PEF fiber knitted fabric and low-temperature dyeing process

Abstract

The invention relates to the technical field of fabrics, in particular to a PEF fiber knitted fabric and a low-temperature dyeing process, PEF fibers serve as a core layer, the core layer is coated with bio-based protein fibers to form a skin-core structure, and the surface of the fabric is of a microporous structure; the proportion of the PEF fibers in the skin-core structure is 60%-80%, and the proportion of the bio-based protein fibers in the skin-core structure is 20%-40%; the intrinsic viscosity of the PEF fiber is 0.8 to 1.0 dL / g; the pore diameter of the microporous structure is 1-5 microns, the porosity is larger than or equal to 15%, the microporous structure is prepared through a supercritical CO2 foaming process, the foaming pressure is 15-25 MPa, and the temperature is 60-70 DEG C; through cooperation of a skin-core structure, fiber modification, supercritical CO2 foaming and a low-temperature dyeing process, a microcosmic interface, a structural form and process control are comprehensively optimized, so that the PEF fiber knitted fabric has environmental friendliness, high air permeability, high mechanical strength and excellent dyeing performance at the same time, the technical problems of an existing PEF fabric are effectively solved, and the PEF fiber knitted fabric is worthy of popularization and application. The market demand of the current green clothing fabric is met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fabrics, in particular to a PEF fiber knitted fabric and a low-temperature dyeing process. BACKGROUND

[0002] With the improvement of global environmental awareness, the application of bio-based polymer materials in the textile field has become a research hotspot. Among them, polyethylene furandicarboxylate (PEF) fiber, which is derived from renewable resources (such as furandicarboxylic acid prepared by fermentation of plant straw), has good biodegradability and mechanical properties, and gradually replaces traditional petroleum-based fibers (such as PET) for knitted fabric production. However, PEF fiber still faces some problems in practical application, which restricts its industrialization process.

[0003] Firstly, PEF fiber has a high crystallinity (about 40%-50%), and the pure PEF knitted fabric has a tight fiber arrangement and lacks effective ventilation channels, with a general air permeability of less than 10 L / m 2 ·s, which is difficult to meet the core demand of comfortable air permeability of clothing fabric. Secondly, the heat distortion temperature of PEF fiber is only 70-75℃, while the traditional dyeing process in the textile industry usually uses high temperature conditions of 80-100℃. High temperature not only easily leads to thermal shrinkage of PEF fiber (shrinkage rate can reach 5%-8%), which destroys the dimensional stability of the fabric, but also damages the internal crystal structure of the fiber, resulting in a 15%-20% decrease in the breaking strength of the fabric.

[0004] Furthermore, in order to improve the performance of pure PEF fabric, the industry often tries to composite it with other fibers, but the interface compatibility between PEF molecular chain and conventional natural fibers (such as cotton and unmodified silk fibroin fiber) is poor, and the composite fabric is prone to fiber delamination and peeling, and the mechanical strength is difficult to meet the use standard of clothing fabric (the breaking strength in the warp direction should be ≥400N).

[0005] In summary, solving the problems of poor air permeability of PEF fiber fabric, easy deformation of high-temperature dyeing, weak interface bonding of fiber composite, and foaming / dyeing process has become a problem that needs to be solved in the current PEF fiber knitted fabric industrialization. SUMMARY

[0006] The present application relates to the technical field of fabrics, in particular to a PEF fiber knitted fabric and a low-temperature dyeing process.

[0007] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0008] A PEF fiber knitted fabric, comprising a core layer of PEF fiber and an outer layer of bio-based protein fiber forming a core-sheath structure, with a microporous structure on the fabric surface; the proportion of PEF fiber in the core-sheath structure is 60%-80%, and the proportion of bio-based protein fiber is 20%-40%; the intrinsic viscosity of the PEF fiber is 0.8-1.0 dL / g; the pore size of the microporous structure is 1-5 μm, the porosity is ≥15%, and the microporous structure is prepared by supercritical CO2 foaming process at a foaming pressure of 15-25 MPa and a temperature of 60-70℃; the heat distortion temperature of the PEF fiber is 70-75℃, and the foaming temperature is 5-8℃ lower than the heat distortion temperature of the PEF fiber.

[0009] As a further technical solution: the bio-based protein fiber is a silk fibroin fiber modified by γ-ray irradiation, with an irradiation dose of 6-10 kGy.

[0010] As a further technical solution: In the supercritical CO2 foaming process, the CO2 flow rate is 2-5 L / min, the foaming and heat preservation time is 10-15 minutes, and after foaming, the pressure is naturally released to atmospheric pressure at a rate of 0.8-1 MPa / min.

[0011] As a further technical solution: the weight per square meter of the fabric is 120-180g / m². 2 .

[0012] The low-temperature dyeing process for PEF fiber knitted fabrics includes the following steps:

[0013] (1) Pretreatment: Soak the fabric in deionized water at 40-50℃ for 15-20 minutes, and add 0.3-0.5g / L of soybean lecithin derivative degreasing agent during soaking;

[0014] (2) Bio-based auxiliary dyeing: The temperature for bio-based auxiliary dyeing is 40-60℃ and the time is 30-40 minutes. The pH of the dyeing solution is adjusted to 4.5-5.5 with acetate-sodium acetate buffer. The dyeing bath ratio is 1:10-15. Bio-based auxiliary agents include tea polyphenol derivative dispersants and chitosan-based leveling agents.

[0015] (3) Microwave color fixation: Microwave color fixation uses microwave radiation with a frequency of 2.45 GHz, with a total processing time of 6-10 minutes. It adopts an intermittent radiation method, with each radiation lasting 2-3 minutes and an interval of 1-2 minutes, and a power of 300-500W.

