Bio-based ecological fiber fabric and preparation method thereof

Abstract

The invention discloses a bio-based ecological fiber fabric and a preparation method thereof, and relates to the technical field of ecological fiber fabrics, the bio-based ecological fiber fabric comprises a fiber base material and a bio-modified layer attached to the surface of the fiber base material through chemical bonding; the fiber base material is formed by blending soybean protein composite fibers and polylactic acid fibers, the soybean protein composite fibers are blended spinning fibers of soybean protein and polyvinyl alcohol, and the biological modification layer is formed by carrying out in-situ cross-linking reaction on arginine grafted oxidized sodium alginate and phytic acid on the surface of the fiber base material; the arginine grafted oxidized sodium alginate has an amphiphilic structure. The stable biological modification layer is constructed through chemical bonding, durable and washable antibacterial and antistatic performance is achieved, the nanogel structure on the surface endows the fabric with soft and smooth touch feeling and effectively inhibits static electricity, the compact cross-linked network structure guarantees the continuity of the film layer, and the overall stability and wearing comfort of the fabric are improved.

Description

Technical Field

[0001] This invention relates to the field of eco-fiber fabric technology, specifically to a bio-based eco-fiber fabric and its preparation method. Background Technology

[0002] Bio-based textiles often achieve a balance between comfort and mechanical properties by blending protein fibers with synthetic polymer fibers. However, endowing them with lasting functionality still faces many challenges. Existing functional finishing technologies mostly rely on physical adsorption or simple encapsulation processes to attach antibacterial or antistatic agents to the fabric surface. In actual use, due to the lack of strong adhesion, the attached active ingredients are easily detached under the mechanical friction and water shearing action during washing. This causes the antibacterial and antistatic functions of the fabric to rapidly decline with increasing use, failing to meet the needs of long-term use.

[0003] To compensate for the defects of weak physical adhesion, existing technologies often extend the functional life by increasing the coating thickness or using inorganic particulate additives. This not only clogs the micropores on the fiber surface but also increases the roughness of the fiber surface, resulting in a stiff and rough feel to the fabric. This damages the original soft and skin-friendly properties of protein fibers. Furthermore, synthetic fiber components such as polylactic acid are prone to accumulating static electricity, and conventional physical coatings are difficult to form a continuous and effective conductive path. This leads to static electricity adsorption when worn in dry environments, affecting wearing comfort.

[0004] In terms of preparation process, conventional drying and curing processes usually use direct high-temperature heating. This rapid heat treatment causes the solvent in the finishing solution to vaporize instantly on the surface, which can easily generate tiny pores or cracks in the formed film, destroying the continuity and density of the protective layer. This structural defect not only weakens the protective effect of the film on the fiber body, but also further accelerates the peeling and loss of functional components during subsequent use, making it difficult to prepare high-quality fabrics with uniform and stable performance. Summary of the Invention

[0005] The purpose of this invention is to provide a bio-based eco-fiber fabric and its preparation method, thereby solving the problems existing in the background art.

[0006] To address the aforementioned technical problems, this invention provides a bio-based eco-fiber fabric, comprising a fiber substrate and a bio-modified layer attached to the surface of the fiber substrate by chemical bonding; the fiber substrate is a blend of soybean protein composite fiber and polylactic acid fiber, wherein the soybean protein composite fiber accounts for 30-70% by weight; the soybean protein composite fiber is a blended spun fiber of soybean protein and polyvinyl alcohol, and the bio-modified layer is formed by an in-situ crosslinking reaction of arginine-grafted oxidized sodium alginate and phytic acid on the surface of the fiber substrate; the arginine-grafted oxidized sodium alginate has an amphiphilic structure, and is anchored by a Schiff base covalent bond through a condensation reaction between the aldehyde groups remaining on the molecular backbone and the amino groups on the surface of the fiber substrate.

[0007] Preferably, the fineness of the soybean protein composite fiber is 1.0 to 2.5 dtex, and the fineness of the polylactic acid fiber is 1.2 to 3.0 dtex; the biomodified layer has a continuous gel film structure on the surface of the fiber substrate, and its thickness is 50 to 100 nm.

