Multi-thread elastic knitted fabric and preparation method thereof

Abstract

The invention relates to the field of textile materials, and discloses a multi-thread elastic knitted fabric and a preparation method thereof.The multi-thread elastic knitted fabric is prepared from, by weight, 30 parts of ternary polymerization elastic fibers; 70 parts of modified bamboo fiber; the ternary copolymerized elastic fiber is prepared from the following raw material components in parts by weight: 28-32 parts of polylactic acid; 38 to 42 parts of polytrimethylene terephthalate; 28 to 32 parts of poly (butylene succinate); 1 to 3 parts of graphene nanosheets; 0.5 to 1.5 parts of epoxidized soybean oil; 2 to 4 parts of beta-cyclodextrin; the modified bamboo fibers are subjected to enzymatic treatment, silane coupling agent modification, dopamine coating treatment and ultrasonic treatment. Through micro gradient structure design and multi-step functionalization treatment of the ternary polymerization elastic fibers and the modified bamboo fibers, unification of excellent elastic recovery, comfort, multifunctionality and durability is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of textile materials, in particular to a multi-thread elastic knitted fabric and a preparation method thereof. BACKGROUND

[0002] With the diversification of modern lifestyles and the increasing demand for comfortable and functional clothing from consumers, elastic knitted fabrics have received widespread attention due to their excellent fit and comfort. In particular, in the fields of sports and leisure, health care, and smart wear, higher requirements are placed on the elastic recovery, comfort, functionality, and durability of fabrics, prompting researchers to continuously explore new design and preparation methods for elastic knitted fabrics to meet the growing demand for high-performance textiles.

[0003] In the prior art, elastic knitted fabrics are mainly prepared by blending synthetic elastic fibers (such as spandex, polyurethane elastic fibers, etc.) with natural fibers (such as cotton, hemp, bamboo fibers, etc.) or by using core-spun yarn technology. Currently, various elastic core-spun yarn knitted fabrics have been developed to improve fabric elasticity through spandex core-cotton yarn covering structures. Researchers have also proposed methods for modifying bamboo fibers, using alkali treatment and silane coupling agents to improve the performance of bamboo fibers. In addition, functional knitted fabric technology has been developed to achieve temperature regulation and antibacterial functions by adding functional microcapsules. These technical solutions have made some progress in improving certain properties of fabrics.

[0004] Although the prior art has made some progress in the field of elastic knitted fabrics, there are still some deficiencies. First, traditional elastic fibers usually have a single or double component structure, and the interaction between molecular chains is limited, leading to permanent deformation of the fabric after repeated stretching and a decrease in elastic recovery performance. This is because conventional elastic fibers lack micro-enhanced structures and reversible molecular interaction mechanisms. Second, existing bamboo fiber modification techniques are mostly single treatment methods, which cannot simultaneously improve multiple properties of the fibers, especially the lack of synergistic modification of surface activity and internal structure, making it difficult for functional molecules to effectively combine and persistently fix. Third, existing functional treatment techniques often use simple dipping or coating methods, and the bonding force between functional additives and fibers is weak, resulting in a significant decrease in functionality after multiple washes, and lacking a directional fixation and protection mechanism for nanoscale functional particles. Finally, traditional weaving processes do not consider the dynamic synergistic relationship between elastic fibers and non-elastic fibers, ignoring the influence of microstructure design on macroscopic properties, leading to uneven stress distribution in the fabric during use, early damage in local areas, and affecting the overall service life and performance stability. SUMMARY

[0005] The purpose of the present application is to provide a multi-thread elastic knitted fabric and a preparation method thereof, which solves the problem.

[0006] To achieve the above object, the present application is implemented by the following technical solutions: A multi-thread elastic knitted fabric, which comprises the following components in parts by weight: terpolymer elastic fiber: 30 parts; modified bamboo fiber: 70 parts; The terpolymer elastic fiber is made of the following raw material components in parts by weight: polylactic acid: 28-32 parts; polypropylene terephthalate: 38-42 parts; polybutylene succinate: 28-32 parts; graphene nanosheet: 1-3 parts; epoxidized soybean oil: 0.5-1.5 parts; β-cyclodextrin: 2-4 parts; Polylactic acid provides good biocompatibility and environmental protection properties, polypropylene terephthalate contributes excellent elastic recovery performance, and polybutylene succinate enhances the softness and comfort of the material. The three polymers form an interpenetrating network structure at the molecular level, allowing the fiber to quickly recover to its original state after stretching. Graphene nanosheet forms a heat-conducting network in the terpolymer, improving the thermal conductivity of the fiber and enhancing the mechanical strength of the fiber. Epoxidized soybean oil as a bio-based toughening agent, physically crosslinks with the polymer molecular chain, improving the toughness and elasticity of the material. β-cyclodextrin forms a packaging effect at the molecular level, fixing the polymer chain segments on one hand and releasing them when stressed on the other hand, forming a reversible molecular "spring" mechanism.

[0007] The modified bamboo fiber is treated by enzyme method, modified by silane coupling agent, coated with dopamine, and treated by ultrasonic wave.

[0008] Preferably, the terpolymer elastic fiber further comprises 0.2-0.5 parts of antioxidant and 0.3-0.6 parts of nucleating agent.

[0009] Preferably, the surface of the terpolymer elastic fiber contains 0.3-0.7 parts of phase change material microcapsules; and the surface of the modified bamboo fiber contains 0.5-1.0 parts of modified titanium dioxide nanoparticles.

[0010] Preferably, the fabric has a micro-graduated structure, the hardness of the fiber cross-section gradually decreases from inside to outside, forming an elastic gradient; and / or the fabric has an asymmetric interweaving structure, the difference in elastic modulus between the front and back of the fabric is controlled between 15-25%; and / or the fabric has a stress response structure, the microstructure rearranges when stretched.

[0011] The present application also provides a preparation method of a multi-thread elastic knitted fabric, which is used to prepare the above multi-thread elastic knitted fabric, comprising the following steps: S1, preparing ternary copolymer elastic fiber: drying polylactic acid, polytrimethylene terephthalate, polybutylene succinate, and then mixing with graphene nanosheet, epoxidized soybean oil and β-cyclodextrin, antioxidant and nucleating agent, and preparing ternary copolymer elastic fiber through spinning and pre-stretching treatment; S2, preparing modified bamboo fiber: sequentially performing enzyme treatment, silane coupling agent modification, dopamine coating treatment and ultrasonic treatment on the modified bamboo fiber; S3, functional additive treatment: performing phase change material microcapsule treatment on the ternary copolymer elastic fiber, and performing titanium dioxide nanoparticle treatment on the modified bamboo fiber; S4, weaving: mixing the treated ternary copolymer elastic fiber and the modified bamboo fiber, and weaving, wherein the length of the ternary copolymer elastic fiber is 15-20% longer than that of the modified bamboo fiber; S5, finishing: sequentially performing pre-setting treatment, biological enzyme dyeing and finished product setting.

[0012] Preferably, the preparation of the ternary copolymer elastic fiber comprises the following steps: Drying polylactic acid, polytrimethylene terephthalate and polybutylene succinate at 80-90°C under vacuum for 8-12 hours, and controlling the water content to be 0.005-0.01%; Mixing the dried raw materials with graphene nanosheet, epoxidized soybean oil and β-cyclodextrin, antioxidant and nucleating agent for melt copolymerization, and extruding in a twin-screw extruder, setting the temperature gradient of the extruder as follows: first zone 180-185°C, second zone 185-190°C, third zone 190-195°C, fourth zone 185-190°C, die 180-185°C, screw rotation speed 80-100 rpm, and vacuum degree 0.08-0.10 MPa; Cutting the extrudate into granules after water bath cooling, and controlling the cutting size to be 2-3 mm, and drying under vacuum at 100-110°C for 12-16 hours; Melt spinning the dried cut granules, melt temperature 185-195°C, spinneret hole diameter 0.2-0.3 mm, hole number 24-36, shear rate 1000-1500 s-1, and spinning speed 1200-1500 m / min; Pre-stretching the spun fiber, first stretching at 50-60°C by 10-15%, then further stretching at 60-70°C by 10-15%, then relaxing at 80-90°C for 10-15 minutes, and controlling the shrinkage rate to be 5-8%.

