Environment-friendly degradable antibacterial strong and tough polylactic acid-based elastic fiber and preparation method thereof

Abstract

The application provides an environment-friendly, degradable, antibacterial and tough polylactic acid-based elastic fiber and a preparation method thereof, and relates to the technical field of fiber materials, and comprises the following components in percentage by mass: 55-80wt% of polylactic acid, 13.7-17.5wt% of polyhydroxyalkanoate, 0.5-5wt% of a metal antibacterial agent, 5-20wt% of a thermoplastic polyurethane elastomer, and 0.8-2.5wt% of a star-shaped hyperbranched compatibilizer; the molecular structure of the star-shaped hyperbranched compatibilizer comprises a polylactic acid oligomer segment, a polyethylene glycol segment and a pyrocatechol group; the polylactic acid provides the degradability and basic strength of the matrix; the polyhydroxyalkanoate enhances the toughness, degradability and processability; the metal antibacterial agent endows the fiber with high-efficiency and broad-spectrum antibacterial function; the thermoplastic polyurethane elastomer contributes excellent elasticity and flexibility; and the star-shaped hyperbranched compatibilizer improves the compatibility of the fiber system; and the components synergize under the above-mentioned ratio to lay a multifunctional foundation of the fiber, including the antibacterial function, good elasticity and environment-friendly degradability.

Description

Technical Field

[0001] This invention relates to the field of fiber materials technology, specifically to an environmentally friendly, biodegradable, antibacterial, and tough polylactic acid-based elastic fiber and its preparation method. Background Technology

[0002] Under the current trend of sustainable development, the field of fiber materials is undergoing profound changes. With the unprecedented rise in global environmental awareness and the increasing emphasis on ecological balance, biodegradable materials have become a hot research and development area. Among them, polylactic acid (PLA), as a highly representative biodegradable thermoplastic polyester, has demonstrated unique advantages and enormous application potential.

[0003] Polylactic acid (PLA) is primarily sourced from renewable resources, such as starch-rich crops like corn and cassava. This biomass-based approach not only reduces reliance on traditional petroleum-based resources but also mitigates the environmental impact of oil extraction and processing. Furthermore, PLA's biodegradability aligns perfectly with core environmental protection principles. In the natural environment, PLA can be gradually decomposed into harmless substances like carbon dioxide and water through hydrolysis and metabolism by microorganisms. This avoids the soil and water pollution, as well as ecosystem damage, caused by the long-term persistence of traditional synthetic fibers in the environment after disposal.

[0004] Numerous existing patents relate to polylactic acid (PLA) fiber technology. For example, patent document CN104195320A discloses a method for preparing PLA fibers, which mainly focuses on improving the mechanical properties of PLA fibers but does not consider the need for antibacterial properties. In special applications such as medical and hygiene, bacteria can easily grow and multiply on the fiber surface. PLA fibers lacking antibacterial properties cannot meet the requirements and can easily lead to cross-infection and other problems.

[0005] Furthermore, patent document CN103205799A mentions a polylactic acid fiber with certain functionalities, but its elasticity is poor. In practical applications, such as sportswear and everyday tight-fitting clothing, fibers need to have good elasticity to ensure comfort and flexibility. This insufficient elasticity of polylactic acid fiber limits its application in these fields.

[0006] Meanwhile, while some published patents involve antibacterial fibers, the antibacterial agents used may pose potential environmental hazards or biosafety issues. Furthermore, regarding biodegradability, some fibers degrade too slowly in the natural environment, failing to truly meet environmental protection requirements and still causing long-term pollution. In addition, existing technologies have significant shortcomings in combining antibacterial function with good elasticity and environmental biodegradability, making it difficult to meet market demand for high-performance polylactic acid fibers. Summary of the Invention

[0007] The present invention aims to address the problem that existing elastic fibers have significant deficiencies in their overall performance in terms of antibacterial function, good elasticity, and environmental biodegradability.

