Bio-based fabric conversion process

Abstract

The invention relates to a bio-based fabric conversion process, which belongs to the technical field of fabrics, and comprises the following steps: mixing glycerol, itaconic acid and 4-toluene sulfonic acid according to a mass ratio of (9.0-10.0): (12.5-13.5): (0.01-0.02), introducing nitrogen for protection, heating to 140-160 DEG C, carrying out melt polycondensation reaction for 2-4 hours, vacuumizing, carrying out vacuum dehydration treatment for 1-3 hours, and cooling to obtain hydroxyl-terminated hyperbranched polyester; the hydroxyl-terminated hyperbranched polyester is dissolved in anhydrous acetone, isophorone diisocyanate and dibutyltin dilaurate are added, the mass ratio of the isophorone diisocyanate to the hydroxyl-terminated hyperbranched polyester is (1.0-1.2): 1, the mixture is stirred at the constant temperature of 50-60 DEG C for a reaction for 1.5-2.5 h, an isocyanate-terminated prepolymer is prepared, and the isocyanate-terminated hyperbranched polyester-dibutyltin dilaurate copolymer is obtained. The formed flexible cross-linked network can effectively disperse stress concentration when the fibers are subjected to external force, and accumulation of stress on a single cross-linked point is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fabrics, in particular to a bio-based fabric conversion process. BACKGROUND

[0002] With the increasing demand for functional textiles, bio-based fabrics represented by cotton, hemp, viscose and lyocell are increasingly widely used in daily clothing and home textiles. However, such fabrics generally have problems such as easy wrinkling, poor dimensional stability, and easy bacterial growth during actual use. In particular, pure cotton fabric and viscose fiber are prone to wrinkling after washing and wearing, affecting the appearance; hemp fabric is not only prone to wrinkling, but also often has a rough and itchy feel; Currently, the industry usually uses resin finishing agents to treat the above-mentioned fabrics for wrinkle resistance. However, in actual application, traditional finishing processes have obvious limitations; common chemical crosslinking agents continuously release formaldehyde during finishing and subsequent use of the fabric; not only does it pose a potential threat to the health of production personnel and consumers, but it also makes it difficult to meet the requirements of green and environmentally friendly industries; traditional wrinkle-resistant finishing often sacrifices fiber strength. When existing technologies improve the wrinkle resistance of fabrics, they often cause severe hydrolysis or excessive crosslinking of cellulose molecules, resulting in a significant decrease in the breaking strength of the fabric, which seriously shortens the service life of the fabric; In addition, the functionalization means of existing fabrics often cannot balance durability and comfort. Many finishing agents that claim to have antibacterial properties can only be attached to the surface of the fiber through physical adsorption, resulting in rapid loss of functional components after multiple washes, which cannot provide long-term protection. At the same time, due to the poor matching of the molecular structure of the finishing agent and the fiber, the finished fabric often becomes stiff and rough, losing the original softness of the bio-based fiber; therefore, how to simultaneously improve the efficient wrinkle resistance, long-lasting antibacterial properties and comfort of bio-based fabrics without using formaldehyde-containing additives is a difficult problem that needs to be solved in the field of textile processing.

[0003] The above information disclosed in the background section is only used to enhance the understanding of the background of the present disclosure, and therefore it can include information that does not constitute prior art known to those of ordinary skill in the art. SUMMARY

[0004] The purpose of the present application is to provide a bio-based fabric conversion process to solve the problems raised in the background art.