[0013] Preferably, the preparation of the modified bamboo fiber comprises the following steps: Soak the bamboo fibers in a 1-2 g / L non-ionic surfactant solution at a liquid ratio of 1:20 and a temperature of 40-50°C for 30-40 minutes, then rinse with soft water 3-5 times until neutral; Enzymatic treatment: prepare a cellulase solution of 1-2 g / L, add 0.2-0.4 g / L buffer salt, adjust the pH value to 6.8-7.2, soak the bamboo fibers in the enzyme solution at a liquid ratio of 1:20 and a temperature of 45-50°C for 2-4 hours, then wash with 60-70°C soft water 3-5 times, and add 0.1-0.3 g / L enzyme inhibitor to terminate the reaction; Enzymatic treatment can selectively degrade the hemicellulose and lignin on the surface of bamboo fibers, preserving the cellulose main structure, forming a micro-rough structure on the fiber surface, and increasing the specific surface area.

[0014] Silane coupling agent modification: prepare a 2-4 part KH-550 aqueous solution, adjust the pH value to 4.0-5.0, hydrolyze at room temperature for 30-60 minutes, soak the enzyme-treated bamboo fibers in the solution at a liquid ratio of 1:15 and a temperature of 60-65°C for 1-2 hours, then wash with deionized water 2-3 times, and dry at 80-90°C for 2-3 hours; The modification of the fiber surface by the silane coupling agent introduces active groups, providing chemical reaction sites for subsequent treatment.

[0015] Dopamine coating treatment: prepare a 0.8-1.2 part dopamine hydrochloride solution, add 2-4 g / L Tris buffer, adjust the pH value to 8.0-8.5, soak the silanized bamboo fibers in the solution at a liquid ratio of 1:20, treat at room temperature for 3-5 hours, add 0.05-0.10 g / L ammonium persulfate as an initiator, and wash with deionized water until neutral; Dopamine coating treatment takes advantage of the self-polymerization properties of dopamine to form a biomimetic adhesion layer on the fiber surface, not only enhancing the surface activity of the fibers, but also improving their interfacial bonding force with the ternary copolymer elastic fibers.

[0016] Ultrasonic treatment: place the dopamine-treated bamboo fibers in an ultrasonic treatment device, power 300-500 W, frequency 20-25 kHz, treatment time 30-60 minutes, pause for 1-2 minutes every 10 minutes, temperature control at 25-30°C, and dry at 60-70°C for 3-4 hours.

[0017] Ultrasonic treatment further strengthens the microstructure of the fiber surface through acoustic cavitation effects, and promotes the uniform distribution and solidification of the dopamine coating.

[0018] Preferably, the functional additive treatment includes the following steps: Phase change material microcapsule treatment: prepare 0.3-0.7 parts of phase change material microcapsule dispersion liquid, add 0.1-0.2 parts of dispersing agent, 0.2-0.4 parts of crosslinking agent, ultrasonic dispersion for 10-15 minutes, power 200-300W, immerse the terpolymer elastic fiber into the dispersion liquid, liquid ratio 1:15, temperature 40-45℃, treatment for 30-40 minutes, add 0.3-0.6 parts of color fixing agent, dry at 50-60℃ for 1-2 hours, relative humidity 40-50%, then heat set at 120-130℃ for 10-15 minutes; Titanium dioxide nanoparticle treatment: prepare 0.5-1.0 parts of modified titanium dioxide nanoparticle dispersion liquid, add 0.2-0.3 parts of coupling agent, 0.1-0.2 parts of dispersing agent, ultrasonic dispersion for 15-20 minutes, power 250-350W, immerse the modified bamboo fiber into the dispersion liquid, liquid ratio 1:15, temperature 45-50℃, treatment for 40-50 minutes, pH value 6.5-7.5, wash 1-2 times with deionized water, dry at 60-70℃ for 2-3 hours, then heat set at 130-140℃ for 5-10 minutes.

[0019] Preferably, the specific steps of the weaving in step S4 are: Yarn preparation: mix the terpolymer elastic fiber with the modified bamboo fiber, the length of the terpolymer elastic fiber is 15-20% longer than that of the modified bamboo fiber, the single yarn twist is 300-400T / m, S twist, the strand twist is 200-300T / m, Z twist, adjust the yarn humidity to 6-8%, temperature 20-25℃, humidity adjustment time 24-48 hours; Yarn sizing: the sizing formula is polyvinyl alcohol 5-8 parts, acrylate 1-2 parts, wax emulsion 0.5-1.0 parts, water 90-94 parts, sizing liquid concentration 6-8%, sizing liquid temperature 80-90℃, sizing rate 8-12%; Warping: warping speed 400-500m / min, warping tension 15-20% of the yarn breaking strength, beam density 350-400 roots / 10cm; Weaving: use high-speed electronic jacquard circular machine to implement weaving, loom speed 400-500rpm, warp tension 25-30% of the fiber breaking strength, weft tension 20-25%, implement variable frequency tension control, frequency 0.5-1.0Hz, amplitude 45GHz of the basic tension, radiation power 400-600W, pre-setting temperature 145-155℃, treatment time 90-120 seconds, pre-setting machine width 92-94% of the fabric blank width, apply 3-5 times of vacuum pulse in the setting process, each time lasts for 10-15 seconds, interval 20-30 seconds, residual pressure 50-100Pa, cooling rate 3-5℃ / min, cool to 30-35℃, relax treatment at room temperature for 4-6 hours, relative humidity 65-75%; Bio-enzyme dyeing: prepare a dyeing solution with a dye concentration of 2-4 parts of reactive dye and 1-2 parts of disperse dye, add 0.5-1.0 parts of bio-enzyme, 0.2-0.4 parts of enzyme stabilizer, 0.3-0.6 parts of buffer salt, and 2-4 parts of glycerol as a biocompatible auxiliary agent, adjust the pH value to 5.0-6.0, dye at a temperature of 85-90℃ for 30-45 minutes, with a liquor ratio of 1:15, combined with supercritical CO2 dyeing auxiliary technology, pressure 8-12 MPa, temperature 80-90℃, treatment time 20-30 minutes, washed to neutral, and washing times 3-5 times; Finished product setting: dehydration to a moisture content of 40-50%, pre-drying to a moisture content of 15-20%, temperature 80-90℃, setting temperature 130-140℃, and treatment time 60-90 seconds; Add 1-2 parts of chitosan-based softener, 0.3-0.6 parts of crosslinking agent, and 0.2-0.4 parts of emulsifier, dip at a temperature of 25-30℃, with a pick-up rate of 70-80%, apply 2-3 more vacuum pulses, each lasting 8-12 seconds, with an interval of 15-20 seconds, residual pressure 70-120 Pa, drying temperature 100-110℃, time 2-3 minutes, cool to room temperature, and obtain the finished product fabric.

[0020] In summary, the present application includes at least one of the following beneficial technical effects: 1. The multi-thread elastic knitted fabric provided by the present application realizes excellent elastic recovery performance and gradient deformation characteristics through the synergistic effect of ternary copolymer elastic fiber and modified bamboo fiber. The synergistic effect of graphene nanosheets and beta-cyclodextrin in ternary copolymer elastic fiber forms a micro-enhanced network and a reversible supramolecular structure, enabling the fabric to quickly recover to its original state after stretching and deformation, while maintaining a comfortable touch and good fit, solving the problem of easy deformation and misalignment of traditional elastic fabrics, and providing an ideal solution for close-fitting wear.

[0021] 2. The multi-step treatment process (enzyme treatment, silane coupling agent modification, dopamine coating treatment, and ultrasonic treatment) of the modified bamboo fiber used in the present application significantly improves the comfort and functionality of the fabric. The dopamine coating forms a dense functional layer on the fiber surface through its self-polymerization property, enhancing the hydrophilicity and surface activity of the fiber; ultrasonic treatment improves the microstructure and internal channels of the fiber through cavitation effect, promoting the deep penetration of functional molecules. This multi-level modification treatment enables the fabric to have excellent air permeability, moisture absorption, and thermal and moisture regulation capabilities, providing users with a comfortable all-weather wearing experience.

[0022] 3.The functional additive treatment technology of the present application firmly combines phase change material microcapsules and modified titanium dioxide nanoparticles to the surface of fibers, endowing the fabric with intelligent temperature regulation and excellent antibacterial and ultraviolet resistance. Phase change materials regulate the temperature of the fabric by absorbing and releasing latent heat, while modified titanium dioxide inhibits bacterial growth and effectively blocks ultraviolet radiation through photocatalytic action. This multifunctional integrated design enables the fabric to maintain basic performance while possessing environmental adaptability and health protection functions, meeting the diverse needs of modern consumers for high-quality functional textiles.