[0016] (4) Reduction cleaning: Soak the fabric in a 0.5-1g / L sodium hydrosulfite solution at 30-40℃ for 8-12 minutes. After soaking, rinse with deionized water 2-3 times, each time for 5-8 minutes.

[0017] The sodium dithionite solution uses deionized water as a solvent and contains sodium dithionite as the main agent, sodium sulfite as the stabilizer, and sodium carbonate as the pH adjuster; wherein the concentration of sodium dithionite is 0.8-1 g / L, the concentration of sodium sulfite is 0.2-0.4 g / L, the concentration of sodium carbonate is 0.1-0.3 g / L, and the pH value of the sodium dithionite solution is controlled at 8-9.

[0018] As a further technical solution: the tea polyphenol derivative dispersant is obtained from tea waste through supercritical CO2 extraction, with an extraction pressure of 20-30 MPa, a temperature of 40-50℃, an extraction time of 2-3 hours, and an amount of tea polyphenol derivative dispersant of 1-2 g / L.

[0019] As a further technical solution, the chitosan-based leveling agent is prepared by the following method:

[0020] S1 Take chitosan with a molecular weight of 50,000-80,000 Da, add it to a 1%-2% dilute acetic acid solution, stir to dissolve until the chitosan solution has a mass concentration of 3%-5%, stir at a speed of 300-400 r / min, and dissolve at a temperature of 25-30℃.

[0021] S2. Add propylene oxide dropwise to the chitosan solution. The mass ratio of propylene oxide to chitosan is 1:2-3. The dropping rate is 1-2 mL / min. After adding the propylene oxide, raise the temperature to 60-70℃ and keep the temperature for 4-6 hours. During the reaction, maintain the pH of the solution at 4.0-4.5.

[0022] After the S3 reaction is completed, neutralize to pH 7.0-7.5 with a 5%-10% sodium hydroxide solution, let stand for 2-3 hours to precipitate, and then filter and collect the precipitate.

[0023] S4. Wash the precipitate with deionized water 3-4 times, with the amount of water used each time being 5-8 times the mass of the precipitate. After washing, vacuum dry at 60-70℃ for 8-10 hours with a vacuum degree of -0.08 to -0.09 MPa to obtain hydroxypropyl modified chitosan-based leveling agent.

[0024] The amount of chitosan-based leveling agent used is 0.8-1.5 g / L.

[0025] As a further technical solution: in the bio-based auxiliary dyeing step, the dye solution is heated at a rate of 1-2℃ / min, from room temperature to a dyeing temperature of 40-60℃.

[0026] As a further technical solution: after microwave color fixing, the fabric is first allowed to cool naturally to room temperature for 5-8 minutes, and then proceeds to the restoration and cleaning step.

[0027] As a further technical solution: the fabric after restoration and cleaning is dried with hot air at a temperature of 50-60℃ and a wind speed of 1-2m / s, and the moisture content of the fabric after drying is ≤8%.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] 1. This invention employs a core-sheath structure with PEF fiber as the core layer and γ-ray-modified bio-based protein fiber as the sheath layer, optimizing the bonding performance between fibers and the mechanical properties of the fabric at the microscopic level. The PEF core layer, with its high crystallinity, provides rigid support to the fabric, ensuring its basic mechanical strength. After irradiation with 6-10 kGy γ-rays, the molecular chains of the bio-based protein fiber (such as silk fibroin fiber) undergo moderate cross-linking, forming more active groups (such as hydroxyl and amino groups). These active groups can form hydrogen bonds with the ester groups on the surface of the PEF core layer, significantly increasing the interfacial bonding sites and reducing interfacial voids. This improved interfacial compatibility at the microscopic level directly solves the delamination problem when traditional PEF is combined with other fibers, resulting in a significant increase in the warp breaking strength compared to pure PEF fabrics. Simultaneously, the sheath layer of bio-based protein fiber also improves the brittleness of pure PEF fabrics, increasing the elongation at break to 15.5%-20.3%, giving the fabric better flexibility and meeting the stretching requirements of clothing fabrics during wear.

[0030] 2. The supercritical CO2 foaming process employed in this invention perfectly solves the problems of uneven pore size and easy fiber damage in traditional foaming processes through microscopic mass transfer and temperature control. Under high pressure of 15-25 MPa, CO2 in a supercritical state uniformly permeates into the gaps between the core-sheath structure fibers and the free volume between PEF molecular chains, forming stable bubble nuclei. The foaming temperature of 60-70℃ is strictly controlled 5-8℃ below the heat distortion temperature of PEF fibers (70-75℃), preventing thermal shrinkage or crystal structure damage due to high temperatures. Subsequently, a slow depressurization rate of 0.8-1 MPa / min ensures that the bubble nuclei grow uniformly into micropores of 1-5 μm, ultimately forming microscopic air-permeable channels with a porosity ≥15%. This uniform microporous structure not only increases the fabric's air permeability to 15.2-22.3 L / m², but also... 2 The breathability of PEF fabric is significantly improved compared to pure PEF fabric, solving the problem of poor breathability. Simultaneously, the microporous structure provides spatial channels for dye molecule diffusion during subsequent dyeing, laying the foundation for improved colorfastness. Furthermore, the supercritical CO2 foaming process leaves no chemical residue, and the CO2 is recyclable, meeting environmental protection requirements and avoiding fabric pollution problems caused by residues of traditional chemical foaming agents.

