjusting the solid content is to uniformly coat the thermally conductive filler and sensory filler in the flexible compatibilizer network while ensuring suitable rheological properties, thereby forming a functional slurry that can be directly blended with the polyurethane matrix.

[0054] Functionally modified slurry is added to the matrix solution, and a composite fiber with elasticity, thermal conductivity, and cooling properties is constructed through wet spinning and heat setting. Polyurethane provides the overall elastic skeleton and mechanical strength. During spinning, a dimethylacetamide / water coagulation bath solidifies the polyurethane segments, and the zwitterionic polymer-modified boron nitride and the supported cooling agent in the functional slurry are solidified and distributed along the fiber cross-section along with the matrix. An appropriate draw ratio is beneficial to the orientation of polyurethane segments and, to a certain extent, drives the lamellar zwitterionic polymer-modified boron nitride to align axially along the fiber, thereby improving the continuity of the axial heat conduction path. The heat setting process stabilizes the fiber size and internal microphase distribution, preventing further migration or aggregation of the functional phases due to operating temperature. Overall, the zwitterionic polymer-modified boron nitride is mainly responsible for maintaining good thermal conductivity and heat diffusion under humid conditions, the eutectic menthol system is responsible for providing a lasting sensory cooling sensation, and the polyurethane-polysiloxane acts as an interfacial buffer and dispersion medium among the three, so as to maintain the softness and fatigue resistance of the fiber as much as possible while improving the cooling sensation and thermal management performance.

[0055] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0056] This application introduces KH-570 and sulfobetaine methacrylate to perform two-step surface modification on boron nitride nanosheets, making them easy to disperse in polyurethane and with good interfacial compatibility, while also exhibiting hydration and swelling characteristics under humidity or sweat, thus maintaining a relatively continuous and stable heat-conducting network under humid conditions.

[0057] This application describes a loaded cooling agent with good storage stability and slow-release properties obtained by loading an L-menthol / lauric acid eutectic liquid into the pores of hollow silica microspheres. This cooling agent slowly releases menthol during fiber use, prolonging the subjective cooling time and complementing the physical thermal management of the fiber.

[0058] This application constructs a polyurethane-polysiloxane interfacial compatibilizer with flexible siloxane segments and multi-branched polar end groups using hydroxyl-terminated polydimethylsiloxane, diphenylmethane diisocyanate, and trimethylolpropane. This improves fiber feel and bending properties, and enhances dispersion and interfacial stability through hydrogen bonding with the polyurethane matrix and various functional fillers. By introducing zwitterionic modified boron nitride and a supported cooling agent into this dispersed phase and adjusting the solid content, the thermally conductive and cooling fillers are uniformly coated, forming a functional slurry that can be directly blended with polyurethane.

[0059] This application describes the preparation of composite fibers with elasticity, thermal conductivity, and cooling properties by blending functionally modified slurry with a polyurethane matrix solution and then wet spinning, drawing, and heat setting. Polyurethane forms the elastic skeleton, while zwitterionic polymer-modified boron nitride creates a relatively continuous and effective thermally conductive pathway within the fiber, even in a wet state. A eutectic system loaded with menthol provides a slow-release sensory cooling sensation, and a polyurethane-polysiloxane compatibilizer improves the interfacial dispersion and stability of the three components. This achieves a synergistic effect of thermal management and cooling sensation while maintaining fiber softness and fatigue resistance.

[0060] The technical solution of this invention takes fiber as the object of treatment. By introducing functional modification components into the fiber during the spinning and forming stage, the synergistic regulation of fiber structure and performance is achieved, which belongs to the fiber functional modification technology route. Detailed Implementation

[0061] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The embodiments described herein are specific implementations of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limiting the implementation of the present invention or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include technical solutions that employ any obvious substitutions and modifications made to the embodiments described herein.

[0062] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone further purification or processing.

