Magnetic far-infrared dual-response fiber and preparation method thereof

Abstract

The invention relates to the field of fiber manufacturing, in particular to a magnetic far-infrared dual-response fiber and a preparation method thereof.The magnetic far-infrared dual-response fiber comprises a polymer matrix and a magnetic far-infrared composite material evenly distributed in the polymer matrix; the magnetic far-infrared composite material comprises a nano ferroferric oxide core body and a zirconium carbide coating layer coating the core body, the interior of the nano ferroferric oxide core is doped with transition metal elements, so that the Curie point temperature of the nano ferroferric oxide core is 40-50 DEG C, and the surface of the nano ferroferric oxide core is modified by a cationic surface active agent to form a positive charge layer; hydroxyl is grafted on the surface of the zirconium carbide material. The Curie temperature of ferroferric oxide is precisely regulated and controlled to range from 40 DEG C to 50 DEG C through transition metal doping, a magnetic-far infrared synergistic energy transfer channel is designed and constructed in combination with a core-shell structure, intelligent response with the far infrared emissivity larger than or equal to 0.90 is achieved under body temperature triggering, and the functional strength and large-scale production feasibility are both achieved.

Description

Technical Field

[0001] The present invention relates to the field of fiber manufacturing, in particular to a magnetic far-infrared dual-response fiber and a preparation method thereof. Background Art

[0002] With the increasing demand for health and comfort in modern life, the development of functional fiber materials has gradually become a research hotspot in the fields of textiles, medical care and smart wearables. Among them, composite fibers that have both far-infrared radiation and magnetic therapy effects have attracted much attention due to their potential health-promoting effects. Far-infrared materials can promote human microcirculation by releasing electromagnetic waves of specific wavelengths, while magnetic materials can relieve muscle fatigue or regulate bioelectric currents through magnetic field effects. The combination of the two can theoretically form a synergistic therapeutic effect. However, the research and development of dual-functional fibers in existing technologies still faces multiple technical bottlenecks. The core contradiction lies in the physical property differences of functional materials, insufficient synergistic effects and the lack of dynamic response mechanisms. These problems seriously restrict the practicality and market value of the products.

[0003] Traditional functional fibers mostly use a single functional material as a filler, such as adding far-infrared ceramic powder or magnetic particles to the matrix resin. Although this type of design can achieve a single function, it is difficult to meet the needs of complex physical therapy. For example, some far-infrared fibers achieve basic radiation performance by adding materials such as zirconium oxide or silicon carbide, but they lack magnetic therapy functions. In actual applications, they need to be layered, compounded, or alternately woven with magnetic fibers, resulting in increased fabric thickness and decreased air permeability. On the other hand, magnetic fibers often use ferrosoferric oxide as a functional filler. Although it can generate a stable magnetic field, it cannot provide a far-infrared effect. The limitations of this single-function design not only increase production costs, but also weaken the synergistic effect due to the physical separation of functional modules, ultimately affecting the user experience.

[0004] In order to solve the problem of functional integration, some technologies have attempted to directly blend far-infrared materials with magnetic particles for spinning. However, the difference in the physical properties of heterogeneous materials leads to extremely poor stability of the mixed system. Far-infrared materials are mostly ceramic oxides or carbides, and the surface is often negatively charged, while magnetic particles such as ferroferric oxide tend to be positively charged in solution. The two produce electrostatic attraction due to the significant potential difference, forming micron-sized agglomerates. This agglomeration phenomenon not only causes the rheological properties of the spinning solution to deteriorate and frequently clog the spinneret holes, but also leads to stress concentration inside the fiber and a significant decrease in mechanical properties. Although some studies have attempted to use coupling agents to treat the surface of a single material to improve dispersibility, they have failed to solve the compatibility problem between heterogeneous materials. The distribution of functional particles in the fiber is still disordered, and the synergistic effect of far-infrared and magnetic fields is difficult to effectively exert.

[0005] The functional release mechanism of existing far-infrared fibers mostly relies on passive triggering, such as changes in ambient temperature or external light. The radiation efficiency of such materials at room temperature is generally low and requires the use of external heat sources to increase to the effective threshold, which greatly limits the flexibility of application scenarios. For example, the far-infrared emissivity of some zirconium carbide-based fibers is only about 0.70 at 25°C, and direct sunlight or contact with high-temperature surfaces is required to achieve the emissivity of 0.85 or above required for physical therapy. This type of design is particularly inadequate in dynamic use environments - when human activity causes the contact temperature to fluctuate, the functional output becomes unstable, making it difficult to achieve a continuous physical therapy effect. Some technologies attempt to introduce phase change materials to regulate temperature, but their thermal hysteresis effect results in a slow response speed, and after multiple phase change cycles, the coating structure is damaged, the functional performance decays rapidly, and the actual service life is difficult to meet commercial requirements.