[0031] 3. The low-temperature dyeing process of the present invention completely solves the problems of high energy consumption, easy deformation of PEF fibers and low color fastness of traditional high-temperature dyeing through the microscopic synergy of each step. In the pretreatment stage, a mild temperature of 40-50℃ combined with a soybean lecithin derivative degreasing agent with an HLB value of 8-10 can efficiently remove oil stains from the fabric surface without damaging the PEF fibers. This is achieved through the adsorption of oil stains by the lipophilic groups of the degreasing agent and the dissolution promoted by the hydrophilic groups, thus clearing obstacles for subsequent dyeing. In the bio-based auxiliary dyeing stage, a low-temperature environment of 40-60℃ is matched with the heat distortion temperature of PEF to avoid fiber heat deformation. At the same time, the tea polyphenol derivative dispersant can reduce the aggregation degree between dye molecules and promote the diffusion of dye into the fiber micropores. The hydroxypropyl modified chitosan-based leveling agent, with its enhanced adsorption, ensures that the dye is evenly dispersed on the fabric surface, avoiding color unevenness. In the microwave fixing stage, intermittent radiation of 2.45GHz can ensure that the fabric is heated evenly. The microwave energy can also promote the chemical bonding between dye molecules and the hydroxyl and amino groups on the fiber surface. Furthermore, the power design adjusted according to the porosity can avoid local overheating that could damage the microporous structure. Detailed Implementation

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0033] This invention provides a PEF fiber knitted fabric and its low-temperature dyeing process, aiming to solve the problems of poor air permeability, high dyeing energy consumption, low color fastness, and insufficient fiber interfacial bonding of traditional synthetic fiber fabrics.

[0034] The PEF fiber knitted fabric has PEF fiber as the core layer, with bio-based protein fibers wrapped around it to form a core-sheath structure, and the fabric surface has a microporous structure. The proportion of PEF fiber in the core-sheath structure is 60%-80%, and the proportion of bio-based protein fibers is 20%-40%. The intrinsic viscosity of the PEF fiber is 0.8-1.0 dL / g, and the heat distortion temperature is 70-75℃. The bio-based protein fiber is preferably silk fibroin fiber modified by γ-ray irradiation, with an irradiation dose of 6-10 kGy.

[0035] The microporous structure is prepared via a supercritical CO2 foaming process at a foaming pressure of 15-25 MPa and a temperature of 60-70°C, which is 5-8°C lower than the heat distortion temperature of PEF fibers. In the supercritical CO2 foaming process, the CO2 flow rate is 2-5 L / min, the foaming holding time is 10-15 minutes, and after foaming, the pressure is naturally released to atmospheric pressure at a rate of 0.8-1 MPa / min. The final microporous structure has a pore size of 1-5 μm and a porosity ≥15%. The fabric has a weight per square meter of 120-180 g / m². 2 .

[0036] The low-temperature staining process includes four steps: pretreatment, staining with bio-based auxiliaries, microwave fixation, and reduction cleaning, as detailed below:

[0037] Pretreatment: Soak the fabric in deionized water at 40-50℃ for 15-20 minutes, adding 0.3-0.5g / L of soybean lecithin derivative degreasing agent during soaking.

[0038] The preparation method of soybean phospholipid derivative oil remover is as follows: Soybean phospholipids and allyl glycidyl ether are mixed at a mass ratio of 50:1 and reacted at a constant temperature of 40°C for 2 hours; then formic acid and concentrated sulfuric acid are added to the reaction system as catalysts, and hydrogen peroxide is slowly added dropwise over 1 hour, controlling the mass ratio of soybean phospholipids, formic acid, concentrated sulfuric acid and hydrogen peroxide to be 100:5.4:0.5:25, and the reaction is carried out for 8 hours; the obtained product is reacted with sodium 3-chloro-2-hydroxypropanesulfonate at a mass ratio of 1:0. 5. Place the mixture in an aqueous phase, add an acid-binding agent and a phase transfer catalyst. The acid-binding agent is triethylamine, and its amount is 1.0 times the molar amount of sodium 3-chloro-2-hydroxypropanesulfonate. The phase transfer catalyst is tetrabutylammonium bromide, and its amount is 1.2% of the soybean phospholipid content. Reflux the reaction at 75°C for 4 hours, while controlling the pH of the reaction system between 8 and 10. After the reaction is completed, remove the solvent by vacuum distillation. Wash the obtained solid with ethanol and dry it under vacuum at 60°C to constant weight.

[0039] Bio-based auxiliaries for staining: The staining temperature is 40-60℃ and the time is 30-40 minutes. The pH of the staining solution is adjusted to 4.5-5.5 with acetate-sodium acetate buffer. The staining bath ratio is 1:10-15. The dyeing solution is heated at a rate of 1-2℃ / min from room temperature to the staining temperature. The bio-based auxiliaries include tea polyphenol derivative dispersants and chitosan-based leveling agents. The tea polyphenol derivative dispersants are obtained from tea waste through supercritical CO2 extraction, and the dosage is 1-2 g / L. The chitosan-based leveling agent needs to be prepared by hydroxypropyl modification, and the dosage is 0.8-1.5 g / L.

[0040] Tea waste refers to the tea stems and waste generated during the production of green tea.

[0041] The preparation method of tea polyphenol derivative dispersant is as follows: tea waste is cleaned, dried and crushed; under the conditions of extraction pressure of 20-30MPa and temperature of 40-50℃, the tea waste is extracted with supercritical CO2 as solvent for 2-3 hours to obtain the product.