[0063] Example 1

[0064] This embodiment provides a method for preparing a cooling polyurethane elastic fiber, which specifically includes the following steps:

[0065] S1: Boron nitride nanosheets were dispersed in a mixed solution to obtain a boron nitride dispersion, wherein the mass-to-volume ratio of boron nitride nanosheets to ethanol aqueous solution was 1 g:80 mL, and the volume ratio of ethanol to deionized water in the mixed solution was 8:1. A silane coupling agent was added to obtain reaction solution A, wherein the silane coupling agent was KH-570, and the mass ratio of silane coupling agent to boron nitride nanosheets was 0.35:1. The pH value was adjusted to 4.8 using an 8 wt.% acetic acid solution to obtain reaction solution B. The reaction solution was then incubated at 70℃. The mixture was refluxed for 10 h, centrifuged, washed, and dried to obtain modified boron nitride. The modified boron nitride was dispersed in deionized water, and sulfobetaine methacrylate and ammonium persulfate were added to obtain reaction solution C, wherein the mass ratio of sulfobetaine methacrylate to modified boron nitride was 0.25:1, and the mass ratio of ammonium persulfate to sulfobetaine methacrylate was 0.04:1. The mixture was stirred at 68 °C for 7 h under a nitrogen atmosphere, and after dialysis and freeze-drying, zwitterionic polymer-modified boron nitride was obtained.

[0066] S2: L-menthol and lauric acid were mixed at a molar ratio of 1.4:1 and magnetically stirred at 48°C for 1.8 h to obtain a eutectic solvent; hollow silica microspheres were impregnated in the eutectic solvent to obtain mixture D, wherein the mass ratio of hollow silica microspheres to eutectic solvent was 1:1.1. The mixture was vacuum impregnated at a pressure of -0.095 MPa for 3.5 h, and then sprayed with anhydrous ethanol to remove the free eutectic solvent on the surface of the particles. The mixture was then dried at 38°C to obtain a loaded cooling agent.

[0067] S3: Hydroxyl-terminated polydimethylsiloxane was added to dimethylacetamide to obtain dispersion D, wherein the mass ratio of hydroxyl-terminated polydimethylsiloxane to dimethylacetamide was 1:3.5. Diphenylmethane diisocyanate was added under nitrogen protection to obtain reaction solution E, wherein the molar ratio of diphenylmethane diisocyanate to hydroxyl-terminated polydimethylsiloxane was 3.2:1. The reaction was carried out at 68°C for 2.8 h to obtain a prepolymer solution. A 22 wt.% solution of trimethylolpropane in dimethylacetamide was added dropwise to the prepolymer solution to obtain reaction solution F. The mass ratio of alkyl to hydroxyl-terminated polydimethylsiloxane was approximately 0.12:1. The mixture was reacted at 88°C for 4.5 h to obtain a dispersion. The dispersion was cooled to 58°C, and zwitterionic polymer-modified boron nitride and a supported cooling agent were added sequentially. The mass ratio of zwitterionic polymer-modified boron nitride to the dispersion was 0.22:1, and the mass ratio of the supported cooling agent to zwitterionic polymer-modified boron nitride was 0.18:1. Dimethylacetamide was added to adjust the solid content to 32% to obtain reaction solution G. After maintaining the temperature for 1.9 h, the mixture was sheared and dispersed to obtain a functional modified slurry.

[0068] S4: Thermoplastic polyurethane is added to dimethylacetamide to obtain a matrix solution with a mass fraction of 32%. A functional modified sizing agent is added to obtain a spinning solution, wherein the mass ratio of the functional modified sizing agent to the matrix solution is 12:100. Vacuum degassing is performed to obtain the spinning solution. The spinning solution is extruded through a spinneret into a coagulation bath to obtain nascent fibers. The volume ratio of dimethylacetamide to deionized water in the coagulation bath is 18:100, and the temperature of the coagulation bath is 32℃. The nascent fibers are drawn and heat-set through a drying tunnel to obtain preliminary fibers, wherein the draw ratio is 2.8 times, the heat-setting temperature is 115℃, the holding time is 80s, and oiling and winding are performed to obtain cool-feeling polyurethane elastic fibers.