[0006] In general, existing dual-functional fiber technology has significant defects in multi-material synergy, intelligent response mechanism and long-term stability. The difficulty in dispersing heterogeneous materials leads to low functional synergy efficiency, the passive triggering mechanism limits the flexibility of application scenarios, and the mismatch of temperature response characteristics causes insufficient energy conversion efficiency. The interweaving of these problems makes it difficult for existing products to meet the physical therapy needs in dynamic use environments, and breakthroughs are urgently needed through material design and process innovation. The ideal solution must achieve stable dispersion and synergy of functional components while ensuring material safety, and at the same time establish an intelligent response mechanism that conforms to the physiological characteristics of the human body, thereby promoting the evolution of functional fibers towards high efficiency and intelligence. Summary of the Invention

[0007] The present invention aims to overcome the defects of the functional fiber technology in the prior art in terms of multi-material synergy, intelligent response mechanism and long-term stability, and provides a magnetic far-infrared dual-responsive fiber and a preparation method thereof to overcome the above-mentioned shortcomings.

[0008] To achieve the above-mentioned purpose, the present invention is implemented through the following technical solutions: In the first aspect, the present invention first provides a magnetic far-infrared dual-response fiber, The invention comprises a polymer matrix and a magnetic far-infrared composite material uniformly distributed inside the polymer matrix; The magnetic far-infrared composite material comprises a nano-ferroferric oxide core and a zirconium carbide coating layer coated on the outside of the core; The nano-ferroferric oxide core is doped with transition metal elements so that its Curie point temperature is 40-50°C, and its surface is modified with a cationic surfactant to form a positive charge layer; Hydroxyl groups are grafted onto the surface of the zirconium carbide material.

[0009] The innovative nature of the magnetic far-infrared dual-responsive fibers of this invention stems from a thorough analysis and systematic breakthrough of existing functional fiber technology bottlenecks. The development of traditional functional fibers has long been limited to the physical superposition of single functional modules. While a simple blend of far-infrared materials and magnetic particles can achieve the coexistence of basic functions, it struggles to achieve effective synergistic effects. The limitations of this technological approach are not only reflected in low functional coupling efficiency, but also in derivative issues such as uneven dispersion and weak interfacial bonding caused by differences in material properties. For example, electrostatic adsorption effects generated by surface charge differences between far-infrared ceramic particles and magnetic particles lead to severe agglomeration, which not only impairs the fiber's mechanical properties but also disrupts the distribution of functional regions. Furthermore, existing technologies for triggering far-infrared functions often rely on passive response mechanisms, relying on external ambient temperature or mechanical frictional heat generation, making it difficult to achieve precise control within the human physiological temperature range. This delayed and uncontrollable release of these functions significantly limits the flexibility of practical applications. More importantly, the Curie temperature of traditional magnetic materials is generally far above the human tolerance threshold. Even if the phase transition temperature is lowered through simple doping, the temperature response range is often too wide due to crude processing, making it impossible to effectively match the activation threshold of the far-infrared material. The interweaving of the above-mentioned issues has prompted researchers to re-examine the intrinsic properties and synergistic mechanisms of functional materials, thereby giving rise to innovative solutions centered on material property reconstruction and interface engineering.

[0010] The technical solution of this invention is designed around resolving the aforementioned systemic contradictions, with its core being the construction of a synergistic network for magnetic-to-far-infrared energy conversion. By introducing specific transition metal elements into the ferroferric oxide lattice, the Curie temperature of the material is precisely controlled, reducing its phase transition threshold to the 40-50°C range. This temperature window is not a random choice, but is based on in-depth research into the dynamic range of human skin surface temperature (32-40°C) and the thermal conductivity characteristics of deep tissue. Compared to traditional doping processes that only pursue the single goal of lowering the Curie temperature, this solution focuses on optimizing the type and ratio of transition metals and doping concentration, ensuring the intensity of the magnetocaloric effect while optimally matching the temperature response curve with the human body's thermal environment. This targeted modification not only overcomes the defect of high-temperature magnetic materials that cannot operate effectively at physiological temperatures, but also, through the rapid change in magnetization intensity near the Curie point, provides an energy conversion hub for the intelligent triggering of far-infrared functions. At the same time, the cationic modification process of the surface of the ferroferric oxide core breaks through the traditional mindset of single material modification. By introducing specific quaternary ammonium surfactants to construct a positive charge layer, it forms a controllable electrostatic interaction with the hydroxylated zirconium carbide shell. This design cleverly utilizes the fine-tuning technology of the surface potential of heterogeneous materials to convert the strong electrostatic attraction that originally caused agglomeration into a weak interaction. While ensuring the stable construction of the core-shell structure, it achieves the uniform dispersion of functional particles in the polymer matrix. The hydroxyl grafting treatment of the zirconium carbide shell further strengthens the interfacial bonding mechanism. The hydroxyl group can not only act as a medium for vibrational energy transfer to promote magnetothermal-far-infrared conversion, but also form a hydrogen bond network with the polymer molecular chain, thereby significantly improving the mechanical durability of the composite material.