[0008] A method for preparing bio-based eco-fiber fabric is also provided, comprising the following steps: S1, preparation of modifier precursor: sodium alginate oxide is prepared by sodium periodate oxidation, followed by the introduction of arginine under weakly acidic conditions for grafting reaction. By controlling the reactant ratio, some aldehyde groups on the sodium alginate oxide skeleton are retained. After dialysis and drying, arginine-grafted sodium alginate oxide powder is obtained; S2, compounding and dispersing of finishing solution: arginine-grafted sodium alginate oxide is dissolved in water, phytic acid is added, and dispersion is carried out under mechanical stirring and ultrasonic oscillation to obtain a uniform bio-based functional finishing solution; S3, padding and coating treatment: the greige fabric of soybean protein composite fiber and polylactic acid fiber blend is immersed in the bio-based functional finishing solution, and a two-dip and two-pad process is adopted to allow the finishing solution to penetrate into the fiber interior and surface; S4, gradient temperature crosslinking: the padded greige fabric is sent into a drying room, and successively subjected to low-temperature pre-drying to remove moisture and high-temperature baking to trigger Schiff base condensation reaction to construct a surface gel network and obtain bio-based eco-fiber fabric.

[0009] Preferably, in step S1, the preparation process of oxidized sodium alginate is as follows: a mixed solvent of ethanol and water is prepared, wherein the volume ratio of ethanol to water is 1:(1-3), sodium alginate is dissolved in the mixed solvent, sodium periodate is added, and the reaction is carried out under light-protected conditions with magnetic stirring for 2-6 hours, and the reaction temperature is controlled at 20-30℃; after the reaction is completed, ethylene glycol is added for quenching treatment, and the reaction solution is purified by dialysis bag until the conductivity is less than 10μS / cm. Finally, white flocculent oxidized sodium alginate is obtained by freeze drying or spray drying; the molar ratio of sodium alginate repeating unit to sodium periodate is 1:(0.8-1.2).

[0010] Preferably, in step S1, the preparation process of arginine-grafted sodium alginate is as follows: sodium alginate is prepared into an aqueous solution with a mass concentration of 1% to 5%, and the pH value is adjusted to 5.0 to 6.0 using dilute hydrochloric acid or sodium hydroxide solution; under constant temperature of 35 to 45°C in a water bath and with magnetic stirring, the arginine aqueous solution is slowly added dropwise to the sodium alginate solution, and the pH value is maintained at 5.0 to 6.0 during and after the addition, and the reaction is continued at a constant temperature for 1 to 3 hours; wherein, the mass ratio of sodium alginate to arginine is (2 to 4):1.

[0011] Preferably, in step S2, the amount of phytic acid added is 0.5% to 2.0% of the mass of arginine-grafted oxidized sodium alginate; the dispersion process is as follows: first, mechanically stir at 300 to 500 rpm for 10 to 20 minutes, then ultrasonically disperse at 40 to 60 kHz for 5 to 10 minutes, and use after standing to remove bubbles.

[0012] Preferably, in step S3, the roll residue of the two-dip and two-roll process is controlled at 70% to 85%, and the temperature of the finishing solution is maintained at 20 to 30°C.

[0013] Preferably, in step S4, the pre-baking temperature is 80-90°C and the time is 3-5 minutes; the baking temperature is 100-120°C and the time is 2-4 minutes.

[0014] Preferably, the preparation method is characterized by the fact that no formaldehyde crosslinking agents or metal ion antibacterial agents are added throughout the entire process.

[0015] Compared with the prior art, the present invention has the following beneficial effects: By constructing a biomodified layer with a specific chemical structure on the fiber surface, and utilizing the active groups on the molecular backbone to form covalent bonds with the reaction sites on the fiber substrate surface, the binding form of functional components and substrate is fundamentally changed. This allows the material to maintain a stable adhesion even after repeated washing and mechanical friction, ensuring that the fabric can continuously exert its antibacterial and antistatic effects during long-term service. This avoids rapid performance degradation caused by weak physical adsorption and extends the product's service life.

[0016] The nanogel film structure formed on the fiber surface has good amphiphilic properties, which can improve the wettability of the synthetic fiber surface and form a continuous conductive network, thereby effectively dissipating static charge. It constructs a hydration barrier on the fiber surface, fills the uneven areas of the fiber surface, and gives the fabric a soft and smooth touch. It solves the problem of rough hand feel caused by traditional inorganic finishing agents. The introduced cross-linked network structure has good chelating ability, which helps to maintain the color stability of the fiber during processing and improves the overall appearance quality of the fabric.