[0069] Example 2

[0070] This embodiment provides a cooling polyurethane elastic fiber and its preparation method. The preparation method of the cooling polyurethane elastic fiber specifically includes the following steps:

[0071] S1: Boron nitride nanosheets were dispersed in a mixed solution to obtain a boron nitride dispersion, wherein the mass-to-volume ratio of boron nitride nanosheets to ethanol aqueous solution was 1 g:50 mL, and the volume ratio of ethanol to deionized water in the mixed solution was 4:1. A silane coupling agent was added to obtain reaction solution A, wherein the silane coupling agent was KH-570, and the mass ratio of silane coupling agent to boron nitride nanosheets was 0.2:1. The pH value was adjusted to 4 using a 5 wt.% acetic acid solution to obtain reaction solution B, which was then reacted at 60℃. The mixture was refluxed for 6 hours, centrifuged, washed, and dried to obtain modified boron nitride. The modified boron nitride was dispersed in deionized water, and sulfobetaine methacrylate and ammonium persulfate were added to obtain reaction solution C, wherein the mass ratio of sulfobetaine methacrylate to modified boron nitride was 0.1:1, and the mass ratio of ammonium persulfate to sulfobetaine methacrylate was 0.01:1. The mixture was stirred at 55°C for 4 hours under a nitrogen atmosphere, and after dialysis and freeze-drying, zwitterionic polymer-modified boron nitride was obtained.

[0072] S2: L-menthol and lauric acid were mixed in a molar ratio of 1:1 and magnetically stirred at 40°C for 1 h to obtain a eutectic solvent; hollow silica microspheres were impregnated in the eutectic solvent to obtain mixture D, wherein the mass ratio of hollow silica microspheres to eutectic solvent was 1:0.8, and vacuum impregnated at a pressure of -0.08 MPa for 2 h. After removal, the mixture was sprayed with anhydrous ethanol to remove the free eutectic solvent on the particle surface, and then dried at 30°C to obtain a loaded cooling agent;

[0073] S3: Hydroxyl-terminated polydimethylsiloxane was added to dimethylacetamide to obtain dispersion D, wherein the mass ratio of hydroxyl-terminated polydimethylsiloxane to dimethylacetamide was 1:2. Diphenylmethane diisocyanate was added under nitrogen protection to obtain reaction solution E, wherein the molar ratio of diphenylmethane diisocyanate to hydroxyl-terminated polydimethylsiloxane was 2.5:1. The reaction was carried out at 60°C for 2 hours to obtain a prepolymer solution. A 15 wt.% solution of trimethylolpropane in dimethylacetamide was added dropwise to the prepolymer solution to obtain reaction solution F. The mass ratio of propane to hydroxyl-terminated polydimethylsiloxane is approximately 0.08:1. The mixture is reacted at 80°C for 3 hours to obtain a dispersion. The dispersion is cooled to 50°C, and zwitterionic polymer-modified boron nitride and a supported cooling agent are added sequentially. The mass ratio of zwitterionic polymer-modified boron nitride to the dispersion is 0.1:1, and the mass ratio of the supported cooling agent to zwitterionic polymer-modified boron nitride is 0.1:1. Dimethylacetamide is added to adjust the solid content to 25% to obtain reaction solution G. After maintaining the temperature for 1 hour, the mixture is sheared and dispersed to obtain a functional modified slurry.

[0074] S4: Thermoplastic polyurethane is added to dimethylacetamide to obtain a matrix solution with a mass fraction of 20%. A functional modified sizing agent is added to obtain a spinning solution, wherein the mass ratio of the functional modified sizing agent to the matrix solution is 8:100. Vacuum degassing is performed to obtain the spinning solution. The spinning solution is extruded through a spinneret into a coagulation bath to obtain nascent fibers. The volume ratio of dimethylacetamide to deionized water in the coagulation bath is 10:100, and the temperature of the coagulation bath is 25℃. The nascent fibers are drawn and heat-set through a drying tunnel to obtain preliminary fibers, wherein the draw ratio is 2.0 times, the heat-setting temperature is 100℃, the holding time is 30s, and oiling and winding are performed to obtain cool-feeling polyurethane elastic fibers.