[0042] Microwave color fixing: Microwave radiation at a frequency of 2.45GHz is used, with a total processing time of 6-10 minutes. Intermittent radiation is used, with each radiation session lasting 2-3 minutes and an interval of 1-2 minutes. The power is 300-500W. After microwave color fixing, the fabric is allowed to cool naturally to room temperature for 5-8 minutes before proceeding to the restoration cleaning step.

[0043] Reduction cleaning: Soak the fabric in a 0.5-1 g / L sodium dithionite solution at 30-40℃ for 8-12 minutes. After soaking, rinse 2-3 times with deionized water, each rinse lasting 5-8 minutes. The sodium dithionite solution uses deionized water as a solvent and contains the main agent sodium dithionite (concentration 0.8-1 g / L), the stabilizer sodium sulfite (concentration 0.2-0.4 g / L), and the pH adjuster sodium carbonate (concentration 0.1-0.3 g / L). The pH value of the sodium dithionite solution is controlled at 8-9. After reduction cleaning, the fabric is dried with hot air at a temperature of 50-60℃ and an air velocity of 1-2 m / s. The moisture content of the dried fabric is ≤8%.

[0044] The preparation method of the chitosan-based leveling agent is as follows:

[0045] S1 Take chitosan with a molecular weight of 50,000-80,000 Da, add it to a 1%-2% dilute acetic acid solution, and stir at 300-400 r / min at 25-30℃ to dissolve it, forming a chitosan solution with a mass concentration of 3%-5%.

[0046] S2. Add propylene oxide dropwise to the chitosan solution at a mass ratio of propylene oxide to chitosan of 1:2-3 and a dropping rate of 1-2 mL / min. After the addition is complete, raise the temperature to 60-70℃ and keep the reaction at this temperature for 4-6 hours. During the reaction, maintain the pH of the solution at 4.0-4.5.

[0047] After the S3 reaction is complete, neutralize to pH 7.0-7.5 with a 5%-10% sodium hydroxide solution, let stand for 2-3 hours to precipitate, and then filter and collect the precipitate.

[0048] S4 washes the precipitate 3-4 times with deionized water, each time using 5-8 times the mass of the precipitate; after washing, vacuum dry at 60-70℃ and a vacuum degree of -0.08 to -0.09 MPa for 8-10 hours to obtain hydroxypropyl modified chitosan-based leveling agent.

[0049] The following are specific examples:

[0050] Example 1: Preparation of core-sheath structured fibers:

[0051] PEF fibers with an intrinsic viscosity of 0.9 dL / g and a heat distortion temperature of 72℃ were selected as the core layer. Bio-based protein fibers were prepared by γ-ray irradiation modification of silk fibroin fibers (8 kGy). Bio-based protein fibers were coated onto the surface of the PEF fibers using a coating process, with a mass ratio of 70% PEF fibers and 30% bio-based protein fibers, forming a core-sheath structure fiber.

[0052] Knitted fabric weaving and supercritical CO2 foaming:

[0053] The core-sheath structure fiber is woven to a weight of 150g / m². 2 The knitted fabric was prepared using a supercritical CO2 foaming process to create a microporous structure on its surface: the foaming pressure was set at 20 MPa, the foaming temperature at 65℃ (7℃ lower than the heat distortion temperature of PEF fibers), the CO2 flow rate at 3.5 L / min, and the foaming holding time at 12 minutes; after foaming, the pressure was naturally released to atmospheric pressure at a rate of 0.9 MPa / min. The final microporous structure on the fabric surface had a pore size of 3 μm and a porosity of 18%.

[0054] Low-temperature dyeing process:

[0055] (1) Pretreatment: Soak the above knitted fabric in deionized water at 45°C for 18 minutes, and add soybean lecithin derivative degreasing agent with a concentration of 0.4g / L during the soaking process.

[0056] (2) Bio-based dyeing auxiliaries: First, a tea polyphenol derivative dispersant was prepared and extracted from tea waste by supercritical CO2 extraction (extraction pressure 25 MPa, temperature 45℃, extraction time 2.5 hours), with a dosage of 1.5 g / L; then, a chitosan-based leveling agent was prepared (chitosan molecular weight 60000 Da, dilute acetic acid concentration 1.5%, chitosan solution mass concentration 4%, stirring rate 350 r / min, dissolution temperature 28℃; propylene oxide to chitosan mass ratio 1:2.5, dropping rate 1.5 mL / min, reaction temperature 65℃, reaction time 5 hours, neutralization with sodium hydroxide solution concentration 8%, washing water volume 6 times the precipitate mass, drying temperature 65℃, vacuum degree -0.085 MPa, drying time 9 hours), with a dosage of 1.2 g / L. The pH of the staining solution was adjusted to 5.0 with acetate-sodium acetate buffer. The staining bath ratio was 1:12. The temperature was increased from room temperature to 50°C at a rate of 1.5°C / min, and the staining was maintained at 50°C for 35 minutes.

[0057] (3) Microwave color fixation: Microwave radiation at a frequency of 2.45 GHz and a power of 400 W was used. The total processing time was 8 minutes, using intermittent radiation: each radiation session lasted 2.5 minutes with a 1.5-minute interval. After microwave color fixation, the product was allowed to cool naturally to room temperature for 6 minutes.

[0058] (4) Reduction cleaning: Prepare a sodium hydrosulfite solution with sodium dithionite concentration of 0.9 g / L, sodium sulfite concentration of 0.3 g / L, sodium carbonate concentration of 0.2 g / L, and the remainder being water. The pH value of the solution is 8.5. Soak the fabric in the sodium hydrosulfite solution at 35°C for 10 minutes. After soaking, rinse twice with deionized water for 7 minutes each time.