[0005] The technical solution of the present application is as follows: (1) mixing glycerol, itaconic acid, 4-methylbenzenesulfonic acid according to the mass ratio of 9.0-10.0:12.5-13.5:0.01-0.02, passing nitrogen protection, heating to 140-160℃, carrying out melt polycondensation reaction for 2-4h, then vacuum dehydration treatment for 1-3h, cooling to obtain the hydroxyl-terminated hyperbranched polyester; (2) dissolving the hydroxyl-terminated hyperbranched polyester in anhydrous acetone, adding isophorone diisocyanate, dibutyltin dilaurate, wherein the mass ratio of isophorone diisocyanate to hydroxyl-terminated hyperbranched polyester is 1.0-1.2:1, stirring at 50-60℃ for 1.5-2.5h to obtain the isocyanate group terminated prepolymer; (3) adding the hydroxypropyltrimethylammonium chloride chitosan dissolved in water to the isocyanate group terminated prepolymer, the mass ratio of the hydroxypropyltrimethylammonium chloride chitosan to the isocyanate group terminated prepolymer is 0.1-0.15:1, reacting for 0.5-1.5h, then adding sodium bisulfite aqueous solution, the mass ratio of the sodium bisulfite to the isocyanate group terminated prepolymer is 0.2-0.3:1, carrying out high-speed shearing emulsification for 20-40min, then removing acetone by rotary evaporation under reduced pressure to obtain the stable aqueous bio-based hyperbranched modifier emulsion containing carbamic acid sulfonate structure; (4) immersing the bio-based fabric in the finishing liquid prepared from the aqueous bio-based hyperbranched modifier emulsion, magnesium chloride and water, wherein the concentration of the modifier is 40-80g / L, the concentration of magnesium chloride is 1.5-2.5g / L, and the pH value is adjusted to 5.0-6.0 using acetic acid or citric acid, carrying out double immersion and double padding, and controlling the pick-up rate to be 70%-80%; (5) pre-drying the immersed and padded bio-based fabric at 90-100℃ for 2-3min, then carrying out high-temperature baking treatment at 160-170℃ for 120-180s, washing with warm water after taking out, drying and setting to obtain the in-situ cross-linked functionalized bio-based fabric.

[0006] Preferably, the vacuum degree of the vacuum dehydration treatment in step (1) is controlled to be to .

[0007] Preferably, the rotation speed of the high-speed shearing emulsification in step (3) is 3000-5000rpm.

[0008] Preferably, the temperature of the rotary evaporation under reduced pressure in step (3) is controlled to be 40-50℃.

[0009] Preferably, the bio-based fabric in step (4) is one of pure cotton plain fabric, ramie fabric, viscose fabric or lyocell fabric.

[0010] Preferably, in the high-temperature baking process of step (5), the carbamic acid sulfonate structure formed by sodium bisulfite capping in the aqueous bio-based hyperbranched modifier emulsion prepared in step (3) is pyrolyzed and uncapped to regenerate isocyanate groups, which adduct with the hydroxyl groups on the surface of the bio-based fabric fibers to form urethane bonds.

[0011] The present application provides a bio-based fabric conversion process by improving the prior art, which has the following improvements and advantages: 1. The present application uses hyperbranched polyester formed by glycerol and itaconic acid polymerization as the core skeleton, which is different from traditional 2D resin and other linear crosslinking agents. Hyperbranched polymers have a unique quasi-spherical structure and a large number of terminal active groups. During high-temperature baking, the flexible crosslinking network formed by the system can effectively disperse the stress concentration of the fibers when subjected to external force, avoiding the accumulation of stress on a single crosslinking point. Experimental data show that the crease recovery angle of pure cotton, hemp and viscose fabrics can be improved to 248° to 272°, and the breaking strength retention rate is still maintained at more than 85%. This overcomes the defect that anti-wrinkle and strength cannot be achieved in the prior art, and does not involve formaldehyde components throughout, achieving green and environmentally friendly finishing; 2. The present application uses isophorone diisocyanate as a connecting arm to chemically graft cationic antibacterial active hydroxypropyl trimethyl ammonium chloride chitosan onto the hyperbranched skeleton. The key is to use sodium bisulfite to cap the isocyanate groups, so that they remain stable in the emulsion state, and are pyrolyzed and uncapped during the high-temperature baking stage. The high-activity isocyanate groups released after uncapping can adduct with the hydroxyl groups on the surface of the fibers to form firm urethane bonds. This in-situ crosslinking mechanism changes the antibacterial component from physical attachment to chemical anchoring, ensuring that the antibacterial rate remains above 95% after 50 standard washes. DETAILED DESCRIPTION

[0012] To make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below with specific examples. Example 1:

[0013] The present application provides a bio-based fabric conversion process, which aims to solve the problem of easy wrinkling and bacterial growth of pure cotton plain fabric in daily use, and improves the dimensional stability and hygiene performance of the fabric without using formaldehyde. The specific steps are as follows: (1) Glycerol, itaconic acid, 4-methylbenzenesulfonic acid were mixed in a mass ratio of 9.0:12.5:0.01, and nitrogen was introduced to protect the mixture. The mixture was heated to 140°C and subjected to melt polycondensation reaction for 4h. The lower temperature setting in this stage was intended to prevent the bio-based monomers from excessive oxidation and discoloration. The amount of catalyst 4-methylbenzenesulfonic acid was 0.01, which ensured that the reaction was completed within 4h and the branching degree reached 0.65, and minimized the potential impact of residual acidic catalyst on the whiteness of cotton fibers. After the reaction was completed, vacuum dehydration treatment was performed for 3h at a vacuum degree of-0.08MPa. The temperature was then lowered to obtain the hydroxyl-terminated hyperbranched polyester. Gel permeation chromatography test showed that the number average molecular weight Mn of the obtained polyester was 4500.