[0017] By employing a gradient temperature crosslinking process and controlling the temperature in stages, the process achieves stable removal of moisture and orderly crosslinking reaction, avoiding film defects caused by rapid solvent evaporation. This ensures the formation of a dense, uniform, and continuous gel network on the fiber surface, which not only enhances the physical protective performance of the functional layer but also effectively blocks external media such as sweat from eroding the fiber body. While ensuring the breathability of the fabric, it maintains the original mechanical strength and structural integrity of the fiber material. Detailed Implementation

[0018] Raw material specifications: Sodium alginate: Analytical grade sodium alginate was used, with a weight-average molecular weight (Mw) of 220,000–250,000 Da and a mannouronic acid to guluronic acid (M / G) ratio of 1.2–1.5. Soy protein composite fiber: Commercially available soybean protein / polyvinyl alcohol blend modified fiber is selected, with soybean protein content of 45% to 55% and polyvinyl alcohol content of 45% to 55%, and the surface contains abundant hydroxyl and amino active sites; Grafting rate determination method: The nitrogen content (N%) in pure oxidized sodium alginate and arginine-grafted oxidized sodium alginate was determined using an elemental analyzer. Since the sodium alginate skeleton does not contain nitrogen, all the nitrogen in the grafted product comes from arginine; based on the molecular formula of arginine C6H14N4O2 and its nitrogen content of 32.16%, calculate the grafting rate. Calculation formula: Grafting rate (%) = (N content of sample % / 32.16%) × (arginine molecular weight 174.2 / sodium alginate unit molecular weight 196) × 100%; All grafting rate data recorded in this article are based on this method. Membrane thickness measurement: The cross-section of the fiber was observed using a scanning electron microscope, and the thickness of the skin layer was measured at 10 randomly selected points and the average value was taken. Example 1:

[0019] In this embodiment, the soybean protein composite fiber weight percentage in the fiber substrate is selected as 30%, with the remainder being polylactic acid fiber. The soybean protein composite fiber is made by blending soybean protein and polyvinyl alcohol in a mass ratio of 50:50. This formulation strategy aims to utilize the high modulus characteristics of polylactic acid fiber as a skeleton, while introducing an appropriate amount of soybean protein fiber to improve skin affinity, making it particularly suitable for the development of lightweight summer fabrics. The amphiphilic structure of arginine-grafted sodium alginate plays a key interfacial bridging role here. Its hydrophilic carboxyl side chains improve the wettability of the polylactic acid surface, while the hydrophobic skeleton region forms van der Waals force adsorption with the fiber surface, providing a foundation for subsequent... The continuous covalent bonding provides pre-anchoring sites; specifically, in this embodiment, the fineness of the soybean protein composite fiber is selected as 1.0 dtex, and the fineness of the polylactic acid fiber is selected as 1.2 dtex; the selection of finer fiber fineness aims to increase the specific surface area of ​​the fiber, thereby exposing more amino sites, which helps to improve the grafting density of the biomodified layer; the nanogel membrane structure is not a simple physical cover, but a continuous gel membrane with a thickness of about 50~100 nm is constructed on the fiber surface through the synergistic effect of chemical anchoring of Schiff base bonds and physical chelation of phytic acid. This structure effectively blocks the erosion of the fiber body by sweat, while giving the fabric a smooth touch; S1. Preparation of Modifier Precursor: Sodium alginate oxide was prepared by sodium periodate oxidation. Then, arginine was introduced under weakly acidic conditions for a grafting reaction. By controlling the reactant ratio, some aldehyde groups on the sodium alginate oxide skeleton were retained. After dialysis and freeze-drying, arginine-grafted sodium alginate oxide powder was obtained. This step is crucial for constructing the functionalized building blocks. All raw materials used in this embodiment were commercially available analytical grade. The sodium alginate had a weight-average molecular weight of approximately 230,000 Da and a viscosity of 200-500 mPa. •s (1% aqueous solution, 20℃); The specific operation is as follows: Prepare a mixed solvent of ethanol and water with a volume ratio of 1:1, dissolve sodium alginate in it, add sodium periodate, and control the molar ratio of sodium alginate repeating units to sodium periodate to be 1:0.8; react at 20℃ in the dark for 2 hours; the introduction of ethanol as a co-solvent aims to reduce the dielectric constant of the system, inhibit the excessive swelling of the sodium alginate molecular chain, thereby limiting the oxidation reaction to mainly occur on the surface and amorphous region of the molecular chain, and preserving the mechanical strength of the core skeleton; after the reaction, add excess ethylene glycol, specifically with a molar ratio of 1.5:1 to sodium periodate, to completely quench unreacted sodium periodate and prevent uncontrolled oxidation during subsequent dialysis; the reaction temperature is controlled at 20℃ and the reaction time is relatively short at 2 hours in order to prepare a product with low oxidation degree in combination with a low oxidant ratio, and minimize the degradation of the main chain; the final yield of oxidized sodium alginate is about 88%; in this example, the oxidized sodium alginate is prepared as a 1% solution, the pH is adjusted to 5.0, and reacted at 3 Arginine was added dropwise at 5℃ at a mass ratio of 2:1, and the reaction was carried out for 1 hour. Under this weakly acidic pH 5.0 environment, the α-amino group of arginine was in a state of protonation and deprotonation equilibrium, which was conducive to its nucleophilic attack on the aldehyde group on sodium alginate to form an unstable intermediate, which was then dehydrated to form a Schiff base. The relatively low reaction temperature (35℃) was controlled to prevent the reversible hydrolysis of the formed Schiff base in aqueous solution and to ensure the grafting rate. The grafting rate of the obtained arginine grafted onto sodium alginate was determined to be approximately 12.5%. S2. Finishing Solution Coagulation and Dispersion: Arginine-grafted oxidized sodium alginate was dissolved in water, phytic acid was added, and dispersion was carried out under mechanical stirring and ultrasonic oscillation to obtain a uniform bio-based functional finishing solution. This step achieves molecular-level mixing of the crosslinking agent and the functional matrix. In this embodiment, arginine-grafted oxidized sodium alginate was first dissolved in deionized water to prepare a matrix solution with a mass concentration of 2.0%. This concentration ensures that the finishing solution has a suitable viscosity to adhere to the fiber surface without causing clogging. The phytic acid used was commercially available. A 70% aqueous solution was added at a concentration equivalent to 0.5% of the mass of arginine-grafted oxidized sodium alginate, calculated based on the pure substance. The solution was stirred at 300 rpm for 10 minutes and sonicated at 40 kHz for 5 minutes. The low phytic acid concentration was to avoid premature gelation in the solution and to ensure the fluidity of the finishing solution. The coupling effect of mechanical stirring and ultrasound effectively broke the molecular chain entanglement of arginine-grafted oxidized sodium alginate, allowing phytic acid molecules to be uniformly embedded into the gaps in the polymer chain, thus pre-embedding anchor points for subsequent in-situ crosslinking. S3. Pad Coating Treatment: The grey fabric blended with soybean protein composite fiber and polylactic acid fiber is immersed in a bio-based functional finishing solution using a two-dip, two-pad process to allow the finishing solution to penetrate into the fiber interior and surface. This step completes the physical loading of the functional solution onto the fabric surface. In this embodiment, the pad-up rate is controlled at 70%, and the finishing solution temperature is 20°C. The lower pad-up rate combined with the lower finishing solution temperature aims to control the thickness of the liquid film and prevent the problem of a stiff hand feel after drying due to an excessively thick liquid film. At the same time, the low temperature environment of 20°C inhibits potential side reactions in the solution, ensuring the retention rate of aldehyde groups before entering the drying room. S4. Gradient Temperature Crosslinking: The impregnated fabric is sent to a drying oven, where it undergoes low-temperature pre-drying to remove moisture and high-temperature baking to trigger the Schiff base condensation reaction, constructing a surface gel network to obtain a bio-based eco-fiber fabric. Gradient temperature is the core process for achieving structural densification. In this embodiment, the pre-drying temperature is set at 80°C for 3 minutes, and the baking temperature is set at 100°C for 2 minutes. The first pre-drying at 80°C aims to remove free water at a relatively gentle rate, preventing the vapor pressure generated by rapid evaporation of moisture from disrupting the continuity of the liquid film. The subsequent baking at 100°C is a thermodynamically necessary condition for triggering the Schiff base condensation reaction. At this temperature, the movement of molecular chain segments intensifies, and the residual aldehyde groups undergo multiple cross-linking with the amino groups on the fiber surface and the guanidine groups on arginine. At the same time, the phosphate groups of phytic acid and the polar groups in soybean protein form a hydrogen bond network, which together solidifies the gel structure. In this embodiment, by using a lower degree of oxidation and milder cross-linking conditions, the positive charge is introduced by the guanidine groups of arginine while ensuring that the fiber strength is not damaged. Combined with the film-forming properties of oxidized sodium alginate, the problem of polylactic acid fiber being prone to static electricity and having a rough hand feel is improved. The resulting fabric has a smooth hand feel and is suitable for the field of infant and toddler clothing where the softness requirement is extremely high. Example 2:

[0020] This embodiment provides a solution focusing on warmth retention and high-strength antibacterial properties. The soybean protein composite fiber in the fiber substrate is selected as 70% by weight, with a fineness of 2.5 dtex, and polylactic acid fiber is 3.0 dtex. The high proportion of protein fibers aims to mimic the warmth retention properties of cashmere. In S1, the volume ratio of ethanol to water is adjusted to 1:3, the molar ratio of oxidant is increased to 1:1.2, the reaction temperature is 30°C, and the reaction time is 6 hours. This high-intensity oxidation condition aims to generate a high density of aldehyde sites, sacrificing some molecular chain length, but providing a foundation for subsequent high-density cross-linking. In the grafting reaction, the mass ratio of oxidized sodium alginate to arginine is 4:1, pH 6.0, and the reaction is carried out at 45°C for 3 hours to promote greater arginine loading. In S2... In step S3, arginine is grafted onto sodium alginate to prepare a 2.5% (w / w) solution to increase the solid content of the finishing solution. The phytic acid addition is increased to 2.0%, and vigorous stirring at 500 rpm is performed. The high concentration of phytic acid not only acts as a cross-linking agent but also as a natural antioxidant, preventing the protein fibers from yellowing during high-temperature treatment. In step S4, the pick-up rate is controlled at 85%, and the finishing temperature is 30℃ to ensure sufficient liquid absorption. In step S5, the pre-drying temperature is 90℃ for 5 minutes, followed by baking at 120℃ for 4 minutes. The high-temperature baking promotes the formation of a dense cross-linking network, enabling the fabric to maintain excellent antibacterial properties even after high-intensity washing. It is particularly suitable for use as a lining for sports protective equipment, solving the problems of bacterial growth and odor after sweating during exercise. Example 3:

[0021] This embodiment provides a standardized solution with balanced performance; the soybean protein composite fiber in the fiber substrate accounts for 50%, with a fineness of 1.5 dtex / 2.0 dtex, balancing hygroscopicity and quick-drying properties; in S1, the volume ratio of ethanol to water is 1:2, the molar ratio of oxidant is 1:1.0, and the reaction is carried out at 25°C for 4 hours; these parameters are in the equilibrium range, and the prepared oxidized sodium alginate has both good film-forming properties and moderate reactivity; the grafting reaction is controlled at pH 5.5, 40°C, and a mass ratio of 3:1; in S2, arginine is grafted onto the oxidized sodium alginate to prepare a solution with a mass concentration of 2.0%. Phytic acid was added at 1.2%, and the mixture was dispersed at 400 rpm / 50 kHz. Medium-intensity ultrasonic dispersion ensured uniform particle size distribution of the finishing solution. In S3, the roll-off rate was 78% at 25°C. In S4, the pre-drying temperature was 85°C / 4 min, followed by baking at 110°C / 3 min. This gradient temperature curve effectively avoided the skin-core effect, i.e., the phenomenon of excessively rapid surface film formation without internal moisture drying. The resulting fabric combines good hand feel and long-lasting antibacterial properties. Due to the chelating effect of phytic acid, the fabric has a bright color and is not prone to heat yellowing during processing, making it very suitable as a fabric for high-end yoga wear. Example 4:

[0022] This embodiment aims to explore a high-efficiency implementation path under low finishing agent concentration; the fiber substrate contains 40% soybean protein composite fiber with a fineness of 1.2 dtex / 1.5 dtex; in S1, the volume ratio of ethanol to water is 1:1.5, the molar ratio of oxidant is 1:0.9, and the reaction is carried out at 22°C for 3 hours; a relatively long molecular chain is retained through mild oxidation; the grafting reaction is carried out at pH 5.2, 38°C, and a mass ratio of 2.5:1; in S2, arginine is grafted onto sodium alginate to prepare a dilute solution with a mass concentration of 1.5% to reduce the liquid film. Thickness, phytic acid addition 0.8%; in S3, the roll-off rate is 75%, 22℃; in S4, pre-drying is 82℃ / 3.5min, baking is 105℃ / 2.5min; this embodiment strengthens the distribution density of arginine on the sodium alginate skeleton through specific oxidation degree and grafting ratio, so that the prepared bio-based ecological fiber fabric still shows a significant inhibitory effect on Staphylococcus aureus at a relatively low finishing agent concentration, while maintaining the fabric's lightness and breathability, making it suitable for making home wear for the spring and summer transition season. Example 5:

[0023] This embodiment focuses on constructing a thick film structure with moisturizing function. The fiber substrate contains 60% soybean protein composite fiber with a fineness of 2.0 dtex / 2.5 dtex. In S1, the volume ratio of ethanol to water is 1:2.5, the molar ratio of oxidant is 1:1.1, and the reaction is carried out at 28℃ for 5 hours. In S2, arginine-grafted oxidized sodium alginate is prepared into a high-concentration solution with a mass concentration of 3.0%, and phytic acid is added at 1.5%. In S3, the roll-off rate is 82%, and the reaction is carried out at 28℃. In S4, pre-drying is performed at 88℃ for 4.5 min, followed by baking at 115℃ for 3.5 min. This embodiment, by increasing the base concentration of the finishing solution and controlling the aldehyde content of oxidized sodium alginate and the grafting amount of arginine, allows the bio-modified layer to form a hydrated gel layer of a certain thickness on the fiber surface. This structure not only effectively locks in antibacterial components but also endows the fabric with excellent moisturizing properties, alleviating itching caused by dry skin in autumn and winter, making it suitable for the development of thermal underwear.

[0024] Comparative Example 1: This comparative example provides a method for preparing a bio-based fiber fabric, which differs from Example 3 only in that: in step S1, sodium alginate that has not undergone oxidation treatment is directly mixed with arginine without a chemical grafting reaction; and in steps S2 and S4, due to the lack of aldehyde groups, Schiff base covalent bonds cannot be formed, and the fabric is attached only by physical adsorption and hydrogen bonding; the remaining steps are consistent with Example 3; this comparative example aims to verify the necessity of oxidative grafting modification for constructing a covalently bonded network.

[0025] Comparative Example 2: This comparative example provides a method for preparing a bio-based fiber fabric, which differs from Example 3 only in that: phytic acid is not added in step S2; the remaining steps are consistent with Example 3; this comparative example aims to verify the auxiliary bridging and catalytic effect of phytic acid in the cross-linked network.

[0026] Comparative Example 3: This comparative example provides a method for preparing an antibacterial fiber fabric. It adopts a traditional padding process and uses commercially available nano-silver antibacterial agent to treat a blended fabric of soybean protein composite fiber and polylactic acid fiber, without using arginine-grafted sodium alginate. This comparative example represents the mainstream inorganic antibacterial finishing scheme in the prior art.

[0027] Comparative Example 4: This comparative example provides a method for preparing a bio-based fiber fabric, which differs from Example 3 only in that: in step S4, instead of using a gradient temperature crosslinking process, the impregnated fabric is directly sent into a high-temperature drying room at 110°C for one-step drying and baking for 7 minutes; the remaining steps are consistent with Example 3; this comparative example aims to verify the importance of the gradient temperature process for maintaining the integrity of the gel membrane structure and preventing Schiff base hydrolysis.

[0028] Verification experiment: To verify the performance of the bio-based eco-fiber fabric of the present invention, performance tests were conducted on the fabrics prepared in Examples 1-5 and Comparative Examples 1-4. Testing standards: Washability and antibacterial properties: After washing 50 times according to the GB / T8629 standard procedure, the antibacterial rate against Staphylococcus aureus and Escherichia coli was tested according to the GB / T20944.3 shaking method. Antistatic properties: Surface resistivity after 50 washes, according to GB / T12703.1 standard; Touch evaluation: Subjective touch evaluation was conducted by 5 professional evaluators in a blind test, and the results were divided into smooth and soft, average, and rough / stiff. Strength retention rate: The percentage of the breaking strength after finishing relative to the original fabric, as tested according to GB / T3923.1; Specific testing process: All samples were conditioned for 24 hours under constant temperature and humidity (20±2℃, 65±4%RH) conditions before testing. For antibacterial performance, each sample was tested in parallel three times and the average value was taken. For surface resistivity, the geometric mean of five different points was taken. For strength retention rate, five tests were conducted in the warp and weft directions and the average value was taken.