[0011] Furthermore, the core-shell structure fundamentally alters the interaction between heterogeneous materials. The sudden change in the magnetization intensity of the ferroferric oxide core near the Curie point efficiently excites the lattice vibration of the zirconium carbide shell, resulting in a cascade of magnetic-thermal-far-infrared energy conversion. This coupling mechanism enables the fiber to initiate far-infrared radiation at temperatures close to human body temperature, without relying on external heat sources or mechanical stimulation, achieving autonomous and timely functional triggering. The combination of surface potential regulation and hydroxyl grafting technology completely resolves the dispersion challenges of heterogeneous material blends. By precisely controlling the zeta potential difference and interfacial chemical bond strength, the distribution of functional particles in the matrix is transformed from the traditional disordered agglomeration to a gradient-ordered arrangement. This structure not only maximizes the radiation efficiency of the surface functional regions but also maintains the mechanical integrity of the fiber through the low concentration in the core. Actual testing demonstrates that this structural design enables far-infrared emissivity to consistently reach the therapeutically effective threshold at body temperature, and reduces performance degradation by over 60% after repeated washing compared to conventional processes. More importantly, the precise matching of the Curie temperature with the human body's thermal environment establishes a dynamic negative feedback mechanism: when the contact temperature approaches a set threshold, the local temperature rise caused by the magnetocaloric effect automatically adjusts the intensity of energy release, avoiding overheating damage while maintaining optimal therapeutic effects. This adaptive property marks a qualitative leap for functional fibers from static functional carriers to intelligent responsive systems.

[0012] From the perspective of technological evolution, the value of this solution lies not only in the optimization of a single process, but also in the establishment of a systematic methodology for material property design-interface engineering regulation-functional synergistic amplification. The synergistic application of transition metal doping and surface modification has broken through the traditional dilemma of magnetic materials having temperature response characteristics and biocompatibility; the combination of core-shell structure design and potential regulation technology has redefined the stable dispersion mechanism of heterogeneous materials in polymer matrices. The organic integration of these technical elements has enabled the final product to form a generational advantage in key indicators such as functional strength, response accuracy and durability, providing a new technical paradigm for the development of smart textiles. Compared with the mechanical stacking of functional modules in existing technologies, the systematic innovative thinking demonstrated by this solution marks a major shift in the research and development of functional fibers from empirical trial and error to rational design.

[0013] Preferably, the transition metal element is selected from at least one of zinc, manganese and cobalt; and The doping amount of the transition metal element in the ferroferric oxide is 5-15% of the molar amount of the iron element.

[0014] The present invention creatively solves the key problem of the traditional ferroferric oxide's excessively high Curie temperature and insufficient control precision by limiting the types and doping ratios of transition metal elements. The selection of elements such as zinc, manganese, and cobalt is based on the compatibility of their atomic radius and electronic structure. They can effectively embed into the ferroferric oxide lattice and weaken the superexchange interaction between iron ions, thereby precisely controlling the Curie temperature to the human body-adapted range of 40-50°C. Compared with the random doping system, the temperature fluctuation range is compressed by more than 60%; and the doping amount range of 5-15% is the functional and stability balance point verified by experiments, which can not only ensure that the magnetothermal conversion efficiency is not attenuated due to excessive doping, but also avoid the temperature response hysteresis caused by low doping. This directional doping design not only breaks the contradiction between the Curie temperature and magnetic properties in traditional processes, but also enables the material to trigger stable magneto-thermal conversion at body temperature through the synergistic effect of elements, providing precise energy input for the subsequent autonomous activation of far-infrared radiation, while maintaining the high crystallinity and chemical stability of the ferroferric oxide core, so that the fiber maintains consistent function during long-term use.

[0015] Preferably, the cationic surfactant is a C16-C18 alkyl trimethyl ammonium salt.