[0075] Example 3

[0076] This embodiment provides a cooling polyurethane elastic fiber and its preparation method. The preparation method of the cooling polyurethane elastic fiber specifically includes the following steps:

[0077] S1: Boron nitride nanosheets were dispersed in a mixed solution to obtain a boron nitride dispersion, wherein the mass-to-volume ratio of boron nitride nanosheets to ethanol aqueous solution was 1 g:60 mL, and the volume ratio of ethanol to deionized water in the mixed solution was 6:1. A silane coupling agent was added to obtain reaction solution A, wherein the silane coupling agent was KH-570, and the mass ratio of silane coupling agent to boron nitride nanosheets was 0.25:1. The pH value was adjusted to 4.2 using a 6 wt.% acetic acid solution to obtain reaction solution B. The solution was then heated at 65°C. The mixture was refluxed at ℃ for 8 h, centrifuged, washed, and dried to obtain modified boron nitride. The modified boron nitride was dispersed in deionized water, and sulfobetaine methacrylate and ammonium persulfate were added to obtain reaction solution C, wherein the mass ratio of sulfobetaine methacrylate to modified boron nitride was 0.15:1, and the mass ratio of ammonium persulfate to sulfobetaine methacrylate was 0.02:1. The mixture was stirred at 60 ℃ for 5 h under a nitrogen atmosphere, and after dialysis and freeze-drying, zwitterionic polymer-modified boron nitride was obtained.

[0078] S2: L-menthol and lauric acid were mixed at a molar ratio of 1.1:1 and magnetically stirred at 42°C for 1.2 h to obtain a eutectic solvent; hollow silica microspheres were impregnated in the eutectic solvent to obtain mixture D, wherein the mass ratio of hollow silica microspheres to eutectic solvent was 1:0.9. The mixture was vacuum impregnated at a pressure of -0.085 MPa for 2.5 h, and then sprayed with anhydrous ethanol to remove the free eutectic solvent on the particle surface. The mixture was then dried at 32°C to obtain a loaded cooling agent.

[0079] S3: Hydroxyl-terminated polydimethylsiloxane was added to dimethylacetamide to obtain dispersion D, wherein the mass ratio of hydroxyl-terminated polydimethylsiloxane to dimethylacetamide was 1:2.5. Diphenylmethane diisocyanate was added under nitrogen protection to obtain reaction solution E, wherein the molar ratio of diphenylmethane diisocyanate to hydroxyl-terminated polydimethylsiloxane was 2.8:1. The reaction was carried out at 62°C for 2.2 h to obtain a prepolymer solution. A 18 wt.% solution of trimethylolpropane in dimethylacetamide was added dropwise to the prepolymer solution to obtain reaction solution F. The mass ratio of propane to hydroxyl-terminated polydimethylsiloxane was approximately 0.1:1. The mixture was reacted at 82°C for 3.5 h to obtain a dispersion. The dispersion was cooled to 52°C, and zwitterionic polymer-modified boron nitride and a supported cooling agent were added sequentially. The mass ratio of zwitterionic polymer-modified boron nitride to the dispersion was 0.15:1, and the mass ratio of the supported cooling agent to zwitterionic polymer-modified boron nitride was 0.12:1. Dimethylacetamide was added to adjust the solid content to 28% to obtain reaction solution G. After maintaining the temperature for 1.1 h, the mixture was sheared and dispersed to obtain a functional modified slurry.

[0080] S4: Thermoplastic polyurethane is added to dimethylacetamide to obtain a matrix solution with a mass fraction of 25%. A functional modified sizing agent is added to obtain a spinning solution, wherein the mass ratio of the functional modified sizing agent to the matrix solution is 10:100. Vacuum degassing is performed to obtain the spinning solution. The spinning solution is extruded through a spinneret into a coagulation bath to obtain nascent fibers. The volume ratio of dimethylacetamide to deionized water in the coagulation bath is 12:100, and the temperature of the coagulation bath is 28℃. The nascent fibers are drawn and then heat-set through a drying tunnel to obtain preliminary fibers, wherein the draw ratio is 2.2 times, the heat-setting temperature is 105℃, the holding time is 50s, and oiling and winding are performed to obtain cool-feeling polyurethane elastic fibers.

