Preparation method of hydroxyapatite far-infrared functional fiber
By blending hydroxyapatite ultrafine particles with thermoplastic polymers and preparing functional fibers using melt spinning, the problems of dispersibility, mechanical properties and functional durability of existing fiber materials have been solved. Stable integration of antibacterial and far-infrared functions has been achieved, making it suitable for medical dressings and protective gear.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-25
- Publication Date
- 2026-03-13
AI Technical Summary
Existing functional fiber materials have problems in terms of dispersibility, mechanical properties and functional durability, and traditional antibacterial agents may pose safety hazards, making it difficult to achieve a stable integration of antibacterial and far-infrared functions.
Functional fibers are prepared by blending hydroxyapatite ultrafine particles derived from animal bones or shells with thermoplastic polymers and using a melt spinning process. This ensures the integration of antibacterial and far-infrared functions of the fibers and improves their mechanical properties and durability.
The prepared hydroxyapatite far-infrared functional fiber has excellent biocompatibility, high far-infrared emissivity, high antibacterial rate, and maintains good performance after multiple washings. It also has stable mechanical properties and is suitable for medical dressings and protective gear.
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Figure CN121653871A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of functional fiber materials and textile composite materials, and specifically relates to a method for preparing hydroxyapatite far-infrared functional fibers. Background Technology
[0002] With the increasing demand for health protection, functional clothing, and medical fiber materials, new fiber materials with antibacterial, health-promoting, and far-infrared emission properties have attracted widespread attention. Far-infrared functional fibers can release far-infrared rays that are absorbable by the human body in the 4–14 μm wavelength range, promoting blood circulation and relieving fatigue. At the same time, these fibers can effectively inhibit bacterial growth, prevent skin lesions and odor formation, making them particularly suitable for underwear and medical fabrics.
[0003] Currently, common functional fibers typically achieve far-infrared and antibacterial effects by introducing composite powders such as tourmaline, silver ions, and nano-zinc oxide into the fiber. However, existing technologies have the following prominent problems: First, the composite additive system is mostly a multi-component design, and the physical properties of different functional powders vary greatly, which can easily lead to uneven dispersion and severe agglomeration, affecting spinning stability and fiber mechanical properties; second, some antibacterial components, such as metal ions, pose safety hazards and may cause skin irritation with long-term use; third, some functional coatings are applied by surface spraying or impregnation, which makes it difficult to maintain their function for a long time and they are easily detached during washing and friction.
[0004] In addition, although hydroxyapatite (HAp) is widely used in bone repair and biomedical materials due to its excellent biocompatibility and natural antibacterial properties, there are still few studies on its application as a single functional filler in far-infrared antibacterial fibers. In particular, there are no systematic reports on the preparation of scalable functional fibers based on HAp from natural sources through ultrafine processing, melt blending with thermoplastic polymers, and melt spinning. Summary of the Invention
[0005] To address the shortcomings mentioned in the background art, the present invention aims to provide a method for preparing hydroxyapatite far-infrared functional fibers. This method involves blending hydroxyapatite ultrafine particles derived from animal bones or shells with thermoplastic polymers and then using a melt spinning process to prepare functional fibers. This achieves the integration of antibacterial and far-infrared functions while ensuring good mechanical properties and durability of the fibers, thus meeting the application needs of the health and medical fields.
[0006] The objective of this invention can be achieved through the following technical solutions: A method for preparing hydroxyapatite far-infrared functional fibers includes the following steps: S1. Select animal bones or shells as raw materials, and successively clean, dry and calcine at high temperature to obtain crude hydroxyapatite. The crude product is then processed by air jet milling and wet grinding to prepare hydroxyapatite ultrafine particles with a particle size of 50-200 nm. S2. The hydroxyapatite ultrafine particles and matrix material are added to a high-speed mixer and mixed, followed by melt blending and extrusion granulation to obtain hydroxyapatite / polymer composite particles; S3. After drying, the composite particles are fed into a spinning machine and subjected to melt spinning process. The particles are extruded through a spinneret to form nascent fibers. The nascent fibers are then cooled, stretched, and heat-set to obtain hydroxyapatite far-infrared antibacterial functional fibers.
[0007] More preferably, the high-temperature calcination temperature in step S1 is 800–1200°C, and the time is 2–4 hours.