[0014] (2) The hydroxyl-terminated hyperbranched polyester was dissolved in anhydrous acetone, and isophorone diisocyanate and dibutyltin dilaurate were added, wherein the mass ratio of isophorone diisocyanate to hydroxyl-terminated hyperbranched polyester was 1.0:1. The mixture was stirred at 50°C for 2.5h to obtain an isocyanate group-terminated prepolymer. The isophorone diisocyanate introduced in this step served as a linking arm, and the remaining isocyanate groups provided reactivity for subsequent functionalization.

[0015] (3) An aqueous solution of hydroxypropyltrimethylammonium chloride chitosan dissolved in water was added dropwise to the isocyanate group-terminated prepolymer, and the mass ratio of hydroxypropyltrimethylammonium chloride chitosan to isocyanate group-terminated prepolymer was 0.1:1. After 1.5h of reaction, an aqueous solution of sodium bisulfite was added, and the mass ratio of sodium bisulfite to isocyanate group-terminated prepolymer was 0.2:1. High-speed shearing emulsification was performed at a speed of 3000rpm for 40min. Subsequently, acetone was removed by rotary evaporation under reduced pressure, and the temperature was controlled at 40°C to obtain a stable aqueous bio-based hyperbranched modifier emulsion containing a sulfonate carbamic acid structure.

[0016] (4) Pure cotton plain fabric was selected as a bio-based fabric, which was immersed in a finishing liquid prepared from the aqueous bio-based hyperbranched modifier emulsion, magnesium chloride, and water. The concentration of the modifier was 40g / L, the concentration of magnesium chloride was 1.5g / L, and acetic acid was used to adjust the pH value to 5.0. Double-dipping and double-padding were performed, and the wet pick-up rate was controlled at 70%. The lower concentration of the modifier was suitable for finishing of summer cotton fabrics with high air permeability requirements.

[0017] (5) The bio-based fabric after padding was pre-dried at 90°C for 3min, and then subjected to high-temperature curing treatment at 160°C for 180s. In this process, the sodium bisulfite-terminated isocyanate groups formed in step (3) were pyrolyzed and released, and the generated isocyanate groups reacted with the hydroxyl groups on the surface of the bio-based fabric to form carbamate bonds. After removal, the fabric was washed with warm water and dried to obtain an in-situ cross-linked functionalized bio-based fabric. Example 2:

[0018] This embodiment provides a bio-based fabric conversion process, primarily targeting the characteristics of linen fibers such as high rigidity and easy wrinkling. By adjusting the formula ratio to enhance the crosslinking density, the wearing performance of linen fabrics is improved. The specific steps are as follows: (1) Glycerol, itaconic acid, and 4-methylbenzenesulfonic acid were mixed in a mass ratio of 9.5:13.0:0.015, and nitrogen gas was introduced for protection. The mixture was heated to 150°C and subjected to a melt polycondensation reaction for 3 hours. After the reaction, the mixture was subjected to vacuum dehydration for 2 hours, with the vacuum level controlled at -0.09 MPa. The mixture was then cooled to obtain a hydroxyl-terminated hyperbranched polyester. The above reaction conditions ensured that the polyester backbone had a suitable degree of branching and molecular weight.

[0019] (2) The hydroxyl-terminated hyperbranched polyester was dissolved in anhydrous acetone, and isophorone diisocyanate and dibutyltin dilaurate were added, wherein the mass ratio of isophorone diisocyanate to hydroxyl-terminated hyperbranched polyester was 1.1:1. The mixture was stirred at 55°C for 2.0 h to obtain an isocyanate-terminated prepolymer. This ratio is intended to improve the reactivity of the final finishing agent with the fiber.