[0029] Data table:

[0030] Result analysis components: The data in the table above and the comparative analysis show that the bio-based ecological fiber fabrics prepared in Examples 1-5 maintained an antibacterial rate of over 90% against Staphylococcus aureus and Escherichia coli after 50 washes, and the surface resistivity was significantly reduced to the order of magnitude. This indicates that arginine grafted oxidized sodium alginate is firmly anchored to the fiber surface through Schiff base covalent bonds, forming a stable conductive antibacterial layer. Mechanism Analysis and Comparative Explanation of Differences: 1. The Crucial Role of Chemical Bonding: Comparing Example 3 with Comparative Example 1, it can be seen that the unoxidized sodium alginate lacks aldehyde groups and cannot form Schiff base covalent bonds with the amino and arginine on the fiber surface, relying solely on physical adsorption. Under the mechanical shear force of repeated washing, a large number of functional molecules are detached, causing the antibacterial rate to plummet from 93.2% to 35.4%, and the surface resistivity to increase significantly, resulting in the loss of antistatic function. 2. Synergistic Crosslinking Effect: Comparing Example 3 with Comparative Example 2, the absence of phytic acid leads to a decrease in the antibacterial rate of approximately 10 percentage points, and the strong retention rate decreases to 91.5%. This is because phytic acid not only increases the density of the membrane layer as a crosslinking agent, but its phosphate groups can also chelate any trace metal ions that may be present, preventing them from catalyzing fiber degradation. Without phytic acid, the gel network... 3. Thermodynamic effects of the process: Compared with Comparative Example 4, Comparative Example 4, which uses a one-step high-temperature drying method, has a lower antibacterial rate and a less desirable feel than the gradient temperature process. The mechanism is that direct high temperature causes the moisture on the liquid film surface to vaporize instantly, forming micropores and destroying the continuity of the gel film. At the same time, direct high-temperature baking without removing moisture may induce some of the already formed Schiff bases to undergo reverse hydrolysis, reducing the crosslinking density. The gradient process of this invention first removes moisture at low temperature and then cures at high temperature, ensuring the integrity and density of the film layer. 4. Comparison with traditional technology: Comparative Example 3 uses nano-silver, which has a good initial effect, but the physically attached particles are easy to lose, and the nanoparticles increase the roughness of the fiber surface, resulting in a stiff feel, which cannot meet the needs of high-end intimate apparel. In summary, this invention utilizes the synergistic effect of arginine grafted onto oxidized sodium alginate and phytic acid, combined with a gradient temperature crosslinking process, to construct a bio-modified layer with antibacterial, antistatic, and moisturizing functions in situ on the fiber surface. This solves the problems of limited functionality and poor washability of bio-based fiber fabrics. Furthermore, the preparation method described in this invention does not require the addition of toxic aldehyde crosslinking agents such as formaldehyde and glutaraldehyde, nor does it rely on heavy metal antibacterial agents such as silver or copper ions. By constructing the network through the chemical reaction of the bio-based material itself, it not only avoids the potential irritation of human skin by residual toxic substances but also eliminates the risk of heavy metal pollution in production wastewater.

[0031] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A bio-based eco-fiber fabric, characterized in that, It includes a fiber substrate and a biomodified layer attached to the surface of the fiber substrate by chemical bonding; the fiber substrate is made of a blend of soybean protein composite fiber and polylactic acid fiber, wherein the weight percentage of soybean protein composite fiber is 30-70%; the soybean protein composite fiber is a blended spun fiber of soybean protein and polyvinyl alcohol, and the biomodified layer is formed by in-situ crosslinking reaction of arginine-grafted oxidized sodium alginate and phytic acid on the surface of the fiber substrate; the arginine-grafted oxidized sodium alginate has an amphiphilic structure, and is anchored by Schiff base covalent bonds through the condensation reaction between the aldehyde groups remaining on the molecular backbone and the amino groups on the surface of the fiber substrate.