[0059] (5) Drying: Hot air drying is used, with a drying temperature of 55℃ and a wind speed of 1.5m / s. The moisture content of the fabric after drying is 7%.

[0060] Example 2: Preparation of core-sheath structured fibers:

[0061] PEF fibers with an intrinsic viscosity of 0.8 dL / g and a heat distortion temperature of 70℃ were selected as the core layer. Bio-based protein fibers were prepared by γ-ray irradiation modification of silk fibroin fibers at an irradiation dose of 6 kGy. Following a mass ratio of 60% PEF fibers and 40% bio-based protein fibers, a coating process was used to coat the surface of the PEF fibers, forming a core-sheath structure fiber.

[0062] Knitted fabric weaving and supercritical CO2 foaming:

[0063] The core-sheath structure fiber is woven to a weight of 120g / m². 2 The knitted fabric was prepared using a supercritical CO2 foaming process to create a microporous structure on its surface: the foaming pressure was set at 15 MPa, the foaming temperature at 63℃ (7℃ lower than the heat distortion temperature of PEF fibers), the CO2 flow rate at 2 L / min, and the foaming holding time at 10 minutes; after foaming, the pressure was naturally released to atmospheric pressure at a rate of 0.8 MPa / min. The final microporous structure on the fabric surface had a pore size of 1 μm and a porosity of 15%.

[0064] Low-temperature dyeing process:

[0065] (1) Pretreatment: Soak the above knitted fabric in deionized water at 40°C for 15 minutes, and add soybean lecithin derivative degreasing agent with a concentration of 0.3g / L during the soaking process.

[0066] (2) Bio-based auxiliary staining: First, a tea polyphenol derivative dispersant was prepared and extracted from tea waste using supercritical CO2 (extraction pressure 20 MPa, temperature 40℃, extraction time 2 hours), with a dosage of 1 g / L. Then, a chitosan-based leveling agent was prepared (chitosan molecular weight 50000 Da, dilute acetic acid concentration 1%, chitosan solution mass concentration 3%, stirring speed 300 r / min, dissolution temperature 25℃; propylene oxide to chitosan mass ratio 1:2, dropping rate 1 mL / min, reaction temperature 60℃, reaction time 4 hours, neutralization using 5% sodium hydroxide solution, washing water volume 5 times the precipitate mass, drying temperature 60℃, vacuum degree -0.08 MPa, drying time 8 hours), with a dosage of 0.8 g / L. The staining solution was adjusted to pH 4.5 using an acetate-sodium acetate buffer solution, with a staining bath ratio of 1:10. The temperature was increased from room temperature to 40℃ at a rate of 1℃ / min, and the staining was maintained at 40℃ for 30 minutes.

[0067] (3) Microwave color fixation: Microwave radiation at a frequency of 2.45 GHz and a power of 300 W was used. The total processing time was 6 minutes, and intermittent radiation was used: each radiation session lasted 2 minutes, with a 1-minute interval. After microwave color fixation, the product was allowed to cool naturally to room temperature for 5 minutes.

[0068] (4) Reduction cleaning: Prepare a sodium hydrosulfite solution with sodium dithionite concentration of 0.8 g / L, sodium sulfite concentration of 0.2 g / L, sodium carbonate concentration of 0.1 g / L, and the remainder being water. The pH value of the solution is 8. Soak the fabric in the sodium hydrosulfite solution at 30°C for 8 minutes. After soaking, rinse twice with deionized water for 5 minutes each time.

[0069] (5) Drying: Hot air drying is used, with a drying temperature of 50℃ and a wind speed of 1m / s. The moisture content of the fabric after drying is 8%.

[0070] Example 3: Preparation of core-sheath structured fibers:

[0071] PEF fibers with an intrinsic viscosity of 1.0 dL / g and a heat distortion temperature of 75℃ were selected as the core layer. Bio-based protein fibers were prepared by γ-ray irradiation modification of silk fibroin fibers at an irradiation dose of 10 kGy. Following a mass ratio of 80% PEF fibers and 20% bio-based protein fibers, a coating process was used to coat the surface of the PEF fibers, forming a core-sheath structure fiber.

[0072] Knitted fabric weaving and supercritical CO2 foaming:

[0073] The core-sheath structure fiber is woven to a weight of 180g / m². 2The knitted fabric was prepared using a supercritical CO2 foaming process to create a microporous structure on its surface: the foaming pressure was set at 25 MPa, the foaming temperature at 68℃ (7℃ lower than the heat distortion temperature of PEF fibers), the CO2 flow rate at 5 L / min, and the foaming holding time at 15 minutes; after foaming, the pressure was naturally released to atmospheric pressure at a rate of 1 MPa / min. The final microporous structure on the fabric surface had a pore size of 5 μm and a porosity of 20%.

[0074] Low-temperature dyeing process:

[0075] (1) Pretreatment: Soak the above knitted fabric in deionized water at 50°C for 20 minutes, and add soybean lecithin derivative degreasing agent with a concentration of 0.5g / L during the soaking process.

[0076] (2) Bio-based auxiliary staining: First, a tea polyphenol derivative dispersant was prepared and extracted from tea waste using supercritical CO2 (extraction pressure 30 MPa, temperature 50℃, extraction time 3 hours), with a dosage of 2 g / L. Then, a chitosan-based leveling agent was prepared (chitosan molecular weight 80000 Da, dilute acetic acid concentration 2%, chitosan solution mass concentration 5%, stirring rate 400 r / min, dissolution temperature 30℃; propylene oxide to chitosan mass ratio 1:3, dropping rate 2 mL / min, reaction temperature 70℃, reaction time 6 hours, neutralization using sodium hydroxide solution concentration 10%, washing water volume 8 times the precipitate mass, drying temperature 70℃, vacuum degree -0.09 MPa, drying time 10 hours), with a dosage of 1.5 g / L. The staining solution was adjusted to pH 5.5 using an acetate-sodium acetate buffer solution, with a staining bath ratio of 1:15. The temperature was increased from room temperature to 60℃ at a rate of 2℃ / min, and the staining was maintained at 60℃ for 40 minutes.