[0020] (3) An aqueous solution containing hydroxypropyltrimethylammonium chloride chitosan was added dropwise to the isocyanate-terminated prepolymer. The mass ratio of hydroxypropyltrimethylammonium chloride chitosan to isocyanate-terminated prepolymer was 0.125:1. After reacting for 1.0 h, an aqueous solution of sodium bisulfite was added. The mass ratio of sodium bisulfite to isocyanate-terminated prepolymer was 0.25:1. High-speed shear emulsification was performed at a rotation speed of 4000 rpm for 30 min. Acetone was then removed by vacuum rotary evaporation at a temperature controlled at 45 °C to obtain a stable aqueous bio-based hyperbranched modifier emulsion containing carbamate sulfonate structure. The moderate shear rate ensured the uniformity of the emulsion particle size, which facilitated penetration into the interior of hemp fibers.

[0021] (4) Linen fabric was selected as the bio-based fabric and immersed in a finishing solution. The finishing solution was prepared from the aqueous bio-based hyperbranched modifier emulsion, magnesium chloride, and water, wherein the modifier concentration was 60 g / L, the magnesium chloride concentration was 2.0 g / L, and the pH value was adjusted to 5.5 using citric acid. The mixture was dipped and nibbled twice, with the liquid-holding ratio controlled at 75%. Increasing the modifier concentration helps to fill the large gaps in the linen fibers and build a stronger wrinkle-resistant skeleton.

[0022] (5) The impregnated bio-based fabric is pre-dried at 95°C for 2.5 min, and then subjected to high-temperature baking at 165°C for 150 s. During this process, the sodium bisulfite-terminated isocyanate groups formed in step (3) undergo thermal desealing, and the generated isocyanate groups react with the hydroxyl groups on the surface of the bio-based fabric fibers to form urethane bonds. After removal, the fabric is washed with warm water, dried and shaped to obtain the in-situ cross-linked functionalized bio-based fabric. This chemical anchoring effect significantly improves the wash resistance of linen fabrics. Example 3:

[0023] This embodiment provides a bio-based fabric conversion process that addresses the low wet strength of viscose fiber fabrics by enhancing the bonding force between fibers through a high-density cross-linked network, while simultaneously imparting antibacterial properties. The specific steps are as follows: (1) Glycerol, itaconic acid, and 4-methylbenzenesulfonic acid were mixed in a mass ratio of 10.0:13.5:0.02, and nitrogen gas was introduced for protection. The mixture was heated to 160°C and subjected to a melt polycondensation reaction for 2 hours. The higher monomer ratio and temperature promoted the reaction rate. The catalyst dosage of 0.02 was selected here to meet the high modification requirements of viscose fiber and quickly construct a highly branched skeleton with a DB of 0.75. At the same time, the reaction kinetics were precisely controlled to ensure high reactivity while avoiding crosslinking runaway. After the reaction, vacuum dehydration was performed for 1 hour. The vacuum degree of the vacuum dehydration was controlled at -0.1 MPa. After cooling, hydroxyl-terminated hyperbranched polyester was obtained.

[0024] (2) The hydroxyl-terminated hyperbranched polyester was dissolved in anhydrous acetone, and isophorone diisocyanate and dibutyltin dilaurate were added, wherein the mass ratio of isophorone diisocyanate to hydroxyl-terminated hyperbranched polyester was 1.2:1. The reaction was carried out at 60°C with constant temperature stirring for 1.5 h to obtain isocyanate-based end-capped prepolymer.

[0025] (3) An aqueous solution containing hydroxypropyltrimethylammonium chloride chitosan was added dropwise to the isocyanate-terminated prepolymer. The mass ratio of hydroxypropyltrimethylammonium chloride chitosan to isocyanate-terminated prepolymer was 0.15:1, and the reaction was carried out for 0.5 h. This mass ratio was intended to impart stronger antibacterial properties to the fabric. Subsequently, an aqueous solution of sodium bisulfite was added. The mass ratio of sodium bisulfite to isocyanate-terminated prepolymer was 0.3:1, and high-speed shear emulsification was performed at a rotation speed of 5000 rpm for 20 min. Acetone was then removed by vacuum rotary evaporation at a temperature controlled at 50 °C to obtain a stable aqueous bio-based hyperbranched modifier emulsion containing a carbamate sulfonate structure. High-speed emulsification ensured the stability of the emulsion at high solids content.