[0008] To address the aforementioned problems, this invention provides an environmentally friendly, biodegradable, antibacterial, and tough polylactic acid-based elastic fiber, comprising the following components by weight percentage: 55-80 wt% polylactic acid (PLA), 13.7-17.5 wt% polyhydroxyalkanoates (PHA), 0.5-5 wt% a metallic antibacterial agent, 5-20 wt% thermoplastic polyurethane elastomer, and 0.8-2.5 wt% a star-shaped hyperbranched compatibilizer; the sum of the weight percentages of all components is 100%.

[0009] The molecular structure of the star-shaped hyperbranched compatibilizer includes polylactic acid oligomer segments, polyethylene glycol segments, and catechol groups.

[0010] The environmentally friendly, biodegradable, antibacterial, and tough polylactic acid-based elastic fiber of the present invention has, but is not limited to, the following beneficial effects compared with the prior art:

[0011] In the environmentally friendly, biodegradable, antibacterial, and tough polylactic acid-based elastic fiber of the present invention, PLA provides the matrix with biodegradability and basic strength; PHA enhances toughness, biodegradability, and processability; metallic antibacterial agents impart highly efficient and broad-spectrum antibacterial functions; thermoplastic polyurethane elastomers contribute excellent elasticity and flexibility; the components work synergistically in this ratio, laying a multifunctional foundation for the fiber's antibacterial function, good elasticity, and environmental degradability.

[0012] More importantly, the introduction of star-shaped hyperbranched compatibilizers improves the compatibility of the fiber system. The polylactic acid oligomer segments, polyethylene glycol segments, and catechol groups can significantly improve the overall mechanical properties of the fiber. While enhancing the tensile strength of the fiber, it greatly improves its elongation at break and elastic recovery rate, achieving a strong, tough, and elastic effect. This overcomes the contradiction between strength and elasticity in traditional modification, which often restrict each other, and achieves long-lasting and stable antibacterial function.

[0013] Specifically, polylactic acid oligomer segments improve the compatibility and co-crystallization of PLA and PHA matrices, while polyethylene glycol segments achieve miscibility and hydrogen bonding with the soft segments of thermoplastic polyurethane elastomers. The catechol groups strongly chelate metal ions, firmly fixing and uniformly dispersing the metal antibacterial agent, thus avoiding agglomeration, migration, and explosive release during processing and use. This results in a long-lasting and stable antibacterial effect, improved processing performance, enhanced system compatibility, reduced melt viscosity fluctuations, improved melt spinning stability, and reduced fiber breakage rate, which is beneficial for industrial production. At the same time, the introduction of star-shaped hyperbranched compatibilizers may form a finer microstructure inside the fiber, which is conducive to the penetration of moisture and microorganisms, thereby improving the fiber degradation rate.

[0014] Furthermore, the metal antibacterial agent is one or more of the masterbatches of silver-based, zinc-based, copper-based and their composite systems.

[0015] Specifically, the metal antibacterial agent is in masterbatch form, which ensures its stability, compatibility with polymers, and antibacterial efficiency during high-temperature spinning; silver, zinc, copper and their composite systems provide efficient and broad-spectrum antibacterial capabilities, and can be selected and compounded according to the needs of different application scenarios.

[0016] Furthermore, the star-shaped hyperbranched compatibilizer is prepared according to the following steps:

[0017] Step 1: Dissolve HPG (hyperbranched polyglycerol) in anhydrous toluene, heat to 110-120℃ under nitrogen protection and reflux for 2 hours to remove water, then cool to 80℃, add LA (L-lactide) and catalyst a, heat to 130-140℃ under nitrogen protection and stir for 6-8 hours. Dissolve the reaction product in dichloromethane and add it dropwise to methanol while stirring. After purification, the precipitated white crystals are obtained as the polymerization product.

[0018] Step 2: Dissolve the polymerization product in DMF (N,N-dimethylformamide), add dopamine and catalyst b, and stir until homogeneous to obtain mixture A; dissolve DCC (dicyclohexylcarbodiimide) in DMF to obtain mixture B; add mixture B dropwise to mixture A under ice bath conditions, remove the ice bath after the addition is complete, and react at room temperature for 4 hours. After the reaction is complete, add monomethoxy polyethylene glycolamine, heat to 40-50℃ and react for 12 hours. The resulting reaction product is filtered, dialyzed, and dried to obtain a star-shaped hyperbranched compatibilizer.