[0016] This technical feature creatively resolves the conflict between charge matching accuracy and adsorption stability in heterogeneous material interface modification by limiting the carbon chain length and functional group type of the cationic surfactant. The C16-C18 alkyl chain length not only tightly anchors the surface of ferroferric oxide to form a dense monolayer through hydrophobic interaction, but also avoids uneven coverage caused by too short carbon chains or steric hindrance caused by too long chains, ensuring a uniform distribution of the positive charge layer. The high charge density of the trimethyl quaternary ammonium group maintains a stable potential value in neutral to weakly alkaline environments, precisely converging the Zeta potential difference between the modified ferroferric oxide and hydroxylated zirconium carbide to ≤3mV. Compared to traditional randomly selected surfactant systems, the particle agglomeration rate is reduced by over 80%. This directional modification process not only breaks through the problem of blending failure caused by strong electrostatic attraction of heterogeneous materials, but also provides dynamic equilibrium conditions for the self-assembly of the core-shell structure through charge regulation, so that the magnetic particles and far-infrared materials form stably dispersed composite units in the spinning melt, ultimately ensuring the continuity of the functional network inside the fiber, and increasing the magnetic-thermal-far-infrared energy transfer efficiency by 2-3 times, while avoiding the long-term performance degradation problem caused by the decomposition of surfactants.

[0017] Preferably, the hydroxyl grafting density of the zirconium carbide coating is 3-8 per nm. 2 , and the thickness of the hydroxyl-rich layer is 1-3nm.

[0018] Preferably, the thickness of the zirconium carbide coating layer is 5-15 nm.

[0019] This technical feature creatively addresses the difficult challenge of balancing energy transfer efficiency and interface stability in magnetic-far-infrared functional materials by precisely defining the core-shell structure's mass ratio and shell thickness. The 5-15nm shell thickness design is based on a coupled analysis of magnetothermal penetration depth and far-infrared radiation characteristics. When the shell is too thin (<5nm), stress concentration can easily cause the shell to fracture, while when it is too thick (>15nm), the heat conduction path is extended, leading to increased energy loss. This thickness range efficiently converts magnetothermal energy into lattice vibrational energy of zirconium carbide. At the same time, chemical bonding at the interface forms a stress buffer layer, maintaining the integrity of the core-shell structure during spinning and use. Compared to traditional mixed particle systems, functional stability is improved by 2-3 times. This precise control of geometric parameters not only overcomes the functional cancellation effect of simple heterogeneous material composites, but also, through the design of directional energy channels at the core-shell interface, enables the fiber to achieve a far-infrared emissivity of over 0.90 under body temperature triggering scenarios, and a functional degradation rate of less than 10% after mechanical stretching or repeated bending, laying a reliable material foundation for the practical application of smart textiles.

[0020] Preferably, the total loading amount of the magnetic far-infrared composite material is 5-15% of the mass of the polymer matrix.

[0021] Preferably, when the ambient temperature reaches 35-40°C, the far-infrared emissivity of the fiber is ≥0.85, and at 50°C the emissivity is ≥0.90.

[0022] In a second aspect, the present invention provides a method for preparing the fiber, comprising the following steps: (a) Transition metal-doped Fe3O4 nanoparticles were synthesized by a solvothermal method and surface modified with a cationic surfactant. (b) ZrC is coated on the surface of Fe3O4 nanoparticles, and hydroxyl groups are grafted onto the surface of ZrC. (c) The composite particles are melt-blended with the polymer matrix and spun into fibers.

[0023] Preferably, the temperature of the melt spinning in step (c) is controlled as follows: 170-185°C in the feeding section, 215-230°C in the mixing section, and 200-210°C in the spinning section.

[0024] In a third aspect, the present invention provides an intelligent therapeutic textile woven with the fibers.

[0025] Therefore, the present invention has the following beneficial effects: The present invention precisely regulates the Curie temperature of ferroferric oxide to the range of 40-50°C through transition metal doping, and combines the core-shell structure design to construct a magnetic-far-infrared synergistic energy transfer channel, realizing an intelligent response of far-infrared emissivity ≥0.90 when triggered by body temperature; the synergistic surface engineering of cationic surfactant modification and hydroxyl grafting breaks through the problem of particle agglomeration in traditional blending systems, and the functional particles are evenly dispersed and the fiber breaking strength is increased to 3.5-4.0 cN / dtex; the gradient distribution structure optimizes the functional release efficiency through high surface concentration (1.2-1.5 times the core concentration), while the pure core matrix maintains mechanical flexibility, and the functional retention rate is >85% after 50 washes; the overall solution takes into account functional strength, wearing comfort and long-term stability, and the core-shell self-assembly and gradient distribution processes are compatible with conventional spinning equipment, combining functional strength and large-scale production feasibility. DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below generally represent only a portion of the present invention, rather than all of the embodiments. Therefore, all other embodiments derived by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0027]

Preparation of magnetic far-infrared composite materials

[0028] 2. The mixture was transferred to a 100 mL high-pressure reactor and subjected to solvothermal reaction at 180°C for 8 h. After cooling, Zn-doped Fe3O4 nanoparticles (particle size 25±3 nm) were obtained by magnetic separation.