[0008] More preferably, the matrix material in step S2 is selected from one or more of polyester chips, polylactic acid, and polyvinyl alcohol.
[0009] More preferably, the hydroxyapatite far-infrared functional fiber comprises the following raw materials in parts by weight: 80-95% matrix material and 5-20% hydroxyapatite ultrafine particles.
[0010] More preferably, the mixing temperature in step S2 is 80–120°C, and the mixing time is 10–20 minutes.
[0011] More preferably, in step S2, the melt blending process is set with different temperature ranges according to the different matrix materials. The melt blending temperature of polyester is 230-280°C, the melt blending temperature of polylactic acid is 160-200°C, and the melt blending temperature of polyvinyl alcohol is 180-220°C.
[0012] More preferably, in step S3, the composite particles are dried before spinning, and their moisture content is controlled to be no higher than 0.05%.
[0013] More preferably, in step S3, the cooling temperature of the nascent fiber is 20-30°C, the stretching ratio is 2-5 times, and the stretching temperature is 60-100°C.
[0014] More preferably, in step S3, the heat setting temperature of the fiber during the heat setting stage is 100-150°C, and the heat setting time is 5-10 seconds.
[0015] More preferably, the functional fiber has a far-infrared emissivity of not less than 0.86 in the 4–14 μm band, and an antibacterial rate of not less than 95% against both Escherichia coli and Staphylococcus aureus.
[0016] The beneficial effects of this invention are: The hydroxyapatite used in this invention is naturally derived and possesses excellent biocompatibility, avoiding the risks of irritation to the human body caused by heavy metal ions and chemical residues commonly found in traditional antibacterial agents. It is particularly suitable for applications requiring high biocompatibility, such as medical dressings, protective gear, and therapeutic clothing. Furthermore, the hydroxyapatite particles in this invention undergo ultrafine grinding, with a particle size controlled between 50 and 200 nm, exhibiting good interfacial dispersibility and compatibility with the polymer matrix. This allows for uniform distribution during blending and spinning, significantly improving the mechanical properties and structural stability of the fibers. Simultaneously, this material possesses lattice vibration characteristics, continuously releasing far-infrared radiation in the 4–14 μm wavelength range, which helps promote microcirculation, relieve fatigue, and aid in physical therapy. The Ca²⁺ and PO₄³⁻ released from its surface hydroxyl active sites have a disruptive effect on bacterial cell walls, achieving broad-spectrum physical antibacterial activity. Experimental results show that the far-infrared emissivity of the prepared functional fiber is higher than 0.86, the antibacterial rate against Escherichia coli and Staphylococcus aureus is over 95%, and it maintains good functional performance after multiple washes, exhibiting excellent durability. Attached Figure Description
[0017] The invention will now be further described with reference to the accompanying drawings.
[0018] Figure 1 This is a comparison chart of the antibacterial rates of samples from Examples 1-3 and Comparative Examples 1-2; Figure 2 The graphs show the changes in the antibacterial retention rate of Escherichia coli for samples from Examples 1-3 and Comparative Examples 1-2 with the number of washing cycles. Figure 3 The graph shows a comparison of the fracture strength and elongation at break of the samples from Examples 1-3 and Comparative Examples 1-2. Detailed Implementation
[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0020] Example 1 A method for preparing hydroxyapatite far-infrared functional fibers specifically includes the following steps: S1. Take 500 g of cleaned and dried bovine bone powder and calcine it at 800℃ for 2 hours to obtain crude hydroxyapatite. Then add the crude product to a wet ball mill jar, add 1000 mL of deionized water, set the ball milling time to 4 hours and the speed to 300 rpm, and connect an air jet milling device at the end to control the average particle size at the end to about 50 nm to obtain uniformly dispersed hydroxyapatite ultrafine particles. S2. Take 95 g of polyester chips and 5 g of hydroxyapatite ultrafine particles, add them to a high-speed mixer, mix at 80°C for 10 minutes at 500 rpm, then feed the mixture into a twin-screw extruder, melt blend at 230°C, after uniform melt blending, extrude, cool and granulate to obtain hydroxyapatite / polymer composite particles. S3. The above composite particles are treated in a hot air dryer for 8 hours at a drying temperature of 80°C until the moisture content is no higher than 0.05%. The dried masterbatch is fed into a spinning machine and melt-spun at a spinneret temperature of 230°C, extruding through the spinneret to form nascent fibers with a diameter of approximately 15 μm. After being cooled and shaped in a cooling air zone at 20°C, the nascent fibers enter a stretching zone and are hot-stretched once at 60°C with a stretch ratio of 2. Finally, they are heat-set in a heat-setting box at 100°C for 5 seconds and then wound up to obtain the hydroxyapatite far-infrared functional fiber.