[0026] (4) Viscose fiber fabric was selected as the bio-based fabric and immersed in a finishing solution. The finishing solution was prepared by the aqueous bio-based hyperbranched modifier emulsion, magnesium chloride, and water, wherein the modifier concentration was 80 g / L, the magnesium chloride concentration was 2.5 g / L, the pH value was adjusted to 6.0 with acetic acid, and the mixture was dipped and rubbed twice, with the liquid carry-over rate controlled at 80%. The high concentration of the finishing solution can form a dense protective film on the surface and inside of the viscose fiber.

[0027] (5) The impregnated bio-based fabric is pre-dried at 100°C for 2 minutes, and then subjected to high-temperature baking at 170°C for 120 seconds. During this process, the sodium bisulfite-terminated isocyanate groups formed in step (3) undergo thermal desealing, and the generated isocyanate groups react with the hydroxyl groups on the surface of the bio-based fabric fibers to form urethane bonds. After removal, the fabric is washed with warm water, dried, and shaped to obtain the in-situ cross-linked functionalized bio-based fabric. This embodiment shows that the combination of high-concentration finishing liquid and strong shear emulsification can significantly improve the mechanical properties of viscose fibers. Example 4:

[0028] This embodiment provides a bio-based fabric conversion process that addresses the fibrillation problem of lyocell fiber fabrics by utilizing the coating effect of hyperbranched polymers to improve their surface properties. The specific steps are as follows: (1) Glycerol, itaconic acid and 4-methylbenzenesulfonic acid were mixed in a mass ratio of 9.2:12.8:0.012, nitrogen gas was introduced for protection, and the temperature was raised to 145°C for melt polycondensation reaction for 3.5 h. After the reaction was completed, vacuum dehydration treatment was carried out for 2.5 h. The vacuum degree of vacuum dehydration treatment was controlled at -0.085 MPa. The hydroxyl-terminated hyperbranched polyester was obtained by cooling.

[0029] (2) The hydroxyl-terminated hyperbranched polyester was dissolved in anhydrous acetone, and isophorone diisocyanate and dibutyltin dilaurate were added, wherein the mass ratio of isophorone diisocyanate to hydroxyl-terminated hyperbranched polyester was 1.05:1. The reaction was carried out at 52°C with constant temperature stirring for 2.2 h to obtain isocyanate-based end-capped prepolymer.

[0030] (3) An aqueous solution containing hydroxypropyltrimethylammonium chloride chitosan was added dropwise to the isocyanate-terminated prepolymer. The mass ratio of hydroxypropyltrimethylammonium chloride chitosan to isocyanate-terminated prepolymer was 0.11:1. After reacting for 1.2 h, an aqueous solution of sodium bisulfite was added. The mass ratio of sodium bisulfite to isocyanate-terminated prepolymer was 0.22:1. High-speed shear emulsification was performed at a rotation speed of 3500 rpm for 35 min. Then, acetone was removed by vacuum rotary evaporation at a temperature controlled at 42 °C to obtain a stable aqueous bio-based hyperbranched modifier emulsion containing carbamate sulfonate structure.

[0031] (4) Select Lyocell fiber fabric as bio-based fabric and immerse it in finishing solution. The finishing solution is prepared by the aqueous bio-based hyperbranched modifier emulsion, magnesium chloride and water, wherein the modifier concentration is 50 g / L, the magnesium chloride concentration is 1.8 g / L, the pH value is adjusted to 5.2 with citric acid, and the process is repeated twice and nibbled twice to control the liquid carry-over rate to 72%.

[0032] (5) The impregnated bio-based fabric was pre-dried at 92°C for 2.8 min, and then subjected to high-temperature baking at 162°C for 160 s. During this process, the sodium bisulfite-terminated isocyanate groups formed in step (3) underwent thermal desealing. The generated isocyanate groups reacted with the hydroxyl groups on the surface of the bio-based fabric fibers to form urethane bonds. After removal, the fabric was washed with warm water, dried, and shaped to obtain the in-situ cross-linked functionalized bio-based fabric. This embodiment verifies the surface modification effect of this process on easily fibrillable fibers. Example 5:

[0033] This embodiment provides a bio-based fabric conversion process to explore the finishing effect under the boundary conditions of process parameters, in order to verify the tolerance of the process. The specific steps are as follows: (1) Glycerol, itaconic acid, and 4-methylbenzenesulfonic acid were mixed in a mass ratio of 9.8:13.2:0.018, and nitrogen gas was introduced for protection. The mixture was heated to 155°C and subjected to a melt polycondensation reaction for 2.5 h. The catalyst dosage of 0.018 used in this embodiment is the optimal value after comprehensively considering the reaction efficiency and the uniformity of the product molecular weight distribution. Compared with a dosage of 0.015, the reaction time was shortened by 20% and no obvious side reactions such as gelation were observed. After the reaction was completed, vacuum dehydration was performed for 1.5 h. The vacuum degree of the vacuum dehydration was controlled at -0.095 MPa. The product was then cooled to obtain a hydroxyl-terminated hyperbranched polyester.

[0034] (2) The hydroxyl-terminated hyperbranched polyester was dissolved in anhydrous acetone, and isophorone diisocyanate and dibutyltin dilaurate were added, wherein the mass ratio of isophorone diisocyanate to hydroxyl-terminated hyperbranched polyester was 1.15:1. The reaction was carried out at 58°C with constant temperature stirring for 1.8 h to obtain isocyanate-based end-capped prepolymer.

[0035] (3) An aqueous solution containing hydroxypropyltrimethylammonium chloride chitosan was added dropwise to the isocyanate-terminated prepolymer. The mass ratio of hydroxypropyltrimethylammonium chloride chitosan to isocyanate-terminated prepolymer was 0.14:1. After reacting for 0.8 h, an aqueous solution of sodium bisulfite was added. The mass ratio of sodium bisulfite to isocyanate-terminated prepolymer was 0.28:1. High-speed shear emulsification was performed at a rotation speed of 4500 rpm for 25 min. Then, acetone was removed by vacuum rotary evaporation at a temperature of 48 °C to obtain a stable aqueous bio-based hyperbranched modifier emulsion containing carbamate sulfonate structure.

[0036] (4) Select pure cotton plain weave fabric as bio-based fabric, immerse it in finishing solution, the finishing solution is prepared by the aqueous bio-based hyperbranched modifier emulsion, magnesium chloride and water, wherein the modifier concentration is 70g / L, the magnesium chloride concentration is 2.2g / L, the pH value is adjusted to 5.8 with acetic acid, two dips and two nips, and the liquid carry-over rate is controlled to 78%.

[0037] (5) The impregnated bio-based fabric is pre-dried at 98°C for 2.2 min, and then subjected to high-temperature baking at 168°C for 140 s. During this process, the sodium bisulfite-terminated isocyanate groups formed in step (3) undergo thermal desealing, and the generated isocyanate groups react with the hydroxyl groups on the surface of the bio-based fabric fibers to form urethane bonds. After removal, the fabric is washed with warm water, dried and shaped to obtain the in-situ cross-linked functionalized bio-based fabric. This embodiment demonstrates that even under fluctuating process parameters, the present invention can still maintain a stable finishing effect.

[0038] Comparative Example 1 This comparative example provides a fabric treatment process that differs from Example 2 only in that hydroxypropyltrimethylammonium chloride chitosan is not added in step (3), while the remaining steps and parameters are consistent with Example 2. This comparative example aims to verify the antibacterial contribution of the bio-based quaternized component in the system and to evaluate its specific impact on the antibacterial rate of the final fabric by omitting this component.

[0039] Comparative Example 2 This comparative example provides a fabric treatment process that differs from Example 2 only in that, in step (3), sodium bisulfite aqueous solution is not added for end-capping; instead, the isocyanate-terminated prepolymer is directly dispersed in water. The results showed that due to the lack of hydrophilic end-capping groups and the rapid reaction of isocyanate groups with water to form polyurea precipitate, a stable aqueous bio-based hyperbranched modifier emulsion could not be formed, leading to the inability to proceed with subsequent steps. The finishing solution exhibited severe demulsification and precipitation, and stains appeared on the fabric surface. This, in turn, demonstrates the necessity of sodium bisulfite end-capping in step (3) for constructing an aqueous system.

[0040] Comparative Example 3 This comparative example provides a fabric treatment process using commercially available dimethyloldihydroxyethylene urea (2D resin) to finish the same linen fabric. The finishing solution formulation is: 60 g / L 2D resin and 15 g / L magnesium chloride. The process conditions are padding (75% liquid retention), pre-drying, and baking (165℃ × 3 min). This comparative example aims to compare the differences between traditional anti-wrinkle finishing and the bio-based conversion process of this invention in terms of formaldehyde release and strength retention, serving as a blank control of the prior art.