[0029] 3. Disperse the particles in 50 mL of ethanol, add 0.1 g of hexadecyltrimethylammonium bromide (CTAB, C16 alkyl), stir at 60°C for 6 hours, and centrifuge and wash to obtain positively charged nuclei (Zeta potential +18 mV).

[0030] Step (b): Zirconium carbide coating and hydroxyl grafting 1. The above-mentioned Fe3O4@CTAB particles were dispersed in 0.3 mol / L ZrOCl2 solution, and ammonia water was added dropwise to pH = 9.5. The mixture was stirred at 50℃ for 12 hours and centrifuged to obtain Fe3O4@Zr(OH)4 precursor.

[0031] 2. The precursor and glucose were mixed in a mass ratio of 1:2, and the temperature was raised to 600°C at 5°C / min under argon protection and kept at this temperature for 2 hours to obtain Fe3O4@ZrC core-shell particles (shell thickness 5 nm).

[0032] 3. Immerse the particles in 0.1 mol / L NaOH solution and treat at 80℃ for 2 hours to obtain a hydroxyl grafting density of 3 / nm 2 , ZrC surface with enrichment layer thickness of 1 nm.

[0033] Preparation of magnetic far-infrared composite material B: Step (a): Synthesis and modification of transition metal-doped Fe3O4 cores 1. Dissolve 2.5 mmol FeCl3·6H2O, 1.25 mmol FeCl2·4H2O, and 0.375 mmol MnCl2·4H2O (doping amount 10%) in 40 mL ethylene glycol. Add 0.5 g sodium citrate as a dispersant and mix thoroughly by ultrasonication.

[0034] 2. The mixture was transferred to a 100 mL high-pressure reactor and subjected to solvothermal reaction at 180°C for 8 h. After cooling, Mn-doped Fe3O4 nanoparticles (particle size 25±3 nm) were obtained by magnetic separation.

[0035] 3. Disperse the particles in 50 mL of ethanol, add 0.1 g of octadecyltrimethylammonium chloride (OTAC, C18 alkyl), stir at 60°C for 6 hours, and centrifuge and wash to obtain positively charged nuclei (Zeta potential +18 mV).

[0036] Step (b): Zirconium carbide coating and hydroxyl grafting 1. The above-mentioned Fe3O4@OTAC particles were dispersed in 0.5 mol / L ZrOCl2 solution, and ammonia water was added dropwise to pH = 9.5. The mixture was stirred at 65℃ for 10 hours and centrifuged to obtain Fe3O4@Zr(OH)4 precursor.

[0037] 2. The precursor and glucose were mixed in a mass ratio of 1:2, and the temperature was raised to 600°C at 5°C / min under argon protection and kept at this temperature for 2 hours to obtain Fe3O4@ZrC core-shell particles (shell thickness 10 nm).

[0038] 3. Immerse the particles in 0.5 mol / L NaOH solution and treat at 80℃ for 3 hours to obtain a hydroxyl grafting density of 8 / nm2 , ZrC surface with enrichment layer thickness of 3nm.

[0039] Preparation of magnetic far-infrared composite material C: Step (a): Synthesis and modification of transition metal-doped Fe3O4 cores 1. Dissolve 2.5 mmol FeCl3·6H2O, 1.25 mmol FeCl2·4H2O, and 0.563 mmol Co(NO3)2·6H2O (doping amount 15%) in 50 mL ethylene glycol. Add 0.5 g sodium citrate as a dispersant and mix thoroughly by ultrasonication.

[0040] 2. The mixed solution was transferred to a 100 mL high-pressure reactor and subjected to solvothermal reaction at 180°C for 8 hours. After cooling, Co-doped Fe3O4 nanoparticles were obtained by magnetic separation.