[0021] Example 2 A method for preparing hydroxyapatite far-infrared functional fibers specifically includes the following steps: S1. Take 1000 g of cleaned and dried oyster shells, place them in a box-type resistance furnace, and calcine them at 1200℃ for 4 hours to obtain crude hydroxyapatite. Then add the crude product to a wet ball mill jar, add 2000 mL of deionized water, and wet mill at 400 rpm for 6 hours. Then process it through an air jet mill, control the end particle size distribution to not exceed 200 nm, and obtain uniformly dispersed hydroxyapatite ultrafine particles. S2. Take 800 g of polyvinyl alcohol resin granules and 200 g of hydroxyapatite ultrafine granules, add them to a high-speed mixer, stir and mix at 120℃ for 20 minutes at a stirring speed of 600 rpm, then feed the mixture into a twin-screw extruder, melt blend at 220℃, after the melt blend is uniform, extrude, cool and granulate to obtain hydroxyapatite / polymer composite granules; S3. Transfer the above composite particles into a hot air drying oven at 90°C for 10 hours until the moisture content is controlled to ≤0.05%. The dried particles are then fed into a spinning machine and melt-extruded at a spinning head temperature of 220°C. The nascent fibers are formed through a spinneret with a spinneret orifice diameter of 0.2 mm. The nascent fibers are rapidly cooled in a 30°C cold air environment, then stretched 5 times at 100°C in a stretching zone. Finally, they are sent to a heat-setting box and set at 150°C for 10 seconds before being wound up to obtain the hydroxyapatite far-infrared functional fiber.
[0022] Example 3 A method for preparing hydroxyapatite far-infrared functional fibers specifically includes the following steps: S1. Take 750 g of cleaned and dried sheep bones, place them in a box-type resistance furnace, and calcine them at 1000℃ for 3 hours to obtain crude hydroxyapatite. Then add the crude product to a wet ball mill jar, add 1500 mL of deionized water, wet mill at 350 rpm for 5 hours, and supplement with ultrasonic dispersion. Then, pulverize by airflow to control the end particle size to 125 nm to obtain uniformly dispersed hydroxyapatite ultrafine particles. S2. Take 875 g of polylactic acid and 125 g of hydroxyapatite ultrafine particles, add them to a high-speed mixer, stir and mix at 100℃ for 15 minutes at a stirring speed of 550 rpm, then feed the mixture into a twin-screw extruder, melt blend at 180℃, after uniform melt blending, extrude, cool and granulate to obtain hydroxyapatite / polymer composite particles; S3. The above composite particles were placed in a hot air circulating drying oven and dried at 85°C for 9 hours, with a moisture content of 0.05%. The dried masterbatch was fed into a melt spinning device, and the spinneret temperature was set to 180°C. The masterbatch was extruded through the spinneret to form nascent fibers with a diameter of approximately 16 μm. After being uniformly cooled by 25°C cold air, the nascent fibers were fed into a stretching zone and stretched 3.5 times at 80°C. They were then fed into a heat setting device and set at 125°C for 7.5 seconds before being wound up to obtain the hydroxyapatite far-infrared functional fiber.
[0023] Comparative Example 1 A method for preparing hydroxyapatite far-infrared functional fibers specifically includes the following steps: S1. Weigh 1000 g of polylactic acid and place it directly in a drying oven. Dry it at 85°C for 9 hours to ensure that its moisture content is reduced to no more than 0.05%, so as to provide a dry matrix for subsequent melt blending. S2. Add the dried polylactic acid to a high-speed mixer and stir for 15 minutes at 100°C with a stirring speed of 550 rpm. Then feed the mixture into a twin-screw extruder and melt-blend at 180°C. After the melt-blending is uniform, extrude, cool, and granulate to obtain polylactic acid-based particles. S3. The polylactic acid-based particles were dried again at 85°C for 9 hours. After drying, they were fed into a spinning machine and extruded through a spinneret at a melting temperature of 180°C to form nascent fibers. The spinneret orifice diameter was the same as in Example 3. The nascent fibers were cooled and shaped under cold air at 25°C, then stretched 3.5 times at 80°C, and finally heat-set at 125°C for 7.5 seconds before being wound up to obtain the comparative functional fiber.