[0019] Specifically, step 1 involves HPG-initiated LA ring-opening polymerization to form a star-shaped intermediate with HPG as the core and multiple polylactic acid oligomer segments grafted onto its periphery. This method is efficient and can control the PLA segment length. In step 2, dopamine providing catechol groups is first grafted onto the remaining hydroxyl groups of the star-shaped intermediate using DCC condensation. Then, monomethoxy polyethylene glycol amine is added, and its amino group reacts with the activated carboxyl or hydroxyl groups in the system to introduce polyethylene glycol segments. This ensures that the polylactic acid oligomer segments, polyethylene glycol segments, and catechol groups are integrated into the backbone of the star-shaped intermediate.

[0020] Further, in step 1, the mass ratio of HPG to LA is 1:(2.1-2.3).

[0021] Specifically, this mass ratio ensures that the active hydroxyl groups on each HPG molecule are fully activated and grafted with sufficient PLA segments to provide strong matrix anchoring. At the same time, this ratio avoids the problems of homopolymer formation caused by excessive LA or excessively short PLA arms and reduced compatibility caused by insufficient LA.

[0022] Further, in step 1, the amount of catalyst a is 1-2% of the mass of LA; catalyst a is p-toluenesulfonic acid.

[0023] Specifically, a dosage of 1-2% can ensure that the polymerization reaction proceeds fully and stably within 6-8 hours at 130-140℃, avoiding excessively rapid reaction leading to an overly wide molecular weight distribution or localized overheating, and also avoiding incomplete reaction due to insufficient dosage.

[0024] Further, in step 2, the mass ratio of the polymer product, dopamine, DCC, and monomethoxy polyethylene glycol amine is 60:10.8:14:30.

[0025] Specifically, this mass ratio maximizes the grafting efficiency of catechol groups and PEG segments while minimizing side reactions and unreacted raw material residues; for example, the amount of DCC used is sufficient to activate the carboxyl group of dopamine and promote subsequent reactions with PEG amines.

[0026] Further, in step 2, the amount of catalyst b is 1-2% of the mass of dopamine; the catalyst b is 4-dimethylaminopyridine.

[0027] Further, in step 2, the purification includes the following steps: filtration, washing, and drying.

[0028] Preferably, the specific methods for filtering, washing, and drying are as follows:

[0029] Filtration: The reaction product was filtered to remove the byproduct dicyclohexylurea (DCU) white solid, and the filtrate was obtained.

[0030] Washing: Transfer the filtrate to a dialysis bag with a molecular weight cutoff of 3500 Da, dialyze with deionized water for 3 days (changing the water 3-4 times a day), and then dialyze with a 1:1 ethanol / water mixture for 1 day to remove unreacted reagents, byproducts and DMF.

[0031] Drying: The solution in the dialysis bag is transferred to a rotary evaporator and concentrated under reduced pressure at 40-50℃ until it becomes viscous. Then it is freeze-dried to obtain a light brown to brownish-red spongy solid, which is the star-shaped hyperbranched compatibilizer.

[0032] Specifically, filtration aims to remove dicyclohexylurea solid impurities, a byproduct of the condensation reaction; washing thoroughly removes unreacted small monomers, catalysts, and the solvent DMF; drying yields a solid product that is easy to store and weigh. This purification process ensures that the compatibilizer functions stably in subsequent fiber processing and will not affect fiber properties or the spinning process due to the introduction of impurities.

[0033] This invention also discloses a preparation method for preparing the environmentally friendly, biodegradable, antibacterial, and tough polylactic acid-based elastic fiber as described above, comprising the following steps:

[0034] S1. After drying the polylactic acid, polyhydroxyalkanoate, metal antibacterial agent, thermoplastic polyurethane elastomer, and star-shaped hyperbranched compatibilizer respectively, weigh them according to the mass percentage and set them aside.