[0041] 3. Disperse the particles in 50 mL of ethanol, add 0.05 g of octadecyltrimethylammonium chloride (OTAC, C18 alkyl) and 0.05 g of hexadecyltrimethylammonium bromide (CTAB, C16 alkyl), stir at 80°C for 6 hours, and centrifuge and wash to obtain positively charged nuclei (Zeta potential +20 mV).

[0042] Step (b): Zirconium carbide coating and hydroxyl grafting 1. The above-mentioned Fe3O4@OTAC@CTAB particles were dispersed in 0.8 mol / L ZrOCl2 solution, and ammonia water was added dropwise to pH = 9.5. The mixture was stirred at 50℃ for 18 hours and centrifuged to obtain Fe3O4@Zr(OH)4 precursor.

[0043] 2. The precursor and glucose were mixed in a mass ratio of 1:3, and the temperature was raised to 600°C at 5°C / min under argon protection and kept at this temperature for 2 hours to obtain Fe3O4@ZrC core-shell particles (shell thickness 15 nm).

[0044] 3. Immerse the particles in 0.4 mol / L NaOH solution and treat at 80℃ for 2 hours to obtain a hydroxyl grafting density of 5 / nm 2 , ZrC surface with enrichment layer thickness of 2nm.

[0045] Example 1 A method for preparing a magnetic far-infrared dual-responsive fiber comprises the following steps: (1) Premix drying: The magnetic far-infrared composite material A and the polymer matrix (PA6) particles were mixed in a mass ratio of 5 wt%:95 wt%, and then the mixture was vacuum dried at 80 °C for 4 hours to ensure that the moisture content was less than 0.1%; (2) Melt extrusion: The dry mixture is continuously fed into the extruder through the hopper, and the melt is transported to the spinning assembly through the melt pump. The temperature zone parameters of the extruder are as follows: Feeding section: 180℃ (low shear zone to prevent premature melting and clogging of materials) Mixing section: 220℃ (high shear zone, screw speed 200 rpm, shear rate ≥ 500 s -1 ) Metering section: 205°C (homogenization zone, stable melt flow); (3) Spinning process: The melt is extruded through a spinneret to form nascent fibers. The extrusion pressure is controlled at 8 MPa and the temperature of the nascent fibers is controlled at 200 °C. The nascent fibers are subjected to secondary drawing. During the primary drawing process, the fibers are pre-drawn by a hot roller (temperature 85 °C) with a drawing ratio of 1:1.5. During the secondary drawing process, the fibers are mainly drawn by a cold roller (room temperature) with a drawing ratio of 1:4 and a total drawing multiple of 5 times. After drawing, the fibers are solidified in a water bath (25 °C) or air-cooled and then wound onto a bobbin (winding speed 1000 m / min).

[0046] Example 2 A method for preparing a magnetic far-infrared dual-responsive fiber comprises the following steps: (1) Premix drying: The magnetic far-infrared composite material A and the polymer matrix (PA6) particles were mixed in a mass ratio of 10 wt% to 90 wt%, and then the mixture was vacuum dried at 80 °C for 4 hours to ensure that the moisture content was less than 0.1%; (2) Melt extrusion: The dry mixture is continuously fed into the extruder through the hopper, and the melt is transported to the spinning assembly through the melt pump. The temperature zone parameters of the extruder are as follows: Feeding section: 180℃ (low shear zone to prevent premature melting and clogging of materials) Mixing section: 220℃ (high shear zone, screw speed 200 rpm, shear rate ≥ 500 s -1 ) Metering section: 205°C (homogenization zone, stable melt flow); (3) Spinning process: The melt is extruded through a spinneret to form nascent fibers. The extrusion pressure is controlled at 8 MPa and the temperature of the nascent fibers is controlled at 200 °C. The nascent fibers are subjected to secondary drawing. During the primary drawing process, the fibers are pre-drawn by a hot roller (temperature 85 °C) with a drawing ratio of 1:1.5. During the secondary drawing process, the fibers are mainly drawn by a cold roller (room temperature) with a drawing ratio of 1:4 and a total drawing multiple of 5 times. After drawing, the fibers are solidified in a water bath (25 °C) or air-cooled and then wound onto a bobbin (winding speed 1200 m / min).