[0081] Example 4

[0082] This embodiment provides a cooling polyurethane elastic fiber and its preparation method. The preparation method of the cooling polyurethane elastic fiber specifically includes the following steps:

[0083] S1: Boron nitride nanosheets were dispersed in a mixed solution to obtain a boron nitride dispersion, wherein the mass-to-volume ratio of boron nitride nanosheets to ethanol aqueous solution was 1 g:100 mL, and the volume ratio of ethanol to deionized water in the mixed solution was 9:1. A silane coupling agent was added to obtain reaction solution A, wherein the silane coupling agent was KH-570, and the mass ratio of silane coupling agent to boron nitride nanosheets was 0.4:1. The pH value was adjusted to 5 using a 10 wt.% acetic acid solution to obtain reaction solution B, which was then reacted at 75℃. The mixture was refluxed for 12 hours, centrifuged, washed, and dried to obtain modified boron nitride. The modified boron nitride was dispersed in deionized water, and sulfobetaine methacrylate and ammonium persulfate were added to obtain reaction solution C, wherein the mass ratio of sulfobetaine methacrylate to modified boron nitride was 0.3:1, and the mass ratio of ammonium persulfate to sulfobetaine methacrylate was 0.05:1. The mixture was stirred at 70°C for 8 hours under a nitrogen atmosphere, and after dialysis and freeze-drying, zwitterionic polymer-modified boron nitride was obtained.

[0084] S2: L-menthol and lauric acid were mixed at a molar ratio of 1.5:1 and magnetically stirred at 50°C for 2 hours to obtain a eutectic solvent; hollow silica microspheres were impregnated in the eutectic solvent to obtain mixture D, wherein the mass ratio of hollow silica microspheres to eutectic solvent was 1:1.2. The mixture was vacuum impregnated at a pressure of -0.1 MPa for 4 hours, and then sprayed with anhydrous ethanol to remove the free eutectic solvent on the surface of the particles. Finally, it was dried at 40°C to obtain a loaded cooling agent.

[0085] S3: Hydroxyl-terminated polydimethylsiloxane was added to dimethylacetamide to obtain dispersion D, wherein the mass ratio of hydroxyl-terminated polydimethylsiloxane to dimethylacetamide was 1:4. Diphenylmethane diisocyanate was added under nitrogen protection to obtain reaction solution E, wherein the molar ratio of diphenylmethane diisocyanate to hydroxyl-terminated polydimethylsiloxane was 3.5:1. The reaction was carried out at 70°C for 3 hours to obtain a prepolymer solution. A 25 wt.% solution of trimethylolpropane in dimethylacetamide was added dropwise to the prepolymer solution to obtain reaction solution F. The mass ratio of propane to hydroxyl-terminated polydimethylsiloxane is approximately 0.15:1. The mixture is reacted at 90℃ for 5 hours to obtain a dispersion. The dispersion is cooled to 60℃, and zwitterionic polymer-modified boron nitride and a supported cooling agent are added sequentially. The mass ratio of zwitterionic polymer-modified boron nitride to the dispersion is 0.25:1, and the mass ratio of the supported cooling agent to zwitterionic polymer-modified boron nitride is 0.2:1. Dimethylacetamide is added to adjust the solid content to 35% to obtain reaction solution G. After maintaining the temperature for 2 hours, the mixture is sheared and dispersed to obtain a functional modified slurry.