[0041] Comparative Example 4 This comparative example provides a bio-based fabric conversion process, which differs from Example 2 only in that the high-temperature baking treatment in step (5) is set at 120°C for 180 seconds. This comparative example aims to verify the critical effect of medium-high temperature baking on the desealing of sodium bisulfite and the formation of covalent bonds. By lowering the temperature, the completeness of the thermal desealing reaction and its impact on the final washability are examined.

[0042] To objectively evaluate the technical effects of the bio-based fabric conversion process of this invention, the fabrics prepared in Examples 1-5 and Comparative Examples 1, 3, and 4 were subjected to performance tests. The test results showed that the wrinkle recovery angle of the fabrics in Examples 1-5 was significantly improved to 248°-272°, and the tensile strength retention rate remained above 85%. Comparing Example 2 with Comparative Example 3 (traditional 2D resin), it can be seen that although the 2D resin can provide a 260° recovery angle, its strength retention rate is only 65.0%, accompanied by a formaldehyde release of 85 ppm. This indicates that the flexible cross-linked network constructed by the hyperbranched polymer in this invention, while imparting excellent wrinkle resistance to the fabric, disperses stress concentration between fibers through its unique spherical three-dimensional structure, effectively avoiding cellulose hydrolysis and brittleness caused by traditional acidic catalysts, and achieving a formaldehyde-free, high-strength, green finishing process.

[0043] Furthermore, comparing Example 2 and Comparative Example 4, it can be seen that when the baking temperature decreased from 165°C to 120°C, the wrinkle recovery angle dropped sharply from 252° to 165°, and the antibacterial rate after 50 washes also decreased from 96.1% to 25.0%. This confirms that the thermal deblocking-addition reaction mechanism is the core framework for achieving durable finishing. At 120°C, the sodium bisulfite-terminated carbamate sulfonate failed to reach the deblocking activation energy threshold and could not release the highly active isocyanate groups. Comparing Example 2 and Comparative Example 1, it can be seen that the sample lacking hydroxypropyltrimethylammonium chloride chitosan had an antibacterial rate of only 12.5%, close to the original level, indicating that the hyperbranched polyester framework itself does not have bactericidal ability and needs to be used in conjunction with functional groups. Examples 1-5 cover a variety of cellulose fibers such as cotton, linen, viscose, and lyocell. In particular, for linen fabrics, the hand feel evaluation improved from 3.0 to 4.0, effectively improving the rough and itchy surface characteristics of linen fibers.

[0044] Table 1: Performance Test Data of Finished Fabric

[0045] As shown in Table 1, the wrinkle recovery angles of the fabrics in Examples 1-5 were significantly improved to 248°-272°, and the tensile strength retention rate remained above 85%. Comparing Example 2 and Comparative Example 3, it can be seen that while traditional 2D resin can provide a 260° recovery angle, its strength retention rate is only 65.0%, accompanied by a formaldehyde release of 85 ppm. This indicates that the flexible cross-linked network constructed by the hyperbranched polymer in this invention, while imparting excellent wrinkle resistance to the fabric, disperses stress concentration between fibers through its unique spherical three-dimensional structure, effectively avoiding cellulose hydrolysis and brittleness caused by traditional acid catalysts, thus achieving a formaldehyde-free, high-strength, green finishing process.

[0046] Comparing Example 2 and Comparative Example 4, it can be seen that when the baking temperature drops from 165°C to 120°C, the wrinkle recovery angle drops sharply from 252° to 165°, and the antibacterial rate after 50 washes also drops from 96.1% to 25.0%. This confirms that the above-mentioned thermal deblocking-addition reaction mechanism is the core framework for achieving durable finishing. At 120°C, the sodium bisulfite-terminated carbamate sulfonate fails to reach the deblocking activation energy threshold and cannot release highly active isocyanate groups. As a result, the modifier only adheres to the fiber surface through physical adsorption and cannot form covalent bonds for anchoring. Therefore, a large amount of it falls off during the washing process, resulting in a loss of functionality.