2. The bio-based eco-fiber fabric as described in claim 1, characterized in that, The fineness of soybean protein composite fiber is 1.0–2.5 dtex, and the fineness of polylactic acid fiber is 1.2–3.0 dtex; the biomodified layer has a continuous gel film structure on the surface of the fiber substrate, with a thickness of 50–100 nm.

3. A method for preparing a bio-based eco-fiber fabric as described in claim 1 or 2, characterized in that, Includes the following steps: S1. Preparation of Modifier Precursor: Sodium alginate oxide was prepared by sodium periodate oxidation. Then, arginine was introduced under weakly acidic conditions for grafting reaction. By controlling the reactant ratio, some aldehyde groups on the sodium alginate oxide skeleton were retained. After dialysis and drying, arginine-grafted sodium alginate oxide powder was obtained. S2. Finishing Solution Compounding and Dispersion: Arginine-grafted sodium alginate oxide was dissolved in water, phytic acid was added, and dispersion was carried out under mechanical stirring and ultrasonic oscillation to obtain a uniform bio-based functional finishing solution. S3. Impregnation and Coating Treatment: The fabric blended with soybean protein composite fiber and polylactic acid fiber was immersed in the bio-based functional finishing solution and a two-dip and two-ply process was adopted to allow the finishing solution to penetrate into the fiber interior and surface. S4. Gradient temperature crosslinking: The impregnated fabric is sent into the drying room and successively subjected to low-temperature pre-drying to remove moisture and high-temperature baking to trigger Schiff base condensation reaction, thereby constructing a surface gel network and obtaining bio-based ecological fiber fabric.

4. The method for preparing a bio-based eco-fiber fabric as described in claim 3, characterized in that, In step S1, the preparation process of oxidized sodium alginate is as follows: a mixed solvent of ethanol and water is prepared, wherein the volume ratio of ethanol to water is 1:(1-3). Sodium alginate is dissolved in the mixed solvent, sodium periodate is added, and the reaction is carried out under light-protected conditions with magnetic stirring for 2-6 hours, and the reaction temperature is controlled at 20-30℃. After the reaction is completed, ethylene glycol is added for quenching treatment. The reaction solution is purified by dialysis through a dialysis bag until the conductivity is less than 10 μS / cm. Finally, white flocculent oxidized sodium alginate is obtained by freeze drying or spray drying. The molar ratio of sodium alginate repeating unit to sodium periodate is 1:(0.8-1.2).

5. The method for preparing a bio-based eco-fiber fabric as described in claim 3, characterized in that, In step S1, the preparation process of arginine-grafted sodium alginate is as follows: sodium alginate is prepared into an aqueous solution with a mass concentration of 1% to 5%, and the pH value is adjusted to 5.0 to 6.0 using dilute hydrochloric acid or sodium hydroxide solution; under constant temperature of 35 to 45°C in a water bath and with magnetic stirring, the arginine aqueous solution is slowly added dropwise to the sodium alginate solution, and the pH value is maintained at 5.0 to 6.0 during and after the addition, and the reaction is continued at a constant temperature for 1 to 3 hours; wherein, the mass ratio of sodium alginate to arginine is (2 to 4):

1.

6. The method for preparing a bio-based eco-fiber fabric as described in claim 3, characterized in that, In step S2, the amount of phytic acid added is 0.5% to 2.0% of the mass of arginine-grafted oxidized sodium alginate; the dispersion process is as follows: first, mechanically stir at 300 to 500 rpm for 10 to 20 minutes, then ultrasonically disperse at 40 to 60 kHz for 5 to 10 minutes, and use after standing to remove bubbles.

7. The method for preparing a bio-based eco-fiber fabric as described in claim 3, characterized in that, In step S3, the roll residue of the two-dip and two-roll process is controlled at 70% to 85%, and the temperature of the finishing solution is maintained at 20 to 30°C.

8. The method for preparing a bio-based eco-fiber fabric as described in claim 3, characterized in that, In step S4, the pre-baking temperature is 80-90℃ and the time is 3-5 minutes; the baking temperature is 100-120℃ and the time is 2-4 minutes.

9. The method for preparing a bio-based eco-fiber fabric as described in claim 3, characterized in that, The entire preparation process does not involve the addition of formaldehyde-based crosslinking agents or metal ion antibacterial agents.

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