[0077] (3) Microwave color fixation: Microwave radiation at a frequency of 2.45 GHz and a power of 500 W was used. The total processing time was 10 minutes, and intermittent radiation was used: each radiation session lasted 3 minutes, with a 2-minute interval. After microwave color fixation, the product was allowed to cool naturally to room temperature for 8 minutes.

[0078] (4) Reduction cleaning: Prepare a sodium hydrosulfite solution with a sodium dithionite concentration of 1 g / L, a sodium sulfite concentration of 0.4 g / L, a sodium carbonate concentration of 0.3 g / L, and the remainder being water. The pH value of the solution is 9. Soak the fabric in the sodium hydrosulfite solution at 40℃ for 12 minutes. After soaking, rinse three times with deionized water for 8 minutes each time.

[0079] (5) Drying: Hot air drying is used, with a drying temperature of 60℃ and a wind speed of 2m / s. The moisture content of the fabric after drying is 6%.

[0080] Comparative Example 1:

[0081] The fiber and fabric preparation uses only PEF fibers with an intrinsic viscosity of 0.9 dL / g and a heat distortion temperature of 72℃, without coating with bio-based protein fibers, and is directly woven into 150 g / m² fabric. 2 Knitted fabric.

[0082] The supercritical CO2 foaming parameters were consistent with those of Example 1: pressure 20 MPa, temperature 65 °C, CO2 flow rate 3.5 L / min, holding time 12 minutes, and pressure relief 0.9 MPa / min. The final microporous pore size was 3 μm, and the porosity was 12%.

[0083] The low-temperature staining process is completely consistent with that in Example 1.

[0084] Comparative Example 2:

[0085] The parameters for preparing PEF fibers (0.9 dL / g, 72℃) for the core-sheath structure fibers were consistent with those in Example 1. The silk fibroin fibers were not modified by γ-ray irradiation and were prepared at a mass ratio of 70%:30%.

[0086] The fabric weaving and foaming are the same as in Example 1 (150g / m²). 2 (With the same foaming parameters), the microporous pore size is 3μm and the porosity is 16%.

[0087] The low-temperature staining process is completely consistent with that in Example 1.

[0088] Comparative Example 3:

[0089] The preparation of the core-sheath structure fiber was exactly the same as in Example 1.

[0090] Fabric weaving and traditional foam weaving result in 150g / m² 2 After fabrication, a high-pressure air foaming process is used: pressure 10MPa, temperature 75℃ (exceeding the heat distortion temperature of PEF 72℃), heat preservation for 12 minutes, and pressure release rate 0.5MPa / min. The final fabric has a pore size of 8μm (non-uniform) and a porosity of 10%.

[0091] The low-temperature staining process is completely consistent with that in Example 1.

[0092] Comparative Example 4:

[0093] The preparation and foaming of the core-sheath structure fiber were completely consistent with those in Example 1 (core-sheath structure, supercritical foaming, pore size 3 μm, porosity 18%).

[0094] The low-temperature dyeing process (only the color fixing step is different) pretreatment and bio-based auxiliary dyeing steps are the same as in Example 1; step (3) microwave color fixing step is changed to conventional high-temperature color fixing: keep warm in an 80℃ hot water bath for 20 minutes, and directly enter the reduction cleaning without cooling; the reduction cleaning and drying steps are the same as in Example 1.

[0095] Comparative Example 5:

[0096] The preparation and foaming of the core-sheath structure fiber were completely consistent with those in Example 1 (core-sheath structure, supercritical foaming, pore size 3 μm, porosity 18%).

[0097] In the low-temperature staining process, the bio-based auxiliary staining step does not use polyphenol derivative dispersants, and the remaining steps are the same as in Example 1.

[0098] test:

[0099] Experiment 1: Fabric breathability test

[0100] According to GB / T5453-2012, tests were conducted under standard environmental conditions (temperature 23℃±2℃, relative humidity 50%±5%). Five different locations were randomly selected from each sample (Examples 1-3, Comparative Examples 1-5), with each location having a cut area of ​​20 cm². 2 The test samples were tested with a pressure difference of 100 Pa, and the air permeability of each sample was measured (unit: L / m³). 2 The average value of the five samples was calculated as the final air permeability data, and the results are as follows: Table 1

[0101]

[0102]

[0103] As shown in Table 1, the air permeability of Examples 1-3 is significantly higher than that of Comparative Examples 1-4. The core-sheath structure of Examples 1-3 creates uniform gaps between fibers. Combined with the microporous structure with pore size of 1-5 μm and porosity of ≥15% prepared by supercritical CO2 foaming, it constructs unobstructed and uniform air permeability channels, resulting in high air permeability. Comparative Example 1 lacks the core-sheath structure covered by bio-based protein fibers. The tightly packed PEF fibers result in a dense fabric with a porosity of only 12%, reducing air permeability channels and resulting in an air permeability of only 8.3 L / m²·s. The bio-based protein fibers of Comparative Example 2 have not been modified by γ-ray irradiation. Poor inter-fiber bonding and partial blockage of micropores by loose fibers reduced the porosity to 16%. Comparative Example 3 used traditional physical foaming, but the foaming temperature exceeded the heat distortion temperature of PEF fibers (75℃>72℃), causing fiber shrinkage, uneven pore size, and a porosity of only 10%. The air permeability channels were disordered and narrow, resulting in the lowest air permeability. The high-temperature color fixing (80℃) of Comparative Example 4 caused slight shrinkage of the fabric, reducing the porosity from 18% to 15%, which verified the importance of low-temperature microwave color fixing in maintaining the porous structure of the fabric. The bio-based auxiliary dyeing step of Comparative Example 5, which did not use polyphenol derivative dispersants, slightly reduced the air permeability.