[0047] Comparing Example 2 with Comparative Example 1, it can be seen that the sample lacking hydroxypropyltrimethylammonium chloride chitosan has an antibacterial rate of only 12.5%, which is close to the original level. This indicates that the hyperbranched polyester skeleton in the system of the present invention does not have bactericidal ability itself. Its main function is to act as a carrier to firmly graft chitosan derivatives with cationic bactericidal activity onto the fiber surface through isocyanate groups, thereby giving the fabric a durable antibacterial protective layer.

[0048] Examples 1-5 covered various cellulose fibers such as cotton, linen, viscose, and lyocell, and all achieved ideal finishing effects. In particular, for linen fabrics, the hand feel rating improved from 3.0 to 4.0, which was better than the stiff hand feel of Comparative Example 3 (3.0). This is attributed to the large number of cavity structures and flexible segments at the ends of the hyperbranched polymer, which formed a nanoscale soft film on the fiber surface, effectively improving the rough and itchy surface characteristics of linen fibers.

[0049] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A bio-based fabric conversion process characterized by, The method comprises the following steps: (1) mixing glycerol, itaconic acid and 4-methylbenzenesulfonic acid according to a mass ratio of 9.0-10.0:12.5-13.5:0.01-0.02, introducing nitrogen protection, heating to 140-160 ℃, carrying out melt polycondensation reaction for 2-4 h, carrying out vacuum dehydration treatment for 1-3 h, and cooling to obtain a hydroxyl-terminated hyperbranched polyester; (2) dissolving the hydroxyl-terminated hyperbranched polyester in anhydrous acetone, adding isophorone diisocyanate and dibutyltin dilaurate, wherein the mass ratio of isophorone diisocyanate to the hydroxyl-terminated hyperbranched polyester is 1.0-1.2:1, stirring at a constant temperature of 50-60 ℃ for 1.5-2.5 h, and preparing an isocyanate group-terminated prepolymer; (3) adding an aqueous solution of hydroxypropyltrimethylammonium chloride chitosan dissolved in water to the isocyanate group-terminated prepolymer, wherein the mass ratio of the hydroxypropyltrimethylammonium chloride chitosan to the isocyanate group-terminated prepolymer is 0.1-0.15:1, reacting for 0.5-1.5 h, adding an aqueous sodium bisulfite solution, wherein the mass ratio of the sodium bisulfite to the isocyanate group-terminated prepolymer is 0.2-0.3:1, and carrying out high-speed shearing emulsification for 20-40 min, and then removing acetone by rotary evaporation under reduced pressure to obtain a stable aqueous bio-based hyperbranched modifier emulsion containing a carbamic acid sulfonic acid salt structure; (4) immersing a bio-based fabric in a finishing liquid prepared from the aqueous bio-based hyperbranched modifier emulsion, magnesium chloride and water, wherein the concentration of the modifier is 40-80 g / L, the concentration of the magnesium chloride is 1.5-2.5 g / L, and acetic acid or citric acid is used to adjust the pH value to 5.0-6.0, and double immersion and double padding are carried out to control the liquid retention rate to be 70%-80%; (5) pre-drying the bio-based fabric after immersion and padding at 90-100 ℃ for 2-3 min, then carrying out high-temperature baking treatment at 160-170 ℃ for 120-180 s, washing with warm water after taking out, and drying and setting to obtain an in-situ cross-linked functional bio-based fabric.

2. A bio-based fabric conversion process according to claim 1, characterized in that, The vacuum degree of the vacuum dewatering treatment of step (1) is controlled to be to .

3. The bio-based fabric conversion process of claim 1, wherein, The rotation speed of the high-speed shearing emulsification in step (3) is 3000-5000 rpm.

4. The bio-based fabric conversion process of claim 1, wherein, The temperature of the rotary evaporation under reduced pressure in step (3) is controlled to be 40-50 ℃.

5. The bio-based fabric conversion process of claim 1, wherein, The bio-based fabric in step (4) is one of pure cotton plain fabric, ramie fabric, viscose fabric or lyocell fabric.

6. The bio-based fabric conversion process of claim 1, wherein, During the high-temperature baking treatment in step (5), the carbamic acid sulfonic acid salt structure terminated by sodium bisulfite in the aqueous bio-based hyperbranched modifier emulsion prepared in step (3) is pyrolyzed to regenerate isocyanate groups, and the isocyanate groups adduct with hydroxyl groups on the surface of the bio-based fabric to generate carbamate bonds.

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