[0023] 4.The present application adopts the pre-reserve length difference design of ternary copolymer elastic fiber and modified bamboo fiber and the variable frequency tension control weaving process, realizing the micro- gradient structure and macro-uniformity of the fabric. This structural design enables the fabric to realize step-by-step dispersion and slow release of stress during stretching, avoiding early damage caused by local stress concentration, while maintaining the dimensional stability and appearance flatness of the fabric. Combined with the precisely controlled finishing process, the fabric of the present application exhibits excellent durability and service life, and can maintain good performance and appearance even after multiple washes and long-term wear, providing technical support for sustainable fashion. DETAILED DESCRIPTION

[0024] The present application is further described below.

[0025] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0026] Example 1: The present application provides a multi-thread elastic knitted fabric, which comprises the following components in parts by weight: ternary copolymer elastic fiber 30 parts and modified bamboo fiber 70 parts. The ternary copolymer elastic fiber is made of polylactic acid 30 parts, polytrimethylene terephthalate 40 parts, polybutylene succinate 30 parts, graphene nanosheet 2 parts, epoxidized soybean oil 1 part, β-cyclodextrin 3 parts, antioxidant (2,6-di-tert-butyl-4-methylphenol) 0.35 parts, and nucleating agent (sodium benzoate) 0.45 parts. The surface of the ternary copolymer elastic fiber contains 0.5 parts of phase change material microcapsules (n-octadecane microcapsules), and the surface of the modified bamboo fiber contains 0.75 parts of modified titanium dioxide nanoparticles (modified by silane coupling agent KH-570).

[0027] The preparation method of the knitted fabric is as follows: S1, preparation of terpolymer elastic fiber: polylactic acid, polytrimethylene terephthalate, polybutylene succinate are vacuum dried at 85°C for 10 hours, the water content is controlled at 0.0075%; the dried raw materials are mixed with graphene nanosheet, epoxidized soybean oil, β-cyclodextrin, antioxidant and nucleating agent for melt copolymerization, and are placed in a twin-screw extruder for extrusion, the temperature gradient of the extruder is set as: first zone 182°C, second zone 187°C, third zone 192°C, fourth zone 187°C, die 182°C, screw rotation speed 90 rpm, vacuum degree 0.09 MPa; the extrudate is cooled in a water bath and then pelletized, the pellet size is 2.5 mm, and the dried pellets are vacuum dried at 105°C for 14 hours; the dried pellets are melt spun, the melt temperature is 190°C, the spinneret aperture is 0.25 mm, the number of holes is 30, the shear rate is 1250 s -1 , the spinning speed is 1350 m / min; the spun fiber is pre-stretched, first stretched at 55°C by 12.5%, then further stretched at 65°C by 12.5%, then relaxed at 85°C for 12 minutes, and the shrinkage rate is controlled at 6.5%.

[0028] S2, preparation of modified bamboo fiber: the bamboo fiber is soaked in a 1.5 g / L non-ionic surfactant (polyoxyethylene ether) solution, the liquid ratio is 1:20, the temperature is 45°C, and the treatment time is 35 minutes, and the bamboo fiber is washed with soft water for 4 times until neutral; enzyme treatment: a cellulase (derived from Trichoderma) solution of 1.5 g / L is prepared, 0.3 g / L phosphate buffer salt is added, the pH value is adjusted to 7.0, the bamboo fiber is soaked in the enzyme solution, the liquid ratio is 1:20, the temperature is 47.5°C, and the treatment time is 3 hours, the bamboo fiber is washed with 65°C soft water for 4 times, and 0.2 g / L enzyme inhibitor (disodium EDTA) is added to terminate the reaction; silane coupling agent modification: 3 parts of KH-550 (γ-aminopropyl triethoxysilane) aqueous solution is prepared, the pH value is adjusted to 4.5 (adjusted with glacial acetic acid), and hydrolysis is carried out at room temperature for 45 minutes, the enzyme-treated bamboo fiber is soaked in the solution, the liquid ratio is 1:15, the temperature is 62.5°C, and the treatment time is 1.5 hours, the bamboo fiber is washed with deionized water for 2 times, and is dried at 85°C for 2.5 hours; dopamine coating treatment: 1 part of dopamine hydrochloride solution is prepared, 3 g / L of Tris (tris-hydroxymethyl aminomethane) buffer is added, the pH value is adjusted to 8.25 (adjusted with sodium hydroxide solution), the silanized bamboo fiber is soaked in the solution, the liquid ratio is 1:20, and the treatment time is 4 hours at room temperature, 0.075 g / L of ammonium persulfate is added as an initiator, and the bamboo fiber is washed with deionized water until neutral; ultrasonic treatment: the dopamine-treated bamboo fiber is placed in an ultrasonic treatment device, the power is 400 W, the frequency is 22.5 kHz, the treatment time is 45 minutes, the treatment is paused for 1.5 minutes every 10 minutes, the temperature is controlled at 27.5°C, and the bamboo fiber is dried at 65°C for 3.5 hours.

[0029] S3, functional additive treatment: phase change material microcapsule treatment: prepare 0.5 parts of phase change material microcapsule dispersion, add 0.15 parts of dispersant (polyvinylpyrrolidone), 0.3 parts of crosslinking agent (N-methyl acrylamide), ultrasonic dispersion for 12.5 minutes, power 250W, immerse the terpolymer elastic fiber into the dispersion, liquid ratio 1:15, temperature 42.5℃, treat for 35 minutes, add 0.45 parts of color fixing agent (polyurethane resin), dry at 55℃ for 1.5 hours, relative humidity 45%, then heat and solidify at 125℃ for 12.5 minutes; titanium dioxide nanoparticle treatment: prepare 0.75 parts of modified titanium dioxide nanoparticle dispersion, add 0.25 parts of coupling agent (KH-570, γ-methacryloxypropyltrimethoxysilane), 0.15 parts of dispersant (polyethylene glycol), ultrasonic dispersion for 17.5 minutes, power 300W, immerse the modified bamboo fiber into the dispersion, liquid ratio 1:15, temperature 47.5℃, treat for 45 minutes, pH value 7.0 (adjust with phosphate buffer), wash once with deionized water, dry at 65℃ for 2.5 hours, then heat and solidify at 135℃ for 7.5 minutes.

[0030] S4, weaving: yarn preparation: mix the terpolymer elastic fiber with the modified bamboo fiber, the linear length of the terpolymer elastic fiber is 17.5% longer than that of the modified bamboo fiber, single yarn twist 350T / m, S twist, ply twist 250T / m, Z twist, adjust the yarn humidity to 7%, temperature 22.5℃, humidity adjusting time 36 hours; yarn sizing: the sizing formula is polyvinyl alcohol 6.5 parts, acrylate 1.5 parts, wax emulsion 0.75 parts, water 91.25 parts, sizing liquid concentration 7%, sizing liquid temperature 85℃, sizing rate 10%; beaming: beaming speed 450m / min, beaming tension 17.5% of the yarn breaking strength, beam density 375 ends / 10cm; weaving: use high-speed electronic jacquard circular machine to implement weaving, loom speed 450rpm, warp tension 27.5% of the fiber breaking strength, weft tension 22.5%, implement variable frequency tension control, frequency 0.75Hz, amplitude ±5% of the basic tension, weaving environment temperature 24℃, relative humidity 60%, fabric density: warp density 375 ends / 10cm, weft density 300 ends / 10cm.