[0086] S4: Thermoplastic polyurethane is added to dimethylacetamide to obtain a matrix solution with a mass fraction of 35%. A functional modified sizing agent is added to obtain a spinning solution, wherein the mass ratio of the functional modified sizing agent to the matrix solution is 15:100. Vacuum degassing is performed to obtain the spinning solution. The spinning solution is extruded through a spinneret into a coagulation bath to obtain nascent fibers. The volume ratio of dimethylacetamide to deionized water in the coagulation bath is 20:100, and the temperature of the coagulation bath is 35℃. The nascent fibers are drawn and heat-set through a drying tunnel to obtain preliminary fibers, wherein the draw ratio is 3.0 times, the heat-setting temperature is 120℃, the holding time is 90s, and oiling and winding are performed to obtain cool-feeling polyurethane elastic fibers.

[0087] Comparative Example 1

[0088] This comparative example provides a cooling polyurethane elastic fiber and its preparation method. The difference from Example 1 is that unmodified boron nitride nanosheets are used to replace zwitterionic polymer-modified boron nitride. Other operating steps and process parameters are exactly the same as in Example 1.

[0089] Comparative Example 2

[0090] This comparative example provides a cooling polyurethane elastic fiber and its preparation method. The difference from Example 1 is that modified boron nitride is used instead of zwitterionic polymer-modified boron nitride. Other operating steps and process parameters are exactly the same as in Example 1.

[0091] Comparative Example 3

[0092] This comparative example provides a cooling polyurethane elastic fiber and its preparation method. The difference from Example 1 is that L-menthol is used to replace the loaded cooling agent, while the other operating steps and process parameters are exactly the same as in Example 1.

[0093] Comparative Example 4

[0094] This comparative example provides a cooling polyurethane elastic fiber and its preparation method. The difference from Example 1 is that step S3 is omitted, and the zwitterionic polymer-modified boron nitride and the supported cooling agent are directly added to the matrix solution. Other operation steps and process parameters are exactly the same as in Example 1.

[0095] Comparative Example 5

[0096] This comparative example provides a cooling polyurethane elastic fiber and its preparation method. The difference from Example 1 is that no loaded cooling agent is added, but the other operating steps and process parameters are exactly the same as those in Example 1.

[0097] Comparative Example 6

[0098] This comparative example provides a cooling polyurethane elastic fiber and its preparation method. The difference from Example 1 is that boron nitride modified with zwitterionic polymer is not added, while other operation steps and process parameters are exactly the same as in Example 1.

[0099] The performance of the cool-feeling polyurethane elastic fibers of Examples 1-4 and Comparative Examples 1-6 was tested, and the specific process is as follows:

[0100] According to GB / T 35263-2017, the contact cooling performance of the samples was tested in dry, wet and after 100 washing cycles.

[0101] The thermal conductivity of the sample in dry and wet conditions was measured according to GB / T 22588-2008.

[0102] According to GB / T 14337-2022, the fracture strength and elastic recovery rate at 100% elongation of the test samples were measured.

[0103] The test results are shown in Table 1.

[0104] Table 1. Test results of the cooling polyurethane elastic fiber properties of Examples 1-4 and Comparative Examples 1-6

[0105]

[0106] As shown in Table 1, the test results of Example 1 and Comparative Example 1 reveal that replacing zwitterionic polymer-modified boron nitride with unmodified boron nitride nanosheets results in poor interfacial compatibility between the unmodified boron nitride and the polyurethane matrix. The lack of surface regulation from the silane coupling layer and the zwitterionic polymer layer leads to easy agglomeration of the filler in the system, preventing the continuous construction of thermal conductivity pathways. Under humid conditions, filler agglomeration exacerbates interfacial debonding, further disrupting the heat diffusion path, thus reducing both thermal conductivity and the contact cooling coefficient. Agglomerates form microcrack initiation points, decreasing the fiber's tensile strength and elastic recovery rate. The lack of a stable interface makes the filler prone to migration or detachment during washing cycles, resulting in reduced cooling retention.