[0035] S2. Add polylactic acid, polyhydroxyalkanoate, metal antibacterial agent, thermoplastic polyurethane elastomer, and star-shaped hyperbranched compatibilizer into a high-speed mixer and mix for 30-60 minutes at 40-60℃ and 500-1000 rpm until homogeneous to obtain a mixture.

[0036] S3. Add the mixture to the screw extruder for melt spinning. Set the temperature of each zone of the screw to 160-220℃. Extrude the nascent fiber through the spinneret.

[0037] S4. Nascent fibers are stretched by hot rollers at 60-100℃ and then shaped to obtain environmentally friendly, biodegradable, antibacterial, and tough polylactic acid-based elastic fibers.

[0038] The preparation method of the present invention, compared with the prior art, has the following beneficial effects, but is not limited to:

[0039] The drying process in S1 ensures that all components (especially easily hydrolyzed PLA, PHA, and hygroscopic star-shaped hyperbranched compatibilizer) have extremely low moisture content before processing, preventing hydrolysis and degradation at high temperatures and ensuring the stability of raw materials and spinning quality. The mixing step in S2, under gentle shearing at 40-60℃ and 500-1000rpm, allows the solid star-shaped hyperbranched compatibilizer powder to achieve preliminary uniform dispersion and premixing with other component particles, creating favorable conditions for interfacial compatibility in the melting stage. The melt spinning in S3, under a temperature gradient of 160-220℃, allows the mixture to fully melt and homogenize, and the star-shaped hyperbranched compatibilizer migrates to the interfaces of each phase in the melt to play a bridging role. The drafting and setting in S4, through heating and stretching with hot rollers, orients and crystallizes the fiber molecular chains, ultimately locking the fine microstructure optimized by the compatibilizer, so that the excellent mechanical and functional properties are fixed and manifested.

[0040] Furthermore, in S3, the diameter of the spinneret orifice is 0.2-0.5 mm.

[0041] Specifically, smaller pore sizes can be used to produce fine denier or micro denier fibers, suitable for high-end medical dressings and intimate apparel where softness and coverage are required; larger pore sizes are suitable for producing fibers of regular specifications, used in ordinary textile fabrics, hygiene products, etc.; this diameter range reflects the universality and adjustability of the spinning process, making it suitable for a variety of end products.

[0042] Furthermore, in S4, the stretching factor is 2-5 times.

[0043] Specifically, a lower draw ratio results in a lower degree of molecular chain orientation, leading to softer fibers with higher elongation at break, suitable for ordinary clothing that emphasizes comfort; a higher draw ratio results in a high degree of molecular chain orientation, significantly improving the tensile strength, modulus, and dimensional stability of the fiber, suitable for sportswear, industrial materials, etc., where higher strength is required. Detailed Implementation

[0044] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0045] The terminology used in the embodiments of this application is for the purpose of describing particular implementations only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the implementations of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0046] It should be understood that in the various embodiments of this application, the sequence number of each process does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the implementation regulations of this application.

[0047] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0048] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0049] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods. For example, the types and sources of materials involved in the following examples and comparative examples are as follows.

[0050] Polylactic acid: weight-average molecular weight is 100,000 g / mol;

[0051] Polyhydroxy fatty acid ester: purchased from Shanghai Yuanye Biotechnology Co., Ltd., product number S22177;

[0052] Zinc-based antibacterial agent: Antibac purchased from Shanghai Langyi Functional Materials Co., Ltd. ™ ZN series;

[0053] Thermoplastic polyurethane elastomer: hardness 85A, purchased from Wanhua Chemical Group.