[0024] Comparative Example 2 A method for preparing hydroxyapatite far-infrared functional fibers specifically includes the following steps: S1. Add 500 g of nano titanium dioxide dry powder to 1000 mL of deionized water to prepare a 25 wt% slurry. Add zirconia balls with a diameter of 1 mm as grinding media and grind in a wet planetary ball mill at 350 rpm for 4 hours, with ultrasonic dispersion for 30 minutes during the process. Control the average particle size (D50) to about 125 nm and set aside. S2. Take 875 g of polylactic acid and 125 g of nano titanium dioxide particles, add them to a high-speed mixer, stir and mix at 100℃ for 15 minutes at a stirring speed of 550 rpm, then feed the mixture into a twin-screw extruder, melt blend at 180℃, after uniform melt blending, extrude, cool and granulate to obtain nano titanium dioxide / polymer composite particles. S3. The above composite particles were placed in a hot air circulating drying oven and dried at 85°C for 9 hours, with a moisture content of 0.05%. The dried masterbatch was fed into a melt spinning device, and the spinneret temperature was set to 180°C. The masterbatch was extruded through the spinneret to form nascent fibers with a diameter of approximately 16 μm. After being uniformly cooled by 25°C cold air, the nascent fibers entered the stretching zone and underwent a 3.5-fold stretching treatment at 80°C. Subsequently, they were sent to a heat setting device and set at 125°C for 7.5 seconds. The fibers were then wound up to obtain the comparative functional fibers.
[0025] Performance testing 1. Far-infrared emission performance test The far-infrared emissivity of fiber samples in the 4–14 μm wavelength range was measured using a far-infrared emissivity meter, according to the national standard GB / T 30127-2013 "Test Methods for Far-Infrared Properties of Textiles". Fiber samples were cut into sheets of uniform thickness, laid flat on the testing platform, and maintained at a testing distance of 10 cm. The ambient temperature was set to 25℃ and the relative humidity to 50%. The infrared radiation intensity of the samples was measured using an infrared sensor, and the emissivity was calculated by comparing it with blackbody radiation. Each group of samples was tested three times, and the average value was taken as the final result. The results are shown in Table 1 below.
[0026] Table 1. Test results of far-infrared emission performance
[0027] As shown in Table 1, the far-infrared emissivity of Examples 1-3 is all higher than 0.86, exhibiting good far-infrared radiation performance. In particular, the emissivity of Example 2 reaches 0.894, showing the best performance. In contrast, the emissivity of Comparative Examples 1 and 2 is only 0.746 and 0.781, respectively, which is significantly lower than that of the Examples, indicating that the type of functional particles has a decisive influence on far-infrared performance.
[0028] 2. Antibacterial performance test According to GB / T 20944.3-2008 standard, *Escherichia coli* (ATCC 8739) and *Staphylococcus aureus* (ATCC 6538) were selected as test bacteria. Each fiber sample was cut into 50 mm × 50 mm pieces and immersed in an immersion solution containing 1 × 10⁻⁶ bacteria. 5 The bacterial suspension was incubated at CFU / mL in a 37°C shaking incubator for 24 hours. After treatment, the suspension was removed, washed with neutralization solution, diluted, and spread onto nutrient agar plates for incubation. Colony forming units (CFU) were counted, and the antibacterial rate was calculated by comparing the results with the untreated control group. The results are shown in Table 2 below.