[0031] S5, finishing: pre-setting treatment: enzyme desizing of the fabric, enzyme concentration 1.5 g / L, temperature 55℃, time 35 minutes, centrifugal dehydration to 45% moisture content after washing, pre-setting by controllable microwave radiation technology, frequency 2.45 GHz, radiation power 500 W, pre-setting temperature 150℃, processing time 105 seconds, pre-setting rack width is 93% of the fabric blank width, 4 vacuum pulses are applied during setting, each lasting 12.5 seconds, interval 25 seconds, residual pressure 75 Pa, cooling rate 4℃ / min, cooling to 32.5℃, relaxation treatment at room temperature for 5 hours, relative humidity 70%; bio-enzyme dyeing: preparation of dyeing solution, dye concentration is 3 parts of reactive dye, 1.5 parts of disperse dye, 0.75 parts of bio-enzyme, 0.3 parts of enzyme stabilizer, 0.45 parts of buffer salt, 3 parts of glycerol as biocompatible auxiliary agent, adjust pH to 5.5, dyeing temperature 87.5℃, dyeing time 37.5 minutes, liquid ratio 1:15, combined with supercritical CO2 dyeing auxiliary technology, pressure 10 MPa, temperature 85℃, processing time 25 minutes, washing to neutral, washing times 4 times; finished product setting: dehydration to 45% moisture content, pre-drying to 17.5% moisture content, temperature 85℃, setting temperature 135℃, processing time 75 seconds; addition of 1.5 parts of chitosan-based softener, crosslinking agent 0.45 parts, emulsifier 0.3 parts, padding temperature 27.5℃, pick-up rate 75%, again 2 vacuum pulses are applied, each lasting 10 seconds, interval 17.5 seconds, residual pressure 95 Pa, drying temperature 105℃, time 2.5 minutes, cooling to room temperature to obtain finished fabric.

[0032] Example 2: The application provides a multi-thread elastic knitted fabric, which comprises the following components in parts by weight: 30 parts of ternary copolymer elastic fiber and 70 parts of modified bamboo fiber. The ternary copolymer elastic fiber is made of 28 parts of polylactic acid, 38 parts of polypropylene terephthalate, 28 parts of polybutylene succinate, 1 part of graphene nanosheet, 0.5 part of epoxidized soybean oil, 2 parts of β-cyclodextrin, 0.2 part of antioxidant (2,6-di-tert-butyl-4-methylphenol) and 0.3 part of nucleating agent (sodium benzoate). The surface of the ternary copolymer elastic fiber contains 0.3 parts of phase change material microcapsules (n-octadecane microcapsules), and the surface of the modified bamboo fiber contains 0.5 parts of modified titanium dioxide nanoparticles (modified by silane coupling agent KH-570).

[0033] The preparation method of the knitted fabric is as follows: S1, preparation of terpolymer elastic fiber: polylactic acid, polytrimethylene terephthalate, polybutylene succinate were vacuum dried at 80°C for 8 hours, the water content was controlled at 0.005%; the dried raw materials were mixed with graphene nanosheet, epoxidized soybean oil, β-cyclodextrin, antioxidant and nucleating agent, and were extruded in a twin-screw extruder, the temperature gradient of the extruder was set as: first zone 180°C, second zone 185°C, third zone 190°C, fourth zone 185°C, die 180°C, screw rotation speed 80 rpm, vacuum degree 0.08 MPa; the extrudate was cooled in water bath and then pelletized, the pellet size was 2 mm, and the pellets were vacuum dried at 100°C for 12 hours; the dried pellets were melt spun, the melt temperature was 185°C, the spinneret aperture was 0.2 mm, the number of holes was 24, the shear rate was 1000 s -1 , the spinning speed was 1200 m / min; the spun fiber was pre-stretched, first stretched by 10% at 50°C, then further stretched by 10% at 60°C, then relaxed at 80°C for 10 minutes, and the shrinkage was controlled at 5%.

[0034] S2, preparation of modified bamboo fiber: the bamboo fiber was soaked in a 1 g / L non-ionic surfactant (polyoxyethylene ether) solution, liquid ratio 1:20, temperature 40°C, treatment time 30 minutes, washed with soft water for 3 times to neutral; enzyme treatment: cellulase (derived from Trichoderma) solution 1 g / L, 0.2 g / L phosphate buffer salt was added, pH value was adjusted to 6.8, the bamboo fiber was soaked in the enzyme solution, liquid ratio 1:20, temperature 45°C, treatment time 2 hours, washed with 60°C soft water for 3 times, 0.1 g / L enzyme inhibitor (disodium EDTA) was added to terminate the reaction; silane coupling agent modification: 2 parts of KH-550 (γ-aminopropyl triethoxysilane) aqueous solution was prepared, the pH value was adjusted to 4.0 (adjusted with glacial acetic acid), hydrolyzed at room temperature for 30 minutes, the enzyme-treated bamboo fiber was immersed in the solution, liquid ratio 1:15, temperature 60°C, treatment time 1 hour, washed with deionized water for 2 times, dried at 80°C for 2 hours; dopamine coating treatment: 0.8 parts of dopamine hydrochloride solution was prepared, 2 g / L of Tris (tris-hydroxymethyl aminomethane) buffer was added, the pH value was adjusted to 8.0 (adjusted with sodium hydroxide solution), the silanized bamboo fiber was immersed in the solution, liquid ratio 1:20, treatment time 3 hours at room temperature, 0.05 g / L of ammonium persulfate was added as initiator, washed with deionized water to neutral; ultrasonic treatment: the dopamine-treated bamboo fiber was placed in an ultrasonic treatment device, power 300 W, frequency 20 kHz, treatment time 30 minutes, pause for 1 minute every 10 minutes, temperature controlled at 25°C, dried at 60°C for 3 hours.

[0035] S3, functional additive treatment: phase change material microcapsule treatment: prepare 0.3 parts of phase change material microcapsule dispersion liquid, add 0.1 parts of dispersant (polyvinylpyrrolidone), 0.2 parts of crosslinking agent (N-methyl acrylamide), ultrasonic dispersion for 10 minutes, power 200W, immerse the terpolymer elastic fiber into the dispersion liquid, liquid ratio 1:15, temperature 40℃, treat for 30 minutes, add 0.3 parts of color fixing agent (polyurethane resin), dry at 50℃ for 1 hour, relative humidity 40%, then heat and solidify at 120℃ for 10 minutes; titanium dioxide nanoparticle treatment: prepare 0.5 parts of modified titanium dioxide nanoparticle dispersion liquid, add 0.2 parts of coupling agent (KH-570, γ-methacryloxypropyltrimethoxysilane), 0.1 parts of dispersant (polyethylene glycol), ultrasonic dispersion for 15 minutes, power 250W, immerse the modified bamboo fiber into the dispersion liquid, liquid ratio 1:15, temperature 45℃, treat for 40 minutes, pH value 6.5 (adjust with phosphate buffer), wash once with deionized water, dry at 60℃ for 2 hours, then heat and solidify at 130℃ for 5 minutes.

[0036] S4, weaving: yarn preparation: mix the terpolymer elastic fiber with the modified bamboo fiber, the linear length of the terpolymer elastic fiber is 15% longer than that of the modified bamboo fiber, the single yarn twist is 300T / m, S twist, the strand twist is 200T / m, Z twist, adjust the yarn humidity to 6%, temperature 20℃, humidity adjusting time 24 hours; yarn sizing: the sizing formula is polyvinyl alcohol 5 parts, acrylate 1 part, wax emulsion 0.5 parts, water 93.5 parts, sizing liquid concentration 6%, sizing liquid temperature 80℃, sizing rate 8%; beaming: beaming speed 400m / min, beaming tension is 15% of the yarn breaking strength, beam density 350 roots / 10cm; weaving: use high-speed electronic jacquard circular machine to implement weaving, loom speed 400rpm, warp tension is 25% of the fiber breaking strength, weft tension is 20%, implement variable frequency tension control, frequency 0.5Hz, amplitude is ±5% of the basic tension, weaving environment temperature 22℃, relative humidity 55%, fabric density: warp density 350 roots / 10cm, weft density 280 roots / 10cm.