[0054] Preparation Example 1

[0055] The star-shaped hyperbranched compatibilizer was prepared according to the following steps:

[0056] Step 1: Dissolve 100g of HPG in 500mL of anhydrous toluene, heat to 115℃ under nitrogen protection and reflux for 2h to remove water, then cool to 80℃, add 230g of LA and 2.5g of p-toluenesulfonic acid, heat to 135℃ under nitrogen protection and stir for 7h. After the reaction is complete, cool the resulting reaction product to room temperature, then dissolve it in 750mL of dichloromethane, and then add it dropwise to 5L of methanol while stirring. White crystals precipitate out. After filtration, wash the obtained white crystals twice with methanol, and then place them in an oven and vacuum dry at 50℃ for 12h to obtain 316.26g of polymer product.

[0057] Step 2: Dissolve all the polymerization products in 1.5 L of DMF, add 54 g of dopamine and 1 g of 4-dimethylaminopyridine and stir until homogeneous to obtain mixture A; under ice bath conditions, dissolve 70 g of DCC in 250 mL of DMF to obtain mixture B; under ice bath conditions, add mixture B dropwise to mixture A, remove the ice bath after the addition is complete, stir the reaction at room temperature for 4 h, after the reaction is complete, add 150 g of monomethoxy polyethylene glycolamine, heat to 45 °C and react for 12 h, filter the generated reaction product to obtain filtrate, transfer the filtrate to a dialysis bag with a molecular weight cutoff of 3500 Da, dialyze with deionized water for 3 days (changing the water 3-4 times a day), then dialyze with a 1:1 volume ratio ethanol / water mixture for 1 day, then transfer the solution in the dialysis bag to a rotary evaporator, concentrate under reduced pressure at 45 °C to a viscous state, and then freeze dry to obtain a brown sponge-like solid, which is the star-shaped hyperbranched compatibilizer.

[0058] Preparation Example 2

[0059] Compared with Preparation Example 1, the only difference is that in step 1, the mass of LA was adjusted to 220g, while the other steps and conditions remained the same, and the star-shaped hyperbranched compatibilizer was finally obtained.

[0060] Preparation Example 3

[0061] Compared with Preparation Example 1, the only difference is that in step 1, the mass of LA was adjusted to 210g, while the other steps and conditions remained the same, and the star-shaped hyperbranched compatibilizer was finally obtained.

[0062] Example 1

[0063] This embodiment discloses an environmentally friendly, biodegradable, antibacterial, and tough polylactic acid-based elastic fiber, which is prepared according to the following steps:

[0064] S1. Polylactic acid and polyhydroxyalkanoate were placed in a drying oven and vacuum dried at 55°C for 3 hours. Zinc-based antibacterial agent was placed in a drying oven and dried at 45°C for 4 hours. The thermoplastic polyurethane elastomer and the star-shaped hyperbranched compatibilizer of Preparation Example 1 were placed in a drying oven and vacuum dried at 35°C for 2.5 hours. Then they were weighed according to the following mass percentages: 70wt%, 16wt%, 3wt%, 10wt%, and 1wt%, respectively, for later use.

[0065] S2. Add polylactic acid, polyhydroxyalkanoate, metal antibacterial agent, thermoplastic polyurethane elastomer, and star-shaped hyperbranched compatibilizer into a high-speed mixer and mix for 40 minutes at 50°C and 800 rpm until homogeneous to obtain a mixture.

[0066] S3. The mixture is added to the screw extruder for melt spinning. The temperature in the feed area of ​​the screw extruder is 160°C. As the material moves towards the outlet, the temperature gradually increases from 160°C to 220°C. The material is extruded through a spinneret with a spinneret orifice diameter of 0.3 mm to form nascent fibers. During the spinning process, the pressure of the screw extruder is controlled to be 8 MPa and the screw speed is 30 rpm.

[0067] S4. Nascent fibers are stretched at 3 times the stretching ratio by passing through a hot roller at 80°C and then set at 90°C for 15 seconds to obtain environmentally friendly, biodegradable, antibacterial, and tough polylactic acid-based elastic fibers.