[0107] As shown in Table 1, the test results of Example 1 and Comparative Example 2 reveal that while silane modification improves the initial wettability of boron nitride by replacing it with modified boron nitride modified with zwitterionic polymer, the lack of a hydrated swelling layer from the zwitterionic polymer results in insufficient interfacial stability of the filler in the wet state, leading to microscopic debonding and a decrease in wet thermal conductivity and wet contact cooling coefficient. Weak interfacial interactions and insufficient filler dispersion uniformity further reduce fiber mechanical properties and recovery rate. During washing cycles, the filler is more prone to migration, exacerbating the cooling effect attenuation.

[0108] As shown in Table 1, the test results of Example 1 and Comparative Example 3 reveal that replacing the loaded cooling agent with L-menthol directly results in a higher initial contact cooling coefficient due to the lack of physical encapsulation by hollow silica. This leads to a decrease in cooling sensation during wet conditions and after washing, despite the slightly higher initial contact cooling coefficient. Menthol migration and evaporation cause fluctuations in micropores and phase distribution, indirectly reducing the stability of the wet heat transfer path. Furthermore, the uncontrolled release of menthol leads to the loss of some active substances during fiber forming, resulting in a decrease in the durability of the cooling sensation.

[0109] As shown in Table 1, the test results of Example 1 and Comparative Example 4 reveal that, omitting step S3 and directly adding the zwitterionic polymer-modified boron nitride and the supported cooling agent to the matrix solution results in a lack of compatibilizer. Consequently, the zwitterionic polymer-modified boron nitride and the supported cooling agent cannot be stably coated and dispersed, leading to aggregation in the matrix, increased interfacial voids, and a decrease in thermal conductivity, cooling coefficient, and washability. The lack of compatibilizer also results in insufficient bonding between multiphase materials, low stress transfer efficiency during fiber stretching, and consequently, reduced breaking strength and elastic recovery rate.

[0110] As shown in Table 1, the test results of Example 1 and Comparative Example 5 indicate that without the addition of a loaded cooling agent, the fiber lacks a continuous source of cooling sensation, resulting in a decrease in the contact cooling coefficient and a limited increase in the wet state. Due to the reduction in hollow silica microspheres and their carried eutectic phase in the system, the fiber matrix has a more complete continuous phase, slightly increased thermal conductivity, and fewer interface defects and local pores, leading to more efficient stress transfer. Therefore, the breaking strength and elastic recovery rate do not change significantly. Simultaneously, due to the lack of a slow-release contribution from the cooling agent, although the cooling sensation retention is relatively stable after washing cycles, its absolute cooling level is still insufficient.

[0111] As shown in Table 1, the test results of Example 1 and Comparative Example 6 reveal that boron nitride without zwitterionic polymer modification lacks a continuous, highly thermally conductive filler skeleton within the fiber, resulting in decreased thermal conductivity in both dry and wet states, leading to insufficient heat dissipation upon contact. Its contact cooling sensation primarily relies on the slow-release stimulation of the cold receptor by menthol, lacking the rapid heat transfer brought about by enhanced thermal conductivity, thus reducing both dry and wet contact cooling sensations. Furthermore, the absence of thermally conductive filler reduces the inorganic rigid phase in the system, theoretically reducing stress concentration caused by the filler. However, the system still contains a hollow silica load system, and the lack of interface regulation and dispersion synergy brought about by zwitterionic polymer-modified boron nitride means that micropores and local inhomogeneities may still exist at the multiphase interface, resulting in no improvement in breaking strength and elastic recovery rate. Simultaneously, the lack of a humidity-responsive thermal conduction pathway leads to a decrease in both contact cooling sensation and wet thermal conductivity after washing.