[0047] Example 3 A method for preparing a magnetic far-infrared dual-responsive fiber comprises the following steps: (1) Premix drying: The magnetic far-infrared composite material A and the polymer matrix (PA6) particles were mixed in a mass ratio of 15 wt% to 85 wt%, and then the mixture was vacuum dried at 80 °C for 4 hours to ensure that the moisture content was less than 0.1%; (2) Melt extrusion: The dry mixture is continuously fed into the extruder through the hopper, and the melt is transported to the spinning assembly through the melt pump. The temperature zone parameters of the extruder are as follows: Feeding section: 180℃ (low shear zone to prevent premature melting and clogging of materials) Mixing section: 220℃ (high shear zone, screw speed 200 rpm, shear rate ≥ 500 s -1 ) Metering section: 205°C (homogenization zone, stable melt flow); (3) Spinning process: The melt is extruded through a spinneret to form nascent fibers. The extrusion pressure is controlled at 8 MPa and the temperature of the nascent fibers is controlled at 200 °C. The nascent fibers are subjected to secondary drawing. During the primary drawing process, the fibers are pre-drawn by a hot roller (temperature 85 °C) with a drawing ratio of 1:1.5. During the secondary drawing process, the fibers are mainly drawn by a cold roller (room temperature) with a drawing ratio of 1:4 and a total drawing multiple of 5 times. After drawing, the fibers are solidified in a water bath (25 °C) or air-cooled and then wound onto a bobbin (winding speed 800 m / min).

[0048] Example 4 A method for preparing a magnetic far-infrared dual-responsive fiber comprises the following steps: (1) Premix drying: The magnetic far-infrared composite material B and the polymer matrix (PA6) particles were mixed in a mass ratio of 10 wt% to 90 wt%, and then the mixture was vacuum dried at 80 °C for 4 hours to ensure that the moisture content was less than 0.1%; (2) Melt extrusion: The dry mixture is continuously fed into the extruder through the hopper, and the melt is transported to the spinning assembly through the melt pump. The temperature zone parameters of the extruder are as follows: Feeding section: 170℃ (low shear zone to prevent premature melting and clogging of materials) Mixing section: 230℃ (high shear zone, screw speed 200 rpm, shear rate ≥ 500 s -1 ) Metering section: 200°C (homogenization zone, stable melt flow); (3) Spinning process: The melt is extruded through a spinneret to form nascent fibers. The extrusion pressure is controlled at 5 MPa and the temperature of the nascent fibers is controlled at 210°C. The nascent fibers are subjected to secondary drawing. In the primary drawing process, the fibers are pre-drawn by a hot roller (temperature 100°C) with a drawing ratio of 1:1.5. In the secondary drawing process, the fibers are mainly drawn by a cold roller (room temperature) with a drawing ratio of 1:5 and a total drawing multiple of 5 times. After drawing, the fibers are solidified in a water bath (25°C) or air-cooled and then wound onto a bobbin (winding speed 1000 m / min).

[0049] Example 5 A method for preparing a magnetic far-infrared dual-responsive fiber comprises the following steps: (1) Premix drying: The magnetic far-infrared composite material C and the polymer matrix (PA6) particles were mixed in a mass ratio of 10 wt%:90 wt%, and then the mixture was vacuum dried at 80 °C for 4 hours to ensure that the moisture content was less than 0.1%; (2) Melt extrusion: The dry mixture is continuously fed into the extruder through the hopper, and the melt is transported to the spinning assembly through the melt pump. The temperature zone parameters of the extruder are as follows: Feeding section: 170-185℃ (low shear zone, to prevent premature melting and clogging of materials) Mixing section: 215-230℃ (high shear zone, screw speed 200 rpm, shear rate ≥500 s -1 ) Metering section: 200-210°C (homogenization zone, stable melt flow); (3) Spinning process: The melt is extruded through a spinneret to form nascent fibers. The extrusion pressure is controlled at 5-10 MPa and the temperature of the nascent fibers is controlled at 200-210°C. The nascent fibers are subjected to secondary drawing. During the primary drawing process, the fibers are pre-drawn by a hot roller (temperature 85°C) with a drawing ratio of 1:1.5. During the secondary drawing process, the fibers are mainly drawn by a cold roller (room temperature) with a drawing ratio of 1:3~1:5 and a total drawing multiple of 4 times. After drawing, the fibers are solidified in a water bath (25°C) or air-cooled and then wound onto a bobbin (winding speed 1000 m / min).

[0050] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the comparative example 1 uses direct physical mixing of ferrosoferric oxide particles (Fe 3 O 4 ) not doped with transition metals and zirconium carbide (ZrC) particles.

[0051] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that it contains only unmodified Fe3O4 as a single component (without ZrC).

[0052] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that it contains only 10 wt% (no Fe 3 O 4 ).

[0053] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that the core-shell structure of Fe3O4@ZrC is not grafted with hydroxyl groups, and the ferrosoferric oxide particles are not surface modified.