[0068] Example 2

[0069] This embodiment discloses an environmentally friendly, biodegradable, antibacterial, and tough polylactic acid-based elastic fiber, which is prepared according to the following steps:

[0070] S1. Polylactic acid and polyhydroxyalkanoate were placed in a drying oven and vacuum dried at 55°C for 3 hours. Zinc-based antibacterial agent was placed in a drying oven and dried at 45°C for 4 hours. The thermoplastic polyurethane elastomer and the star-shaped hyperbranched compatibilizer of Preparation Example 1 were placed in a drying oven and vacuum dried at 35°C for 2.5 hours. Then they were weighed according to the following mass percentages: 55wt%, 17.5wt%, 5wt%, 20wt%, and 2.5wt%, respectively, for later use.

[0071] S2. Add polylactic acid, polyhydroxyalkanoate, metal antibacterial agent, thermoplastic polyurethane elastomer, and star-shaped hyperbranched compatibilizer into a high-speed mixer and mix for 30 minutes at 40°C and 1000 rpm until homogeneous to obtain a mixture.

[0072] S3. The mixture is added to the screw extruder for melt spinning. The temperature in the feed area of ​​the screw extruder is 160°C. As the material moves towards the outlet, the temperature gradually increases from 160°C to 220°C. The material is extruded through a spinneret with a spinneret orifice diameter of 0.3 mm to form nascent fibers. During the spinning process, the pressure of the screw extruder is controlled to be 8 MPa and the screw speed is 30 rpm.

[0073] S4. Nascent fibers are stretched at 3 times the stretching ratio by passing through a hot roller at 80°C and then set at 90°C for 15 seconds to obtain environmentally friendly, biodegradable, antibacterial, and tough polylactic acid-based elastic fibers.

[0074] Example 3

[0075] This embodiment discloses an environmentally friendly, biodegradable, antibacterial, and tough polylactic acid-based elastic fiber, which is prepared according to the following steps:

[0076] S1. Polylactic acid and polyhydroxyalkanoate were placed in a drying oven and vacuum dried at 55°C for 3 hours. Zinc-based antibacterial agent was placed in a drying oven and dried at 45°C for 4 hours. The thermoplastic polyurethane elastomer and the star-shaped hyperbranched compatibilizer of Preparation Example 1 were placed in a drying oven and vacuum dried at 35°C for 2.5 hours. Then they were weighed according to the following mass percentages: 80wt%, 13.7wt%, 0.5wt%, 5wt%, and 0.8wt%, respectively, for later use.

[0077] S2. Add polylactic acid, polyhydroxyalkanoate, metal antibacterial agent, thermoplastic polyurethane elastomer, and star-shaped hyperbranched compatibilizer into a high-speed mixer and mix for 60 minutes at 60°C and 500 rpm until homogeneous to obtain a mixture.

[0078] S3. The mixture is added to the screw extruder for melt spinning. The temperature in the feed area of ​​the screw extruder is 160°C. As the material moves towards the outlet, the temperature gradually increases from 160°C to 220°C. The material is extruded through a spinneret with a spinneret orifice diameter of 0.3 mm to form nascent fibers. During the spinning process, the pressure of the screw extruder is controlled to be 8 MPa and the screw speed is 30 rpm.

[0079] S4. Nascent fibers are stretched at 3 times the stretching ratio by passing through a hot roller at 80°C and then set at 90°C for 15 seconds to obtain environmentally friendly, biodegradable, antibacterial, and tough polylactic acid-based elastic fibers.

[0080] Example 4

[0081] Compared with Example 1, the only difference is that the star-shaped hyperbranched compatibilizer of Preparation Example 1 is replaced with the star-shaped hyperbranched compatibilizer of Preparation Example 2; the other steps and conditions are kept the same, and polylactic acid-based elastic fibers are finally obtained.

[0082] Example 5

[0083] Compared with Example 1, the only difference is that the star-shaped hyperbranched compatibilizer of Preparation Example 1 is replaced with the star-shaped hyperbranched compatibilizer of Preparation Example 3; the other steps and conditions are kept the same, and polylactic acid-based elastic fibers are finally obtained.

[0084] Comparative Example 1

[0085] Compared with Example 1, the only difference is that the addition of the star-shaped hyperbranched compatibilizer is omitted; the other steps and conditions remain the same, and polylactic acid-based elastic fibers are finally obtained.