[0104] Test 2: Color fastness test of fabric; "Tests for color fastness of textiles: color fastness to washing with soap", using method A(1), washing with standard soap solution (5g / L) for 30 minutes at 40℃±2℃, and evaluating the color change grade of the sample and the staining grade of the lining fabric after washing (grades 1-5, grade 5 is the best).

[0105] Colorfastness to perspiration: Referring to GB / T3922-2013, two test solutions were used: acidic perspiration (pH 5.5) and alkaline perspiration (pH 8.0). After the sample was bonded to the lining fabric, it was immersed in the test solution for 30 minutes, subjected to a pressure of 12.5 kPa, and placed at 37℃±2℃ for 4 hours. The color change and staining grades were evaluated, and the results are as follows:

[0106] Table 2

[0107]

[0108]

[0109] As shown in Table 2, the color fastness (wash fastness and perspiration fastness) of Examples 1-3 is superior to that of the comparative example. The core-sheath structure (PEF and modified bio-based fiber) of Examples 1-3 enhances the fiber's ability to adsorb dyes, and γ-ray irradiation modification strengthens the binding force between the bio-based fiber and the dye. Simultaneously, low-temperature dyeing avoids dye decomposition, and microwave fixing (intermittent radiation) promotes uniform dye fixation, resulting in a color fastness grade of 3.5-4.5. Comparative Example 1 lacks a core-sheath structure; when the PEF fiber exists alone, the dye adsorption is low, and the smooth fiber surface makes the dye easily detached, resulting in wash fastness and perspiration fastness grades of only 2.5-3. The bio-based fiber in Comparative Example 2 was not irradiated, its structure was not modified, and its binding force with the dye was weak, leading to a decrease in color fastness compared to Example 1, thus verifying the necessity of γ-ray irradiation modification. Comparative Example 3, due to the uneven pore size caused by traditional foaming, resulted in uneven dye distribution in the fabric, with dye accumulation and easy detachment in some areas, leading to a decrease in color fastness compared to Example 1. This demonstrates the impact of supercritical CO2 foaming (uniform pore size) on dyeing uniformity. Comparative Example 4, with its high-temperature fixing (80°C), caused fabric fiber shrinkage, squeezing out some of the adsorbed dye. Furthermore, the high temperature disrupted the bond between the dye and fiber, resulting in color fastness comparable to Comparative Example 1. This demonstrates the importance of low-temperature microwave fixing for maintaining color fastness. Comparative Example 5, with its bio-based auxiliary dyeing step, did not use polyphenol derivative dispersants, leading to a comprehensive decrease in the fabric's color fastness.

[0110] Experiment 3: Fabric tensile properties test;

[0111] According to GB / T3923.1-2013, the test was conducted under standard environmental conditions (temperature 23℃±2℃, relative humidity 50%±5%). Five warp and five weft strips (200mm×50mm) were cut from each specimen. The tensile speed was set to 100mm / min. The breaking strength (unit: N) and elongation at break (unit: %) of each strip were measured. The average values ​​for the warp and weft directions were calculated as the final data. The results are as follows:

[0112] Table 3

[0113]

[0114]

[0115] As shown in Table 3, the tensile properties (breaking strength and elongation at break) of Examples 1-3 are significantly better than those of the comparative example, thanks to the synergistic effect of the core-sheath structure and fiber modification: the core-sheath structure of Examples 1-3 (PEF provides rigidity to the core layer, and modified bio-based fibers provide toughness to the sheath layer) forms a rigid-flexible structure. γ-ray irradiation modification enhances the degree of cross-linking of the molecular chains of the bio-based fibers, improving the bonding force between fibers; at the same time, supercritical CO2 foaming does not destroy the fiber structure, so the breaking strength reaches 398-489N, and the elongation at break reaches 15.5%-20.3%. Comparative Example 1 has no core-sheath structure, only PEF fibers are woven alone, the bonding force between fibers is weak, and the PEF fibers are relatively brittle, with a breaking strength of only 308-325N and an elongation at break of only 11.5%-12.3%, verifying the role of the core-sheath structure in improving mechanical properties. Comparative Example 2's bio-based fiber was unirradiated, resulting in low cross-linking of the fiber molecular chains, insufficient toughness, and poor interfacial bonding with PEF fibers. Its breaking strength and elongation at break were lower than in Example 1, highlighting the necessity of γ-ray irradiation modification. Comparative Example 3 used traditional physical foaming, with a foaming temperature exceeding the heat distortion temperature of PEF, leading to fiber structural damage (partial fiber breakage). Although the core-sheath structure remained, the fiber's inherent strength decreased, and its breaking strength was lower than in Example 1, demonstrating the importance of supercritical CO2 foaming (low temperature, uniform pressure) for fiber structure protection. Comparative Example 4's high-temperature color fixing caused slight fiber shrinkage and a tighter fiber arrangement, resulting in a breaking strength close to that of Example 2. However, the high temperature slightly reduced fiber toughness, and the elongation at break was lower than in Example 1, further verifying the protective effect of low-temperature processes on fiber performance. Comparative Example 5's bio-based auxiliary dyeing step did not use polyphenol derivative dispersants, thus having little impact on the fabric's tensile properties.