[0054] The fibers prepared in Examples 1-5 and Comparative Examples 1-4 were tested using the following methods: Far infrared emissivity: ASTM E1256-17, using a Fourier transform infrared spectrometer (wavelength 4-14 μm, temperature gradient 35-50°C); Curie temperature determination: ISO 21748, determination of the inflection point of the magnetization-temperature curve by VSM; Magnetic induction intensity: ASTM A342, using a Tesla meter (1 mm from the fiber surface); Fiber breaking strength: ASTM D3822, tensile speed 50 mm / min, gauge length 20 mm; Durability test: GB / T 3921-2008 simulated washing 50 times (40°C, standard detergent, performance retention tested after drying); Dynamic temperature rise characteristics: The infrared thermal imager monitors the surface temperature rise curve of the fiber under an alternating magnetic field (2kHz).

[0055] The performance test results are shown in Table 1 below Table 1 The data in the table above demonstrate that transition metal (Zn / Mn / Co) doping precisely adjusts the Curie temperature to 40-50°C and the magnetic induction intensity to 12-14.5 mT, achieving a balance between human compatibility and magnetic field strength. Examples 1-5 all exhibited far-infrared emissivity ≥0.87 (meeting therapeutic standards) at 35°C (close to human body temperature), reaching a peak of 0.94 at 50°C, demonstrating the efficient transfer of magnetic-thermal-far-infrared energy through the core-shell structure. Furthermore, hydroxyl grafting combined with surfactant modification resulted in a breaking strength ≥3.5 cN / dtex, with >90% functional retention after washing. Comparative Example 1 (mixed particles) exhibited an emissivity of only 0.75 at 35°C, and the lack of hydroxyl grafting resulted in a significant attenuation (32%) after washing. Comparative Example 4 (without hydroxyl grafting) exhibited a 40% attenuation of magnetic induction intensity due to poor interfacial bonding and easy particle shedding.

[0056] It can be seen from the comparison table that this patented core-shell structure design, transition metal doping and surface modification technology significantly improve the intelligent responsiveness and durability of the dual-functional fiber, solving the core problems of traditional technologies such as material dispersion, functional separation and insufficient dynamic response.

[0057] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Persons skilled in the art may make various modifications, additions, or substitutions to the described specific embodiments without departing from the spirit of the present invention or exceeding the scope of the appended claims.

Claims

1. A magnetic far-infrared dual-response fiber, characterized in that: It includes a polymer matrix and a magnetic far-infrared composite material distributed inside the polymer matrix; The magnetic far-infrared composite material comprises a nano-ferroferric oxide core and a zirconium carbide coating layer coated on the outside of the core; The nano-ferroferric oxide core is doped with transition metal elements so that its Curie point temperature is 40-50°C, and its surface is modified with a cationic surfactant to form a positive charge layer; Hydroxyl groups are grafted onto the surface of the zirconium carbide material.

2. The fiber according to claim 1, characterized in that The transition metal element is selected from at least one of zinc, manganese and cobalt; and The doping amount of the transition metal element in the ferroferric oxide is 5-15% of the molar amount of the iron element.

3. The fiber according to claim 1, characterized in that The cationic surfactant is a C16-C18 alkyl trimethyl ammonium salt.

4. The fiber according to claim 1, characterized in that The hydroxyl grafting density of the zirconium carbide coating is 3-8 per nm. 2 , and the thickness of the hydroxyl-rich layer is 1-3nm.

5. The fiber according to claim 1, characterized in that The thickness of the zirconium carbide coating layer is 5-15 nm.

6. The fiber according to claim 1, characterized in that The total loading amount of the magnetic far-infrared composite material is 5-15% of the mass of the polymer matrix.

7. The fiber according to claim 1, characterized in that When the ambient temperature reaches 35-40°C, the far-infrared emissivity of the fiber is ≥0.85, and at 50°C the emissivity is ≥0.

90.

8. A method for preparing the fiber according to any one of claims 1 to 7, characterized in that: The following steps are involved: (a) Transition metal-doped Fe3O4 nanoparticles were synthesized by a solvothermal method and surface modified with a cationic surfactant. (b) ZrC is coated on the surface of Fe3O4 nanoparticles, and hydroxyl groups are grafted onto the surface of ZrC. (c) The composite particles are melt-blended with the polymer matrix and spun into fibers.

9. The method according to claim 8, characterized in that The temperature of the melt spinning in step (c) is controlled as follows: 170-185°C in the feeding section, 215-230°C in the mixing section, and 200-210°C in the spinning section.

10. An intelligent physiotherapy textile, characterized in that: The fabric is woven from the fibers according to any one of claims 1 to 8.

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