[0037] S5, finishing: pre-setting treatment: enzyme desizing of the fabric, enzyme concentration 1 g / L, temperature 50℃, time 30 minutes, centrifugal dehydration to 40% moisture content after washing, pre-setting by controllable microwave radiation technology, frequency 2.45 GHz, radiation power 400 W, pre-setting temperature 145℃, processing time 90 seconds, pre-setting rack width is 92% of the fabric blank width, 3 times of vacuum pulse is applied during setting, each time lasts for 10 seconds, interval 20 seconds, residual pressure 50 Pa, cooling rate 3℃ / min, cooling to 30℃, relaxation treatment at room temperature for 4 hours, relative humidity 65%; biological enzyme dyeing: preparation of dyeing solution, dye concentration is 2 parts of reactive dye and 1 part of disperse dye, 0.5 parts of biological enzyme, 0.2 parts of enzyme stabilizer, 0.3 parts of buffer salt, 2 parts of glycerol as biological compatibility aid, adjust pH value to 5.0, dyeing temperature 85℃, dyeing time 30 minutes, liquid ratio 1:15, combined with supercritical CO2 dyeing auxiliary technology, pressure 8 MPa, temperature 80℃, processing time 20 minutes, washing to neutral, washing times 3 times; finished product setting: dehydration to 40% moisture content, pre-drying to 15% moisture content, temperature 80℃, setting temperature 130℃, processing time 60 seconds; add 1 part of chitosan-based softener, crosslinking agent 0.3 parts, emulsifier 0.2 parts, padding temperature 25℃, pick-up rate 70%, apply 2 times of vacuum pulse again, each time lasts for 8 seconds, interval 15 seconds, residual pressure 70 Pa, drying temperature 100℃, time 2 minutes, cool to room temperature, to obtain finished fabric.

[0038] Example 3: The application provides a multi-thread elastic knitted fabric, which comprises the following components in parts by weight: 30 parts of ternary copolymer elastic fiber and 70 parts of modified bamboo fiber. The ternary copolymer elastic fiber is made of 32 parts of polylactic acid, 42 parts of polytrimethylene terephthalate, 32 parts of polybutylene succinate, 3 parts of graphene nanosheet, 1.5 parts of epoxidized soybean oil, 4 parts of β-cyclodextrin, 0.5 part of antioxidant (2,6-di-tert-butyl-4-methylphenol) and 0.6 part of nucleating agent (sodium benzoate). The surface of the ternary copolymer elastic fiber contains 0.7 parts of phase change material microcapsules (n-octadecane microcapsules), and the surface of the modified bamboo fiber contains 1.0 part of modified titanium dioxide nanoparticles (modified by silane coupling agent KH-570).

[0039] The preparation method of the knitted fabric is as follows: S1, preparation of terpolymer elastic fiber: polylactic acid, polytrimethylene terephthalate, polybutylene succinate were vacuum dried at 90°C for 12 hours, the water content was controlled at 0.01%; the dried raw materials were mixed with graphene nanosheet, epoxidized soybean oil, β-cyclodextrin, antioxidant and nucleating agent, and were extruded in a twin-screw extruder, the temperature gradient of the extruder was set as: first zone 185°C, second zone 190°C, third zone 195°C, fourth zone 190°C, die 185°C, screw rotation speed 100 rpm, vacuum degree 0.10 MPa; the extrudate was cooled in a water bath and then pelletized, the pellet size was 3 mm, and the pellets were vacuum dried at 110°C for 16 hours; the dried pellets were melt spun, the melt temperature was 195°C, the spinneret aperture was 0.3 mm, the number of holes was 36, the shear rate was 1500 s -1 , the spinning speed was 1500 m / min; the spun fiber was pre-stretched, first stretched by 15% at 60°C, then further stretched by 15% at 70°C, then relaxed at 90°C for 15 minutes, and the shrinkage was controlled at 8%.

[0040] S2, preparation of modified bamboo fiber: the bamboo fiber was soaked in a 2 g / L non-ionic surfactant (polyoxyethylene ether) solution, liquid ratio 1:20, temperature 50°C, treatment time 40 minutes, washed with soft water for 5 times to neutral; enzyme treatment: cellulase (derived from Trichoderma) solution 2 g / L, 0.4 g / L phosphate buffer salt was added, pH value was adjusted to 7.2, the bamboo fiber was soaked in the enzyme solution, liquid ratio 1:20, temperature 50°C, treatment time 4 hours, washed with 70°C soft water for 5 times, 0.3 g / L enzyme inhibitor (disodium EDTA) was added to terminate the reaction; silane coupling agent modification: 4 parts of KH-550 (γ-aminopropyl triethoxysilane) aqueous solution was prepared, the pH value was adjusted to 5.0 (adjusted with glacial acetic acid), hydrolyzed at room temperature for 60 minutes, the enzyme-treated bamboo fiber was immersed in the solution, liquid ratio 1:15, temperature 65°C, treatment time 2 hours, washed with deionized water for 3 times, dried at 90°C for 3 hours; dopamine coating treatment: 1.2 parts of dopamine hydrochloride solution was prepared, 4 g / L of Tris (tris-hydroxymethyl aminomethane) buffer was added, the pH value was adjusted to 8.5 (adjusted with sodium hydroxide solution), the silanized bamboo fiber was immersed in the solution, liquid ratio 1:20, treated at room temperature for 5 hours, 0.10 g / L of ammonium persulfate was added as initiator, washed with deionized water to neutral; ultrasonic treatment: the dopamine-treated bamboo fiber was placed in an ultrasonic treatment device, power 500 W, frequency 25 kHz, treatment time 60 minutes, pause every 10 minutes for 2 minutes, temperature control at 30°C, dried at 70°C for 4 hours.

[0041] S3, functional additive treatment: phase change material microcapsule treatment: prepare 0.7 parts of phase change material microcapsule dispersion liquid, add 0.2 parts of dispersant (polyvinylpyrrolidone), 0.4 parts of crosslinking agent (N-methyl acrylamide), ultrasonic dispersion for 15 minutes, power 300W, immerse the terpolymer elastic fiber into the dispersion liquid, liquid ratio 1:15, temperature 45℃, treatment for 40 minutes, add 0.6 parts of color fixing agent (polyurethane resin), dry at 60℃ for 2 hours, relative humidity 50%, then heat and solidify at 130℃ for 15 minutes; titanium dioxide nanoparticle treatment: prepare 1.0 parts of modified titanium dioxide nanoparticle dispersion liquid, add 0.3 parts of coupling agent (KH-570, γ-methacryloxypropyltrimethoxysilane), 0.2 parts of dispersant (polyethylene glycol), ultrasonic dispersion for 20 minutes, power 350W, immerse the modified bamboo fiber into the dispersion liquid, liquid ratio 1:15, temperature 50℃, treatment for 50 minutes, pH value 7.5 (adjusted with phosphate buffer), wash twice with deionized water, dry at 70℃ for 3 hours, then heat and solidify at 140℃ for 10 minutes.

[0042] S4, weaving: yarn preparation: mix the terpolymer elastic fiber with the modified bamboo fiber, the linear length of the terpolymer elastic fiber is 20% longer than that of the modified bamboo fiber, the single yarn twist is 400T / m, S twist, the strand twist is 300T / m, Z twist, adjust the yarn humidity to 8%, temperature 25℃, humidity adjustment time 48 hours; yarn sizing: the sizing formula is polyvinyl alcohol 8 parts, acrylate 2 parts, wax emulsion 1.0 part, water 89 parts, sizing liquid concentration 8%, sizing liquid temperature 90℃, sizing rate 12%; beaming: beaming speed 500m / min, beaming tension is 20% of the yarn breaking strength, beam density 400 roots / 10cm; weaving: use high-speed electronic jacquard circular machine to implement weaving, loom speed 500rpm, warp tension is 30% of the fiber breaking strength, weft tension is 25%, implement variable frequency tension control, frequency 1.0Hz, amplitude is ±5% of the basic tension, weaving environment temperature 26℃, relative humidity 65%, fabric density: warp density 400 roots / 10cm, weft density 320 roots / 10cm.

[0043] S5, finishing: pre-setting treatment: enzyme desizing of the fabric, enzyme concentration 2 g / L, temperature 60℃, time 40 minutes, centrifugal dehydration to 50% moisture content after washing, pre-setting by controllable microwave radiation technology, frequency 2.45 GHz, radiation power 600 W, pre-setting temperature 155℃, treatment time 120 seconds, pre-setting rack width is 94% of the fabric blank width, 5 vacuum pulses are applied during setting, each lasting 15 seconds, interval 30 seconds, residual pressure 100 Pa, cooling rate 5℃ / min, cooling to 35℃, relaxation treatment at room temperature for 6 hours, relative humidity 75%; bio-enzyme dyeing: preparation of dyeing solution, dye concentration is 4 parts of reactive dye and 2 parts of disperse dye, 1.0 part of bio-enzyme, 0.4 part of enzyme stabilizer, 0.6 part of buffer salt, 4 parts of glycerol as a biocompatible auxiliary agent, adjust pH to 6.0, dyeing temperature 90℃, dyeing time 45 minutes, liquor ratio 1:15, combined with supercritical CO2 dyeing auxiliary technology, pressure 12 MPa, temperature 90℃, treatment time 30 minutes, washing to neutral, washing times 5 times; finished product setting: dehydration to 50% moisture content, pre-drying to 20% moisture content, temperature 90℃, setting temperature 140℃, treatment time 90 seconds; add 2 parts of chitosan-based softener, crosslinking agent 0.6 parts, emulsifier 0.4 parts, padding temperature 30℃, pick-up rate 80%, apply 3 vacuum pulses again, each lasting 12 seconds, interval 20 seconds, residual pressure 120 Pa, drying temperature 110℃, time 3 minutes, cool to room temperature, to get finished fabric.