[0116] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0117] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A PEF fiber knitted fabric, characterized by: The PEF fiber is taken as a core layer, and a biobased protein fiber is coated outside the core layer to form a skin-core structure, and the surface of the fabric has a microporous structure; the proportion of the PEF fiber in the skin-core structure is 60%-80%, and the proportion of the biobased protein fiber is 20%-40%; the intrinsic viscosity of the PEF fiber is 0.8-1.0 dL / g; the microporous structure has a pore size of 1-5 μm and a porosity of ≥15%, and the microporous structure is prepared by a supercritical CO2 foaming process with a foaming pressure of 15-25 MPa and a temperature of 60-70℃; the heat distortion temperature of the PEF fiber is 70-75℃, and the foaming temperature is 5-8℃ lower than the heat distortion temperature of the PEF fiber.

2. The PEF fiber knit fabric according to claim 1, characterized in that: The biobased protein fiber is a silk fibroin fiber modified by γ-ray irradiation, and the irradiation dose is 6-10 kGy.

3. The PEF fiber knit fabric of claim 1, wherein: In the supercritical CO2 foaming process, the flow rate of CO2 is 2-5 L / min, the foaming and heat preservation time is 10-15 minutes, and after foaming, the pressure is naturally released to normal pressure at a pressure release rate of 0.8-1 MPa / min.

4. The PEF fiber knit fabric of claim 1, wherein: The fabric has a weight per square meter of 120-180 g / m 2 .

5. A low temperature dyeing process of PEF fibre knitted fabric as claimed in any one of claims 1 to 4, wherein, The method comprises the following steps: (1) Pretreatment: the fabric is soaked in deionized water at 40-50℃ for 15-20 minutes, and 0.3-0.5 g / L of soybean phospholipid derivative oil removal agent is added during soaking; (2) Biobased auxiliary agent dyeing: the temperature of biobased auxiliary agent dyeing is 40-60℃, and the time is 30-40 minutes; the dyeing solution is adjusted to pH 4.5-5.5 with acetic acid-sodium acetate buffer solution, and the dyeing bath ratio is 1:10-15; the biobased auxiliary agent includes tea polyphenol derivative diffusing agent and chitosan-based leveling agent; (3) Microwave fixation: microwave fixation adopts microwave radiation with a frequency of 2.45 GHz, and the total processing time is 6-10 minutes; the intermittent radiation mode is adopted, each radiation time is 2-3 minutes, the interval is 1-2 minutes, and the power is 300-500 W; (4) Reduction cleaning: the fabric is soaked in 0.5-1 g / L of sodium hydrosulfite solution at 30-40℃ for 8-12 minutes, and then rinsed with deionized water for 2-3 times, each time for 5-8 minutes; The sodium hydrosulfite solution takes deionized water as a solvent, and contains main agent sodium hydrosulfite, stabilizer sodium sulfite and pH adjuster sodium carbonate; wherein the concentration of sodium hydrosulfite is 0.8-1 g / L, the concentration of sodium sulfite is 0.2-0.4 g / L, and the concentration of sodium carbonate is 0.1-0.3 g / L; and the pH value of the sodium hydrosulfite solution is controlled to be 8-9.

6. The low temperature dyeing process according to claim 5, characterized in that: The tea polyphenol derivative diffusing agent is obtained by supercritical CO2 extraction from tea waste, with an extraction pressure of 20-30 MPa, an extraction temperature of 40-50℃, and an extraction time of 2-3 hours; and the amount of the tea polyphenol derivative diffusing agent is 1-2 g / L.

7. The low temperature dyeing process according to claim 5, characterized in that: The chitosan-based leveling agent is prepared by the following method: S1: take chitosan with a molecular weight of 50000-80000 Da, add 1%-2% dilute acetic acid solution, stir and dissolve to obtain a chitosan solution with a mass concentration of 3%-5%, the stirring rate is 300-400 r / min, and the dissolution temperature is 25-30℃; S2 drop propylene oxide into the chitosan solution, the mass ratio of propylene oxide to chitosan is 1:2-3, the drop rate is 1-2 mL / min, after dropping, the temperature is raised to 60-70℃, and the reaction is kept for 4-6 hours, and the pH of the solution is maintained at 4.0-4.5 during the reaction; S3 after the reaction, neutralize to pH 7.0-7.5 with 5%-10% sodium hydroxide solution, stand for 2-3 hours, collect the precipitate by filtration; S4 wash the precipitate with deionized water for 3-4 times, the amount of water used for each washing is 5-8 times the mass of the precipitate, after washing, dry at 60-70℃ under vacuum for 8-10 hours, the vacuum degree is-0.08 to-0.09 MPa, to obtain the hydroxypropyl modified chitosan-based leveling agent; The dosage of the chitosan-based leveling agent is 0.8-1.5 g / L.

8. The low temperature dyeing process according to claim 5, characterized in that: In the biological-based auxiliary dyeing step, the heating rate of the dyeing solution is 1-2℃ / min, and the dyeing temperature is raised from room temperature to 40-60℃.

9. The low temperature dyeing process according to claim 5, characterized in that: After the microwave fixation, the fabric is naturally cooled to room temperature, the cooling time is 5-8 minutes, and then enters the reduction cleaning step.

10. The low temperature dyeing process according to claim 5, characterized in that: After the reduction cleaning, the fabric is dried by hot air, the drying temperature is 50-60℃, the air speed is 1-2 m / s, and the water content of the fabric after drying is ≤8%.

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