[0086] Comparative Example 2

[0087] Compared with Example 1, the only difference is that the star-shaped hyperbranched compatibilizer in Preparation Example 1 was replaced with a common compatibilizer (polylactic acid grafted maleic anhydride, purchased from Nanjing Julong Technology Co., Ltd.); the other steps and conditions were kept the same, and polylactic acid-based elastic fibers were finally obtained.

[0088] The polylactic acid-based elastic fibers of Examples 1-5 and Comparative Examples 1-2 were subjected to performance tests. The specific test items and methods are as follows:

[0089] Mechanical properties: The tensile strength, elongation at break, elastic recovery rate and Young's modulus were tested in accordance with GB / T 3916-2013 "Determination of breaking strength and elongation at break of single yarn in packaged textiles".

[0090] Antibacterial properties: In accordance with GB / T 20944.3-2008 "Evaluation of antibacterial properties of textiles - Part 3: Shaking method", Staphylococcus aureus (Gram-positive bacteria) and Escherichia coli (Gram-negative bacteria) were selected as the bacterial strains to test their initial antibacterial rate and the antibacterial rate after 20 and 50 washes. The washing method was in accordance with GB / T 12490-2014 "Tests for color fastness of textiles - Household and commercial washing" for standard washing.

[0091] Degradation performance: The weight loss rate and molecular weight reduction rate were tested in accordance with ISO 14855-1 "Determination of final aerobic biodegradability of plastic materials under controlled composting conditions".

[0092] The test results of the mechanical properties are listed in Table 1, as follows:

[0093] Table 1 Mechanical performance test results

[0094]

[0095] Analysis of the data in Table 1 shows that, compared to Comparative Examples 1-2, the polylactic acid-based elastic fibers of Examples 1-5 are significantly superior in terms of tensile strength, elongation at break, elastic recovery, and Young's modulus. This indicates that the overall mechanical properties of the polylactic acid-based elastic fibers of the present invention are superior. Among them, the polylactic acid-based elastic fiber of Comparative Example 1 has the worst mechanical properties. This may be because no star-shaped hyperbranched compatibilizer was added to the system, resulting in poor component compatibility and low interfacial bonding, thus leading to poor mechanical properties. The mechanical properties of the polylactic acid-based elastic fiber of Comparative Example 2 are slightly improved compared to Comparative Example 1. This may be because a common compatibilizer was added, which slightly improved the system compatibility, but the degree of improvement is far less than that of Examples 1-5, which included a star-shaped hyperbranched compatibilizer.

[0096] The test results of the mechanical properties are listed in Table 1, as follows:

[0097] Table 2 Antibacterial performance test results

[0098]

[0099] Analysis of the data in Table 2 shows that, compared to Comparative Examples 1-2, the initial antibacterial rate of the polylactic acid-based elastic fibers in Examples 1-5 is slightly better. However, with the increase of washing cycles, the antibacterial rate of the polylactic acid-based elastic fibers in Comparative Examples 1-2 decreases significantly and faster, indicating that the antibacterial performance of the polylactic acid-based elastic fibers of the present invention is superior. Among them, the antibacterial rate of the polylactic acid-based elastic fibers in Comparative Example 1 shows the strongest decrease. This may be because no star-shaped hyperbranched compatibilizer was added to the system, resulting in poor component compatibility, low interfacial bonding, and faster shedding of antibacterial components with increasing washing cycles, thus leading to a rapid decrease in antibacterial performance. The antibacterial performance of the polylactic acid-based elastic fibers in Comparative Example 2 is slightly improved compared to Comparative Example 1. This may be because a common compatibilizer was added, which slightly improved the system compatibility, but the degree of improvement is far less than that of Examples 1-5, which included a star-shaped hyperbranched compatibilizer.

[0100] The test results for degradation performance are listed in Table 3, as follows:

[0101] Table 3 Degradation performance test results

[0102]

[0103] Analysis of the data in Table 3 shows that the polylactic acid-based elastic fibers of Examples 1-5 have significantly higher degradation performance compared to Comparative Examples 1-2.