[0029] Table 2 Antibacterial effect
[0030] As shown in Table 2, Examples 1-3 all exhibited antibacterial rates exceeding 95% against both *Escherichia coli* and *Staphylococcus aureus*, with Example 2 demonstrating the best performance, indicating that the prepared functional fibers possess significant broad-spectrum antibacterial properties. Comparative Example 1 showed almost no antibacterial ability, and although nano-TiO2 was added to Comparative Example 2, its antibacterial rate was far lower than that of the Examples, indicating that its antibacterial effect was limited and unstable. The hydroxyapatite particles used in this invention are naturally sourced and have controllable particle size. Through the interaction of their surface hydroxyl active sites with the cell membrane, they release Ca²⁺ and PO₄³⁻, interfering with bacterial metabolism and disrupting the membrane structure, thereby achieving non-contact broad-spectrum antibacterial activity. Furthermore, the good interfacial compatibility between hydroxyapatite and the polymer matrix ensures its uniform dispersion within the fibers, resulting in stable and long-lasting antibacterial function.
[0031] 0. Durability test of antibacterial and far-infrared functions Each sample was placed in a standard washing apparatus and subjected to 30 simulated household washes at 40°C using a non-ionic detergent. After washing, the samples were air-dried, and their far-infrared emissivity and antibacterial properties were tested according to methods 1 and 2, and the functional retention rate was calculated.
[0032] The results are shown in Table 3 below.
[0033] Table 3 Far-infrared emission and antibacterial retention rate
[0034] As shown in Table 3, Examples 1-3 exhibited excellent far-infrared emissivity and antibacterial retention rates after 30 standard washes, indicating that the functional fibers prepared in this invention have good durability and stability in practical use. This is attributed to the uniform dispersion of hydroxyapatite ultrafine particles in the polymer matrix and their good interfacial compatibility with the matrix material, allowing them to be firmly embedded in the fiber structure and not easily detached or deactivated during washing. Simultaneously, their stable surface lattice structure allows for the continuous release of Ca²⁺ and PO₄³⁻ ions, maintaining broad-spectrum antibacterial and far-infrared radiation functions. In contrast, although the far-infrared emissivity of Comparative Example 1 did not change significantly after washing, the initial value was already low, making the functional retention rate meaningless. In Comparative Example 2, even with similar particle sizes, the functional retention rate decreased significantly after using TiO₂ to replace HAp, especially with a severe decline in antibacterial performance, demonstrating the irreplaceable synergistic function achieved by hydroxyapatite in this invention.
[0035] 4. Fracture strength and elongation at break The tests were conducted according to GB / T 3916-2013, "Determination of Breaking Strength and Elongation at Break of Synthetic Fiber Filaments". Fiber samples were conditioned for 24 hours in a standard laboratory environment with a constant temperature (20±2℃) and relative humidity of 65±5%, and then subjected to tensile testing using an electronic single-yarn tensile testing machine. Fiber strips with a length of 250 mm were selected for testing, and the tensile speed was 250 mm / min, stretched until breakage. The breaking strength (unit: cN / dtex) and elongation at break (unit: %) were recorded. Each group of samples was tested 10 times, and the average value was taken as the result. The results are shown in Table 4 below.
[0036] Table 4. Fracture Strength and Elongation at Break
[0037] As shown in Table 4, the functional fibers prepared in Examples 1-3 maintained good tensile strength and elongation even after the introduction of hydroxyapatite ultrafine particles. In particular, Example 2 achieved a tensile strength of 3.46 cN / dtex, exhibiting the best overall performance. This indicates that the selected particle size range and content ratio achieved a good balance between mechanical reinforcement and flexibility. The high dispersion of hydroxyapatite within the fiber and its stable interface with the matrix prevented stress concentration and fracture points. In contrast, Comparative Example 1, although exhibiting a slightly higher elongation at break, lacked functional reinforcement due to the absence of functional particles, resulting in a softer material with poor structural density and stability. In Comparative Example 2, the poor compatibility of TiO2 with the matrix and severe particle agglomeration led to failure of interfacial stress transfer, resulting in a significant decrease in tensile strength to only 2.71 cN / dtex, demonstrating a clear trend towards embrittlement.
[0038] 5. Heat shrinkage rate test The test was conducted according to GB / T 6505-2009, "Determination of Heat Shrinkage Rate of Chemical Fiber Filaments". Each fiber sample was cut into straight strips of 500 mm in length and suspended in a constant temperature oven for tension-free shrinkage at 160℃ for 15 minutes. After cooling to room temperature, the final length L2 was measured and compared with the initial length L1. The heat shrinkage rate was calculated using the following formula:
[0039]
[0040] Each group of samples was tested 5 times, and the average value was taken. The results are shown in Table 5 below.