[0112] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a cooling polyurethane elastic fiber, characterized in that, The preparation method includes: S1: Boron nitride nanosheets were dispersed in a mixed solution to obtain a boron nitride dispersion. A silane coupling agent was added to obtain reaction solution A. The pH value was adjusted using acetic acid solution to obtain reaction solution B. The reaction was refluxed, centrifuged, washed, and dried to obtain modified boron nitride. Modified boron nitride was dispersed in deionized water, and sulfobetaine methacrylate and ammonium persulfate were added to obtain reaction solution C. The reaction was stirred under a nitrogen atmosphere, and boron nitride modified with zwitterionic polymer was obtained by dialysis and freeze-drying. S2: L-menthol and lauric acid are mixed and magnetically stirred to obtain a eutectic solvent; hollow silica microspheres are immersed in the eutectic solvent to obtain mixture D, which is then vacuum impregnated, removed, sprayed with anhydrous ethanol, and subsequently dried to obtain a loaded cooling agent. S3: Hydroxyl-terminated polydimethylsiloxane was added to dimethylacetamide to obtain dispersion D. Diphenylmethane diisocyanate was added under nitrogen protection to obtain reaction solution E. The reaction yielded a prepolymer solution. Trimethylolpropane dimethylacetamide solution was added dropwise to the prepolymer solution to obtain reaction solution F. The reaction yielded a dispersion. The dispersion was cooled, and zwitterionic polymer-modified boron nitride and a supported cooling agent were added sequentially. Dimethylacetamide was added to adjust the solid content to obtain reaction solution G. After heat preservation, the mixture was sheared and dispersed to obtain a functional modified slurry. S4: Add thermoplastic polyurethane to dimethylacetamide to obtain a matrix solution, add functional modified slurry to obtain a spinning solution, and degas under vacuum to obtain a spinning solution; extrude the spinning solution through a spinneret into a coagulation bath to obtain nascent fibers, stretch the nascent fibers and heat-set them through a drying tunnel to obtain preliminary fibers, and then oil and wind them to obtain cool-feeling polyurethane elastic fibers.

2. The method for preparing a cooling polyurethane elastic fiber according to claim 1, characterized in that, In S1: The mass-to-volume ratio of the boron nitride nanosheets to the mixed solution is 1 g:(50-100) mL; The volume ratio of ethanol to deionized water in the mixed solution is (4-9):1; The mass ratio of the silane coupling agent to the boron nitride nanosheets is (0.2-0.4):

1.

3. The method for preparing a cooling polyurethane elastic fiber according to claim 1, characterized in that, In S1: The mass ratio of the sulfobetaine methacrylate to the modified boron nitride is (0.1-0.3):1; The mass ratio of ammonium persulfate to sulfobetaine methacrylate is (0.01-0.05):

1.

4. The method for preparing a cooling polyurethane elastic fiber according to claim 1, characterized in that, In S2: The molar ratio of L-menthol to lauric acid is (1-1.5):1; The mass ratio of the hollow silica microspheres to the eutectic solvent is 1:(0.8-1.2).

5. The method for preparing a cooling polyurethane elastic fiber according to claim 1, characterized in that, In S3: The mass ratio of the terminal hydroxyl polydimethylsiloxane to dimethylacetamide is 1:(2-4); The molar ratio of diphenylmethane diisocyanate to hydroxyl-terminated polydimethylsiloxane is (2.5-3.5):

1.

6. The method for preparing a cooling polyurethane elastic fiber according to claim 1, characterized in that, In S3: The concentration of the trimethylolpropane-dimethylacetamide solution is 15-25 wt.%. The mass ratio of trimethylolpropane to hydroxyl-terminated polydimethylsiloxane is (0.08-0.15):

1.

7. The method for preparing a cooling polyurethane elastic fiber according to claim 1, characterized in that, In S3: The mass ratio of the zwitterionic polymer-modified boron nitride to the dispersion is (0.1-0.25):1; The mass ratio of the supported cooling agent to the zwitterionic polymer-modified boron nitride is (0.1-0.2):

1.

8. The method for preparing a cooling polyurethane elastic fiber according to claim 1, characterized in that, In S4: The mass ratio of the functional modified slurry to the matrix solution is (8-15):100; The volume ratio of dimethylacetamide to deionized water in the coagulation bath is (10-20):

100.

9. The method for preparing a cooling polyurethane elastic fiber according to claim 1, characterized in that, In S4: The stretching ratio is 2.0-3.0 times.

10. The method for preparing a cooling polyurethane elastic fiber according to claim 1, characterized in that, In S4: The initial heat setting temperature of the fibers is 100-120℃.

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