[0104] The foregoing has described several embodiments of the present invention in detail, but these descriptions are merely preferred embodiments and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. An environmentally friendly, biodegradable, antibacterial, and tough polylactic acid-based elastic fiber, characterized in that, It comprises the following components by weight percentage: 55-80 wt% polylactic acid, 13.7-17.5 wt% polyhydroxyalkanoates, 0.5-5 wt% metallic antibacterial agent, 5-20 wt% thermoplastic polyurethane elastomer, and 0.8-2.5 wt% star-shaped hyperbranched compatibilizer; the sum of the weight percentages of all components is 100%. The molecular structure of the star-shaped hyperbranched compatibilizer includes polylactic acid oligomer segments, polyethylene glycol segments, and catechol groups. The star-shaped hyperbranched compatibilizer was prepared according to the following steps: Step 1: Dissolve hyperbranched polyglycerol in anhydrous toluene, heat to 110-120℃ under nitrogen protection and reflux for 2 hours to remove water, then cool to 80℃, add L-lactide and catalyst a, heat to 130-140℃ under nitrogen protection and stir for 6-8 hours. Dissolve the reaction product in dichloromethane and add it dropwise to methanol while stirring. After purification, the precipitated white crystals are obtained as the polymer product. Step 2: Dissolve the polymerization product in N,N-dimethylformamide, add dopamine and catalyst b, and stir until homogeneous to obtain mixture A; dissolve dicyclohexylcarbodiimide in N,N-dimethylformamide to obtain mixture B; add mixture B dropwise to mixture A under ice bath, remove the ice bath after the addition is complete, and react at room temperature for 4 hours. After the reaction is complete, add monomethoxy polyethylene glycolamine, heat to 40-50℃ and react for 12 hours. The resulting reaction product is filtered, dialyzed, and dried to obtain a star-shaped hyperbranched compatibilizer. In step 1, the mass ratio of hyperbranched polyglycerol to L-lactide is 1:(2.1-2.3); In step 1, the amount of catalyst a is 1-2% of the mass of L-lactide; catalyst a is p-toluenesulfonic acid; In step 2, the mass ratio of the polymerization product, dopamine, dicyclohexylcarbodiimide, and monomethoxy polyethylene glycol amine is 60:10.8:14:

30. In step 2, the amount of catalyst b is 1-2% of the mass of dopamine; catalyst b is 4-dimethylaminopyridine.

2. The environmentally friendly, biodegradable, antibacterial, and tough polylactic acid-based elastic fiber according to claim 1, characterized in that, The metal antibacterial agent is one or more of the masterbatches of silver, zinc, copper and their composite systems.

3. A preparation method for preparing the environmentally friendly, biodegradable, antibacterial, and tough polylactic acid-based elastic fiber as described in any one of claims 1-2, characterized in that, Includes the following steps: S1. After drying the polylactic acid, polyhydroxyalkanoate, metal antibacterial agent, thermoplastic polyurethane elastomer, and star-shaped hyperbranched compatibilizer respectively, weigh them according to the mass percentage and set them aside. S2. Add polylactic acid, polyhydroxyalkanoate, metal antibacterial agent, thermoplastic polyurethane elastomer, and star-shaped hyperbranched compatibilizer into a high-speed mixer and mix for 30-60 minutes at 40-60℃ and 500-1000 rpm until homogeneous to obtain a mixture. S3. Add the mixture to the screw extruder for melt spinning. Set the temperature of each zone of the screw to 160-220℃. Extrude the nascent fiber through the spinneret. S4. Nascent fibers are stretched by hot rollers at 60-100℃ and then shaped to obtain environmentally friendly, biodegradable, antibacterial, and tough polylactic acid-based elastic fibers.

4. The preparation method according to claim 3, characterized in that, In S3, the diameter of the spinneret orifice is 0.2-0.5 mm.

5. The preparation method according to claim 3, characterized in that, In S4, the stretching ratio is 2-5 times.

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