[0044] Comparative Example 1: Compared with Example 1, the difference is that no graphene nanosheet is added in the ternary copolymer elastic fiber, and the rest is the same.

[0045] Comparative Example 2: Compared with Example 1, the difference is that the amount of polylactic acid in the ternary copolymer elastic fiber is 25 parts, and the rest is the same.

[0046] Comparative Example 3: Compared with Example 1, the difference is that the modified bamboo fiber is only treated by enzyme and silane coupling agent modification, and the rest is the same.

[0047] Comparative Example 4: Compared with Example 1, the difference is that the ratio of ternary copolymer elastic fiber to modified bamboo fiber is 20:80, and the rest is the same.

[0048] Comparative Example 5: Compared with Example 1, the difference is that no β-cyclodextrin is added in the ternary copolymer elastic fiber, and the rest is the same.

[0049] Comparative Example 6: Compared with Example 1, the difference is that the surface of the ternary copolymer elastic fiber is not treated with phase change material microcapsules, and the surface of the modified bamboo fiber is not treated with titanium dioxide nanoparticles, and the rest is the same.

[0050] Comparative Example 7: Compared with Example 1, the difference is that the linear length of the ternary copolymerized elastic fiber is the same as that of the modified bamboo fiber during weaving, and the rest is the same.

[0051] Comparative Example 8: Compared with Example 1, the difference is that the amount of epoxidized soybean oil is 2.5 parts, and the rest is the same.

[0052] Test Example 1: Experimental Steps: Sample Preparation: The fabric of Example 1 and Comparative Examples 1-8 was cut into standard test samples with a size of 250mm x 50mm, and 5 parallel samples were prepared for each fabric.

[0053] The test samples were placed in standard atmospheric conditions (temperature 21 °C, relative humidity 65%).

[0054] Multi-step cyclic loading-unloading tests were conducted at a strain rate of 0.5% / min: First cycle: 0-10% strain; Second cycle: 0-20% strain; Third cycle: 0-30% strain; Each cycle was held for 60 seconds after loading to the target strain, then unloaded to 0.01N, and held for another 60 seconds.

[0055] The stress-strain curves of each cycle were recorded, and the modulus changes at each stage were calculated.

[0056] Data Processing: The test data was statistically analyzed using SPSS 25.0 software.

[0057] The average value, standard deviation and coefficient of variation of each index were calculated.

[0058] An analysis of variance (ANOVA) was performed to evaluate the significance of the performance differences between different samples, and the test results are shown in Table 1.

[0059] Table 1: Physical performance test results of Example 1 and Comparative Examples 1-8 fabrics From Table 1, we can see that: The fabric of Example 1 exhibits excellent physical properties, especially in terms of elastic recovery rate, breaking strength and modulus change rate. This is mainly due to the synergistic effect of graphene nanosheets and β-cyclodextrin in the ternary copolymerized elastic fiber. The graphene nanosheets form a network-like reinforcing structure in the polymer matrix through their two-dimensional sheet structure, improving the mechanical strength of the material. The β-cyclodextrin forms a supramolecular inclusion complex with the polymer chain segment through its special ring structure, enhancing the reversible interaction between molecules, thereby improving the elastic recovery performance of the material.

[0060] The reasonable ratio of the terpolymer elastic fiber and the modified bamboo fiber and the design of the elastic fiber reserved length enable the fabric to realize the step-by-step dispersion and slow release of stress during the stretching process. The comparative example 7 lacks the elastic fiber reserved length, and the modulus change rate thereof is only 15.9%, which shows a relatively rigid mechanical property and cannot realize the rearrangement of the microstructure in the stress response structure, which further confirms the key role of the design of the elastic fiber reserved length in the present application.

[0061] The comparative example 3 omits the dopamine coating treatment and the ultrasonic treatment steps, and the breaking strength and the elastic recovery rate thereof are obviously lower than those of the example 1. The dopamine coating forms a dense functional layer on the fiber surface through the self-polymerization property thereof, enhances the interfacial bonding force between the fibers, and the ultrasonic treatment improves the surface morphology and the internal structure of the fiber through the cavitation effect and promotes the deep penetration of the functional molecules.

[0062] Test example 2: Experimental steps: Sample preparation: The fabric of the example 1 and the comparative examples 1-8 is cut into a standard sample size suitable for each test item.

[0063] All the samples are placed under standard atmospheric conditions (temperature 212 mL of bacterial suspension is uniformly added to the sample, and placed at 370 software to statistically analyze the test data.

[0064] The average value, the standard deviation and the coefficient of variation of each index are calculated.

[0065] The variance analysis (ANOVA) is performed to evaluate the significance (p<0.05) of the performance difference between different samples.

[0066] The comprehensive comfort index CSI is calculated, and the formula is CSI=(APx0.3)+(MRx0.3)+(1 / Rx0.2)+(BRx0.1)+(UPFx0.1), wherein AP is the air permeability, MR is the moisture absorption rate, R is the thermal resistance value, BR is the antibacterial rate, and UPF is the ultraviolet protection coefficient, and the test results are shown in Table 2.

[0067] Table 2: Comfort and functionality test results of the fabric of the example 1 and the comparative examples 1-8 From Table 2, it can be obtained that: Example 1 performs outstanding in terms of comfort and functionality, which is achieved by multi-level material structure design and functional treatment process. The modified bamboo fibers are subjected to multi-step treatment process, which significantly improves the air permeability and moisture absorption of the fabric. The enzyme treatment effectively removes impurities and hydrophobic substances from the surface of the fibers, increasing the specific surface area of the fibers. The dopamine coating enhances the hydrophilicity of the fibers through its rich hydroxyl and amino structures, forming effective capillary channels. The ultrasonic treatment further optimizes the microstructure of the fibers, forming a micro-nano scale rough structure on the surface of the fibers, enhancing the adsorption capacity of water molecules. Comparative Example 3 lacks dopamine coating and ultrasonic treatment, and its air permeability and moisture absorption decrease by about 30% and 35%, respectively.

[0068] Silane coupling agent KH-570 modified titanium dioxide nanoparticles form a stable functional layer through covalent bonding with the surface of the bamboo fibers, producing photocatalytic activity under ultraviolet light, effectively inhibiting bacterial growth. At the same time, its high refractive index property enables it to effectively scatter and absorb ultraviolet rays, providing excellent UV protection performance. Comparative Example 6 does not undergo functional additive treatment, and its antibacterial rate and UPF value decrease to about 30% and 28% of Example 1, respectively, indicating that functional additive treatment is a key step to achieve fabric functionality.

[0069] The cavity structure of β-cyclodextrin can reversibly adsorb water molecules, acting as a buffer when the environmental humidity changes. The n-octadecane microcapsules absorb and release latent heat through the phase change process, regulating the temperature of the fabric. This micro-level heat and moisture regulation mechanism enables Example 1 to maintain a low thermal resistance value (14.2 x 10 -3 m 2 ·K / W), effectively improving the comfort of the fabric. The overall comfort index reaches 89.5, far higher than the comparative examples, especially Comparative Example 6 (52.6), achieving the unity of high comfort and multi-functionality.

[0070] Test Example 3: Experimental Steps: Sample Preparation: Cut the fabric of Example 1 and Comparative Examples 1-8 into standard sample sizes suitable for each test item.

[0071] Pre-treat all samples under standard atmospheric conditions (temperature 21±1℃, relative humidity 65±2%) for 24 hours.

[0072] Prepare a sufficient number of parallel samples for each fabric to meet the testing requirements after multiple washes.

[0073] Abrasion Resistance Test: Use YG401E Martindale Abrasion Tester.

[0074] The sample was cut into a circle with a diameter of 38 mm and fixed on the sample holder of the abrasion tester.