[0041] Table 5 Results of heat shrinkage rate
[0042] As shown in Table 5, the thermal shrinkage rates of Examples 1-3 were all controlled below 6.3%, with Example 2 having the lowest at 5.5%, indicating that the functional fibers prepared by this invention possess good thermal stability and dimensional control capabilities. Hydroxyapatite ultrafine particles exhibit structural stability at high temperatures, are not easily thermally decomposed or migrated, and are uniformly distributed within the fiber matrix. This effectively restricts the disordered movement of polymer chain segments, acting as a spatial barrier and stabilizing crystal regions, thereby reducing fiber dimensional shrinkage during heat treatment. Especially in a highly dispersed state, HAp forms a synergistic network structure with the polymer, improving the fiber's molding density and thermal response stability. In contrast, Comparative Example 1 lacks a crystal constraint and thermal shielding structure, resulting in a shrinkage rate as high as 7.8%; while in Comparative Example 2, severe TiO2 particle agglomeration and poor compatibility with the matrix, along with uneven structural distribution, further weakened dimensional stability, increasing its thermal shrinkage rate to 9.4%.
[0043] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.
Claims
1. A method for preparing hydroxyapatite far-infrared functional fibers, characterized in that, Includes the following steps: S1. Select animal bones or shells as raw materials, and successively clean, dry and calcine at high temperature to obtain crude hydroxyapatite. The crude product is then processed by air jet milling and wet grinding to prepare hydroxyapatite ultrafine particles with a particle size of 50-200 nm. S2. The hydroxyapatite ultrafine particles and matrix material are added to a high-speed mixer and mixed, followed by melt blending and extrusion granulation to obtain hydroxyapatite / polymer composite particles; S3. After drying, the composite particles are fed into a spinning machine and subjected to melt spinning process. The particles are extruded through a spinneret to form nascent fibers. The nascent fibers are then cooled, stretched, and heat-set to obtain hydroxyapatite far-infrared antibacterial functional fibers.
2. The method for preparing hydroxyapatite far-infrared functional fibers according to claim 1, characterized in that, The high-temperature calcination temperature in step S1 is 800-1200℃, and the time is 2-4 hours.
3. The method for preparing hydroxyapatite far-infrared functional fibers according to claim 1, characterized in that, The matrix material mentioned in step S2 is selected from one or more of polyester chips, polylactic acid, and polyvinyl alcohol.
4. The method for preparing hydroxyapatite far-infrared functional fibers according to claim 1, characterized in that, The hydroxyapatite far-infrared functional fiber comprises the following raw materials in parts by weight: 80-95% matrix material and 5-20% hydroxyapatite ultrafine particles.
5. The method for preparing hydroxyapatite far-infrared functional fibers according to claim 1, characterized in that, The mixing temperature in step S2 is 80–120°C, and the mixing time is 10–20 minutes.
6. The method for preparing hydroxyapatite far-infrared functional fibers according to claim 1, characterized in that, In step S2, the melt blending process is set with different temperature ranges according to the different matrix materials. The melt blending temperature of polyester is 230-280℃, the melt blending temperature of polylactic acid is 160-200℃, and the melt blending temperature of polyvinyl alcohol is 180-220℃.
7. The method for preparing hydroxyapatite far-infrared functional fibers according to claim 1, characterized in that, In step S3, the composite particles are dried before spinning, and their moisture content is controlled to be no higher than 0.05%.
8. The method for preparing hydroxyapatite far-infrared functional fibers according to claim 1, characterized in that, In step S3, the cooling temperature of the nascent fiber is 20-30°C, the stretching ratio is 2-5 times, and the stretching temperature is 60-100°C.
9. The method for preparing hydroxyapatite far-infrared functional fibers according to claim 1, characterized in that, In step S3, the heat setting temperature of the fiber during the heat setting stage is 100-150°C, and the heat setting time is 5-10 seconds.
10. The functional fiber prepared by the method for preparing hydroxyapatite far-infrared functional fiber according to claim 1, characterized in that, The functional fiber has a far-infrared emissivity of not less than 0.86 in the 4–14 μm band, and an antibacterial rate of not less than 95% against both Escherichia coli and Staphylococcus aureus.