[0075] A standard wool abrasive was used with a pressure of 9 kPa applied.

[0076] The test endpoint was set as the occurrence of two yarn breakages or the formation of a hole in the sample.

[0077] The number of rubs until the endpoint was reached was recorded.

[0078] Four parallel samples were tested for each sample, and the average and standard deviation were calculated.

[0079] At the same time, after 5000, 10000, 15000, and 20000 rubs, the mass loss of the sample was measured using an electronic balance (precision 0.0001 g).

[0080] Washing resistance test: A SW-12A fabric washing color fastness tester was used.

[0081] The sample was cut into a square of 100 mm x 100 mm.

[0082] The washing solution was prepared: 4 g of standard detergent (without fluorescent whitening agent) was added per liter of water.

[0083] The washing conditions were set: temperature 40 ± 2°C, washing time 45 minutes, number of steel beads 10.

[0084] After washing was complete, the samples were rinsed twice with clean water for 3 minutes each, and then air-dried at room temperature.

[0085] Cycles of 5, 10, 20, and 50 washes were performed.

[0086] After each washing cycle, the following indicators were measured: Breaking strength retention rate: the breaking strength was tested, and the percentage compared to the initial value was calculated.

[0087] Dimensional stability: the changes in length and width of the sample were measured, and the dimensional change rate was calculated.

[0088] Color change: the color parameters (Lab*) of the sample were measured using a spectrophotometer, and the color difference ΔE was calculated.

[0089] Pilling resistance test: A YG502 random rotating pilling tester was used.

[0090] The sample was cut into a square of 125 mm x 125 mm and sewn into a cylindrical shape.

[0091] The sample was fitted over the polyurethane tube of the pilling tester, and 3 samples and 25 mg of cotton wool were placed in each box.

[0092] The rotational speed was set to 60 ± 2 r / min, and the test time was 30 minutes, 60 minutes, 90 minutes, and 120 minutes.

[0093] At each time point, the sample was taken out and compared with the standard photo to evaluate the pilling grade (1-5 grade, 5 grade being the best).

[0094] At the same time, the digital image analysis system was used to quantitatively evaluate the pilling situation: High-definition images of the sample surface were taken.

[0095] Image processing software was used to calculate the pilling density (pieces / cm 2 ), average pilling area (mm 2 ), and pilling coverage (%).

[0096] Light fastness test: A xenon arc lamp weathering tester was used.

[0097] The sample was cut into a rectangle of 45 mm x 100 mm. The test conditions were set as follows: irradiance was 550 W / m 2 (300-400 nm waveband), black standard temperature was 63 ± 3 °C, and relative humidity was 50 ± 5%.

[0098] Exposure was carried out for 20 hours, 40 hours, 60 hours, and 80 hours, respectively.

[0099] At each exposure time point, the color change (gray sample card 1-5 grade) and physical property change of the sample were evaluated.

[0100] Data processing: SPSS 25.0 software was used for statistical analysis of the test data.

[0101] The mean, standard deviation, and coefficient of variation of each index were calculated.

[0102] Analysis of variance (ANOVA) was performed to evaluate the significance of the performance difference between different samples (p < 0.05).

[0103] The comprehensive durability index CDI was calculated, with the formula CDI = (AR x 0.3) + (SR x 0.3) + (PR x 0.25) + (CR x 0.15), where AR is the wear resistance performance index, SR is the strength retention rate, PR is the anti-pilling grade, and CR is the color fastness grade. The test results are shown in Table 3.

[0104] Table 3: Durability test results of the fabric of Example 1 and Comparative Examples 1-8 From Table 3, it can be seen that: Example 1 exhibits excellent durability performance through the component ratio of terpolymer elastic fiber and the multi-step processing of modified bamboo fiber. The graphene nanosheets in the terpolymer elastic fiber form a network-like reinforcing structure in the polymer matrix through its two-dimensional sheet structure, significantly improving the wear resistance of the material; and the β-cyclodextrin enhances the reversible interaction between molecules by forming a supramolecular inclusion complex with the polymer segment, thereby improving the strength retention rate of the material after repeated washing. The component ratio of Comparative Example 2 and Comparative Example 8 deviates from the optimal range, resulting in a significant decrease in the number of wear times and the strength retention rate, which confirms the key role of component ratio optimization in fabric durability.

[0105] Enzymatic treatment removes the tiny burrs on the surface of the fiber, silane coupling agent modification enhances the surface smoothness of the fiber, and dopamine coating treatment forms a dense protective layer on the surface of the fiber. The synergistic effect of these processes significantly reduces the tendency of fiber pilling during the rubbing process. The fiber ratio of Comparative Example 4 is unreasonable, resulting in an anti-pilling rating of only 2.5, with a pilling density and coverage much higher than Example 1, indicating that the fiber ratio has an important influence on the surface performance of the fabric. Ultrasonic treatment improves the internal structure and interfacial bonding of the fiber through cavitation effect, further enhancing the overall durability of the fabric.

[0106] The reasonable ratio of terpolymer elastic fiber and modified bamboo fiber and the design of the reserved length of elastic fiber enable the fabric to maintain a stable structure during repeated deformation and washing. The phase change material microcapsules and modified titanium dioxide nanoparticles introduced in the functional additive treatment stage can maintain high functionality after multiple washes through firm bonding with the fiber surface. The comprehensive durability index of Example 1 is as high as 91.3, much higher than each comparative example, especially Comparative Example 4 (68.7) and Comparative Example 2 (72.1), achieving the unity of high durability and high functionality of the fabric.

[0107] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A multi-thread elastic knitted fabric, characterized by, The knitted fabric comprises the following components by weight: ternary copolymerized elastic fiber: 30 parts; modified bamboo fiber: 70 parts; The ternary copolymerized elastic fiber is made of the following raw material components by weight: poly-lactic acid: 28-32 parts; polypropylene terephthalate: 38-42 parts; polybutylene succinate: 28-32 parts; graphene nanosheet: 1-3 parts; epoxidized soybean oil: 0.5-1.5 parts; β-cyclodextrin: 2-4 parts; The modified bamboo fiber is treated by enzyme method, silane coupling agent modification, dopamine coating treatment and ultrasonic treatment.

2. A multi-thread elastic knit fabric according to claim 1, wherein, The ternary copolymerized elastic fiber further comprises 0.2-0.5 parts of antioxidant and 0.3-0.6 parts of nucleating agent.

3. A multi-thread elastic knit fabric according to claim 1, wherein, The surface of the ternary copolymerized elastic fiber contains 0.3-0.7 parts of phase change material microcapsules; and the surface of the modified bamboo fiber contains 0.5-1.0 parts of modified titanium dioxide nanoparticles.

4. A multi-thread elastic knit fabric according to claim 1, wherein, The fabric has a micro-graduated structure, the hardness of the fiber cross-section gradually decreases from inside to outside, forming an elastic gradient; and / or the fabric has an asymmetric interweaving structure, the difference in elastic modulus between the front and back of the fabric is controlled within 15-25%; and / or the fabric has a stress response structure, the microstructure rearranges when stretched.

5. A method of making a multi-thread elastic knitted fabric, characterized by, A multi-thread elastic knitted fabric according to any one of claims 1-4, comprising the following steps: S1, preparing ternary copolymerized elastic fiber: drying poly-lactic acid, polypropylene terephthalate and polybutylene succinate, then mixing with graphene nanosheet, epoxidized soybean oil, β-cyclodextrin, antioxidant and nucleating agent, and treating by spinning and pre-stretching to obtain ternary copolymerized elastic fiber; S2, preparing modified bamboo fiber: sequentially treating modified bamboo fiber by enzyme method, silane coupling agent modification, dopamine coating treatment and ultrasonic treatment; S3, functional additive treatment: treating ternary copolymerized elastic fiber with phase change material microcapsules and treating modified bamboo fiber with titanium dioxide nanoparticles; S4, weaving: mixing treated ternary copolymerized elastic fiber and modified bamboo fiber, and weaving, wherein the thread length of ternary copolymerized elastic fiber is 15-20% longer than that of modified bamboo fiber; S5, post-finishing: sequentially performing pre-setting treatment, biological enzyme dyeing and finished product setting.

6. A method of making a multi-thread elastic knitted fabric according to claim 5, characterized in that, The preparation of ternary copolymerized elastic fiber comprises the following steps: vacuum drying poly-lactic acid, polypropylene terephthalate and polybutylene succinate at 80-90℃ for 8-12 hours, and controlling the water content within 0.005-0.01%; melting and copolymerizing the dried raw materials with graphene nanosheet, epoxidized soybean oil and β-cyclodextrin, antioxidant and nucleating agent, and extruding in a twin-screw extruder, setting the temperature gradient of the extruder as follows: first zone 180-185℃, second zone 185-190℃, third zone 190-195℃, fourth zone 185-190℃, die 180-185℃, screw rotation speed 80-100rpm, vacuum degree 0.08-0.10MPa; cutting the extrudate into 2-3mm in size after water bath cooling, and vacuum drying at 100-110℃ for 12-16 hours; The dried granules are melt-spun at a melt temperature of 185-195°C, a spinneret aperture of 0.2-0.3mm, a number of apertures of 24-36, a shear rate of 1000-1500s -1 , and a spinning speed of 1200-1500m / min. The spun fiber is pre-stretched, first stretched by 10-15% at 50-60°C, then further stretched by 10-15% at 60-70°C, then relaxed at 80-90°C for 10-15 minutes, and the shrinkage is controlled at 5-8%.

7. A method of making a multi-thread elastic knitted fabric according to claim 6, characterized in that, The preparation of the modified bamboo fiber comprises the following steps: The bamboo fiber is soaked in a 1-2 g / L non-ionic surfactant solution at a liquid ratio of 1:20 and a temperature of 40-50°C for 30-40 minutes, and then washed with soft water for 3-5 times until neutral; Enzymatic treatment: a cellulase solution of 1-2 g / L is prepared, 0.2-0.4 g / L buffer salt is added, and the pH value is adjusted to 6.8-7.2, the bamboo fiber is soaked in the enzyme solution at a liquid ratio of 1:20 and a temperature of 45-50°C for 2-4 hours, and then washed with 60-70°C soft water for 3-5 times, and 0.1-0.3 g / L enzyme inhibitor is added to terminate the reaction; Silane coupling agent modification: a 2-4 part KH-550 aqueous solution is prepared, the pH value is adjusted to 4.0-5.0, and the solution is hydrolyzed at room temperature for 30-60 minutes, the enzyme-treated bamboo fiber is immersed in the solution at a liquid ratio of 1:15 and a temperature of 60-65°C for 1-2 hours, and then washed with deionized water for 2-3 times and dried at 80-90°C for 2-3 hours; Dopamine coating treatment: a 0.8-1.2 part dopamine hydrochloride solution is prepared, 2-4 g / L Tris buffer is added, and the pH value is adjusted to 8.0-8.5, the silanized bamboo fiber is immersed in the solution at a liquid ratio of 1:20 and treated at room temperature for 3-5 hours, 0.05-0.10 g / L ammonium persulfate is added as an initiator, and then washed with deionized water until neutral; Ultrasonic treatment: the dopamine-treated bamboo fiber is placed in an ultrasonic treatment device, the power is 300-500 W, the frequency is 20-25 kHz, the treatment time is 30-60 minutes, the treatment is paused for 1-2 minutes every 10 minutes, the temperature is controlled at 25-30°C, and then dried at 60-70°C for 3-4 hours.

8. A method of making a multi-thread elastic knitted fabric according to claim 7, characterized in that, The functional additive treatment comprises the following steps: Phase change material microcapsule treatment: a 0.3-0.7 part phase change material microcapsule dispersion liquid is prepared, 0.1-0.2 parts dispersant and 0.2-0.4 parts crosslinking agent are added, ultrasonic dispersion is performed for 10-15 minutes at a power of 200-300 W, the terpolymer elastic fiber is immersed in the dispersion liquid at a liquid ratio of 1:15 and a temperature of 40-45°C for 30-40 minutes, 0.3-0.6 parts fixing agent is added, dried at 50-60°C for 1-2 hours at a relative humidity of 40-50%, and then heat-set at 120-130°C for 10-15 minutes; Titanium dioxide nanoparticles treatment: 0.5-1.0 parts of modified titanium dioxide nanoparticles dispersion liquid is prepared, 0.2-0.3 parts of coupling agent, 0.1-0.2 parts of dispersing agent are added, ultrasonic dispersion is carried out for 15-20 minutes, power is 250-350 W, the modified bamboo fiber is immersed in the dispersion liquid, liquid ratio is 1:15, temperature is 45-50℃, treatment is carried out for 40-50 minutes, pH value is 6.5-7.5, deionized water is used for washing 1-2 times, drying is carried out at 60-70℃ for 2-3 hours, and then heat setting is carried out at 130-140℃ for 5-10 minutes.

9. A method of making a multi-thread elastic knitted fabric according to claim 8, characterized in that, The specific steps of weaving in step S4 are as follows: Yarn preparation: ternary copolymer elastic fiber is mixed with modified bamboo fiber, the length of the ternary copolymer elastic fiber is 15-20% longer than that of the modified bamboo fiber, the single yarn twist is 300-400 T / m, the S direction twist is twisted, the strand twist is 200-300 T / m, the Z direction twist is twisted, the yarn humidity is adjusted to 6-8%, the temperature is 20-25℃, and the humidity adjusting time is 24-48 hours; Yarn sizing: the sizing formula is polyvinyl alcohol 5-8 parts, acrylate 1-2 parts, wax emulsion 0.5-1.0 parts, and water 90-94 parts, the sizing liquid concentration is 6-8%, the sizing liquid temperature is 80-90℃, and the sizing rate is 8-12%; Warping: the warping speed is 400-500 m / min, the warping tension is 15-20% of the yarn breaking strength, and the beam density is 350-400 roots / 10 cm; Weaving: high-speed electronic jacquard circular machine is used for implementation of weaving, the weaving machine speed is 400-500 rpm, the warp tension is 25-30% of the fiber breaking strength, the weft tension is 20-25%, variable frequency tension control is implemented, the frequency is 0.5-1.0 Hz, and the amplitude is 45 GHz of the basic tension.

10. A method of making a multi-thread elastic knitted fabric according to claim 9, characterized in that, The specific steps of the post-finishing in step S5 are as follows: Pre-setting treatment: enzyme method desizing is carried out on the fabric, the enzyme concentration is 1-2 g / L, the temperature is 50-60℃, the time is 30-40 minutes, after washing, centrifugal dewatering is carried out to a water content of 40-50%, controllable microwave radiation technology is used for pre-setting, the frequency is 2.45 GHz, the radiation power is 400-600 W, the pre-setting temperature is 145-155℃, the treatment time is 90-120 seconds, the pre-setting machine frame width is 92-94% of the fabric blank width, 3-5 times of vacuum pulse is applied in the setting process, each time lasts for 10-15 seconds, the interval is 20-30 seconds, the residual pressure is 50-100 Pa, the cooling rate is 3-5℃ / min, cooling is carried out to 30-35℃, and relaxation treatment is carried out at room temperature for 4-6 hours, the relative humidity is 65-75%. Bio-enzyme dyeing: prepare dyeing solution, dye concentration is 2-4 parts of reactive dye, 1-2 parts of disperse dye, add 0.5-1.0 parts of bio-enzyme, 0.2-0.4 parts of enzyme stabilizer, 0.3-0.6 parts of buffer salt, add 2-4 parts of glycerol as biocompatible auxiliary agent, adjust pH value to 5.0-6.0, dyeing temperature is 85-90℃, dyeing time is 30-45 minutes, liquor ratio is 1:15, combine with supercritical CO2 dyeing auxiliary technology, pressure is 8-12 MPa, temperature is 80-90℃, treatment time is 20-30 minutes, wash to neutral, washing times is 3-5 times; Finished product setting: dehydration to moisture content of 40-50%, pre-drying to moisture content of 15-20%, temperature is 80-90℃, setting temperature is 130-140℃, treatment time is 60-90 seconds; Add 1-2 parts of chitosan-based softener, crosslinking agent 0.3-0.6 parts, emulsifier 0.2-0.4 parts, padding temperature is 25-30℃, pick-up rate is 70-80%, apply vacuum pulse for 2-3 times again, each time lasts for 8-12 seconds, interval is 15-20 seconds, residual pressure is 70-120 Pa, drying temperature is 100-110℃, time is 2-3 minutes, cool to room temperature, get finished product fabric.

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